Role of Natural Antibodies Against Oxidation Specific Epitopes in Bone Homeostasis

抗氧化特异性表位的天然抗体在骨稳态中的作用

• 批准号: 10477223
• 负责人: Elena Ambrogini
• 金额: --
• 依托单位: CENTRAL ARKANSAS VETERANS HLTHCARE SYS
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10477223
• 关键词: Adverse effects; Age; Age-Months; Age-Related Bone Loss; Anabolism; Antibodies; Antibody Therapy; Apoptosis; Apoptotic; Atherosclerosis; Binding; Bone Density; Bone Marrow; Calvaria; Cardiovascular Diseases; Cells; Chronic; Data; Defense Mechanisms; Development; Diet; Disease; Epidemiology; Epitopes; Female; Genes; High Fat Diet; Homeostasis; Human; Immunoglobulin M; In Vitro; Incidence; Inflammation; Inflammatory; Inflammatory Response; Innate Immune System; Knockout Mice; Lipid Peroxidation; Lipids; Longevity; Lymphocyte; Measures; Mediating; Mus; Osteoblasts; Osteocytes; Osteogenesis; Osteoporosis; Oxidative Stress; Oxides; Pathogenesis; Pathway interactions; Phenotype; Phospholipids; Phosphorylcholine; Play; Population; Prevention; Production; Proteins; Receptor Activation; Roentgen Rays; Role; Site; Skeleton; Surface; Testing; Therapeutic; Tissues; Transgenes; Transgenic Mice; Veterans; Virulence Factors; Work; adduct; age related; aged; amino group; antigen binding; base; bone; bone loss; bone mass; cell injury; cell type; cohort; cortical bone; cytokine; human old age (65+); in vivo; macrophage; male; natural antibodies; novel therapeutic intervention; osteogenic; overexpression; oxidation; oxidized low density lipoprotein; prevent; scavenger receptor; skeletal; substantia spongiosa

Lipid peroxidation forms highly reactive molecules that generate adducts with amino groups of proteins and lipids, known as oxidation specific epitopes (OSEs). OSEs are ubiquitous pro-inflammatory moieties that cause extensive cell damage if not promptly eliminated. Natural antibodies of the innate immune system, recognize OSEs and block their adverse effects. Scavenger receptors (SRs) expressed in macrophages and other cell types recognize OSEs and dispose of oxidatively-modified endogenous molecules. Persistence and/or excessive amounts of OSEs overwhelm these defense mechanisms, and the inflammatory response initiated by scavenger receptor/toll-receptor activation causes tissue damage and the development of disease. Phosphocholine-containing oxidized phospholipids (PC-OxPLs) form OSEs on oxidized low density lipoproteins (OxLDLs) and on the surface of apoptotic cells. The IgM E06 is a natural antibody that recognizes PC-OxPL. Transgenic mice expressing a single chain (scFv) form of the antigen-binding domain of E06 IgM (E06-scFv) are protected against atherosclerosis and have increased lifespan. This effect results from the prevention of OSE binding to macrophages and the subsequent activation of inflammatory pathways. In humans, low levels of natural antibodies are associated with increased incidence of cardiovascular disease. Epidemiologic evidence in humans as well as mechanistic studies in mice indicate that the OSE-rich OxLDL is a pathogenic factor for osteoporosis as well. Remarkably, we found that the E06-scFv transgene prevents the cortical bone loss caused by HFD by increasing endosteal osteoblast number and bone formation. In addition, E06-scFv increases cancellous and cortical bone in male and female C57Bl/6J mice fed a normal diet by increasing bone formation and osteoblast number. Mechanistic studies showed that E06 IgM prevents the negative effects of OxLDL on proliferation, differentiation, and survival of cultured osteoblastic cells suggesting that anti-OSE antibodies promote bone anabolism by preventing the negative effects of OSEs on osteoblasts. Consistently, the production of anti-osteogenic cytokines by macrophages was not affected in E06-scFv transgenic mice. Deletion of the scavenger receptor ScrB1, the most abundant scavenger receptor for PC- OxPL in cells of the osteoblast lineage, prevents the adverse effects of OxLDL on apoptosis and differentiation. Moreover, anti-PC IgM (which includes E06) decline with age in mice, in association with a decline in bone mass. Therefore, we hypothesize that anti PC-OxPLs antibodies play a beneficial role in skeletal homeostasis by protecting against deleterious effects of PC-OxPLs on bone formation, that are transmitted by ScrB1 on osteoblasts. Increased production of OSEs due to accelerated apoptosis, oxidative stress, or chronic inflammation, in concert with declining levels of anti PC-OxPLs antibodies with age, contributes to the pathogenesis of osteoporosis in both mice and humans. Studies proposed in this application will establish whether ScrB1 mediates the negative effects of PC-OxPLs on osteoblasts in vivo by characterizing the bone phenotype of mice in which the ScrB1 gene has been deleted in cells of the osteoblast lineage. We will also determine if E06-scFv prevents the reduction in bone formation caused by old age. Additionally, we will investigate whether endogenous anti-PC IgM levels correlate with bone mineral density in humans by measuring the levels of anti-PC IgM in a cohort of eligible Veterans who had a bone mineral density (BMD) assessment by dual X-ray absorptiometry (DXA). Successful completion of this work may may suggest a novel therapeutic approach for the management of osteoporosis and atherosclerosis simultaneously.

脂质过氧化形成高反应性分子，该分子与氨基的蛋白质组产生加合物， 脂质，称为氧化特异性表位（OS）。 OSS是无处不在的促炎性部分引起的 如果没有迅速消除，则广泛的细胞损害。先天免疫系统的天然抗体，识别 OS并阻止其不利影响。在巨噬细胞和其他细胞中表达的清道夫受体（SRS） 类型识别氧化性内源性分子的OS和处置。持久性和/或 过量的OSS压倒了这些防御机制，炎症反应引发了 通过清道夫受体/收费受体激活会导致组织损伤和疾病的发展。 氧化的磷脂（PC-OXPLS）在氧化的低密度上形成OSO（PC-OXPLS） 脂蛋白（OXLDL）和凋亡细胞的表面。 IGM E06是一种识别的天然抗体 PC-OXPL。 E06 IgM的抗原结合结构域的单链（SCFV）形式的转基因小鼠 （E06-SCFV）受到防止动脉粥样硬化的保护，并增加了寿命。这种影响是由 预防与巨噬细胞的OSE结合以及随后的炎症途径的激活。在 人类，低水平的天然抗体与心血管疾病的发生率增加有关。 人类的流行病学证据以及小鼠的机理研究表明，富含OSE的OXLDL是 骨质疏松症也是一种致病因素。值得注意的是，我们发现E06-SCFV转基因可防止 由HFD引起的皮质骨质流失是由于增加内膜成骨细胞数和骨形成而引起的。此外， E06-SCFV增加了雄性和雌性C57BL/6J小鼠的取消和皮质骨，喂养正常饮食 增加骨形成和成骨细胞数。机械研究表明，E06 IgM可防止 OXLDL对培养成骨细胞的增殖，分化和存活的负面影响表明 该抗蛋白抗体通过防止OSO对成骨细胞的负面影响促进骨变性。 一致地，在E06-SCFV中不影响巨噬细胞的抗肌生成细胞因子的产生 转基因小鼠。删除清道夫受体SCRB1，这是PC-最丰富的清道夫受体 成骨细胞谱系细胞中的OXPL防止了OXLDL对凋亡和分化的不利影响。 此外，抗PC IGM（包括E06）随着年龄的年龄而下降，骨骼下降 大量的。因此，我们假设抗PC-OXPLS抗体在骨骼稳态中起有益的作用 通过防止PC-OXPLS对骨形成的有害影响，这些作用是由SCRB1传递的 成骨细胞。由于凋亡，氧化应激或慢性的加速凋亡，OOS的产生增加 随着年龄的增长，炎症与抗PC-OXPLS抗体水平下降相结合，有助于 小鼠和人类骨质疏松的发病机理。该应用程序提出的研究将建立 SCRB1是否通过表征骨骼的体内介导PC-OXPLS对成骨细胞的负面影响 在成骨细胞谱系中已删除了SCRB1基因的小鼠的表型。我们也会 确定E06-SCFV是否防止了老年引起的骨形成的减少。此外，我们会的 研究内源性抗PC IgM水平是否通过人类的骨矿物质密度相关 在具有骨矿物质密度（BMD）的合格退伍军人队列中测量抗PC IgM的水平 通过双X射线吸收法（DXA）评估。成功完成这项工作可能可能暗示一本小说 同时治疗骨质疏松和动脉粥样硬化的治疗方法。