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

环孢素A （Cyclosporine 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，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，α2β1整合素作为I型胶原在成纤维细胞上的特异性受体。为了阐明α2β1整合素在csa诱导的牙龈过度生长中的作用，我们研究了大鼠牙龈过度生长中胶原吞噬和α2β1整合素的表达。分别饲喂含或不含CsA的粉末状饲料30天，从大鼠的牙龈中分离成纤维细胞。流式细胞术检测成纤维细胞的胶原吞噬和ct2整合素的表达。此外，从成纤维细胞中分离总rna，并采用逆转录-聚合酶链反应研究cx2整合素的mRNA水平。体外胶原吞噬实验显示，csa处理的成纤维细胞和对照成纤维细胞中，吞噬细胞的平均含量分别为13.5%和36.1%。csa处理的成纤维细胞β1整合素表达量比对照组低28%，α2整合素mRNA表达量明显低于对照组，但f31整合素mRNA表达不受影响。此外，在csa处理的大鼠牙龈中，AP-1的一个亚基c-fos的mRNA表达被抑制到对照大鼠牙龈的49%，该亚基与a2整合素的增强区结合并上调其表达。这些发现提示牙龈过度生长的一个病因可能是通过抑制牙龈成纤维细胞中c-fos mRNA的表达来减少cc2整合素的表达，从而抑制胶原吞噬。

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.