Huurre A, Laitinen K, Rautava S, Korkeamäki M, Isolauri E. Clin Exp Allergy. 2008;38(8):1342–1348
PURPOSE OF THE STUDY. To explore factors in infant sensitization and the effect of probiotics.
STUDY POPULATION. The researchers evaluated 171 mother-infant pairs from an ongoing, placebo-controlled, double-blind study with nutrition modulation through dietary counseling and probiotic supplementation.
METHODS. Mothers with no chronic or metabolic disease before or during early pregnancy had dietary counseling and were randomly assigned to receive either probiotics (Lactobacillus rhamnosus strain GG and Bifidobacterium lactis Bb12) or placebo from the first trimester of pregnancy to the end of exclusive breastfeeding. Atopic sensitization of the infants was assessed by skin-prick test to cow's milk, egg white, wheat, rice, gliadin, cod, soya bean, birch, 6 grasses, cat, dog, Dermatophagoides pteronyssinus (dust mite), latex, potato, carrot, and banana at the ages of 6 and 12 months. The mothers were skin tested for these antigens as well as peanut, hazelnut, alder, and mugwort in their third trimester of pregnancy. Infants were examined at 1, 6, and 12 months of age. Breast milk samples were collected immediately after birth and 1 month after delivery. Concentrations of transforming growth factor β2 (TGF-β2) and soluble CD14 were measured in breast milk by using commercial sandwich enzyme-linked immunosorbent assays. The concentrations of interferon γ, tumor necrosis factor α, interleukin (IL)-10, IL-6, IL-4, and IL-2 were measured via flow cytometry. Infant sensitization assessed by skin-prick test at the age of 12 months was the primary variable. The effects of probiotic intervention, allergy status of the mother, and duration of total and exclusive breastfeeding on infant sensitization were analyzed by using the χ2 test. The t test for independent samples was used to compare the probiotic and placebo groups.
RESULTS. At the age of 12 months, 30% of the infants showed ≥1 positive reactions on the skin-prick test. Allergic disease and positive skin-prick test results in the mother were likely to be associated with increased risk of sensitization in the child. The total duration of breastfeeding affected the risk of sensitization in the infant according to the allergy status of the mother; the risk of sensitization increased for infants with allergic mothers breastfeeding for >6 months or exclusively breastfeeding for >2.5 months (odds ratio: 4.8; P = .005). Probiotic supplementation had a protective effect against sensitization in infants with mothers with sensitization. The concentration of TGF-β2 tended to be higher in the colostrum of the mothers in the probiotic group, compared with those in the placebo group (probiotic/placebo ratio: 1.5; P = .02). A low level of TGF-β2 in the colostrum seemed to be associated with a positive skin-prick test result in the infant. Probiotic supplementation had a protective effect against sensitization in a subgroup of infants with maternal sensitization: 26% of the infants in the probiotic group versus 50% in the placebo group had positive skin-prick test results. Atopic eczema was diagnosed at the age of 12 months in 9.7% of the infants in the probiotic group and in 17.6% of the infants in the placebo group.
CONCLUSIONS. Maternal skin-prick test reactivity accompanied by allergic disease may increase infant vulnerability to sensitization. Breastfeeding by atopic mothers increases the likelihood of sensitization in infants. Probiotics provide protection from sensitization in infants at high risk.
REVIEWERS COMMENTS. The authors of this article raise interesting questions about the impact of breast milk in the prevention of atopic disease. They noted a protective benefit of probiotic supplementation in their study population and theorized that the possible mechanism for this protective effect is through an increase in antiinflammatory TGF-β2 in breast milk. The authors noted possible limitations of probiotics, including appropriate selections of antiinflammatory probiotic strains and risk of disease in the infant. This is a fascinating area for future study.
- Copyright © 2009 by the American Academy of Pediatrics