Trained immunity induced by high salt diet impedes stroke recovery
Ontology highlight
ABSTRACT: High salt diet-induced functional adaptions in bone marrow progenitor cells, which subsequently reduced monocyte-derived macrophage reparative phenotype and impeded stroke recovery
Project description:A high-salt diet (HSD) elicits sustained sterile inflammation and worsens tissue injury. However, how this occurs after stroke, a leading cause of morbidity and mortality, remains unknown. Here, we report that HSD impairs long-term brain recovery after intracerebral hemorrhage, a severe form of stroke, despite salt withdrawal prior to the injury. Mechanistically, HSD induces innate immune priming and training in hematopoietic stem and progenitor cells (HSPCs) by downregulation of NR4a family and mitochondrial oxidative phosphorylation. This training compromises alternative activation of monocyte-derived macrophages (MDMs) without altering the initial inflammatory responses of the stroke brain. Healthy mice transplanted with bone marrow from HSD-fed mice retain signatures of reduced MDM reparative functions, further confirming a persistent form of innate immune memory that originates in the bone marrow. Loss of NR4a1 in macrophages recapitulates HSD-induced negative impacts on stroke outcomes while gain of NR4a1 enables stroke recovery in HSD animals. Together, we provide the first evidence that links HSD-induced innate immune memory to the acquisition of persistent dysregulated inflammatory responses and unveils NR4a1 as a potential therapeutic target.
Project description:A high-salt diet (HSD) elicits sustained sterile inflammation and worsens tissue injury. However, how this occurs after stroke, a leading cause of morbidity and mortality, remains unknown. Here, we report that HSD impairs long-term brain recovery after intracerebral hemorrhage, a severe form of stroke, despite salt withdrawal prior to the injury. Mechanistically, HSD induces innate immune priming and training in hematopoietic stem and progenitor cells (HSPCs) by downregulation of NR4a family and mitochondrial oxidative phosphorylation. This training compromises alternative activation of monocyte-derived macrophages (MDMs) without altering the initial inflammatory responses of the stroke brain. Healthy mice transplanted with bone marrow from HSD-fed mice retain signatures of reduced MDM reparative functions, further confirming a persistent form of innate immune memory that originates in the bone marrow. Loss of NR4a1 in macrophages recapitulates HSD-induced negative impacts on stroke outcomes while gain of NR4a1 enables stroke recovery in HSD animals. Together, we provide the first evidence that links HSD-induced innate immune memory to the acquisition of persistent dysregulated inflammatory responses and unveils NR4a1 as a potential therapeutic target.
Project description:Ischemic stroke recovery involves dynamic interactions between the central nervous system and infiltrating immune cells. Peripheral immune cells compete with resident microglia for spatial niches in the brain, but how modulating this balance affects recovery remains unclear. Here, we use PLX5622 to create spatial niches for peripheral immune cells, altering the competition between infiltrating immune cells and resident microglia in male mice following transient middle cerebral artery occlusion (tMCAO). We find that early-phase microglia attenuation promotes long-term functional recovery. This intervention amplifies a subset of monocyte-derived macrophages (RAMf) with reparative properties, characterized by high expression of GPNMB and CD63, enhanced lipid metabolism, and pro-angiogenic activity. Transplantation of RAMf into stroke-affected mice improves white matter integrity and vascular repair. We identify Mafb as the transcription factor regulating the reparative phenotype of RAMf. These findings highlight strategies to optimize immune cell dynamics for post-stroke rehabilitation.
Project description:Ischemic stroke recovery involves dynamic interactions between the central nervous system and infiltrating immune cells. Peripheral immune cells compete with resident microglia for spatial niches in the brain, but how modulating this balance affects recovery remains unclear. Here, we use PLX5622 to create spatial niches for peripheral immune cells, altering the competition between infiltrating immune cells and resident microglia in male mice following transient middle cerebral artery occlusion (tMCAO). We find that early-phase microglia attenuation promotes long-term functional recovery. This intervention amplifies a subset of monocyte-derived macrophages (RAMf) with reparative properties, characterized by high expression of GPNMB and CD63, enhanced lipid metabolism, and pro-angiogenic activity. Transplantation of RAMf into stroke-affected mice improves white matter integrity and vascular repair. We identify Mafb as the transcription factor regulating the reparative phenotype of RAMf. These findings highlight strategies to optimize immune cell dynamics for post-stroke rehabilitation.
Project description:To date, miRNA expression studies on cerebral ischemia in both human and animal models have focused mainly on acute phase of ischemic stroke. In this study, we present the roles played by microRNAs in the spontaneous recovery phases in cerebral ischemia using rodent stroke models. In this study presented here, Middle Cerebral Artery Occlusion stroke model was established by using embolus and the brain samples of stroke model were harvested at 0hrs, 3hrs, 6hrs, 12hrs, 24hrs, 48hrs, 72hrs, 120hrs and 168hrs. RNAs were extracted from these samples and microRNA array and mRNA array were performed.
Project description:To date, miRNA and mRNA expression studies on cerebral ischemia in both human and animal models have focused mainly on acute phase of ischemic stroke. In this study, we present the roles played by microRNAs in the spontaneous recovery phases in cerebral ischemia using rodent stroke models. In this study presented here, Middle Cerebral Artery Occlusion stroke model was established by using embolus and the brain samples of stroke model were harvestd at 0hrs, 3hrs, 6hrs, 12hrs, 24hrs, 48hrs, 72hrs, 120hrs and 168hrs. RNAs were extracted from these samples and microRNA array and mRNA array were performed.
Project description:To date, miRNA expression studies on cerebral ischemia in both human and animal models have focused mainly on acute phase of ischemic stroke. In this study, we present the roles played by microRNAs in the spontaneous recovery phases in cerebral ischemia using rodent stroke models.
Project description:To date, miRNA and mRNA expression studies on cerebral ischemia in both human and animal models have focused mainly on acute phase of ischemic stroke. In this study, we present the roles played by microRNAs in the spontaneous recovery phases in cerebral ischemia using rodent stroke models.
Project description:Stroke causes death of brain tissue leading to long-term deficits. Behavioral evidence from neurorehabilitative therapies suggest learning-induced neuroplasticity can lead to beneficial outcomes. However, molecular and cellular mechanisms that link learning and stroke recovery are unknown. We show that in mouse models of stroke, with enhanced recovery of function from genetic perturbations of learning and memory genes, express activity-dependent transcriptional programs that are normally active during formation or storage of new memories. The expression of neuronal activity-dependent genes are predictive of recovery and occupy a molecular latent space unique to motor recovery. With motor recovery, networks of activity-dependent genes are co-expressed with their transcription factor targets forming gene regulatory networks that support activity-dependent transcription, that are normally diminished after stroke. Neuronal activity-dependent changes at the circuit level are influenced by interactions with microglia. At the molecular level, we show that enrichment of activity-dependent programs in neurons lead to transcriptional changes in microglia where they differentially interact to support intercellular signaling pathways for axon guidance, growth and synaptogenesis. Together, these studies identify activity-dependent transcriptional programs as a fundamental mechanism for neural repair post-stroke.