Formula diet driven microbial diversity and immunological consequence in small intestine of neonatal porcine model

Abstract

Several studies have shown that the development and function of the neonatal immune system is enhanced by breast feeding compared to formula feeding. It is important to understand the interaction between infant feeding regimens and the developing GI tract, to identify the protective components of breast milk and mechanisms attributed in immune system development. We used the neonatal piglet model in which piglets were exclusively fed cow's milk formula (n=12) or sow fed (n = 12) from postnatal day (PND) 2 to PND 21 to study the microbiome and GI immune system development. Microbial richness and diversity were assessed from small intestinal contents (duodenum, jejunum and ileum) via 16sRNA amplicon sequencing using V4 variable primers. Data analyses was carried out by using QIIME 1.9.1. Principal component analyses (PCoA) indicated clear separation of the diet groups in all three regions of small intestine. The duodenum showed a significantly more diverse microbial population than jejunum and ileum (FDR corrected, P<0.001) in both sow‐ and formula‐fed groups. However, formula feeding was associated with more microbial diversity in comparison to sow‐diet (FDR corrected, P<0.01). In sow‐fed piglets, Lactobacillus spp was the most abundant and Clostridia spp was the next abundant (FDR corrected, P<0.01) with 3 to 5‐fold higher amounts observed in comparison to formula fed piglets; whereas, Gamma proteobacteria was observed to be 3 to 5‐fold greater in formula fed piglets (FDR corrected, P<0.01) in comparison to sow‐diet. We also assessed histomorphometric changes of Peyer's patches, surface area and inflammatory responses of ileum. In formula‐fed piglets, the lymphoid follicle size (P<0.01) and germinal centers (P <0.01) within the Peyer's patch were significantly decreased compared to to sow‐fed, suggesting less‐developed immune system. The surface area of the ileum mucosa significantly increased in formula group compared to sow‐fed pigs (P <0.01) with no significant differences in growth rate or body weights between the diet groups. However, sow‐fed piglets had relatively longer small intestine than formula‐fed piglets (P<0.05). The decrease in small intestine length in the formula group corresponds to 14%, suggesting compensation for surface area and possibly for nutrient absorption. Furthermore, in ileum, formula diet induced significant down‐regulation of anti‐inflammatory IL‐10 (P <0.01) at protein level, indicating that formula diet impacts the immune response. We conclude that feeding a milk formula diet alters the microbiome, small intestine morphology and gut‐associated lymphoid tissue development and immune response.Funding: USDA‐ARS Project 6026‐51000‐010‐05S.Support or Funding InformationUSDA‐ARS Project 6026‐51000‐010‐05S.