Alcohol induces mitochondrial derangements in alveolar macrophages by upregulating NADPH oxidase 4

• Published in: Alcohol (Fayetteville, N.Y.) N.Y.), 2021-02, Vol.90, p.27-38
• Main Authors: Morris, Niya L., Harris, Frank L., Brown, Lou Ann S., Yeligar, Samantha M.
• Format: Article
• Language: English
• Subjects: Alcohol use; alveolar macrophage; Alveoli; Animals; Bioenergetics; Cell Line; Confocal microscopy; Drug abuse; Electron microscopy; Ethanol; Ethanol - toxicity; Gene expression; Immunofluorescence; Infections; Laboratory animals; Ligands; Macrophages; Macrophages, Alveolar - metabolism; Macrophages, Alveolar - pathology; Mice; MicroRNAs; miR-92a; miRNA; Mitochondria; mRNA; NAD(P)H oxidase; NADPH Oxidase 4 - genetics; NADPH Oxidase 4 - metabolism; Nox4; NOX4 protein; Oxidative Stress; Penicillin; Phagocytes; Phosphorylation; Pioglitazone; Proteins; Reactive oxygen species; Reactive Oxygen Species - metabolism; Rosiglitazone; Transfection; Transmission electron microscopy
• ISSN: 0741-8329; 1873-6823
• DOI: 10.1016/j.alcohol.2020.11.004

Excessive alcohol users have increased risk of developing respiratory infections in part due to oxidative stress-induced alveolar macrophage (AM) phagocytic dysfunction. Chronic ethanol exposure increases cellular oxidative stress in AMs via upregulation of NADPH oxidase (Nox) 4, and treatment with the peroxisome proliferator-activated receptor gamma (PPARγ) ligand, rosiglitazone, decreases ethanol-induced Nox4. However, the mechanism by which ethanol induces Nox4 expression and the PPARγ ligand reverses this defect has not been elucidated. Since microRNA (miR)-92a has been predicted to target Nox4 for destabilization, we hypothesized that ethanol exposure decreases miR-92a expression and leads to Nox4 upregulation. Previous studies have implicated mitochondrial-derived oxidative stress in AM dysfunction. We further hypothesized that ethanol increases mitochondrial-derived AM oxidative stress and dysfunction via miR-92a, and that treatment with the PPARγ ligand, pioglitazone, could reverse these derangements. To test these hypotheses, a mouse AM cell line, MH-S cells, was exposed to ethanol in vitro, and primary AMs were isolated from a mouse model of chronic ethanol consumption to measure Nox4, mitochondrial target mRNA (qRT-PCR) and protein levels (confocal microscopy), mitochondria-derived reactive oxygen species (confocal immunofluorescence), mitochondrial fission (electron microscopy), and mitochondrial bioenergetics (extracellular flux analyzer). Ethanol exposure increased Nox4, enhanced mitochondria-derived oxidative stress, augmented mitochondrial fission, and impaired mitochondrial bioenergetics. Transfection with a miR-92a mimic in vitro or pioglitazone treatment in vivo diminished Nox4 levels, resulting in improvements in these ethanol-mediated derangements. These findings demonstrate that pioglitazone may provide a novel therapeutic approach to mitigate ethanol-induced AM mitochondrial derangements. •Ethanol increases mitochondrial Nox4 via decreases in miR-92a.•Ethanol impairs mitochondrial bioenergetics in alveolar macrophages.•Pioglitazone reverses ethanol-induced mitochondrial dysfunction.