Ligand-dependent and cell type-specific functions of integrin CD11b/CD18 in multiple sclerosis

整合素 CD11b/CD18 在多发性硬化症中的配体依赖性和细胞类型特异性功能

基本信息

批准号：
10660972
负责人：
LI ZHANG
金额：
$ 41.51万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-15 至 2025-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10660972
关键词：
Amino Acids Animals Anti-Inflammatory Agents Antigens Autoantigens Autoimmune Autoimmune Diseases Axon Binding Blood Blood coagulation Bone Marrow Bone Marrow Transplantation Cells Complex Data Demyelinations Development Disease Disease Progression Disease remission Endotoxins Event Exhibits Experimental Autoimmune Encephalomyelitis Extravasation FDA approved Fibrin Fibrinogen Fibrinolysis Future Goals Hemostatic function Homologous Gene Host Defense Human ITGAM gene ITGB2 gene Immunosuppression Infiltration Inflammatory Inflammatory Response Infusion procedures Integrins Interleukin-10 Interleukin-6 Knock-in Mouse Knowledge Leukocytes Ligand Binding Ligands Link LoxP-flanked allele Lymphocyte Macrophage Macrophage-1 Antigen Mediating Microglia Molecular Monoclonal Antibodies Multiple Sclerosis Mus Mutagenesis Mutate Myelin Nerve Pathogenesis Pathologic Pathway interactions Patients Peptides Pharmaceutical Preparations Play Primary Progressive Multiple Sclerosis Property Proteins Regulatory T-Lymphocyte Relapsing-Remitting Multiple Sclerosis Risk Role Scanning Severities Severity of illness Signal Pathway Signal Transduction System Systemic Lupus Erythematosus TNFSF5 gene Testing Therapeutic immunosuppression Thrombosis Variant antagonist anti-CD20 autoreactivity cell type chronic inflammatory disease design experience experimental study genome wide association study in vivo insight interest loss of function loss of function mutation mouse model multiple sclerosis treatment mutant nervous system disorder neuroinflammation next generation novel receptor response targeted treatment

项目摘要

Leakage of blood fibrinogen into the central nerve system and its conversion into reactive fibrin plays a key role in many neurological diseases, including multiple sclerosis (MS), a neuroinflammatory disease. Fibrin stimulates the proinflammatory activity of macrophages and microglia by binding to the integrin receptor CD11b/CD18 (Mac-1; αMβ2). However, this proinflammatory paradigm of CD11b/CD18 is complicated by our surprising discovery that CD11b/CD18 possesses anti-inflammatory properties in several mouse models of inflammatory diseases. Indeed, independent genome-wide association studies have linked loss-of-function variants of human CD11b to increased risks of autoimmune systemic lupus erythematosus. The molecular mechanism by which ligand binding property of CD11b confers macrophages/microglia with distinct inflammatory activities is unknown. The overall goal of this project is two-fold: (1) to determine the molecular basis by which CD11b/CD18 ligand binding confers macrophages and microglia with different inflammatory properties and (2) to identify specific leukocyte subsets that mediate the pathological or beneficial functions of CD11b/CD18 in MS. In our preliminary studies, we discovered a novel CD11b mutant, CD11bKH, that is defective in fibrin binding. Knock-in mice expressing CD11bKH exhibited normal macrophage infiltration but reduced proinflammatory activity in vivo. Using a mouse model of progressive MS, we found that CD11bKH mice developed early signs of disease but could spontaneously reverse disease progression, a unique ability not observed in wild-type or CD11b-deficient mice. Our bone marrow transplantation experiments further demonstrated that CD11b on bone marrow-derived cells and resident microglia play distinct roles in the pathogenesis of MS. Based on these exciting preliminary results, we hypothesize that CD11b/CD18 modulates the pathogenesis of MS in a ligand-dependent and cell type-specific manner. To test this hypothesis, we will determine the ability of CD11b mutants including CD11bKH to bind its various protein ligands associated with MS. We will also identify key signaling pathways responsible for the CD11b/CD18-fibrin-initiated proinflammatory activities (Aim 1). We will next determine the mechanism by which CD11b/CD18 modulates disease progression and remission. Importantly, we will inactivate CD11b on bone marrow-derived cells or resident microglia at specific stages of disease development using our newly generated CD11b-floxed mice and determine their impact on disease development (Aim 2). Finally, we will investigate whether disrupting the CD11b/CD18-fibrin pathway will enhance anti-CD20-induced antigen-specific immunosuppression (Aim 3). Completion of this project will fill the gap in our knowledge regarding the mechanism by which CD11b/CD18 ligand binding dictates its inflammatory properties. Importantly, given that ocrelizumab (a humanized anti-CD20 mAb) is the only FDA-approved treatment for primary progressive MS, the information obtained from this project can help us develop next-generation anti-CD20-based drugs to treat this intractable form of the disease.

血纤维蛋白原泄漏到中枢神经系统中，其转化为反应性纤维蛋白起着关键作用在许多神经系统疾病中，包括多发性硬化症（MS），一种神经炎症性疾病。纤维蛋白通过与整联蛋白受体结合，刺激巨噬细胞和小胶质细胞的促炎活性 CD11b/CD18（MAC-1;αMβ2）。但是，我们的CD11b/CD18的促炎范式由我们的令人惊讶的发现，CD11b/CD18在几种小鼠模型中具有抗炎特性炎症性疾病。实际上，独立的全基因组关联研究已将功能丧失联系在一起人CD11b的变体增加了自身免疫性全身性红斑狼疮的风险。分子 CD11b的配体结合特性承认巨噬细胞/小胶质细胞的机制炎症活动尚不清楚。该项目的总体目标是两个方面：（1）确定分子 CD11b/CD18配体结合以不同的炎症为基础巨噬细胞和小胶质细胞属性和（2）确定介导的特定白细胞子集，以介导 MS中的CD11b/CD18。在我们的初步研究中，我们发现了一个新型的CD11b突变体CD11BKH，即纤维蛋白结合有缺陷。表达CD11BKH的敲入小鼠暴露了正常的巨噬细胞浸润，但体内促炎活性降低。使用渐进式MS的鼠标模型，我们发现CD11BKH 小鼠出现了早期的疾病迹象，但可能会赞助疾病的进展，这是一种独特的能力在野生型或CD11b缺陷小鼠中未观察到。我们的骨髓移植实验进一步证明了骨髓衍生细胞和居民小胶质细胞上的CD11b在 MS的发病机理。基于这些令人兴奋的初步结果，我们假设CD11b/CD18 以配体依赖性和细胞类型特异性方式调节MS的发病机理。为了检验这一假设，我们将确定CD11b突变体（包括CD11BKH）结合其各种蛋白质配体相关的能力与MS。我们还将确定负责CD11b/CD18-纤维蛋白引发的关键信号通路促进活动（AIM 1）。接下来，我们将确定CD11b/CD18调制的机制疾病进展和缓解。重要的是，我们将在骨髓衍生的细胞上灭活CD11b或使用我们新生成的CD11b浮游小鼠在疾病发展的特定阶段的居民小胶质细胞并确定它们对疾病发展的影响（AIM 2）。最后，我们将调查是否破坏 CD11b/CD18-纤维蛋白途径将增强抗CD20诱导的抗原特异性免疫抑制（AIM 3）。该项目的完成将填补我们关于CD11b/CD18的机制的知识的空白配体结合决定其炎症特性。重要的是，鉴于Ocrelizumab（人源化抗CD20 mab）是唯一用于原始进行性MS的FDA批准的治疗方法，从此获得的信息项目可以帮助我们开发下一代抗CD20的药物来治疗这种棘手的疾病。