Kim Mi-Sun, Kim Yeon Kyung, Cho Kwang Hyun, Chung Jin Ho
Department of Dermatology, Seoul National University College of Medicine, Clinical Research Institute, Seoul National University Hospital, Institute of Dermatological Science, Medical Research Center, Chongno-gu, Republic of Korea.
Mech Ageing Dev. 2006 Dec;127(12):875-82. doi: 10.1016/j.mad.2006.09.007. Epub 2006 Oct 25.
Human skin is daily exposed to infrared (IR) radiation from natural sunlight. However, the effects of IR irradiation on collagen metabolism have not been investigated in human skin in vivo. Here, we examined whether single or repeated (three times a week for 4 weeks) exposure to IR irradiation changes the expressions of type I procollagen and interstitial collagenase (MMP-1). By using immunostaining, Western blotting, and semi-quantitative RT-PCR, we analyzed the protein and mRNA levels of type I procollagen and MMP-1 in young buttock skin. A single dose of IR to human skin increased the expression of type I procollagen within 24h, but did not change the expression of MMP-1. On the other hand, multiple IR doses reduced the expression of type I procollagen and increased the expression of MMP-1. We also found that TGF-betas may mediate type I procollagen synthesis in IR-irradiated human skin. Our results demonstrate that the regulations of the expressions of type I procollagen and MMP-1 differ in acute and chronically IR-irradiated skin. In particular, decreased collagen levels and increased MMP-1 levels in chronic IR-irradiated skin may be associated with connective tissue damage. Thus, we suggest that repeated exposure to IR irradiation might induce premature skin aging (photoaging) in human skin in vivo.
人体皮肤每天都会暴露于自然阳光中的红外线（IR）辐射下。然而，红外线照射对人体皮肤胶原蛋白代谢的影响尚未在体内进行研究。在此，我们研究了单次或重复（每周三次，共4周）红外线照射是否会改变I型前胶原和间质胶原酶（MMP-1）的表达。通过免疫染色、蛋白质印迹法和半定量逆转录-聚合酶链反应，我们分析了年轻臀部皮肤中I型前胶原和MMP-1的蛋白质和mRNA水平。单次红外线照射人体皮肤在24小时内增加了I型前胶原的表达，但未改变MMP-1的表达。另一方面，多次红外线照射降低了I型前胶原的表达并增加了MMP-1的表达。我们还发现，转化生长因子-β可能介导红外线照射的人体皮肤中I型前胶原的合成。我们的结果表明，I型前胶原和MMP-1表达的调节在急性和慢性红外线照射的皮肤中有所不同。特别是，慢性红外线照射皮肤中胶原蛋白水平降低和MMP-1水平升高可能与结缔组织损伤有关。因此，我们认为重复暴露于红外线照射可能会在体内诱导人体皮肤过早衰老（光老化）。
