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Background: Probiotic supplementation in early life may be effective for preventing eczema. Previous studies have suggested that prenatal administration may be particularly important for beneficial effects., Objective: We examined whether prenatal treatment with the probiotic Lactobacillus rhamnosus GG (LGG) can influence the risk of eczema during infancy., Methods: We recruited 250 pregnant women carrying infants at high risk of allergic disease to a randomized controlled trial of probiotic supplementation (LGG 1.8 × 10(10) cfu/day) from 36 weeks gestation until delivery. Infants were assessed during their first year for eczema or allergic sensitization. Immunological investigations were performed in a subgroup. Umbilical cord blood was examined for dendritic cell and regulatory T cell numbers and production of TGFβ, IL-10, IL-12, IL-13, IFN-γ and TNFα. Maternal breast milk was examined for total IgA, soluble CD14 and TGFβ., Results: Prenatal probiotic treatment was not associated with reduced risk of eczema (34% probiotic, 39% placebo; RR 0.88; 95% CI 0.63, 1.22) or IgE-associated eczema (18% probiotic, 19% placebo; RR 0.94; 95% CI 0.53, 1.68). Prenatal probiotic treatment was not associated with any change in cord blood immune markers, but was associated with decreased breast milk soluble CD14 and IgA levels., Conclusions: Prenatal treatment with Lactobacillus rhamnosus GG was not sufficient for preventing eczema. If probiotics are effective for preventing eczema, then a postnatal component to treatment or possibly an alternative probiotic strain is necessary., (© 2010 John Wiley & Sons A/S.)

Background: Several clinical trials suggest that probiotics may have a role in the prevention of eczema. The optimal timing and mechanisms underlying this intervention are not clear. In particular it is not known whether such treatment works during pregnancy or whether postnatal exposure is important., Objective: We investigated whether the probiotic Lactobacillus rhamnosus strain GG (LGG) influences fetal immune responses when administered to pregnant women, as a possible mechanism for its protective effects against the development of eczema., Methods: Peripheral blood mononuclear cell from 11 adults treated with LGG, and cord blood mononuclear cells (CBMCs) from 73 women participating in a randomized controlled trial of LGG treatment were cultured with heat-killed LGG, ovalbumin (OVA) or without stimulus. Cells were analysed by flow cytometry and real-time PCR for markers of dendritic cell (DC) phenotype, T cell proliferation and regulation. Cytokine secretion was analysed in culture supernatants by multiplex cytokine assay., Results: LGG treatment of adults led to systemic immune responses suggestive of antigen-specific tolerance including reduced CD4(+) T cell proliferation to heat-killed LGG (30% reduction; P=0.03). LGG treatment of pregnant women did not influence CD4(+) T cell proliferation, forkhead box P3 expression, DC phenotype or cytokine secretion in CBMCs cultured with heat-killed LGG or OVA., Conclusion: LGG treatment of pregnant women fails to influence fetal antigen-specific immune responses. This suggests that modulation of fetal immune responses may not be a major mechanism by which probiotics such as LGG prevent eczema.