Chronic alcohol consumption induces phenotypic and functional alterations consistent with a hyper-inflammatory state in peripheral blood mononuclear cell-derived microglia in a rhesus macaque model.

Alcohol-induced dysregulation of microglial activity is associated with neuroinflammation, cognitive decline, heightened risk for neurodegenerative diseases, alcohol dependence, and escalation of alcohol drinking. Given the challenge of longitudinally sampling primary microglia, we optimized an in vitro method to differentiate peripheral blood mononuclear cells (PBMC) from rhesus macaque (RM) into induced microglia-like cells (RM-iMGLs). The RM-iMGLs displayed transcriptional profiles distinct from monocyte progenitors and closely resembling primary microglia. Notably, morphological features showed that differentiated RM-iMGLs derived from subjects with chronic alcohol consumption (CAC), while bigger, exhibited a bipolar-like morphology. Additionally, dysregulation in key inflammatory and regulatory markers, along with increased baseline phagocytic activity, was observed in CAC-derived RM-iMGLs. Phenotypic and functional assessments following LPS stimulation indicated the enrichment of a CD86+ hyper-inflammatory subpopulation in RM-iMGLs derived from ethanol-consuming animals, accompanied by an overall increase in immune reactivity, indicative of a heightened inflammatory state. Collectively, these findings demonstrate that in vitro differentiation of PBMCs offers a minimally invasive yet highly translational approach to studying the impact of CAC on microglial function and that CAC reshapes both functional and transcriptional profiles of RM-iMGLs, which require further investigation at the single-cell level.