Alteration Of Elastic,Collagen Fibers And Expression Of AGEs In Cutaneous Photoaging

Object:To observe alteration of elastic and collagen fibers in the exposure and unexposure skin with aging;to detect advanced glycation endproducts(AGEs),the products of nonenzymic glycation,in the exposure and unexposure skin and investigate the contribution of nonenzymic glycation in the mechanism of cutaneous photoaging.Methods:Skin specimens from 30 patients(9-78y),were made into frozen sections,each of which was attached a sun exposure history questionnaire.We differentiated exposure specimen from unexposure specimen according to the location and the history of sun exposure.Each specimen was stained with Gomori method for elastic fibers,VG method for collagen fibers and SP immunohistochemistry method for AGEs.All samples were observed by microscope combined with image and statistics analysis.Results:1) Elastic fibers expressed hyperplasia with thickening,curling and irregular distribution in the exposure skin,while in the unexposure skin,there were decreased elastic fibers. There were significant difference between both(P< 0.05).2 ) Collagen fibers decreasd in both exposure and unexposure skin,and there were no significant difference(P>0.05).But the content of collagen fibers was fewer in the exposure skin than in the unexposure skin(P<0.05).3) There was expression of AGEs in both exposure and unexposure skin with middle or old age(P <0.05 ),but the content of AGEs was higher in the exposure skin than in the unexposure skin(P < 0.05).4 ) The accumulated location of AGEs:the stratum corneum,cytoplasma of keratinocyte,fibers and vessel walls in the dermis.Meanwhile,there was more expression of AGEs in the upper layer of dermis,where was maybe the location of degenerate elastic fibers.Conclusion:1)Ultraviolet radiation can induce denaturation of elastic fibers and decline of collagen fibers,and these cause the chlinical manifestation of cutaneous photoaging.2) nonenzymic glycation maybe contribute to the mechanism of cutaneous photoaging.UV can excite oxidative stress,which induce nonenzymic glycation and its products-AGEs can up-regulate the synthesis of elastic fibers and down-regulate the degradation of elastic fibers,but for collagen fibers,AGEs can down-regulate the synthesis and up-regulate the degradation.Besides,UV can excite oxidative stress which accelerate the process of cutaneous aging through photo sensibility of AGEs and reaction of AGEs-RAGE.