Submitted to: Biology of the Neonate
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2006
Publication Date: 1/11/2007
Citation: Golden, C., McMahon, M., Thampi, P., Badger, T.M., Nagarajan, S., Helm, R.M. 2007. Diet regulates the development of gut-associated lymphoid tissues in neonatal piglets. Neonatology. 91(4):248-255.
Interpretive Summary: Newborns do not have a good way to fight infections and rely on mother's breast milk for protection from germs as well as their nutritional needs. Human milk is very complex, and scientists are still trying to unravel and understand what makes it such a good source of nutrition for rapidly growing and developing infants. Even though formula-fed babies do not receive infection-fighting antibodies in formula, they received four to six month supplies of these antibodies through the maternal bloodstream prior to delivery. We studied newborn piglets because they have an immune and digestive system that is very similar to the newborn infant. Another advantage of this model over rodents models is that the piglet can easily be bottle-fed, whereas rodents can not. The results of the current study demonstrated that formula-fed piglets had a reduced maturation of the immune system as compared to breast-fed piglets. Furthermore, we demonstrated that the pig can be used as a model for human infants. Future studies will focus on more careful characterization of nutritional status and immune function in formula-fed piglets and how various diets, such as soy formula, affect grow, development and function of the GI tract.
Technical Abstract: During the immediate postnatal period tissue growth in the pig gastrointestinal tract increases by up to 80%. Controversy exists concerning diet-induced changes to the gut epithelial and immunocytes that occur during weaning. Comparisons of bovine milk protein digestion in 3-week-old piglets and 3-month-old infants suggest that neonatal piglets may be a good model for studying casein protein-gastrointestinal interactions and immune development of the gastrointestinal associated lymphoid tissue (GALT). The purpose of this study was to compare growth and development, intestinal morphology, and GALT immune maturation in sow-reared littermates to that of early-weaned piglets fed a casein-based liquid diet. Piglets were breast-fed by the sow or were weaned at 48 h to a casein-based diet (formula-fed) that provided National Research Council recommended nutrients. The gross physical appearance of piglets, the gastrointestinal tract and other organs at necropsy revealed normal organogenesis in both cohorts. At postnatal day 21, body weight gain, liver and kidney weight, small intestine length and weight to length ratio were greater in formula-fed piglets compared to sow-reared piglets (p<0.05). The CD21+ B-lymphocyte component of the gut-associated lymphoid tissue (GALT) and systemic immune system was reduced in formula-fed piglets. This was associated with lower circulating IgG and IgM levels in formula-fed compared to breast-fed neonatal piglets (p < 0.001). These data indicate that feeding a casein-based formula to newborn piglets supports excellent weight gains, but may compromise development of GALT and systemic immune systems relative to breast feeding. This neonatal piglet animal model should be adequate to identify dietary influences affecting the immune development of the neonate.