PDF(Pubmed)
Abstract：
Excessive alcohol intake is a major risk factor for pancreatitis, sensitizing the exocrine pancreas to stressors by mechanisms that remain obscure. Impaired autophagy drives nonalcoholic pancreatitis, but the effects of ethanol (EtOH) and alcoholic pancreatitis on autophagy are poorly understood. Here, we find that ethanol reduces autophagosome formation in pancreatic acinar cells, both in a mouse model of alcoholic pancreatitis induced by a combination of EtOH diet and cerulein (a CCK ortholog) and in EtOH+CCK-treated acinar cells (ex vivo model). Ethanol treatments decreased pancreatic level of LC3-II, a key mediator of autophagosome formation. This was caused by ethanol-induced upregulation of ATG4B, a cysteine protease that, cell dependently, regulates the balance between cytosolic LC3-I and membrane-bound LC3-II. We show that ATG4B negatively regulates LC3-II in acinar cells subjected to EtOH treatments. Ethanol raised ATG4B level by inhibiting its degradation, enhanced ATG4B enzymatic activity, and strengthened its interaction with LC3-II. We also found an increase in ATG4B and impaired autophagy in a dissimilar, nonsecretagogue model of alcoholic pancreatitis induced by EtOH plus palmitoleic acid. Adenoviral ATG4B overexpression in acinar cells greatly reduced LC3-II and inhibited autophagy. Furthermore, it aggravated trypsinogen activation and necrosis, mimicking key responses of ex vivo alcoholic pancreatitis. Conversely, shRNA Atg4B knockdown enhanced autophagosome formation and alleviated ethanol-induced acinar cell damage. The results reveal a novel mechanism, whereby ethanol inhibits autophagosome formation and thus sensitizes pancreatitis, and a key role of ATG4B in ethanol\'s effects on autophagy. Enhancing pancreatic autophagy, particularly by downregulating ATG4B, could be beneficial in mitigating the severity of alcoholic pancreatitis.NEW & NOTEWORTHY Ethanol sensitizes mice and humans to pancreatitis, but the underlying mechanisms remain obscure. Autophagy is important for maintaining pancreatic acinar cell homeostasis, and its impairment drives pancreatitis. This study reveals a novel mechanism, whereby ethanol inhibits autophagosome formation through upregulating ATG4B, a key cysteine protease. ATG4B upregulation inhibits autophagy in acinar cells and aggravates pathological responses of experimental alcoholic pancreatitis. Enhancing pancreatic autophagy, particularly by down-regulating ATG4B, could be beneficial for treatment of alcoholic pancreatitis.
摘要：
过量饮酒是胰腺炎的主要危险因素,通过仍然模糊的机制使外分泌胰腺对应激源敏感。自噬受损导致非酒精性胰腺炎，但乙醇（EtOH）和酒精性胰腺炎对自噬的影响知之甚少。这里,我们发现乙醇能减少胰腺腺泡细胞中自噬体的形成,在EtOH饮食和cerulein（CCK直系同源物）联合诱导的酒精性胰腺炎小鼠模型中以及在EtOHCCK处理的腺泡细胞中（离体模型）。乙醇治疗降低LC3-II的胰腺水平，自噬体形成的关键介质。这是由乙醇诱导的ATG4B上调引起的，一种半胱氨酸蛋白酶，细胞依赖性，调节胞质LC3-I和膜结合的LC3-II之间的平衡。我们显示ATG4B负调节接受EtOH处理的腺泡细胞中的LC3-II。乙醇通过抑制其降解来提高ATG4B水平，增强ATG4B酶活性，并加强了其与LC3-II的相互作用。我们还发现ATG4B的增加和自噬受损在一个不同的,乙醇加棕榈油酸诱导酒精性胰腺炎的非促分泌素模型。腺泡细胞中的腺病毒ATG4B过表达大大降低了LC3-II并抑制了自噬。此外，它加重了胰蛋白酶原的活化和坏死,模拟离体酒精性胰腺炎的关键反应。相反，shRNAAtg4B敲除增强自噬体形成并减轻乙醇诱导的腺泡细胞损伤。结果揭示了一种新的机制，乙醇抑制自噬体形成，从而使胰腺炎敏感，以及ATG4B在乙醇对自噬的影响中的关键作用。增强胰腺自噬,特别是通过下调ATG4B，可能有助于减轻酒精性胰腺炎的严重程度。新与注意乙醇使小鼠和人类对胰腺炎敏感，但是潜在的机制仍然模糊。自噬对维持胰腺腺泡细胞稳态非常重要,它的损伤会导致胰腺炎。这项研究揭示了一种新的机制，乙醇通过上调ATG4B抑制自噬体形成，一种关键的半胱氨酸蛋白酶.ATG4B上调抑制腺泡细胞自噬并加重实验性酒精性胰腺炎的病理反应。增强胰腺自噬,特别是通过下调ATG4B，可能有利于治疗酒精性胰腺炎。
