Comparação entre histologia e espectroscopia de fluorescência para avaliação de atrofia cutânea induzida por glicocorticóide em ratos

The gold standard for evaluating skin atrophy is the histological study. When compared to the technique of Fluorescence Spectroscopy (FS), histology requires the physical removal of tissue and their processing in the laboratory, while the FS conducts fast assessments in vivo. The objective of this study was to standardize a methodology for inducing skin atrophy in an experimental model, compare the collagen in normal and atrophic skin, and estimate the potential assessment of FS in skin atrophy. We used 20 adult male Wistar rats, from the UFSCar Central Animal Biotery, kept in a controlled environment. The cutaneous atrophy was induced with topical use of the glucocorticoid Clobetasol propionate 0.05%, 2 times daily for 14 days and evaluated by histological analysis and FS with laser excitation at 532nm and 408nm. We evaluated 96 skin fragments with HE and picrosirius red staining. In biopsies from the first day, the average of epidermal thickness was 44 ± 9&#956;m and, after 14 days of CB, was 16 ± 6&#956;m (p <0.0001), confirming atrophy. This result was confirmed by staining with picrosirius red, which was observed coarsed and disorganized rearrangement of the collagen fibers in the dermis after the use of corticosteroids. For the analysis of results from FS, the spectra have been nominated as "normal" or "atrophic" in correspondence to the histological study. The FS with 408nm laser analysis allowed to distinguish the "normal" and "atrophic" group with fewer spectral parameters. In the future, this technique could be used as a complementary diagnostic method in dermatology.O padrão ouro para avaliar a atrofia de pele é o estudo histológico. Quando comparada à técnica de Espectroscopia de Fluorescência (EF), a histologia exige a remoção física de tecidos e seu processamento em laboratório; enquanto a EF realiza avaliações rápidas e in vivo. O objetivo dessa pesquisa foi padronizar uma metodologia para indução de atrofia cutânea em modelo experimental; comparar o colágeno na pele normal e atrófica; e estimar o potencial da EF na avaliação da atrofia cutânea. Foram utilizados 20 ratos machos Wistar adultos, provenientes do Biotério Central da UFSCar, mantidos em ambiente controlado. A atrofia cutânea foi induzida com o uso tópico do glicocorticóide propionato de clobetasol a 0,05% (CB), 2 vezes ao dia, por 14 dias, e avaliada por meio de estudo histológico e EF com laser de excitação em 532nm e 408nm. Foram avaliados 96 fragmentos de pele com coloração HE e Picrosirius red. Nas biópsias do primeiro dia, a média de espessura da epiderme foi de 44±9&#956;m e, após 14 dias de CB, foi de 16±6&#956;m (p<0,0001), confirmando a atrofia. Esse resultado foi corroborado pela coloração com Picrosirius red, na qual se observou, após uso de corticóide, rearranjo mais grosseiro e desorganizado das fibras colágenas da derme. Para a análise dos resultados da EF, os espectros foram nomeados como normal ou atrófico , em correspondência ao estudo histológico. A avaliação por EF com laser de 408nm permitiu distinguir os grupos normal e atrófico com menor número de parâmetros espectrais. No futuro, esta técnica poderá ser usada como método de diagnóstico complementar na área da dermatologia

Fluorescence spectroscopy as a tool to detect and evaluate glucocorticoid-induced skin atrophy

Topical glucocorticoid (GC) therapy has been successfully used in the treatment of several common cutaneous diseases in clinical practice for a long time, and skin atrophy is one of the most typical cutaneous side effects of this therapy. The aim of this study was to evaluate the potential of noninvasive fluorescence spectroscopy (FS) technique in the detection and classification of GC-induced skin atrophy. A total of 20 male Wistar rats were used in the experimental protocol under controlled environmental conditions and with free access to food. One group received topical application of clobetasol propionate 0.05% for 14 days to induce cutaneous atrophy (atrophic group) and the other (control) group received only vehicle application following the same protocol and schedule. Histological analyses and FS measurements with laser excitation at both 532 nm and 408 nm were obtained on days 1 and 15. The FS results were classified as "normal" or "atrophic" according by histological analysis. Fluorescence spectra obtained with excitation at 408 nm allowed a clear distinction between the control and atrophic groups, and were more informative than the those obtained at 532 nm. Our results reveal that, if correctly applied, FS allows noninvasive evaluation of corticosteroid-induced skin atrophy, and thus represents an important step towards better monitoring of undesirable side effects of cutaneous therapy.CAPES (Brazilian Coordination for the Improvement of Higher Education PersonnelCAPES (Brazilian Coordination for the Improvement of Higher Education Personnelprogram NANOBIOTEC) [23038.027482/2009-60]program NANOBIOTEC