Epileptic seizures increase circulating endothelial cells in peripheral blood as early indicators of cerebral vascular damage

Abstract

Circulating endothelial cells (CECs) are nonhematopoetic mononuclear cells in peripheral blood that are dislodged from injured vessels during cardiovascular disease, systemic vascular disease, and inflammation. Their occurrence during cerebrovascular insults has not been previously described. Epileptic seizures cause the long-term loss of cerebrovascular endothelial dilator function. We hypothesized that seizures cause endothelial sloughing from cerebral vessels and the appearance of brain-derived CECs (BCECs), possible early indicators of cerebral vascular damage. Epileptic seizures were induced by bicuculline in newborn pigs; venous blood was then sampled during a 4-h period. CECs were identified in the fraction of peripheral blood mononuclear cells by the expression of endothelial antigens (CD146, CD31, and endothelial nitric oxide synthase) and by Ulex europeaus lectin binding. In control animals, few CECs were detected. Seizures caused a time-dependent increase in CECs 2-4 h after seizure onset. Seizure-induced CECs coexpress glucose transporter-1, a blood-brain barrier-specific glucose transporter, indicating that these cells originate in the brain vasculature and are thus BCECs. Seizure-induced BCECs cultured in EC media exhibited low proliferative potential and abnormal cell contacts. BCEC appearance during seizures was blocked by a CO-releasing molecule (CORM-A1) or cobalt protoporphyrin (heme oxygenase-1 inducer), which prevented apoptosis in cerebral arterioles and the loss of cerebral vascular endothelial function during the late postictal period. These findings suggest that seizure-induced BCECs are injured ECs dislodged from cerebral microvessels during seizures. The correlation between the appearance of BCECs in peripheral blood, apoptosis in cerebral vessels, and the loss of postictal cerebral vascular function suggests that BCECs are early indicators of late cerebral vascular damage.

CORM-A1 prevents blood-brain barrier dysfunction caused by ionotropic glutamate receptor-mediated endothelial oxidative stress and apoptosis

“…Glutamatergic epileptic seizures cause oxidative stress and long-term loss of endothelial vasodilator function in the cerebral circulation of newborn piglets (21,35,46). We investigated the mechanisms and functional consequences of glutamate-induced oxidative stress and apoptosis in cerebral vascular endothelium.…”

“…CMVEC detached from the extracellular matrix following a 3-h exposure to TNF-␣, glutamate, or iGluR agonists have little ability to reattach and grow after reseeding (data not shown), indicating that these cells are irreversibly damaged. This mechanism may account for the appearance of circulating endothelial cells of brain origin in the peripheral blood of newborn piglets during glutamatergic epileptic seizures (35). Brain-derived circulating endothelial cells that appear 2-4 h after onset of seizures are early indicators of cerebral vascular damage and loss of endothelium-mediated vasodilator functions (35).…”

“…This mechanism may account for the appearance of circulating endothelial cells of brain origin in the peripheral blood of newborn piglets during glutamatergic epileptic seizures (35). Brain-derived circulating endothelial cells that appear 2-4 h after onset of seizures are early indicators of cerebral vascular damage and loss of endothelium-mediated vasodilator functions (35).…”

“…A CO-releasing molecule, CORM-A1, exhibits strong antioxidant and antiapoptotic properties against cerebrovascular endothelial damage caused by seizures in newborn pigs (35,46). We have now used CORM-A1 (50 M) to model the cytoprotective effect of gaseous CO in the in vitro model of cerebral vascular endothelial injury.…”

“…In the cerebral circulation of newborn pigs in vivo, CO delivered in a pharmacologically active form as a CO-releasing molecule, CORM-A1, reduced oxidative stress and prevented loss of cerebral vascular dilator function caused by glutamatergic seizures (35,37,46). Furthermore, CORM-A1 prevented the appearance of brain-derived circulating endothelial cells in peripheral blood as early indicators of cerebral vascular endothelial damage caused by seizures (35).…”