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Moghimpour Bijani F, Vallejo JG, Rezaei N. Toll-like receptor signaling pathways in cardiovascular diseases: challenges and opportunities. Int Rev Immunol 2013; 31:379-95. [PMID: 23083347 DOI: 10.3109/08830185.2012.706761] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Toll-like receptors (TLRs), a family of surface molecules, are involved in innate immune responses. Recent studies indicated that TLRs play a critical role in inflammatory responses to exogenous and endogenous triggers. This article focuses on probable effects of TLRs in the morbidity of cardiovascular events, e.g., ischemic reperfusion (I/R) injury and atherosclerosis. TLR2 and TLR4 have been shown to have the most fundamental role in promoting cytokine production and subsequent inflammatory damages in these states. Blockade of these receptors may be beneficial in both preventing the occurrence and decreasing the complications in cardiovascular events. However, controversies exist on the certainty of this beneficial effect; therefore, additional studies are needed.
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Affiliation(s)
- Faezeh Moghimpour Bijani
- Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
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202
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Blomkalns AL, Gavrila D, Thomas M, Neltner BS, Blanco VM, Benjamin SB, McCormick ML, Stoll LL, Denning GM, Collins SP, Qin Z, Daugherty A, Cassis LA, Thompson RW, Weiss RM, Lindower PD, Pinney SM, Chatterjee T, Weintraub NL. CD14 directs adventitial macrophage precursor recruitment: role in early abdominal aortic aneurysm formation. J Am Heart Assoc 2013; 2:e000065. [PMID: 23537804 PMCID: PMC3647288 DOI: 10.1161/jaha.112.000065] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Background Recruitment of macrophage precursors to the adventitia plays a key role in the pathogenesis of abdominal aortic aneurysms (AAAs), but molecular mechanisms remain undefined. The innate immune signaling molecule CD14 was reported to be upregulated in adventitial macrophages in a murine model of AAA and in monocytes cocultured with aortic adventitial fibroblasts (AoAf) in vitro, concurrent with increased interleukin‐6 (IL‐6) expression. We hypothesized that CD14 plays a crucial role in adventitial macrophage precursor recruitment early during AAA formation. Methods and Results CD14−/− mice were resistant to AAA formation induced by 2 different AAA induction models: aortic elastase infusion and systemic angiotensin II (AngII) infusion. CD14 gene deletion led to reduced aortic macrophage infiltration and diminished elastin degradation. Adventitial monocyte binding to AngII‐infused aorta in vitro was dependent on CD14, and incubation of human acute monocytic leukemia cell line‐1 (THP‐1) monocytes with IL‐6 or conditioned medium from perivascular adipose tissue (PVAT) upregulated CD14 expression. Conditioned medium from AoAf and PVAT induced CD14‐dependent monocyte chemotaxis, which was potentiated by IL‐6. CD14 expression in aorta and plasma CD14 levels were increased in AAA patients compared with controls. Conclusions These findings link CD14 innate immune signaling via a novel IL‐6 amplification loop to adventitial macrophage precursor recruitment in the pathogenesis of AAA.
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Affiliation(s)
- Andra L Blomkalns
- Division of Cardiovascular Diseases, University of Cincinnati, College of Medicine, Cincinnati, OH 45267-0769, USA.
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203
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Speer T, Rohrer L, Blyszczuk P, Shroff R, Kuschnerus K, Kränkel N, Kania G, Zewinger S, Akhmedov A, Shi Y, Martin T, Perisa D, Winnik S, Müller MF, Sester U, Wernicke G, Jung A, Gutteck U, Eriksson U, Geisel J, Deanfield J, von Eckardstein A, Lüscher TF, Fliser D, Bahlmann FH, Landmesser U. Abnormal high-density lipoprotein induces endothelial dysfunction via activation of Toll-like receptor-2. Immunity 2013; 38:754-68. [PMID: 23477738 DOI: 10.1016/j.immuni.2013.02.009] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 02/11/2013] [Indexed: 01/06/2023]
Abstract
Endothelial injury and dysfunction (ED) represent a link between cardiovascular risk factors promoting hypertension and atherosclerosis, the leading cause of death in Western populations. High-density lipoprotein (HDL) is considered antiatherogenic and known to prevent ED. Using HDL from children and adults with chronic kidney dysfunction (HDL(CKD)), a population with high cardiovascular risk, we have demonstrated that HDL(CKD) in contrast to HDL(Healthy) promoted endothelial superoxide production, substantially reduced nitric oxide (NO) bioavailability, and subsequently increased arterial blood pressure (ABP). We have identified symmetric dimethylarginine (SDMA) in HDL(CKD) that causes transformation from physiological HDL into an abnormal lipoprotein inducing ED. Furthermore, we report that HDL(CKD) reduced endothelial NO availability via toll-like receptor-2 (TLR-2), leading to impaired endothelial repair, increased proinflammatory activation, and ABP. These data demonstrate how SDMA can modify the HDL particle to mimic a damage-associated molecular pattern that activates TLR-2 via a TLR-1- or TLR-6-coreceptor-independent pathway, linking abnormal HDL to innate immunity, ED, and hypertension.
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Affiliation(s)
- Thimoteus Speer
- Cardiovascular Center, Cardiology, University Hospital Zurich and Cardiovascular Research, Institute of Physiology, University of Zurich, Zurich, Switzerland.
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204
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Chatzidimitriou D, Kirmizis D, Gavriilaki E, Chatzidimitriou M, Malisiovas N. Atherosclerosis and infection: is the jury still not in? Future Microbiol 2013; 7:1217-30. [PMID: 23030426 DOI: 10.2217/fmb.12.87] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.
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205
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Lundberg AM, Ketelhuth DF, Johansson ME, Gerdes N, Liu S, Yamamoto M, Akira S, Hansson GK. Toll-like receptor 3 and 4 signalling through the TRIF and TRAM adaptors in haematopoietic cells promotes atherosclerosis. Cardiovasc Res 2013; 99:364-73. [DOI: 10.1093/cvr/cvt033] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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206
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Richards MR, Black AS, Bonnet DJ, Barish GD, Woo CW, Tabas I, Curtiss LK, Tobias PS. The LPS2 mutation in TRIF is atheroprotective in hyperlipidemic low density lipoprotein receptor knockout mice. Innate Immun 2013; 19:20-9. [PMID: 22637968 PMCID: PMC3434265 DOI: 10.1177/1753425912447130] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Signaling through MyD88, an adaptor utilized by all TLRs except TLR3, is pro-atherogenic; however, it is unknown whether signaling through TIR-domain-containing adaptor-inducing interferon-β (TRIF), an adaptor used only by TLRs 3 and 4, is relevant to atherosclerosis. We determined that the TRIF(Lps2) lack-of-function mutation was atheroprotective in hyperlipidemic low density lipoprotein (LDL) receptor knockout (LDLr(-/-)) mice. LDLr(-/-) mice were crossed with either TRIF(Lps2) or TLR3 knockout mice. After feeding an atherogenic diet for 10-15 wks, atherosclerotic lesions in the heart sinus and aorta were quantitated. LDLr(-/-) mice with TRIF(Lps2) were significantly protected from atherosclerosis. TRIF(Lps2) led to a reduction in cytokines secreted from peritoneal macrophages (M) in response to hyperlipidemia. Moreover, heart sinus valves from hyperlipidemic LDLr(-/-) TRIF(Lps2) mice had significantly fewer lesional M. However, LDLr(-/-) mice deficient in TLR3 showed some enhancement of disease. Collectively, these data suggest that hyperlipidemia resulting in endogenous activation of the TRIF signaling pathway from TLR4 leads to pro-atherogenic events.
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Affiliation(s)
- M. Rachel Richards
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037
| | - Audrey S. Black
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037
| | - David J. Bonnet
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037
| | - Grant D. Barish
- Gene Expression Laboratory, the Salk Institute, La Jolla, CA 92037
| | - Connie W. Woo
- Department of Medicine, Columbia University, 630 West 168 St., New York, NY 10032
| | - Ira Tabas
- Department of Medicine, Columbia University, 630 West 168 St., New York, NY 10032
| | - Linda K. Curtiss
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037
| | - Peter S. Tobias
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037
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207
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Kim M, Choi SH, Jin YB, Lee HJ, Ji YH, Kim J, Lee YS, Lee YJ. The effect of oxidized low-density lipoprotein (ox-LDL) on radiation-induced endothelial-to-mesenchymal transition. Int J Radiat Biol 2013; 89:356-63. [PMID: 23289363 DOI: 10.3109/09553002.2013.763193] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE Radiation-induced cardiovascular disease is a potentially severe side-effect of thoracic radiotherapy treatment. Clinically, this delayed side-effect presents as a form of accelerated atherosclerosis several years after irradiation. As general endothelial dysfunction is known to be an initiating event in radiation-induced vascular damage, we examined the effects of radiation on endothelial cells in radiation-induced atherosclerosis. MATERIALS AND METHODS The effects of radiation on human aortic endothelial cells (HAoEC) were assessed by immunoblotting and immunofluorescence assays. Radiation-induced phenotypic changes of endothelial cells (ECs) were examined using atherosclerotic tissues of irradiated apoprotein E null (ApoE(-/-)) mice. RESULTS Radiation induced the HAoEC to undergo phenotypic conversion to form fibroblast-like cells, called the endothelial-to-mesenchymal transition (EndMT), which leads to the upregulation of mesenchymal cell markers such as alpha-smooth muscle actin (α-SMA), fibroblast specific protein-1 (FSP-1), and vimentin, and downregulation of endothelial cell-specific markers such as CD31 and vascular endothelial (VE)-cadherin. Furthermore, compared with low-density lipoprotein (LDL), oxidized low-density lipoprotein (ox-LDL) significantly augmented radiation-induced EndMT in HAoEC. These fibrotic phenotypes of ECs were found in atherosclerotic tissues of irradiated ApoE(-/-) mice with increased levels of ox-LDL. CONCLUSIONS Taken together, these observations suggest that ox-LDL accelerates radiation-induced EndMT and subsequently contributes to radiation-induced atherosclerosis, providing a novel target for the prevention of radiation-induced atherosclerosis.
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Affiliation(s)
- Miseon Kim
- Division of Radiation Effects, Korea Institute of Radiological & Medical Sciences, Seoul, Korea
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208
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Bzowska M, Nogieć A, Skrzeczyńska-Moncznik J, Mickowska B, Guzik K, Pryjma J. Oxidized LDLs inhibit TLR-induced IL-10 production by monocytes: a new aspect of pathogen-accelerated atherosclerosis. Inflammation 2013; 35:1567-84. [PMID: 22556042 PMCID: PMC3397235 DOI: 10.1007/s10753-012-9472-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is widely accepted that oxidized low-density lipoproteins and local infections or endotoxins in circulation contribute to chronic inflammatory process at all stages of atherosclerosis. The hallmark cells of atherosclerotic lesions-monocytes and macrophages-are able to detect and integrate complex signals derived from lipoproteins and pathogens, and respond with a spectrum of immunoregulatory cytokines. In this study, we show strong inhibitory effect of oxLDLs on anti-inflammatory interleukin-10 production by monocytes responding to TLR2 and TLR4 ligands. In contrast, pro-inflammatory tumor necrosis factor secretion was even slightly increased, when stimulated with lipopolysaccharide from Porphyromonas gingivalis-an oral pathogen associated with atherosclerosis. The oxLDLs modulatory activity may be explained by altered recognition of pathogen-associated molecular patterns, which involves serum proteins, particularly vitronectin. We also suggest an interaction between vitronectin receptor, CD11b, and TLR2. The presented data support a novel pathway for pathogen-accelerated atherosclerosis, which relies on oxidized low-density lipoprotein-mediated modulation of anti-inflammatory response to TLR ligands.
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Affiliation(s)
- Małgorzata Bzowska
- Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Anna Nogieć
- Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Joanna Skrzeczyńska-Moncznik
- Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Barbara Mickowska
- Malopolska Centre of Food Monitoring and Certification, Faculty of Food Technology, Agricultural University, Balicka 122, 30-149 Kraków, Poland
| | - Krzysztof Guzik
- Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Juliusz Pryjma
- Department of Immunology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
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209
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Oxidized LDLs inhibit TLR-induced IL-10 production by monocytes: a new aspect of pathogen-accelerated atherosclerosis. Inflammation 2013. [PMID: 22556042 DOI: 10.1007/s110753-012-9472-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
It is widely accepted that oxidized low-density lipoproteins and local infections or endotoxins in circulation contribute to chronic inflammatory process at all stages of atherosclerosis. The hallmark cells of atherosclerotic lesions-monocytes and macrophages-are able to detect and integrate complex signals derived from lipoproteins and pathogens, and respond with a spectrum of immunoregulatory cytokines. In this study, we show strong inhibitory effect of oxLDLs on anti-inflammatory interleukin-10 production by monocytes responding to TLR2 and TLR4 ligands. In contrast, pro-inflammatory tumor necrosis factor secretion was even slightly increased, when stimulated with lipopolysaccharide from Porphyromonas gingivalis-an oral pathogen associated with atherosclerosis. The oxLDLs modulatory activity may be explained by altered recognition of pathogen-associated molecular patterns, which involves serum proteins, particularly vitronectin. We also suggest an interaction between vitronectin receptor, CD11b, and TLR2. The presented data support a novel pathway for pathogen-accelerated atherosclerosis, which relies on oxidized low-density lipoprotein-mediated modulation of anti-inflammatory response to TLR ligands.
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210
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Abstract
The CC chemokine receptor 7 (CCR7) and its ligands CCL19 and CCL21 essentially contribute to both immunity and tolerance by directing T cells and antigen-presenting dendritic cells (DCs) to and within lymph organs. In the pathogenesis of atherosclerosis, the accumulation of cholesterol in the subendothelial space of the vessel wall represents the initial step of plaque development in which DCs acquire and process low-density lipoprotein cholesterol as antigen in the vessel wall and then migrate to draining lymph nodes and present this antigen to naive T cells. Deletion of CCR7 receptor in murine atherosclerosis not only results in a reduced atherosclerotic plaque content but also leads to a disturbed entry and exit of T cells within the inflamed vessel wall. These observations are consistent with the notion that CCR7-dependent T cell priming in secondary lymphoid organs and CCR7-dependent recirculation of T cells between secondary lymphoid organs and inflamed tissue is pivotal for atherosclerotic plaque development and may represent an interesting target for innovative immune-modulatory therapy.
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Affiliation(s)
- Bernhard Schieffer
- Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
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211
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Murumalla RK, Gunasekaran MK, Padhan JK, Bencharif K, Gence L, Festy F, Césari M, Roche R, Hoareau L. Fatty acids do not pay the toll: effect of SFA and PUFA on human adipose tissue and mature adipocytes inflammation. Lipids Health Dis 2012; 11:175. [PMID: 23259689 PMCID: PMC3551671 DOI: 10.1186/1476-511x-11-175] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 12/18/2012] [Indexed: 12/27/2022] Open
Abstract
Background On the basis that high fat diet induces inflammation in adipose tissue, we wanted to test the effect of dietary saturated and polysunsaturated fatty acids on human adipose tissue and adipocytes inflammation. Moreover we wanted to determine if TLR2 and TLR4 are involved in this pathway. Methods Human adipose tissue and adipocytes primary cultures were treated with endotoxin-free BSA conjugated with SFA (lauric acid and palmitic acid - LA and PA) and PUFA (eicosapentaeneic acid, docosahexaenoic acid and oleic acid - EPA, DHA and OA) with or without LPS. Cytokines were then assayed by ELISA (TNF-alpha, IL-6 and MCP-1). In order to determine if TLR2 and TLR4 are activated by fatty acid (FA), we used HEK-Blue cells transfected by genes from TLR2 or TLR4 pathways associated with secreted alkaline phosphatase reporter gene. Results None of the FA tested in HEK-Blue cells were able to activate TLR2 or TLR4, which is concordant with the fact that after FA treatment, adipose tissue and adipocytes cytokines levels remain the same as controls. However, all the PUFA tested: DHA, EPA and to a lesser extent OA down-regulated TNF-alpha, IL-6 and MCP-1 secretion in human adipose tissue and adipocytes cultures. Conclusions This study first confirms that FA do not activate TLR2 and TLR4. Moreover by using endotoxin-free BSA, both SFA and PUFA tested were not proinflammatory in human adipose tissue and adipocytes model. More interestingly we showed that some PUFA exert an anti-inflammatory action in human adipose tissue and adipocytes model. These results are important since they clarify the relationship between dietary fatty acids and inflammation linked to obesity.
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Affiliation(s)
- Ravi Kumar Murumalla
- GEICO-Study Group on Chronic Inflammation and Obesity, Platform 'Cyclotron Reunion Ocean Indien' CYROI, 2 Rue Maxime Rivière, Sainte-Clotilde, Reunion Island 97490, France
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212
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Toll-like receptor activity in patients with obstructive sleep apnea. Sleep Breath 2012; 17:1009-16. [DOI: 10.1007/s11325-012-0791-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 11/22/2012] [Accepted: 11/23/2012] [Indexed: 10/27/2022]
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213
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Won K, Kim SM, Lee SA, Rhim BY, Eo SK, Kim K. Multiple Signaling Molecules are Involved in Expression of CCL2 and IL-1β in Response to FSL-1, a Toll-Like Receptor 6 Agonist, in Macrophages. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2012; 16:447-53. [PMID: 23271927 PMCID: PMC3526750 DOI: 10.4196/kjpp.2012.16.6.447] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/21/2012] [Accepted: 11/26/2012] [Indexed: 12/21/2022]
Abstract
TLR6 forms a heterodimer with TLR2 and TLR4. While proinflammatory roles of TLR2 and TLR4 are well documented, the role of TLR6 in inflammation is poorly understood. In order to understand mechanisms of action of TLR6 in inflammatory responses, we investigated the effects of FSL-1, the TLR6 ligand, on expression of chemokine CCL2 and cytokine IL-1β and determined cellular factors involved in FSL-1-mediated expression of CCL2 and IL-1β in mononuclear cells. Exposure of human monocytic leukemia THP-1 cells to FSL-1 resulted not only in enhanced secretion of CCL2 and IL-1β, but also profound induction of their gene transcripts. Expression of CCL2 was abrogated by treatment with OxPAPC, a TLR-2/4 inhibitor, while treatment with OxPAPC resulted in partially inhibited expression of IL-1β. Treatment with FSL-1 resulted in enhanced phosphorylation of Akt and mitogen-activated protein kinases and activation of protein kinase C. Treatment with pharmacological inhibitors, including SB202190, SP6001250, U0126, Akt inhibitor IV, LY294002, GF109203X, and RO318220 resulted in significantly attenuated FSL-1-mediated upregulation of CCL2 and IL-1β. Our results indicate that activation of TLR6 will trigger inflammatory responses by upregulating expression of CCL2 and IL-1β via TLR-2/4, protein kinase C, PI3K-Akt, and mitogen-activated protein kinases.
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Affiliation(s)
- Keunsoo Won
- Department of Pharmacology, School of Medicine, Pusan National University, Yangsan 626-870, Korea. ; Department of Neurosurgery, School of Medicine, Konkuk University, Chungju 380-704, Korea
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214
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De Arras L, Seng A, Lackford B, Keikhaee MR, Bowerman B, Freedman JH, Schwartz DA, Alper S. An evolutionarily conserved innate immunity protein interaction network. J Biol Chem 2012; 288:1967-78. [PMID: 23209288 DOI: 10.1074/jbc.m112.407205] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The innate immune response plays a critical role in fighting infection; however, innate immunity also can affect the pathogenesis of a variety of diseases, including sepsis, asthma, cancer, and atherosclerosis. To identify novel regulators of innate immunity, we performed comparative genomics RNA interference screens in the nematode Caenorhabditis elegans and mouse macrophages. These screens have uncovered many candidate regulators of the response to lipopolysaccharide (LPS), several of which interact physically in multiple species to form an innate immunity protein interaction network. This protein interaction network contains several proteins in the canonical LPS-responsive TLR4 pathway as well as many novel interacting proteins. Using RNAi and overexpression studies, we show that almost every gene in this network can modulate the innate immune response in mouse cell lines. We validate the importance of this network in innate immunity regulation in vivo using available mutants in C. elegans and mice.
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Affiliation(s)
- Lesly De Arras
- Integrated Department of Immunology, National Jewish Health and University of Colorado, Denver, Colorado 80206, USA
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215
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Moutzouri E, Tellis CC, Rousouli K, Liberopoulos EN, Milionis HJ, Elisaf MS, Tselepis AD. Effect of simvastatin or its combination with ezetimibe on Toll-like receptor expression and lipopolysaccharide – Induced cytokine production in monocytes of hypercholesterolemic patients. Atherosclerosis 2012; 225:381-7. [PMID: 23062767 DOI: 10.1016/j.atherosclerosis.2012.08.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 07/25/2012] [Accepted: 08/25/2012] [Indexed: 02/07/2023]
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216
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Bustamante J, Tamayo E, Herreros J. Genomics in cardiovascular diseases: analysis of the importance of the toll-like receptor signaling pathway. Int J Gen Med 2012. [PMID: 23204853 PMCID: PMC3508562 DOI: 10.2147/ijgm.s33416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The development of techniques for genomics study makes it possible for us to further our knowledge about the physiopathology of various immunological or infectious diseases. These techniques improve our understanding of the development and evolution of such diseases, including those of cardiovascular origin, whilst they help to bring about the design of new therapeutic strategies. We are reviewing the genetic alterations of immunity in said field, and focusing on the signaling pathway of toll-like receptors because not only does this play a decisive role in response to microorganisms, it is also heavily involved in modulating the inflammatory response to tissue damage, a side effect of numerous cardiovascular diseases. These alterations in tissue homeostasis are present under a wide range of circumstances, such as reperfusion ischemia (myocardial infarction) phenomena, arteriosclerosis, or valvulopathy.
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Affiliation(s)
- J Bustamante
- Department of Cardiovascular Surgery, Hospital Universitario La Princesa, Madrid
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217
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Pagano S, Satta N, Werling D, Offord V, de Moerloose P, Charbonney E, Hochstrasser D, Roux-Lombard P, Vuilleumier N. Anti-apolipoprotein A-1 IgG in patients with myocardial infarction promotes inflammation through TLR2/CD14 complex. J Intern Med 2012; 272:344-57. [PMID: 22329401 DOI: 10.1111/j.1365-2796.2012.02530.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES Toll-like receptor (TLR)-mediated vascular inflammation, inducible by - amongst other factors - auto-antibodies, is increasingly recognized as a potential mediator of cardiovascular disease. We investigated whether anti-apolipoprotein (Apo)A-1 IgG was associated with a pro-inflammatory cytokine profile in myocardial infarction (MI) patients and whether anti-ApoA-1 IgG elicited a pro-inflammatory response by activating TLRs. METHODS As surrogate markers of atherosclerotic plaque vulnerability, interleukin (IL)-6, tumour necrosis factor (TNF)-α, matrix metalloproteinase (MMP)-9 and MMP-3 levels were assessed in 221 consecutive MI patients. Using human monocyte-derived macrophages (HMDMs) we investigated (i) the anti-ApoA-1 IgG interaction with TLRs using proximity ligation assay and (ii) anti-ApoA-1 IgG-dependent IL-6/TNF-α production. TLR involvement was further confirmed using HEK293-Blue TLR-2/-4 cells and by computational docking simulations. RESULTS In MI patients, anti-ApoA-1 IgG positivity was associated with higher levels of IL-6, TNF-α and MMP-9, but lower MMP-3 levels. In in vitro experiments, anti-ApoA-1 antibodies bound to HDMDs in a TLR2-dependent manner, resulting in nuclear translocation of NFκB and a significant increase in TNF-α and IL-6 production. Subsequent functional studies highlighted the importance of CD14 as co-receptor in the anti-ApoA-1 IgG-TLR2-induced cytokine production. Additional bioinformatic studies identified structural homologies between TLR2 and ApoA-1, which may explain the observed cross-reactivity between antibodies against these two molecules. CONCLUSIONS Anti-ApoA-1 IgG positivity in MI is associated with a high-risk cytokine profile. These auto-antibodies promote inflammation by stimulating the TLR2/CD14 receptor complex, probably because of molecular mimicry, which may contribute to atherosclerosis-related complications in patients.
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Affiliation(s)
- S Pagano
- Division of Laboratory Medicine, Department of Genetics and Laboratory Medicine, Geneva University Hospital, Geneva, Switzerland
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218
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Lee GL, Chang YW, Wu JY, Wu ML, Wu KK, Yet SF, Kuo CC. TLR 2 induces vascular smooth muscle cell migration through cAMP response element-binding protein-mediated interleukin-6 production. Arterioscler Thromb Vasc Biol 2012; 32:2751-60. [PMID: 22995520 DOI: 10.1161/atvbaha.112.300302] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Migration of vascular smooth muscle cells (VSMCs) from the media into intima contributes to the development of atherosclerosis. Gene deletion experiments implicate a role for toll-like receptor 2 (TLR2) in atherogenesis. However, the underlying mechanisms remain unclear. We postulate that TLR2 promotes VSMC migration by enhancing interleukin (IL)-6 production. METHODS AND RESULTS Migration assays revealed that TLR2 agonists promoted VSMC migration but not cell proliferation or viability. TLR2 deficiency or inhibition of TLR2 signaling with anti-TLR2 antibody suppressed TLR2 agonist-induced VSMC migration and IL-6 production, which was mediated via p38 mitogen-associated protein kinase and extracellular signal-regulated kinase 1/2 signaling pathways. Neutralizing anti-IL-6 antibodies impaired TLR2-mediated VSMC migration and formation of filamentous actin fiber and lamellipodia. Blockade of p38 mitogen-associated protein kinase or extracellular signal-regulated kinase 1/2 activation inhibited TLR2 agonist pam3CSK4-induced phosphorylation of cAMP response element-binding protein, which regulates IL-6 promoter activity through the cAMP response element site. Moreover, cAMP response element-binding protein small interfering RNA inhibited pam3CSK4-induced IL-6 production and VSMC migration. Additionally, Rac1 small interfering RNA inhibited pam3CSK4-induced VSMC migration but not IL-6 production. CONCLUSIONS Our results suggest that on ligand binding, TLR2 activates p38 mitogen-associated protein kinase and extracellular signal-regulated kinase 1/2 signaling in VSMCs. These signaling pathways act in concert to activate cAMP response element-binding protein and subsequent IL-6 production, which in turn promotes VSMC migration via Rac1-mediated actin cytoskeletal reorganization.
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Affiliation(s)
- Guan-Lin Lee
- Institute of Cellular and System Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan
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Hayashi C, Papadopoulos G, Gudino CV, Weinberg EO, Barth KR, Madrigal AG, Chen Y, Ning H, LaValley M, Gibson FC, Hamilton JA, Genco CA. Protective role for TLR4 signaling in atherosclerosis progression as revealed by infection with a common oral pathogen. THE JOURNAL OF IMMUNOLOGY 2012; 189:3681-8. [PMID: 22956579 DOI: 10.4049/jimmunol.1201541] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Clinical and epidemiological studies have implicated chronic infections in the development of atherosclerosis. It has been proposed that common mechanisms of signaling via TLRs link stimulation by multiple pathogens to atherosclerosis. However, how pathogen-specific stimulation of TLR4 contributes to atherosclerosis progression remains poorly understood. In this study, atherosclerosis-prone apolipoprotein-E null (ApoE(-/-)) and TLR4-deficient (ApoE(-/-)TLR4(-/-)) mice were orally infected with the periodontal pathogen Porphyromonas gingivalis. ApoE(-/-)TLR4(-/-) mice were markedly more susceptible to atherosclerosis after oral infection with P. gingivalis. Using live animal imaging, we demonstrate that enhanced lesion progression occurs progressively and was increasingly evident with advancing age. Immunohistochemical analysis of lesions from ApoE(-/-)TLR4(-/-) mice revealed an increased inflammatory cell infiltrate composed primarily of macrophages and IL-17 effector T cells (Th17), a subset linked with chronic inflammation. Furthermore, enhanced atherosclerosis in TLR4-deficient mice was associated with impaired development of Th1 immunity and regulatory T cell infiltration. In vitro studies suggest that the mechanism of TLR4-mediated protective immunity may be orchestrated by dendritic cell IL-12 and IL-10, which are prototypic Th1 and regulatory T cell polarizing cytokines. We demonstrate an atheroprotective role for TLR4 in response to infection with the oral pathogen P. gingivalis. Our results point to a role for pathogen-specific TLR signaling in chronic inflammation and atherosclerosis.
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Affiliation(s)
- Chie Hayashi
- Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Polykratis A, van Loo G, Xanthoulea S, Hellmich M, Pasparakis M. Conditional targeting of tumor necrosis factor receptor-associated factor 6 reveals opposing functions of Toll-like receptor signaling in endothelial and myeloid cells in a mouse model of atherosclerosis. Circulation 2012; 126:1739-51. [PMID: 22935568 DOI: 10.1161/circulationaha.112.100339] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Previous studies implicated Toll-like receptor signaling as a critical pathogenic pathway in atherosclerosis, but the cell-specific mechanisms by which Toll-like receptors act to control atherosclerotic plaque development remain poorly understood. METHODS AND RESULTS To study the cell-specific role of tumor necrosis factor receptor-associated factor 6 (TRAF6) in atherosclerosis, we generated ApoE(-/-) mice with endothelial cell- or myeloid cell-specific TRAF6 deficiency using Cre/LoxP-mediated gene targeting. Endothelial TRAF6 deficiency reduced atherosclerosis in female ApoE(-/-) mice by inhibiting nuclear factor-κB-dependent proinflammatory gene expression and monocyte adhesion to endothelial cells. In contrast, myeloid cell-specific TRAF6 deficiency caused exacerbated atherosclerosis, with larger plaques containing more necrotic areas in both male and female ApoE(-/-) mice. TRAF6-deficient macrophages showed impaired expression of the antiinflammatory and atheroprotective cytokine interleukin-10, elevated endoplasmic reticulum stress, increased sensitivity to oxidized low-density lipoprotein-induced apoptosis, and reduced capacity to clear apoptotic cells. Thus, the reduced antiinflammatory properties, coupled with increased sensitivity to apoptosis and impaired efferocytosis capacity of TRAF6-deficient macrophages, result in exacerbated atherosclerosis development in TRAF6(MYKO)/ApoE(-/-) mice. CONCLUSION Toll-like receptor-mediated TRAF6 signaling acts in endothelial cells to promote atherosclerosis but displays atheroprotective, antiinflammatory and prosurvival functions in myeloid cells.
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Affiliation(s)
- Apostolos Polykratis
- Institute for Genetics, University of Cologne, Zülpicher Strasse 47a, D-50674 Cologne, Germany
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Salagianni M, Galani IE, Lundberg AM, Davos CH, Varela A, Gavriil A, Lyytikäinen LP, Lehtimäki T, Sigala F, Folkersen L, Gorgoulis V, Lenglet S, Montecucco F, Mach F, Hedin U, Hansson GK, Monaco C, Andreakos E. Toll-Like Receptor 7 Protects From Atherosclerosis by Constraining “Inflammatory” Macrophage Activation. Circulation 2012; 126:952-62. [DOI: 10.1161/circulationaha.111.067678] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background
Toll-like receptors (TLRs) have long been considered to be major culprits in the development of atherosclerosis, contributing both to its progression and clinical complications. However, evidence for most TLRs beyond TLR2 and TLR4 is lacking.
Methods and Results
We used experimental mouse models, human atheroma cultures, and well-established human biobanks to investigate the role of TLR7 in atherosclerosis. We report the unexpected finding that TLR7, a receptor recognizing self–nucleic acid complexes, is protective in atherosclerosis. In
Apoe
−/−
mice, functional inactivation of TLR7 resulted in accelerated lesion development, increased stenosis, and enhanced plaque vulnerability as revealed by Doppler ultrasound and/or histopathology. Mechanistically, TLR7 interfered with macrophage proinflammatory responses to TLR2 and TLR4 ligands, reduced monocyte chemoattractant protein-1 production, and prevented expansion of Ly6C
hi
inflammatory monocytes and accumulation of inflammatory M1 macrophages into developing atherosclerotic lesions. In human carotid endarterectomy specimens TLR7 levels were consistently associated with an M2 anti-inflammatory macrophage signature (interleukin [IL]-10, IL-1RA, CD163, scavenger and C-type lectin receptors) and collagen genes, whereas they were inversely related or unrelated to proinflammatory mediators (IL-12/IL-23, interferon beta, interferon gamma, CD40L) and platelet markers. Moreover, in human atheroma cultures, TLR7 activation selectively suppressed the production of key proatherogenic factors such as monocyte chemoattractant protein-1 and tumor necrosis factor without affecting IL-10.
Conclusions
These findings provide evidence for a beneficial role of TLR7 in atherosclerosis by constraining inflammatory macrophage activation and cytokine production. This challenges the prevailing concept that all TLRs are pathogenic and supports the exploitation of the TLR7 pathway for therapy.
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Affiliation(s)
- Maria Salagianni
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Ioanna E. Galani
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Anna M. Lundberg
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Constantinos H. Davos
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Aimilia Varela
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Ariana Gavriil
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Leo-Pekka Lyytikäinen
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Terho Lehtimäki
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Fragiska Sigala
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Lasse Folkersen
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Vassilis Gorgoulis
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Sébastien Lenglet
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Fabrizio Montecucco
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - François Mach
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Ulf Hedin
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Göran K. Hansson
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Claudia Monaco
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
| | - Evangelos Andreakos
- From the Center for Immunology and Transplantation (M.S., I.E.G., A.G., E.A.), Center for Clinical Research (C.H.D., A.V.), and Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece (V.G.); Center for Molecular Medicine, Department of Medicine at Karolinska University Hospital Solna, Karolinska Institutet, Stockholm, Sweden (A.M.L., L.F., U.H., G.K.H.); Department of Clinical Chemistry, Tampere University Hospital & University of Tampere Medical School,
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222
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Staphylococcus aureus, Toll-like receptors, superantigens, and their derivatives. J Mol Med (Berl) 2012; 90:1091-3. [DOI: 10.1007/s00109-012-0939-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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223
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Luo J, Obmolova G, Malia TJ, Wu SJ, Duffy KE, Marion JD, Bell JK, Ge P, Zhou ZH, Teplyakov A, Zhao Y, Lamb RJ, Jordan JL, San Mateo LR, Sweet RW, Gilliland GL. Lateral clustering of TLR3:dsRNA signaling units revealed by TLR3ecd:3Fabs quaternary structure. J Mol Biol 2012; 421:112-24. [PMID: 22579623 PMCID: PMC3920545 DOI: 10.1016/j.jmb.2012.05.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 04/27/2012] [Accepted: 05/03/2012] [Indexed: 12/19/2022]
Abstract
Toll-like receptor 3 (TLR3) recognizes dsRNA and initiates an innate immune response through the formation of a signaling unit (SU) composed of one double-stranded RNA (dsRNA) and two TLR3 molecules. We report the crystal structure of human TLR3 ectodomain (TLR3ecd) in a quaternary complex with three neutralizing Fab fragments. Fab15 binds an epitope that overlaps the C-terminal dsRNA binding site and, in biochemical assays, blocks the interaction of TLR3ecd with dsRNA, thus directly antagonizing TLR3 signaling through inhibition of SU formation. In contrast, Fab12 and Fab1068 bind TLR3ecd at sites distinct from the N- and C-terminal regions that interact with dsRNA and do not inhibit minimal SU formation with short dsRNA. Molecular modeling based on the co-structure rationalizes these observations by showing that both Fab12 and Fab1068 prevent lateral clustering of SUs along the length of the dsRNA ligand. This model is further supported by cell-based assay results using dsRNA ligands of lengths that support single and multiple SUs. Thus, their antagonism of TLR3 signaling indicates that lateral clustering of SUs is required for TLR3 signal transduction.
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Affiliation(s)
- Jinquan Luo
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Galina Obmolova
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Thomas J. Malia
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Sheng-Jiun Wu
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Karen E. Duffy
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - James D. Marion
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Jessica K. Bell
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Peng Ge
- Electron Imaging Center for Nanomachines (EICN), UCLA, Los Angeles, CA 90095, USA
| | - Z. Hong Zhou
- Electron Imaging Center for Nanomachines (EICN), UCLA, Los Angeles, CA 90095, USA
| | - Alexey Teplyakov
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Yonghong Zhao
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Roberta J. Lamb
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Jarrat L. Jordan
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Lani R. San Mateo
- Immunology Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Raymond W. Sweet
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
| | - Gary L. Gilliland
- Biologics Research, Janssen Research and Development, L.L.C., 145 King of Prussia Road, Radnor, PA 19087, USA
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224
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Laguna JC, Alegret M. Regulation of gene expression in atherosclerosis: insights from microarray studies in monocytes/macrophages. Pharmacogenomics 2012; 13:477-95. [PMID: 22380002 DOI: 10.2217/pgs.12.9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Atherosclerosis is a pathological phenomenon in which the walls of large arteries thicken and lose elasticity as a result of the growth of atheromatous lesions. It is a complex, multifactorial disease that involves several cell types and various pathobiological processes. Its genetic basis has not yet been deciphered, but it is related to complex multigene patterns influenced by environmental interactions. In this review, we focus specifically on the application of microarrays to atherosclerosis research using monocytes and monocyte-derived macrophages, as these are key cells in all phases of atherosclerosis, from the formation of foam cells to the destabilization and rupture of the atherosclerotic plaque. These studies have provided relevant information on genes involved in atherosclerosis development, contributing to our understanding of the molecular mechanisms that underlie this complex disease.
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Affiliation(s)
- Juan C Laguna
- Pharmacology Department, Faculty of Pharmacy & Institute of Biomedicine (IBUB), University of Barcelona, Spain
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225
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Fairweather D, Petri MA, Coronado MJ, Cooper LT. Autoimmune heart disease: role of sex hormones and autoantibodies in disease pathogenesis. Expert Rev Clin Immunol 2012; 8:269-84. [PMID: 22390491 DOI: 10.1586/eci.12.10] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cardiovascular disease (CVD) and autoimmune diseases (ADs) are the first and third highest causes of death in the USA, respectively. Men have an increased incidence of the majority of CVDs, including atherosclerosis, myocarditis, dilated cardiomyopathy and heart failure. By contrast, nearly 80% of all ADs occur in women. However, in one category of ADs, rheumatic diseases, CVD is the main cause of death. Factors that link rheumatic ADs to CVD are inflammation and the presence of autoantibodies. In this review we will examine recent findings regarding sex differences in the immunopathogenesis of CVD and ADs, explore possible reasons for the increased occurrence of CVD within rheumatic ADs and discuss whether autoantibodies, including rheumatoid factor, could be involved in disease pathogenesis.
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Affiliation(s)
- DeLisa Fairweather
- Johns Hopkins University Bloomberg School of Public Health, Department of Environmental Health Sciences, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
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226
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Curtiss LK, Black AS, Bonnet DJ, Tobias PS. Atherosclerosis induced by endogenous and exogenous toll-like receptor (TLR)1 or TLR6 agonists. J Lipid Res 2012; 53:2126-2132. [PMID: 22822027 DOI: 10.1194/jlr.m028431] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Atherosclerosis is a chronic inflammatory vascular disease. Toll-like receptors (TLRs) are major initiators of inflammation. TLR2 promotes atherosclerosis in LDL receptor (LDLr)-deficient mice fed a high-fat diet (HFD). TLR2 forms heterodimers with TLR1 or TLR6 to enable inflammatory responses in the presence of distinct ligands. Here we asked whether TLR1 and/or TLR6 are required. We studied atherosclerotic disease using either TLR1- or TLR6-deficient mice. Deficiency of TLR1 or TLR6 did not diminish HFD-driven disease. When HFD-fed LDLr-deficient mice were challenged with Pam3 or MALP2, specific exogenous ligands of TLR2/1 or TLR2/6, respectively, atherosclerotic lesions developed with remarkable intensity in the abdominal segment of the descending aorta. In contrast to atherosclerosis induced by the endogenous agonists, these lesions were diminished by deficiency of either TLR1 or TLR6. The endogenous ligand(s) that arise from consumption of a HFD and promote disease via TLR2 are unknown. Either TLR1 or TLR6 are redundant for this endogenous ligand detection, or they are both irrelevant to endogenous ligand detection. However, the exogenous ligands Pam3 and MALP2 promote severe abdominal atherosclerosis in the descending aorta that is dependent on TLR1 and TLR6, respectively.
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Affiliation(s)
- Linda K Curtiss
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA.
| | - Audrey S Black
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA
| | - David J Bonnet
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA
| | - Peter S Tobias
- Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA
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227
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Maitra U, Deng H, Glaros T, Baker B, Capelluto DG, Li Z, Li L. Molecular mechanisms responsible for the selective and low-grade induction of proinflammatory mediators in murine macrophages by lipopolysaccharide. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 189:1014-23. [PMID: 22706082 PMCID: PMC3392521 DOI: 10.4049/jimmunol.1200857] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Low-dose endotoxemia is prevalent in humans with adverse health conditions, and it correlates with the pathogenesis of chronic inflammatory diseases such as atherosclerosis, diabetes, and neurologic inflammation. However, the underlying molecular mechanisms are poorly understood. In this study, we demonstrate that subclinical low-dose LPS skews macrophages into a mild proinflammatory state, through cell surface TLR4, IL-1R-associated kinase-1, and the Toll-interacting protein. Unlike high-dose LPS, low-dose LPS does not induce robust activation of NF-κB, MAPKs, PI3K, or anti-inflammatory mediators. Instead, low-dose LPS induces activating transcription factor 2 through Toll-interacting protein-mediated generation of mitochondrial reactive oxygen species, allowing mild induction of proinflammatory mediators. Low-dose LPS also suppresses PI3K and related negative regulators of inflammatory genes. Our data reveal novel mechanisms responsible for skewed and persistent low-grade inflammation, a cardinal feature of chronic inflammatory diseases.
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Affiliation(s)
- Urmila Maitra
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0910
| | - Hui Deng
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0910
| | - Trevor Glaros
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0910
| | - Bianca Baker
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0910
| | | | - Zihai Li
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC29425
| | - Liwu Li
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061-0910
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228
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Feingold KR, Shigenaga JK, Kazemi MR, McDonald CM, Patzek SM, Cross AS, Moser A, Grunfeld C. Mechanisms of triglyceride accumulation in activated macrophages. J Leukoc Biol 2012; 92:829-39. [PMID: 22753953 DOI: 10.1189/jlb.1111537] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
LPS treatment of macrophages induces TG accumulation, which is accentuated by TG-rich lipoproteins or FFA. We defined pathways altered during macrophage activation that contribute to TG accumulation. Glucose uptake increased with activation, accompanied by increased GLUT1. Oxidation of glucose markedly decreased, whereas incorporation of glucose-derived carbon into FA and sterols increased. Macrophage activation also increased uptake of FFA, associated with an increase in CD36. Oxidation of FA was markedly reduced, whereas the incorporation of FA into TGs increased, associated with increased GPAT3 and DGAT2. Additionally, macrophage activation decreased TG lipolysis; however, expression of ATGL or HSL was not altered. Macrophage activation altered gene expression similarly when incubated with exogenous FA or AcLDL. Whereas activation with ligands of TLR2 (zymosan), TLR3 (poly I:C), or TLR4 (LPS) induced alterations in macrophage gene expression, leading to TG accumulation, treatment of macrophages with cytokines had minimal effects. Thus, activation of TLRs leads to accumulation of TG in macrophages by multiple pathways that may have beneficial effects in host defense but could contribute to the accelerated atherosclerosis in chronic infections and inflammatory diseases.
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Affiliation(s)
- Kenneth R Feingold
- Metabolism Section, Department of Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA.
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229
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Paul-Clark MJ, George PM, Gatheral T, Parzych K, Wright WR, Crawford D, Bailey LK, Reed DM, Mitchell JA. Pharmacology and therapeutic potential of pattern recognition receptors. Pharmacol Ther 2012; 135:200-15. [PMID: 22627269 DOI: 10.1016/j.pharmthera.2012.05.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 04/20/2012] [Indexed: 12/30/2022]
Abstract
Pharmacologists have used pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharide (LPS) for decades as a stimulus for studying mediators involved in inflammation and for the screening of anti-inflammatory compounds. However, in the view of immunologists, LPS was too non-specific for studying the mechanisms of immune signalling in infection and inflammation, as no receptors had been identified. This changed in the late 1990s with the discovery of the Toll-like receptors. These 'pattern recognition receptors' (PRRs) were able to recognise highly conserved sequences, the so called pathogen associated molecular patterns (PAMPs) present in or on pathogens. This specificity of particular PAMPs and their newly defined receptors provided a common ground between pharmacologists and immunologists for the study of inflammation. PRRs also recognise endogenous agonists, the so called danger-associated molecular patterns (DAMPs), which can result in sterile inflammation. The signalling pathways and ligands of many PRRs have now been characterised and there is no doubt that this rich vein of research will aid the discovery of new therapeutics for infectious conditions and chronic inflammatory disease.
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Affiliation(s)
- M J Paul-Clark
- Department of Cardiothoracic Pharmacology, Pharmacology and Toxicology, National Heart and Lung Institute, Imperial College London, Guy Scadding Building, Dovehouse Street, London SW3 6LY, United Kingdom.
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230
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Ding Y, Subramanian S, Montes VN, Goodspeed L, Wang S, Han C, Teresa AS, Kim J, O'Brien KD, Chait A. Toll-like receptor 4 deficiency decreases atherosclerosis but does not protect against inflammation in obese low-density lipoprotein receptor-deficient mice. Arterioscler Thromb Vasc Biol 2012; 32:1596-604. [PMID: 22580897 DOI: 10.1161/atvbaha.112.249847] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
OBJECTIVE Obesity is associated with insulin resistance, chronic low-grade inflammation, and atherosclerosis. Toll-like receptor 4 (TLR4) participates in the cross talk between inflammation and insulin resistance, being activated by both lipopolysaccharide and saturated fatty acids. The present study was undertaken to determine whether TLR4 deficiency has a protective role in inflammation, insulin resistance, and atherosclerosis induced by a diabetogenic diet. METHODS AND RESULTS TLR4 and low-density lipoprotein (LDL) receptor double knockout mice and LDL receptor-deficient mice were fed either a normal chow or a diabetogenic diet for 24 weeks. TLR4 and LDL receptor double knockout mice fed a diabetogenic diet showed improved plasma cholesterol and triglyceride levels but developed obesity, hyperinsulinemia, and glucose intolerance equivalent to obese LDL receptor-deficient mice. Adipocyte hypertrophy, macrophage accumulation, and local inflammation were not attenuated in intraabdominal adipose tissue in TLR4 and LDL receptor double knockout mice. However, TLR4 deficiency led to markedly decreased atherosclerosis in obese TLR4 and LDL receptor double knockout mice. Compensatory upregulation of TLR2 expression was observed both in obese TLR4-deficient mice and in palmitate-treated TLR4-silenced 3T3-L1 adipocytes. CONCLUSIONS TLR4 deficiency decreases atherosclerosis without affecting obesity-induced inflammation and insulin resistance in LDL receptor-deficient mice. Alternative pathways may be responsible for adipose tissue macrophage infiltration and insulin resistance that occurs in obesity.
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Affiliation(s)
- Yilei Ding
- Division of Metabolism, Endocrinology and Nutrition and Diabetes and Obesity Center of Excellence, Department of Medicine, University of Washington, Seattle, 98109, USA
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231
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Kim SY, Jeong E, Joung SM, Lee JY. PI3K/Akt contributes to increased expression of Toll-like receptor 4 in macrophages exposed to hypoxic stress. Biochem Biophys Res Commun 2012; 419:466-71. [PMID: 22424098 DOI: 10.1016/j.bbrc.2012.02.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 02/03/2012] [Indexed: 01/26/2023]
Abstract
Toll-like receptors (TLRs) play critical roles in triggering immune and inflammatory responses by detecting invading microbial pathogens and endogenous danger signals. Increased expression of TLR4 is implicated in aggravated inflammatory symptoms in ischemic tissue injury and chronic diseases. Results from our previous study showed that TLR4 expression was upregulated by hypoxic stress mediated by hypoxia-inducible factor-1 (HIF-1) at a transcriptional level in macrophages. In this study, we further investigated the upstream signaling pathway that contributed to the increase of TLR4 expression by hypoxic stress. Either treatment with pharmacological inhibitors of PI3K and Akt or knockdown of Akt expression by siRNA blocked the increase of TLR4 mRNA and protein levels in macrophages exposed to hypoxia and CoCl(2). Phosphorylation of Akt by hypoxic stress preceded nuclear accumulation of HIF-1α. A PI3K inhibitor (LY294002) attenuated CoCl(2)-induced nuclear accumulation and transcriptional activation of HIF-1α. In addition, HIF-1α-mediated upregulation of TLR4 expression was blocked by LY294002. Furthermore, sulforaphane suppressed hypoxia- and CoCl(2)-induced upregulation of TLR4 mRNA and protein by inhibiting PI3K/Akt activation and the subsequent nuclear accumulation and transcriptional activation of HIF-1α. However, p38 was not involved in HIF-1α activation and TLR4 expression induced by hypoxic stress in macrophages. Collectively, our results demonstrate that PI3K/Akt contributes to hypoxic stress-induced TLR4 expression at least partly through the regulation of HIF-1 activation. These reveal a novel mechanism for regulation of TLR4 expression upon hypoxic stress and provide a therapeutic target for chronic diseases related to hypoxic stress.
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Affiliation(s)
- So Young Kim
- School of Life Sciences, Gwangju Institute of Science and Technology, Republic of Korea
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232
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Diverse roles of macrophages in atherosclerosis: from inflammatory biology to biomarker discovery. Mediators Inflamm 2012; 2012:693083. [PMID: 22577254 PMCID: PMC3337637 DOI: 10.1155/2012/693083] [Citation(s) in RCA: 129] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 01/11/2012] [Indexed: 02/07/2023] Open
Abstract
Cardiovascular disease, a leading cause of mortality in developed countries, is mainly caused by atherosclerosis, a chronic inflammatory disease. Macrophages, which differentiate from monocytes that are recruited from the blood, account for the majority of leukocytes in atherosclerotic plaques. Apoptosis and the suppressed clearance of apoptotic macrophages (efferocytosis) are associated with vulnerable plaques that are prone to rupture, leading to thrombosis. Based on the central functions of macrophages in atherogenesis, cytokines, chemokines, enzymes, or microRNAs related to or produced by macrophages have become important clinical prognostic or diagnostic biomarkers. This paper discusses the impact of monocyte-derived macrophages in early atherogenesis and advanced disease. The role and possible future development of macrophage inflammatory biomarkers are also described.
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233
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Paolillo R, Iovene M, Carratelli CR, Rizzo A. Induction of VEGF and MMP-9 Expression by Toll-like Receptor 2/4 in Human Endothelial Cells Infected withChlamydia Pneumoniae. Int J Immunopathol Pharmacol 2012; 25:377-86. [DOI: 10.1177/039463201202500207] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- R. Paolillo
- Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Faculty of Medicine and Surgery, Second University of Naples, Naples, Italy
| | - M.R. Iovene
- Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Faculty of Medicine and Surgery, Second University of Naples, Naples, Italy
| | - C. Romano Carratelli
- Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Faculty of Medicine and Surgery, Second University of Naples, Naples, Italy
| | - A. Rizzo
- Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Faculty of Medicine and Surgery, Second University of Naples, Naples, Italy
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234
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Davanian H, Båge T, Lindberg J, Lundeberg J, Q. Concha H, Sällberg Chen M, Yucel-Lindberg T. Signaling pathways involved in the regulation of TNFα-induced toll-like receptor 2 expression in human gingival fibroblasts. Cytokine 2012; 57:406-16. [DOI: 10.1016/j.cyto.2011.12.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 11/16/2011] [Accepted: 12/12/2011] [Indexed: 11/25/2022]
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235
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Major AS, Harrison DG. What fans the fire: insights into mechanisms of inflammation in atherosclerosis and diabetes mellitus. Circulation 2012; 124:2809-11. [PMID: 22184043 DOI: 10.1161/circulationaha.111.070565] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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236
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Abstract
Macrophages are key innate immune effector cells best known for their role as professional phagocytes, which also include neutrophils and dendritic cells. Recent evidence indicates that macrophages are also key players in metabolic homoeostasis. Macrophages can be found in many tissues, where they respond to metabolic cues and produce pro- and/or anti-inflammatory mediators to modulate metabolite programmes. Certain metabolites, such as fatty acids, ceramides and cholesterol crystals, elicit inflammatory responses through pathogen-sensing signalling pathways, implicating a maladaptation of macrophages and the innate immune system to elevated metabolic stress associated with overnutrition in modern societies. The outcome of this maladaptation is a feedforward inflammatory response leading to a state of unresolved inflammation and a collection of metabolic pathologies, including insulin resistance, fatty liver, atherosclerosis and dyslipidaemia. The present review summarizes what is known about the contributions of macrophages to metabolic diseases and the signalling pathways that are involved in metabolic stress-induced macrophage activation. Understanding the role of macrophages in these processes will help us to develop therapies against detrimental effects of the metabolic syndrome.
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237
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Jialal I, Kaur H. The Role of Toll-Like Receptors in Diabetes-Induced Inflammation: Implications for Vascular Complications. Curr Diab Rep 2012; 12:172-179. [PMID: 22314791 DOI: 10.1007/s11892-012-0258-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Diabetes confers an increased risk for both microvascular and macrovascular complications. Numerous studies have reported increased levels of biomarkers of inflammation that could predispose to vascular complications. The pattern recognition receptors of the innate immune response, such as Toll-like receptors (TLRs), especially TLR2 and TLR4, have been incriminated in both atherosclerosis and insulin resistance. Studies have reported increased expression and activity of these receptors in both type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus. Most recently, knockout of TLR2 has been shown to attenuate the proinflammatory state of T1DM and the progression of diabetic nephropathy. The increased activity of TLRs in diabetes could be the result of a conspiracy of both endogenous and exogenous ligands. Biomediators of increased TLR2 and TLR4 activity include tumor necrosis factor-α, interleukin (IL)-1β, IL-6, monocyte chemoattractant protein-1, and type 1 interferons. Modulating these TLRs could be beneficial in forestalling diabetic complications given the pivotal role of inflammation in both microvascular and macrovascular complications.
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Affiliation(s)
- Ishwarlal Jialal
- Laboratory of Atherosclerosis and Metabolic Research, UC Davis Medical Center, Sacramento, CA, 95817, USA,
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238
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Tedgui A, Owens AP, Mackman N. 2011 Nobel Prize in Physiology or Medicine: Toll-like receptors, dendritic cells, and their roles in atherosclerosis. Arterioscler Thromb Vasc Biol 2012; 31:2767-8. [PMID: 22096091 DOI: 10.1161/atvbaha.111.240432] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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239
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Kwon MY, Liu X, Lee SJ, Kang YH, Choi AMK, Lee KU, Perrella MA, Chung SW. Nucleotide-binding oligomerization domain protein 2 deficiency enhances neointimal formation in response to vascular injury. Arterioscler Thromb Vasc Biol 2012; 31:2441-7. [PMID: 21903945 DOI: 10.1161/atvbaha.111.235135] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Nucleotide-binding oligomerization domain protein 2 (NOD2) stimulates diverse inflammatory responses resulting in differential cellular phenotypes. To identify the role of NOD2 in vascular arterial obstructive diseases, we investigated the expression and pathophysiological role of NOD2 in a vascular injury model of neointimal hyperplasia. METHODS AND RESULTS We first analyzed for neointimal hyperplasia following femoral artery injury in NOD2(+/+) and NOD2(-/-) mice. NOD2(-/-) mice showed a 2.86-fold increase in neointimal formation that was mainly composed of smooth muscle (SM) α-actin positive cells. NOD2 was expressed in vascular smooth muscle cells (VSMCs) and NOD2(-/-) VSMCs showed increased cell proliferation in response to mitogenic stimuli, platelet-derived growth factor-BB (PDGF-BB), or fetal bovine serum, compared with NOD2(+/+) VSMCs. Furthermore, NOD2 deficiency markedly promoted VSMCs migration in response to PDGF-BB, and this increased cell migration was attenuated by a phosphatidylinositol 3-kinase inhibitor. However, protein kinase C and c-Jun N-terminal kinase inhibitors exerted negligible effects. Moreover, muramyl dipeptide-stimulated NOD2 prevented PDGF-BB-induced VSMCs migration. CONCLUSION Functional NOD2 was found to be expressed in VSMCs, and NOD2 deficiency promoted VSMCs proliferation, migration, and neointimal formation after vascular injury. These results provide evidence for the involvement of NOD2 in vascular homeostasis and tissue injury, serving as a potential molecular target in the modulation of arteriosclerotic vascular disease.
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Affiliation(s)
- Min-Young Kwon
- School of Biological Sciences, University of Ulsan, Ulsan, South Korea
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240
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Park DW, Lee HK, Jeong TW, Kim JS, Bae YS, Chin BR, Baek SH. The JAK2-Akt-glycogen synthase kinase-3β signaling pathway is involved in toll-like receptor 2-induced monocyte chemoattractant protein-1 regulation. Mol Med Rep 2012; 5:1063-7. [PMID: 22218715 PMCID: PMC3493083 DOI: 10.3892/mmr.2012.741] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 12/21/2011] [Indexed: 12/27/2022] Open
Abstract
Monocyte chemoattractant protein-1 (MCP-1) is an essential cytokine for the migration of monocytes into vessels, and is also involved in the pathogenesis of atherosclerosis. In this study, we investigated the importance of janus kinase 2 (JAK2) and the function of the Akt and glycogen synthase kinase-3β (GSK3β) pathway in toll-like receptor (TLR2)-mediated MCP-1 expression. The TLR2 agonist, Pam3CSK4, induced MCP-1 expression in the Raw264.7 cell line. The induction of MCP-1 was seen in the bone marrow-derived macrophages of wild-type mice but not in TLR2 knockout mice. The TLR2-mediated MCP-1 induction was myeloid differentiation primary response gene 88 (MyD88)-independent. By contrast, the inactivation of JAK2 attenuated TLR2-mediated MCP-1 expression. The JAK inhibitor suppressed the phosphorylation of GSK3β as well as Akt by Pam3CSK4 stimulation. While the inactivation of Akt by LY294002 suppressed TLR2-mediated MCP-1 induction, the inactivation of GSK3β by LiCl potentiated TLR2-mediated MCP-1 induction. Furthermore, Akt inhibitor suppressed TLR2-mediated phosphorylation of GSK3β. Taken together, these results suggest that a MyD88-independent pathway exists in TLR2 signaling; the JAK2-Akt-GSK3β pathway is a novel MyD88-independent pathway for MCP-1 induction.
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Affiliation(s)
- Dae-Weon Park
- Department of Biochemistry and Molecular Biology, Aging-associated Vascular Disease Research Center, 210 Main Building, College of Medicine, Yeungnam University, Daegu 705-802, Republic of Korea
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Herrera JL, Gonzalez-Rey E, Fernandez-Montesinos R, Quintana FJ, Najmanovich R, Pozo D. Toll-like receptor stimulation differentially regulates vasoactive intestinal peptide type 2 receptor in macrophages. J Cell Mol Med 2011; 13:3209-17. [PMID: 20196778 PMCID: PMC4516478 DOI: 10.1111/j.1582-4934.2009.00662.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Vasoactive intestinal peptide (VIP) was originally isolated as a vasodilator intestinal peptide, then as a neuropeptide. In the immune system, VIP is described as an endogenous macrophage-deactivating factor. VIP exerts its immunological actions in a paracrine and/or autocrine manner, through specific receptors. However, very little is known about the molecular regulation of VIP type 2 receptor (VPAC(2)) in the immune system. We now report that different toll-like receptor (TLR) ligands selectively regulate the VPAC(2) receptor gene and show a gene repression system controlled by key protein kinase signalling cascades in macrophages. VPAC(2) gene expression is regulated by gram-positive (TLR2 ligands) and gram-negative bacteria wall constituents (TLR4 ligands). Moreover, VPAC(2) is tightly regulated: TLR2- or TLR2/6- but not TLR2/1-mediated mechanisms are responsible for the induction of VPAC(2). TLR stimulation by viral or bacterial nucleic acids did not modify the VPAC(2) mRNA levels. Remarkably, imiquimod--a synthetic TLR7 ligand--led to a potent up-regulation of VPAC(2) gene expression. TLR5 stimulation by flagellin present in gram-positive and gram-negative bacteria did not affect VPAC(2) mRNA. The p38 mitogen-activated protein kinase (MAPK) activity accounted for the TLR4-mediated induction of VPAC(2) gene expression. Surprisingly, our data strongly suggest for the first time a tightly repressed control of VPAC(2) mRNA induction by elements downstream of MAPK kinase 1/2, PI3K/Akt, and particularly Jun-NH(2)-terminal kinase signalling pathways.
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Affiliation(s)
- Juan Luis Herrera
- CABIMER-Andalusian Center for Molecular Biology and Regenerative Medicine, CSIC-University of Seville-UPO-Junta de Andalucia, Seville, Spain
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242
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Bertocchi C, Traunwieser M, Dörler J, Hasslacher J, Joannidis M, Dunzendorfer S. Atorvastatin inhibits functional expression of proatherogenic TLR2 in arterial endothelial cells. Cell Physiol Biochem 2011; 28:625-30. [PMID: 22178874 DOI: 10.1159/000335758] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2011] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND There is growing evidence that TLR2 plays a role in the pathogenesis of atherosclerosis. It is highly expressed in endothelial cells in areas of disturbed blood flow, like plaques or vessel bifurcations, but laminar blood flow suppresses endothelial TLR2 expression and is therefore thought to be atheroprotective. We sought for means to also protect lesion prone sites from TLR2 over-expression and subsequent endothelial activation. METHODS Human coronary artery endothelial cells (HCAEC) were treated with atorvastatin (ATV) and TLR2 surface expression was determined by FACS analyses. Western blot analyses were used to explore the phosphorylation status of SP1. RESULTS ATV profoundly inhibited basal and stimulated endothelial TLR2 expression in a time- and dose-dependent manner. It also inhibited HCAEC activation by MALP-2. TLR2 surface expression was inversely correlated to SP1 serine phosphorylation and was casein kinase 2 dependent. CONCLUSION We demonstrate that ATV can control over-expression of proinflammatory endothelial TLR2 protein and TLR2-mediated endothelial activation. The mechanism involves casein kinase 2 and SP1 phosphorylation. ATV effects on endothelial cell TLR2 are comparable to those of laminar blood flow and might therefore also be atheroprotective.
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Affiliation(s)
- Cristina Bertocchi
- Department of Internal Medicine, Medical University of Innsbruck, Anichstrasse 35, Innsbruck, Austria
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243
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Nicolaou G, Goodall AH, Erridge C. Diverse bacteria promote macrophage foam cell formation via Toll-like receptor-dependent lipid body biosynthesis. J Atheroscler Thromb 2011; 19:137-48. [PMID: 22123216 DOI: 10.5551/jat.10249] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM Atherosclerotic lesions contain DNA signatures from a wide variety of bacteria, although little is known of how exposure to these organisms may modulate the accumulation of lipids in macrophages. METHODS To address this, a panel of nine bacteria representing those most frequently reported to be present in human atheroma were examined for their potential to promote lipid accumulation in human primary monocytes and murine J774 macrophages. RESULTS All bacteria examined, and defined stimulants of Toll-like receptors (TLRs) 2, 3, 4, 5 and 9, induced lipid body formation and cholesterol ester accumulation in a dose-dependent manner. The mechanisms of bacteria-mediated foam cell formation were found to be dependent on TLR2 and/or TLR4 signalling, but independent of lipoprotein oxidation pathways, since lipid accumulation was significantly inhibited by the TLR4 inhibitors polymyxin-B and TAK-242, or the TLR2 and TLR4 inhibitor oxidised palmitoyl-arachidonyl-phosphatidyl-choline, but not by the scavenger receptor blocker polyinosinic acid or the antioxidant butylated hydroxytoluene. A number of genes involved in lipid body biosynthesis, including perilipin-A, stearoyl-coenzyme-A desaturase 1, fatty acid synthase and HMG-CoA reductase were upregulated in response to TLR4 stimulation. CONCLUSIONS The bacterial debris observed in human atheroma, which is currently considered to be harmless, may have potential to contribute to disease progression via TLR-dependent lipid body formation in macrophages.
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Affiliation(s)
- Giovanna Nicolaou
- Department of Cardiovascular Sciences, Glenfield Hospital, Leicester, UK
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244
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Xia M, Guerra N, Sukhova GK, Yang K, Miller CK, Shi GP, Raulet DH, Xiong N. Immune activation resulting from NKG2D/ligand interaction promotes atherosclerosis. Circulation 2011; 124:2933-43. [PMID: 22104546 DOI: 10.1161/circulationaha.111.034850] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The interplay between the immune system and abnormal metabolic conditions sustains and propagates a vicious feedback cycle of chronic inflammation and metabolic dysfunction that is critical for atherosclerotic progression. It is well established that abnormal metabolic conditions, such as dyslipidemia and hyperglycemia, cause various cellular stress responses that induce tissue inflammation and immune cell activation, which in turn exacerbate the metabolic dysfunction. However, molecular events linking these processes are not well understood. METHODS AND RESULTS Tissues and organs of humans and mice with hyperglycemia and hyperlipidemia were examined for expression of ligands for NKG2D, a potent immune-activating receptor expressed by several types of immune cells, and the role of NKG2D in atherosclerosis and metabolic diseases was probed with the use of mice lacking NKG2D or by blocking NKG2D with monoclonal antibodies. NKG2D ligands were upregulated in multiple organs, particularly atherosclerotic aortas and inflamed livers. Ligand upregulation was induced in vitro by abnormal metabolites associated with metabolic dysfunctions. Using apolipoprotein E-deficient mouse models, we demonstrated that preventing NKG2D functions resulted in a dramatic reduction in plaque formation, suppressed systemic and organ inflammation mediated by multiple immune cell types, and alleviated abnormal metabolic conditions. CONCLUSIONS The NKG2D/ligand interaction is a critical molecular link in the vicious cycle of chronic inflammation and metabolic dysfunction that promotes atherosclerosis and might be a useful target for therapeutic intervention in the disease.
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Affiliation(s)
- Mingcan Xia
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, 115 Henning Bldg, University Park, PA 16802, USA
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Kadl A, Sharma PR, Chen W, Agrawal R, Meher AK, Rudraiah S, Grubbs N, Sharma R, Leitinger N. Oxidized phospholipid-induced inflammation is mediated by Toll-like receptor 2. Free Radic Biol Med 2011; 51:1903-9. [PMID: 21925592 PMCID: PMC3197756 DOI: 10.1016/j.freeradbiomed.2011.08.026] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 08/22/2011] [Accepted: 08/23/2011] [Indexed: 12/18/2022]
Abstract
Oxidative tissue damage is a hallmark of many chronic inflammatory diseases. However, the precise mechanisms linking oxidative changes to inflammatory reactions remain unclear. Herein we show that Toll-like receptor 2 (TLR2) translates oxidative tissue damage into inflammatory responses by mediating the effects of oxidized phospholipids. Intraperitoneal injection of oxidized 1-palmitoyl-2-arachidonyl-sn-3-glycerophosphorylcholine (OxPAPC) resulted in upregulation of inflammatory genes in wild-type, but not in TLR2(-/-) mice. In vitro, OxPAPC induced TLR2 (but not TLR4)-dependent inflammatory gene expression and JNK and p38 signaling in macrophages. Induction of TLR2-dependent gene expression required reducible functional groups on sn-2 acyl chains of oxidized phospholipids, as well as serum cofactors. Finally, TLR2(-/-) mice were protected against carbon tetrachloride-induced oxidative tissue damage and inflammation, which was accompanied by accumulation of oxidized phospholipids in livers. Together, our findings demonstrate that TLR2 mediates cellular responses to oxidative tissue damage and they provide new insights into how oxidative stress is linked to acute and chronic inflammation.
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Affiliation(s)
- Alexandra Kadl
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Poonam R. Sharma
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Wenshu Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Rachana Agrawal
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Akshaya K. Meher
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Swetha Rudraiah
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Nathaniel Grubbs
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
| | - Rahul Sharma
- Department of Medicine, Center for Immunity, Inflammation and Regenerative Medicine, University of Virginia, Charlottesville, VA 22908, USA
| | - Norbert Leitinger
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA
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246
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Song Y, Shen H, Schenten D, Shan P, Lee PJ, Goldstein DR. Aging enhances the basal production of IL-6 and CCL2 in vascular smooth muscle cells. Arterioscler Thromb Vasc Biol 2011; 32:103-9. [PMID: 22034510 DOI: 10.1161/atvbaha.111.236349] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Increased circulating cytokine levels are a prominent feature of aging that may contribute to atherosclerosis. However, the role vascular cells play in chronic inflammation induced by aging is not clear. Here, we examined the role of aging on inflammatory responses of vascular cells. METHODS AND RESULTS In an ex vivo culture system, we examined the inflammatory response of aortas from young (2-4 months) and aged (16-18 months) mice under nonstimulatory conditions. We found that basal levels of interleukin-6 were increased in aged aortas. Aged aortic vascular smooth muscle cells (VSMC) exhibited a higher basal secretion of interleukin-6 than young VSMC. Gene and protein expression analysis revealed that aged VSMC exhibited upregulation of chemokines (eg, CCL2), adhesion molecules (eg, intracellular adhesion molecule 1), and innate immune receptors (eg, Toll-like receptor [TLR] 4), which all contribute to atherosclerosis. Using VSMC from aged TL4(-/-) and Myd88(-/-) mice, we demonstrate that signaling via TLR4 and its signal adaptor, MyD88, are in part responsible for the age-elevated basal interleukin-6 response. CONCLUSIONS Aging induces a proinflammatory phenotype in VSMC due in part to increased signaling of TLR4 and MyD88. Our results provide a potential explanation as to why aging leads to chronic inflammation and enhanced atherosclerosis.
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Affiliation(s)
- Yang Song
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale University School of Medicine, New Haven, CT, USA
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Jin J, Samuvel DJ, Zhang X, Li Y, Lu Z, Lopes-Virella MF, Huang Y. Coactivation of TLR4 and TLR2/6 coordinates an additive augmentation on IL-6 gene transcription via p38MAPK pathway in U937 mononuclear cells. Mol Immunol 2011; 49:423-32. [PMID: 22030478 DOI: 10.1016/j.molimm.2011.08.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Revised: 08/05/2011] [Accepted: 08/17/2011] [Indexed: 11/17/2022]
Abstract
Studies have demonstrated that TLR4 and TLR2 expression by monocytes and the blood levels of TLR4 and TLR2 ligand in diabetic patients are significantly incased compared to nondiabetic patients, indicating that more monocytes in diabetic patients may have coactivation of TLR4 and TLR2. Although it has been shown that either TLR4 or TLR2 activation leads to increased expression of proinflammatory cytokines, the effect of coactivation of TLR2 and TLR4 in mononuclear cells on proinflammatory cytokine expression and the underlying molecular mechanisms remain largely unknown. In this study, we found that while TLR1, TLR2, TLR4 and TLR6 were expressed by U937 mononuclear cells, TLR4 was expressed at the highest level. Interestingly, results showed that while activation of either TLR4 or TLR2/6 (TLR2dimerized with TLR6), but not TLR2/1 (TLR2dimerized with TLR1), significantly increased IL-6 expression by U937 mononuclear cells, coactivation of TLR4 and TLR2/6, but not TLR4 and TLR2/1, led to a further augmentation on IL-6 expression by increasing IL-6 transcriptional activity, but not mRNA stability. To explore the signaling mechanisms involved in the augmentation, we found that p38MAPK and NFκB pathways, but not ERK and JNK pathways, were required for the augmentation of IL-6 expression by coactivation of TLR4 and TLR2/6. Furthermore, we found that coactivation of TLR4 and TLR2/6 increased p38 phosphorylation, but not NFkB activity, as compared to activation of TLR4or TLR2/6 alone. Taken together, this study showed that coactivation of TLR4 and TLR2/6 coordinates an additive augmentation of IL-6 gene transcription via p38MAPK pathway in U937 mononuclear cells.
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Affiliation(s)
- Junfei Jin
- Division of Endocrinology, Diabetes and Medical Genetics, Department of Medicine, Medical University of South Carolina, Charleston, SC 29425, United States
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248
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Lievens D, von Hundelshausen P. Platelets in atherosclerosis. Thromb Haemost 2011; 106:827-38. [PMID: 22012554 DOI: 10.1160/th11-08-0592] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2011] [Accepted: 10/03/2011] [Indexed: 01/04/2023]
Abstract
Beyond obvious functions in haemostasis and thrombosis, platelets are considered to be essential in proinflammatory surroundings such as atherosclerosis, allergy, rheumatoid arthritis and even cancer. In atherosclerosis, platelets facilitate the recruitment of inflammatory cells towards the lesion sites and release a plethora of inflammatory mediators, thereby enriching and boosting the inflammatory milieu. Platelets do so by interacting with endothelial cells, circulating leukocytes (monocytes, neutrophils, dendritic cells, T-cells) and progenitor cells. This cross-talk enforces leukocyte activation, adhesion and transmigration. Furthermore, platelets are known to function in innate host defense through the release of antimicrobial peptides and the expression of pattern recognition receptors. In severe sepsis, platelets are able to trigger the formation of neutrophil extracellular traps (NETs), which bind and clear pathogens. The present antiplatelet therapies that target key pathways of platelet activation and aggregation therefore hold the potential to modulate platelet-derived immune functions by reducing cellular interactions of platelets with other immune components and by reducing the secretion of inflammatory proteins into the milieu. The objective of this review is to update and discuss the current perceptions of the platelet immune constituents and their prospect as therapeutic targets in an atherosclerotic setting.
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Affiliation(s)
- D Lievens
- Institute for Cardiovascular Prevention, Ludwig-Maximilians University Munich, Munich, Germany.
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Salomon RG, Hong L, Hollyfield JG. Discovery of carboxyethylpyrroles (CEPs): critical insights into AMD, autism, cancer, and wound healing from basic research on the chemistry of oxidized phospholipids. Chem Res Toxicol 2011; 24:1803-16. [PMID: 21875030 DOI: 10.1021/tx200206v] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Basic research, exploring the hypothesis that 2-(ω-carboxyethyl)pyrrole (CEP) modifications of proteins are generated nonenzymatically in vivo is delivering a bonanza of molecular mechanistic insights into age-related macular degeneration, autism, cancer, and wound healing. CEPs are produced through covalent modification of protein lysyl ε-amino groups by γ-hydroxyalkenal phospholipids that are formed by oxidative cleavage of docosahexaenate-containing phospholipids. Chemical synthesis of CEP-modified proteins and the production of highly specific antibodies that recognize them preceded and facilitated their detection in vivo and enabled exploration of their biological occurrence and activities. This investigational approach, from the chemistry of biomolecules to disease phenotype, is proving to be remarkably productive.
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Affiliation(s)
- Robert G Salomon
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106-7078, USA.
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250
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Lundberg AM, Yan ZQ. Innate immune recognition receptors and damage-associated molecular patterns in plaque inflammation. Curr Opin Lipidol 2011; 22:343-9. [PMID: 21881501 DOI: 10.1097/mol.0b013e32834ada80] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW To highlight critical advances achieved over the last year in the study of endogenous proatherogenic danger signals and corresponding molecular mechanism of innate immune signalling in atherosclerosis. RECENT FINDINGS The identity and signalling mechanisms of LDL-derived inflammatory components are central in understanding the pathogenic role of modified LDL in the development of atherosclerosis. Studies in the preceding years have revealed LDL-derived phospholipids and cholesterol crystals as endogenous danger signals. These danger signals trigger Toll-like receptors and nucleotide-binding oligomerization domain-like receptors inflammasome respectively, thereby instigating inflammatory responses and promoting disease progression. SUMMARY Recent understandings of the causal role of LDL in atherosclerosis provide a new perspective on modified LDL-derived danger signals. These insights suggest dysregulated Toll-like receptor and nucleotide-binding oligomerization domain inflammasome signalling as an important mechanism underlying atherogenesis.
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Affiliation(s)
- Anna M Lundberg
- Karolinska Institute, Center for Molecular Medicine, L8:03, Karolinska University Hospital, SE-17176 Stockholm, Sweden
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