Guar gum fiber increases suppressor of cytokine signaling-1 expression via toll-like receptor 2 and dectin-1 pathways, regulating inflammatory response in small intestinal epithelial cells
Direct regulation of intestinal inflammation by intact dietary fibers is still unclear. Here, the anti-inflammatory regulation by intact guar gum (GG) was investigated using mice and human intestinal Caco-2 cells.Methods and results:
Administration of dextran sodium sulfate (DSS) increased myeloperoxidase activity and CXC motif chemokine ligand2 (an IL-8 homolog) expression in the small intestines of mice, while supplemental GG reduced these increases. Stimulation of Caco-2 cells with tumor necrosis factor (TNF)-α induced IL-8 expression through nuclear factor kappa B p65, spleen tyrosine kinase, and mitogen-activated protein kinases pathways. Pre-treatment of cells with GG reduced the TNF-α-induced IL-8 expression and cellular signaling. GG increased the suppressor of cytokine signaling (SOCS)-1 expression in Caco-2 cells, suggesting that this is one of the probable mechanisms involved in GG-mediated anti-inflammatory regulation. The anti-inflammatory regulation and SOCS-1 expression induced by GG were sensitive to neutralization of toll-like receptor (TLR)2 and dectin-1, and to inhibition of Janus kinase (JAK) and tyrosine kinase cSrc pathways. Finally, supplemental GG increased SOCS-1 expression in the small intestines of both DSS-administered and normal mice.Conclusion:
Intact GG activates TLR2 and dectin-1, and increases SOCS-1 expression via JAK and cSrc pathways, resulting in anti-inflammatory regulation in intestinal epithelium.