白癜风皮损表皮钙离子梯度与角质层板层脂膜超微结构观察

Ultrastructural changes of epidermal calcium gradient and lipid lameUar membrane in depigmented skin lesions of vitiligo patients

目的探讨白癜风皮损黑素脱失对表皮钙离子分布和角质层板层脂膜超微结构的影响。方法2014年8月至2015年2月于武汉大学人民医院皮肤科门诊招募稳定期寻常型白癜风患者和健康对照各5例。四氧化钌（RuO4）电子特染结合透射电子显微镜技术观察皮肤标本角质层板层脂膜的超微结构；用钙离子化学捕捉技术结合透射电镜观察表皮钙沉淀颗粒的数量及分布。结果健康对照皮肤角质层细胞问隙可见排列规整、电子致密带和电子透明带重复交替排列的板层结构；白癜风皮损角质层细胞间隙扩大，板层脂膜分离断裂，出现空泡，空泡内填充有无形电子致密物。健康对照皮肤的颗粒层可见到粗大密集的钙沉淀颗粒，基底层细胞间可见细小的钙沉淀颗粒与Ⅳ期黑素小体；而白癜风皮损的颗粒层钙沉淀颗粒大小和数目较正常对照明显减少，基底层几乎完全缺乏黑素小体。结论白癜风皮损同时存在表皮钙离子梯度消失和板层脂膜结构紊乱，提示表皮黑素可能与表皮钙梯度形成与渗透性屏障结构完整性相关。

Objective To investigate the effects of melanin disappearance in vitiliginous skin on the ultrastructure of epidermal calcium distribution and the stratum corueum （ SC ） lipid lamellar membranes. Methods Five outpatients with stable vitiligo vulgaris and 5 healthy controls were recruited from August 2014 to February 2015 at Department of Dermatology, Renmin Hospital of Wuhan University. The uhrastruetural changes of lipid lamellar membranes of the skin were assessed using transmission electron microscopy （TEM） technique in combination with ruthenium tetroxide （RuQ） staining. The concentration and distribution of calcium precipitates in the epidermis were studied using calcium ion-capture cytoehemistry combined with TEM. Results The multilayered lipid lamellae existed within the intercellular space of the normal SC with a characteristic alternating electron-dense and electron-lucent pattern. Expanded intercellular space, fragmentation and lamellar separation were observed in the depigmented skin lesions from vitiligo patients, the bulbous regions of lipid lamellae were filled with electron-dense amorphous materials. Large clumps of calcium precipitates were visualized in the stratum granulosum （SG） of normal skin, fine calcium precipitates and stage IV melanosomes were noted within the normal stratum basale （SB）. In depigmented skin lesions of vitiligo, both the size and number of calcium precipitates in the SG were dramatically decreased. Melanosome was barely seen in the vitiligo SB. Conclusion Disrupted ultrastructure of SC lamellar membranes and disappearance of calcium gradient co-exist in the skin lesion of vitiligo, indicating that melanin in epidermis may play a role in formation of epidermal calcium gradient and maintenance of structural integrity of permeability barrier.