Dichapetalin-type triterpenoids inhibits macrophage interferon expression by regulating the cGas-STING pathway, suggesting potential application in immunosuppression

Dichapetalin-type triterpenoids (DTs) derived from Dichapetalum longipetalum (Turcz.) Engl. have attracted extensive attention due to their novel structure, as well as potent anti-tumor and anti-inflammatary activities. In this study, the immunosuppressive effect of Dichapetalin-type triterpenoids on mouse peritoneal macrophages (MPMs) was studied. MPMs were stimulated with HSV-1 or LPS for the inflammation model. The cytokines and inflammatory mediators were detected by RT-PCR. Western blotting was carried out to determine the phosphorylation of TBK1 and IRF3. Our results showed that DTs inhibited the expression of IFN-β in MPMs infected with HSV-1, and also inhibited the expression of Il-1β and Il-6 in LPS-stimulated MPMs. In addition, compound 1 (dichapetalin A) down regulated the phosphorylation of Tbk1 and Irf3 in HSV-1-infected MPMs. Taken together, this study suggests that DTs isolated from the Dichapetalum longipetalum (Turcz.) Engl. inhibits macrophage activation through the cGas-STING pathway in MPMs, which would be potential for the treatment of autoimmune diseases.