Novel functional roles for enteric glia in the gastrointestinal tract

Abstract

Enteric glia are a unique class of peripheral glial cells within the gastrointestinal tract. Major populations of enteric glia are found in enteric ganglia in the myenteric and submucosal plexuses of the enteric nervous system (ENS); these cells are also found outside of the ENS, within the circular muscle and in the lamina propria of the mucosa. These different populations of cells probably represent unique classes of glial cells with differing functions. In the past few years, enteric glia have been found to be involved in almost every gut function including motility, mucosal secretion and host defence. Subepithelial glia seem to have a trophic and supporting relationship with intestinal epithelial cells, but the necessity of these roles in the maintenance of normal epithelial functions remains to be shown. Likewise, glia within enteric ganglia are activated by synaptic stimulation, suggesting an active role in synaptic transmission, but the precise role of glial activation in normal enteric network activity is unclear. Excitingly, enteric glia can also give rise to new neurons, but seemingly only under limited circumstances. In this Review, we discuss the current body of evidence supporting functional roles of enteric glia and identify key gaps in our understanding of the physiology of these unique cells.

Clostridium difficile-related postinfectious IBS: a case of enteroglial microbiological stalking and/or the solution of a conundrum?

“…The important role of EGC, besides mechanical/trophic support function [27], involves regulation of gut barrier functions [28], maintenance and modulation of enteric neurotransmission [29], enteric neurons homeostasis [30], and acting as mediators of interactions between the enteric nervous system and the immune system [25,31]. These functions are particularly interesting in the setting of PI-IBS, in that there are emerging data that immune-mediated barrier defects are found in IBS patients [32,33].…”

“…To exert this role, EGC strongly interact with the enteric neurons and neurotransmitters [27,29]. Most EGC within enteric ganglia are contacted by vesiculated nerve processes with presynaptic specializations [35], and respond to transmitters released by these terminations by expressing a series of receptors for neurotransmitters and neuromodulators [36][37][38][39].…”

Le système nerveux entérique et l’unité neuro-glio-épithéliale digestive

“…Le SNE est constitué de deux types cellulaires particuliers : les neurones et les cellules gliales entériques (CGE) (Gulbransen & Sharkey, 2012). Ces dernières ont des propriétés morphologiques semblables à celles des astrocytes du SNC et se distinguent aussi des cellules de Schwann périphériques (Gabella, 1971;Cook & Burnstock, 1976).…”

Toward a better understanding of enteric gliogenesis

“…8 Other work focusing on the diversity of enteric glial cells led to the identification of 4 specific types based on their morphology and their location along the serosa-to-lumen axis: star-shaped "protoplasmic gliocytes" within myenteric ganglia (type I), elongated "fibrous gliocytes" within fiber tracts (type II), mucosal and intramuscular gliocytes with 4 primary processes (type III mucosa and Type III MP/SMP , respectively) and bipolar intramuscular gliocytes (type IV). 9,10 Whether each of these subtypes has an associated physiologic role remains to be determined but differences in dye filling, calcium transient and receptor expression strongly suggest that enteric glial subtypes are functionally distinct. 2,9 Another interesting feature of enteric glial cells is their remarkable plasticity.…”