Postnatal cecal and cecal content luminal miRNA signatures in C57BL/6-VAF/Elite® mice

The interplay between the intestinal microbiota and host is critical to intestinal ontogeny and homeostasis. MicroRNAs (miRNAs) may be an underlying link. Intestinal miRNAs are microbiota-dependent and when shed in the lumen, affect resident microorganisms. Yet, longitudinal relationships between intestinal tissue miRNAs, luminal miRNAs, and luminal microorganisms have not been elucidated, especially in early life. Here, we investigated the postnatal cecal miRNA and microbiota populations, their relationship, and their impact on intestinal maturation in specific and opportunistic pathogen free mice; we also assessed if they can be modified by an intervention with allochthonous probiotic lactobacilli. We report that cecal and cecal content miRNA and microbiota signatures are temporally regulated, correlated, and modifiable by probiotics with implications for intestinal maturation. These findings help with understanding causal relationships within the gut ecosystem and provide a basis for preventing and managing their alterations in diseases throughout life. C57BL/6-VAF/Elite® 6-8-week-old female mice were randomized to the control (n=7, receiving sterile drinking water) or probiotics (n=6; receiving a probiotic mixture of Lacticaseibacillus rhamnosus R0011 and L. helveticus R0052 (ratio 95:5) in the drinking water) group starting one week before breeding. On Day 7 (D7), mice were bred harem-style. Pregnant dams were housed individually and continued receiving sterile water with or without probiotics throughout the pregnancy until parturition at D28 (postnatal day (PND) 0). The litters were followed longitudinally; offspring were euthanized at PND14, PND21, and PND36, and cecum and its content (paired) were collected for total RNA extraction and miRNA analysis. For the control group, a total of 12 samples were analyzed: 1 male offspring/dam/PND (n = 4 male offspring/PND). For the probiotics group, a total of 12 samples were analyzed across all dams: n = 3, n = 5, and n = 4 male offspring for PND14, PND21, and PND36, respectively.