Abstract
Background/Objectives: Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disease that primarily affects the joints. Current treatments aim to relieve pain and limit joint damage; however, many are associated with significant side effects or high costs. Neutrophils play a critical role in RA development and progression by driving synovial inflammation and tissue damage, yet no approved therapies directly target neutrophil-mediated pathogenic mechanisms. Cannabinoids have demonstrated anti-inflammatory potential. Although cannabinoids have been studied in RA, the direct modulation of neutrophil-driven mechanisms by purified CBG has not been systematically addressed. To harness the cannabinoid potential, we investigated the effects of the purified cannabinoid Cannabigerol (CBG) on neutrophil-mediated immune responses in RA. Methods: We assessed the effects of CBG on human blood isolated neutrophil cytokine secretion, signal transduction and migration as ex vivo models. In addition, collagen antibody-induced arthritis (CAIA) was applied in C57BL/6 wt mice, and immune-cell recruitment and cytokine secretion were examined after CBG treatment. Results: Ex vivo experiments demonstrated that CBG hampered the secretion of pro-inflammatory cytokines from human neutrophils in a dose-dependent manner (TNF-α and IL-6 by 68% and 72%, respectively). Furthermore, CBG downregulated inflammatory signal transduction, such as P38-MAPK, ERK1/2 and Akt phosphorylationpost neutrophil activation by 41%, 54% and 78%, respectively. Importantly, 60% of the CBG downregulation of IL-6 was consistent with the CB2 receptor axis in a selective way. In addition, CBG attenuated neutrophil migration toward IL-8 by 67%. To further evaluate CBG therapeutic capacity, we used CAIA as an in vivo model. CBG treatment resulted in improving mice arthritis clinical scores and body weight in comparison to RA-diseased mice. Moreover, CBG reduced leukocyte recruitment to the inflamed joints by 48%, primarily through the inhibition of neutrophil and monocyte cells to 27% and 49%, respectively. Additionally, CBG showed its anti-inflammatory effect by decreasing inflammatory cytokines like IL-6 and IL-1β by 98% and 60% in the blood. Also, CBG reduced MCP-1 and IL-1β cytokines in the joints by 22% and 38%, respectively. Conclusions: These results show that CBG has anti-inflammatory capacity and therapeutic potential in regulating neutrophil-mediated immunity in RA. These findings are preclinical and require further validation before therapeutic positioning.