Meszaros Evan C, Malemud Charles J
Department of Medicine, Division of Rheumatic Diseases.
Department of Anatomy, Case Western Reserve University School of Medicine and University Hospitals Cleveland Medical Center, Cleveland, OH, USA.
J Inflamm Res. 2017 Sep 28;10:143-150. doi: 10.2147/JIR.S93797. eCollection 2017.
Two immortalized human juvenile chondrocyte cell lines, T/C28a2 and C28/I2, were employed to determine the extent to which recombinant human (rh) IL-6, a known cytokine activator of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway in many cell types, caused STAT proteins to be phosphorylated. The results showed that STAT3 was constitutively phosphorylated in the absence of rhIL-6 in T/C28a2 chondrocytes. However, C28/I2 chondrocytes treated with rhIL-6 caused STAT1, STAT3, and STAT5 to be phosphorylated without altering total unphosphorylated STAT proteins. STAT3 phosphorylation in response to rhIL-6 in T/C28a and C28/I2 chondrocytes was efficiently blocked by the JAK3-selective inhibitor WHI-P131 (Janex-1) and by soluble IL-6 receptor-α (sIL-6R). However, the combination of rhIL-6 and ruxolitinib, a JAK1/JAK2-selective inhibitor, was a less effective inhibitor of STAT protein activation. These findings showed that rhIL-6 activated STAT proteins in the C28/I2 chondrocyte cell line. STAT protein phosphorylation could be blocked by a JAK3-selective inhibitor or by the combination of rhIL-6 and sIL-6R.
采用两种永生化的人类幼年软骨细胞系T/C28a2和C28/I2，以确定重组人（rh）IL-6（已知在许多细胞类型中为Janus激酶/信号转导子和转录激活子（JAK/STAT）途径的细胞因子激活剂）导致STAT蛋白磷酸化的程度。结果显示，在T/C28a2软骨细胞中，STAT3在不存在rhIL-6的情况下组成性磷酸化。然而，用rhIL-6处理的C28/I2软骨细胞导致STAT1、STAT3和STAT5磷酸化，而未改变总的未磷酸化STAT蛋白。在T/C28a和C28/I2软骨细胞中，JAK3选择性抑制剂WHI-P131（Janex-1）和可溶性IL-6受体α（sIL-6R）有效阻断了rhIL-6诱导的STAT3磷酸化。然而，rhIL-6与JAK1/JAK2选择性抑制剂鲁索替尼的组合对STAT蛋白激活的抑制效果较差。这些发现表明，rhIL-6在C28/I2软骨细胞系中激活了STAT蛋白。STAT蛋白磷酸化可被JAK3选择性抑制剂或rhIL-6与sIL-6R的组合阻断。
