Fatty Acid Ethyl Esters, The Non-Oxidative Ethanol Metabolites, Stimulate Extracellular Matrix Protein Production By Dispersed Pancreatic Acini: Role Of Tgf-Beta.

Background & Aims. Fibrosis is one of the main features of alcoholic pancreatitis but the role of ethanol or its metabolites in this process is unknown. In pancreas, ethanol is mainly metabolized via non-oxidative pathways resulting in production of fatty acid ethyl esters (FAEEs). In this study, we investigated the effect of FAEEs on major extracellolar matrix (ECM) proteins -laminin, collagen and fibronectinin dispersed pancreatic acini and the role ot TGF/7 in regulating these effects. Method~. Rat pancreatic acini were incubated for 1 and 3 h without (control) or with an equimolar mixture of ethyl oleate, ethyl linolaate and ethyl palmitate. Expression of laminin, fibronectin, TGF-~anit TGF-~ receptors I and II was measured by Western blotting and RT-PCR. Collagen expression was assessed by measuring hydroxyproline content and by RT-PCR. Results. FAEEs increased ECM protein content in a dosedependent manner. At 3 hour incubation, 1 mM FAEEs caused 1.9-+0.2 fold significant increase in hydroxyproline content (n = 6) and 4.0and 1.6-fold increase in laminin and flbrouectin, respectively. On RNA level, the expression of a number of ECM proteins was detected in pancreatic acini: laminin ~5, g2, /33 and -y2 chains, fibronectin, and collagens I and II1. Blocking transcription with 10 p.g/ml actinomicin D did not alter the FAEE-induced increase in laminin, suggesting that under these experimental conditions laminin synthesis is regulated at the post-transcriptional level. In agreement with this data, RT-PCR showed no marked upregulation of ECM mRNA expression by FAEEs, except for laminin ~,2. FAEEs increased the level of TGF-,8 precursor as measured by Western blot analysis using a pan TGF-/] antibody. Furthermore, neutralizing TGF-,8 antibody inhibited FAEE-induced increase in laminin, suggesting that this effect be regulated by TGF-fl. TGF-,8 receptors I and II were present in pancreatic acini and their levels were not affected by FAEEs. Conclusion~. FAEEs stimulate expression and production of ECM proteins in rat pancreatic acini. This effect appears to be regulated by TGF-/7. This can be one mechanism mediating fibrosis in alcoholic pancreatitis.