(OR15-03-25) Astaxanthin Modulates Mitochondrial Unfolded Protein Response to Protect Hepatocytes From Alcohol-Induced Damage

Objectives: Chronic alcohol consumption induces oxidative stress, inflammation, and mitochondrial dysfunction in hepatocytes, driving alcohol-related liver disease. The mitochondrial unfolded protein response (UPR^mt) usually aids proteostasis under stress by upregulating chaperones and proteases, but its excessive activation can worsen inflammation and tissue damage. Here, we investigated the role of UPR^mt in the antioxidant and anti-inflammatory effects of the xanthophyll carotenoid astaxanthin (ASTX) in ethanol-exposed hepatocytes.

Methods: VL-17A cells are derived from HepG2 cells, a human hepatoma cell line, expressing alcohol dehydrogenase and cytochrome P450 2E1. The cells were pre-treated with 25 μM of ASTX for 6 h, and then incubated with 80 mM of ethanol for 72 h to determine gene and protein expression, reactive oxygen species (ROS) levels, ATF5 nuclear localization, and mitochondrial quantity and function.

Results: Ethanol significantly increased total cellular ROS and mitochondrial superoxide accumulation while decreasing antioxidant gene expression. Also, pro-inflammatory gene expression was significantly increased by ethanol. ASTX abolished ethanol-induced oxidative stress and inflammation. Concurrently, induction of UPR^mt-related mitochondrial chaperones and proteases by ethanol, indicative of heightened mitochondrial stress, was attenuated by ASTX. ASTX also completely abolished the reduction of mitochondrial DNA copy number by ethanol. To further corroborate the effect of ethanol and ASTX on the regulation of the UPR^mt pathway, we determined the cellular localization of ATF5, whose nuclear presence can induce UPR^mt genes. Both Western blot and immunofluorescence analyses indicated that ethanol increased the nuclear translocation of ATF5 while diminishing its mitochondrial contents, which ASTX mitigated.

Conclusions: ASTX suppressed ethanol-induced oxidative stress and inflammation by preserving mitochondrial biogenesis and integrity. By curbing ethanol’s mitochondrial damage, ASTX prevented excessive UPR^mt activation, safeguarding mitochondrial function. This study highlights the therapeutic potential of ASTX in alcohol-induced liver injury.

Funding Sources: USDA Multi-State Hatch & Research Excellence Program at the University of Connecticut