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Kakalij RM, Dsouza DL, Ha L, Boesen EI. TLR7 activation by imiquimod worsens glycemic control in female FVB/N mice consuming a high-fat diet. Physiol Rep 2024; 12:e15949. [PMID: 38346802 PMCID: PMC10861349 DOI: 10.14814/phy2.15949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 01/30/2024] [Accepted: 01/30/2024] [Indexed: 02/15/2024] Open
Abstract
Toll-like receptor-7 (TLR7) activation promotes autoimmunity, and metabolic syndrome (MetS) is a common comorbidity in patients with autoimmune disease. We previously demonstrated hyperinsulinemia in TLR7 agonist imiquimod (IMQ)-treated, high-fat diet (HFD)-fed female C57BL/6 mice. Since mouse strains differ in susceptibility to MetS and target organ damage, this study investigated whether 12 weeks of exposure to HFD and IMQ promoted MetS, autoimmunity, and target organ damage in female FVB/N mice. Supporting early-stage autoimmunity, spleen-to-tibia ratio, and anti-nuclear antibodies (ANA) were significantly increased by IMQ. No significant effect of IMQ on urinary albumin excretion or left ventricular hypertrophy was observed. HFD increased liver-to-tibia ratio, which was further exacerbated by IMQ. HFD increased fasting blood glucose levels at the end of 12 weeks, but there was no significant effect of IMQ treatment on fasting blood glucose levels at 6 or 12 weeks of treatment. However, oral glucose tolerance testing at 12 weeks revealed impaired glucose tolerance in HFD-fed mice compared to control diet mice together with IMQ treatment exacerbating the impairment. Accordingly, these data suggest TLR7 activation also exacerbates HFD-induced dysregulation of glucose handling FVB/N mice, supporting the possibility that endogenous TLR7 activation may contribute to dysglycemia in patients with autoimmune disease.
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Affiliation(s)
- Rahul M. Kakalij
- Department of Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - Del L. Dsouza
- Department of Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - LiGyeom Ha
- Department of Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
| | - Erika I. Boesen
- Department of Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNebraskaUSA
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Kakalij RM, Dsouza DL, Boesen EI. Development of High Fat Diet-Induced Hyperinsulinemia in Mice Is Enhanced by Co-treatment With a TLR7 Agonist. Front Physiol 2022; 13:930353. [PMID: 35874527 PMCID: PMC9298857 DOI: 10.3389/fphys.2022.930353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/17/2022] [Indexed: 12/20/2022] Open
Abstract
Metabolic syndrome (MetS) is common in Systemic Lupus Erythematosus (SLE) patients and is associated with increased cardio-renal risk. Toll-like receptor 7 (TLR7) stimulation promotes the development of SLE through mechanisms including activating type I Interferon (IFN) and autoreactive B cells. The current study tested whether combined TLR7 agonist treatment and exposure to a high fat, high sucrose “Western diet” intervention affects the early-stage development of SLE or MetS features. Female C57BL/6 mice were untreated or treated with the TLR7 agonist imiquimod (IMQ) and fed a high-fat diet (HFD; fat 42% kcal, sucrose 34% kcal) or control diet (fat 12.6% kcal, sucrose 34% kcal) for 6 weeks. Supporting early-stage induction of autoimmunity, spleen weights were significantly increased and anti-nuclear antibody (ANA) positivity was detected in IMQ-treated mice. Increased body weight, gonadal fat pad mass, and plasma leptin levels were observed between HFD and control animals for both IMQ and untreated mice. However, the increase in these parameters with HFD was slightly but significantly diminished in IMQ-treated mice. Both the HFD and IMQ treatments significantly increased fasting blood glucose levels. Notably, IMQ treatment affected fasting insulin concentrations in a diet-dependent manner, with hyperinsulinemia observed in IMQ-HFD treated mice. Together, this indicates that the IMQ model of SLE is associated with metabolic alterations, impaired glycemic control, and hyperinsulinemia under HFD conditions. This model may be helpful in further investigating the relationship between MetS and SLE, and supports a role of TLR7 signaling in promoting or accelerating the development of dysglycemia and hyperinsulinemia.
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Affiliation(s)
- Rahul M Kakalij
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Del L Dsouza
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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3
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Xia Z, Vellichirammal NN, Han L, Gao L, Boesen EI, Schiller AM, Pellegrino PR, Lisco SJ, Guda C, Zucker IH, Wang HJ. Cardiac Spinal Afferent Denervation Attenuates Renal Dysfunction in Rats With Cardiorenal Syndrome Type 2. JACC Basic Transl Sci 2022; 7:582-596. [PMID: 35818505 PMCID: PMC9270585 DOI: 10.1016/j.jacbts.2022.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/27/2022]
Abstract
Epicardial application of RTX at the time of MI largely prevented renal dysfunction, attenuated renal congestion, and partially restored renal blood flow in rats with CHF. RNA sequencing analysis showed that renal injury, inflammation, hypoxia, and apoptosis genes were significantly up-regulated in the renal tissue of CHF rats, which was largely prevented by epicardial RTX at the time of MI. Cardiac afferent ablation by intra–stellate ganglia injection of RTX or unilateral renal denervation 4 weeks after MI had similar renal protective effects on renal tubular damage in CHF rats. These data provide evidence for cardiac spinal afferent modulation of renal function and a potential targeted therapy.
Cardiorenal syndrome type 2 (CRS2) is defined as a chronic cardiovascular disease, usually chronic heart failure (CHF), resulting in chronic kidney disease. We hypothesized that the cardiac spinal afferent reflex (CSAR) plays a critical role in the development of CRS2. Our data suggest that cardiac afferent ablation by resiniferatoxin not only improves cardiac function but also benefits the kidneys and increases long-term survival in the myocardial infarction model of CHF. We also found that renal denervation has a similar reno-protective effect in CHF rats. We believe this novel work contributes to the development of a unique neuromodulation therapy to treat CHF patients.
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Affiliation(s)
- Zhiqiu Xia
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | | | - Li Han
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Lie Gao
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Erika I. Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Alicia M. Schiller
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Peter R. Pellegrino
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Steven J. Lisco
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Chittibabu Guda
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Bioinformatics and Systems Biology Core, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Irving H. Zucker
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Han-Jun Wang
- Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
- Address for correspondence: Dr Han-Jun Wang, Department of Anesthesiology, University of Nebraska Medical Center, 985850, 42nd and Emile Streets, Omaha, Nebraska 68198, USA.
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Dsouza DL, Boesen EI. Sensitivity to Iron‐Mediated Pro‐Inflammatory Signaling in NZBWF1 Mice, a Model of Systemic Lupus Erythematosus. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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5
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Kakalij RM, Boesen EI. Developing a Mouse Model to Test the Impact of Metabolic Syndrome on Systemic Lupus Erythematosus‐Induced Organ Damage. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tang W, Jogdeo CM, Panja S, Tang S, Ding L, Yu A, Foster KW, Dsouza D, Chhonker YS, Jensen-Smith H, Jang HS, Boesen EI, Murry DJ, Padanilam B, Oupický D. Modified chitosan for effective renal delivery of siRNA to treat acute kidney injury. Biomaterials 2022; 285:121562. [DOI: 10.1016/j.biomaterials.2022.121562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 04/02/2022] [Accepted: 05/01/2022] [Indexed: 11/02/2022]
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Theut LR, Dsouza DL, Grove RC, Boesen EI. Evidence of Renal Iron Accumulation in a Male Mouse Model of Lupus. Front Med (Lausanne) 2020; 7:516. [PMID: 33015091 PMCID: PMC7506121 DOI: 10.3389/fmed.2020.00516] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022] Open
Abstract
Lupus nephritis represents a common and serious complication of the autoimmune disease Systemic Lupus Erythematosus (SLE). Clinical studies suggest that several proteins related to iron metabolism, including transferrin, serve as urinary biomarkers of lupus nephritis. We previously reported that in female NZBWF1 mice, a commonly used mouse model of SLE with a female sex bias, increased urinary transferrin excretion and renal iron accumulation occur around the onset of albuminuria. The current study investigated whether similar findings occur in male mice of a different mouse model of SLE, the MRL/lpr mouse. Two different cohorts were studied: MRL/lpr mice at an early, pre-albuminuric age (8 weeks), and after developing albuminuria (>100 mg/dL, confirmed by ELISA); age-matched MRL/MpJ control strain mice served for comparison. Urinary transferrin excretion was dramatically increased in the older, albuminuric MRL/lpr mice compared to the age-matched MRL/MpJ (P < 0.05), but there was no significant difference between strains at 8 weeks of age. Similarly, there were no significant differences between strains in renal cortical or outer medullary non-heme iron concentrations at 8 weeks. In the older, albuminuric MRL/lpr mice, renal cortical and outer medullary non-heme iron concentrations were significantly increased compared with age-matched MRL/MpJ mice, as was the expression of the iron storage protein ferritin (P < 0.01). Together, these data show that increased urinary transferrin excretion and renal tissue iron accumulation also occurs in albuminuric male MRL/lpr mice, suggesting that renal iron accumulation may be a feature of multiple mouse models of SLE.
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Affiliation(s)
- Lindsey R Theut
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Del L Dsouza
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ryan C Grove
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Erika I Boesen
- Department of Cellular & Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
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Boesen EI. ET A receptor activation contributes to T cell accumulation in the kidney following ischemia-reperfusion injury. Physiol Rep 2018; 6:e13865. [PMID: 30198212 PMCID: PMC6129774 DOI: 10.14814/phy2.13865] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 08/20/2018] [Indexed: 12/19/2022] Open
Abstract
Renal ischemia-reperfusion (IR) injury and acute kidney injury (AKI) increase the risk of developing hypertension, with T cells suspected as a possible mechanistic link. Endothelin promotes renal T cell infiltration in several diseases, predominantly via the ETA receptor, but its contribution to renal T cell infiltration following renal IR injury is poorly understood. To test whether ETA receptor activation promotes T cell infiltration of the kidney following IR injury, male C57BL/6 mice were treated with the ETA receptor antagonist ABT-627 or vehicle, commencing 2 days prior to unilateral renal IR injury. Mice were sacrificed at 24 h or 10 days post-IR for assessment of the initial renal injury and subsequent infiltration of T cells. Vehicle and ABT-627-treated mice displayed significant upregulation of endothelin-1 (ET-1) in the IR compared to contralateral kidney at both 24 h and 10 days post-IR (P < 0.001). Renal CD3+ T cell numbers were increased in the IR compared to contralateral kidneys at 10 days, but ABT-627-treated mice displayed a 35% reduction in this effect in the outer medulla (P < 0.05 vs. vehicle) and a nonsignificant 23% reduction in the cortex compared to vehicle-treated mice. Whether specific T cell subsets were affected awaits confirmation by flow cytometry, but outer medullary expression of the T helper 17 transcription factor RORγt was reduced by ABT-627 (P = 0.06). These data indicate that ET-1 acting via the ETA receptor contributes to renal T cell infiltration post-IR injury. This may have important implications for immune system-mediated long-term consequences of AKI, an area which awaits further investigation.
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Affiliation(s)
- Erika I. Boesen
- Department of Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNebraska
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Boesen EI, Bonnemaison ML. Endoplasmic Reticulum Stress Promotes the Development and Progression of Lupus Nephritis. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.849.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Boesen EI, Rahman SS, Band H. EHD4 Regulates Prostaglandin E2 Synthesis in Renal Collecting Duct Principal Cells: Potential Implications for AQP2. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.619.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I. Boesen
- Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Shamma S. Rahman
- Cellular & Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Hamid Band
- Eppley InstituteUniversity of Nebraska Medical CenterOmahaNE
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11
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Marks ES, Bonnemaison ML, Brusnahan SK, Zhang W, Fan W, Garrison JC, Boesen EI. Renal iron accumulation occurs in lupus nephritis and iron chelation delays the onset of albuminuria. Sci Rep 2017; 7:12821. [PMID: 28993663 PMCID: PMC5634457 DOI: 10.1038/s41598-017-13029-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 09/19/2017] [Indexed: 12/11/2022] Open
Abstract
Proteins involved in iron homeostasis have been identified as biomarkers for lupus nephritis, a serious complication of systemic lupus erythematosus (SLE). We tested the hypothesis that renal iron accumulation occurs and contributes to renal injury in SLE. Renal non-heme iron levels were increased in the (New Zealand Black x New Zealand White) F1 (NZB/W) mouse model of lupus nephritis compared with healthy New Zealand White (NZW) mice in an age- and strain-dependent manner. Biodistribution studies revealed increased transferrin-bound iron accumulation in the kidneys of albuminuric NZB/W mice, but no difference in the accumulation of non-transferrin bound iron or ferritin. Transferrin excretion was significantly increased in albuminuric NZB/W mice, indicating enhanced tubular exposure and potential for enhanced tubular uptake following filtration. Expression of transferrin receptor and 24p3R were reduced in tubules from NZB/W compared to NZW mice, while ferroportin expression was unchanged and ferritin expression increased, consistent with increased iron accumulation and compensatory downregulation of uptake pathways. Treatment of NZB/W mice with the iron chelator deferiprone significantly delayed the onset of albuminuria and reduced blood urea nitrogen concentrations. Together, these findings suggest that pathological changes in renal iron homeostasis occurs in lupus nephritis, contributing to the development of kidney injury.
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Affiliation(s)
- Eileen S Marks
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Mathilde L Bonnemaison
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Susan K Brusnahan
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wenting Zhang
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Wei Fan
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Jered C Garrison
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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12
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Rahman SS, Moffitt AEJ, Trease AJ, Foster KW, Storck MD, Band H, Boesen EI. EHD4 is a novel regulator of urinary water homeostasis. FASEB J 2017; 31:5217-5233. [PMID: 28778975 DOI: 10.1096/fj.201601182rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 07/25/2017] [Indexed: 01/08/2023]
Abstract
The Eps15-homology domain-containing (EHD) protein family comprises 4 members that regulate endocytic recycling. Although the kidney expresses all 4 EHD proteins, their physiologic roles are largely unknown. This study focused on EHD4, which we found to be expressed differentially across nephron segments with the highest expression in the inner medullary collecting duct. Under baseline conditions, Ehd4-/- [EHD4-knockout (KO)] mice on a C57Bl/6 background excreted a higher volume of more dilute urine than control C57Bl/6 wild-type (WT) mice while maintaining a similar plasma osmolality. Urine excretion after an acute intraperitoneal water load was significantly increased in EHD4-KO mice compared to WT mice, and although EHD4-KO mice concentrated their urine during 24-h water restriction, urinary osmolality remained significantly lower than in WT mice, suggesting that EHD4 plays a role in renal water handling. Total aquaporin 2 (AQP2) and phospho-S256-AQP2 (pAQP2) protein expression in the inner medulla was similar in the two groups in baseline conditions. However, localization of both AQP2 and pAQP2 in the renal inner medullary principal cells appeared more dispersed, and the intensity of apical membrane staining for AQP2 was reduced significantly (by ∼20%) in EHD4-KO mice compared to WT mice in baseline conditions, suggesting an important role of EHD4 in trafficking of AQP2. Together, these data indicate that EHD4 play important roles in the regulation of water homeostasis.-Rahman, S. S., Moffitt, A. E. J., Trease, A. J., Foster, K. W., Storck, M. D., Band, H., Boesen, E. I. EHD4 is a novel regulator of urinary water homeostasis.
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Affiliation(s)
- Shamma S Rahman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Alexandra E J Moffitt
- The Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Andrew J Trease
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Kirk W Foster
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Matthew D Storck
- The Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Hamid Band
- The Eppley Institute for Research in Cancer, University of Nebraska Medical Center, Omaha, Nebraska, USA; .,Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA.,Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA.,Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, USA.,Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska, USA; and.,Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, USA;
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Boesen EI. Lack of an apparent role for endothelin-1 in the prolonged reduction in renal perfusion following severe unilateral ischemia-reperfusion injury in the mouse. Physiol Rep 2016; 4:4/21/e13027. [PMID: 27905299 PMCID: PMC5112503 DOI: 10.14814/phy2.13027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/12/2016] [Accepted: 10/13/2016] [Indexed: 12/31/2022] Open
Abstract
Therapeutic approaches to block the progression from acute kidney injury to chronic kidney disease are currently lacking. Endothelin‐1 (ET‐1) is a powerful vasoconstrictor, induced by hypoxia, and previously implicated in renal ischemia‐reperfusion (IR) injury. This study tested the hypothesis that blunting the vascular influence of ET‐1, either through endothelin ETA receptor blockade (ABT‐627) or vascular endothelial cell deletion of ET‐1 (VEET KO), would improve recovery of renal perfusion and repair of injury following a severe ischemic insult in mice (45 min unilateral renal ischemia). Male C57Bl/6 mice receiving vehicle or ABT‐627 commencing 2 days prior to surgery, and VEET KO mice and wild‐type littermates (WT) underwent 45 min unilateral renal IR surgery followed by 28 days recovery. Renal blood velocity was measured by pulsed‐wave Doppler ultrasound before and after surgery. Renal blood velocity was not significantly different between pairs of groups before surgery. Unilateral IR induced a marked reduction in renal blood velocity of the IR kidney at 24 h postsurgery in all groups, which partially recovered but remained below baseline at 28 days post‐IR. Despite the lack of effect on renal blood velocity, ETA receptor blockade significantly attenuated the atrophy of the post‐IR kidney, whereas this was not significantly affected by lack of endothelial ET‐1 expression. These data suggest that although blockade of the ETA receptor is mildly beneficial in preserving renal mass following a severe ischemic insult, this protective effect does not appear to involve improved recovery of renal perfusion.
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Affiliation(s)
- Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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Rahman SS, Boesen EI. Outside the mainstream: novel collecting duct proteins regulating water balance. Am J Physiol Renal Physiol 2016; 311:F1341-F1345. [PMID: 27784697 DOI: 10.1152/ajprenal.00488.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/06/2016] [Accepted: 10/18/2016] [Indexed: 12/26/2022] Open
Abstract
Body water balance is critical to survival and, therefore, very tightly regulated by the hypothalamus and kidney. A key mechanism involved in this process, the arginine vasopressin-mediated phosphorylation and apical membrane insertion of aquaporin 2 in the collecting duct, has been extensively studied; however, with the increased availability of conditional knockout animals, several novel collecting duct proteins have recently been implicated in water homeostasis. In this Mini-Review, we briefly discuss these novel proteins and their roles in the regulation of water homeostasis.
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Affiliation(s)
- Shamma S Rahman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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15
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Cheema MU, Irsik DL, Wang Y, Miller-Little W, Hyndman KA, Marks ES, Frøkiær J, Boesen EI, Norregaard R. Estradiol regulates AQP2 expression in the collecting duct: a novel inhibitory role for estrogen receptor α. Am J Physiol Renal Physiol 2015; 309:F305-17. [PMID: 26062878 DOI: 10.1152/ajprenal.00685.2014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 05/30/2015] [Indexed: 11/22/2022] Open
Abstract
While there is evidence that sex hormones influence multiple systems involved in salt and water homeostasis, the question of whether sex hormones regulate aquaporin-2 (AQP2) and thus water handling by the collecting duct has been largely ignored. Accordingly, the present study investigated AQP2 expression, localization and renal water handling in intact and ovariectomized (OVX) female rats, with and without estradiol or progesterone replacement. OVX resulted in a significant increase in urine osmolality and increase in p256-AQP2 in the renal cortex at 7 days post-OVX, as well as induced body weight changes. Relative to OVX alone, estradiol repletion produced a significant increase in urine output, normalized urinary osmolality and reduced both total AQP2 (protein and mRNA) and p256-AQP2 expression, whereas progesterone repletion had little effect. Direct effects of estradiol on AQP2 mRNA and protein levels were further tested in vitro using the mpkCCD principal cell line. Estradiol treatment of mpkCCD cells reduced AQP2 at both the mRNA and protein level in the absence of deamino-8-d-AVP (dDAVP) and significantly blunted the dDAVP-induced increase in AQP2 at the protein level only. We determined that mpkCCD and native mouse collecting ducts express both estrogen receptor (ER)α and ERβ and that female mice lacking ERα displayed significant increases in AQP2 protein compared with wild-type littermates, implicating ERα in mediating the inhibitory effect of estradiol on AQP2 expression. These findings suggest that changes in estradiol levels, such as during menopause or following reproductive surgeries, may contribute to dysregulation of water homeostasis in women.
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Affiliation(s)
| | - Debra L Irsik
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Yan Wang
- Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Kelly A Hyndman
- Division of Nephrology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Eileen S Marks
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Jørgen Frøkiær
- Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Rikke Norregaard
- Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark;
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Merchen TD, Boesen EI, Gardner JR, Harbarger R, Kitamura E, Mellor A, Pollock DM, Ghaffari A, Podolsky R, Nahman NS. Indoleamine 2,3-dioxygenase inhibition alters the non-coding RNA transcriptome following renal ischemia-reperfusion injury. Transpl Immunol 2014; 30:140-4. [PMID: 24751756 DOI: 10.1016/j.trim.2014.04.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 04/10/2014] [Accepted: 04/11/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUND Indoleamine 2,3 dioxygenase (IDO) degrades the essential amino acid tryptophan and has been shown to minimize rejection in animal models of renal transplantation. Ischemia-reperfusion injury (IRI) is unavoidable in renal transplantation and correlates with shorter graft survival times. Despite its favorable effects on rejection, there is evidence that IDO may facilitate renal IRI. Differentiating the negative impact of IDO on IRI from its pro-tolerant effects in allograft rejection is of clinical relevance. In these studies we hypothesized that constitutive IDO activity may influence renal genes associated with recovery from IRI, and that IDO inhibition may unmask these effects. METHODS We examined the renal transcriptome in a rat model of IRI with and without IDO inhibition with 1-methyl-d-tryptophan (1-MT), and assessed for alterations in the gene expression signature. RESULTS These studies demonstrated that during recovery from renal IRI, pre-treatment with 1-MT alleviated alterations in 105 coding sequences associated with IRI, and in turn triggered new changes in 66 non-coding transcripts, the majority of which were represented by small nucleolar RNA. CONCLUSION These results suggest a biologic role for non-coding, IDO-dependent genes in regulating the early response to IRI.
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Affiliation(s)
- Todd D Merchen
- Department of Surgery, Georgia Regents University, Augusta, GA, United States
| | - Erika I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - John R Gardner
- Department of Medicine, Georgia Regents University Augusta, GA, United States
| | - Rachel Harbarger
- Immunotherapy Center, Georgia Regents University Augusta, GA, United States
| | - Eiko Kitamura
- Genomics Core, Comprehensive Cancer Center, Georgia Regents UniversityAugusta, GA, United States
| | - Andrew Mellor
- Immunotherapy Center, Georgia Regents University Augusta, GA, United States
| | - David M Pollock
- Department of Medicine, Georgia Regents University Augusta, GA, United States
| | - Arina Ghaffari
- Department of Surgery, Georgia Regents University, Augusta, GA, United States
| | - Robert Podolsky
- Department of Medicine, Georgia Regents University Augusta, GA, United States; Center for Biotechnology and Genomic Medicine, Georgia Regents UniversityAugusta, GA, United States; Department of Biostatistics, Georgia Regents University, Augusta, GA, United States
| | - N Stanley Nahman
- Department of Medicine, Georgia Regents University Augusta, GA, United States; Department of Medicine Georgia Regents University, Charlie Norwood VAMC, Augusta, GA, United States.
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Abstract
Chronic renal inflammation is an increasingly recognized phenomenon in multiple disease states, but the impact of specific cytokines on renal function is unclear. Previously, we found that 14-day interleukin-1β (IL-1β) infusion increased urine flow in mice. To determine the mechanism by which this occurs, the current study tested the possible involvement of three classical prodiuretic pathways. Chronic IL-1β infusion significantly increased urine flow (6.5 ± 1 ml/day at day 14 vs. 2.3 ± 0.3 ml/day in vehicle group; P < 0.05) and expression of cyclooxygenase (COX)-2, all three nitric oxide synthase (NOS) isoforms, and endothelin (ET)-1 in the kidney (P < 0.05 in all cases). Urinary prostaglandin E metabolite (PGEM) excretion was also significantly increased at day 14 of IL-1β infusion (1.21 ± 0.26 vs. 0.29 ± 0.06 ng/day in vehicle-infused mice; P = 0.001). The selective COX-2 inhibitor celecoxib markedly attenuated urinary PGEM excretion and abolished the diuretic response to chronic IL-1β infusion. In contrast, deletion of NOS3, or inhibition of NOS1 with L-VNIO, did not blunt the diuretic effect of IL-1β, nor did pharmacological blockade of endothelin ETA and ETB receptors with A-182086. Consistent with a primary effect on water transport, IL-1β infusion markedly reduced inner medullary aquaporin-2 expression (P < 0.05) and did not alter urinary Na⁺ or K⁺ excretion. These data indicate a critical role for COX-2 in mediating the effects of chronic IL-1β elevation on the kidney.
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Affiliation(s)
- E I Boesen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, USA.
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18
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Hyndman KA, Boesen EI, Elmarakby AA, Brands MW, Huang P, Kohan DE, Pollock DM, Pollock JS. Renal collecting duct NOS1 maintains fluid-electrolyte homeostasis and blood pressure. Hypertension 2013; 62:91-8. [PMID: 23608660 DOI: 10.1161/hypertensionaha.113.01291] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nitric oxide is a pronatriuretic and prodiuretic factor. The highest renal NO synthase (NOS) activity is found in the inner medullary collecting duct. The collecting duct (CD) is the site of daily fine-tune regulation of sodium balance, and led us to hypothesize that a CD-specific deletion of NOS1 would result in an impaired ability to excrete a sodium load leading to a salt-sensitive blood pressure phenotype. We bred AQP2-CRE mice with NOS1 floxed mice to produce flox control and CD-specific NOS1 knockout (CDNOS1KO) littermates. CDs from CDNOS1KO mice produced 75% less nitrite, and urinary nitrite+nitrate (NOx) excretion was significantly blunted in the knockout genotype. When challenged with high dietary sodium, CDNOS1KO mice showed significantly reduced urine output, sodium, chloride, and NOx excretion, and increased mean arterial pressure relative to flox control mice. In humans, urinary NOx is a newly identified biomarker for the progression of hypertension. These findings reveal that NOS1 in the CD is critical in the regulation of fluid-electrolyte balance, and this new genetic model of CD NOS1 gene deletion will be a valuable tool to study salt-dependent blood pressure mechanisms.
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Affiliation(s)
- Kelly A Hyndman
- Section of Experimental Medicine, Department of Medicine, Georgia Regents University, Augusta, GA 30912, USA
| | | | - Ahmed A Elmarakby
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Mansoura University, Egypt
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19
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Boesen EI, Crislip GR, Sullivan JC. Use of ultrasound to assess renal reperfusion and P-selectin expression following unilateral renal ischemia. Am J Physiol Renal Physiol 2012; 303:F1333-40. [PMID: 22933301 DOI: 10.1152/ajprenal.00406.2012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Renal ischemia-reperfusion injury is a major cause of acute kidney injury that carries a high mortality rate and increases the risk of later development of hypertension and chronic kidney disease. Although mouse models have contributed much to our understanding of the mechanisms involved, studying aspects of the injury process in vivo remains technically challenging. This study validates the use of noninvasive ultrasound imaging to assess both renal perfusion and vascular adhesion molecule expression following 1-h unilateral renal ischemia in male and female mice. Pulsed-wave Doppler measurements of renal arterial blood velocity revealed renal perfusion recoveries of 56 ± 9% in male and 69 ± 10% in female mice 1 h after the commencing of reperfusion, which is similar to what we have previously published using conventional invasive methodology. At 24 h postischemia, renal perfusion was 40 ± 8% in male and 46 ± 7% in female mice, representing a further significant reduction of perfusion (P(Time) < 0.001). Using ultrasound imaging of a P-selectin-targeted contrast agent, a significant increase in vascular P-selectin protein expression was observed after 1-h reperfusion in the cortex of the postischemic compared with contralateral kidney in both male and female mice (18 ± 5 vs. 3 ± 3 intensity units in male and 30 ± 6 vs. 0 ± 4 in female mice, P(Ischemia) < 0.01). An approximately sixfold increase in P-selectin mRNA was observed ex vivo in the renal vasculature of male and female mice at this time point (P < 0.01). In conclusion, ultrasound represents an effective and noninvasive method for the measurement of both renal perfusion and vascular adhesion molecule expression in mice.
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Affiliation(s)
- Erika I Boesen
- Section of Experimental Medicine, Department of Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA
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20
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Boesen EI, Zoll KE. Endothelin ET
A
receptor blockade does not attenuate the rise in early markers of acute kidney injury following bilateral renal ischemia. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.868.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Kyle E Zoll
- MedicineGeorgia Health Sciences UniversityAugustaGA
- University of EvansvilleEvansvilleIN
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21
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Boesen EI, Krishnan KR, Pollock JS, Pollock DM. ETA activation mediates angiotensin II-induced infiltration of renal cortical T cells. J Am Soc Nephrol 2011; 22:2187-92. [PMID: 22021713 DOI: 10.1681/asn.2010020193] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
T cells and endothelin (ET-1) both contribute to angiotensin II (AngII)-dependent hypertension. To determine whether ET-1, via the ET(A) receptor, facilitates T cell infiltration in the kidney during AngII-dependent hypertension, we measured T cell infiltration in response to four different treatments: saline, AngII infusion, AngII infusion with an ET(A) receptor antagonist, or AngII infusion with triple-antihypertensive therapy. After 14 days, AngII increased both BP and the numbers of CD3(+) and proliferating cells in the kidney. Mice treated concomitantly with the ET(A) receptor antagonist had lower BP and fewer CD3(+) and proliferating cells in the renal cortex. Mice treated with triple therapy had similar reductions in BP but no change in renal cortical CD3(+) cells compared with kidneys from AngII-infused hypertensive mice. In the outer medulla, both the ET(A) receptor antagonist and triple therapy reduced the number of CD3(+) cells and macrophages. Taken together, these data suggest that ET(A) receptor activation in AngII-mediated hypertension increases CD3(+) cells and proliferation in the renal cortex independent of changes in BP, but changes in the number of inflammatory cells in the renal medulla are BP dependent.
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Affiliation(s)
- Erika I Boesen
- Experimental Medicine, Georgia Health Sciences University, Augusta, GA 30912, USA.
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22
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Boesen EI, Williams DL, Pollock JS, Pollock DM. Immunosuppression with mycophenolate mofetil attenuates the development of hypertension and albuminuria in deoxycorticosterone acetate-salt hypertensive rats. Clin Exp Pharmacol Physiol 2011; 37:1016-22. [PMID: 20626757 DOI: 10.1111/j.1440-1681.2010.05428.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
1. The interplay between the immune and renin-angiotensin systems is emerging as a crucial factor in the development and progression of hypertension. The aim of the present study was to determine the involvement of immune cells in the hypertension and renal injury produced by a non-angiotensin II-dependent form of hypertension, namely deoxycorticosterone acetate (DOCA)-salt-induced hypertension, in rats. 2. Male Sprague-Dawley rats underwent uninephrectomy and received either a sustained-release pellet of DOCA s.c. and 0.9% NaCl (saline) to drink for 21 days or a placebo pellet and water to drink for 21 days. Additional groups of DOCA-salt- and placebo-treated rats were treated concurrently with the immune suppressant mycophenolate mofetil (MMF; 30 mg/kg per day). Rats were placed in metabolic cages for 24 h urine collection prior to and at weekly intervals during the 21 day experimental period. 3. Mycophenolate mofetil significantly attenuated the development of hypertension in DOCA-salt rats compared with untreated DOCA-salt hypertensive rats (mean arterial pressure by telemetry on Day 18,146 ± 7 vs 180 ± 3 mmHg, respectively; P < 0.001), as well as proteinuria (87 ± 27 vs 305 ± 63 mg/day, respectively, on Day 21) and albuminuria (51 ± 15 vs 247 ± 73 mg/day, respectively, on Day 21). Creatinine clearance was better preserved in MMF-treated DOCA-salt rats compared with untreated DOCA-salt rats (0.74 ± 0.07 vs 0.49 ± 0.09 mL/min, respectively; P < 0.05), but was still significantly reduced compared with that in the placebo group (1.15 ± 0.12 mL/min; P < 0.05). Finally, MMF treatment significantly attenuated the DOCA-salt-induced rise in renal cortical T-lymphocyte and macrophage infiltration (P < 0.05). 4. These data indicate that immune cells play a deleterious role in both the hypertension and renal injury associated with DOCA-salt hypertension.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, Augusta, Georgia 30912, USA.
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23
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Boesen EI. Chronic elevation of IL‐1β induces diuresis independently of endothelin: potential involvement of cyclo‐oxygenase and nitric oxide synthase pathways. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1079.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology CenterGeorgia Health Sciences UniversityAugustaGA
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24
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Saleh MA, Boesen EI, Pollock JS, Savin VJ, Pollock DM. Endothelin receptor A-specific stimulation of glomerular inflammation and injury in a streptozotocin-induced rat model of diabetes. Diabetologia 2011; 54:979-88. [PMID: 21191784 PMCID: PMC3804244 DOI: 10.1007/s00125-010-2021-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 11/29/2010] [Indexed: 10/18/2022]
Abstract
AIMS/HYPOTHESIS Activation of endothelin receptor-A (ET(A)) increases glomerular permeability to albumin (P(alb)) and elevates pro-inflammatory markers in hyperglycaemic rats. METHODS Male Sprague-Dawley rats were given streptozotocin (n = 32) or saline (sham; n = 32). Half of the animals in each group received the ET(A)-selective antagonist, ABT-627 (atrasentan; orally), beginning immediately after hyperglycaemia was confirmed. Glomeruli were isolated by sieving techniques and P(alb) determined from the change in glomerular volume induced by oncotic gradients of albumin. Glomerular nephrin levels were assessed by immunofluorescence, whereas urinary nephrin was measured by immunoassay. RESULTS At 3 and 6 weeks after streptozotocin injection, proteinuria was significantly increased compared with sham controls and significantly reduced by ABT-627 treatment. P(alb) was also increased at 3 and 6 weeks post-streptozotocin. ABT-627 had no effect on P(alb) or protein excretion in sham control rats. In glomeruli isolated from hyperglycaemic rats, incubation with BQ-123, a selective ET(A) antagonist, reduced P(alb), whereas BQ-788, a selective endothelin receptor-B antagonist had no effect (n = 6 rats per group, 5-8 glomeruli per rat). Glomerular and plasma content of soluble intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 were significantly increased 6 weeks after streptozotocin (ELISA). ABT-627 attenuated these increases. After 6 weeks of hyperglycaemia, glomerular nephrin content was decreased with a concurrent increase in urinary nephrin excretion. ABT-627 prevented glomerular nephrin loss in hyperglycaemic rats (n = 5-8 rats per group; eight groups). CONCLUSIONS/INTERPRETATION These observations support the hypothesis that endothelin-1, via the ET(A) receptor, directly increases P(alb), possibly via nephrin loss, as well as early inflammation in the hyperglycaemic rat.
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Affiliation(s)
- M A Saleh
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd, Augusta, GA 30907-2500, USA
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25
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Boesen EI, Pollock JS, Pollock DM. Contrasting effects of intervention with ETA and ETB receptor antagonists in hypertension induced by angiotensin II and high-salt diet. Can J Physiol Pharmacol 2011; 88:802-7. [PMID: 20725138 DOI: 10.1139/y10-051] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelin (ET) receptor antagonists are antihypertensive and renoprotective in angiotensin II (AngII)-induced hypertension if administered when AngII infusion commences, but their effects on established hypertension are poorly understood. We therefore tested the effects of intervening with an ETA (ABT-627) or ETB (A-192621) receptor antagonist after establishing hypertension with AngII (65 ng/min s.c.) plus 8% NaCl diet (AngII-HS) in rats. Prior to administration of ABT-627, AngII-HS and AngII-HS plus ABT-627 groups displayed robust hypertension (mean arterial pressure (MAP), 170 +/- 5 and 165 +/- 5 mm Hg versus 110 +/- 3 mm Hg in normal salt control rats at day 7, P < 0.05). Administering ABT-627 from day 8 of AngII-HS treatment prevented further rises in MAP (168 +/- 5 and 191 +/- 3 mm Hg at day 13 in AngII-HS plus ABT-627 and AngII-HS, P < 0.001), without blunting the significant increases in urinary protein (19-fold), albumin (25-fold), or MCP-1 excretion (6- to 8-fold) or the reduction in creatinine clearance. Administering A-192621 from day 8 mildly exacerbated AngII-HS induced hypertension (P < 0.05 for AngII-HS versus AngII-HS plus A-192621 on days 11 and 12 only) and reduced plasma nitrite/nitrate concentration (P < 0.05), without affecting proteinuria, albuminuria, or creatinine clearance. These results confirm the importance of ETA receptor signaling in maintaining AngII-HS hypertension and suggest that including ETB receptor blockade in therapeutic approaches to treating hypertension would be ineffective or even counterproductive.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Boulevard, Augusta, GA 30912, USA.
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26
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Boesen EI, Pollock DM. Cooperative role of ETA and ETB receptors in mediating the diuretic response to intramedullary hyperosmotic NaCl infusion. Am J Physiol Renal Physiol 2010; 299:F1424-32. [PMID: 20844020 DOI: 10.1152/ajprenal.00015.2010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acute intramedullary infusion of hyperosmotic NaCl, used to simulate a high-salt diet-induced increase of medullary osmolality, increases urine production and endothelin release from the kidney. To determine whether endothelin mediates this diuretic and natriuretic response, urine flow and Na(+) excretion rate were measured during acute intramedullary infusion of hyperosmotic NaCl in anesthetized rats, with or without endothelin receptor antagonism. Isosmotic NaCl was infused into the left renal medulla during an equilibration period and 30-min baseline period, followed by hyperosmotic NaCl for two additional 30-min periods. Hyperosmotic NaCl infusion significantly increased urine flow of vehicle-treated rats (from 5.9 ± 0.9 to 11.1 ± 1.8 μl/min). Systemic ET(B) receptor blockade enhanced this effect (A-192621; from 7.7 ± 1.1 to 18.7 ± 2.9 μl/min; P < 0.05), ET(A) receptor blockade (ABT-627) had no significant effect alone, but the diuresis was markedly attenuated by combined ABT-627 and A-192621 administration (from 4.4 ± 0.7 to 5.4 ± 0.9 μl/min). Mean arterial pressures overall were not significantly different between groups. Surprisingly, the natriuretic response to hyperosmotic NaCl infusion was not significantly altered by systemic endothelin receptor blockade, and furthermore, intramedullary ET(B) receptor blockade enhanced the diuretic and natriuretic response to hyperosmotic NaCl infusion. ET(A) receptor blockade significantly attenuated both the diuretic and natriuretic responses to hyperosmotic NaCl infusion in ET(B) receptor-deficient sl/sl rats. These results demonstrate an important role of endothelin in mediating diuretic responses to intramedullary infusion of hyperosmotic NaCl. Moreover, these data suggest ET(A) and ET(B) receptors are both required for the full diuretic and natriuretic actions of endothelin.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd., Augusta, GA 30912, USA.
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27
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Saleh MA, Boesen EI, Pollock JS, Savin VJ, Pollock DM. Endothelin-1 increases glomerular permeability and inflammation independent of blood pressure in the rat. Hypertension 2010; 56:942-9. [PMID: 20823379 DOI: 10.1161/hypertensionaha.110.156570] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Endothelin (ET) 1 is a potent vasoactive peptide implicated in the pathogenesis of hypertension and renal disease. The aim of the current study was to test the hypotheses that ET-1 increases albumin permeability of glomeruli isolated from normal rats and that chronic ET-1 infusion will increase glomerular permeability and inflammation independent of blood pressure. Glomerular permeability to albumin was determined from the change in glomerular volume induced by exposing isolated glomeruli to oncotic gradients. Incubation of glomeruli taken from normal rats with ET-1 at a concentration that did not produce direct glomerular contraction (1 nmol/L) significantly increased glomerular permeability to albumin, reaching a maximum after 4 hours. Chronic ET-1 infusion for 2 weeks in Sprague-Dawley rats significantly increased glomerular permeability to albumin and nephrin excretion rate, effects that were attenuated in rats given an ET(A) receptor antagonist (ABT-627, 5 mg/kg per day). Urinary protein and albumin excretion and mean arterial pressure (telemetry) were not changed by ET-1 infusion. Acute incubation of glomeruli isolated from ET-1-infused rats with the selective ET(A) antagonist significantly reduced glomerular permeability to albumin, an effect not observed with acute treatment with a selective ET(B) antagonist. Chronic ET-1 infusion increased glomerular and plasma soluble intercellular adhesion molecule 1 and monocyte chemoattractant protein 1 and elevated the number of macrophages and lymphocytes in renal cortices (ED-1 and CD3-positive staining, respectively). These effects were all attenuated in rats given an ET(A) selective antagonist. These data support the hypothesis that ET-1 directly increases glomerular permeability to albumin and renal inflammation via ET(A) receptor activation independent of changes in arterial pressure.
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Affiliation(s)
- Mohamed A Saleh
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA
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28
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Allahdadi KJ, Hannan JL, Boesen EI, Webb RC. Augmented endothelin‐1 constriction in pudendal arteries from ETB receptor‐deficient rats: linking hypertension and female sexual dysfunction. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.985.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Affiliation(s)
- David M Pollock
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA.
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30
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Sullivan JC, Wang B, Boesen EI, D'Angelo G, Pollock JS, Pollock DM. Novel use of ultrasound to examine regional blood flow in the mouse kidney. Am J Physiol Renal Physiol 2009; 297:F228-35. [PMID: 19420115 DOI: 10.1152/ajprenal.00016.2009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Conventional methods used for measuring regional renal blood flow, such as laser-Doppler flowmetry, are highly invasive, and each measurement is restricted to a discrete location. The aim of this study was to determine whether ultrasound imaging in conjunction with enhanced contrast agent (microbubbles; Vevo MicroMarker, VisualSonics) could provide a viable noninvasive alternative. This was achieved by determining changes in renal cortical and medullary rate of perfusion in response to a bolus injection of endothelin-1 (ET-1; 0.6, 1.0, or 2.0 nmol/kg) and comparing these responses to those observed in separate groups of mice with conventional laser-Doppler methods. Intravenous infusion of ET-1 in anesthetized male C57bl/6 mice resulted in a dose-dependent increase in mean arterial pressure and a dose-dependent decrease in total renal blood flow as measured by pulse-wave Doppler. ET-1 infusion resulted in a dose-dependent decrease in regional kidney perfusion as measured by both ultrasound with enhanced contrast agent and laser-Doppler measurements, verifying the use of ultrasound to measure regional kidney perfusion. Noted limitations of ultrasound imaging compared with laser-Doppler flowmetry included a lower degree of sensitivity to changes in tissue perfusion and the inability to assess rapid or transient changes in tissue perfusion. In conclusion, ultrasound represents an effective and noninvasive method for the measurement of relatively short-term, steady-state changes in regional blood flow in the mouse kidney.
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Affiliation(s)
- Jennifer C Sullivan
- Vascular Biology Center and Department of Pharmacology, Medical College of Georgia, Augusta, Georgia 30912, USA.
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31
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Kittikulsuth W, Boesen EI, Pollock DM. Natriuretic response to renal medullary endothelin B receptor activation is blunted in chronic angiotensin II‐infused rats. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.lb145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Erika I Boesen
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
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32
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Boesen EI, Wang B, Pollock DM, Sullivan JC. Measurement of regional kidney perfusion in mice: comparison of a novel, non‐invasive technique against conventional laser‐Doppler flowmetry. FASEB J 2009. [DOI: 10.1096/fasebj.23.1_supplement.969.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
| | - Bin Wang
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
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34
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Boesen EI, Sasser JM, Saleh MA, Potter WA, Woods M, Warner TD, Pollock JS, Pollock DM. Interleukin-1beta, but not interleukin-6, enhances renal and systemic endothelin production in vivo. Am J Physiol Renal Physiol 2008; 295:F446-53. [PMID: 18524861 DOI: 10.1152/ajprenal.00095.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The inflammatory cytokines IL-1beta and IL-6 have been shown to stimulate production of endothelin-1 (ET-1) by several cell types in vitro, but their effects on renal ET-1 production in vivo are not known. To test whether IL-1beta and IL-6 stimulate renal ET-1 production and release in vivo, urine was collected from male C57BL/6 mice over 24-h periods at baseline and on days 7 and 14 of a 14-day subcutaneous infusion of IL-1beta (10 ng/h), IL-6 (16 ng/h), or vehicle. By day 14, plasma ET-1 was significantly increased by IL-1beta infusion (1.7 +/- 0.1 vs. 0.8 +/- 0.1 pg/ml for vehicle, P < 0.001). Compared with vehicle infusion, IL-1beta infusion induced significant increases in urinary ET-1 excretion rate and urine flow but did not affect conscious mean arterial pressure (telemetry). IL-1beta infusion significantly increased renal cortical and medullary IL-1beta content (ELISA) and prepro-ET-1 mRNA expression (quantitative real-time PCR). In contrast, 14 days of IL-6 infusion had no significant effect on plasma ET-1 or urinary ET-1 excretion rate. To determine whether IL-1beta stimulates ET-1 release via activation of NF-kappaB, inner medullary collecting duct (IMCD-3) cells were incubated for 24 h with IL-1beta, and ET-1 release and NF-kappaB activation were measured (ELISA). IL-1beta activated NF-kappaB and increased ET-1 release in a concentration-dependent manner. The effect of IL-1beta on ET-1 release could be partially inhibited by pretreatment of IMCD-3 cells with an inhibitor of NF-kappaB activation (BAY 11-7082). These results indicate that IL-1beta stimulates renal and systemic ET-1 production in vivo, providing further evidence that ET-1 participates in inflammatory responses.
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Affiliation(s)
- Erika I Boesen
- Department of Pharmacology and Vascular Biology Center, Medical College of Georgia, Augusta, Georgia, USA
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Saleh MA, Boesen EI, Pollock JS, Pollock DM. Chronic ETA receptor blockade attenuates expression of inflammatory mediators in diabetic rats. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.944.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Mohamed A Saleh
- Pharmacology and Toxicology
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
| | - Erika I Boesen
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
| | - Jennifer S Pollock
- Pharmacology and Toxicology
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
| | - David M Pollock
- Pharmacology and Toxicology
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
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Nakano D, Middleton CL, Socha HM, Boesen EI, Pollock DM. Natriuretic activity of prehypertensive Dahl salt‐sensitive (DS) and salt‐resistant (SS13BN) rats. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1158.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Daisuke Nakano
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
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Boesen EI, Pollock JS, Pollock DM. Interleukin‐1 in chronic angiotensin II‐high salt diet induced hypertension. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.923.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology CenterMedical College of GeorgiaAugustaGA
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Stepp DW, Boesen EI, Sullivan JC, Mintz JD, Hair CD, Pollock DM. Obesity augments vasoconstrictor reactivity to angiotensin II in the renal circulation of the Zucker rat. Am J Physiol Heart Circ Physiol 2007; 293:H2537-42. [PMID: 17693541 DOI: 10.1152/ajpheart.01081.2006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obesity is an emerging risk factor for renal dysfunction, but the mechanisms are poorly understood. Obese patients show heightened renal vasodilation to blockade of the renin-angiotensin system, suggesting deficits in vascular responses to angiotensin II (ANG II). This study tested the hypothesis that obesity augments renal vasoconstriction to ANG II. Lean (LZR), prediabetic obese (OZR), and nonobese fructose-fed Zucker rats (FF-LZR) were studied to determine the effects of obesity and insulin resistance on reactivity of blood pressure and renal blood flow to vasoconstrictors. OZR showed enlargement of the kidneys, elevated urine output, increased sodium intake, and decreased plasma renin activity (PRA) vs. LZR, and renal vasoconstriction to ANG II was augmented in OZR. Renal reactivity to norepinephrine and mesenteric vascular reactivity to ANG II were similar between LZR and OZR. Insulin-resistant FF-LZR had normal reactivity to ANG II, indicating the insulin resistance was an unlikely explanation for the changes observed in OZR. Four weeks on a low-sodium diet (0.08%) to raise PRA reduced reactivity to ANG II in OZR back to normal levels without effect on LZR. From these data, we conclude that in the prediabetic stages of obesity, a decrease in PRA is observed in Zucker rats that may lead to increased renal vascular reactivity to ANG II. This increased reactivity to ANG II may explain the elevated renal vasodilator effects observed in obese humans and provide insight into early changes in renal function that predispose to nephropathy in later stages of the disease.
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Affiliation(s)
- David W Stepp
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd., Augusta, GA 30912, USA.
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Boesen EI, Anderson WP, Kett MM. ACUTE PRESSURE?NATRIURESIS RELATIONSHIP FOLLOWING WITHDRAWAL OF CHRONIC NORADRENALINE INFUSION. Clin Exp Pharmacol Physiol 2007; 34:881-3. [PMID: 17645634 DOI: 10.1111/j.1440-1681.2007.04634.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
1. Pathological changes to the kidney, such as vascular remodelling, have been found in several models of hypertension and may contribute to the maintenance of hypertension or confer susceptibility to redeveloping hypertension after the original prohypertensive stimulus is withdrawn. 2. To investigate whether noradrenaline-induced hypertension induces persistent, functionally important changes to the kidney, the acute pressure-natriuresis relationship was characterized in anaesthetized rats under controlled neural and hormonal conditions following chronic (14 days) intravenous infusion of noradrenaline (48 microg/kg per h) or vehicle (0.04 mg/mL ascorbic acid and 0.156 mg/mL NaH2PO4 2 H2O in 10 IU/mL heparinized saline). 3. Conscious mean arterial pressure was significantly elevated by infusion of noradrenaline at 48 microg/kg per h (+10 +/- 2 mmHg at Day 14; P < 0.01 vs vehicle group). The acute relationships between arterial pressure and renal blood flow, glomerular filtration rate, Na+ excretion and urine flow were not significantly different between the noradrenaline- and vehicle-infused rats immediately after termination of noradrenaline infusion. 4. In summary, chronic intravenous noradrenaline infusion did not cause persistent changes in renal function, indicating that, in contrast with many models of hypertension, this model does not induce underlying prohypertensive changes to the kidney.
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Affiliation(s)
- E I Boesen
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Sullivan JC, Semprun-Prieto L, Boesen EI, Pollock DM, Pollock JS. Sex and sex hormones influence the development of albuminuria and renal macrophage infiltration in spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2007; 293:R1573-9. [PMID: 17699561 DOI: 10.1152/ajpregu.00429.2007] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is a sex difference in hypertensive renal injury, with men experiencing greater severity and a more rapid progression of renal disease than women; however, the molecular mechanisms protecting against renal injury in women are unknown. The goal of this study was to determine whether sex hormones modulate blood pressure and the progression of albuminuria during the developmental phase of hypertension in male and female spontaneously hypertensive rats (SHR). Studies were also performed to examine how sex and sex hormones influence two major risk factors for albuminuria, overactivation of the renin-angiotensin system and oxidative stress. Blood pressure was measured by telemetry in gonad-intact and gonadectomized male and female SHR. Microalbumin excretion, measured over time, and macrophage infiltration were used to assess renal health. Male SHR had significantly higher blood pressures than female SHR, and gonadectomy decreased blood pressures in males with no effect in females. Male SHR displayed a gonad-sensitive increase in albuminuria over time, and female SHR had a gonad-sensitive suppression in macrophage infiltration. Female SHR had greater plasma ANG II levels and similar levels of renal cortical ANG II vs. levels shown in males but less AT(1)-receptor protein expression in the renal cortex. Female SHR also had a gonad-sensitive decrease in renal oxidative stress. Therefore, the renal protection afforded to female SHR is associated with lower blood pressure, decreased macrophage infiltration, and decreased levels of oxidative stress.
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Affiliation(s)
- Jennifer C Sullivan
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd, Augusta, GA 30912, USA.
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Abstract
Interleukin (IL)-6 has been implicated as a contributing factor in the pathogenesis of hypertension, although the mechanisms involved are unclear. Studies conducted in vitro suggest that IL-6 may have a direct effect on vascular tone and may modulate constrictor responses to agonists. Whether this effect can be observed in vivo is unknown. Therefore, mice were treated with either IL-6 (16 ng/h sc) or vehicle for 14 days, and the acute blood pressure and heart rate responses to endothelin (ET)-1, angiotensin II (ANG II), and phenylephrine (PE) were assessed under isoflurane anesthesia. Blood pressure responses to ET-1 were identical in vehicle- and IL-6-infused mice, both in the presence and the absence of ganglion blockade with chlorisondamine. The fall in heart rate during ET-1 responses was significantly attenuated in IL-6-infused mice with autonomic reflexes intact (vehicle vs. IL-6, P < 0.05 at 1 and 3 nmol/kg of ET-1), but this difference was not observed after ganglionic blockade. Both blood pressure and heart rate responses to ANG II were indistinguishable between IL-6- and vehicle-infused mice, as were responses to PE except for a significant increase in the blood pressure response and decrease in the heart rate response in IL-6-infused mice observed only at the highest dose of PE (300 microg/kg; P < 0.05). These findings show that, despite what might be predicted from studies conducted in vitro, chronic exposure to elevated plasma IL-6 concentrations in itself does not predispose the mouse to enhanced responsiveness to vasoconstrictors in vivo.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd., Augusta GA 30912, USA
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Abstract
First identified as a powerful vasoconstrictor, endothelin has an extremely diverse set of actions that influence homeostatic mechanisms throughout the body. Two receptor subtypes, ET(A) and ET(B), which usually have opposing actions, mediate the actions of endothelin. ET(A) receptors function to promote vasoconstriction, growth, and inflammation, whereas ET(B) receptors produce vasodilation, increases in sodium excretion, and inhibit growth and inflammation. Potent and selective receptor antagonists have been developed and have shown promising results in the treatment of cardiovascular diseases such as pulmonary arterial hypertension, acute and chronic heart failure, hypertension, renal failure, and atherosclerosis. However, results are often contradictory and complicated because of the tissue-specific vasoconstrictor actions of ET(B) receptors and the fact that endothelin is an autocrine and paracrine factor whose activity is difficult to measure in vivo. Considerable questions remain regarding whether ET(A)-selective or nonselective ET(A)/ET(B) receptor antagonists would be useful in a range of clinical settings.
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Affiliation(s)
- Markus P Schneider
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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Abstract
First identified as a powerful vasoconstrictor, endothelin has an extremely diverse set of actions that influence homeostatic mechanisms throughout the body. Two receptor subtypes, ET(A) and ET(B), which usually have opposing actions, mediate the actions of endothelin. ET(A) receptors function to promote vasoconstriction, growth, and inflammation, whereas ET(B) receptors produce vasodilation, increases in sodium excretion, and inhibit growth and inflammation. Potent and selective receptor antagonists have been developed and have shown promising results in the treatment of cardiovascular diseases such as pulmonary arterial hypertension, acute and chronic heart failure, hypertension, renal failure, and atherosclerosis. However, results are often contradictory and complicated because of the tissue-specific vasoconstrictor actions of ET(B) receptors and the fact that endothelin is an autocrine and paracrine factor whose activity is difficult to measure in vivo. Considerable questions remain regarding whether ET(A)-selective or nonselective ET(A)/ET(B) receptor antagonists would be useful in a range of clinical settings.
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Affiliation(s)
- Markus P Schneider
- Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912, USA
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Boesen EI, Pollock JS, Pollock DM. Chronic infusion of IL‐1β but not IL‐6 enhances renal and systemic endothelin production in mice. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a590-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia1459 Laney Walker BlvdAugustaGA30912
| | - Jennifer S Pollock
- Vascular Biology Center, Medical College of Georgia1459 Laney Walker BlvdAugustaGA30912
| | - David M Pollock
- Vascular Biology Center, Medical College of Georgia1459 Laney Walker BlvdAugustaGA30912
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Boesen EI, Anderson WP, Evans RG, Kett MM. Endogenous endothelins and the response to electrical renal nerve stimulation in anaesthetized rabbits. Auton Neurosci 2007; 132:8-15. [PMID: 16978927 DOI: 10.1016/j.autneu.2006.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Revised: 07/25/2006] [Accepted: 08/07/2006] [Indexed: 11/29/2022]
Abstract
The influence of endogenous endothelins on the neural control of renal function is poorly understood. We therefore studied the effects of endothelin blockade (combined ET(A) and ET(B) receptor antagonism using TAK-044) on the acute and prolonged effects of renal nerve stimulation in rabbits, measuring renal blood flow, glomerular filtration rate (GFR), urine flow and sodium excretion. Brief (3 min) stimulation over 0.5-8 Hz produced frequency-dependent reductions in total renal blood flow, cortical blood flow and, less markedly, medullary blood flow. TAK-044 did not significantly alter basal total renal blood flow or cortical blood flow, or their responses to nerve stimulation, but significantly increased basal medullary blood flow (P<0.01) and increased the slope of the stimulation frequency-medullary blood flow relationship (P<0.05). Prolonged (20 min) stimulation at 0, 0.5 and 2 Hz produced frequency-dependent reductions in total renal blood flow, GFR, urine flow and sodium excretion, but not medullary blood flow. Pretreatment with TAK-044 did not significantly alter these responses. Thus, endogenous endothelins do not appear to either augment or lessen the effects of renal nerve activation on total renal blood flow, cortical blood flow, GFR or sodium excretion. The apparent ability of TAK-044 to enhance medullary blood flow responses to renal nerve stimulation may reflect an action of endogenous endothelins to blunt neurally mediated vasoconstriction in the medullary circulation. Alternatively, it may simply be secondary to the effects of endogenous endothelins on basal medullary blood flow.
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Affiliation(s)
- Erika I Boesen
- Department of Physiology, Monash University, Melbourne, Victoria 3800, Australia.
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Abstract
Experiments conducted in vitro suggest that high osmolality stimulates endothelin production and release by renal tubular epithelial cells. Whether hyperosmotic solutions exert similar effects in vivo is unknown. Therefore, we tested the hypothesis that increasing renal medullary osmolality enhances urinary excretion of endothelin in anesthetized rats. Isosmotic NaCl (284 mosmol/kgH2O) was infused either intravenously (1.5 ml/h) or into the renal medullary interstitium (0.5 ml/h) during a 1-h equilibration period and 30-min baseline urine collection period, followed by either isosmotic or hyperosmotic NaCl (921 or 1,664 mosmol/kgH2O iv; 1,714 mosmol/kgH2O into renal medulla) for two further 30-min periods. Compared with isosmotic NaCl, infusion of hyperosmotic NaCl into the renal medulla significantly increased the endothelin excretion rate ( P < 0.05; from 0.30 ± 0.02 to 0.49 ± 0.03 fmol/min). Intravenous infusion of hyperosmotic NaCl also significantly increased endothelin excretion rate in a concentration-dependent manner (from 0.79 ± 0.07 to 1.77 ± 0.16 fmol/min and 0.59 ± 0.04 to 1.11 ± 0.08 fmol/min for 1,664 and 921 mosmol/kgH2O, respectively). To differentiate between effects of osmolality and NaCl, similar experiments were performed using mannitol solutions. Compared with isosmotic mannitol, medullary interstitial infusion of hyperosmotic mannitol (1,820 mosmol/kgH2O) significantly increased endothelin excretion rate ( P < 0.05; from 0.54 ± 0.03 to 0.94 ± 0.12 fmol/min). Thus exposing the renal medulla to hyperosmotic concentrations of either NaCl or mannitol stimulates endothelin release in vivo, consistent with medullary osmolality being an important regulator of renal endothelin synthesis.
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Affiliation(s)
- Erika I Boesen
- Vascular Biology Center, Medical College of Georgia, 1459 Laney Walker Blvd, Augusta, GA 30912, USA
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Boesen EI, Pollock DM. Control of renal endothelin release by medullary osmolarity. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a765-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology CenterMedical College of Georgia1459 Laney Walker BlvdAugustaGeorgia30912‐2500
| | - David M Pollock
- Vascular Biology CenterMedical College of Georgia1459 Laney Walker BlvdAugustaGeorgia30912‐2500
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Boesen EI, Pollock DM. Interleukin‐6 does not contribute to the increase in renal endothelin production stimulated by high salt intake. FASEB J 2006. [DOI: 10.1096/fasebj.20.4.a765-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erika I Boesen
- Vascular Biology CenterMedical College of Georgia1459 Laney Walker BlvdAugustaGeorgia30912‐2500
| | - David M Pollock
- Vascular Biology CenterMedical College of Georgia1459 Laney Walker BlvdAugustaGeorgia30912‐2500
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Abstract
OBJECTIVE To investigate the role of endothelin in noradrenaline-induced hypertension in rats. DESIGN The dose-response relationship of chronic noradrenaline infusion on arterial pressure was characterized to identify a dose that would produce sustained hypertension, and the effect of combined endothelin ETA and ETB receptor blockade (TAK-044) on the response to this dose was then examined. METHODS AND RESULTS Noradrenaline (or vehicle) was infused intravenously at 1 (subpressor acutely), 24 or 48 microg/kg per h (acute pressor response of 9 +/- 1 and 11 +/- 1 mmHg, respectively) for a 14-day infusion, and blood pressure was measured by radiotelemetry. Noradrenaline infusion at 1 microg/kg per h did not produce a 'slow pressor' rise in blood pressure. During noradrenaline infusions at 24 and 48 microg/kg per h, mean arterial pressure peaked initially on days 2-3 (+10 +/- 1 and 14 +/- 2 mmHg, respectively; P < 0.01), fell towards basal levels after day 3, and then began to rise again at days 5-6 only with 48 microg/kg per h, being 10 +/- 1 mmHg above control levels at days 13-14 (P < 0.05). TAK-044 treatment did not alter the magnitude of the initial (13 +/- 1 mmHg) or eventual (12 +/- 2 mmHg) rise in blood pressure achieved in response to 14 days' infusion of noradrenaline at 48 microg/kg per h, but abolished the transient fall. CONCLUSION Chronic noradrenaline infusion at acutely pressor doses leads either to a transient blood pressure elevation at a moderate dose, or to a triphasic but sustained hypertension at a higher dose, with a temporary escape from the hypertension apparently mediated by endothelin.
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Affiliation(s)
- Erika I Boesen
- Department of Physiology, Monash University, Victoria 3800, Australia
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Kett MM, Denton KM, Boesen EI, Anderson WP. Effects of early carvedilol treatment and withdrawal on the development of hypertension and renal vascular narrowing. Am J Hypertens 2004; 17:161-6. [PMID: 14751659 DOI: 10.1016/j.amjhyper.2003.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The aims of this study were to examine whether combined blockade of alpha(1) and beta-adrenoceptors with carvedilol postweaning affected the development of hypertension and renal vascular narrowing in spontaneously hypertensive rats (SHR), and whether these effects on pressure and renal vascular changes persisted after treatment withdrawal. METHODS From 4 to 12 weeks of age male SHR were administered carvedilol in rat chow at 1.2 mg/g chow (low-dose) or 2.4 mg/g chow (high-dose), or were given normal chow. At 12 weeks of age, rats from each group either underwent experimentation or had treatment withdrawn and were studied at 20 weeks. On the experimental day, conscious mean arterial pressure (MAP) was measured and, as a functional test of renal vessel lumen characteristics, pressure-flow and pressure-glomerular filtration rate (pressure-GFR) relationships were determined in the maximally dilated kidney. RESULTS At 12 weeks of age, SHR on low and high-dose carvedilol had significantly lower MAP than that of untreated SHR (137 +/- 3, 134 +/- 1, 152 +/- 2 mm Hg, respectively; P <.001). The SHR treated with high-dose (but not low-dose) carvedilol demonstrated a steeper renal pressure-flow relationship (P <.001), and a leftward shifted (P <.01) and steeper (P <.001) pressure-GFR relationship compared with control SHR. Eight weeks after carvedilol withdrawal, there were no significant differences in MAP, pressure-flow, or pressure-GFR relationships between groups. CONCLUSIONS These results suggest that postweaning alpha(1) and beta-adrenoceptor blockade with high-dose carvedilol attenuated the development of hypertension and led to a preferential reduction in preglomerular resistance (increased lumen dimensions) independent of the effects on MAP. However, treatment of SHR from 4 to 12 weeks of age with high-dose carvedilol did not lead to persistent, long-term effects on arterial pressure or renal vascular narrowing after treatment withdrawal.
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Affiliation(s)
- Michelle M Kett
- Department of Physiology, PO Box 13F, Monash University, Victoria 3800, Australia.
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