Anti-inflammatory and antiresorptive effects of Calendula officinalis on inflammatory bone loss in rats

The aim of this work was to evaluate the anti-inflammatory and antiresorptive effects of Calendula officinalis (CLO) on alveolar bone loss (ABL) in rats. Male Wistar rats were subjected to ABL by ligature with nylon thread around the second upper left molar. The contralateral hemimaxillae were used as control. Rats received saline solution (SAL) or CLO (10, 30, or 90 mg/kg) 30 min before ligature and daily until the 11th day. The maxillae were removed and prepared for macroscopic, radiographic, micro-tomographic, histopathologic, histometric analysis, and immunohistochemical localization of receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG). The gingival tissues were used to quantify the myeloperoxidase (MPO) activity, tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta) concentrations by ELISA. Blood samples were collected for leukogram and to evaluate the bone-specific alkaline phosphatase (BALP) activity and serum levels of aspartate and alanine transaminases (AST/ALT). The bone loss induced by 11 days of ligature induced bone loss, reduced levels of BALP, leukocyte infiltration, increased MPO activity, gingival concentrations of TNF-alpha and IL-1 beta, and RANKL while reduced OPG immunoexpressions in the periodontal tissue and leukocytosis. Of the CLO, 90 mg/kg reduced bone loss, neutrophilia, the levels of pro-inflammatory mediators, and RANKL expression, while it increased OPG immunopositive cells and BALP serum levels, when compared to SAL. CLO did not affect either kidney or liver function, indicated by serum AST/ALT levels. The present data suggests that CLO reduced inflammatory bone resorption in experimental periodontitis, which may be mediated by its anti-inflammatory properties and its effects on bone metabolism. CLO can be a potential therapeutical adjuvant in the treatment of periodontitis.