Milk Oligosaccharides - Advanced Dairy Chemistry - page 327

oligosaccharides was demonstrated. The binding of Neisseria pili to bovine
thyroglobulin was most effective and was clearly inhibited by neutral human
or acidic bovine milk oligosaccharides at concentrations of 1-2 g/L, suggest-
ing that these fractions had the potential ability to inhibit the attachment of
this bacterium to the colonic mucosa (Hakkarainen et al., 2005).
There is evidence that oligosaccharides from milks other than human can
act as receptor analogues, inhibiting the adhesion of pathogenic microorgan-
isms. Fractions containing milk oligosaccharides, in the form of supernatants
that had been separated from colostrum and from transitional, mature and late
lactation milk of Spanish brown cows by ethanol precipitation and subsequent
centrifugation, were used to investigate the inhibition of hemagglutination by
seven enterotoxigenic E. coli strains (K99, FK, F41, F17, B16, B23 and B64).
These strains had been isolated from diarrheal calves. The fractions from the
transitional and late lactation milk inhibited hemagglutination by all of these
strains, whereas those from colostrum and late lactation milk produced
weaker inhibition (Martin et al., 2002). It was assumed that this inhibition
was due to 3 0 -SL, 6 0 -SL, 6 0 -N-acetylneuraminyl-N-acetyllactosamine (6 0 -
SLN: Neu5Ac( 2-6)Gal( 1-4)GlcNAc) and disialyl lactose (DSL: Neu5Ac
( 2-8)Neu5Ac( 2-3)Gal( 1-4)Glc). The fractions from transitional and mature
milk, in which the ratio of 6 0 -SL to 3 0 -SL was higher than in the fractions from
colostrum and late lactation milk, had a stronger effect than the others.
It has been suggested that Neu5Gc( 2-3)Gal( 1-4)Glc, which is found
in ovine (Nakamura et al., 1998) and caprine (Urashima et al., 1997) colos-
trum, inhibits the attachment of enterotoxigenic E. coli K99 to the infant's
colon, Neu5Gc( 2-3)Gal being the receptor recognized by E. coli K99 adhe-
sins (Kyogashima et al., 1989). Globotriose (Gal( 1-4)Gal( 1-4)Glc), which
is present in bottle-nosed dolphin colostrum (Uemura et al., 2005), is sug-
gested as a possible inhibitor of the binding of Shigella toxin and Shiga-like
toxin produced by pathogenic E. coli (Lindberg et al., 1987; Samael et al.,
1990). Gal( 1-3)Gal( 1-4)GlcNAc( 1-3)Gal( 1-4)Glc, which has been
found in the milk of the white-nosed coati (Urashima et al., 1999) and mink
(Urashima et al., 2005), has been suggested to be a possible inhibitor of the
binding of toxin A produced by Clostridium difficile (Clark et al., 1987).

8.8. Immuno-Modulating Effect of Milk Oligosaccharides

Although direct detection of human milk oligosaccharides in the blood of
infants has not yet been reported (Bode, 2006), it nevertheless seems very
likely that small amounts of intact human milk oligosaccharides are normally
absorbed from the gastrointestinal tract, and that they are transported into
the blood, on the basis of their observed urinary excretion (Rudloff et al.,