Project description:Preconditioning strategies like caloric restriction (CR) and hypoxic preconditioning (HP) show remarkable protective effects in animal models of acute kidney injury (AKI). Since the underlying molecular effects are still not fully understood we performed an experiment directly comparing CR and HP in a murine model of ischemia-reperfusion injury (IRI) of the kidney. 8 to 12-week-old, male C57BL6/J mice were either put to 4 weeks of caloric restriction (70% of normal food intake) or placed in a hypoxic chamber (8%O2) for 3 consecutive days prior to IRI. Whole kidneys were used for transcriptional analysis (RNAseq) before and after ischemia-reperfusion injury to look for common effects of both modes of preconditioning.
Project description:Background: Cardiac surgery-associated acute kidney injury (CS-AKI) is reported in 20-30% of patients undergoing cardiac surgery and, leading to poor outcomes and increased healthcare costs. Because the pathophysiology of CS-AKI is complex and has not been fully elucidated, no effective preventive and interventional strategy has been reported. Nitrite, a nitric oxide (NO) donor under hypoxic conditions, has shown to exert organ-protective effects in various kind of preclinical models, however, its efficacy in CS-AKI remains unclear. Objectives: This study aimed to generate a rat cardiopulmonary bypass (CPB) model to induce AKI, identify key molecular pathways involved in its pathophysiology, and evaluate the renoprotective effects of nitrite. Methods: A CPB model was established using rats and AKI was confirmed through molecular and histological analysis. RNA-seq was performed to identify differentially expressed genes and enriched pathway. Nitrite (2 mg/kg) was intravenously administered prior to CPB, and its effects on kidney injury markers and inflammation-related pathways were evaluated. Results: AKI was successfully produced in our rat CPB model, as evidenced by increased KIM-1 and NGAL expression and renal histological damage. RNA-seq revealed significant activation of multiple inflammation-related pathways, including TNF and NFκB signaling pathway. Nitrite administration significantly reduced KIM-1 and NGAL expression and suppressed these pathways associated with development of AKI. Conclusion: This study underscores the role of inflammation in CS-AKI pathophysiology and demonstrates the renoprotective potential of nitrite. These findings provide a foundation for further investigations into nitrite's mechanisms and its potential clinical application in cardiac surgery.
Project description:This study was aimed to investigate the role and underlying mechanism of TRPM2 in cisplatin nephrotoxicity. Cisplatin-induced acute kidney injury (AKI) model was established in WT and TRPM2-KO mice. The transcriptome profiling of the kidneys of WT and TRPM2-KO mice treated with cisplatin was compared to find differentially expressed gene which may be related to TRPM2 on cisplatin nephrotoxicity.
Project description:Renal hypoxia is widespread in acute kidney injury (AKI) of various aetiologies. Hypoxia adaptation, conferred through the hypoxia-inducible factor (HIF), appears to be insufficient. Here we show that HIF activation in renal tubules through Pax8-rtTA-based inducible knockout of von Hippel-Lindau protein (VHL-KO) protects from rhabdomyolysis-induced AKI. In this model, histological observations indicate that injury mainly affects proximal convoluted tubules, with 5% necrosis at d1 and 40% necrosis at d2. HIF-1alpha up-regulation in distal tubules reflects renal hypoxia. However, lack of HIF in proximal tubules suggests insufficient adaptation by HIF. AKI in VHL-KO mice leads to prominent HIF activation in all nephron segments, as well as to reduced serum creatinine, serum urea, tubular necrosis, and apoptosis marker caspase-3 protein. At d1 after rhabdomyolysis, when tubular injury is potentially reversible, HIF mediated protection in AKI is associated with activated glycolysis, cellular glucose uptake and utilization, autophagy, vasodilation, and proton removal as demonstrated by qPCR, pathway enrichment analysis and immunohistochemistry. Together, our data provide evidence for a HIF-orchestrated multi-level shift towards glycolysis as a major mechanism for protection against acute tubular injury. All experiments were carried out in transgenic mice in which selective renal tubular VHL knockout (VHL-KO) was inducible by doxycycline (Reference: Mathia S, Paliege A, Koesters R, Peters H, Neumayer HH, Bachmann S, Rosenberger C. Action of hypoxia-inducible factor in liver and kidney from mice with Pax8-rtTA-based deletion of von Hippel-Lindau protein. Acta Physiol (Oxf). 2013; 207(3):565-76.). Four groups of animals were used: 1) controls: untreated mice; 2) VHL-KO: injected with doxycycline (0.1 mg per 10 g body weight SC), 4 days prior to sacrifice; 3) AKI: rhabdomyolysis; 4) VHL-KO/AKI: doxycycline plus rhabdomyolysis. To induce AKI, 50% glycerol (0.05 ml per 10 g body weight) was injected IM into the left hind limb under isoflurane narcosis. Drinking water was withdrawn between 20 h prior and 24 h after glycerol injection.
Project description:Ischemic acute kidney injury (AKI), a complication that frequently occurs in hospital settings, is often associated with hemodynamic compromise, sepsis, cardiac surgery or exposure to nephrotoxicants. AKI is associated with immune cell infiltration into the kidney stroma, which causes acute tubular injury. Here, using a murine renal ischemic-reperfusion injury (IRI) model we show that intercalated cells (ICs) rapidly adopt a pro-inflammatory phenotype post IRI. During the early phase of AKI, we demonstrate that either blocking the pro-inflammatory P2Y14 receptor located on the apical membrane of ICs, or ablation of the gene encoding the P2Y14 receptor in ICs: 1) inhibits IRI-induced chemokine expression increase in ICs; 2) reduces neutrophil and monocyte renal infiltration; 3) reduces the extent of kidney dysfunction; and 4) attenuates proximal tubule (PT) damage. These observations indicate that the P2Y14 receptor participates in the very first inflammatory steps associated with ischemic AKI. In addition, we show that the concentration of the P2Y14 receptor ligand, uridine diphosphate-glucose (UDP-Glc), is higher in urine samples from intensive care unit patients who developed AKI when compared with urine from patients without AKI. In particular, we observed a strong correlation between UDP-Glc concentration and the development of AKI in cardiac surgery patients. Our study identifies the UDP-Glc/P2Y14 receptor axis as a potential target for the prevention and/or attenuation of ischemic-AKI.