Investigating the presence of eNAMPT/visfatin in human skimmed milk and milk fat globule membrane before and after Holder pasteurization.

Maternal milk is the perfect nutrition for infants of all species. Human milk proteins, a mixture of whey proteins including caseins, milk fat globules membrane proteins (MFGM), various peptides and their amino acids, play a crucial role in the growth and development of the child also as non­nutritional bioactive components. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT/visfatin), is a conserved cytokine/enzyme released by many mammalian cells correlated with multiple metabolic and immune processes (Audrito et al., 2020). After visfatin detection in skimmed milk and the hypothesis of its potential role in regulating infant adiposity through maternal milk (Bienertová­Vašků et al., 2012), no other investigations have been reported. We have analyzed milk samples from human milk donated bank. After milk fractionation (2,000 x g for 30 minutes at 10°C) both skimmed milk and MFGM were analyzed by SDS­PAGE and MALDI­TOF mass spectrometry. In order to evaluate eNAMPT/visfatin content in skimmed milk ELISA assay was performed, while MFGMs were investigated through immunoblot. Data show a higher eNAMPT/visfatin content in raw skimmed milk if compared to pasteurized samples. In addition, we identify eNAMPT/visfatin associated with MFGM proteins, never described before, where their levels seem to be higher in MFGM proteins derived from pasteurized milk if compared to raw milk, an opposite result compared milk samples. Overall, these results may suggest an involvement of eNAMPT/visfatin in the reshuffling of MFGM induced by the Holder pasteurization process.