Résumé
BACKGROUND:There is a very close relationship between osteoporosis and periodontal disease in postmenopausal women, but the mechanism remains unclear. OBJECTIVE:To investigate the expression of nuclear factor-κB in the alveolar bone andinterleukin-17 in the serum and gingiva in the mouse model of osteoporosis caused by ovariectomy. METHODS:Female mice aged 3 months were randomly divided into ovariectomy and sham operation groups. At 6 months after surgery, the mouse models were evaluated histologically on the submandibular bone and thigh bone stained with hematoxylin and eosin. In the submandibular bone, the expression levels of OCN and Runx2 were detected by RT-PCR, and the expression level of nuclear factor-κB was detected by immunohistochemical staining and western blot assay. Besides, the expression level of interleukin-17 in the serum and gingival homogenate was evaluated using Cytometric Beads Array. RESULTS AND CONCLUSION:The thigh bone in the ovariectomy group revealed the thin cortical bone, enlarged marrow cavity, and increased resorption lacunae, as well as fewer, thinner trabeculae with lower density and irregular structure. Compared with the sham operation group, the expression levels of OCN and Runx2 in the alveolar bone were decreased in the ovariectomy group. The activation of nuclear factor-κB (P65)appeared with P65 positive expression in the submandibular bone in the ovariectomy group, and the relative expression level was higher than that in the sham operation group. The serum level of interleukin-17 in the ovariectomy group was higher than that in the sham operation group, but the level in the gingival tissue showed no significant difference between the two groups. These results indicate that estrogen deficiency after ovariectomy can activate nuclear factor-κB signal pathway to play a role in periodontal osteolysis. However interleukin-17 in the local periodontal tissue may not be a key cytokine to damage the periodontal tissue.
Résumé
BACKGROUND:As the multipotent differentiation potential, bone marrow mesenchymal stem cells exert an important role in bone metabolism disorders, which is regulated by a variety of hormones and cytokines. Currently, the epigenetic regulatory mechanisms underlying osteogenic differentiation of bone marrow mesenchymal stem cells are unclear, and association between histone deacetylase (Hdac) and osteoporosis needs to be further explored. OBJECTIVE:To investigate the epigenetic mechanisms of bone formation by analyzing the expression of Hdac1, 3, 4 mRNA profile in bone marrow mesenchymal stem cells isolated from ovariectomized mice. METHODS:A total 30 female healthy Kunming mice were randomly divided into sham group and ovariectomy group. After 7 days of adaptive feeding, mice in the ovariectomized group (n=15) were subject to bilateral ovariectomy;mice in sham group (n=15) were sham-operated. RESULTS AND CONCLUSION:In the ovariectomy group, the trabecular bone of the femur was sparse or broken, the width of trabecular bone was narrowed, the trabecular separation was widened, and the trabecular bone volume was reduced. The level of Hdac3 mRNA was lower in bone marrow mesenchymal stem cells from ovariectomized mice compared with controls, but there was no significance between Hdac1, Hdac4 mRNA expression of the two groups. These findings demonstrate that Hdac might play an important role in bone remodeling in the model of estrogen deficiency-induced osteoporosis.