Dissertation
Dissertation > Medicine, health > Medical research methods > Experimental medicine, medical experiments > Medical Laboratory Animal Science

Experimental Study on 420nm Intense Pulse Light in Animal Acne Model

Author XingYueZhen
Tutor YangRongZuo
School Third Military Medical University
Course Dermatology and Venereology
Keywords 420nm intense pulse light animal acne model TNF-α MMP-2
CLC R758.733
Type Master's thesis
Year 2010
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Background and ObjectiveAcne is a chronic hair follicle and sebaceous gland inflammation skin disease caused by many factors and its pathogenesis is complex. Inflammatory response is one of the main reasons for causing acne. While, as the primary factor leading acne inflammations, propionibacterium acne can induce local inflammatory response and organism immune response by secreting a variety of inflammation prompting factors. Researches show that as a high-energy specific spectrum blue light, 420nm intense pulsed light acting on endogenous porphyrins produced by metabolism of propionibacterium acne, releasing singlet oxygen, as well as effectively killing the propionibacterium acne. Also, 420nm intense pulsed light enables more oxygen entering into pores and inhibits the growth of propionibacterium acne through thermal effects. Meanwhile, in order to treat acne, light and heat effects of 420nm intense pulsed light promote the absorption and fadeaway of inflammation. But propionibacterium acne generates chronic inflammatory response in dermis of human. And the mechanism of 420nm intense pulsed light irradiation on dermis has not been explained yet.In this research, propionibacterium acne bacterial suspension was subcutaneously injected in the center of right inner auricles of SD rats to establish animal acne models. On the basis of the above-mentioned method, changes in appearance and pathology of local injected skin of acne model rats before and after treating by 420nm intense pulsed light were observed. This research focuses on exploring possible mechanisms of treating acne by 420nm intense pulsed light, which can be served as an important reference for further understanding the pathogenesis of acne and exploring new treatments.MethodIn order to establish acne models, propionibacterium acne bacterial suspension (50μl) was subcutaneously injected in the center of right inner auricles of SD rats. 7 days later, the model was checked out to be whether successful or not by observing changes of appearance, lesions and pathology of injected skin. Animal acne models were irradiated by 420nm intense pulsed light. Changes in appearance and pathology of local injected skin of acne model rats before and after treating by 420nm intense pulsed light were also observed. Immunohistochemical methods and Real-time PCR methods were used to determine the changes of TNF-α, MMP-2 and other cytokines in the skin of rats in each group. TNF-αand MMP-2 and other factors were determined by Immunohistochemistry and Real-time PCR.Result1. The ear inflammation acne model construction of the rat has been successfully verified by the performance of its skin appearance changes, skin lesions and pathologic changes.2. Before and after treating by 420nm intense pulsed light, rats of irradiation group were compared to those of model group. It was indicated that local inflammatory reaction obviously alleviated in irradiation group after treatment. Also, pathology of irradiation group showed that follicular keratosis layer significantly became thinner, inflammatory cells in dermis decreased and sebaceous glands became smaller.3. Immunohistochemistry showed that TNF-αand MMP-2 were positively expressed, which was influenced by irradiation of 420nm intense pulsed light. Real-time PCR showed TNF-αand MMP-2 was overexpressed in the model group, while the expression was reduced after irradiation (P <0.05).Conclusion1. 420nm intense pulse light has excellent therapeutic effects on acne;2. Through observing the changes of TNF-αand MMP-2 before and after treating by 420nm intense pulsed light, it is deduced that the cytokines TNF-αand MMP-2 are not only related with acne pathogenesis, but also play important roles in treating acne with 420nm intense pulsed light.

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