Expressão de marcadores inflamatórios na osteonecrose dos maxilares induzida por bisfosfonatos e efeito do tratamento crônico com ácido zoledrônico nos tecidos gengival e ósseodentário de ratos

Abstract

The Zoledronic Acid (ZA) is a bisphosphonate (BF) that can lead to immune-inflammatory dysregulation leading to Bisphosphonate-related Osteonecrosis of the Jaws (BRONJ). The objective of this study was to determine the cellular profile and the immune expression of inflammatory markers in mandibular bone of a BRONJ experimental model and in gingival and tooth of rats chronically treated with ZA. Materials and Methods: Male Wistar rats (180-220 g) were chronically infused (four times) venously with sterile saline or 0.04, 0.20 or 1.00 mg/kg of ZA and the left hemimandible was subjected to first molar exodontia (day 49). After 70 days we performed the euthanasia and the hemimandibles (right and left) were histologically and immunohistochemically analyzed (CD68, Tumor Necrosis Factor alpha (TNF-α), Interleukin(IL)-1β, inducible Nitric Oxide Synthases (iNOS), Nuclear Factor kappa B (NF-kB) and IL-18(bidding protein) bp). In bone subjected to exodontia (left hemimandible) we counted the viable and empty osteocyte lacunae, the viable and apoptotic osteoclasts, the polymorphonuclear neutrophils cells (PMN), mast cells and positive cytoplasmic cells for cited markers. Dental pulp and periodontium of first right molar (contralateral hemimandible) was histologically analyzed by presence of inflammatory cells, dilated/ectasic blood vessels (pulp only) and immunohistochemically by scores. We repeated the protocol (saline versus 0.20 mg/kg ZA) to dosage of TNF-α, IL-1β, myeloperoxidase (MPO), Malondialdehyde (MDA) e Glutathione (GSH) of gingiva of animals. Results: the BRONJ was observed in 0.20 mg/kg and 1.00 mg/kg ZA-treated animals that showed increase in percentage of empty osteocyte lacunae (p<0.001) and percentage of apoptotic osteoclast (p<0.001), total osteoclasts number (p=0.003), PMN (p=0.009), cytoplasmic positive cells for CD68 (p<0.001), TNF-α (p=0.001), IL-1β (p=0.001), iNOS (p<0.001) e NF-kB (p=0.006), and nuclear positivity for NF-kB (p=0.011). The immune expression of IL-18bp decreased dose dependently (p=0.005). In dental pulp there was augment in number of mononuclear CD68+ cells (p=0.026) and immunostaining for TNF-α (p=0.020), IL-1β (p=0.027), iNOS (p=0.001) in odontoblasts and IL-1β (p=0.027) in non odontoblasts dental pulp cells. In periodontium ZA treated animals showed an increase in number of animals showing inflammatory cells (p=0.001) and cytoplasmic immunostaining for TNF-α (p=0.003), IL-1β (p=0.004), iNOS (p=0.008) and NF-kB (p=0.025). MPO (p<0.001), TNF-α (p=0.002), IL-1β (p<0.001) and GSH (p=0.005) levels were significantly raised in 0.20 mg/kg ZA treated gingiva animals. Conclusion: There is overexpression of inflammatory markers in exodontia area with establishing of BRONJ. The chronic infusion of ZA raised the expression of inflammatory markers and cells in gingiva, periodontium and pulp tissue of rats.