Celastrol ameliorates experimental autoimmune uveitis through STAT3 targeting and gut microenvironment reprofiling

Background: Extensive research has revealed the favorable effects of celastrol (CEL) against various diseases, but the role of CEL in autoimmune uveitis remains unexplored. Methods: We first assessed the prophylactical and therapeutical effects of CEL on autoimmune uveitis via rat experimental autoimmune uveitis model. After network pharmacology, functional enrichment and molecular docking analyses, we predicted the potential target of CEL and validated its effect on EAU by clinical and histopathological scores, Evans blue staining, immunofluorescence assay and western blotting. Then we evaluated the role of CEL in the gut environment by 16S rRNA sequencing and untargeted metabolomic analysis. Results: We confirmed that CEL treatment suppressed the pathological TH17 response, inhibited the migration of inflammatory cells, and preserved the integrity of BRB via targeting STAT3-IL17 pathway. Furthermore, CEL was found to reduce the relative abundance of opportunistic pathogenic bacteria including Clostridium_sensu_stricto_1, Parasutterella and GCA-900066575, and enrich the relative abundance of beneficial Oscillospirales and Ruminococcus_torques_group in EAU rats by fecal 16S rRNA sequencing. Meanwhile, CEL treatment reshaped the gut metabolites in the EAU rats by increasing the relative concentrations of cholic acid, progesterone and guggulsterone, and decreasing the relative levels of isoproterenol, creatinine and phenylacetylglutamine. Conclusions: CEL exerts its ameliorative effects on the experimental autoimmune uveitis through the dual mechanisms of targeting STAT3 and reprofiling the gut microenvironment.