Ozawa Toshiyuki, Sugawara Koji, Tsuruta Daisuke
Department of Dermatology, Osaka City University Graduate School of Medicine, Osaka, Japan.
Exp Dermatol. 2014 Jun;23(6):393-4. doi: 10.1111/exd.12385.
It was previously thought that the skin barrier is composed singly by the stratum corneum. However, this concept was overturned by the report of Tsukita's group in 2002. They convinced us that tight junctions exist in the stratum granulosum of the epidermis, with the constituent proteins being occludin, claudin-1 and claudin-4. However, more than 30 years before this, Hashimoto et al. described the possible existence of tight junctions in the epidermis in 'Intercellular spaces of the human epidermis as demonstrated with lanthanum' in 1971. Dr. Hashimoto observed lanthanum nitrate-injected human skin by electron microscopy. He discovered that the injected lanthanum penetrated the intercellular spaces of the basal and spinous layers of the epidermis and then moved towards the skin surface until penetration was halted in the granular cell layer near the stratum corneum. He described the cell-to-cell adhesion structures that blocked the movement of lanthanum as 'truly tight junctions'. Thus, this was the first description of the existence of tight junctions in the epidermis. However, the presence of these structures was denied by others and was forgotten. Thanks to the discovery of claudin, the existence of tight junctions between epidermal keratinocytes was finally confirmed. It is interesting that Hashimoto's finding was eventually proved to be correct three decades later as a result of progress in molecular biology. This article encourages us to recognize the importance of careful observation in the molecular biology era.
以前人们认为皮肤屏障仅由角质层构成。然而，2002年筑田小组的报告推翻了这一概念。他们让我们相信，在表皮颗粒层中存在紧密连接，其组成蛋白为闭合蛋白、Claudin-1和Claudin-4。然而，在此之前30多年，桥本等人在1971年发表的《用镧显示的人类表皮细胞间空间》中描述了表皮中可能存在紧密连接。桥本博士通过电子显微镜观察了注射硝酸镧的人体皮肤。他发现注入的镧穿透了表皮基底层和棘层的细胞间空间，然后向皮肤表面移动，直到在角质层附近的颗粒细胞层中停止穿透。他将阻止镧移动的细胞间粘附结构描述为“真正的紧密连接”。因此，这是对表皮中存在紧密连接的首次描述。然而，这些结构的存在被其他人否定并被遗忘了。由于Claudin的发现，表皮角质形成细胞之间紧密连接的存在最终得到证实。有趣的是，由于分子生物学的进展，桥本的发现最终在三十年后被证明是正确的。本文鼓励我们认识到在分子生物学时代仔细观察的重要性。
