Evidence for neuromodulation of enteropathogen invasion in the intestinal mucosa

The extensively innervated intestinal mucosa encompasses a vast surface exposed to an array of potentially infectious microorganisms. We investigated the role of enteric nerves in modulating intracellular internalization of a multidrug-resistant Salmonella typhimurium DT104 field isolate in mucosa-submucosa sheets from the porcine ileum, a biomedical model for the human intestine. The effects of transmural electrical stimulation and drugs on intracellular internalization of Salmonella over 90 min was determined by a gentamicin-resistance assay relative to untreated tissues from the same animal serving as controls. The actin inhibitor cytochalasin D reduced internalization of Salmonella, and the mucus-disrupting agent dithiothreitol decreased its mucosal adherence. Transmural electrical stimulation increased, and neuronal conduction blockers saxitoxin and lidocaine decreased Salmonella internalization in stimulated and unstimulated tissues. Furthermore, the alpha-adrenergic/ imidazoline receptor ligand phentolamine and the 5-HT₃ receptor antagonist tropisetron decreased internalization in stimulated tissues. Based on these findings, enteric neural activity appears to modulate interactions between the intestinal mucosa and pathogenic bacteria.