The relevance of IL-33 and its receptor ST2 for bone remodeling is not well-defined. Our aim was to assess the role and underlying mechanisms of IL-33/ST2 in mechanically induced bone remodeling. BALB/c (wild type) and ST2 deficient (St2(-/-)) mice were subjected to mechanical loading in alveolar bone. Microtomography, histology, and real-time quantitative PCR were performed to analyze bone parameters, apoptosis and bone cell counts, and expression of bone remodeling markers, respectively. MC3T3-E1 osteoblastic cells and bone marrow cells were used to verify if mechanical force triggered IL-33 and ST2 expression as well as the effects of IL-33 on osteoclast differentiation and activity. Mechanical loading increased the expression of IL-33 and ST2 in alveolar bone in vivo and in osteoblastic cells in vitro. St2(-/-) mice had increased mechanical loading-induced bone resorption, number of osteoclasts, and expression of proresorptive markers. In contrast, St2(-/-) mice exhibited reduced numbers of osteoblasts and apoptotic cells in periodontium and diminished expression of osteoblast signaling molecules. In vitro, IL-33 treatment inhibited osteoclast differentiation and activity even in the presence of receptor activator of NF-κB ligand. IL-33 also increased the expression of pro-apoptotic molecules, including Bcl-2-associated X protein (BAX), cell-surface Fas receptor (FAS), FASL, FAS-associated death domain, tumor necrosis factor-related apoptosis-inducing ligand, and BH3 interacting-domain death (BID). Overall, these findings suggest that IL-33/ST2 have anti-osteoclastogenic effects and reduce osteoclast formation and activity by inducing their apoptosis.

Interleukin-33 (IL-33) and its receptor, ST2, are implicated in bone remodeling. The lack of estrogen after menopause results in an accelerated bone loss. Here we investigated the role of ST2 in the bone loss induced by estrogen deficiency. ST2-deficient mice (ST2 ) and their littermates (wildtype [WT]) were ovariectomized (OVX), while ovary-intact mice were used as controls. Bone sites were analyzed by microcomputed tomography, histomorphometry, and quantitative real-time polymerase chain reaction (qPCR). Deletion of IL-33 or ST2 resulted in a similar bone loss in the femur and maxilla. Ovariectomy in WT mice caused bone loss in the same areas. The lack of ST2 in OVX mice did not alter bone remodeling in the femur but prevented bone loss in the maxilla. Consistently, ovariectomy increased the IL-33 messenger RNA (mRNA) levels in the maxilla but not in the femur. Under mechanical stimulation, ovariectomy and ST2 deletion independently increased bone remodeling induced by orthodontic tooth movement, which was also associated with a greater number of osteoclasts and a reduced number of osteoblasts in the maxillary bone. ST2 OVX mice, however, displayed twice as many osteoblasts as that of WT OVX mice. Ovariectomy and ST2 deletion differently altered the cytokine mRNA levels in the maxilla. Remarkably, interleukin-10 expression was decreased in both WT OVX and ST2 mice, and this reduction was completely restored in ST2 OVX mice. The results demonstrate that estrogen and IL33/ST2 independently protect against bone loss. However, the ovariectomy-induced bone loss is IL-33/ST2-dependent in the maxilla but not in the femur, indicating a bimodal and site-specific role of ST2 in bone remodeling.

Purpose: To determine the identification, morphometry and volumetric analysis of genital tubercles in radiographic and tomographic examinations. Methods: 15 dry human jaws were exposed to four stages. At first, they were exposed to two-dimensional radiographic and three-dimensional image examinations. In the second stage, the same image exams were performed on the mandibles with the genial tubers accentuated with barium sulphate. In the third stage, a gingival needle was inserted in the lingual foramen to perform the imaging exams. In the last stage, the genial tubercles were removed for imaging. The radiographs were evaluated by two radiologist dentists trained for morphological analysis. For the morphometric evaluation, the software ITK-snap® Version 3.6.0 was used. Results: As a result of the periapical radiographs, no changes were observed in the initial or final images. In addition, with the highlight of barium sulphate, it is noticed that the genial tubers increase the radiopacity of the symphysis region. In the occlusal radiographic images, changes were observed in each of the stages, since the position of the mandible during the examination shows the projections of the genial tubercles, and the two-dimensional examination is indicated for the evaluation of these anatomical structures. Conclusion: Cone beam computed tomography has, in a different way, the property of providing three-dimensional images rich in detail. Thus, it can be concluded that the periapical radiography of the lower incisors highlights the lingual canal, the occlusal radiography highlights the genial tubercles and tomography is the exam that presents the conditions to differentiate these structures.