Estudo histomorfométrico, ultraestrutural e da expressão de Wnt1, WIF-1 e ASIP na pele com melasma em comparação com a pele sã perilesional e retroauricular
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2017-07-20
Autores
Lemos, Ana Cláudia Cavalcante Espósito [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O melasma é hipermelanose crônica e adquirida decorrente de um complexo processo que envolve hipertrofia melanocítica e disfunção melanogênica. Acomete preferencialmente o sexo feminino e as lesões ocorrem nas áreas fotoexpostas, especialmente a face. Sua patogênese não é bem compreendida e os estudos clássicos avaliam apenas pele acometida e perilesional, mas pouco se sabe do comportamento da pele fotoprotegida, submetida aos mesmos fatores sistêmicos e genéticos. Neste estudo, objetivamos avaliar características histológicas, vias epidérmicas que influem na melanogênese (Wnt e ASIP) e características ultraestruturais da pele com melasma em comparação com a pele sã adjacente e retroauricular. Para a execução deste estudo transversal com controle intra-sujeito, foram coletadas três biópsias cutâneas (punch 3 mm) de onze mulheres com melasma facial. As áreas de coleta foram a pele com melasma, pele sã adjacente (distando no máximo 2 cm do limite da lesão) e pele retroauricular ipsilateral. Os fragmentos provenientes de dez participantes foram corados por hematoxilina-eosina, ácido periódico de Schiff, Fontana-Masson, picrosirius red, azul de toluidina e Verhöff; imunomarcados para CD34 e submetidos à imunofluorescência direta (IFD) de dupla marcação para proteínas Wnt1, WIF-1 e ASIP. Já os três fragmentos de uma das participantes foram processados para Microscopia Eletrônica de Transmissão (MET). Os dados obtidos foram comparados entre as topografias por modelo linear generalizado de efeitos mistos. As participantes eram fototipo III ou IV de Fitzpatrick, com idade média (desvio-padrão) de 42,9 (8,9) anos e apresentavam lesões há 16,7 (7,9) anos. Houve adelgaçamento da camada córnea na pele com melasma e na pele adjacente. Na pele com melasma houve maior compactação da córnea, maior pigmentação melânica epidérmica, maior heterogeneidade do colágeno, elastose solar, maior número de mastócitos, falhas da integridade da zona da membrana basal, melanócitos em pêndulo, bem como maior celularidade e vasos na derme superficial. IFD evidenciou maior intensidade de marcação de Wnt1 na pele com melasma em relação à pele adjacente e maior intensidade na pele retroauricular em relação à pele sã adjacente. Não houve diferença estatística significativa na intensidade de marcação de WIF-1 e ASIP entre as topografias. À MET, houve maior dano estrutural na lâmina lúcida no melasma, bem como maior número de melanossomas maduros e organelas citoplasmáticas nos melanócitos e queratinócitos basais. Tais resultados evidenciam que a pele com melasma apresenta, além da hipertrofia melanocítica, alterações na barreira epidérmica, na derme superior, zona de membrana basal e maior ativação da via Wnt, que diferem da pele fotoexposta adjacente e da retroauricular, configurando um fenótipo individualizado e não somente uma extensão do fotoenvelhecimento ou do envelhecimento intrínseco.
Melasma is a chronic and acquired hypermelanosis resulting from a complex process which involves melanocytic hypertrophy and melanogenic dysfunction. Melasma mainly affects females and lesions occur in the photoexposed areas, especially the face. Its pathogenesis is not well understood, and classical studies evaluate only the affected and perilesional skin, but little is known about the behavior of the non-sun-exposed skin, subjected to the same systemic and genetic factors. In this study, we aimed to evaluate histological features, epidermal pathways that influence melanogenesis (Wnt and ASIP) and ultrastructural characteristics of the skin with melasma in comparison to healthy adjacent and retroauricular skin. For the execution of this cross-sectional study with intrasubject control, three skin biopsies (punch 3 mm) were collected from eleven women with facial melasma. The areas of collection were the skin with melasma, adjacent healthy skin and retroauricular skin. Fragments from ten participants were stained with hematoxylin-eosin, periodic acid from Schiff, Fontana-Masson, picrosirius red, toluidine blue and Verhöff; immunomarked for CD34 and subjected to double-labeled direct immunofluorescence (DIF) for Wnt1, WIF-1 and ASIP proteins. The three fragments of one of the participants were processed for Transmission Electron Microscopy (TEM). The data obtained were compared between topographies by generalized linear model of mixed effects. Participants were Fitzpatrick's phototype III or IV; the mean age (standard deviation) was 42.9 (8.9) years and they had lesions for 16.7 (7.9) years. There was thinning of the corneal layer on the skin with melasma and adjacent skin. In the skin with melasma, there was more corneal compaction, greater epidermal melanic pigmentation, greater collagen heterogeneity, solar elastosis, more mast cells, defects of the basement membrane area, pendulum melanocytes, as well as greater cellularity and vessels in the superficial dermis. DIF showed a greater intensity of Wnt1 marking in the skin with melasma in relation to the adjacent skin, and greater intensity in the retroauricular skin in relation to the adjacent healthy skin. There was no significant statistical difference in the intensity of WIF-1 and ASIP marking between topographies. At TEM, there was more structural damage to the lamina lucida in melasma, as well as more mature melanosomes and cytoplasmic organelles in melanocytes and basal keratinocytes. These results show that melasma skin presents, in addition to melanocytic hypertrophy, alterations in the epidermal barrier, upper dermis, basement membrane zone and greater activation of the Wnt pathway, which differ from adjacent and retroauricular photoexposed skin, forming an individualized phenotype and not only an extension of photoaging or intrinsic aging.
Melasma is a chronic and acquired hypermelanosis resulting from a complex process which involves melanocytic hypertrophy and melanogenic dysfunction. Melasma mainly affects females and lesions occur in the photoexposed areas, especially the face. Its pathogenesis is not well understood, and classical studies evaluate only the affected and perilesional skin, but little is known about the behavior of the non-sun-exposed skin, subjected to the same systemic and genetic factors. In this study, we aimed to evaluate histological features, epidermal pathways that influence melanogenesis (Wnt and ASIP) and ultrastructural characteristics of the skin with melasma in comparison to healthy adjacent and retroauricular skin. For the execution of this cross-sectional study with intrasubject control, three skin biopsies (punch 3 mm) were collected from eleven women with facial melasma. The areas of collection were the skin with melasma, adjacent healthy skin and retroauricular skin. Fragments from ten participants were stained with hematoxylin-eosin, periodic acid from Schiff, Fontana-Masson, picrosirius red, toluidine blue and Verhöff; immunomarked for CD34 and subjected to double-labeled direct immunofluorescence (DIF) for Wnt1, WIF-1 and ASIP proteins. The three fragments of one of the participants were processed for Transmission Electron Microscopy (TEM). The data obtained were compared between topographies by generalized linear model of mixed effects. Participants were Fitzpatrick's phototype III or IV; the mean age (standard deviation) was 42.9 (8.9) years and they had lesions for 16.7 (7.9) years. There was thinning of the corneal layer on the skin with melasma and adjacent skin. In the skin with melasma, there was more corneal compaction, greater epidermal melanic pigmentation, greater collagen heterogeneity, solar elastosis, more mast cells, defects of the basement membrane area, pendulum melanocytes, as well as greater cellularity and vessels in the superficial dermis. DIF showed a greater intensity of Wnt1 marking in the skin with melasma in relation to the adjacent skin, and greater intensity in the retroauricular skin in relation to the adjacent healthy skin. There was no significant statistical difference in the intensity of WIF-1 and ASIP marking between topographies. At TEM, there was more structural damage to the lamina lucida in melasma, as well as more mature melanosomes and cytoplasmic organelles in melanocytes and basal keratinocytes. These results show that melasma skin presents, in addition to melanocytic hypertrophy, alterations in the epidermal barrier, upper dermis, basement membrane zone and greater activation of the Wnt pathway, which differ from adjacent and retroauricular photoexposed skin, forming an individualized phenotype and not only an extension of photoaging or intrinsic aging.
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Palavras-chave
Melasma, Microscopia eletrônica, Histologia, Luz solar, Raios ultravioletas, Colágeno, Melanose, Melanócitos, Melanossomas, Técnica direta de fluorescência para anticorpo, Imunofluorescência, Microscopy, Electron, Histology, Sunlight, Ultraviolet rays, Collagen, Melanosis, Melanocytes, Melanosomes, Fluorescent antibody technique, Direct