Alteration of C/EBPs and endoplasmic reticulum stress related molecules expression in pancreatic tissues in rats with hypertriglyceridemia related acute pancreatitis

Abstract

Objective To investigate the alteration of C/EBP α, C/EBP β and endoplasmic reticulum stress (ERS) related molecules (IRE1 α and sXBP1) expression in pancreatic tissues in rats with hypertriglyceridemia related acute pancreatitis. Methods Ninety six Sprague Dawley (SD) rats were divided into 4 groups: control group, hypertriglyceridemia (HTG) group (n=24, fed with high fat diet for 2 weeks), AP group (n=24), HTG+ AP group (n=24), and AP was induced by peritoneal injection of cerulein. The rats were sacrificed at 3, 6, 9, 24 h after AP induction, respectively. The pathological changes of the pancreatic tissues were observed and scored by HE staining. Plasma levels of IL-1β, IL-6 and TNF-α weremeasured by ELISA. The expression of IRE1α, sXBP1, C/EBPα, C/EBPβ mRNA were analyzed by real time PCR. The expressions of IRE1α, sXBP1, NF-kB, C/EBPα and C/EBPβ protein were determined by Western Blot. The expressions of C/EBPα and C/EBPβ proteins were also determined by immunohitochemistry. Results After two weeks of high fat diet, serum levels of triglyceride(TG) and total cholesterol (TC) in HTG group, HTG+ AP group were much higher than those of the control group, and the difference was statistically significant (P<0.05). The pancreatic tissue injury was more severe in HTG + AP group, particularly at 9 h (P<0.05). And plasma IL-1β, IL-6 and TNF-α levels were also much higher in HTG+ AP group when compared with that of AP group, the differences were all significant at 9 h (P=0.011; P=0.034; P=0.027). After AP induction, IRE1, sXBP1, C/EBP and C/EBPβ mRNA began to be up-regulated at 3 h, and IRE1 mRNA reached the highest level at 24 h, sXBP1 mRNA at 9 h, while C/EBP and C/EBPβ mRNA reached the highest level at 6 h. Compared with AP group, IRE1, sXBP1, C/EBP and C/EBPβ mRNA levels were much higher in HTG+ AP group. In addition, as to IRE1 and sXBP1 mRNA, the difference was significant at 3, 6, 9, 24 h, and C/EBP mRNA at 6, 9, 24 h, C/EBPβ mRNA at 6 and 9 h (P<0.05). After AP induction, IRE1α, sXBP1 and NF-kB proteins in the pancreatic tissue began to be up-regulated at 3 h, and all reached the highest level at 9 h. IRE1α, sXBP1 and NF-kB proteins were up-regulated more obviously in HTG+ AP group, and the up-regulation in HTG+ AP group was higher than that in AP group, and the high expressions of C/EBPα and C/EBPβ proteins could only be detected at 6 and 9 h in the HTG+ AP group, while there was no expression detected in AP group. Conclusions C/EBPα, C/EBPβ, IRE1α and sXBP1 may be involved in the pathogenesis of HTG related AP, and IRE1α/sXBP1 pathway and C/EBPα, C/EBPβ may mediate the pathologic injury and inflammation process of HTG related AP. Key words: Pancreatitis; C/EBPα; C/EBPβ; Endoplasmic reticulum stress; Hyperlipidemias; Rats