RESUMO
BACKGROUND: Oral isotretinoin (ISO) is the drug of choice for the treatment of severe acne. For photoaging treatment, ISO has been proved to be effective in some controlled and noncontrolled trials and is an alternative to topical retinoic acid (RA) therapy, which causes an expected skin irritation. OBJECTIVE: To evaluate and compare the skin remodeling in patients taking ISO 20 mg 3 times a week for 12 weeks and 12 weeks after the end of the treatment to quantify collagen I and collagen III augmentation. MATERIAL AND METHODS: Immunohistochemical studies were performed to evaluate the expression of collagen I and collagen III, metalloproteinases (MMPs) -1, -3, -7, -9, -12, and the tissue inhibitor of MMP type-1 (TIMP-1) of the skin of 20 45 to 50-year-old women through morphometry in a semiquantitative method. The inclusion criteria were facial aging 2 and 3 of Glogau's classification, with phototypes between II and V who had not entered menopause. Biopsies of the skin of the left preauricular region were performed at three different times: pre-treatment (T0), end of 12-week treatment (T1), and 12 weeks posttreatment (T2). RESULTS: Collagen fibers I and III increased with statistical significance in T1 (50.7%; P = 0.012) but not in T2 (49.7%), which in turn was higher than in T0 (47.2%) for collagen I and T1 (33.3%; P = 0.002) but not in T2 (32.7%), and also was higher than T0 (32.0%) for collagen III. MMP-9 presented a decreased activity with statistical significance in T1 (P = 0.047) and T2 (P = 0.058). MMP-1 showed a reduction in T2 only (P = 0.015). MMPs -3, -7, -12, and TIMP-1 did not present significant modification in their expressions during or after the treatment. CONCLUSIONS: Low-dose ISO is effective in remodeling the extracellular matrix (ECM). This study found that the increase of collagen occurs through the augmentation of both collagen I and collagen III fibers. With originality, it was possible to verify the durability of these fibers for at least 12 weeks. This may be related to the decrease in MMP-9 expression verified at the end of the treatment and 12 weeks posttreatment.