Role Of Self-immunotolerance Disorder On Pathogenesis Of Systemic Erythematosus Lupus

Autoimmune disease (AD) is a kind of disease caused by harmful immune responses between auto antigens and potentially pathogenic auto reactive antigens, which result in tissues and/or organs destruction and loss of physical functions. Self-tolerance is controlled by central and peripheral mechanisms. To investigate the disorder of central and peripheral tolerance in Systemic lupus erythematosus (SLE) and effect of glucocorticoid therapy on immunotolerance, three experiments were designed and completed to clarify the issue.Part 1 Change of CD4~+CD25~+T cell in SLE patientsIn order to investigate the effect of CD4~+CD25~+Treg cell and its functional gene (Foxp3) on SLE, CD4~+CD25~+Treg cell and Foxp3 were detected in peripheral blood mononuclear cells (PBMC) of SLE patients after treatment by glucocorticoid. The results showed that the number of CD4~+CD25~+Treg was significantly enhanced in PBMC from SLE patients. The expressions of Foxp3 mRNA were not significantly changed. It means that CD4~+CD25~+Treg may be responsible for pathogenesis of SLE and glucocorticoid may increment CD4~+CD25~+Treg frequency to treat SLE patients.Part 2 The abnormities of central and peripheral tolerance in SLE modelIn order to clarify the pathogenesis of SLE, cGVHD induced SLE murine model was made and role of promiscuous gene expression in thymus and CD4~+CD25~+ regulatory T cell were investigated on this model. 1. The establishment of SLE model(Balb/c×C57BL/6) F1 mice were made by 6-8 weeks-old Balb/c and C57BL/6 mice. With the injection of lymphocyte separated from spleens, thymus and lymph nodes of Balb/c mice to F1 mice, the SLE models were established successfully by the method of chronic graft versus host disease (cGVHD). 4 week after the last injection, the model group got the phenomena of loosing hairs, particularly in snouts, and activity reduced. Urine protein in the model group was positive (~+~+~~+~+~+), but in the control group were negative. Anti-nuclear antibody (ANA) in serum was positive for all the model mouses. There were no positive results in the control and the negative control group. All kidney slices of the model group showed various degrees of green fluorescence. This result demonstrated that the immunocomplex deposited in glomcrulus and most were IgG..Glomerulus's hyperplasia, thickening basement and lots of inflammatory cells infiltration were found in the kidney slice of the model group mice. And in the mean time, inflammatory cells were infiltrated in salivary glands.2. Role of promiscuous gene expression in thymus and CD4~+CD25~+ regulatory T cell on immunotolerance of SLE modelThe thymic promiscuous gene expression of CTSL and SP2 declined in the model group. Obvious sialadenitis and general symptoms in SLE model mice may be relevant with this phenomenon. The quantities of CD4~+CD25~+Treg and the ratio of Treg/CD4~+T were not significantly changed both in thymus and spleen. Foxp3 declined, but CTLA-4 and GITR increased in model group. The results indicated that both Treg function decreased and T cell activated contributed to the pathogenesis of SLE model.3. Effects of glucocorticoid therapy on the central and peripheral tolerance for SLE modelIn order to clarify the role of the glucocorticoid therapy on central and peripheral immunotolerance, model mice were divided into control and therapy group randomly. The therapy group was injected with glucocorticoid. The model group was injected with normal saline (NS). Less trichomadesis phenomenon was found in therapy group. New hairs were found in trichomadesis mice of the therapy group. However, the model group mice did not improve. Urine protein of the model group were ~+~+~~+~+~+, and the counterpart of the therapy group mice were ~+~~+~+. The fluorescence intensity in the therapy group mice was less obviously than that in the model group. The symptoms in therapy group were improved greatly by glucocorticoid. The promiscuous gene expression of CTSL and SP2 in the therapy group was higher than that in the model group. The thymic promiscuous gene expression has recovered by the therapy of glucocorticoid. Quantities of CD4~+CD25~+Treg were not changed after the therapy, but the expression of Foxp3 recovered and CTLA-4 and GITR decreased in the therapy group. The results showed that the function of Treg reinforced obviously and T cell activation was depressed by glucocorticoid.Part 3 The abnormities of central and peripheral tolerance in MRL/lpr miceMRL/lpr mice showed that Anti-nuclear antibody was positive in model group but negative in control group. The thymic promiscuous gene expression of CTSL, CRP, TG and SP2 declined in MRL/lpr mice. There were no significant differences of quantities of CD4~+CD25~+Treg in thymus for model and control group.Foxp3 levels of model group were no significant difference in thymus but lower in spleen compared with that of control group. CTLA-4 levels of model group were higher than control group both in thymus and in spleen. These result suggest that MRL/lpr mice does not occur as a result of reduced level of CD4~+CD25~+Treg, but function defect of CD4~+CD25~+Treg may be responsible for its occurrence.