基于JAK2/STAT1信号通路探讨骨桥蛋白缓解高血糖大鼠脑出血后炎症反应机制

To investigate the mechanism of osteopontin alleviating inflammatory response after cerebral hemorrhage in hyperglycemia rats based on JAK2/STAT1 signaling pathway

Objective To investigate the mechanism of osteopontin(OPN)alleviating inflammatory response after hyperglycemia ICH in rats based on the JAK2/STAT1 signaling pathway.Methods Intracerebral hemorrhage rat model was established by collagenase injection. Acute cerebral hematoma dilation was induced by intraperitoneal injection of 50% glucose 3 h after ICH. Recombinant osteopotin(rOPN)was administered intranasally 1 h after ICH. Brain water content(BWC), neurological deficit, Western blot and immunohistochemistry were used to evaluate the occurrence and development of brain injury. The molecular mechanisms and pathways of integrin β1 siRNA and JAK2 agonist C-A1 were studied.Results OPN expression was significantly decreased at 24 h after ICH, and then continued to increase at 48-72 h. Integrin β1 also showed the similar expression pattern. In addition, the ratios of p-JAK2/JAK2 and p-STAT1/STAT1 were significantly increased 24 h after ICH. Low doses of OPN had no effect on brain water content(BWC), while both medium and high doses of OPN could significantly inhibit ICH induced BMC increasion. Behavioral scores showed improvement of neurological function, but there was no significant difference between high and medium doses of OPN. OPN attenuated the increase of BWC and improved the neurologic dysfunction induced by ICH. The expression of OPN in brain tissue was increased by medium dose(3 μg)and high dose(9 μg)rOPN treatment, accompanied by the increase of integrin β1 expression. ICH induced the increase of p-JAK2/JAK2 and p-STAT1/STAT1 ratios, while the increase of OPN was accompanied by the decrease of p-JAK2/JAK2 and p-STAT1/STAT1 ratios. ICH induced excessive production of TNF-a and IL-1β, accompanied by activation of MMP-9, while rOPN-induced inhibition of the JAK2/STAT1 pathway resulted in decreased production of TNF-a and IL-1β, leading to a dose-dependent reduction of ICH-induced MMP-9 overexpression. In addition, immunohistochemistry staining of neutrophil specific protein MPO and Western blotting assessment showed that rOPN reduced neutrophil infiltration after ICH. The effect of OPN was reversed by the intervention of integrin β1 siRNA and C-A1 on the JAK2/STAT1 signaling pathway.Conclusion rOPN alleviated the inflammatory response after ICH in hyperglycemic rats, alleviated brain edema and improved neurological function. The effect of rOPN is mediated by the inhibition of the JAK2/STAT1 signaling pathway induced by integrin β1.