Project description:The aim of this study was to identify miRNAs that regulate AKI and develop their applications as diagnostic biomarkers and therapeutic agents. First, kidney tissues from two different AKI mouse models, namely, AKI induced by the administration of lipopolysaccharide (LPS) causing sepsis (LPS-AKI mice) and AKI induced by renal ischemia–reperfusion injury (IRI-AKI mice), were exhaustively screened for their changes of miRNA expression compared with that of control mice by microarray analysis.
Project description:The aim of this study was to identify miRNAs that regulate AKI and develop their applications as diagnostic biomarkers and therapeutic agents. First, kidney tissues from two different AKI mouse models, namely, AKI induced by the administration of lipopolysaccharide (LPS) causing sepsis (LPS-AKI mice) and AKI induced by renal ischemia–reperfusion injury (IRI-AKI mice), were exhaustively screened for their changes of miRNA expression compared with that of control mice by microarray analysis.
Project description:Sepsis-associated acute kidney injury (SA-AKI) is a severe and life-threatening condi-tion with high morbidity and mortality among emergency patients, and it poses a sig-nificant risk of chronic renal failure. Clinical treatments for SA-AKI remain reactive and non-specific, lacking effective diagnostic biomarkers or treatment targets. In this study, we established an SA-AKI mouse model using LPS and performed proteomics and metabolomics analyses. A variety of bioinformatic analyses, including Gene Set En-richment Analysis (GSEA), Weighted Gene Co-expression Network Analysis (WGCNA), protein and protein interactions (PPI), and MetaboAnalyst analysis, were conducted to investigate the key molecules of SA-AKI. Proteomics and metabolomics analyses re-vealed that sepsis led to impaired renal mitochondrial function and metabolic disorders. Immune-related pathways were found to be activated in kidneys upon septic infection. The catabolic products of polyamines accumulated in septic kidneys. Overall, our study provides a more comprehensive understanding of SA-AKI and identifies potential pathways for this condition.
Project description:Clustering of the Enteropathogenic (EPEC) Escherichia coli Tir effector, induced by its binding to Intimin, leads to pyroptotic cell death in macrophages. The effect of Tir clustering following EPEC infection of epithelial cells remains unexplored. In this study, we show that EPEC induces pyroptosis in an intestinal epithelial cell (IEC) line, in a Tir-dependent but actin polymerisation-independent manner, which was enhanced by priming with IFNγ. Mechanistically, Tir clustering induces rapid Ca2+ influx, which promotes internalisation of LPS, followed by activation of caspase-4. Chelation of extracellular Ca2+ or knockdown of caspase-4 inhibited cell death upon EPEC infection, whereas ATP-induced extracellular Ca2+ influx had the opposite effect confirming the regulatory role of calcium in the pathway. Additionally, IEC lines with low endogenous expression of caspase-4 were resistant to EPEC-induced cell death. We reveal a novel mechanism of LPS internalisation, following infection with an extracellular pathogen, leading to pyroptosis in IECs.
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:Endothelial dysfunction is a hallmark of LPS-induced acute kidney injury (AKI). Endothelial cells (EC) acquired a fibroblast-like phenotype and contributed to myofibroblasts generation through Endothelial to Mesenchymal Transition (EndMT) process. Noteworthy, ARPCs enhance tubular regenerative mechanism during AKI, but little is known about their effects on EC. Here we investigated whether ARPCs could prevent sepsis-induced EndMT and the related mechanism. When activated by LPS, Human endothelial cells (EC) proliferated and decreased specific EC markers such as CD31 and VE-cadherin and up-regulated myofibroblast markers such as Collagen I and Vimentin. The co-culture with ARPCs normalized EC proliferation rate and abrogated the LPS-induced EndMT by restoring the high expression of EC markers and the low expression of myofibroblast markers. Gene set enrichment analysis showed that most of genes modulated in LPS-stimulated ARPCs belongs to cell activation and defense response pathways. In particular, among most up-regulated genes we found BPIFA2, SAA2, SAA4 and CXCL6. BPIFA2 is recently described as an early biomarker of AKI but little is known about its function in the kidney. The other genes are frequently involved in the response to bacterial infection and kidney injury. Finally, in a swine model of LPS-induced AKI, we observed an increase of CD133+ARPCs that expressed BPIFA2 respect to healthy pigs. Taken together, these results suggest an underestimate role of ARPCS in preventing endothelial dysfuncton by the production of several proteins. The identification of these molecules may offer novel strategies to protect endothelial compartment and promote kidney repair.
Project description:Here, we investigated the efficacy of polymethyl methacrylate membrane (PMMA)-based continuous hemofiltration (CVVH) in modulating systemic and tissue immune activation in a swine model of LPS-induced AKI. Methods: After 3 hours from LPS infusion, animals underwent to PMMA-CVVH or polysulfone (PS)-CVVH. Gene expression profile was performed from isolated peripheral blood mononuclear cells (PBMC) by microarrays and the results validated by Real-time PCR.
Project description:Altered cellular metabolism in kidney proximal tubule (PT) cells plays a critical role in the development and progression of acute kidney injury (AKI). The transcription factor Krüppel-like factor 6 (KLF6) is rapidly and robustly induced in the PT after AKI, suggesting an early-inducible injury response gene. PT-specific Klf6 knockdown (Klf6PTKO) are protected from AKI and resulting fibrosis in mice. Combined RNA-sequencing and ChIP-sequencing demonstrated preserved expression of genes encoding branched chain amino acid (BCAA) catabolic enzymes in Klf6PTKO mice, with several of the genes also having KLF6 binding sites close to their transcription start sites. Conversely, inducible KLF6 overexpression suppressed expression of BCAA genes and exacerbated kidney injury and fibrosis in mice. Injured kidney cells could not respond to the BCAA catabolic activator BT2, and injured cells overexpressing KLF6 were less able to utilize BCAA. Thus, targeting KLF6-mediated suppression of BCAA catabolism may serve as key therapeutic target in AKI and kidney fibrosis.