Sulforaphane Pre-Treatment Improves Alveolar Macrophage Killing After Alcohol-Induced Phagocytic Dysfunction In Vitro<em> </em>and<em> </em>in <em>Galleria mellonella </em>Larvae

Background: Alcohol is associated with increased mortality and morbidity globally. Pulmonary infections with opportunistic pathogens can occur in healthy humans; however, binge alcohol intoxication (≥ 0.08% BAC) is a major risk factor. We have previously shown that a single dose of alcohol comparable to binge alcohol intoxication increases infection by reducing alveolar macrophage function in vivo. The aim of this study was to test the therapeutic potential of the phytonutrient sulforaphane (SFN) given as a pretreatment to prevent alcohol-induced phagocytic dysfunction. Methods: Intracellular phagocytic killing was measured via colony forming units (CFU) and cytokine expression via ELISA. G. mellonella survival was used to determine the therapeutic potential of SFN in vivo. Results: Dose response curves indicated that SFN concentrations less than 20 µM were not cytotoxic in both MH-S (murine) and THP-1 (human) cells. Live infection assay results showed MH-S and THP-1 cells pretreated with SFN (5 µM) and challenged with 0.2% (v/v) alcohol for 3 or 8 hours prior to live B. thailandensis or S. epidermidis infection improved intracellular pathogen killing between 12- and 20-fold—compared to macrophages treated with alcohol alone. ELISA analysis indicated that SFN significantly reduced levels of Tumor necrosis factor-alpha (TNF-α) expression at 3 and 8 hours compared to controls. Additionally, a Galleria mellonella larvae model demonstrated greater survivability in the prophylaxis group compared to larvae exposed to either Gram-positive or Gram-negative pathogens, as well as in groups that received alcohol prior to pathogen inoculation. Conclusions: Taken together, SFN-induced cytoprotection was extended beyond in vitro cell culture to include an in vivo G. mellonella model demonstrating protection against Gram-positive and negative opportunistic pathogens. These data demonstrate that SFN may be an effective pretreatment option to prevent alcohol-mediated innate immune dysfunction and restore macrophage phagocytic killing.