ERRα transcriptionally activates METRNL, ameliorating cardiomyocyte apoptosis and inflammatory injury in septic cardiomyopathy through the NF-κB/NLRP3 pathway.

Septic cardiomyopathy (SCM) is a prevalent complication among septic patients, accompanied by high mortality. Estrogen-related receptor alpha (ERRα), a transcription factor, is implicated in various cardiovascular diseases. Nonetheless, its role in SCM remains unclear. Here, the cecum ligation and puncture (CLP) procedure was used to construct a mouse sepsis model. We found that the ERRα expression was downregulated in septic hearts. Adeno-associated virus-9 (AAV-9)-mediated cardiomyocyte-specific ERRα overexpression improved the survival rate of septic mice. Additionally, ERRα overexpression ameliorated CLP-induced cardiac dysfunction and myocardial pathological damage. In vitro, HL-1 mouse cardiomyocytes were transduced with an ERRα overexpression adenovirus before LPS stimulation. The results demonstrated that ERRα overexpression mitigated LPS-induced inflammatory cytokines (IL-6, IL-1β, TNF-α, IL-18) and apoptosis (Bax, cleaved caspase-3/9) in HL-1 cells. Mechanistically, ERRα inhibited the NF-κB/NLRP3 inflammasome activation in septic hearts and LPS-stimulated HL-1 cells. Furthermore, we overlapped the differentially expressed genes of septic hearts (GSE125042) and ERRα KO hearts (GSE7196) to identify the downstream target genes. Meteorin like, glial cell differentiation regulator (METRNL) was identified as the target gene of ERRα. Notably, ERRα bound to the METRNL promoter and upregulated its activity, which was confirmed via dual-luciferase reporter assay, ChIP-qPCR, and oligonucleotide pull-down assay. Knockdown of METRNL prevented the effects of ERRα overexpression on the apoptosis and inflammatory response of cardiomyocytes induced by LPS. Our findings underscore the role of ERRα in mitigating myocardial injury in SCM, indicating its potential as a new therapeutic approach.