Ethyl Acetate Extract fromCelastrus aculeatusMerr. Suppresses Synovial Inflammation in Adjuvant Arthritis Rats through Apoptosis Induction of CD4+CD25+FOXP3+T Cells

Abstract

Celastrus aculeatusMerr. has been widely used in traditional Chinese medicine to treat rheumatoid arthritis (RA) in clinic. However, the main active fraction of this plant is still unclear. In this study, we attempted to evaluate the suppressive effect of ethyl acetate extract (EAE) fromCelastrus aculeatusMerr. on synovial inflammation in adjuvant arthritis (AA) rats induced byMycobacterium tuberculosisH37Ra (Mtb) and to explore the underlying mechanisms. SD rats immunized with heat-killed Mtb were fed with EAE and observed for erythema, swelling, and induration of each paw. The pathologic changes in joint synovium were tested by hematoxylin-eosin staining. Apoptosis induction of synoviocytes was tested immunohistochemically. Apoptosis of peripheral lymphocytes and the level of regulatory T cells were analyzed by flow cytometry. After treatment with EAE, the joint inflammation in rats with AA was alleviated. Both apoptotic ratios of synoviocytes and peripheral lymphocytes and the ratio of CD4+CD25+FOXP3+to CD4 regulatory T cells were significantly increased. In summary, we first demonstrated that EAE ofCelastrus aculeatusMerr. can inhibit synovial inflammation in AA rats through apoptosis induction of CD4+CD25+FOXP3+T cells. Our study provides a rationale for the application ofCelastrus aculeatusMerr. to treat RA.