Manzo Antonio, Vitolo Barbara, Humby Frances, Caporali Roberto, Jarrossay David, Dell'accio Francesco, Ciardelli Laura, Uguccioni Mariagrazia, Montecucco Carlomaurizio, Pitzalis Costantino
St. Bartholomew's and Royal London School of Medicine, London, UK.
Arthritis Rheum. 2008 Nov;58(11):3377-87. doi: 10.1002/art.23966.
Synovial B cells play a critical role in rheumatoid arthritis (RA), being involved in autoantibody synthesis, T cell activation, and cytokine production. CXCL13 is a B cell chemoattractant that is instrumental in synovial B cell organization; the regulatory determinants of CXCL13 in inflammation are poorly characterized. This study was undertaken to investigate the functional involvement of synovial T cells in the ectopic expression of CXCL13 in RA.
CXCL13 production and regulation were addressed using immunohistochemistry, in situ hybridization, quantitative polymerase chain reaction, multicolor flow cytometry, and enzyme-linked immunosorbent assay, by in situ-ex vivo analysis and in vitro functional assays with rheumatoid synovial tissue and primary cells.
CXCL13 messenger RNA and protein expression and spontaneous CXCL13 secretion were detected in RA synovial fluid T cells but were not detected (or were detected only occasionally) in peripheral blood T cells. Analysis of tissue expression confirmed cytoplasm localization of CXCL13 in T lymphocytes infiltrating B cell follicles and small perivascular aggregates. Multicolor characterizations in synovial fluid demonstrated CXCL13 expression in antigen-experienced T helper cells, frequently characterized by terminal differentiation and the lack of the follicular helper T cell markers CXCR5 and BCL6 protein. In vitro functional assays revealed the enhancing effect of T cell receptor-CD28 engagement on CXCL13 production and secretion in primary cells.
Our findings define a new functional property of synovial T cells, demonstrating their active involvement in the local production of B cell chemoattractants, and support a direct contribution of the adaptive immune system and antigen-dependent signals in the mechanisms of B cell localization in RA.
滑膜B细胞在类风湿关节炎（RA）中起关键作用，参与自身抗体合成、T细胞活化和细胞因子产生。CXCL13是一种B细胞趋化因子，对滑膜B细胞的组织形成至关重要；CXCL13在炎症中的调节决定因素尚不明确。本研究旨在探讨滑膜T细胞在RA中CXCL13异位表达中的功能作用。
通过免疫组织化学、原位杂交、定量聚合酶链反应、多色流式细胞术和酶联免疫吸附测定，采用原位-离体分析以及类风湿滑膜组织和原代细胞的体外功能测定，研究CXCL13的产生和调节。
在RA滑膜液T细胞中检测到CXCL13信使核糖核酸和蛋白表达以及自发CXCL13分泌，但在外周血T细胞中未检测到（或仅偶尔检测到）。组织表达分析证实CXCL13在浸润B细胞滤泡和小血管周围聚集物的T淋巴细胞的细胞质中定位。滑膜液中的多色表征显示CXCL13在抗原接触过的辅助性T细胞中表达，这些细胞通常具有终末分化特征，且缺乏滤泡辅助性T细胞标志物CXCR5和BCL6蛋白。体外功能测定显示T细胞受体-CD28结合对原代细胞中CXCL13的产生和分泌有增强作用。
我们的研究结果定义了滑膜T细胞的一种新功能特性，证明它们积极参与B细胞趋化因子的局部产生，并支持适应性免疫系统和抗原依赖性信号在RA中B细胞定位机制中的直接作用。
