Interaction of Mannan oligosaccharide with Immune System “Transport of MOS in to the Lamina Propria”

Abstract

Summary Mannan oligosaccharide (MOS) is a complex that is derived from the cell wall of the yeast Saccharomyces cerevisiae. This complex carbohydrate product has been utilized around the world to improve the productivity and wellbeing of poultry, fish and livestock. Questions related to the specific interaction between MOS and the immune cells still remain unclear. The objectives of this study are to investigate if MOS passes through the intestinal epithelium and if it is translocated to the lamina propria of the small intestine. In order to understand the fate of MOS in the gastrointestinal tract and its interaction with the immune related cells, this study compares the translocation of Albumin, the negative control which is known not to be quickly digested and not translocated; that of Dextran, the positive control which is known to be phagocytosed by dendritic cells and that MOS, the experimental group. Pure mannan was obtained from a mannan rich fraction by reacting with 7-methoxycoumarin-3-isocyanate in dimethylsulphoxide. The labeled product was isolated by ethanol precipitation. The MOS was labeled with a flourescent tag. In this study sixteen one-day old broiler chicks (Cobb x Cobb) were used. They were kept in brooder batteries with four chicks per pen. Each group (n=4) was assigned to a different fluorescent-labeled diet. The control group got the basal diet without fluorescent-tagged molecules in order to determine background levels of fluorescence. The ratio of fluorescent labeled MOS, albumin and dextran to the basic diet was 20 mg/kg. The experiment lasted three weeks. At the end of the study chickens were terminated with carbon dioxide. The removed intestinal segments were preserved in 10% formalin and fixed on the slides using the paraffin method. From each segment, 72 glass slides were prepared. Images captured by fluorescent microscopy were used to determine the extent of translocation of MOS into the lamina propria. The data was analyzed by ANOVA. P value <0.05 was considered to be significant. Foci of fluorescence from albumin were not detectable. The albumin was degraded prior to entrance into the lamina propria as expected in the negative control group. Thus it was not included in the statistical analysis. Comparatively, dextran, the positive control group was transported into the lamina propria, most significantly in the ileum. MOS, the experimental group was transported into the lamina propria. In the duodenum and jejunum, our results indicated that larger amounts of MOS were as transported into lamina propria as compared to dextran. In conclusion MOS does not interact specifically with the epithelial cells but it makes its way to the gut associated lymphoid tissue (GALT) of the lamina propria via an independent method, which appears to be mediated by dendritic cells as an immune surveillance mechanism that is vital in the mucosal immunity. MOS has likely a general adjuvant effect on immune system without causing “danger signals” that are inherent in pathogen. Further studies are needed to identify the mechanism of this interaction especially with M-Cells, which are specialized epithelial cells and play a key role in stimulating the immune system.