Metformin attenuated sepsis-related liver injury by modulating the DNA methylation and hydroxymethylation landscape

Sepsis-associated liver injury (SLI) is a common complication of sepsis, for which effective therapeutic strategies are lacking. DNA methylation and hydroxymethylation play crucial roles in the regulation of gene expression. This study investigated the effects of metformin on the DNA methylation landscape in a rat model of cecal ligation and puncture (CLP)-induced SLI. Reduced representation bisulfite sequencing (RRBS) and oxidative RRBS (ox-RRBS) were used to assess global DNA methylation and hydroxymethylation patterns in the liver tissues. The results showed that CLP-induced SLI was associated with global DNA hypomethylation and hyperhydroxymethylation, which were partially reversed by metformin treatment. The expression levels of DNA methyltransferases and ten-eleven translocation 2 (TET2) were elevated in the CLP group and were modulated by metformin. Functional enrichment analysis of differentially methylated and hydroxymethylated genes revealed their involvement in oxidative phosphorylation and metabolic pathways. Furthermore, integration of DNA methylation, hydroxymethylation, and transcriptome data identified two genes, A1cf and Atxn7l1, that exhibited increased methylation and decreased expression in CLP, which were reversed by metformin treatment. These findings provide novel insights into the epigenetic mechanisms underlying SLI and suggest that metformin exerts hepatoprotective effects by modulating DNA methylation and hydroxymethylation.