Biomarkers of intestinal fibrosis - one step towards clinical trials for stricturing inflammatory bowel disease.

Intestinal fibrosis, caused by an excessive deposition of extracellular matrix components, and subsequent stricture development are a common complication of inflammatory bowel disease. However, currently there are no biomarkers which reliably predict the risk of developing intestinal strictures or identify early stages of fibrosis prior to clinical symptoms. Candidate biomarkers of intestinal fibrosis, including gene variants (i.e. nucleotide-binding oligomerization domain-2 gene), serum microRNAs (miR-19, miR-29), serum extracellular matrix proteins (i.e. collagen, fibronectin) or enzymes (i.e. tissue inhibitor of matrix metalloproteinase-1), serum growth factors (i.e. basic fibroblast growth factor, YKL-40), serum anti-microbial antibodies (i.e. anti-Saccharomyces cerevisiae) and circulating cells (i.e. fibrocytes) have shown conflicting results on relatively heterogeneous patients' cohorts, and none of them was proven to be strictly specific for fibrostenosis, but rather predictive of a disease disabling course. In this review we critically reassess the diagnostic and prognostic value of serum biomarkers of intestinal fibrosis in inflammatory bowel disease.