Targeting CB1 and TRPM8 receptors to counteract CD8+ T cell exhaustion.

The prolonged interaction between the immune system and tumor antigens can result in T cell exhaustion. Extensive research has been conducted on strategies to reactivate exhausted T cells within the tumor microenvironment. However the exact contribution of the endocannabinoid system (ECS) and nociceptors in regulating CD8+ T cells within the framework of cancer-related inflammation has not been thoroughly studied. This study investigated the use of a TRPM8 antagonist (RQ-00203078), a selective cannabinoid receptor 1 (CB1) antagonist (AM251), and alpelisib (BYL-719) to control CD8+ T cell exhaustion. Our findings showed that administration of the CB1 antagonist AM251, either alone or in combination with alpelisib, significantly reduced the expression of PD-1 and Lag-3 on CD8+ T cells. Interestingly, treatment with the TRPM8 antagonist led to a notable increase in PD-1 expression on CD8+ T cells. These findings suggest that the decreased expression of inhibitory receptors on CD8+ T cells after treatment with the CB1 antagonist whether alone or with alpelisib and TRPM8 highlights the potential of ECS as a promising therapeutic target in cancer treatment.