皮肤干燥是通透屏障功能受损的表现吗?

Does dry skin indicate defective epidermal permeability barrier?

有学者认为,皮肤干燥是表皮通透屏障功能受损的表现,但目前尚没有足够的证据证明这一观点。实际上,皮肤干燥是角质层含水量降低的表现。角质层含水量主要由角质层天然保湿因子的量决定,而表皮通透屏障功能则主要由角质层脂质的质和量以及结构蛋白决定。如果皮肤干燥是由表皮通透屏障功能降低所致,那么,角质层含水量应当与透皮失水率呈负相关性。但是研究表明,无论是正常人皮肤、鱼鳞病皮损或皮脂腺缺乏的小鼠皮肤,角质层含水量与透皮失水率均无负相关性。相反,有研究显示,人角质层含水量与透皮失水率呈正相关性。因此,皮肤干燥似乎不是表皮通透屏障功能受损的表现。

It has been speculated that dry skin results from dysfunction of epidermal permeability barrier.But so far,there is no sufficient evidence to support this speculation.In fact,dry skin indicates low levels of stratum corneum hydration.Stratum corneum hydration levels are primarily determined by the content of natural moisturizers in the skin,while epidermal permeability barrier is mainly regulated by intercellular lipids and structural proteins in the stratum corneum.If dry skin is due to a defective permeability barrier,stratum corneum hydration levels should be inversely correlated with transepidermal water loss(TEWL),an indicator of epidermal permeability barrier function.But no negative correlation has been demonstrated between stratum corneum hydration levels and TEWL in either normal human skin,ichthyoses lesions of patients,or sebaceous gland-deficient mice in a number of studies.In contrast,a positive correlation between stratum corneum hydration levels and TEWL was observed in normal human skin.Taken together,a line of evidence suggests that dry skin unlikely indicates epidermal permeability barrier dysfunction.