EFEITOS DA FOTOBIOMODULAÇÃO E DO USO DE CREME A BASE DE SERICINA EM LESÕES EXPERIMENTAIS POR QUEIMADURA DE 2° GRAU EM RATOS WISTAR

Abstract

Second-degree burns are among the most common skin injuries, characterized by intense pain and high sensitivity. Previous in vitro studies have shown that sericin stimulates fibroblast migration and may favor lesion re-epithelialization. Photobiomodulation, whose anti-inflammatory effect is widely recognized, also presents therapeutic potential. Thus, both the isolated use of each of these approaches and their association were analyzed, with the objective of investigating their contribution to the recovery of experimentally induced second-degree burns. For this purpose, male Wistar rats were randomized into six groups: a control group (CON) that received no treatment; a group treated with silver sulfadiazine ointment (SUL); a group treated with sericin cream (SER); a group treated with low-level laser photobiomodulation (LBP); a group treated with sulfadiazine and laser (SUL+LBP); and a group treated with sericin and laser (SER+LBP). Each group consisted of 20 animals, 12 weeks old and approximately 350g. The groups were subdivided, with half of the animals euthanized after 7 days (D7) and the other half after 14 days (D14) following lesion induction. The burn was caused by contact with a metal instrument previously heated in a direct flame with the anesthetized animal's skin for a period of 3 seconds. Macroscopic evaluation by photography, thermography by photothermography, and histomorphometry of intact and lesioned skin were performed. A systematic review with meta-analysis was also conducted, considering articles that report the use of photobiomodulation in burn treatment. For statistical analysis, the generalized linear models test was performed with p=0.05. No statistical differences were found regarding lesion area among the 7-day groups; however, there was a statistical difference (p<0.05) between the CON and LBP groups and the others, as they presented a reduction in burned area. There was a statistical difference between the AV0 and AV1 evaluations in the analysis of lesion surface temperature in the 7- and 14-day groups (p>0.05). However, there was no difference in the analysis of granulation tissue formation scale among any group. Regarding collagen deposition, the SER, LBP, SUL+LBP, and SER+LBP groups were different from the CON control group, with higher scores on the scale used (p<0.05); the SER+LBP group also presented a higher percentage of type I collagen, being statistically different from the other groups (p<0.05). In the molecular analyses of the 14-day groups, there was a reduction in TNFα, TBARS, and CAT concentrations (p<0.05), especially in the treatments combined with LBP, indicating a reduction in oxidative stress. The study pointed to an improvement in the tissue healing process, and further analyses could further elucidate the mechanisms of skin repair in the analyzed animals