Project description:The repair of white matter damage is of paramount importance for functional recovery after brain injuries.We report that interleukin-4 (IL-4) promotes oligodendrocyte regeneration and remyelination. IL-4 receptor expression was detected in a variety of glial cells after ischemic brain injury, including oligodendrocyte lineage cells. IL-4 deficiency in knockout mice resulted in greater deterioration of white matter over 14 days after stroke. Consistent with these findings, intranasal delivery of IL-4 nanoparticles after stroke improved white matter integrity and attenuated long-term sensorimotor and cognitive deficits in wild-type mice, as revealed by histological immunostaining, electron microscopy, diffusion tensor imaging, and electrophysiology. The selective effect of IL-4 on remyelination was verified in an ex vivo organotypic model of demyelination. By leveraging primary oligodendrocyte progenitor cells (OPCs), microglia-depleted mice, and conditional OPC-specific PPARγ knockout mice, we discovered a direct salutary effect of IL-4 on oligodendrocyte differentiation that was mediated by the PPARγ axis. Our findings reveal a new regenerative role of IL-4 in the CNS, which lies beyond its known immunoregulatory functions on microglia/macrophages or peripheral lymphocytes. Therefore, intranasal IL-4 delivery may represent a novel therapeutic strategy to improve white matter integrity in stroke and other brain injuries.
Project description:Tissue progenitors maintain the integrity of organ systems through aging and stress. The brain’s white matter regions experience ischemic lesions and age-dependent degeneration. Brain white matter contains progenitors, oligodendrocyte precursor cells (OPCs), which can repair some insults. The response of OPCs to white matter ischemia and aging is not known. We characterized the response of OPCs to white matter stroke using OPC reporter mice, cell migration tracking, OPC specific RNA sequencing, and mechanistic studies in candidate biochemical pathways in the aged brain. White matter stroke induces initial proliferation of local OPCs but blocks differentiation, shunting a portion into astrocytes. Candidate signaling pathways for this differentiation block including novel interactions of inhibin and matrilin-2 and new roles of NgR1 ligands following white matter stroke. Stroke induces inhibin expression in astrocytes and downregulates OPC matrilin-2 that contributes into OPC differentiation block. Antagonism of NgR1 ligands promotes OPC differentiation by attenuating the OPC astrocytic transformation and enhances functional recovery from stroke in aged animals.
Project description:Subcortical white matter stroke (WMS) accounts for up to 30% of all stroke events. WMS damages astrocytes, axons, oligodendrocytes, and myelin. We hypothesized that an astrocytic therapy would be ideally suited for brain repair after WMS. We characterized the molecular profile, epigenetic patterns and in vivo tissue repair activity of a novel glial enriched progentior cell differentiated from human induced pluripotent stem cells (hiPSCs). hiPSC-GEPs are derived from hiPSCs with an experimental manipulation of HIF activity by brief treatment with a prolyl hydroxylase inhibitor. This treatment permanently biased these cells toward an immature astrocyte fate. hiPSC-GEPs transplanted into the brain in the subacute period after WMS migrate widely, mature into astrocytes and induced endogenous oligodendrocyte precursor proliferation and re-myelination. hiPSC-GEPs enhanced motor recovery compared to other hiPSC-differentiated cell types. This approach establishes a hiPSC-derived product with easy scale-up capabilities and efficacy in a common and untreatable brain disease.
Project description:The precise mechanisms underlying the salutary effects of regulatory T cells (Tregs) on long-term tissue repair after stroke remain elusive. Here, , we performed RNAseq analysis on sorted CD4+CD25+Foxp3(GFP)+ Tregs from the ischemic brain and blood of DTR stroke mice 14d after surgery and from the blood of sham DTR mice. The unique patterns of gene expression of brain-infiltrating Tregs exhibited a significant enrichment for genes with functions in immunoregulation and cell-cell interactions, especially the activation of phagocytes.
Project description:Oligodendrocyte progenitor cells (OPCs) differentiate to myelin-producing mature oligodendrocytes and enwrap growing or demyelinated axons during development and post central nervous diseases. Failure of remyelination due to cell death or undifferentiation of OPC contributes to severe neurologic deficits and motor dysfunction. However, how to prevent the cell death of OPCs is still poorly understood, especially in hemorrhagic diseases. In this current study, we injected autologous blood into the mouse lateral ventricular to study the hemorrhage induced OPC cell death in vivo. The integrity of the myelin sheath of the corpus callosum was disrupted post intraventricular hemorrhage (IVH) assessed by using magnetic resonance imaging, immunostaining, and transmission electron microscopy. Consistent with the severe demethylation, we observed massive cell death of oligodendrocyte lineages in the periventricular area. In addition, we found that ferroptosis is the major cell death form in Hemin-induced OPC death by using RNA-seq analysis, and the mechanism was glutathione peroxidase 4 (GPx4) expression and activity reduction-resulted lipid peroxide accumulation. Furthermore, inhibition of ferroptosis rescued OPC cell death in vitro, and in vivo attenuated IVH-induced white matter injury and promoted recovery of neurological function. These data demonstrate that ferroptosis is an essential form of OPC cell death in hemorrhagic stroke, and rescuing ferroptotic OPCs could serve as a therapeutic target for stroke and related diseases.
Project description:White matter hyperintensity (WMH) is a pressing global medical issue linked to cognitive decline and stroke risk. Despite its significance, the underlying mechanisms remain unclear. Here, we directly demonstrated in humans that high WMH burden correlated with delayed glymphatic pathway drainage. Additionally, a longitudinal cohort study revealed that glymphatic dysfunction predicted WMH progression. Next, in a rat model of WMH, we confirmed the presence of impaired lymphangiogenesis and glymphatic drainage, followed by elevated microglial activation and white matter demyelination. Notably, enhancing meningeal lymphangiogenesis and glymphatic drainage through adenoviral delivery of Vascular Endothelial Growth Factor-C (VEGF-C) mitigated microglial gliosis and white matter demyelination. Conversely, blocking the growth of meningeal lymphatics with a VEGF-C trap strategy exacerbated these changes. Our findings highlight the role of meningeal lymphatics and glymphatic pathway dysfunction in aggravating brain white matter injury and advancing WMH, providing a potential novel strategy for WMH prevention and treatment.