Autophagy and acute pancreatitis: A novel autophagy theory for trypsinogen activation

Auto-digestion of the pancreas by its own prematurely activated digestive proteases is thought to be an important event in the onset of acute pancreatitis. Although lysosomal hydrolases, such as cathepsin B, play a key role in intrapancreatic trypsinogen activation, it remains unclear where and how trypsinogen meets these lysosomal enzymes. Autophagy is an intracellular bulk degradation system in which cytoplasmic components are directed to the lysosome/vacuole by a membrane-mediated process. To analyze the role of autophagy in acute pancreatitis, we produced a conditional knockout mouse that lacks the autophagy-related (Atg) gene Atg5 in the pancreatic acinar cells. The severity of acute pancreatitis induced by cerulein is greatly reduced in these mice. In addition, Atg5-deficient acinar cells show a significantly decreased level of trypsinogen activation. These data suggest that autophagy exerts a detrimental effect in pancreatic acinar cells by activation of trypsinogen to trypsin. We propose a theory in which autophagy accelerates trypsinogen activation by lysosomal hydrolases under acidic conditions, thus triggering acute pancreatitis in its early stage.

Addendum to: Hashimoto D, Ohmuraya M, Hirota M, Yamamoto A, Suyama K, Ida S, Okumura Y, Takahashi E, Kido H, Araki K, Baba H, Mizushima N, Yamamura K. Involvement of autophagy in trypsinogen activation within the pancreatic acinar cells. J Cell Biol 2008; 181:1065-72.     

Involvement of autophagy in trypsinogen activation within the pancreatic acinar cells

Autophagy is mostly a nonselective bulk degradation system within cells. Recent reports indicate that autophagy can act both as a protector and killer of the cell depending on the stage of the disease or the surrounding cellular environment (for review see Cuervo, A.M. 2004. Trends Cell Biol. 14:70-77). We found that cytoplasmic vacuoles induced in pancreatic acinar cells by experimental pancreatitis were autophagic in origin, as demonstrated by microtubule-associated protein 1 light chain 3 expression and electron microscopy experiments. To analyze the role of macroautophagy in acute pancreatitis, we produced conditional knockout mice lacking the autophagy-related 5 gene in acinar cells. Acute pancreatitis was not observed, except for very mild edema in a restricted area, in conditional knockout mice. Unexpectedly, trypsinogen activation was greatly reduced in the absence of autophagy. These results suggest that autophagy exerts devastating effects in pancreatic acinar cells by activation of trypsinogen to trypsin in the early stage of acute pancreatitis through delivering trypsinogen to the lysosome.     

Pathobiology of experimental acute pancreatitis.

Pancreatic duct obstruction, even in the absence of biliary obstruction and/or bile reflux into the pancreatic duct, can trigger acute hemorrhagic necrotizing pancreatitis. The earliest changes are seen within acinar cells. Early derangements in acinar cell biology include inhibition of digestive enzyme secretion and the co-localization of lysosomal hydrolases with digestive enzyme zymogens. Under appropriate conditions, this co-localization could lead to digestive enzyme activation within acinar cells.     

自噬在胰腺炎中的研究及进展

自噬是广泛存在于真核细胞内的一种溶酶体依赖性降解途径,作为细胞生存的一种机制,在很多生理过程如清除损伤、衰老细胞器以及冗余蛋白上发挥重要作用。自噬在人类胰腺炎的研究最早由Helin等人早在1980年提出,随着不断深入研究,发现自噬在胰腺炎发生发展过程中起主导作用。急性胰腺炎是一种发病率和死亡率极高的疾病,目前表明这种疾病始于胰腺腺泡细胞,主要诊断指标为高淀粉酶血症,胰腺腺泡细胞内消化酶的激活、液泡的大量堆积和炎症因子的聚集,最终胰腺炎症细胞侵润及引起的全身炎症反应导致腺泡细胞的凋亡和坏死,在其发病机制和治疗方面仍需进一步研究探讨。本文综述近年最新研究成果,深入探讨自噬在胰腺炎中的研究及进展。     

Cathepsin B inhibition prevents trypsinogen activation and reduces pancreatitis severity

Intrapancreatic activation of trypsinogen is believed to play a critical role in the initiation of acute pancreatitis, but mechanisms responsible for intrapancreatic trypsinogen activation during pancreatitis have not been clearly defined. In previous in vitro studies, we have shown that intra-acinar cell activation of trypsinogen and acinar cell injury in response to supramaximal secretagogue stimulation could be prevented by the cell permeant cathepsin B inhibitor E64d (Saluja A, Donovan EA, Yamanaka K, Yamaguchi Y, Hofbauer B, and Steer ML. Gastroenterology 113: 304-310, 1997). The present studies evaluated the role of intrapancreatic trypsinogen activation, this time under in vivo conditions, in two models of pancreatitis by using another highly soluble cell permeant cathepsin B inhibitor, L-3-trans-(propylcarbamoyl)oxirane-2-carbonyl-L-isoleucyl-L-proline methyl ester (CA-074me). Intravenous administration of CA-074me (10 mg/kg) before induction of either secretagogue-elicited pancreatitis in mice or duct infusion-elicited pancreatitis in rats markedly reduced the extent of intrapancreatic trypsinogen activation and substantially reduced the severity of both pancreatitis models. These observations support the hypothesis that, during the early stages of pancreatitis, trypsinogen activation in the pancreas is mediated by the lysosomal enzyme cathepsin B. Our findings also suggest that pharmacological interventions that inhibit cathepsin B may prove useful in preventing acute pancreatitis or reducing its severity.     

Expression of human cationic trypsinogen (PRSS1) in murine acinar cells promotes pancreatitis and apoptotic cell death

Hereditary pancreatitis (HP) is an autosomal dominant disease that displays the features of both acute and chronic pancreatitis. Mutations in human cationic trypsinogen (PRSS1) are associated with HP and have provided some insight into the pathogenesis of pancreatitis, but mechanisms responsible for the initiation of pancreatitis have not been elucidated and the role of apoptosis and necrosis has been much debated. However, it has been generally accepted that trypsinogen, prematurely activated within the pancreatic acinar cell, has a major role in the initiation process. Functional studies of HP have been limited by the absence of an experimental system that authentically mimics disease development. We therefore developed a novel transgenic murine model system using wild-type (WT) human PRSS1 or two HP-associated mutants (R122H and N29I) to determine whether expression of human cationic trypsinogen in murine acinar cells promotes pancreatitis. The rat elastase promoter was used to target transgene expression to pancreatic acinar cells in three transgenic strains that were generated: Tg(Ela-PRSS1)NV, Tg(Ela-PRSS1*R122H)NV and Tg(Ela-PRSS1*N29I)NV. Mice were analysed histologically, immunohistochemically and biochemically. We found that transgene expression is restricted to pancreatic acinar cells and transgenic PRSS1 proteins are targeted to the pancreatic secretory pathway. Animals from all transgenic strains developed pancreatitis characterised by acinar cell vacuolisation, inflammatory infiltrates and fibrosis. Transgenic animals also developed more severe pancreatitis upon treatment with low-dose cerulein than controls, displaying significantly higher scores for oedema, inflammation and overall histopathology. Expression of PRSS1, WT or mutant, in acinar cells increased apoptosis in pancreatic tissues and isolated acinar cells. Moreover, studies of isolated acinar cells demonstrated that transgene expression promotes apoptosis rather than necrosis. We therefore conclude that expression of WT or mutant human PRSS1 in murine acinar cells induces apoptosis and is sufficient to promote spontaneous pancreatitis, which is enhanced in response to cellular insult.     

Effects of pancreatic duct ligation on pancreatic response to bombesin

To examine mechanisms that might be related to biliary pancreatitis, we examined the effects of pancreatic duct ligation (PDL) with pancreatic stimulation in vivo. PDL alone caused no increase in pancreatic levels of trypsinogen activation peptide (TAP), trypsin, or chymotrypsin and did not initiate pancreatitis. Although bombesin caused zymogen activation within the pancreas, the increases were slight and it did not cause pancreatitis. However, the combination of PDL with bombesin resulted in prominent increases in pancreatic TAP, trypsin, chymotrypsin, and the appearance of TAP in acinar cells and caused pancreatitis. Disruption of the apical actin network in the acinar cell was observed when PDL was combined with bombesin but not with PDL or bombesin alone. These studies suggest that when PDL is combined with pancreatic acinar cell stimulation, it can promote zymogen activation, the retention of active enzymes in acinar cells, and the development of acute pancreatitis.     

Relationship between NF-kappaB and trypsinogen activation in rat pancreas after supramaximal caerulein stimulation

Intra-acinar cell nuclear factor-kappaB (NF-kappaB) and trypsinogen activation are early events in secretagogue-induced acute pancreatitis. We have studied the relationship between NF-kappaB and trypsinogen activation in rat pancreas. CCK analogue caerulein induces early (within 15 min) parallel activation of both NF-kappaB and trypsinogen in pancreas in vivo as well as in pancreatic acini in vitro. However, NF-kappaB activation can be induced without trypsinogen activation by lipopolysaccharide in pancreas in vivo and by phorbol ester in pancreatic acini in vitro. Stimulation of acini with caerulein after 6 h of culture results in NF-kappaB but not trypsinogen activation. Protease inhibitors (AEBSF, TLCK, and E64d) inhibit both intracellular trypsin activity and NF-kappaB activation in caerulein stimulated acini. A chymotrypsin inhibitor (TPCK) inhibits NF-kappaB activation but not trypsin activity. The proteasome inhibitor MG-132 prevents caerulein-induced NF-kappaB activation but does not prevent trypsinogen activation. These findings indicate that although caerulein-induced NF-kappaB and trypsinogen activation are temporally closely related, they are independent events in pancreatic acinar cells. NF-kappaB activation per se is not required for the development of early acinar cell injury by supramaximal secretagogue stimulation.     

Activation of Soluble Adenylyl Cyclase Protects against Secretagogue Stimulated Zymogen Activation in Rat Pancreaic Acinar Cells

An early feature of acute pancreatitis is activation of zymogens, such as trypsinogen, within the pancreatic acinar cell. Supraphysiologic concentrations of the hormone cholecystokinin (CCK; 100 nM), or its orthologue cerulein (CER), induce zymogen activation and elevate levels of cAMP in pancreatic acinar cells. The two classes of adenylyl cyclase, trans-membrane (tmAC) and soluble (sAC), are activated by distinct mechanisms, localize to specific subcellular domains, and can produce locally high concentrations of cAMP. We hypothesized that sAC activity might selectively modulate acinar cell zymogen activation. sAC was identified in acinar cells by PCR and immunoblot. It localized to the apical region of the cell under resting conditions and redistributed intracellularly after treatment with supraphysiologic concentrations of cerulein. In cerulein-treated cells, pre-incubation with a trans-membrane adenylyl cyclase inhibitor did not affect zymogen activation or amylase secretion. However, treatment with a sAC inhibitor (KH7), or inhibition of a downstream target of cAMP, protein kinase A (PKA), significantly enhanced secretagogue-stimulated zymogen activation and amylase secretion. Activation of sAC with bicarbonate significantly inhibited secretagogue-stimulated zymogen activation; this response was decreased by inhibition of sAC or PKA. Bicarbonate also enhanced secretagogue-stimulated cAMP accumulation; this effect was inhibited by KH7. Bicarbonate treatment reduced secretagogue-stimulated acinar cell vacuolization, an early marker of pancreatitis. These data suggest that activation of sAC in the pancreatic acinar cell has a protective effect and reduces the pathologic activation of proteases during pancreatitis.     

Pancreatic acinar cell-specific autophagy disruption reduces coxsackievirus replication and pathogenesis in vivo

Autophagy protects against many infections by inducing the lysosomal-mediated degradation of invading pathogens. However, previous in?vitro studies suggest that some enteroviruses not only evade these protective effects but also exploit autophagy to facilitate their replication. We generated Atg5(f/f)/Cre(+) mice, in which the essential autophagy gene Atg5 is specifically deleted in pancreatic acinar cells, and show that coxsackievirus B3 (CVB3) requires autophagy for optimal infection and pathogenesis. Compared to Cre(-) littermates, Atg5(f/f)/Cre(+) mice had an ～2,000-fold lower CVB3 titer in the pancreas, and pancreatic pathology was greatly diminished. Both in?vivo and in?vitro, Atg5(f/f)/Cre(+) acinar cells had reduced intracellular viral RNA and?proteins. Furthermore, intracellular structural elements induced upon CVB3 infection, such as compound membrane vesicles and highly geometric paracrystalline arrays, which may represent viral replication platforms, were infrequently observed in?infected Atg5(f/f)/Cre(+) cells. Thus, CVB3-induced subversion of autophagy not only benefits the virus but also exacerbates pancreatic pathology.     

Intracellular proteolysis of pancreatic zymogens.

Activation of pancreatic digestive zymogens within the pancreatic acinar cell may be an early event in the development of pancreatitis. To detect such activation, an immunoblot assay has been developed that measures the relative amounts of inactive zymogens and their respective active enzyme forms. Using this assay, high doses of cholecystokinin or carbachol were found to stimulate the intracellular conversion of at least three zymogens (procarboxypeptidase A1, procarboxypeptidase B, and chymotrypsinogen 2) to their active forms. Thus, this conversion may be a generalized phenomenon of pancreatic zymogens. The conversion is detected within ten minutes of treatment and is not associated with changes in acinar cell morphology; it has been predicted that the lysosomal thiol protease, cathepsin B, may initiate this conversion. Small amounts of cathepsin B are found in the secretory pathway, and cathepsin B can activate trypsinogen in vitro; however, exposure of acini to a thiol protease inhibitor (E64) did not block this conversion. Conversion was inhibited by the serine protease inhibitor, benzamidine, and by raising the intracellular pH, using chloroquine or monensin. This limited proteolytic conversion appears to require a low pH compartment and a serine protease activity. After long periods of treatment (60 minutes), the amounts of the active enzyme forms began to decrease; this observation suggested that the active enzyme forms were being degraded. Treatment of acini with E64 reduced this late decrease in active enzyme forms, suggesting that thiol proteases, including lysosomal hydrolases, may be involved in the degradation of the active enzyme forms. These findings indicate that pathways for zymogen activation as well as degradation of active enzyme forms are present within the pancreatic acinar cell.     

Pancreatic secretory trypsin inhibitor I reduces the severity of chronic pancreatitis in mice overexpressing interleukin-1β in the pancreas

IL-1β is believed to play a pathogenic role in the development of pancreatitis. Expression of human IL-1β in pancreatic acinar cells produces chronic pancreatitis, characterized by extensive intrapancreatic inflammation, atrophy, and fibrosis. To determine if activation of trypsinogen is important in the pathogenesis of chronic pancreatitis in this model, we crossed IL-1β transgenic [Tg(IL1β)] mice with mice expressing a trypsin inhibitor that is normally produced in rat pancreatic acinar cells [pancreatic secretory trypsin inhibitor (PTSI) I]. We previously demonstrated that transgenic expression of PSTI-I [Tg(Psti1)] increased pancreatic trypsin inhibitor activity by 190%. Tg(IL1β) mice were found to have marked pancreatic inflammation, characterized by histological changes, including acinar cell loss, inflammatory cell infiltration, and fibrosis, as well as elevated myeloperoxidase activity and elevated pancreatic trypsin activity, as early as 6 wk of age. In contrast to Tg(IL1β) mice, pancreatitis was significantly less severe in dual-transgenic [Tg(IL1β)-Tg(Psti1)] mice expressing IL-1β and PSTI-I in pancreatic acinar cells. These findings indicate that overexpression of PSTI-I reduces the severity of pancreatitis and that pancreatic trypsin activity contributes to the pathogenesis of an inflammatory model of chronic pancreatitis.     

Endoplasmic Reticulum Stress Is Chronically Activated in Chronic Pancreatitis

The pathogenesis of chronic pancreatitis (CP) is poorly understood. Endoplasmic reticulum (ER) stress has now been recognized as a pathogenic event in many chronic diseases. However, ER stress has not been studied in CP, although pancreatic acinar cells seem to be especially vulnerable to ER dysfunction because of their dependence on high ER volume and functionality. Here, we aim to investigate ER stress in CP, study its pathogenesis in relation to trypsinogen activation (widely regarded as the key event of pancreatitis), and explore its mechanism, time course, and downstream consequences during pancreatic injury. CP was induced in mice by repeated episodes of acute pancreatitis (AP) based on caerulein hyperstimulation. ER stress leads to activation of unfolded protein response components that were measured in CP and AP. We show sustained up-regulation of unfolded protein response components ATF4, CHOP, GRP78, and XBP1 in CP. Overexpression of GRP78 and ATF4 in human CP confirmed the experimental findings. We used novel trypsinogen-7 knock-out mice (T^−/−), which lack intra-acinar trypsinogen activation, to clarify the relationship of ER stress to intra-acinar trypsinogen activation in pancreatic injury. Comparable activation of ER stress was seen in wild type and T^−/− mice. Induction of ER stress occurred through pathologic calcium signaling very early in the course of pancreatic injury. Our results establish that ER stress is chronically activated in CP and is induced early in pancreatic injury through pathologic calcium signaling independent of trypsinogen activation. ER stress may be an important pathogenic mechanism in pancreatitis that needs to be explored in future studies.     

Protection from pancreatitis by the zymogen granule membrane protein integral membrane-associated protein-1

Pancreatitis is a common disease with substantial morbidity and mortality. To better understand the mechanisms conferring sensitivity or resistance to pancreatitis, we have initiated the analysis of novel acinar cell proteins. Integral membrane-associated protein-1 (Itmap1) is a CUB (complement subcomponents C1r/C1s, sea urchin Uegf protein, bone morphogenetic protein-1) and zona pellucida (ZP) domain-containing protein we find prominently expressed in pancreatic acinar cells. Within the acinar cell, Itmap1 localizes to zymogen granule membranes. Although roles in epithelial polarity, granule assembly, and mucosal protection have been postulated for CUB/ZP proteins, in vivo functions for these molecules have not been proven. To determine the function of Itmap1, we generated Itmap1-deficient mice. Itmap1(-/-) mice demonstrate increased severity of secretagogue- and diet-induced pancreatitis in comparison to Itmap1(+/+) mice. In contrast to previous animal models exhibiting altered severity of pancreatitis, Itmap1 deficiency results in impaired activation of trypsin, an enzyme believed critical for initiating a cascade of digestive zymogen activation during pancreatitis. Itmap1 deficiency does not alter zymogen granule size, appearance, or the composition of zymogen granule contents. Our results demonstrate that Itmap1 plays an essential role in trypsinogen activation and that both impaired and augmented trypsinogen activation can be associated with increased severity of pancreatitis.     

Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses

Clinical studies indicate that cigarette smoking increases the risk for developing acute pancreatitis. The nicotine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a major cigarette smoke toxin. We hypothesized that NNK could sensitize to pancreatitis and examined its effects in isolated rat pancreatic acini and in vivo. In acini, 100 nM NNK caused three- and fivefold activation of trypsinogen and chymotrypsinogen, respectively, above control. Furthermore, NNK pretreatment in acini enhanced zymogen activation in a cerulein pancreatitis model. The long-term effects of NNK were examined in vivo after intraperitoneal injection of NNK (100 mg/kg body wt) three times weekly for 2 wk. NNK alone caused zymogen activation (6-fold for trypsinogen and 2-fold for chymotrypsinogen vs. control), vacuolization, pyknotic nuclei, and edema. This NNK pretreatment followed by treatment with cerulein (40 μg/kg) for 1 h to induce early pancreatitis responses enhanced trypsinogen and chymotrypsinogen activation, as well as other parameters of pancreatitis, compared with cerulein alone. Potential targets of NNK include nicotinic acetylcholine receptors and β-adrenergic receptors; mRNA for both receptor types was detected in acinar cell preparations. Studies with pharmacological inhibitors of these receptors indicate that NNK can mediate acinar cell responses through an nonneuronal α(7)-nicotinic acetylcholine receptor (α(7)-nAChR). These studies suggest that prolonged exposure to this tobacco toxin can cause pancreatitis and sensitize to disease. Therapies targeting NNK-mediated pathways may prove useful in treatment of smoking-related pancreatitis.     

Presence of cathepsin B in the human pancreatic secretory pathway and its role in trypsinogen activation during hereditary pancreatitis

The lysosomal cysteine protease cathepsin B is thought to play a central role in intrapancreatic trypsinogen activation and the onset of experimental pancreatitis. Recent in vitro studies have suggested that this mechanism might be of pathophysiological relevance in hereditary pancreatitis, a human inborn disorder associated with mutations in the cationic trypsinogen gene. In the present study evidence is presented that cathepsin B is abundantly present in the secretory compartment of the human exocrine pancreas, as judged by immunogold electron microscopy. Moreover, pro-cathepsin B and mature cathepsin B are both secreted together with trypsinogen and active trypsin into the pancreatic juice of patients with sporadic pancreatitis or hereditary pancreatitis. Finally, cathepsin B- catalyzed activation of recombinant human cationic trypsinogen with hereditary pancreatitis-associated mutations N29I, N29T, or R122H were characterized. In contrast to a previous report, cathepsin B-mediated activation of wild type and all three mutant trypsinogen forms was essentially identical under a wide range of experimental conditions. These observations confirm the presence of active cathepsin B in the human pancreatic secretory pathway and are consistent with the notion that cathepsin B-mediated trypsinogen activation might play a pathogenic role in human pancreatitis. On the other hand, the results clearly demonstrate that hereditary pancreatitis-associated mutations do not lead to increased or decreased trypsinogen activation by cathepsin B. Therefore, mutation-dependent alterations in cathepsin B-induced trypsinogen activation are not the cause of hereditary pancreatitis.     

Differential effects of saralasin and ramiprilat,the inhibitors of renin-angiotensin system,on cerulein-induced acute pancreatitis

Acute pancreatitis is an inflammatory disease characterized by pancreatic tissue edema, acinar cell necrosis, hemorrhage and inflammation of the damaged gland. It is believed that acinar cell injury is initiated by the activation of digestive zymogens inside the acinar cells, leading finally to the autodigestion of the pancreas. Previous study in our laboratory demonstrated that cerulein-induced acute pancreatitis was associated with an up-regulation of local renin-angiotensin system (RAS) in rat pancreas. Therefore, the utilization of RAS inhibitors may provide a novel and alternative treatment for acute pancreatitis. By means of a rat model of cerulein-induced acute pancreatitis, results from the present study showed that an intravenous injection of saralasin, an antagonist for angiotensin II receptors, at a dose of 40 microg/kg 30 min before the induction of acute pancreatitis significantly attenuated pancreatic edema. Results from the biochemical measurements showed that pretreatment with saralasin at a dose of 20 microg/kg markedly reduced pancreatic injury, as evidenced by the decreased activities of alpha-amylase and lipase in plasma. However, the same recipe of ramiprilat, a specific inhibitor for angiotensin-converting enzyme, at a dose of 20 microg/kg did not provide any protective effect against acute pancreatitis. On the contrary, pretreatment with ramiprilat at a dose 40 microg/kg enhanced cerulein-induced pancreatic injury. Results from histopathological analysis of these RAS inhibitors further confirmed with those results as obtained from biochemical analysis. These data indicate that administration of saralasin but not ramiprilat could be protective against acute pancreatitis and that activation of pancreatic RAS in acute pancreatitis may play a role in pancreatic tissue injury.     

Simvastatin induces autophagic flux to restore cerulein-impaired phagosome-lysosome fusion in acute pancreatitis

BackgroundDuring pancreatitis, autophagy is activated, but lysosomal degradation of dysfunctional organelles including mitochondria is impaired, resulting in acinar cell death. Retrospective cohort analyses demonstrated an association between simvastatin use and decreased acute pancreatitis incidence.MethodsWe examined whether simvastatin can protect cell death induced by cerulein and the mechanisms involved during acute pancreatitis. Mice were pretreated with DMSO or simvastatin (20 mg/kg) for 24 h followed by 7 hourly cerulein injections and sacrificed 1 h after last injection to harvest blood and tissue for analysis.ResultsPancreatic histopathology revealed that simvastatin reduced necrotic cell death, inflammatory cell infiltration and edema. We found that cerulein triggered mitophagy with autophagosome formation in acinar cells. However, autophagosome-lysosome fusion was impaired due to altered levels of LAMP-1, AMPK and ULK-1, resulting in autophagosome accumulation (incomplete autophagy). Simvastatin abrogated these effects by upregulating LAMP-1 and activating AMPK which phosphorylated ULK-1, resulting in increased formation of functional autolysosomes. In contrast, autophagosomes accumulated in control group during pancreatitis. The effects of simvastatin to promote autophagic flux were inhibited by chloroquine. Mitochondria from simvastatin-treated mice were resistant to calcium overload compared to control, suggesting that simvastatin induced mitochondrial quality control to eliminate susceptible mitochondria. Clinical specimens showed a significant increase in cell-free mtDNA in plasma during pancreatitis compared to normal controls. Furthermore, genetic deletion of parkin abrogated the benefits of simvastatin.ConclusionOur findings reveal the novel role of simvastatin in enhancing autophagic flux to prevent pancreatic cell injury and pancreatitis.