Short-chain fatty acids produced by synbiotic mixtures in skim milk differentially regulate proliferation and cytokine production in peripheral blood mononuclear cells

Short chain fatty acids (SCFAs) are major products of prebiotic fermentation and confer human health benefits such as immune-regulation. In this study, reconstituted skim milk supplemented with prebiotics (RSMP) including inulin, hi-maize or beta-glucan was fermented by probiotic strains of Lactobacillus spp. and Bifidobacteria spp. After 24 h of fermentation, probiotics growth and SCFAs production were investigated and the produced SCFAs were extracted. Inulin and Lactobacillus rhamnosus GG ATCC 53013 (LGG) combination released highest concentrations of SCFAs compared to LGG and hi-maize or beta-glucan. Extracted SCFAs were then used for in vitro immune modulation study in human peripheral blood mononuclear cells (PBMCs). In lipopolysaccharide (LPS)-stimulated PBMCs, SCFAs particularly butyrate down-regulated tumor necrosis factor alpha, interleukin (IL)-12, interferon gamma (IFN-gamma) and transforming growth factor beta-1 (TGF-beta 1), and up-regulated IL-4, IL-10, while no significant effect was noted in non-LPS-stimulated PBMCs. The results indicate that SCFAs regulated cytokine milieu in LPS-stimulated PBMCs to anti-inflammatory cytokines.