D1.473 - Features of the intestinal microbiota composition in infants with IgE- and non-IgE-mediated allergy

The assessment of the intestinal microbiota composition disorders in children with allergy as one of the possible factors of the allergic inflammation induction is important to determine the directions of its correction.

Objective: to study the features of the intestinal microbiota composition in infants with allergy depending on the presence / absence of specific sensitization.

60 infants with allergy to food, respiratory and household allergens were included in the cross-sectional study: group I (n=37, infants of the first year of life) at the age of 7 [6; 9] months old and group II (n=23, infants of the second year of life) at the age of 16 [15; 19] months old. The intestinal microbiota composition in patients of both groups was simultaneously studied by the metagenomic analysis of 16S rRNA gene fragment sequencing method and the determination of specific IgE by the ALEX2 allergochip method.

Allergic sensitization to food and respiratory/household allergens was detected in 19 (51.4%) patients of group I and in 8 (35%) patients of group II. Significantly lower α-diversity of the intestinal microbiota was revealed in group I infants with IgE sensitization compared to patients with non-IgE-mediated allergy. When assessing β-diversity of the intestinal microbiota in group I IgE-sensitized patients, only two dominant genera of SCFA producing bacteria, Megamonas and Robinsoniella, were identified, while in infants without IgE sensitization there were significantly more such genera of microbes, including Enterocloster, Lacrimispora, and Anaerostipes. In group II IgE-sensitized patients, with a decrease in the α-diversity of the intestinal microbiota and the detection of opportunistic microbes - Enterococcus avium and Enterobacter hormaechei - the representation of the Megamonas genus bacteria (Megamonas rupellensis, Megamonas hypermegale, Megamonas funiformis) increases. In group II infants with non-IgE-mediated allergy, an increase in the species diversity of SCFA-producing microorganisms, Roseburia, Blautia, and Clostridium, was also detected.

Intestinal dysbiosis is more pronounced in infants with allergy of groups I and II with IgE sensitization than in non-sensitized patients of both groups. With increasing age, the content of SCFA-producing microbes in the intestinal microbiota increases in all infants, which may be associated with the possible formation of immune tolerance.