Impact of holder pasteurization on protein and eNAMPT/Visfatin content in human breast milk

Human milk proteins, a mixture of whey proteins including caseins, milk fat globule membrane (MFGM) proteins, various peptides, and their amino acids, play a crucial role in infant growth and development, as do non-nutritional bioactive components. The extracellular nicotinamide phosphoribosyltransferase (eNAMPT) or visfatin is a conserved cytokine/enzyme released by many mammalian cells, related to multiple metabolic and immune processes. Few investigations have been reported about detecting visfatin in skimmed milk and the hypothesis of its potential role in regulating infant adiposity through breast milk. Milk samples from a donated human milk bank were analyzed. After milk fractionation by centrifugation, skimmed milk and MFGM were analyzed by SDS-PAGE, MALDI-TOF mass spectrometry ELISA and/or Western blot. The ELISA assay showed a higher visfatin content in raw skimmed milk than in pasteurized samples. Meanwhile, MFGMs revealed higher visfatin levels in pasteurized samples. This is the first time visfatin has been identified associated with MFGM, and these results could suggest an affinity of this molecule for a lipidic environment.