Tansirikongkol Anyarporn, Wickett R Randall, Visscher Marty O, Hoath Steven B
College of Pharmacy, Cincinnati Children's Hospital Research Foundation, University of Cincinnati, Cincinnati, Ohio 45267, USA.
Pediatr Res. 2007 Jul;62(1):49-53. doi: 10.1203/PDR.0b013e318067b442.
The fetal epidermal barrier undergoes rapid development during late gestation despite conditions injurious to the skin postnatally, i.e. prolonged exposure to water (urine) and noxious substances such as pancreatic chymotrypsin. Nevertheless, at birth, term newborns have a superb epidermal barrier. Concomitant with formation of the stratum corneum in utero, vernix caseosa forms a natural multifunctional cream separating the skin surface from the amniotic fluid with possible unique barrier properties. Therefore, we investigated the effect of native vernix, synthetic vernix, and Desitin on penetration of chymotrypsin, a proteolytic enzyme present in both developing epidermis and meconium. Alpha-chymotrypsin penetration through test materials was conducted in vitro using a modified Franz diffusion cell. The presence of alpha-chymotrypsin in vernix and a possible inhibitory effect of vernix on alpha-chymotrypsin activity were investigated. Vernix films significantly impeded chymotrypsin penetration compared with controls during 24-h exposure experiments. Alpha-chymotryptic activity in vernix was undetectable, and vernix showed no endogenous inhibition of such activity. Both synthetic vernix and Desitin significantly impeded alpha-chymotrypsin penetration compared with controls during 9-h exposure experiments. With respect to the developing epidermal barrier, these results are consistent with the hypothesis that vernix films retain endogenous (epidermal) chymotrypsin while preventing exposure to exogenous (pancreatic) chymotrypsin.
尽管胎儿出生后皮肤会受到诸如长时间接触水（尿液）和有害物质（如胰凝乳蛋白酶）等有害条件的影响，但胎儿的表皮屏障在妊娠晚期仍会快速发育。然而，足月新生儿出生时具有出色的表皮屏障。在子宫内角质层形成的同时，胎脂形成一种天然的多功能乳膏，将皮肤表面与羊水隔开，可能具有独特的屏障特性。因此，我们研究了天然胎脂、合成胎脂和德西丁（Desitin）对胰凝乳蛋白酶渗透的影响，胰凝乳蛋白酶是一种存在于发育中的表皮和胎粪中的蛋白水解酶。使用改良的弗兰兹扩散池在体外进行α-胰凝乳蛋白酶透过测试材料的实验。研究了胎脂中α-胰凝乳蛋白酶的存在情况以及胎脂对α-胰凝乳蛋白酶活性可能的抑制作用。在24小时暴露实验中，与对照组相比，胎脂膜显著阻碍了胰凝乳蛋白酶的渗透。在胎脂中未检测到α-胰凝乳蛋白酶活性，并且胎脂对这种活性没有内源性抑制作用。在9小时暴露实验中，与对照组相比，合成胎脂和德西丁都显著阻碍了α-胰凝乳蛋白酶的渗透。关于发育中的表皮屏障，这些结果与以下假设一致：胎脂膜保留内源性（表皮）胰凝乳蛋白酶，同时防止暴露于外源性（胰腺）胰凝乳蛋白酶。
