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Background An altered compositional signature and reduced diversity of early gut microbiota are linked to development of allergic disease. We investigated the relationship between dominant Bifidobacterium species during the early post-natal period and subsequent development of allergic disease in the first year of life. Methods Faecal samples were collected at age 1 week, 1 month and 3 months from 117 infants at high risk of allergic disease. Bifidobacterium species were analysed by quantitative PCR and terminal restriction fragment length polymorphism. Infants were examined at 3, 6 and 12 months, and skin prick test was performed at 12 months. Eczema was diagnosed according to the UK Working Party criteria. Results The presence of B. catenulatum at 3 months was associated with a higher risk of developing eczema ( ORadj = 4.5; 95% CI: 1.56-13.05, padj = 0.005). Infants colonized with B. breve at 1 week ( ORadj = 0.29; 95% CI: 0.09-0.95, padj = 0.04) and 3 months ( ORadj = 0.15; 95% CI: 0.05-0.44, padj = 0.00001) had a reduced risk of developing eczema. Furthermore, the presence of B. breve at 3 months was associated with a lower risk of atopic sensitization at 12 months ( ORadj = 0.38; 95% CI: 0.15-0.98, padj = 0.05). B. breve colonization patterns were influenced by maternal allergic status, household pets and number of siblings. Conclusions Temporal variations in Bifidobacterium colonization patterns early in life are associated with later development of eczema and/or atopic sensitization in infants at high risk of allergic disease. Modulation of the early microbiota may provide a means to prevent eczema in high-risk infants. [ABSTRACT FROM AUTHOR]

Background Regulatory T cells (Treg) play an essential role in early immune programming and shaping the immune response towards a pro-allergic or tolerant state. We evaluated cord blood Treg and cytokine responses to microbial and non-microbial stimuli in infants at high risk of allergic disease and their associations with development of allergic disease in the first year. Methods Cord blood mononuclear cells from 72 neonates were cultured with toll-like receptors ( TLR2) ligands: lipoteichoic acid ( LTA) and heat-killed Lactobacillus rhamnosus GG ( HKL); TLR4 ligand: lipopolysaccharide ( LPS); ovalbumin ( OVA); anti- CD3; or media for 48 h. Treg numbers and Treg cytokines were assessed in relation to allergic disease outcomes during the first year of life (eczema and atopic sensitization). Results Infants with eczema (n = 24) had reduced percentages of FoxP3hi CD25hi Treg in LTA (p = 0.01, adj p = 0.005) and HKL (p = 0.04, adj p = 0.02) stimulated cultures as well as reduced IL-10 (p = 0.01) production following HKL stimulation compared to those without eczema (n = 48). No differences in Treg or cytokine responses to LPS, OVA or anti- CD3 were seen. Infants who developed sensitization had lower percentages of Treg following TLR2 stimulation (but not other stimuli) compared to non-sensitized infants. Conclusions High-risk children who develop allergic disease in the first year of life have deficient Treg responses to microbial stimuli but not allergen from the time of birth, which may contribute to failure of immune tolerance development in infancy. [ABSTRACT FROM AUTHOR]