Study of the gut metabolome in postoperative Hirschsprung's disease patients hints at increased glycosaminoglycan breakdown and dysbiosis

Hirschsprung's disease (HD) is a neurological intestinal birth defect seen in approximately 1 to 5000 newborns. Despite surgical treatment shortly after presentation, up to 60% of patients will express long-term gastrointestinal complaints, including recurring and potentially life-threatening Hirschsprung-associated enterocolitis (HAEC). The aim of this study was to unravel chronic post-operative gastrointestinal disturbances, furthermore looking into predisposing differences between patients with and without a history of HAEC. Faecal samples from postoperative HD patients (n = 38) and their healthy siblings (n = 21) were subjected to targeted and untargeted metabolomic analysis using high resolution Q-Orbitrap MS. Targeted analysis identified pipecolic acid, N-acetylneuraminic acid, N-acetylglucosamine, glutamic acid, isovaleric acid, ethyl pentyl ketone, fructose and serine as significantly (p < 0.05) decreased in HD patients, whereas dopamine was significantly (p < 0.05) increased. The HAEC subgroup expressed decreased concentrations of trans-4-hydroxy-L-proline and 4-methyl-3-penten-2-one, but increased ethyl pentyl ketone. Validated multivariate OPLS-DA regression models (based on 42760 untargeted metabolite features) of the comprehensive gut metabolome allowed differentiation of HD patients versus healthy controls, as well as between patients with and without a HAEC. Pathway analysis revealed impact on amino sugar, lysine, sialic acid and heparan sulfate metabolism in HD, as well as impaired tyrosine metabolism in patients with a history of HAEC. These changes imply disruption of the intestinal mucosa due to glycosaminoglycan breakdown and dysbiosis, furthermore revealing promising diagnostic and/or prognostic candidate biomarkers. Parallels between HAEC biomarkers with pediatric celiac disease markers hint towards similarities in pathophysiology, warranting further investigation.