Dose-dependent effects of chronic alcohol drinking on peripheral immune responses

It is well established that chronic heavy alcohol drinking (CHD) results in significant organ damage, increased susceptibility to infections, and poor outcomes following injury. In contrast, chronic moderate drinking (CMD) has been associated with improved cardiovascular health and immunity. These differential outcomes have been linked to alterations in both innate and adaptive branches of the immune system; however, the mechanisms remain poorly understood. To address this question, we determined the impact of chronic drinking on the transcriptional and functional responses of peripheral blood mononuclear cells (PBMC) collected from male rhesus macaques classified as CMD or CHD after 12 months of voluntary ethanol self-administration. Our analysis suggests that chronic alcohol drinking alters resting transcriptomes of PBMC in a dose-dependent manner, with the largest impact seen in innate immune cells. Additionally, chronic alcohol drinking is associated with a dose-dependent increase in the cytokine response to LPS stimulation. Moreover, we observed a dose-dependent shift in the kinetics of transcriptional responses to LPS, partially explained by alterations in microRNA profiles. These findings explain the dichotomy in clinical and immunological outcomes observed with moderate versus heavy alcohol drinking.