Chronic alcohol misuse induces alveolar macrophage oxidative stress and mitochondrial dysfunction via upregulation of microRNA‐130a

Abstract

ObjectiveCompared to non‐alcoholics, individuals who misuse alcohol are 2–4 times as likely to develop respiratory infections and acute respiratory distress syndrome. Alcohol misuse enhances alveolar macrophage (AM) oxidative stress and causes phagocytic dysfunction via upregulation of microRNA (miR)‐130a. Although studies indicate that alcohol‐induced mitochondrial (MT) redox imbalance in AM may contribute to AM phagocytic dysfunction, the mechanisms by which this occurs is unknown. We hypothesized that alcohol upregulates miR‐130a to destabilize its target peroxisome proliferator‐activated receptor (PPAR)γ, which dysregulates AM MT function and depletes ATP levels necessary for phagocytosis.MethodsAMs were obtained from the bronchoalveolar lavage fluid of C57BL/6J mice fed ± ethanol (20% w/v) in the drinking water for 12 wks. In parallel, MH‐S cells, a mouse AM cell line, were transfected ± 50 nM miR‐130a inhibitor and treated ± 0.08% ethanol for 3 d. Levels of PPARγ‐related miR‐130a, which binds to the PPARγ 3′untranslated region to decrease PPARγ, and PPARγ mRNA were assessed by qRT‐PCR. PPARγ protein expression was assessed by confocal cytoimmunostaining. MT‐derived oxidative stress was measured using MitoSOX and MitoTracker CMXRos fluorescent molecular probes. MT bioenergetics profile was measured with MT stress testing using a Agilent Seahorse XF96 Extracellular Flux Analyzer. AM function was evaluated by phagocytosis assay (S. aureus internalization).ResultsIn vivo and in vitro studies demonstrated that ethanol: 1) increased miR‐130a levels and decreased PPARγ expression; 2) increased MT‐derived oxidative stress; 3) decreased MT oxygen consumption rate, bioenergetics, and ATP; and 4) impaired phagocytic capacity. miR‐130a inhibitor reversed these ethanol‐induced AM derangements.ConclusionsChronic alcohol misuse enhances AM oxidative stress and MT dysfunction by upregulating PPARγ‐related miR‐130a. Our studies suggest that therapeutically targeting MT as an intervention will ameliorate alcohol‐induced AM phagocytic dysfunction and may decrease susceptibility of lung infections in patients with a history of alcohol misuse.Support or Funding InformationResearch Funding Source: R00AA021803 (SMY).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.