Thrombopoietin could protect cerebral tissue against ischemia-reperfusion injury by suppressing NF-κB and MMP-9 expression in rats

Objective: To determine the neuroprotective effects and underpinning mechanisms of thrombopoietin (TPO), Matrix Metalloproteinase-9(MMP-9) and Nuclear Factor-κB (NF-κB) after focal cerebral ischemia-reperfusion in rats. Methods: Male rats underwent 2 hours of right middle cerebral artery occlusion (MCAO) followed by 22 hours of reperfusion. PBS or TPO (0.1ug/kg) was administered from caudal vein before reperfusion. Neurologic deficits, brain edema, Evans blue (EB) extravasation, NF-κB and MMP-9 expression were subsequently examined. Results: Ischemia-reperfusion injury produced a large area of edema. TPO significantly reduced edema and alleviated neurologic deficits after ischemia-reperfusion. Ischemia-induced increases of NF-κB, MMP-9 and Evans blue extravasation were reduced by TPO intervention. Conclusion: TPO improved neurological function and ameliorated brain edema after stroke, partly by reducing the ischemia-induced increase of NF-κB and MMP-9.

Green tea polyphenols affect invasiveness of human gastric MKN-28 cells by inhibition of LPS or TNF-α induced Matrix Metalloproteinase-9/2

Several studies demonstrated a correlation between green tea consumption and a reduced cancer risk. Among different components, green tea polyphenols have been identified as molecules responsible for the beneficial effects showed by the green tea against oxidative stress and cell invasiveness. In this study, we investigated the effects of green tea polyphenol extracts (GTPs) in human gastric MKN-28 cell line. To this aim, we have first evaluated the effect of GTPs on oxidative stress induced cell injury. The pre-treatment with 10^-4 M catechin equivalents of GTPs exerts a protective effect on xanthine-xanthine oxidase induced cell cytotoxicity, thus confirming the anti-oxidant properties of GTPs. The effect of GTPs was also extended to the invasive ability of MKN-28 cells stimulated with TNF-α or LPS, as pro-inflammatory factors. Migration and matrigel invasion assays demonstrated that GTPs exposure (10^-6 M) prevents the increase in cell invasiveness induced by TNF-α or LPS. Finally, we have analyzed the effect of GTPs on the levels of Matrix Metalloproteinases (MMP)-9/2, whose expression is up-regulated by TNF-α or LPS. Our results indicated that the pre-treatment with GTPs was able to reduce MMP-9/2 expression at both protein and enzyme activity levels in the conditioned media of TNF-α or LPS stimulated MKN-28 cells. In conclusion, our results demonstrated that green tea polyphenol extract reduces the invasiveness of gastric MKN-28 cancer cells through the reduction of TNF-α or LPS induced MMP-9/2 up-regulation. Therefore, these data support the hypothesis that GTPs could exert a protective role against the metastatic process in gastric cancer.