GPR55 antagonist CID16020046 suppresses DNCB-induced atopic dermatitis-like symptoms by suppressing Th1/Th2/Th17 populations in mice

G protein-coupled receptor 55 (GPR55) is a lipid-sensing receptor that plays a role as an immune mediator and is primarily upregulated during immune cell activation. There is a lack of knowledge about the role of GPR55 in allergic inflammatory diseases such as atopic dermatitis. The purpose of this study was to investigate the role of GPR55 through the use of its antagonist, CID16020046, in an atopic dermatitis mouse model. It was found that BALB/c mice develop lesions similar to those associated with atopic dermatitis following sensitization and repeated exposure to 1-chloro-2,4-dinitrobenzene (DNCB). It was found that CID16020046 (1 mg/kg, i. p.) alleviated the atopic dermatitis-like symptoms as well as immune dysregulation caused by DNCB. Based on histopathological analysis, CID16020046 reduced ear thickening and mast cell counts in the dermis. CID16020046 decreased DNCB-induced increases in serum IgE levels, as measured using enzyme-linked immunosorbent assays. A significant reduction in lymph node hypertrophy was also observed with CID16020046 as well as significant reductions in CD4⁺ T helper 1 (Th1), Th2, and Th17 cells in the lymph nodes. As a result of the administration of CID16020046, cytokines of Th1 (IFN-γ), Th2 (IL-4 and IL-13), and Th17 (IL-17 A) types were also reduced in the skin and lymph nodes. In conclusion, blocking GPR55 alleviates DNCB-induced atopic dermatitis-like symptoms, suggesting that GPR55 is a potential therapeutic target for allergic inflammatory diseases via immunoregulation.