Human milk miRNAs associate to maternal dietary nutrients, milk microbiota, infant gut microbiota and growth

Background Maternal diet influences the milk composition, yet little information is available on the impact of maternal diet on milk miRNAs expression. Further, the association of milk miRNAs to maternal diet and milk microbiota is not explored. In addition, the role of milk miRNAs on the infant gut microbiota, infant growth and development has not been investigated. Methods Milk samples were collected from 60 healthy lactating women at <15d post-partum, HTG transcriptome assay was performed to examine milk miRNA profile. Maternal clinical and dietary clusters information were available and infant anthropometric measures were followed up to one year of age. Milk and infant microbiota were analyzed by 16S rRNA gene sequencing and integrative multi-omics data analysis was performed to identify potential association between microRNA, maternal dietary nutrients and microbiota. Results Discriminant analysis revealed that the milk miRNAs were clustered into groups according to the maternal protein source. Interestingly, 34 miRNAs were differentially expressed (P adj < 0.05) between maternal dietary clusters (Cluster 1: enriched in plant protein and fibers and Cluster 2: enriched in animal protein), with 33 miRNAs downregulated in the plant protein group relative to animal protein group. Pathway analysis revealed that the top enriched pathways (P adj < 0.01) were involved in cell growth and proliferation processes. Furthermore, significant features contributing to the clustering were associated with maternal dietary nutrients and milk microbiota (r > 0.70). Further, miR-378 and 320 family miRNAs involved in adipogenesis were positively correlated (r = 0.5) to the infant BMI-z-scores, weight, and weight for length-z-scores at 6 months of age. Conclusions Maternal dietary source impacts the milk miRNA expression profile. Further, miRNAs were associated with maternal dietary nutrients, milk microbiota and to the infant gut microbiota and infant growth and development. Clinical Trial The study is registered in ClinicalTrials.gov. The identification number is NCT03552939.