l-Cysteine Alleviates Peritoneal Fibrosis by Repressing PKM2 in Peritoneal Mesothelial Cells

Peritoneal fibrosis is one of the main causes of peritoneal dysfunction and withdrawal of patients from peritoneal dialysis (PD). Our previous study has shown that high-glucose dialysis solution promotes glycolysis in peritoneal mesothelial cells, leading to mesothelial-to-mesenchymal transition (MMT) and peritoneal fibrosis. However, the molecular mechanisms remain unclear. Using single-cell RNA sequencing (scRNA-seq) analysis of cells from the effluent of patients undergoing PD from our previous study, we found that pyruvate kinase isozymes M2 (PKM2), a key rate-limiting enzyme of glucose metabolism, was significantly upregulated in the mesothelial cells of patients with long-term peritoneal dialysis (LPD). Using co-immunoprecipitation, chromatin immunoprecipitation assay, and gene silencing techniques, we revealed that PKM2 promotes the expression of transcription factor SNAI2 by acetylating histone H3K9 (H3K9ac), thereby promoting the occurrence of MMT and hence peritoneal fibrosis. l-cysteine, a known PKM2 inhibitor, blocked these responses and prevented PD-induced peritoneal fibrosis. These results could provide a novel therapeutic strategy for treating peritoneal fibrosis.