The appendix and ulcerative colitis - an unsolved connection

The appendix is thought to have a role in the pathogenesis of ulcerative colitis, but the nature and basis of this association remains unclear. In this Perspective, we consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to evidence that supports the involvement of the appendix in ulcerative colitis. In experimental models, removal of the inflamed appendix prevents colitis, and in human observational studies, appendectomy is associated with protection against ulcerative colitis. Further, among people who develop ulcerative colitis, appendectomy before diagnosis might influence the course and outcomes of the disease - some evidence suggests that it protects against colectomy but could increase the risk of colorectal cancer. Appendectomy after onset of ulcerative colitis seems to have disparate consequences. Clinical trials to understand whether appendectomy has a role in the treatment of ulcerative colitis are ongoing. Major questions about the role of the appendix in the pathogenesis of ulcerative colitis remain unanswered, and further research is needed to establish whether the connection is clinically relevant. The appendix is thought to have a role in the pathogenesis of ulcerative colitis but the association remains unclear. In this Perspective, the authors consider the biology of the appendix with respect to its immunological function and the microbiome, and how this relates to its possible involvement in ulcerative colitis.

Automated summary

The appendix is believed to play a role in the development of ulcerative colitis, but the exact nature of this association is still unclear. This Perspective discusses the immunological function and microbiome of the appendix and how they may relate to its potential involvement in ulcerative colitis. Experimental models have shown that removal of the inflamed appendix prevents colitis, and observational studies in humans have found that appendectomy is associated with protection against ulcerative colitis. Further research is needed to determine the clinical relevance of the connection between the appendix and ulcerative colitis.