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Showing papers on "Respiratory epithelium published in 1992"



Journal ArticleDOI
TL;DR: Direct evidence is provided of an increased expression of granulocyte-macrophage-colony-stimulating factor, interleukin-6, and interleUKin-8 genes and proteins in bronchial epithelium from patients with symptomatic asthma.
Abstract: We have previously demonstrated that cultured human bronchial epithelial cells produce cytokines with potent proinflammatory properties on exposure to several stimuli in vitro, and we have hypothesized that these epithelial cell-derived factors may contribute to the pathogenesis of some inflammatory diseases of the bronchial mucosa, particularly asthma, by promoting the infiltration of granulocytes and T cells and their local activation. We provide, in this study, direct evidence of an increased expression of granulocyte-macrophage-colony-stimulating factor, interleukin-6, and interleukin-8 genes and proteins in bronchial epithelium from patients with symptomatic asthma. The up regulation of the production of these cytokines in bronchial epithelial cells of patients with asthma could be abolished in vitro by corticosteroids (hydrocortisone, 10 −7 mol/L), but the up regulation also spontaneously disappeared during a period of 6 days after the removal of the cells from the diseased tissue.

409 citations


Journal ArticleDOI
TL;DR: The finding that increased Mn-SOD in distal respiratory epithelial cells confers protection from oxygen injury provides a basis for novel therapies to protect lung from injury during oxygen therapy of acute and chronic lung diseases.

307 citations


Journal Article
TL;DR: The sites of cytotoxicity within the respiratory tract (nasal cavity and tracheobronchial airway tree) resulting from administration of naphthalene, an organic chemical whose cytotoxic properties require metabolic activation via the cytochrome P-450 monooxygenase system were defined.
Abstract: The purpose of this study was to define the sites of cytotoxicity within the respiratory tract (nasal cavity and tracheobronchial airway tree) resulting from administration of naphthalene, an organic chemical whose cytotoxic properties require metabolic activation via the cytochrome P-450 monooxygenase system. Three species were compared: mouse, hamster and rat. Naphthalene was administered in corn oil at these doses: mouse (0-400 mg/kg), hamster (0-800 mg/kg) and rat (0-1600 mg/kg), and the animals were sacrificed 24 hr later. In mice, naphthalene produced Clara cell cytotoxicity at 50 mg/kg. The primary alteration was swelling and vacuolation of Clara cells in terminal bronchioles. At 100 mg/kg, the number of terminal bronchioles with vacuolated Clara cells and the number of Clara cells within terminal bronchioles which showed vacuolation increased. At 200 and 300 mg/kg, almost all of the nonciliated cells lining terminal bronchioles in mice were exfoliated and necrotic. In contrast, there was no apparent effect on Clara cells or ciliated cells of terminal bronchioles in rats treated with up to 1600 mg/kg. At 800 mg/kg, minor alterations in Clara cells in some terminal bronchioles were observed in hamsters. At 300 mg/kg, lobar bronchus and trachea showed swelling 'and vacuolation of nonciliated cells in mice, but no detectable change at 200 mg/kg or below. The trachea and lobar bronchus were unaffected in rats, but showed cytotoxic changes in hamsters. In the nasal cavity of mice, cytotoxicity was observed only in the olfactory epithelium and only in animals treated with 400 mg/kg. There were minimal alterations in the respiratory epithelium. The only epithelial population showing cytotoxicity in the rat was the olfactory epithelium. Complete necrosis was observed at 200 mg/kg and higher. In the hamster there was no discernible alteration in the olfactory epithelium at 100 and 200 mg/kg. At 400 mg/kg, the olfactory epithelium was necrotic. Naphthalene injury to the tracheobronchial epithelium of the mouse is: 1) Clara cell specific; 2) dose-related in the terminal bronchiole; and 3) involves more proximal airways in a dose-dependent fashion. The tracheobronchial epithelium of the rat is refractory to Clara cell injury even at the LD50, but proximal airways are more susceptible than distal airways in the hamster. The nasal cavity shows specific injury in one zone (olfactory epithelium) in a dose and species specific manner. The susceptibility to naphthalene-induced injury in the olfactory epithelium does not correlate with the susceptibility of Clara cells in more distal portions of the respiratory tract.(ABSTRACT TRUNCATED AT 400 WORDS)

183 citations


Journal ArticleDOI
TL;DR: A significant negative correlation was noted between the age of the subject and the probability of obtaining olfactory epithelium, supporting the idea that the olf factory mucosa is gradually replaced by respiratory epithelio with aging.
Abstract: Thirty-six mucosal specimens were obtained with a biopsy instrument from the upper nasal septum of 12 human autopsy cases before the en bloc removal of the entire olfactory area. Examination of these 36 specimens with transmission electron microscopy demonstrated olfactory epithelium in only 17. A significant negative correlation (r = -.728) was noted between the age of the subject and the probability of obtaining olfactory epithelium, supporting the idea that the olfactory mucosa is gradually replaced by respiratory epithelium with aging. Using the en bloc specimens, the distribution of olfactory epithelium was reconstructed from light microscopic examination of silver-stained sections. Multiple patches of respiratory epithelium were observed over the upper portion of the nasal septum and superior turbinates, ie, the presumptive olfactory area. On transmission electron microscopic examination, frequent respiratory metaplasia was also suggested. Within the area of respiratory metaplasia, supporting cell-like and microvillar cell-like structures often were found; these structures may be remnants of olfactory epithelium. The sampling of olfactory tissue with a biopsy procedure is hampered by the irregular and patchy distribution of olfactory epithelium. The invasion of respiratory epithelial patches into the olfactory mucosa seems to be characteristic of the human olfactory epithelium and may increase as a function of age. Thus, conclusions about the structure of the olfactory mucosa in an individual patient must be based on several tissue samples.

167 citations


Journal ArticleDOI
01 Jul 1992-Thorax
TL;DR: It is proposed that shedding of epithelial cells occurs along a suprabasal plane and that there is a potential plane of cleavage between the suprapasal and the basal cell layers, which might be more vulnerable to the various insults.
Abstract: BACKGROUND: Attention has recently been focused on the basal cells of the tracheobronchial epithelium as the mechanism of anchorage of the tall columnar cells, which themselves do not appear to form hemidesmosomes with the basement membrane of the epithelium. Residual basal cells have been described as remaining attached to the basement membrane after epithelial denudation. This led this group to formulate the hypothesis that there may be a potential plane of cleavage between the basal cells and the overlying columnar cell layer within the bronchial epithelium, which becomes disrupted in asthma. METHODS: Bronchoalveolar lavage samples were obtained during bronchoscopy from eight patients with atopic asthma and four normal controls. Ultrathin sections of lavage cell pellets were examined by electron microscopy and the number of columnar and basal cells found in each epithelial cell cluster was counted. Cytocentrifuge preparations of the lavage samples from the same subjects were also examined for free epithelial cells and epithelial cell clusters. RESULTS: Electron microscopic examination of the cell pellets showed that basal cells were present in very small numbers in the epithelial clusters in all subjects (mean 0.03 (SE 0.02)/cluster) and the ratio of columnar cells to basal cells was far greater than was encountered in the intact bronchial epithelium (167 nu 4). The cytocentrifuge preparations showed an increased number of epithelial cell clusters and epithelial cells in the asthmatic patients. Although these clusters were similar in size in the two groups of subjects (6.3 nu 5.1 cells/cluster) the ratio of free epithelial cells to cells within the cluster was higher in the non-asthmatic subjects. CONCLUSIONS: It is proposed that shedding of epithelial cells occurs along a suprabasal plane and that there is a potential plane of cleavage between the suprabasal and the basal cell layers, which might be more vulnerable to the various insults.

149 citations


Journal ArticleDOI
TL;DR: To evaluate the factors controlling migration of leukocytes into pulmonary airway epithelium, the biochemical mechanisms responsible for the regulation of intercellular adhesion molecule-1 (ICAM-1) expression on cultured monolayers of human tracheal epithelial cells (HTECs) or SV40 virus-transformed human bronchial epithelial Cells (BEAS-2B).
Abstract: To evaluate the factors controlling migration of leukocytes into pulmonary airway epithelium, we determined the biochemical mechanisms responsible for the regulation of intercellular adhesion molecule-1 (ICAM-1) expression on cultured monolayers of human tracheal epithelial cells (HTECs) or SV40 virus-transformed human bronchial epithelial cells (BEAS-2B). Validation experiments with human umbilical vein endothelial cells (HUVECs) demonstrated little detectable ICAM-1 expression on unstimulated cells or on cells incubated with interferon-gamma (IFN-gamma), but HUVEC monolayers responded to interleukin-1 beta (IL-1 beta) or tumor necrosis factor-alpha (TNF-alpha) with significant increases in ICAM-1 and ICAM-1-dependent adherence of polymorphonuclear leukocytes (PMNs). HTEC monolayers also exhibited no significant basal ICAM-1 expression but, in contrast to HUVEC monolayers, had marked increases in ICAM-1 expression and ICAM-1-dependent PMN adherence only after incubation with IFN-gamma (and not after IL-1 beta or TNF-alpha) treatment. BEAS-2B cells also exhibited relatively selective IFN-gamma stimulation of ICAM-1 expression and ICAM-1-dependent PMN adherence but (like late passage HTEC) showed significant basal ICAM-1 expression. Differences in IFN-gamma effect on ICAM-1 levels between HUVEC and HTEC monolayers were not due to differences in number or responsiveness of IFN-gamma receptors, because both cell types exhibited a similar number of receptors and other IFN-gamma-dependent responses of HUVECs remained active. In all analyses, ICAM-1 mRNA levels correlated closely with detection of ICAM-1 on the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

148 citations


Journal Article
TL;DR: A pivotal role of P-glycoprotein in physiology of various organs already in early phases of human development is suggested and may help to identify its physiologic substrates.
Abstract: P-glycoprotein, a transmembrane protein associated with multidrug resistance in cancer cells, is also expressed in normal tissues. To get more insight into the physiologic role of mdr1/P-glycoprotein, we investigated its expression in human fetal tissues after 7 to 38 weeks of gestation by an immunohistochemical technique, using three different monoclonal antibodies, and by a sensitive RNAse protection assay. Expression of mdr1-mRNA could already be demonstrated in the embryonal phase of human development, after 7 weeks of gestation. Comparing the adult with the fetal tissue distribution, differences were found in specific organs, such as adrenal, intestine, respiratory epithelium, and brain capillaries. In the fetal zone cells of the fetal adrenal cortex no staining was observed by immunohistochemistry, whereas the definitive zone showed increasing expression throughout gestation. Prenatal intestine did not show staining of the epithelium, although definite mdr1-mRNA expression was observed in late specimens. Interestingly, respiratory epithelium of main bronchi and pharynx, not expressing P-gp in adults, did stain positive. Expression of P-gp in brain capillaries was not observed before the third trimester of pregnancy, whereas in kidney and liver, mdr1-mRNA expression and staining for P-glycoprotein were detected in early fetal life (11 to 14 weeks). These findings suggest a pivotal role of P-glycoprotein in physiology of various organs already in early phases of human development and may help to identify its physiologic substrates.

138 citations


Journal ArticleDOI
TL;DR: Investigation of the effects of extracellular ATP on the Cl- secretory process in human normal and CF nasal epithelial cultures with double-barreled Cl- selective microelectrodes concludes that luminally applied ATP is an effective Cl-secretagogue that activates the apical membrane Cl- conductance of normal andCF nasal epithelia to an equivalent level.
Abstract: Chloride secretion across cystic fibrosis (CF) airway epithelia is effectively regulated by pathways associated with intracellular Ca2+ metabolism, but not by mechanisms dependent on protein kinase A or C. In a search for therapeutically useful agonists, we investigated the effects of extracellular ATP on the Cl- secretory process in human normal and CF nasal epithelial cultures with double-barreled Cl- selective microelectrodes. When applied to the basolateral membrane of normal, but not CF, nasal epithelium, extracellular ATP (10(-4) M) stimulated a small increase in Cl- secretion that was primarily associated with a hyperpolarizing conductance in the basolateral membrane. In contrast, ATP applied to the apical (luminal) membrane of either normal or CF nasal epithelium stimulated a greater increase in Cl- secretion that was associated with activation of an apical membrane Cl- conductance. The increases in Cl- current and apical conductance were greater in CF tissues and attained maximal values similar to normal nasal epithelium. We conclude 1) that basolateral application of ATP indirectly induces Cl- secretion by activating a basolateral (K+) conductance and is an effective secretagogue only in normal nasal epithelium and 2) that luminally applied ATP is an effective Cl- secretagogue that activates the apical membrane Cl- conductance of normal and CF nasal epithelia to an equivalent level.

136 citations


Journal ArticleDOI
TL;DR: The ultrastructure of guinea pig tracheal epithelium exposed to 10 micrograms of rhamnolipid in vivo was normal, and Mono- and dirhamnlipid had equivalent effects.
Abstract: Pseudomonas aeruginosa rhamnolipid causes ciliostasis and cell membrane damage to rabbit tissue, is a secretagogue in cats, and inhibits epithelial ion transport in sheep tissue. It could therefore perturb mucociliary clearance. We have investigated the effect of rhamnolipid on mucociliary transport in the anesthetized guinea pig and guinea pig and human respiratory epithelium in vitro. Application of rhamnolipid to the guinea pig tracheal mucosa reduced tracheal mucus velocity (TMV) in vivo in a dose-dependent manner: a 10-microgram bolus caused cessation of TMV without recovery; a 5-micrograms bolus reduced TMV over a period of 2 h by 22.6% (P = 0.037); a 2.5-microgram bolus caused no overall changes in TMV. The ultrastructure of guinea pig tracheal epithelium exposed to 10 micrograms of rhamnolipid in vivo was normal. Application of 1,000 micrograms/ml rhamnolipid had no effect on the ciliary beat frequency (CBF) of guinea pig tracheal rings in vitro after 30 min, but 250 micrograms/ml stopped ciliary beating after 3 h. Treatment with 100 micrograms/ml rhamnolipid caused immediate slowing of the CBF (P less than 0.01) of human nasal brushings (n = 7), which was maintained for 4 h. Mono- and dirhamnolipid had equivalent effects. The CBF of human nasal turbinate organ culture was also slowed by 100 micrograms/ml rhamnolipid, but only after 4 h (CBF test, 9.87 +/- 0.41 Hz; control, 11.48 +/- 0.27 Hz; P less than 0.05, n = 6), and there was subsequent recovery by 14 h.(ABSTRACT TRUNCATED AT 250 WORDS)

135 citations


Journal ArticleDOI
TL;DR: Findings are consistent with the concept that the CFTR delta Phe 508 mutation modifies the intracellular maturation and trafficking of the protein, leading to an altered subcellular distribution of the delta P he 508 mutant CFTR.
Abstract: Deletion of the amino acid residue Phe 508 of the cystic fibrosis transmembrane conductance regulator (CFTR) protein represents the most common mutation identified in cystic fibrosis (CF) patients. A monoclonal and a polyclonal antibody directed against different regions of CFTR were used to localize the CFTR protein in normal and CF airway epithelium derived from polyps of non-CF and CF subjects homozygous for the ΔPhe 508 CFTR mutation. To identify the cellular and subcellular localization of CFTR, immunofluorescent light microscopy, confocal scanning microscopy, and immunogold transmission electron microscopy were performed on cryofixed tissue. A markedly different subcellular distribution was identified between normal and CF airway epithelial cells. In normal epithelium, labeling was restricted to the surface apical compartment of the ciliated cells. In contrast, in the epithelium from homozygous ΔPhe 508 CF patients, CFTR markedly accumulated in the cytosol of all the epithelial cells. These findings...

Journal ArticleDOI
TL;DR: Induction or interleukin‐8 gene expression in virus‐infected airway epithelium may be an important early step lending to virus‐induced airway inflammation.

Journal ArticleDOI
TL;DR: With the exception of the airway epithelium, there was a good correlation between the distribution of mRNAs by in situ hybridization and the distributionof receptor subtypes by autoradiographic mapping.
Abstract: m2 mRNA in airway smooth muscle; m3 mRNA in airway epithelium, airway smooth muscle, and submucosal glands. No detection of m4 and m5 mRNAs was observed in any cellular structures. The presence of various muscarinic receptor subtype mRNAs was confirmed by Northern blot analysis. Only human lung mRNA hybridized to the m1 probe giving a single 3.2 kb transcript. mRNA from the human cultured airway smooth muscle cells gave m2 and m3 hybridization bands of about 6.0 kb and 4.5 kb, respectively, while mRNA from the cultured airway epithelial cells gave only m3 hybridization band of 4.5 kb. With the exception of the airway epithelium, there was a good correlation between the distribution of mRNAs by in situ hybridization and the distribution of receptor subtypes by autoradiographic mapping. These results may have an important clinical implication, and also give rise to further investigation of gene regulation of pulmonary muscarinic receptor subtypes in health and disease.

Journal ArticleDOI
TL;DR: In this article, the authors examined the feasibility of delivering DNA to respiratory epithelial cells by the receptor-mediated endocytosis pathway and showed that effective gene transfer requires both the DNA-binding moiety and cognate moiety for the cell surface receptor.
Abstract: Gene-based therapies for a variety of inherited and acquired pulmonary diseases will require the development of vectors capable of safe and efficient transfer of DNA to the respiratory epithelium. The present study examined the feasibility of delivering DNA to respiratory epithelial cells by the receptor-mediated endocytosis pathway. This strategy employs molecular conjugates consisting of a cognate moiety, in this case human transferrin, covalently linked to a DNA-binding moiety, such as a cationic polyamine. Complexes were formed between transferrin-polylysine conjugates (hTfpL) and plasmid DNA carrying the firefly luciferase reporter gene (pRSVL). The conjugate-DNA complexes were added directly to cells in tissue culture and incubated for 24 h, after which cell lysates were analyzed for luciferase enzyme activity by luminometry. An immortalized human respiratory epithelial cell line (HBE1) treated with the transferrin-polylysine-DNA complexes exhibited luciferase enzyme activity significantly augmented over background levels. This respiratory epithelial cell line exhibited greater susceptibility to gene transfer by the transferrin-polylysine conjugates than did non-respiratory epithelial cell lines known to possess high levels of transferrin receptors. Effective gene transfer was shown to require both the DNA-binding moiety and cognate moiety for the cell surface receptor. Specific internalization of the conjugates by the transferrin pathway was verified by competition for the transferrin receptor. In addition, treatment with agents that either increased transferrin receptor number or decreased lysosomal degradation markedly augmented gene expression mediated by the conjugates. Thus, respiratory epithelial cells possess receptors for transferrin that can be exploited to accomplish gene transfer by the receptor-mediated endocytosis pathway.

Journal ArticleDOI
01 Jun 1992-Chest
TL;DR: Fibronectin, a dimeric cell-adhesive extracellular matrix glycoprotein, is secreted by mesenchymal cells and assembled into insoluble matrices which have important biological functions in embryologic development as well as in tissue response to injury.

Journal Article
TL;DR: The results indicate that erythromycin may selectively inhibit Cl secretion across airway epithelium through the inhibition of prostaglandin synthesis and suggest that this action possibly reflects its clinical efficacy in the treatment of airway hypersecretion.
Abstract: We studied the effect of the macrolide antibiotic erythromycin on bioelectrical properties of canine cultured tracheal epithelium under short-circuit conditions in vitro. Addition of erythromycin to the submucosal but not to the mucosal side dose-dependently decreased short-circuit current (Isc), the maximal decrease from the baseline value and the concentration required to produce a half-maximal effect (IC50) being 5.6 +/- 1.0 microA.cm-2 (mean +/- SE, p less than 0.001) and 18 microM, respectively. In contrast, other antibiotics including ampicillin, cephazolin and tetracycline were without effect. The erythromycin-induced decrease in Isc was not altered by amiloride, but it was abolished by bumetanide, diphenylamine-2-carboxylate2, and substitution of Cl in the bathing medium with gluconate (p less than 0.001, in each case). The effect of erythromycin on epithelial Isc was attenuated by pretreatment of cells with indomethacin but not with AA-861 a lipoxygenase inhibitor. Incubation of cells with erythromycin inhibited the release of prostaglandins E2 and F2 alpha from tracheal epithelial cells. These results indicate that erythromycin may selectively inhibit Cl secretion across airway epithelium through the inhibition of prostaglandin synthesis and suggest that this action possibly reflects its clinical efficacy in the treatment of airway hypersecretion.

Journal Article
TL;DR: Repeat airway instillations of endotoxin induce an increase in the amount of intraepithelial mucosubstances, secretory cell hyperplasia, and excess luminal mucus in pulmonary airways, indicating that endotoxin released from gram-negative bacteria may be partially responsible for the structural alterations, in the airway surface epithelium.
Abstract: Bacteria-induced bronchopneumonias are often characterized by an influx of neutrophils and excess mucus in pulmonary airways This study determined how endotoxin, a component of gram-negative bacteria and a potent inflammatory agent, affects the ultrastructure of the mucociliary apparatus and the amount of stored intraepithelial mucosubstances in the main axial airways within the lung Rats were intranasally instilled, once a day for 3 days, with endotoxin or saline (controls) Animals were sacrificed 1, 2, or 7 days after the last instillation Microdissected intrapulmonary axial airways (generations 8-11) from the right caudal lobes of infusion-fixed lungs were processed for light and electron microscopy Morphometric techniques were used to determine the volume densities (Vs) of histochemically stained intraepithelial mucosubstances and numerical densities of airway epithelial cells There were marked increases, compared with controls, in the amount of intraepithelial mucosubstances in the intrapulmonary axial airways at generations 8 and 11 in the right caudal lobes from endotoxin-instilled rats sacrificed 1, 2, and 7 days after the last instillation There were significantly greater numbers of surface epithelial cells per length of basal lamina (ie, hyperplasia) in endotoxin-exposed airways compared with airways from controls This endotoxin-induced hyperplasia was due primarily to an increase in the number of mucus-secretory cells, which in endotoxin-exposed epithelium were columnar and contained numerous, large confluent, electronlucent, secretory granules composed of acidic and neutral glycoproteins In contrast, secretory cells in airway epithelium from controls were cuboidal and contained small discrete, electron-dense, granules composed of only neutral glycoproteins The numbers of ciliated cells and basal cells were similar in both control and endotoxin-exposed epithelium Only endotoxin-exposed epithelium, however, contained atypical epithelial cells with numerous basal bodies, few cilia, and few apical secretory granules These results indicate that repeated airway instillations of endotoxin induce an increase in the amount of intraepithelial mucosubstances, secretory cell hyperplasia, and excess luminal mucus in pulmonary airways Therefore, endotoxin released from gram-negative bacteria may be partially responsible for the structural alterations, in the airway surface epithelium, which result in the excess luminal mucus observed in bacteria-induced bronchopneumonias

Journal Article
TL;DR: The variability of response by species, airway and epithelial cell type to cytochrome P-450-mediated pulmonary toxicants and the need for precise quantitative methods of defining both cytotoxic and metabolic events are emphasized.

Journal ArticleDOI
TL;DR: This study demonstrates the induction of c-fos in epithelial cells of asthmatics, suggesting a role for this proto-oncogene in activation rather than in proliferation.
Abstract: c-fos, a proto-oncogene regulating the transcription of many genes, plays a critical role in the cell cycle and differentiation and may be involved in the regulation of inflammation in asthma. Very low levels of c-fos are detectable in most human cells, and its expression is rapidly and transiently increased by multiple factors, some of which are involved in the airways inflammation of asthma (histamine, eicosanoids, and cytokines). The presence of c-fos protein, as detected by immunofluorescence, and the immunoreactivity of PCNA, a cell proliferation marker, were examined in bronchial biopsies obtained from 12 asthmatics and 10 normal subjects. Biopsies of eight of 12 asthmatics expressed c-fos versus none of 10 normal subjects. The expression was heterogeneous and localized to cells positive for anti-cytokeratin monoclonal antibody, indicating their epithelial origin. On the other hand, PCNA immunoreactivity was only observed in one asthmatic and one control subject but it was not related with c-fos expression. This study demonstrates the induction of c-fos in epithelial cells of asthmatics, suggesting a role for this proto-oncogene in activation rather than in proliferation.

Journal ArticleDOI
TL;DR: The properties of the PAO1 neuraminidase were examined to determine its potential role in facilitating Pseudomonas colonization of the respiratory epithelium and under the hyperosmolar conditions postulated to exist in the CF lung, nanA is likely to be expressed to facilitate the initial adherence of Pseudomanas to the respiratory tract.
Abstract: The pathogenesis of Pseudomonas aeruginosa infection in cystic fibrosis (CF) is a complex process attributed to specific characteristics of both the host and the infecting organism. In this study, the properties of the PAO1 neuraminidase were examined to determine its potential role in facilitating Pseudomonas colonization of the respiratory epithelium. The PAO1 neuraminidase was 1000-fold more active than the Clostridium perfringens enzyme in releasing sialic acid from respiratory epithelial cells. This effect correlated with increased adherence of PAO1 to epithelial cells after exposure to PAO1 neuraminidase and was consistent with in vitro studies demonstrating Pseudomonas adherence to asialoganglioside receptors. The regulation of the neuraminidase gene nanA was examined in Pseudomonas and as cloned and expressed in Escherichia coli. In hyperosmolar conditions neuraminidase expression was increased by 50% (P less than 0.0004), an effect which was OmpR dependent in E. coli. In Pseudomonas the osmotic regulation of neuraminidase production was dependent upon algR1 and algR2, genes involved in the transcriptional activation of algD, which is responsible for the mucoid phenotype of Pseudomonas and pathognomonic for chronic infection in CF. Under the hyperosmolar conditions postulated to exist in the CF lung, nanA is likely to be expressed to facilitate the initial adherence of Pseudomonas to the respiratory tract.

Journal Article
TL;DR: The alteration of secretory cell number and chemical composition of their secretions during the second trimester of foetal life is similar to that which occurs in chronic bronchitis in the adult, however, in hypersecretory disease the extent and site of the major change appear to be inappropriate to the defence of the lung.
Abstract: The combined secretions of distinct secretory cells of the airway lining mucosa serve to keep the inspired air moist and free of potentially harmful dust particles, organisms and adsorbed gases. Apart from their role in protecting the respiratory zone of the lung, mucus-secreting cells act as pluripotential stem cells during foetal development and, in the adult, following mucosal injury. The variety of secretory cells include the mucous and serous cells of the surface and glandular epithelium, the non-ciliated bronchiolar (Clara) cell and the less frequent dense-core granulated (neuroendocrine) cell. The last-mentioned is the first type to differentiate at about 10 weeks of gestation; mucus-secreting cells are present from the 13th week of gestation, when mature ciliated cells are already present, and Clara cells begin to mature during the 19th week of human development. The alteration of secretory cell number and chemical composition of their secretions during the second trimester of foetal life is similar to that which occurs in chronic bronchitis in the adult. However, in hypersecretory disease the extent and site of the major change appear to be inappropriate to the defence of the lung.

Journal ArticleDOI
TL;DR: The specific BLP receptor antagonist, [Leu13-psi(CH2NH)Leu14]bombesin abolishes these effects on fetal lung growth, suggesting that CD10/NEP modulates BLP-mediated proliferation.
Abstract: The cell membrane-associated enzyme CD10/neutral endopeptidase 24.11 (CD10/NEP) functions in multiple organ systems to downregulate responses to peptide hormones. Recently, CD10/NEP was found to hydrolyze bombesin-like peptides (BLP), which are mitogens for normal bronchial epithelial cells and small cell lung carcinomas. Growth of BLP-responsive small cell lung carcinomas was potentiated by CD10/NEP inhibition, implicating CD10/NEP in regulation of BLP-mediated tumor growth. BLP are also likely to participate in normal lung development because high BLP levels are found in fetal lung, and bombesin induces proliferation and maturation of human fetal lung in organ cultures and murine fetal lung in utero. To explore potential roles for CD10/NEP in regulating peptide-mediated human fetal lung development, we have characterized temporal and cellular patterns of CD10/NEP expression and effects of CD10/NEP inhibition in organ cultures. Peak CD10/NEP transcript levels are identified at 11-13 wk gestation by Northern blots and localized to epithelial cells and mesenchyme of developing airways by in situ hybridization. CD10/NEP immunostaining is most intense in undifferentiated airway epithelium. In human fetal lung organ cultures, inhibition of CD10/NEP with either phosphoramidon or SCH32615 increases thymidine incorporation by 166-182% (P < 0.025). The specific BLP receptor antagonist, [Leu13-psi(CH2NH)Leu14]bombesin abolishes these effects on fetal lung growth, suggesting that CD10/NEP modulates BLP-mediated proliferation. CD10/NEP expression in the growing front of airway epithelium and the effects of CD10/NEP inhibitors in lung explants implicate the enzyme in the regulation of peptide-mediated fetal lung growth.

Journal ArticleDOI
TL;DR: In the developing lung, bFGF seems to be sequestered and stored in the extracellular matrix, and may be released at times of need, and FGF-R up- and down-regulation offers another mechanism by which the growth of specific cell populations may be controlled during fetal lung development.
Abstract: To study the role of basic fibroblast growth factor (bFGF) in fetal lung development, the distribution of bFGF peptide and FGF receptor (FGF-R) was examined by immunohistochemistry in embryonic and fetal rat lung [d 12 to term (term = 22 d)). Throughout development bFGF was localized to airway epithelial cells, their basement membranes, and their extracellular matrix. FGF-R was also detected in airway epithelial cells, especially in the branching areas, and in interstitial cells as early as d 13. The number of FGF-R immunoreactive cells increased during the embryonic and pseudoglandular stages of lung development, followed by fluctuations in reactivity during the canalicular stage. No FGF-R was detected in tissue from the saccular stage of lung development. The presence of bFGF and FGF-R in developing airway epithelium and mesenchyme is compatible with a role for this growth factor during fetal lung development. In the developing lung, bFGF seems to be sequestered and stored in the extracellular matrix, and may be released at times of need. Furthermore, FGF-R up- and down-regulation offers another mechanism by which the growth of specific cell populations may be controlled during fetal lung development.

Journal ArticleDOI
TL;DR: The results suggest that active TGF-beta produced by airway epithelial cells may function in an autocrine or paracrine manner to modulate epithelial cell behavior.
Abstract: The ability of airway epithelial cells to produce transforming growth factor-beta (TGF-beta) may be an important mechanism for the control of growth, differentiation, and repair of the airway epithelium. To determine whether airway epithelial cells are capable of producing TGF-beta, we examined primary cultures of bovine bronchial epithelial cells. Using a bioassay, TGF-beta activity was detected readily in media conditioned by bovine bronchial epithelial cells. Neutralizing antisera to TGF-beta 1 and TGF-beta 2 were used to demonstrate that the majority of the activity was of the TGF-beta 2 isoform. Interestingly, some of the TGF-beta activity was present in the conditioned media as "active" TGF-beta, not requiring acid activation. The production of TGF-beta was variable, depending on cell density and the presence of retinoic acid. The presence of endogenously produced active TGF-beta in the culture media was shown to modulate the behavior of the cell cultures as evidenced by the effects of TGF-beta-neutralizing antisera on cell size and fibronectin production. Our results suggest that active TGF-beta produced by airway epithelial cells may function in an autocrine or paracrine manner to modulate epithelial cell behavior.

Journal ArticleDOI
TL;DR: The observations made in the present study are compatible with the hypothesis that colloid cysts of the third ventricle originate from the endoderm, most likely the respiratory epithelium.
Abstract: The histogenesis of colloid cyst of the third ventricle remains unsettled. Ultrastructural and immunohistochemical analyses have suggested the following possible origins: (a) neuroepithelium, including paraphysis, ependyma, choroid plexus and tela chorioidea; and (b) endoderm, including respiratory and enteric epithelium. This report describes the ultrastructural features of the lining epithelium in four cases of colloid cyst. Six distinct cell types were recognized: (1) ciliated cells with occasional abnormal cilia; (2) non-ciliated cells with microvilli coated with granulofibrillary material; (3) goblet cells showing discharge of secretory granules; (4) basal cells with prominent tonofilaments and desmosomes; (5) basal-located cells with elongated electron-lucent cytoplasm and scattered membrane-bound dense-core granules (150–350 nm); and (6) small undifferentiated cells with scanty organelles. Junctional complexes were present in the former four cell types but absent in the latter two. The types of epithelial cells and their topographic distribution within the epithelium are both very similar to those of normal respiratory epithelium and to the lining epithelium of intraspinal bronchogenic cyst. The observations made in the present study are compatible with the hypothesis that colloid cysts of the third ventricle originate from the endoderm, most likely the respiratory epithelium.

Journal ArticleDOI
TL;DR: Chronic exposure to low levels of O3 causes epithelial inflammation and interstitial fibrosis in the proximal alveolar region and bronchiolar epithelial cell injury, and chronic exposure resulted in structural changes, suggesting injury to both ciliated and Clara cells.

Journal ArticleDOI
TL;DR: In bronchioles, hyperpolarization by luminal Cl(-)-free solution was inversely related to fractional inhibition of PD with amiloride but directly related to lumen diameter, which suggests that porcine tracheas, bronchi, and bron chioles actively absorb Na+, and secretion of Cl- may occur in all airway regions except small bronchiola.
Abstract: Ion transport properties of pulmonary small airway epithelia are poorly understood. To characterize these properties, airways were excised from anesthetized pigs. Transepithelial potential differen...

Journal ArticleDOI
TL;DR: It is apparent that the effects of viral respiratory infections on the development of airway hyperresponsiveness are multiple and interrelated and involved the production of viral specific IgE, upregulation of leukocyte inflammatory activity, enhancement of the factors involved in the generation of late phase allergic responses, altered beta-adrenergic and cholinergic nervous system activity, and damage to the airway epithelium.

Journal ArticleDOI
TL;DR: Fimbriation of H. influenzae increased buccal cell adherence but did not facilitate association with normal or damaged respiratory epithelium or increase epithelial damage, indicating that adhesins other than fimbriae are present.
Abstract: One nontypeable laboratory strain and five nontypeable clinical isolates of Haemophilus influenzae from sputum were investigated. Bacteria replicated from 10(4) to 10(8) cfu/ml over 24 h in an organ culture of human respiratory mucosa with only the intact mucosal surface exposed. By transmission electron microscopy, bacteria were not seen in association with normal respiratory epithelium, even after incubation for 24 h. H. influenzae infection caused patchy and occasionally confluent damage to epithelium, and the bacteria associated only with structurally damaged cells. Scanning electron microscopy revealed increased mucus, and slowed ciliary beat frequency was measured by photometry. Fimbriation of H. influenzae increased buccal cell adherence but did not facilitate association with normal or damaged respiratory epithelium or increase epithelial damage, indicating that adhesins other than fimbriae are present. Interactions with mucus, cilia, and epithelium are likely to be important in the pathogenesis of H. influenzae respiratory infections.

Journal ArticleDOI
TL;DR: CCSP-human growth hormone transgenic mice provide a model to dissect the developmental mechanisms regulating gene expression during pulmonary epithelial cell growth and differentiation and exhibit an unusual phenotype of growth retardation and delayed hair appearance, suggesting a unique effect of human growth hormone on normal intrauterine development.
Abstract: Clara cell secretory protein (CCSP) is an abundant 10-kDa protein synthesized and secreted by nonciliated epithelial cells lining the respiratory and terminal bronchioles of the lung. CCSP gene expression is an informative developmental marker within the bronchiolar epithelium recapitulating cellular differentiation in the distal respiratory epithelium during late fetal and early postnatal life. To define the mechanisms that establish and maintain gene expression within this epithelium, CCSP-human growth hormone chimeric gene constructs were created and used to generate transgenic mice. RNA blot analysis of organs from F1 transgenic offspring and normal littermates revealed that cis-acting elements within 2.25 kilobases of the 5' flanking region of the CCSP gene were sufficient to direct lung-specific expression of human growth hormone. In situ hybridization and immunohistochemistry of individual bronchioles revealed that human growth hormone expression in the respiratory epithelium of these mice was confined to Clara cells, consistent with observations of the endogenous CCSP gene. Unexpectedly, founder animals and F1 transgenic offspring exhibited an unusual phenotype of growth retardation and delayed hair appearance, suggesting a unique effect of human growth hormone on normal intrauterine development. CCSP-human growth hormone transgenic mice provide a model to dissect the developmental mechanisms regulating gene expression during pulmonary epithelial cell growth and differentiation. Definition of the cis-acting elements determining such cell-specific expression will be of value in strategies for the somatic gene therapy of human pulmonary disease.