Kim J-Y, Kwok S-K, Hur K-H, Kim H-J, Kim N S, Yoo S-A, Kim W-U, Cho C-S
Division of Rheumatology, Department of Internal Medicine, School of Medicine, Catholic University of Korea, Seoul, South Korea.
Clin Exp Immunol. 2008 May;152(2):328-35. doi: 10.1111/j.1365-2249.2008.03637.x. Epub 2008 Mar 18.
Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that has been demonstrated to regulate the apoptosis of several cell types. Dysregulated apoptosis of fibroblasts has been implicated in a variety of fibrotic diseases, including systemic sclerosis (SSc). In this study, we investigated the role of MIF in the apoptosis of dermal fibroblasts. The concentrations of MIF were measured in sera and in culture supernatants of peripheral blood mononuclear cells (PBMCs) and dermal fibroblasts by enzyme-linked immunosorbent assay. The degree of apoptosis was determined by colorimetric assay, and signalling pathways were examined by Western blot. The results showed that serum levels of MIF were significantly higher in patients with SSc (n = 47) than in healthy controls (n = 56). Stimulation of PBMCs by anti-CD3 and anti-CD28 increased the production of MIF by fourfold over the constitutive levels. SSc dermal fibroblasts produced higher amounts of MIF than normal dermal fibroblasts. When treated with sodium nitroprusside (SNP), SSc dermal fibroblasts showed a lower degree of apoptosis compared with normal dermal fibroblasts. Exogenous MIF (1-100 ng/ml) inhibited SNP-induced apoptosis of dermal fibroblasts dose-dependently. Both extracellular regulated kinase (ERK) inhibitor (PD98059) and protein kinase B (Akt) inhibitor (LY294002) almost completely blocked the inhibitory effect of MIF on apoptosis. Furthermore, MIF increased the expression of Bcl-2, phospho-ERK and phospho-Akt activity in dermal fibroblasts. Taken together, our data suggest that MIF released by activated T cells and dermal fibroblasts decreases the apoptosis of dermal fibroblasts through activation of ERK, Akt and Bcl-2 signalling pathways, which might be associated with excessive fibrosis in SSc.
巨噬细胞移动抑制因子（MIF）是一种促炎细胞因子，已被证明可调节多种细胞类型的凋亡。成纤维细胞凋亡失调与多种纤维化疾病有关，包括系统性硬化症（SSc）。在本研究中，我们调查了MIF在真皮成纤维细胞凋亡中的作用。通过酶联免疫吸附测定法测量血清、外周血单核细胞（PBMC）和真皮成纤维细胞培养上清液中MIF的浓度。通过比色法测定凋亡程度，并通过蛋白质印迹法检测信号通路。结果显示，SSc患者（n = 47）的血清MIF水平显著高于健康对照组（n = 56）。用抗CD3和抗CD28刺激PBMC可使MIF的产生比基础水平增加四倍。SSc真皮成纤维细胞产生的MIF比正常真皮成纤维细胞多。用硝普钠（SNP）处理时，SSc真皮成纤维细胞与正常真皮成纤维细胞相比凋亡程度较低。外源性MIF（1-100 ng/ml）剂量依赖性地抑制SNP诱导的真皮成纤维细胞凋亡。细胞外调节激酶（ERK）抑制剂（PD98059）和蛋白激酶B（Akt）抑制剂（LY294002）几乎完全阻断了MIF对凋亡的抑制作用。此外，MIF增加了真皮成纤维细胞中Bcl-2的表达、磷酸化ERK和磷酸化Akt的活性。综上所述，我们的数据表明，活化的T细胞和真皮成纤维细胞释放的MIF通过激活ERK、Akt和Bcl-2信号通路降低真皮成纤维细胞的凋亡，这可能与SSc中的过度纤维化有关。
