Effect of Human Milk Oligosaccharides on Messenger Ribonucleic Acid Expression of Toll-like Receptor 2 and 4, and of MD2 in the Intestinal Cell Line HT-29

Abstract

It is believed that human milk oligosaccharides (HMO) act as receptor analogues that inhibit the attachment of pathogenic microorganisms to the infant colon, but the direct involvement of HMO in anti infection has not as yet been demonstrated. The present study was conducted to clarify whether HMOs as well as commercially available galacto oligosaccharides (GO), from which lactose has been removed, affect the expression of toll-like receptor (TLR) 2 and 4, and of MD2 mRNA in the HT-29, human colonic cell line. HT-29 cells were treated with neutral human milk oligosaccharides (nHMOs), which had been separated from the acidic oligosaccharide fraction and also from lactose, as well as with GOs. HT-29 cells were treated with specific oligosaccharides of major components of nHMO or GO. The mRNA expression of TLR2, 4 and MD2 were measured using Real-time RT-PCR normalized to glyceraldehydes 3-phosphate dehydrogenase (GAPDH) mRNA expression. The addition of nHMO affected the expression of TLR2. Treatment with 1.0 mg/mL of nHMO as well as with 0.5 mg and 1.0 mg/mL GO enhanced the mRNA expression of TLR4. In experiments with specific oligosaccharides, treatments with 3'-sialyllactose (3'-SL), 6'-sialyllactose (6'-SL) or 6'-galactosyllactose (6'-GL) increased the expression of TLR-2, while the administration of lacto-N-fucopentaose I (LNFP I), 3'-, 6'-SL or 6'-GL enhanced that of TLR4. These results suggest that HMOs as well as GOs had a direct effect on colonic epithelial cells, with induction of the mRNA expression of TLR.