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CD4 T cell response in AKI

ABSTRACT: CD4+ T cells mediate the pathogenesis of ischemic and nephrotoxic acute kidney injury (AKI), as well as acute injury to other organs. However, the underlying mechanisms of CD4+ T cell-mediated pathogenesis are largely unknown. We therefore conducted unbiased RNA-sequencing to discover novel mechanistic pathways of kidney CD4+ T cells post-ischemia compared to normal mouse kidney. Unexpectedly, lipocalin-2 (Lcn2) gene, which encodes neutrophil gelatinase-associated lipocalin (NGAL) had the highest (~60)-fold increase. The NGAL increase in CD4+ T cells during AKI was confirmed at the mRNA level with real-time PCR and at the protein level with ELISA. NGAL is a potential biomarker for the early detection of AKI and has multiple potential biological functions during organ injury. However, the role of NGAL produced by CD4+ T cells has not been investigated. We found that ischemic AKI in NGAL knockout (KO) mice had worse renal outcomes compared to wild type (WT) mice. Adoptive transfer of NGAL-deficient CD4+ T cells from NGAL KO mice into CD4 KO or WT mice led to worse renal function than transfer of WT CD4+ T cells. In vitro simulated ischemia reperfusion showed that NGAL-deficient CD4+ T cells express higher levels of IFN-γ mRNA compared to WT CD4+ T cells. In vitro differentiation of naive CD4+ T cells to Th17, Th1 and Th2 cells led to significant increase in Lcn2 expression. Human kidney CD4+ T cell NGAL also increased significantly post-ischemia. These results demonstrate an important role for CD4+ T cell NGAL as a mechanism by which CD4+ T cells mediate AKI and extend the importance of NGAL in AKI beyond diagnostics.

ORGANISM(S): Mus musculus

PROVIDER: GSE139171 | GEO | 2019/11/25

REPOSITORIES: GEO

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Project description:Hypertension and persistent activation of the renin-angiotensin system (RAS) are predisposing factors for development of acute kidney injury (AKI). Although bone marrow-derived stromal cells (BMSCs) have shown therapeutic promise in treatment of AKI, the impact of pathological RAS on BMSC functionality has remained unresolved. RAS and its local components in the bone marrow are involved in several key steps of cell maturation processes. This may also render BMSC population vulnerable to alterations even in the early phases of RAS pathology. We isolated TG-BMSCs from young, end organ disease-free rats with increased RAS activation (human angiotensinogen/renin double transgenic rats; dTGR) that eventually develop hypertension and die of end-organ damage and kidney failure at 8-weeks-of-age. Control cells were isolated from wild-type Sprague-Dawley rats (SD-BMSCs). Cell phenotype, mitochondrial reactive oxygen species (ROS) production and respiration were assessed, and gene expression profiling was carried out using microarrays. Cells’ therapeutic efficacy was evaluated in a rat model of acute ischemia-reperfusion-induced AKI. Serum urea and creatinine were measured at 24h and 48h. Acute tubular damage was scored and immunohistochemistry was used for evaluation for markers of inflammation (MCP-1, ED-1), and kidney injury (KIM-1, NGAL). TG-BMSCs showed distinct mitochondrial morphology, decreased cell respiration, and increased production of ROS. Gene expression profiling revealed a pronounced pro-inflammatory phenotype. In contrast to the therapeutic effect of SD-BMSCs, administration of TG-BMSCs in the AKI model resulted in exacerbation of kidney injury and high mortality. Our results demonstrate that early persistent RAS activation can dramatically compromise therapeutic potential of BMSCs by shift into a pro-inflammatory phenotype with mitochondrial dysfunction. A comparison of transcriptome of a bone marrow-derived stromal cells from a double-transgene rats compared to those from control rats

Project description:Microarray analysis of human kidneys with acute kidney injury (AKI) has been limited because such kidneys are seldom biopsied. However, all kidney transplants experience AKI, and early kidney transplants without rejection are an excellent model for human AKI: they are screened to exclude chronic kidney disease, frequently biopsied, and have extensive follow-up. We used histopathology and microarrays to compare indication biopsies from 28 transplants with AKI to 11 pristine protocol biopsies of stable transplants. Kidneys with AKI showed increased expression of 394 injury-repair response associated transcripts, including many known epithelial injury molecules (e.g. ITGB6, LCN2), tissue remodeling molecules (e.g. VCAN), and inflammation molecules (S100A8, ITGB3). Many other genes also predict the phenotype, depending on statistical filtering rules, including AKI biomarkers as HAVCR1 and IL18. Most mouse orthologs of the top injury-repair transcripts were increased in published mouse AKI models. Pathway analysis of the injury-repair transcripts revealed similarities to cancer, development, and cell movement. The injury-repair transcript score AKI kidneys correlated with reduced function, future recovery, brain death, and need for dialysis, but not future graft loss. In contrast, histologic features of "acute tubular injury" did not correlate with function or with the molecular changes. Thus the injury-repair associated transcripts represent a massive coordinate injury-repair response of kidney parenchyma to AKI, similar to mouse AKI models, and provide an objective measure for assessing the severity of AKI in kidney biopsies and validation for the use of many AKI biomarkers. AKI biopsies sample names and CEL files are from GSE21374. All consenting renal transplant patients undergoing biopsies for cause as standard of care between 09/2004 and 10/2007 at the university of Alberta or between 11/2006 and 02/2007 at the University of Illinois were included in the analysis. In addition to the cores required for standard histopathology, we collected one core for gene expression studies. the relationship between gene expression in the biopsy and subsequent graft loss was analyzed. This dataset is part of the TransQST collection.

Project description:Background: Acute kidney injury (AKI) is a common clinical event with high morbidity and mortality. We previously demonstrated that injection of cord blood endothelial colony forming cell (ECFC)-derived exosomes, highly enriched in miRNA(miR)-486-5p, prevented ischemic kidney injury in mice. While preclinical models support involvement of several miRs in AKI, the direct effects of miR-486-5p on injury and the kidney transcriptome are unknown. Objective: We studied effects of miR-486-5p in mice with kidney ischemia-reperfusion (IR) injury, and compared the impact of miR-486-5p and ECFC-derived exosomes on the transcriptome of proximal tubules (PTs) and renal endothelial cells. Methods: Adult male mice were subjected to bilateral kidney ischemia (30 min), and injected via tail vein with or without vehicle, miR-486-5p mimic, ECFC-derived exosomes, or scramble miR at the start of reperfusion. Plasma and tissues were collected 24 hrs after reperfusion, and proximal tubular and endothelial cells were isolated for mRNA analysis by RNA-Seq. Results: In mice with kidney IR, injection of miR-486-5p mimic increased levels of miR-486-5p in proximal tubules and endothelial cells, and significantly improved plasma creatinine, histological injury, neutrophil infiltration, and apoptosis, compared to vehicle treatment. MiR-486-5p inhibited expression of phosphatase and tensin homolog (PTEN), and activated AKT. Similar results were observed with exosomes, but scramble miR had no effect. In proximal tubules, miR-486-5p or exosomes reduced expression of several AKI genes (e.g. Lcn2, Havcr1 and Krt20) and caused alterations in apoptotic genes compared to IR alone. In endothelium, miR-486-5p or exosomes caused milder effect than in PTs but still impacting on expression of injury-related genes. Conclusion: MiR-486-5p protects mice against ischemic kidney injury. Both miR-486-5p and exosomes reduce expression of apoptotic genes in PTs and endothelium. The results suggest that systemic delivery of miR-486-5p has therapeutic potential in ischemic AKI.

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CD4 T cell response in AKI

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