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Molitoris BA, Dunn KW, Sandoval RM. Proximal tubule role in albumin homeostasis: controversy, species differences, and the contributions of intravital microscopy. Kidney Int 2023; 104:1065-1069. [PMID: 37981429 DOI: 10.1016/j.kint.2023.05.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/23/2023] [Accepted: 05/30/2023] [Indexed: 11/21/2023]
Affiliation(s)
- Bruce A Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.
| | - Kenneth W Dunn
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ruben M Sandoval
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Wagner MC, Sandoval RM, Yadav SPS, Campos SB, Rhodes GJ, Phillips CL, Molitoris BA. Lrpap1 (RAP) Inhibits Proximal Tubule Clathrin Mediated and Clathrin Independent Endocytosis, Ameliorating Renal Aminoglycoside Nephrotoxicity. Kidney360 2023; 4:591-605. [PMID: 36848531 PMCID: PMC10278819 DOI: 10.34067/kid.0000000000000094] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 01/31/2023] [Indexed: 03/01/2023]
Abstract
Key Points Proximal tubule endocytosis of toxins often leads to nephrotoxicity. Inhibition of endocytosis with receptor-associated protein may serve as a clinical approach to reduce or eliminate kidney damage from a potential nephrotoxin. Background Proximal tubules (PTs) are exposed to many exogenous and endogenous nephrotoxins that pass through the glomerular filter. This includes many small molecules, such as aminoglycoside and myeloma light chains. These filtered molecules are rapidly endocytosed by the PTs and lead to nephrotoxicity. Methods To investigate whether inhibition of PT uptake of filtered toxins can reduce toxicity, we evaluated the ability of Lrpap1 or receptor-associated protein (RAP) to prevent PT endocytosis. Munich Wistar Frömter rats were used since both glomerular filtration and PT uptake can be visualized and quantified. The injury model chosen was the well-established gentamicin-induced toxicity, which leads to significant reductions in GFR and serum creatinine increases. CKD was induced with a right uninephrectomy and left 40-minute pedicle clamp. Rats had 8 weeks to recover and to stabilize GFR and proteinuria. Multiphoton microscopy was used to evaluate endocytosis in vivo and serum creatinine, and 24-hour creatinine clearances were used to evaluate kidney functional changes. Results Studies showed that preadministration of RAP significantly inhibited both albumin and dextran endocytosis in outer cortical PTs. Importantly, this inhibition was found to be rapidly reversible with time. RAP was also found to be an excellent inhibitor of PT gentamicin endocytosis. Finally, gentamicin administration for 6 days resulted in significant elevation of serum creatinine in vehicle-treated rats, but not in those receiving daily infusion of RAP before gentamicin. Conclusions This study provides a model for the potential use of RAP to prevent, in a reversible manner, PT endocytosis of potential nephrotoxins, thus protecting the kidney from damage.
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Affiliation(s)
- Mark C Wagner
- Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
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Datta-Mannan A, Molitoris BA, Feng Y, Martinez MM, Sandoval RM, Brown RM, Merkel D, Croy JE, Dunn KW. Intravital Microscopy Reveals Unforeseen Biodistribution Within the Liver and Kidney Mechanistically Connected to the Clearance of a Bifunctional Antibody. Drug Metab Dispos 2023; 51:403-412. [PMID: 36460476 PMCID: PMC11022859 DOI: 10.1124/dmd.122.001049] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/16/2022] [Accepted: 11/07/2022] [Indexed: 12/03/2022] Open
Abstract
Bifunctional antibody (BfAb) therapeutics offer the potential for novel functionalities beyond those of the individual monospecific entities. However, combining these entities into a single molecule can have unpredictable effects, including changes in pharmacokinetics that limit the compound's therapeutic profile. A better understanding of how molecular modifications affect in vivo tissue interactions could help inform BfAb design. The present studies were predicated on the observation that a BfAb designed to have minimal off-target interactions cleared from the circulation twice as fast as the monoclonal antibody (mAb) from which it was derived. The present study leverages the spatial and temporal resolution of intravital microscopy (IVM) to identify cellular interactions that may explain the different pharmacokinetics of the two compounds. Disposition studies of mice demonstrated that radiolabeled compounds distributed similarly over the first 24 hours, except that BfAb accumulated approximately two- to -three times more than mAb in the liver. IVM studies of mice demonstrated that both distributed to endosomes of liver endothelia but with different kinetics. Whereas mAb accumulated rapidly within the first hour of administration, BfAb accumulated only modestly during the first hour but continued to accumulate over 24 hours, ultimately reaching levels similar to those of the mAb. Although neither compound was freely filtered by the mouse or rat kidney, BfAb, but not mAb, was found to accumulate over 24 hours in endosomes of proximal tubule cells. These studies demonstrate how IVM can be used as a tool in drug design, revealing unpredicted cellular interactions that are undetectable by conventional analyses. SIGNIFICANCE STATEMENT: Bifunctional antibodies offer novel therapeutic functionalities beyond those of the individual monospecific entities. However, combining these entities into a single molecule can have unpredictable effects, including undesirable changes in pharmacokinetics. Studies of the dynamic distribution of a bifunctional antibody and its parent monoclonal antibody presented here demonstrate how intravital microscopy can expand our understanding of the in vivo disposition of therapeutics, detecting off-target interactions that could not be detected by conventional pharmacokinetics approaches or predicted by conventional physicochemical analyses.
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Affiliation(s)
- Amita Datta-Mannan
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Bruce A Molitoris
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Yiqing Feng
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Michelle M Martinez
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Ruben M Sandoval
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Robin M Brown
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Daniel Merkel
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Johnny E Croy
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
| | - Kenneth W Dunn
- Exploratory Medicine and Pharmacology (A.D-M.), Clinical Laboratory Services (R.M.B.), and Biotechnology Discovery Research (Y.F., D.M., J.E.C.), Lilly Research Laboratories, Indianapolis, Indiana and Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana (K.W.D.)
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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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Molitoris BA, Sandoval RM, Yadav SPS, Wagner MC. Albumin Uptake and Processing by the Proximal Tubule: Physiologic, Pathologic and Therapeutic Implications. Physiol Rev 2022; 102:1625-1667. [PMID: 35378997 PMCID: PMC9255719 DOI: 10.1152/physrev.00014.2021] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
For nearly 50 years the proximal tubule (PT) has been known to reabsorb, process, and either catabolize or transcytose albumin from the glomerular filtrate. Innovative techniques and approaches have provided insights into these processes. Several genetic diseases, nonselective PT cell defects, chronic kidney disease (CKD), and acute PT injury lead to significant albuminuria, reaching nephrotic range. Albumin is also known to stimulate PT injury cascades. Thus, the mechanisms of albumin reabsorption, catabolism, and transcytosis are being reexamined with the use of techniques that allow for novel molecular and cellular discoveries. Megalin, a scavenger receptor, cubilin, amnionless, and Dab2 form a nonselective multireceptor complex that mediates albumin binding and uptake and directs proteins for lysosomal degradation after endocytosis. Albumin transcytosis is mediated by a pH-dependent binding affinity to the neonatal Fc receptor (FcRn) in the endosomal compartments. This reclamation pathway rescues albumin from urinary losses and cellular catabolism, extending its serum half-life. Albumin that has been altered by oxidation, glycation, or carbamylation or because of other bound ligands that do not bind to FcRn traffics to the lysosome. This molecular sorting mechanism reclaims physiological albumin and eliminates potentially toxic albumin. The clinical importance of PT albumin metabolism has also increased as albumin is now being used to bind therapeutic agents to extend their half-life and minimize filtration and kidney injury. The purpose of this review is to update and integrate evolving information regarding the reabsorption and processing of albumin by proximal tubule cells including discussion of genetic disorders and therapeutic considerations.
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Affiliation(s)
- Bruce A. Molitoris
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
- Dept.of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Ruben M. Sandoval
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Shiv Pratap S. Yadav
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Mark C. Wagner
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
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Molitoris BA, Sandoval RM, Wagner MC. Intravital Multiphoton Microscopy as a Tool for Studying Renal Physiology, Pathophysiology and Therapeutics. Front Physiol 2022; 13:827280. [PMID: 35399274 PMCID: PMC8988037 DOI: 10.3389/fphys.2022.827280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/09/2022] [Indexed: 11/13/2022] Open
Abstract
Intravital multiphoton microscopy has empowered investigators to study dynamic cell and subcellular processes in vivo within normal and disease organs. Advances in hardware, software, optics, transgenics and fluorescent probe design and development have enabled new quantitative approaches to create a disruptive technology pioneering advances in understanding of normal biology, disease pathophysiology and therapies. Offering superior spatial and temporal resolution with high sensitivity, investigators can follow multiple processes simultaneously and observe complex interactions between different cell types, intracellular organelles, proteins and track molecules for cellular uptake, intracellular trafficking, and metabolism in a cell specific fashion. The technique has been utilized in the kidney to quantify multiple dynamic processes including capillary flow, permeability, glomerular function, proximal tubule processes and determine the effects of diseases and therapeutic mechanisms. Limitations include the depth of tissue penetration with loss of sensitivity and resolution due to scattered emitted light. Tissue clearing technology has virtually eliminated penetration issues for fixed tissue studies. Use of multiphoton microscopy in preclinical animal models offers distinct advantages resulting in new insights into physiologic processes and the pathophysiology and treatment of diseases.
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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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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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Uchida M, Maier B, Waghwani HK, Selivanovitch E, Pay SL, Avera J, Yun EJ, Sandoval RM, Molitoris BA, Zollman A, Douglas T, Hato T. The archaeal Dps nanocage targets kidney proximal tubules via glomerular filtration. J Clin Invest 2020; 129:3941-3951. [PMID: 31424427 DOI: 10.1172/jci127511] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 06/18/2019] [Indexed: 12/15/2022] Open
Abstract
Nature exploits cage-like proteins for a variety of biological purposes, from molecular packaging and cargo delivery to catalysis. These cage-like proteins are of immense importance in nanomedicine due to their propensity to self-assemble from simple identical building blocks to highly ordered architecture and the design flexibility afforded by protein engineering. However, delivery of protein nanocages to the renal tubules remains a major challenge because of the glomerular filtration barrier, which effectively excludes conventional size nanocages. Here, we show that DNA-binding protein from starved cells (Dps) - the extremely small archaeal antioxidant nanocage - is able to cross the glomerular filtration barrier and is endocytosed by the renal proximal tubules. Using a model of endotoxemia, we present an example of the way in which proximal tubule-selective Dps nanocages can limit the degree of endotoxin-induced kidney injury. This was accomplished by amplifying the endogenous antioxidant property of Dps with addition of a dinuclear manganese cluster. Dps is the first-in-class protein cage nanoparticle that can be targeted to renal proximal tubules through glomerular filtration. In addition to its therapeutic potential, chemical and genetic engineering of Dps will offer a nanoplatform to advance our understanding of the physiology and pathophysiology of glomerular filtration and tubular endocytosis.
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Affiliation(s)
- Masaki Uchida
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Bernhard Maier
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
| | | | | | - S Louise Pay
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
| | - John Avera
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, USA
| | - EJun Yun
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Ruben M Sandoval
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
| | - Bruce A Molitoris
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
| | - Amy Zollman
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
| | - Trevor Douglas
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Takashi Hato
- Department of Medicine, Indiana University Indianapolis, Indianapolis, Indiana, USA
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Sandoval RM, Garcia-Sanchez AJ, Garcia-Haro J. Optimizing and Updating LoRa Communication Parameters: A Machine Learning Approach. IEEE Trans Netw Serv Manage 2019. [DOI: 10.1109/tnsm.2019.2927759] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
Renal tubular epithelial cells are consistently exposed to flow of glomerular filtrate that creates fluid shear stress at the apical cell surface. This biophysical stimulus regulates several critical renal epithelial cell functions, including transport, protein uptake, and barrier function. Defining the in vivo mechanical conditions in the kidney tubule is important for accurately recapitulating these conditions in vitro. Here we provide a summary of the fluid flow conditions in the kidney and how this translates into different levels of fluid shear stress down the length of the nephron. A detailed method is provided for measuring fluid flow in the proximal tubule by intravital microscopy. Devices to mimic in vivo fluid shear stress for in vitro studies are discussed, and we present two methods for culture and analysis of renal tubule epithelial cells exposed physiological levels of fluid shear stress. The first is a microfluidic device that permits application of controlled shear stress to cells cultured on porous membranes. The second is culture of renal tubule cells on an orbital shaker. Each method has advantages and disadvantages that should be considered in the context of the specific experimental objectives.
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Affiliation(s)
- Nicholas Ferrell
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, United States; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States.
| | - Ruben M Sandoval
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Bruce A Molitoris
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Paul Brakeman
- Department of Pediatrics, University of California, San Francisco, CA, United States
| | - Shuvo Roy
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA, United States
| | - William H Fissell
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN, United States
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Molitoris BA, George AG, Murray PT, Meier D, Reilly ES, Barreto E, Sandoval RM, Rizk DV, Shaw AD, Peacock WF. A Novel Fluorescent Clinical Method to Rapidly Quantify Plasma Volume. Cardiorenal Med 2019; 9:168-179. [PMID: 30844821 PMCID: PMC7175413 DOI: 10.1159/000496480] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 12/28/2018] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES To determine the performance of a rapid fluorescent indicator technique for measuring plasma volume (PV). METHODS This was an open-label, observational evaluation of a two-component intravenous visible fluorescent dye technique to rapidly measure PV in 16 healthy subjects and 16 subjects with chronic kidney disease (8 stage 3 and 8 stage 4 CKD), at 2 clinical research sites. The method consisted of a single intravenous injection of 12 mg of a large 150-kDa carboxy-methyl dextran conjugated to a fluorescent rhodamine-derived dye as the PV marker (PVM), and 35 mg of a small 5-kDa carboxy-methyl dextran conjugated to fluorescein, the renal clearance marker. Dye concentrations were quantified 15 min after the injections for initial PV measurements using the indicator-dilution principle. Additional samples were taken over 8 h to evaluate the stability of the PVM as a determinant of PV. Blood volumes (BV) were calculated based on PV and the subject's hematocrit. Pharmacokinetic parameters were calculated from the plasma concentration data taken over several days using noncompartmental methods (Phoenix WinNonlin®). Linear correlation and Bland-Altman plots were used to compare visible fluorescent injectate-measured PV compared to Nadler's formula for estimating PV. Finally, 8 healthy subjects received 350 mL infusion of a 5% albumin solution in normal saline over 30 min and a repeat PV determination was then carried out. RESULTS PV and BV varied according to weight and body surface area, with PV ranging from 2,115 to 6,234 mL and 28.6 to 41.9 mL/kg when weight adjusted. Both parameters were stable for > 6 h with repeated plasma measurements of the PVM. There was no difference between healthy subjects and CKD subjects. Overall, there was general agreement with Nadler's estimation formula for the mean PV in subjects. A 24-h repeat dose measurement in 8 healthy subjects showed PV variability of 98 ± 121 mL (mean = 3.8%). Additionally, following an intravenous bolus of 350 mL of a 5% albumin solution in normal saline in 8 healthy subjects, the mean (SD) measured increase in PV was 356 (±50.0) mL post-infusion. There were no serious adverse events reported during the study. CONCLUSIONS This minimally invasive fluorescent dye approach safely allowed for rapid, accurate, and reproducible determination of PV, BV, and dynamic monitoring of changes following fluid administration.
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Affiliation(s)
- Bruce A Molitoris
- Indiana University, Indianapolis, Indiana, USA,
- FAST BioMedical, Carmel, Indiana, USA,
| | - Anthony G George
- Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Alberta, Canada
| | | | | | | | | | - Ruben M Sandoval
- Indiana University, Indianapolis, Indiana, USA
- FAST BioMedical, Carmel, Indiana, USA
| | - Dana V Rizk
- University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Andrew D Shaw
- Department of Anesthesiology and Pain Medicine, University of Alberta, Edmonton, Alberta, Canada
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13
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Abstract
The rat is a favored model organism to study physiological function in vivo. This is largely due to the fact that it has been used for decades and is often more comparable to corresponding human conditions (both normal and pathologic) than mice. Although the development of genetic manipulations in rats has been slower than in mice, recent advances of new genomic editing tools allow for the generation of targeted global and specific cell type mutations in different rat strains. The rat is an ideal model for advancing imaging techniques like intravital multi-photon microscopy or IVMPM. Multi-photon excitation microscopy can be applied to visualize real-time physiologic events in multiple organs including the kidney. This imaging modality can generate four-dimensional high resolution images that are inherently confocal due to the fact that the photon density needed to excite fluorescence only occurs at the objective focal plane, not above or below. Additionally, longer excitation wavelengths allow for deeper penetration into tissue, improved excitation, and are inherently less phototoxic than shorter excitation wavelengths. Applying imaging tools to study physiology in rats has become a valuable scientific technique due to the relatively simple surgical procedures, improved quality of reagents, and reproducibility of established assays. In this chapter, the authors provide an example of the application of fluorescent techniques to study cardio-renal functions in rat models. Use of experimental procedures described here, together with multiple available genetically modified animal models, provide new prospective for the further application of multi-photon microscopy in basic and translational research.
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Affiliation(s)
- Ruben M Sandoval
- Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, USA
- Indiana Center for Biological Microscopy, Indianapolis, IN, USA
| | - Bruce A Molitoris
- Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, USA
- Indiana Center for Biological Microscopy, Indianapolis, IN, USA
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, USA.
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14
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Schulz A, Chuquimia OD, Antypas H, Steiner SE, Sandoval RM, Tanner GA, Molitoris BA, Richter-Dahlfors A, Melican K. Protective vascular coagulation in response to bacterial infection of the kidney is regulated by bacterial lipid A and host CD147. Pathog Dis 2018. [DOI: 10.1093/femsle/fty087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Anette Schulz
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Olga D Chuquimia
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Haris Antypas
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Svava E Steiner
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Ruben M Sandoval
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA
| | - George A Tanner
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Bruce A Molitoris
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA
| | - Agneta Richter-Dahlfors
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Keira Melican
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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15
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Schulz A, Chuquimia OD, Antypas H, Steiner SE, Sandoval RM, Tanner GA, Molitoris BA, Richter-Dahlfors A, Melican K. Protective vascular coagulation in response to bacterial infection of the kidney is regulated by bacterial lipid A and host CD147. Pathog Dis 2018; 76:5210089. [PMID: 30476069 PMCID: PMC7297223 DOI: 10.1093/femspd/fty087] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [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: 07/24/2018] [Accepted: 11/23/2018] [Indexed: 01/26/2023] Open
Abstract
Bacterial infection of the kidney leads to a rapid cascade of host protective responses, many of which are still poorly understood. We have previously shown that following kidney infection with uropathogenic Escherichia coli (UPEC), vascular coagulation is quickly initiated in local perivascular capillaries that protects the host from progressing from a local infection to systemic sepsis. The signaling mechanisms behind this response have not however been described. In this study, we use a number of in vitro and in vivo techniques, including intravital microscopy, to identify two previously unrecognized components influencing this protective coagulation response. The acylation state of the Lipid A of UPEC lipopolysaccharide (LPS) is shown to alter the kinetics of local coagulation onset in vivo. We also identify epithelial CD147 as a potential host factor influencing infection-mediated coagulation. CD147 is expressed by renal proximal epithelial cells infected with UPEC, contingent to bacterial expression of the α-hemolysin toxin. The epithelial CD147 subsequently can activate tissue factor on endothelial cells, a primary step in the coagulation cascade. This study emphasizes the rapid, multifaceted response of the kidney tissue to bacterial infection and the interplay between host and pathogen during the early hours of renal infection.
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Affiliation(s)
- Anette Schulz
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Olga D Chuquimia
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Haris Antypas
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Svava E Steiner
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Ruben M Sandoval
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA
| | - George A Tanner
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Bruce A Molitoris
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA
| | - Agneta Richter-Dahlfors
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
| | - Keira Melican
- Swedish Medical Nanoscience Center, Department of Neuroscience, Karolinska Institutet, SE-171 77, Stockholm, Sweden
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16
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Rizk DV, Meier D, Sandoval RM, Chacana T, Reilly ES, Seegmiller JC, DeNoia E, Strickland JS, Muldoon J, Molitoris BA. A Novel Method for Rapid Bedside Measurement of GFR. J Am Soc Nephrol 2018; 29:1609-1613. [PMID: 29748326 DOI: 10.1681/asn.2018020160] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 04/17/2018] [Indexed: 01/01/2023] Open
Abstract
Background Direct quantitative measurement of GFR (mGFR) remains a specialized task primarily performed in research settings. Multiple formulas for estimating GFR have been developed that use the readily available endogenous biomarkers creatinine and/or cystatin C. However, eGFR formulas have limitations, and an accurate mGFR is necessary in some clinical situations and for certain patient populations. We conducted a prospective, open-label study to evaluate a novel rapid technique for determining plasma volume and mGFR.Methods We developed a new exogenous biomarker, visible fluorescent injectate (VFI), consisting of a large 150-kD rhodamine derivative and small 5-kD fluorescein carboxymethylated dextrans. After a single intravenous injection of VFI, plasma volume and mGFR can be determined on the basis of the plasma pharmacokinetics of the rhodamine derivative and fluorescein carboxymethylated dextrans, respectively. In this study involving 32 adults with normal kidney function (n=16), CKD stage 3 (n=8), or CKD stage 4 (n=8), we compared VFI-based mGFR values with values obtained by measuring iohexol plasma disappearance. VFI-based mGFR required three 0.5-ml blood draws over 3 hours; iohexol-based mGFR required five samples taken over 6 hours. Eight healthy participants received repeat VFI injections at 24 hours.Results VFI-based mGFR values showed close linear correlation with the iohexol-based mGFR values in all participants. Injections were well tolerated, including when given on consecutive days. No serious adverse events were reported. VFI-based mGFR was highly reproducible.Conclusions The VFI-based approach allows for the rapid determination of mGFR at the bedside while maintaining patient safety and measurement accuracy and reproducibility.
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Affiliation(s)
- Dana V Rizk
- Nephrology Division, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama;
| | | | - Ruben M Sandoval
- FAST BioMedical, Carmel, Indiana.,Nephrology Division, Department of Medicine, Indiana University, Indianapolis, Indiana
| | - Teresa Chacana
- Nephrology Division, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | | | - Jesse C Seegmiller
- Advanced Research and Diagnostics Laboratory, University of Minnesota, Minneapolis, Minnesota; and
| | | | | | | | - Bruce A Molitoris
- FAST BioMedical, Carmel, Indiana.,Nephrology Division, Department of Medicine, Indiana University, Indianapolis, Indiana
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17
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Abstract
Intravital microscopy, microscopy of living animals, is a powerful research technique that combines the resolution and sensitivity found in microscopic studies of cultured cells with the relevance and systemic influences of cells in the context of the intact animal. The power of intravital microscopy has recently been extended with the development of multiphoton fluorescence microscopy systems capable of collecting optical sections from deep within the kidney at subcellular resolution, supporting high-resolution characterizations of the structure and function of glomeruli, tubules, and vasculature in the living kidney. Fluorescent probes are administered to an anesthetized, surgically prepared animal, followed by image acquisition for up to 3 hr. Images are transferred via a high-speed network to specialized computer systems for digital image analysis. This general approach can be used with different combinations of fluorescent probes to evaluate processes such as glomerular permeability, proximal tubule endocytosis, microvascular flow, vascular permeability, mitochondrial function, and cellular apoptosis/necrosis. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Kenneth W Dunn
- Indiana University School of Medicine, Indianapolis, Indiana
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18
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Sandoval RM, Molitoris BA. Intravital multiphoton microscopy as a tool for studying renal physiology and pathophysiology. Methods 2017; 128:20-32. [PMID: 28733090 DOI: 10.1016/j.ymeth.2017.07.014] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 06/12/2017] [Accepted: 07/17/2017] [Indexed: 01/10/2023] Open
Abstract
The kidney is a complex and dynamic organ with over 40 cell types, and tremendous structural and functional diversity. Intravital multi-photon microscopy, development of fluorescent probes and innovative software, have rapidly advanced the study of intracellular and intercellular processes within the kidney. Researchers can quantify the distribution, behavior, and dynamic interactions of up to four labeled chemical probes and proteins simultaneously and repeatedly in four dimensions (time), with subcellular resolution in near real time. Thus, multi-photon microscopy has greatly extended our ability to investigate cell biology intravitally, at cellular and subcellular resolutions. Therefore, the purpose of the chapter is to demonstrate how the use in intravital multi-photon microscopy has advanced the understanding of both the physiology and pathophysiology of the kidney.
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Affiliation(s)
- Ruben M Sandoval
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA
| | - Bruce A Molitoris
- Indiana University School of Medicine, Roudebush VAMC, Indiana Center for Biological Microscopy, Indianapolis, IN 46202, USA.
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19
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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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20
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Hato T, Winfree S, Day R, Sandoval RM, Molitoris BA, Yoder MC, Wiggins RC, Zheng Y, Dunn KW, Dagher PC. Two-Photon Intravital Fluorescence Lifetime Imaging of the Kidney Reveals Cell-Type Specific Metabolic Signatures. J Am Soc Nephrol 2017; 28:2420-2430. [PMID: 28250053 DOI: 10.1681/asn.2016101153] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [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: 10/31/2016] [Accepted: 01/30/2017] [Indexed: 11/03/2022] Open
Abstract
In the live animal, tissue autofluorescence arises from a number of biologically important metabolites, such as the reduced form of nicotinamide adenine dinucleotide. Because autofluorescence changes with metabolic state, it can be harnessed as a label-free imaging tool with which to study metabolism in vivo Here, we used the combination of intravital two-photon microscopy and frequency-domain fluorescence lifetime imaging microscopy (FLIM) to map cell-specific metabolic signatures in the kidneys of live animals. The FLIM images are analyzed using the phasor approach, which requires no prior knowledge of metabolite species and can provide unbiased metabolic fingerprints for each pixel of the lifetime image. Intravital FLIM revealed the metabolic signatures of S1 and S2 proximal tubules to be distinct and resolvable at the subcellular level. Notably, S1 and distal tubules exhibited similar metabolic profiles despite apparent differences in morphology and autofluorescence emission with traditional two-photon microscopy. Time-lapse imaging revealed dynamic changes in the metabolic profiles of the interstitium, urinary lumen, and glomerulus-areas that are not resolved by traditional intensity-based two-photon microscopy. Finally, using a model of endotoxemia, we present examples of the way in which intravital FLIM can be applied to study kidney diseases and metabolism. In conclusion, intravital FLIM of intrinsic metabolites is a bias-free approach with which to characterize and monitor metabolism in vivo, and offers the unique opportunity to uncover dynamic metabolic changes in living animals with subcellular resolution.
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Affiliation(s)
| | | | | | | | - Bruce A Molitoris
- Departments of Medicine.,Department of Medicine, Roudebush Indianapolis Veterans Affairs Medical Center, Indianapolis, Indiana
| | | | - Roger C Wiggins
- Department of Medicine, University of Michigan, Ann Arbor, Michigan; and
| | - Yi Zheng
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | | | - Pierre C Dagher
- Departments of Medicine, .,Department of Medicine, Roudebush Indianapolis Veterans Affairs Medical Center, Indianapolis, Indiana.,Pediatrics, Indiana University, Indianapolis, Indiana
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21
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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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22
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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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23
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Sandoval RM, Garcia-Sanchez AJ, Garcia-Sanchez F, Garcia-Haro J. Evaluating the More Suitable ISM Frequency Band for IoT-Based Smart Grids: A Quantitative Study of 915 MHz vs. 2400 MHz. Sensors (Basel) 2016; 17:s17010076. [PMID: 28042863 PMCID: PMC5298649 DOI: 10.3390/s17010076] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/19/2016] [Accepted: 12/28/2016] [Indexed: 11/26/2022]
Abstract
IoT has begun to be employed pervasively in industrial environments and critical infrastructures thanks to its positive impact on performance and efficiency. Among these environments, the Smart Grid (SG) excels as the perfect host for this technology, mainly due to its potential to become the motor of the rest of electrically-dependent infrastructures. To make this SG-oriented IoT cost-effective, most deployments employ unlicensed ISM bands, specifically the 2400 MHz one, due to its extended communication bandwidth in comparison with lower bands. This band has been extensively used for years by Wireless Sensor Networks (WSN) and Mobile Ad-hoc Networks (MANET), from which the IoT technologically inherits. However, this work questions and evaluates the suitability of such a “default” communication band in SG environments, compared with the 915 MHz ISM band. A comprehensive quantitative comparison of these bands has been accomplished in terms of: power consumption, average network delay, and packet reception rate. To allow such a study, a dual-band propagation model specifically designed for the SG has been derived, tested, and incorporated into the well-known TOSSIM simulator. Simulation results reveal that only in the absence of other 2400 MHz interfering devices (such as WiFi or Bluetooth) or in small networks, is the 2400 MHz band the best option. In any other case, SG-oriented IoT quantitatively perform better if operating in the 915 MHz band.
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Affiliation(s)
- Ruben M Sandoval
- Department of Information and Communication Technologies, Universidad Politécnica de Cartagena (UPCT), Campus Muralla del Mar, E-30202 Cartagena, Spain.
| | - Antonio-Javier Garcia-Sanchez
- Department of Information and Communication Technologies, Universidad Politécnica de Cartagena (UPCT), Campus Muralla del Mar, E-30202 Cartagena, Spain.
| | - Felipe Garcia-Sanchez
- Department of Information and Communication Technologies, Universidad Politécnica de Cartagena (UPCT), Campus Muralla del Mar, E-30202 Cartagena, Spain.
| | - Joan Garcia-Haro
- Department of Information and Communication Technologies, Universidad Politécnica de Cartagena (UPCT), Campus Muralla del Mar, E-30202 Cartagena, Spain.
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24
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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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Li XC, Sandoval RM, Molitoris BA, Zhuo JL. Abstract 077: In Vivo Evidence of AT1a Receptor-Mediated Uptake of Angiotensin II by the Proximal Tubule Visualized by Intravital Multiphoton Imaging. Hypertension 2015. [DOI: 10.1161/hyp.66.suppl_1.077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The development of all forms of angiotensin II (ANG II)-dependent hypertension is associated with higher levels of intrarenal ANG II, which are greater than can be explained on the basis of circulating ANG II and suppressed cortical renin expression. In the present study, we used intravital multiphoton imaging to test the hypothesis that AT1 (AT1a) receptor-mediated uptake of ANG II by the proximal tubules of the kidney plays a major role in the underlying mechanisms. Adult male Munich-Wistar rats were anesthetized with Inactin and continuously infused with a pressor dose of Alexa 488-conjugated ANG II (50 ng/min, i.v.) for 2 hr. Time-dependent proximal tubular uptake responses of Alexa 488-ANG II were studied with mean arterial blood pressure maintained at ~150 mmHg throughout the experiment. After 30 min infusion, very low levels of Alexa 488-ANG II were visualized within proximal tubules and cortical collecting ducts (CCDs) (p<0.05). However, high levels of Alexa 488-ANG II were accumulated in the lumen of CCDs, but not that of proximal tubules. After 1 hr infusion, moderate levels of Alexa 488-ANG II were visualized in the proximal tubules, but not in the glomeruli and CCDs. The most striking uptake responses were visualized in all segments of proximal tubules after 2 hr infusion. Internalized Alexa 488-ANG II was predominantly localized to the basolateral side, where it was colocalized with tetramethyl rhodamine methyl ester (TMRM), a mitochondrial membrane potential-dependent dye. TMRM is a lipophilic cationic dye that is primarily accumulated in the mitochondria of proximal tubules. Some internalized Alexa 488-ANG II was visualized around and over the nuclei. Furthermore, the uptake of Alexa 488-ANG II by proximal tubules was significantly attenuated in caveolin 1-knockout mice (p<0.01), and blocked in AT1a receptor-knockout mice (p<0.01). Our results provide strong intravital multiphoton microscopic evidence that circulating ANG II is primarily taken up by the proximal tubules of the kidney via an AT1a receptor-mediated mechanism, and that internalized ANG II may be transported to the mitochondria and the nucleus, where it may alter mitochondrial and nuclear function in the proximal tubules of the kidney.
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Affiliation(s)
- Xiao C Li
- Univ of Mississippi Med Cntr, Jackson, MS
| | | | | | - Jia L Zhuo
- Univ of Mississippi Med Cntr, Jackson, MS
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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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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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Sandoval RM, Wang E, Molitoris BA. Finding the bottom and using it: Offsets and sensitivity in the detection of low intensity values in vivo with 2-photon microscopy. Intravital 2014; 2. [PMID: 25313346 DOI: 10.4161/intv.23674] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Maximizing 2-photon parameters used in acquiring images for quantitative intravital microscopy, especially when high sensitivity is required, remains an open area of investigation. Here we present data on correctly setting the black level of the photomultiplier tube amplifier by adjusting the offset to allow for accurate quantitation of low intensity processes. When the black level is set too high some low intensity pixel values become zero and a nonlinear degradation in sensitivity occurs rendering otherwise quantifiable low intensity values virtually undetectable. Initial studies using a series of increasing offsets for a sequence of concentrations of fluorescent albumin in vitro revealed a loss of sensitivity for higher offsets at lower albumin concentrations. A similar decrease in sensitivity, and therefore the ability to correctly determine the glomerular permeability coefficient of albumin, occurred in vivo at higher offset. Finding the offset that yields accurate and linear data are essential for quantitative analysis when high sensitivity is required.
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Affiliation(s)
- Ruben M Sandoval
- Indiana University School of Medicine; Indianapolis, IN USA ; The Roudebush VA; Indianapolis, IN USA
| | - Exing Wang
- Department of Cellular and Structural Biology; University of Texas Health Science Center; San Antonio, TX USA
| | - Bruce A Molitoris
- Indiana University School of Medicine; Indianapolis, IN USA ; The Roudebush VA; Indianapolis, IN USA
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Carrisoza-Gaytan R, Liu Y, Flores D, Else C, Lee HG, Rhodes G, Sandoval RM, Kleyman TR, Lee FYI, Molitoris B, Satlin LM, Rohatgi R. Effects of biomechanical forces on signaling in the cortical collecting duct (CCD). Am J Physiol Renal Physiol 2014; 307:F195-204. [PMID: 24872319 DOI: 10.1152/ajprenal.00634.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
An increase in tubular fluid flow rate (TFF) stimulates Na reabsorption and K secretion in the cortical collecting duct (CCD) and subjects cells therein to biomechanical forces including fluid shear stress (FSS) and circumferential stretch (CS). Intracellular MAPK and extracellular autocrine/paracrine PGE2 signaling regulate cation transport in the CCD and, at least in other systems, are affected by biomechanical forces. We hypothesized that FSS and CS differentially affect MAPK signaling and PGE2 release to modulate cation transport in the CCD. To validate that CS is a physiological force in vivo, we applied the intravital microscopic approach to rodent kidneys in vivo to show that saline or furosemide injection led to a 46.5 ± 2.0 or 170 ± 32% increase, respectively, in distal tubular diameter. Next, murine CCD (mpkCCD) cells were grown on glass or silicone coated with collagen type IV and subjected to 0 or 0.4 dyne/cm(2) of FSS or 10% CS, respectively, forces chosen based on prior biomechanical modeling of ex vivo microperfused CCDs. Cells exposed to FSS expressed an approximately twofold greater abundance of phospho(p)-ERK and p-p38 vs. static cells, while CS did not alter p-p38 and p-ERK expression compared with unstretched controls. FSS induced whereas CS reduced PGE2 release by ∼40%. In conclusion, FSS and CS differentially affect ERK and p38 activation and PGE2 release in a cell culture model of the CD. We speculate that TFF differentially regulates biomechanical signaling and, in turn, cation transport in the CCD.
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Affiliation(s)
| | - Yu Liu
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Daniel Flores
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, James J. Peters Veterans Affairs Medical Center, New York, New York
| | - Cindy Else
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Heon Goo Lee
- Department of Orthopedics, Robert Carroll and Jane Chace Carroll Laboratories, Columbia College of Physicians and Surgeons, New York, New York
| | - George Rhodes
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Ruben M Sandoval
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Thomas R Kleyman
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Francis Young-In Lee
- Department of Orthopedics, Robert Carroll and Jane Chace Carroll Laboratories, Columbia College of Physicians and Surgeons, New York, New York
| | - Bruce Molitoris
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Rajeev Rohatgi
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, James J. Peters Veterans Affairs Medical Center, New York, New York;
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Sandoval RM, Molitoris BA. Letter to the editor: "Quantifying albumin permeability with multiphoton microscopy: why the difference?". Am J Physiol Renal Physiol 2014; 306:F1098-100. [PMID: 24785957 PMCID: PMC5243215 DOI: 10.1152/ajprenal.00652.2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Ruben M Sandoval
- Indiana Univ. School of Medicine, 1120 South Dr., Indianapolis, IN 46202-5116.
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Abstract
Recent data highlight the role of the proximal tubule (PT) in reabsorbing, processing, and transcytosing urinary albumin from the glomerular filtrate. Innovative techniques and approaches have provided exciting insights into these processes, and numerous investigators have shown that selective PT cell defects lead to significant albuminuria, even reaching nephrotic range in animal models. Thus, the mechanisms of albumin reabsorption and transcytosis are undergoing intense study. Working in concert with megalin and cubilin, a nonselective multireceptor complex that predominantly directs proteins for lysosomal degradation, the neonatal Fc receptor (FcRn) located at the brush border of the apical membrane has been implicated as the "receptor" mediating albumin transcytosis. The FcRn pathway facilitates reabsorption and mediates transcytosis by its pH-dependent binding affinity in endosomal compartments. This also allows for selective albumin sorting within the PT cell. This reclamation pathway minimizes urinary losses and catabolism of albumin, thus prolonging its serum half-life. It may also serve as a molecular sorter to preserve and reclaim normal albumin while allowing "altered" albumin to be catabolized via lysosomal pathways. Here, we critically review the data supporting this novel mechanism.
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Affiliation(s)
- Landon E Dickson
- Indiana University School of Medicine, The Roudebush Veterans Affairs Medical Center, Indiana Center for Biological Microscopy, Indianapolis, Indiana
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Sandoval RM, Molitoris BA. Quantifying glomerular permeability of fluorescent macromolecules using 2-photon microscopy in Munich Wistar rats. J Vis Exp 2013. [PMID: 23628966 DOI: 10.3791/50052] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Kidney diseases involving urinary loss of large essential macromolecules, such as serum albumin, have long been thought to be caused by alterations in the permeability barrier comprised of podocytes, vascular endothelial cells, and a basement membrane working in unison. Data from our laboratory using intravital 2-photon microscopy revealed a more permeable glomerular filtration barrier (GFB) than previously thought under physiologic conditions, with retrieval of filtered albumin occurring in an early subset of cells called proximal tubule cells (PTC)(1,2,3). Previous techniques used to study renal filtration and establishing the characteristic of the filtration barrier involved micropuncture of the lumen of these early tubular segments with sampling of the fluid content and analysis(4). These studies determined albumin concentration in the luminal fluid to be virtually non-existent; corresponding closely to what is normally detected in the urine. However, characterization of dextran polymers with defined sizes by this technique revealed those of a size similar to serum albumin had higher levels in the tubular lumen and urine; suggesting increased permeability(5). Herein is a detailed outline of the technique used to directly visualize and quantify glomerular fluorescent albumin permeability in vivo. This method allows for detection of filtered albumin across the filtration barrier into Bowman's space (the initial chamber of urinary filtration); and also allows quantification of albumin reabsorption by proximal tubules and visualization of subsequent albumin transcytosis(6). The absence of fluorescent albumin along later tubular segments en route to the bladder highlights the efficiency of the retrieval pathway in the earlier proximal tubule segments. Moreover, when this technique was applied to determine permeability of dextrans having a similar size to albumin virtually identical permeability values were reported(2). These observations directly support the need to expand the focus of many proteinuric renal diseases to included alterations in proximal tubule cell reclamation.
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Abstract
Intravital microscopy, microscopy of living animals, is a powerful research technique that combines the resolution and sensitivity found in microscopic studies of cultured cells with the relevance and systemic influences of cells in the context of the intact animal. The power of intravital microscopy has recently been extended with the development of multiphoton fluorescence microscopy systems capable of collecting optical sections from deep within the kidney at subcellular resolution, supporting high-resolution characterizations of the structure and function of glomeruli, tubules, and vasculature in the living kidney. Fluorescent probes are administered to an anesthetized, surgically prepared animal, followed by image acquisition for up to 3 hr. Images are transferred via a high-speed network to specialized computer systems for digital image analysis. This general approach can be used with different combinations of fluorescent probes to evaluate processes such as glomerular permeability, proximal tubule endocytosis, microvascular flow, vascular permeability, mitochondrial function, and cellular apoptosis/necrosis.
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Affiliation(s)
- Kenneth W Dunn
- Indiana University School of Medicine, Indianapolis, IN, USA
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Abstract
Mitochondrial dysfunction has been implicated in the pathogenesis of acute kidney injury due to ischemia and toxic drugs. Methods for imaging mitochondrial function in cells using confocal microscopy are well established; more recently, it was shown that these techniques can be utilized in ex vivo kidney tissue using multiphoton microscopy. We extended this approach in vivo and found that kidney mitochondrial structure and function can be imaged in anesthetized rodents using multiphoton excitation of endogenous and exogenous fluorophores. Mitochondrial nicotinamide adenine dinucleotide increased markedly in rat kidneys in response to ischemia. Following intravenous injection, the mitochondrial membrane potential-dependent dye TMRM was taken up by proximal tubules; in response to ischemia, the membrane potential dissipated rapidly and mitochondria became shortened and fragmented in proximal tubules. In contrast, the mitochondrial membrane potential and structure were better maintained in distal tubules. Changes in mitochondrial structure, nicotinamide adenine dinucleotide, and membrane potential were found in the proximal, but not distal, tubules after gentamicin exposure. These changes were sporadic, highly variable among animals, and were preceded by changes in non-mitochondrial structures. Thus, real-time changes in mitochondrial structure and function can be imaged in rodent kidneys in vivo using multiphoton excitation of endogenous and exogenous fluorophores in response to ischemia-reperfusion injury or drug toxicity.
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MESH Headings
- Acute Kidney Injury/etiology
- Acute Kidney Injury/pathology
- Acute Kidney Injury/physiopathology
- Animals
- Gentamicins/adverse effects
- Glutathione/metabolism
- Ischemia/complications
- Kidney/blood supply
- Kidney Tubules, Distal/metabolism
- Kidney Tubules, Distal/pathology
- Kidney Tubules, Distal/physiopathology
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/pathology
- Kidney Tubules, Proximal/physiopathology
- Male
- Membrane Potential, Mitochondrial/physiology
- Mice
- Mice, Inbred C57BL
- Microscopy, Fluorescence, Multiphoton/methods
- Mitochondria/pathology
- Mitochondria/physiology
- NAD/metabolism
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Reactive Oxygen Species/metabolism
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Affiliation(s)
- Andrew M Hall
- University College London Centre for Nephrology, Royal Free Hospital, London, UK.
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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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A. Molitoris B, J. Meier D, Wang E, M. Sandoval R, Sheridan E, S. Strickland J. Quantifying Glomerular Filtration Rates: Kidney Function Analysis Method and Apparatus. ACTA ACUST UNITED AC 2012. [DOI: 10.2174/2210309011202030209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Imamura R, Isaka Y, Sandoval RM, Ichimaru N, Abe T, Okumi M, Yazawa K, Kitamura H, Kaimori J, Nonomura N, Rakugi H, Molitoris BA, Takahara S. A nonerythropoietic derivative of erythropoietin inhibits tubulointerstitial fibrosis in remnant kidney. Clin Exp Nephrol 2012; 16:852-62. [PMID: 22678524 DOI: 10.1007/s10157-012-0647-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [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] [Received: 01/08/2012] [Accepted: 05/11/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND The tissue-protective effects of erythropoietin (EPO) have been extensively investigated, and EPO administration can raise the hemoglobin (Hb) concentration. Recently, we reported that carbamylated erythropoietin (CEPO) protected kidneys from ischemia-reperfusion injury as well as EPO. METHODS To investigate the clinical applications of CEPO, we next evaluated the long-term therapeutic effect of CEPO using a tubulointerstitial model rat. We randomized remnant kidney model rats to receive saline, EPO, or CEPO for 8 weeks. RESULTS CEPO- and EPO-treated rats had improved serum creatinine levels compared with saline-treated remnant kidney model rats, although the Hb level was significantly increased in EPO-treated rats. Two-photon microscopy revealed that EPO/CEPO significantly ameliorated tubular epithelial cell damage assessed by endocytosis. In addition, CEPO or EPO protected endothelial cells with a sustained blood flow rate. EPO or CEPO suppressed the number of TUNEL-positive apoptotic cells with weak αSMA staining. Furthermore, PCR analysis demonstrated that TGF-β and type I collagen expression was attenuated in EPO- or CEPO-treated rats, accompanied by a significant decrease in interstitial fibrosis. CONCLUSION We established a long-term therapeutic approach to protect tubulointerstitial injury with CEPO, and thus, the therapeutic value of this approach warrants further attention and preclinical studies.
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Affiliation(s)
- Ryoichi Imamura
- Department of Urology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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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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Abstract
To understand the underlying mechanisms of bacterial infections, researchers have for long addressed the molecular interactions occurring when the bacterium interacts with host target cells. In these studies, primarily based on in vitro systems, molecular details have been revealed along with increased knowledge regarding the general infection process. With the recent advancements in in vivo imaging techniques, we are now in a position to bridge a transition from classical minimalistic in vitro approaches to allow infections to be studied in its native complexity-the live organ. Techniques such as multiphoton microscopy (MPM) allow cellular-level visualization of the dynamic infection process in real time within the living host. Studies in which all interplaying factors, such as the influences of the immune, lymphatic, and vascular systems can be accounted for, are likely to provide new insights to our current understanding of the infection process. MPM imaging becomes extra powerful when combined with advanced surgical procedure, allowing studies of the illusive early hours of infection. In this chapter, our intention is to provide a general view on how to design and carry out intravital imaging of a bacterial infection. While exemplifying this using a spatiotemporally well-controlled uropathogenic Escherichia coli (UPEC) infection in rat kidneys, we hope to provide the reader with general considerations that can be adapted to other bacterial infections in organs other than the kidney.
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Affiliation(s)
- Ferdinand X Choong
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
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Kalakeche R, Hato T, Rhodes G, Dunn KW, El-Achkar TM, Plotkin Z, Sandoval RM, Dagher PC. Endotoxin uptake by S1 proximal tubular segment causes oxidative stress in the downstream S2 segment. J Am Soc Nephrol 2011; 22:1505-16. [PMID: 21784899 DOI: 10.1681/asn.2011020203] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Gram-negative sepsis carries high morbidity and mortality, especially when complicated by acute kidney injury (AKI). The mechanisms of AKI in sepsis remain poorly understood. Here we used intravital two-photon fluorescence microscopy to investigate the possibility of direct interactions between filtered endotoxin and tubular cells as a possible mechanism of AKI in sepsis. Using wild-type (WT), TLR4-knockout, and bone marrow chimeric mice, we found that endotoxin is readily filtered and internalized by S1 proximal tubules through local TLR4 receptors and through fluid-phase endocytosis. Only receptor-mediated interactions between endotoxin and S1 caused oxidative stress in neighboring S2 tubules. Despite significant endotoxin uptake, S1 segments showed no oxidative stress, possibly as a result of the upregulation of cytoprotective heme oxygenase-1 and sirtuin-1 (SIRT1). Conversely, S2 segments did not upregulate SIRT1 and exhibited severe structural and functional peroxisomal damage. Taken together, these data suggest that the S1 segment acts as a sensor of filtered endotoxin, which it takes up. Although this may limit the amount of endotoxin in the systemic circulation and the kidney, it results in severe secondary damage to the neighboring S2 segments.
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Affiliation(s)
- Rabih Kalakeche
- Department of Medicine, Division of Nephrology, Indiana University, Indianapolis, Indiana, USA
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Saleh MA, Sandoval RM, Rhodes GJ, Campos SB, Molitoris BA, Pollock DM. Increased proximal tubular uptake prevents albuminuria in chronic endothelin‐1‐infused rats as determined by intravital 2‐photon microscopy. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.665.5] [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)
| | | | | | | | | | - David M Pollock
- SurgeryMedical College of GeorgiaAugustaGA
- Vascular Biology Center
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Melican K, Sandoval RM, Kader A, Josefsson L, Tanner GA, Molitoris BA, Richter-Dahlfors A. Uropathogenic Escherichia coli P and Type 1 fimbriae act in synergy in a living host to facilitate renal colonization leading to nephron obstruction. PLoS Pathog 2011; 7:e1001298. [PMID: 21383970 PMCID: PMC3044688 DOI: 10.1371/journal.ppat.1001298] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 01/18/2011] [Indexed: 12/03/2022] Open
Abstract
The progression of a natural bacterial infection is a dynamic process influenced by the physiological characteristics of the target organ. Recent developments in live animal imaging allow for the study of the dynamic microbe-host interplay in real-time as the infection progresses within an organ of a live host. Here we used multiphoton microscopy-based live animal imaging, combined with advanced surgical procedures, to investigate the role of uropathogenic Escherichia coli (UPEC) attachment organelles P and Type 1 fimbriae in renal bacterial infection. A GFP+ expressing variant of UPEC strain CFT073 and genetically well-defined isogenic mutants were microinfused into rat glomerulus or proximal tubules. Within 2 h bacteria colonized along the flat squamous epithelium of the Bowman's capsule despite being exposed to the primary filtrate. When facing the challenge of the filtrate flow in the proximal tubule, the P and Type 1 fimbriae appeared to act in synergy to promote colonization. P fimbriae enhanced early colonization of the tubular epithelium, while Type 1 fimbriae mediated colonization of the center of the tubule via a mechanism believed to involve inter-bacterial binding and biofilm formation. The heterogeneous bacterial community within the tubule subsequently affected renal filtration leading to total obstruction of the nephron within 8 h. Our results reveal the importance of physiological factors such as filtration in determining bacterial colonization patterns, and demonstrate that the spatial resolution of an infectious niche can be as small as the center, or periphery, of a tubule lumen. Furthermore, our data show how secondary physiological injuries such as obstruction contribute to the full pathophysiology of pyelonephritis. When bacteria such as uropathogenic Escherichia coli (UPEC) infect a living kidney, they face numerous physiological challenges such as the flow of urine. Bacteria need to attach themselves to the epithelial linings of the kidney to withstand this flow. In this work we use a live animal imaging model to study how UPEC colonize a living kidney despite the physiological challenges they face. We show that P and Type 1 fimbriae, two of the most well described UPEC adhesion factors, work together to promote successful bacterial colonization. P fimbriae mediate binding between the bacteria and the epithelial cells lining the tubules, while Type 1 appears to play a role in inter-bacterial binding and biofilm formation in the center parts of the lumen. The heterogeneous bacterial community which filled the tubule was subsequently shown to effect nephron filtration and resulted in a total loss of filtrate flow i.e. obstruction. This work demonstrates the interplay between the bacterial and host aspects, indicating how factors such as filtration may affect bacterial adhesion and vice versa. It also highlights the multifactorial basis of kidney infection, demonstrating how physiological injuries such as obstruction may contribute towards the full pathophysiology of pyelonephritis.
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Affiliation(s)
- Keira Melican
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - Ruben M. Sandoval
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Abdul Kader
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - Lina Josefsson
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
| | - George A. Tanner
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Bruce A. Molitoris
- Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Agneta Richter-Dahlfors
- Department of Neuroscience, Swedish Medical Nanoscience Center, Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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Molitoris BA, Sandoval RM. Kidney Endothelial Dysfunction: Ischemia, Localized Infections and Sepsis. Contributions to Nephrology 2011; 174:108-118. [DOI: 10.1159/000329248] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Imamura R, Isaka Y, Sandoval RM, Ori A, Adamsky S, Feinstein E, Molitoris BA, Takahara S. Intravital Two-Photon Microscopy Assessment of Renal Protection Efficacy of siRNA for p53 in Experimental Rat Kidney Transplantation Models. Cell Transplant 2010; 19:1659-70. [DOI: 10.3727/096368910x516619] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Renal ischemia-reperfusion (I/R) injury, which is unavoidable in renal transplantation, frequently influences both short- and long-term allograft survival. Despite decades of laboratory and clinical investigations, and the advent of renal replacement therapy, the overall mortality rate due to acute tubular injury has changed little. I/R-induced DNA damage results in p53 activation in proximal tubule cells (PTC), leading to their apoptosis. Therefore, we examined the therapeutic effect of temporary p53 inhibition in two rat renal transplantation models on structural and functional aspects of injury using intravital two-photon microscopy. Nephrectomized Sprague-Dawley rats received syngeneic left kidney transplantation either after 40 min of intentional warm ischemia or after combined 5-h cold and 30-min warm ischemia of the graft. Intravenously administrated siRNA for p53 (siP53) has previously been shown to be filtered and reabsorbed by proximal tubular epithelial cells following the warm ischemia/reperfusion injury in a renal clamp model. Here, we showed that it was also taken up by PTC following 5 h of cold ischemia. Compared to saline-treated recipients, treatment with siP53 resulted in conservation of renal function and significantly suppressed the I/R-induced increase in serum creatinine in both kidney transplantation models. Intravital two-photon microscopy revealed that siP53 significantly ameliorated structural and functional damage to the kidney assessed by quantification of tubular cast formation and the number of apoptotic and necrotic tubular cells and by evaluation of blood flow rate. In conclusion, systemic administration of siRNA for p53 is a promising new approach to protect kidneys from I/R injury in renal transplantation.
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Affiliation(s)
- Ryoichi Imamura
- Department of Urology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yoshitaka Isaka
- Department of Nephrology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Ruben M. Sandoval
- Department of Medicine, Division of Nephrology, Indiana Center for Biological Microscopy, Indiana University, Bloomington, IN, USA
| | - Asaf Ori
- Quark Pharmaceuticals Inc., Fremont, CA, USA
| | | | | | - Bruce A. Molitoris
- Department of Medicine, Division of Nephrology, Indiana Center for Biological Microscopy, Indiana University, Bloomington, IN, USA
| | - Shiro Takahara
- Department of Advanced Technology for Transplantation, Osaka University Graduate School of Medicine, Osaka, Japan
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Wang E, Sandoval RM, Campos SB, Molitoris BA. Rapid diagnosis and quantification of acute kidney injury using fluorescent ratio-metric determination of glomerular filtration rate in the rat. Am J Physiol Renal Physiol 2010; 299:F1048-55. [PMID: 20685826 DOI: 10.1152/ajprenal.00691.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The rapid diagnosis and quantification of acute kidney injury (AKI) severity remain high clinical priorities. By combining intravital fluorescent ratiometric two-photon kidney imaging and the two-compartment pharmacokinetics model, we demonstrate that rapid quantification of glomerular filtration rate (GFR) can be achieved in physiologic and AKI rat kidney models. Using a bolus infusion of a mixture of FITC-inulin and a 500-kDa Texas Red dextran, a full spectrum of GFR values, ranging from 0.17 to 1.12 ml·min(-1)·100 g(-1), was obtained. The GFR values thus determined correlated well with values obtained by the standard 2-h inulin infusion clearance method with a Pearson's correlation coefficient of 0.85. In addition, postischemia deterioration was studied by measuring GFR using the two-photon approach during 24 h following a 45-min bilateral ischemia clamp model. The GFR was found to decline sharply during the initial 4 h followed by a nadir with little sign of rising over the ensuing 24-h period. Moreover, a FITC-labeled 5-kDa dextran was identified as having nearly identical filtration characteristics as FITC-inulin, but had markedly increased fluorescent intensity, thus minimizing the quantity needed for individual studies. The technique reported allows for very rapid GFR determinations, within 10-15 min, based on plasma clearance of a freely filtered fluorescence probe, instead of a prolonged one-compartment interstitial space reporter molecule clearance employed by other technologies.
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Affiliation(s)
- Exing Wang
- Nephrology Div., Dept. of Medicine, Indiana Univ. School of Medicine, Indianapolis, IN 46202, USA
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Sandoval RM, Wagner MC, Campos‐Bilderback SB, Wean SE, Molitoris BA. Quantification of Renal Albumin Filtration and FcRn‐Mediated Transcytosis via 2‐Photon Microscopy. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.818.2] [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)
| | - Mark C Wagner
- Medicine/NephrologyIU School of MedicineIndianapolisIN
| | | | - Sarah E Wean
- Medicine/NephrologyIU School of MedicineIndianapolisIN
| | - Bruce A Molitoris
- Medicine/NephrologyIU School of MedicineIndianapolisIN
- Roudebush VAMCIndianapolisIN
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Molitoris BA, Dagher PC, Sandoval RM, Campos SB, Ashush H, Fridman E, Brafman A, Faerman A, Atkinson SJ, Thompson JD, Kalinski H, Skaliter R, Erlich S, Feinstein E. siRNA targeted to p53 attenuates ischemic and cisplatin-induced acute kidney injury. J Am Soc Nephrol 2009; 20:1754-64. [PMID: 19470675 PMCID: PMC2723992 DOI: 10.1681/asn.2008111204] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [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] [Received: 11/24/2008] [Accepted: 04/02/2009] [Indexed: 01/11/2023] Open
Abstract
Proximal tubule cells (PTCs), which are the primary site of kidney injury associated with ischemia or nephrotoxicity, are the site of oligonucleotide reabsorption within the kidney. We exploited this property to test the efficacy of siRNA targeted to p53, a pivotal protein in the apoptotic pathway, to prevent kidney injury. Naked synthetic siRNA to p53 injected intravenously 4 h after ischemic injury maximally protected both PTCs and kidney function. PTCs were the primary site for siRNA uptake within the kidney and body. Following glomerular filtration, endocytic uptake of Cy3-siRNA by PTCs was rapid and extensive, and significantly reduced ischemia-induced p53 upregulation. The duration of the siRNA effect in PTCs was 24 to 48 h, determined by levels of p53 mRNA and protein expression. Both Cy3 fluorescence and in situ hybridization of siRNA corroborated a short t(1/2) for siRNA. The extent of renoprotection, decrease in cellular p53 and attenuation of p53-mediated apoptosis by siRNA were dose- and time-dependent. Analysis of renal histology and apoptosis revealed improved injury scores in both cortical and corticomedullary regions. siRNA to p53 was also effective in a model of cisplatin-induced kidney injury. Taken together, these data indicate that rapid delivery of siRNA to proximal tubule cells follows intravenous administration. Targeting siRNA to p53 leads to a dose-dependent attenuation of apoptotic signaling, suggesting potential therapeutic benefit for ischemic and nephrotoxic kidney injury.
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Affiliation(s)
- Bruce A. Molitoris
- *Department of Medicine, Division of Nephrology, and Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
- Roudebush V.A. Medical Center, Indianapolis, Indiana
| | - Pierre C. Dagher
- *Department of Medicine, Division of Nephrology, and Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ruben M. Sandoval
- *Department of Medicine, Division of Nephrology, and Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
- Roudebush V.A. Medical Center, Indianapolis, Indiana
| | - Silvia B. Campos
- *Department of Medicine, Division of Nephrology, and Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
- Roudebush V.A. Medical Center, Indianapolis, Indiana
| | - Hagit Ashush
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
| | - Eduard Fridman
- Department of Pathology, Sheba Medical Center, Sackler School of Medicine, Tel Ha-Shomer, Israel
| | - Anat Brafman
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
| | - Alexander Faerman
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
| | - Simon J. Atkinson
- *Department of Medicine, Division of Nephrology, and Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Hagar Kalinski
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
| | - Rami Skaliter
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
- Development Division, Quark Pharmaceuticals Inc, Boulder, Colorado
| | - Shai Erlich
- Development Division, Quark Pharmaceuticals Inc, Boulder, Colorado
| | - Elena Feinstein
- Research Division, Quark Pharmaceuticals Inc (QBI Enterprises Ltd), Weizmann Science Park, Ness Ziona, Israel
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Imamura R, Isaka Y, Sandoval RM, Kakuta Y, Abe T, Okumi M, Ichimaru N, Takada S, Matsumiya K, Molitoris BA, Okuyama A, Takahara S. SYSTEMIC ADMINISTRATION OF SIRNA TARGETING P53 PROTECTS KIDNEYS FROM ISCHEMIA-REPERFUSION INJURY IN EXPERIMENTAL RAT KIDNEY TRANSPLANTATION MODEL. J Urol 2009. [DOI: 10.1016/s0022-5347(09)62075-9] [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: 11/17/2022]
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Sharfuddin AA, Sandoval RM, Berg DT, McDougal GE, Campos SB, Phillips CL, Jones BE, Gupta A, Grinnell BW, Molitoris BA. Soluble thrombomodulin protects ischemic kidneys. J Am Soc Nephrol 2009; 20:524-34. [PMID: 19176699 DOI: 10.1681/asn.2008060593] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [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
Altered coagulation and inflammation contribute to the pathogenesis of ischemic renal injury. Thrombomodulin is a necessary factor in the anticoagulant protein C pathway and has inherent anti-inflammatory properties. We studied the effect of soluble thrombomodulin (sTM) in a hypoperfusion model of ischemic kidney injury. To markedly reduce infrarenal aortic blood flow and femoral arterial pressures, we clamped the suprarenal aorta of rats, occluding them 90%, for 60 min. Reversible acute kidney injury (AKI) occurred at 24 h in rats subjected to hypoperfusion. Histologic analysis at 24 h revealed acute tubular necrosis (ATN), and intravital two-photon microscopy showed flow abnormalities in the microvasculature and defects of endothelial permeability. Pretreatment with rat sTM markedly reduced both I-R-induced renal dysfunction and tubular histologic injury scores. sTM also significantly improved microvascular erythrocyte flow rates, reduced microvascular endothelial leukocyte rolling and attachment, and minimized endothelial permeability to infused fluorescence dextrans, assessed by intravital quantitative multiphoton microscopy. Furthermore, sTM administered 2 h after reperfusion protected against ischemia-induced renal dysfunction at 24 h and improved survival. By using an sTM variant, we also determined that the protective effects of sTM were independent of its ability to generate activated protein C. These data suggest that sTM may have therapeutic potential for ischemic AKI.
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Affiliation(s)
- Asif A Sharfuddin
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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