Rapamycin Alleviates Hypertriglyceridemia-Related Acute Pancreatitis via Restoring Autophagy Flux and Inhibiting Endoplasmic Reticulum Stress.

Abstract

Hypertriglyceridemia (HTG) can aggravate acute pancreatitis (AP), but its pathogenesis remains unclear. As autophagic activity is closely related to lipid metabolism and AP, we investigated the autophagic response in models of AP aggravated by HTG and explored whether rapamycin has a protective effect against HTG-related pancreatitis. HTG-associated AP models were established in vivo in rats and in vitro. The degree of inflammation, pancreatic injury, the expression of endoplasmic reticulum (ER) stress, and autophagy markers (P62, LC3) were compared. Autophagic flux were assessed using immunostaining, electron microscopy, and immunoblotting. Compared with the normal diet group, the high-fat diet (HFD) AP group exhibited more severe pancreatic injury, apoptosis, and blocked autophagic flux. In addition, the three branches (PERK-eIF2α, ATF-6-GRP78, and IRE1-sXBP1) of the unfolded protein response and mTORC1/S6K1 pathway were activated in HFD AP models. Moreover, the same phenomena were confirmed in vitro in palmitic acid-stimulated pancreatic acinar cells. Preincubation with the mTOR inhibitor rapamycin restored the autophagic flux and markedly reduced the adverse effects of HTG. In conclusion, the autophagic flux is impaired in HFD-induced AP models and is strongly associated with ER stress. Rapamycin could prevent the aggravation of HTG-associated AP via inhibiting mTORC1/S6K1 pathway.