Alcohol activates cannabinoid receptor 1 and 2 in a model of pathogen induced pulmonary inflammation

Abstract

Alcohol use disorder (AUD) is defined as patterns of alcohol misuse and affects over 30 million people in the US. AUD is a systemic disease with the epidemiology of acute lung injury and excessive alcohol use established in the literature. However, the distinct mechanisms by which alcohol induces the risk of pulmonary inflammation are less clear. A compelling body of evidence shows that cannabinoid receptors (CB1R and CB2R) play a relevant role in AUD. For this study, we investigated the role of CBR signaling in pulmonary immune activation. Using a human macrophage cell line, we evaluated the expression of CBR1 and CBR2 after cells were exposed to EtOH, +/- cannabinoid agonists and antagonists by flow cytometry. We also evaluated the expression of cannabinoid receptors from the lungs of adolescent mice exposed to acute binge EtOH +/- cannabinoid agonists and antagonists at both resting state and after microbial challenge via western blot, rt-PCR, cytokine analysis, and histology. Our results suggest that EtOH exposure modulates the expression of CBR1 and CBR2. Second, EtOH may contribute to the release of DAMPs and other proinflammatory cytokines, Finally, microbial challenge induces pulmonary inflammation in acute binge EtOH-exposed mice, and this observed immune activation may be CBR-dependent. We have shown that adolescent binge drinking primes the lung to subsequent microbial infection in adulthood and this response can be mitigated with cannabinoid antagonists. These novel findings may provide a framework for developing potential novel therapeutics in AUD research.