Milk fat globule membrane (MFGM) proteins constitute a milk fraction currently of great interest, as they appear to significantly contribute to milk protective role. We investigated these proteins in human preterm colostrum and milk. For the former we found a peculiar 2-DE pattern, with a spot concentration at low molecular weight, which mass spectrometry analysis showed to be fragments belonging to some MFGM proteins with a well-known biological and especially immunological role: lactadherin, membrane-associated lactoferrin, butyrophilin, clusterin and heavy-chain immunoglobulin. Since we were able to rule out protease activity after specimen collection, we hypothesize the localization of the proteolytic enzymes in the alveolar cell membranes of the mammary gland. This mechanism is probably under hormonal control and the unexpected advent of preterm delivery would not allow hormonal conditions typical of lactation to occur immediately, causing a delay in enzymatic inhibition. This hypothesis is supported by some of our results, picturing a peculiar transient phenomenon of adaptation of the mammary-gland-membrane proteins after preterm delivery. Further studies will be required to verify whether the presence of protein fragments exerts a specific biological and immuno-defensive role in preterm infants, thus adding evidence to the outstanding biological role and benefits of mother's own milk in feeding preterm infants.
American Academy of Pediatrics, Work Group on Breastfeeding: Breastfeeding and the use of human milk. Pediatrics2005; 115:496–506.
2.
HamoshM. Bioactive factors in human milk. Pediatr Clin North Am2001; 48:69–86.
3.
RigoJ. Protein, amino acids and other nitrogen compounds. In: Nutrition of the preterm infant. TsangRCUauyRKoletzkoBZlotkinSH, editors. Cincinnati, Ohio: Digital Educational Publishing, 2005; pp. 45–80.
4.
AtkinsonSA. Effects of gestational stage at delivery on human milk components. In: Handbook of milk composition. JensenRG, editor. San Diego, California: Academy Press, 1995; pp 222–36.
5.
BallabioCBertinoECosciaA. Immunoglobulin-A profile in breast milk from mothers delivering full-term and preterm infants. Int J Immunopathol Pharmacol2007; 20:119–128.
6.
VelonàTAbbiatiLBerettaBGaiaschiAFlaùtoUTagliabuePGalliCLRestaniP. Protein profiles in breast milk from mothers delivering term and preterm babies. Pediatr Res1999; 45:658–63.
7.
HamoshMPetersonJAHendersonTRScallanCDKiwanRCerianiRLArmandMMehtaNRHamoshP. Protective function of human milk: The milk fat globule. Semin Perinatol1999; 23:242–49.
8.
CavalettoMGiuffridaMGContiA. The proteomic approach to analysis of human milk fat globule membrane. Clin Chim Acta2004; 347:41–8.
9.
FortunatoDGiuffridaMGCavalettoM. Structural proteome of human colostral fat globules membrane proteins. Proteomics2003; 3:897–905.
10.
PetersonJAHamoshMScallanCDCerianiRLHendersonTRMehtaNRArmandMHamoshPM. Milk fat globule glycoproteins in human milk and in gastric aspirates of mother's milk-fed preterm infants. Pediatr Res1998; 44:499–506.
11.
PalmerCANevilleMCAndersonSMMcManamanJL. Analysis of lactation defects in transgenic mice. J Mammary Gland Biol Neoplasia2006; 11:269–282.
12.
BuhimschiCS. Endocrinology of lactation. Obstet Gynecol Clin North Am2004; 31:963–79.
13.
MercerBMMacphersonCAGoldenbergR. Are women with recurrent spontaneous preterm births different from those without such history?Am J Obstet Gynecol2006; 194:1176–85.
14.
FlorioPZatelliMCReisFMUbertiEC DegliPetragliaF. Corticotropin releasing hormone: A diagnostic marker for behavioral and reproductive disorders?Front Biosci2007; 12:551–60.
15.
QuarantaSGiuffridaMGCavalettoM. Human proteome enhancement: High-recovery method and improved two-dimensional map of colostral fat globule membrane proteins. Electrophoresis2001; 22:1810–18.
16.
LönnerdalBWoodhouseLRGlazierC. Compartmentalization and quantitation of protein in human milk. J Nutr1987; 11:1385–95.
17.
LaemmliUK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature1970; 227:680–85.
18.
WesselDFluggeUI. A method for the quantitative recovery of protein in dilute solution in the presence of detergents and lipids. Anal Biochem1984; 138:141–43.
19.
NeuhoffVAroldNTaubeDEhrhardtW. Improved staining of proteins in polyacrylamide gels including isoelectric focusing gels with clear background at nanogram sensitivity using Coomassie Brilliant Blue G-250 and R-250. Electrophoresis1988; 9:255–262.
20.
PappinDJHojrupPBleasbyAJ. Rapid identification of proteins by peptide-mass fingerprinting. Curr Biol1993; 3:327–32.
21.
HellmannUWernstedtCGonezJHeldinCH. Improvement of an in-gel digestion procedure for the micropreparation of internal protein-fragments for amino acid sequencing. Anal Biochem1995; 224:451–55.
22.
SzabovaLYamadaSSBirkedal-HansenHHolmbeckK. Expression pattern of four membrane-type matrix metalloproteinases in the normal and diseased mouse mammary gland. J Cell Physiol2005; 205:123–32.
23.
CauveBvan den SteenPEOpdenakkerG. The biochemical, biological, and pathological kaleidoscope of cell surface substrates processed by matrix metalloproteinases. Crit Rev Biochem Mol Biol2007; 42:113–85.
24.
BaldiAPolitiIPecoriniCFusiEChronopoulouRDell'OrtoV. Biological effects of milk proteins and their peptides with emphasis on those related to the gastrointestinal ecosystem. J Dairy Res2005; 72:66–72.
25.
GiuffridaMGCavalettoMGiuntaCContiAGodovac-ZimmermannJ. Isolation and characterization of full and truncated forms of human breast carcinoma protein BA46 from human milk fat globule membranes. J Prot Chem1998; 17:143–48.
26.
CavalettoMGiuffridaMGGiuntaCVellanoCFabrisCBertinoEGodovac-ZimmermannJContiAJ. Multiple forms of lactadherin (breast antigen BA46) and butyrophilin are secreted into human milk as major components of milk fat globule membrane. J Dairy Res1999; 66:295–301.
27.
CavalettoMGiuffridaMGFortunatoD. A proteomic approach to evaluate the butyrophilin gene family expression in human milk fat globule membrane. Proteomics2002; 2:850–56.
28.
TaylorMRCoutoJRScallanCDCerianiRLPetersonJA. Lactadherin (formerly BA46), a membrane-associated glycoprotein expressed in human milk and breast carcinomas, promotes ArgGlyAsp (RGD)-dependent cell adhesion. DNA Cell Biol1997; 16:861–69.
29.
HäggqvistBNäslundJSlettenK. Medin: An integral fragment of aortic smooth muscle cell-produced lactadherin forms the most common human amyloid. Proc Natl Acad Sci USA1999; 96:8669–74.
30.
PengSWestermarkGTNäslundJHäggqvistBGlennertJWestermarkP. Medin and medin-amyloid in ageing inflamed and non-inflamed temporal arteries. J Pathol2002; 196:91–6.
31.
NilssonMRDobsonCM. In vitro characterization of lactoferrin aggregation and amyloid formation. Biochemistry2003; 42:375–82.
32.
OhashiAMurataEYamamotoKMajimaESanoELeQTKatunumaN. New functions of lactoferrin and beta-casein in mammalian milk as cysteine protease inhibitors. Biochem Biophys Res Comm2003; 306:98–103.
33.
YamauchiKTomitaMGiehlTJEllisonRT3rd. Antibacterial activity of lactoferrin and a pepsin-derived lactoferrin peptide fragment. Infect Immun1993; 6:719–28.
34.
GuggenmosJSchubartASOggSAnderssonMOlssonTMatherIHLiningtonC. Antibody cross-reactivity between myelin oligodendrocyte glycoprotein and the milk protein butyrophilin in multiple sclerosis. J Immunol2004; 172:661–68.
