Elevated Expression of VEGF-C and Its Receptors, VEGFR-2 and VEGFR-3, in Patients with Mesial Temporal Lobe Epilepsy

Mesial temporal lobe epilepsy (MTLE) is a frequent form of focal intractable epilepsy in adults. We previously reported overexpression of vascular endothelial growth factor C (VEGF-C) and its receptors, VEGFR-2 and VEGFR-3, in epilepsy-associated tuberous sclerosis complex. To identify whether VEGF-C and its receptors are involved in epileptogenesis of MTLE, we investigated the levels and expression pattern of VEGF-C and its receptors in temporal neocortex and hippocampus (HPC) from 28 patients with MTLE and ten control (CTX) subjects. Real-time quantitative polymerase chain reaction and Western blotting results revealed upregulated mRNA and immunoreactive protein levels of VEGF-C, VEGFR-2, and VEGFR-3 in the MTLE group compared to the control groups. Immunohistochemistry and double-labeled immunofluorescence showed that VEGF-C was highly expressed in neurons and astrocytes, including reactive astrocytes and vascular endothelial cells, VEGFR-2 was expressed at a high level in reactive astrocytes and vascular endothelial cells, but not in neurons, whereas VEGFR-3 was only overexpressed in reactive astrocytes. Taken together, these findings suggest that VEGF-C and its receptors, VEGFR-2 and VEGFR-3, may contribute to the epileptogenesis of MTLE.