Untargeted metabolomics combined with 16S rRNA sequencing reveals the characteristics of intestinal metabolism and gut microbiota in hazelnut Cor a 14-allergic BALB/c mice

Cor a 14 is one of the most vital allergens in hazelnuts. However, the features of intestinal metabolites and microbiota associated with Cor a 14-induced allergy remain unclear. In this study, we established a hazelnut Cor a 14-allergic BALB/c mice model, which was distinguished by the dropped temperature and enhanced allergic inflammatory factor levels in serum. Faeces were collected to detect characteristics of the intestinal metabolites by untargeted metabolomics and the gut microbiota by 16S rRNA sequencing. The α- and β-diversity of gut microbiota in Cor a 14-allergic mice differed from the controls with elevated relative abundance of Lactobacillus and reduced relative abundances of Odoribacter, Chloroplast, Alistipes and Lachnospiraceae_NK4A136_group. Untargeted metabolomics results revealed that 238 significantly differential metabolites (111 up-regulated, 127 down-regulated) were identified, of which, L-tryptophan, histamine and N-acetylhistamine were remarkably accumulated and primarily enriched in the enhanced L-tryptophan and histidine metabolism pathways. Spearman correlation analysis suggested that L-tryptophan was positively correlated with allergic indicators and screened as the potential biomarker for Cor a 14 allergy. Collectively, our findings uncovered the characteristics of intestinal metabolites and gut microbiota during Cor a 14 anaphylaxis and provided new potential insights for diagnosis of hazelnut allergy.