BackgroundInflammation plays a key role in the pathophysiology of ischemic stroke. Some proinflammatory mediators, such as cytokines and chemokines, are produced in stroke. Chemokine-like factor 1 (CKLF1), as a novel C-C chemokine, displays chemotactic activities in a wide spectrum of leukocytes and plays an important role in brain development. In previous studies, we have found that the expression of CKLF1 increased in rats after focal cerebral ischemia and treatment with the CKLF1 antagonist C19 peptide decreased the infarct size and water content. However, the role of CKLF1 in stroke is still unclear. The objective of the present study was to ascertain the possible roles and mechanism of CKLF1 in ischemic brain injury by applying anti-CKLF1 antibody.MethodsMale Sprague–Dawley rats were subjected to one-hour middle cerebral artery occlusion. Antibody to CKLF1 was applied to the right cerebral ventricle immediately after reperfusion; infarct volume and neurological score were measured at 24 and 72 hours after cerebral ischemia. RT-PCR, Western blotting and ELISA were utilized to characterize the expression of adhesion molecules, inflammatory factors and MAPK signal pathways. Immunohistochemical staining and myeloperoxidase activity was used to determine the extent of neutrophil infiltration.ResultsTreatment with anti-CKLF1 antibody significantly decreased neurological score and infarct volume in a dose-dependent manner at 24 and 72 hours after cerebral ischemia. Administration with anti-CKLF1 antibody lowered the level of inflammatory factors TNF-α, IL-1β, MIP-2 and IL-8, the expression of adhesion molecules ICAM-1 and VCAM-1 in a dose-dependent manner. The results of immunohistochemical staining and detection of MPO activity indicated that anti-CKLF1 antibody inhibited neutrophil infiltration. Further studies suggested MAPK pathways associated with neutrophil infiltration in cerebral ischemia.ConclusionsSelective inhibition of CKLF1 activity significantly protects against ischemia/reperfusion injury by decreasing production of inflammatory mediators and expression of adhesion molecules, thereby reducing neutrophils recruitment to the ischemic area, possibly via inhibiting MAPK pathways. Therefore, CKLF1 may be a novel target for the treatment of stroke.

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Triptolide (TP) is the major active principle of Tripterygium wilfordii Hook f. and very effective in treatment of autoimmune diseases. However, TP induced hepatotoxicity limited its clinical applications. Our previous study found that TP was a substrate of P-glycoprotein and its hepatobiliary clearance was markedly affected by P-gp modulation in sandwich-cultured rat hepatocytes. In this study, small interfering RNA (siRNA) and specific inhibitor tariquidar were used to investigate the impact of P-gp down regulation on TP-induced hepatotoxicity. The results showed that when the function of P-gp was inhibited by mdr1a-1 siRNA or tariquidar, the systemic and hepatic exposures of TP were significantly increased. The aggravated hepatotoxicity was evidenced with the remarkably lifted levels of serum biomarkers (ALT and AST) and pathological changes in liver. The other toxicological indicators (MDA, SOD and Bcl-2/Bax) were also significantly changed by P-gp inhibition. The data analysis showed that the increase of TP exposure in mice was quantitatively correlated to the enhanced hepatotoxicity, and the hepatic exposure was more relevant to the toxicity. P-gp mediated clearance played a significant role in TP detoxification. The risk of herb-drug interaction likely occurs when TP is concomitant with P-gp inhibitors or substrates in clinic.

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Tissue-type plasminogen activator (t-PA) remains the only approved therapy for acute ischemic stroke but has a restrictive treatment time window of 4.5 hr. Prolonged ischemia causes blood-brain barrier (BBB) damage and increases the incidence of hemorrhagic transformation (HT) secondary to reperfusion. In this study, we sought to determine the effect of pinocembrin (PCB; a pleiotropic neuroprotective agent) on t-PA administration-induced BBB damage in a novel rat thromboembolic stroke model. By assessing the leakage of Evans blue into the ischemic hemisphere, we demonstrated that PCB pretreatment 5 min before t-PA administration significantly reduced BBB damage following 2 hr, 4 hr, 6 hr, and even 8 hr ischemia. Consistently, PCB pretreatment significantly decreased t-PA infusion-resulting brain edema and infarction volume and improved the behavioral outcomes following 6 hr ischemia. Mechanistically, PCB pretreatment inhibited the activation of MMP-2 and MMP-9 and degradation of tight junction proteins (TJPs) occludin and claudin-5 in the ischemic hemisphere. Moreover, PCB pretreatment significantly reduced phosphorylation of platelet-derived growth factor receptor α (PDGFRα) as compared with t-PA alone. In an in vitro BBB model, PCB decreased transendothelial permeability upon hypoxia/aglycemia through inhibiting PDGF-CC secretion. In conclusion, we demonstrated that PCB pretreatment shortly before t-PA infusion significantly protects BBB function and improves neurological outcomes following prolonged ischemia beyond the regular 4.5 hr t-PA time window. PCB pretreatment may represent a novel means of increasing the safety and the therapeutic time window of t-PA following ischemic stroke.