The Effect Of Autophagy On Acute Pancreatitis

BackgroudAcute pancreatitis is an acute inflammatory disease, it is a common acute abdominaldisease, the mechanism is still unclear. The severity of the disease varies widely from mildacute pancreatitis only affecting the pancreas to acute pancreatitis with systemic infam-matory response syndrome and death. The mortality of all acute pancreatitis is about5%,but the mortality of patients with severe necrotizing pancreatitis is approximately35~50%. Recent years, there have been signifcant advances in the supportive care in dealingwith complications of severe acute pancreatitis. However, the mortality of severe acutepancreatitis is of little decrease, the reasons may be that treatments we design are oftenfollowing clinical symptoms. Most researchers now believe that the abnormal activation ofenzymogen in the pancreas cell is the cause of acute pancreatitis, however, how is theenzymogen activated in the pancreas cell? it is not clear. A series of experimentsconfirmed that autophagy played an important role in enzymogen activation. Doesautophagy have protective or damage effect? Yet there is a big controversy.ObjectiveTo study the role of autophagy in pathogenesis of acute pancreatitis. Methods1, C57mice are given hourly intraperitoneal injections of saline containing50μg/kgcerulein for7times,1h after the last injection, mice are killed, serum amylase andpercentage of water content are detected, pancreatic tissue pathological scores are tested,Electron microscope and Western-blot analysis are performed on pancreatic tissue totested autophagy, comparing with normal and fasting groups.2, AR42J cells are incubatedin F12k medium in the presence of cerulein to induce acute pancreatic cell model,Western-blot analysis and immunofluorescence are performed to tested autophagy.3.AR42J cells are incubated in F12k medium in the presence or absence of3-methyladenine,chloroquine, E64D and cerulein, respectively. Cytotoxicity, cytoactive and apoptosis ofAR42J cells are detected, respectively.4, AR42J cells are incubated in F12k medium inthe presence or absence of3-methyladenine, chloroquine, E64D and cerulein, respectively.Trypsin activity of AR42J cells is detected by BZiPAR(fluorescent substrate for trypsin).5,C57mice are given hourly intraperitoneal injections of saline containing50μg/kg ceruleinfor1to7times, respectively, in order to induce several degrees of severity of the acutepancreatitis, and autophagy is tested by Western-blot analysis, then the relationshipbetween autophagy and the severity of acute pancreatitis is observed.Result1. Cerulein-induced pancreatitis by hourly intraperitoneal injections for7times，is quitesimilar to the early phrase of AP in humans. The number of autophagy increases andautophagies containing zymogen granules are observed in acinar cell of pancreatitis.2,AR42J cells hyperstimulated with cerulein cause autophagy increasing and autophagicdysfunction.3, Cerulein does not directly cause AR42J cells necrosis or apoptosis, incontrast, proliferation of AR42J cells is observed, and when autophagy is inhibited, theproliferation of AR42J cells is inhibited, too.4, AR42J cells hyperstimulated with ceruleincause activation of trypsinogen, the activation can be inhibited by3-MA, in addition, toprolong time of AR42J cells hyperstimulated with cerulein is not to increases activation oftrypsinogen.5, Autophagic dysfunction is associated with the serious degree of acutepancreatitis, the more serious acute pancreatitis is, the more obvious Autophagic dysfunction is.ConclusionOur studies confirm that autophagic dysfunction can cause activation of trypsinogen inAR42J cells or acinar cells of pancreas. Incubating with cerulein can not make AR42Jcells necrotizing or apoptosis, in contrast, cerulein-induced pancreatitis in vivo, necrosisis observed in pancreas, and there is positive link between autophagic dysfunction and theserious degree of acute pancreatitis. We speculate that autophagic dysfunction is a earlyevents in pancreatitis, when autophagic function is impaired, a reaction-unknown istriggered to damage pancreas.