Properties of epidermal proteins against microorganisms

皮肤的生物功能之一是保护活体免受微生物、紫外线等的伤害。角质层的细胞膜是皮肤的外层，是由几种蛋白质组成的厚厚的细胞被膜，称为角化被膜。因此，这是一个物理障碍。另一方面，皮肤中一定存在一些具有抗微生物活性的蛋白质。我们研究了胱抑素α和杀菌/通透性增加蛋白在皮肤中的性质。半胱氨酸蛋白酶抑制剂α是一种半胱氨酸蛋白酶抑制剂，属于半胱氨酸蛋白酶超家族1，存在于角质层颗粒和角化被膜中。角化的包膜也抑制半胱氨酸蛋白酶的活性。半胱氨酸蛋白酶α抑制脊髓灰质炎病毒和金黄色葡萄球菌V8产生的半胱氨酸蛋白酶活性，以及病毒和细菌的生长。胱抑素α将起到阻挡皮肤表面微生物的作用。BPI样蛋白定位于人和大鼠皮肤内根鞘细胞的细胞质中。并抑制内毒素活性。内根鞘和汗腺中都有大量细菌存在。因此，BPI样蛋白可以抑制皮肤中产生内毒素的革兰氏阴性细菌的生长。

One of the biological functions of skin is the protection of living body against microorganisms, ultraviolet rays and so on. Cell membrane of the stratum corneum, the outside layer of the skin, is thick cell envelope composed several proteins and called cornified envelope. So it is a physical barrier. On the other hand, there must be some proteins which have anti-microorganism activity in the skin. We have investigated the properties of cystatin α and bactericidal/permeability-increasing protein (BPI)-like protein in skin. Cystatin α is a cysteine protease inhibitor, belonging to cystatin super family 1, in keratohyalin granules and the cornified envelope. The cornified envelope also inhibited the activity of cysteine protease. Cystatin α inhibited activities of cysteine proteases produced by poliovirus and Staphylococcus aureus V8, and growth of the virus and bacteria. Cystatin α would play a role as a barrier against microorganisms on the skin surface. BPI-like protein located in the cytoplasm of the inner root sheath cells in human and rat skin. And it inhibited endotoxin activity. A lot of bacteria locate in the inner root sheath as well as in sweat gland. Therefore, BPI-like protein could inhibit growth Gram-negative bacteria that produce endotoxin in the skin.