Metabolic signatures distinguish the impact of formula carbohydrates on disease outcome in a pretern piglet model of NEC

Authors: CALL, LEE - Children'S Nutrition Research Center (CNRC); STOLL, BARBARA - Children'S Nutrition Research Center (CNRC); OOSTERLOO, BERTHE - Children'S Nutrition Research Center (CNRC); AJAMI, NADIM - Baylor College Of Medicine; SHEIKH, FARIHA - Baylor College Of Medicine; WITTKE, ANJA - Mead Johnson; WAWORUNTU, ROSALINE - Mead Johnson; BERG, BRIAN - Mead Johnson; PETROSINO, JOSEPH - Baylor College Of Medicine; OLUTOYE, OLUYINKA - Baylor College Of Medicine; Burrin, Douglas - Doug

Submitted to: Microbiome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2018
Publication Date: 6/19/2018
Publication URL: https://handle.nal.usda.gov/10113/6743200
Citation: Call, L., Stoll, B., Oosterloo, B., Ajami, N., Sheikh, F., Wittke, A., Waworuntu, R., Berg, B., Petrosino, J., Olutoye, O., Burrin, D.G. 2018. Metabolic signatures distinguish the impact of formula carbohydrates on disease outcome in a pretern piglet model of NEC. BMC Microbiome. 6:111. https://doi.org/10.1186/s40168-018-0498-0
DOI: https://doi.org/10.1186/s40168-018-0498-0

Interpretive Summary: Necrotizing enterocolitis (NEC) is a very devastating, serious disease that causes an inflammatory process that leads to intestinal damage and sometimes death in premature infants. Although this condition has been known for more than 50 years, researchers still don’t understand exactly how it develops. In this study, we used a premature piglet model of NEC that closely reproduces the characteristics observed in human infants. Preterm infant formulas contain two main sugars, lactose and corn syrup solids. The main carbohydrates in human milk are lactose and oligosaccharides. We previously showed that feeding formula containing the sugar lactose protected preterm piglets from NEC. In comparison, piglets fed formula containing corn syrup solids had a higher risk of developing the condition. In this study, we confirmed that formula containing lactose protects against NEC, whereas corn syrup solids increase the risk of disease. We also examined the development of the bacterial communities or microbiome of the gut, and the metabolite profiles found in the gut and the blood. We found that that the communities of bacteria were not dramatically different between the lactose and the corn syrup solids group, but the metabolite profiles were very different. This work suggests that the metabolite profile is perhaps an early determinant of the development of this disease, as the microbiome begins to develop. These findings suggest that the lactose is the optimal sugar to include in preterm infant formula and that inclusion of corn syrup solids should be reconsidered.

Technical Abstract: Major risk factors for necrotizing enterocolitis (NEC) include premature birth and formula feeding in the context of microbial colonization of the gastrointestinal tract. We previously showed that feeding formula composed of lactose vs. corn syrup solids protects against NEC in preterm pigs; however, the microbial and metabolic effects of these different carbohydrates used in infant formula has not been explored. Our objective was to characterize the effects of lactose- and corn syrup solid-based formulas on the metabolic and microbial profiles of preterm piglets and to determine whether unique metabolomic or microbiome signatures correlate with severity or incidence of NEC. Preterm piglets (103 days gestation) were given total parenteral nutrition (2 days) followed by gradual (5 days) advancement of enteral feeding of formulas matched in nutrient content but containing either lactose (LAC), corn syrup solids (CSS), or 1:1 mix (MIX). Gut contents and mucosal samples were collected and analyzed for microbial profiles by sequencing the V4 region of the 16S rRNA gene. Metabolomic profiles of cecal contents and plasma were analyzed by LC/GC mass spectrometry. NEC incidence was 14, 50, and 44% in the LAC, MIX, and CSS groups, respectively. The dominant classes of bacteria were Bacilli, Clostridia, and Gammaproteobacteria. The number of observed OTUs was lowest in colon contents of CSS-fed pigs. CSS-based formula was associated with higher Bacilli and lower Clostridium from clusters XIVa and XI in the colon. NEC was associated with decreased Gammaproteobacteria in the stomach and increased Clostridium sensu stricto in the ileum. Plasma from NEC piglets was enriched with metabolites of purine metabolism, aromatic amino acid metabolism, and bile acids. Markers of glycolysis, e.g., lactate, were increased in the cecal contents of CSS-fed pigs and in plasma of pigs which developed NEC. Feeding formula containing lactose is not completely protective against NEC, yet selects for greater microbial richness associated with changes in Bacilli and Clostridium and lower NEC incidence. We conclude that feeding preterm piglets a corn syrup solid vs. lactose-based formula increases the incidence of NEC and produces distinct metabolomic signatures despite modest changes in microbiome profiles.