Nox4‐related miR‐92a Mimic Improves Alcohol‐Induced Derangements in Alveolar Macrophage Immunometabolism

Abstract

ObjectiveIndividuals with a history of alcohol use disorders (AUD) are at increased risk of developing respiratory infections due in part to alveolar macrophage (AM) phagocytic dysfunction. Cellular metabolism and bioenergetics are known to play key roles in immune cell functions. Chronic alcohol exposure increases NADPH oxidase (Nox)4, which increases AM oxidative stress, and may contribute to derangements in AM immunometabolism. Nox4 expression may be post‐transcriptionally regulated by microRNA (miR)‐92a, leading to Nox4 downregulation. Therefore, we hypothesized that chronic alcohol exposure decreases mir‐92a to upregulate Nox4, which increases mitochondrial oxidative stress and dysfunction in immunometabolism, resulting in increased susceptibility to respiratory infections.MethodsMH‐S, a mouse alveolar macrophage cell line, were treated ± 0.08% ethanol (EtOH) for 3 d ± miR‐92a mimic (50 μM, last 1 d). Expression of miR‐92a and Nox4 were measured by qRT‐PCR. Cellular reactive oxygen species (ROS) generation and H2O2 were measured using 2′,7′‐dichlorofluorescein‐diacetate fluorescence and Amplex Red assay, respectively. Co‐localization of Nox4 and mitochondria were assessed by confocal microscopy. Mitochondrial respiration and bioenergetics were measured using an extracellular flux bioanalyzer. In vitro phagocytic capacity was measured using pHrodo Staphylococcus aureus BioParticles conjugate.ResultsIn vitro EtOH: 1) decreased miR‐92a and increased Nox4 expression, 2) increased ROS and H2O2, 3) increased Nox4 co‐localization with mitochondria, 4) decreased mitochondrial respiration and bioenergetics, and 5) decreased AM phagocytic ability. Treatment with miR‐92a mimic reversed these EtOH‐induced impairments.ConclusionsChronic alcohol consumption increases alveolar macrophage oxidative stress, while reducing mitochondrial respiration and phagocytic capacity. Treatment with miR‐92a mimic reduced EtOH‐induced oxidative stress and improved AM immunometabolism and phagocytic function. Our studies reveal that miR‐92a may be a novel therapeutic target in the treatment of pulmonary infections in individuals with a history of AUD.Support or Funding InformationThis work was supported by the National Institute of Alcohol Abuse and Alcoholism R01‐AA026086 (SMY) and by the Emory Acute Lung Injury Training Program T32‐HL116271‐05 (David M. Guidot).