Alcohol and Monocyte Signaling

ABSTRACT Alcohol use is associated with both pro-inflammatory and immunosuppressive effects; however, cellular and molecular mechanisms or therapeutic interventions to normalize immune disturbances caused by alcohol are yet to be explored. Increased pro-inflammatory responses in the monocyte/macrophage and neutrophil populations are complicated by immune exhaustion leading to poor clinical outcomes in alcohol-associated hepatitis (AH). Recent studies described “trained immunity” that is characterized by long-term epigenetic reprogramming of innate immune cells by an infection or host factors such as, potentially, alcohol use. Our preliminary data suggest that alcohol induces features of “trained immunity” that is characterized by enhanced pro-inflammatory responses to subsequent insults. Thus, we hypothesize that chronic and/or binge alcohol use result in trained immunity in monocytes/macrophages and neutrophils and this contributes to exacerbated inflammatory responses in AH. Emerging evidence suggests that trained immunity is a result of immunometabolic and epigenetic programming of innate immune cells including bone marrow precursors. Consistent with this, we found increased utilization of glycolysis as opposed to OXPHOX in PBMCs of patients with AH. Thus, we hypothesize that alcohol-induced trained immunity is mediated by immunometabolic reprogramming. Our preliminary results also show altered metabolic profile in mice, specifically when challenged with LPS. We postulate that by identifying key alcohol-induced immunometabolic and epigenetic events, we can design targets for reversal of dysregulated innate immunity in AH. Our Aims are #1: To investigate the effects of alcohol use on features of trained immunity in mouse models and in human alcohol-associated hepatitis (AH) by a) Evaluating “trained immunity” in bone marrow granulocyte-monocyte progenitors (BM-GMP) and in liver neutrophils and monocyte/macrophages (Mo/Mφ) in alcohol “trained mice” after an LPS challenge; b) Identifying epigenetic features of trained immunity in liver neutrophil and Mo/Mφ populations and BM-GMP by snRNA+scATAC seq, and determine specific gene activation/repression marks by ChIP-qPCR; c) Characterizing the phenotypic and epigenetic signature of “trained immunity” in circulating neutrophil and Mo/Mφ populations in AH patients. #2: To identify the immunometabolic signature in “alcohol trained” mice after an LPS challenge and in humans with AH; and #3: To evaluate underlying mechanisms by which alcohol induces metabolic reprogramming and trained immunity by a) Assessing the role of the cellular energy sensor “PAS Kinase” in in vivo models of alcohol-induced trained immunity in mice; b) Restoring immune cell functionality by modulating specific immunometabolic receptors (SUCNR1, OXGR1), and immune checkpoint receptors (PD-1); c) Targeting key epigenetic regulators (HDAC9) in restoration of alcohol-induced trained immunity. Results from this proposal will provide novel insights into alcohol-induced immunometabolic and epigenetic alterations that can lead to “trained immunity” and thereby derail immune responses even after stopping alcohol use.