Introduction of milk phospholipids and lipids in infant formula promotes the intestinal immune system maturation in neonatal piglets

Milk phospholipids and lipids have been associated with modulation of membrane properties and intestinal inflammation, but less is known on their effects on the development of gut physiology and immune system in neonates. Two infant formulas differing by the presence of bovine milk phospholipids and lipids (CRTL: a standard-based formula adapted to neonatal pig requirement; PLUS: CRTL plus phospholipids and lipids) were distributed with an automatic milk feeder to 36 piglets during the nursing period (i.e. 28 days). The residual immunoreactivity of β-lactoglobulin and caseins present in the digestive compartments was determined by ELISA. The intestinal permeability was evaluated using Ussing chambers. Mononuclear cells were isolated from mesenteric lymph nodes (MLN) and cultured in presence of a mitogen to evaluate their cytokine pattern. Physiological data were compared to previous data obtained on same aged-sow suckling piglets. Moreover, immunoregulatory capacity of peptide and lipid fractions extracted from jejunal digestas was evaluated in vitro on mitogen-stimulated MLN cells from sow suckling 7 days-old piglets. The immunoreactivity of β-lactoglobulin and caseins was higher in PLUS than CRTL digestas both in jejunum and ileum. Higher intestinal thickness observed in PLUS group was not associated with changes in permeability. The reduced mononuclear cell density in MLN of PLUS-fed piglets indicated a modification of the mobilization or recruitment of MLN cells. PLUS formula also increased IFNγ secretion suggesting an improved intestinal immune system maturation such as observed in sow suckling piglets. Finally, a major immunosuppressor effect of the lipid fractions was evidenced with both formulas. However, the less severe inhibitor activity of lipids extracted from PLUS digesta may participate in the in vivo increased IFNγ secretion in PLUS formula-fed piglets. In conclusion, introduction of milk phospholipids and lipids in infant formula induced modifications of the intestinal immune system maturation that may promote intestinal immune system maturation similar to sow suckling piglets