OPN Enhances Neuroplasticity after Stroke via VEGF Pathway

LIAO Haikang^1,2,3, LIU Weiqin⁴, ZOU Zhenyou¹, YAO Hua^1,3*

（¹Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical College, Guilin 541004, China; ²Key Laboratory of Alzheimer’s Disease of Zhejiang Province, Institute of Aging, Wenzhou Medical University, Wenzhou 325035, China; ³Institute of Neurology and Chemistry, Wenzhou University, Wenzhou 325035, China; ⁴Department of Neurosurgery, Ganzhou City People’s Hospital, Ganzhou 341000, China)

Abstract:

This study aimed to investigate the effect of OPN (osteopontin) on neuroplasticity in the subacute phase of ischemic stroke. A mice model of photochemical embolization was induced, and Western blot was performed to determine the synaptophysin expression at protein levels in the peri-infarct cortex after 2, 7, 14, 21, and 28 days of stroke. The human rOPN (recombinant osteopontin) was locally delivered by stereotactic apparatus after 7 days of stroke. The VgluT 1 (vesicular glutamate transporter 1) and PSD 95 (post synaptic density protein 95) were detected by immunofluorescence staining, to observe the number of colocalized synapses in the periinfarct cortex after OPN treatment. To evaluate the OPN impact on astrocytosis and vascular density, this article stained the GFAP (glial fibrillary acidic protein), IBA1 (ionized calcium-binding adapter molecule 1), and CD31 (platelet endothelial cell adhesion molecule-1) by the immunofluorescence technique. In addition, the underlying mechanism of regulating neural plasticity by OPN was analyzed through the RNA-seq studies. This article indicated that the expression level of synaptophysin in the penumbra was significantly upregulated on the 7th day after stroke, compared with the sham group (P<0.01). Compared with the stroke+saline group, OPN significantly improved neuroplasticity, angiogenesis and astrocytosis in the peri-infarct cortex (P<0.01). Sequencing data revealed that OPN induced the mRNA level of VEGF (vascular endothelial growth factor). Moreover, Western blot confirmed that OPN could significantly upregulate the protein levels of VEGF in the peri-infarct area (P<0.01). In conclusion, this article proved that OPN might induce VEGF expression and play a neural repair role by activating synapse-related proteins, regulating neuroplasticity, increasing angiogenesis and gliosis in the subacute phase of stroke. Therefore, it suggests that OPN may serve as a therapeutic protein to promote neural repair after stroke.

CSTR: 32200.14.cjcb.2022.08.0018