Introduction

Blood-Brain Barrier (BBB) disruption plays a crucial role in devastating malignant brain edema and hemorrhagic transformation after cerebral ischemia-reperfusion. Inhibition of inflammatory response represents a potential treatment for protecting BBB integrity following cerebral ischemia-reperfusion. Our previous study  showed netrin-1 is an important molecule in regulating astrocyte activation and neuroinflammation in cerebral ischemia. However, the effect of NTN-1 on BBB integrity after cerebral ischemia have not been investigated, and little is known about how netrin-1 affects pericyte-microglia interaction in the MCAO brain.

Methods

One hundred and twenty-four male mice were subjected to the model of middle cerebral artery occlusion(MCAO). Recombinant human NTN-1 (rh-NTN-1) was administered intravenously. Post-MCAO evaluations included neurobehavioral function, brain water content, Western blot analysis, and immunohistochemistry.   Our study observed the function of netrin-1 in neuroinflammation , the permeability of BBB and brain injury after middle cerebral artery occlusion.

Results

Our results demonstrated that NTN-1 reduced albumin and Evans blue extravasation compared to that in the vehicle-treated group at 24 hours after tMCAO (p<0.01, Fig. 2D). Gelatin zymography and  western blot showed NTN-1 significantly decreased MMP-9 activity and thereby increased expressions of endothelial junction proteins at 24 hours after MCAO. Moreover, injection of netrin-1 attenuated microglial activation and neutrophil infiltration and the release of interleukins and reduced infarct volume after brain ischemia (p <0.05).  Flow cytometry results showed NTN-1 treatment markedly reduced CD86 + cells and increased CD206+ cells on CD11b+CD45low microglias 24 hours after MCAO. The immunofluorescence staining results showed that the expression of PDGFRB was decreased in tMCAO brain microvessels , but NTN-1 increased the expression of co-localization.

Conclusion

NTN-1 can alleviates blood-brain barrier dysfunction via inhibiting  neuroinflammation after cerebral ischemia-reperfusion injury,which is related to promote micriglia M2 polaration and increase pericyte coverage and il-10 secretion  in pericyte.