Study of AP-1 in cyclosporine A-induced gingival overgrowth in rats.

环孢菌素A(CsA)是一种免疫抑制剂，通过减少成纤维细胞对胶原的吞噬作用而诱导纤维性牙龈过度生长。在胶原吞噬过程中，不同的受体参与了胶原与成纤维细胞的结合，而α2β1整合素是成纤维细胞上I型胶原的特异性受体。为了阐明α2f3l整合素在CsA诱导的牙龈过度生长中的作用，我们观察了CsA诱导的大鼠牙龈过度生长过程中胶原的吞噬作用和β2整合素的表达。流式细胞仪检测成纤维细胞的胶原吞噬功能和ct2整合素的表达。提取成纤维细胞总RNA，用逆转录聚合酶链式反应检测cx2整合素的mRNA水平。体外胶原吞噬实验显示，CsA处理组和对照组大鼠牙周成纤维细胞的平均吞噬细胞数分别为13.5%和36.1%。CsA处理组成纤维细胞β1整合素表达较对照组降低2 8%，α2整合素基因表达明显低于对照组，而F31整合素基因表达无明显变化。此外，CsA处理的大鼠牙周组织中结合a2整合素增强子区域并上调其表达的亚基AP-1的c-fos的mRNA表达被抑制到对照大鼠的49%。这些发现表明，牙龈过度生长的原因之一可能是通过抑制牙龈成纤维细胞中CC2整合素的表达，从而抑制胶原的吞噬作用。

Cyclosporine A (CsA), an immunosuppresive agent, induces fibrous gingival overgrowth through reduction of collagen phagocytosis by fibroblasts. Distinct receptors are involved in the binding of collagen to fibroblasts in collagen phagocytosis, and α2β1 integrin serves as a specific receptor for type I collagen on fibroblasts. To elucidate the role ofa2f3l integrin in CsA-induced gingival overgrowth, we investigated collagen phagocytosis and α2β1 integrin expression in rat gingival overgrowth.Fibroblasts were isolated from gingiva of rats fed a powdered diet containing or lacking CsA for 30 days. Flow cytometric analysis were performed to measure the collagen phagocytosis and the ct2 integrin expression in fibroblasts. Furthermore, total RNAs were isolated from fibroblasts, and the reverse transcriptase-polymerase chain reaction was employed to investigate the mRNA levels of cx2 integrin. And cDNA microarrays were performed to examine the various RNA expressions in CsA-treated and control rat gingivalIn vitro collagen phagocytosis assay revealed that CsA-treated and control fibroblasts contained a mean of 13.5% and 36.1% phagocytic cells, respectively. CsA-treated fibroblasts had 28% lower expression of β1 integrin than that of control, and mRNA expression of α2 integrin in CsA-treated fibroblasts was apparently lower than in the controls, but the mRNA expression of f31 integrin was not affected. Furthermore, mRNA expression of c-fos in CsA-treated rat gingiva, a subunit of AP-1, which binds to enhancer region of a2 integrin and up-regulates of it expression, was suppressed to 49% of control rat gingiva.These findings suggest that one etiological factor of gingival overgrowth may be inhibition of collagen phagocytosis by reducing cc2 integrin expression through the inhibition of c-fos mRNA in gingival fibroblasts.