The Intestinal Microbiome in Allergic Disease

Evidence from epidemiological studies demonstrates that the prevalence of allergic disease is increasing worldwide; an epidemic largely driven by environmental factors associated with the adoption of a modern, urbanized lifestyle. Changes in early-life intestinal colonization patterns stemming from reduced exposure to traditional environmental microbes have been implicated in the failure of allergic individuals to develop appropriate immunoregulatory networks. Indeed, differences in intestinal microflora composition are observed between allergic and non-allergic persons, and colonization patterns measured within the first few months of life are especially predictive of allergic status. Several environmental factors have been associated with this microbiome imbalance, but there is conflicting evidence as to which exposures are truly driving disruption. Based on evidence linking microbiome perturbation to the pathogenesis of allergic disease, an obvious approach to prevention and treatment of allergy has been the use of probiotics and bacterial by-products (i.e. SCFAs). These interventions have seen some success in animal studies, but current attempts to therapeutically manipulate the microbiome in humans have been largely unable to impact systemic sensitization and alter host allergic status.