Intestinal peristalsis is regulated by the enteric nervous system and is influenced by dietary and microbial changes. In Cell, Muller et al. show that a distinct population of macrophages that are distributed in the intestinal smooth muscles (muscularis macrophages) and are characterized as MHCIIhiCD11cloCD103−CD11b+CX3CR1hi cells regulate the peristaltic activity of the colon in the steady state. Muscularis macrophages are found along nerve fibers and secrete the soluble mediator BMP2, which signals constitutively to enteric neurons through the BMP receptor. In turn, enteric neurons contribute to the maintenance of muscularis macrophages through secretion of the macrophage growth factor CSF1. Antibiotic treatment diminishes the expression of BMP2 and the number of macrophages, as well as signaling via the BMP receptor and expression of CSF1 in neurons and results in dysregulated peristalsis. These findings suggest that the macrophage-neuron crosstalk that controls gut peristalsis is influenced by bacterial commensals.

Cell 158, 300–313 (2014)