Approximately ~7% of alcohol-consuming individuals engage in chronic heavy drinking (CHD), which is associated with increased susceptibility to infections as well as impaired wound healing and tissue repair resulting in poor post-operative outcomes. Evidence suggests that many of these defects are mediated by excessive inflammatory responses originating from myeloid cells, notably circulating monocytes and tissue- resident macrophages. These data were primarily generated from in vitro studies where monocytes from healthy donors or cell lines are treated high doses of ethanol. However, the mechanisms underlying the effects of CHD cannot be fully understood by in vitro studies because immune cells carry out their functions in a multicellular environment in which alcohol has widespread effects. Due to a lack of studies utilizing reliable in vivo models, our understanding of the mechanisms underlying aberrant inflammatory responses in the context of CHD remains incomplete. To address these knowledge gaps, we propose to leverage a rhesus macaque model of voluntary ethanol self-administration that accurately mirrors human physiology and recapitulates complex human drinking behavior. Using this model, our lab has recently demonstrated that CHD results in transcriptional and epigenetic rewiring of circulating monocytes and splenic macrophages, resulting in aberrant responses to LPS stimulation. However, the functional implications of this reprogramming and the epigenetic mechanisms controlling it remain unknown. Importantly, because monocytes are short-lived circulating cells under constant repopulation from the bone marrow, these observations suggest perturbations of the hematopoietic niche. Preliminary single-cell analyses of hematopoietic progenitors point to a shift in differentiation potential towards more mature myeloid progenitors with alcohol. However, a link between this observation in progenitor cells and their differentiated states in blood and tissue remains unclear. In this application, we propose to test the hypothesis that chronic alcohol consumption reprograms the epigenetic landscape of monocyte progenitors in the bone marrow giving rise to circulating monocytes poised towards a hyper- inflammatory response. We will first examine the impact of CHD on functional reprogramming of circulating monocytes, implementing assays to test their ability to migrate, phagocytose, and generate proper metabolic responses. We will next examine the effect of stimulation on the monocyte epigenetic landscape through assessment of chromatin accessibility and abundance of specific histone modifications. Finally, we will determine the effect of CHD on the differentiation potential, transcriptome activation, and epigenetic rewiring of bone marrow myeloid progenitors and integrate these data with those obtained from peripheral blood monocytes. Completion of this proposal will provide novel insight into the impact of CHD on myelopoiesis and mechanisms by which it compromised immunity and host defense as well as design interventions to mitigate these adverse events and improve immunological outcomes.
/RELEVANCE Approximately 7% of alcohol users engage in chronic heavy drinking (CHD), which is associated with increased risk of bacterial and viral infections as well as decreased tissue repair ability. These observations suggest a failure of innate immune cells to perform their functions. The proposed research aims to identify CHD-mediated functional, transcriptomic, and epigenetic alterations in monocytes and their progenitors in the bone marrow, with the goal of better understanding the etiology of reduced immune fitness.
