Association Between Plasma Level of Collagen Type III alpha 1 Chain and Development of Strictures in Pediatric Patients With Crohn's Disease.
BACKGROUND & AIMS:There are few serum biomarkers to identify patients with Crohn's disease (CD) who are at risk for stricture development. The extracellular matrix components, collagen type III alpha 1 chain (COL3A1) and cartilage oligomeric matrix protein (COMP), could contribute to intestinal fibrosis. We investigated whether children with inflammatory CD (B1) who later develop strictures (B2) have increased plasma levels of COL3A1 or COMP at diagnosis, compared to children who remain B1. We compared results to previously studied biomarkers, including autoantibodies against colony stimulating factor 2 (CSF2). METHODS:We selected 161 subjects (mean age, 12.2 years; 62% male) from the Risk Stratification and Identification of Immunogenic and Microbial Markers of Rapid Disease Progression in Children with Crohn's cohort, completed at 28 sites in the United States and Canada from 2008 through 2012. The children underwent colonoscopy and upper endoscopy at diagnosis and were followed every 6 months for 36 months; plasma samples were collected at baseline. Based on CD phenotype, children were separated to group 1 (B1 phenotype at diagnosis and follow up), group 2 (B2 phenotype at diagnosis), or group 3 (B1 phenotype at diagnosis who developed strictures during follow up). Plasma samples were collected from patients and 40 children without inflammatory bowel disease (controls) at baseline and analyzed by ELISA to measure COL3A1 and COMP. These results were compared with those from a previous biomarker study. Kruskal-Wallis test and pairwise Dunn's tests with Bonferroni correction were used to compare differences among groups. RESULTS:The median baseline concentration of COL3A1 was significantly higher in plasma from group 3 vs group 1 (P<.01) and controls (P=.01). Median baseline plasma concentrations of COMP did not differ significantly among groups. A model comprising baseline concentrations of COL3A1 and anti-CSF2 identified patients with B2 vs B1 CD with an area under the curve of 0.80 (95% CI, 0.71-0.89); the combined concentration identified patients with strictures with a sensitivity value of 0.70 (95% CI, 0.55-0.83) and a specificity value of 0.83 (95% CI 0.67-0.93). CONCLUSION:We found median plasma concentrations of COL3A1, measured by ELISA at diagnosis, to be significantly higher in patients with CD who later developed strictures than in patients without strictures. The combination of concentrations of COL3A1 and anti-CSF2 might be used to identify pediatric patients at CD diagnosis who are at risk for future strictures.