Development of the early-life gut microbiome and associations with eczema in a prospective Chinese cohort.

The first few years of life is a key period for the development of the gut microbiome. However, our current understanding of this topic is largely biased toward Western populations. In this study, we characterized the development and determinants of the gut microbiome in a prospective cohort of 112 term Chinese children by sequencing 713 stool samples collected at nine time points from birth to 3 years of age using 16S rRNA gene sequencing. We revealed alterations in the composition and alpha and beta diversities of the gut microbiota across the first 3 years of life. We identified mode of delivery, feeding mode, and intrapartum antibiotics as the major determinants of the early-life gut microbiome, the effects of all of which persisted up to 12 months. Importantly, by conducting a nested case-control study, we showed that alterations in the infant gut microbiota precede the development of eczema. Interestingly, we identified a depletion of Bacteroides and an enrichment of Clostridium sensu stricto 1 in the gut microbiome of infants with eczema at 1 year old. The same patterns were also observed in C-section-born infants within the same time frames, suggesting a role of the gut microbiota in previously reported associations between C-section and increased risk of eczema. Our study has revealed important associations between the gut microbiome and eczema in infancy and has established the basis for potential prevention/treatment of eczema via modulation of the gut microbiota. IMPORTANCE Eczema is a major allergic disease in children, which is particularly prevalent in Chinese children during their first year of life. In this study, we showed that alterations in the infant gut microbiota precede the development of eczema in a prospective Chinese cohort. In particular, we discovered enrichments of the genera Clostridium sensu stricto 1 and Finegoldia in the cases at 3 and 1 month of age, respectively, which may represent potential targets for intervention to prevent eczema. Besides, we identified a depletion of Bacteroides from 1 to 6 months of age and an enrichment of Clostridium sensu stricto 1 at 3 months in the eczema cases, patterns also observed in C-section-born infants within the same time frames, providing first evidence to support a role of the gut microbiota in previously reported associations between C-section and increased risk of eczema in infancy.