The interaction between C/EBPβ and TFAM promotes acute kidney injury via regulating NLRP3 inflammasome-mediated pyroptosis

Sepsis-induced inflammatory damage is a crucial cause of acute kidney injury (AKI), and AKI is an ecumenical fearful complication in approximately half of patients with sepsis. CCAAT/enhancer-binding protein beta (C/EBP beta) plays roles in regulating acute phase responses and inflammation. However, the role and mechanism of C/EBP beta in AKI are unclear. LPS combined with ATP-treated renal epithelial cells HK2 and cecal ligation-peferation (CLP)mice were used as models of AKI in vitro and in vivo. Cell damage, the secretion of interleukin-1 beta (IL-1 beta), IL-18 and cysteinyl aspartate specific proteinase 1 (caspase-1) activity were tested by LDH, ELISA assay and flow cytometry analysis, respectively. The expression levels of TFAM, C/EBP beta, and pyroptosis-related molecules were tested by qRT-PCR and Western blotting. Chromatin immunoprecipitation (ChIP) assessed the interaction between C/EBP beta with TFAM. Hematoxylin-Eosin (H&E) staining detected pathological changes of kidney tissues, and immunohistochemistry measured TFAM and C/EBP beta in mice kidney tissues. C/EBP beta or TFAM were up-regulated in LPS combined with ATP-induced HK2 cells. Knockdown of C/EBP beta could suppress cell injury and the secretion of IL-1 beta and IL-18 induced by LPS combined with ATP. Furthermore, C/EBP beta up-regulated the expression levels of TFAM via directly binding to TFAM promoter. Overexpression of TFAM reversed the effects of C/EBP beta deficiency on pyroptosis. Knockdown of C/EBP beta could inhibit NLRP3 inflammasome-mediated caspase-1 signaling pathway by inactivating TFAM/RAGE pathway. It was further confirmed in the AKI mice that C/EBP beta and TFAM promoted AKI by activating NLRP3-mediated pyroptosis. The interaction of between C/EBP beta and TFAM facilitated pyroptosis by activating NLRP3/caspase-1 signal axis, thereby promoting the occurrence of AKI.