Enhanced antibacterial properties of enteric glial cells attenuate intestinal inflammation through the GABABR-mediated autophagy pathway

Abstract

Enterotoxigenic Escherichia coli (ETEC) infection is a severe threat to global public health because of its high morbidity and mortality among children and infants. Enteric glial cells (EGCs) are involved in host–bacteria communication. However, the mechanisms through which EGCs interact with ETEC remain unclear. We attempted to assess whether γ-aminobutyric acid type B receptor (GABABR) activation participated in EGC autophagy during Escherichia coli K88 (ETECK88) infection. Alterations in autophagy and EGC activity were observed in the intestines of the ETECK88-infected mice, and similar results were obtained from experiments in which the EGCs were directly infected with ETECK88. EGC pretreatment with specific autophagy agonists significantly decreased the inflammatory response and bacterial burden, whereas pretreatment with inhibitors had the opposite effect. Interestingly, in EGCs, GABABR activation notably increased Beclin 1 and LC3 levels and autophagosome and autolysosome numbers, thus promoting autophagy activation and enhancing antimicrobial responses against ETECK88 infection. Furthermore, GABABR defense was mediated via myeloid differentiation factor 88 (MyD88) signaling in EGCs, which was proven to be based on the inhibition or overexpression of MyD88. Notably, comparable results of GABABR activation in vivo were observed in response to ETECK88, implicating this as a defense mechanism that reinforced antibacterial activity to alleviate intestinal inflammation in mice. Our study revealed previously unappreciated roles for GABABR in linking EGC antibacterial autophagy to strengthen host defense against ETECK88 infection, thus identifying GABABR as an important target for the treatment of infective enteritis.