Acetaldehyde increases endogenous adiponectin and fibrogenesis in hepatic stellate cells but exogenous adiponectin inhibits fibrogenesis

Background: Adiponectin has antifibrogenic properties. Acetaldehyde, the principal metabolite of ethanol, is known to stimulate the expression of type I collagen genes and the production of type I collagen by wild-type (wt) but not by obese gene (ob/ob) stellate cells. The aim of this study was to determine the expression of adiponectin in activated stellate cells obtained from wt and ob/ob mice and to determine the effects of acetaldehyde on adiponectin in relation to the expression of type I collagen. Methods: Stellate cells were isolated from wt and ob/ob mice by perfusion of the portal vein and cultured. Cell adiponectin was visualized by immunohistochemistry and confocal microscopy and determined by radioimmunoassay and by western blot. Adiponectin mRNA and α₁(I) collagen mRNA were determined by quantitative real time polymerase chain reaction. Results: Adiponectin levels were similar in wt and ob/ob stellate cells. Adiponectin receptor 2 mRNA (AdipoR2 mRNA) and AdipoR2 immunoprotein were higher in ob/ob than in wt stellate cells (p < 0.01). Acetaldehyde (200 μM) increased adiponectin both in wt and in ob/ob stellate cells (p < 0.05), but increased AdipoR2 immunoprotein only in ob/ob stellate cells (p < 0.01). However, in the presence of leptin, acetaldehyde decreased adiponectin in ob/ob stellate cells (p < 0.01). Acetaldehyde enhanced α₁(I) collagen mRNA in wt (p < 0.05), but decreased it in ob/ob stellate cells (p < 0.01). Leptin abrogated the effect of acetaldehyde in decreasing α₁(I) collagen mRNA in ob/ob stellate cells (p < 0.01). Adiponectin inhibited α₁(I) collagen mRNA in the basal state in wt stellate cells or when enhanced by acetaldehyde. Conclusions: Adiponectin and adiponectin receptor are present in activated stellate cells. Adiponectin has a negative regulatory role on the enhancing effect of acetaldehyde on fibrogenesis in alcoholic liver disease.