P056 Cereal intake and diet-related microbial metabolites in faeces associate with recurrence of gut inflammation during food reintroduction in children with Crohn’s disease treated with exclusive enteral nutrition; iPENS a multicentre, prospective study

Abstract

Abstract Background Faecal calprotectin (FCAL) rises rapidly in children with Crohn’s disease (CD) following treatment with exclusive enteral nutrition (EEN). We aimed to identify clinical, dietary and diet-related microbial metabolites which associate with the recurrence of FCAL above 250 mg/kg after 21 days of food reintroduction. Methods Children with CD (age 6-17 years), clinically responding to EEN, were recruited, prospectively, from 11 UK hospitals (January 2020-May 2023, NCT04225689). They provided a single faecal sample before EEN completion (timepoint A) and 6 serial samples (timepoints B-G; 3, 6, 9, 12, 15, 21 days) in the first 21 days of food reintroduction. Faecal short (SCFA) and branched (BCFA) chain fatty acids were measured as proxies of fibre and protein bacterial fermentation, respectively. In faeces, pH, water content (%), Bristol stool score, total microbial load (qPCR) and starch output were measured. Clinical parameters, medications, CRP, ESR, albumin and anthropometry were recorded at EEN completion. Nutrient and food group intake was analysed with Nutritics®. Relationships with FCAL levels were explored. Results Thirty children provided 209/210 (99%) of expected faecal samples. FCAL (median [Q1, Q3], mg/kg) increased within 12 days of food reintroduction (EEN completion: 328 [154, 2370] vs 12 days post-EEN: 1123 (451, 2073), p<0.01) and remained high throughout follow-up. Negative correlations were observed between FCAL with acetate, whereas positive correlations were noted with BCFA (isovalerate and isobutyrate) and their ratio over acetate; the latter remained significant at all 7 timepoints (Figure 1A). Use of immunosuppressants, blood inflammatory markers, clinical and anthropometry at EEN completion were not predictive of FCAL increase post-EEN. In a subset of patients with FCAL<250 mg/kg at EEN completion, (n=13/30), subset regression using ‘end of EEN’ diet-related microbial data, generated a model with 91% accuracy to predict FCAL increase over 250 mg/kg at 21 days of food reintroduction, with isovalerate being the sole predictor of FCAL recurrence (Figure 1B). Average intake of cereal products (median [Q1, Q3], g/day) over 21 days was lower in patients who experienced an FCAL recurrence (FCAL<250mg/kg: 313 (223, 370) vs FCAL>250mg/kg: 186 (167, 217), p=0.013). Positive correlations were observed between the 21-day average intake of cereal products and concentration of SCFA at 21 days post-EEN; acetate (rho=0.38, p=0.041), butyrate (rho=0.46, p=0.0.01) and total SCFA (rho=0.41, p=0.026). Conclusion This study suggests that early FCAL rebound, following treatment with EEN, is related to an increased ratio of dietary protein to fibre bacterial fermentation and a lower intake of cereal products.