Comparison of the Effects of 3 Forms of Soluble Dietary Fiber on the Production of IgA in BALB/cAJcl and BALB/cAJcl-nu/nu Mice

Abstract

BackgroundThe ability of soluble dietary fibers (SDFs) to induce the production of IgA, especially in the intestine, is one of the health benefits of SDFs, but the mechanism involved is unclear. ObjectiveThis study was designed to identify the relationship between the induction of IgA by SDFs and the cecal short-chain fatty acid (SCFA) content, and to evaluate the importance of T cell-independent IgA production for SDF-induced IgA production. MethodsWe compared 3 SDFs—fructooligosaccharides (FO), indigestible glucan (IG), and polydextrose (PD). Male BALB/cAJcl mice or T cell-deficient BALB/cAJcl-nu/nu (nude) mice were fed diets supplemented with 1 SDF (3% w/w) for 10 wk, and IgA content in their feces, plasma, lung, and submandibular gland was measured. ResultsIn BALB/cAJcl mice, the consumption of all 3 SDF diets induced fecal IgA production, but the response was stronger in the IG and PD groups than in the FO group. The IgA concentrations of the plasma and lung were also higher in the FO and PD groups, and these groups showed significantly higher cecal acetic and n-butyric acid content. In contrast, in nude mice, the induction of IgA production was identified only in fecal samples of mice fed the 3 SDF diets, although there were significant increases in cecal SCFA content. ConclusionsThe induction of IgA production by SDFs occurred independent of T cells in the intestine, but in the plasma, lung, and submandibular gland it was T-cell dependent. SCFAs generated in the large intestine may influence the systemic immune system, but there is no clear relationship between the generation of SCFAs and intestinal IgA production in response to SDF consumption.