Immune mechanism of Daphnes Cortex and its processed products on CIA rats based on B7/CD28/CTLA-4 pathway

Abstract

This study investigates the effects of Daphnes Cortex and its processed products on the differentiation of Th17/Treg cells in SD rats with type Ⅱ collagen-induced arthritis(CIA).Sixty-four SD rats were randomly divided into the normal group(normal),model group(model),fried Daphne giraldii Nitsche low-dose and high-dose groups(FDGN-L group, FDGN-H group),raw D. giraldii Nitsche low-dose and high-dose groups(RDGN-L group, RDGN-H group),daphnetin group(DAPH group),and tripterygium glycosides group(GTW group).Except for the normal group, the CIA model was immunized on the seventh day after the first immunization, and was gavaged for 28 days after the second immunization.After sampling, the inflammation of articular synovial membrane in CIA rats was observed by hematoxylin-eosin(HE)staining; the levels of transforming growth factor-β(TGF-β),interferon-γ(IFN-γ),interleukin(IL)-2,IL-4,and IL-10 in serum were detected by enzyme-linked immunosorbent assay(ELISA); real-time reverse transcription-PCR(qRT-PCR)and Western blot were used to detect the mRNA and protein expressions of cluster of differentiation(CD) 80(B7-1),CD 86(B7-2),CD28,and cytotoxic T lymphocyte-associated antigen 4(CTLA-4)in the synovial membrane of rats; flow cytometry was used to detect the proportion of Th17 and Treg cells in the synovial membrane of rats.The results showed that compared with the normal group, the joint synovial inflammation of rats in the model group was significantly aggravated, the arthritis index was significantly increased, and the immune organ index was increased(P<0.01).Compared with the model group, each drug administration group could improve the joint inflammation of rats to varying degrees, reduce the arthritis index, inhibit synovial hyperplasia, and reduce the immune organ index; compared with the model group, the serum levels of IL-2 and IFN-γ in each drug administration group were significantly decreased(P<0.01),TGF-β,IL-4,and IL-10 were significantly increased(P<0.01),the mRNA and protein expressions of B7-1 and CTLA-4 in the synovial membrane were significantly increased(P<0.01),and the proportion of Th17 cells and Treg cells in the joint tissue was significantly decreased(P<0.01).In conclusion, Daphnes Cortex inhibits the expression of Th17 cells in CIA rats and promotes the expression of Treg cells by regulating the B7/CD28/CTLA-4 pathway and the balance of Th17/Treg, thereby treating rheumatoid arthritis.