Factors Influencing the Infant Gut Microbiome at Age 3-6 months: Findings from the ethnically diverse Vitamin D Antenatal Asthma Reduction Trial (VDAART).
J Allergy Clin Immunol. 2016 Oct 13. Epub 2016 Aug 13. PMID: 27746239
Joanne E Sordillo
BACKGROUND: The gut microbiome in infancy influences immune system maturation, and may have an important impact allergic disease risk.
OBJECTIVE: To determine how prenatal and early life factors impact the gut microbiome in a relatively large, ethnically diverse study population of infants at 3-6 months of age, who were enrolled in VDAART, a clinical trial of vitamin D supplementation in pregnancy to prevent asthma and allergies in offspring.
METHODS: We performed 16S rRNA gene sequencing on 333 infants' stool samples. Microbial diversity was computed using the Shannon Index. Factor analysis applied to the top 25 most abundant taxa revealed four underlying bacterial co-abundance groups; the first dominated by Firmicutes (Lachnospiraceae/ Clostridiales), the second by Proteobacteria (Klebsiella/Enterobacter), the third by Bacteriodetes, and the fourth by Veillonella. Scores for co-abundance groups were used as outcomes in regression models, with prenatal/birth and demographic characteristics as independent predictors. Multivariate analysis, using all microbial community members, was also conducted.
RESULTS: Caucasian race/ethnicity was associated with lower diversity but higher Bacteroidetes co-abundance scores. Caucasian infants had lower Proteobacteria scores as compared to African Americans. C-section birth was associated with higher diversity, but with decreased Bacteroidetes co-abundance scores. Firmicutes and Proteobacteria scores were higher for infants born by C-section. Breastfed infants had lower proportions of Clostridiales. Cord blood vitamin D was linked to increased Lachnobacterium, but decreased Lactococcus.
CONCLUSIONS: The findings presented here suggest that race, mode of delivery, breastfeeding and cord blood vitamin D levels are associated with infant gut microbiome composition, with possible long-term implications for immune system modulation and asthma/allergic disease incidence.