The role of the complement system in gastrointestinal-related diseases

The complement system bridges innate and adaptive immunity, orchestrating immune surveillance and maintaining tissue homeostasis. This review summarizes the role of the complement system in gastrointestinal-related diseases, including its function in innate immunity, impact on adaptive immunity, and regulatory role under physiological and pathological conditions in the gut. The activation pathways, regulatory mechanisms, and interactions of the complement system with the gut microbiome are crucial for maintaining intestinal homeostasis. Genetic deficiencies or excessive activation of the complement system are closely associated with the development of various intestinal diseases, including infections, inflammatory bowel disease (IBD), and tumors. This review also explores the role of the complement system in the tumor microenvironment (TME) of the gut and its potential as a therapeutic target. By deepening our understanding of the mechanisms by which the complement system operates in gastrointestinal diseases, we can provide a theoretical foundation for the development of novel treatment strategies.