Lysosomal Damage, Impaired Autophagy, and Alcoholic Pancreatitis

溶酶体损伤、自噬受损和酒精性胰腺炎

• 批准号: 8606720
• 负责人: ILYA GUKOVSKY
• 金额: $ 29.73万
• 依托单位: BRENTWOOD BIOMEDICAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-02-01 至 2016-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8606720
• 关键词: Acinar Cell; Acute; Affect; Alcohol abuse; Alcoholic Pancreatitis; Alcohols; Autophagocytosis; Autophagosome; Cathepsins; Cholecystokinin; Data; Disease; Dose; Endotoxemia; Ethanol; Ethanol toxicity; Event; Exocrine pancreas; Experimental Models; Functional disorder; Genetic; Goals; Golgi Apparatus; Human; Hydrolase; Impairment; In Vitro; Knock-out; LAMP-2; Lead; Life; Lysosomes; Mediating; Mediator of activation protein; Membrane Proteins; Mitochondria; Modeling; Mus; Organ; Organelles; Pancreas; Pancreatitis; Pathogenesis; Pathologic; Pathway interactions; Process; Proteins; Rattus; Resolution; Risk Factors; Rodent; Role; Sincalide; Stress; Testing; Trypsin; Trypsinogen; Vacuole; acute pancreatitis; alcohol effect; analog; base; feeding; in vivo; insight; late endosome; mouse model; new therapeutic target; non-alcoholic; novel; novel therapeutic intervention; overexpression; public health relevance; response; stressor; trafficking

DESCRIPTION (provided by applicant): Pancreatitis is a potentially fatal disease of exocrine pancreas the pathogenesis of which remains obscure and for which no specific treatment has been developed. Alcohol abuse is a major etiologic factor for pancreatitis; however, the mechanisms by which alcohol predisposes to this disease remain elusive. Here we propose a novel hypothesis for the pathogenesis of alcoholic pancreatitis stating that a combination of two events is critical for pancreatitis: 1) induction of autophagy and 2) impaired lysosomal function which makes autophagy defective. Autophagy (a.k.a. macroautophagy) is the main cellular degradative, lysosome-driven process. Our recent study has revealed a profound impairment of autophagy in experimental models of nonalcoholic acute pancreatitis. We found that autophagy is activated but its progression/resolution is impaired. Autophagy impairment is caused by lysosomal dysfunction a prominent manifestation of which is defective processing/maturation of cathepsins, major lysosomal hydrolases. Further, our findings revealed that impaired autophagy mediates 2 key pathologic responses of pancreatitis: acinar cell vacuolation and intra- acinar trypsinogen activation. Our results indicate that ethanol feeding alone causes lysosomal dysfunction in pancreas similar to that we found in nonalcoholic pancreatitis. However, ethanol per se does not induce pancreatitis because it does not activate autophagy. Thus, in conditions of basal unstimulated autophagy, the consequences of ethanol- induced lysosomal dysfunction are limited. However, a combination of ethanol feeding, which causes lysosomal dysfunction, and stresses that induce autophagy leads to defective autophagy and thus pancreatitis. Our results suggest that this is the mechanism through which ethanol feeding "sensitizes" rats or mice to pancreatitis induced by low-dose cerulein (CR; a CCK-8 analog) that by itself does not elicit pancreatitis. We propose that similar mechanism mediates pancreatitis induced by the combination of ethanol feeding and endotoxemia (i.e., LPS), the other available "in vivo sensitization" model of alcoholic pancreatitis. Our results indicate that ethanol causes dysregulation of endolysosomal trafficking and the Golgi, associated with defective processing and activity of cathepsins and decreased level of LAMP-2, a major lysosomal membrane protein. We further propose that manipulating the level of autophagy (by, respectively, inhibiting autophagy through Atg5 knockout or stimulating it through overexpression of Atg8/LC3, a critical autophagy mediator) ameliorates or worsens alcoholic pancreatitis. The Specific Aims for the project are: 1. Determine the effects of ethanol feeding alone and experimental alcoholic pancreatitis (i.e., ethanol feeding combined with low-dose CR or LPS) on lysosomal dysfunction in pancreas, and the role of LAMP-2 in these effects. 2. Determine the effects of ethanol feeding alone and experimental alcoholic pancreatitis on endolysosomal trafficking and the Golgi. 3. Determine the effects of ethanol feeding alone and experimental alcoholic pancreatitis on autophagy induction and progression, and the role of LAMP-2 in these effects. 4. Determine the effects of genetically inhibiting or stimulating autophagy on alcoholic pancreatitis. The proposed studies elucidate ethanol's effects on lysosomes, the Golgi, and autophagy in pancreas; suggest a new model for alcoholic pancreatitis; and indicate novel targets for therapeutic approaches to treat or mitigate this disease. Further, similar mechanisms involving ethanol-induced lysosomal dysfunction may mediate alcohol toxicity to other organs.

描述(申请人提供)：胰腺炎是一种潜在的致命的胰腺外分泌疾病，其发病机制仍不清楚，目前还没有专门的治疗方法。酒精滥用是胰腺炎的一个主要病因；然而，酒精导致这种疾病的机制仍然不清楚。在此，我们提出了酒精性胰腺炎发病机制的新假说，认为两个事件的组合对胰腺炎至关重要：1)诱导自噬；2)溶酶体功能受损，使自噬功能受损。自噬(又名巨型自噬)是主要的细胞降解、溶酶体驱动的过程。我们最近的研究表明，在非酒精性急性胰腺炎的实验模型中，自噬功能存在严重的损害。我们发现自噬被激活了，但它的进程/分辨率受到了损害。自噬功能障碍是由溶酶体功能障碍引起的，其突出表现是主要溶酶体水解酶组织蛋白的加工/成熟缺陷。此外，我们的发现表明，自噬受损介导了胰腺炎的两个关键病理反应：腺泡细胞空泡化和腺泡内胰蛋白酶原激活。我们的结果表明，单纯酒精喂养会导致胰腺溶酶体功能障碍，与我们在非酒精性胰腺炎中发现的类似。然而，乙醇本身并不会导致胰腺炎，因为它不会激活自噬。因此，在基础非刺激自噬的条件下，乙醇诱导的溶酶体功能障碍的后果是有限的。然而，酒精喂养会导致溶酶体功能障碍，而应激导致自噬会导致自噬缺陷，从而导致胰腺炎。我们的结果表明，这就是酒精喂养使大鼠或小鼠对低剂量蓝蛋白(CR；CCK-8类似物)诱发的胰腺炎“敏感”的机制，而低剂量蓝蛋白本身并不会引发胰腺炎。我们认为，酒精喂养和内毒素血症(即内毒素血症)相结合诱导的胰腺炎也有类似的机制，另一种现有的酒精性胰腺炎的体内敏化模型。我们的结果表明，乙醇引起内溶酶体转运和高尔基体的失调，与组织蛋白的加工和活性缺陷以及主要溶酶体膜蛋白LAMP-2的水平降低有关。我们进一步提出，控制自噬的水平(分别通过ATG5基因敲除抑制自噬或通过过度表达ATG8/LC3来刺激自噬)可以改善或加重酒精性胰腺炎。本项目的具体目标是：1.研究单纯酒精喂养和实验性酒精性胰腺炎(即酒精喂养联合小剂量CR或LPS)对胰腺溶酶体功能障碍的影响，以及LAMP-2在这些作用中的作用。2.测定单纯酒精喂养和实验性酒精性胰腺炎对溶酶体转运和高尔基体的影响。3.检测单纯酒精喂养和实验性酒精性胰腺炎对自噬的诱导和进展的影响，以及LAMP-2在这些作用中的作用。4.确定基因抑制或刺激自噬对酒精性胰腺炎的影响。拟议的研究阐明了乙醇对溶酶体、胰腺高尔基体和自噬的影响；提出了酒精性胰腺炎的新模型；并为治疗或减轻这种疾病的治疗方法指明了新的靶点。此外，与乙醇引起的溶酶体功能障碍有关的类似机制可能会介导酒精对其他器官的毒性。