Biomedical subjects

M H Coconnier

Publications and source records attributed to M H Coconnier.

22 records · Page 2Linked to original sources

PubMed1992

Protein-mediated adhesion of Lactobacillus acidophilus BG2FO4 on human enterocyte and mucus-secreting cell lines in culture.

The adhesion of Lactobacillus acidophilus BG2FO4, a human stool isolate, to two human enterocytelike cell lines (Caco-2 and HT-29) and to the mucus secreted by a subpopulation of mucus-secreting HT29-MTX cells was investigated. Scanning electron microscopy revealed that the bacteria interacted with the well-defined apical microvilli of Caco-2 cells without cell damage and with the mucus secreted by the subpopulation of HT29-MTX cells. The adhesion to Caco-2 cells did not require calcium and involved an adhesion-promoting factor that was present in the spent supernatant of L. acidophilus cultures. This factor promoted adhesion of poorly adhering human Lactobacillus casei GG but did not promote adhesion of L. casei CNRZ 387, a strain of dairy origin. The adherence components on the bacterial cells and in the spent supernatant were partially characterized. Carbohydrates on the bacterial cell wall appeared to be partly responsible for the interaction between the bacteria and the extracellular adhesion-promoting factor. The adhesion-promoting factor was proteinaceous, since trypsin treatment dramatically decreased the adhesion of the L. acidophilus strain. The adhesion-promoting factor may be an important component of Lactobacillus species that colonize the gastrointestinal tract.

Bacterial Adhesion↗

PubMed1992

Expression of receptors for enterotoxigenic Escherichia coli during enterocytic differentiation of human polarized intestinal epithelial cells in culture.

To study the expression of human intestinal receptors for enterotoxigenic Escherichia coli (ETEC), the human polarized intestinal epithelial cell line Caco-2 in culture and several subpopulations of HT-29 cells in culture--parental (mainly undifferentiated) HT-29 cells (HT-29 Std), an enterocytelike subpopulation obtained by selection through glucose deprivation (HT-29 Glc-), and an enterocytelike subpopulation obtained by selection through glucose deprivation which maintains its differentiation characteristics when switched back to standard glucose-containing medium (HT-29 Glc-/+)--were used. Since Caco-2 spontaneously differentiated in culture under standard culture conditions (in the presence of glucose) and HT-29 cells were undifferentiated when cultured under standard conditions (HT-29 Std) and differentiated when grown in a glucose-free medium (HT-29 Glc-), we studied the expression of the receptors for colonization factor antigens (CFA) I, II, and III and the 2230 antigen of ETEC in relation to enterocytic differentiation. We provide evidence that expression of ETEC CFA receptors develops in parallel with other differentiation functions of the cultured cells. The expression of ETEC-specific brush border receptors was studied by indirect immunofluorescence using antibodies raised against purified ETEC CFA. No ETEC receptors were detected in HT-29 Std or short-term-cultured Caco-2 cells. However, among the population of HT-29 Std cells, 2 to 4% of the cells were found to bind ETEC, and these cells expressed positive carcinoembryonic antigen immunoreactivity. This indicated that among the population of undifferentiated HT-29 cells, clusters of differentiated cells were present. ETEC CFA receptors were expressed in the apical and basolateral domains of differentiated HT-29 cells, whereas in differentiated Caco-2 cells only apical expression was observed. Both in HT-29 cells (HT-29 Glc-/+) and in Caco-2 cells cultured under standard conditions, ETEC CFA receptors develop as a function of day in culture. This indicated that the expression of the ETEC CFA receptors was a growth-related event. Indeed, ETEC CFA receptors developed in step with the apical expression of differentiation-associated proteins.

Antigens, Bacterial↗

PubMed1991

Use of purified F1845 fimbrial adhesin to study localization and expression of receptors for diffusely adhering Escherichia coli during enterocytic differentiation of human colon carcinoma cell lines HT-29 and Caco-2 in culture.

Whole diffusely adhering Escherichia coli (DAEC) C1845 cells bearing the F1845 adhesive factor bind diffusely to differentiated human colon carcinoma cell lines HT-29 and Caco-2. By using antibodies directed against the purified fimbrial adhesin F1845 factor, the expression of the DAEC F1845-specific brush border receptors in the polarized human intestinal HT-29 and Caco-2 epithelial cells was studied by indirect immunofluorescence. A low level of DAEC F1845 receptors in undifferentiated intestinal cells was detected; they were localized in a cluster of cells. DAEC F1845 receptors were expressed at a high level in differentiated HT-29 and Caco-2 cells. DAEC F1845 receptors were expressed at a strikingly high level in the apical domains of the cells and developed during enterocytic differentiation in culture, in parallel with the apical expression of the intestinal brush border hydrolase, sucrase-isomaltase.

Bacterial Adhesion↗

PubMed1991

A new in vitro model of Entamoeba histolytica adhesion, using the human colon carcinoma cell line Caco-2: scanning electron microscopic study.

The human colon carcinoma cell line Caco-2, which is widely used to study the adhesion and cytotoxicity of enterobacteria, was used to investigate the adhesion of the trophozoites of Entamoeba histolytica. We observed a high percentage of adhesion of amoebae to Caco-2 cells. Scanning electron microscopy showed that amoebial membrane structures were involved in adhesion and the cytolytic action. These differentiated cells should prove to be a useful model system for investigation of the pathogenic action of amoebae.

Animals↗