Galactooligosacharides reduces colitis by modulating the function and trafficking of NK cells

The use of prebiotics could represent a novel therapeutic strategy for individuals with inflammatory bowel disease.
The gut microbiota plays an essential role in intestinal immunity. Prebiotics, including galacto-oligosaccharides (GOS), are fermentable fibers that beneficially affect the host by stimulating the growth of specific microbial populations.
The effect of GOS on colitis development and on immune variables in Smad3-deficient mice treated with the pathogen Helicobacter hepaticus. Mice were supplemented daily with 5000 mg GOS/kg body weight 2 wk prior to infection and 4 wk post-infection, a time period at which colitis severity peaks in this model. Mice (n = 4–8/treatments at each time) were killed pre-infection (0 d) and at 3, 7, and 28 d post-infection to evaluate immune variables in the spleen and in mesenteric lymph nodes (MsLN) by flow cytometry.
Colon and cecum samples were collected for histopathologic analysis. Fecal pellets (n = 8–9/treatments) were collected prior to infection to measure relative changes in Bifidobacterium ssp. and Lactobacillus ssp. by real-time PCR. GOS significantly reduced colitis severity in response to H. hepaticus (P, 0.0001). This was associated with a significant increase in the percentage of NK cells in the spleen (P , 0.001) and in MsLN (P , 0.001) at 3 d post-infection and a 1.5-fold increase in fecal Bifidobacterium ssp. (P = 0.003).
GOS stimulated NK expression of CCR9, a chemokine receptor involved in lymphocyte trafficking to the gut pre-infection (0 d) in the blood (P = 0.02), spleen (P = 0.033), and MsLN (P = 0.017). In addition, GOS stimulated colonic IL-15 production 3 d post-infection (P, 0.001).
These data suggest that GOS reduces colitis by modulating the function and trafficking of NK cells and may provide a novel therapeutic strategy for individuals with inflammatory bowel disease.
Source: J. Nutr. doi: 10.3945/jn.111.154732.