Influence of aging on the preB cell product, λ5, and its contribution to age-related bone loss

衰老对前 B 细胞产物 α5 的影响及其对与年龄相关的骨质流失的贡献

• 批准号: 10589513
• 负责人: Mohamed Khass
• 金额: $ 30.44万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10589513
• 关键词: Adipocytes; Adoptive Transfer; Affect; Age; Age-Related Bone Loss; Aging; Antibodies; B-Lymphocytes; Binding; Biological Assay; Bone Development; Bone Marrow; Bone Marrow Cells; CD19 gene; Cadherins; Cell Count; Cell surface; Cells; Charge; Coculture Techniques; Data; Development; Endosteum; Female; Fracture; Galactose Binding Lectin; Genes; Globulins; Goals; Hematopoietic stem cells; Heparitin Sulfate; Homeostasis; Human; Immunoglobulins; Impairment; In Vitro; Knowledge; Lead; Ligand Binding; Ligands; Link; LoxP-flanked allele; Marrow; Mediating; Membrane; Mesenchymal; Methods; Molecular Abnormality; Mus; Natural History; Obesity; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Ovariectomy; Pathologic; Patients; Phenotype; Population; Prevention; Process; Production; Proteins; Receptor Cell; Recovery; Role; Skeletal bone; Source; Stem Cell Development; Surface; Tail; Testing; Transplantation; Wild Type Mouse; aged; bone; bone aging; bone fragility; bone loss; bone mass; differential expression; in vivo; insight; male; mesenchymal stromal cell; new therapeutic target; novel; novel therapeutic intervention; osteogenic; osteoimmunology; progenitor; reconstitution; skeletal; stem cell aging; stem cells; substantia spongiosa; surrogate light chain

Project Summary: Aging is associated with a decrease in bone mass that coincides with decreased numbers of early B cells (proB and preB cells). PreB cells approach the endosteum where bone forming osteoblasts and bone resorbing osteoclasts reside. PreB cells express two genes, IGLL1 and VPREB, whose proteins (λ5 and VpreB) form the surrogate light chain (SLC) that binds immunoglobulin µHC to form the cell-surface expressed preB cell receptor (preBCR). In both mice and humans, early B cell numbers and their λ5-expression decrease with age. Little is known about the role of early B cells and λ5 expression in bone homeostasis and aging. This represents a significant gap in our knowledge. Previously, we observed increased bone fragility of λ5-deficient mice. Since it is recognized that both early B cell numbers and λ5 expression normally decline with age, we reasoned that λ5 might contribute to skeletal aging. Our preliminary data show that absence of λ5 disrupts acquisition of trabecular bone, decreases trabecular bone mass and accelerates bone aging. This phenotype is more prominent in female than male mice, resembling the natural history of osteoporosis in human, and importantly this process can be reversed. Irradiated λ5-/- mice reconstituted with wild type (WT) bone marrow show recovery of trabecular bone mass, whereas loss of trabecular bone mass was observed when WT mice received λ5-/- marrow. We have identified a subset of mesenchymal stromal/stem cells (MSCs) that express λ5 protein. Similar to the aging- associated decrease in early B cell numbers, the numbers of λ5-expressing MSCs decrease with age. Our preliminary studies show that disrupting λ5, or its known ligands (heparan sulfate and galectins) in bone marrow MSC cultures, diminishes osteoblast development and function. Moreover, loss of λ5 in MSCs promotes their development into adipocytes at the expanse of osteoblasts, resulting in an MSC aging phenotype which induces increased adiposity. This suggests a role for λ5 in MSC developmental fate decision. Building on our novel findings, we will test the hypothesis that aging induces changes in λ5 expression in MSCs and early B cells that impact osteoblast development and function and lead to age-associated bone loss. Our premise is that studies using λ5-deficient (λ5-/-) and B cell-depleted (JH-/-) mice will elucidate mechanisms of λ5 control of bone homeostasis and skeletal aging. In specific Aim 1, we will determine how changes in λ5 expression affect skeletal aging. In aim 2, we will identify contributions of major cellular source(s) of λ5 to bone development and aging. In aim 3, we will determine the mechanisms by which λ5 controls bone homeostasis and aging. Our experimental approach incorporates the use of primary MSCs and early B cell co-culture, Mass Spec of early B cell secreted factors affecting MSCs, and adoptive transfer and conditional deletion to dissect the in-vivo role of λ5 during aging. The significance of this project is that successful pursuit of these aims will advance the field of osteoimmunology through identifying λ5 as a new therapeutic target for prevention and/or treatment of age- associated bone loss.

项目总结： 衰老与骨量的减少有关，这与早期B细胞的数量减少相一致(Prob 和Preb细胞)。Preb细胞接近骨内膜，在那里成骨细胞和骨吸收 破骨细胞驻留在。Preb细胞表达两个基因，IGLL1和VprEB，它们的蛋白(λ5和VpreB)形成 结合免疫球蛋白µHC形成细胞表面表达的Preb细胞受体的代理轻链(SLC) (前BCR)。在小鼠和人类中，早期B细胞的数量及其λ-5的表达随着年龄的增长而减少。小才是 已知早期B细胞和λ5的表达在骨稳态和衰老中的作用。这表示一个 在我们的知识上有很大差距。此前，我们观察到λ5缺陷小鼠的骨脆性增加。因为它 发现早期B细胞数量和λ-5的表达均随年龄增长而下降，我们推测λ-5 可能会导致骨骼老化。我们的初步数据显示，λ5的缺失扰乱了骨小梁的获取 骨骼，减少骨小梁质量，加速骨骼老化。这一表型在女性中更为突出。 比雄性小鼠，类似于人类骨质疏松的自然历史，重要的是这个过程可以 颠倒了。经照射的野生型(WT)骨髓重建的λ5-/-小鼠的骨小梁恢复 当WT小鼠接受λ5/骨髓时，观察到松质骨量的丢失。我们有 鉴定出一组表达λ5蛋白的间充质基质/干细胞(MSCs)。与衰老相似- 伴随着早期B细胞数量的减少，表达λ-5的MSCs的数量随着年龄的增长而减少。我们的 初步研究表明，干扰骨髓中的λ5或其已知配体(硫酸肝素和半乳糖凝集素) MSC培养，减少成骨细胞的发育和功能。此外，MSCs中λ5的缺失促进了他们的 在成骨细胞扩张时发育成脂肪细胞，导致MSC衰老表型，诱导 肥胖症增加。这表明λ5在决定骨髓间充质干细胞发育命运中发挥了作用。以我们的小说为基础 发现，我们将检验衰老诱导骨髓间充质干细胞和早期B细胞λ5表达变化的假设 影响成骨细胞的发育和功能，并导致与年龄相关的骨丢失。我们的前提是研究 利用λ5缺陷(λ5-/-)和B细胞耗尽(JH-/-)小鼠将阐明λ5控制骨骼的机制 动态平衡和骨骼老化。在特定目标1中，我们将确定λ5表达的变化如何影响骨骼 衰老。在目标2中，我们将确定λ5的主要细胞来源(S)对骨发育和衰老的贡献。在……里面 目的3，我们将确定λ5控制骨内稳态和衰老的机制。我们的实验 方法结合使用原代MSCs和早期B细胞共培养，大量分泌早期B细胞 影响骨髓间充质干细胞的因素，以及过继转移和条件缺失对λ5在体内的作用 衰老。这个项目的意义在于，成功地追求这些目标将推动 骨免疫学通过确定λ5作为预防和/或治疗AGE的新治疗靶点 相关的骨丢失。