Although allergies are multifactorial diseases, they most often result from an abnormal immune response to allergens. This disorder may be due to a microbiota imbalance.
Food allergies (FA) are increasingly common in developed countries. In Europe, the prevalence of FA is 4.7% in children and 3.2% in adults. In France, around 5% of the population is allergic1. FA are related to an hypersensitivity to dietary proteins, most often IgE-dependent. In children, five specific allergens are responsible for 82% of FA: chicken eggs, peanut, cow’s milk, mustard, and fish, to which are added, in adults, shellfish, wheat, and nuts2.
An identified immune mechanism
To explain these allergies, researchers suppose that the proper maturation of the immune system requires repeated exposure to new bacterial antigens, and that the impoverishment of the microbial ecosystem promotes the development of inappropriate immune responses to antigens that are normally inoffensive3.
An obvious connection to intestinal microbiota
Epidemiological observations have very quickly connected allergic phenomena with microbiota alteration: all allergic patients have a different microbiota than healthy individuals4,5. It has been shown that dysbiosis is present in allergic individuals and bacteria belonging to the Clostridia, Proteobacteria, Bacteroidetes and Actinobacteria6-9 classes are particularly involved in cases of FA.
Results suggest than modulating the microbiota could help prevent allergies, through the use of probiotics and prebiotics. A large number of studies exist on the positive effects of probiotics in animal models (mice, rats, pigs) of sensitization to food allergies, atopic dermatitis, and asthma10.
1 - Moneret-Vautrin DA. Épidémiologie de l’allergie alimentaire Revue française d’allergologie et d’immunologie clinique 2008 ; 48 : 171–178 .
2 – Rona RJ et al. The prevalence of food allergy: a meta-analysis. J Allergy Clin Immunol 2007 ; 120:638–46.
3 - Omenetti S. et al. The Treg/Th17 axis : a dynamic balance regulated by the gut microbiome. Front Immunol 2015 ; 6 : 639.
4 - Panzer AR et al. Influence and effect of the human microbiome in allergy and asthma. Curr Opin Rheumatol 2015 ; 27(4) : 373–80.
5 - Drell T et al. Differences in Gut Microbiota Between Atopic and Healthy Children. Curr Microbiol 2015 ; 71 : 177-83.
6 - Thompson-Chagoyan OC et al. Faecal microbiota and short-chain fatty acid levels in faeces from infants with cow’s milk protein allergy. Int Arch Allergy Immunol 2011 ; 156 : 325-32.
7 - Candela M et al. Unbalance of intestinal microbiota in atopic children. BMC Microbiol 2012 ; 12 : 95.
8 - Ling Z, Li Z, Liu X, et al. Altered fecal microbiota composition associated with food allergy in infants. Appl Environ Microbiol 2014 ; 80 : 2546-54.
9 - Sepp E, Julge K, Mikelsaar M, Björkstén B. Intestinal microbiota and immunoglobulin E responses in 5-year-old Estonian children. Clin Exp Allergy 2005 ; 35 : 1141-6.
10 - de Azevedo MS, Innocentin S, Dorella FA, et al. Immunotherapy of allergic diseases using probiotics or recombinant probiotics. J Appl Microbiol 2013 ; 115 : 319-33.