Transcriptional, epigenetic, and functional reprogramming of blood monocytes in non-human primates following chronic alcohol drinking

Chronic heavy drinking (CHD) of alcohol is a known risk factor for increased susceptibility to bacterial and viral infection as well as impaired wound healing. Evidence suggests that these defects are mediated by a dysregulated inflammatory response originating from myeloid cells, notably monocytes and macrophages, but the mechanisms remain poorly understood. Our ability to study CHD is impacted by the complexities of human drinking patterns and behavior as well as comorbidities and confounding risk factors for patients with alcohol use disorders. To overcome these challenges, we utilize a translational rhesus macaque model of voluntary ethanol self-administration in order to recapitulate human drinking patterns and chronicity. In this study, we examined the effects of CHD on blood monocytes and alveolar macrophages in control and CHD female macaques after 12 months of daily ethanol consumption. We first showed that monocytes from CHD female macaques generate a hyper-inflammatory response to ex vivo LPS stimulation. In depth scRNA-Seq analysis of purified monocytes revealed significant shifts in classical monocyte subsets with accumulation of cells expressing markers of hypoxia (HIF1A) and cytokine production (NFkB signaling pathway) in CHD macaques. The increased presence of monocyte subsets poised to generate a hyperinflammatory response was confirmed by the epigenetic analysis which revealed higher accessibility of promoter regions that regulate genes involved in cytokine signaling pathways. To assess functional responses to a gram-negative bacteria, monocytes were stimulated with E.coli and discovered to have a reduced ability to respond. Finally, examination of alveolar macrophages (AM) from the same animals indicated that the hyper-inflammatory phenotype extends to tissue-resident macrophages, which produced higher levels of inflammatory mediators in response to LPS stimulation. Additionally, the AM had a reduced ability to phagocytose bacteria, indicating functionally consequences of CHD in the tissue. Collectively, data presented in this manuscript demonstrate that CHD primes monocytes and tissue-resident macrophages towards a more hyper-inflammatory immune response, which could be used in diagnostic purposes or preventative measures for patients with alcohol use disorders.