Free fatty acids promote hepatic lipotoxicity by stimulating TNF-α expression via a lysosomal pathway

作者：Ariel E. Feldstein, Nathan W. Werneburg, Ali Canbay, Maria Eugenia Guicciardi, Steven F. Bronk, Robert M. Rydzewski, Laurence J. Burgart, Gregory J. Gores · 发表于：Hepatology · 年份：2004 · DOI：10.1002/hep.20283 · 被引用次数：842 · 研究领域：Liver Disease Diagnosis and Treatment、Sphingolipid Metabolism and Signaling、Endoplasmic Reticulum Stress and Disease

Nonalcoholic fatty liver disease (NAFLD) is a serious health problem. Although NAFLD represents a form of lipotoxicity, its pathogenesis remains poorly understood. The aim of this study was to examine the cellular mechanisms involved in free fatty acid (FFA)-mediated hepatic lipotoxicity. FFA treatment of liver cells resulted in Bax translocation to lysosomes and lysosomal destabilization with release of cathepsin B (ctsb), a lysosomal cysteine protease, into the cytosol. This process was also partially dependent on ctsb. Lysosomal destabilization resulted in nuclear factor kappa B-dependent tumor necrosis factor alpha expression. Release of ctsb into the cytoplasm was also observed in humans with NAFLD and correlated with disease severity. In a dietary murine model of NAFLD, either genetic or pharmacological inactivation of ctsb protected against development of hepatic steatosis, liver injury, and insulin resistance with its associated "dysmetabolic syndrome." In conclusion, these data support a lipotoxic model of FFA-mediated lysosomal destabilization.