Demystifying Dysbiosis: Can the Gut Microbiome Promote Oral Tolerance Over IgE-mediated Food Allergy?

摘要

The growing burden of food allergy is being driven by environmental exposures and thepotential role of gut micro-organisms (or ‘microbiota’) is hotly debated. Early culture-based studiesoutlined that imbalances between commensal gut constituents (‘dysbiosis’) early in life may raisethe risk of developing allergic disease. A number of studies using animal models describe mechanismsby which specific bacterial taxa within the gut microbiota, their diversity and dietary substratessuch as fibre may promote oral tolerance. Next-generation sequencing now allows the detailedcharacterization of the microbiota in relation to epidemiological exposures and clinical foodallergy status in humans. Faecal samples from one birth cohort characterized for food allergy statushave been sequenced and showed less gut microbiota richness amongst three month infants wholater developed food sensitization at one year. A large cross-sectional survey of young childrenwith milk allergy showed that greater gut microbiota diversity and enrichment of Clostridia andFirmicutes phyla during early infancy is associated with greater likelihood of out-growing milk allergyby eight years of age. Case control studies are limited to selecting participants from amongsthospital patients and have only allowed comparison of heterogeneous groups. To assess whetherinfants’ gut microbiota may predispose towards the development of food allergy, cohort studiesmust be undertaken to evaluate gut microbiota development from early in infancy and prospectivelycharacterise patterns according to whether challenge proven food allergy later develops, whilst adjustingfor atopic dermatitis, dietary and antibiotic exposures.