RANKL and lymphocyte-mediated bone loss

RANKL 和淋巴细胞介导的骨丢失

• 批准号: 9275307
• 负责人: CHARLES A O'BRIEN
• 金额: --
• 依托单位: CENTRAL ARKANSAS VETERANS HLTHCARE SYS
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9275307
• 关键词: Address; Alleles; B cell differentiation; B-Lymphocytes; Bone Growth; Bone Marrow; Bone Marrow Cells; Bone Resorption; Bone remodeling; Cell Count; Cells; Cytokine Receptors; Development; Environment; Estrogen Receptor alpha; Estrogen Receptors; Estrogens; Female; Funding; Genes; Genetic study; Gonadal Steroid Hormones; Histologic; Homeostasis; Immune; In Vitro; Label; Lead; Ligands; Lymphocyte; Measures; Mediating; Menopause; Modeling; Molecular; Mus; Osteoblasts; Osteoclasts; Osteocytes; Ovariectomy; Pathologic; Play; Postmenopause; Premenopause; Production; Rattus; Reporter; Role; Skeletal Development; Skeleton; Source; Stromal Cells; T-Cell Activation; T-Lymphocyte; Tumor necrosis factor receptor 11b; Wild Type Mouse; Woman; Work; base; bone; bone loss; bone mass; cell type; cortical bone; cytokine; differentiated B cell; in vivo; male; osteoclastogenesis; prevent; progenitor; public health relevance; receptor; receptor activator of NF-kappa B; receptor expression; skeletal; substantia spongiosa

DESCRIPTION (provided by applicant): A decline in estrogen levels, such as occurs at the menopause, causes bone loss by increasing the number of bone resorbing osteoclasts. The mechanisms by which estrogen controls osteoclast number are only partially understood, but previous studies suggest that lymphocytes play an important role. For example, ovariectomy of mice or rats consistently leads to increased numbers of B lymphocytes in the bone marrow. This increase in B cell number has been suggested to contribute to increased osteoclast formation by different mechanisms, such as B cell production of the osteoclastogenic cytokine receptor activator of NF-kappa-B ligand (RANKL) and differentiation of B cell precursors into osteoclasts. However, until recently, there was no functional evidence that B cells play an essential role in ovariectomy-induced bone loss. In studies leading to this application, we have found that production of the cytokine receptor activator of NF-kappa-B ligand (RANKL) by B lymphocytes is essential for the cancellous bone loss caused by estrogen deficiency in mice. Importantly, RANKL is also required for the increase in B cell number that is caused by estrogen deficiency. Also, ovariectomy did not increase the levels of RANKL in B cells in wild type mice. Together, these results suggest that it is the increase in B cell number that is required for ovariectomy-induced bone loss in this model. It is also important to note that deletion of RANKL from B cells did not prevent loss of cortical bone caused by estrogen deficiency. Therefore, RANKL produced by cell types other than B cells must be involved in the osteoclast formation in this skeletal compartment. Based on these results, we hypothesize that loss of estrogen causes cancellous bone loss, in part, by increasing the number of B cells, which can then act as osteoclast progenitors. Further, we propose that loss of estrogen causes cortical bone loss by altering production of RANKL by cells of the osteoblast lineage. To address these hypotheses, lineage-tracing studies will be performed to determine whether B cells, at any stage of their development, can differentiate into bone resorbing osteoclasts in vivo. In addition, whether estrogen suppresses B cell number by acting directly on these cells will be determined by conditional deletion of estrogen receptor alpha from this cell type. Lastly, mice in which the RANKL gene has been deleted from either osteocytes or from stromal cells of the osteoblast lineage will be ovariectomized to determine whether RANKL produced by these cell types contributes to the cortical bone loss caused by estrogen deficiency.

描述（由申请人提供）：