Efeito osteoprotetor do gel do derivado semissintético 6,7-dimetox-3-nitrocumarina na periodontite experimental em camundongos: envolvimento via de sinalização WNT/β-catenina

Abstract

Periodontitis is an immunoinflammatory process that affects the protective and supporting tissues of the teeth, manifested by inflammatory cellular infiltration and bone resorption. WNT/β-catenin signaling plays a crucial role in regulating gene transcription of proteins essential for the differentiation, maturation and activity of osteoblasts, directly influencing bone metabolism. From the plant Platymiscium floribundum Vog. the derivative 6,7-dimethoxy-3-nitrocoumarin (DN) was developed, which was able to reduce periodontal bone loss. The objective of the present work was to carry out a systematic review on WNT/β-catenin signaling in bone loss associated with experimental periodontitis, in addition to developing a gel containing DN to evaluate its local effect in experimental periodontitis (PE) and investigate the participation of the pathway WNT/β-catenin in the possible therapeutic response. The systematic review was carried out according to the standard protocol for animal studies (CAMARADES), resulting in the inclusion of 8 studies. These studies suggest that modulation of components of the WNT/b-catenin pathway has a positive impact, reducing bone loss associated with periodontitis. In the preclinical study, PE was induced by placing a cotton bandage (4-0) around the cervical area of the lower first molars of anesthetized animals. Initially, the best concentration of DN to be incorporated into the gel was determined. For this, the naive and PE groups were used, and two groups of animals were subjected to PE and treated with DN (1 mg/kg or 10 mg/kg), orally, once a day. Administration began 30 minutes before PE induction (prophylactic approach) or from the 5th day after PE induction (therapeutic approach). Based on the results, a gel containing 1 mg/ml DN was developed. This gel was applied locally to animals undergoing PE (NITRO group). The control groups included animals that were not subjected to any procedure or treatment (NAIVE group) and animals subjected to PE that received local treatment with a gel containing only the vehicle for DN incorporation (VEIC Group). The DN gel or vehicle gel was administered from the 11th day of PE, twice a day, to the gingival tissue around the 1st and 2nd lower molars, until the animals were euthanized on the 21st day. After euthanasia, blood was collected for serum analysis of bone alkaline phosphatase (FAO) and the jaws were removed for analysis of alveolar bone loss (AOP) (Macroscopy and μCT Analysis); Histological and histomorphometric analysis; Collagen analysis; measurement of IL-1 β, TNF α and IL-10 in gingival tissue; and Analysis of gene expression of components of the WNT/β-catenin pathway. Statistical analysis (p<0.05) was performed by Analysis of Variance (ANOVA), followed by Tukey's comparison test. The results were expressed as mean±S.E.M. Animals in the VEIC group showed higher POA (p<0.05), greater collagen destruction, increased inflammatory cytokines (IL-1β and TNF- α), reduced anti-inflammatory cytokine (IL-10), significant reduction in FAO, when compared to the Naïve group. Treatment with DN gel reduced POA (p<0.05) considering all parameters analyzed when compared to the VEIC group. Furthermore, the DN gel decreased the concentrations of TNF-α, IL-1β (p<0.05), increased IL-10 and FAO activity (p<0.05), compared to the VEIC group. Treatment with DN gel increased the expression of WNT10b and β-catenin and reduced the expression of GSK-3 β and DKK-1 (p<0.05), when compared to the VEIC group. The results therefore suggest antiresorptive and anti-inflammatory effects of DN gel, with the potential participation of the WNT/ β -catenin signaling pathway in experimental periodontitis.