Abstract
The loss of tight junction (TJ) and adherens junction (AJ) proteins leads to the damage of the blood-brain barrier (BBB) during cerebral ischemia. Inhibition of cyclic nucleotide phosphodiesterase 4 (PDE4) by roflumilast (Roflu) protects against ischemic stroke-induced neuronal damage. However, the effects of Roflu on vascular endothelial injury and BBB integrity remain unknown. Here, we investigated whether and how Roflu protects against cerebrovascular endothelial injury caused by cerebral ischemia/reperfusion. We demonstrated that PDE4B knocking-down increased the expression of TJ and AJ proteins in human brain microvascular endothelial cells (HBMECs) subjected to oxygen-glucose deprivation reperfusion (OGD/R). Inhibition of PDE4 by Roflu (1.0 μM) showed similar effects as PDE4B knocking-down. We then found that Roflu activated Notch1/Hairy and enhancer of split 1 (Hes1) signaling. Consistently, the effects of Roflu on TJ and AJ proteins were reversed by the γ-secretase inhibitor DAPT or Hes1 knocking-down. Furthermore, Roflu (1.0 mg/kg) improved neurobehavioral outcomes and ameliorated BBB disruption in rats following ischemic stroke. Roflu also increased the levels of TJ proteins and AJ proteins in vivo. Collectively, these data suggest that Roflu is a promising compound for the prevention of BBB damage. The protective effects of Roflu are mediated through activation of the Notch1/Hes1 pathway.
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