Astrocytic cytochrome P450 4A/20-hydroxyeicosatetraenoic acid contributes to angiogenesis in the experimental ischemic stroke.

ABSTRACT

20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450 4A (CYP4A) metabolite of arachidonic acid, is one of the primary eicosanoids in most of microcirculatory beds. Studies have indicated that 20-HETE has important functions in the modulation of vascular tone, ion transport, inflammation reaction, and cellular proliferation. Both we and others have demonstrated that 20-HETE plays an important role in acute phase of ischemic stroke. However, little is known about the effect of 20-HETE on recovery phase of stroke. Crosstalk between the cells within the neurovascular unit is increasingly suspected of playing critical roles in stroke recovery. We found that CYP4A is upregulated in astrocytes exposed to oxygen-glucose deprivation (OGD), which increases the production of 20-HETE that promotes endothelial cell proliferation, tube formation and migration. siRNA suppression of CYP4A or 20-HETE inhibitor prevents this effect. In a mouse model of transient focal cerebral ischemia, inhibition of CYP4A reduces peri-infact angiogenesis and worsens neurological deficits 14 days after stroke. We further showed that ischemia injury increases VEGF and HIF-1α expression in cell cultures and ischemic brains, which is negated by a 20-HETE inhibitor-HET0016. Lastly, we showed that JNK signaling pathway is a component of 20-HETE regulated ischemic angiogenesis after stroke. Taken together, we demonstrated a positive influence of 20-HETE in angiogenesis in later stage of stroke. These molecular and in vivo findings also support a previously undescribed mechanism of crosstalk between reactive astrocytes and endothelial cells wherein 20-HETE promotes neurovascular remodeling and functional recovery after ischemic stroke.