Su1788 Pancreatic Fibrosis in Alcohol-Fed LPS Challenged Mice Is Regulated by the TLR4 Receptor

Abstract

Background: Pancreatic stellate cells (PSCs) play a pivotal role in the pathogenesis of pancreatic fibrosis in chronic pancreatitis (CP) and pancreatic cancer. Secondary diabetes (type 3c diabetes) frequently occurs in advanced CP and pancreatic cancer. In addition, patients with type 2 diabetes also have variable intraand peri-islet fibrosis. Loss of β-cell masses and β-cell dysfunction might play a role in these clinical settings, but the molecular mechanisms linking islet fibrosis, β-cell dysfunction, and β-cell loss remain unknown. We hypothesized that PSCs might play a role in islet fibrosis and alter cell fate in β-cells. Aim: To clarify the role of PSCs in islet fibrosis and the effects of PSCs on β-cell functions. Methods: Expression of α-smooth muscle actin (α-SMA; a marker of activated PSCs) was examined by immunohistochemical staining in the resected specimen of the pancreas from patients undergoing operation for CP or pancreatic cancer. Rat PSCs were isolated from male Wistar rats after perfusion with collagenase P. The RIN-5F rat pancreatic β-cells were mono-cultured or indirectly co-cultured with rat PSCs using culture inserts. Insulin secretion and mRNA expression were examined by the ELISA and real-time PCR, respectively. Cell viability was examined by the MTT assay. Induction of apoptosis was examined by the cytoplasmic histone-associated DNA fragments ELISA and Apoptag® in situ apoptosis detection kit. Activation of caspases 3 and 9 was examined by Western blotting and immunofluorescent staining, respectively. Results: α-SMA-positive activated PSCs were found around and within the fibrotic islets. Expression of insulin was decreased in co-cultured RIN-5F cells than mono-cultured cells. PSCs decreased cell viability and induced apoptosis in RIN-5F cells. These changes were associated with the activation of caspases 3 and 9. Conclusions: PSCs might play a role in the development of islet fibrosis. PSCs decreased insulin expression and induced apoptosis in pancreatic β-cells, suggesting a novel mechanism of diabetes mellitus in diseased pancreas.