Dietary non-digestible oligosaccharide-induced epithelial
galectin-9 secretion correlates with protection against allergic
symptoms.
S. de Kivit1, E. Saeland2, A.D. Kraneveld1, H.J.G. van de Kant1, B.
Schouten1,3, B.C.A.M. van Esch1,3, J. Knol3, A.B. Sprikkelman4, L.B. van der
Aa4, L.M.J. Knippels1,3, Y. van Kooyk 2, J. Garssen1,3, L.E.M. Willemsen1
1
Pharmacology, Utrecht Institute Pharmaceutical Sciences, Utrecht University,
Utrecht, 2Molecular Cell Biology and Immunology, VU University Medical Center,
Amsterdam, 3Danone Research, Wageningen, 4Pediatric Respiratory Medicine
and Allergy, Emma Children’s Hospital, Amsterdam
Background: Intestinal epithelial cells (IEC) abundantly express galectins, which
are known to modulate T cell responses. In this study, immune modulation and
epithelial
expression
of
galectin-9
(Gal-9),
induced
by
a
galacto/fructooligosaccharide mixture (scGOS/lcFOS) and TLR9 ligand, and its
relevance for the suppression of allergic disease were determined both in vitro
and in vivo. Methods: Human IEC were grown on transwell inserts and apically
exposed to 0.5% scGOS/lcFOS together with Toll-like receptor ligands and cocultured with activated healthy donor PBMC in the basolateral compartment.
After 24h, cytokines and immune cell phenotype were measured. In vivo, mice
were sensitized orally to whey, while being fed a diet containing Bifidobacterium
breve M-16V and scGOS/lcFOS (GF/Bb). Gal-9 expression was determined by
immunohistochemistry in the intestine and measured in the serum by ELISA. In
addition, in a double-blind, placebo-controlled multicentre trial, Gal-9 levels were
measured in sera of 90 infants with atopic dermatitis that received hydrolyzed
formulae with or without GF/Bb for 12 weeks. Results: IEC-derived Gal-9 mRNA,
protein expression, and basolateral secretion increased after combined addition
of scGOS/lcFOS and TLR9 ligand in the co-culture model. This coincided with
enhanced IL-10 and IFN- secretion by PBMC and increased percentages of T h1
and Treg cells. Basolateral neutralization of galectins suppressed IL-10 and IFN-,
but enhanced IL-6, IL-17 and TNF- secretion. Furthermore, development of Th1
and Treg cells was enhanced in Gal-9 treated PBMC, resulting in increased IL-10
and IFN-, but suppressed IL-17 secretion in a dose dependant manner.
Immunohistochemistry in mouse intestine revealed expression of Gal-9 in
epithelial cells in the small intestine. Interestingly, the GF/Bb diet enhanced
serum Gal-9 levels, which correlated with decreased allergic symptoms. In
addition, infants suffering from atopic dermatitis receiving the GF/Bb diet also
showed enhanced Gal-9 levels in serum, which coincided with less severe
allergic symptoms. Conclusion: GF/Bb-induced Gal-9 expression by IEC may
protect against the development of allergic disease by modulating the effector T
cell response.
This study/work was performed within the framework of the Dutch Top Institute
Pharma, project T1-214.