scholarly journals NMR spectroscopy and electron microscopy identification of metabolic and ultrastructural changes to the kidney following ischemia-reperfusion injury

2018 ◽  
Vol 314 (2) ◽  
pp. F154-F166 ◽  
Author(s):  
Tafadzwa Chihanga ◽  
Qing Ma ◽  
Jenna D. Nicholson ◽  
Hannah N. Ruby ◽  
Richard E. Edelmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Proximal Tubule ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Ultrastructural Changes ◽  
Urinary Glucose ◽  
Brush Borders ◽  
Distal Tubules ◽  
Collecting Tubules

Cellular, molecular, and ultrastructural nephron changes associated with ischemia-reperfusion injury-induced acute kidney injury (IRI-AKI) are not completely understood. Here, a multidisciplinary study was used to identify nephron changes in a mouse model of IRI-AKI. Histological analyses indicated distended Bowman’s glomerular spaces and proximal and distal tubules. Increased filtrate volume in nephrons was caused by reduced water reabsorption by severely damaged proximal tubule brush borders and blocked flow of filtrate into collecting tubules by mucoprotein casts in distal tubules. Immunohistochemistry revealed protein AKI biomarkers in proximal tubules and glomeruli but not in distal tubules. Nuclear magnetic resonance spectroscopy revealed several metabolites that increased such as valine, alanine, and lactate. Other metabolites such as trigonelline, succinate, 2-oxoisocaproate, and 1- methyl-nicotinamide decreased or were absent in urine following IRI due to altered kidney function or metabolism. Urinary glucose increased due to reduced reabsorption by damaged proximal tubule brush borders. Scanning electron microscopy revealed flattening of podocytes and pedicals surrounding glomerular capillaries, and transmission electron microscopy (TEM) revealed effacement of podocyte pedicals, both consistent with increased hydrostatic pressure in nephrons following IRI-AKI. TEM revealed shortened proximal tubule microvilli in IRI kidneys with diminished lamina propia. TEM showed dramatic loss of mitochondria in distal tubule epithelia of IRI kidneys and emergence of multivesicular bodies of endosomes indicating ongoing cellular death. Collectively, the data define ultrastructural changes to nephrons and altered kidney metabolism associated with IRI-AKI.

scholarly journals Proximal Tubule–Derived Amphiregulin Amplifies and Integrates Profibrotic EGF Receptor Signals in Kidney Fibrosis

2019 ◽  
Vol 30 (12) ◽  
pp. 2370-2383 ◽  
Author(s):  
Eirini Kefaloyianni ◽  
Manikanda Raja Keerthi Raja ◽  
Julian Schumacher ◽  
Muthu Lakshmi Muthu ◽  
Vaishali Krishnadoss ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Reperfusion Injury ◽  
Knockout Mice ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Proximal Tubule Cell ◽  
Tubule Cell ◽  
Proximal Tubule Cells ◽  
Kidney Fibrosis ◽  
Tubule Cells

BackgroundSustained activation of EGF receptor (EGFR) in proximal tubule cells is a hallmark of progressive kidney fibrosis after AKI and in CKD. However, the molecular mechanisms and particular EGFR ligands involved are unknown.MethodsWe studied EGFR activation in proximal tubule cells and primary tubular cells isolated from injured kidneys in vitro. To determine in vivo the role of amphiregulin, a low-affinity EGFR ligand that is highly upregulated with injury, we used ischemia-reperfusion injury or unilateral ureteral obstruction in mice with proximal tubule cell–specific knockout of amphiregulin. We also injected soluble amphiregulin into knockout mice with proximal tubule cell–specific deletion of amphiregulin’s releasing enzyme, the transmembrane cell-surface metalloprotease, a disintegrin and metalloprotease-17 (ADAM17), and into ADAM17 hypomorphic mice.ResultsYes-associated protein 1 (YAP1)–dependent upregulation of amphiregulin transcript and protein amplifies amphiregulin signaling in a positive feedback loop. YAP1 also integrates signals of other moderately injury-upregulated, low-affinity EGFR ligands (epiregulin, epigen, TGFα), which also require soluble amphiregulin and YAP1 to induce sustained EGFR activation in proximal tubule cells in vitro. In vivo, soluble amphiregulin injection sufficed to reverse protection from fibrosis after ischemia-reperfusion injury in ADAM17 hypomorphic mice; injected soluble amphiregulin also reversed the corresponding protective proximal tubule cell phenotype in injured proximal tubule cell–specific ADAM17 knockout mice. Moreover, the finding that proximal tubule cell–specific amphiregulin knockout mice were protected from fibrosis after ischemia-reperfusion injury or unilateral ureteral obstruction demonstrates that amphiregulin was necessary for the development of fibrosis.ConclusionsOur results identify amphiregulin as a key player in injury-induced kidney fibrosis and suggest therapeutic or diagnostic applications of soluble amphiregulin in kidney disease.

Protective Effect of Octreotide Against Liver Ischemic Reperfusion Injury in Rats

2020 ◽  
Vol 10 (8) ◽  
pp. 1115-1121
Author(s):  
Shuangfa Zou ◽  
Huiping Sun ◽  
Yanhua Peng ◽  
Shuo Yang ◽  
Jinfeng Yang
Keyword(s):  
Electron Microscopy ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Light And Electron Microscopy ◽  
Control Group ◽  
Sham Operation ◽  
Morphological Alterations ◽  
Saline Treatment ◽  
Octreotide Treatment

Liver ischemia-reperfusion injury (LIRI) is an inevitable complication during liver resection and liver transplantation. This study explored the effect of octreotide pretreatment on LIRI in rat model. Thirty male SD rats were included. They were divided into three groups: control group (sham operation plus saline treatment); ischemia/reperfusion group (IR group, ischemia/reperfusion operation plus saline treatment) and octreotide treatment group (IR + Oct group, ischemia/reperfusion operation plus octreotide treatment). The serum liver enzymes (ALT, AST) were tested to assess the liver damage in the rats. Light and electron microscopy was used to identify morphological alterations in each group. The expressions of HMGB1, RIP1 and RIP3 were measured by Immunohistochemistry and Western Blot. The levels of AST, ALT in IR group increased significantly (P < 0 05), and were significantly reduced by Octreotide pretreatment (P < 0 05). Morphology of control group remained grossly normal by transmission electron microscopy. While mitochondrial degeneration, cristae disruption, swelling, rupture was observed in IR group. The microscopic morphology of liver cells was basically normal and occasionally a small number of mitochondria were a little swelled in pretreatment with octreotide group. The expressions of HMGB1, RIP1 and RIP3 in pretreatment with octreotide were significantly down-regulated compared with those in pretreatment without octreotide (P < 0 001). The present study suggested that octreotide pretreatment play a protective role in LIRI, due to the decreased necrotizing apoptosis of hepatocytes. The mechanisms underlying these effects may be associated with the inhibition of HMGB1/RIP1/RIP3 necrotizing apoptosis signals.

scholarly journals Proximal Tubule CD73 Is Critical in Renal Ischemia-Reperfusion Injury Protection

2016 ◽  
Vol 28 (3) ◽  
pp. 888-902 ◽  
Author(s):  
Sun-sang J. Sung ◽  
Li Li ◽  
Liping Huang ◽  
Jessica Lawler ◽  
Hong Ye ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Reperfusion Injury ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Renal Ischemia ◽  
Renal Ischemia Reperfusion Injury ◽  
Injury Protection

scholarly journals Intravital imaging of real-time endogenous actin dysregulation in proximal and distal tubules at the onset of severe ischemia-reperfusion injury

2021 ◽  
Author(s):  
Peter R. Corridon ◽  
Shurooq H. Karam ◽  
Ali A. Khraibi ◽  
Anousha A. Khan ◽  
Mohamed A. Alhashmi
Keyword(s):  
Reperfusion Injury ◽  
Real Time ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Renal Ischemia ◽  
Two Photon Microscopy ◽  
Real Time Visualization ◽  
Distal Tubules ◽  
Actin Expression

Abstract Severe renal ischemia-reperfusion injury (IRI) can lead to acute and chronic kidney dysfunction. Cytoskeletal modifications are among the main effects of this condition. The majority of studies that have contributed to the current understanding of IRI have relied on histological analyses using exogenous probes after the fact. Here we report the successful real-time visualization of actin cytoskeletal alterations in live proximal and distal tubules that arise at the onset of severe IRI. To achieve this, we induced fluorescent actin expression in these segments in rats with hydrodynamic gene delivery (HGD). Using intravital two-photon microscopy we then tracked and quantified endogenous actin dysregulation that occurred by subjecting these animals to 60 minutes of bilateral renal ischemia. Rapid (by 1-hour post-reperfusion) and significant (up to 50%) declines in actin content were observed. The decline in fluorescence within proximal tubules was significantly greater than that observed in distal tubules. Actin-based fluorescence was not recovered during the measurement period extending 24 hours post-reperfusion. Such injury decimated the renal architecture, in particular, actin brush borders, and hampered the reabsorptive and filtrative capacities of these tubular compartments. Thus, for the first time, we show that the combination of HGD and intravital microscopy can serve as an experimental tool to better understand how IRI modifies the cytoskeleton in vivo and provide an extension to current histopathological techniques.

Reversibility of ultrastructural, contractile function and Ca2+ transport changes in guinea pig hearts after global ischemia

1986 ◽  
Vol 64 (11) ◽  
pp. 1368-1375 ◽  
Author(s):  
Pawan K. Singal ◽  
Sheu L. Lee ◽  
Pallab K. Ganguly ◽  
Vincenzo Panagia ◽  
Naranjan S. Dhalla
Keyword(s):  
Guinea Pig ◽  
Reperfusion Injury ◽  
Structural Damage ◽  
Ischemia Reperfusion Injury ◽  
Contractile Function ◽  
Ischemia Reperfusion ◽  
Contractile Force ◽  
Global Ischemia ◽  
Ultrastructural Changes ◽  
Ischemic Insult

To understand the subcellular basis of contractile failure due to ischemia–reperfusion injury, effects of 20, 60, and 90 min of global ischemia followed by 30 min of reperfusion were examined in isolated guinea pig hearts. Cardiac ultrastructure and function as well as Ca2+ transport abilities of both mitochondrial and microsomal fractions were determined in control, ischemic, and reperfused hearts. Hearts were unable to generate any contractile force after 20 min of ischemia and showed a 75% recovery upon reperfusion. However, there were no significant changes in the subcellular Ca2+ transport in the 20-min ischemic or reperfused hearts. When hearts were made ischemic for 60 and 90 min, the recovery of contractile force on reperfusion was 50 and 7%, respectively. There was a progressive decrease in mitochondrial and microsomal Ca2+ binding and uptake activities after 60 and 90 min of ischemia; these changes were evident at various times of incubation period and at different concentrations of Ca2+. Mitochondrial Ca2+ transport changes were only partially reversible upon reperfusion after 60 and 90 min of ischemia, whereas the microsomal Ca2+ binding, uptake and Ca2+ ATPase activities deteriorated further upon reperfusion of the 90-min ischemic hearts. Ultrastructural changes increased with the duration of the ischemic insult and reperfusion injury was extensive in the 90-min ischemic hearts. These data show that the lack of recovery of contractile function upon reperfusion after a prolonged ischemic insult was accompanied by defects in sarcoplasmic reticulum Ca2+ transporting properties and structural damage.

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