In Vitro Evidence for Immune-Modulatory Properties of Non-Digestible Oligosaccharides: Direct Effect on Human Monocyte Derived Dendritic Cells

Abstract

Infant formulas containing non-digestible oligosaccharides (NDO) similar to the composition in breast milk or a combination of lactic acid bacteria (LAB) and NDO have been shown to harbor preventive effects towards immune-regulatory disorders. The aim of this study was to investigate the immune-modulatory potential of non-digestible short chain galacto- and long chain fructo-oligosaccharides (scGOS/lcFOS) mimicking the natural distribution of oligosaccharides in human breast milk in presence or absence of certain LAB strains in human monocyte derived dendritic cells (MoDC). Immature human MoDC prepared from peripheral blood of healthy non-atopic volunteers were screened in vitro after stimulation with specific scGOS/lcFOS in presence or absence of LAB. IL-10 and IL-12p70 release was analyzed after 24 hours in cell-free supernatants by enzyme-linked immunosorbent assay (ELISA). A luminex-based assay was conducted to assess further cytokine and chemokine release by MoDC. To investigate the resulting T cell response, stimulated MoDC were co-incubated with naïve T cells in allogeneic stimulation assays and intracellular Foxp3 expression, as well as immune-suppressive capacity was determined. Oligosaccharides did not induce relevant amounts of IL-12p70 production, but did promote IL-10 release by MoDC. Furthermore, scGOS/lcFOS mixtures exerted a significant enhancing effect on LAB induced IL-10 secretion by MoDC while no increase in IL-12p70 production was observed. Blocking toll like receptor (TLR)4 abrogated the increase in IL-10 in both the direct stimulation and the LAB stimulation of MoDC, suggesting that scGOS/lcFOS act via TLR4. Finally, scGOS/lcFOS-treated MoDC were shown to upregulate the number of functional suppressive Foxp3 positive T cells following allogeneic stimulation. Our results indicate anti-inflammatory and direct, microbiota independent, immune-modulatory properties of scGOS/lcFOS mixtures on human MoDC suggesting a possible induction of regulatory T cells (Tregs). The tested combinations of LAB and scGOS/lcFOS might represent a useful dietary ingredient for the maintenance of intestinal homeostasis via the induction of Tregs.

Protein kinase C δ signaling is required for dietary prebiotic-induced strengthening of intestinal epithelial barrier function

“…Taken together, these results support a view that prebiotics may be directly activating TLR signaling to alter cytokine/chemokine expressions and the integrity of the epithelial barrier. This is also in line with multiple reports showing that prebiotics induce cytokine and chemokine production in monocytes and intestinal epithelial cells in a TLR2- or TLR4-dependent fashion121928293031. However, whether PKCδ is the only PKC isoform or the only signal transduction pathway affected is still unclear.…”

Human milk oligosaccharides promote immune tolerance via direct interactions with human dendritic cells

“…Both IL‐10 and IL‐27 released by moDC, are linked to the induction of CD4 + T‐cell with regulatory function . Conversely, IL‐12p70 has been shown to reduce the frequency of regulatory T‐cell and Foxp3 expression and enhance the activation and proliferation of conventional T‐cell .…”

“…In human monocytes‐derived DCs (moDCs), a mixture of short‐chain galacto‐oligosaccharides (scGOS) and long‐chain fructo‐oligosaccharides (lcFOS) at a ratio of 9:1, directly modulated DCs phenotype. Both cytokine and chemokine production and T‐cell priming were modulated in a TLR4‐mediated manner in vitro . In a murine colitis model pro‐inflammatory stimulation was induced by 3’SL, possibly through direct recognition by intestinal DCs in a TLR4‐dependent manner, whereas 6’SL was not able alter the DCs .…”

Microbiota‐dependent and ‐independent effects of dietary fibre on human health

“…Interestingly, pectin inhibited TLR2-TLR1 activation (Sahasrabudhe et al, 2018). Lehmann et al, 2015). Different HMOs controlled immune responses via TLR3 and TLR4 signalling as reviewed by .…”