| Objective: To study the effect of collagen synthesis and decomposition on the structure of mouse dorsal skin by the irradiation of 810 nm semiconductor laser in vivo, and reveals the mechanism of collagen renewal by S100a8- IKBa- nuclear transcription factor kappaB(NF-?B) signaling pathway and TGF-? / Smad signaling pathway in laser-induced skin.To provide a molecular theoretical basis for the treatment of skin aging by 810 nm semiconductor laser.Materials and Methods: 12 ICR mice were used as experimental subjects were randomly divided into two cages, All the back of mice were divided into six areas Separately after shaving, the left for the irradiated group were blank control groups, corresponding to the right(from head to tail) respectively was 20 J / cm2 laser irradiation group, 40 J / cm2 laser irradiation group and 60 J / cm2 laser irradiation group. One cage of mice was randomly selected treated by 810 nm semiconductor laser irradiation at 1,3,5,7 days, Treatments were performed four times at an interval of 2 days, To observe the skin appearance and living status by the other cage mice at 30 days after irradiation, Dermal thickness was measured by an independent histologist who collected three representative measurements per tissue section using Image-Pro Plus 6.0 software. The mean value of six sections was calculated In addition to the microscope magnification used as the final dermal thickness, The unit is ?m. Representative histological changes by Hematoxylin and eosin stain and detected type I collagen by use of immunohistochemical techniques, then observe the changes of morphology at group of 40 J / cm2 laser irradiation by scanning electron microscope electron microscope. Another cage mouse skin samples taken for detective pathology and molecular biology at 0, 1, 3,7,30 days after irradiation, to observe histological changes in the structure of the skin at various time points by HE stain, and detected the expression of procola1, MMP-2, IL-6, IL-8, TNF-a, TGF-?, IL-1?, TIMP-1, IKBa and S100a8, S100a9 by RT-PCR and western blot.Results: The mice were observed at 30 days after irradiation, the area of skin by irradiation can be find more luster, delicate and flexible than in the control area of skin, and the mouse as usual,there are no damage was find at 20 J / cm2 irradiation area and 40 J / cm2 irradiation area of skin.the irradiated area has inflammation after 12 h from the result of histology, a large part of the nucleus stained, the elastic fiber degeneration was find in 60 J / cm2 irradiation zone,and acute edema be visible. The inflammation was significantly reduced in irradiated area after 24 h from the result of histology, and elastic fiber degeneration obviously and part of the new collagen was found.type I collagen found significantly increased in 40 J / cm2 irradiation zone at 30 days after irradiation by the result of immunological, taking a step forward in the scanning electron microscope tips 40 J / cm2 irradiation has area neat and orderly collagen, collagen bundles can be seen intact. The result of dermal thickness measurements showed each laser irradiation group compared with their corresponding control group were statistically significant(P <0.05 n=36) and 40 J / cm2 irradiation group compared with other irradiated group also found statistically significant differences(F = 10.407, P <0.01);The results of RT-PCR; It has detect upregulated of IL-1?at 60 J / cm2 laser irradiation zone after 12 h irradiation, while s100a8 energy irradiation in each region have increased expression; ? procollagen expression at 40 J / cm2 laser irradiation area and 60 J / cm2 laser irradiation zone were upregulated after 24 h irradiation; Inflammatory cytokines TNF-?, IL-8, IL-6 in the irradiated group were seen to up regulated compared with the control group after irradiation, Especially IL-8, IL-6 increased more pronounced at higher energy group, It can be seen IL-1? in 60 J / cm2 laser irradiation area downregulated at 7 day,and has poor upregulation in 20 J / cm2 laser irradiation area and 40 J / cm2 laser irradiation area;? procollagen can be seen a significant increase in the irradiated area and control area, This phenomenon became more obvious at 30 days after irradiationThe results of Western blot; The results of expression of procollagen type I and expression of MMP-2 also show upregulated at 40 J / cm2 laser irradiation area and 60 J / cm2 laser irradiation area at 12 h after irradiation, while the expression of TIMP-1 did not change significantly; IKBa has visible upregulated in the irradiated group; Western blot results also show that antibody of I procollagen a1 and a2 at 40 J / cm2 laser irradiation area more significant expression at 24 h after irradiation, while no significant expression in other irradiated group.Conclusion : If choice the appropriate energy and does can not cause skin damage by 10 nm semiconductor laser, in our experiments 40 J / cm2 light group is the most obviously effect on collagen and no damage is found, therefore 810 nm semiconductor laser is effective way for the treatment of skin aging; and in the long term results revels 810 nm semiconductor laser irradiation can effectively increase the thickness of the dorsal skin of mice, and has dense arrangement of collagen fibers, dyed darker skin structure has been significantly improved. From the molecular mechanisms, 810 nm semiconductor laser irradiation can start dermal inflammation, activate IL-6, IL-8, TNF-a, TIL-1?, S100a8, S100a9 other inflammatory factors, and then activate NF-?B, TGF-? / Smad signaling pathways and RAGE, and by outside MMP2 aging degradation of extracellular matrix proteins, they work together to promote the synthesis of collagen in the skin and updates. Therefore, 810 nm semiconductor laser can act directly on the dermis and stimulate self-renewal dermis play the role of anti-aging, have good prospects in terms of light rejuvenation. |
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