RESUMO
PURPOSE: Clinically, it is challenging to manage diabetic patients with periodontitis. Biochemically, both involve a wide range of inflammatory/collagenolytic conditions which exacerbate each other in a "bi-directional manner." However, standard treatments for this type of periodontitis rely on reducing the bacterial burden and less on controlling hyper-inflammation/excessive-collagenolysis. Thus, there is a crucial need for new therapeutic strategies to modulate this excessive host response and to promote enhanced resolution of inflammation. The aim of the current study is to evaluate the impact of a novel chemically-modified curcumin 2.24 (CMC2.24) on host inflammatory response in diabetic rats. METHODS: Type I diabetes was induced by streptozotocin injection; periodontal breakdown then results as a complication of uncontrolled hyperglycemia. Non-diabetic rats served as controls. CMC2.24, or the vehicle-alone, was administered by oral gavage daily for 3 weeks to the diabetics. Micro-CT was used to analyze morphometric changes and quantify bone loss. MMPs were analyzed by gelatin zymography. Cell function was examined by cell migration assay, and cytokines and resolvins were measured by ELISA. RESULTS: In this severe inflammatory disease model, administration of the pleiotropic CMC2.24 was found to normalize the excessive accumulation and impaired chemotactic activity of macrophages in peritoneal exudates, significantly decrease MMP-9 and pro-inflammatory cytokines to near normal levels, and markedly increase resolvin D1 (RvD1) levels in the thioglycolate-elicited peritoneal exudates (tPE). Similar effects on MMPs and RvD1 were observed in the non-elicited resident peritoneal washes (rPW). Regarding clinical relevance, CMC2.24 significantly inhibited the loss of alveolar bone height, volume and mineral density (ie, diabetes-induced periodontitis and osteoporosis). CONCLUSION: In conclusion, treating hyperglycemic diabetic rats with CMC2.24 (a tri-ketonic phenylaminocarbonyl curcumin) promotes the resolution of local and systemic inflammation, reduces bone loss, in addition to suppressing collagenolytic MMPs and pro-inflammatory cytokines, suggesting a novel therapeutic strategy for treating periodontitis complicated by other chronic diseases.
RESUMO
BACKGROUND: CMC2.24, a novel tri-ketonic chemically modified compound based on natural di-ketonic curcumin, has been shown to reduce bone loss and inflammatory mediators in experimental periodontitis, however, a potential dose-response relationship was not determined. The purpose of this study was to assess the effects of different doses of CMC2.24 on inflammation and bone resorption in vivo and also to describe on the effects of CMC2.24 on macrophage response. METHODS: CMC2.24 was administered daily to animals for 28 days by oral gavage, at the following doses: 0 (control), 1, 3, 10, and 30 mg/kg of body weight. Experimental periodontitis was induced by injections of lipopolysaccharide (LPS) into the gingival tissues. Outcomes assessed were bone resorption, detection of tartrate-resistant acid phosphatase, and determination of gene expression. In vitro, macrophages (RAW264.7) were treated with different concentrations of CMC2.24: 1, 3, 10, and 30 µM and then subjected to different activation stimuli. Gene expression, phagocytic activity, production of reactive oxygen species (ROS) and cytokine production were evaluated. RESULTS: CMC2.24 inhibited bone resorption, osteoclastogenesis, and tumor necrosis factor (TNF)-α expression in vivo. These beneficial responses reached maximum levels at a dose of 1 mg/kg, i.e. no dose-dependent effect. In vitro, CMC2.24 reduced the production of TNF-α and interleukin-10, inhibited phagocytic activity and stimulated production of ROS. A dose-dependent effect was observed only for ROS production. CONCLUSION: Low doses of CMC2.24 (1 mg/kg/day) administered orally were sufficient to significantly inhibit alveolar bone resorption associated with the experimental periodontal disease; whereas in vitro macrophage inflammatory gene expression and phagocytosis were reduced, whereas production of ROS was stimulated.