Tracking intestinal translocation and tissue deposition of orally ingested polymeric compounds 4809

Description The gut epithelial barrier is exposed to a diverse collection of macromolecular structures derived from commensal gut bacteria and dietary inputs. Movement of material from the gut lumen into the tissues can occur via M-cell mediated transcytosis and dendritic cell uptake, but whether these pathways contribute to translocation of dietary glycan substrates remains unclear. We sought to test whether dietary plant polysaccharides can cross the epithelium under homeostatic conditions, and determine the immunological consequences of their accumulation in the lamina propria. We began by generating 40 distinct dietary polysaccharide-biotin conjugates which we orally administered to mice to assess translocation and tissue deposition. Surprisingly, we found that control preparations consisting entirely of polymeric biotin were detected in liver lysates 17 hours after gavage. Liver tissue sections revealed that polymeric biotin was not localized within Kupffer cells, and instead appeared in discrete collections of hepatocytes surrounding endothelial cells. Polymeric biotin did not induce IL1b or IL10 production in macrophages in vitro, and thus may be a viable vehicle for shuttling orally ingested polysaccharide substrates across the gut epithelium to study their immunostimulatory properties.