Myoblast Mitochondrial Adaptation to Chronic Alcohol Administration

Abstract

Skeletal muscle adaptation to chronic alcohol consumption involves disruption of anabolic, catabolic, and oxidative metabolism pathways and is associated with decreased muscle mass and impaired metabolic function. These maladaptive responses may contribute to increased risk of metabolic disorders, particularly in people living with human immunodeficiency virus (PLWH) on combination antiretroviral therapy (ART). Aging, increased survival of PLWH on ART, and lifestyle choices including unhealthy alcohol use are complicated by metabolic comorbidities. We tested the hypothesis that mitochondrial homeostasis is critically impacted by chronic binge alcohol (CBA) administration. Specifically, we hypothesized that CBA impairs skeletal muscle expression of genes underlying mitochondrial metabolic function and alters myoblast function in SIV‐infected, ART‐treated rhesus macaques. Female rhesus macaques (n=10) were assigned to receive either CBA (50–60 mM peak blood alcohol/day, 5 days/week) or isovolumetric water (VEH) for 3 months before SIVmac251 infection. After 2.5 months, ART was initiated, and skeletal muscle samples were collected from all animals at study endpoint (~12 months post‐SIV infection). mRNA was extracted and analyzed for genes related to mitochondrial biogenesis and metabolic function [peroxisome proliferator‐activated receptor‐gamma coactivator (PGC)‐1α, PGC‐1β, mitochondrial transcription factor A (TFAM), estrogen related receptor (ERR)α, nuclear respiratory factor (NRF)1 and 2]. Naïve (no alcohol or SIV) primary myoblasts were isolated from skeletal muscle and incubated with alcohol (50 mM) or control (media only) for three days. To assess mitochondrial metabolic function, oxygen consumption rate was determined at baseline in alcohol‐treated and control myoblasts after the addition of oligomycin, carbonyl cyanide‐4 (trifluoromethoxy) phenylhydrazone (FCCP), and rotenone and antimycin A using Agilent Seahorse technology. CBA reduced expression of PGC‐1β, TFAM, ERRα, NRF1, and NRF2, but not PGC‐1α mRNA in skeletal muscle from SIV‐infected, ART‐treated female rhesus macaques. In vitro, alcohol treatment reduced basal and maximal oxygen consumption rate of naïve myoblasts. Together, our findings demonstrate maladaptive changes in myoblast mitochondrial gene expression and function. These results identified potential therapeutic targets to improve skeletal muscle metabolic health in PLWH. Specifically, the role of PGC‐1β as a potential mechanism by which alcohol impairs skeletal muscle mitochondrial function warrants further investigation on its responsiveness to pharmacotherapeutic intervention to restore its levels and improve mitochondrial metabolic health in PLWH with unhealthy alcohol use.Support or Funding InformationThis research was supported by grants from the National Institute on Alcohol Abuse and Alcoholism, 1F32AA027982‐01A1, 5P60AA009803‐25, K01AA024494‐03, and 5T32AA007577‐20.