Lisby S, Müller K M, Jongeneel C V, Saurat J H, Hauser C
Department of Dermatology, Hôpital Cantonal Universitaire, Geneva, Switzerland.
Int Immunol. 1995 Mar;7(3):343-52. doi: 10.1093/intimm/7.3.343.
A critical role of tumor necrosis factor (TNF)-alpha in irritant contact dermatitis and in the challenge phase of allergic contact dermatitis has recently been demonstrated in vivo. As in situ hybridization studies have indicated that keratinocytes were the cellular source of TNF-alpha in these reactions, we studied the mechanisms of TNF-alpha mRNA induction in keratinocytes by agents that induce contact dermatitis. Murine la-/CD3- epidermal cells were stimulated with phorbol myristate acetate (PMA), dimethylsulfoxide (DMSO), sodium dodecyl sulfate (SDS) and NiSO4, all of which up-regulated epidermal cell TNF-alpha mRNA production. In contrast, trinitrobenzenesulfonic acid and trinitrochlorobenzene did not significantly up-regulate TNF-alpha mRNA. These results were confirmed with murine keratinocyte cell lines. In keratinocytes transfected with a chloramphenicol acetyltransferase construct containing the -1059 to +138 base pair TNF-alpha promoter, increased promoter activity was observed upon stimulation with PMA and DMSO. In addition, PMA stimulation did not affect the stability of TNF-alpha mRNA. The PMA- but also the DMSO- and SDS- induced up-regulation of TNF-alpha mRNA was abolished by an inhibitor of protein kinase C (PKC). In contrast, NiSO4 up-regulated TNF-alpha mRNA by a PKC-independent mechanism, did not increase TNF-alpha promoter activity, but markedly increased the stability of the TNF-alpha mRNA. Co-stimulation with PMA and NiSO4 induced a marked increase in TNF-alpha mRNA over that obtained with each agent alone. Thus, whereas PKC-dependent irritants act by up-regulating TNF-alpha promoter activity, nickel acts via post-transcriptional regulation. Our results also establish that some irritants and irritant sensitizers directly induce TNF-alpha in keratinocytes without intermediate Langerhans cell-derived signals.
肿瘤坏死因子（TNF）-α在刺激性接触性皮炎及过敏性接触性皮炎激发阶段所起的关键作用最近已在体内得到证实。原位杂交研究表明角质形成细胞是这些反应中TNF-α的细胞来源，因此我们研究了诱导接触性皮炎的试剂对角质形成细胞中TNF-α mRNA诱导的机制。用佛波酯（PMA）、二甲基亚砜（DMSO）、十二烷基硫酸钠（SDS）和硫酸镍（NiSO4）刺激小鼠la-/CD3-表皮细胞，所有这些试剂均上调表皮细胞TNF-α mRNA的产生。相比之下，三硝基苯磺酸和三硝基氯苯并未显著上调TNF-α mRNA。这些结果在小鼠角质形成细胞系中得到证实。在用含有-1059至+138碱基对TNF-α启动子的氯霉素乙酰转移酶构建体转染的角质形成细胞中，PMA和DMSO刺激后观察到启动子活性增加。此外，PMA刺激不影响TNF-α mRNA的稳定性。蛋白激酶C（PKC）抑制剂可消除PMA以及DMSO和SDS诱导的TNF-α mRNA上调。相比之下，NiSO4通过不依赖PKC的机制上调TNF-α mRNA，不增加TNF-α启动子活性，但显著增加TNF-α mRNA的稳定性。PMA与NiSO4共同刺激诱导的TNF-α mRNA显著高于单独使用每种试剂时。因此，依赖PKC的刺激物通过上调TNF-α启动子活性起作用，而镍则通过转录后调节起作用。我们的结果还证实，一些刺激物和刺激致敏剂可直接诱导角质形成细胞中的TNF-α，而无需中间的朗格汉斯细胞衍生信号。
