Ileal Mucus Research Articles

Abnormal fucosylation of ileal mucus in cystic fibrosis: I. A histochemical study using peroxidase labelled lectins.

Peroxidase conjugated lectins were used to analyse the glycoproteins of small intestinal mucins in normal infants and those with cystic fibrosis to ascertain whether there are any detectable histochemical differences in saccharide composition. A significant decrease in Lotus tetragonolobus (LTG) binding fucose was shown in normal small intestinal mucin starting around 36 weeks' gestation with total absence of staining at term and beyond. In contrast, the age matched patients with cystic fibrosis showed persistent and intense LTG binding of fucose. These results provide the first clear histochemical evidence that cystic fibrosis mucin is abnormal and confirm the findings of previous biochemical studies.

Presence of K88-specific receptors in porcine ileal mucus is age dependent

Ileal mucus and epithelial cells were isolated from newborn piglets that had never been fed and 35-day-old unweaned piglets. Both newborn and 35-day-old piglet mucus preparations supported growth of Escherichia coli Bd 1107/75 08, a K88-fimbriated porcine enterotoxigenic strain, equally well (i.e., generation times of 28 min were observed in both cases). Adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet ileal epithelial cells was, at most, 2 times that of the same strain to newborn piglet ileal epithelial cells; however, adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet ileal mucus was 16 times that of the same strain to newborn piglet ileal mucus. The receptor in 35-day-old piglet ileal mucus was K88 specific, since it could be removed by purified K88ab fimbriae. Furthermore, adhesion of E. coli Bd 1107/75 08 to 35-day-old piglet ileal mucus was blocked by PAB10, a K88ab-, K88ac-, K88ad-specific monoclonal antibody. Although E. coli Bd 1107/75 08 traversed both newborn and 35-day-old piglet ileal mucus about equally well in vitro and bound well to underlying ileal epithelial cells after passing through newborn ileal mucus, it did not bind to ileal epithelial cells after passing through 35-day-old piglet ileal mucus. The data are discussed with respect to the role that K88-specific receptors present in newborn and ileal mucus might play in the pathogenesis of porcine enterotoxigenic E. coli strains which bear K88 fimbriae.

AnIn vitroStudy of Ileal Colonisation Resistance toEscherichia coliStrain Bd 1107/75 08 (K88) in Relation to Indigenous Squamous Gastric Colonisation in Piglets of Varying Ages

Ileal colonisation resistance to Escherichia coli strain Bd 1107/75 08 (K88) in piglets aged 5, 26 and 47 days and the possible relation to indigenous gastric colonisation was studied. In diluted ileal extracts, heat labile growth inhibitory activity was detected. At 26 d, the in vitro adhesion of K88 fimbriae on E. coli to ileal mucus was markedly increased, while the level of in vitro adhesion of Lactobacillus crispatus strain 152 to stomach tissue pieces decreased. In addition, scanning electron microscopy revealed that the composition of the squamous stomach epithelium associated flora changed dramatically at this time. From these results, it appears that age and consequently related factors influence the ileal colonisation resistance to E. coli strain Bd 1107/75 08 (K88) and the composition of the squamous indigenous gastric flora. Keywords: E. coli K88; Lactobacillus; Colonisation resistance; Adhesion; Growth.

AnIn vitroStudy of Ileal Colonisation Resistance toEscherichia coliStrain Bd 1107/75 08 (K88) in Relation to Indigenous Squamous Gastric Colonisation in Piglets of Varying Ages

Ileal colonisation resistance to Escherichia coli strain Bd 1107/75 08 (K88) in piglets aged 5, 26 and 47 days and the possible relation to indigenous gastric colonisation was studied. In diluted ileal extracts, heat labile growth inhibitory activity was detected. At 26 d, the in vitro adhesion of K88 fimbriae on E.coli to ileal mucus was markedly increased, while the level of in vitro adhesion of Lactobacillus crispatus strain 152 to stomach tissue pieces decreased. In addition, scanning electron microscopy revealed that the composition of the squamous stomach epithelium associated flora changed dramatically at this time. From these results, it appears that age and consequently related factors influence the ileal colonisation resistance to E.coli strain Bd 1107/75 08 (K88) and the composition of the squamous indigenous gastric flora.

In vitro adherence study using formalin-treated human small intestine: Fimbria-meidated adherence of enterotoxigenic Escherichia coli and Salmonella typhi oral-route vaccine strain possessing E. coli colonization factor antigen to villi and lymphoid folli

Enterotoxigenic Escherichia coli possessing colonization factor antigen (CFA)/I or CFA/II adhered to formalin-fixed human ileal villi with their CFA/I- or CFA/II-fimbriae. This adherence was host-specific. Adherence to formalin-fixed human ileal lymphoid follicle epithelium or mucus was also observed, although to a lesser extent. Salmonella typhi oral-route live vaccine strain possessing E. coli CFA/I manifested increased adherence to the human ileal mucosa.

Inhibition of attachment of Escherichia coli RDEC-1 to intestinal microvillus membranes by rabbit ileal mucus and mucin in vitro.

Intestinal mucus is postulated to play a role in preventing colonization of the gastrointestinal tract by microbial pathogens. To evaluate the ability of both crude mucus and purified mucin, a glycoprotein of goblet cell origin, to inhibit mucosal adherence of enteric pathogens, we examined whether mucus and mucin derived from rabbit ileum interact with the rabbit enteropathogen Escherichia coli RDEC-1. We examined the manner in which mucus and mucin inhibited adherence of bacteria to rabbit ileal microvillus membranes (MVMs) in vitro. The purity of the mucin preparation was demonstrated by polyacrylamide gel electrophoresis before and after reduction and by showing that an antiserum raised to the mucin localized to goblet cells in rabbit intestine. Using radioactive labeling of bacteria, we quantitated attachment of RDEC-1 to MVMs, mucus, and mucin that had been immobilized on polystyrene microtiter wells. Binding of RDEC-1 to MVMs was also determined after preincubation of organisms with crude ileal mucus and purified mucin. RDEC-1 bound to both crude mucus and purified mucin when they expressed lectinlike adhesions, previously designated attachment factor rabbit 1 pili. Adherence of piliated RDEC-1 to MVMs, mucus, and mucin was significantly greater than when the bacteria were nonpiliated. Binding of piliated RDEC-1 to MVMs was decreased by preincubation of bacteria with both crude mucus (45.6 +/- 4.2% of control) and purified mucin (50.2 +/- 5.8%). These data indicate that the E. coli enteropathogen RDEC-1 can bind to purified glycoproteins of goblet cell origin and that adherence of these bacteria to mucin is mediated by expression of pili. The findings also support a role for intestinal mucus and its principal organic constituent, mucin, in preventing adherence of a known E. coli enteric pathogen to apical MVMs of enterocytes.