Study on signal transduction pathway via integrins in autoimmune T cells

整合素及其配体在炎症反应的第一步，如白细胞与内皮细胞的粘附中起着关键作用。在这里，我们通过共聚焦图像分析仪显示，在RA滑膜细胞的血管周围和下层区域观察到抗β 1和抗磷酸酪氨酸的双重染色信号，而在OA中未检测到，这提出了粘附相互作用不仅介导粘附，而且将信号传递到细胞中的可能性，有助于维持RA滑膜的炎症。为了探讨其作用机制，我们在体外培养的滑膜细胞中检测了酪氨酸磷酸化。磷酸酪氨酸免疫印迹显示RA滑膜细胞中有5条主要蛋白质带，而OA中几乎没有微弱的条带。由于5条主要蛋白质带中pp125在RA滑膜细胞中最突出，我们接下来检查pp125是否是FAK。pp125 FAK的酪氨酸磷酸化水平在RA滑膜细胞中明显升高。此外，激光共聚焦显微镜显示，在巨噬细胞样滑膜细胞中大量检测到抗磷酸酪氨酸和抗pp125 FAK的信号。

It is now well recognized that integrins and their ligands are pivotal role in the first step of inflammation such as the adhesion between the leukocytes and the endothelial cells. Here, we showed data by a confocal image analyzer that the double stainig signals by anti-beta1 and anti-phosphotyrosine were observed in the perivascular and sublining areas in RA synovial cells, while it was not detected in OA,raising a possibility that the adhesive interaction not only mediates adhesion, but delivers the signals into the cell, contributing to maintain inflammation in RA synovium. To explore the mechanism, we examined the tyrosine phosphorylation of synovial cells in vitro culture system. The immunoblot for hospho-tyrosine demonstrated the five major proteins form the synovial cells in RA,while few faint bands were detected in OA.Since the pp125, among five major bands, was most prominent in RA synovial cells, we next examined whether pp125 is FAK or not.Immunoprecipitation with anti-pp125FAK has demonstrated that the band was pp125FAK itself and the tyrosine phosphorylation of pp125FAK was significantly elevated in RA synovial cells. Furthermore, confocal laser microscopy showed that the signals by anti-phosphotyrosine and anti-pp125FAK were abundantly detected in macrophage-like synovial cells.