Rationale Consumption of alcohol begins during late adolescence in a majority of humans, and the greatest drinking occurs at 18–25 years then decreases with age. Objectives The present study measured differences in ethanol intake in relation to age at the onset of ethanol access among non-human primates to control for self-selection in humans and isolate age effects on heavy drinking. Methods Male rhesus macaques were assigned first access to ethanol during late adolescence (n = 8), young adulthood (n = 8) or early middle age (n = 11). The monkeys were induced to drink ethanol (4% w/v in water) in increasing doses (water, 0.5 g/kg, 1.0 g/kg, 1.5 g/kg) using a fixed-time (FT) 300-s schedule of food delivery, followed by 22 hours/day concurrent access to ethanol and water for 12 months. Age-matched controls consumed isocaloric maltose-dextrin solution yoked to the late adolescents, expected to be rapidly maturing (n = 4). Results Young adult monkeys had the greatest daily ethanol intake and blood-ethanol concentration (BEC). Only late adolescents escalated their intake (ethanol, not water) during the second compared to the first 6 months of access. On average, testosterone was consistent with age differences in maturation, and tended to increase throughout the experiment more for control than ethanol-drinking adolescent monkeys. Conclusions Young adulthood in non-human primates strongly disposes toward heavy drinking independently of sociocultural factors present in humans. Drinking ethanol to intoxication during the critical period of late adolescence is associated with escalation to heavy drinking.

It is well established that heavy ethanol consumption interferes with the immune system and inflammatory processes, resulting in increased risk for infectious and chronic diseases. However, these processes have yet to be systematically studied in a dose and sex-dependent manner. In this study, we investigated the impact of chronic heavy ethanol consumption on gene expression using RNA-seq in peripheral blood mononuclear cells isolated from female rhesus macaques with daily consumption of 4% ethanol available 22hr/day for 12 months resulting in average ethanol consumption of 4.3 g/kg/day (considered heavy drinking). Differential gene expression analysis was performed using edgeR and gene enrichment analysis using MetaCore™. We identified 1106 differentially expressed genes, meeting the criterion of ≥ two-fold change and p-value ≤ 0.05 in expression (445 up- and 661 down-regulated). Pathway analysis of the 879 genes with characterized identifiers showed that the most enriched gene ontology processes were “response to wounding”, “blood coagulation”, “immune system process”, and “regulation of signaling”. Changes in gene expression were seen despite the lack of differences in the frequency of any major immune cell subtype between ethanol and controls, suggesting that heavy ethanol consumption modulates gene expression at the cellular level rather than altering the distribution of peripheral blood mononuclear cells. Collectively, these observations provide mechanisms to explain the higher incidence of infection, delay in wound healing, and increase in cardiovascular disease seen in subjects with Alcohol use disorder.

Background Chronic heavy alcohol drinking (CHD) leads to significant organ damage, increased susceptibility to infections, and delayed wound healing. These adverse outcomes are believed to be mediated by alterations in the function of myeloid cells; however, the mechanisms underlying these changes are poorly understood. Methods We determined the impact of CHD on the phenotype of splenic macrophages using flow cytometry. Changes in functional responses to LPS were measured using luminex and RNA-Seq. Finally, alterations in chromatin accessibility were uncovered using ATAC-Seq. Findings A history of CHD led to increased frequency of splenic macrophages that exhibited a heightened activation state at resting. Additionally, splenic macrophages from CHD animals generated a larger inflammatory response to LPS, both at protein and gene expression levels. Finally, CHD resulted in increased levels of H3K4me3, a histone mark of active promoters, as well as chromatin accessibility at promoters and intergenic regions that regulate inflammatory responses. Interpretation These findings suggest that a history of CHD alters the immune fitness of tissue-resident macrophages via epigenetic mechanisms. Fund National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH) - R24AA019431, U01 AA13641, U01 AA13510, R21AA021947, and R21AA025839.