New diagnostic approaches for inflammatory bowel diseases

Inflammatory bowel diseases (IBD), that include ulcerative colitis (UC) and Crohn's disease (CD) are among the most serious and perplexing digestive diseases. Indeed, diagnosis is sometimes delayed due to the variability and subtlety of its initial manifestations, especially in CD. Since no gold standard is currently defined for the diagnosis and monitoring of IBD, a number of genomic, metabolomic and proteomic studies have tried to address this issue. After illustrating the traditional diagnostic approach (mainly fecal calprotectin), this Opinion Paper reports about the utility of some new biomarkers (micro-RNA, proteomic and metabolomic markers). In particular, the results of a study on fecal peptides are commented. After verifying that proteolytic degradation was clearly visible in fecal samples of a number of control (n=34) and patients with IBD (n=133), the matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry was used to evaluate peptides patterns of fecal samples, in a range from 1000 to 4000 Da. This cohort was used to derive an algorithm for IBD diagnosis. Diagnostic performances were then estimated using an additional validation cohort, including subjects with IBD (n=42) and without IBD (n= 28). Sensitivity was 54.8% (95%CI: 38.7%-70.2%) and specificity 96.4% (95%CI: 81.7%-99.9%) with a positive and a negative predictive value of 95.8% (95%CI: 76.7%-99.4%) and 58.7% (95%CI: 50.3-66.6%), respectively. In comparison, fecal calprotectin, achieved sensitivity and specificity of 78.6% (95%CI: 63.2%-89.7%) and 42.9% (95%CI: 24.5%-62.8%). In spite of the obtained good diagnostic performances, any candidate biomarker, once identified, should be carefully validated before being translated into clinical practice.