Specific Human Milk Oligosaccharides Differentially Promote Th1 and Regulatory Responses in a CpG-Activated Epithelial/Immune Cell Coculture

Abstract

Proper early life immune development creates a basis for a healthy and resilient immune system, which balances immune tolerance and activation. Deviations in neonatal immune maturation can have life-long effects, such as development of allergic diseases. Evidence suggests that human milk oligosaccharides (HMOS) possess immunomodulatory properties essential for neonatal immune maturation. To understand the immunomodulatory properties of enzymatic or bacterial produced HMOS, the effects of five HMOS (2′FL, 3FL, 3′SL, 6′SL and LNnT), present in human milk have been studied. A PBMC immune model, the IEC barrier model and IEC/PBMC transwell coculture models were used, representing critical steps in mucosal immune development. HMOS were applied to IEC cocultured with activated PBMC. In the presence of CpG, 2′FL and 3FL enhanced IFNγ (p < 0.01), IL10 (p < 0.0001) and galectin-9 (p < 0.001) secretion when added to IEC; 2′FL and 3FL decreased Th2 cell development while 3FL enhanced Treg polarization (p < 0.05). IEC were required for this 3FL mediated Treg polarization, which was not explained by epithelial-derived galectin-9, TGFβ nor retinoic acid secretion. The most pronounced immunomodulatory effects, linking to enhanced type 1 and regulatory mediator secretion, were observed for 2′FL and 3FL. Future studies are needed to further understand the complex interplay between HMO and early life mucosal immune development.

Human milk oligosaccharides differentially support gut barrier integrity and enhance Th1 and Th17 cell effector responses in vitro

“…In one study the apparent TLR-4 mediated immunomodulatory effects of 3’SL on human monocyte-derived DCs were attributed to LPS contamination (10 EU/mg), thus warranting caution and a need for assessing LPS contamination levels when studying e.g., TLR-mediated effects of HMOs ( 55 ). The HMOs studied in the present study had a very low endotoxin level (<0.009 EU/mg, Table 1 ), which is not in the range expected to significantly confound immunological responses, as shown previously ( 35 , 55 ). Importantly, HMO supplementation to non-activated DCs stimulated minimal cytokine secretion compared to LPS-activated DCs ( Supplementary Figure 3 ).…”

“…Such models more closely mimic mucosal immune responses, whereas here we have focused on systemic immunomodulatory effects. In a recent study using co-cultures of HT29 human colon epithelial cells conditioned with CpG (a synthetic TLR9 ligand) and PBMCs activated with anti-CD3/CD28 antibodies, 2′FL and 3FL were shown to promote stronger immunomodulatory effects linked to Th1 and regulatory T (T reg ) cell responses than 3′SL and 6′SL ( 35 ). Similarly, DCs exposed to 2′FL and CpG-conditioned HT29 cells gained an enhanced ability to promote the secretion of IFN-γ and IL-10 by CD4 + T cells ( 60 ).…”

“…In another study, the acidic fraction of pooled breastmilk-derived HMOs increased IFN-γ production from cord blood-derived mononuclear cells ( 34 ). Using a co-culture model of intestinal epithelial cells and peripheral blood-derived mononuclear cells (PBMCs), 2′-fucosyllactose (2′FL) and 3-fucosyllactose (3FL) were found to inhibit Th2 differentiation ( 35 ). Furthermore, the acidic HMO 3′-sialyllactose (3′SL), but not the structurally similar 6′-sialyllactose (6′SL), increased the intestinal expression of IL-17A mRNA in a mouse model of colitis ( 36 ).…”

Clinical Studies on the Supplementation of Manufactured Human Milk Oligosaccharides: A Systematic Review

“…In a Bifidobacterium -dominated gut environment, the growth of pathogenic bacteria is strongly discouraged. The microbiome may also support the immune system, either by direct interaction with immune cells [ 78 ] or by producing immunomodulatory metabolites [ 15 ]. In one clinical study, higher levels of sIgA, α-1-antitrypsin, and calprotectin were detected, along with an increase in the abundance of B. infantis [ 51 ].…”

Anti-Inflammatory and Anti-Allergic Properties of Colostrum from Mothers of Full-Term and Preterm Babies: The Importance of Maternal Lactation in the First Days

“…These soluble complexes are non-digestible sugars with various monosaccharides and chemical structures with similar characteristics and functions. They are determined by the α-1-2-fucosyltransferase (FUT-2) and d α-1-3-4-fucosyltransferase (FUT-3) genes, but other factors influence HMOs differences, such as maternal genetic, health, diet, preterm/full-term delivery, lactation period, geographical area, pollution, and other factors [8][9][10][11]. HMOs are prebiotics, which is to say a selectively fermented ingredient that results in specific changes in the composition, diversity, and/or activity of the gastrointestinal microbiota, thus conferring benefits upon host health [12].…”