Preliminary IL-1 Family Cytokine Signature for Crohn’s Disease Onset in Pediatric Juvenile Idiopathic Arthritis

Abstract

Crohn’s disease (CD) in children with juvenile idiopathic arthritis (JIA) is frequently diagnosed late due to overlapping symptoms and non-specific biomarkers. We hypothesized that longitudinal cytokine profiling could identify a pre-symptomatic signature predictive of CD conversion in pediatric JIA patients. Ninety pediatric participants (JIA, CD, psoriatic arthritis, healthy controls) underwent serum cytokine profiling (IL-1α, IL-1β, IL-36α, IL-37, IL-6, IL-18, IL-27, IL-31) at baseline and 12 months. Statistical analysis used Mann–Whitney U tests for two-group comparisons, the Kruskal–Wallis test with Dunn’s post hoc for multi-group comparisons, Fisher’s Exact Test for categorical outcomes, and exploratory principal component analysis (PCA). Baseline screening identified a subgroup of JIA patients (N = 4) with significantly elevated IL-1α, IL-1β, and IL-36α. At 12 months, all four patients in this subgroup received a secondary CD diagnosis (4/4 converters vs. 0/21 non-converters; Fisher’s Exact Test: p < 0.0001). The longitudinal analysis at conversion revealed a broader pro-inflammatory shift, with marked increases in IL-18 and IL-31, alongside elevated IL-37, suggesting a compensatory regulatory response. PCA confirmed that converters clustered distinctly from both stable JIA and established CD. A baseline IL-1 family signature may represent a preliminary predictive signature for CD onset in pediatric JIA. Although constrained by the small converter subgroup (N = 4), these data support cytokine profiling for earlier diagnosis in high-risk populations.