ABSTRACT
Objective: To detect the expression of MMP-13 in the skin of mice treated by near-infrared (IRA) and ultraviolet (UV) so as to observe their effects on skin photoaging and their interrelation and explore molecular mechanisms in IRA-induced skin photoaging. Methods: Male ICR mice were randomly divided into five groups: control group (without ray exposure), IRA group, UV group, IRA/UV group, and UV/IRA group. The mice in the latter four groups had their dorsal skin exposed to different radiated ray respectively. The levels of MMP-13 protein and mRNA in the exposed skin were detected by HE, immunohistochemical method, Western blot and real-time PCR. Results: Both skin lesions by visual inspection and H&E staining results showed that mice in the other four groups had skin photoaging in the exposed skin area compared with the control group. The levels of MMP-13 protein and mRNA in the exposed skin in IRA/UV and UV/IRA groups were significantly higher than those in the control mice (P<0.05). In addition, mice in IRA/UV group showed higher levels of MMP-13 protein and mRNA than those in UV/IRA group (P<0.05). Conclusion: ① IRA causes skin photoaging in mice. ② UV and IRA interact with each other, up-regulate the expression of MMP-13, and promote each other in the process of photoaging. ③ The effects of IRA and UV in combination on skin photoaging are closely related to order of exposure. Taken together, avoiding IRA exposure and the expression of MMP-13 play an important role in preventing skin wrinkle formation and treatment of photoaging in mice.
ABSTRACT
<p><b>OBJECTIVE</b>To observe the effect of solar infrared ray (IR) radiation on the expressions of c-Jun and collagens I and III in cultured human skin fibroblasts (HSFs) and explore the molecular mechanism by which IR radiation causes aging of the skin.</p><p><b>METHODS</b>Primarily cultured HSFs exposed to IR radiation were examined for changes of the cell viability with MTT assay. The mRNA and protein expressions of c-Jun and collagens I and III was detected with real-time quantitative PCR and immunocytochemistry.</p><p><b>RESULTS</b>MTT assay showed that IR irradiation caused inhibition of cell proliferation compared with the control cells. The mRNA and protein expression of collagen I was decreased significantly by IR irradiation with the increase of the irradiation dose (P<0.01). HSFs irradiated by IR for 12 h showed a dose-dependent reduction of the expression of collagen type III mRNA and protein (P<0.05, P<0.01), but the expression increased dose-dependently in response to IR exposure for 24 h (P<0.05 or 0.01). IR irradiation enhanced the mRNA and protein expression of c-Jun in a dose-dependence manner (P<0.05 or 0.01).</p><p><b>CONCLUSIONS</b>IR irradiation can increase the expression of c-Jun, inhibit the expression of collagen I, and cause disturbance in collagen III expression in human skin fibroblasts, which may be one of the mechanism of IR radiation to initiate and promote skin photoaging.</p>