Neuroimmune interactions in inflammatory bowel disease: Role of intestinal macrophages and the cholinergic pathway

The molecular mechanisms by which the autonomic nervous system regulates immune cell function have become a popular research topic. The discovery that vagus nerve stimulation (VNS) alleviates endotoxemia has laid an important foundation for further study of the neuroimmune system. This review focuses on the latest insights related to intestinal neurons and macrophages (Mφs) and outlines the mechanisms underlying cholinergic control of inflammation and key electrophysiological VNS approaches for the treatment of inflammatory bowel disease (IBD). Mφs are the most important antigen-presenting cells in the human body and exist in various forms. In the gut, Mφs can maintain the intestinal balance by engulfing and digesting microorganisms. However, macrophage overactivation results in the production of excessive inflammatory mediators, which can damage the intestinal mucosa and induce an inflammatory response, leading to IBD. The role of cholinergic anti-inflammatory mechanisms in immune-mediated IBD have attracted substantial attention. Mφs are a special type of phagocytes that play a crucial role in maintaining intestinal homeostasis and movement. In the intestinal tract, Mφ is classified into different subgroups based on its position in the parietal layer and is closely related to the microenvironment.