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, skimmed milk and MFGM were analyzed by SDS-PAGE and MALDI-TOF mass spectrometry. An ELISA assay assessed visfatin content in skimmed milk, while MFGMs were analyzed by Western blot. The data showed a higher visfatin content in raw skimmed milk than in pasteurized samples. This is the first time visfatin has been identified associated with MFGM. Its levels appear to be higher in MFGM derived from pasteurized milk than in raw milk, an opposite result to that obtained by analyzing the skimmed milk samples. These results suggest the visfatin involvement in the features of MFGMs and their potential role for infants.