The Mechanism of Bone Remodeling After Bone Aging.

Senescence mainly manifests as a series of degenerative changes in the morphological structure and function of the body. Osteoporosis is a systemic bone metabolic disease characterized by destruction of bone microstructure, low bone mineral content, decreased bone strength, and increased brittleness and fracture susceptibility. Osteoblasts, osteoclasts and osteocytes are the main cellular components of bones. However, in the process of aging, due to various self or environmental factors, the body's function and metabolism are disordered, and osteoporosis will appear in the bones. Here, we summarize the mechanism of aging, and focus on the impact of aging on bone remodeling homeostasis, including the mechanism of ion channels on bone remodeling. Finally, we summarized the current clinical medications, targets and defects for the treatment of osteoporosis.

Interleukin 1 beta-induced chloride currents are important in osteoarthritis onset: an in vitro study.

Persistent hypotonic and inflammatory conditions in the joint cavity can lead to the loss of cartilage matrix and cell death, which are the important mechanisms of osteoarthritis (OA) onset. Previous studies have confirmed that the existence of a hypotonic environment is a red flag for inflammation, as hypotonic environment induces the opening of the chloride channel of the cell and promotes chloride ion efflux, which prompts the cell volume to increase. Chloride channels play an important role in the regulation of mineralization and chondrocyte death. Here, we reported that OA chondrocytes showed a significant increase of cell death rate and the imbalance of cartilage matrix catabolism. We found that the distribution of skeleton protein F-actin was disordered. In addition, the volume-sensitive chloride current of OA chondrocytes decreased significantly with the increase of the expression levels of inflammation-related proteins caspase-1, caspase-3, and NLRP3. Moreover, interleukin-1ß (IL-1ß) showed a potential to activate the chloride current of normal chondrocytes. These results indicate that IL-1ß-induced chloride channel opening in chondrocytes may be closely related to the occurrence of OA. This chloride channel opening process may therefore be a potential target for the treatment of OA.

Overexpression of ClC-3 Chloride Channel in Chondrosarcoma: An In Vivo Immunohistochemical Study with Tissue Microarray.

BACKGROUND Recently, ClC-3 chloride channel expression has been noted to be high in some tumors. In chondrosarcoma, which is a malignant tumor with a high incidence in the bone, there has been no previous literature regarding ClC-3 chloride channel expression. Here we evaluated the expression of ClC-3 chloride channel in chondrosarcoma and explored its clinical significance. MATERIAL AND METHODS In this study, 75 chondrosarcoma and 5 normal cartilage tissues were collected. Thereafter, tissue microarray was performed. Immunohistochemistry was also used to observe the level of ClC-3 chloride channel expression between normal and chondrosarcoma tissues. RESULTS Results showed that the expression of ClC-3 chloride channel in the normal chondrocyte was thinner, since it showed distinct differentiation among chondrosarcoma specimens. Interestingly, we noticed that the moderately-differentiated chondrosarcoma (MDC) and the poorly-differentiated chondrosarcoma (PDC) exhibited 94.44% of ClC-3 chloride channel. Besides, the subcellular localization of ClC-3 chloride channel was changed in association with malignant degree changes. The subcellular localization of ClC-3 chloride channel in the MDC and PDC tissue was localized in the cytoplasm and both nucleus and cytoplasm: 83.33% (5 out of 6 cases) and 91.66% (11 out of 12 cases) respectively. On the other hand, we noticed that patient age and gender could have a relation with ClC-3 chloride channel expression; 30- to 60-year-old males showed more expression. CONCLUSIONS These results demonstrated a high frequency of ClC-3 chloride channel overexpression and subcellular localization differences in MDC and PDC tissue, suggesting a specific role of ClC-3 chloride channel in the pathogenesis of chondrosarcoma.