Crosstalk between muscularis macrophages and enteric neurons regulates gastrointestinal motility

Area of Science:

• Gastroenterology
• Immunology
• Neuroscience

Background:

• Intestinal peristalsis is crucial for gut function but its regulation is not fully understood.
• Macrophages in the intestinal muscularis externa are implicated in gut motility.
• The interplay between immune cells and the nervous system in the gut is complex.

Purpose of the Study:

• To investigate the role of muscularis macrophages in regulating intestinal peristalsis.
• To elucidate the molecular mechanisms underlying macrophage-neuron communication in the gut.
• To determine the influence of microbial factors on this crosstalk.

Main Methods:

• Immunohistochemistry to identify macrophage populations.
• In vivo and ex vivo studies of colonic motility.
• Molecular biology techniques to assess protein and gene expression (BMP2, BMPR, CSF1).
• Studies involving germ-free and conventionally-raised mice.

Main Results:

• Muscularis macrophages directly regulate colonic peristaltic activity in steady-state conditions.
• Macrophages secrete bone morphogenetic protein 2 (BMP2), activating BMP receptors on enteric neurons.
• Enteric neurons secrete colony-stimulating factor 1 (CSF1), essential for macrophage development.
• Microbial commensals modulate BMP2 and CSF1 expression, influencing the macrophage-neuron axis.

Conclusions:

• A novel crosstalk exists between muscularis macrophages and enteric neurons that governs gastrointestinal motility.
• This communication pathway is plastic and driven by the gut microbiota.
• Understanding this axis offers new insights into the regulation of gut function and potential therapeutic targets.