ABSTRACT
PURPOSE: The use of nitrogen-containing bisphosphonates (n-bis) is associated with necrosis of the jaws, also known as bisphosphonate-related osteonecrosis of the jaws (BRONJ); however, the pathophysiology is unknown. Matrix metalloproteinase-9 (MMP-9) expression is essential for normal bone healing and is also required for angiogenesis. N-bis alters MMP-9 expression in vitro and in vivo; therefore, we hypothesized that n-bis alters MMP-9 expression during oral wound healing after tooth extraction. MATERIALS AND METHODS: A total accumulated dose of 2.25 mg/kg (n = 20) of Zoledronic acid (ZA) Zometa or saline (control, n = 20) was administered to Sprague-Dawley male rats. Next, both groups had maxillary molar teeth extracted. Rats were sacrificed at postoperative day 1, 3, 7, or 21. Western blotting or multiplex ELISA was used to evaluate proteins of interest. Real-time polymerase chain reaction was used to assess the relative quantities of target gene mRNA. MMP-9 enzymatic activity was assessed by zymography. RESULTS: The ZA group showed a statistically significant reduction in bone mineralization rate 21 days after tooth extraction compared with the control group (Student t test, P = .005). Moreover, ZA-treated animals showed a statistically significant increase in MMP-9-specific mRNA at postoperative days 3 (P = .003), 7 (P < .0001), and 21 (P < .0001) and protein on postoperative days 3 (P = .005) and 7 (P < .0001). MMP-9 enzymatic activity was also increased in ZA-treated rats compared with control animals (Student t test, P = .014). We also evaluated the extraction sockets for the presence of tissue inhibitor of MMP-1 (TIMP1), which is an inhibitor of MMP-9 enzymatic activity. TIMP1-specific mRNA and protein were not significantly altered by ZA treatment at the times tested (P > .05). Receptor of NF-κB ligand (RANKL) is known to regulate the expression of MMP-9; we therefore assessed the RANKL expression in our experimental oral wound-healing model. The ZA-treated animals had significantly increased RANKL mRNA at postoperative days 3 (P = .02) and 21 (P = .004), while the protein expression was significantly increased at postoperative days 1 (P < .0001), 7 (P = .02), and 21 (P = .03) compared with the control group. CONCLUSIONS: ZA reduced bone mineralization within tooth extraction sockets, suggesting aberrant bone healing. ZA increases the amount and enzymatic activity of MMP-9, while apparently not altering the amount of TIMP1 within extraction sockets. RANKL is increased in ZA-treated rats, which suggests that increased MMP-9 expression is due, in part, to augmented RANKL expression.
Subject(s)
Alveolar Process/enzymology , Bone Density Conservation Agents/therapeutic use , Diphosphonates/therapeutic use , Imidazoles/therapeutic use , Matrix Metalloproteinase 9/drug effects , Tooth Extraction , Tooth Socket/enzymology , Alveolar Process/drug effects , Animals , Blotting, Western , Calcification, Physiologic/drug effects , Fluorescent Dyes , Interleukin-6/analysis , Male , Matrix Metalloproteinase 2/analysis , Matrix Metalloproteinase 2/drug effects , Matrix Metalloproteinase 9/analysis , Maxilla/surgery , Molar/surgery , RANK Ligand/analysis , RANK Ligand/drug effects , Rats , Rats, Sprague-Dawley , Real-Time Polymerase Chain Reaction , Time Factors , Tissue Inhibitor of Metalloproteinase-1/analysis , Tissue Inhibitor of Metalloproteinase-1/drug effects , Tooth Socket/drug effects , Wound Healing/physiology , Zoledronic AcidABSTRACT
Matrix metalloproteinase-8 (MMP-8) participates in skin wound healing and inflammation. We hypothesized that MMP-8 plays a role in wound healing after tooth extraction and in periapical inflammation. Bone formation, collagen metabolism, and inflammation in tooth extraction socket and in periapical lesions were analyzed in wild-type mice and in MMP-8-deficient (MMP-8(-/-)) mice. New trabecular bone area in the extraction sockets and in periapical lesions were similar in both groups. In extraction sockets significantly more type III procollagen was synthesized, and the neutrophil and MMP-9 levels were lower in MMP-8(-/-) mice. The amount of Fas ligand, identified as a substrate for MMP-8, was lower in alveolar mucosa but higher in alveolar bone of MMP-8(-/-) mice. These results indicate that MMP-8 can modulate inflammation and collagen metabolism of alveolar bone and mucosa.
Subject(s)
Matrix Metalloproteinase 8/deficiency , Tooth Extraction , Tooth Socket/enzymology , Alveolar Process/enzymology , Animals , Chemokine CX3CL1/analysis , Collagen/metabolism , Collagen Type III/biosynthesis , Fas Ligand Protein/analysis , Granulocyte Colony-Stimulating Factor/analysis , Granulocyte-Macrophage Colony-Stimulating Factor/analysis , Interferon-gamma/analysis , Interleukin-6/analysis , Leukocyte Count , Male , Matrix Metalloproteinase 9/analysis , Mice , Mice, Inbred C57BL , Mice, Inbred Strains , Mice, Knockout , Mouth Mucosa/enzymology , Neutrophils/enzymology , Neutrophils/pathology , Osteogenesis/physiology , Periapical Diseases/enzymology , Periapical Diseases/physiopathology , Procollagen/biosynthesis , Tooth Socket/physiopathology , Wound Healing/physiologyABSTRACT
Cyclosporin A (CyA) is a cyclic peptide used as an immunosuppressive agent because it can block the synthesis of interleukin-2 and other cytokines produced by CD4+ lymphocytes. It is widely used for the prevention of allograft rejection and treatment of autoimmune diseases. Several side-effects of CyA treatment have been reported, among which are chronic nephrotoxicity, hepatotoxicity and neurotoxicity, lymphoproliferative neoplasms, hypertension, thromboembolic complications and gingival overgrowth. Here, using a rat molar model, it is demonstrated that CyA immunosuppression inhibits the activity of matrix metalloproteinases 2 and 9 in the early phase of granulation tissue in the healing dental socket. These observations suggest that CyA may interfere with the wound healing following dental extractions.
