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.

项目概要： 衰老与骨量减少有关，骨量减少与早期 B 细胞 (proB) 数量减少相一致。 和前B细胞）。 PreB 细胞表达两个基因：IGLL1 和 VPREB，其蛋白质（λ5 和 VpreB）形成了破骨细胞。 结合免疫球蛋白 µHC 形成细胞表面表达的前 B 细胞受体的替代轻链 (SLC) (preBCR)。在小鼠和人类中，早期 B 细胞数量及其 λ5 表达随着年龄的增长而减少。 已知早期 B 细胞和 λ5 表达在骨稳态和衰老中的作用。 此前，我们观察到 λ5 缺陷小鼠的骨骼脆性增加。 众所周知，早期 B 细胞数量和 λ5 表达通常会随着年龄的增长而下降，我们推断 λ5 我们的初步数据表明，缺乏 λ5 会破坏小梁的获得。 骨，减少骨小梁量并加速骨老化，这种表型在女性中更为突出。 与雄性小鼠相比，重新组装了人类骨质疏松症的自然史，重要的是，这个过程可以 用野生型 (WT) 骨髓重建的受辐射 λ5-/- 小鼠显示骨小梁恢复。 质量，而当 WT 小鼠接受 λ5-/- 骨髓时，观察到骨小梁质量损失。 鉴定出表达与衰老相似的 λ5 蛋白的间充质基质/干细胞 (MSC) 子集。 与早期 B 细胞数量减少相关，表达 λ5 的 MSC 数量随着年龄的增长而减少。 初步研究表明，破坏骨髓中的 λ5 或其已知配体（硫酸乙酰肝素和半乳糖凝集素） MSC 培养会降低成骨细胞的发育和功能，此外，MSC 中 λ5 的缺失会促进其生长。 在成骨细胞范围内发育成脂肪细胞，导致 MSC 老化表型，从而诱导 这表明 λ5 在 MSC 发育命运决定中发挥作用。 研究结果表明，我们将检验以下假设：衰老会引起 MSC 和早期 B 细胞中 λ5 表达的变化， 影响成骨细胞的发育和功能并导致与年龄相关的骨质流失，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 骨控制机制 在具体目标 1 中，我们将确定 λ5 表达的变化如何影响骨骼。 在目标 2 中，我们将确定 λ5 的主要细胞来源对骨骼发育和衰老的贡献。 目标 3，我们将确定 λ5 控制骨稳态和衰老的机制。 方法结合使用原代 MSC 和早期 B 细胞共培养、分泌的早期 B 细胞的质谱 影响 MSC 的因素，以及过继转移和条件删除，以剖析 λ5 在体内的作用 该项目的意义在于，成功实现这些目标将推动老龄化领域的发展。 骨免疫学通过将 λ5 确定为预防和/或治疗年龄相关疾病的新治疗靶点 相关的骨质流失。