The Effect Of IL-1 On Differentiation And Development Of Treg Cells

Recently, many researches have indicated that Treg cells play an important role in maintaining immune tolerance mainly by secreting immunological suppressive cytokines and expressing other inhibitory co-stimulatory molecules in order to suppress the response of self-reactive T cells. Furthermore, their absence or functional deficiency may lead to various autoimmune diseases.Rheumatoid arthritis (RA) is a chronic clinical multiple autoimmune diseases, characterized by multiply joints, symmetrical inflammation and progressive cartilage and bone destruction, and mainly involves the joints, particularly the small joints of hands and feet. The disease can invade the adjacent synovial, cartilage and bone. Without timely diagnosis and treatment, it can develop irreversible joint deformities, and eventually lead to disability.Interleukin 1, which is an important proiflammatory cytokine, is known to be involved in the onset of rheumatoid arthritis. During the course of RAS IL-1βderived from a variety of cells can stimulate activation of T and B lymphocytes, monocytes and macrophages, promote fibroblast proliferation and induce osteoclasts.activation.IL-1 receptor antagonist can competitively bind IL-1RI without participating in signal transduction, and thereby block the biological effects of IL-1a and IL-1β. Recently IL-1 receptor antagonist (IL-1ra) had been applied to the clinical therapy for rheumatoid patients, which can reduce the symptoms and signs of RA patient.. However, a number of clinical data showed that IL-1ra treatment may cause some adverse effects, such as serious injection site reactions and the relapse of symptom after long term usage.In the present study, we have established the collage-induced arthritis mice model and observed the therapeutic effects of recombinant IL-1ra in CIA mice.In the study in vitro, we investigated the effect of IL-1βand IL-1ra on CD4+CD25+ T cell proliferation induced by DC,and also studied the effect of IL-1 on the differentiation and development of CD4+CD25+Foxp3+regulatory T cell induced by TGF-β.PartⅠ. The therapeutic effect of IL-1ra on CIA mice in vivoCIA was elicited in mice as previously described. Briefly, on day 0, we used chicken collagenⅡas antigen, and immunized DBA/lmice by subcutaneous injection of 100μl 4mg/ml acidified chicken collagen II emulsified in CFA.with 1:1 ratio at the end of the roots. Mice were boosted with CCII (200μg in IFA) on day 21, we used chicken collagen II as antigen, and immunized DBA/lmice by subcutaneous injection of 100μul 4mg/ml acidified chicken collagen II emulsified in IFA with 1:1 ratio at the end of the roots. According to CIA standards of clinical index:a scale of 0:normal joints; a scale of 1:joint a slight swelling; a scale of 2:joint swelling and serious, involving the entire joint; a scale of 3:paw or joint dysfunction, joint stiffness. The sum score includes each mouse limbs, giving a maximum score of 12 per mouse. We considered the mouse whose joint total score greater than 1 as a model successfully building.According to the experimental purpose, mice were randomly divided into 3 groups, IL-1ra treatment group, PBS treatment control group and the BSA protein treatment control group. From day 33 after the first immunization for 20 days, the CIA mice of IL-1ra treatment group were given s.c 100ug IL-1ra for each mice, the control group were given with equivalent PBS or BSA protein.The established CIA mice developed on day 27 after the first immunization, and reached the peak on day 33. The disease incidence of the CIA mice established successfully by bovine collagen type II reached 80%, and the average clinical scores reached 6 points. Articular manifestations were chronic progressive polyarthritis, firstly including a slight redness of the skin of toes in acute phase, and then involving the paws and ankles, severe swelling of the skin, lately leading to joint deformity or limited motion, histopathologies with H&E showed that synovitis proliferation, pannus formation, cellular fibrosis, articular cartilage and bone destruction.Clinical joint score and pathological results suggested IL-1ra treatment reduced the early CIA joint swelling, inflammatory cell infiltration, pannus formation, e the articular cartilage and bone destruction. But in the late stage, swelling joint intensified, resulting in the destruction of articular cartilage and bone. In addition, in the acute phase of CIA mice, the proportion of CD4+CD25+regulatory T cells in CD4+T cells after treatment by IL-lra did not increase in IL-Ira-treated group. These results suggested the relapse of symptom in the late stage of treatment may be related to the impairment of the differentiation and development of Treg cells in vivo.PartⅡ. The effect of IL-1 on the proliferation of CD4+CD25+ Foxp3+Treg cells in vitroThe differentiation and growth impairment and dysfunction of Treg cells is the main immunological mechanisms leading to autoimmune disease. Based on the source of its development, regulatory T cells include the natural regulatory T cells from the thymus and induced regulatory T cells induced under the conditions of continuous antigen and IL-10, TGF-P and other cytokines outside the thymus. DCs, as a professional antigen presenting cells, were not only involved in the activation of naive T cell, but also controlled the differentiation of initial T cell into different cell subsets. Recent research results show that DCs participate in the self-stability proliferation of natural Treg cells.In this study, we found that both mature and immature DCs and DCs could stimulate the proliferation of CD4+CD25+Treg cells in vitro. Furthermore, the ability of mature DCs to stimulate Treg proliferation was stronger compared with immature DCs. The effect of stimulating the proliferation of Treg by mature DCs could be partially inhibited by irradiation. The results showed that the proliferation of Treg cells stimulated by DC in not only depend on the cell-cell direct contact, but also related closely the secretion of cytokines. Mature DC can secrete high levels of proinflammatory cytokines such as IL-1β, IL-6, IL-2 and TGF-β. In vitro, we found that immature DCs enhanced the proliferation of CD4+CD25+ T cell in the presence of low concentration of IL-1β; IL-1ra inhibited the proliferation of CD4+CD25+ T cells promoted by mature DCs in the presence of lOug/ml IL-lra. These results suggest that low concentrations of IL-1 may serve as a Treg-promoting growth factor, which was involved in the process of the proliferation of Treg induced by DC.In addition, we also established a system in which TGF-βinduced CD4+CD25-cells into CD4+CD25+Foxp3+ regulatory T cell in vitro. These regulatory T cells induced by TGF-b had high expression of FoxP3 and could significantly inhibit the response of responsive CD4+ T cells proliferate. When exogenous IL-1βwas added to the system, the frequency of CD4+CD25+ Foxp3+regulatory T cell induced was increased significantly. These results suggested that IL-1βcould promote differentiation and development of induced regulatory T cell synergistic with TGF-β.In conclusion, our present study found that in CIA acute stage, the proportion of CD4+CD25+Foxp3+ regulatory T cells decreased after IL-1ra treatment which might to related to relapse of symptom in the late stage. IL-1 might be an important growth factor participating in the differentiation and development of Treg cells.