Background:
Cannabis use is prevalent among people living with HIV (PLHIV). Cannabis is mostly smoked leading to inhalation of the psychoactive tetrahydrocannabinol as well as reactive particles, toxins, and oxidants that may induce epigenetic changes and affect immune responses. We therefore analyzed the effect of cannabis on DNA methylation and immune function in PLHIV.
Methods:
Participants were recruited from the 2000HIV study (NTC03994835), a Dutch multi-center study amongst virally suppressed PLHIV, separated into a discovery cohort (n=1512, 280 cannabis users) and a validation cohort (n=317, 47 cannabis users). Cannabis use and tobacco smoking were recorded through a self-reported questionnaire. Genome-wide DNA methylation data was obtained using the Illumina Infinium MethylationEPIC array. Plasma proteins were assessed by targeted proteomics (Olink Explore). PBMC ex vivo cytokine production capacity was measured upon bacterial, fungal, and viral stimulation. The differential DNA Methylation Sites (DMSs) were identified by an epigenome-wide association study, followed by integration with the proteomics, and cytokine secretion data from the same individuals.
Results:
In the discovery cohort, 3741 cannabis-associated DMSs were identified, with 293 DMSs being replicated in the validation cohort. The most significant DMS is cg01940273 (p=1.3e-50) also strongly associated with tobacco smoking in 2000HIV and other studies. After accounting for tobacco smoking effects, 98% DMSs showed reduced significance but the methylation trend remained consistent and 81% DMSs were demethylated. Validated DMSs associated genes were enriched in nervous system development and leukocyte differentiation. The DMS-associated plasma proteins suggested that DMSs are associated with leukocyte differentiation and cytokine expression, such as IL6 upregulation and CXCL10 downregulation (Figure1). The causal inference test suggested that cannabis-induced DMSs may modulate immune response in PLHIV, such as increased IL22 and decreased INF-y production after PBMC stimulation.
Conclusions:
Cannabis inhalation induces significant DNA methylation changes in PLHIV. Such modifications may lead to systematic changes in plasma (inflammatory) protein levels, and cytokine secretion of circulating immune cells. Downregulation of INF-y and INF-y induced protein CXCL10 may influence host response to HIV and co-pathogens. Our data indicate that cannabis use needs to be recorded and corrected for reporting inflammation in PLHIV.
