Macrophages in intestinal inflammation and resolution: a potential therapeutic target in IBD

Macrophages are the gatekeepers of intestinal immune homeostasis as they discriminate between innocuous antigens and potential pathogens to maintain oral tolerance. However, in individuals with a genetic and environmental predisposition, regulation of intestinal immunity is impaired, leading to chronic relapsing immune activation and pathologies of the gastrointestinal tract, such as IBD. As evidence suggests a causal link between defects in the resolution of intestinal inflammation and altered monocyte–macrophage differentiation in patients with IBD, macrophages have been considered as a novel potential target to develop new treatment approaches. This Review discusses the molecular and cellular mechanisms involved in the differentiation and function of intestinal macrophages in homeostasis and inflammation, and their role in resolving the inflammatory process. Understanding the molecular pathways involved in the specification of intestinal macrophages might lead to a new class of targets that promote remission in patients with IBD.