Treatment of secondary injury after ischemic stroke through targeting microglia

通过靶向小胶质细胞治疗缺血性中风后继发性损伤

• 批准号: 8573537
• 负责人: Jaroslaw Aronowski
• 金额: $ 33.25万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8573537
• 关键词: Acute; Adult; Affect; Agonist; Alteplase; Anti-Inflammatory Agents; Anti-inflammatory; Behavioral; Biological; Brain; Brain Injuries; Cells; Cerebral Ischemia; Cessation of life; Communication; Conditioned Culture Media; Data; Eligibility Determination; Equilibrium; Etiology; Excision; Generations; Healed; Hematogenous; IL4 gene; IL4R gene; Image; In Vitro; Infarction; Inflammation; Inflammatory; Injection of therapeutic agent; Injury; Interleukin-10; Interleukin-13; Interleukin-4; Ischemia; Ischemic Stroke; Knock-out; Life; Ligands; Link; Measures; Mediating; Messenger RNA; Methods; Microglia; Modeling; Molecular Target; Mus; Neurites; Neurons; Outcome Measure; Pathway interactions; Patients; Peroxisome Proliferator-Activated Receptors; Phagocytes; Phagocytosis; Phenotype; Play; Process; Production; Property; Proteins; RXR; Reactive Oxygen Species; Receptor Signaling; Recombinants; Recovery; Role; STAT6 gene; Secondary to; Signal Transduction; Source; Staging; Stress; Stroke; T-Lymphocyte; TNF gene; Therapeutic; Time; Tissues; Toxic effect; Translating; United States; acute stroke; base; brain cell; brain tissue; clinically relevant; cytokine; cytotoxic; cytotoxicity; disability; effective therapy; functional outcomes; healing; improved; in vivo; injured; macrophage; microbicide; neurological recovery; neutralizing antibody; novel; post stroke; public health relevance; receptor; receptor expression; relating to nervous system; repaired; research study; response; sensor; stroke recovery; transcription factor

DESCRIPTION (provided by applicant): Though the activated microglia/macrophages (M¿) are known to contribute to secondary brain injury after stroke, M¿ are also instrumental in the repair process. To explain such contrasting roles, two M¿ phenotypes, "harmful"/M1 and "healing"/M2, have been proposed. Importantly, the M1 M¿ can be polarized to M2 and vice versa. While various molecules derived from stroke-injured cells have the propensity to polarize M¿ toward M1 type (causing the generation of pro-inflammatory cytokines and pro-oxidants), other molecules (e.g. generated by T cells), such as IL-4, IL10 or TGF¿, polarize M¿ toward the M2 type. The M2 M¿ control the cleanup processes (phagocytosis- mediated removal of toxic and pro-inflammatory cellular debris), and the production of trophic factors. Thus, the source of toxicity and the biological and physical barriers hampering neural reorganization are removed, while providing trophic support governing neuronal sprouting (the repair process). Without the M2 M¿, healing would not be possible. While both M1 and M2 M¿ phenotypes co-exist shortly after stroke, M2 phenotype weakens within 2-3 days allowing M1 type to dominate. This adversely affects the brain cleanup, repair, and recovery, while boosting cytotoxicity. Exploring the mechanisms underlying such processes and therapeutic approaches aiming at rectifying the M2 polarization loss are the subjects of this proposal. Our novel findings indicate that in response to ischemia, neurons synthesize and release IL-4 (canonical M2 polarizing cytokine) during the first 3 days of stroke, followed by a decline in both IL-4 and M2 M¿ levels. IL-4-induced M2 M¿ polarization requires the activation of RXR-PPAR? pathway. The administration of IL-4 or agonists of PPAR? and RXR (rectifying factors) for 5 days, starting at 1d post stroke, improves recovery and neuronal re-wiring. Loss of PPAR? in M¿ impedes recovery. Aim 1. Elucidate, in vitro, the role of neurons in M¿ polarization and post stroke repair: IL-4- medaited PPAR?:RXR-executed process involving phagocytosis (cleanup) and trophic stimulation. Hypothesis: Neurons act as sensors of "injury" and generate IL-4/IL13 that signals to microglia to induce M2 polarization, while suppressing M1 phenotype associated with cytotoxicity. Aim 2. Elucidate, in vivo, the basis of IL-4 signaling to PPAR?:RXR, and apply them into clinically relevant approaches targeting the phagocyte-mediated brain cleanup, remodeling, and post- stroke recovery. Hypothesis: Because the initial polarization toward the "healing" M¿ phenotype after stroke, driven by neuronal production of IL4/IL13, is lost within few days after stroke, approaches aiming at restoring IL-4-medaited signaling, such as via recombinant IL-4 and PPAR?:RXR activation (molecular targets of IL-4 in M¿), to rectify M2 polarization loss will assist in post stroke recovery.

描述（由申请人提供）：虽然已知激活的小胶质细胞/巨噬细胞（M <$）有助于中风后的继发性脑损伤，但M <$也有助于修复过程。为了解释这种截然不同的作用，提出了两种M <$表型，“有害”/M1和“愈合”/M2。重要的是，M1 M ²可以被极化为M2，反之亦然。虽然源自中风损伤细胞的各种分子具有使M ²向M1型极化的倾向（导致促炎细胞因子和促氧化剂的产生），但其他分子（例如由T细胞产生），例如IL-4、IL-10或TGF ²，使M ²向M2型极化。M2 M？控制清除过程（吞噬作用介导的有毒和促炎细胞碎片的清除）和营养因子的产生。因此，毒性的来源以及阻碍神经重组的生物和物理障碍被去除，同时提供管理神经元发芽（修复过程）的营养支持。如果没有M2 M ²，治疗是不可能的。虽然中风后不久M1和M2 M？表型共存，但M2表型在2-3天内减弱，使M1型占主导地位。这对大脑的清理、修复和恢复产生不利影响，同时增加细胞毒性。探索这些过程的机制和旨在纠正M2极化损失的治疗方法是本提案的主题。我们的新发现表明，为了响应缺血，神经元在中风的前3天合成并释放IL-4（典型的M2极化细胞因子），随后IL-4和M2 M ²水平下降。IL-4诱导的M2 M <$极化需要激活RXR-PPAR？通路IL-4或PPAR激动剂的管理？和RXR（矫正因子）5天，从中风后第1天开始，改善恢复和神经元重新布线。PPAR丢失？在M中阻碍恢复。目标1.体外阐明神经元在M？极化和卒中后修复中的作用：IL-4介导的PPAR？：RXR执行的过程涉及吞噬（清除）和营养刺激。假设：神经元充当“损伤”的传感器并产生IL-4/IL 13，其向小胶质细胞发出信号以诱导M2极化，同时抑制与细胞毒性相关的M1表型。目标2.阐明体内IL-4信号传导至PPAR？的基础：RXR，并将其应用于针对吞噬细胞介导的脑清除、重塑和卒中后恢复的临床相关方法。假设：由于脑卒中后由神经元产生IL 4/IL 13驱动的向“愈合”M <$表型的初始极化在脑卒中后几天内丧失，旨在恢复IL-4介导的信号传导的方法，例如通过重组IL-4和PPAR？：RXR激活（M中IL-4的分子靶点），纠正M2极化损失，将有助于中风后恢复。