Role of Alcohol Metabolism in Alcoholic Chronic Pancreatitis

点击翻译按钮获取中文摘要

Abstract Chronic alcohol abuse is a single most major etiology of chronic pancreatitis, a serious inflammatory disorder of exocrine pancreas leading to loss of pancreatic functions and multiple co-morbidities including diabetes and pancreatic cancer. Therefore, a better understanding of mechanism and metabolic basis of alcoholic chronic pancreatitis (ACP) is of great clinical significance for identifying its therapeutic targets for early detection/prevention of the disease. Majority (~90%) of ingested alcohol (ethanol) is metabolized in the liver via alcohol dehydrogenase (ADH). However, the inhibition of hepatic ADH during chronic alcohol abuse facilitates formation of fatty acid ethyl esters (FAEEs, nonoxidative metabolites of ethanol) by several folds in the pancreas frequently damaged during chronic alcohol abuse. These esters are known to cause injury to pancreatic acinar cells in vitro as well as in vivo. Using hepatic ADH-deficient (ADH-) deer mice fed 3.5% ethanol via Lieber-DeCarli liquid diet, we found formation of fatty pancreas and several fold increases for pancreatic FAEEs, and endoplasmic reticulum (ER) stress and injury. Additionally, we also found inactivation of AMP-activated protein kinase (AMPK)α, which regulates lipid homeostasis via controlling lipid synthesis and β-oxidation of fatty acids, in freshly isolated human pancreatic acinar cells exposed to ethanol in vitro, and in the pancreas of ADH- vs. hepatic normal ADH (ADH+) deer mice after chronic ethanol feeding. Together, these preliminary findings led our central hypothesis that chronic ingestion of ethanol and its nonoxidative metabolism under hepatic ADH inhibition deactivates pancreatic AMPKα resulting into formation of a large quantities of FAEEs in the pancreas, contributing to pathogenesis of ACP. This hypothesis will be tested by establishing progressive pancreatic injury in ADH- deer mice fed ethanol for 1 and 3 months (aim 1), and that chronic ethanol feeding inactivates AMPKα, promotes increased formation of FAEEs resulting into progressive pancreatic injury in ADH- deer mice (aim 2). The in vivo findings will be validated in primary human pancreatic acinar cells. Finally, role of FAEEs in ethanol-induced pancreatic acinar cell injury will be established by using ADH- deer mice and primary human pancreatic acinar cells (aim 3). We expect a progressive ethanol-induced pancreatic injury in our deer mouse model, and to identify the role of endogenous FAEEs in ethanol-induced pancreatic acinar cell injury. Our project is innovative because we are using a hepatic ADH- deer mouse model (a natural variant of hepatic ADH deficiency) and freshly isolated human pancreatic acinar cells to establish the metabolic basis and mechanism of ACP. This project will be benefited by a strong interdisciplinary team of investigators and their research experience with deer mouse and human pancreatic acinar cell culture models. Overall, our project should establish metabolic basis of ACP and identify molecular targets for an early detection/therapeutic intervention of ACP.