RESUMEN
Background and objectives: Pytiriasis alba (PA) is a common skin disorder which affects 80% of children between six and 16 years. The etiology of PA is unclear, but hypo-pigmented patches in photo-exposed zones characterize the disease. Because the high ultraviolet exposition of the skin promotes an acute inflammatory response and an increase of oxidative stress (OS), this study aimed to evaluate the expression levels of inflammatory and OS-related genes in skin biopsies, and their association with PA. Materials and Methods: A cross-sectional study was carried out. Skin biopsies of the lesion sites and healthy skin (controls) from 16 children with PA were evaluated. The tissue expression of IL-4, IL-6, IL-17A, TNFα, INFγ, IL-1ß, SOD1, and HMOX1 was analyzed by qRT-PCR, using SYBR Green and glyceraldehyde-3-phosphate dehydrogenase gene as the endogenous control. Results: There were differences in the ΔCq values of HMOX1, SOD1, IL-6, and IFNγ between tissue with lesions and healthy skin (p < 0.05). Compared with healthy skin, IL-6, IFNγ, HMOX1, and SOD1 were predominantly under-expressed in the lesion sites. However, 25% of skin biopsies with lesions showed over-expression of these four genes. Positive correlations between the expression of IL-6 and HMOX1, SOD1, and IFNγ (p < 0.05) were also observed. Conclusions: Our results suggest the presence of molecular stages of PA, defined according to the over-expression (first stage) or under-expression (second stage) of the HMOX1, SOD1, IL-6, and IFNγ genes in abnormal skin tissue. These findings may have implications for the selection of treatment for PA-related lesions.