López-Santalla Mercedes, Salvador-Bernáldez María, González-Alvaro Isidoro, Castañeda Santos, Ortiz Ana M, García-García María Isabel, Kremer Leonor, Roncal Fernando, Mulero Juan, Martínez-A Carlos, Salvador Jesús M
Centro Nacional de Biotecnología, CSIC, Madrid, Spain.
Arthritis Rheum. 2011 Jul;63(7):1833-42. doi: 10.1002/art.30375.
The p38 MAPK is important in the pathogenic immune response in rheumatoid arthritis (RA). The p38 molecule can be activated through phosphorylation on Thr¹⁸⁰-Tyr¹⁸² by upstream MAPK kinases and via an alternative pathway through phosphorylation on Tyr³²³. We undertook this study to quantify the phosphorylation of Tyr³²³ p38 and of Thr¹⁸⁰-Tyr¹⁸² p38 on T cells from healthy controls and patients with RA or ankylosing spondylitis (AS) to identify variables associated with p38 phosphorylation and disease activity.
We measured p38 phosphorylation on Tyr³²³ and Thr¹⁸⁰-Tyr¹⁸² by flow cytometry and Western blotting on T cells from 30 control subjects, 33 AS patients, 30 patients with RA in remission, and 79 patients with active RA. We collected the clinical characteristics and analyzed correlations between clinical variables, the Disease Activity Score in 28 joints (DAS28), and p38 phosphorylation levels. Multivariate regression analysis was performed to identify variables associated with p38 phosphorylation on Tyr³²³ and Thr¹⁸⁰-Tyr¹⁸².
Phosphorylation of p38 on Tyr³²³ was higher in T cells from patients with active RA (P = 0.008 versus healthy controls) than in patients with RA in remission or in patients with AS. Tyr³²³ p38 phosphorylation was associated with disease activity determined by the DAS28 (P = 0.017). Enhanced p38 phosphorylation was linked to Lck-mediated activation of the Tyr³²³-dependent pathway in the absence of upstream MAPKK activation.
Our results indicate that phosphorylation status on Tyr³²³ p38 correlates with RA disease activity and suggest that the Tyr³²³-dependent pathway is an attractive target for down-regulation of p38 activity in RA patients.
p38丝裂原活化蛋白激酶（MAPK）在类风湿关节炎（RA）的致病性免疫反应中起重要作用。p38分子可通过上游MAPK激酶使其苏氨酸¹⁸⁰ - 酪氨酸¹⁸²位点磷酸化而被激活，也可通过酪氨酸³²³位点磷酸化的另一条途径被激活。我们开展这项研究旨在量化健康对照者以及RA或强直性脊柱炎（AS）患者T细胞上酪氨酸³²³ p38和苏氨酸¹⁸⁰ - 酪氨酸¹⁸² p38的磷酸化水平，以确定与p38磷酸化及疾病活动相关的变量。
我们通过流式细胞术和蛋白质印迹法检测了30名对照者、33名AS患者、30名缓解期RA患者以及79名活动期RA患者T细胞上酪氨酸³²³和苏氨酸¹⁸⁰ - 酪氨酸¹⁸²位点的p38磷酸化情况。我们收集了临床特征，并分析了临床变量、28个关节疾病活动评分（DAS28）与p38磷酸化水平之间的相关性。进行多变量回归分析以确定与酪氨酸³²³和苏氨酸¹⁸⁰ - 酪氨酸¹⁸²位点p38磷酸化相关的变量。
活动期RA患者T细胞中酪氨酸³²³位点的p38磷酸化水平高于缓解期RA患者或AS患者（与健康对照者相比，P = 0.008）。酪氨酸³²³ p38磷酸化与DAS28所确定的疾病活动相关（P = 0.017）。在缺乏上游MAPKK激活的情况下，p38磷酸化增强与Lck介导的酪氨酸³²³依赖性途径的激活有关。
我们的结果表明，酪氨酸³²³ p38的磷酸化状态与RA疾病活动相关，并提示酪氨酸³²³依赖性途径是RA患者中下调p38活性的一个有吸引力的靶点。
