BLyS Participate In The Interaction Between T And B Lymphocytes In Collagen-induced Arthritis Mice And The Effect Of TACI-Ig

Rheumatoid arthritis (RA) is a systemic autoimmune disease, which T and B lymphocytes involved in. B lymphocytes responses to most antigens and produces antibodies rely on the interaction between T and B lymphocytes. B lymphocytes not only are assisted by helper T (Th) cell, but also are antigen presenting cell (APC) during the activation of T lymphocytes. Double signals are required for the activation of T and B lymphocytes. First signal is the complex of class II major histocompability complex (MHC) and T cell receptor (TCR)/B cell receptor (BCR). Second signal are co-stimulatory molecules, including CD28-B7and CD40-CD40L. CD28-B7is mainly related to the activation and proliferation of T lymphocytes. B lymphocyte stimulator (BLyS) plays an important role in B lymphocytes maturation survival. Whether does BLyS involve in the interaction between T and B lymphocytes? If the answer is yes, whether does BLyS regulate the interaction between T and B lymphocytes through CD28-B7, CD40-CD40L co-stimulatory molecules? Which have being still unclear. TACI-Ig is a soluble glycoprotein comprising a human IgGl-Fc fused with the extracellular domain of the human TACI receptor. TACI-Ig could bind with BLyS competitively, which can block B lymphocyte activation mediated by BLyS. Previous study in our lab showed that TACI-Ig could inhibit secondary inflammation in mice with collagen induced arthritis (CIA) through regulating the interaction of T and B lymphocytes. However, there was no report that whether TACI-Ig could regulate the interaction of T and B lymphocytes in CIA mice. The current study was to investigate the role of BLyS on the interaction between T and B lymphocytes in normal and CIA mice and the regulatory of TACI-Ig.Aim:To investigate the role of BLyS on the interaction between T and B lymphocytes in normal and CIA mice and the effects of TACI-Ig.Methods:CIA models were established in DBA/1mice. T and B lymphocytes were co-cultured in BLyS with or without anti-BLyS or TACI-Ig in Transwell insert. To investigate the effect of activated T lymphocytes stimulated by BLyS on B lymphocytes (T lymphocytes proliferation, the levels of levels of IL-2, IL-17in T lymphocytes supernatant, the protein expressions of CD28and CD154(CD40L), the percentages of CD4+CD28+T lymphocytes, CD4+CD154+T lymphocytes), the effect of activated B lymphocytes stimulated by BLyS on T lymphocytes (B lymphocytes proliferation, the levels of levels of IgM in B lymphocytes supernatant, the protein expressions of CD40and CD80(B7), the percentages of CD19+CD40+B lymphocytes, CD19+CD80+B lymphocytes), and to analyze the effect of B lymphocytes of TACI silence on T lymphocytes.The methods of quantitative real-time PCR (qPCR) was utilized to detect the mRNA expressions of BLyS and TACI in the thymus and spleen, the levels of IL-2, IL-17and IgM in T/B lymphocytes co-cultrue supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was used to test the percentages of the CD4+CD154+T lymphocytes, CD4+CD28+T lymphocytes and CD19+CD40+B lymphocytes and CD19+cD80+B lymphocytes, and the expressions of CD28, CD154, CD40and CD80were analyzed by western-blot, MTT was utilized to measure the proliferations of T and B lymphocytes. Results:1. BLyS promoted the interaction between T and B lymphocytes in normal mice, TACI-Ig could inhibit the interaction between T and B lymphocytes in normal mice1.1B lymphocytes activated by BLyS could promote the function of T lymphocytes, TACI-Ig could inhibit the function of T lymphocytes which were co-cultured with B lymphocytes activated by BLySB lymphocytes activated by BLyS up-regulated levels of IL-2and IL-17in T lymphocytes supernatant, increased the percentages of CD4-+CD154+, CD4+CD28+T lymphocytes, and elevated the expression of CD154, CD28. Meanwhile, TACI-Ig down-regulated levels of IL-2and IL-17in T lymphocytes supernatant, reduced the percentages of CD4+CD154+, CD4+CD28+T lymphocytes, and inhibited the expression of CD154, CD28.1.2T lymphocytes activated by BLyS could promote the function of B lymphocytes, TACI-Ig could inhibit the function of B lymphocytes which were co-cultured with T lymphocytes activated by BLyST lymphocytes activated by BLyS up-regulated levels of IgM in B lymphocytes supernatant, increased the percentages of CD19+CD40+, CD19+CD80+B lymphocytes, and elevated the expression of CD40, CD80. Meanwhile, TACI-Ig down-regulated levels of IgM in B lymphocytes supernatant, reduced the percentages of CD19+CD40+, CD19+CD80+B lymphocytes, and inhibited the expression of CD40, CD80. 2. BLyS promoted the interaction between T and B lymphocytes in CIA mice, TACI-Ig could inhibit the interaction between T and B lymphocytes2.1The mRNA expression of BLyS was increased in the thymus and spleen in CIA mice, the mRNA expression of TACI was lower in the thymus and spleen in CIA mice.Compared with normal mice, the mRNA expression of BLyS was increased in the thymus and spleen in CIA mice. However, the mRNA expression of TACI was lower in the thymus and spleen in CIA mice.2.2B lymphocytes activated by BLyS could promote the function of T lymphocytes in CIA mice, TACI-Ig could inhibit the function of T lymphocytes which were co-cultured with B lymphocytes activated by BLySB lymphocytes activated by BLyS promoted the T lymphocytes proliferation, increased the percentages of CD4+CD154+, CD4+CD28+T lymphocytes. Meanwhile, TACI-Ig inhibited the T lymphocytes proliferation, reduced the percentages of CD4+CD154+, CD4+CD28+T lymphocytes.2.3T lymphocytes activated by BLyS could promote the function of B lymphocyte in CIA mice, TACI-Ig could inhibit the function TACI-Ig could inhibit the function of B lymphocytes which were co-cultured with T lymphocytes activated by BLyST lymphocytes activated by BLyS promoted the B lymphocytes proliferation, increased the percentages of CD19+CD40+, CD19+CD80+B lymphocytes. Meanwhile, TACI-Ig inhibited the T lymphocytes proliferation, reduced the percentages of CD19+CD40+, CD19+080+lymphocytes3. BTACI-lymphocytes activated by BLyS could promote the function of T lymphocytesThe mRNA and protein expressions of CD40and CD80in BTACI-cells (activated by BLyS) were higher than that in normal B lymphocytes (activated by BLyS). BLyS could promote the expression of CD154mRNA, CD28mRNA, and the proteins expression of CD154and CD28markedly raised in T/BTACI-cells co-cultrue group.Conclusion:1. BLyS could promote interaction of T and B lymphocytes via CD28-B7, CD40-CD40L co-stimulatory molecules.2. TACI might not be the main receptor, which BLyS promote interaction of T and B lymphocytes through.3. TACI-Ig exerted its inhibited effects on interaction of T and B lymphocytes. It might be one of mechanisms that TACI-Ig regulated the interaction of T and B lymphocytes through neutralizing BLyS and inhibiting the expression of the co-stimulatory molecules.