Serum Protein Biomarkers of Fibrosis Aid in Risk Stratification of Future Stricturing Complications in Pediatric Crohn's Disease

Abstract

Objectives: Avoiding fibrostenotic complications is of paramount concern in the management of Crohn's disease (CD). We sought to investigate the association of candidate biomarkers of fibrosis collected at diagnosis with the future development of fibrostenotic CD.

Methods: Using the Risk Stratification and Identification of Immunogenetic and Microbial Markers of Rapid Disease Progression in Children with Crohn's Disease cohort, a multicenter prospective observational pediatric inception cohort, subjects with an inflammatory phenotype (B1) at diagnosis who later converted to a stricturing phenotype (B2) within 3 years were compared with those who remained B1. Serum collected at diagnosis underwent both parallel reaction monitoring-targeted proteomic analysis and conventional enzyme-linked immunosorbent assay for 10 candidate biomarkers of intestinal fibrosis. Cox proportional hazard regression was used for multivariable analysis of time-dependent outcomes.

Results: In 116 subjects 58 subjects with verified B1 phenotype at diagnosis who later converted to B2 disease were compared with 58 subjects who remained B1 over 3 years of follow-up. Extracellular matrix protein 1 (ECM1) levels in the upper quartile (hazard ratio [HR] 3.43, 95% confidence limit [CL] 1.33, 8.42) were associated with future fibrostenotic disease. ASCA IgA (HR 4.99, 95% CL 1.50, 16.68) and CBir levels (HR 5.19, 95% CL 1.83, 14.74) were also associated with future intestinal fibrostenosis, although ECM1 continued to demonstrate independent association with conversion to B2 even with adjustment for serologies in multivariable analysis (HR 5.33, 95% CL 1.29, 22.13).

Conclusions: ECM1 and other biomarkers of fibrosis may aid in determining the risk of uncomplicated inflammatory disease converting to B2 stricturing phenotypes in children with CD. Prospective validation studies to verify test performance and optimize clinical utilization are needed before clinical implementation.

Figure 1

Comparison of candidate biomarker protein quantitation by PRM between subjects with CD remaining B1 vs those converting to B2 after 3-year follow-up. Peptide abundance plots from PRM analysis using 4 candidate biomarkers demonstrating a significant difference between those remaining B1 and those converting to B2 stricturing disease. Peptide fragments were standardized using light/heavy (L/H) ratios (*P < 0.05; **P < 0.01). CD, Crohn′s disease; COMP, cartilage oligomeric matrix protein; ECM1, extracellular matrix protein 1; FINC, fibronectin; MMP9, matrix metalloproteinase 9; PRM, parallel reaction monitoring.

Figure 2

ELISA quantitation of candidate proteins associated with future conversion to stricturing phenotype. Elevated concentrations of ECM1 and FINC and reduced concentrations of COMP and MMP9 were associated with future intestinal stricture development on unadjusted analysis (*P < 0.05, **P < 0.01). Results on ELISA quantitation were similar to PRM biomarker trends. COMP, cartilage oligomeric matrix protein; ECM1, extracellular matrix protein 1; ELISA, enzyme-linked immunosorbent assay; FINC, fibronectin; MMP9, matrix metalloproteinase 9; PRM, parallel reaction monitoring.