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Biomedical subjects

M C Plotkowski

Publications and source records attributed to M C Plotkowski.

31 records · Page 2Linked to original sources
PubMed1992

Epithelial respiratory cells from cystic fibrosis patients do not possess specific Pseudomonas aeruginosa-adhesive properties.

Nasal polyp cells in primary culture from cystic fibrosis (CF) and non-CF patients were compared for the ability to bind Pseudomonas aeruginosa cells and for the presence of sulphated glycoconjugates at the epithelial cell surface. Quantitation of bacterial adhesion, by scanning electronmicroscopy, showed no significant difference between the cells cultured from CF and non-CF patients. Micro-organisms associated with ciliated cells were mainly aggregated, in contrast with those from non-ciliated cells. Sulphated glycoconjugates were identified on cells cultured from both CF and non-CF patients, regardless of whether or not these cells had attached bacteria. A matrix-like material that surrounded the aggregated bacteria was more prominent on cells cultured from CF patients than on those from non-CF patients. The interaction of aggregated P aeruginosa cells with polyp cells cultured from both CF and non-CF patients appeared to occur by means of this matrix material. Our findings suggest that chronic colonisation of the airways of CF patients cannot be explained by an increased affinity between the P. aeruginosa cells and the respiratory cell surface receptors in the CF patient. Nevertheless, the in-vitro observation that the matrix surrounding the bacteria reacted with a monoclonal antibody against respiratory mucins allows us to speculate that increased mucin secretion by cells from CF patients might, in vivo, play a decisive role in the interaction between P. aeruginosa and the respiratory epithelium.

Bacterial Adhesion↗
PubMed1992

Pseudomonas aeruginosa adhesion to normal and injured respiratory mucosa.

Human nasal polyps in outgrowth culture were used to study the adhesion of Pseudomonas aeruginosa to respiratory cells. By transmission electron microscopy, bacteria associated with ciliated cells were identified trapped at the extremities of cilia, usually as aggregates of several bacterial cells. They were never seen at the interciliary spaces or attached along cilia. Bacteria were also seen to adhere avidly to migrating cells of the periphery of the outgrowth culture. Using a model of repair of wounded respiratory epithelial cells in culture, we observed that the adhesion of P. aeruginosa to migrating cells of the edges of the repairing wounds was significantly higher than the adhesion to non-migrating cells and that adherent bacteria were surrounded by a fibronectin-containing fibrillar material. The secretion of extracellular matrix components is involved in the process of epithelium repair following injury. To investigate the molecular basis of P. aeruginosa adhesion to migrating cells, bacteria were treated with a fibronectin solution before their incubation with the respiratory cells. P. aeruginosa treatment by fibronectin significantly increased their adhesion to migrating cells. Accordingly, we hypothesize that during cell migration, fibronectin secreted by epithelial cells may favour P. aeruginosa adhesion by establishing a bridge between the bacteria and the epithelial cell receptors. Such a mechanism may represent a critical step for P. aeruginosa infection of healing injured epithelium.

Bacterial Adhesion↗
PubMed1991

Proliferation, differentiation and ciliary beating of human respiratory ciliated cells in primary culture.

The growth, differentiation, ciliary beating pattern and frequency of human respiratory ciliated cells in primary culture were studied by scanning and transmission electron microscopy and by videomicroscopy. The epithelial cells were obtained as outgrowth from explants of adult nasal polyps. When the explants were grown on type-I and type-IV collagen substrates in a standard serum-free, hormone-supplemented medium, a high percentage of ciliated cells (range 29 +/- 5% to 37 +/- 6%) was present within 2 days of culture. After 5 days of culture, the percentage of ciliated cells near the explant was 51 +/- 5%. Most of the cultured ciliated cells (85%) were characterized by individual cilia showing a coordinated movement during the beat cycle and a beating frequency (13.3 +/- 1.3 Hz) similar to that reported in vivo. In the other 15% of the ciliated cells, the dyskinetic cilia were aggregated into clumps and characterized by a rigid and planar bending movement and a lower (P less than 0.01) beating frequency (10.7 +/- 1.4 Hz). It is suggested that the latter type of cell, already described during fetal development, might be an intermediate type of ciliated cell which appears temporarily during the surface respiratory epithelial differentiation.

Cell Differentiation↗
PubMed1991

Differential adhesion of Pseudomonas aeruginosa to human respiratory epithelial cells in primary culture.

Human nasal polyps in outgrowth culture were used to study the Pseudomonas aeruginosa adhesion to respiratory cells. By scanning electron microscopy, P. aeruginosa were seen associated with ciliated cells, but by transmission electron microscopy, bacteria were never seen at the interciliary spaces or attached along cilia, but were identified trapped at the extremities of cilia, usually as bacterial aggregates. A fibronectin-containing fibrillar material was seen associated with aggregated bacteria. By time-lapse video microscopy, bacteria were seen to aggregate in the culture medium following their addition to the culture wells. Progressively, these aggregates were trapped by cilia or attached to migrating cells of a lower cell layer that protruded beneath the upper layer cells, at the outgrowth periphery. P. aeruginosa adhesion to these lower cell layer migrating cells was significantly higher than to ciliated or nonciliated cells of the upper cell layer. Migrating cells were intensely labeled by the complexes Con A and arachis hypogea agglutinin (PNA)-FITC, in contrast to the other cells. The percentage of PNA-labeled cells with attached bacteria was significantly higher than that without bacteria. These results suggest that changes of cell surface glycoconjugates related with cell migration may favor P. aeruginosa adhesion to respiratory cells.

Bacterial Adhesion↗
PubMed1990

Ultrastructural comparative distribution of carbohydrates in human tracheal and frog palate mucosa using neuraminidase and lectin-colloidal gold complexes.

We have compared, at the ultrastructural level, the carbohydrate structure of glycoconjugates of the different types of secretory cells of the human tracheal mucosa (HTM) and the frog palate mucosa (FPM), proposed as a model for studying bacterial adherence to mucus-coated respiratory epithelium. In addition to reactivity with Concanavalin A and Lens cullinaris agglutinin, reactivity of Epon-embedded HTM and FPM secretory granules was studied by transmission electron microscopy using neuraminidase-gold complex and colloidal gold-adsorbed lectins with affinity for sugar residues of human mucins, namely the following: Helix pomatia, Lotus tetragonolobus, Ricinus communis II, Wheat germ and Limax flavus agglutinins. The affinity of HTM and FPM mucous and serous cells for the different colloidal-gold complexes was very similar, however Limax flavus agglutinin labelled only HTM and not FPM secretory granules. The FPM mucous and serous secretory granules were nevertheless intensely labelled by the neuraminidase-gold complex, demonstrating the presence of sialic acid residues. The close ultrastructural and histochemical similarities between HTM and FPM suggest that the FPM may be a valuable model for studying the specific interaction between microbial lectins and mucus glycoproteins in the bacterial adherence phenomenon.

Animals↗
PubMed1989

The frog palate mucosa as a model for studying bacterial adhesion to mucus-coated respiratory epithelium.

Most of the methods proposed to quantify bacterial adherence to respiratory mucosa differ mainly from in vivo conditions in the absence of the mucus blanket and in the exposure of the sub-mucosal connective tissue (SMCT) to the micro-organisms. We propose the frog palate as a model to study bacterial adhesion to the respiratory mucosa, with a system which allows the mucus to be preserved and the bacterial adhesion to be quantified in a standardized mucosal area, where mucociliary transport is still active. In order to evaluate the role of respiratory mucus in bacteria-mucosa interaction, we compared the adhesion of radiolabelled pneumococci to 12 mucus-coated and 10 non-mucus-coated frog palate mucosae. The presence or absence of mucus was controlled by scanning electron microscopy (SEM). After a 10 min incubation period, the bacterial adhesion to mucus-coated palate mucosa was five times greater (P less than 0.01) than that to uncoated mucosa. By SEM, bacteria were never seen attached to ciliated cells but could be detected on small areas where mucus was not totally eliminated. Even after a 120 min contact of bacteria to uncoated mucosa, bacterial adhesion remained only half that to mucus-coated epithelium. In order to ascertain whether the exposure of the SMCT represented a means of attraction to bacteria, we incubated the frog palate mucosa face-down with radiolabelled Pseudomonas aeruginosa. As much as 44 per cent of added bacteria adhered to exposed SMCT and, by SEM, numerous micro-organisms were seen attached to connective tissue. In contrast, only a few bacteria were observed adhering to the mucosa, mainly to granules of mucus.

Animals↗
PubMed1989

Adherence of Pseudomonas aeruginosa to respiratory epithelium and the effect of leucocyte elastase.

The tracheobronchial secretions from patients with cystic fibrosis often contain high amounts of free proteases. To evaluate whether human leucocyte elastase (HLE) can favour the persistence of bacterial airways infection, we exposed the frog palate mucosa to HLE and then to radiolabelled Pseudomonas aeruginosa and followed the sequence of events by scanning electronmicroscopy. In response to HLE there was a marked outpouring of mucus and a desquamation of the epithelium. P. aeruginosa was shown to adhere to recently secreted granules of mucus and to the exposed submucosal underlying connective tissues. For the eight different bacterial strains studied, a significative adherence to HLE-injured mucosa was observed only in strains that possessed internal haemagglutinating activity. Neither the presence of fimbriae, nor of the mucoid exopolysaccharide, nor of the bacterial surface haemagglutinating activity could be related to adherence of P. aeruginosa to the injured mucosa. These results support the hypothesis that HLE enhances bacterial infection of the respiratory mucosa both by inducing mucus hypersecretion and by exposing receptors to the microbial adhesins. It is also suggested that P. aeruginosa internal lectins may be implicated in adherence to host tissues.

Animals↗
PubMed1988

A new model for studying bacterial adherence to the respiratory epithelium.

The frog palate mucosa was used as a new model for studying bacterial adherence to the respiratory epithelium. The main advantage of this model is that the mucus blanket, normally present on airway mucosa, can be preserved during the assays. The adherence of radiolabeled pneumococci to mucus-coated mucosa was five times higher (P less than 0.001) than the adherence to mucus-depleted mucosa. In the latter case, bacteria were never seen attached to ciliated cells but could be detected on small remaining patches of mucus. These results demonstrate that respiratory mucus plays a major role in bacteria-mucosa interactions.

Animals↗
PubMed1987

The 99m technetium labeling effect on bacterial surface properties.

The present study was undertaken to determine whether labeling Pseudomonas aeruginosa with 99m Technetium would modify some of the bacterial physicochemical surface properties which play an important role in the interaction between bacteria and eukaryotic cells. No significant difference in electrophoretic mobility or distribution of cationized ferritin on the cell surface was observed between labeled and unlabeled bacteria. Also, the 99m Tc labeling process did not modify bacterial hydrophobicity or adhesiveness to human buccal epithelial cells. It is concluded that bacterial labeling with 99m Tc can be accepted as a useful method for biological research.

Bacterial Adhesion↗
PubMed1987

Effect of human airway lysozyme on the in vitro growth of type I Streptococcus pneumoniae.

The effects of purified human airway lysozyme and hen egg-white lysozyme on growth rate and viability of growing type I Streptococcus pneumoniae were studied. Exposure of bacteria to human and hen lysozyme at the same final concentration (100 micrograms/ml) for 1.5-4.5 h resulted in a marked reduction of the number of colony-forming units per ml compared to control cultures. After a 1.5-h exposure to human or hen lysozyme, the remaining percentage of colony forming units per ml was 54% and 69%, respectively. The onset of growth only appeared after a 3.5-h exposure period for human lysozyme whereas it began at 2.5 h for hen lysozyme. After 3.5 h and 4.5 h of exposure, the number of colony-forming units was significantly lower (p less than 0.05) in human lysozyme-treated bacteria cultures compared to control cultures. Parallel electron microscopic observations of Streptococcus pneumoniae cultures confirmed that the density of pneumococci was less in the presence of either human lysozyme or hen lysozyme in comparison to control cultures, and showed the presence of numerous long, ribbon-like material and cytoplasmic condensations liberated in the culture medium.

Bronchi↗
PubMed1986

Adherence of type I Streptococcus pneumoniae to tracheal epithelium of mice infected with influenza A/PR8 virus.

Bacterial adherence to virus-infected respiratory tract cells may be one of the several mechanisms whereby virus predisposes to bacterial pneumonia. To evaluate the effect of influenza virus infection on pneumococcus adhesion, 39 mice were infected with PR8/A influenza virus. The adherence of radiolabeled pneumococcus to mice tracheal cells was determined 2, 4, and 6 days after viral inoculation. The pneumococcal adhesion to infected tracheas was significantly enhanced on Day 6 (p less than 0.001). Scanning and transmission electron microscopy revealed that by the fourth and sixth days after virus inoculation, the ciliated and the secretory cells of the tracheal epithelium had desquamated and the mucosa were coated with a continuous layer of basal cells. In a few cases, a desquamation of the basal layer was observed and the exposed basement membrane appeared as a pole of attraction for bacteria. Pneumococci were never seen attached to control tracheas. In contrast, they were observed adhered to the microvilli of the basal cells and, to a greater extent, to the exposed basement membrane.

Animals↗