VIP and escherichia coli infection: Furthermore, acetylcholine signals from the vagal nerve stimulated ILC3s to secrete the immunoresolvent PCTR1 during peritoneal E. coli infections.218 In contrast, the neuropeptides neuromedin U (NMU) and vasoactive intestinal peptide (VIP) are expressed in the enteric nervous system and stimulate ILC2s via Nmur1 and Vipr2, respectively.219–223 NMU is expressed in cholinergic neurons in the intestine.