Treatment of secondary injury after ischemic stroke through targeting microglia

描述（由申请人提供）：虽然已知活化的小胶质细胞/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角色，人们提出了两种M¿表型，“有害”/M1和“愈合”/M2。重要的是，M1 M¿可以极化到M2，反之亦然。虽然来自中风损伤细胞的各种分子有使M¿向M1型极化的倾向（引起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），如IL-4、IL10或TGF¿，使M¿向M2型极化。M2 M¿控制清理过程（吞噬-介导的毒性和促炎细胞碎片的清除），以及营养因子的产生。因此，毒性来源和阻碍神经重组的生物和物理障碍被清除，同时为神经元发芽（修复过程）提供营养支持。如果没有M2 - M -¿，治愈是不可能的。虽然M1和M2 M型在中风后不久共存，但M2型在2-3天内减弱，使M1型占主导地位。这会对大脑的清理、修复和恢复产生不利影响，同时增加细胞毒性。探索这些过程背后的机制和旨在纠正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，在缺血的反应中，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¿水平下降。il -4诱导的M2 M¿极化需要激活RXR-PPAR？途径。给药是IL-4还是PPAR激动剂？和RXR（整流因子）5天，从中风后1d开始，改善恢复和神经元重新布线。PPAR损失？这阻碍了复苏。目的1。阐明，在体外，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，包括吞噬（清除）和营养刺激。假设：神经元作为“损伤”的传感器，产生IL-4/IL13信号给小胶质细胞诱导M2极化，同时抑制与细胞毒性相关的M1表型。目标2。在体内阐明IL-4信号传导到PPAR的基础？并将其应用于针对吞噬细胞介导的脑清理、重塑和脑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“愈合”M -表现型的初始极化在脑卒中后几天内消失，旨在恢复IL-4介导的信号传导的方法，如通过重组IL-4和PPAR？：激活RXR （IL-4在M¿中的分子靶点），纠正M2极化损失，有助于脑卒中后恢复。

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.