Maternal Diet Determines Milk Microbiome Composition and Offspring Gut Colonization in Wistar Rats

Mother's milk contains a unique microbiome that plays a relevant role in offspring health. We hypothesize that maternal malnutrition during lactation might impact the microbial composition of milk and affect adequate offspring gut colonization, increasing the risk for later onset diseases. Then, Wistar rats were fed ad libitum (Control, C) food restriction (Undernourished, U) during gestation and lactation. After birth, offspring feces and milk stomach content were collected at lactating day (L)4, L14 and L18. The V3-V4 region of the bacterial 16S rRNA gene was sequenced to characterize bacterial communities. An analysis of beta diversity revealed significant disparities in microbial composition between groups of diet at L4 and L18 in both milk, and fecal samples. In total, 24 phyla were identified in milk and 18 were identified in feces, with Firmicutes, Proteobacteria, Actinobacteroidota and Bacteroidota collectively representing 96.1% and 97.4% of those identified, respectively. A higher abundance of Pasteurellaceae and Porphyromonas at L4, and of Gemella and Enterococcus at L18 were registered in milk samples from the U group. Lactobacillus was also significantly more abundant in fecal samples of the U group at L4. These microbial changes compromised the number and variety of milk-feces or feces-feces bacterial correlations. Moreover, increased offspring gut permeability and an altered expression of goblet cell markers TFF3 and KLF3 were observed in U pups. Our results suggest that altered microbial communication between mother and offspring through breastfeeding may explain, in part, the detrimental consequences of maternal malnutrition on offspring programming.

Gut DYSBIOSIS and altered barrier function precedes the appearance of metabolic syndrome in a rat model of nutrient-induced catch-up growth

Nutritional restriction early in life followed by catch-up growth has been associated with increased risk of metabolic syndrome in adulthood. To elucidate whether altered gut colonization underlies the mechanisms responsible of this predisposition gut microbiome was studied before or afterwards catch-up growth. Offspring of dams fed ad libitum (C) or undernourished during pregnancy and suckling (U), were weaned onto high-fat diet (HFD) for 22 weeks (CHF and UHF, respectively) or continued on their diet. HF-feeding induced glucose intolerance (P<.05), insulin resistance (P<.001), and white adipose tissue inflammation (P<.001) in UHF rats compared to CHF. Analyses of gut microbial composition before catch-up growth revealed reduced F/B ratio and significant expansion of the mucolytic genera Akkermansia (P<.05) and Desulfovibrio (P<.05) in U pups. Although relative abundance of Akkermansia remained elevated to adulthood in U rats, HFD normalized its levels to C and CHF. Food-restriction increased intestinal permeability causing disorganization on the tight-junction proteins of colonic epithelium, Zonula Occludens-1 (ZO-1) and occludin, and reducing the mucus thickness layer in U adult rats. The levels of ZO-1 and occludin were not recovered in U rats after HF-feeding. This event was correlated with increased circulating levels of bacterial lipopolysaccharides in both U and UHF adult rats. Even more, serum lipopolysaccharides were already elevated in U rats compared to C group (P<.001) at weaning. Thus, gut dysbiosis and chronic endotoxemia observed in U rats, even before catch-up growth, might anticipate a pro-inflammatory milieu promoting metabolic diseases when fed hyperlipidic diets.