PURPOSE OF THE STUDY.
To investigate whether galectin-9 has a role in the mechanism of suppression of allergic skin reactions and mast cell degranulation induced by dietary synbiotics.
Three-week-old specific pathogen-free C3H/HeOuJ mice were studied in a cow’s milk allergy model with or without a probiotic or prebiotic. Ninety human infants with atopic dermatitis were studied in a double-blind, placebo-controlled multicenter trial in which they received a hydrolyzed formula with or without synbiotics.
Mice were sensitized orally to whey while being fed a diet containing a specific prebiotic (9:1 mixture of short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides), a specific probiotic (Bifidobacterium breve M-16V), a combination of both, or a control diet (4 groups). Galectin-9 expression was determined by immunohistochemistry in the intestine and measured in the serum by enzyme-linked immunosorbent assay. T-cell differentiation was determined in the mesenteric lymph nodes as well as in galectin-9–exposed peripheral blood mononuclear cell cultures via expression of transcription factors T-bet, GATA-3, RORγT, and Foxp3 along with cytokine production assays. Sera from mice were studied for the capacity to suppress mast cell degranulation. Sera from the 90 human infants were evaluated for galectin-9 levels.
Galectin-9 expression by intestinal epithelial cells as well as serum galectin-9 levels were increased in mice and humans after dietary intervention with the symbiotic combination (pre- and probiotic together). In mice, the levels correlated with reduced acute allergic skin reaction and reduced mast cell degranulation. In addition, the dietary synbiotics resulted in enhanced Th1- and Treg-cell differentiation in lymph nodes and in peripheral blood mononuclear cell cultures exposed to galectin-9.
Dietary supplementation with a synbiotic (prebiotic short-chain galacto-oligosaccharides/long-chain fructo-oligosaccharides + probiotic Bifidobacterium breve M-16V) enhances serum galectin-9 levels which is associated with the prevention of expression of components of allergic responses.
The results of this study show galectin-9, an epithelial product expressed in mucosal surfaces during inflammatory responses, is a significant component of the protective antiallergy effect of synbiotic treatment. This effect is supported by data showing modulation of Th1- and Treg-cell polarization as well as immunoglobulin E sequestration (another study has shown strong binding of galectin-9 to immunoglobulin E) resulting in the reduced mast cell degranulation observed. Galectin-9 may be an important marker for the suppression of food allergy and further studies are warranted.
- Copyright © 2012 by the American Academy of Pediatrics