A Prospective Longitudinal Study of Fecal Microbiome and Calprotectin to Predict Relapse in Patients With Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic idiopathic inflammatory condition of the intestine, which results in diarrhea, rectal bleeding, urgency, weight loss and abdominal pain. The natural course of IBD is characterized by activity outbreaks and periods of remission. In most cases, relapses in Crohn's disease (CD) and in ulcerative colitis (UC) are unpredictable and despite effective medical treatment, a degree of subclinical inflammation may persist in the bowel wall, contributing to a significant risk of relapse.

Endoscopy has been used to monitor a disease but it is time-consuming, costly, invasive, and associated with certain risks of morbidity. Many patients are reluctant to undergo repeated endoscopic examinations, particularly when their disease is quiescent. Acute phase reactants have been used but their sensitivity and specificity in correlating to intestinal inflammatory activity are very low, and their capacity to predict disease relapse is poor and controversial. A number of fecal biomarkers have been evaluated for their utility for monitoring and predicting relapse in IBD but some of these biomarkers are also not specific.

In IBD, altered fecal microbiota signatures have been consistently reported which included a reduction in biodiversity with lower proportions of Firmicutes and increases in Proteobacteria and Bacteroidetes phylum members. In addition, disease remission and relapse are associated with microbial changes in both mucosal and fecal samples. In particular, a loss of species richness in Crohn's disease has been widely observed. Recently microbial biomarkers may differentiate between CD and UC. Furthermore, different microbial groups are associated with smoking habit and localization of the disease in CD and UC. It is however unclear whether changes in microbial profile including diversity and composition can predict disease relapse in IBD. We hypothesize that fecal microbial signatures in conjunction with fecal calprotectin may play a role in predicting relapse in IBD patients.