Kozlowska E, Sollberg S, Mauch C, Eckes B, Klein C E, Krieg T
Department of Dermatology, University of Cologne, Köln, Germany.
Exp Dermatol. 1996 Feb;5(1):57-63. doi: 10.1111/j.1600-0625.1996.tb00094.x.
Systemic scleroderma (SSc) is a complex connective tissue disorder of unknown etiology. In early stages of the disease, fibroblasts are activated to produce large amounts of collagen with subsequent fibrosis. Collagen metabolism of fibroblasts is modulated by their contact with the extracellular matrix (ECM), which involves distinct receptors on the cell surface, mainly belonging to the integrins. We investigated the expression of collagen receptor alpha 2 beta 1 in SSc and normal fibroblasts, since this receptor has been shown to be utilized by fibroblasts for adhesion to and reorganization of collagen I. 9 strains of scleroderma fibroblasts grown as monolayer cultures were first analyzed with respect to their collagen I expression. 6 of these strains were similar to controls "low" producers) and 3 strains showed up to 2-3 x higher levels of collage I mRNA expression ("high" producers). Northern hybridization using a cDNA probe specific for the alpha 2 integrin subunit revealed a decrease of the corresponding mRNA in SSc fibroblasts as compared to controls (75% versus 100%). "High" collagen producing cell strains displayed the lowest values for alpha 2 integrin mRNA. The decrease of alpha 2 integrin subunit expression at the mRNA level in selected fibroblasts was further substantiated by radioimmunoprecipitation using specific mAbs directed against alpha 2 integrin subunit. No significant changes in beta 1 integrin expression could be observed - neither at mRNA nor at the protein level. Our data indicate a correlation between excessive synthesis of collagen and low levels of alpha 2 integrin subunit expression in SSc fibroblasts. Further experiments should clarify whether this observation is a phenomenon specific for scleroderma or whether it reflects an "activated" state of fibroblasts.
系统性硬化症（SSc）是一种病因不明的复杂结缔组织疾病。在疾病早期，成纤维细胞被激活，产生大量胶原蛋白，随后发生纤维化。成纤维细胞的胶原代谢受其与细胞外基质（ECM）接触的调节，这涉及细胞表面不同的受体，主要属于整合素。我们研究了胶原受体α2β1在系统性硬化症成纤维细胞和正常成纤维细胞中的表达，因为已表明该受体被成纤维细胞用于黏附并重组I型胶原。首先对9株以单层培养方式生长的硬皮病成纤维细胞的I型胶原表达进行了分析。其中6株与对照（“低”生产者）相似，3株显示I型胶原mRNA表达水平高达对照的2 - 3倍（“高”生产者）。使用针对α2整合素亚基的cDNA探针进行Northern杂交显示，与对照相比，系统性硬化症成纤维细胞中相应mRNA减少（75%对100%）。“高”胶原产生细胞株的α2整合素mRNA值最低。使用针对α2整合素亚基的特异性单克隆抗体进行放射免疫沉淀进一步证实了所选成纤维细胞中α2整合素亚基在mRNA水平的表达降低。未观察到β1整合素表达有显著变化——无论是在mRNA水平还是蛋白质水平。我们的数据表明系统性硬化症成纤维细胞中胶原蛋白过度合成与α2整合素亚基低表达之间存在相关性。进一步的实验应阐明这一观察结果是硬皮病特有的现象还是反映了成纤维细胞的“激活”状态。
