Increased Expression and Cellular Localization of P2X7R in Cortical Lesions of Patients With Focal Cortical Dysplasia

J Neuropathol Exp Neurol. 2016 Jan;75(1):61-8. doi: 10.1093/jnen/nlv003.

Abstract

Focal cortical dysplasias (FCDs) are major brain malformations that commonly lead to medically intractable epilepsy. The purinergic ionotropic P2X7 receptor (P2X7R) is an atypical P2X subtype that gates calcium and sodium ions. Previous animal studies have suggested that P2X7R is a contributing factor in epileptogenesis. This study aimed to define the distribution and expression of P2X7R in 35 FCD patient-surgical-resection specimens relative to autopsy control samples (n = 8). Immunohistochemical colocalization assays revealed that P2X7R was primarily expressed in neurons, astrocytes, and microglia. In FCD samples, P2X7R protein levels were increased in abnormal cell types such as dysmorphic neurons and balloon cells, which are characteristic of FCD. By real-time PCR and Western blotting, P2X7R mRNA and protein expression levels were elevated in FCD patient samples vs control samples; P2X7R expression was also higher in FCDII vs FCDIa patient samples. Because interleukin-1β is a downstream factor of the P2X7R signaling pathway, we determined that there was also moderate-to-strong interleukin-1β expression in the dysmorphic neurons, balloon cells, and microglia in FCD patient lesions. These results indicate that increasing P2X7R levels may contribute to the pathogenesis of human FCD and that P2X7R represents a potential anti-epileptogenic target.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Cerebral Cortex / chemistry*
  • Cerebral Cortex / metabolism*
  • Cerebral Cortex / pathology
  • Child
  • Child, Preschool
  • Female
  • Gene Expression Regulation
  • Humans
  • Infant
  • Male
  • Malformations of Cortical Development / diagnosis
  • Malformations of Cortical Development / genetics
  • Malformations of Cortical Development / metabolism*
  • Receptors, Purinergic P2X7 / analysis*
  • Receptors, Purinergic P2X7 / biosynthesis*
  • Receptors, Purinergic P2X7 / genetics
  • Young Adult

Substances

  • P2RX7 protein, human
  • Receptors, Purinergic P2X7