Poster presentation, P93

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Alteration of epidermis junctions in human Solar Lentigo

SPEAKER E. Noblesse #whois submiter ?
AUTHOR(s) E. Noblesse, P. Schaeffer, R. Kurfurst, C.Nizard, S. Schnebert, E. Perrier

Solar lentigo is a common component of photoaged skin. It is characterized by hyperpigmented aging spot which appear in chronically irradiated skin mostly after age 50. Previous studies showed that keratinocytes junctions contribute to the maintenance of epithelial barrier functions, proliferation/differentiation equilibrium and epithelial cell polarity, process which are linked with the natural process of melanin evacuation. METHODS: A comparison between lesional, perilesional and normal skin from biopsies of 15 female patients was performed using histology, transmission electron microscopy and immunofluorescence of DSG1, ZO-1 and E.cadherin proteins. The ZO-1, E.cadherin and DSG1 expression are evaluated by immunostaining and image analysis to explore the structural aspect of tight junctions (TJs), adherens junctions and desmosomes. RESULTS: Ultrastructure study shows important modifications of lesional skin in comparison with adjacent normal skin: a hyperpigmented basal layer with melanin accumulation, an elongation of the epidermis rete ridges and a disorganization and disruption of dermal epidermal junction associated with an increases of keratinocyte basal microvillosity The study of keratinocytes junctions ZO-1, E.cadherin and DSG1 expression shows a significant decrease in the epidermis granular layers, gradually from perilesional (-40%, -44% and -20% respectively) to lesional area (-68%, -75%, -68% respectively) in comparison with the adjacent normal skin. Structural analysis of TJs network shows that in the non lesional epidermis, ZO-1 forms a continuous network at the stratum granulosum. When it progresses to the spot area, this network is gradually disorganised in perilesional skin (-28%) and tended to fully disappear in some patients in lesional skin (-51%). CONCLUSION: In a polarized system such as normal human skin, disruption of the epidermis junctions affects normal turn-over of the living epidermis. Necessary for the normal process of keratinocytes differentiation, cell movements are disrupted and lead to a decrease in evacuation of the melanin overproduction which is associated to lentigo formation. Taking together, these results open a new strategy to reduce and prevent solar lentigo in human skin.



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