老年皮肤生理特征及其临床意义

Biophysical Characteristics of the Aged Skin and Its Clinical Implication

老年皮肤生理特征的改变包括形态学的变化:表皮变薄、表皮更替时间延长、真表皮交界变平,真表皮间角质形成细胞黏附下降,黑素细胞的分布改变、朗格汉斯细胞数量也随之减少,真皮胶原合成降低、弹力纤维降解。更重要的是生理功能也发生改变,主要是表皮通透性屏障功能的变化,包括表皮通透性屏障功能恢复减慢,透皮失水(transepidermal water loss,TEWL)降低,角质层含水量降低,及表皮pH增高。因此,导致了老年皮肤科门诊临床最常见的干燥症与瘙痒的发生,且这些改变均能导致持续轻微的炎症继而可能导致系统炎症及疾病的发生,具有重要临床意义。

In the aged skin,biological changes include decreased epidermal thickness,shortened epidermal turnover time and reduced cohesion between the dermis and the epidermis, in addition to the changes in melanocyte distribution and reduced number of Langerhans cells in the epidermis.Alterations in the dermis include decreased collagen synthesis and degradation of elastic fibers.Other important changes are epidermal biophysical properties in the aged skin.The recovery of permeability barrier is slower while baseline transepidermal water loss (TEWL) rates and stratum corneum levels are lower in the aged skin in comparison to the young skin.In contrast,skin surface pH is elevated in the aged skin.These changes in cutaneous structure and function make the aged skin more vulnerable to insults,leading to the development of certain aging associated dermatoses such as xerosis,pruritus and infections,which are commonly seen in dermatological clinics.Moreover,changes in epidermal function alone can lead to cutaneous inflammation,and possible systemic inflammation, resulting in the development of cutaneous and systemic diseases.In this review,agingassociated changes in cutaneous biophysical properties and their clinical significance are summarized.