Starcher B, Pierce R, Hinek A
Department of Biochemistry, The University of Texas Health Center, Tyler 75710, USA.
J Invest Dermatol. 1999 Apr;112(4):450-5. doi: 10.1046/j.1523-1747.1999.00553.x.
UVB irradiation stimulates the synthesis of elastin in the skin of humans and experimental animals. In this study we localized the site and the cells that are responsible for the synthesis of murine dermal elastic fibers. SKH-1 hairless mice were irradiated with UVB and the skin removed for light microscopy, electron microscopy, in situ hybridization, immunohistochemistry, and biochemical studies. In response to chronic low doses of UVB there was an initial moderate increase in tropoelastin mRNA in the papillary dermis. By contrast, there was a continuous marked elevation of collagen alpha1(I) message localizing to sites of inflammatory cell influx throughout the upper and lower dermis. After 25 wk of UV irradiation there was a 2-fold increase in skin elastin, yet total collagen remained unchanged. Serial desmosine analysis from en face sections indicated the increase in elastin content was due to dermal elastic fibers, an increase in the size and number of the dermal cysts, and an increase in subpanniculus elastic fibers. Elastin stains of en face sections suggested that the elastic fibers in the upper dermis were exclusively derived from cells lining the epithelial root sheath and sebaceous glands. In response to UV irradiation, the elastic fibers increased in number and size, wrapping around these structures and aligning in both directions as long fibers parallel to the body axis. Electron micrographs indicated that modified epithelial cells in close proximity to the flattened epithelial cells that encircled the root sheath and sebaceous glands were the source of the elastic fibers.
紫外线B（UVB）照射可刺激人类和实验动物皮肤中弹性蛋白的合成。在本研究中，我们定位了负责合成小鼠真皮弹性纤维的部位和细胞。用UVB照射SKH-1无毛小鼠，然后取下皮肤进行光学显微镜、电子显微镜、原位杂交、免疫组织化学和生化研究。对慢性低剂量UVB的反应是，乳头层真皮中原弹性蛋白mRNA最初适度增加。相比之下，整个真皮上下层中定位在炎症细胞流入部位的胶原蛋白α1（I）信息持续显著升高。紫外线照射25周后，皮肤弹性蛋白增加了两倍，但总胶原蛋白保持不变。从正面切片进行的系列锁链素分析表明，弹性蛋白含量的增加归因于真皮弹性纤维、真皮囊肿大小和数量的增加以及皮下弹性纤维的增加。正面切片的弹性蛋白染色表明，真皮上层的弹性纤维完全来自上皮根鞘和皮脂腺内衬的细胞。对紫外线照射的反应是，弹性纤维数量和大小增加，围绕这些结构并沿与身体轴平行的长纤维在两个方向排列。电子显微镜照片表明，与环绕根鞘和皮脂腺的扁平上皮细胞紧密相邻的修饰上皮细胞是弹性纤维的来源。
