Kitano Masayasu, Hla Timothy, Sekiguchi Masahiro, Kawahito Yutaka, Yoshimura Rikio, Miyazawa Keiji, Iwasaki Tsuyoshi, Sano Hajime, Saba Julie D, Tam Yuen Yee
Hyogo College of Medicine, Nishinomiya-city, Hyogo, Japan.
Arthritis Rheum. 2006 Mar;54(3):742-53. doi: 10.1002/art.21668.
Sphingosine 1-phosphate (S1P) is involved in various pathologic conditions and has been implicated as an important mediator of angiogenesis, inflammation, cancer, and autoimmunity. This study was undertaken to examine the role of S1P/S1P1 signaling in the pathogenesis of rheumatoid arthritis (RA).
We examined S1P1 messenger RNA (mRNA) and protein levels in RA synoviocytes and MH7A cells by reverse transcriptase-polymerase chain reaction and Western blotting. We also performed S1P1 immunohistochemistry analysis in synovial tissue from 28 RA patients and 18 osteoarthritis (OA) patients. We investigated the effects of S1P on proliferation by WST-1 assay, and its effects on tumor necrosis factor alpha (TNFalpha)- or interleukin-1beta (IL-1beta)-induced cyclooxygenase 2 (COX-2) expression and prostaglandin E2 (PGE2) production in RA synoviocytes and MH7A cells by Western blotting and enzyme-linked immunosorbent assay, respectively. Finally, we examined whether these effects of S1P were sensitive to pertussis toxin (PTX), an inhibitor of the Gi/Go proteins.
S1P1 mRNA and protein were detected in RA synoviocytes and MH7A cells. S1P1 was more strongly expressed in synovial lining cells, vascular endothelial cells, and inflammatory mononuclear cells of RA synovium compared with OA synovium. S1P increased the proliferation of RA synoviocytes and MH7A cells. S1P alone significantly enhanced COX-2 expression and PGE2 production. Moreover, S1P enhanced expression of COX-2 and production of PGE2 induced by stimulation with TNFalpha or IL-1beta in RA synoviocytes and MH7A cells. These effects of S1P were inhibited by pretreatment with PTX.
These findings suggest that S1P signaling via S1P receptors plays an important role in cell proliferation and inflammatory cytokine-induced COX-2 expression and PGE2 production by RA synoviocytes. Thus, regulation of S1P/S1P1 signaling may represent a novel therapeutic target in RA.
1-磷酸鞘氨醇（S1P）参与多种病理状况，并且被认为是血管生成、炎症、癌症和自身免疫的重要介质。本研究旨在探讨S1P/S1P1信号在类风湿关节炎（RA）发病机制中的作用。
我们通过逆转录聚合酶链反应和蛋白质印迹法检测RA滑膜细胞和MH7A细胞中S1P1信使核糖核酸（mRNA）和蛋白质水平。我们还对28例RA患者和18例骨关节炎（OA）患者的滑膜组织进行了S1P1免疫组织化学分析。我们通过WST-1法研究S1P对增殖的影响，并分别通过蛋白质印迹法和酶联免疫吸附测定法研究其对RA滑膜细胞和MH7A细胞中肿瘤坏死因子α（TNFα）或白细胞介素-1β（IL-1β）诱导的环氧化酶2（COX-2）表达和前列腺素E2（PGE2）产生的影响。最后，我们研究了S1P的这些作用是否对百日咳毒素（PTX）敏感，PTX是Gi/Go蛋白的抑制剂。
在RA滑膜细胞和MH7A细胞中检测到S1P1 mRNA和蛋白质。与OA滑膜相比，S1P1在RA滑膜的滑膜衬里细胞、血管内皮细胞和炎性单核细胞中表达更强。S1P增加了RA滑膜细胞和MH7A细胞的增殖。单独的S1P显著增强COX-2表达和PGE2产生。此外，S1P增强了RA滑膜细胞和MH7A细胞中TNFα或IL-1β刺激诱导的COX-2表达和PGE2产生。S1P的这些作用被PTX预处理所抑制。
这些发现表明，通过S1P受体的S1P信号在RA滑膜细胞的细胞增殖以及炎性细胞因子诱导的COX-2表达和PGE2产生中起重要作用。因此，调节S1P/S1P1信号可能代表RA的一种新的治疗靶点。
