1
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Costanzo V, D’Apolito L, Sardella D, Iervolino A, La Manna G, Capasso G, Frische S, Trepiccione F. Single nephron glomerular filtration rate measured by linescan multiphoton microscopy compared to conventional micropuncture. Pflugers Arch 2022; 474:733-741. [PMID: 35397662 PMCID: PMC9192459 DOI: 10.1007/s00424-022-02686-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 12/19/2022]
Abstract
Renal micropuncture, which requires the direct access to the renal tubules, has for long time been the technique of choice to measure the single nephron glomerular filtration rate (SNGFR) in animal models. This approach is challenging by virtue of complex animal preparation and numerous technically difficult steps. The introduction of intravital multiphoton microscopy (MPM) offers another approach to the measure of the SNGFR by mean of the high laser-tissue penetration and the optical sectioning capacity. Previous MPM studies measuring SNGFR in vivo relied on fast full-frame acquisition during the filtration process obtainable with high performance resonant scanners. In this study, we describe an innovative linescan–based MPM method. The new method can discriminate SNGFR variations both in conditions of low and high glomerular filtration, and shows results comparable to conventional micropuncture both for rats and mice. Moreover, this novel approach has improved spatial and time resolution and is faster than previous methods, thus enabling the investigation of SNGFR from more tubules and improving options for data-analysis.
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2
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Lang L, Bauer CP, Phillips CR, Keller U. 51-W average power, 169-fs pulses from an ultrafast non-collinear optical parametric oscillator. OPTICS EXPRESS 2021; 29:36321-36327. [PMID: 34809045 DOI: 10.1364/oe.440189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/05/2021] [Indexed: 06/13/2023]
Abstract
We present a high power optical parametric oscillator (OPO) synchronously pumped by the second-harmonic of a modelocked 1030-nm thin-disk laser (TDL) oscillator. The OPO delivers an average power of 51.1 W around degeneracy (1030 nm) with a 10.2-MHz repetition-rate. After extra-cavity dispersion compensation using dispersive mirrors, we obtain a pulse duration of 169 fs, which is 4.6× shorter than the TDL pulse duration of 770 fs. The TDL has 250 W average power, which is converted to 215 W at the second-harmonic. Hence, the OPO exhibits a high photon conversion efficiency of 47% (ratio of signal photons to 515-nm pump photons). Moreover, the OPO generates a peak power of 26.2 MW, which is very similar to the 28.0-MW peak power of the TDL. To facilitate continuous tuning around degeneracy and convenient extraction of the pump and idler beams, the OPO is operated in a noncollinear configuration. A linear cavity configuration was chosen since it offers easy alignment and straightforward cavity length tuning. To the best of our knowledge, this source has the highest average power generated by any ultrafast OPO, and the shortest pulse duration for any >5-W OPO. This result is an important step to adding wavelength tunability to high power Yb-based laser sources without the complexity of either laser or parametric amplifier systems.
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3
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Desposito D, Schiessl IM, Gyarmati G, Riquier-Brison A, Izuhara AK, Kadoya H, Der B, Shroff UN, Hong YK, Peti-Peterdi J. Serial intravital imaging captures dynamic and functional endothelial remodeling with single-cell resolution. JCI Insight 2021; 6:123392. [PMID: 33848265 PMCID: PMC8262275 DOI: 10.1172/jci.insight.123392] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 04/12/2021] [Indexed: 01/01/2023] Open
Abstract
Endothelial cells are important in the maintenance of healthy blood vessels and in the development of vascular diseases. However, the origin and dynamics of endothelial precursors and remodeling at the single-cell level have been difficult to study in vivo owing to technical limitations. Therefore, we aimed to develop a direct visual approach to track the fate and function of single endothelial cells over several days and weeks in the same vascular bed in vivo using multiphoton microscopy (MPM) of transgenic Cdh5-Confetti mice and the kidney glomerulus as a model. Individual cells of the vascular endothelial lineage were identified and tracked owing to their unique color combination, based on the random expression of cyan/green/yellow/red fluorescent proteins. Experimental hypertension, hyperglycemia, and laser-induced endothelial cell ablation rapidly increased the number of new glomerular endothelial cells that appeared in clusters of the same color, suggesting clonal cell remodeling by local precursors at the vascular pole. Furthermore, intravital MPM allowed the detection of distinct structural and functional alterations of proliferating endothelial cells. No circulating Cdh5-Confetti+ cells were found in the renal cortex. Moreover, the heart, lung, and kidneys showed more significant clonal endothelial cell expansion compared with the brain, pancreas, liver, and spleen. In summary, we have demonstrated that serial MPM of Cdh5-Confetti mice in vivo is a powerful technical advance to study endothelial remodeling and repair in the kidney and other organs under physiological and disease conditions.
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Affiliation(s)
- Dorinne Desposito
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Ina Maria Schiessl
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Georgina Gyarmati
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Anne Riquier-Brison
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Audrey K Izuhara
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Hiroyuki Kadoya
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Balint Der
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Urvi Nikhil Shroff
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
| | - Young-Kwon Hong
- Department of Surgery, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Janos Peti-Peterdi
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, and
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4
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Martins JR, Haenni D, Bugarski M, Polesel M, Schuh C, Hall AM. Intravital kidney microscopy: entering a new era. Kidney Int 2021; 100:527-535. [PMID: 34015315 DOI: 10.1016/j.kint.2021.02.042] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/01/2021] [Accepted: 02/16/2021] [Indexed: 02/07/2023]
Abstract
The development of intravital imaging with multiphoton microscopy has had a major impact on kidney research. It provides the unique opportunity to visualize dynamic behavior of cells and organelles in their native environment and to relate this to the complex 3-dimensional structure of the organ. Moreover, changes in cell/organelle function can be followed in real time in response to physiological interventions or disease-causing insults. However, realizing the enormous potential of this exciting approach has necessitated overcoming several substantial practical hurdles. In this article, we outline the nature of these challenges and how a variety of technical advances have provided effective solutions. In particular, improvements in laser/microscope technology, fluorescent probes, transgenic animals, and abdominal windows are collectively making previously opaque processes visible. Meanwhile, the rise of machine learning-based image analysis is facilitating the rapid generation of large amounts of quantitative data, amenable to deeper statistical interrogation. Taken together, the increased capabilities of multiphoton imaging are opening up huge new possibilities to study structure-function relationships in the kidney in unprecedented detail. In addition, they are yielding important new insights into cellular mechanisms of tissue damage, repair, and adaptive remodeling during disease states. Thus, intravital microscopy is truly entering an exciting new era in translational kidney research.
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Affiliation(s)
- Joana R Martins
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Dominik Haenni
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland; Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Milica Bugarski
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | | | - Claus Schuh
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; Department of Nephrology, University Hospital Zurich, Zurich, Switzerland.
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5
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Abstract
Renal epithelial cells show remarkable regenerative capacity to recover from acute injury, which involves specific phenotypic changes, but also significant profibrotic tubule-interstitial crosstalk. Tubule-derived profibrotic stimuli and subsequent myofibroblast activation and extracellular matrix deposition have been linked closely with decline of renal function and nephron loss. However, recent data have questioned the view of purely detrimental effects of myofibroblast activation in the injured kidney and even suggested its beneficial role for epithelial regeneration. This article reviews the current understanding of the underlying mechanisms of tubular cell turnover, new suggested pathways of proregenerative tubular-interstitial crosstalk, and relevant insights of proliferation-enhancing effects of myofibroblasts on epithelial cells in nonrenal tissues.
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6
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Koike Y, Li B, Chen Y, Ganji N, Alganabi M, Miyake H, Lee C, Hock A, Wu R, Uchida K, Inoue M, Delgado-Olguin P, Pierro A. Live Intravital Intestine with Blood Flow Visualization in Neonatal Mice Using Two-photon Laser Scanning Microscopy. Bio Protoc 2021; 11:e3937. [PMID: 33796611 DOI: 10.21769/bioprotoc.3937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 11/02/2022] Open
Abstract
This protocol describes a novel technique to investigate the microcirculation dynamics underlying the pathology in the small intestine of neonatal mice using two-photon laser-scanning microscopy (TPLSM). Recent technological advances in multi-photon microscopy allow intravital analysis of different organs such as the liver, brain and intestine. Despite these advances, live visualization and analysis of the small intestine in neonatal rodents remain technically challenging. We herein provide a detailed description of a novel method to capture high resolution and stable images of the small intestine in neonatal mice as early as postnatal day 0. This imaging technique allows a comprehensive understanding of the development and blood flow dynamics in small intestine microcirculation.
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Affiliation(s)
- Yuhki Koike
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada.,Department of Gastrointestinal and Pediatric Surgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Bo Li
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Yong Chen
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Niloofar Ganji
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Mashriq Alganabi
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Hiromu Miyake
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Carol Lee
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Alison Hock
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Richard Wu
- Division of Gastroenterology, Hepatology and Nutrition, The Hospital for Sick Children, Toronto, ON, Canada
| | - Keiichi Uchida
- Department of Gastrointestinal and Pediatric Surgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Mikihiro Inoue
- Department of Gastrointestinal and Pediatric Surgery, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Paul Delgado-Olguin
- Translational Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.,Heart & Stroke Richard Lewar Centre of Excellence, Toronto, Ontario, Canada
| | - Agostino Pierro
- Division of General and Thoracic Surgery, Physiology and Experimental Medicine Program, The Hospital for Sick Children, Toronto, ON, Canada
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7
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Ranjit S, Lanzanò L, Libby AE, Gratton E, Levi M. Advances in fluorescence microscopy techniques to study kidney function. Nat Rev Nephrol 2020; 17:128-144. [PMID: 32948857 DOI: 10.1038/s41581-020-00337-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/30/2020] [Indexed: 02/07/2023]
Abstract
Fluorescence microscopy, in particular immunofluorescence microscopy, has been used extensively for the assessment of kidney function and pathology for both research and diagnostic purposes. The development of confocal microscopy in the 1950s enabled imaging of live cells and intravital imaging of the kidney; however, confocal microscopy is limited by its maximal spatial resolution and depth. More recent advances in fluorescence microscopy techniques have enabled increasingly detailed assessment of kidney structure and provided extraordinary insights into kidney function. For example, nanoscale precise imaging by rapid beam oscillation (nSPIRO) is a super-resolution microscopy technique that was originally developed for functional imaging of kidney microvilli and enables detection of dynamic physiological events in the kidney. A variety of techniques such as fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS) and Förster resonance energy transfer (FRET) enable assessment of interaction between proteins. The emergence of other super-resolution techniques, including super-resolution stimulated emission depletion (STED), photoactivated localization microscopy (PALM), stochastic optical reconstruction microscopy (STORM) and structured illumination microscopy (SIM), has enabled functional imaging of cellular and subcellular organelles at ≤50 nm resolution. The deep imaging via emission recovery (DIVER) detector allows deep, label-free and high-sensitivity imaging of second harmonics, enabling assessment of processes such as fibrosis, whereas fluorescence lifetime imaging microscopy (FLIM) enables assessment of metabolic processes.
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Affiliation(s)
- Suman Ranjit
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA. .,Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Luca Lanzanò
- Nanoscopy and NIC@IIT, Istituto Italiano di Tecnologia, Genoa, Italy.,Department of Physics and Astronomy "Ettore Majorana", University of Catania, Catania, Italy
| | - Andrew E Libby
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California, Irvine, CA, USA.
| | - Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC, USA.
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8
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Ghazi S, Bourgeois S, Gomariz A, Bugarski M, Haenni D, Martins JR, Nombela-Arrieta C, Unwin RJ, Wagner CA, Hall AM, Craigie E. Multiparametric imaging reveals that mitochondria-rich intercalated cells in the kidney collecting duct have a very high glycolytic capacity. FASEB J 2020; 34:8510-8525. [PMID: 32367531 DOI: 10.1096/fj.202000273r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/30/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023]
Abstract
Alpha intercalated cells (αICs) in the kidney collecting duct (CD) belong to a family of mitochondria rich cells (MRCs) and have a crucial role in acidifying the urine via apical V-ATPase pumps. The nature of metabolism in αICs and its relationship to transport was not well-understood. Here, using multiphoton live cell imaging in mouse kidney tissue, FIB-SEM, and other complementary techniques, we provide new insights into mitochondrial structure and function in αICs. We show that αIC mitochondria have a rounded structure and are not located in close proximity to V-ATPase containing vesicles. They display a bright NAD(P)H fluorescence signal and low uptake of voltage-dependent dyes, but are energized by a pH gradient. However, expression of complex V (ATP synthase) is relatively low in αICs, even when stimulated by metabolic acidosis. In contrast, anaerobic glycolytic capacity is surprisingly high, and sufficient to maintain intracellular calcium homeostasis in the presence of complete aerobic inhibition. Moreover, glycolysis is essential for V-ATPase-mediated proton pumping. Key findings were replicated in narrow/clear cells in the epididymis, also part of the MRC family. In summary, using a range of cutting-edge techniques to investigate αIC metabolism in situ, we have discovered that these mitochondria dense cells have a high glycolytic capacity.
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Affiliation(s)
- Susan Ghazi
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Alvaro Gomariz
- Department of Medical Oncology and Hematology, University of Zurich, Zurich, Switzerland.,Computer Vision Laboratory, ETH Zurich, Zurich, Switzerland
| | - Milica Bugarski
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Dominik Haenni
- Institute of Anatomy, University of Zurich, Zurich, Switzerland.,Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Joana R Martins
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - César Nombela-Arrieta
- Department of Medical Oncology and Hematology, University of Zurich, Zurich, Switzerland
| | - Robert J Unwin
- Department of Renal Medicine, University College London, UK.,AstraZeneca Biopharmaceuticals R&D, Gothenburg, Sweden
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland.,Department of Nephrology, University Hospital Zurich, Switzerland
| | - Eilidh Craigie
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
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9
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BENZING THOMAS. MOLECULAR DESIGN OF THE KIDNEY FILTRATION BARRIER. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2020; 131:125-139. [PMID: 32675853 PMCID: PMC7358502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Kidneys are the central regulators of organismal homeostasis. These organs filter enormous amounts of fluid from plasma; excrete toxic waste products; maintain salt, water, and volume balance; coordinate blood pressure regulation; and maintain the acid-base equilibrium essential for life. Although it has been known for decades that renal glomeruli serve as the site of plasma ultrafiltration and urine production, both the molecular design and function of the kidney filtration barrier have remained elusive. Indeed, the past two decades have witnessed enormous breakthroughs in our fundamental understanding of kidney filtration and the critical role that podocytes, specialized terminally differentiated epithelial cells at the glomerular capillaries, fulfill in the function of the kidney filtration barrier. Here we discuss recent advances in this field that will change the way we think about plasma ultrafiltration in health and proteinuria as a manifestation of glomerular diseases.
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Affiliation(s)
- THOMAS BENZING
- Correspondence and reprint requests: Thomas Benzing, MD, Department II of Internal Medicine, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany+ 49 221 4784480, 49 221 4785959
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10
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Ferrell N, Sandoval RM, Molitoris BA, Brakeman P, Roy S, Fissell WH. Application of physiological shear stress to renal tubular epithelial cells. Methods Cell Biol 2019; 153:43-67. [PMID: 31395384 DOI: 10.1016/bs.mcb.2019.04.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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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11
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Shroff UN, Schiessl IM, Gyarmati G, Riquier-Brison A, Peti-Peterdi J. Novel fluorescence techniques to quantitate renal cell biology. Methods Cell Biol 2019; 154:85-107. [PMID: 31493823 PMCID: PMC6748388 DOI: 10.1016/bs.mcb.2019.04.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Fluorescence microscopy techniques are powerful tools to study tissue dynamics, cellular function and biology both in vivo and in vitro. These tools allow for functional assessment and quantification along with qualitative analysis, thus providing a comprehensive understanding of various cellular processes under normal physiological and disease conditions. The main focus of this chapter is the recently developed method of serial intravital multiphoton microscopy that has helped shed light on the dynamic alterations of the spatial distribution and fate of single renal cells or cell populations and their migration patterns in the same tissue region over several days in response to various stimuli within the living kidney. This technique is very useful for studying in vivo the molecular and cellular mechanisms of tissue remodeling and repair after injury. In addition, complementary in vitro imaging tools are also described and discussed, like tissue clearing techniques and protein synthesis measurement in tissues in situ that provide an in depth assessment of changes at the cellular level. Thus, these novel fluorescence techniques can be effectively leveraged for different tissue types, experimental conditions as well as disease models to improve our understanding of renal cell biology.
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Affiliation(s)
- Urvi Nikhil Shroff
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Ina Maria Schiessl
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Georgina Gyarmati
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Anne Riquier-Brison
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Janos Peti-Peterdi
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
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12
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Gyarmati G, Kadoya H, Moon JY, Burford JL, Ahmadi N, Gill IS, Hong YK, Dér B, Peti-Peterdi J. Advances in Renal Cell Imaging. Semin Nephrol 2019; 38:52-62. [PMID: 29291762 DOI: 10.1016/j.semnephrol.2017.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A great variety of cell imaging technologies are used routinely every day for the investigation of kidney cell types in applications ranging from basic science research to drug development and pharmacology, clinical nephrology, and pathology. Quantitative visualization of the identity, density, and fate of both resident and nonresident cells in the kidney, and imaging-based analysis of their altered function, (patho)biology, metabolism, and signaling in disease conditions, can help to better define pathomechanism-based disease subgroups, identify critical cells and structures that play a role in the pathogenesis, critically needed biomarkers of disease progression, and cell and molecular pathways as targets for novel therapies. Overall, renal cell imaging has great potential for improving the precision of diagnostic and treatment paradigms for individual acute kidney injury or chronic kidney disease patients or patient populations. This review highlights and provides examples for some of the recently developed renal cell optical imaging approaches, mainly intravital multiphoton fluorescence microscopy, and the new knowledge they provide for our better understanding of renal pathologies.
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Affiliation(s)
- Georgina Gyarmati
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Hiroyuki Kadoya
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA; Department of Nephrology and Hypertension, Kawasaki Medical School, Kurashiki, Japan
| | - Ju-Young Moon
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA; Division of Nephrology, Department of Internal Medicine, Kyung Hee University, College of Medicine, Seoul, Korea
| | - James L Burford
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Nariman Ahmadi
- Institute of Urology, Catherine & Joseph Aresty Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Inderbir S Gill
- Institute of Urology, Catherine & Joseph Aresty Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Young-Kwon Hong
- Department of Surgery and Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Bálint Dér
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - János Peti-Peterdi
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.
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13
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Schiessl IM, Fremter K, Burford JL, Castrop H, Peti-Peterdi J. Long-Term Cell Fate Tracking of Individual Renal Cells Using Serial Intravital Microscopy. Methods Mol Biol 2019; 2150:25-44. [PMID: 31087287 DOI: 10.1007/7651_2019_232] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intravital multiphoton microscopy of the kidney is a powerful technique to study alterations in tissue morphology and function simultaneously in the living animal and represents a dynamic and developing research tool in the field. Recent technological advances include serial intravital multiphoton microscopy of the same kidney regions over several weeks and combined with ex vivo histology for cellular biomarker expression of the same cells, which had been subject to serial imaging before. Thus, serial intravital multiphoton microscopy followed by ex vivo histology provides unique tools to perform long-term cell fate tracing of the same renal cells during physiological and pathophysiological conditions, thereby allowing the detection of structural changes of the same renal cells over time. Examples include renal cell migration and proliferation while linking these events to local functional alterations and eventually to the expression of distinct cellular biomarkers. Here, we provide a detailed step-by-step protocol to facilitate serial intravital multiphoton microscopy for long-term in vivo tracking of renal cells and subsequent ex vivo histology for immunohistological staining of the same cells in the fixed tissue.
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Affiliation(s)
- Ina Maria Schiessl
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
| | - Katharina Fremter
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - James L Burford
- Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Janos Peti-Peterdi
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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14
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Lin TC, Liao YC, Chang WT, Yang CH, Cheng LH, Cheng M, Cheng HC. The Establishment of a Lung Colonization Assay for Circulating Tumor Cell Visualization in Lung Tissues. J Vis Exp 2018. [PMID: 29985344 DOI: 10.3791/56761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Metastasis is the major cause of cancer death. The role of circulating tumor cells (CTCs) in promoting cancer metastasis, in which lung colonization by CTCs critically contributes to early lung metastatic processes, has been vigorously investigated. As such, animal models are the only approach that captures the full systemic process of metastasis. Given that problems occur in previous experimental designs for examining the contributions of CTCs to blood vessel extravasation, we established an in vivo lung colonization assay in which a long-term-fluorescence cell-tracer, carboxyfluorescein succinimidyl ester (CFSE), was used to label suspended tumor cells and lung perfusion was performed to clear non-specifically trapped CTCs prior to lung removal, confocal imaging, and quantification. Polymeric fibronectin (polyFN) assembled on CTC surfaces has been found to mediate lung colonization in the final establishment of metastatic tumor tissues. Here, to specifically test the requirement of polyFN assembly on CTCs for lung colonization and extravasation, we performed short term lung colonization assays in which suspended Lewis lung carcinoma cells (LLCs) stably expressing FN-shRNA (shFN) or scramble-shRNA (shScr) and pre-labeled with 20 μM of CFSE were intravenously inoculated into C57BL/6 mice. We successfully demonstrated that the abilities of shFN LLC cells to colonize the mouse lungs were significantly diminished in comparison to shScr LLC cells. Therefore, this short-term methodology may be widely applied to specifically demonstrate the ability of CTCs within the circulation to colonize the lungs.
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Affiliation(s)
- Tsung-Cheng Lin
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University
| | - Ying-Chih Liao
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University
| | - Wen-Tsan Chang
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University; Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University
| | - Cheng-Han Yang
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University
| | - Li-Hsin Cheng
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University
| | - Megan Cheng
- Trauma Office, Children's National Health System
| | - Hung-Chi Cheng
- The Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University; Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University;
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Dunn KW, Sutton TA, Sandoval RM. Live-Animal Imaging of Renal Function by Multiphoton Microscopy. ACTA ACUST UNITED AC 2018; 83:12.9.1-12.9.25. [PMID: 29345326 DOI: 10.1002/cpcy.32] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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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16
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Abstract
Kidney cell death plays a key role in the progression of life-threatening renal diseases, such as acute kidney injury and chronic kidney disease. Injured and dying epithelial and endothelial cells take part in complex communication with the innate immune system, which drives the progression of cell death and the decrease in renal function. To improve our understanding of kidney cell death dynamics and its impact on renal disease, a study approach is needed that facilitates the visualization of renal function and morphology in real time. Intravital multiphoton microscopy of the kidney has been used for more than a decade and made substantial contributions to our understanding of kidney physiology and pathophysiology. It is a unique tool that relates renal structure and function in a time- and spatial-dependent manner. Basic renal function, such as microvascular blood flow regulation and glomerular filtration, can be determined in real time and homeostatic alterations, which are linked inevitably to cell death and can be depicted down to the subcellular level. This review provides an overview of the available techniques to study kidney dysfunction and inflammation in terms of cell death in vivo, and addresses how this novel approach can be used to improve our understanding of cell death dynamics in renal disease.
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17
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Combined use of electron microscopy and intravital imaging captures morphological and functional features of podocyte detachment. Pflugers Arch 2017; 469:965-974. [PMID: 28664407 DOI: 10.1007/s00424-017-2020-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 12/12/2022]
Abstract
The development of podocyte injury and albuminuria in various glomerular pathologies is still incompletely understood due to technical limitations in studying the glomerular filtration barrier (GFB) in real-time. We aimed to directly visualize the early morphological and functional changes of the GFB during the development of focal segmental glomerulosclerosis (FSGS) using a combination of transmission electron microscopy (TEM) and in vivo multiphoton microscopy (MPM) in the rat puromycin aminonucleoside (PAN) model. We hypothesized that this combined TEM + MPM experimental approach would provide a major technical improvement that would benefit our mechanistic understanding of podocyte detachment. Male Sprague-Dawley (for TEM) or Munich-Wistar-Frömter (for MPM) rats were given a single dose of 100-150 mg/kg body weight PAN i.p. and were either sacrificed and the kidneys processed for TEM or surgically instrumented for in vivo MPM imaging at various times 2-14 days after PAN administration. Both techniques demonstrated hypertrophy and cystic dilatations of the subpodocyte space that developed as early as 2-3 days after PAN. Adhesions of the visceral epithelium to the parietal Bowman's capsule (synechiae) appeared at days 8-10. TEM provided unmatched resolution of podocyte foot process remodeling, while MPM revealed the rapid dynamics of pseudocyst filling, emptying, and rupture, as well as endothelial and podocyte injury, misdirected filtration, and podocyte shedding. Due to the complementary advantages of TEM and MPM, this combined approach can provide an unusally comprehensive and dynamic portrayal of the alterations in podocyte morphology and function during FSGS development. The results advance our understanding of the role and importance of the various cell types, hemodynamics, and mechanical forces in the development of glomerular pathology.
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18
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Hall AM, Schuh CD, Haenni D. New frontiers in intravital microscopy of the kidney. Curr Opin Nephrol Hypertens 2017; 26:172-178. [DOI: 10.1097/mnh.0000000000000313] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Khosroshahi HT, Abedi B, Daneshvar S, Sarbaz Y, Shakeri Bavil A. Future of the Renal Biopsy: Time to Change the Conventional Modality Using Nanotechnology. Int J Biomed Imaging 2017; 2017:6141734. [PMID: 28316612 PMCID: PMC5337808 DOI: 10.1155/2017/6141734] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/20/2016] [Accepted: 01/05/2017] [Indexed: 12/19/2022] Open
Abstract
At the present time, imaging guided renal biopsy is used to provide diagnoses in most types of primary and secondary renal diseases. It has been claimed that renal biopsy can provide a link between diagnosis of renal disease and its pathological conditions. However, sometimes there is a considerable mismatch between patient renal outcome and pathological findings in renal biopsy. This is the time to address some new diagnostic methods to resolve the insufficiency of conventional percutaneous guided renal biopsy. Nanotechnology is still in its infancy in renal imaging; however, it seems that it is the next step in renal biopsy, providing solutions to the limitations of conventional modalities.
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Affiliation(s)
| | - Behzad Abedi
- Medical Bioengineering Department, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Sabalan Daneshvar
- Medical Bioengineering Department, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
- Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran
| | - Yashar Sarbaz
- School of Engineering-Emerging Technologies, University of Tabriz, Tabriz, Iran
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Abstract
PURPOSE OF REVIEW The review aims to provide a brief summary and evaluation of the current state of research that uses multiphoton fluorescence microscopy for intravital kidney imaging. RECENT FINDINGS Direct visualization of the glomerular filter, proximal and distal tubule segments, and the renal vasculature in the living, intact kidney in zebrafish, mouse, and rat models with high temporal and spatial resolution provided new insights into the function of the normal and diseased kidney. New technical developments in fluorescence excitation and detection, in combination with transgenic animal models for cell function and fate mapping, and serial imaging of the same glomerulus in the same animal over several days further advanced the field of nephrology research, and the understanding of disease mechanisms. SUMMARY Intravital multiphoton imaging has solved many critical technical barriers in kidney research and allowed the dynamic portrayal of the structure and function of various renal cell types in vivo. It has become a widely used research technique, with significant past achievements, and tremendous potential for future development and applications for the study and better understanding of kidney diseases.
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21
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Calcineurin-inhibition Results in Upregulation of Local Renin and Subsequent Vascular Endothelial Growth Factor Production in Renal Collecting Ducts. Transplantation 2016; 100:325-333. [PMID: 26502369 DOI: 10.1097/tp.0000000000000961] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Tacrolimus (Tac) and Cyclosporine A (CyA) calcineurin inhibitors (CNIs) are 2 effective immunosuppressants which are essential to prevent allograft rejection. Calcineurin inhibitors are known to be nephrotoxic. However, the precise mechanism of nephrotoxicity is not fully understood. In this study, we investigated the in vivo effects of CNIs on the local renal renin-angiotensin system in the collecting duct (CD). METHODS Three-week-old mice were treated with either vehicle, CyA (2 mg/kg per day), Tac (0.075 mg/kg per day), CyA + Aliskiren (25 mg/kg per day), or Tac + Aliskiren for 3 weeks. Serum creatinine was measured. Renin and vascular endothelial growth factor (VEGF) contents in CD were evaluated with flow cytometry and multiphoton microscopy. The diameter of vessels was assessed with multiphoton microscopy, and the amount of renal collagen was determined by real-time polymerase chain reaction and Masson staining. RESULTS The elevated level of serum creatinine in CNI groups was abolished by Aliskiren. Flow cytometric analysis found elevated renin content in principal cells, which was prevented by Aliskiren. This result was further confirmed with multiphoton microscopy. The VEGF content in CD correlated with reduced capillary diameter and with the formation of fibrotic islands. CONCLUSIONS Calcineurin inhibitors induce production of renin in the CD that may contribute to decreased renal blood flow. In turn, CD responds with increased VEGF production, resulting in disproportional vessel growth, further worsening the local hypoxia and striped fibrosis surrounding the CDs. Aliskiren, a direct renin inhibitor blocks these effects and improves CNI-induced nephropathy by decreasing renin production in the CDs. Our data suggest that Aliskiren may be used for the prevention of CNI nephrotoxicity.
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Schießl IM, Castrop H. Deep insights: intravital imaging with two-photon microscopy. Pflugers Arch 2016; 468:1505-16. [PMID: 27352273 DOI: 10.1007/s00424-016-1832-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 04/26/2016] [Indexed: 01/03/2023]
Abstract
Intravital multiphoton microscopy is widely used to assess the structure and function of organs in live animals. Although different tissues vary in their accessibility for intravital multiphoton imaging, considerable progress has been made in the imaging quality of all tissues due to substantial technical improvements in the relevant imaging components, such as optics, excitation laser, detectors, and signal analysis software. In this review, we provide an overview of the technical background of intravital multiphoton microscopy. Then, we note a few seminal findings that were made through the use of multiphoton microscopy. Finally, we address the technical limitations of the method and provide an outlook for how these limitations may be overcome through future technical developments.
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Affiliation(s)
- Ina Maria Schießl
- Institute of Physiology, University of Regensburg, Universitätsstr. 31, 93040, Regensburg, Germany.
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Universitätsstr. 31, 93040, Regensburg, Germany
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23
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Abstract
This article summarizes the past, present, and future promise of multiphoton excitation fluorescence microscopy for intravital kidney imaging. During the past 15years, several high-power visual research approaches have been developed using multiphoton imaging to study the normal functions of the healthy, intact, living kidney, and the various molecular and cellular mechanisms of the development of kidney diseases. In this review, the main focus will be on intravital multiphoton imaging of the glomerulus, the structure and function of the glomerular filtration barrier, especially the podocyte. Examples will be given for the combination of two powerful research tools, in vivo multiphoton imaging and mouse genetics using commercially available whole animal models for the detailed characterization of glomerular cell types, their function and fate, and for the better understanding of the molecular mechanisms of glomerular pathologies. One of the new modalities of multiphoton imaging, serial imaging of the same glomerulus in the same animal over several days will be emphasized for its potential for further advancing the field of nephrology research.
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Affiliation(s)
- János Peti-Peterdi
- Departments of Physiology and Biophysics, and Medicine, Zilkha Neurogenetic Institute, ZNI355, University of Southern California, 1501 San Pablo Street, Los Angeles, CA 90033, USA.
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24
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Schuh C, Haenni D, Craigie E, Ziegler U, Weber B, Devuyst O, Hall AM. Long wavelength multiphoton excitation is advantageous for intravital kidney imaging. Kidney Int 2016; 89:712-9. [DOI: 10.1038/ki.2015.323] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/14/2015] [Accepted: 09/03/2015] [Indexed: 11/09/2022]
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25
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Torres R, Velazquez H, Chang JJ, Levene MJ, Moeckel G, Desir GV, Safirstein R. Three-Dimensional Morphology by Multiphoton Microscopy with Clearing in a Model of Cisplatin-Induced CKD. J Am Soc Nephrol 2015; 27:1102-12. [PMID: 26303068 DOI: 10.1681/asn.2015010079] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 07/09/2015] [Indexed: 11/03/2022] Open
Abstract
Traditional histologic methods are limited in their ability to detect pathologic changes of CKD, of which cisplatin therapy is an important cause. In addition, poor reproducibility of available methods has limited analysis of the role of fibrosis in CKD. Highly labor-intensive serial sectioning studies have demonstrated that three-dimensional perspective can reveal useful morphologic information on cisplatin-induced CKD. By applying the new technique of multiphoton microscopy (MPM) with clearing to a new mouse model of cisplatin-induced CKD, we obtained detailed morphologic and collagen reconstructions of millimeter-thick renal sections that provided new insights into pathophysiology. Quantitative analysis revealed that a major long-term cisplatin effect is reduction in the number of cuboidal cells of the glomerular capsule, a change we term the "uncapped glomerulus lesion." Glomerulotubular disconnection was confirmed, but connection remnants between damaged tubules and atubular glomeruli were observed. Reductions in normal glomerular capsules corresponded to reductions in GFR. Mild increases in collagen were noted, but the fibrosis was not spatially correlated with atubular glomeruli. Glomerular volume and number remained unaltered with cisplatin exposure, but cortical tubulointerstitial mass decreased. In conclusion, new observations were made possible by using clearing MPM, demonstrating the utility of this technique for studies of renal disease. This technique should prove valuable for further characterizing the evolution of CKD with cisplatin therapy and of other conditions.
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Affiliation(s)
| | - Heino Velazquez
- Department of Nephrology, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut; and Department of Internal Medicine, and
| | - John J Chang
- Department of Nephrology, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut; and Department of Internal Medicine, and
| | | | - Gilbert Moeckel
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut
| | - Gary V Desir
- Department of Nephrology, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut; and Department of Internal Medicine, and
| | - Robert Safirstein
- Department of Nephrology, Veterans Affairs Connecticut Healthcare System, West Haven, Connecticut; and Department of Internal Medicine, and
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Brähler S, Ising C, Barrera Aranda B, Höhne M, Schermer B, Benzing T, Brinkkoetter PT. The NF-κB essential modulator (NEMO) controls podocyte cytoskeletal dynamics independently of NF-κB. Am J Physiol Renal Physiol 2015; 309:F617-26. [PMID: 26268269 DOI: 10.1152/ajprenal.00059.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 08/05/2015] [Indexed: 01/01/2023] Open
Abstract
Maintenance of the glomerular filtration barrier with its fenestrated endothelium, the glomerular basement membrane, and the podocytes as the outer layer, is a major prerequisite for proper renal function. Tight regulation of the balance between plasticity and rigidity of the podocytes' architecture is required to prevent the onset of glomerular disease, mainly proteinuria. The underlying cellular signaling pathways that regulate the organization of the podocytes' cytoskeleton are still a matter of controversial debate. In this study, we investigated the role of the NF-κB signaling pathway in podocyte cytoskeletal dynamics. As previously published, genetic inhibition of the NF-κB essential modulator (NEMO) in podocytes does not affect glomerular function under physiological, nonstressed conditions nor does it alter the initial podocyte response in an experimental glomerulonephritis (NTN) model (Brähler S, Ising C, Hagmann H, Rasmus M, Hoehne M, Kurschat C, Kisner T, Goebel H, Shankland SJ, Addicks K, Thaiss F, Schermer B, Pasparakis M, Benzing T, Brinkkoetter PT. Am J Physiol Renal Physiol 303: F1473-F1475, 2012). Quite the contrary, podocyte-specific NEMO null mice recovered significantly faster and did not develop glomerulosclerosis and end-stage renal failure over time. Here, we show that cytoskeletal rearrangements and increased podocyte motility following stimulation with IL-1, TNF-α, or LPS depend on NEMO. NEMO also regulates the phosphorylation of the MAP kinase ERK1/2 and suppresses the activation of RhoA following stimulation with IL-1. The migratory response and altered ERK1/2 phosphorylation is independent of NF-κB signaling as demonstrated by expression of a mutant IκB resistant to phosphorylation and degradation. In conclusion, signaling through NEMO might not only be involved in the production of NF-κB proinflammatory chemokines but also regulates podocyte dynamics independently of NF-κB, most likely through small GTPases and MAP kinases.
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Affiliation(s)
- Sebastian Brähler
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Christina Ising
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Belén Barrera Aranda
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases, University of Cologne, Cologne, Germany; and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases, University of Cologne, Cologne, Germany; and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing-Associated Diseases, University of Cologne, Cologne, Germany; and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Paul Thomas Brinkkoetter
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany;
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Hall AM, Molitoris BA. Dynamic multiphoton microscopy: focusing light on acute kidney injury. Physiology (Bethesda) 2015; 29:334-42. [PMID: 25180263 DOI: 10.1152/physiol.00010.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Acute kidney injury (AKI) is a major global health problem; much research has been conducted on AKI, and numerous agents have shown benefit in animal studies, but none have translated into treatments. There is, therefore, a pressing unmet need to increase knowledge of the pathophysiology of AKI. Multiphoton microscopy (MPM) provides a tool to non-invasively visualize dynamic events in real time and at high resolution in rodent kidneys, and in this article we review its application to study novel mechanisms and treatments in different forms of AKI.
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Affiliation(s)
- Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Bruce A Molitoris
- Indiana University School of Medicine, Indiana Center for Biological Microscopy, Indianapolis, Indiana
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28
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Novel in vivo techniques to visualize kidney anatomy and function. Kidney Int 2015; 88:44-51. [PMID: 25738253 PMCID: PMC4490063 DOI: 10.1038/ki.2015.65] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/05/2015] [Accepted: 01/06/2015] [Indexed: 12/11/2022]
Abstract
Intravital imaging using multiphoton microscopy (MPM) has become an increasingly popular and widely used experimental technique in kidney research over the past few years. MPM allows deep optical sectioning of the intact, living kidney tissue with submicron resolution which is unparalleled among intravital imaging approaches. MPM has solved a long-standing critical technical barrier in renal research to study several complex and inaccessible cell types and anatomical structures in vivo in their native environment. Comprehensive and quantitative kidney structure and function MPM studies helped our better understanding of the cellular and molecular mechanisms of the healthy and diseased kidney. This review summarizes recent in vivo MPM studies with a focus on the glomerulus and the filtration barrier, although select, glomerulus-related renal vascular and tubular functions are also mentioned. The latest applications of serial MPM of the same glomerulus in vivo, in the intact kidney over several days, during the progression of glomerular disease are discussed. This visual approach, in combination with genetically encoded fluorescent markers of cell lineage, has helped to track the fate and function (e.g. cell calcium changes) of single podocytes during the development of glomerular pathologies, and provided visual proof for the highly dynamic rather than static nature of the glomerular environment. Future intravital imaging applications have the promise to further push the limits of optical microscopy, and to advance our understanding of the mechanisms of kidney injury. Also, MPM will help to study new mechanisms of tissue repair and regeneration, a cutting edge area of kidney research.
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29
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Schießl IM, Kattler V, Castrop H. In Vivo Visualization of the Antialbuminuric Effects of the Angiotensin-Converting Enzyme Inhibitor Enalapril. J Pharmacol Exp Ther 2015; 353:299-306. [DOI: 10.1124/jpet.114.222125] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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30
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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] [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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31
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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] [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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32
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Brasen JC, Burford JL, McDonough AA, Holstein-Rathlou NH, Peti-Peterdi J. Local pH domains regulate NHE3-mediated Na⁺ reabsorption in the renal proximal tubule. Am J Physiol Renal Physiol 2014; 307:F1249-62. [PMID: 25298526 DOI: 10.1152/ajprenal.00174.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The proximal tubule Na(+)/H(+) exchanger 3 (NHE3), located in the apical dense microvilli (brush border), plays a major role in the reabsorption of NaCl and water in the renal proximal tubule. In response to a rise in blood pressure NHE3 redistributes in the plane of the plasma membrane to the base of the brush border, where NHE3 activity is reduced. This NHE3 redistribution is assumed to provoke pressure natriuresis; however, it is unclear how NHE3 redistribution per se reduces NHE3 activity. To investigate if the distribution of NHE3 in the brush border can change the reabsorption rate, we constructed a spatiotemporal mathematical model of NHE3-mediated Na(+) reabsorption across a proximal tubule cell and compared the model results with in vivo experiments in rats. The model predicts that when NHE3 is localized exclusively at the base of the brush border, it creates local pH microdomains that reduce NHE3 activity by >30%. We tested the model's prediction experimentally: the rat kidney cortex was loaded with the pH-sensitive fluorescent dye BCECF, and cells of the proximal tubule were imaged in vivo using confocal fluorescence microscopy before and after an increase of blood pressure by ∼50 mmHg. The experimental results supported the model by demonstrating that a rise of blood pressure induces the development of pH microdomains near the bottom of the brush border. These local changes in pH reduce NHE3 activity, which may explain the pressure natriuresis response to NHE3 redistribution.
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Affiliation(s)
- Jens Christian Brasen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Biomedical Engineering, Department of Electrical Engineering, Technical University of Denmark, Lyngby, Denmark; and
| | - James L Burford
- Departments of Physiology and Biophysics and Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California; and
| | - Alicia A McDonough
- Department of Cell and Neurobiology, University of Southern California, Los Angeles, California
| | | | - Janos Peti-Peterdi
- Departments of Physiology and Biophysics and Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California; and
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Peti-Peterdi J, Burford JL, Hackl MJ. Can kidney regeneration be visualized? Nephron Clin Pract 2014; 126:86. [PMID: 24854647 DOI: 10.1159/000360673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Various cell types, including podocytes and parietal epithelial cells, play important roles in the development and progression of glomerular kidney diseases, albuminuria, and glomerulosclerosis. Besides their role in renal pathologies, glomerular cells have emerging new functions in endogenous repair mechanisms. A better understanding of the dynamics of the glomerular environment and cellular composition in an intact living kidney is critically important for the development of new regenerative therapeutic strategies for kidney diseases. However, progress in this field has been hampered by the lack of in vivo research tools. SUMMARY This review summarizes the current state-of-the-art in the application of the unique intravital imaging technology of multiphoton fluorescence microscopy for the dynamic visualization of glomerular structure and function over time in the intact, living kidney. Recently, this imaging approach in combination with transgenic mouse models allowed tracking of the fate of individual glomerular cells in vivo over several days and depicted the highly dynamic nature of the glomerular environment, particularly in disease conditions. KEY MESSAGES The technology is ready and available for future intravital imaging studies investigating new glomerular regenerative approaches in animal models.
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Affiliation(s)
- János Peti-Peterdi
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, Calif., USA
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Burford JL, Villanueva K, Lam L, Riquier-Brison A, Hackl MJ, Pippin J, Shankland SJ, Peti-Peterdi J. Intravital imaging of podocyte calcium in glomerular injury and disease. J Clin Invest 2014; 124:2050-8. [PMID: 24713653 DOI: 10.1172/jci71702] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 02/20/2014] [Indexed: 11/17/2022] Open
Abstract
Intracellular calcium ([Ca²⁺]i) signaling mediates physiological and pathological processes in multiple organs, including the renal podocyte; however, in vivo podocyte [Ca²⁺]i dynamics are not fully understood. Here we developed an imaging approach that uses multiphoton microscopy (MPM) to directly visualize podocyte [Ca²⁺]i dynamics within the intact kidneys of live mice expressing a fluorescent calcium indicator only in these cells. [Ca²⁺]i was at a low steady-state level in control podocytes, while Ang II infusion caused a minor elevation. Experimental focal podocyte injury triggered a robust and sustained elevation of podocyte [Ca²⁺]i around the injury site and promoted cell-to-cell propagating podocyte [Ca²⁺]i waves along capillary loops. [Ca²⁺]i wave propagation was ameliorated by inhibitors of purinergic [Ca²⁺]i signaling as well as in animals lacking the P2Y2 purinergic receptor. Increased podocyte [Ca²⁺]i resulted in contraction of the glomerular tuft and increased capillary albumin permeability. In preclinical models of renal fibrosis and glomerulosclerosis, high podocyte [Ca²⁺]i correlated with increased cell motility. Our findings provide a visual demonstration of the in vivo importance of podocyte [Ca²⁺]i in glomerular pathology and suggest that purinergic [Ca²⁺]i signaling is a robust and key pathogenic mechanism in podocyte injury. This in vivo imaging approach will allow future detailed investigation of the molecular and cellular mechanisms of glomerular disease in the intact living kidney.
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Kistler AD, Caicedo A, Abdulreda MH, Faul C, Kerjaschki D, Berggren PO, Reiser J, Fornoni A. In vivo imaging of kidney glomeruli transplanted into the anterior chamber of the mouse eye. Sci Rep 2014; 4:3872. [PMID: 24464028 PMCID: PMC3902446 DOI: 10.1038/srep03872] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 12/09/2013] [Indexed: 11/24/2022] Open
Abstract
Multiphoton microscopy enables live imaging of the renal glomerulus. However, repeated in vivo imaging of the same glomerulus over extended periods of time and the study of glomerular function independent of parietal epithelial and proximal tubular cell effects has not been possible so far. Here, we report a novel approach for non-invasive imaging of acapsular glomeruli transplanted into the anterior chamber of the mouse eye. After microinjection, glomeruli were capable of engrafting on the highly vascularized iris. Glomerular structure was preserved, as demonstrated by podocyte specific expression of cyan fluorescent protein and by electron microscopy. Injection of fluorescence-labeled dextrans of various molecular weights allowed visualization of glomerular filtration and revealed leakage of 70 kDa dextran in an inducible model of proteinuria. Our findings demonstrate functionality and long-term survival of glomeruli devoid of Bowman's capsule and provide a novel approach for non-invasive longitudinal in vivo study of glomerular physiology and pathophysiology.
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Affiliation(s)
- Andreas D Kistler
- 1] Department of Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, USA [2] Division of Nephrology, University Hospital Zürich, Zürich, Switzerland
| | - Alejandro Caicedo
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Florida, USA
| | - Midhat H Abdulreda
- Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, Florida
| | - Christian Faul
- Department of Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Dontscho Kerjaschki
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - Per-Olof Berggren
- 1] Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, Florida [2] The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Jochen Reiser
- 1] Department of Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, USA [2] Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Alessia Fornoni
- 1] Department of Medicine, Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, USA [2] Diabetes Research Institute, Miller School of Medicine, University of Miami, Miami, Florida
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Molitoris BA. Using 2-photon microscopy to understand albuminuria. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2014; 125:343-56; discussion 356-7. [PMID: 25125750 PMCID: PMC4112674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Intravital 2-photon microscopy, along with the development of fluorescent probes and innovative software, has rapidly advanced the study of intracellular and intercellular processes at the organ level. Researchers can quantify the distribution, behavior, and dynamic interactions of up to four labeled chemical probes and proteins simultaneously and repeatedly in four dimensions (3D + time) with subcellular resolution in real time. Transgenic fluorescently labeled proteins, delivery of plasmids, and photo-activatable probes enhance these possibilities. Thus, multi-photon microscopy has greatly extended our ability to understand cell biology intra-vitally at cellular and subcellular levels. For example, evaluation of rat surface glomeruli and accompanying proximal tubules has shown the long held paradigm regarding limited albumin filtration under physiologic conditions is to be questioned. Furthermore, the role of proximal tubules in determining albuminuria under physiologic and disease conditions was supported by direct visualization and quantitative analysis.
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Hackl MJ, Burford JL, Villanueva K, Lam L, Suszták K, Schermer B, Benzing T, Peti-Peterdi J. Tracking the fate of glomerular epithelial cells in vivo using serial multiphoton imaging in new mouse models with fluorescent lineage tags. Nat Med 2013; 19:1661-6. [PMID: 24270544 PMCID: PMC3884556 DOI: 10.1038/nm.3405] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Accepted: 10/07/2013] [Indexed: 12/13/2022]
Abstract
Podocytes are critical in the maintenance of a healthy glomerular filter, however they have been difficult to study in the intact kidney due to technical limitations. Here we report the development of serial multiphoton microscopy (MPM) of the same glomeruli over several days to visualize the motility of podocytes and parietal epithelial cells (PEC) in vivo. In Podocin-GFP mice podocytes formed sporadic multi-cellular clusters after unilateral ureteral ligation (UUO) and migrated into the parietal Bowman’s capsule. The tracking of single cells in Podocin-confetti mice featuring cell-specific expression of CFP, GFP, YFP, or RFP revealed the simultaneous migration of multiple podocytes. In PEPCK-GFP mice serial MPM found PEC-to-podocyte migration and nanotubule connections. Our data support the highly dynamic rather than static nature of the glomerular environment and cellular composition. Future application of this new approach promises to advance our understanding of the mechanisms of glomerular injury and regeneration.
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Affiliation(s)
- Matthias J Hackl
- 1] Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA. [2] Department of Medicine, University of Southern California, Los Angeles, California, USA. [3] Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
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Linkermann A, Heller JO, Prókai A, Weinberg JM, De Zen F, Himmerkus N, Szabó AJ, Bräsen JH, Kunzendorf U, Krautwald S. The RIP1-kinase inhibitor necrostatin-1 prevents osmotic nephrosis and contrast-induced AKI in mice. J Am Soc Nephrol 2013; 24:1545-57. [PMID: 23833261 DOI: 10.1681/asn.2012121169] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The pathophysiology of contrast-induced AKI (CIAKI) is incompletely understood due to the lack of an appropriate in vivo model that demonstrates reduced kidney function before administration of radiocontrast media (RCM). Here, we examine the effects of CIAKI in vitro and introduce a murine ischemia/reperfusion injury (IRI)-based approach that allows induction of CIAKI by a single intravenous application of standard RCM after injury for in vivo studies. Whereas murine renal tubular cells and freshly isolated renal tubules rapidly absorbed RCM, plasma membrane integrity and cell viability remained preserved in vitro and ex vivo, indicating that RCM do not induce apoptosis or regulated necrosis of renal tubular cells. In vivo, the IRI-based CIAKI model exhibited typical features of clinical CIAKI, including RCM-induced osmotic nephrosis and increased serum levels of urea and creatinine that were not altered by inhibition of apoptosis. Direct evaluation of renal morphology by intravital microscopy revealed dilation of renal tubules and peritubular capillaries within 20 minutes of RCM application in uninjured mice and similar, but less dramatic, responses after IRI pretreatment. Necrostatin-1 (Nec-1), a specific inhibitor of the receptor-interacting protein 1 (RIP1) kinase domain, prevented osmotic nephrosis and CIAKI, whereas an inactive Nec-1 derivate (Nec-1i) or the pan-caspase inhibitor zVAD did not. In addition, Nec-1 prevented RCM-induced dilation of peritubular capillaries, suggesting a novel role unrelated to cell death for the RIP1 kinase domain in the regulation of microvascular hemodynamics and pathophysiology of CIAKI.
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Affiliation(s)
- Andreas Linkermann
- Division of Nephrology and Hypertension, Christian-Albrechts-University, Kiel, Germany
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Abstract
In the past decade, our understanding of the role of podocytes in the function of the glomerular filtration barrier, and of the role of podocyte injury in the pathogenesis of proteinuric kidney disease, has substantially increased. Landmark genetic studies identified mutations in genes expressed by podocytes as a cause of albuminuria and nephrotic syndrome, leading to breakthrough discoveries from many laboratories. These discoveries contributed to a dramatic change in our view of the glomerular filtration barrier of the kidney and of the role of podocyte injury in the development of albuminuria and progressive kidney disease. In the past several years, studies have demonstrated that podocyte injury is a major cause of marked albuminuria and nephrotic syndrome, and have confirmed that podocytes are important for the maintenance of an intact glomerular filtration barrier. An essential role of loss of these cells in the pathogenesis of glomerulosclerosis and progressive proteinuric kidney disease has also been identified. In this Review, we discuss the importance of podocytes for the maintenance of an intact glomerular filtration barrier and their role in albumin handling.
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Affiliation(s)
- Paul Thomas Brinkkoetter
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Kerpener Strasse 62, 50937 Cologne, Germany
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Schießl IM, Bardehle S, Castrop H. Superficial nephrons in BALB/c and C57BL/6 mice facilitate in vivo multiphoton microscopy of the kidney. PLoS One 2013; 8:e52499. [PMID: 23349687 PMCID: PMC3549997 DOI: 10.1371/journal.pone.0052499] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 11/19/2012] [Indexed: 02/05/2023] Open
Abstract
Multiphoton microscopy (MPM) offers a unique approach for addressing both the function and structure of an organ in near-real time in the live animal. The method however is limited by the tissue-specific penetration depth of the excitation laser. In the kidney, structures in the range of 100 µm from the surface are accessible for MPM. This limitation of MPM aggravates the investigation of the function of structures located deeper in the renal cortex, like the glomerulus and the juxtaglomerular apparatus. In view of the relevance of gene-targeted mice for investigating the function of these structures, we aimed to identify a mouse strain with a high percentage of superficially located glomeruli. The mean distance of the 30 most superficial glomeruli from the kidney surface was determined in 10 commonly used mouse strains. The mean depth of glomeruli was 118.4±3.4, 123.0±2.7, 133.7±3.0, 132.3±2.6, 141.0±4.0, 145.3±4.3, 148.9±4.2, 151.6±2.7, 167.7±3.9, and 207.8±3.2 µm in kidney sections from 4-week-old C3H/HeN, BALB/cAnN, SJL/J, C57BL/6N, DBA/2N, CD1 (CRI), 129S2/SvPas, CB6F1, FVB/N and NMRI (Han) mice, respectively (n = 5 animals from each strain). The mean distance from the kidney surface of the most superficial glomeruli was significantly lower in the strains C3H/HeN Crl, BALB/cAnN, DBA/2NCrl, and C57BL/6N when compared to a peer group consisting of all the other strains (p<.0001). In 10-week-old mice, the most superficial glomeruli were located deeper in the cortex when compared to 4-week-old animals, with BALB/cAnN and C57BL/6N being the strains with the highest percentage of superficial glomeruli (25% percentile 116.7 and 121.9 µm, respectively). In summary, due to significantly more superficial glomeruli compared to other commonly used strains, BALB/cAnN and C57BL/6N mice appear to be particularly suitable for the investigation of glomerular function using MPM.
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Affiliation(s)
- Ina Maria Schießl
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Sophia Bardehle
- Institute of Physiology, Department of Physiological Genomics, Ludwig-Maximilians-University, Munich, Germany
- Institute for Stem Cell Research, Helmholtz Zentrum, Munich, Germany
| | - Hayo Castrop
- Institute of Physiology, University of Regensburg, Regensburg, Germany
- * E-mail:
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Höhne M, Ising C, Hagmann H, Völker LA, Brähler S, Schermer B, Brinkkoetter PT, Benzing T. Light microscopic visualization of podocyte ultrastructure demonstrates oscillating glomerular contractions. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 182:332-8. [PMID: 23246153 DOI: 10.1016/j.ajpath.2012.11.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/17/2012] [Accepted: 11/01/2012] [Indexed: 12/23/2022]
Abstract
Podocytes, the visceral epithelial cells of the kidney glomerulus, elaborate primary and interdigitating secondary extensions to enwrap the glomerular capillaries. A hallmark of podocyte injury is the loss of unique ultrastructure and simplification of the cell shape, called foot process effacement, which is a classic feature of proteinuric kidney disease. Although several key pathways have been identified that control cytoskeletal regulation, actin dynamics, and polarity signaling, studies into the dynamic regulation of the podocyte structure have been hampered by the fact that ultrastructural analyses require electron microscopic imaging of fixed tissue. We developed a new technique that allows for visualization of podocyte foot processes using confocal laser scanning microscopy. The combination of inducible and mosaic expression of membrane-tagged fluorescent proteins in a small subset of podocytes enabled us to acquire light microscopic images of podocyte foot processes in unprecedented detail, even in living podocytes of freshly isolated glomeruli. Moreover, this technique visualized oscillatory glomerular contractions and confirmed the morphometric evaluations obtained in static electron microscopic images of podocyte processes. These data suggest that the new technique will provide an extremely powerful tool for studying the dynamics of podocyte ultrastructure.
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Affiliation(s)
- Martin Höhne
- Department II of Internal Medicine and the Center for Molecular Medicine Cologne, University of Cologne, 50937 Cologne, Germany
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43
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Peppiatt-Wildman CM, Crawford C, Hall AM. Fluorescence imaging of intracellular calcium signals in intact kidney tissue. Nephron Clin Pract 2012; 121:e49-58. [PMID: 23147410 DOI: 10.1159/000342812] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 08/14/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Intracellular calcium (Ca(2+)) plays an important role in normal renal physiology and in the pathogenesis of various kidney diseases; however, the study of Ca(2+) signals in intact tissue has been limited by technical difficulties, including achieving adequate loading of Ca(2+)-sensitive fluorescent dyes. The kidney slice preparation represents a model whereby three-dimensional tissue architecture is preserved and structures in both the cortex and medulla can be imaged using confocal or multiphoton microscopy. METHODS Ca(2+)-sensitive dyes Rhod-2, Fura-red and Fluo-4 were loaded into tubular and vascular cells in rat kidney slices using a re-circulating perfusion system and real-time imaging of Ca(2+) signals was recorded by confocal microscopy. Kidney slices were also obtained from transgenic mice expressing the GCaMP2 Ca(2+)-sensor in their endothelial cells and real time Ca(2+) transients stimulated by physiological stimuli. RESULTS Wide spread loading of Ca(2+) indicators was achieved in the tubular and vascular structures of both the medulla and cortex. Real time Ca(2+) signals were successfully recorded in different intracellular compartments of both rat and mouse cortical and medullary tubules in response to physiological stimuli (ATP and angiotensin II). Glomerular Ca(2+) transients were similarly recorded in kidney slices taken from the transgenic mouse expressing the GCaMP2 Ca(2+)-sensor. CONCLUSION We present new approaches that can be adopted to image cytosolic and mitochondrial Ca(2+) signals within various cell types in intact kidney tissue. Moreover, techniques described in this study can be used to facilitate future detailed investigations of intracellular Ca(2+) homeostasis in renal health and disease.
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Affiliation(s)
- C M Peppiatt-Wildman
- Medway School of Pharmacy, The Universities of Kent and Greenwich at Medway, Chatham Maritime, UK. C.M.Peppiatt @ kent.ac.uk
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Khoury CC, Khayat MF, Yeo TK, Pyagay PE, Wang A, Asuncion AM, Sharma K, Yu W, Chen S. Visualizing the mouse podocyte with multiphoton microscopy. Biochem Biophys Res Commun 2012; 427:525-30. [PMID: 23022193 DOI: 10.1016/j.bbrc.2012.09.089] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 09/14/2012] [Indexed: 01/05/2023]
Abstract
The podocyte is a highly specialized kidney glomerular epithelial cell that plays an essential role in glomerular filtration and is believed to be the target of numerous glomerular diseases leading to proteinuria. Despite the leaps in our understanding of podocyte biology, new methodologies are needed to facilitate research into the cell. Multiphoton microscopy (MPM) was used to image the nephrin knockout/green fluorescent protein (GFP) knock-in heterozygote (Nphs1(tm1Rkl)/J) mouse. The nephrin promoter restricts GFP expression to the podocytes that fluoresce green under excitation. From the exterior of an intact kidney, MPM can peer into the renal parenchyma and visualize the podocytes that outline the globular shape of the glomeruli. Details as fine as the podocyte's secondary processes can be resolved. In contrast, podocytes exhibit no fluorescence in the wildtype mouse and are invisible to MPM. Phenotypically, there are no significant differences between wildtype and Nphs1(tm1Rkl)/J mice in body weight, urinary albumin excretion, creatinine clearance, or glomerular depth. Interestingly, the glomeruli are closer to the kidney capsule in female mice, making the gender the preferred choice for MPM. For the first time, green fluorescent podocytes in a mouse model free of confounding phenotypes can be visualized unequivocally and in the "positive" by MPM, facilitating intravital studies of the podocyte.
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Affiliation(s)
- Charbel C Khoury
- Division of Nephrology/Hypertension, Northwestern University, Chicago, IL, USA.
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Nakano D, Kobori H, Burford JL, Gevorgyan H, Seidel S, Hitomi H, Nishiyama A, Peti-Peterdi J. Multiphoton imaging of the glomerular permeability of angiotensinogen. J Am Soc Nephrol 2012; 23:1847-56. [PMID: 22997258 DOI: 10.1681/asn.2012010078] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Patients and animals with renal injury exhibit increased urinary excretion of angiotensinogen. Although increased tubular synthesis of angiotensinogen contributes to the increased excretion, we do not know to what degree glomerular filtration of systemic angiotensinogen, especially through an abnormal glomerular filtration barrier, contributes to the increase in urinary levels. Here, we used multiphoton microscopy to visualize and quantify the glomerular permeability of angiotensinogen in the intact mouse and rat kidney. In healthy mice and Munich-Wistar-Frömter rats at the early stage of glomerulosclerosis, the glomerular sieving coefficient of systemically infused Atto565-labeled human angiotensinogen (Atto565-hAGT), which rodent renin cannot cleave, was only 25% of the glomerular sieving coefficient of albumin, and its urinary excretion was undetectable. In a more advanced phase of kidney disease, the glomerular permeability of Atto565-hAGT was slightly higher but still very low. Furthermore, unlike urinary albumin, the significantly higher urinary excretion of endogenous rat angiotensinogen did not correlate with either the Atto565-hAGT or Atto565-albumin glomerular sieving coefficients. These results strongly suggest that the vast majority of urinary angiotensinogen originates from the tubules rather than glomerular filtration.
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Affiliation(s)
- Daisuke Nakano
- Department of Pharmacology, Kagawa University, Kagawa, Japan
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Salmon AHJ, Ferguson JK, Burford JL, Gevorgyan H, Nakano D, Harper SJ, Bates DO, Peti-Peterdi J. Loss of the endothelial glycocalyx links albuminuria and vascular dysfunction. J Am Soc Nephrol 2012; 23:1339-50. [PMID: 22797190 DOI: 10.1681/asn.2012010017] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Patients with albuminuria and CKD frequently have vascular dysfunction but the underlying mechanisms remain unclear. Because the endothelial surface layer, a meshwork of surface-bound and loosely adherent glycosaminoglycans and proteoglycans, modulates vascular function, its loss could contribute to both renal and systemic vascular dysfunction in proteinuric CKD. Using Munich-Wistar-Fromter (MWF) rats as a model of spontaneous albuminuric CKD, multiphoton fluorescence imaging and single-vessel physiology measurements revealed that old MWF rats exhibited widespread loss of the endothelial surface layer in parallel with defects in microvascular permeability to both water and albumin, in both continuous mesenteric microvessels and fenestrated glomerular microvessels. In contrast to young MWF rats, enzymatic disruption of the endothelial surface layer in old MWF rats resulted in neither additional loss of the layer nor additional changes in permeability. Intravenous injection of wheat germ agglutinin lectin and its adsorption onto the endothelial surface layer significantly improved glomerular albumin permeability. Taken together, these results suggest that widespread loss of the endothelial surface layer links albuminuric kidney disease with systemic vascular dysfunction, providing a potential therapeutic target for proteinuric kidney disease.
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Affiliation(s)
- Andrew H J Salmon
- Microvascular Research Laboratories, School of Physiology and Pharmacology, University of Bristol, Southwell Street, Bristol, UK.
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Peti-Peterdi J, Gevorgyan H, Lam L, Riquier-Brison A. Metabolic control of renin secretion. Pflugers Arch 2012; 465:53-8. [PMID: 22729752 DOI: 10.1007/s00424-012-1130-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 06/09/2012] [Accepted: 06/11/2012] [Indexed: 01/04/2023]
Abstract
One emerging topic in renin-angiotensin system (RAS) research is the direct local control of renin synthesis and release by endogenous metabolic intermediates. During the past few years, our laboratory has characterized the localization and signaling of the novel metabolic receptor GPR91 in the normal and diabetic kidney and established GPR91 as a new, direct link between high glucose and RAS activation in diabetes. GPR91 (also called SUCNR1) binds tricarboxylic acid (TCA) cycle intermediate succinate which can rapidly accumulate in the local tissue environment when energy supply and demand are out of balance. In a variety of physiological and pathological conditions associated with metabolic stress, succinate signaling via GPR91 appears to be an important mediator or modulator of renin secretion. This review summarizes our current knowledge on the control of renin release by molecules of endogenous metabolic pathways with the main focus on succinate/GPR91.
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Affiliation(s)
- János Peti-Peterdi
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, ZNI 335, Los Angeles, CA 90033, USA.
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