THC Exposure Shifts Immune Response to Helminth Infection Toward Anti-Inflammatory State in Mice
A new mouse study found that sustained THC exposure altered immune responses to helminth (parasitic worm) infection, pushing eosinophils and macrophages toward anti-inflammatory transcriptional programs. Mice were treated with 5 mg/kg/day of THC for 14 days before infection with Nippostrongylus brasiliensis, a lung-and-gut-infecting helminth. The findings raise questions about whether cannabis use could dampen protective immune responses to parasitic infections in humans.
Researchers using C57BL/6J mice investigated how 14 days of THC exposure (5 mg/kg/day) affected immune responses to the helminth Nippostrongylus brasiliensis, which infects both the lungs and small intestine. While THC did not significantly change infection-associated weight loss or overall parasite burden, it selectively reduced circulating eosinophils and monocytes while increasing regulatory T cells. Splenocytes from THC-treated infected mice also showed reduced secretion of the pro-inflammatory cytokines TNF and IFN-γ. Bulk RNA sequencing revealed that THC shifted lung eosinophils and macrophage-enriched cells away from inflammatory, fibrotic, and costimulatory gene programs toward stress-response and metabolic-adaptive pathways. Within macrophages, THC reduced CD80 expression — a key costimulatory molecule — while upregulating MHC class II and antigen-presentation genes, suggesting a nuanced shift in how macrophages activate T cells. Immunofluorescent staining further showed that THC mitigated infection-associated loss of lung collagen, consistent with altered tissue remodeling. The study, posted as a preprint on bioRxiv, adds to growing evidence that endocannabinoid signaling meaningfully shapes type 2 immune responses, though its translational relevance to human cannabis users remains to be established.
What's missing
As a preprint, this study has not yet undergone peer review. Key limitations include the use of a single inbred mouse strain (C57BL/6J) and a single THC dose, which may not reflect the diversity of human cannabis use patterns, routes of administration, or genetic backgrounds. The study does not address whether the observed immune shifts would impair long-term parasite clearance or increase susceptibility to reinfection. The study does not examine effects of other cannabinoids present in cannabis, such as CBD, which could modulate outcomes.
What different sources said
- bioRxivCenter
{triangleup}9-Tetrahydrocannabinol exposure shifts eosinophil and macrophage transcriptional programs towards an anti-inflammatory phenotype in helminth infection
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