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| Author(s): |
Gabrielli Brianezi
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Botucatu. 2016-02-26. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Medicina. Botucatu |
| Defense date: | 2016-01-26 |
| Advisor: | Hélio Amante Miot; Mariângela Esther Alenca Marques |
| Abstract | |
The melasma pathogenesis, specially the role of keratinocytes and fibroblast in the disease development and maintenance are not completely understood. Dermal alterations such as basal membrane structural damage, pendulous melanocytes, solar elastosis, cellularity, vascular proliferation, in addition to the expression of inflammatory mediators, grow factors, epithelial melanocortin and sexual hormones receptors, suggest there is an interaction between the epidermal melanin unit and dermis in melasma physiopathology. The melanin skin pigmentation can be stimulated by different signaling pathways. UVR, dermal cytokines and epidermal inflammation are the most common models. These study aims to compare the nuclear morphology and chromatin texture in basal keratinocytes between melasma and adjacent skin, to investigate the activation of different pigmentation signaling pathways, and the dermal involvement, focusing on basal membrane zone and collagen. Therefore, facial skin biopsies (2 mm) from women were taken from melasma and normal skin (<2 cm apart) and processed for PAS and picrosirius red; immunofluorescence for p53, p38, IL-1α, αMSH, MC1R and COX2, immunohistochemistry for Melan-A counterstaining with PAS, and transmission electronic microscopy. Furthermore, primary fibroblast culture for real-timePCRarray and SA-β-gal staining. The nuclei of basal keratinocytes were evaluated as nuclear morphometry and chromatin texture; the fluorescence intensity was quantified in the epidermis and dermis; cytoplasm organelles and basal membrane zone were evaluated; in addition to dermal collagen and melanocytes density: total and pendulous. Regarding adjacent healthy skin, the melasma skin showed alterations in morphometric index and chromatin texture; there was greater epithelial expression of αMSH and MC1R, but without difference for p53, p38, IL1α and COX2; cytoplasm organelles and melanossomas in higher maturity were in greater number in keratinocytes and melanocytes; there were commoner damaged areas in basal membrane zone, presence of microvesicules adjacent to basal membrane; and higher number of pendulous melanocyte; dermal collagen was less structured. There were greater SA-β-gal staining and altered expression of COL4A1, IL6, ESR2, DKK3, CCL2, WIF1, WNT3A, HGF, IL1B, MMPs 1-7-9 genes in melasma fibroblasts.The alterations presented in keratinocytes, dermis and basal membrane zone suggest the melasma phenotype can result from alteration in entire epidermal melanin unit, not just hypertrophic melanocytes, the epidermal inflammatory pathways and p53 dependents do not show prominence, in addition to the possible role of the repair/ damage process identified at dermis and fibroblast senescence in the melasma pathogenesis. (AU) | |
| FAPESP's process: | 12/05004-1 - Morphofunctional assessment and genomic culture of melanocytes from patients with facial melasma |
| Grantee: | Gabrielli Brianezi |
| Support Opportunities: | Scholarships in Brazil - Doctorate |