Effects Of BLyS On The Activity Of Peripheral B Lymphocytes Mediated By BLyS Receptors In Patients With SLE And The Influence Of TACI-Ig

Systemic lupus erythematosus (SLE) is an autoimmune disease of high degree of heterogeneity and of unknown etiology and shows a diversity and complexity of clinical manifestations. There is still no radical cure for SLE. How to prevent or delay of the organization for the pathological damage to essential organs is most important. Numerous factors were involved in the pathogenesis of SLE. The current notion is attributed to genetic and environmental factors causing the disorders of the immune system and the immunologic tolerance broken which triggers inflammatory damage in multiple organs/organ systems.Aberrant activation and death signaling in T, B lymphocytes underlie the pathology of SLE. On a cellular level, the enhanced activity of CD4+T lymphocyte and the deficiency of both CDg+T lymphocyte and NK function result in lack of effective feedback inhibition to B lymphocytes. Decreased CD3ζlevels are concomitant with the appearance of an analogous molecule FcRIy in the TCR-CD3complex, which diverted the TCR initiated signals and are the uppermost part of T cell dysfunction. In recent years, we appreciate that function for B cells in SLE is not exclusive to autoantibody production and several evidence have shed light on the antibody-independent roles of B cells in SLE. B cells can be activated in a T-cell-independent manner. In T-cell-deficient BAFF Tg mice, high levels of BAFF signaling via TACI up-regulated TLR7and TLR9on B cells which in turn up-regulated TACI expression. The cross-talk between and TLR7/9play a role in driving B cell aberrant activation and autoantibody production and therefore, is becoming the research hotspot in the world.B-lymphocyte stimulator (BLyS) is a member of the TNF family (also named BAFF, zTNF4, THANK, and Tall-1). BLyS is produced by myeloid lineage cells, malignant B cells, activated T cells, and bone marrow stromal cells, macrophages, dendritic cells, monocytes. Under normal conditions, BLyS (also known as BAFF) and its three receptors, is required for the development and homeostasis of mature B cells. Under normal conditions, BLyS is the key regulator of primary B cell homeostasis, governing the overall numbers of mature, preimmune B cells. It plays a central role in maintaining B cell tolerance at the TR checkpoint. Once BLyS level rise, it can rescues autoreactive cells of T2stage and the chances of autoreactive B cell maturity become larger. BLyS-BR3interactions are absolutely necessary for primary B cells. The role of TACI is indefinite. On the one hand, TACI can bind both BLyS and APRIL which was initially discovered for its tumorigenic capacity. APRIL-TACI interactions can drive T cell-independent B cell autoantibody response and isotype switching. On the other hand, TACI can down-regulate B cell activation and expansion in TACI-/-mice. So TACI has emerged as a truly unusual TNF receptor and deserved to be study in a deep-going way.Thirty new-onset patients with SLE and Twenty age-matched healthy volunteers were recruited into the current research. Peripheral blood samples were used to analyze the expression of BLyS protein, related receptors (BR3,TACI) and to detect peripheral B cell subsets of different phases. We analyse the correlation between the above mentioned parameters with SLEDAI. By means of TACI-Ig, we inquire into the proliferation of PBMC stimulated by rhBLyS and lymphocyte subpopulation variation, BR3, TACI expression on B cell in vitro.OBJECTIVECollecting clinical data and analyzing T, B lymphocytes subpopulationgs of peripheral blood samples, we are trying to make clear the abnormalities of T, B cells in the patients with SLE and the correlations between lmphocytes subsets and SLEDAI. We next sought to the expression of B lymphocyte stimulator and its two receptors (BR3, TACI) and analyze the relationship with clinical parameters and lymphocyte subsets, trying to inquire into the role of BLyS and its two receptors in the pathogenesis of SLE. Finally we examined the stimulation effects of BLyS on peripheral blood mononuclear cells in vitro and the blocking effect of TACI-Ig on the above shown BLyS stimulation, speculating the effect of TACI-Ig on the treatment of SLE.METHODSThirty patients fulfilling the American College of Rheumatology (ACR) revised criteria for the diagnosis of SLE and twenty age-matched healthy volunteers were recruited. The clinical characteristics of each patients were be perfected and Disease activity index of SLE was graded according to SLEDAI system. Peripheral blood samples were used to analyze the expression of BLyS protein, related receptors (BR3, TACI) and to detect peripheral B cell subsets of different phases. BLyS levels were determined by ELISA. Peripheral B cell subsets were assayed by multiparameter flow cytometry. The expression of BR3, TACI were determined by multiparameter flow cytometry and by real-time ploymerase chain reaction. The proliferation of PBMC stimulated by rhBLyS was measured by MTT assay.RESULTS1. Serum BLyS levels detected by ELISA were increased in patient group in comparison with healthy group (P<0.05).2. In the results examined by multiparameter flow cytometry showed that BR3MFI had no difference between patients and controls (P>0.05). Nevertheless TACI MFI were higher in patients with SLE than in healthy volunteers (P<0.01). In the results examined by real-time ploymerase chain reaction, we found that both BR3mRNA and TACI mRNA levels were all increased in patient groups (P <0.05).3. In the results of B lymphocytes subpopulations, the expression of CD5+,CD27+,CD38+on CD19+B cells were all increased significantly in patient group (P<0.05). Moreover SLEDAI correlated with positively with the percentage of CD19+CD27+and CD19+CD38+(P<0.01).4.The expression rate of CD4+CD25+Foxp3in patients group were decreased compared with controls(P<0.05).5. BLyS levels was observed to show positive correlation with SLEDAI (P<0.05). We also found BLyS levels positively correlated with TACI MFI (P<0.05).6. Only TACI MFI had a positive correlation with SLEDAI (P<0.01) and BR3expression had no relevance with SLEDAI. 7.There was significantly negtive correlation between TACI MFI and lymphocyte numbers (P<0.01) and B cell absolute numbers (P<0.05). There was positive correlation between TACI MFI and anti-dsDNA titers (P<0.01) and renal involvement (P<0.05).8. In the results of experiment in vitro, rhBLyS stimulated the proliferation of PBMC separated from patients with SLE. The suboptimal concentration of rhBLyS was lμg/mL and the optimized stimulation time of rhBLyS was24hours. TACI-Ig can prevent the proliferation of PBMC stimulated by rhBLyS at the concentration of1,10,100μg/mL and can bring about decline in CD38and BR3, TACI expression on B cells.CONCLUSIONS1. Serum BLyS levels increased in patients with SLE. The increased levels of BLyS showed positive correlation with SLEDAI.2. In correspondence with BLyS levels, both BR3mRNA and TACImRNA increased in patients with SLE. But only TACI expression on B cells showed differences between two groups.3. The percentage of B1B cells, plasma cells and memorylike B cells were all increased. The expression of regulatory T cell decreased.4. All that higher expression of BLyS levels and TACI expression on B cells show positive correlation with SLEDAI indicated that both of them play a great role in the mechanism of SLE and they could be potential therapeutic target in SLE treatment.5.TACI-Ig, as a soluble fusion protein, can prevent the proliferation of PBMC stimulated by rhBLyS, can down-regulate the expression of CD38, BR3and TACI on B cells stimulated by rhBLyS.