Two sides of the same coin: protective versus pathogenic mesentery in inflammatory bowel diseases – a comprehensive review

The mesentery, a membranous structure containing blood vessels, nerves, and lymphatics and attaching the intestines to the posterior abdominal wall, plays a crucial role in the pathogenesis of inflammatory bowel disease (IBD). In this review, we describe the signature features of the mesentery in IBD, including mesenteric hypervascularity (the comb sign) and edema, creeping fat generation, mesenteric fibrofatty proliferation, mesenteric lymphadenopathy, stenosis/sacculation, and hyperplasia of neurological components. These traits trigger a surge in the production of chemokines and proinflammatory cytokines within the mesentery and cause a significant buildup of inflammatory immune cells, exacerbating intestinal inflammation. Contradictorily, the intact lymphatic mesentery, in conjunction with the intestinal mucosa, immune cells, and commensal bacteria, constitutes a mechanical barrier that restricts bacterial penetration, thus preventing the initiation of abnormal immune responses. The mesentery also contributes to the processes of fibrosis and stenosis by secreting adiponectin and anti-inflammatory cytokines and suppresses intestinal perforation and the translocation of bacteria to the peritoneum, leading to the containment and remission of intestinal inflammation. Moreover, we also propose novel diagnostic strategies and therapeutic interventions that target the mesentery in the management of IBD.