Genetic deletion of histone deacetylase 6 prevents peritoneal fibrosis via suppression of heat shock protein 90 deacetylation

Abstract Peritoneal fibrosis (PF) is a serious complication contributing to ultrafiltration failure in patients undergoing peritoneal dialysis that currently lacks effective treatment strategies. Our recent studies highlighted the key role of histone deacetylase 6 (HDAC6) in the development of PF. To better understand the mechanisms underlying the involvement of HDAC6 in PF, we conducted in vivo experiments using Hdac6 KO mice and in vitro studies using human peritoneal mesothelial cells (HPMCs). Our results demonstrated that HDAC6 gene silencing improved PF and angiogenesis in vivo and altered pathological phenotypes in vitro . In Hdac6 KO mice, the key pathways regulating extracellular matrix accumulation, angiogenesis, and secretion of inflammatory cytokines (including TGFB1/SMAD3, HIF‐1α/VEGFR‐2/MAPK3/MAPK1, and TLR4/NF‐κB pathways) were inhibited. We also identified heat shock protein 90 (HSP90) as the substrate of HDAC6 in both PF mice and HPMCs and demonstrated that HDAC6 exerted its regulatory function in PF through the deacetylation of HSP90. Overall, our study provides novel insights into the critical role of the HDAC6‐HSP90 interplay in PF using Hdac6 KO mice. We identify HSP90 as an essential substrate through which HDAC6 exerts its function in PF, providing an experimental basis for the development of novel therapeutic strategies. © 2025 The Pathological Society of Great Britain and Ireland.