Intestinal microbiota and allergic diseases: A systematic review

Area of Science:

• Microbiology
• Immunology
• Allergy Research

Background:

• Intestinal microbiota imbalances are increasingly implicated in allergic disease development.
• Previous studies (pre-2007) suggested correlations but did not clearly distinguish protective vs. risk-associated microbes.

Purpose of the Study:

• To review studies published since 2007 focusing on intestinal microbiota composition in allergic diseases.
• To identify specific microbial signatures associated with allergy development and manifestation.

Main Methods:

• Systematic literature review of studies published from 2007 onwards.
• Exclusion of studies involving clinical interventions before stool sample collection.
• Analysis of identified studies for microbial composition in early-life and symptomatic allergic children.

Main Results:

• Early-life microbiota in children who developed allergies showed lower diversity, a Firmicutes predominance, higher Bacteroidaceae, and specific shifts in anaerobic bacteria (e.g., increased B. fragilis, E. coli; decreased B. adolescentis, Lactobacillus).
• Microbiota at allergy onset revealed higher Bacteroides counts, lower beneficial bacteria (e.g., A. muciniphila, F. prausnitzii), and altered prevalence of Bifidobacterium and Staphylococcus species, alongside reduced overall bacterial diversity.

Conclusions:

• Specific intestinal microbial profiles are associated with the development and onset of allergic diseases in children.
• Further research is needed to elucidate the causal roles of these microbial shifts and to identify potential protective or pathogenic microorganisms.