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

A novel in vitro model of primary human pediatric lung epithelial cells

BACKGROUND

Current in vitro human lung epithelial cell models derived from adult tissues may not accurately represent all attributes that define homeostatic and disease mechanisms relevant to the pediatric lung.

METHODS

We report methods for growing and differentiating primary Pediatric Human Lung Epithelial (PHLE) cells from organ donor infant lung tissues. We use immunohistochemistry, flow cytometry, quantitative RT-PCR, and single cell RNA sequencing (scRNAseq) analysis to characterize the cellular and transcriptional heterogeneity of PHLE cells.

RESULTS

PHLE cells can be expanded in culture up to passage 6, with a doubling time of ~4 days, and retain attributes of highly enriched epithelial cells. PHLE cells can form resistant monolayers, and undergo differentiation when placed at air-liquid interface. When grown at Air-Liquid Interface (ALI), PHLE cells expressed markers of airway epithelial cell lineages. scRNAseq suggests the cultures contained 4 main sub-phenotypes defined by expression of FOXJ1, KRT5, MUC5B, and SFTPB. These cells are available to the research community through the Developing Lung Molecular Atlas Program Human Tissue Core.

CONCLUSION

Our data demonstrate that PHLE cells provide a novel in vitro human cell model that represents the pediatric airway epithelium, which can be used to study perinatal developmental and pediatric disease mechanisms.

Non-diluted seawater enhances nasal ciliary beat frequency and wound repair speed compared to diluted seawater and normal saline

Background

The regulation of mucociliary clearance is a key part of the defense mechanisms developed by the airway epithelium. If a high aggregate quality of evidence shows the clinical effectiveness of nasal irrigation, there is a lack of studies showing the intrinsic role of the different irrigation solutions allowing such results. This study investigated the impact of solutions with different pH and ionic compositions, eg, normal saline, non‐diluted seawater and diluted seawater, on nasal mucosa functional parameters.

Methods

For this randomized, controlled, blinded, in vitro study, we used airway epithelial cells obtained from 13 nasal polyps explants to measure ciliary beat frequency (CBF) and epithelial wound repair speed (WRS) in response to 3 isotonic nasal irrigation solutions: (1) normal saline 0.9%; (2) non‐diluted seawater (Physiomer®); and (3) 30% diluted seawater (Stérimar). The results were compared to control (cell culture medium).

Results

Non‐diluted seawater enhanced the CBF and the WRS when compared to diluted seawater and to normal saline. When compared to the control, it significantly enhanced CBF and slightly, though nonsignificantly, improved the WRS. Interestingly, normal saline markedly reduced the number of epithelial cells and ciliated cells when compared to the control condition.

Conclusion

Our results suggest that the physicochemical features of the nasal wash solution is important because it determines the optimal conditions to enhance CBF and epithelial WRS thus preserving the respiratory mucosa in pathological conditions. Non‐diluted seawater obtains the best results on CBF and WRS vs normal saline showing a deleterious effect on epithelial cell function.

Interaction of Mycobacterium leprae with human airway epithelial cells: adherence, entry, survival, and identification of potential adhesins by surface proteome analysis

This study examined the in vitro interaction between Mycobacterium leprae, the causative agent of leprosy, and human alveolar and nasal epithelial cells, demonstrating that M. leprae can enter both cell types and that both are capable of sustaining bacterial survival. Moreover, delivery of M. leprae to the nasal septum of mice resulted in macrophage and epithelial cell infection in the lung tissue, sustaining the idea that the airways constitute an important M. leprae entry route into the human body. Since critical aspects in understanding the mechanisms of infection are the identification and characterization of the adhesins involved in pathogen-host cell interaction, the nude mouse-derived M. leprae cell surface-exposed proteome was studied to uncover potentially relevant adhesin candidates. A total of 279 cell surface-exposed proteins were identified based on selective biotinylation, streptavidin-affinity purification, and shotgun mass spectrometry; 11 of those proteins have been previously described as potential adhesins. In vitro assays with the recombinant forms of the histone-like protein (Hlp) and the heparin-binding hemagglutinin (HBHA), considered to be major mycobacterial adhesins, confirmed their capacity to promote bacterial attachment to epithelial cells. Taking our data together, they suggest that the airway epithelium may act as a reservoir and/or portal of entry for M. leprae in humans. Moreover, our report sheds light on the potentially critical adhesins involved in M. leprae-epithelial cell interaction that may be useful in designing more effective tools for leprosy control.

Analysis of cell dispersion and migration by video-microscopy

In different physiopathological situations such as embryogenesis, wound repair and tumor invasion, isolated cells, or cell populations exhibit changes to their normal behavior and may acquire different migratory phenotypes. Live-cell imaging associated with the use of appropriate in vitro models in culture has become a powerful analytical tool for studying factors involved in cell migration and in cell-to-cell interactions. The scope of this chapter is to give an overview of in vitro models of cell migration and the technical advances permitting multiparameter quantification. The chapter hereby provides a detailed description of two-dimensional and three-dimensional approaches of cell dispersion and migration and finally gives a brief insight on computational quantification of the cell behavior.

In vitro culturing of ciliary respiratory cells--a model for studies of genetic diseases

Primary ciliary dyskinesia (PCD) is a rare genetic disorder caused by the impaired functioning of ciliated cells. Its diagnosis is based on the analysis of the structure and functioning of cilia present in the respiratory epithelium (RE) of the patient. Abnormalities of cilia caused by hereditary mutations closely resemble and often overlap with defects induced by the environmental factors. As a result, proper diagnosis of PCD is difficult and may require repeated sampling of patients' tissue, which is not always possible. The culturing of differentiated cells and tissues derived from the human RE seems to be the best way to diagnose PCD, to study genotype-phenotype relations of genes involved in ciliary dysfunction, as well as other aspects related to the functioning of the RE. In this review, different methods of culturing differentiated cells and tissues derived from the human RE, along with their potential and limitations, are summarized. Several considerations with respect to the factors influencing the process of in vitro differentiation (cell-to-cell interactions, medium composition, cell-support substrate) are also discussed.

Video-microscopic imaging of cell spatio-temporal dispersion and migration

Live-cell imaging has become a powerful analytical tool in most cell biology laboratories. The scope of this paper is to give an overview of the environmental considerations for maintaining living cells on the microscope stage and the technical advances permitting multi-parameter imaging. The paper will then focus on two-dimensional and three-dimensional analysis of cell dispersion and migration and finally give a brief insight on computational modeling of the cell behavior.

Non-adhesive organ culture of human biliary epithelium with stroma

OBJECTIVE

Explanted tissue has been shown to keep adult human cells in organ culture with a preserved morphology for at least one month as spheres in a non-adhesive organ culture. In the present study, we explored whether also human biliary epithelium can be grown in this manner, because the result may be of interest in studies of hepato-biliary-pancreatic carcinogenesis. MATERIAL AND METHODS. Small tissue samples were obtained from the gallbladder wall of patients who had been operated upon with cholecystectomy. Fragments of about 300 microm in diameter from each patient were cultured and investigated with light microscopy at the time of explantation and after 5, 10, 20, 30 and 40 days of culture. Scanning and transmission electron microscopy were performed to demonstrate the ultrastructure. Incubation of cultured fragments with the vital dyes revealed a viable epithelium.

RESULTS

At the time of explantation, all the tissue fragments had a rough appearance with an uneven, torn periphery, while during the first few days of culture they became rounder with a smooth-looking surface covering the entire circumference. This spheroid morphology persisted for the remainder of the culture period. The core of the fragments harboured connective tissue with vascular elements, fibroblasts and leucocytes. Immunostaining for cytokeratin 7, 19 and 20 revealed a strong positive staining of the epithelium.

CONCLUSIONS

These results show that biliary epithelium can be grown in vitro in a non-adhesive organ culture with their stroma.

[Tissue engineering of respiratory epithelium. Regenerative medicine for reconstructive surgery of the upper airways]

Reconstruction of long tracheal defects remains an unsolved surgical problem. Tissue engineering of respiratory epithelium is therefore of utmost surgical and scientific interest. Successful cultivation and reproduction of respiratory epithelium in vitro is crucial to seed scaffolds of various biomaterials with functionally active respiratory mucosa. Most frequently, the suspension culture as well as the tissue or explant cultures are used. Collagenous matrices, synthetic and biodegradable polymers, serve as carriers in studies. It is essential for clinical practice that mechanically stable biomaterials be developed that are resorbable in the long term or that cartilaginous constructs produced in vitro be employed which are seeded with respiratory epithelium before implantation. Vascularization of a bioartificial matrix for tracheal substitution is also prerequisite for integration of the constructs produced in vitro into the recipient organism. Here, the state of the art of research, perspectives and limitations of tracheal tissue engineering are reviewed.

Bronchial epithelial spheroids: an alternative culture model to investigate epithelium inflammation-mediated COPD

Background

Chronic obstructive pulmonary disease (COPD) is characterized by abnormal lung inflammation that exceeds the protective response. Various culture models using epithelial cell lines or primary cells have been used to investigate the contribution of bronchial epithelium in the exaggerated inflammation of COPD. However, these models do not mimic in vivo situations for several reasons (e.g, transformed epithelial cells, protease-mediated dissociation of primary cells, etc.). To circumvent these concerns, we developed a new epithelial cell culture model.

Methods

Using non transformed non dissociated bronchial epithelium obtained by bronchial brushings from COPD and non-COPD smokers, we developed a 3-dimensional culture model, bronchial epithelial spheroids (BES). BES were analyzed by videomicroscopy, light microscopy, immunofluorescence, and transmission electron microscopy. We also compared the inflammatory responses of COPD and non-COPD BES. In our study, we chose to stimulate BES with lipopolycaccharide (LPS) and measured the release of the pro-inflammatory mediators interleukin-8 (IL-8) and leukotriene B4 (LTB4) and the anti-inflammatory mediator prostaglandin E2 (PGE2).

Results

BES obtained from both COPD and non-COPD patients were characterized by a polarized bronchial epithelium with tight junctions and ciliary beating, composed of basal cells, secretory cells and ciliated cells. The ciliary beat frequency of ciliated cells was not significantly different between the two groups. Of interest, BES retained their characteristic features in culture up to 8 days. BES released the inflammatory mediators IL-8, PGE2 and LTB4 constitutively and following exposure to LPS. Interestingly, LPS induced a higher release of IL-8, but not PGE2 and LTB4 in COPD BES (p < 0.001) which correlated with lung function changes.

Conclusion

This study provides for the first time a compelling evidence that the BES model provides an unaltered bronchial surface epithelium. More importantly, BES represent an attractive culture model to investigate the mechanisms of injuring agents that mediate epithelial cell inflammation and its contribution to COPD pathogenesis.

Recombinant Escherichia coli as a gene delivery vector into airway epithelial cells

To transfer genes into airway epithelial cells, we have generated auxotrophic dap Escherichia coli BM2710 mutant that expresses the invasin of Yersinia pseudotuberculosis and the listeriolysin of Listeria monocytogenes. E. coli BM2710 harboring a plasmid carrying the gfp gene was incubated with immortalized normal or cystic fibrosis (CF) airway epithelial cells or with primary bronchial epithelial cells grown as an explant-outgrowth cell culture model. Approximately 2% of immortalized cells expressed GFP. Few primary cells were transfected that were always poorly differentiated and located at the edge of the outgrowth. This was consistent with the expression of beta1-integrins only on these cells and with the required interaction for cell entry of E. coli expressing the invasin with beta1-integrins. The subsequent intracellular trafficking of E. coli BM2710 studied by confocal and electronic microscopy showed that the E. coli-containing phagosomes rapidly matured into phagolysosomes. This is the first demonstration that recombinant bacteria are able to transfer genes into primary airway epithelial cells, provided that they are able to invade the cells.

Uptake of plasmid/glycosylated polymer complexes and gene transfer efficiency in differentiated airway epithelial cells

BACKGROUND

We have studied gene transfer efficiency of glycosylated polylysines and glycosylated polyethylenimines as vectors in immortalized differentiated airway gland serous cells and primary cultures of human airway surface epithelial cells.

METHODS AND RESULTS

In both cell types, lactosylated PEI was more efficient for gene transfer than unsubstituted PEI and lactosylated polylysine which requires the presence of endosomolytic agents. However, for all the vectors tested, gene transfer efficiency was lower in differentiated cells as compared with poorly differentiated cells. The presence of membrane lectins, i.e. cell surface sugar-specific receptors, was evaluated using fluorescein-conjugated neoglycoproteins and microscopy or flow cytometry. In differentiated airway surface epithelial cells, membrane lectins were not expressed and plasmid DNA/fluorescein-conjugated glycosylated polymer complexes were not incorporated. This accounted in part for the lack of gene transfer efficiency in these cells. In contrast, in differentiated airway gland serous cells, expression of lectins and their endocytotic properties appeared to be similar to that observed in undifferentiated cells, and plasmid DNA/fluorescein-conjugated glycosylated polymer complexes were incorporated in similar amounts by cells in both differentiated states

CONCLUSIONS

Glycosylated PEI appears to be a promising gene delivery system since it is more efficient than the sugar-free polymer and does not require endosomolytic agents. However, in differentiated airway gland serous cells, a low gene transfer efficiency was observed that could not be attributed to low expression of membrane lectins or low uptake of glycosylated complexes. An impaired intracellular trafficking of glycosylated complexes in differentiated airway gland serous cells is suggested.

Nonadhesive organ culture of human exocrine pancreatic cells with their stroma

INTRODUCTION

Studies using explanted tissue have shown that it is possible to keep adult human cells in organ culture with a preserved morphology for up to 1 month as spheres in a nonadhesive organ culture.

AIMS

The current study was to determine whether human exocrine pancreatic cells also can be grown in this manner.

METHODOLOGY

Small tissue samples from organ donors and tumor-free resection rim from patients with pancreatic carcinoma were obtained (n = 16 adults). From each patient, fragments of approximately 300 microm in diameter were cultured and investigated with light microscopy and scanning and transmission electron microscopy at the time of explantation and after 5, 10, 20, 30, and 40 days of culture.

RESULTS

Incubation of cultured fragments with vital dyes revealed a viable epithelium. At the time of explantation all the tissue fragments had a rough appearance with an uneven, torn periphery. During the first week of culture the fragments became rounder, with a smooth surface covering the whole circumference. This spheroid morphology persisted for the rest of the 6-week culture period. The fragments were within 1 week covered by a highly differentiated, polarized epithelium with secretory apparatus, apical secretion granules, and microvilli, as well as specialized cell junctions, with the same appearance as acinoductal pancreatic cells of the original tissue. The core of the fragments consisted of connective tissue with vascular elements, fibroblasts, leukocytes, and a few ductal and acinar elements. Transmission electron microscopy of the spheroids revealed a continuous basal lamina underneath the epithelium. Immunostaining for cytokeratin 5, 6, 7, 8, 17, and 18 was strongly positive in the epithelium.

CONCLUSION

These results show that normal exocrine pancreatic cells can be grown in vitro in a nonadhesive organ culture with their stroma.

Fibronectin-binding proteins of Staphylococcus aureus are involved in adherence to human airway epithelium

This study was designed to investigate the molecular mechanisms of Staphylococcus aureus adherence to human airway epithelium. Using a humanized bronchial xenograft model in the nude mouse and primary cultures of human airway epithelial cells (HAEC), we showed that S. aureus adhered mainly to undifferentiated HAEC whereas weak adherence (11- to 20-fold lower) to differentiated HAEC was observed (P < 0.01). A fibronectin (FN)-binding protein (FnBP)-deficient strain of S. aureus had a fivefold-lower adherence level to undifferentiated HAEC than did the parental strain (P < 0.005), suggesting that S. aureus FN-binding capacity is involved in the adherence to HAEC. We also showed that 97% of 32 S. aureus clinical strains, isolated from the airway secretions of cystic fibrosis patients (n = 18) and patients with nosocomial pneumonia (n = 14), possessed the two fnb genes. The strains from pneumonia patients had a significantly (P < 0.05) higher FN-binding capacity than did the strains from CF patients. This result was confirmed by the expression of FnBPs, investigated by Western ligand affinity blotting. Our results suggest a major role of FnBPs in the colonization of the airways by S. aureus and point to the importance of the adhesin regulatory pathways in the staphylococcal infectious process.

Cell wall-associated protein A as a tool for immunolocalization of Staphylococcus aureus in infected human airway epithelium

Staphylococcus aureus is a common human pathogen involved in non-bronchial diseases and in genetic and acquired bronchial diseases. In this study, we applied an immunolabeling approach for in vivo and in vitro detection of S. aureus, based on the affinity of staphylococcal protein A (SpA) for the Fc region of immunoglobulins, especially IgG. Most strains of S. aureus, including clinical strains, can be detected with this labeling technique. The approach can be used for detection and localization with transmission electron microscopy or light-fluorescence microscopy of S. aureus in infected tissues such as human bronchial tissue from cystic fibrosis (CF) patients. The methodology can also be applied to cell culture models with the aim of characterizing bacterial adherence to epithelial cells in backscattered electron imaging with scanning electron microscopy. Application to the study of S. aureus adherence to airway epithelium showed that the bacteria did not adhere in vivo to intact airway epithelium. In contrast, bacteria adhered to the basolateral plasma membrane of columnar cells, to basal cells, to the basement membrane and were identified beneath the lamina propria when the epithelium was injured and remodeled, or in vitro when the epithelial cells were dedifferentiated.

Nasal mucociliary clearance as a factor in nasal drug delivery

The nasal mucociliary clearance system transports the mucus layer that covers the nasal epithelium towards the nasopharynx by ciliary beating. Its function is to protect the respiratory system from damage by inhaled substances. Impairment of nasal mucociliary clearance can result in diseases of the upper airways. Therefore, it is important to study the effects of drugs and drug excipients on nasal mucociliary clearance. A large number of methods are used to assess mucociliary clearance. These methods study the effects of drug and excipients on the mucociliary system in vitro or in vivo in animals and humans. In some cases, the results of different in vitro and in vivo measurements do not correlate well. In vitro methods, especially ciliary beat frequency measurements, have been demonstrated to be valuable tools for toxicity screening. However, in vivo studies are essential to confirm the safety of nasal drug formulations. Nasal mucociliary clearance also has implications for nasal drug absorption. Drugs are cleared rapidly from the nasal cavity after intranasal administration, resulting in fast systemic drug absorption. Several approaches are discussed to increase the residence time of drug formulations in the nasal cavity, resulting in improved nasal drug absorption. However, more experimental evidence is needed to support the conclusion that this improved absorption is caused by a longer residence time of the nasal drug formulation.

ATP depletion induces a loss of respiratory epithelium functional integrity and down-regulates CFTR (cystic fibrosis transmembrane conductance regulator) expression

To mimic the effect of ischemia on the integrity of airway epithelium and expression of cystic fibrosis transmembrane conductance regulator (CFTR), we induced an ATP depletion of the respiratory epithelium from upper airway cells (nasal tissue) and human bronchial epithelial 16HBE14o- cell line. Histological analysis showed that 2 h of ATP depletion led to a loss of the epithelium integrity at the interface between basal cells and columnar cells. The expression of connexin 43 (Cx43, subunit of the gap junctions) and desmoplakins 1 and 2 (DPs 1 and 2, major components of the desmosomes) proteins was inhibited. After 90 min of ATP depletion, a significant decrease of the transepithelial resistance (25%) was observed but was reversible. Similar results were obtained with the 16HBE14o- human bronchial epithelial cell line. ATP depletion led to actin filaments depolymerization. The expression of the mature CFTR (170 kDa) and fodrin proteins at the apical domain of the ciliated cells was down-regulated. The steady-state levels of CFTR, Cx43, DPs 1 and 2 mRNAs, semiquantified by RT-polymerase chain reaction kinetics, remained constant throughout ATP depletion in nasal tissue as in the homogeneous cell population of 16HBE14o- human bronchial epithelial cell line. This suggests that the down-regulation of these proteins might be posttranscriptional. The intercellular diffusion through gap junctions of Lucifer dye was completely inhibited after 90 min of ATP depletion but was reversible. The volume-dependent and the cAMP-dependent chloride secretion were inhibited in a nonreversible way. Taken together, these results suggest that an ATP depletion in human airway epithelium, mimicking ischemia, may induce a marked alteration in the junctional complexes and cytoskeleton structure concomitantly with a loss of apical CFTR expression and chloride secretion function.

Morphologic and motility changes of nasal cilia in primary culture caused by Haemophilus influenzae

We focused on the pathogenicity of otitis media with effusion (OME) with respect to the susceptibility of the upper respiratory tract mucosa to Haemophilus influenzae. Human nasal polyps in outgrowth culture were used to study H influenzae disturbance of the ciliary beat frequency (CBF) and the morphology of cilia. The CBF of control primary culture was 11.7 +/- 2.7 Hz. The CBF slowed down significantly, to 8.5 +/- 5.7 Hz, after incubation with the filtrate of 10(8) CFU/mL of H influenzae, and to 4.1 +/- 4.1 Hz with a suspension of 10(8) CFU/mL of H influenzae (p<.05). In the morphologic study, we classified the shapes of the cilia into five types: normal cilia, immotile cilia, swollen cilia, clumped cilia, and exfoliated ciliated cells. The abnormal shapes of cilia increased after incubation with the suspension or the filtrate of H influenzae. By scanning electron microscopy, we saw that aggregated bacteria tended to associate with cilia. Thus, the findings suggest that H influenzae disturbs the ciliary clearance of nasal cells and makes them more susceptible to infections.

Asialo GM1 is a receptor for Pseudomonas aeruginosa adherence to regenerating respiratory epithelial cells

We investigated the implication of asialo GM1 as an epithelial receptor in the increased Pseudomonas aeruginosa affinity for regenerating respiratory epithelial cells from cystic fibrosis (CF) and non-CF patients. Human respiratory epithelial cells were obtained from nasal polyps of non-CF subjects and of CF patients homozygous for the delta F 508 transmembrane conductance regulator protein (CFTR) mutation and cultured according to the explant-outgrowth model. At the periphery of the outgrowth, regenerating respiratory epithelial cells spreading over the collagen I matrix with lamellipodia were observed, characteristic of respiratory epithelial wound repair after injury. P aeruginosa adherence to regenerating respiratory epithelial cells was found to be significantly greater in the delta F 508 homozygous CF group than in the non-CF group (P < 0.001). In vitro competitive binding inhibition assays performed with rabbit polyclonal antibody against asialo GM1 demonstrated that blocking asialo GM1 reduces P. aeruginosa adherence to regenerating respiratory epithelial cells in delta F 508 homozygous cultures (P < 0.001) as well as in non-CF cultures (P < 0.001). Blocking of asialo GM1 was significantly more efficient in CF patients than in non-CF subjects (P < 0.05). Distribution of asialo GM1 as determined by preembedding labelling and immunoelectron microscopy clearly demonstrated the specific apical membrane expression of asialo GM1 by regenerating respiratory epithelial cells, whereas other cell phenotypes did not apically express asialo GM1. These results demonstrate that (i) asialo GM1 is an apical membrane receptor for P. aeruginosa expressed at the surface of CF and non-CF regenerating respiratory epithelial cells and (ii) asialo GM1 is specifically recovered in regenerating respiratory epithelium. These results suggest that in CF, epithelial repair represents the major event which exposes asialo GM1 for P. aeruginosa adherence.

In vitro and in vivo gene transfer to pulmonary cells mediated by cationic liposomes

Cationic liposomes have been proposed as alternative to adenovirus in the treatment of cystic fibrosis lung disease. Therefore, we have investigated the efficiency of two lipid mixtures in mediating gene transfer in in vitro and in vivo models. The cationic lipid DOTMA (N-(1-(2,3(dioleyloxy)propyl)-n,n,n-trimethylammoniumchloride++ +) and DOGS (dioctadecylamidoglycylspermine) were used in combination with the neutral lipid DOPE (dioleoylphosphatidylethanolamine). The relative transfection efficiencies of the two cationic liposomes were tested using the bacterial beta-galactosidase (lacZ) and the firefly luciferase genes. Gene expression was detected in both cell limes and primary culture of rhesus monkey airway epithelium after transfection with plasmid DNA complexed with DOGS/DOPE or DOTMA/DOPE. Transfection efficiency of both types of lipids was higher in the mouse fibroblast 3T3 cell line as compared to human carcinoma A549 cells and primary epithelial cultures. Administration of DNA-liposome complexes via intratracheal instillation resulted in expression of the lacZ and luciferase marker gene in the mouse airways. In vivo transfection mediated by both types of liposomes were proven to be far less efficient than adenovirus treatment.

Regenerating cells in human airway surface epithelium represent preferential targets for recombinant adenovirus

To investigate the efficiency of adenovirus-mediated gene delivery in regenerating human respiratory epithelium, we have performed infections with an E1- and E3-deleted type 5 recombinant adenovirus containing the Escherichia coli LacZ reporter gene on different culture models of regenerating human nasal polyp surface epithelium. These models included: (i) an ex vivo organ culture of nasal polyp tissue, (ii) an explant outgrowth cell culture, and (iii) an in vitro wound repair model, on dissociated cells. In ex vivo nasal polyp tissue, transduced cells were not detected in normal pseudostratified areas, but were found in areas of the surface epithelium with a morphology reminiscent of regenerating airway tissue. In the explant outgrowth cell culture, adenovirus-infected cells were preferentially detected at the periphery of the outgrowth. These transducible epithelial cells, representative of epithelial cells present in vivo during the process of surface airway epithelium regeneration, were shown to be migrating and poorly differentiated cells, which were proliferating or not. In the in vitro wound repair model, the efficiency of cell transduction was much higher in cells present in the wound area than in those far from the wound area. These results indicate that regenerating cells from human airway surface epithelium represent preferential targets for transgene expression, and suggest that efficiency of CFTR gene transfer by recombinant adenovirus vectors may be higher in regenerating CF airway mucosa than in normal tissue. However, since these cells do not show endogenous CFTR expression, the relevance of their preferential transduction for the functional correction of the ion transport defect in cystic fibrosis needs further investigations.

Ciliogenesis and mucus synthesis in cultured human respiratory epithelial cells

The mechanisms for the regulation of ciliogenesis and for the synthesis of mucus are not well understood. We sought to develop a culture system for differentiating ciliated and secretory types of human respiratory epithelial (HRE) cells. Dissociated HRE cells obtained from nasal polyps and maxillary sinus mucosa were cultured on type I collagen gel. Cells grown to confluence on collagen gel lost their cilia and exhibited a flat, squamous-like appearance. After reaching confluence, the cultured cells with a collagen gel substrate were removed from plastic dishes and floated in the culture medium. After 7 days in the floating culture, some cells exhibited several centrioles or basal bodies, while others showed secretory granules. The secretory phenotype predominated after 7 days. After 14 days in the floating culture, nearly all cells were ciliated. The results demonstrate that the differentiation of HRE cells can be induced by floating cultured cells with a collagen gel substrate in a defined culture medium.

Cytotoxicity of Pseudomonas aeruginosa internal lectin PA-I to respiratory epithelial cells in primary culture

Pseudomonas aeruginosa is the most important bacterial pathogen associated with chronic airway infection, especially in cystic fibrosis. We addressed the question of whether the galactophilic internal lectin of P. aeruginosa (PA-I) could represent a virulence factor for the respiratory epithelium. PA-I lectin was localized in all the bacteria of P. aeruginosa ATCC 33347 as determined by immunofluorescence staining. We investigated the dose-dependent effect of P. aeruginosa PA-I lectin on the growth, the ciliary beating frequency, and the morphology of human respiratory cells in primary culture of nasal polyps collected from non-cystic fibrosis patients. PA-I lectin significantly (P < 0.01) inhibited the growth of respiratory cells at a concentration of > or = 10 micrograms/ml. The percentage of active ciliated cell surface of the cultures decreased significantly (P < 0.05) at a PA-I lectin concentration of 50 micrograms/ml. Exposed to a low concentration of PA-I lectin (10 micrograms/ml), respiratory epithelial cells showed intracytoplasmic vacuoles when examined by light and transmission electron microscopy. At a higher concentration of PA-I lectin (100 micrograms/ml), major cell damage and severe epithelial shedding occurred. These results demonstrate that the P. aeruginosa internal PA-I lectin has a dose-dependent cytotoxic effect on respiratory epithelial cells in vitro. The P. aeruginosa PA-I lectin may represent a virulence factor by contributing to the respiratory epithelial damage during P. aeruginosa respiratory infections.

Protection of human respiratory epithelium from Pseudomonas aeruginosa adherence by phosphatidylglycerol liposomes

The ability of phosphatidylglycerol (DSPG) liposomes to prevent adherence of Pseudomonas aeruginosa to primary cultures of non-cystic fibrosis (CF) and delta F508 homozygous CF human respiratory epithelium was studied. The culture model was characterized by the simultaneous presence of various cellular phenotypes: well-differentiated respiratory epithelial cells, ciliated and nonciliated cells, and migrating cells which can be assimilated into a regenerating epithelium after injury. DSPG liposomes significantly decreased the binding of P. aeruginosa to migrating cells of both non-CF and delta F508 homozygous CF cultures compared with control cultures (35.5 x 10(-3) +/- 8.1 x 10(-3) bacteria per micron 2 versus 23.9 x 10(-3) +/- 2.5 x 10(-3); P < 0.01 for non-CF cultures and 88.8 x 10(-3) +/- 17.2 x 10(-3) bacteria per micron 2 versus 29.1 x 10(-3) +/- 0.6 x 10(-3), P < 0.001 for CF cultures). After treatment with DSPG liposomes, the size of P. aeruginosa aggregates bound to migrating cells in both non-CF cultures and delta F508 homozygous CF cultures was significantly decreased (14.4 +/- 3 bacteria per aggregate versus 11.9 +/- 2.5 bacteria per aggregate [P < 0.05] and 29.9 +/- 8.4 bacteria per aggregate versus 17.3 +/- 2.3 bacteria per aggregate [P < 0.01], respectively). Moreover, the control cultures were characterized by a differential P. aeruginosa adherence according to both the cellular phenotype and the mutation. The migrating cells bound more bacteria than the stationary cells of both non-CF and delta F508 homozygous CF cultures. The CF migrating cells bound significantly more bacteria than the non-CF migrating cells (88.8 x 10(-3) +/- 17.2 x 10(-3) bacteria per microns 2 versus 35.5 x 10(-3) +/- 8.1 x 10(-3) bacteria per micron 2, P < 0.001). These results suggest that DSPG liposomes are able to decrease P. aeruginosa adherence to CF and non-CF respiratory epithelium, particularly to migrating cells, which mimic a regenerating epithelium after injury. DSPG liposomes could also represent a hydrophobic barrier limiting the deleterious action of P. aeruginosa exoproducts.

Nasal epithelial cell culture as a tool in evaluating ciliary dysfunction

Cultures of respiratory epithelial cells were obtained from nasal polyps collected in patients with and without primary ciliary defect. The ciliary beating frequency and the ciliary beating heterogeneity were determined on native and cultured tissues. We observed a significantly higher (p < 0.01) ciliary beating frequency of cultured ciliated cells, when compared with ciliated cells from the native tissue. The ciliary beating frequency of the cultured ciliated cells from the patient with primary defect (7.9 +/- 2.1 Hz) was significantly lower when compared with the beating frequency of the ciliated cells from the control subject (12.4 +/- 2.0 Hz). In addition, the percentage of ciliated cells characterized by a beating frequency lower than 8 Hz was 90.7% in the native tissue and 47.5% in the cultured tissue from the patient with ciliary primary defect. In the patient without ciliary primary defect, 90% of the cultured ciliated cells had a homogeneous ciliary beating, whereas in the patient with primary ciliary defect, only 47% of the ciliated cells had a homogeneous ciliary beating. These results suggest that the culture of respiratory cells associated with the functional activity measurement of the ciliated cells represent another way of precisely determining the extent of the primary ciliary dyskinesia defect.

Studies on human porin. IX. Immunolocalization of porin and CFTR channels in human surface respiratory epithelium

The expression of the voltage-dependent anion channel (VDAC) "Porin 31 HL" and its cellular and subcellular immunocytochemical localization in the human respiratory epithelium were studied with monoclonal and polyclonal antibodies using immunofluorescence and immunogold labelling with light (LM) and transmission electron microscopy (TEM), respectively. Porin was identified in the apical domain of the ciliated cells and in the basal cells of the respiratory epithelium. Immunogold labelling was present in the apical plasma membrane and subapical vesicles of the ciliated cells. In pre-embedded freshly dissociated surface epithelial cells, porin could also be identified with TEM at the outer part of the plasma membrane of basal cells. By LM double immunolabelling, both porin and cystic fibrosis transmembrane conductance regulator (CFTR) were identified in the apical domain of ciliated cells but not in basal cells where CFTR was never identified. On Western blots of solubilized total membrane protein preparations from the same frozen surface epithelial respiratory cells, the antibodies recognized a group of 3 proteins of 31, 60 and 130-140 kDa with a strong reactivity for a 31 kDa protein, corresponding to the porin and a protein of 170 kDa which is consistent with mature CFTR. These results suggest that porin might be part of a multi-component chloride channel complex which could interact with CFTR.

Quantitative analysis and cartography in scanning electron microscopy: application to the study of bacterial adhesion to respiratory epithelium

This paper describes the coupling between a scanning electron microscope (SEM) and an image analysis workstation. The system was designed in order to drive the SEM and to analyse any sample. It allows automatic (edge detection) or semiautomatic (pointing, marking, drawing) object detection. Two types of data can be obtained: (1) topographical information, such as the location of the object within a region of interest drawn at any magnification of the microscope, or (2) quantitative data, such as morphometric characteristics of objects. In addition, high resolution maps of the section, regions of interest, and objects can be obtained with a laser printer. This software was first applied to quantitate the adhesion of the bacteria Pseudomonas aeruginosa to human respiratory epithelial cells in culture. P. aeruginosa was shown associated with ciliated cells. The second application concerned the study of the distribution of specific carbohydrate residues at the surface of the respiratory cells. The gal residues were revealed using the lectin Ricinus communis agglutinin II, adsorbed to colloidal gold particles. A relationship between the presence of adherent bacteria and labelling was shown.

Wound repair of human surface respiratory epithelium

Surface airway epithelium is frequently injured by noxious inhaled agents, epithelial wound repair may be an important process by which the epithelial barrier integrity is maintained. To evaluate the role of surface airway cells in the wound repair process, we developed an in vitro wounding model of human nasal epithelial respiratory cells in primary culture. Circular wounds were made in the epithelial cell culture by detaching, with a glass capillary, approximately 50 cells from the collagen matrix. Video microscopy and electron microscopy observations demonstrated the contribution of two main events during the repair process: the spreading of the cells at the edge of the wounded surface, and the migration of epithelial cell sheets. Complete wound closure occurred within 5 to 8 h. The inhibition of wound repair by cytoskeleton inhibitors or cellular protein synthesis inhibitors suggested that these factors are involved in the wound repair process of surface airway epithelium.