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Bush KT, Singh P, Nigam SK. Gut-derived uremic toxin handling in vivo requires OAT-mediated tubular secretion in chronic kidney disease. JCI Insight 2020; 5:133817. [PMID: 32271169 DOI: 10.1172/jci.insight.133817] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 02/28/2020] [Indexed: 12/12/2022] Open
Abstract
The role of the renal organic anion transporters OAT1 (also known as SLC22A6, originally identified as NKT) and OAT3 (also known as SLC22A8) in chronic kidney disease (CKD) remains poorly understood. This is particularly so from the viewpoint of residual proximal tubular secretion, a key adaptive mechanism to deal with protein-bound uremic toxins in CKD. Using the subtotal nephrectomy (STN) model, plasma metabolites accumulating in STN rats treated with and without the OAT inhibitor, probenecid, were identified. Comparisons with metabolomics data from Oat1-KO and Oat3-KO mice support the centrality of the OATs in residual tubular secretion of uremic solutes, such as indoxyl sulfate, kynurenate, and anthranilate. Overlapping our data with those of published metabolomics data regarding gut microbiome-derived uremic solutes - which can have dual roles in signaling and toxicity - indicates that OATs play a critical role in determining their plasma levels in CKD. Thus, the OATs, along with other SLC and ABC drug transporters, are critical to the movement of uremic solutes across tissues and into various body fluids, consistent with the remote sensing and signaling theory. The data support a role for OATs in modulating remote interorganismal and interorgan communication (gut microbiota-blood-liver-kidney-urine). The results also have implications for understanding drug-metabolite interactions involving uremic toxins.
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Affiliation(s)
- Kevin T Bush
- Department of Pediatrics, University of California, San Diego, La Jolla, California, USA
| | - Prabhleen Singh
- Division of Nephrology-Hypertension, University of California, San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California, USA.,Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Sanjay K Nigam
- Department of Pediatrics, University of California, San Diego, La Jolla, California, USA.,Department of Medicine, University of California, San Diego, La Jolla, California, USA
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2
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Thomson SC. Nitric oxide mediates anomalous tubuloglomerular feedback in rats fed high-NaCl diet after subtotal nephrectomy. Am J Physiol Renal Physiol 2018; 316:F223-F230. [PMID: 30379101 DOI: 10.1152/ajprenal.00066.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tubuloglomerular feedback (TGF) responses become anomalous in rats fed high-NaCl diet after subtotal nephrectomy (STN), such that stimulating TGF causes single nephron GFR (SNGFR) to increase rather than decrease. Micropuncture experiments were performed to determine whether this anomaly results from heightened nitric oxide response to distal delivery, which is a known mechanism for resetting TGF, or from connecting tubule TGF (cTGF), which is a novel amiloride-inhibitable system for offsetting TGF responses. Micropuncture was done in Wistar Froemter rats fed high-NaCl diet (HS) for 8-10 days after STN or sham nephrectomy. TGF was manipulated by orthograde microperfusion of Henle's loop with artificial tubular fluid with or without NOS inhibitor, LNMMA, or the cell-impermeant amiloride analog, benzamil. SNGFR was measured by inulin clearance in tubular fluid collections from the late proximal tubule. TGF responses were quantified as the increase in SNGFR that occurred when the perfusion rate was reduced from 50 to 8 nl/min in STN or 40 to 8 nl/min in sham animals. The baseline TGF response was anomalous in STN HS (-4 ± 3 vs 14 ± 3 nl/min, P < 0.001). TGF response was normalized by perfusing STN nephron with LNMMA (14 ± 3 nl/min, P < 0.005 for ANOVA cross term) but not with benzamil (-3 ± 4 nl/min, P = 0.4 for ANOVA cross term). Anomalous TGF occurs in STN HS due to heightened effect of tubular flow on nitric oxide signaling, which increases to the point of overriding the normal TGF response. There is no role for cTGF in this phenomenon.
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Affiliation(s)
- Scott C Thomson
- Division of Nephrology-Hypertension, VA San Diego Healthcare System and University of California, San Diego School of Medicine , La Jolla, California
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Liu ZZ, Bullen A, Li Y, Singh P. Renal Oxygenation in the Pathophysiology of Chronic Kidney Disease. Front Physiol 2017; 8:385. [PMID: 28701959 PMCID: PMC5487476 DOI: 10.3389/fphys.2017.00385] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/23/2017] [Indexed: 12/19/2022] Open
Abstract
Chronic kidney disease (CKD) is a significant health problem associated with high morbidity and mortality. Despite significant research into various pathways involved in the pathophysiology of CKD, the therapeutic options are limited in diabetes and hypertension induced CKD to blood pressure control, hyperglycemia management (in diabetic nephropathy) and reduction of proteinuria, mainly with renin-angiotensin blockade therapy. Recently, renal oxygenation in pathophysiology of CKD progression has received a lot of interest. Several advances have been made in our understanding of the determinants and regulators of renal oxygenation in normal and diseased kidneys. The goal of this review is to discuss the alterations in renal oxygenation (delivery, consumption and tissue oxygen tension) in pre-clinical and clinical studies in diabetic and hypertensive CKD along with the underlying mechanisms and potential therapeutic options.
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Affiliation(s)
- Zhi Zhao Liu
- Division of Nephrology-Hypertension, University of California San Diego School of Medicine, VA San Diego Healthcare SystemSan Diego, CA, United States
| | - Alexander Bullen
- Division of Nephrology-Hypertension, University of California San Diego School of Medicine, VA San Diego Healthcare SystemSan Diego, CA, United States
| | - Ying Li
- Division of Nephrology-Hypertension, University of California San Diego School of Medicine, VA San Diego Healthcare SystemSan Diego, CA, United States
| | - Prabhleen Singh
- Division of Nephrology-Hypertension, University of California San Diego School of Medicine, VA San Diego Healthcare SystemSan Diego, CA, United States
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Thomas JL, Pham H, Li Y, Hall E, Perkins GA, Ali SS, Patel HH, Singh P. Hypoxia-inducible factor-1α activation improves renal oxygenation and mitochondrial function in early chronic kidney disease. Am J Physiol Renal Physiol 2017; 313:F282-F290. [PMID: 28331062 DOI: 10.1152/ajprenal.00579.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 03/17/2017] [Accepted: 03/20/2017] [Indexed: 02/07/2023] Open
Abstract
The pathophysiology of chronic kidney disease (CKD) is driven by alterations in surviving nephrons to sustain renal function with ongoing nephron loss. Oxygen supply-demand mismatch, due to hemodynamic adaptations, with resultant hypoxia, plays an important role in the pathophysiology in early CKD. We sought to investigate the underlying mechanisms of this mismatch. We utilized the subtotal nephrectomy (STN) model of CKD to investigate the alterations in renal oxygenation linked to sodium (Na) transport and mitochondrial function in the surviving nephrons. Oxygen delivery was significantly reduced in STN kidneys because of lower renal blood flow. Fractional oxygen extraction was significantly higher in STN. Tubular Na reabsorption was significantly lower per mole of oxygen consumed in STN. We hypothesized that decreased mitochondrial bioenergetic capacity may account for this and uncovered significant mitochondrial dysfunction in the early STN kidney: higher oxidative metabolism without an attendant increase in ATP levels, elevated superoxide levels, and alterations in mitochondrial morphology. We further investigated the effect of activation of hypoxia-inducible factor-1α (HIF-1α), a master regulator of cellular hypoxia response. We observed significant improvement in renal blood flow, glomerular filtration rate, and tubular Na reabsorption per mole of oxygen consumed with HIF-1α activation. Importantly, HIF-1α activation significantly lowered mitochondrial oxygen consumption and superoxide production and increased mitochondrial volume density. In conclusion, we report significant impairment of renal oxygenation and mitochondrial function at the early stages of CKD and demonstrate the beneficial role of HIF-1α activation on renal function and metabolism.
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Affiliation(s)
- Joanna L Thomas
- Department of Biomedical Engineering, School of Engineering, Mercer University, Macon, Georgia
| | - Hai Pham
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, and VA San Diego Healthcare System, San Diego, California
| | - Ying Li
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, and VA San Diego Healthcare System, San Diego, California
| | - Elanore Hall
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, and VA San Diego Healthcare System, San Diego, California
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, La Jolla, California
| | - Sameh S Ali
- Center for Aging and Associated Diseases, Helmy Institute of Medical Science, Zewail City of Science and Technology, Giza, Egypt; and.,Department of Anesthesiology, University of California, San Diego, California and VA San Diego Healthcare System, San Diego, California
| | - Hemal H Patel
- Department of Anesthesiology, University of California, San Diego, California and VA San Diego Healthcare System, San Diego, California
| | - Prabhleen Singh
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, and VA San Diego Healthcare System, San Diego, California;
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Takashima S, Fujita H, Fujishima H, Shimizu T, Sato T, Morii T, Tsukiyama K, Narita T, Takahashi T, Drucker DJ, Seino Y, Yamada Y. Stromal cell-derived factor-1 is upregulated by dipeptidyl peptidase-4 inhibition and has protective roles in progressive diabetic nephropathy. Kidney Int 2016; 90:783-96. [PMID: 27475229 DOI: 10.1016/j.kint.2016.06.012] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 05/31/2016] [Accepted: 06/02/2016] [Indexed: 12/20/2022]
Abstract
The role of stromal cell-derived factor-1 (SDF-1) in the pathogenesis of diabetic nephropathy and its modification by dipeptidyl peptidase-4 (DPP-4) inhibition are uncertain. Therefore, we studied this independent of glucagon-like peptide-1 receptor (GLP-1R) signaling using two Akita diabetic mouse models, the diabetic-resistant C57BL/6-Akita and diabetic-prone KK/Ta-Akita. Increased SDF-1 expression was found in glomerular podocytes and distal nephrons in the diabetic-prone mice, but not in kidneys from diabetic-resistant mice. The DPP-4 inhibitor linagliptin, but not the GLP-1R agonist liraglutide, further augmented renal SDF-1 expression in both Glp1r(+/+) and Glp1r(-/-) diabetic-prone mice. Along with upregulation of renal SDF-1 expression, the progression of albuminuria, glomerulosclerosis, periglomerular fibrosis, podocyte loss, and renal oxidative stress was suppressed in linagliptin-treated Glp1r(+/+) diabetic-prone mice. Linagliptin treatment increased urinary sodium excretion and attenuated the increase in glomerular filtration rate which reflects glomerular hypertension and hyperfiltration. In contrast, selective SDF-1 receptor blockade with AMD3100 reduced urinary sodium excretion and aggravated glomerular hypertension in the Glp1r(+/+) diabetic-prone mice. Thus, DPP-4 inhibition, independent of GLP-1R signaling, contributes to protection of the diabetic kidney through SDF-1-dependent antioxidative and antifibrotic effects and amelioration of adverse renal hemodynamics.
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Affiliation(s)
- Satoru Takashima
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Hiroki Fujita
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan.
| | - Hiromi Fujishima
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Tatsunori Shimizu
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Takehiro Sato
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Tsukasa Morii
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Katsushi Tsukiyama
- Division of Metabolism and Clinical Nutrition Science, Akita University Graduate School of Medicine, Akita, Japan
| | - Takuma Narita
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
| | - Takamune Takahashi
- Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Daniel J Drucker
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada; The Lunenfeld-Tanenbaum Research Institute, Mt. Sinai Hospital, Toronto, Ontario, Canada
| | - Yutaka Seino
- Kansai Electric Power Medical Research Institute, Osaka, Japan
| | - Yuichiro Yamada
- Division of Endocrinology, Metabolism and Geriatric Medicine, Akita University Graduate School of Medicine, Akita, Japan
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Layton AT. Recent advances in renal hemodynamics: insights from bench experiments and computer simulations. Am J Physiol Renal Physiol 2015; 308:F951-5. [PMID: 25715984 DOI: 10.1152/ajprenal.00008.2015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/23/2015] [Indexed: 01/08/2023] Open
Abstract
It has been long known that the kidney plays an essential role in the control of body fluids and blood pressure and that impairment of renal function may lead to the development of diseases such as hypertension (Guyton AC, Coleman TG, Granger Annu Rev Physiol 34: 13-46, 1972). In this review, we highlight recent advances in our understanding of renal hemodynamics, obtained from experimental and theoretical studies. Some of these studies were published in response to a recent Call for Papers of this journal: Renal Hemodynamics: Integrating with the Nephron and Beyond.
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Affiliation(s)
- Anita T Layton
- Department of Mathematics, Duke University, Durham, North Carolina
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Wu H, Liang Y, Zheng Y, Bai Q, Zhuang Z, A L, Zheng D, Wang Y. Up-regulation of intrarenal renin-agiotensin system contributes to renal damage in high-salt induced hypertension rats. Kidney Blood Press Res 2014; 39:526-35. [PMID: 25531334 DOI: 10.1159/000368463] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS To investigate the change of intrarenal renin-agiotensin system (RAS) and its role in high-salt induced hypertension. METHODS Wistar rats were divided into normal-salt (NS), high-salt diet (HS) and high-salt diet with Losartan group (HS+L), for 6 weeks. Systolic blood pressure (SBP) was monitored. Blood and urine samples were collected every 2 weeks. Angiotensinogen (AGT) was measured by ELISA. AGT mRNA and protein were measured by real-time PCR and immunohistochemistry. Renin activity and angiotensin II (Ang II) were measured by radioimmunoassay. RESULTS HS versus NS group, SBP increased from 2(nd) week (P<0.05), urinary protein increased at 6(th) week (P<0.05). Although plasma renin, AGT and Ang II had no significant changes (P>0.05), renal cortex renin, AGT, and Ang II increased significantly in HS (P<0.05). In HS+L, Losartan failed to reduce SBP (P>0.05) but abolished the increase of proteinuria (P<0.01), renal cortex renin, AGT, Ang II and urinary AGT reduced (P<0.05) while plasma renin, AGT and Ang II enhanced (P<0.05) when compared with HS. Urinary AGT was positively correlated with renal AGT (r=0.592, P <0.01) and Ang II (r=0.726, P <0.01). CONCLUSION Inappropriate response of the renal RAS to a high salt diet may contribute to hypertension and renal damage, and urinary AGT could reflect intrarenal RAS activity.
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Affiliation(s)
- Haiyan Wu
- Department of Nephrology, Peking University Third Hospital, Beijing 100191, China
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Blantz RC, Singh P. Glomerular and tubular function in the diabetic kidney. Adv Chronic Kidney Dis 2014; 21:297-303. [PMID: 24780458 DOI: 10.1053/j.ackd.2014.03.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 03/09/2014] [Accepted: 03/10/2014] [Indexed: 01/11/2023]
Abstract
Diabetes mellitus with its attendant complications is a significant cause of morbidity and mortality with diabetic nephropathy being the leading cause of end stage renal disease in the Western world. Characteristic structural and functional changes in the kidney early in the course of diabetes have been shown to have enduring effects on the progression of disease. A better understanding of the mechanisms underlying these changes is imperative to the development of new therapeutic strategies. Renal hypertrophy and hyperfiltration along with proximal tubular hyperreabsorption are among the distinctive features of early diabetic nephropathy. Additionally, there are particular alterations in the sensitivity of the glomerular and tubular function to dietary salt intake in early diabetes. Herein, we focus on these early physiologic changes and discuss some of the primary and secondary mechanisms discovered in recent years which lead to these alterations in kidney function.
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