Jelaska A, Korn J H
Boston University School of Medicine, Boston Department of Veterans Affairs Medical Center, Massachusetts 02118, USA.
Arthritis Rheum. 2000 Oct;43(10):2230-9. doi: 10.1002/1529-0131(200010)43:10<2230::AID-ANR10>3.0.CO;2-8.
We hypothesized that pathophysiologic events during the development of systemic sclerosis (SSc) may lead to selection and propagation of certain apoptosis-resistant fibroblast subpopulations. The aim of this study was to examine a possible role for apoptosis in fibroblast selection in SSc and the role of transforming growth factor beta1 (TGFbeta1).
We compared SSc and normal fibroblasts for their susceptibility to anti-Fas-induced apoptosis and analyzed 2 models that might lead to fibroblast resistance to apoptosis in this process: long-term exposure to either anti-Fas or TGFbeta1.
SSc-derived fibroblasts were resistant to anti-Fas-induced apoptosis, showing 5.5 +/- 17.2% (mean +/- SD) apoptosis, compared with 32.1 +/- 14.0% among normal fibroblasts (P < 0.05). Anti-Fas-selected normal fibroblasts showed 9.0 +/- 3.7% apoptosis, compared with 21.6 +/- 5.9% for sham-treated cells, which is consistent with the elimination of apoptosis-susceptible subpopulations. Normal fibroblasts subjected to 6 weeks of TGFbeta1 treatment showed not only resistance to apoptosis, but also proliferation (118.5 +/- 35.4%), after anti-Fas treatment, compared with sham-treated cells (35.1 +/- 11.1% apoptotic cell death). TGFbeta1 treatment also increased the proportion of myofibroblasts (47% versus 28% in controls). Cultured SSc fibroblasts had a greater proportion of myofibroblasts (32-83%) than did normal fibroblasts (4-25%). We also examined the relationship between collagen gene expression and the myofibroblast phenotype in normal and SSc skin sections. Only 2 of 7 normal sections had alpha-smooth muscle actin (a-SMA)-positive cells (mean +/- SD score 0.29 +/- 0.49 on a scale of 0-3), but all SSc sections were positive for alpha-SMA, with a mean score of 1.90 +/- 0.88 for lesional and 1.50 +/- 0.71 for nonlesional sections. Scores for alpha1(I) procollagen messenger RNA (mRNA) in lesional skin (mean +/- SD 3.30 +/- 0.82 on a scale of 1-4) were significantly higher than in normal (1.43 +/- 0.79) or nonlesional (1.40 +/- 0.52) skin, but scores varied, and there was no correlation between collagen mRNA and alpha-SMA levels.
Our results show that resistance to apoptosis is an important part of the SSc phenotype. TGFbeta1 may play a role by inducing apoptosis-resistant fibroblast populations, and also by inducing myofibroblasts and by enhancing extracellular matrix synthesis.
我们推测系统性硬化症（SSc）发展过程中的病理生理事件可能导致某些抗凋亡成纤维细胞亚群的选择和增殖。本研究的目的是探讨凋亡在SSc成纤维细胞选择中的可能作用以及转化生长因子β1（TGFβ1）的作用。
我们比较了SSc成纤维细胞和正常成纤维细胞对抗Fas诱导凋亡的敏感性，并分析了在此过程中可能导致成纤维细胞抗凋亡的两种模型：长期暴露于抗Fas或TGFβ1。
SSc来源的成纤维细胞对抗Fas诱导的凋亡具有抗性，凋亡率为5.5±17.2%（平均值±标准差），而正常成纤维细胞的凋亡率为32.1±14.0%（P<0.05）。抗Fas选择的正常成纤维细胞凋亡率为9.0±3.7%，而假处理细胞的凋亡率为21.6±5.9%，这与凋亡敏感亚群的消除一致。接受6周TGFβ1处理的正常成纤维细胞在抗Fas处理后不仅表现出抗凋亡能力，而且还出现增殖（118.5±35.4%），而假处理细胞的凋亡率为35.1±11.1%。TGFβ1处理还增加了肌成纤维细胞的比例（47%，而对照组为28%）。培养的SSc成纤维细胞中肌成纤维细胞的比例（32-83%）高于正常成纤维细胞（4-25%）。我们还研究了正常和SSc皮肤切片中胶原基因表达与肌成纤维细胞表型之间的关系。7个正常切片中只有2个有α-平滑肌肌动蛋白（α-SMA）阳性细胞（在0-3评分中平均值±标准差为0.29±0.49），但所有SSc切片的α-SMA均为阳性，病变切片的平均评分为1.90±0.88，非病变切片的平均评分为1.50±0.71。病变皮肤中α1（I）前胶原信使核糖核酸（mRNA）的评分（在1-4评分中平均值±标准差为3.30±0.82）显著高于正常皮肤（1.43±0.79）或非病变皮肤（1.40±0.52），但评分存在差异，胶原mRNA与α-SMA水平之间无相关性。
我们的结果表明，抗凋亡是SSc表型的重要组成部分。TGFβ1可能通过诱导抗凋亡成纤维细胞群体、诱导肌成纤维细胞以及增强细胞外基质合成发挥作用。
