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: 9415546
• 负责人: Elena Ambrogini
• 金额: $ 29.92万
• 依托单位: UNIV OF ARKANSAS FOR MED SCIS
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-16 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9415546
• 关键词: Adverse effects; Affect; Age; Aging; Anabolism; Antibodies; Apoptosis; Apoptotic; Atherosclerosis; Attenuated; Binding; Biological Assay; Bone Marrow; Bone Resorption; Cardiovascular Diseases; Cells; Characteristics; Chronic; Defense Mechanisms; Development; Disease; Dual-Energy X-Ray Absorptiometry; Epidemiology; Epitopes; Genes; High Fat Diet; Homeostasis; Human; Immunoglobulin M; Impairment; In Vitro; Incidence; Inflammation; Inflammatory; Inflammatory Response; Innate Immune System; Knockout Mice; Label; Lipid Peroxidation; Lipids; Lipoprotein (a); Lymphocyte; Macrophage Activation; Measurement; Mentors; Mus; Musculoskeletal Diseases; Musculoskeletal System; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; Oxidative Stress; Oxides; Pathogenesis; Pathogenicity; Pathway interactions; Performance; Phenotype; Phospholipids; Phosphorylcholine; Play; Process; Production; Proteins; Receptor Activation; Research; Role; Serum; Skeleton; Surface; Testing; Tissues; Transgenes; Transgenic Mice; Virulence Factors; Work; adduct; amino group; antigen binding; base; bone; bone loss; bone mass; cell injury; cortical bone; cytokine; feeding; genetic analysis; macrophage; microCT; negative affect; novel; novel therapeutic intervention; novel therapeutics; osteoclastogenesis; osteoprogenitor cell; oxidation; oxidized low density lipoprotein; prevent; progenitor; red fluorescent protein; scavenger receptor; skeletal; substantia spongiosa

PROJECT SUMMARY/ABSTRACT Lipid peroxidation leads to the formation of oxidation specific epitopes (OSEs) that are proinflammatory and, unless they are removed, cause extensive cell damage. OSEs are present in oxidized low density lipoproteins (OxLDLs) and on the surface of apoptotic cells and cleared by binding to scavenger receptors (SRs) on macrophages. Persistence and/or excessive amounts of OSEs overwhelm the defense mechanisms against them. Additionally, the inflammatory response initiated by SR activation leads to tissue damage that becomes pathogenic in several diseases, including atherosclerosis. Natural antibodies (nAbs) produced by B1 cells of the innate immune system recognize OSEs and block their adverse effects. Epidemiologic evidence in humans as well as mechanistic studies in mice indicate that the OSE-rich OxLDLs are a pathogenic factor in both atherosclerosis and osteoporosis. Phosphocholine in oxidized phospholipids (PC-OxPL) forms OSEs that are recognized by several SRs including ScrB1 and by the nAb E06 IgM. Transgenic mice expressing a single chain (scFv) form of the antigen-binding domain of E06 IgM (E06-scFv) are protected against atherosclerosis induced by high fat diet (HFD) because the transgene prevents the binding of OSEs to macrophages and activation of inflammatory pathways. We have found that transgenic mice expressing E06-scFv have increased trabecular bone mass, accompanied by an increase in bone formation rate. The E06-scFv transgene also prevents the cortical bone loss caused by HFD by increasing endosteal osteoblast number and bone formation. E06 IgM prevents the negative effects of OxLDL on proliferation, differentiation, and survival of cultured osteoblastic cells. Our findings suggest that anti-OSE antibodies promote bone anabolism by preventing the negative effects of OSEs on osteoblasts and bone formation. Moreover, the level of anti-PC IgM (which includes E06) declines with age in mice, in association with a decline in bone mass. We hypothesize that increased production of OSEs due to accelerated apoptosis, oxidative stress, or chronic inflammation, in concert with inadequate levels of anti-OSE antibodies, contributes to the pathogenesis of osteoporosis. Studies proposed in this application will establish the cellular mechanisms of the bone anabolic effect of the E06-scFv transgene using DXA, microCT, histomorphometry, and measurement of inflammatory cytokines. Changes in the number and characteristics of osteoclast and osteoblast progenitors will be analyzed, in part by use of a novel FACS approach to study fluorescently labeled osteoprogenitors. The mechanisms by which the E06-scFv transgene attenuates HFD- induced bone loss will be further explored and the ability of this transgene to prevent the bone loss caused by old age will be determined. In addition, we will investigate whether OSEs negatively affect osteoblasts by binding to ScrB1, the most abundant SR for PC-OxPL in osteoblasts. Successful completion of this work should elucidate a previously unappreciated role of OSEs and anti-OSE antibodies in bone homeostasis and may suggest a novel therapeutic approach for the management of osteoporosis and atherosclerosis simultaneously.

项目总结/摘要 脂质过氧化导致氧化特异性表位（OSE）的形成，其是促炎性的， 除非它们被移除，否则会造成广泛的细胞损伤。OSE存在于氧化低密度脂蛋白中 （OxLDL）和凋亡细胞的表面上，并通过与细胞表面上的清道夫受体（SR）结合而清除。 巨噬细胞持久性和/或过量的OSE压倒了防御机制 他们此外，由SR激活引发的炎症反应导致组织损伤， 在包括动脉粥样硬化在内的多种疾病中具有致病性。天然抗体（nAbs）由B1细胞产生， 先天性免疫系统识别OSE并阻断其不利影响。人类的流行病学证据， 以及小鼠的机制研究表明，富含OSE的OxLDL是两种疾病的致病因素， 动脉粥样硬化和骨质疏松症。氧化磷脂（PC-OxPL）中的磷酸胆碱形成OSE， 由包括ScrB 1的几种SR和nAb E06 IgM识别。表达单链的转基因小鼠 E06 IgM的抗原结合结构域（E06-scFv）的单链（scFv）形式被保护免受动脉粥样硬化诱导的损伤。 因为转基因阻止了OSE与巨噬细胞的结合和巨噬细胞的激活， 炎症通路。我们已经发现表达E06-scFv的转基因小鼠具有增加的骨小梁细胞， 骨量增加，同时伴有骨形成率的增加。E06-scFv转基因还阻止了E06-scFv的表达。 HFD通过增加骨内膜成骨细胞数量和骨形成引起的皮质骨丢失。E06 IgM 防止OxLDL对培养的成骨细胞的增殖、分化和存活的负面影响。 我们的研究结果表明，抗OSE抗体通过防止骨形成的负面影响， OSE对成骨细胞和骨形成的影响。此外，抗PC IgM（包括E06）的水平随着时间的推移而下降。 年龄在小鼠中，与骨量下降有关。我们假设，由于OSE的产生增加， 加速细胞凋亡，氧化应激或慢性炎症，与抗OSE水平不足一致 骨质疏松症的发病机制是什么？本申请中提出的研究将建立 使用DXA，microCT， 组织形态计量学和炎性细胞因子的测量。的数量和特征的变化 破骨细胞和成骨细胞祖细胞将被分析，部分是通过使用一种新的流式细胞术方法来研究， 荧光标记的骨祖细胞。E06-scFv转基因减弱HFD-1的机制 将进一步探索诱导的骨丢失，并且这种转基因预防由骨丢失引起的骨丢失的能力。 年龄将被确定。此外，我们将研究OSE是否通过结合成骨细胞而对成骨细胞产生负面影响。 ScrB 1是成骨细胞中PC-OxPL最丰富的SR。这项工作的成功完成应阐明 OSE和抗OSE抗体在骨稳态中的作用以前未被认识到，这可能表明一种新的 同时治疗骨质疏松症和动脉粥样硬化。