Review article: lymphatic system and associated adipose tissue in the development of inflammatory bowel disease

Summary Background The lymphatic system plays critical roles in tissue fluid homoeostasis, immune defence and metabolic maintenance. Lymphatic vessels transport lymph, proteins, immune cells and digested lipids, allowing fluid and proteins to be returned to the blood stream, lipids to be stored and metabolized and antigens to be sampled in lymph nodes. Lymphatic drainage is mainly driven by rhythmic constrictions intrinsic to the vessels and critically modulated by fluid pressure and inflammatory mediators. Aim To collect and discuss the compelling available information linking the lymphatic system, adiposity and inflammation. Methods A literature search was performed through PubMed focusing on lymphatic system, inflammation, immune cells and fat transport and function in the context of IBD. Results Evidence collected allows us to propose the following working model. Compromised lymph drainage, reported in IBD, leads to oedema, lymphangiogenesis, impaired immune cell trafficking and lymph leakage. Lymph factor(s) stimulate adipose tissue to proliferate and produce cytokines, which affect immune cell functions and exacerbate inflammation. Conclusions Understanding the lymphatic system’s role in immune cell trafficking and immune responses, contribution to fat transport, distribution, metabolism and implication in the pathogenesis of chronic intestinal inflammation may provide the basis for new therapeutic strategies and improved quality-of-life.