Description
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- 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.
Overall Design
C57BL6/J WT and CD4Keap1 KO mice were assigned to control and ischemia reperfusion injury (IRI) groups. RNA was isolated 24h after the surgery and kidney CD4 T cells flow sorted for RNA-seq analysis. There were 12 samples comprising 4 biologic classes of three replicates each, and experimental samples were compared to controls.
Curator
hy_li