Moxibustion alleviates inflammation via SIRT5 post-translational modification and macrophage polarization

Abstract

Abstract Background Macrophage polarization plays an essential role in the anti-inflammation process. Moxibustion, a traditional Chinese medicine therapy, has been reported to have an anti-inflammatory effect via enhancing α-ketoglutarate (α-KG) and succinate levels. Succinate/α-KG ratio is a hallmark of M1 and M2 macrophage shift. Glutamate dehydrogenase 1 (GLUD1) is a vital enzyme for α-KG production and can be deacetylated by Sirtuin5 (SIRT5). Currently, the role of moxibustion in SIRT5-GLUD1-α-KG-related macrophage alteration in inflammatory diseases has not been discussed yet. Methods In this study, complete Freund's adjuvant (CFA)-induced adjuvant arthritis models were established. On day 4 post-CFA, moxibustion and acupoint MC3482 injection were administered. Foot volume was measured before and after the model was established, and after the moxibustion and acupoint injection interventions. ELISA assays were then performed to quantify inflammatory factors, including IL-1β, TNF-α, IL-4, TGF-β, succinate, and α-ketoglutarate (α-KG). Flow cytometry (FCM) and immunofluorescence were used to test M1- and M2-like macrophage expressions in the right arthrodial cartilages of mice. Furthermore, western blotting and immunoprecipitation (IP) were used to detect SIRT5, GLUD1, and GLUD1 succinylation expressions. Results Moxibustion and SIRT5 desuccinylation inhibitor MC3482 decreased inflammation by increasing M2 macrophage and reducing M1 macrophage levels in CFA model. The potential mechanism may relate to the effects of moxibustion and SIRT5 inhibition, which could invert succinate and α-KG levels in the CFA group, which displayed low succinate, high α-KG and increased GLUD1 succinylation modification after treatment. Conclusion This study supports that moxibustion's anti-inflammation effects are related to the consequences of macrophage conversion after SIRT5 post-translational modification.