Schistosoma Japonicum Cystatin Attenuatesmurine Collagen-induced Arthritisby Prophylactic Intervention

BackgroundRheumatoid arthritis (RA) is a chronic inflammatory and systemic destructive autoimmune disorder with high incidence, and with no cure available. Development of CIA is related to helper T cells and regulatory T cells. RA is generally considered to be mediated by the Thl response, which aggravates joint inflammation by the way of Thl cells release of IFN-y, TNF-a and lymphotoxin β in synovial tissue. IL-17-producer CD4+T cell subpopulation, termed Th17 cells, represents a different pro-inflammatory Th-cell lineage that has been confirmed to play a critical role in the generation of several types of autoimmune arthritis such as CIA. Schistosoma japonicum infection has been proved to be protective in murine model of collagen-induced arthritis (CIA). Nevertheless, intensity and chronicity of infection are important factors that are associated with the amelioration of allergic inflammation, whereas acute infections may procure aggravation of allergic responses.S. japonicum cystatin is a member of stefin family and the recombinant Sjcystatin (rSjcystatin) possesses enzymatic activity and negatively immune regulatory property, for it could inhibit the proteolytic activity of papain and antigen presentation process in vitro experiment. rSjcystatin reduce the monocytes activation, enhance IL-10 generation and decrease pro-inflammatory factors production involving TNF-a and IL-6. It has been reported that cystatins of filaria, a tissue-dwelling nematode, inhibits class Ⅱ MHC-restricted antigen processing, induces the polarization of immunosuppressive cells, and restrains immune cell activation and migration, and is responsible for degrading of the immune components of the host.ObjectiveThe precise mechanism of the potential immunomodulatory or therapeutical effects mediated by rSjcystatin in rheumatoid inflammation remains to be determined. We investigated the potential effects of rSjcystatin on CIA mice.Methods We aimed to study the putative immune regulation of rSjcystatin and its prophylactic/ therapeutic effects on murine collagen-induced arthritis (CIA). CIA was induced in DBA/1 mice by inoculation with bovine collagen II (CII). rSjcystatin was administered prior or post development of CIA. The CII-specific antibodies in sera and cytokines in splenocytes culture supernatants were measured by ELISA. Th1/Th2/Th17 cells and Tregs development in splenocytes were monitored by flow cytometry. The inflammatory mediators in the diseased joint were semi-quantitated by qPCR. Prophylactic injection of rSjcystatin attenuated paws clinical scores, incidence, and histopathology scores of joints in CIA mice.ResultsrSjcystatin, a recombinant protein of Schistosoma japonicum cysteine protease inhibitor, has been reported to have an effect on immunoregulation mediated by IL-10 induction. Rheumatoid arthritis (RA) is a common autoimmune inflammatory arthropathy, and recombinant immune-modulating drugs for RA treatment are under development. The arthritis-alleviative effects were closely associated with the augmentation of IL-4, IL-10, collagen-specific IgG1, and with the distinct reduction of IFN-y, collagen-specific IgG2a, and the marked decrease of pro-inflammatory cytokines IL-6, IL-17, and TNF-a and RANKL. The data indicated that rSjcystatin may prevent cartilage destruction and inflammation of joints in CIA mice. The effects are related to the inhibitory modulation of Th1 and Th17, and upregulation of Tregs and Th2 via a shift of cytokines profiling from Th1 to Th2 response.ConclusionsWe have demonstrated for the first time that rSjcystatin, a recombinant S. japonicum cysteine protease inhibitor, can effectively alleviate the pathology of murine adjuvant arthritis by prophylactic intervention. The amelioration of clinical parameters, decline of histopathological scores and improvement of the detection indexes appear to be attributed to the down-regulated role of rSjcystatin in pathogenesis of arthritis in mice. rSjcystatin might be promising for further study on prophylactic and complementary use in the therapeutic strategy of rheumatoid arthritis.