Endothelial CD36 Contributes to Postischemic Brain Injury by Promoting Neutrophil Activation via CSF3

Abstract

The scavenger receptor CD36 is a critical factor initiating ischemic brain injury, but the cell type(s) expressing CD36 and responsible for its harmful effects remain unknown. Using bone marrow (BM) chimeras subjected to transient middle cerebral artery occlusion, we found that CD36 Ϫ/Ϫ mice transplanted with wild-type ( ¡CD36Ϫ/Ϫ mice was attenuated. Surprisingly, however, in WT¡CD36 Ϫ/Ϫ mice, in which infarcts were small, neutrophil infiltration was large and similar to that of CD36 Ϫ/Ϫ ¡WT mice, in which infarcts were not reduced. Postischemic neutrophil free radical production was attenuated in WT¡CD36 Ϫ/Ϫ mice compared with CD36 Ϫ/Ϫ ¡WT mice, whereas expression of the neutrophil activator colonystimulating factor 3 (CSF3) was suppressed in CD36 Ϫ/Ϫ cerebral endothelial cells, but not microglia. In CD36 Ϫ/Ϫ cerebral endothelial cultures exposed to extracts from stroke brains, the upregulation of CSF3, but not neutrophil attractant chemokines, was suppressed. Intracerebroventricular administration of CSF3, 24 h after stroke, reconstituted neutrophil radical production and increased infarct volume in WT¡CD36 Ϫ/Ϫ mice. The findings identify endothelial cells as a key player in the deleterious effects of CD36 in stroke, and unveil a novel role of endothelial CD36 in enabling neutrophil neurotoxicity through CSF3.

Perivascular macrophages mediate the neurovascular and cognitive dysfunction associated with hypertension

“…Mice were transcardially perfused under deep anesthesia with 30 ml of heparinized saline to remove blood cells, as described previously (65). Briefly, cerebral hemispheres were gently triturated in HEPES-HBSS buffer and then digested with 62.5 μg/ml Liberase DH (Roche Diagnostics) and 50 U/ml DNase I (Worthington Biochemical).…”

“…Erythrolysis was performed as described above, and afterward blood leukocytes were resuspended in buffer. Isolated brain cells and blood leukocytes were stained at 4°C with predetermined optimal concentrations of antibodies for 20 minutes and analyzed on an Accuri C6 flow cytometer (BD Biosciences) (65). For intracellular staining of CD206, cells were stained for surface markers, fixed and permeabilized using fixation and permeabilization buffers from eBioscience following the manufacturer's instructions.…”

Brain Perivascular Macrophages Initiate the Neurovascular Dysfunction of Alzheimer Aβ Peptides

“…Procedures for BM transplant have been previously described 34, 43 and are only summarized. Whole-body irradiation was performed in 7 weeks-old mice (Nordion Gammacell 40 Exactor).…”

Cell Surface CD36 Protein in Monocyte/Macrophage Contributes to Phagocytosis during the Resolution Phase of Ischemic Stroke in Mice

“…Genetic deletion and pharmacological intervention studies * This work was supported by National Institutes of Health Grants have shown that CD36 contributes to acute ischemic brain injury (18,19), apparently mediated by CD36 expressed in endothelial cells (20). On the other hand, hemorrhagic and neonatal stroke studies showed a beneficial side of CD36 through enhancing phagocytic function (21)(22)(23).…”