Maas-Szabowski N, Fusenig N E
Division of Differentiation and Carcinogenesis, German Cancer Research Center, Heidelberg.
J Invest Dermatol. 1996 Dec;107(6):849-55. doi: 10.1111/1523-1747.ep12331158.
Tissue homeostasis in skin is regulated by epithelial-mesenchymal interactions, mostly operating via diffusible factors. To study the underlying regulatory mechanisms, in vitro systems have been established to mimic the in vivo situation in skin. In co-cultures, keratinocytes grow either adjacent to irradiated fibroblasts on plastic or on top of collagen gels containing fibroblasts, thus forming 3-dimensional organotypic structures. Keratinocyte growth is supported in part by fibroblast-produced factors induced by keratinocyte mediators such as interleukin-1 (IL-1). To better understand this cellular interaction and its modulation by fibroblast proliferation and extracellular matrix (ECM), we examined the effect of IL-1 on growth factor expression in proliferating and growth-arrested x-irradiated human dermal fibroblasts on plastic and in resting cells embedded in collagen gels. By semiquantitative reverse transcriptase PCR, we demonstrated that IL-1alpha and IL-1beta stimulated the expression of KGF, HGF, IL-1alpha, IL-1beta, IL-1RI, and IL-8 in fibroblasts regardless of their physiologic condition, whereas that of TGF-beta remained unaffected. The constitutive mRNA levels were usually lower in irradiated postmitotic and ECM-embedded cells than in proliferating fibroblasts. Cells responded to stimulation with IL-1 under all three culture conditions, although to different degrees depending on the growth factor. As demonstrated for HGF, IL-8, and IL-1beta, the IL-1alpha-induced mRNA expression was followed by production and secretion of protein in irradiated fibroblasts. Thus, our findings show that resting and growth-inhibited fibroblasts, reflecting more closely the situation in dermis, exhibit lower constitutive growth factor expression levels but characteristically respond to IL-1 stimulation.
皮肤中的组织稳态由上皮-间充质相互作用调节，主要通过可扩散因子发挥作用。为了研究潜在的调节机制，已建立体外系统来模拟皮肤中的体内情况。在共培养中，角质形成细胞要么在塑料上与经辐照的成纤维细胞相邻生长，要么在含有成纤维细胞的胶原凝胶上生长，从而形成三维器官样结构。角质形成细胞的生长部分受到成纤维细胞产生的因子的支持，这些因子由角质形成细胞介质如白细胞介素-1（IL-1）诱导产生。为了更好地理解这种细胞间相互作用及其受成纤维细胞增殖和细胞外基质（ECM）的调节，我们研究了IL-1对在塑料上增殖和生长停滞的经X射线辐照的人真皮成纤维细胞以及嵌入胶原凝胶中的静止细胞中生长因子表达的影响。通过半定量逆转录酶PCR，我们证明IL-1α和IL-1β刺激成纤维细胞中KGF、HGF、IL-1α、IL-1β、IL-1RI和IL-8的表达，无论其生理状态如何，而TGF-β的表达不受影响。有丝分裂后经辐照的细胞和嵌入ECM的细胞中的组成型mRNA水平通常低于增殖的成纤维细胞。在所有三种培养条件下，细胞都对IL-1刺激有反应，尽管根据生长因子的不同程度有所差异。正如对HGF、IL-8和IL-1β所证明的那样，IL-1α诱导的mRNA表达之后是经辐照的成纤维细胞中蛋白质的产生和分泌。因此，我们的研究结果表明，静止和生长受抑制的成纤维细胞更能反映真皮中的情况，其组成型生长因子表达水平较低，但对IL-1刺激具有特征性反应。
