A histone deacetylase inhibitor, trichostatin A, suppresses myofibroblastic differentiation of rat hepatic stellate cells in primary culture

Hepatic stellate cells are the major cellular sources of extracellular matr ix in chronic liver diseases leading to fibrosis, We explored the antifibro genic effect of two histone deacetylase inhibitors, sodium butyrate and tri chostatin A (TSA), on this cell type in vitro, Primary hepatic stellate cel ls as well as culture activated cells were exposed to butyrate (0.01-1 mmol /L) or TSA (1-100 nmol/L); their effect on collagen types I and III and smo oth muscle ol-actin was examined by quantitative immunoprecipitation and by Northern analysis. Their antiproliferative effect was examined by H-3-thym idine incorporation and cell counting, Hyperacetylation of histones was dem onstrated by acid urea/Triton-X-100 (AUT) polyacrylamide gel electrophoresi s. Possible cytotoxic effects were judged on stellate cells by evaluating d e novo total protein synthesis, and on hepatocytes by measuring lactate deh ydrogenase (LDH) leakage, albumin secretion, and epoxide hydrolase and etho xycoumarin O-deethylase activity, TSA at 100 nmol/L and butyrate at 1 mmol/ L retarded the morphological changes characteristic for activation of prima ry stellate cells. TSA at 100 nmol/L inhibited synthesis of collagen types I and III and smooth muscle alpha-actin by 62%, 70%, and 88%, Butyrate at 1 mmol/L showed a modest inhibitory effect on collagen type III and smooth m uscle alpha-actin, but had no effect on collagen type I. Northern analysis suggested that these inhibitory effects on collagen type III and smooth mus cle alpha-actin were transcriptional, while the effect on collagen type I w as largely posttranscriptional, At 100 nmol/L, TSA strongly suppressed prol iferation of primary hepatic stellate cells. Inhibition of activation of st ellate cells was preceded by hyperacetylation of histone H4, When tested on cells at day 14 in culture, butyrate had no inhibitory effects on the synt hesis of collagens or smooth muscle alpha-actin. One hundred or 10 nmol/L T SA modestly inhibited the synthesis of collagens type I (-24%,-22%) and III (-34%,-22%), and smooth muscle alpha-actin (-27%,-12%). We conclude that T SA inhibits transdifferentiation of stellate cells into myofibroblasts by i nterfering with the level of acetylation of histone H4.