Immunomodulation of white matter integrity after stroke

中风后白质完整性的免疫调节

• 批准号: 9243323
• 负责人: Xiaoming Hu
• 金额: $ 33.69万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9243323
• 关键词: Anti-Inflammatory Agents; Anti-inflammatory; Astrocytes; Attenuated; Axon; Behavior; Biological Process; Brain; Brain region; Cell Differentiation process; Cell Maturation; Coculture Techniques; Cognitive; Cognitive deficits; Corpus Callosum; Corpus striatum structure; Data; Demyelinations; Development; Dichloromethylene Diphosphonate; Disease; Endothelin-1; Exhibits; External Capsule; Failure; Future; Generations; In Vitro; Inflammation; Inflammatory; Injection of therapeutic agent; Interleukin-10; Interleukin-14; Interleukin-4; Internal Capsule; Intranasal Administration; Intraventricular Infusion; Ischemia; Ischemic Stroke; Knockout Mice; Liposomes; Long-Term Effects; Mediating; Microglia; Microinjections; Middle Cerebral Artery Occlusion; Modeling; Mus; Myelin Basic Proteins; Myelin Sheath; Neuroglia; Neurologic Deficit; Neurological outcome; Neurons; Oligodendroglia; Outcome; PPAR alpha; PPAR gamma; Peroxisome Proliferator-Activated Receptors; Phenotype; Production; Rattus; Recovery; Recovery of Function; Regulation; Reperfusion Therapy; Role; Signal Transduction; Stroke; System; Testing; base; cytokine; immunoregulation; improved; in vivo; inflammatory marker; injured; macrophage; migration; myelination; nanomolar; nervous system disorder; neurological recovery; neurorestoration; novel; oligodendrocyte precursor; post stroke; precursor cell; promoter; public health relevance; receptor; remyelination; repaired; stroke therapy; tissue repair; transcription factor; white matter; white matter injury

 DESCRIPTION (provided by applicant): White matter (WM) injury, characterized by demyelination and loss of axonal integrity, is an important cause of long-term sensorimotor and cognitive deficits after stroke. A persistent pro-inflammatory microenvironment after stroke is considered one underlying mechanism that hinders oligodendrocyte precursor cell (OPCs) differentiation and maturation into myelinating oligodendrocytes (OLs). Accumulating recent evidence suggests that the different functional phenotypes of microglia/macrophages contribute considerably to the regulation of inflammatory status of injured WM and ultimately impact the WM integrity. Specifically, "alternatively activated" M2 microglia are essential for remyelination and WM repair because they resolve local inflammation, clear broken myelin sheath or cellular debris, and provide trophic factors that promote OPC differentiation. Interleukin-4 (IL-4) is thus far the best characterized inducer for M2 polarization of microglia/macrophages; however, its role in microglia regulation in WM and long term stroke outcomes is not known. We have discovered that IL-4 is a novel endogenous protectant against WM injury and that it promotes WM repair. Our preliminary results show that IL-4 knockout (KO) mice exhibit worse sensorimotor deficits over 14 days after tMCAO. Remarkably, IL-4 KO mice display deteriorated WM injury. Moreover, IL-4 KO mice show markedly reduced numbers of M2 microglia/macrophages in WM-enriched brain regions, including the corpus callosum and striatum after tMCAO. In contrast, intraventricular infusion of IL-4 for 14 days beginning 6h after MCAO attenuates long-term sensorimotor and cognitive deficits and improves WM integrity. In addition to promoting M2 polarization, we have found that IL-4 directly induces the differentiation of primary OPCs into mature OLs at nanomolar concentrations and that this effect of IL-4 on OPCs is mediated through the activation of PPARγ. In this proposal, we will focus on the novel action of IL-4 on WM integrity and explore the underlying mechanisms. We will test the overarching hypothesis that IL-4 promotes WM integrity and long-term neurological recovery after stroke by dual mechanisms, in that it 1) promotes OPC differentiation/maturation via PPARγ activation and 2) potentiates microglia/macrophage polarization toward the beneficial M2 phenotype, which is essential for remyelination and WM repair in demyelinating brains. The Specific Aims to be tested are: Aim 1: Test the hypothesis that post-ischemia IL-4 treatment enhances WM integrity and long-term neurological recovery after stroke. IL-4 will be delivered into the brain by repeated intranasal administrations after reperfusion. The endpoints for assessment include neurological outcomes and various markers for WM integrity. Aim 2: Test the hypothesis that IL-4 induces OPC differentiation into mature OLs and promotes axonal remyelination via PPARγ activation. Aim 3: Test the hypothesis that IL-4 potentiates microglia/macrophage polarization into the inflammation-resolving, tissue repair-enhancing M2 phenotype and restores a "healthy" microenvironment for efficient WM repair.