Changes in peripheral immune populations during pregnancy and modulation by probiotics and ω-3 fatty acids.

Allergic diseases have become a major health problem, partly due to reduced microbial stimulation and a decreased dietary ω-3/ω-6 long-chain polyunsaturated fatty acid ratio. Prenatal exposures have been reported to influence allergy development, possibly induced via changes in maternal immune regulation. In a randomized double-blind placebo-controlled multicenter allergy prevention trial (PROOM-3), pregnant women were recruited at gestational week 20, and randomized to four study groups, one receiving both L. reuteri oil drops and ω-3 PUFA capsules (n = 22), the second receiving ω-3 PUFA supplementation and placebo regarding L. reuteri (n = 21), the third receiving L. reuteri and placebo regarding ω-3 PUFA (n = 22) and the fourth group receiving placebo capsules and placebo oil drops (n = 23). In this substudy, supplemental and pregnancy-related effects on maternal peripheral immune cell populations during pregnancy were assessed by flow cytometry immune phenotyping at gestational week 20, 32 and 4 days after delivery. The numbers of activated and regulatory T (Treg) cells (CD45RA- Foxp3++/CD45RA+Foxp3+) were reduced after delivery, with the lowest count in the L. reuteri supplemented group compared with the placebo group 4 days after delivery, while the ω-3 PUFA group did not differ from the placebo group. Several treatment-independent changes were observed during and after pregnancy in lymphocytes (CD4+/8+/19+/56+/45RA+/-), CD14+16+/- monocytes, and in subpopulations of T helper cells (Th) CD4+CD45RA-Tbet+ (Th1) and CD4+CD45RA-RORC+ (Th17) cells. In conclusion, probiotic supplementation to the mother during the second half of pregnancy resulted in immunomodulatory effects among activated and resting Treg cells. Furthermore, several systemic immune modifying effects of pregnancy were observed.

Oral microbiota maturation during the first 7 years of life in relation to allergy development.

BACKGROUND: Allergic diseases have become a major public health problem in affluent societies. Microbial colonization early in life seems to be critical for instructing regulation on immune system maturation and allergy development in children. Even though the oral cavity is the first site of encounter between a majority of foreign antigens and the immune system, the influence of oral bacteria on allergy development has not yet been reported. OBJECTIVE: We sought to determine the bacterial composition in longitudinally collected saliva samples during childhood in relation to allergy development. METHODS: Illumina sequencing of the 16S rDNA gene was used to characterize the oral bacterial composition in saliva samples collected at 3, 6, 12, 24 months, and 7 years of age from children developing allergic symptoms and sensitization (n = 47) and children staying healthy (n = 33) up to 7 years of age. RESULTS: Children developing allergic disease, particularly asthma, had lower diversity of salivary bacteria together with highly divergent bacterial composition at 7 years of age, showing a clearly altered oral microbiota in these individuals, likely as a consequence of an impaired immune system during infancy. Moreover, the relative amounts of several bacterial species, including increased abundance of Gemella haemolysans in children developing allergies and Lactobacillus gasseri and L. crispatus in healthy children, were distinctive during early infancy, likely influencing early immune maturation. CONCLUSION: Early changes in oral microbial composition seem to influence immune maturation and allergy development. Future experiments should test the probiotic potential of L. gasseri and L. crispatus isolates.

Low gut microbiota diversity in early infancy precedes asthma at school age.

BACKGROUND: Low total diversity of the gut microbiota during the first year of life is associated with allergic diseases in infancy, but little is known how early microbial diversity is related to allergic disease later in school age. OBJECTIVE: To assess microbial diversity and characterize the dominant bacteria in stool during the first year of life in relation to the prevalence of different allergic diseases in school age, such as asthma, allergic rhinoconjunctivitis (ARC) and eczema. METHODS: The microbial diversity and composition was analysed with barcoded 16S rDNA 454 pyrosequencing in stool samples at 1 week, 1 month and 12 months of age in 47 infants which were subsequently assessed for allergic disease and skin prick test reactivity at 7 years of age (ClinicalTrials.gov ID NCT01285830). RESULTS: Children developing asthma (n = 8) had a lower diversity of the total microbiota than non-asthmatic children at 1 week (P = 0.04) and 1 month (P = 0.003) of age, whereas allergic rhinoconjunctivitis (n = 13), eczema (n = 12) and positive skin prick reactivity (n = 14) at 7 years of age did not associate with the gut microbiota diversity. Neither was asthma associated with the microbiota composition later in infancy (at 12 months). Children having IgE-associated eczema in infancy and subsequently developing asthma had lower microbial diversity than those that did not. There were no significant differences, however, in relative abundance of bacterial phyla and genera between children with or without allergic disease. CONCLUSION AND CLINICAL RELEVANCE: Low total diversity of the gut microbiota during the first month of life was associated with asthma but not ARC in children at 7 years of age. Measures affecting microbial colonization of the infant during the first month of life may impact asthma development in childhood.

Oral administration of Lactobacillus reuteri during the first year of life reduces caries prevalence in the primary dentition at 9 years of age.

The aim of this study was to evaluate the effect on oral health, at age 9 years, of daily oral supplementation with the probiotic Lactobacillus reuteri, strain ATCC 55730, to mothers during the last month of gestation and to children through the first year of life. The study was a single-blind, placebo-controlled, multicenter trial involving 113 children: 60 in the probiotic and 53 in the placebo group. The subjects underwent clinical and radiographic examination of the primary dentition and carious lesions, plaque and gingivitis were recorded. Saliva and plaque were sampled for determination of mutans streptococci (MS) and lactobacilli (LB) in saliva and plaque as well as salivary secretory IgA (SIgA). Forty-nine (82%) children in the probiotic group and 31 (58%) in the placebo group were caries-free (p < 0.01). The prevalence of approximal caries lesions was lower in the probiotic group (0.67 ± 1.61 vs. 1.53 ± 2.64; p < 0.05) and there were fewer sites with gingivitis compared to the placebo group (p < 0.05). There were no significant differences between the groups with respect to frequency of toothbrushing, plaque and dietary habits, but to intake of fluoride supplements (p < 0.05). There were no intergroup differences with respect to L. reuteri, MS, LB or SIgA in saliva. Within the limitation of this study it seems that daily supplementation with L. reuteri from birth and during the first year of life is associated with reduced caries prevalence and gingivitis score in the primary dentition at 9 years of age.

Pre- and post-natal Lactobacillus reuteri supplementation decreases allergen responsiveness in infancy.

BACKGROUND: We have previously shown that Lactobacillus reuteri supplementation from pregnancy week 36 and to the infant through the first year of life decreased the prevalence of IgE-associated eczema at 2 years. The underlying immunological mechanisms are unknown, however. OBJECTIVE: To investigate the immunomodulatory effect of probiotic supplementation on allergen- and mitogen-induced immune responses in children until 2 years of age. METHODS: Blood mononuclear cells were collected at birth, 6, 12 and 24 months from 61 children (29 probiotic and 32 placebo treated) and cultured with ovalbumin, birch and cat extract and Phytohaemagglutinin (PHA). Cytokine and chemokine secretion was determined using an in-house multiplexed Luminex assay and ELISA. Real-time PCR was performed to investigate the Ebi3, Foxp3, GATA-3 and T-bet mRNA expression. RESULTS: Probiotic treatment was associated with low cat-induced Th2-like responses at 6 months (IL-5, P = 0.01, and IL-13, P = 0.009), with a similar trend for IL-5 at 12 months (P = 0.09). Cat-induced IFN-γ responses were also lower after probiotic than after placebo treatment at 24 months (P = 0.007), with similar findings for the anti-inflammatory IL-10 at birth (P = 0.001) and at 12 months (P = 0.009). At 24 months, Th2-associated CCL22 levels were lower in the probiotic than in the placebo group after birch stimulation (P = 0.02), with a similar trend after ovalbumin stimulation (P = 0.07). Lower CCL22 levels were recorded at 12 and 24 months (P = 0.03 and P = 0.01) after PHA stimulation. CONCLUSION AND CLINICAL RELEVANCE: Lactobacillus reuteri supplementation decreases allergen responsiveness and may enhance immunoregulatory capacity during infancy. L. reuteri supplementation from week 36 and during the first year of life significantly decreases IgE-associated eczema and lowers allergen and mitogen responsiveness.

A Th1/Th2-associated chemokine imbalance during infancy in children developing eczema, wheeze and sensitization.

BACKGROUND: Analyses of circulating chemokines offer novel tools to investigate the T helper (Th)1/Th2 imbalance in allergic disease in vivo. OBJECTIVE: To relate circulating Th1- and Th2-associated chemokines in infancy to allergic disease, sensitization and probiotic supplementation. METHODS: Circulating levels of Th1-associated CXC-chemokine ligand (CXCL)9, CXCL10 and CXCL11 and Th2-associated CC-chemokine ligand (CCL)17 and CCL22 were assessed with Luminex and CCL18 with enzyme-linked immunosorbent assay at birth (n=109), 6 (n=104), 12 (n=116) and 24 months (n=123) in 161 infants completing a double-blind placebo-controlled allergy prevention trial with Lactobacillus reuteri during the last month of gestation and through the first year of life. The infants were followed regarding the development of allergic disease and sensitization until 2 years of age. RESULTS: The Th2-associated chemokines CCL17 and CCL22 were the highest at birth and then decreased, whereas CCL18 and the Th1-associated chemokines increased with age. High Th2-associated chemokine levels were observed in children developing allergic disease. Sensitization was preceded by elevated levels of the Th2-associated CCL22 and reduced levels of the Th1-associated CXCL11 already at birth. The Th2-associated CCL17 was also elevated at birth in infants developing recurrent wheeze. A high Th2/Th1 ratio (CCL22/CXCL10) at birth associated with both sensitization and eczema development. The presence of L. reuteri in stool in the first week of life was associated with low CCL17 and CCL22 and high CXCL11 levels at 6 months of age. High Th1-associated chemokine levels were associated with day-care. CONCLUSION AND CLINICAL RELEVANCE: Allergic disease and sensitization in infancy was associated with low circulating Th1- and high Th2-associated chemokine levels already from birth. Circulating chemokines are useful for investigating the Th1/Th2 imbalance in allergic disease in vivo. Elucidation of the role of chemokines in allergic diseases may lead to future treatments (ClinicalTrials.gov NCT01285830).