Role of enteric glial cells in inflammatory bowel disease

Enteric glial cells (EGCs) represent an extensive but relatively poorly described cell population within the gastrointestinal tract. Accumulating data suggest that EGCs represent the morphological and functional equivalent of CNS astrocytes within the enteric nervous system (ENS). The EGC network has trophic and protective functions toward enteric neurons and is fully implicated in the integration and the modulation of neuronal activities. Moreover, EGCs seem to be active elements of the ENS during intestinal inflammatory and immune responses, sharing with astrocytes the ability to act as antigen-presenting cells and interacting with the mucosal immune system via the expression of cytokines and cytokine receptors. Transgenic mouse systems have demonstrated that specific ablation of EGC by chemical ablation or autoimmune T-cell targeting induces an intestinal pathology that shows similarities to the early intestinal immunopathology of Crohn's disease. EGCs may also share with astrocytes the ability to regulate tissue integrity, thereby postulating that similar interactions to those observed for the blood-brain barrier may also be partly responsible for regulating mucosal and vascular permeability in the gastrointestinal tract. Disruption of the EGC network in Crohn's disease patients may represent one possible cause for the enhanced mucosal permeability state and vascular dysfunction that are thought to favor mucosal inflammation.