Análise morfológica da ação regenerativa do óleo de pequi em queimaduras cutâneas em camundongos

Abstract

Skin present two layers, the epidermis and dermis, which protect the organism against injuries. First, second, and third-degree burns, can compromise skin functions and initiate tissue repair, which involves hemostasis, inflammation, proliferation, and remodeling. To develop strategies that enhance this process, study of pequi oil (Caryocar brasiliense) medicinal proprieties stands out for its bioactive compounds with healing and anti-inflammatory properties. The therapeutic action of this oil may be related to annexin-A1 AnxA1), a protein that mediates inflammation and participates in processes such as cell proliferation and differentiation. Therefore, this study aims to evaluate the regenerative activity of pequi oil in second-degree skin burns in mice. A burn was made on the back of mice, which were treated (Treated n=18) or not (Control n=18) topically with pequi oil, and sacrificed on days 7, 14 and 21. A fragment of the wound region and the adjacent region was collected, which was established and processed histologically for the performance of several histopathological analyses. In both Treated and Control groups, there was no evidence of re-epithelialization at 7 days. However, morphometric analysis of the newly formed epithelium revealed, at 14 days, a greater epithelial height in the Treated group compared to the Control group (p ≤ 0.05). After 21 days, the epithelial height became similar in both groups, indicating that pequi oil accelerated the proliferative phase, promoting faster wound closure. A gradual increase in type I collagen was observed in the dermis of the animals in the Control group (not significant), while in the Treated group, the amount of this collagen remained stable, indicating that pequi oil inhibited its deposition. On the other hand, the amount of reticular fibers (type III collagen) increased significantly in Treated group at 7, 14, and 21 days compared to their respective Controls (p ≤ 0.05; p ≤ 0.0001; p ≤ 0.001, respectively), indicating that pequi oil modulated the deposition of this collagen throughout the regeneration process. Furthermore, the intensity of AnxA1 protein expression, both in the burned epithelium and in the preserved epithelium, was similar among the different experimental groups analyzed. However, quantifying the epithelial cells immunostained for AnxA1 in the newly formed epithelium, showed that in Treated animals there was a smaller amount at 14 days (p ≤ 0.05) and a greater amount at 21 days, compared to the Control. Furthermore, in preserved epithelium (adjacent to the burn site), the number of AnxA1-positive cells was similar among in the two groups. The results suggest that pequi oil decreases local inflammatory activity, thus regulating the expression of AnxA1, which in turn delays the maturation of type III collagen to type I collagen, favoring tissue repair, to the detriment of healing. Thus, it is concluded that pequi oil can modulate the phases of tissue repair, increasing epithelial thickness and the deposition of reticular fibers, showing promise for the treatment of cutaneous burns.