Cannabinoids shift the basal ganglia microRNA m6A methylation profile towards an anti-inflammatory phenotype in SIV-infected rhesus macaques

Epitranscriptomic modifications [N6-methyladenosine (m⁶A)] regulate various diseases, including cancer and inflammation. Despite their functional relevance in neural development and differentiation, the role of m⁶A modifications in HIV neuropathogenesis is unknown. Using anti-N6-methyladenosine (m⁶A) antibody-immunoprecipitation and microarray profiling, we identified m⁶A modifications in miRNAs in basal ganglia (BG) of uninfected (VEH) and SIV-infected Rhesus macaques (RMs) on combination anti-retroviral therapy (ART) and either VEH-treated (VEH/SIV/ART) or THC:CBD-treated (THC:CBD/SIV/ART). HIV/SIV infection promoted an overall hypomethylated miRNA m⁶A profile. While THC:CBD did not significantly impact the overall hypomethylated m⁶A profile, specific miRNAs predicted to target proinflammatory genes showed marked m⁶A hypomethylation compared to VEH-treated RMs. Additionally, specific BG m⁶A-modified miRNAs were detected in BG-derived extracellular vesicles. Mechanistically, the DRACH motif in the miR-194-5p seed region was significantly m⁶A hypomethylated in THC:CBD/SIV/ART RMs. Unlike wild-type, in-vitro transfected m⁶A-modified miR-194-5p mimics failed to downregulate STAT1 protein expression. Further, compared to VEH/SIV/ART RMs, THC:CBD significantly reduced m⁶A methylation of 44 miRNAs directly involved in regulating CNS network genes. Our findings indicate that m⁶A epi-transcriptomic marks in the seed nucleotides can impair miRNA function and that cannabinoids may preserve it by reducing m⁶A methylation levels, thus providing a mechanistic explanation underlying their anti-neuroinflammatory effects in HIV/SIV infection.