Lectins as markers of rumen epithelial cell differentiation

Gastroesophageal reflux disease leads to major alterations in lectin-binding in the columnar epithelium of the gastroesophageal junction

OBJECTIVE

Chronic gastritis and esophagitis are associated with changes in glycosylation patterns. Lectins are carbohydrate-binding proteins that are used as sensitive tools in the analysis of glycosylation patterns. The aim was to investigate the binding patterns of lectins UEA-I, DBA, HPA and PNA at the squamocolumnar junction in relation to the existence of gastroesophageal reflux disease (GERD) and Helicobacter pylori (H. pylori) infection.

MATERIAL AND METHODS

Eighty-eight patients with either dyspeptic or gastroesophageal reflux-related symptoms were included in the study and stratified into four subgroups based on the presence of GERD and H. pylori infection. The binding patterns of lectins were examined immunohistochemically at the squamocolumnar junction, in squamous (SE) and columnar-lined epithelium (CLE). Staining patterns of lectins were semiquantitatively evaluated using an immunohistochemical score; data were analyzed using the non-parametric Mann-Whitney U-test.

RESULTS

The presence of GERD led to significant changes in lectin-binding patterns. Lectin-binding was significantly reduced for UEA-I (p<0.0001), DBA (p<0.0001), PNA (p<0.01) and DBA (p<0.05) in CLE and SE of patients with GERD, respectively. H. pylori infection was associated with reduced PNA and DBA binding to the deep glandular mucosa of CLE (p<0.05) and surface SE (p<0.05), respectively.

CONCLUSIONS

Distinct and complex changes in lectin-staining patterns are most prominent in CLE of patients with GERD. The functional relevance of changes in the glycosylation patterns needs further investigation.

Egg-matrix for large-scale single-step affinity purification of plant lectins with different carbohydrate specificities

Hen eggs represent an easily available and inexpensive source of glycoproteins expressing a variety of sugars. Egg glycoproteins might therefore be exploited to purify by affinity chromatography carbohydrate-binding proteins (lectins) with different specificities. A method to generate an affinity matrix from hen eggs is described. The matrix was assayed for its ability to purify in a single step biologically active phytohemagglutinin, wheat germ agglutinin, lentil lectin, and peanut agglutinin. Milligrams of purified lectins per gram of matrix was obtained, with the only exception of peanut agglutinin that was not efficiently retained into the affinity column. Hen egg chromatography is a relatively simple, fast, and reproducible method to purify high amount of plant lectins.

Light and electron microscopic investigation of the lectin-binding pattern in the oxyntic gland region of bovine abomasum

For the first time the expression of glycoconjugate residues in the oxyntic gland region of bovine abomasum has been investigated by means of lectin histochemistry. For light microscopic investigations, a battery of ten lectins, Con A, PSA, UEA I, WGA, LEA, SNA, RCA120, MPA, DBA and SBA was used. For electron microscopic examinations, WGA and RCA120 were utilized. The staining pattern of the lectins in all exocrine cell types of the oxyntic gland region is described. Compared to the results of monogastric species our study reveals some similarities, but just as many differences in the composition of glycoconjugate residues in bovine exocrine cell types. Typical for surface mucous cells is the amount of L-fucose, N-acetyl glucosamine residues and Galbeta1, 4GlcNAc sequences in the secretory granules. SNA could serve as a marker for surface mucous cells, because this lectin exclusively stains the plasma membrane and the secretory granules of surface mucous cells and the extracellular mucus. L-fucose and N-acetyl glucosamine are typical for the secretory granules of mucous neck cells. In addition, the secretory granules show the highest amount of N-acetyl galactosamine residues of all exocrine cells, so that DBA and SBA are recommended as marker lectins for mucous neck cells. Most lectins strongly stain the intracellular membrane system of oxyntic cells. The cocktail of glycoconjugates in the vicinity of the HCI production site provide protection against chemical injury. In chief cells only the apical plasma membrane is more or less labeled with all lectins apart from SNA. Specific marker lectins for oxyntic cells or chief cells of the bovine have not been characterized.

Characteristics of sheep-rumen isolates of Pseudomonas aeruginosa inhibitory to the growth of Escherichia coli O157

Screening facultative sheep-rumen bacteria which inhibit growth of Escherichia coli produced 11 strains of Pseudomonas aeruginosa. The isolates showed three different pulsed-field gel electrophoresis patterns and strains from different sheep produced pyocins that varied in strain specificity. Representative strains were resistant to ampicillin, methicillin, erythromycin, fusidic acid and augmentin, but not to tetracycline or nalidixic acid. Tested strains attached in large numbers to cultured rumen epithelial cells, potentially providing a means of survival in this ecosystem.

Attachment of different Escherichia coli strains to cultured rumen epithelial cells

The attachment to fully characterized primary rumen epithelial cell cultures of Escherichia coli strains isolated from different animal species and expressing F1-F4 or F17 fimbriae was examined. As the cell cultures contained stratified (keratinized) and non-stratified (non-keratinized) cells which grew either confluently or non-confluently, the strength of attachment of the different bacterial strains was assessed in relation to the differentiation state of the cells. Thus, strains having F1 fimbriae attached to all types of cultured cells, while strains with F2 and F3 fimbriae did not bind at all. E. coli strains having F4 or F17 fimbriae attached only to non-keratinized cells, particularly to confluent areas. As membrane glycosylation is known to change with differentiation (keratinization), our results suggest that the attachment of fimbriated E. coli strains which were capable of binding to rumen cells was more likely to be dependent on differentiation than the host specificity of the bacteria.

Characterization of Na+/H+ exchange in sheep rumen epithelial cells kept in primary culture

The study aimed at testing whether Na+/H+ exchange activity is maintained during isolation and cultivation of rumen epithelial cells (REC) and whether Na+/H+ exchange is altered during proliferation and differentiation. REC were isolated from sheep rumen epithelium by fractional trypsinization and further cultivated for up to 21 days. Characteristics of Na+ uptake into cultured REC were the same as previously described for the Na+/H+ exchange in the intact rumen epithelium. Na+ uptake was increased by intracellular acidification and was inhibited by high doses of amiloride. Amiloride inhibited 3H-thymidine incorporation into REC at concentrations similar to those found for the inhibition of Na+ uptake. Fetal calf serum, a growth factor, stimulated amiloride-sensitive Na+ uptake. We therefore conclude that cultured rumen epithelial cells express Na+/H+ exchange and that the activity of the exchange is at least correlated to the intensity of proliferation.