Influência da suplementação oral com lactiplantibacillus plantarum 6.2 no desenvolvimento da osteonecrose experimental em ratos

Abstract

Osteonecrosis (ON) is a disease characterized by the death of bone cells in a segment of bone associated with loss of blood supply. Among the types of bone necrosis, the most relevant for clinical practice of Dentists is Medication-Related Osteonecrosis of the Jaw (MRONJ), given its location in the jawbones and its relation to oral infections. In order to evaluate the influence of oral supplementation with Lactiplantibacillus plantarum 6.2 (LP 6.2) in a murine model of MRONJ, 20 male rats of the species Rattus norvegicus, Wistar lineage, aged 8 to 10 weeks and weighing approximately 250g, were used. The animals were divided into groups: BASAL (N=4) representing negative control; LAC (N=4) representing a group supplemented with LP 6.2; ONE, positive control (N=6); and ONE+LAC representing a group with induction of osteonecrosis and supplementation with LP 6.2 (N=6). Over 8 weeks, osteonecrosis was induced with 250μg/kg of Zoledronic Acid via intraperitoneal injection, with 0.9% saline solution injected in the BASAL and LAC groups. Extraction of the left lower first molar in the fourth week was the trigger for osteonecrosis in all animals. For LP 6.2 supplementation, bacterial concentration was adjusted and administered via gavage to the LAC and ONE+LAC groups, while non-supplemented groups underwent the same stress with saline solution. The animals were euthanized, and their mandibles dissected for macroscopic examination of bone exposure and epithelial repair. Microscopically, histo-morphometric methods were used for quantitative evaluation of photomicrographs, presenting results in area/μm² or pixel/μm². Histological analyses of the mandibles quantified bone exposure area, tissue viability (area of anucleated osteocytes), and extracellular matrix (ECM) deposition. Immunohistochemical analyses for NF-kB and TGF-ß markers in the mandibles were quantified, and intestinal analysis included immunohistochemistry for tight junctions. Macroscopic and histomorphometric data were analyzed using one-way ANOVA and Tukey's post-test, with statistical significance set at 5% (p<0.05) to determine differences between groups. The BASAL, LAC, and ONE+LAC groups showed partial or total mucosal repair, smaller areas of bone exposure, and preserved osteocytes. ECM deposition was more evident in the LP 6.2 supplemented groups. NF-kB immunostaining was more pronounced in the ONE group compared to others, with statistical significance, while TGF-ß was more present in the LAC group, with the ONE group showing the least staining. In summary, supplementation with LP 6.2 in the treatment of MRONJ proves effective for bone and epithelial repair, and was effective in reducing NF-kB-mediated inflammation and increasing TGF-ß in mandibular osteonecrosis lesions.