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.

项目摘要： 衰老与骨量减少有关，骨量减少与早期B细胞（proB）数量减少一致 和preB细胞）。前B细胞接近骨内膜，在那里骨形成成骨细胞和骨吸收 破骨细胞存在。PreB细胞表达两种基因，IGLL 1和VPREB，其蛋白质（λ5和VpreB）形成了细胞的免疫原性。 替代轻链（SLC），结合免疫球蛋白µHC以形成细胞表面表达的preB细胞受体 （preBCR）。在小鼠和人类中，早期B细胞数量及其λ5表达随年龄增长而减少。之甚少 已知早期B细胞和λ5表达在骨稳态和衰老中的作用。这表示 我们的知识差距很大。先前，我们观察到λ5缺陷小鼠的骨脆性增加。因为它 早期B细胞数量和λ5表达通常随年龄增长而下降，我们推断λ5 可能会导致骨骼老化我们的初步数据表明，λ5的缺失破坏了小梁细胞的获取， 骨，减少松质骨质量并加速骨老化。这种表型在女性中更为突出 这与人类骨质疏松症的自然史相似，重要的是，这一过程可以是 颠倒的。用野生型（WT）骨髓重建的辐照λ5-/-小鼠显示骨小梁恢复 当WT小鼠接受λ5-/-骨髓时，观察到骨小梁质量的损失。我们有 鉴定了表达λ5蛋白的间充质基质/干细胞（MSC）的一个子集。与衰老相似- 与早期B细胞数量的减少相关，表达λ5的MSC的数量随着年龄的增长而减少。我们 初步研究表明，破坏λ5或其已知的配体（硫酸乙酰肝素和半乳糖凝集素）在骨髓中， MSC培养，减少成骨细胞的发育和功能。此外，MSC中λ5的缺失促进了它们的生长。 在成骨细胞的扩张中发育成脂肪细胞，导致MSC衰老表型，其诱导 肥胖增加。这表明λ5在MSC发育命运决定中的作用。基于我们的小说 研究结果，我们将检验衰老诱导MSC和早期B细胞λ5表达变化的假设， 影响成骨细胞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 使用λ5-缺陷（λ5-/-）和B细胞耗尽（JH-/-）小鼠将阐明λ5控制骨的机制 稳态和骨骼老化。在具体的目标1中，我们将确定λ5表达的变化如何影响骨骼肌的生长， 衰老在目标2中，我们将确定λ5的主要细胞来源对骨发育和衰老的贡献。在 目的3，我们将确定λ5控制骨稳态和衰老的机制。我们的实验 方法包括使用原代MSC和早期B细胞共培养，早期B细胞分泌的质谱 影响MSC的因素，过继转移和条件性缺失，以剖析λ5在骨髓间充质干细胞移植中的体内作用。 衰老该项目的意义在于，成功地实现这些目标将推动 骨免疫学，通过鉴定λ5作为预防和/或治疗年龄- 相关的骨质流失。