Digoxin attenuates bisphosphonate related osteonecrosis of the jaws by RORγt-dependent Th17 response in male rats

Abstract

The study aimed to evaluate digoxin, an RORγt inhibitor, in Medication-Related Osteonecrosis of the Jaws (MRONJ) in male rats treated with zoledronic acid (ZA). Forty male Wistar rats were divided into a negative control group (0.1 mL/kg saline), a positive control group (ZA, 0.20 mg/kg), and three test groups treated with ZA and digoxin at 1 (DG1), 2 (DG2), or 4 (DG4) mg/kg. These groups received treatment three times weekly. ZA was administered intravenously on days 0, 7, and 14, followed by extraction of the left lower first molar on day 42, a final ZA dose on day 49, and euthanasia on day 70. Analyses included radiographic, histomorphometric, and immunohistochemical evaluation of the mandibles, western blotting of gingiva, and mechanical tests on femurs. Statistical analysis was performed using ANOVA/Bonferroni tests (P < .05). Digoxin reduced radiolucency of MRONJ (P < .001), inflammatory cells, empty osteocyte lacunae (P < .001), apoptotic osteoclasts (P < .001), and Caspase-3-positive osteocytes (P = .021). ZA increased immunoreactivity for most markers except c-Fos, while digoxin reduced interleukin 17, TNF-α, IL-6, IL-2, FOXP3, c-Jun, NFκB (P < .001), TGF-β (P = .009), RANKL (P = .035), and OPG (P = .034). Digoxin also reversed RORγt expression (P < .001), increased diarrhea scores (P = .028), renal and cardiac indexes (P < .001), and enhanced femur mechanical properties (P < .013). Digoxin attenuated MRONJ by inhibiting RORγt and reducing the Th17 response.