1
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Bryniarski MA, Sandoval RM, Ruszaj DM, Fraser-McArthur J, Yee BM, Yacoub R, Chaves LD, Campos-Bilderback SB, Molitoris BA, Morris ME. Defining the Intravital Renal Disposition of Fluorescence-Quenched Exenatide. Mol Pharm 2023; 20:987-996. [PMID: 36626167 PMCID: PMC9907348 DOI: 10.1021/acs.molpharmaceut.2c00671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 12/13/2022] [Accepted: 12/14/2022] [Indexed: 01/11/2023]
Abstract
Despite the understanding that renal clearance is pivotal for driving the pharmacokinetics of numerous therapeutic proteins and peptides, the specific processes that occur following glomerular filtration remain poorly defined. For instance, sites of catabolism within the proximal tubule can occur at the brush border, within lysosomes following endocytosis, or even within the tubule lumen itself. The objective of the current study was to address these limitations and develop methodology to study the kidney disposition of a model therapeutic protein. Exenatide is a peptide used to treat type 2 diabetes mellitus. Glomerular filtration and ensuing renal catabolism have been shown to be its principal clearance pathway. Here, we designed and validated a Förster resonance energy transfer-quenched exenatide derivative to provide critical information on the renal handling of exenatide. A combination of in vitro techniques was used to confirm substantial fluorescence quenching of intact peptide that was released upon proteolytic cleavage. This evaluation was then followed by an assessment of the in vivo disposition of quenched exenatide directly within kidneys of living rats via intravital two-photon microscopy. Live imaging demonstrated rapid glomerular filtration and identified exenatide metabolism occurred within the subapical regions of the proximal tubule epithelia, with subsequent intracellular trafficking of cleaved fragments. These results provide a novel examination into the real-time, intravital disposition of a protein therapeutic within the kidney and offer a platform to build upon for future work.
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Affiliation(s)
- Mark A. Bryniarski
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, University at Buffalo, 304 Pharmacy Building, Buffalo, New York 14215, United States
| | - Ruben M. Sandoval
- Department
of Medicine, Indiana University, Indianapolis, Indiana 46202, United States
| | - Donna M. Ruszaj
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, University at Buffalo, 304 Pharmacy Building, Buffalo, New York 14215, United States
| | - John Fraser-McArthur
- Department
of Pharmacy, University of Rochester Medical
Center, Rochester, New York 14642, United States
| | - Benjamin M. Yee
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, University at Buffalo, 304 Pharmacy Building, Buffalo, New York 14215, United States
| | - Rabi Yacoub
- Department
of Internal Medicine, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203, United States
| | - Lee D. Chaves
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, University at Buffalo, 304 Pharmacy Building, Buffalo, New York 14215, United States
- Department
of Neurosurgery, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14203, United States
| | | | - Bruce A. Molitoris
- Department
of Medicine, Indiana University, Indianapolis, Indiana 46202, United States
| | - Marilyn E. Morris
- Department
of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical
Sciences, University at Buffalo, 304 Pharmacy Building, Buffalo, New York 14215, United States
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2
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Wagner MC, Sandoval RM, Campos-Bilderback SB, Molitoris BA. Using 2-Photon Microscopy to Quantify the Effects of Chronic Unilateral Ureteral Obstruction on Glomerular Processes. J Vis Exp 2022. [DOI: 10.3791/63329] [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] [Indexed: 10/31/2022] Open
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3
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Yadav SPS, Sandoval RM, Zhao J, Huang Y, Wang E, Kumar S, Campos-Bilderback SB, Rhodes G, Mechref Y, Molitoris BA, Wagner MC. Mechanism of how carbamylation reduces albumin binding to FcRn contributing to increased vascular clearance. Am J Physiol Renal Physiol 2021; 320:F114-F129. [PMID: 33283642 PMCID: PMC7847050 DOI: 10.1152/ajprenal.00428.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/12/2020] [Accepted: 11/27/2020] [Indexed: 12/13/2022] Open
Abstract
Chronic kidney disease results in high serum urea concentrations leading to excessive protein carbamylation, primarily albumin. This is associated with increased cardiovascular disease and mortality. Multiple methods were used to address whether carbamylation alters albumin metabolism. Intravital two-photon imaging of the Munich Wistar Frömter (MWF) rat kidney and liver allowed us to characterize filtration and proximal tubule uptake and liver uptake. Microscale thermophoresis enabled quantification of cubilin (CUB7,8 domain) and FcRn binding. Finally, multiple biophysical methods including dynamic light scattering, small-angle X-ray scattering, LC-MS/MS and in silico analyses were used to identify the critical structural alterations and amino acid modifications of rat albumin. Carbamylation of albumin reduced binding to CUB7,8 and FcRn in a dose-dependent fashion. Carbamylation markedly increased vascular clearance of carbamylated rat serum albumin (cRSA) and altered distribution of cRSA in both the kidney and liver at 16 h post intravenous injection. By evaluating the time course of carbamylation and associated charge, size, shape, and binding parameters in combination with in silico analysis and mass spectrometry, the critical binding interaction impacting carbamylated albumin's reduced FcRn binding was identified as K524. Carbamylation of RSA had no effect on glomerular filtration or proximal tubule uptake. These data indicate urea-mediated time-dependent carbamylation of albumin lysine K524 resulted in reduced binding to CUB7,8 and FcRn that contribute to altered albumin transport, leading to increased vascular clearance and increased liver and endothelial tissue accumulation.
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MESH Headings
- Animals
- Chromatography, Liquid
- Disease Models, Animal
- Glomerular Filtration Rate
- Histocompatibility Antigens Class I/metabolism
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/physiopathology
- Liver/metabolism
- Lysine
- Male
- Microscopy, Fluorescence, Multiphoton
- Protein Binding
- Protein Carbamylation
- Rats, Inbred Strains
- Rats, Sprague-Dawley
- Receptors, Cell Surface/metabolism
- Receptors, Fc/metabolism
- Renal Insufficiency, Chronic/metabolism
- Renal Insufficiency, Chronic/pathology
- Renal Insufficiency, Chronic/physiopathology
- Scattering, Small Angle
- Serum Albumin/metabolism
- Tandem Mass Spectrometry
- Time Factors
- X-Ray Diffraction
- Rats
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Affiliation(s)
- Shiv Pratap S Yadav
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ruben M Sandoval
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jingfu Zhao
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas
| | - Yifan Huang
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas
| | - Exing Wang
- Department of Cell Systems and Anatomy, UT Health San Antonio, San Antonio, Texas
| | - Sudhanshu Kumar
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Silvia B Campos-Bilderback
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - George Rhodes
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Yehia Mechref
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas
| | - Bruce A Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Mark C Wagner
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
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4
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Endres BT, Sandoval RM, Rhodes GJ, Campos-Bilderback SB, Kamocka MM, McDermott-Roe C, Staruschenko A, Molitoris BA, Geurts AM, Palygin O. Intravital imaging of the kidney in a rat model of salt-sensitive hypertension. Am J Physiol Renal Physiol 2017; 313:F163-F173. [PMID: 28404591 DOI: 10.1152/ajprenal.00466.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 03/30/2017] [Accepted: 04/11/2017] [Indexed: 01/07/2023] Open
Abstract
Hypertension is one of the most prevalent diseases worldwide and a major risk factor for renal failure and cardiovascular disease. The role of albuminuria, a common feature of hypertension and robust predictor of cardiorenal disorders, remains incompletely understood. The goal of this study was to investigate the mechanisms leading to albuminuria in the kidney of a rat model of hypertension, the Dahl salt-sensitive (SS) rat. To determine the relative contributions of the glomerulus and proximal tubule (PT) to albuminuria, we applied intravital two-photon-based imaging to investigate the complex renal physiological changes that occur during salt-induced hypertension. Following a high-salt diet, SS rats exhibited elevated blood pressure, increased glomerular sieving of albumin (GSCalb = 0.0686), relative permeability to albumin (+Δ16%), and impaired volume hemodynamics (-Δ14%). Serum albumin but not serum globulins or creatinine concentration was decreased (-0.54 g/dl), which was concomitant with increased filtration of albumin (3.7 vs. 0.8 g/day normal diet). Pathologically, hypertensive animals had significant tubular damage, as indicated by increased prevalence of granular casts, expansion and necrosis of PT epithelial cells (+Δ2.20 score/image), progressive augmentation of red blood cell velocity (+Δ269 µm/s) and micro vessel diameter (+Δ4.3 µm), and increased vascular injury (+Δ0.61 leakage/image). Therefore, development of salt-induced hypertension can be triggered by fast and progressive pathogenic remodeling of PT epithelia, which can be associated with changes in albumin handling. Collectively, these results indicate that both the glomerulus and the PT contribute to albuminuria, and dual treatment of glomerular filtration and albumin reabsorption may represent an effective treatment of salt-sensitive hypertension.
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Affiliation(s)
- Bradley T Endres
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin.,Department of Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Ruben M Sandoval
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | - George J Rhodes
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Malgorzata M Kamocka
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin; and
| | - Bruce A Molitoris
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | - Aron M Geurts
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; .,Department of Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin.,Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin; and
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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5
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Collett JA, Corridon PR, Mehrotra P, Kolb AL, Rhodes GJ, Miller CA, Molitoris BA, Pennington JG, Sandoval RM, Atkinson SJ, Campos-Bilderback SB, Basile DP, Bacallao RL. Hydrodynamic Isotonic Fluid Delivery Ameliorates Moderate-to-Severe Ischemia-Reperfusion Injury in Rat Kidneys. J Am Soc Nephrol 2017; 28:2081-2092. [PMID: 28122967 DOI: 10.1681/asn.2016040404] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 12/17/2016] [Indexed: 01/03/2023] Open
Abstract
Highly aerobic organs like the kidney are innately susceptible to ischemia-reperfusion (I/R) injury, which can originate from sources including myocardial infarction, renal trauma, and transplant. Therapy is mainly supportive and depends on the cause(s) of damage. In the absence of hypervolemia, intravenous fluid delivery is frequently the first course of treatment but does not reverse established AKI. Evidence suggests that disrupting leukocyte adhesion may prevent the impairment of renal microvascular perfusion and the heightened inflammatory response that exacerbate ischemic renal injury. We investigated the therapeutic potential of hydrodynamic isotonic fluid delivery (HIFD) to the left renal vein 24 hours after inducing moderate-to-severe unilateral IRI in rats. HIFD significantly increased hydrostatic pressure within the renal vein. When conducted after established AKI, 24 hours after I/R injury, HIFD produced substantial and statistically significant decreases in serum creatinine levels compared with levels in animals given an equivalent volume of saline via peripheral infusion (P<0.05). Intravital confocal microscopy performed immediately after HIFD showed improved microvascular perfusion. Notably, HIFD also resulted in immediate enhancement of parenchymal labeling with the fluorescent dye Hoechst 33342. HIFD also associated with a significant reduction in the accumulation of renal leukocytes, including proinflammatory T cells. Additionally, HIFD significantly reduced peritubular capillary erythrocyte congestion and improved histologic scores of tubular injury 4 days after IRI. Taken together, these results indicate that HIFD performed after establishment of AKI rapidly restores microvascular perfusion and small molecule accessibility, with improvement in overall renal function.
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Affiliation(s)
| | - Peter R Corridon
- Department of Craniofacial Biology, University of Colorado Denver, Anschutz Campus, Aurora, Colorado
| | | | - Alexander L Kolb
- Department of Biology, Indiana University-Purdue University, Indianapolis, Indiana; and
| | | | | | - Bruce A Molitoris
- Division of Nephrology, Department of Medicine.,Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | | | | | - Simon J Atkinson
- Department of Biology, Indiana University-Purdue University, Indianapolis, Indiana; and
| | | | - David P Basile
- Department of Cellular and Integrative Physiology.,Division of Nephrology, Department of Medicine
| | - Robert L Bacallao
- Division of Nephrology, Department of Medicine, .,Department of Medicine, Division of Nephrology, Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana
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6
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McCurley A, Alimperti S, Campos-Bilderback SB, Sandoval RM, Calvino JE, Reynolds TL, Quigley C, Mugford JW, Polacheck WJ, Gomez IG, Dovey J, Marsh G, Huang A, Qian F, Weinreb PH, Dolinski BM, Moore S, Duffield JS, Chen CS, Molitoris BA, Violette SM, Crackower MA. Inhibition of αv β5 Integrin Attenuates Vascular Permeability and Protects against Renal Ischemia-Reperfusion Injury. J Am Soc Nephrol 2017; 28:1741-1752. [PMID: 28062569 DOI: 10.1681/asn.2016020200] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 11/22/2016] [Indexed: 01/28/2023] Open
Abstract
Ischemia-reperfusion injury (IRI) is a leading cause of AKI. This common clinical complication lacks effective therapies and can lead to the development of CKD. The αvβ5 integrin may have an important role in acute injury, including septic shock and acute lung injury. To examine its function in AKI, we utilized a specific function-blocking antibody to inhibit αvβ5 in a rat model of renal IRI. Pretreatment with this anti-αvβ5 antibody significantly reduced serum creatinine levels, diminished renal damage detected by histopathologic evaluation, and decreased levels of injury biomarkers. Notably, therapeutic treatment with the αvβ5 antibody 8 hours after IRI also provided protection from injury. Global gene expression profiling of post-ischemic kidneys showed that αvβ5 inhibition affected established injury markers and induced pathway alterations previously shown to be protective. Intravital imaging of post-ischemic kidneys revealed reduced vascular leak with αvβ5 antibody treatment. Immunostaining for αvβ5 in the kidney detected evident expression in perivascular cells, with negligible expression in the endothelium. Studies in a three-dimensional microfluidics system identified a pericyte-dependent role for αvβ5 in modulating vascular leak. Additional studies showed αvβ5 functions in the adhesion and migration of kidney pericytes in vitro Initial studies monitoring renal blood flow after IRI did not find significant effects with αvβ5 inhibition; however, future studies should explore the contribution of vasomotor effects. These studies identify a role for αvβ5 in modulating injury-induced renal vascular leak, possibly through effects on pericyte adhesion and migration, and reveal αvβ5 inhibition as a promising therapeutic strategy for AKI.
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Affiliation(s)
| | - Stella Alimperti
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts.,The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Silvia B Campos-Bilderback
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana; and
| | - Ruben M Sandoval
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana; and
| | | | | | | | | | - William J Polacheck
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts.,The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | | | | | | | | | - Fang Qian
- Biogen Inc., Cambridge, Massachusetts
| | | | | | | | | | - Christopher S Chen
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts.,The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Bruce A Molitoris
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana; and.,Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
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7
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Wagner MC, Myslinski J, Pratap S, Flores B, Rhodes G, Campos-Bilderback SB, Sandoval RM, Kumar S, Patel M, Ashish, Molitoris BA. Mechanism of increased clearance of glycated albumin by proximal tubule cells. Am J Physiol Renal Physiol 2016; 310:F1089-102. [PMID: 26887834 PMCID: PMC4889321 DOI: 10.1152/ajprenal.00605.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/10/2016] [Indexed: 11/22/2022] Open
Abstract
Serum albumin is the most abundant plasma protein and has a long half-life due to neonatal Fc receptor (FcRn)-mediated transcytosis by many cell types, including proximal tubule cells of the kidney. Albumin also interacts with, and is modified by, many small and large molecules. Therefore, the focus of the present study was to address the impact of specific known biological albumin modifications on albumin-FcRn binding and cellular handling. Binding at pH 6.0 and 7.4 was performed since FcRn binds albumin strongly at acidic pH and releases it after transcytosis at physiological pH. Equilibrium dissociation constants were measured using microscale thermophoresis. Since studies have shown that glycated albumin is excreted in the urine at a higher rate than unmodified albumin, we studied glucose and methylgloxal modified albumins (21 days). All had reduced affinity to FcRn at pH 6.0, suggesting these albumins would not be returned to the circulation via the transcytotic pathway. To address why modified albumin has reduced affinity, we analyzed the structure of the modified albumins using small-angle X-ray scattering. This analysis showed significant structural changes occurring to albumin with glycation, particularly in the FcRn-binding region, which could explain the reduced affinity to FcRn. These results offer an explanation for enhanced proximal tubule-mediated sorting and clearance of abnormal albumins.
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Affiliation(s)
- Mark C Wagner
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Jered Myslinski
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Shiv Pratap
- The Council of Scientific and Industrial Research Institute of Microbial Technology, Chandigarh, India
| | - Brittany Flores
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - George Rhodes
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Silvia B Campos-Bilderback
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Ruben M Sandoval
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Sudhanshu Kumar
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Monika Patel
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Ashish
- The Council of Scientific and Industrial Research Institute of Microbial Technology, Chandigarh, India
| | - Bruce A Molitoris
- Nephrology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana; Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana; and
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8
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Wagner MC, Campos-Bilderback SB, Chowdhury M, Flores B, Lai X, Myslinski J, Pandit S, Sandoval RM, Wean SE, Wei Y, Satlin LM, Wiggins RC, Witzmann FA, Molitoris BA. Proximal Tubules Have the Capacity to Regulate Uptake of Albumin. J Am Soc Nephrol 2015; 27:482-94. [PMID: 26054544 DOI: 10.1681/asn.2014111107] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 05/04/2015] [Indexed: 12/26/2022] Open
Abstract
Evidence from multiple studies supports the concept that both glomerular filtration and proximal tubule (PT) reclamation affect urinary albumin excretion rate. To better understand these roles of glomerular filtration and PT uptake, we investigated these processes in two distinct animal models. In a rat model of acute exogenous albumin overload, we quantified glomerular sieving coefficients (GSC) and PT uptake of Texas Red-labeled rat serum albumin using two-photon intravital microscopy. No change in GSC was observed, but a significant decrease in PT albumin uptake was quantified. In a second model, loss of endogenous albumin was induced in rats by podocyte-specific transgenic expression of diphtheria toxin receptor. In these albumin-deficient rats, exposure to diphtheria toxin induced an increase in albumin GSC and albumin filtration, resulting in increased exposure of the PTs to endogenous albumin. In this case, PT albumin reabsorption was markedly increased. Analysis of known albumin receptors and assessment of cortical protein expression in the albumin overload model, conducted to identify potential proteins and pathways affected by acute protein overload, revealed changes in the expression levels of calreticulin, disabled homolog 2, NRF2, angiopoietin-2, and proteins involved in ATP synthesis. Taken together, these results suggest that a regulated PT cell albumin uptake system can respond rapidly to different physiologic conditions to minimize alterations in serum albumin level.
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Affiliation(s)
- Mark C Wagner
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Silvia B Campos-Bilderback
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Mahboob Chowdhury
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Brittany Flores
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Xianyin Lai
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Jered Myslinski
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Sweekar Pandit
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Ruben M Sandoval
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Sarah E Wean
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
| | - Yuan Wei
- Department of Pediatrics, The Icahn School of Medicine at Mount Sinai, New York
| | - Lisa M Satlin
- Department of Pediatrics, The Icahn School of Medicine at Mount Sinai, New York
| | - Roger C Wiggins
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Frank A Witzmann
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Bruce A Molitoris
- Indiana University School of Medicine, The Roudebush Veterans Affair Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana; Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
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9
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Ferrell N, Sandoval RM, Bian A, Campos-Bilderback SB, Molitoris BA, Fissell WH. Shear stress is normalized in glomerular capillaries following ⅚ nephrectomy. Am J Physiol Renal Physiol 2015; 308:F588-93. [PMID: 25587117 DOI: 10.1152/ajprenal.00290.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Loss of significant functional renal mass results in compensatory structural and hemodynamic adaptations in the nephron. While these changes have been characterized in several injury models, how they affect hemodynamic forces at the glomerular capillary wall has not been adequately characterized, despite their potential physiological significance. Therefore, we used intravital multiphoton microscopy to measure the velocity of red blood cells in individual glomerular capillaries of normal rats and rats subjected to ⅚ nephrectomy. Glomerular capillary blood flow rate and wall shear stress were then estimated using previously established experimental and mathematical models to account for changes in hematocrit and blood rheology in small vessels. We found little change in the hemodynamic parameters in glomerular capillaries immediately following injury. At 2 wk postnephrectomy, significant changes in individual capillary blood flow velocity and volume flow rate were present. Despite these changes, estimated capillary wall shear stress was unchanged. This was a result of an increase in capillary diameter and changes in capillary blood rheology in nephrectomized rats.
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Affiliation(s)
- Nicholas Ferrell
- Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee;
| | - Ruben M Sandoval
- Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Aihua Bian
- Department of Biostatistics, Vanderbilt University, Nashville, Tennessee; and
| | | | - Bruce A Molitoris
- Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana; Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana
| | - William H Fissell
- Division of Nephrology, Vanderbilt University Medical Center, Nashville, Tennessee
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10
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Saleh MA, Sandoval RM, Rhodes GJ, Campos-Bilderback SB, Molitoris BA, Pollock DM. Chronic endothelin-1 infusion elevates glomerular sieving coefficient and proximal tubular albumin reuptake in the rat. Life Sci 2012; 91:634-7. [PMID: 22727794 PMCID: PMC3728660 DOI: 10.1016/j.lfs.2012.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 05/31/2012] [Accepted: 06/05/2012] [Indexed: 10/28/2022]
Abstract
AIM We have previously found that chronic endothelin-1 (ET-1) infusion in Sprague-Dawley rats increases glomerular permeability to albumin (P(alb)) as assessed in vitro independent of blood pressure with no observed albuminuria. In this study, we hypothesized that ET-1 increases glomerular albumin filtration with accompanied increase in albumin uptake via the proximal tubule, which masks the expected increase in urinary albumin excretion. MAIN METHODS Nonfasting Munich-Wistar Fromter rats were surgically prepared for in vivo imaging (n=6). Rats were placed on the microscope stage with the exposed kidney placed in a cover slip-bottomed dish bathed in warm isotonic saline. Rats were then injected i.v. with rat serum albumin conjugated to Texas Red that was observed to enter capillary loops of superficial glomeruli, move into Bowman's space, bind to the proximal tubular cell brush border and reabsorbed across the apical membrane. Glomerular sieving coefficient (GSC) was calculated as the ratio of conjugated albumin within the glomerular capillary versus that in Bowman's space. Rats were again studied after 2 weeks of chronic ET-1 (2 pmol/kg/min; i.v. osmotic minipump). KEY FINDINGS Glomerular sieving coefficient was significantly increased in rats following chronic ET-1 infusion (0.025 ± 0.005 vs. 0.017 ± 0.003, p<0.05). Mean fluorescence intensity for conjugated albumin within proximal tubules was increased by ET-1 infusion: 118.40 ± 6.34 vs. 74.27 ± 4.45 pixel intensity (p<0.01). SIGNIFICANCE These data provide in vivo evidence that ET-1 directly increases glomerular permeability to albumin and that albuminuria is prevented by increased PT albumin uptake in the rat.
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Affiliation(s)
- Mohamed A. Saleh
- Department of Pharmacology and Toxicology, Georgia Health Sciences University, Augusta, GA
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Egypt
| | - Ruben M. Sandoval
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN
| | - George J. Rhodes
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN
| | | | - Bruce A. Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN
| | - David M. Pollock
- Section of Experimental Medicine, Department of Medicine, Georgia Health Sciences University, Augusta, GA
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Sandoval RM, Wagner MC, Patel M, Campos-Bilderback SB, Rhodes GJ, Wang E, Wean SE, Clendenon SS, Molitoris BA. Multiple factors influence glomerular albumin permeability in rats. J Am Soc Nephrol 2012; 23:447-57. [PMID: 22223875 DOI: 10.1681/asn.2011070666] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Different laboratories recently reported incongruous results describing the quantification of albumin filtration using two-photon microscopy. We investigated the factors that influence the glomerular sieving coefficient for albumin (GSC(A)) in an effort to explain these discordant reports and to develop standard operating procedures for determining GSC(A). Multiple factors influenced GSC(A), including the kidney depth of image acquisition (10-20 μm was appropriate), the selection of fluorophore (probes emitting longer wavelengths were superior), the selection of plasma regions for fluorescence measurements, the size and molecular dispersion characteristics of dextran polymers if used, dietary status, and the genetic strain of rat. Fasting reduced the GSC(A) in Simonsen Munich Wistar rats from 0.035±0.005 to 0.016±0.004 (P<0.01). Frömter Munich Wistar rats had a much lower GSC(A) in both the fed and the fasted states. Finally, we documented extensive albumin transcytosis with vesicular and tubular delivery to and fusion with the basolateral membrane in S1 proximal tubule cells. In summary, these results help explain the previously conflicting microscopy and micropuncture data describing albumin filtration and highlight the dynamic nature of glomerular albumin permeability.
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Affiliation(s)
- Ruben M Sandoval
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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