Histone deacetylase 6 inhibition counteracts the epithelial-mesenchymal transition of peritoneal mesothelial cells and prevents peritoneal fibrosis

The role of histone deacetylase 6 (HDAC6) in peritoneal fibrosis remains unknown. In this study, we examined the effect of HDAC6 inhibition on the epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells and development of peritoneal fibrosis. Treatment with tubastatin A, a highly selective HDAC6 inhibitor, or silencing of HDAC6 with siRNA inhibited transforming growth factor β1-induced EMT, as evidenced by decreased expression of α-smooth muscle actin, collagen I and preserved expression of E-cadherin in cultured human peritoneal mesothelial cells. In a mouse model of peritoneal fibrosis induced by high glucose dialysate, administration of TA prevented thickening of the submesothelial region and decreased expression of collagen I and α-SMA. Mechanistically, tubastatin A treatment inhibited expression of TGF-β1 and phosphorylation of Smad-3, epidermal growth factor receptor, STAT3, and NF-κBp65. HDAC6 inhibition also suppressed production of multiple inflammatory cytokines/chemokines and reduced the infiltration of macrophages to the injured peritoneum. Moreover, tubastatin A was effective in inhibiting peritoneal increase of CD31(+) blood vessels and expression of vascular endothelial growth factor in the injured peritoneum. Collectively, these results suggest that HDAC6 inhibition can attenuate peritoneal fibrosis by inhibiting multiple pro-fibrotic signaling pathways, EMT, inflammation and blood vessel formation.