Abstract
Hemorrhagic transformation (HT) is a serious complication that stimulates inflammation during reperfusion therapy after acute ischemic stroke. Rosuvastatin, a 3-hydroxymethyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, might improve the outcome of HT by inhibiting neuroinflammation. This study aimed to explore the protective effects of rosuvastatin against HT after recombinant tissue plasminogen activator (rt-PA) treatment in mice with experimental stroke via the attenuation of inflammation. A total of one hundred sixty-nine male BALB/c mice were used in the experiment. HT was successfully established in 70 mice that were subjected to 3 h of middle cerebral artery occlusion (MCAO) followed by a 10 mg/kg rt-PA injection over 10 min and reperfusion for 24 h. The mice were then administered rosuvastatin (1 mg/kg, 5 mg/kg) or saline (vehicle). The brain water content and neurological deficits (wire hang and adhesive removal somatosensory tests) were assessed at 24 h after rt-PA reperfusion following MCAO surgery. The morphology, blood-brain barrier (BBB) permeability and number of astrocytes and microglia were assessed by immunohistochemistry, electron microscopy and western blotting at 24 h after rt-PA reperfusion following MCAO surgery. Rosuvastatin protected against impaired neurological function and reversed the BBB leakage observed in the HT group. The increased activation of astrocytes and microglia and secretion of inflammatory factors caused by HT damage were significantly attenuated by high-dose rosuvastatin treatment vs. normal-dose rosuvastatin treatment. Related inflammatory pathways, such as the nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, were downregulated in the rosuvastatin-treated groups compared with the HT group. In conclusion, our results indicate that rosuvastatin is a promising therapeutic agent for HT after rt-PA reperfusion following MCAO surgery in mice, as it attenuates neuroinflammation. Additionally, high-dose rosuvastatin treatment could have a greater anti-inflammatory effect on HT than normal-dose rosuvastatin treatment.
Highlights
MATERIALS AND METHODSHemorrhagic transformation (HT) is a serious complication that occurs after acute ischemic stroke (Álvarez-Sabin et al, 2013; Wang et al, 2015)
In addition to blood leakage due to disruption of the blood-brain barrier (BBB), which significantly upregulates the activation of microglia/macrophages (Khatri et al, 2012; Ozkul-Wermester et al, 2014) and astrocytes, the elevated expression of the proinflammatory cytokines IL-1β and IL-6, the activation of their transcription factor NF-κB, and the expression of the inflammatory enzymes cyclooxygenase 2 (Cox-2) and inducible nitric oxide synthase (iNOS) are considered the chief mechanisms underlying HT
TNF-α, Cox-2, iNOS, IL-1β and IL-6 levels are ameliorated by NF-κB inactivation, and the numbers of microglia and astrocytes are decreased in rosuvastatin-treated mice
Summary
Hemorrhagic transformation (HT) is a serious complication that occurs after acute ischemic stroke (Álvarez-Sabin et al, 2013; Wang et al, 2015). Increasing studies in the literature have shown that inflammation related to the interaction between microglia and astrocytes but not astrocytes alone contributes to ischemia-induced HT and oedema (del Zoppo et al, 2012). In vivo studies have shown that statins induce time- and concentration-dependent reductions in Aβ production, and the reduced production of Aβ has been attributed to reductions in neuroinflammation (Hosaka et al, 2013). One study has suggested that reduced chronic neuroinflammation might be a key mechanism underlying statin-induced neuroprotection (McFarland et al, 2014). Whether statins protect against HT and the related mechanisms in mice have not been determined
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