Chronic Alcohol Ingestion Impairs Rat Alveolar Macrophage Phagocytosis via Disruption of RAGE Signaling

• Type of Material: Article
• Authors: Bashar S. Staitieh, Emory University; Eduardo E. Egea, Emory University; Adaugo Amah, Morehouse School of Medicine; Xian Fan, Emory University; David M Guidot, Emory University
• Language: English
• Date: 2018-05-01
• Publisher: Lippincott, Williams & Wilkins
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2017 Southern Society for Clinical Investigation
• Final Published Version (URL): http://dx.doi.org/10.1016/j.amjms.2017.12.013
• Title of Journal or Parent Work: American Journal of the Medical Sciences
• ISSN: 0002-9629
• Volume: 355
• Issue: 5
• Start Page: 497
• End Page: 505
• Grant/Funding Information: Dr. Staitieh was supported by K08 AA 024512; Dr. Egea and Ms. Amah were supported by T32 HL116271; and Dr. Guidot was supported by R01 AA 017627.
• Keywords: OXIDATIVE STRESS; Life Sciences & Biomedicine; Antioxidant; Medicine, General & Internal; CELL; RAGE; CHRONIC ETHANOL INGESTION; General & Internal Medicine; Science & Technology; Innate immunity; DYSFUNCTION; RECEPTOR; Alveolar macrophage; ABUSE; LUNG; Alcohol; GLUTATHIONE
• Research Categories: Health Sciences, Medicine and Surgery

Abstract

Background: Alcohol significantly impairs antioxidant defenses and innate immune function in the lung and increases matrix metalloproteinase 9 (MMP-9) activity. The receptor for advanced glycation end products (RAGE) is a well-characterized marker of lung injury that is cleaved by MMP-9 into soluble RAGE and has not yet been examined in the alcoholic lung. We hypothesized that chronic alcohol ingestion would impair RAGE signaling via MMP-9 in the alveolar macrophage and thereby impair innate immune function. Materials and Methods: Primary alveolar macrophages were isolated from control-fed or alcohol-fed rats. Real-time polymerase chain reaction (qRT-PCR), Western blotting, and enzyme-linked immunosorbent assays were performed to evaluate RAGE expression. Silencing of MMP-9 ribonucleic acid (RNA) in a rat alveolar macrophage cell line was confirmed by qRT-PCR, and immunofluorescence (IF) was used to assess the association between alcohol, MMP-9, and RAGE. Phagocytosis was assessed using flow cytometry. Sulforaphane and glutathione were used to assess the relationship between oxidative stress and RAGE. Results: RAGE messenger RNA expression was significantly increased in the alveolar macrophages of alcohol-fed rats, but IF showed that membrane-bound RAGE protein expression was decreased. Lavage fluid demonstrated increased levels of soluble RAGE (sRAGE). Decreasing MMP-9 expression using si-MMP-9 abrogated the effects of alcohol on RAGE protein. Phagocytic function was suppressed by direct RAGE inhibition, and the impairment was reversed by antioxidant treatment. Conclusions: Chronic alcohol ingestion reduces RAGE protein expression and increases the amount of sRAGE in alveolar lavage fluid, likely via cleavage by MMP-9. In addition, it impairs phagocytic function. Antioxidants restore membrane-bound RAGE and phagocytic function.