Konjac glucomannan polysaccharide and inulin oligosaccharide enhance the colonic mucosal barrier function and modulate gut-associated lymphoid tissue immunity in C57BL/6J mice.

Both konjac glucomannan (KGM) and inulin oligosaccharide have been shown to improve bowel function, but their effects on the mucosal barrier function and immunity are not fully understood. The aim of this study was to determine effects of a low-level supplementation of dietary fibres on the colonic mucosal barrier function, antioxidant enzyme defense and immunity. C57BL/6J mice (six weeks of age, 8 per group) were randomly assigned to consume one of the following diets: control, or control diet supplemented with 2% (w/w) of KGM, inulin oligosaccharide (degree polymerization=8) or KGM+Inulin (1% w/w each). Fresh feces were collected on d 19-21 for analyses of short-chain fatty acid and microflora. Mice were sacrificed on d 22 after fasting. Segments of colon tissues were processed for histological procedure and stained for acidic mucins and tight junction protein marker ZO-1. The remaining tissues were processed to determine gene expressions of mucin 2, tight junction proteins, antioxidant enzymes and cytokines. The plasma TNF-α and IL-10 level were also measured to investigate the systemic effects of dietary fibres. Results indicated that KGM, inulin and K+I significantly increased the mucosal layer thickness, mucin density (granule number/crypt) and gene expression of Muc2 as compared with the control. All fibre treatments increased the gene expressions of ZO-1, occludin, GPX, GST, catalase, and IL-10. In addition, all fibre treatments increased fecal butyrate and probiotics, and plasma IL-10 concentrations. In conclusion, supplementation of low-level, 2% (w/w), of KGM and inulin was sufficient to enhance the mucosal barrier function and anti-inflammatory status.