Exposure of intestinal epithelial cells to 2′-fucosyllactose and cpg enhances galectin release and instructs dendritic cells to drive th1 and regulatory-type immune development

Intestinal epithelial cells (IEC) release immunomodulatory galectins upon exposure to CpG DNA (mimicking bacterial triggers) and short-chain galacto- and long-chain fructo-oligosaccharides (GF). This study aims to investigate the immunomodulatory properties of 20-fucosyllactose (20-FL), a non-digestible oligosaccharide (NDO) abundantly present in human milk, using a co-culture model developed to study the crosstalk between IEC and innate and adaptive immune cells. IECs, co-cultured with αCD3/CD28-activated peripheral blood mononuclear cells (PBMC), were apically exposed to NDOs and CpG, washed and co-cultured with immature monocyte-derived dendritic cells (moDC). Subsequently, moDC were co-cultured with naïve CD4+ T-cells. In the presence of CpG, both 20-FL or GF-exposed IEC enhanced Th1-type IFN and regulatory IL-10 secretion of PBMCs, compared to CpG alone, while Th2-type IL-13 was reduced. Both NDOs increased IEC-derived galectin-3, -4, -9 and TGF-β1 of CpG-exposed IEC. Only galectin-9 correlated with all modified immune parameters and TGF-β1 secretion. MoDCs exposed to 20-FL and CpG-conditioned IEC instructed IFN and IL-10 secretion by CD4+ T-cells, suggesting the development of a regulatory Th1 response. These results reveal that 20-FL and GF could contribute to the mucosal immune development by supporting the e_ect of microbial CpG DNA associated with the modulation of epithelial galectin and TGF-β1 secretion.