Role of visceral fat in colonic inflammation: from Crohn's disease to diverticulitis

Purpose of reviewThe composition of activated adipose tissue with adipocytes secreting a broad spectrum of immune-modulatory adipokines next to adipose tissue-derived stromal cells and professional immune effector cells in the visceral fat creates a complex network of inflammatory processes shaping local immune responses in the adjacent inflamed intestinal mucosa.Recent findingsIn Crohn's disease a particular phenomenon called creeping fat' can be observed. Here the hyperplastic mesenteric fat tissue not only grows around inflamed small intestinal segments but also furthermore affects the regulation of the mucosal immune system. Diverticular disease is highly prevalent in the western world but the knowledge about its immunopathology remains incomplete. Interestingly, adipose tissue also frequently covers the basolateral site of inflamed diverticula, hence locally reflecting the phenomenon seen in Crohn's disease.SummaryThis review aims to summarize the current knowledge in which measures this intraabdominal fat participates in the regulation of intestinal inflammation with a particular focus on differences and possible parallels in Crohn's disease and diverticulitis. The available data allow for suggesting that each inflamed diverticula mechanistically reflects Crohn's disease on a miniature scale.