Chronic alcohol feeding increases mitochondrial respiration in frg mice with humanized liver

Abstract

Trabajo presentado en el Annual Meeting of the American-Association-for-the-Study-of-Liver-Diseases (AASLD) / Liver Meeting, celebrado en San Francisco del 9 al 13 de noviembre de 2018[Background] Alcoholic liver disease (ALD) is a spectrum of disorders that begin with hepatic steatosis, which can progress to alcoholic steatohepatitis (ASH) and cirrhosis. The incomplete understanding of mechanisms contributing to ALD progression has limited the availability of effective therapy. Mitochondrial dysfunction is a hallmark of ALD. Altered mitochondrial morphology in human ALD and indirect metabolic determinations suggested impaired mitochondrial function in ALD patients. In experimental models, impaired mitochondrial respiration seems to be species-dependent (rats vs. mice), with evidence in mice showing a correlation between increased mitochondrial respiration and ALD severity. Therefore, we examined the mitochondrial function from alcohol-fed FRG mice xenotransplanted with human adult hepatocytes (HH).[Methods] FRG mice were injected with HH through the spleen followed by controlled cycles of NTBC withdrawal. Humanized FRG mice were fed an alcohol (5%, ethanol; 36% calories) or control liquid diets for 10 days after 5 days of acclimation. HH were isolated and oxygen consumption rates (OCR) determined by a flux analyzer to examine respiratory parameters. In parallel, hepatocyte mitochondrial respiration was determined in wild type mice fed alcohol diet for comparison. In some cases, perivenous (PV) and periportal (PP) hepatocytes were isolated from wild type mice fed alcohol.[Results] FRG mice were repopulated with HH by 80-85%, as estimated by the determination of serum human albumin levels and expression of fumaroylacetoacetate by immunohistochemistry. OCR significantly increased in HH from FRG mice fed alcohol compared to FRG mice fed control diet. This outcome translated in a significant increase (2-fold) in basal OCR, ATP production and maximal respiration, without changes in proton leak, coupling efficiency or mitochondrial mass (cytochrome c immunostaining). Interestingly, these findings in OCR and respiratory parameters were similar to those found in mitochondrial respiration from wild type mice fed alcohol for the same period of time. Moreover, the mitochondrial respiratory alterations reflected predominant changes in PV rather than PP hepatocytes from wild type mice fed alcohol. Conclusion: Using this subrogate model of humanized ALD, our findings show that alcohol feeding increases mitochondrial respiration in human hepatocytes metabolizing alcohol, suggesting that increased mitochondrial respiration may contribute to human ALD.Peer reviewe