van Lieshout A W T, van der Voort R, Toonen L W J, van Helden S F G, Figdor C G, van Riel P L C M, Radstake T R D J, Adema G J
Departments of Rheumatology, Radboud University Nijmegen Medical Centre, The Netherlands.
Ann Rheum Dis. 2009 Jun;68(6):1036-43. doi: 10.1136/ard.2007.086611. Epub 2008 Jul 15.
Chemokine (C-X-C motif) ligand 16 (CXCL16) is secreted by macrophages and dendritic cells (DCs) to attract memory type T cells. CXCL16 expression is increased in arthritic joints of patients with rheumatoid arthritis (RA) and a role for CXCL16 has been suggested in the pathogenesis of RA. To date, little is known about the regulation of CXCL16 on monocytes/macrophages and DCs. The aim of this study was to elucidate how CXCL16 expression is regulated in healthy donors and patients with RA.
CD14+cells were isolated from the peripheral blood or synovial fluid of patients with RA and healthy controls, differentiated into different types of dendritic cells or macrophages and stimulated with various cytokines or lipopolysaccharide (LPS). Cell surface proteins, including surface CXCL16, were measured by flow cytometry and soluble CXCL16 was measured by ELISA.
Distinct types of dendritic cells constitutively express and secrete CXCL16, which is not affected by maturation. Monocytes rapidly upregulate membrane-bound CXCL16 expression and release soluble CXCL16 upon culture. CXCL16 expression by monocytes is transiently inhibited by the Toll-like receptor (TLR)4 ligand LPS. Th2 type cytokines inhibit soluble CXCL16, whereas T helper (Th)1 cell stimulus enhances its release. In RA monocytes/macrophages, neither CXCL16 expression, nor CXCL16 regulation is different from healthy controls.
Culture of monocytes is the main trigger for CXCL16 surface expression in vitro, which is not altered in RA. Together our data suggest that the increased CXCL16 expression in patients with RA is likely to be caused by increased influx of monocytes rather than intrinsic differences in CXCL16 regulation.
趋化因子（C-X-C基序）配体16（CXCL16）由巨噬细胞和树突状细胞（DC）分泌，以吸引记忆型T细胞。类风湿关节炎（RA）患者的关节炎关节中CXCL16表达增加，提示CXCL16在RA发病机制中发挥作用。迄今为止，关于CXCL16对单核细胞/巨噬细胞和DC的调节知之甚少。本研究旨在阐明健康供体和RA患者中CXCL16的表达是如何被调节的。
从RA患者和健康对照者的外周血或滑液中分离出CD14+细胞，将其分化为不同类型的树突状细胞或巨噬细胞，并用各种细胞因子或脂多糖（LPS）进行刺激。通过流式细胞术检测细胞表面蛋白，包括表面CXCL16，并用ELISA检测可溶性CXCL16。
不同类型的树突状细胞组成性表达和分泌CXCL16，其不受成熟的影响。单核细胞在培养时迅速上调膜结合CXCL16的表达并释放可溶性CXCL16。单核细胞的CXCL16表达受到Toll样受体（TLR）4配体LPS的短暂抑制。Th2型细胞因子抑制可溶性CXCL16，而辅助性T（Th）1细胞刺激则增强其释放。在RA单核细胞/巨噬细胞中，CXCL16的表达及其调节与健康对照无差异。
单核细胞培养是体外CXCL16表面表达的主要触发因素，在RA中未发生改变。我们的数据共同表明，RA患者中CXCL16表达增加可能是由于单核细胞流入增加而非CXCL16调节的内在差异所致。
