Effect of nonpathogenic Escherichia coli monoassociation on small intestinal brush-border glycoconjugate moieties and cytokine production after colonization in ex-germ-free rats and pigs

Abstract

We evaluated the contribution of nonpathogenic Escherichia coli O83 after colonization of germ-free (GF) rat pups and piglets on development of terminal α2,6- and α2,3-sialylated and broad range of terminal α1,2-, core α1,6-, and α1,3-, α1,4-fucosylated glycoconjugates in the suckling period relative to noncolonized GF and conventional (CV) counterparts. The ELISA-lectin approach was used to specify and quantify sialylated and fucosylated glycans in brush-border membrane vesicles (BBMV). Levels of pro- and anti-inflammatory cytokines in sera and splenocyte secretions were demonstrated using ELISA. Rat and pig intestinal responses to E. coli O83 monoassociation were different from those of GF and more similar to the CV animals in the decline of sialylated glycans, which is in agreement with the shorter life span of enterocytes in E. coli O83 monoassociated rats and pigs. No significant effect of E. coli O83 colonization on labeling fucosylated glycans was observed for immature fucosylation at the late suckling period. We demonstrate spontaneous secretion of pro-inflammatory cytokine IL-18 and anti-inflammatory IL-10 by GF rat splenocytes, and its suppression of IL-18 in E. coli O83 associated rat pups, and suggest that these cytokines serve as an immunomodulatory pool during the suckling period indicating the balance between T helper (Th) 1 and Th2 phenotypes.