The hypo-pigmentation of human skin on the palms and the soles compared with other areas of the body has recently been reported to be due to mesenchymal-epithelial interactions via a fibroblast-derived factor, dickkopf 1, an inhibitor of the canonical Wnt signaling pathway. Recently, it has been reported that keratinocytes play a significant role in skin color determination by producing cytokines involved in melanogenesis. Thus, we hypothesized that the downregulated expression of keratinocyte- or fibroblast-derived melanogenic cytokines may also be responsible for the decreased function of palmoplantar (PP) melanocytes in addition to the suppressive effects of dickkopf 1 on melanogenic function in epidermal melanocytes. Immunohistochemistry revealed that the number of tyrosinase, S100alpha, c-KIT, endothelin B receptor (ETBR), SOX10, and microphthalmia-associated transcription factor (MITF) immuno-positive melanocytes is significantly reduced in PP epidermis. In contrast, dopa-histochemistry demonstrated no substantial reduction in melanocyte populations in PP epidermis. Real-time RT-PCR revealed that the expression of stem cell factor (SCF) and endothelin (ET)-1 mRNAs in PP skin was significantly downregulated. In parallel, immunohistochemistry revealed that SCF and ET-1 immuno-staining was markedly attenuated in PP skin. Western blotting revealed that the expression of SCF, c-KIT, and MITF-M proteins was significantly decreased in PP skin. These findings suggest the possibility that downregulation of ET-1/SCF/receptor linkages is also associated with the decreased function of melanocytes in PP skin.

中文翻译：

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色素沉着的掌plant皮肤中黑色素生成的旁分泌细胞因子的连接被下调。

最近有报道称，与其他部位相比，人的手掌和足底皮肤色素沉着是由于间充质-上皮相互作用，这是通过成纤维细胞衍生因子Dickkopf 1（一种典型的Wnt信号通路抑制剂） 。最近，已经报道，角质形成细胞通过产生涉及黑素生成的细胞因子在皮肤颜色确定中起重要作用。因此，我们假设角质形成细胞或成纤维细胞衍生的黑色素细胞因子的表达下调也可能是掌plant（PP）黑色素细胞功能下降的原因，此外还有dickkopf 1对表皮黑色素细胞中黑色素生成功能的抑制作用。免疫组化显示酪氨酸酶，S100alpha，c-KIT，内皮素B受体（ETBR），SOX10，PP表皮中的微眼科相关转录因子（MITF）免疫阳性黑素细胞显着减少。相比之下，多巴组织化学显示PP表皮中黑素细胞数量没有实质性减少。实时RT-PCR显示，PP皮肤中干细胞因子（SCF）和内皮素（ET）-1 mRNA的表达显着下调。同时，免疫组织化学显示PP皮肤中SCF和ET-1的免疫染色明显减弱。Western印迹显示PP皮肤中SCF，c-KIT和MITF-M蛋白的表达显着降低。这些发现表明，ET-1 / SCF /受体连接的下调也可能与PP皮肤黑素细胞功能下降有关。