Abstract

BACKGROUND
Pancreatic stellate cells (PSCs) are known to be related to pancreatic inflammation and fibrosis, and are the result of extracellular matrix(ECM) protein synthesis. Recent studies have shown that blockade of the renin-angiotensin system (RAS) attenuated pancreatic inflammation and fibrosis. However, there is little data relating to high glucose (HG) and its effects on PSCs. We investigated the effects of HG on ECM protein and angiotensin II(AT II) in PSCs. METHODS: Isolated PSCs were cultured in HG(D-glucose 5.5(LG), 27.8 mM(HG)) medium. The levels of AT II and TGF-beta were measured using radioimmunoassay, and the AT II-stained cells counted. RT-PCR for the AT II receptor subtypes and Western blot analyses for the expressions of ECM proteins, such as connective tissue growth factor(CTGF) and collagen type IV, were performed. The AT II receptor antagonist, candesartan(10micrometer), and angiotensin converting enzyme inhibitor, ramiprilat(100nM) treatedments were also used. RESULTS: The thymidine uptake of the PSCs increased 4 times in the HG culture. The AT II levels(LG vs. HG, 17.1+/-4.9 vs. 36.0+/-.2pg/mL, P<0.05) and AT II-stained PSCs (LG vs. HG, 22.5+/-2.0 vs. 39.3+/-11.0%, P<0.05) were significantly increased after 6 hrs under HG conditions. The TGF-beta concentration was also significantly higher under HG conditions(LG vs. HG, 436.3+/-69.0 vs. 1115.1+/-434.0pg/mL, P<0.05) after 72 hrs. After 72 hrs, the protein expressions of CTGF and collagen type IV under HG conditions were significantly increased and effectively attenuated by the candesartan and ramiprilat treatments. CONCLUSION: A high glucose concentration could significantly increased PSCs proliferation, which also correlated with the AT II production. Consequently, PSCs proliferation was caused by HG induced ECM protein synthesis, and was attenuated by the AT II receptor antagonist. Therefore, pancreatic inflammation and fibrosis could be aggravated by hyperglycemia, and AT II might play an important role in the pathogenesis.