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Shridas P, Ji A, Trumbauer AC, Noffsinger VP, Meredith LW, de Beer FC, Mullick AE, Webb NR, Karounos DG, Tannock LR. Antisense oligonucleotide targeting hepatic Serum Amyloid A limits the progression of angiotensin II-induced abdominal aortic aneurysm formation. Atherosclerosis 2024; 391:117492. [PMID: 38461759 PMCID: PMC11006562 DOI: 10.1016/j.atherosclerosis.2024.117492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/07/2024] [Accepted: 02/23/2024] [Indexed: 03/12/2024]
Abstract
BACKGROUND AND AIMS Obesity increases the risk for abdominal aortic aneurysms (AAA) in humans and enhances angiotensin II (AngII)-induced AAA formation in C57BL/6 mice. We reported that deficiency of Serum Amyloid A (SAA) significantly reduces AngII-induced inflammation and AAA in both hyperlipidemic apoE-deficient and obese C57BL/6 mice. The aim of this study is to investigate whether SAA plays a role in the progression of early AAA in obese C57BL/6 mice. METHODS Male C57BL/6J mice were fed a high-fat diet (60% kcal as fat) throughout the study. After 4 months of diet, the mice were infused with AngII until the end of the study. Mice with at least a 25% increase in the luminal diameter of the abdominal aorta after 4 weeks of AngII infusion were stratified into 2 groups. The first group received a control antisense oligonucleotide (Ctr ASO), and the second group received ASO that suppresses SAA (SAA-ASO) until the end of the study. RESULTS Plasma SAA levels were significantly reduced by the SAA ASO treatment. While mice that received the control ASO had continued aortic dilation throughout the AngII infusion periods, the mice that received SAA-ASO had a significant reduction in the progression of aortic dilation, which was associated with significant reductions in matrix metalloprotease activities, decreased macrophage infiltration and decreased elastin breaks in the abdominal aortas. CONCLUSIONS We demonstrate for the first time that suppression of SAA protects obese C57BL/6 mice from the progression of AngII-induced AAA. Suppression of SAA may be a therapeutic approach to limit AAA progression.
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Affiliation(s)
- Preetha Shridas
- Department of Internal Medicine, University of Kentucky, Lexington, 40536, Kentucky, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA.
| | - Ailing Ji
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
| | - Andrea C Trumbauer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
| | - Victoria P Noffsinger
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
| | - Luke W Meredith
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
| | - Frederick C de Beer
- Department of Internal Medicine, University of Kentucky, Lexington, 40536, Kentucky, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
| | | | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA; Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, 40536, Kentucky, USA
| | - Dennis G Karounos
- Department of Internal Medicine, University of Kentucky, Lexington, 40536, Kentucky, USA; Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, 40536, Kentucky, USA; Department of Veterans Affairs, Lexington, 40536, Kentucky, USA
| | - Lisa R Tannock
- Department of Internal Medicine, University of Kentucky, Lexington, 40536, Kentucky, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, 40536, Kentucky, USA
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Ji A, Trumbauer AC, Noffsinger VP, Meredith LW, Dong B, Wang Q, Guo L, Li X, De Beer FC, Webb NR, Tannock LR, Starr ME, Waters CM, Shridas P. Deficiency of Acute-Phase Serum Amyloid A Exacerbates Sepsis-Induced Mortality and Lung Injury in Mice. Int J Mol Sci 2023; 24:17501. [PMID: 38139330 PMCID: PMC10744229 DOI: 10.3390/ijms242417501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/11/2023] [Accepted: 12/13/2023] [Indexed: 12/24/2023] Open
Abstract
Serum amyloid A (SAA) is a family of proteins, the plasma levels of which may increase >1000-fold in acute inflammatory states. We investigated the role of SAA in sepsis using mice deficient in all three acute-phase SAA isoforms (SAA-TKO). SAA deficiency significantly increased mortality rates in the three experimental sepsis mouse models: cecal ligation and puncture (CLP), cecal slurry (CS) injection, and lipopolysaccharide (LPS) treatments. SAA-TKO mice had exacerbated lung pathology compared to wild-type (WT) mice after CLP. A bulk RNA sequencing performed on lung tissues excised 24 h after CLP indicated significant enrichment in the expression of genes associated with chemokine production, chemokine and cytokine-mediated signaling, neutrophil chemotaxis, and neutrophil migration in SAA-TKO compared to WT mice. Consistently, myeloperoxidase activity and neutrophil counts were significantly increased in the lungs of septic SAA-TKO mice compared to WT mice. The in vitro treatment of HL-60, neutrophil-like cells, with SAA or SAA bound to a high-density lipoprotein (SAA-HDL), significantly decreased cellular transmigration through laminin-coated membranes compared to untreated cells. Thus, SAA potentially prevents neutrophil transmigration into injured lungs, thus reducing exacerbated tissue injury and mortality. In conclusion, we demonstrate for the first time that endogenous SAA plays a protective role in sepsis, including ameliorating lung injury.
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Affiliation(s)
- Ailing Ji
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Andrea C. Trumbauer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Victoria P. Noffsinger
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Luke W. Meredith
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Brittany Dong
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; (B.D.); (C.M.W.)
| | - Qian Wang
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Ling Guo
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
| | - Xiangan Li
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; (B.D.); (C.M.W.)
- Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA;
| | - Frederick C. De Beer
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA;
| | - Nancy R. Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
- Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA;
| | - Lisa R. Tannock
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA;
| | - Marlene E. Starr
- Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA;
- Department of Surgery, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Christopher M. Waters
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA; (B.D.); (C.M.W.)
| | - Preetha Shridas
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536, USA; (A.J.); (A.C.T.); (V.P.N.); (L.W.M.); (Q.W.); (L.G.); (X.L.); (N.R.W.); (L.R.T.)
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA;
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Shridas P, Ji A, Trumbauer AC, Noffsinger VP, Meredith LW, de Beer FC, Mullick AE, Webb NR, Karounos DG, Tannock LR. Antisense Oligonucleotide Targeting Hepatic Serum Amyloid A Limits the Progression of Angiotensin II-Induced Abdominal Aortic Aneurysm Formation. bioRxiv 2023:2023.08.22.554377. [PMID: 37662383 PMCID: PMC10473661 DOI: 10.1101/2023.08.22.554377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
OBJECTIVE Obesity increases the risk for abdominal aortic aneurysms (AAA) in humans and enhances angiotensin II (AngII)-induced AAA formation in C57BL/6 mice. Obesity is also associated with increases in serum amyloid A (SAA). We previously reported that deficiency of SAA significantly reduces AngII-induced inflammation and AAA in both hyperlipidemic apoE-deficient and obese C57BL/6 mice. In this study, we investigated whether SAA plays a role in the progression of early AAA in obese C57BL/6 mice. APPROACH AND RESULTS Male C57BL/6J mice were fed a high-fat diet (60% kcal as fat) throughout the study. After 4 months of diet, the mice were infused with angiotensin II (AngII) until the end of the study. Mice with at least a 25% increase in the luminal diameter of the abdominal aorta after 4 weeks of AngII infusion were stratified into 2 groups. The first group received a control antisense oligonucleotide (Ctr ASO), and the second group received ASO that suppresses SAA (SAA-ASO) until the end of the study. Plasma SAA levels were significantly reduced by the SAA ASO treatment. While mice that received the control ASO had continued aortic dilation throughout the AngII infusion periods, the mice that received SAA-ASO had a significant reduction in the progression of aortic dilation, which was associated with significant reductions in matrix metalloprotease activities, decreased macrophage infiltration and decreased elastin breaks in the abdominal aortas. CONCLUSION We demonstrate for the first time that suppression of SAA protects obese C57BL/6 mice from the progression of AngII-induced AAA. Suppression of SAA may be a therapeutic approach to limit AAA progression.
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Ji A, Trumbauer AC, Noffsinger VP, de Beer FC, Webb NR, Tannock LR, Shridas P. Serum Amyloid A augments the atherogenic effects of Cholesteryl Ester Transfer Protein. J Lipid Res 2023; 64:100365. [PMID: 37004910 PMCID: PMC10165456 DOI: 10.1016/j.jlr.2023.100365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Serum Amyloid A (SAA) is predictive of cardiovascular disease (CVD) in humans and causes atherosclerosis in mice. SAA has many pro-atherogenic effects in vitro. However, HDL, the major carrier of SAA in the circulation, masks these effects. The remodeling of HDL by CETP liberates SAA restoring its pro-inflammatory activity. Here, we investigated whether deficiency of SAA suppresses the previously described pro-atherogenic effect of Cholesteryl Ester Transfer Protein (CETP). ApoE-/- mice and apoE-/- mice deficient in the three acute-phase isoforms of SAA (SAA1.1, SAA2.1, and SAA3; "apoE-/- SAA-TKO") with and without AAV-mediated expression of CETP were studied. There was no effect of CETP expression or SAA genotype on plasma lipids or inflammatory markers. Atherosclerotic lesion area in the aortic arch of apoE-/- mice was 5.9 ± 1.2%, CETP expression significantly increased atherosclerosis in apoE-/- mice (13.1 ± 2.2%). However, atherosclerotic lesion area in the aortic arch of apoE-/- SAA-TKO mice (5.1±1.1%) was not significantly increased by CETP expression (6.2 ± 0.9%). The increased atherosclerosis in apoE-/- mice expressing CETP was associated with markedly increased SAA immunostaining in aortic root sections. Thus, SAA augments the atherogenic effects of CETP, which suggests that inhibiting CETP may be of particular benefit in patients with high SAA.
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Affiliation(s)
- Ailing Ji
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Andrea C Trumbauer
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Victoria P Noffsinger
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Frederick C de Beer
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, USA
| | - Nancy R Webb
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA; Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Lisa R Tannock
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, USA; Lexington Veterans Affairs Medical Center, Lexington, KY, USA
| | - Preetha Shridas
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, USA.
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Shridas P, Ji A, Trumbauer AC, Noffsinger VP, Leung SW, Dugan AJ, Thatcher SE, Cassis LA, de Beer FC, Webb NR, Tannock LR. Adipocyte-Derived Serum Amyloid A Promotes Angiotensin II-Induced Abdominal Aortic Aneurysms in Obese C57BL/6J Mice. Arterioscler Thromb Vasc Biol 2022; 42:632-643. [PMID: 35344382 PMCID: PMC9050948 DOI: 10.1161/atvbaha.121.317225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Obesity increases the risk for human abdominal aortic aneurysms (AAAs) and enhances Ang II (angiotensin II)-induced AAA formation in C57BL/6J mice. Obesity is also associated with increases in perivascular fat that expresses proinflammatory markers including SAA (serum amyloid A). We previously reported that deficiency of SAA significantly reduces Ang II-induced inflammation and AAA in hyperlipidemic apoE-deficient mice. In this study. we investigated whether adipose tissue-derived SAA plays a role in Ang II-induced AAA in obese C57BL/6J mice. METHODS The development of AAA was compared between male C57BL/6J mice (wild type), C57BL/6J mice lacking SAA1.1, SAA2.1, and SAA3 (TKO); and TKO mice harboring a doxycycline-inducible, adipocyte-specific SAA1.1 transgene (TKO-Tgfat; SAA expressed only in fat). All mice were fed an obesogenic diet and doxycycline to induce SAA transgene expression and infused with Ang II to induce AAA. RESULTS In response to Ang II infusion, SAA expression was significantly increased in perivascular fat of obese C57BL/6J mice. Maximal luminal diameters of the abdominal aorta were determined by ultrasound before and after Ang II infusion, which indicated a significant increase in aortic luminal diameters in wild type and TKO-TGfat mice but not in TKO mice. Adipocyte-specific SAA expression was associated with MMP (matrix metalloproteinase) activity and macrophage infiltration in abdominal aortas of Ang II-infused obese mice. CONCLUSIONS We demonstrate for the first time that SAA deficiency protects obese C57BL/6J mice from Ang II-induced AAA. SAA expression only in adipocytes is sufficient to cause AAA in obese mice infused with Ang II.
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Affiliation(s)
- Preetha Shridas
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
- Barnstable Brown Diabetes Center (P.S., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
| | - Ailing Ji
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
| | - Andrea C Trumbauer
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
| | - Victoria P Noffsinger
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
| | - Steve W Leung
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
| | - Adam J Dugan
- Biostatistics (A.J.D.), University of Kentucky, Lexington
| | - Sean E Thatcher
- Department of Pharmacology, Temple University, Philadelphia, PA (S.E.T.)
| | - Lisa A Cassis
- Pharmacology and Nutritional Sciences (L.A.C., N.R.W.), University of Kentucky, Lexington
| | - Frederick C de Beer
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
- Barnstable Brown Diabetes Center (P.S., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
| | - Nancy R Webb
- Pharmacology and Nutritional Sciences (L.A.C., N.R.W.), University of Kentucky, Lexington
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
- Barnstable Brown Diabetes Center (P.S., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
| | - Lisa R Tannock
- Departments of Internal Medicine (P.S., A.J., V.P.N., S.W.L., F.C.d.B., L.R.T.), University of Kentucky, Lexington
- Saha Cardiovascular Research Center (P.S., A.C.T., S.W.L., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
- Barnstable Brown Diabetes Center (P.S., F.C.d.B., N.R.W., L.R.T.), University of Kentucky, Lexington
- Department of Veterans Affairs, Lexington, KY (L.R.T.)
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Webb NR. Correction to: High-Density Lipoproteins and Serum Amyloid A (SAA). Curr Atheroscler Rep 2022; 24:73. [PMID: 35132572 DOI: 10.1007/s11883-022-01005-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Nancy R Webb
- Department of Pharmacology and Nutritional Sciences, Saha Cardiovascular Research Center, and Barnstable Brown Diabetes Center, University of Kentucky, 553 Wethington Building, 900 South Limestone, Lexington, KY, 40536-0200, USA.
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Nordness MJ, Baxter BT, Matsumura J, Terrin M, Zhang K, Ye F, Webb NR, Dalman RL, Curci JA. The effect of diabetes on abdominal aortic aneurysm growth over 2 years. J Vasc Surg 2021; 75:1211-1222.e1. [PMID: 34695550 DOI: 10.1016/j.jvs.2021.10.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/14/2021] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Abdominal aortic aneurysm (AAA) is a common progressive disease and a significant cause of morbidity and mortality. Prior investigations have shown that diabetes mellitus (DM) may be relatively protective of AAA incidence and growth. The Non-invasive Treatment of Aortic Aneurysm Clinical Trial (N-TA3CT) is a contemporary study of small AAA growth that provides a unique opportunity to validate and explore the effect of DM on AAA. Confirming the effect of DM on AAA growth in this study may present opportunities to explore for clues to potential biologic mechanisms as well as inform current patient management. METHODS This is a secondary analysis examining the association of diabetes and aneurysm growth within N-TA3CT: a placebo-controlled multicenter trial of doxycycline in 261 patients with AAA maximum transverse diameters (MTDs) between 3.5 and 5 cm. The primary outcome is the change in the MTD from baseline as determined by computed tomography (CT) scans obtained during the trial. Secondary outcome is the growth pattern of the AAA. Baseline characteristics and growth patterns were assessed with t tests (continuous) or χ2 tests (categorical). Unadjusted and adjusted longitudinal analyses were performed with a repeated measures linear mixed model to compare AAA growth rates between patients with and without diabetes. RESULTS Of 261 patients, 250 subjects had sufficient imaging and were included in this study. There were 56 patients (22.4%) with diabetes and 194 (77.6%) without. Diabetes was associated with higher body mass index and increased rates of hypercholesterolemia and coronary artery disease (P < .05). Diabetes was also associated with increased frequency of treatment for atherosclerosis and hypertension including treatment with statin, angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, anti-platelet, and diuretic therapy (P < .05). Baseline MTD was not significantly different between those with (4.32 cm) and without DM (4.30 cm). Median growth rate for patients with diabetes was 0.12 cm/y (interquartile range, 0.07-0.22 cm/y) and 0.19 cm/y (interquartile range, 0.12-0.27 cm/y) in patients without DM, which was significantly different on unadjusted analysis (P < .0001). Diabetes remained significantly associated with AAA growth after adjustment for other relevant clinical factors (coef, -0.057; P < .0001). CONCLUSIONS Patients with diabetes have more than a 35% reduction in the median growth rates of AAA despite more severe concomitant vascular comorbidities and similar initial sizes of aneurysms. This effect persists and remains robust after adjusted analysis; and slower growth rates may delay the time to reach repair threshold. Rapid growth (>0.5 cm/y) is infrequent in patients with DM.
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Affiliation(s)
- Matthew J Nordness
- Department of Vascular Surgery, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tenn
| | - B Timothy Baxter
- Division of Vascular Surgery, Department of Surgery, University of Nebraska Medical Center, Omaha, Neb
| | - Jon Matsumura
- Department of Surgery, Medicine and Public Health, University of Wisconsin, Madison, Wisc
| | - Michael Terrin
- Division of Gerontology, Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Md
| | - Kevin Zhang
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, Tenn
| | - Fei Ye
- Department of Biostatistics, Vanderbilt University School of Medicine, Nashville, Tenn
| | - Nancy R Webb
- Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, Ky
| | - Ronald L Dalman
- Department of Surgery-Vascular Surgery, Stanford University School of Medicine, Stanford, Calif
| | - John A Curci
- Department of Vascular Surgery, Vanderbilt University Medical Center and Vanderbilt University School of Medicine, Nashville, Tenn.
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Trumbauer A, Noffsinger V, Ji A, DEBEER FC, Dugan A, Mullick AE, Webb NR, Shridas P, Tannock LR. Abstract P101: Suppression Of Serum Amyloid A Limits Progression Of Obesity Associated Abdominal Aortic Aneurysms. Arterioscler Thromb Vasc Biol 2021. [DOI: 10.1161/atvb.41.suppl_1.p101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Obesity increases the risk for abdominal aortic aneurysms (AAA) in humans, and enhances angiotensin II (AngII)-induced AAA formation in C57BL/6 mice. Obesity is also associated with increases in serum amyloid A (SAA). We previously reported that deficiency of SAA significantly reduces AngII-induced inflammation and AAA in apoE-deficient mice. In this study we investigated whether SAA plays a role in progression of an established AAA in obese C57BL/6 mice.
Approach and Results:
Male C57BL/6 mice were fed a high fat diet (60% kcal as fat) throughout the study. After 4 months of diet the mice were infused with angiotensin II (AngII) at 1000ng/kg/min until the end of the study. Ultrasound (US) was performed in all mice before and after 28 days of AngII infusion, and mice that had at least a 25% increase in the luminal diameter of the abdominal aorta were stratified by luminal diameter into 3 groups. Group 1 was killed to establish baseline AAA. Groups 2 and 3 continued to receive AngII for a further 8 weeks along with an antisense oligonucleotide (ASO) that suppresses all 3 acute phase SAA isoforms (SAA-ASO), or a control ASO (5 mg/kg/wk). US was repeated at study end to assess AAA progression. Plasma SAA at the end of the experiment was 89.2±83.2 mg/L in the control ASO group, and 18.6±0.7 mg/L in the SAA-ASO group (mean±SD , p=0.008). There was no impact of SAA suppression on body weight, body fat, or blood pressure. After the first 4 weeks of AngII infusion, the average luminal diameter in all mice was 1.81±0.40 mm (mean±SD). Mice that received the control ASO had continued aortic dilation (average luminal aortic diameter 2.06±0.42 mm), whereas the mice that received the SAA-ASO had a significant reduction in progression of aortic dilation (average luminal diameter 1.64±0.43 mm, p=0.0015 for interaction between time and group).
Conclusions:
We demonstrate for the first time that suppression of SAA protects obese C57BL/6 mice from progression of AngII-induced AAA. Suppression of SAA may be a therapeutic approach to limit AAA progression.
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Abstract
PURPOSE OF REVIEW Serum amyloid A (SAA) is a highly sensitive acute phase reactant that has been linked to a number of chronic inflammatory diseases. During a systemic inflammatory response, liver-derived SAA is primarily found on high-density lipoprotein (HDL). The purpose of this review is to discuss recent literature addressing the pathophysiological functions of SAA and the significance of its association with HDL. RECENT FINDINGS Studies in gene-targeted mice establish that SAA contributes to atherosclerosis and some metastatic cancers. Accumulating evidence indicates that the lipidation state of SAA profoundly affects its bioactivities, with lipid-poor, but not HDL-associated, SAA capable of inducing inflammatory responses in vitro and in vivo. Factors that modulate the equilibrium between lipid-free and HDL-associated SAA have been identified. HDL may serve to limit SAA's bioactivities in vivo. Understanding the factors leading to the release of systemic SAA from HDL may provide insights into chronic disease mechanisms.
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Affiliation(s)
- Nancy R Webb
- Department of Pharmacology and Nutritional Sciences, Saha Cardiovascular Research Center, and Barnstable Brown Diabetes Center, University of Kentucky, 553 Wethington Building, 900 South Limestone, Lexington, KY, 40536-0200, USA.
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10
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Shen YH, LeMaire SA, Webb NR, Cassis LA, Daugherty A, Lu HS. Aortic Aneurysms and Dissections Series: Part II: Dynamic Signaling Responses in Aortic Aneurysms and Dissections. Arterioscler Thromb Vasc Biol 2020; 40:e78-e86. [PMID: 32208998 DOI: 10.1161/atvbaha.120.313804] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Aortic structure and function are controlled by the coordinated actions of different aortic cells and the extracellular matrix. Several pathways have been identified that control the aortic wall in a cell-type-specific manner and play diverse roles in various phases of aortic injury, repair, and remodeling. This complexity of signaling in the aortic wall poses challenges to the development of therapeutic strategies for treating aortic aneurysms and dissections. Here, in part II of this Recent Highlights series on aortic aneurysms and dissections, we will summarize recent studies published in Arteriosclerosis, Thrombosis, and Vascular Biology that have contributed to our knowledge of the signaling pathway-related mechanisms of aortic aneurysms and dissections.
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Affiliation(s)
- Ying H Shen
- From the Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX (Y.H.S., S.A.L.).,Department of Cardiovascular Surgery, Texas Heart Institute, Houston (Y.H.S., S.A.L.)
| | - Scott A LeMaire
- From the Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX (Y.H.S., S.A.L.).,Department of Cardiovascular Surgery, Texas Heart Institute, Houston (Y.H.S., S.A.L.)
| | - Nancy R Webb
- Department of Pharmacology and Nutritional Sciences (N.R.W., L.A.C.), University of Kentucky, Lexington
| | - Lisa A Cassis
- Department of Pharmacology and Nutritional Sciences (N.R.W., L.A.C.), University of Kentucky, Lexington
| | - Alan Daugherty
- Department of Physiology and Saha Cardiovascular Research Center (A.D., H.S.L.), University of Kentucky, Lexington
| | - Hong S Lu
- Department of Physiology and Saha Cardiovascular Research Center (A.D., H.S.L.), University of Kentucky, Lexington
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11
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Barnett JV, Beckman JA, Bonaca MP, Carnethon MR, Cassis LA, Creager MA, Daugherty A, Feinberg MW, Freiberg MS, Goodney PP, Greenland P, Leeuwenburgh C, LeMaire SA, McDermott MM, Sabatine MS, Shen YH, Wasserman DH, Webb NR, Wells QS. American Heart Association Vascular Disease Strategically Focused Research Network. Arterioscler Thromb Vasc Biol 2020; 40:e47-e54. [PMID: 31969016 PMCID: PMC7047580 DOI: 10.1161/atvbaha.120.313967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Joey V. Barnett
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
- Department of Pharmacology, Vanderbilt University, Nashville, TN
| | - Joshua A. Beckman
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Marc P. Bonaca
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Mercedes R. Carnethon
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University Chicago IL
| | - Lisa A. Cassis
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Mark A. Creager
- Dartmouth-Hitchcock Heart and Vascular Center, The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Lebanon, NH
| | - Alan Daugherty
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
- Department of Physiology, University of Kentucky, Lexington, KY
| | - Mark W. Feinberg
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Matthew S. Freiberg
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Philip P. Goodney
- Dartmouth-Hitchcock Heart and Vascular Center, The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Lebanon, NH
- Section of Vascular Surgery, The Dartmouth Institute for Health Policy and Clinical Practice, Geisel School of Medicine at Dartmouth, Lebanon, NH
- VA Quality Scholars Program, VA Outcomes Group, Veterans Health Association, White River Junction, VT
| | - Philip Greenland
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University Chicago IL
| | | | - Scott A. LeMaire
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX
- Department of Cardiovascular Surgery, Texas Heart Institute, Houston TX
| | - Mary M. McDermott
- Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University Chicago IL
- Department of Medicine, Feinberg School of Medicine, Northwestern University Chicago IL
| | - Marc S. Sabatine
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA
| | - Ying H. Shen
- Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX
- Department of Cardiovascular Surgery, Texas Heart Institute, Houston TX
| | - David H. Wasserman
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Nancy R. Webb
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | - Quinn S. Wells
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University, Nashville, TN
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12
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Abstract
The aortic wall is composed of highly dynamic cell populations and extracellular matrix. In response to changes in the biomechanical environment, aortic cells and extracellular matrix modulate their structure and functions to increase aortic wall strength and meet the hemodynamic demand. Compromise in the structural and functional integrity of aortic components leads to aortic degeneration, biomechanical failure, and the development of aortic aneurysms and dissections (AAD). A better understanding of the molecular pathogenesis of AAD will facilitate the development of effective medications to treat these conditions. Here, we summarize recent findings on AAD published in ATVB. In this issue, we focus on the dynamics of aortic cells and extracellular matrix in AAD; in the next issue, we will focus on the role of signaling pathways in AAD.
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Affiliation(s)
- Ying H Shen
- From the Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX (Y.H.S., S.A.L.).,Department of Cardiovascular Surgery, Texas Heart Institute, Houston (Y.H.S., S.A.L.)
| | - Scott A LeMaire
- From the Division of Cardiothoracic Surgery, Michael E. DeBakey Department of Surgery, Baylor College of Medicine, Houston, TX (Y.H.S., S.A.L.).,Department of Cardiovascular Surgery, Texas Heart Institute, Houston (Y.H.S., S.A.L.)
| | - Nancy R Webb
- Department of Pharmacology and Nutritional Sciences (N.R.W., L.A.C.), University of Kentucky, Lexington
| | - Lisa A Cassis
- Department of Pharmacology and Nutritional Sciences (N.R.W., L.A.C.), University of Kentucky, Lexington
| | - Alan Daugherty
- Department of Physiology and Saha Cardiovascular Research Center (A.D., H.S.L.), University of Kentucky, Lexington
| | - Hong S Lu
- Department of Physiology and Saha Cardiovascular Research Center (A.D., H.S.L.), University of Kentucky, Lexington
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13
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Ji A, Wang X, Noffsinger VP, Jennings D, de Beer MC, de Beer FC, Tannock LR, Webb NR. Serum amyloid A is not incorporated into HDL during HDL biogenesis. J Lipid Res 2020; 61:328-337. [PMID: 31915139 DOI: 10.1194/jlr.ra119000329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 01/06/2020] [Indexed: 11/20/2022] Open
Abstract
Liver-derived serum amyloid A (SAA) is present in plasma where it is mainly associated with HDL and from which it is cleared more rapidly than are the other major HDL-associated apolipoproteins. Although evidence suggests that lipid-free and HDL-associated forms of SAA have different activities, the pathways by which SAA associates and disassociates with HDL are poorly understood. In this study, we investigated SAA lipidation by hepatocytes and how this lipidation relates to the formation of nascent HDL particles. We also examined hepatocyte-mediated clearance of lipid-free and HDL-associated SAA. We prepared hepatocytes from mice injected with lipopolysaccharide or an SAA-expressing adenoviral vector. Alternatively, we incubated primary hepatocytes from SAA-deficient mice with purified SAA. We analyzed conditioned media to determine the lipidation status of endogenously produced and exogenously added SAA. Examining the migration of lipidated species, we found that SAA is lipidated and forms nascent particles that are distinct from apoA-I-containing particles and that apoA-I lipidation is unaltered when SAA is overexpressed or added to the cells, indicating that SAA is not incorporated into apoA-I-containing HDL during HDL biogenesis. Like apoA-I formation, generation of SAA-containing particles was dependent on ABCA1, but not on scavenger receptor class B type I. Hepatocytes degraded significantly more SAA than apoA-I. Taken together, our results indicate that SAA's lipidation and metabolism by the liver is independent of apoA-I and that SAA is not incorporated into HDL during HDL biogenesis.
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Affiliation(s)
- Ailing Ji
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | - Xuebing Wang
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | | | - Drew Jennings
- Departments of Agricultural and Medical Biotechnology, University of Kentucky, Lexington, KY
| | - Maria C de Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Physiology, University of Kentucky, Lexington, KY
| | - Frederick C de Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Internal Medicine, University of Kentucky, Lexington, KY
| | - Lisa R Tannock
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Internal Medicine, University of Kentucky, Lexington, KY
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY .,Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
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14
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Lee JW, Stone ML, Porrett PM, Thomas SK, Komar CA, Li JH, Delman D, Graham K, Gladney WL, Hua X, Black TA, Chien AL, Majmundar KS, Thompson JC, Yee SS, O'Hara MH, Aggarwal C, Xin D, Shaked A, Gao M, Liu D, Borad MJ, Ramanathan RK, Carpenter EL, Ji A, de Beer MC, de Beer FC, Webb NR, Beatty GL. Hepatocytes direct the formation of a pro-metastatic niche in the liver. Nature 2019; 567:249-252. [PMID: 30842658 PMCID: PMC6430113 DOI: 10.1038/s41586-019-1004-y] [Citation(s) in RCA: 224] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 02/12/2019] [Indexed: 12/25/2022]
Abstract
The liver is the most common site of metastatic disease1. Although this metastatic tropism may reflect the mechanical trapping of circulating tumour cells, liver metastasis is also dependent, at least in part, on the formation of a 'pro-metastatic' niche that supports the spread of tumour cells to the liver2,3. The mechanisms that direct the formation of this niche are poorly understood. Here we show that hepatocytes coordinate myeloid cell accumulation and fibrosis within the liver and, in doing so, increase the susceptibility of the liver to metastatic seeding and outgrowth. During early pancreatic tumorigenesis in mice, hepatocytes show activation of signal transducer and activator of transcription 3 (STAT3) signalling and increased production of serum amyloid A1 and A2 (referred to collectively as SAA). Overexpression of SAA by hepatocytes also occurs in patients with pancreatic and colorectal cancers that have metastasized to the liver, and many patients with locally advanced and metastatic disease show increases in circulating SAA. Activation of STAT3 in hepatocytes and the subsequent production of SAA depend on the release of interleukin 6 (IL-6) into the circulation by non-malignant cells. Genetic ablation or blockade of components of IL-6-STAT3-SAA signalling prevents the establishment of a pro-metastatic niche and inhibits liver metastasis. Our data identify an intercellular network underpinned by hepatocytes that forms the basis of a pro-metastatic niche in the liver, and identify new therapeutic targets.
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Affiliation(s)
- Jae W Lee
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Meredith L Stone
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Paige M Porrett
- Division of Transplant Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Stacy K Thomas
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Chad A Komar
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Joey H Li
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Devora Delman
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Kathleen Graham
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Whitney L Gladney
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xia Hua
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Taylor A Black
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Austin L Chien
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Krishna S Majmundar
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jeffrey C Thompson
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Stephanie S Yee
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mark H O'Hara
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Charu Aggarwal
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Dong Xin
- Division of Transplant Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Abraham Shaked
- Division of Transplant Surgery, Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mingming Gao
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA, USA
| | - Dexi Liu
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA, USA
| | - Mitesh J Borad
- Mayo Clinic Cancer Center, Mayo Clinic, Phoenix, AZ, USA
| | - Ramesh K Ramanathan
- Mayo Clinic Cancer Center, Mayo Clinic, Phoenix, AZ, USA
- Merck Research Labs, Rahway, NJ, USA
| | - Erica L Carpenter
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ailing Ji
- Department of Internal Medicine, University of Kentucky, Lexington, KY, USA
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Maria C de Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
- Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Frederick C de Beer
- Department of Internal Medicine, University of Kentucky, Lexington, KY, USA
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, USA
| | - Gregory L Beatty
- Abramson Cancer Center, University of Pennsylvania, Philadelphia, PA, USA.
- Division of Hematology-Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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15
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Wilson PG, Thompson JC, Shridas P, McNamara PJ, de Beer MC, de Beer FC, Webb NR, Tannock LR. Serum Amyloid A Is an Exchangeable Apolipoprotein. Arterioscler Thromb Vasc Biol 2018; 38:1890-1900. [PMID: 29976766 PMCID: PMC6202200 DOI: 10.1161/atvbaha.118.310979] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Objective- SAA (serum amyloid A) is a family of acute-phase reactants that have proinflammatory and proatherogenic activities. SAA is more lipophilic than apoA-I (apolipoprotein A-I), and during an acute-phase response, <10% of plasma SAA is found lipid-free. In most reports, SAA is found exclusively associated with high-density lipoprotein; however, we and others have reported SAA on apoB (apolipoprotein B)-containing lipoproteins in both mice and humans. The goal of this study was to determine whether SAA is an exchangeable apolipoprotein. Approach and Results- Delipidated human SAA was incubated with SAA-free human lipoproteins; then, samples were reisolated by fast protein liquid chromatography, and SAA analyzed by ELISA and immunoblot. Both in vitro and in vivo, we show that SAA associates with any lipoprotein and does not remain in a lipid-free form. Although SAA is preferentially found on high-density lipoprotein, it can exchange between lipoproteins. In the presence of CETP (cholesterol ester transfer protein), there is greater exchange of SAA between lipoproteins. Subjects with diabetes mellitus, but not those with metabolic syndrome, showed altered SAA lipoprotein distribution postprandially. Proteoglycan-mediated lipoprotein retention is thought to be an underlying mechanism for atherosclerosis development. SAA has a proteoglycan-binding domain. Lipoproteins containing SAA had increased proteoglycan binding compared with SAA-free lipoproteins. Conclusions- Thus, SAA is an exchangeable apolipoprotein and increases apoB-containing lipoproteins' proteoglycan binding. We and others have previously reported the presence of SAA on low-density lipoprotein in individuals with obesity, diabetes mellitus, and metabolic syndrome. We propose that the presence of SAA on apoB-containing lipoproteins may contribute to cardiovascular disease development in these populations.
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Affiliation(s)
- Patricia G Wilson
- Department of Veterans Affairs, Lexington, KY
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Joel C Thompson
- Department of Veterans Affairs, Lexington, KY
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Preetha Shridas
- Department of Internal Medicine, College of Medicine, University of Kentucky
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Patrick J McNamara
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky
| | - Maria C de Beer
- Department of Physiology, College of Medicine, University of Kentucky
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Frederick C de Beer
- Department of Internal Medicine, College of Medicine, University of Kentucky
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Nancy R Webb
- Department of Veterans Affairs, Lexington, KY
- Department of Pharmacology and Nutritional Sciences, College of Medicine, University of Kentucky
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
| | - Lisa R Tannock
- Department of Veterans Affairs, Lexington, KY
- Department of Internal Medicine, College of Medicine, University of Kentucky
- Saha Cardiovascular Research Center, College of Medicine, University of Kentucky
- Barnstable Brown Diabetes Center, College of Medicine, University of Kentucky
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16
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Shridas P, De Beer MC, Webb NR. High-density lipoprotein inhibits serum amyloid A-mediated reactive oxygen species generation and NLRP3 inflammasome activation. J Biol Chem 2018; 293:13257-13269. [PMID: 29976759 DOI: 10.1074/jbc.ra118.002428] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 06/18/2018] [Indexed: 12/11/2022] Open
Abstract
Serum amyloid A (SAA) is a high-density apolipoprotein whose plasma levels can increase more than 1000-fold during a severe acute-phase inflammatory response and are more modestly elevated in chronic inflammation. SAA is thought to play important roles in innate immunity, but its biological activities have not been completely delineated. We previously reported that SAA deficiency protects mice from developing abdominal aortic aneurysms (AAAs) induced by chronic angiotensin II (AngII) infusion. Here, we report that SAA is required for AngII-induced increases in interleukin-1β (IL-1β), a potent proinflammatory cytokine that is tightly controlled by the Nod-like receptor protein 3 (NLRP3) inflammasome and caspase-1 and has been implicated in both human and mouse AAAs. We determined that purified SAA stimulates IL-1β secretion in murine J774 and bone marrow-derived macrophages through a mechanism that depends on NLRP3 expression and caspase-1 activity, but is independent of P2X7 nucleotide receptor (P2X7R) activation. Inhibiting reactive oxygen species (ROS) by N-acetyl-l-cysteine or mito-TEMPO and inhibiting activation of cathepsin B by CA-074 blocked SAA-mediated inflammasome activation and IL-1β secretion. Moreover, inhibiting cellular potassium efflux with glyburide or increasing extracellular potassium also significantly reduced SAA-mediated IL-1β secretion. Of note, incorporating SAA into high-density lipoprotein (HDL) prior to its use in cell treatments completely abolished its ability to stimulate ROS generation and inflammasome activation. These results provide detailed insights into SAA-mediated IL-1β production and highlight HDL's role in regulating SAA's proinflammatory effects.
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Affiliation(s)
- Preetha Shridas
- From the Departments of Internal Medicine, .,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, Kentucky 40536
| | - Maria C De Beer
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, Kentucky 40536.,Physiology, and.,Pharmacology and Nutritional Sciences
| | - Nancy R Webb
- Barnstable Brown Diabetes Center, University of Kentucky, Lexington, Kentucky 40536.,Pharmacology and Nutritional Sciences.,Saha Cardiovascular Research Center, and
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17
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Lee JW, Thomas SK, Komar CA, Gladney WL, Hua X, Xin D, Shaked A, Borad MJ, Ramanathan RK, Ji A, Webb NR, Beer MCD, Beer FCD, Porrett PM, Beatty GL. Abstract 1102: IL-6/STAT3 activation in hepatocytes drives pro-metastatic niche formation in the liver. Cancer Res 2018. [DOI: 10.1158/1538-7445.am2018-1102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
The liver is the most common site of metastasis in pancreatic ductal adenocarcinoma (PDAC). This metastatic tropism is dependent, at least in part, on the formation of a “pro-metastatic” niche that supports tumor cell seeding and colonization in the liver. However, mechanisms that direct the formation of this niche remain poorly understood. We show using the LSL-KrasG12D/+;LSL-Trp53R172H/+;Pdx-1-Cre (KPC) model of PDAC that pancreatic tumor development enhances the susceptibility of the liver to metastatic seeding by inducing recruitment of F4/80+ and Ly6G+ myeloid cells and fibrosis within the liver. 3' mRNA sequencing (QuantSeq) on RNA isolated from the liver of KPC mice versus control PC mice revealed that the liver produces a specific set of myeloid chemoattractants, particularly serum amyloid A1 and A2 (SAA1/2), early during PDAC development. In addition, gene set enrichment analysis (GSEA) on genes upregulated in the liver of KPC mice demonstrated a significant enrichment of the interleukin 6 (IL-6)/Signal Transducer and Activator of Transcription 3 (STAT3) signaling pathway. Consistent with this finding, phosphorylation of STAT3 was detected in 20-30% of F4/80+ myeloid cells and 80-90% of hepatocytes. A requirement for IL-6/STAT3 signaling in the formation of a pro-metastatic niche was determined by comparing the metastatic potential of wild type mice, Il-6 knockout (Il-6-/-) mice, and mice treated with anti-IL-6 receptor (IL-6R) antibody after orthotopic implantation of KPC-derived PDAC cells. Compared to wild type mice, the liver of Il-6-/- mice and mice treated with anti-IL-6R antibody was less susceptible to metastatic seeding and showed significantly less accumulation of myeloid cells, fibrosis, and production of SAA1/2 in the liver. We obtained similar results with mice that lack Stat3 specifically in hepatocytes (Stat3flox/flox Alb-Cre), demonstrating that IL-6/STAT3 signaling in hepatocytes is necessary for the formation of a pro-metastatic niche in the liver. Further, using Saa1/2 double knockout (Saa-/-) mice, we found that SAA1/2 production by hepatocytes was required for formation of the pro-metastatic niche in the liver and increased susceptibility to metastatic seeding. Patients with a history of liver metastasis also showed higher levels of SAA1/2 in the plasma compared to normal donors, and SAA overexpression was detected in hepatocytes in liver biopsy samples collected from PDAC patients. Collectively, our study reveals a novel role for hepatocytes in directing the formation of a pro-metastatic niche in the liver during PDAC development and identifies IL-6/STAT3/SAA1/2 signaling as a promising therapeutic target for prevention of metastasis in PDAC.
Citation Format: Jae W. Lee, Stacy K. Thomas, Chad A. Komar, Whitney L. Gladney, Xia Hua, Dong Xin, Abraham Shaked, Mitesh J. Borad, Ramesh K. Ramanathan, Ailing Ji, Nancy R. Webb, Maria C. de Beer, Frederick C. de Beer, Paige M. Porrett, Gregory L. Beatty. IL-6/STAT3 activation in hepatocytes drives pro-metastatic niche formation in the liver [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1102.
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Affiliation(s)
- Jae W. Lee
- 1University of Pennsylvania, Philadelphia, PA
| | | | | | | | - Xia Hua
- 1University of Pennsylvania, Philadelphia, PA
| | - Dong Xin
- 1University of Pennsylvania, Philadelphia, PA
| | | | | | | | - Ailing Ji
- 3University of Kentucky, Lexington, KY
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18
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Shridas P, de Beer MC, Webb NR. Abstract 566: High-density Lipoprotein Inhibits Serum Amyloid a -Mediated Inflammasome Activation. Arterioscler Thromb Vasc Biol 2018. [DOI: 10.1161/atvb.38.suppl_1.566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives:
Interleukin-1beta (IL-1β) has been implicated in inflammatory diseases, including atherosclerosis and abdominal aortic aneurysm (AAA). Production of bioactive IL-1β is controlled by the inflammasome, a multi-protein complex that regulates caspase-1 activity. Serum Amyloid A (SAA) is an acute-phase protein whose levels in circulation is elevated in individuals with chronic inflammation. We previously reported that deficiency of SAA protects mice from angiotensin II (AngII)-induced AAA. Here we report that reduced AngII-induced AAA in SAA-deficient mice is accompanied by significant reductions in plasma IL-1β, indicating that SAA is required for inflammasome activation in AngII-infused mice. The objective of this study is to investigate mechanisms involved in SAA-mediated inflammasome activation.
Methods/Results:
SAA dose-dependently induced both caspase-1 activation and IL-1β secretion in J774 macrophage-like cells incubated with 0-25 μg/ml purified mouse SAA. The ability of SAA to induce IL-1β secretion was significantly reduced in bone marrow-derived macrophages deficient in NLRP3. A caspase-1inhibitor, Z-YVAD-FMK, significantly suppressed IL-1β secretion induced by SAA, whereas the P2X7-receptor antagonist, AA38079, had no effect. Inhibition of reactive oxygen species (ROS), cathepsin-B activation, and cellular potassium efflux by N-acetyl-L-cysteine, CA-074, and glyburide, respectively, blocked NLRP3 inflammasome activation by SAA. Pre-incubating SAA with HDL prior to cell treatments completely abrogated SAA-mediated inflammasome activation. In contrast, HDL did not alter inflammasome activation triggered by ATP.
Conclusions:
SAA-mediated NLRP3 inflammasome activation in macrophages is dependent on ROS generation, release of cathepsin-B, and potassium efflux, and is independent of the P2X7 receptor. Moreover, our data identify a novel mechanism by which HDL may exert cardioprotective effects.
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19
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Thompson JC, Wilson PG, Shridas P, Ji A, de Beer M, de Beer FC, Webb NR, Tannock LR. Serum amyloid A3 is pro-atherogenic. Atherosclerosis 2018; 268:32-35. [PMID: 29175652 PMCID: PMC5839639 DOI: 10.1016/j.atherosclerosis.2017.11.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/24/2017] [Accepted: 11/15/2017] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND AIMS Serum amyloid A (SAA) predicts cardiovascular events. Overexpression of SAA increases atherosclerosis development; however, deficiency of two of the murine acute phase isoforms, SAA1.1 and SAA2.1, has no effect on atherosclerosis. SAA3 is a pseudogene in humans, but is an expressed acute phase isoform in mice. The goal of this study was to determine if SAA3 affects atherosclerosis in mice. METHODS ApoE-/- mice were used as the model for all studies. SAA3 was overexpressed by an adeno-associated virus or suppressed using an anti-sense oligonucleotide approach. RESULTS Over-expression of SAA3 led to a 4-fold increase in atherosclerosis lesion area compared to control mice (p = 0.01). Suppression of SAA3 decreased atherosclerosis in mice genetically deficient in SAA1.1 and SAA2.1 (p < 0.0001). CONCLUSIONS SAA3 augments atherosclerosis in mice. Our results resolve a previous paradox in the literature and support extensive epidemiological data that SAA is pro-atherogenic.
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Affiliation(s)
- Joel C Thompson
- Department of Veterans Affairs, Lexington, KY 40502, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Patricia G Wilson
- Department of Veterans Affairs, Lexington, KY 40502, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Preetha Shridas
- Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Ailing Ji
- Department of Veterans Affairs, Lexington, KY 40502, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Maria de Beer
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Frederick C de Beer
- Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Nancy R Webb
- Department of Veterans Affairs, Lexington, KY 40502, USA; Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA
| | - Lisa R Tannock
- Department of Veterans Affairs, Lexington, KY 40502, USA; Department of Internal Medicine, University of Kentucky, Lexington, KY, 40536, USA; Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY, 40536, USA; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, 40536, USA.
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20
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Tannock LR, De Beer MC, Ji A, Shridas P, Noffsinger VP, den Hartigh L, Chait A, De Beer FC, Webb NR. Serum amyloid A3 is a high density lipoprotein-associated acute-phase protein. J Lipid Res 2017; 59:339-347. [PMID: 29247043 DOI: 10.1194/jlr.m080887] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/22/2017] [Indexed: 12/20/2022] Open
Abstract
Serum amyloid A (SAA) is a family of acute-phase reactants. Plasma levels of human SAA1/SAA2 (mouse SAA1.1/2.1) can increase ≥1,000-fold during an acute-phase response. Mice, but not humans, express a third relatively understudied SAA isoform, SAA3. We investigated whether mouse SAA3 is an HDL-associated acute-phase SAA. Quantitative RT-PCR with isoform-specific primers indicated that SAA3 and SAA1.1/2.1 are induced similarly in livers (∼2,500-fold vs. ∼6,000-fold, respectively) and fat (∼400-fold vs. ∼100-fold, respectively) of lipopolysaccharide (LPS)-injected mice. In situ hybridization demonstrated that all three SAAs are produced by hepatocytes. All three SAA isoforms were detected in plasma of LPS-injected mice, although SAA3 levels were ∼20% of SAA1.1/2.1 levels. Fast protein LC analyses indicated that virtually all of SAA1.1/2.1 eluted with HDL, whereas ∼15% of SAA3 was lipid poor/free. After density gradient ultracentrifugation, isoelectric focusing demonstrated that ∼100% of plasma SAA1.1 was recovered in HDL compared with only ∼50% of SAA2.1 and ∼10% of SAA3. Thus, SAA3 appears to be more loosely associated with HDL, resulting in lipid-poor/free SAA3. We conclude that SAA3 is a major hepatic acute-phase SAA in mice that may produce systemic effects during inflammation.
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Affiliation(s)
- Lisa R Tannock
- Departments of Internal Medicine, University of Kentucky, Lexington, KY.,Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY.,Veterans Affairs Lexington, University of Kentucky, Lexington, KY
| | - Maria C De Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY.,Departments of Physiology, University of Kentucky, Lexington, KY
| | - Ailing Ji
- Departments of Internal Medicine, University of Kentucky, Lexington, KY.,Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | - Preetha Shridas
- Departments of Internal Medicine, University of Kentucky, Lexington, KY.,Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY
| | - Victoria P Noffsinger
- Departments of Internal Medicine, University of Kentucky, Lexington, KY.,Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | - Laura den Hartigh
- Department of Medicine University of Washington, Seattle, WA.,University of Washington Diabetes Institute, University of Washington, Seattle, WA
| | - Alan Chait
- Department of Medicine University of Washington, Seattle, WA.,University of Washington Diabetes Institute, University of Washington, Seattle, WA
| | - Frederick C De Beer
- Departments of Internal Medicine, University of Kentucky, Lexington, KY.,Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY .,Barnstable Brown Diabetes Center, University of Kentucky, Lexington, KY.,Veterans Affairs Lexington, University of Kentucky, Lexington, KY.,Departments of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
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21
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Abstract
PURPOSE Group X (GX) and group V (GV) secretory phospholipase A2 (sPLA2) potently release arachidonic acid (AA) from the plasma membrane of intact cells. We previously demonstrated that GX sPLA2 negatively regulates glucose-stimulated insulin secretion (GSIS) by a prostaglandin E2 (PGE2)-dependent mechanism. In this study we investigated whether GV sPLA2 similarly regulates GSIS. METHODS GSIS and pancreatic islet-size were assessed in wild-type (WT) and GV sPLA2-knock out (GV KO) mice. GSIS was also assessed ex vivo in isolated islets and in vitro using MIN6 pancreatic beta cell lines with or without GV sPLA2 overexpression or silencing. RESULTS GSIS was significantly decreased in islets isolated from GV KO mice compared to WT mice and in MIN6 cells with siRNA-mediated GV sPLA2 suppression. MIN6 cells overexpressing GV sPLA2 (MIN6-GV) showed a significant increase in GSIS compared to control cells. Though the amount of AA released into the media by MIN6-GV cells was significantly higher, PGE2 production was not enhanced or cAMP content decreased compared to control MIN6 cells. Surprisingly, GV KO mice exhibited a significant increase in plasma insulin levels following i.p. injection of glucose compared to WT mice. This increase in GSIS in GV KO mice was associated with a significant increase in pancreatic islet size and number of proliferating cells in β-islets compared to WT mice. CONCLUSIONS Deficiency of GV sPLA2 results in diminished GSIS in isolated pancreatic beta-cells. However, the reduced GSIS in islets lacking GV sPLA2 appears to be compensated by increased islet mass in GV KO mice.
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Affiliation(s)
- Preetha Shridas
- Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY, 40536, USA.
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY, 40536, USA.
| | - Victoria P Noffsinger
- Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY, 40536, USA
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY, 40536, USA
| | - Andrea C Trumbauer
- Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY, 40536, USA
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY, 40536, USA
- Pharmacology and Nutritional Sciences, Division of Nutritional Sciences, University of Kentucky Medical Center, Lexington, KY, 40536, USA
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22
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Wilson PG, Thompson JC, Shridas P, de Beer FC, Webb NR, Tannock LR. Abstract 15: Serum Amyloid A is Not Just an HDL-Associated Lipoprotein. Arterioscler Thromb Vasc Biol 2017. [DOI: 10.1161/atvb.37.suppl_1.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Serum Amyloid A (SAA) is traditionally thought to be only found with HDL; however, recently several groups have found that SAA is found on apoB-containing lipoproteins (LDL and VLDL) under some circumstances. The goal of this study was to determine the relative lipoprotein association of SAA. Native human acute phase SAA was isolated from acute phase plasma collected from patients undergoing cardiovascular bypass surgery; the SAA was purified and delipidated. Plasma was collected from a group of healthy, non-obese humans with low levels of SAA (< 2 mg/L) and lipoproteins (VLDL, LDL and HDL) were isolated by density gradient ultracentrifugation. The delipidated SAA (at 2 concentrations) was incubated in vitro with the various lipoprotein preparations then samples were re-isolated by fast protein liquid chromatography and SAA was analyzed by ELISA and immunoblot. When SAA was incubated with any single lipoprotein all of the SAA was found associated with that lipoprotein and none remained in a lipid-free form. When SAA was incubated with a mixture of VLDL, LDL and HDL (based on equal protein and corresponding to concentrations in plasma) a majority of SAA (50-60%) was found on HDL with the remaining SAA found on VLDL and LDL. When SAA first complexed to HDL was added to a mixture of SAA-free LDL and VLDL the majority of SAA remained with the HDL (76-86%) but 5-10% of the SAA was found on each of LDL and VLDL. When SAA first complexed to either apoB-containing lipoprotein was then added to a mixture of HDL and the other apoB-containing lipoprotein most SAA moved to HDL (55-70%) but the remainder was found on the apoB-containing particles. Thus, SAA can move between lipoprotein particles in vitro. To determine if the presence of SAA on apoB-containing lipoproteins had a functional effect we evaluated lipoprotein-proteoglycan binding affinity. Proteoglycan mediated lipoprotein retention in the vessel wall is thought to be one of the key steps in initiation of atherosclerosis. Compared to SAA-free LDL or VLDL, the presence of SAA on apoB-containing lipoproteins caused increased proteoglycan binding affinity. Thus, SAA is not simply an HDL lipoprotein, but SAA can move between lipoprotein particles, and the presence of SAA on apoB particles may increase their atherogenicity.
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23
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Ji A, Akinmusire A, de Beer MC, de Beer FC, Webb NR, van der Westhuyzen DR. Abstract 380: SAA Lipidation and Delipidation by Hepatocytes. Arterioscler Thromb Vasc Biol 2017. [DOI: 10.1161/atvb.37.suppl_1.380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Serum amyloid A (SAA) is one of the most striking acute phase reactants that can rapidly increase 1000-fold in plasma concentration in response to inflammatory cytokines. SAA in lipid-free form exhibits pro-inflammatory activities, but its putative physiological function(s) are poorly understood. SAA is produced and secreted largely by the liver and is present in plasma mainly as an HDL apolipoprotein. The pathways by which SAA is lipidated and incorporated into HDL are poorly understood. Plasma SAA is cleared more rapidly than the other major HDL apolipoproteins, but pathways involved in its delipidation and plasma clearance have also not been defined. In this study we examined how SAA is lipidated in primary hepatocytes and how such lipidation relates to the formation of nascent HDL particles. Endogenous hepatocyte SAA was lipidated and released from cells as large particles that were distinct from apoA-I-containing nascent HDL’s. Unlike apoA-I, formation of these SAA-containing particles was independent of ABCA-I. Similarly, when SAA was exogenously added to cells, SAA was lipidated to form nascent particles that were distinct from apoA-I-containing particles. We further studied the interaction of lipid-free and HDL-bound SAA with hepatocytes. Both in lipid-free form and as part of HDL, SAA exhibited significantly greater binding to cells than apoA-I or apoA-II. Binding studies were also carried out with normal and acute phase HDL’s isolated from control and SAA-deficient mice. Together, the results suggested that SAA, unlike apoA-I, is selectively removed from HDL by binding to hepatocytes. These findings may provide new insights into SAA metabolism and function.
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24
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De Beer MC, Ji A, Noffsinger VP, Schridas P, De Beer FC, Tannock LR, Webb NR. Abstract 563: Serum Amyloid A3 is a High Density Lipoprotein-associated Acute Phase Protein. Arterioscler Thromb Vasc Biol 2017. [DOI: 10.1161/atvb.37.suppl_1.563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute phase serum amyloid (SAA) is a family of evolutionarily conserved, secreted proteins that exerts innate functions relevant to vascular disease. In humans, two SAA isoforms (SAA1 and SAA2) are highly induced in the liver and extrahepatic tissues under the regulation of inflammatory cytokines. During severe inflammation, SAA1/2 levels can increase ≥1000-fold in plasma, where it is found associated with HDL. Mice produce an additional acute phase SAA, SAA3, which is thought to be produced mainly by adipocytes and macrophages and has not previously been found circulating on HDL. The goal of this study was to investigate whether SAA3 serves as a third liver-derived, HDL-associated acute phase SAA in mice. Using isoform-specific oligonucleotide primers for qRT-PCR, we determined that SAA3 is transcriptionally induced to a similar extent (~2500-fold) compared to SAA1.1/2.1 (~6000-fold) in livers of C57BL/6 mice 19 hr after lipopolysaccharide (LPS) injection (100 μg/mouse). SAAs were also robustly induced in fat tissue (SAA1/2~100-fold; SAA3~400-fold). The analysis of primary mouse hepatocytes and
in situ
hybridization of mouse liver sections indicated that liver-derived SAAs are produced by hepatocytes and not other stromal cells, including Kupffer cells. All 3 SAA isoforms were detected in plasma of LPS-injected mice, although SAA3 levels were ~20% of SAA1/2. After separation by FPLC, virtually all of plasma SAA1/2 eluted with the HDL fraction, whereas ~15% of plasma SAA3 appeared to be lipid poor/free. HDL isolated from acute phase mouse plasma by density gradient ultracentrifugation was subjected to isoelectric focusing to determine the relative recovery of the various SAA isoforms. Whereas the bulk of plasma SAA1.1 was found in the d=1.063-1.21 fraction, only ~50% of SAA2.1 and ~10% of SAA3 was recovered after ultracentrifugation. These findings suggest that SAA3 may be more loosely associated with HDL compared to SAA1.1/2.1, which may give rise to lipid poor/free SAA3 that is susceptible to more rapid clearance in vivo. We conclude that SAA3 is a major hepatic acute phase SAA in mice that may produce systemic effects during inflammation. Future studies investigating SAA pathobiology in mice must take into account the previously under-studied SAA3.
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25
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Schewe M, Franken PF, Sacchetti A, Schmitt M, Joosten R, Böttcher R, van Royen ME, Jeammet L, Payré C, Scott PM, Webb NR, Gelb M, Cormier RT, Lambeau G, Fodde R. Secreted Phospholipases A2 Are Intestinal Stem Cell Niche Factors with Distinct Roles in Homeostasis, Inflammation, and Cancer. Cell Stem Cell 2016; 19:38-51. [PMID: 27292189 DOI: 10.1016/j.stem.2016.05.023] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 02/10/2016] [Accepted: 05/19/2016] [Indexed: 01/04/2023]
Abstract
The intestinal stem cell niche provides cues that actively maintain gut homeostasis. Dysregulation of these cues may compromise intestinal regeneration upon tissue insult and/or promote tumor growth. Here, we identify secreted phospholipases A2 (sPLA2s) as stem cell niche factors with context-dependent functions in the digestive tract. We show that group IIA sPLA2, a known genetic modifier of mouse intestinal tumorigenesis, is expressed by Paneth cells in the small intestine, while group X sPLA2 is expressed by Paneth/goblet-like cells in the colon. During homeostasis, group IIA/X sPLA2s inhibit Wnt signaling through intracellular activation of Yap1. However, upon inflammation they are secreted into the intestinal lumen, where they promote prostaglandin synthesis and Wnt signaling. Genetic ablation of both sPLA2s improves recovery from inflammation but increases colon cancer susceptibility due to release of their homeostatic Wnt-inhibitory role. This "trade-off" effect suggests sPLA2s have important functions as genetic modifiers of inflammation and colon cancer.
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Affiliation(s)
- Matthias Schewe
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Patrick F Franken
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Andrea Sacchetti
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Mark Schmitt
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Rosalie Joosten
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - René Böttcher
- Department of Urology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Martin E van Royen
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands; Erasmus Optical Imaging Centre, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands
| | - Louise Jeammet
- Institute of Molecular and Cellular Pharmacology, Centre National de la Recherche Scientifique and University of Nice Sophia Antipolis, Valbonne 06560, France
| | - Christine Payré
- Institute of Molecular and Cellular Pharmacology, Centre National de la Recherche Scientifique and University of Nice Sophia Antipolis, Valbonne 06560, France
| | - Patricia M Scott
- Department of Biomedical Sciences, University of Minnesota Medical School Duluth, Duluth, MN 55812-3031, USA
| | - Nancy R Webb
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40506-9983, USA
| | - Michael Gelb
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA
| | - Robert T Cormier
- Department of Biomedical Sciences, University of Minnesota Medical School Duluth, Duluth, MN 55812-3031, USA
| | - Gérard Lambeau
- Institute of Molecular and Cellular Pharmacology, Centre National de la Recherche Scientifique and University of Nice Sophia Antipolis, Valbonne 06560, France
| | - Riccardo Fodde
- Department of Pathology, Erasmus MC Cancer Institute, Rotterdam 3000CA, The Netherlands.
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26
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De Beer MC, Kim MH, Wroblewski JM, Charnigo RC, Ji A, Webb NR, De Beer FC, Van der Westhuyzen DR. Abstract 388: Impact of Individual Acute Phase Serum Amyloid A Isoforms on HDL Metabolism in Mice. Arterioscler Thromb Vasc Biol 2016. [DOI: 10.1161/atvb.36.suppl_1.388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The acute phase reactant serum amyloid A (SAA) is an HDL apolipoprotein that exhibits biological activities as a pro-inflammatory mediator, but its physiological function(s) are poorly understood. Possible functional differences between SAA1.1 and SAA2.1, the two major SAA isoforms, are also unclear. Mice deficient in either SAA1.1 or SAA2.1 were used to investigate SAA isoform plasma clearance rates and effects on HDL structure, composition and apolipoprotein catabolism. The absence of either isoform did not affect the size of the normally enlarged HDL found in acute phase wild type mice, and did not result in significant changes in HDL lipid composition. Plasma clearance rates of normal and acute phase HDL apolipoproteins were determined using native HDL particles. The fractional clearance rates (FCR’s) of apoA-I, apoA-II and SAA were distinct, indicating that neither normal nor acute phase particles are cleared as intact particles. No significant difference was found between the FCR’s of SAA1.1 and SAA2.1 in acute phase mice, suggesting that the selective deposition of SAA1.1 observed in amyloid plaques is not associated with a difference in the rates of plasma clearance of the isoforms. In the absence of the HDL receptor SR-BI, the clearance rate of SAA was reduced by about 30% and remained significantly greater compared to that of apoA-I and apoA-II, indicating a relatively minor role of SR-BI in SAA clearance. These studies contribute to our understanding of the metabolism of SAA and its effects on acute phase HDL composition and catabolism.
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Affiliation(s)
| | | | | | | | - Ailing Ji
- Medicine, Univ. of Kentucky, Lexington, KY
| | - Nancy R Webb
- Pharmacology and Nutritional Sciences, Univ. of Kentucky, Lexington, KY
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27
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Kim MH, de Beer MC, Wroblewski JM, Charnigo RJ, Ji A, Webb NR, de Beer FC, van der Westhuyzen DR. Impact of individual acute phase serum amyloid A isoforms on HDL metabolism in mice. J Lipid Res 2016; 57:969-79. [PMID: 27018443 DOI: 10.1194/jlr.m062174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 01/12/2023] Open
Abstract
The acute phase (AP) reactant serum amyloid A (SAA), an HDL apolipoprotein, exhibits pro-inflammatory activities, but its physiological function(s) are poorly understood. Functional differences between SAA1.1 and SAA2.1, the two major SAA isoforms, are unclear. Mice deficient in either isoform were used to investigate plasma isoform effects on HDL structure, composition, and apolipoprotein catabolism. Lack of either isoform did not affect the size of HDL, normally enlarged in the AP, and did not significantly change HDL composition. Plasma clearance rates of HDL apolipoproteins were determined using native HDL particles. The fractional clearance rates (FCRs) of apoA-I, apoA-II, and SAA were distinct, indicating that HDL is not cleared as intact particles. The FCRs of SAA1.1 and SAA2.1 in AP mice were similar, suggesting that the selective deposition of SAA1.1 in amyloid plaques is not associated with a difference in the rates of plasma clearance of the isoforms. Although the clearance rate of SAA was reduced in the absence of the HDL receptor, scavenger receptor class B type I (SR-BI), it remained significantly faster compared with that of apoA-I and apoA-II, indicating a relatively minor role of SR-BI in SAA's rapid clearance. These studies enhance our understanding of SAA metabolism and SAA's effects on AP-HDL composition and catabolism.
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Affiliation(s)
- Myung-Hee Kim
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536
| | - Maria C de Beer
- Physiology, University of Kentucky Medical Center, Lexington, KY 40536 Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536
| | - Joanne M Wroblewski
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536 Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536
| | - Richard J Charnigo
- Departments of Statistics and Biostatistics, University of Kentucky, Lexington, KY 40506
| | - Ailing Ji
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536 Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536 Pharmacology and Nutritional Sciences, University of Kentucky Medical Center, Lexington, KY 40536
| | - Frederick C de Beer
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536 Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536
| | - Deneys R van der Westhuyzen
- Departments of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536 Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536 Molecular and Cellular Biochemistry, University of Kentucky Medical Center, Lexington, KY 40536
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Shridas P, Noffsinger VP, Webb NR. Abstract 483: Non-redundant and Opposing Roles of Group X and Group V Secretory Phospholipase A2s on Pancreatic Beta-cell Function. Arterioscler Thromb Vasc Biol 2015. [DOI: 10.1161/atvb.35.suppl_1.483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Group X and group V secretory phospholipase A2s (GX and GV sPLA2s) potently release arachidonic acid (AA) from the plasma membrane of intact cells. AA is an activator of glucose-stimulated insulin secretion (GSIS) by β-islet cells. However, the AA metabolite prostaglandin E2 (PGE2) is a known inhibitor of GSIS. Both GX and GV sPLA2s are expressed in mouse pancreatic islet cells. We previously demonstrated that GX sPLA2 negatively regulates GSIS by a PGE2-dependent mechanism. In this study we investigated whether GV sPLA2 similarly regulates GSIS.
Methods and Results:
GSIS was measured in pancreatic islet cells isolated from WT and GV sPLA2-deficient (GV KO) mice. To complement these studies, GSIS was also assessed in vitro using MIN6 pancreatic beta cell lines with or without GV sPLA2 overexpression or silencing. In marked contrast to our findings in GX KO mice, GSIS was significantly decreased in islets isolated from GV KO mice compared to WT mice. Similarly, there was a significant decrease in GSIS in MIN6 cells with siRNA-mediated GV sPLA2 suppression. Consistent with these findings, MIN6 cells overexpressing GV sPLA2 (MIN6-GV) showed a significant increase in GSIS compared to control cells. As expected, the amount of AA released into the media by MIN6-GV cells was significantly increased compared to control MIN6 cells. However, unlike MIN6 cells overexpressing GX sPLA2, MIN6-GV cells did not exhibit enhanced PGE2 production or decreased cAMP content compared to control MIN6 cells, despite similar amounts of sPLA2 activity produced by the two cell lines.
Conclusions:
We conclude that GX and GV sPLA2s play opposing and non-redundant roles in pancreatic β-cell function. Whereas GV sPLA2 activates GSIS, GX sPLA2 suppresses this process. This functional difference appears to be due to the extent to which AA generated by the respective sPLA2’s is coupled to PGE2 production.
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Affiliation(s)
| | | | - Nancy R Webb
- Molecular and Biomedical Pharmacology, Univ of Kentucky, Lexington, KY
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Webb NR, De Beer MC, Wroblewski JM, Ji A, Bailey W, Shridas P, Charnigo RJ, Noffsinger VP, Witta J, Howatt DA, Balakrishnan A, Rateri DL, Daugherty A, De Beer FC. Deficiency of Endogenous Acute-Phase Serum Amyloid A Protects apoE-/- Mice From Angiotensin II-Induced Abdominal Aortic Aneurysm Formation. Arterioscler Thromb Vasc Biol 2015; 35:1156-65. [PMID: 25745063 DOI: 10.1161/atvbaha.114.304776] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 02/13/2015] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Rupture of abdominal aortic aneurysm (AAA), a major cause of death in the aged population, is characterized by vascular inflammation and matrix degradation. Serum amyloid A (SAA), an acute-phase reactant linked to inflammation and matrix metalloproteinase induction, correlates with aortic dimensions before aneurysm formation in humans. We investigated whether SAA deficiency in mice affects AAA formation during angiotensin II (Ang II) infusion. APPROACH AND RESULTS Plasma SAA increased ≈60-fold in apoE(-/-) mice 24 hours after intraperitoneal Ang II injection (100 μg/kg; n=4) and ≈15-fold after chronic 28-day Ang II infusion (1000 ng/kg per minute; n=9). AAA incidence and severity after 28-day Ang II infusion was significantly reduced in apoE(-/-) mice lacking both acute-phase SAA isoforms (SAAKO; n=20) compared with apoE(-/-) mice (SAAWT; n=20) as assessed by in vivo ultrasound and ex vivo morphometric analyses, despite a significant increase in systolic blood pressure in SAAKO mice compared with SAAWT mice after Ang II infusion. Atherosclerotic lesion area of the aortic arch was similar in SAAKO and SAAWT mice after 28-day Ang II infusion. Immunostaining detected SAA in AAA tissues of Ang II-infused SAAWT mice that colocalized with macrophages, elastin breaks, and enhanced matrix metalloproteinase activity. Matrix metalloproteinase-2 activity was significantly lower in aortas of SAAKO mice compared with SAAWT mice after 10-day Ang II infusion. CONCLUSIONS Lack of endogenous acute-phase SAA protects against experimental AAA through a mechanism that may involve reduced matrix metalloproteinase-2 activity.
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Affiliation(s)
- Nancy R Webb
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.).
| | - Maria C De Beer
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Joanne M Wroblewski
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Ailing Ji
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - William Bailey
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Preetha Shridas
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Richard J Charnigo
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Victoria P Noffsinger
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Jassir Witta
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Deborah A Howatt
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Anju Balakrishnan
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Debra L Rateri
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Alan Daugherty
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
| | - Frederick C De Beer
- From the Departments of Pharmacology Division of Nutritional Sciences (N.R.W.), Physiology (M.C.D.B.) and Internal Medicine (J.M.W., A.J., W.B., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Saha Cardiovascular Research Center (N.R.W., M.C.D.B., J.M.W., A.J., P.S., V.P.N., D.A.H., A.B., D.L.R., A.D., F.C.D.B.), and Departments of Statistics and Biostatistics (R.J.C.), University of Kentucky, Lexington; and Foundation Gastroenterology, Nashua, NH (J.W.)
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Layne JD, Shridas P, Webb NR. Ectopically expressed pro-group X secretory phospholipase A2 is proteolytically activated in mouse adrenal cells by furin-like proprotein convertases: implications for the regulation of adrenal steroidogenesis. J Biol Chem 2015; 290:7851-60. [PMID: 25623068 DOI: 10.1074/jbc.m114.634667] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Group X secretory phospholipase A2 (GX sPLA2) hydrolyzes mammalian cell membranes, liberating free fatty acids and lysophospholipids. GX sPLA2 is produced as a pro-enzyme (pro-GX sPLA2) that contains an N-terminal 11-amino acid propeptide ending in a dibasic motif, suggesting cleavage by a furin-like proprotein convertase (PC). Although propeptide cleavage is clearly required for enzymatic activity, the protease(s) responsible for pro-GX sPLA2 activation have not been identified. We previously reported that GX sPLA2 negatively regulates adrenal glucocorticoid production, likely by suppressing liver X receptor-mediated activation of steroidogenic acute regulatory protein expression. In this study, using a FLAG epitope-tagged pro-GX sPLA2 expression construct (FLAG-pro-GX sPLA2), we determined that adrenocorticotropic hormone (ACTH) enhanced FLAG-pro-GX sPLA2 processing and phospholipase activity secreted by Y1 adrenal cells. ACTH increased the expression of furin and PCSK6, but not other members of the PC family, in Y1 cells. Overexpression of furin and PCSK6 in HEK 293 cells significantly enhanced FLAG-pro-GX sPLA2 processing, whereas siRNA-mediated knockdown of both PCs almost completely abolished FLAG-pro-GX sPLA2 processing in Y1 cells. Expression of either furin or PCSK6 enhanced the ability of GX sPLA2 to suppress liver X receptor reporter activity. The PC inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethyl ketone significantly suppressed FLAG-pro-GX sPLA2 processing and sPLA2 activity in Y1 cells, and it significantly attenuated GX sPLA2-dependent inhibition of steroidogenic acute regulatory protein expression and progesterone production. These findings provide strong evidence that pro-GX sPLA2 is a substrate for furin and PCSK6 proteolytic processing and define a novel mechanism for regulating corticosteroid production in adrenal cells.
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Affiliation(s)
- Joseph D Layne
- From the Department of Pharmacology and Nutritional Sciences, Division of Nutritional Sciences, the Saha Cardiovascular Research Center, and
| | - Preetha Shridas
- the Department of Internal Medicine, University of Kentucky Medical Center, Lexington, Kentucky 40536
| | - Nancy R Webb
- the Department of Internal Medicine, University of Kentucky Medical Center, Lexington, Kentucky 40536
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Shridas P, Zahoor L, Forrest KJ, Layne JD, Webb NR. Group X secretory phospholipase A2 regulates insulin secretion through a cyclooxygenase-2-dependent mechanism. J Biol Chem 2014; 289:27410-7. [PMID: 25122761 DOI: 10.1074/jbc.m114.591735] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Group X secretory phospholipase A2 (GX sPLA2) potently hydrolyzes membrane phospholipids to release arachidonic acid (AA). While AA is an activator of glucose-stimulated insulin secretion (GSIS), its metabolite prostaglandin E2 (PGE2) is a known inhibitor. In this study, we determined that GX sPLA2 is expressed in insulin-producing cells of mouse pancreatic islets and investigated its role in beta cell function. GSIS was measured in vivo in wild-type (WT) and GX sPLA2-deficient (GX KO) mice and ex vivo using pancreatic islets isolated from WT and GX KO mice. GSIS was also assessed in vitro using mouse MIN6 pancreatic beta cells with or without GX sPLA2 overexpression or exogenous addition. GSIS was significantly higher in islets isolated from GX KO mice compared with islets from WT mice. Conversely, GSIS was lower in MIN6 cells overexpressing GX sPLA2 (MIN6-GX) compared with control (MIN6-C) cells. PGE2 production was significantly higher in MIN6-GX cells compared with MIN6-C cells and this was associated with significantly reduced cellular cAMP. The effect of GX sPLA2 on GSIS was abolished when cells were treated with NS398 (a COX-2 inhibitor) or L-798,106 (a PGE2-EP3 receptor antagonist). Consistent with enhanced beta cell function, GX KO mice showed significantly increased plasma insulin levels following glucose challenge and were protected from age-related reductions in GSIS and glucose tolerance compared with WT mice. We conclude that GX sPLA2 plays a previously unrecognized role in negatively regulating pancreatic insulin secretion by augmenting COX-2-dependent PGE2 production.
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Affiliation(s)
- Preetha Shridas
- From Saha Cardiovascular Research Center and Departments of Internal Medicine and
| | - Lubna Zahoor
- From Saha Cardiovascular Research Center and Departments of Internal Medicine and
| | - Kathy J Forrest
- From Saha Cardiovascular Research Center and Departments of Internal Medicine and
| | - Joseph D Layne
- From Saha Cardiovascular Research Center and Pharmacology and Nutritional Sciences, Division of Nutritional Sciences, University of Kentucky Medical Center, Lexington Kentucky 40536
| | - Nancy R Webb
- From Saha Cardiovascular Research Center and Pharmacology and Nutritional Sciences, Division of Nutritional Sciences, University of Kentucky Medical Center, Lexington Kentucky 40536
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Ji A, Wroblewski JM, Webb NR, van der Westhuyzen DR. Impact of phospholipid transfer protein on nascent high-density lipoprotein formation and remodeling. Arterioscler Thromb Vasc Biol 2014; 34:1910-6. [PMID: 25060793 DOI: 10.1161/atvbaha.114.303533] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Phospholipid transfer protein (PLTP), which binds phospholipids and facilitates their transfer between lipoproteins in plasma, plays a key role in lipoprotein remodeling, but its influence on nascent high-density lipoprotein (HDL) formation is not known. The effect of PLTP overexpression on apolipoprotein A-I (apoA-I) lipidation by primary mouse hepatocytes was investigated. APPROACH AND RESULTS Overexpression of PLTP through an adenoviral vector markedly affected the amount and size of lipidated apoA-I species that were produced in hepatocytes in a dose-dependent manner, ultimately generating particles that were <7.1 nm but larger than lipid-free apoA-I. These <7.1-nm small particles generated in the presence of overexpressed PLTP were incorporated into mature HDL particles more rapidly than apoA-I both in vivo and in vitro and were less rapidly cleared from mouse plasma than lipid-free apoA-I. The <7.1-nm particles promoted both cellular cholesterol and phospholipid efflux in an ATP-binding cassette transporter A1-dependent manner, similar to apoA-I in the presence of PLTP. Lipid-free apoA-I had a greater efflux capacity in the presence of PLTP than in the absence of PLTP, suggesting that PLTP may promote ATP-binding cassette transporter A1-mediated cholesterol and phospholipid efflux. These results indicate that PLTP alters nascent HDL formation by modulating the lipidated species and by promoting the initial process of apoA-I lipidation. CONCLUSIONS Our findings suggest that PLTP exerts significant effects on apoA-I lipidation and nascent HDL biogenesis in hepatocytes by promoting ATP-binding cassette transporter A1-mediated lipid efflux and the remodeling of nascent HDL particles.
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Affiliation(s)
- Ailing Ji
- From the Department of Internal Medicine (A.J., J.M.W., D.R.v.d.W.), Department of Pharmacology and Nutritional Sciences (A.J., J.M.W., N.R.W., D.R.v.d.W.), Department of Molecular and Cellular Biochemistry (D.R.v.d.W.), and Saha Cardiovascular Research Center (A.J., J.M.W., N.R.W., D.R.v.d.W.), University of Kentucky, Lexington; and Department of Veterans Affairs Medical Center (N.R.W., D.R.v.d.W.), Lexington, KY
| | - Joanne M Wroblewski
- From the Department of Internal Medicine (A.J., J.M.W., D.R.v.d.W.), Department of Pharmacology and Nutritional Sciences (A.J., J.M.W., N.R.W., D.R.v.d.W.), Department of Molecular and Cellular Biochemistry (D.R.v.d.W.), and Saha Cardiovascular Research Center (A.J., J.M.W., N.R.W., D.R.v.d.W.), University of Kentucky, Lexington; and Department of Veterans Affairs Medical Center (N.R.W., D.R.v.d.W.), Lexington, KY
| | - Nancy R Webb
- From the Department of Internal Medicine (A.J., J.M.W., D.R.v.d.W.), Department of Pharmacology and Nutritional Sciences (A.J., J.M.W., N.R.W., D.R.v.d.W.), Department of Molecular and Cellular Biochemistry (D.R.v.d.W.), and Saha Cardiovascular Research Center (A.J., J.M.W., N.R.W., D.R.v.d.W.), University of Kentucky, Lexington; and Department of Veterans Affairs Medical Center (N.R.W., D.R.v.d.W.), Lexington, KY
| | - Deneys R van der Westhuyzen
- From the Department of Internal Medicine (A.J., J.M.W., D.R.v.d.W.), Department of Pharmacology and Nutritional Sciences (A.J., J.M.W., N.R.W., D.R.v.d.W.), Department of Molecular and Cellular Biochemistry (D.R.v.d.W.), and Saha Cardiovascular Research Center (A.J., J.M.W., N.R.W., D.R.v.d.W.), University of Kentucky, Lexington; and Department of Veterans Affairs Medical Center (N.R.W., D.R.v.d.W.), Lexington, KY.
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Webb NR, Wroblewski JM, Lutshumba J, De Beer MC, Noffsinger VP, Ji A, Guo Z, De Beer FC. Abstract 356: Serum Amyloid A Augments Aortic Aneurysm Formation Induced by Mineralocorticoid Receptor Agonists in the Presence of High Salt. Arterioscler Thromb Vasc Biol 2014. [DOI: 10.1161/atvb.34.suppl_1.356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives:
The annual mortality in the United States from ruptured aortic aneurysms is ~15000. Therapeutic interventions that prevent AAA progression and rupture remain to be identified. In humans, plasma concentrations of the acute phase reactant serum amyloid A (SAA) correlates with aortic dimensions before aneurysm formation. We have shown that endogenous SAA augments AAA in the well-established angiotensin II (AngII) infusion mouse model (unpublished data). Here we investigated whether endogenous SAA impacts aneurysm formation induced by deoxycorticosterone acetate (DOCA), a mineralocorticoid receptor agonist, in the presence of high salt.
Approach and results:
DOCA pellets (50mg, 21 day release) were implanted subcutaneously in the lateral dorsal region of 8-month old male C57BL/6 (SAAWT) mice and C57BL/6 mice lacking both acute phase SAA isoforms, SAA1.1 and SAA2.1 (SAAKO). The mice were also provided drinking water containing 0.9% NaCl and 0.2% KCl for 21 days (n = 7-8). As expected, DOCA + salt resulted in significantly increased systolic blood pressure, which was not affected by the absence of SAA. Unexpectedly SAAKO mice displayed a reduced urine output, accompanied by a reduced water intake. Plasma sodium and potassium concentrations in SAAWT and SAAKO mice were similar after treatment. The maximal luminal diameter of the abdominal aorta, as determined by ultrasound, was significantly lower in SAAKO mice compared to SAAWT mice after a 3-week DOCA + salt regime. Aneurysm incidence, determined by ultrasound and ex vivo analyses, was 67% for SAAWT mice and 25 % for SAAKO mice. Notably, plasma SAA was markedly increased in the SAAWT mice that formed aneurysms compared to those that did not. In SAAWT mice, immunohistochemical staining and in situ zymography identified SAA in aneurysmal aortic tissue, but not control aortas, that co-localized to regions of enhanced matrix metalloproteinase (MMP) activity, suggesting a role for SAA in MMP activation.
Conclusions:
We conclude that endogenous SAA augments aortic aneurysm formation induced by mineralocorticoid receptor agonists in the presence of high salt. Thus, SAA contributes to pathological processes leading to aortic aneurysm in two robust and mechanistically distinct animal models.
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Affiliation(s)
| | | | | | | | | | - Ailing Ji
- Medicine, Univ of Kentucky, Lexington, KY
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De Beer MC, Wroblewski JM, Noffsinger VP, Rateri DL, Howatt DA, Balakrishnan A, Ji A, Shridas P, Thompson JC, van der Westhuyzen DR, Tannock LR, Daugherty A, Webb NR, De Beer FC. Deficiency of endogenous acute phase serum amyloid A does not affect atherosclerotic lesions in apolipoprotein E-deficient mice. Arterioscler Thromb Vasc Biol 2013; 34:255-61. [PMID: 24265416 DOI: 10.1161/atvbaha.113.302247] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Although elevated plasma concentrations of serum amyloid A (SAA) are associated strongly with increased risk for atherosclerotic cardiovascular disease in humans, the role of SAA in the pathogenesis of lesion formation remains obscure. Our goal was to determine the impact of SAA deficiency on atherosclerosis in hypercholesterolemic mice. APPROACH AND RESULTS Apolipoprotein E-deficient (apoE(-/-)) mice, either wild type or deficient in both major acute phase SAA isoforms, SAA1.1 and SAA2.1, were fed a normal rodent diet for 50 weeks. Female mice, but not male apoE-/- mice deficient in SAA1.1 and SAA2.1, had a modest increase (22%; P≤0.05) in plasma cholesterol concentrations and a 53% increase in adipose mass compared with apoE-/- mice expressing SAA1.1 and SAA2.1 that did not affect the plasma cytokine levels or the expression of adipose tissue inflammatory markers. SAA deficiency did not affect lipoprotein cholesterol distributions or plasma triglyceride concentrations in either male or female mice. Atherosclerotic lesion areas measured on the intimal surfaces of the arch, thoracic, and abdominal regions were not significantly different between apoE-/- mice deficient in SAA1.1 and SAA2.1 and apoE-/- mice expressing SAA1.1 and SAA2.1 in either sex. To accelerate lesion formation, mice were fed a Western diet for 12 weeks. SAA deficiency had effect neither on diet-induced alterations in plasma cholesterol, triglyceride, or cytokine concentrations nor on aortic atherosclerotic lesion areas in either male or female mice. In addition, SAA deficiency in male mice had no effect on lesion areas or macrophage accumulation in the aortic roots. CONCLUSIONS The absence of endogenous SAA1.1 and 2.1 does not affect atherosclerotic lipid deposition in apolipoprotein E-deficient mice fed either normal or Western diets.
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Affiliation(s)
- Maria C De Beer
- From the Graduate Center for Nutritional Science (M.C.D.B., J.M.W., V.P.N., A.J., P.S., J.C.T., D.R.v.d.W., L.R.T., N.R.W., F.C.D.B.), Saha Cardiovascular Research Center (M.C.D.B., J.M.W., V.P.N., D.L.R., D.A.H., A.B., A.J., P.S., J.C.T., D.R.v.d.W., L.R.T., A.D., N.R.W., F.C.D.B.), and the Departments of Physiology (M.C.D.B.) and Internal Medicine (J.M.W., V.P.N., D.L.R., D.A.H., A.B., A.J., P.S., J.C.T., D.R.v.d.W., L.R.T., A.D., N.R.W., F.C.D.B.), University of Kentucky Medical Center, Lexington, KY; and Department of Veterans Affairs Medical Center, Lexington, KY (D.R.v.d.W., L.R.T.)
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Rosenson RS, Brewer HB, Ansell B, Barter P, Chapman MJ, Heinecke JW, Kontush A, Tall AR, Webb NR. Translation of High-Density Lipoprotein Function Into Clinical Practice. Circulation 2013; 128:1256-67. [DOI: 10.1161/circulationaha.113.000962] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Robert S. Rosenson
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - H. Bryan Brewer
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Benjamin Ansell
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Philip Barter
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - M. John Chapman
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Jay W. Heinecke
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Anatol Kontush
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Alan R. Tall
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
| | - Nancy R. Webb
- From the Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY (R.S.R.); Cardiovascular Research Institute, MedStar Research Institute, Washington Hospital Center, Washington, DC (H.B.B.); Atherosclerosis Research Unit, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA (B.A.); Centre for Vascular Research at the University of New South Wales, Sydney, Australia (P.B.); Dyslipidemia, Atherosclerosis and Inflammation Research Unit 939, National
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De Beer MC, Wroblewski JM, Rateri DL, Howatt D, Balakrishnan A, Tannock LR, Daugherty A, De Beer FC, Webb NR. Abstract 383: Lack of Endogenous Acute Phase Serum Amyloid A Does Not Impact Atherosclerotic Lipid Deposition in ApoE-/- Mice. Arterioscler Thromb Vasc Biol 2013. [DOI: 10.1161/atvb.33.suppl_1.a383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inflammation is involved in all stages of the development of an atherosclerotic plaque. Serum amyloid A (SAA), a marker of inflammation, is a well-known predictor of increased cardiovascular risk. Although elevated levels of plasma SAA have been associated with increased atherosclerosis, the role of SAA in the pathogenesis of atherosclerosis remains obscure. To investigate the impact of endogenous SAA in the etiology of atherosclerosis we bred mice lacking both major acute phase SAA isoforms SAA1.1 and SAA2.1 to apoE-/- mice. Both strains were in the C57BL/6 background. For ease of terminology we refer to these mice as SAAKO and apoE-/- mice. Aortic atherosclerotic lesion areas were quantified by en face analysis in male and female mice fed normal chow for 12 months. Although female mice weighed less and had lower plasma lipid levels than male mice, the absence of SAA did not affect plasma lipid concentrations or lipoprotein-cholesterol profiles or the size of aortic atherosclerotic lesions of apoE-/- mice. To accelerate lesion formation, male and female apoE-/- and SAAKO mice were fed a Western diet for 12 weeks. We observed gender-related differences in body weight, weight gain and plasma lipid concentrations. However, absence of SAA in apoE-/- mice fed a diet enriched in saturated fat had no discernable effect on plasma lipid concentrations, lipoprotein-cholesterol profiles or the size of the aortic atherosclerotic lesions. Lesions in the aortic root of male mice, quantitated by oil red O staining, was also not affected by genotype.
We conclude that absence of endogenous acute phase SAA does not impact atherosclerotic lesion development in apoE-/- mice fed normal or fat-enriched diets.
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Boyanovsky BB, Bailey W, Dixon L, Shridas P, Webb NR. Group V secretory phospholipase A2 enhances the progression of angiotensin II-induced abdominal aortic aneurysms but confers protection against angiotensin II-induced cardiac fibrosis in apoE-deficient mice. Am J Pathol 2012; 181:1088-98. [PMID: 22813854 DOI: 10.1016/j.ajpath.2012.05.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 05/02/2012] [Accepted: 05/17/2012] [Indexed: 01/23/2023]
Abstract
Abdominal aortic aneurysms (AAAs) and heart failure are complex life-threatening diseases whose etiology is not completely understood. In this study, we investigated whether deficiency of group V secretory phospholipase A(2) (GV sPLA(2)) protects from experimental AAA. The impact of GV sPLA(2) deficiency on angiotensin (Ang) II-induced cardiac fibrosis was also investigated. Apolipoprotein E (apoE)(-/-) mice and apoE(-/-) mice lacking GV sPLA(2) (GV DKO) were infused with 1000 ng/kg per minute Ang II for up to 28 days. Increases in systolic blood pressure, plasma aldosterone level, and urinary and heart prostanoids were similar in apoE(-/-) and GV DKO mice after Ang II infusion. The incidence of aortic rupture in Ang II-infused GV DKO mice (10%) was significantly reduced compared with apoE(-/-) mice (29.4%). Although the incidence of AAA in GV DKO mice (81.3%) and apoE(-/-) mice (100%) was similar, the mean percentage increase in maximal luminal diameter of abdominal aortas was significantly smaller in GV DKO mice (68.5% ± 7.7%) compared with apoE(-/-) mice (92.6% ± 8.3%). Deficiency of GV sPLA(2) resulted in increased Ang II-induced cardiac fibrosis that was most pronounced in perivascular regions. Perivascular collagen, visualized by picrosirius red staining, was associated with increased TUNEL staining and increased immunopositivity for macrophages and myofibroblasts and nicotinamide adenine dinucleotide phosphate oxidase (NOX)-2 and NOX-4, respectively. Our findings indicate that GV sPLA(2) modulates pathological responses to Ang II, with different outcomes for AAA and cardiac fibrosis.
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Affiliation(s)
- Boris B Boyanovsky
- Endocrinology Division, the Department of Internal Medicine, University of Kentucky, Lexington, USA.
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Wroblewski JM, De Beer MC, Witta J, Rateri DL, Daugherty A, De Beer FC, Webb NR. Abstract 64: Serum Amyloid A Augments Angiotensin II-Induced Abdominal Aortic Aneurysm Formation in ApoE-Deficient Mice. Arterioscler Thromb Vasc Biol 2012. [DOI: 10.1161/atvb.32.suppl_1.a64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction and Objectives:
Abdominal aortic aneurysm (AAA), a major cause of death in the aged population, is characterized by vascular inflammation and matrix degradation. Proteolytic enzymes, particularly matrix metalloproteinases (MMP’s), are hypothesized to be active participants in AAA pathogenesis. Serum amyloid A (SAA) is an acute phase reactant that, unlike C-reactive protein (CRP), correlates in humans with aortic dimensions before aneurysm formation. SAA induces MMP expression in cultured cells. In this study we determined whether SAA deficiency in mice altered AAA formation in the well-established angiotensin II (Ang II) infusion model.
Methods and Results:
We confirmed that SAA induced MMP-9 and MMP-13 mRNA abundance in J774 macrophage-like cells. Furthermore, we determined for the first time that SAA enhanced MMP-2 activity in cultured mouse abdominal aorta explants. Plasma SAA increased ∼400-fold in apoE
-/-
mice 24 hours after i.p. Ang II injection (100μg/kg) and ∼12-fold after 28-day Ang II infusion (1000ng/kg/hour). SAA was detected by immunostaining in human AAA tissues and in AAAs of AngII-infused apoE
-/-
mice. Based on
in vivo
ultrasound and
ex vivo
morphological analyses, apoE
-/-
mice with targeted deletion of SAA (SAAKO; n = 20) exhibited significantly reduced AAA 28 days after Ang II infusion compared to apoE
-/-
mice that were wild type for SAA (SAAWT; n = 20), despite a modest, but significant increase in the hypertensive response to Ang II. Although the incidence of aortic rupture in SAAKO mice (15%) and SAAWT mice (20%) were similar, the majority of ruptures (75%) in SAAWT mice occurred in the abdominal region, whereas all of the ruptures in the SAAKO mice occurred in the thoracic region. Atherosclerotic lesion area on the luminal surface of the aortic arch was similar in SAAKO and SAAWT mice after Ang II infusion.
Conclusion:
Our finding that SAA plays a role in experimental AAA may be pertinent to human studies correlating indexed aortic diameter with plasma SAA concentrations.
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Affiliation(s)
| | | | - Jassir Witta
- Internal Medicine, Univ of Kentucky, Lexington, KY
| | | | | | | | - Nancy R Webb
- Internal Medicine, Univ of Kentucky, Lexington, KY
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Boyanovsky BB, Bailey W, Dixon L, Webb NR. Abstract 84: Group V Secretory Phospholipase A2 Enhances the Progression of Angiotensin II-Induced Abdominal Aortic Aneurysms but Confers Protection Against Angiotensin II-Induced Cardiac Fibrosis in ApoE-Deficient Mice. Arterioscler Thromb Vasc Biol 2012. [DOI: 10.1161/atvb.32.suppl_1.a84] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective—
Abdominal aortic aneurysms (AAAs) and heart failure are complex life-threatening diseases whose etiology is not completely understood. We recently reported that deficiency of group X secretory phospholipase A2 (GX sPLA2) reduces abdominal aortic aneurysm (AAA) formation in apoE
-/-
mice infused with angiotensin II. In this study, we investigated whether deficiency of a related enzyme, GV sPLA2, also protects mice from experimental AAA. The impact of GV sPLA2 deficiency on Ang II-induced cardiac fibrosis was also assessed.
Methods and results—
ApoE
-/-
mice and apoE
-/-
mice lacking GV sPLA2 (GV DKO) were infused with 1000 ng/kg/min Ang II for up to 28 days. Increases in systolic blood pressure, urinary prostanoids, and plasma aldosterone were similar in apoE
-/-
and GV DKO mice after Ang II infusion. The incidence of aortic rupture in Ang II-infused GV DKO mice (10%) was significantly lower compared to apoE
-/-
mice (30%). Although the overall incidence of AAA in GV DKO mice (∼81.25%) and apoE
-/-
mice (100%) was similar, the mean percent increase in maximal luminal diameter of abdominal aortas was significantly smaller in GV DKO mice (68.5±7.7%) compared to apoE
-/-
mice (92.6±8.3%). Deficiency of GV sPLA2 resulted in increased Ang II-induced cardiac fibrosis that was most pronounced in perivascular regions. Perivascular collagen, visualized by picrosirius red staining, was associated with increased TUNEL staining and increased immunopositivity for macrophage and myofibroblast cells and NOX-2 and NOX-4.
Conclusion—
Our findings indicate that GV sPLA2 modulates pathological responses to Ang II, with different outcomes for AAA and cardiac fibrosis. These data have important implications for sPLA2 inhibitors that are currently being developed for clinical use.
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Affiliation(s)
| | | | | | - Nancy R Webb
- Internal Medicine, Univ of Kentucky, Lexington, KY
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Ji A, Wroblewski JM, Webb NR, van der Westhuyzen DR. Abstract 167: PLTP Acts in Concert with SAA to Reduce Plasma HDL Levels in Mice and Modulates Nascent HDL Formation in Hepatocytes. Arterioscler Thromb Vasc Biol 2012. [DOI: 10.1161/atvb.32.suppl_1.a167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Phospholipid transfer protein (PLTP), which binds phospholipids and facilitates their transfer between lipoproteins in plasma, plays a key role in lipoprotein remodeling. PLTP levels increase during acute inflammation and increased PLTP activity is associated with the inflammatory markers C-reactive protein (CRP) and serum amyloid A (SAA) as seen in patients with type 2 diabetes and cardiovascular disease. SAA, an HDL apolipoprotein, is highly induced during inflammation. In this study we investigated whether HDL remodeling by PLTP is affected by SAA, and the significance of PLTP on HDL biogenesis. Over-expression of PLTP in mice using an adenoviral vector reduced HDL-C and phospholipid (PL) in a dose dependent manner with the liberation of lipid-poor apoA-I. Co-expression of PLTP and SAA produced a significantly greater reduction in HDL-C and PL than expression of either PLTP or SAA alone. Studies were carried out to examine the lipidation of apoA-I and formation of nascent HDL particles by primary mouse hepatocytes. Over-expression of PLTP in hepatocytes markedly affected the levels as well as the species of nascent HDL particles produced by cells. Although the formation of smaller nascent HDLs was reduced by PLTP, the formation of the larger HDLs was increased. PLTP expression in hepatocytes did not change ABCA1 levels. Co-expression of SAA with PLTP exerted only a modest effect on the levels and types of HDL generated in the presence of PLTP. Our findings suggest that the remodeling of plasma HDL by PLTP and SAA contributes to the reduced HDL-C levels observed during inflammation. PLTP also significantly affects apoA-I lipidation and nascent HDL biogenesis in hepatocytes.
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Affiliation(s)
- Ailing Ji
- Internal medicine, Univ of Kentucky, Lexington, KY
| | | | - Nancy R Webb
- Internal medicine, Univ of Kentucky, Lexington, KY
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Shridas P, Zahoor L, Bailey W, Forrest K, Webb NR. Abstract 143: Group X Secretory Phospholipase A2 Regulates Insulin Secretion by Mouse Pancreatic Beta Cells. Arterioscler Thromb Vasc Biol 2012. [DOI: 10.1161/atvb.32.suppl_1.a143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background:
Group X secretory phospholipase A2 (GX sPLA2) potently releases arachidonic acid (AA) from the plasma membrane of intact cells. AA is a precursor of bioactive prostaglandins that are known to modulate insulin secretion by β-islet cells. C57BL/6 mice deficient in GX sPLA2 (GX KO) are protected from age-related defect in glucose tolerance. GX sPLA2 is expressed in mouse pancreatic islet cells. In this study we tested the hypothesis that GX sPLA2 regulates pancreatic insulin secretion.
Methods and results:
Glucose stimulated insulin secretion (GSIS) was measured in vivo in WT and GX KO mice and ex vivo using pancreatic islet cells isolated from WT and GX KO mice. To complement these studies, GSIS was also assessed in vitro using Min6 pancreatic beta cell lines with or without GX sPLA2 overexpression. GSIS was significantly increased in GX KO mice compared to WT mice, and in islet cells isolated from GX KO mice compared to WT mice. Consistent with this finding, Min6 cells overexpressing GX sPLA2 demonstrated significantly decreased GSIS compared to control cells. Expression of ABCA1 and ABCG1 mRNAs were significantly upregulated in islet cells from GX KO mice compared to WT mice, consistent with our previous report that GX sPLA2 negatively regulates LXR activity. However, there was no significant difference in cholesterol content between islets from WT and GX KO mice suggesting that altered LXR activity may not be the mechanism. Min6 cells overexpressing GX sPLA2 secrete significantly increased levels of PGE2- a known negative regulator of GSIS, in the medium compared to control cells. Treatment of these cells with NS398- an inhibitor of COX2 enzyme, abolished the decrease in GSIS shown by these cells.
Conclusions:
We conclude that GX sPLA2 plays a previously unrecognized role in negatively regulating pancreatic insulin secretion most likely by enhancing PGE2 production.
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Ji A, Wroblewski JM, Cai L, de Beer MC, Webb NR, van der Westhuyzen DR. Nascent HDL formation in hepatocytes and role of ABCA1, ABCG1, and SR-BI. J Lipid Res 2011; 53:446-455. [PMID: 22190590 DOI: 10.1194/jlr.m017079] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To study the mechanisms of hepatic HDL formation, we investigated the roles of ABCA1, ABCG1, and SR-BI in nascent HDL formation in primary hepatocytes isolated from mice deficient in ABCA1, ABCG1, or SR-BI and from wild-type (WT) mice. Under basal conditions, in WT hepatocytes, cholesterol efflux to exogenous apoA-I was accompanied by conversion of apoA-I to HDL-sized particles. LXR activation by T0901317 markedly enhanced the formation of larger HDL-sized particles as well as cellular cholesterol efflux to apoA-I. Glyburide treatment completely abolished the formation of 7.4 nm diameter and greater particles but led to the formation of novel 7.2 nm-sized particles. However, cells lacking ABCA1 failed to form such particles. ABCG1-deficient cells showed similar capacity to efflux cholesterol to apoA-I and to form nascent HDL particles compared with WT cells. Cholesterol efflux to apoA-I and nascent HDL formation were slightly but significantly enhanced in SR-BI-deficient cells compared with WT cells under basal but not LXR activated conditions. As in WT but not in ABCA1-deficient hepatocytes, 7.2 nm-sized particles generated by glyburide treatment were also detected in ABCG1-deficient and SR-BI-deficient hepatocytes. Our data indicate that hepatic nascent HDL formation is highly dependent on ABCA1 but not on ABCG1 or SR-BI.
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Affiliation(s)
- Ailing Ji
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Joanne M Wroblewski
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Lei Cai
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Maria C de Beer
- Physiology, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Nancy R Webb
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Deneys R van der Westhuyzen
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY; Molecular and Cellular Biochemistry and Physiology, University of Kentucky, Lexington, KY; Department of Veterans Affairs Medical Center, Lexington, KY.
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Wroblewski JM, Jahangiri A, Ji A, de Beer FC, van der Westhuyzen DR, Webb NR. Nascent HDL formation by hepatocytes is reduced by the concerted action of serum amyloid A and endothelial lipase. J Lipid Res 2011; 52:2255-2261. [PMID: 21957202 DOI: 10.1194/jlr.m017681] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inflammation is associated with significant decreases in plasma HDL-cholesterol (HDL-C) and apoA-I levels. Endothelial lipase (EL) is known to be an important determinant of HDL-C in mice and in humans and is upregulated during inflammation. In this study, we investigated whether serum amyloid A (SAA), an HDL apolipoprotein highly induced during inflammation, alters the ability of EL to metabolize HDL. We determined that EL hydrolyzes SAA-enriched HDL in vitro without liberating lipid-free apoA-I. Coexpression of SAA and EL in mice by adenoviral vector produced a significantly greater reduction in HDL-C and apoA-I than a corresponding level of expression of either SAA or EL alone. The loss of HDL occurred without any evidence of HDL remodeling to smaller particles that would be expected to have more rapid turnover. Studies with primary hepatocytes demonstrated that coexpression of SAA and EL markedly impeded ABCA1-mediated lipidation of apoA-I to form nascent HDL. Our findings suggest that a reduction in nascent HDL formation may be partly responsible for reduced HDL-C during inflammation when both EL and SAA are known to be upregulated.
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Affiliation(s)
- Joanne M Wroblewski
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and
| | - Anisa Jahangiri
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and
| | - Ailing Ji
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and
| | - Frederick C de Beer
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and; Department of Veterans Affairs Medical Center, Lexington, KY 40511
| | - Deneys R van der Westhuyzen
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and; Department of Veterans Affairs Medical Center, Lexington, KY 40511
| | - Nancy R Webb
- Department of Internal Medicine, Endocrinology Division and Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington, KY 40536; and.
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Shridas P, Bailey WM, Talbott KR, Oslund RC, Gelb MH, Webb NR. Group X secretory phospholipase A2 enhances TLR4 signaling in macrophages. J Immunol 2011; 187:482-9. [PMID: 21622863 DOI: 10.4049/jimmunol.1003552] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Secretory phospholipase A(2)s (sPLA(2)) hydrolyze glycerophospholipids to liberate lysophospholipids and free fatty acids. Although group X (GX) sPLA(2) is recognized as the most potent mammalian sPLA(2) in vitro, its precise physiological function(s) remains unclear. We recently reported that GX sPLA(2) suppresses activation of the liver X receptor in macrophages, resulting in reduced expression of liver X receptor-responsive genes including ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), and a consequent decrease in cellular cholesterol efflux and increase in cellular cholesterol content (Shridas et al. 2010. Arterioscler. Thromb. Vasc. Biol. 30: 2014-2021). In this study, we provide evidence that GX sPLA(2) modulates macrophage inflammatory responses by altering cellular cholesterol homeostasis. Transgenic expression or exogenous addition of GX sPLA(2) resulted in a significantly higher induction of TNF-α, IL-6, and cyclooxygenase-2 in J774 macrophage-like cells in response to LPS. This effect required GX sPLA(2) catalytic activity, and was abolished in macrophages that lack either TLR4 or MyD88. The hypersensitivity to LPS in cells overexpressing GX sPLA(2) was reversed when cellular free cholesterol was normalized using cyclodextrin. Consistent with results from gain-of-function studies, peritoneal macrophages from GX sPLA(2)-deficient mice exhibited a significantly dampened response to LPS. Plasma concentrations of inflammatory cytokines were significantly lower in GX sPLA(2)-deficient mice compared with wild-type mice after LPS administration. Thus, GX sPLA(2) amplifies signaling through TLR4 by a mechanism that is dependent on its catalytic activity. Our data indicate this effect is mediated through alterations in plasma membrane free cholesterol and lipid raft content.
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Affiliation(s)
- Preetha Shridas
- University of Kentucky Medical Center, Lexington, KY 40536, USA.
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Ji A, Meyer JM, Cai L, Akinmusire A, de Beer MC, Webb NR, van der Westhuyzen DR. Scavenger receptor SR-BI in macrophage lipid metabolism. Atherosclerosis 2011; 217:106-12. [PMID: 21481393 DOI: 10.1016/j.atherosclerosis.2011.03.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 03/07/2011] [Accepted: 03/11/2011] [Indexed: 12/15/2022]
Abstract
OBJECTIVE To investigate the mechanisms by which macrophage scavenger receptor BI (SR-BI) regulates macrophage cholesterol homeostasis and protects against atherosclerosis. METHODS AND RESULTS The expression and function of SR-BI was investigated in cultured mouse bone marrow-derived macrophages (BMM). SR-BI, the other scavenger receptors SRA and CD36 and the ATP-binding cassette transporters ABCA1 and ABCG1 were each distinctly regulated during BMM differentiation. SR-BI levels increased transiently to significant levels during culture. SR-BI expression in BMM was reversibly down-regulated by lipid loading with modified LDL; SR-BI was shown to be present both on the cell surface as well as intracellularly. BMM exhibited selective HDL CE uptake, however, this was not dependent on SR-BI or another potential candidate glycosylphosphatidylinositol anchored high density lipoprotein binding protein 1 (GPIHBP1). SR-BI played a significant role in facilitating bidirectional cholesterol flux in non lipid-loaded cells. SR-BI expression enhanced both cell cholesterol efflux and cholesterol influx from HDL, but did not lead to altered cellular cholesterol mass. SR-BI-dependent efflux occurred to larger HDL particles but not to smaller HDL(3). Following cholesterol loading, ABCA1 and ABCG1 were up-regulated and served as the major contributors to cholesterol efflux, while SR-BI expression was down-regulated. CONCLUSION Our results suggest that SR-BI plays a significant role in macrophage cholesterol flux that may partly account for its effects on atherogenesis.
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Affiliation(s)
- Ailing Ji
- Department of Internal Medicine, University of Kentucky, Lexington, KY 40536, USA.
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de Beer MC, Ji A, Jahangiri A, Vaughan AM, de Beer FC, van der Westhuyzen DR, Webb NR. ATP binding cassette G1-dependent cholesterol efflux during inflammation. J Lipid Res 2010; 52:345-53. [PMID: 21138980 DOI: 10.1194/jlr.m012328] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
ATP binding cassette transporter G1 (ABCG1) mediates the transport of cellular cholesterol to HDL, and it plays a key role in maintaining macrophage cholesterol homeostasis. During inflammation, HDL undergoes substantial remodeling, acquiring lipid changes and serum amyloid A (SAA) as a major apolipoprotein. In the current study, we investigated whether remodeling of HDL that occurs during acute inflammation impacts ABCG1-dependent efflux. Our data indicate that lipid free SAA acts similarly to apolipoprotein A-I (apoA-I) in mediating sequential efflux from ABCA1 and ABCG1. Compared with normal mouse HDL, acute phase (AP) mouse HDL containing SAA exhibited a modest but significant 17% increase in ABCG1-dependent efflux. Interestingly, AP HDL isolated from mice lacking SAA (SAAKO mice) was even more effective in promoting ABCG1 efflux. Hydrolysis with Group IIA secretory phospholipase A(2) (sPLA(2)-IIA) significantly reduced the ability of AP HDL from SAAKO mice to serve as a substrate for ABCG1-mediated cholesterol transfer, indicating that phospholipid (PL) enrichment, and not the presence of SAA, is responsible for alterations in efflux. AP human HDL, which is not PL-enriched, was somewhat less effective in mediating ABCG1-dependent efflux compared with normal human HDL. Our data indicate that inflammatory remodeling of HDL impacts ABCG1-dependent efflux independent of SAA.
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Affiliation(s)
- Maria C de Beer
- Departments of Physiology, University of Kentucky Medical Center, Lexington, KY, USA.
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Shridas P, Bailey WM, Gizard F, Oslund RC, Gelb MH, Bruemmer D, Webb NR. Group X secretory phospholipase A2 negatively regulates ABCA1 and ABCG1 expression and cholesterol efflux in macrophages. Arterioscler Thromb Vasc Biol 2010; 30:2014-21. [PMID: 20844270 DOI: 10.1161/atvbaha.110.210237] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE GX sPLA(2) potently hydrolyzes plasma membranes to generate lysophospholipids and free fatty acids; it has been implicated in inflammatory diseases, including atherosclerosis. To identify a novel role for group X (GX) secretory phospholipase A(2) (sPLA(2)) in modulating ATP binding casette transporter A1 (ABCA1) and ATP binding casette transporter G1 (ABCG1) expression and, therefore, macrophage cholesterol efflux. METHODS AND RESULTS The overexpression or exogenous addition of GX sPLA(2) significantly reduced ABCA1 and ABCG1 expression in J774 macrophage-like cells, whereas GX sPLA(2) deficiency in mouse peritoneal macrophages was associated with enhanced expression. Altered ABC transporter expression led to reduced cholesterol efflux in GX sPLA(2)-overexpressing J774 cells and increased efflux in GX sPLA(2)-deficient mouse peritoneal macrophages. Gene regulation was dependent on GX sPLA(2) catalytic activity, mimicked by arachidonic acid and abrogated when liver X receptor (LXR)α/β expression was suppressed, and partially reversed by the LXR agonist T0901317. Reporter assays indicated that GX sPLA(2) suppresses the ability of LXR to transactivate its promoters through a mechanism involving the C-terminal portion of LXR spanning the ligand-binding domain. CONCLUSIONS GX sPLA(2) modulates gene expression in macrophages by generating lipolytic products that suppress LXR activation. GX sPLA(2) may play a previously unrecognized role in atherosclerotic lipid accumulation by negatively regulating the genes critical for cellular cholesterol efflux.
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Affiliation(s)
- Preetha Shridas
- Graduate Center for Nutritional Sciences, Saha Cardiovascular Research Center, University of Kentucky Medical Center, Lexington 40536-0200, USA
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Zack M, Boyanovsky BB, Shridas P, Bailey W, Forrest K, Howatt DA, Gelb MH, de Beer FC, Daugherty A, Webb NR. Group X secretory phospholipase A(2) augments angiotensin II-induced inflammatory responses and abdominal aortic aneurysm formation in apoE-deficient mice. Atherosclerosis 2010; 214:58-64. [PMID: 20833395 DOI: 10.1016/j.atherosclerosis.2010.08.054] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Revised: 07/15/2010] [Accepted: 08/09/2010] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Abdominal aortic aneurysm (AAA) is a complex vascular disease characterized by matrix degradation and inflammation and is a major cause of mortality in older men. Specific interventions that prevent AAA progression remain to be identified. In this study, we tested the hypothesis that Group X secretory phospholipase A(2) (GX sPLA(2)), an enzyme implicated in inflammatory processes, mediates AAA. METHODS AND RESULTS GX sPLA(2) was detected by immunostaining in human aneurysmal tissue and in angiotensin II (Ang II)-induced AAAs in apolipoprotein E-deficient (apoE(-/-)) mice. GX sPLA(2) mRNA was increased significantly (11-fold) in abdominal aortas of apoE(-/-) mice in response to Ang II infusion. To define the role of GX sPLA(2) in experimental AAAs, apoE(-/-) and apoE(-/-) x GX sPLA(2)(-/-) (GX DKO) mice were infused with Ang II for either 10 (n=7) or 28 (n=24-26) days. Deficiency of GX sPLA(2) significantly reduced the incidence and severity of AAAs, as assessed by ultrasound measurements in vivo of aortic lumens and by computer-assisted morphometric analyses ex vivo of external diameter. Results from gene expression profiling indicated that the expression of specific matrix metalloproteinases and inflammatory mediators was blunted in aortas from GX DKO mice compared to apoE(-/-) mice after 10-day Ang II infusion. Ang II induction of cyclooxygenase-2, interleukin-6, matrix metalloproteinase (MMP)-2, MMP-13 and MMP-14 was reduced significantly in GX DKO mice compared to apoE(-/-) mice. CONCLUSION GX sPLA(2) promotes Ang II-induced pathological responses leading to AAA formation.
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Affiliation(s)
- Melissa Zack
- Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY 40536-0200, USA
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de Beer MC, Webb NR, Wroblewski JM, Noffsinger VP, Rateri DL, Ji A, van der Westhuyzen DR, de Beer FC. Impact of serum amyloid A on high density lipoprotein composition and levels. J Lipid Res 2010; 51:3117-25. [PMID: 20667817 DOI: 10.1194/jlr.m005413] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serum amyloid A (SAA) is an acute-phase protein mainly associated with HDL. To study the role of SAA in mediating changes in HDL composition and metabolism during inflammation, we generated mice in which the two major acute-phase SAA isoforms, SAA1.1 and SAA2.1, were deleted [SAA knockout (SAAKO) mice], and induced an acute phase to compare lipid and apolipoprotein parameters between wild-type (WT) and SAAKO mice. Our data indicate that SAA does not affect apolipoprotein A-I (apoA-I) levels or clearance under steady-state conditions. HDL and plasma triglyceride levels following lipopolysaccharide administration, as well as the decline in liver expression of apoA-I and apoA-II, did not differ between both groups of mice. The expected size increase of WT acute-phase HDL was surprisingly also seen in SAAKO acute-phase HDL despite the absence of SAA. HDLs from both mice showed increased phospholipid and unesterified cholesterol content during the acute phase. We therefore conclude that in the mouse, SAA does not impact HDL levels, apoA-I clearance, or HDL size during the acute phase and that the increased size of acute-phase HDL in mice is associated with an increased content of surface lipids, particularly phospholipids, and not surface proteins. These data need to be transferred to humans with caution due to differences in apoA-I structure and remodeling functions.
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Affiliation(s)
- Maria C de Beer
- Graduate Center for Nutritional Science, University of Kentucky Medical Center, Lexington, KY 40536, USA.
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Abstract
Studies in vitro indicate that group X secretory phospholipase A(2) (GX sPLA(2)) potently releases arachidonic acid (AA) and lysophosphatidylcholine from mammalian cell membranes. To define the function of GX sPLA(2) in vivo, our laboratory recently generated C57BL/6 mice with targeted deletion of GX sPLA(2) (GX(-/-) mice). When fed a normal rodent diet, GX(-/-) mice gained significantly more weight and had increased adiposity compared to GX(+/+) mice, which was not attributable to alterations in food consumption or energy expenditure. When treated with adipogenic stimuli ex vivo, stromal vascular cells isolated from adipose tissue of GX(-/-) mice accumulated significantly more (20%) triglyceride compared to cells from GX(+/+) mice. Conversely, overexpression of GX sPLA(2), but not catalytically inactive GX sPLA(2), resulted in a significant 50% reduction in triglyceride accumulation in OP9 adipocytes. The induction of genes encoding adipogenic proteins (PPARγ, SREBP-1c, SCD1, and FAS) was also significantly blunted by 50-80% in OP9 cells overexpressing GX sPLA(2). Activation of the liver X receptor (LXR), a nuclear receptor known to up-regulate adipogenic gene expression, was suppressed in 3T3-L1 and OP9 cells when GX sPLA(2) was overexpressed. Thus, hydrolytic products generated by GX sPLA(2) negatively regulate adipogenesis, possibly by suppressing LXR activation.
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Affiliation(s)
- Xia Li
- Graduate Center for Nutritional Sciences, University of Kentucky Medical Center, Lexington, KY 40536-0200, USA
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