Environmental factors in IBD pathogenesis: Implications for prognosis, prevention and treatment

Speakers: Franck Carbonnel (France), Johan Burisch (Denmark), Fergus Shanahan (Ireland)

The role of gut microbiota in the pathogenesis of inflammatory bowel disease (IBD) is increasingly recognised, as evidenced by the escalating number of publications on microbiota, rising from less than 200 in 1990 to over 1200 in 2012 thus far. This fact was highlighted by Dr Fergus Shanahan when introducing his presentation on microbiota at UEG Week 2012. He noted that a healthy gut is one in which there is high microbial diversity resulting in improved performance and stability. Conversely, in the disease state the opposite is true. Moreover, the heterogeneity of IBD is reflected in the microbiota.

Environmental modifiers have a huge influence on IBD, changing the disease epidemiology, and these may influence the microbiota. In animal models, a defect in immunity is demonstrated to increase the risk of IBD, which is also associated with changes in the microbiota. Interestingly, the gut microbiota is seen to change with increasing age, and in the elderly a change in diet leading to changes in microbiota can affect health parameters such as frailty and inflammation. The age of onset of ulcerative colitis (UC) is typically in the 20s and 30s, and an association is found between migration at a young age correlating with a greater chance of acquiring diseases prevalent in the new country. Dr Shanahan concluded that future treatments may be elicited from mining host-microbe interactions.

Dr Johan Burisch presented the first results from the European EpiCom study on the incidence of IBD and phenotype at diagnosis (www.epicom-ecco.eu); this data won him the award for best poster presented at UEG Week 2012 from his home country of Denmark. In this prospective study of over 1600 patients with UC and Crohn’s disease (CD) from 22 countries, both UC and CD were found to be twice as common in Western Europe compared with Eastern European countries (IBD incidence 18.4 vs. 7.8 per 100,000, respectively). While across Europe, no differences in phenotype at diagnosis, time from onset of symptoms to diagnosis, and smoking status were found.

Dr Franck Carbonnel outlined the increasing knowledge on non-infectious environmental risk factors for IBD. While tobacco and appendectomy are established risk factors for IBD, recent data from prospective studies including EPIC and NHS, show an association with diet, drugs (particularly antibiotics), and level of sun exposure/vitamin D. These factors may be involved in causal networks that also include the microbiota, genetics, epithelial barrier and immune response. He concluded that, in the future further knowledge of the association between environmental risk factors and disease may lead to prevention of IBD in people at risk, and to a decrease in risk of relapse in patients with IBD.

GMFH Editing Team
GMFH Editing Team