Showing papers on "Respiratory epithelium published in 1994"

CFTR expression and chloride secretion in polarized immortal human bronchial epithelial cells.

Abstract: A major limitation in the study of vectorial ion transport, secretion, and differentiated function in the human airway epithelium has been the lack of suitable cell culture systems. Progress in this direction has been made through the transformation of primary cultured epithelial cells. However, these transformants tend to lose differentiated properties with increasing serial passage, particularly following crisis. The suc­ cessful establishment of a postcrisis SV40 large T-antigen transformed epithelial cell line derived from human bronchial epithelium is described. This cell line, 16HBEI40-, retains differentiated epithelial mor­ phology and functions. Cell cultures show the presence of tight junctions and cilia, and monolayers gener­ ate transepithelial resistance, as measured in Ussing chambers, and retain iJ-adrenergic stimulation of cAMP-dependent chloride ion transport, measured either by ,6CI- efflux or as short-circuit current in Ussing chambers. The cells also increase chloride transport in response to bradykinin or calcium iono­ phore. In addition, 16HBE140-cells express levels of both the cystic fibrosis transmembrane conductance regulator (CFTR) mRNA and protein readily detectable by Northern and Western hybridization analysis, respectively. These cells provide a valuable resource for studying the modulation of CFTR and its role in regulation of chloride ion transport in human airway epithelium as well as other aspects of human airway cell biology. The human airway epithelium is pseudostratified, consisting of highly organized layers of polar cells with specific dif­ ferentiated functions. It includes ciliated columnar cells, basal cells, and secretory goblet cells that are linked by tight junctions. The tight junctions provide a barrier between the airway lumen and the underlying tissues and divide the epi­ thelial cells into apical and basolateral domains. Both of these plasma membrane compartments contain different populations of proteins that allow for directional flux of ions

Administration of an adenovirus containing the human CFTR cDNA to the respiratory tract of individuals with cystic fibrosis.

Abstract: We have administered a recombinant adenovirus vector (AdCFTR) containing the normal human CFTR cDNA to the nasal and bronchial epithelium of four individuals with cystic fibrosis (CF). We show that this vector can express the CFTR cDNA in the CF respiratory epithelium in vivo. With doses up to 2 x 10(9) pfu, there was no recombination/complementation or shedding of the vector or rise of neutralizing antibody titres. At 2 x 10(9) pfu, a transient systemic and pulmonary syndrome was observed, possibly mediated by interleukin-6. Follow-up at 6-12 months demonstrated no long term adverse effects. Thus, it is feasible to use an adenovirus vector to transfer and express the CFTR cDNA in the respiratory epithelium of individuals with CF. Correction of the CF phenotype of the airway epithelium might be achieved with this strategy.

Human airway ion transport. Part one.

Abstract: The proper homeostasis of the liquids that line the surfaces of the lung is vitally important for lung defense. During the past 20 years, data derived primarily from animal studies have indicated that ion transport by the pulmonary epithelium regulates the volume and the composition of these surface liquids. The role of pulmonary epithelial ion-transport systems in this activity can be viewed at two levels: (1) the requirement to regulate surface liquid volumes and composition relevant to the local environment, e.g., adjusting the height and composition of surface liquids to permit efficient function of the mucociliary clearance system in the airways; and (2) the requirement of the pulmonary epithelium to coordinate intrapulmonary surface liquid flow (i.e., so-called «axial» flow) between different pulmonary regions, e.g, alveolar and airway surfaces

Targeted expression of a dominant negative FGF receptor blocks branching morphogenesis and epithelial differentiation of the mouse lung.

Abstract: Mouse lung development begins when two lung buds sprout from the epithelium of the embryonic gut. Patterning of the airways is then accomplished by the outgrowth and repetitive branching of the two lung buds, a process called branching morphogenesis. One of the four fibroblast growth factor (FGF) receptor genes, FGFR2, is expressed in the epithelium of a number of embryonic organs including the lung buds. To block the function of FGFR2 during branching morphogenesis of the lung without affecting its function in other embryonic tissues, the human surfactant protein C promoter was used to target expression of a dominant negative FGFR2 exclusively to lung bud epithelium in transgenic mice. Newborn mice expressing the transgene were completely normal except that instead of normally developed lungs they had two undifferentiated epithelial tubes that extended from the bifurcation of the trachea down to the diaphragm, a defect that resulted in perinatal death. Thus, the dominant negative FGF receptor completely blocked airway branching and epithelial differentiation, without prohibiting outgrowth, establishing a specific role for FGFs in branching morphogenesis of the mammalian lung.

Rapid dendritic cell recruitment is a hallmark of the acute inflammatory response at mucosal surfaces.

Abstract: Immunohistochemical analysis of challenge sites such as skin and the peritoneal cavity has identified neutrophils as virtually the sole cellular participants in acute bacterial inflammation, peak influx occurring 24-48 h in advance of mononuclear cell populations associated with adaptive immunity. This study challenges the general applicability of this paradigm. We demonstrate here that the earliest detectable cellular response after inhalation of Moraxella catarrhalis organisms is the recruitment of putative class II major histocompatibility complex-bearing dendritic cell (DC) precursors into the airway epithelium, the initial wave arriving in advance of the neutrophil influx. Unlike the neutrophils which rapidly transit into the airway lumen, the DC precursors remain within the epithelium during the acute inflammatory response where they differentiate, and develop the dendriform morphology typical of resident DC found in the normal epithelium. During the ensuing 48-h period, these cells then migrate to the regional lymph nodes. No comparable DC response was observed after epidermal or intraperitoneal challenge, and it may be that mucosal surfaces are unique in their requirement for rapid DC responses during acute inflammation. We hypothesize that the role of the DC influx during acute inflammation may be surveillance for opportunistic viruses, and that this covert protective mechanism is operative at a restricted number of mucosal tissue sites.

Cell number and distribution in human and rat airways.

Abstract: Morphometric procedures were used to determine the number of cells, cell volume, cell diameter, and surface areas of the airways in human and rat lungs. Nuclear sizes of epithelial cells from human bronchi were significantly larger than other lung cell nuclei. The average volume of human ciliated cell nuclei was 310 +/- 30 microns 3 and 167 +/- 12 microns 3 in bronchi and bronchioles, respectively. The smaller nuclei of human bronchioles were comparable to those of alveolar cells. In the pseudostratified epithelium of human bronchi, basal cells had a large surface area in contact with the basement membrane (51.3 +/- 4.6 microns 2 per cell) when compared with ciliated (1.1 +/- 0.1 microns 2), goblet (7.6 +/- 1.2 microns 2), or other secretory cells (12.0 +/- 2.1 microns 2). In the first four airway generations distal to the trachea, basal cells account for 30% of the cells in human airway epithelium and 2% of the cells in rat airway epithelium. Total airway surface area from trachea to bronchioles was 2,471 +/- 320 and 27.2 +/- 1.7 cm2 in human and rat lungs, respectively. These direct measurements of airway surface area are less than half of the estimates based on current lung models. The total number of airway epithelial cells were 10.5 x 10(9) for human and 0.05 x 10(9) for rat lungs. For both species, there were 18 times more alveolar cells than bronchial epithelial cells.

Origin and steady-state turnover of class II MHC-bearing dendritic cells in the epithelium of the conducting airways.

Abstract: Recent studies have identified a contiguous network of class II MHC-bearing dendritic cells (DC) in the airway epithelium of several species, including humans. This network seems comparable to the epidermal Langerhans cell population, comprising up to 700 DC per mm2 of airway epithelium. Moreover, it accounts for virtually all local immunostaining for class II MHC, suggesting an important role in surveillance for inhaled Ag. This study examines the turnover of these airway DC using a radiation chimera model that uses congenic rats expressing different allotypic variants of CD45, detectable via mAbs. Steady-state bone marrow renewal of the airway DC population (which is continuously depleted by migration of mature cells to draining lymph nodes) was interrupted via x-irradiation or high-dose dexamethasone, after which the resident population declined by 85% over the ensuing 72 h. After transplantation with congenic bone marrow and an initial lag period for graft establishment, the airway DC population was rapidly restored to preirradiation levels. These findings indicate a half-life of or = 15 days. The only comparable (short) half-life previously reported for a peripheral tissue DC population, is that derived from the gut wall. This indicates that rapidly turning over DC populations are a unique feature of the major "mucosal" organ systems, which is consistent with these DC playing an important role in surveillance of mucosal tissues for incoming Ag.

Interleukin-8, interleukin-6, and soluble tumour necrosis factor receptor type I release from a human pulmonary epithelial cell line (A549) exposed to respiratory syncytial virus

Abstract: The release of interleukin-8 (IL-8), interleukin-6 (IL-6) and the soluble forms of the tumour necrosis factor receptor (sTNF-R) from human pulmonary type II-like epithelial cells (A549) after respiratory syncytial virus (RSV) infection was analysed. RSV infection alone induced a time- and RSV dose-dependent IL-8 and IL-6 release from A549 cells. Furthermore, the soluble form of the TNF-RI was also secreted in a time- and RSV dose-dependent fashion. The soluble TNF-RII was not detected in the cell supernatant of infected epithelial cells. The effect of various cytokines [IL-1 alpha/beta, TNF-alpha/beta, IL-3, IL-6, interferon-gamma (IFN-gamma), transforming growth factor-beta 2 (TGF-beta 2)] and colony-stimulating factors [granulocyte (G)-CSF; granulocyte-macrophage (GM)-CSF] on the IL-8 release from A549 cells was also studied. Our data show that the proinflammatory cytokines IL-1 alpha/beta and TNF-alpha/beta induced an IL-8 release in non-infected A549 cells, and increased the IL-8 release of RSV-infected A549 cells synergistically. In addition, IL-3, G-CSF, IFN-gamma and TGF-beta 2, albeit at high concentrations, induced a low IL-8 release from non-infected A549 cells. The enhanced IL-8 secretion rates were accompanied with elevated cytoplasmic IL-8 mRNA steady state levels, as was shown by Northern blot analysis. Cellular co-culture experiments performed with A549 cells and polymorphonuclear granulocytes or peripheral blood mononuclear cells revealed that increased IL-8 amounts were secreted in the co-culture of non-infected as well as RSV-infected cells. The present study suggests a central role for the airway epithelium during RSV infection with regard to cytokine and cytokine receptor release, resulting in a recruitment and activation of inflammatory and immune effector cells. Our data also suggest that paracrine cytokine networks and cell-cell contact are involved in the regulation of IL-8 secretion within the microenvironment of the bronchial epithelium.

Effects of cigarette smoke on epithelial cells of the respiratory tract.

Abstract: Chronic inhalation of cigarette smoke is associated with mucus hypersecretion, mucus pooling, pulmonary connective tissue damage, and chronic airflow obstruction. Cigarette smoke has therefore been causally linked to the development of chronic obstructive pulmonary disease (either chronic bronchitis or emphysema),' increased airway responsiveness,2 exacerbations of asthma,3 impaired pulmonary immune function,4 and increased pulmonary infections.5 Cigarette smoke has also been established as an important risk factor for lung,6 laryngeal,7 and nasal neoplasia.5 Pathogenetic mechanisms related to smoke-induced respiratory perturbations, however, are not fully understood. One cell type in the lung that may play a major part in the pathogenesis of cigarette smoke-induced lesions is the airway epithelial cell. These cells line the lumen of the airways, and thus are in a unique position to interact directly with inhaled cigarette smoke. Most research involving cigarette smoke and airway epithelial cells has focused on the \"target\" cell responses of these cells in relation to their relatively simple roles in barrier and mucociliary clearance functions. Depending in part on the chronicity of exposure, certain functions may be altered for example, ciliary beating, mucus secretion. It has recently become apparent, however, that airway epithelial cells may also act as \"effector\" cells, playing pivotal roles in regulation of airway reflexes, immunological and inflammatory responses, and maintenance of bronchodilation. As part of their overall response to chronic insult these cells are capable of producing and/or releasing a number of inflammatory mediators, or undergoing alterations in expression of cell adhesion molecules processes that may initiate or perpetuate airway inflammation.9 To date the influence of cigarette smoke on effector functions of epithelial cells has yet to be investigated in detail. Much of the information presented herein is based on acute in vitro cigarette smoke exposures of epithelial cell cultures or airway explants, and on relatively acute human or laboratory animal exposures. Thus, non-neoplastic and non-emphysematous end points of respiratory disease have been emphasised. Nevertheless, early events in the response to cigarette smoke or its components may be critical, and certainly an understanding of these events may help to elucidate the pathogenetic mechanisms of many chronic respiratory diseases. Components of cigarette smoke Chemical analytical studies have identified over 3800 compounds in tobacco smoke.'\" Mainstream cigarette smoke is composed of a complex mixture of gases and condensed tar particles. In experimental studies cigarette smoke is often separated into two phases by a glass fibre filter that retains nearly all particulate matter greater than 01 ptm in diameter. The retained particulate matter is commonly referred to as the \"tar\" phase, while the material passing through the filter is referred to as the \"gas\" phase. Known toxins and carcinogens have been identified in both the gaseous and particulate phases.\" Sidestream smoke (smoke emitted from the burning tip of the cigarette) is the major constituent of environmental tobacco smoke. The chemical composition and gas-toparticle associations of environmental tobacco smoke may be different from that of mainstream smoke, owing to prolonged time and cooling in the air.'2 Sidestream cigarette smoke emissions contain carbon monoxide, ammonia, formaldehyde, benzene, nicotine, acrolein, various gases and particles, and an assortment of potentially genotoxic and/or carcinogenic organic compounds.'3 Increased pulmonary particulate burden due to cigarette smoke may also play a part in respiratory disease.'4 Recent epidemiological findings have indicated adverse effects of particulate air pollutants at concentrations below currently permissible levels.'5 Respirable suspended particles in indoor air in homes may increase from approximately 30 jtg/ m3 to greater than 60 jg/M3 due to accumulation of environmental tobacco smoke.'6 The reported effects of \"cigarette smoke\" may include that of mainstream smoke, variably aged environmental tobacco smoke/sidestream and exhaled smoke, gaseous phase components only, particulate phase components only, or individual chemical compounds such as acrolein,'7 acetaldehyde,'5 or formaldehyde.'9 Some studies have used aqueous extracts of cigarette smoke obtained by bubbling the smoke through a buffer, with or without filtering to remove suspended particulates,20 while other researchers have focused on free radical production arising from chemical reactions within the cigarette smoke.2' Overall, owing to the variability in experimental methodologies (including the type of \"cigarette smoke\") used, interstudy comparisons may be difficult to interpret. It is well to keep this in mind when reading this review. Department of Anatomy, Physiological Sciences, and Radiology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA J A Dye K B Adler

Development of the airway intraepithelial dendritic cell network in the rat from class II major histocompatibility (Ia)-negative precursors: differential regulation of Ia expression at different levels of the respiratory tract.

Abstract: The relative inefficiency of respiratory mucosal immune function during infancy is generally attributed to the immaturity of the neonatal T cell system. However, immune competence in the adult lung has recently been shown to be closely linked to the functional capacity of local networks of intraepithelial dendritic cells (DC). This study examines the density and distribution of these DC throughout the neonatal respiratory tract in rats, focusing particularly on microenvironmental regulation of their class II major histocompatibility complex (MHC) (Ia) expression. In animals housed under dust-controlled conditions, airway epithelial and alveolar Ia+ DC detectable by immunostaining with the monoclonal antibody (mAb) Ox6 are usually not seen until day 2-3 after birth, and adult-equivalent staining patterns are not observed until after weaning. In contrast, the mAb Ox62 detects large numbers of DC in fetal, infant, and adult rat airway epithelium. Costaining of these Ox62+ DC with Ox6 is rare in the neonate and increases progressively throughout infancy, and by weaning Ia+ DC comprised, on average, 65% of the overall intraepithelial DC population. In infant rats, Ia+ DC are observed first at the base of the nasal turbinates, sites of maximum exposure to inhaled particulates, suggesting that their maturation is driven in part by inflammatory stimuli. Consistent with this suggestion, densitometric analysis of Ia staining intensity of individual DC demonstrates that by 2-3 d after birth, Ia expression by nasal epithelial DC was comparable with that of Iahigh epidermal Langerhans cells in adjacent facial skin, at a time when expression by tracheal epithelial DC was 7-10-fold lower. Additionally, the rate of postnatal appearance of Iahigh DC in the airway epithelium was increased by administration of interferon gamma, and decreased by exposure of infant rats to aerosolized steroid. These findings collectively suggest that Ia expression by neonatal respiratory tract DC is locally controlled and can be upregulated by mediators that are produced within the lung and airway epithelium in response to inhalation of proinflammatory stimuli. It was also noted that Ialow neonatal airway DC expressed adult equivalent levels of class I MHC, which suggests differences in capacity to prime for CD8(+)-dependent versus CD4(+)-dependent immunity to inhaled pathogens, during the early postnatal period.

Aerosol and intravenous transfection of human alpha 1-antitrypsin gene to lungs of rabbits.

Abstract: In vivo gene transfer to the lungs is possible either by an intravenous or an airway route of administration. A plasmid containing the recombinant human alpha 1-antitrypsin (h alpha 1AT) gene and a cytomegalovirus promoter complexed to cationic liposomes was given either intravenously or by aerosol to New Zealand White rabbits. Both routes of administration resulted in successful transfection and expression of the h alpha 1AT gene. h alpha 1AT mRNA and protein were detected for at least 7 days. Immunohistochemical staining showed h alpha 1AT protein in the pulmonary endothelium following intravenous administration, in alveolar epithelial cells following aerosol administration, and in the airway epithelium by either route. After intravenous injection of radiolabeled plasmids, autoradiographs showed localization of plasmid in endothelial cells, especially at arterial bifurcations, and at the alveolar level. A plasmid-liposome delivery system for gene therapy to the lungs may permit targeting of the DNA to subsets of lung cells by selection of the route of delivery and may permit a broad application of gene therapy to acute as well as chronic diseases.

Ciliostasis and loss of cilia induced by Mycoplasma hyopneumoniae in porcine tracheal organ cultures.

Abstract: In vivo- and in vitro-grown Mycoplasma hyopneumoniae organisms were inoculated onto newborn piglet tracheal organ cultures to provide a model for interaction of this organism with ciliated respiratory epithelium. Ciliostasis and loss of cilia in tracheal rings were induced by M. hyopneumoniae grown in vivo and with low-passage cultures when grown in vitro. Levels of calmodulin or dehydrogenase enzymes in tracheal ring epithelium were not altered even though ciliostasis and loss of cilia induced by M. hyopneumoniae were extensive. The capacity for inducing epithelial damage diminished with in vitro passage of the organism. Attempts to induce higher-passage cultures to attach to cilia, cause ciliostasis, or cause ciliary damage by supplementation of mycoplasmal medium with porcine lung extract failed. Epithelial damage induced by M. hyopneumoniae in tracheal rings was averted by using porcine immune serum or by separating the organisms from ciliated epithelium with a 0.1-microns-pore-size membrane. Attachment, or at least close association, of M. hyopneumoniae to ciliated epithelium appeared to be necessary to induce ciliostasis and loss of cilia in this model.

An investigation of the role of glutathione in increased epithelial permeability induced by cigarette smoke in vivo and in vitro.

Abstract: Airspace epithelial permeability is known to increase in cigarette smokers. To study the role of the antioxidant reduced glutathione (GSH) in this phenomenon, we used an in vitro model of the epithelial permeability of a monolayer of human type II alveolar epithelial cells (A549 cell line). Both whole (WSC) and vapor (VSC) smoke condensates induced a recoverable, concentration-dependent increase in epithelial permeability to 125iodine-labeled bovine serum albumin (125IBSA), associated with a profound fall in intracellular GSH. Buthionine sulfoximine (BSO), a GSH synthesis inhibitor, decreased GSH levels in A549 epithelial cells, significantly increased A549 epithelial cell permeability, and enhanced both WSC and VSC-induced A549 epithelial cell permeability. Co-culturing epithelial cells and GSH (500 microM) reduced WSC-induced, but not VSC-induced A549 epithelial cell permeability. Increasing intracellular GSH also ameliorated the smoke-induced increased epithelial permeability. Concentrations of cigarette smoke condensate of < 20% increased A549 epithelial cell permeability without associated cell detachment and lysis, which was also the case with BSO-induced increased epithelial permeability. WSC and VSC, instilled intratracheally, significantly increased rat lung epithelial permeability to 125IBSA, 6 h postinstillation, associated with a significant recruitment of neutrophils into the airspaces. This was associated with a small increase in GSH in the lung tissue of VSC-treated rats. However, both WSC and VSC markedly reduced GSH in bronchoalveolar lavage (BAL) fluid. Reduction in lung GSH to 95% but not to 68% of control values by BSO increased lung epithelial permeability in vivo. However, there was no additive effect on epithelial permeability of WSC and BSO.(ABSTRACT TRUNCATED AT 250 WORDS)

Epithelial autotoxicity of nitric oxide: role in the respiratory cytopathology of pertussis

Abstract: Bordetella pertussis releases a specific peptidoglycan fragment known as tracheal cytotoxin (TCT) that reproduces the respiratory epithelial cytopathology of whooping cough (pertussis). In vitro, TCT inhibits DNA synthesis in hamster trachea epithelial cells and causes specific destruction of ciliated cells in explants of human and hamster respiratory epithelium. We have recently demonstrated that TCT triggers production of intracellular interleukin 1 by respiratory epithelial cells, and this cytokine may act as an intermediate signal in the generation of TCT toxicity. Here we report the identification of a subsequent critical step in this pathway: induction of nitric oxide synthesis in the respiratory epithelium. The toxic effects of nitric oxide are consistent with spectroscopic evidence of the formation of iron-dinitrosyl-dithiolate complexes in TCT-treated cells. Aconitase, with its iron-sulfur center, is one expected target of nitric oxide, and TCT inhibited 80% of the activity of this enzyme in respiratory epithelial cells. The deleterious effects of TCT and interleukin 1 were dramatically attenuated by the nitric oxide synthase inhibitors NG-monomethyl-L-arginine and aminoguanidine. These results indicate that nitric oxide mediates the toxicity of TCT for the respiratory epithelium, thus implicating a central role for nitric oxide in the pathogenesis of pertussis.

The specialised structure of crypt epithelium in the human palatine tonsil and its functional significance.

Abstract: Material from 25 human palatine tonsils was studied by light microscopy, immunocytochemistry, scanning and transmission electron microscopy. Special attention was focused on the structure of the epithelium lining the tonsillar crypts in the context of its ascribed immunological functions. This epithelium was not uniform and contained patches of stratified squamous nonkeratinising epithelium and patches of reticulated sponge-like epithelium. The degree of reticulation of the epithelial cells and the infiltration of nonepithelial cells varied. Reticulated patches were associated with disruptions in the continuity of basement membrane, and often also with desquamation of the upper cell layers, and contained numerous small blood vessels. The epithelial cells showed considerable variation in their morphology when surrounded by infiltrating cells. The rearrangement of their cytoskeleton and redistribution of desmosomal contacts indicate the responsiveness and dynamic nature of such epithelium. Cytoplasmic glycogen granules, located in the upper strata, suggest the possibility of energy-demanding functions such as absorption and secretion. The numerous membrane-coating granules may have contributed to cell membrane thickening and possibly also to tonsillar mucosal protection. Some areas contained a few keratohyalin granules but there was little evidence of keratinisation. The presence, and sometimes the predominance, of nonepithelial cells was characteristic of the reticulated epithelium. T and B cells often infiltrated the whole epithelial thickness, and many plasma cells were located around intraepithelial vessels, while macrophages and interdigitating cells showed a patchy distribution. It is proposed that the major functions of the reticulated epithelium are: (1) to provide a favourable environment for the intimate contact between the effector cells of immune responses; (2) to facilitate direct transport of antigens; (3) to synthesise the secretory component continually; and (4) to contain a pool of immunoglobulins. Thus the reticulated epithelium lining the tonsillar crypts represents a specialised compartment, important in the immunological functions of the tonsil as a whole.

Temporal-spatial distribution of SP-B and SP-C proteins and mRNAs in developing respiratory epithelium of human lung

Abstract: We determined the temporal and spatial distribution of surfactant protein B (pro-SP-B) and C (pro-SP-C) mRNAs and proteins by immunohistochemistry and in situ hybridization in fetal, neonatal, and adult human lung. Pro-SP-B and SP-B mRNA were detected in bronchi and bronchioles by 15 weeks' gestation. After 25 weeks, pro-SP-B, active SP-B peptide, and SP-B mRNA were co-localized in bronchiolo-alveolar portal cells and in Type II epithelial cells. In adult lung, pro-SP-B and SP-B mRNA were detected primarily in non-ciliated bronchiolar epithelial cells and in Type II cells in the alveolus. Pro-SP-C and SP-C mRNA were detected in cells lining terminal airways from 15 weeks' gestation and thereafter. After 25 weeks, SP-C mRNA and precursor protein were detected in epithelial cells of the bronchiolo-alveolar portals and in Type II cells, where expression increased with advancing gestational age. Distinct cellular patterns of staining for pro-SP-B compared with SP-B active peptide support the concept that its proteolytic processing or cellular routing may be influenced by cell type and/or cell differentiation. SP-B and SP-C are expressed primarily in distal conducting and terminal airway epithelium of human fetal lung well in advance of surfactant lipid synthesis or physiologic requirements to produce pulmonary surfactant at the time of birth.

Acute responses of non-human primates to airway delivery of an adenovirus vector containing the human cystic fibrosis transmembrane conductance regulator cDNA.

Abstract: Recombinant human adenovirus (Ad) vectors are leading candidates for human gene therapy for cystic fibrosis (CF) based on demonstration of efficient transfer of exogenous genes to rodent respiratory epithelium in vivo and human respiratory cells in vitro. The safety of Ad-mediated gene transfer to the respiratory epithelium and acute (up to 21 days) clinical responses to airway delivery of a replication-deficient recombinant, E1¯, E3¯ Ad type 5-based vector containing the human cystic fibrosis transmembrane conductance regulator cDNA (AdCFTR) were evaluated in rhesus monkeys. Airway delivery of an Ad vector with the lacZ marker gene demonstrated β-galactosidase expression in epithelial cells. Animals administered intratracheal AdCFTR demonstrated human CFTR cDNA expression in airway epithelial cells. Animals administered AdCFTR intranasal, and 24 hr later, intrabronchial [2 × 107 to 5 × 1010 plaque-forming units (pfu), n = 12], in a fashion similar to a proposed human protocol, or only intrabronc...

Expression of transforming growth factor-alpha and epidermal growth factor receptor is increased following bleomycin-induced lung injury in rats.

Abstract: To investigate the potential role of transforming growth factor-alpha (TGF-alpha) and the epidermal growth factor receptor (EGF-R) in the fibroproliferative response to acute lung injury, we determined lung steady-state TGF-alpha and EGF-R mRNA levels, TGF-alpha protein levels, and the distribution of TGF-alpha and EGF-R immunoreactive protein of bleomycin-injured and control rat lungs. At 2 and 4 days after a single intratracheal injection of bleomycin, TGF-alpha mRNA levels increased to 159% and 184% of control values, respectively. EGF-R mRNA levels increased to 163%, 314%, and 170% of control values at 1, 7, and 14 days after bleomycin instillation. TGF-alpha protein levels in whole lung extracts increased to 230% of control values at 4 days after bleomycin administration. TGF-alpha and EGF-R immunoreactivity was detected in macrophages, alveolar septal cells, and airway epithelium of control and bleomycin-injured animals with an apparent increase in the intensity and number of specifically immunostained cells following lung injury. TGF-alpha and EGF-R immunoreactive proteins were detected in foci of cellular proliferation and in areas of intraalveolar fibrosis. We conclude that TGF-alpha and the EGF-R are present in normal and bleomycin-injured rat lung and that the expression of this growth factor and its receptor are up-regulated following lung injury. These results suggest that increased expression of TGF-alpha and the EGF-R may be an important mechanism that modulates the fibroproliferative response to acute lung injury.

Lung Gene Therapy: In Vivo Adenovirus-Mediated Gene Transfer to Rhesus Monkey Airway Epithelium

Abstract: Somatic gene therapy of lung disorders such as cystic fibrosis (CF) aims at introducing the therapeutic gene into respiratory epithelium. We have tested the ability of recombinant human adenovirus to infect rhesus monkey airway epithelium in vivo. Application of adenovirus harboring the lacZ marker gene to the airway surface resulted in large patches of lacZ-positive cells in the trachea, bronchi, and bronchioles, 6 days after virus exposure, indicating a successful transfer of the lacZ gene to respiratory epithelium. Microscopic analysis showed that basal, mucous goblet, and ciliated cells were lacZ positive. In addition, gene transfer to the submucosal glands was observed. Pathological examination of the organs revealed no virus-mediated toxic effects to the lungs and other organs. Using polymerase chain reaction (PCR) analysis we found no spread of the virus to blood or any organ tested. These results indicate the potential use and safety of adenoviruses as a tool in human gene therapy procedu...

Interactions of oxygen radicals with airway epithelium.

Abstract: Reactive oxygen species (ROS) have been implicated in the pathogenesis of numerous disease processes. Epithelial cells lining the respiratory airways are uniquely vulnerable regarding potential for...

Oxidative epithelial damage produces hyperresponsiveness of human peripheral airways.

Abstract: The epithelium probably modulates ahway smooth muscle responsiveness by producing relaxing factors, by inactivating agonists, or by acting as a physical barrier. In isolated airway strips, however, only a limited modulatory role of the epithelium has been found, and this may well be due to shortcomlnqs-ot this airway model. The present study compares the modulatory role of the airway epithelium in human airway tubes and strips. In addition, since oxygen radicals may contribute to epithelial damage in asthma, oxidative damage to the airway epithelium was induced with luminally applied hydrogen peroxide (H20 2) , and changes in responsiveness to the agonists histamine, methacholine, and salbutamol were measured. Toexamine whether intact epithelium acts as a barrier to histamine, the histamine concentration in the organ bath was mea­ sured in tubes with intact and damaged epithelium stimulated from the mucosal side. In airway strips, no differences in responsiveness were found between intact and epithelium-denuded airways for any of the three agonists. In contrast, the sensitivity of airway tubes to both histamine and methacholine was signifi­ cantly lower with mucosal stimulation than with serosal stimulation (-log ECso: 4.87 and 4.92 versus 5.87 and 5.45 for histamine and methacholine, respectively, p < 0.001). N6 difference was found between the sensitivity to salbutamol of mucosally and serosally stimulated airways (-log ECso: 6.19 and 6.20, respec­ tively). The modulation of the sensitivity to contractile agonists by the epithelium increased with increasing airway size, and was abolished after treatment with H20 2 • Light microscopic examination of H20 2-treated airway preparations revealed specific damage to the columnar ciliated epithelial cells, with relative preser­ vation of basal cells. The penetration of histamine through the airway wall was similar in intact and Hi 0 2­ treated airways. These results suggest that oxidative damage to the airway epithelium may lead to hyper­ responsiveness to inhaled stimuli; however, this may not be due to a change in barrier function of the damaged epithelium. Hulsmann AR, Raatgeep HR, den Hollander JC, Stijnen T, Saxena PR, Kerrebijn KF, de Jongste JC. Oxidative epithelial damage produces hyperresponsiveness of human peripheral air­ ways. Am J Respir Crit Care Med 1994; 149:519-25.

Oxidative epithelial damage produces hyperresponsiveness of human peripheral airways

Abstract: The epithelium probably modulates airway smooth muscle responsiveness by producing relaxing factors, by inactivating agonists, or by acting as a physical barrier. In isolated airway strips, however, only a limited modulatory role of the epithelium has been found, and this may well be due to shortcomings of this airway model. The present study compares the modulatory role of the airway epithelium in human airway tubes and strips. In addition, since oxygen radicals may contribute to epithelial damage in asthma, oxidative damage to the airway epithelium was induced with luminally applied hydrogen peroxide (H 2 O 2 ), and changes in responsiveness to the agonists histamine, methacholine, and salbutamol were measured

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

Abstract: 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 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.

Effect of inhaled beclomethasone dipropionate on expression of proinflammatory cytokines and activated eosinophils in the bronchial epithelium of patients with mild asthma

Abstract: Increasing evidence suggests that cytokines play a role in airway inflammation by attracting and activating inflammatory cells. This may lead to epithelial cell damage and airway hyperresponsiveness. Bronchial provocative concentration of histamine causing a 20% fall in forced expiratory volume in 1 second was measured in patients with mild asthma, and bronchial biopsy specimens were stained for granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-8, and activated eosinophils (EG2) in the bronchial epithelium. The effect of inhaled beclomethasone dipropionate was also assessed in a placebo-controlled double-blind manner. There was a correlation between GM-CSF expression and EG2-staining cells (r = 0.484 p < 0.05) in the epithelium. Provocative concentration of histamine causing a 20% fall in forced expiratory volume in 1 second was correlated with GM-CSF expression (r = -0.462, p < 0.05). Treatment with inhaled beclomethasone dipropionate 500 micrograms twice a day led to a significant decrease in both the expression of GM-CSF (p < 0.01) and IL-8 (p < 0.02) and the number of EG2-staining cells (p < 0.01) in the epithelium. The changes in GM-CSF (r = 0.798, p < 0.01) and IL-8 (r = 0.653, p < 0.02) expression were correlated with the changes in EG2-staining cells after treatment. These results suggest that GM-CSF may influence eosinophil activation in the epithelium in vivo and participate in the etiology of bronchial hyperresponsiveness in mild asthma. Also, beclomethasone dipropionate may inhibit eosinophil activation partly by downregulating the expression of GM-CSF and IL-8 in the bronchial epithelium.

Pseudomonas stimulates interleukin-8 mRNA expression selectively in airway epithelium, in gland ducts, and in recruited neutrophils.

Abstract: Neutrophils may play important roles in chronic airway diseases. Pseudomonas is a common pathogen in some chronic airway diseases, and expression of the neutrophil chemoattractant interleukin-8 (IL-8) is induced by Pseudomonas in various cells in vitro. Here we examine the localization of IL-8 mRNA expression after incubating human and dog bronchi with Pseudomonas supernatant in vitro. To examine IL-8 expression in recruited neutrophils, we also superfused the dog bypassed tracheal segment with Pseudomonas supernatant in vivo and measured neutrophil number and IL-8 concentration in luminal fluid; simultaneously, we introduced Pseudomonas supernatant by catheter in a peripheral airway. After 6 h, we analyzed IL-8 mRNA expression and localization in removed tissue. Unincubated bronchi showed no IL-8 mRNA expression, but incubation with Pseudomonas supernatant in vitro resulted in IL-8 mRNA expression in surface epithelial, gland duct, and a subpopulation of serous gland cells. In vivo, introduction of Pseudomonas supernatant into dog trachea and peripheral airways caused IL-8 mRNA expression in epithelial and gland duct cells but also in the recruited neutrophils. Pseudomonas lipopolysaccharide alone was without effect in vitro and in vivo. We conclude that Pseudomonas products, but not lipopolysaccharide, stimulate IL-8 expression in airways and that this expression occurs primarily in surface epithelial and gland duct cells, thus bringing the chemoattractant to the bacterial site. Furthermore, IL-8 expression in recruited neutrophils provides a potential mechanism for positive feedback of this protective antibacterial response.

Tumor necrosis factor-induced interleukin-8 expression in cultured human airway epithelial cells

Abstract: The effects of tumor necrosis factor-alpha (TNF-alpha) on interleukin-8 (IL-8) expression and generation were examined in primary cultured human airway epithelial cells (HAEC) and a human lung epithelial cell line (A549). TNF-alpha increased IL-8 mRNA and protein expression in HAEC in a concentration- and time-dependent manner and these effects were inhibited by dexamethasone (1 microM). There was no change in the stability of IL-8 mRNA, and a nuclear run-on assay confirmed that TNF-alpha increased IL-8 gene transcription. TNF-alpha-induced IL-8 mRNA expression showed a biphasic response in HAEC, with an early increase at 2 h followed by a sustained increase from 8 h, which was abolished by the addition of cycloheximide, suggesting that the synthesis of another protein was involved. A549 cells also increased IL-8 secretion and mRNA after incubation of TNF-alpha, with inhibition by dexamethasone. However, A549 cells showed only an early single peak. A549 cells showed a 250-fold increase in the generation of IL-8 immunoreactivity, whereas primary cultured HAEC showed only a threefold increase, suggesting that HAEC and A549 cells may respond to TNF-alpha in different ways. The sustained increase in IL-8 secretion due to an increase in gene transcription in response to TNF-alpha may be an important amplification step in inflammatory diseases of the airways.

Proinflammatory potential of the airway epithelium in bronchial asthma

Abstract: Histopathological studies of asthmatic airways removed postmortem or by bronchial biopsy show marked inflammatory changes, notably epithelial cell disruption and damage, and the presence of large numbers of eosinophils. The epithelial damage is seen in mild, asymptomatic asthmatics as well as in patients who have died in status asthmaticus. Damage to the epithelium may also correlate with bronchial hyperreactivity. The epithelium has been suggested to be a target for inflammatory cell mediators and cytokines. Recently, the airway epithelium has itself been shown to produce and release several proinflammatory mediators and cytokines, and to express adhesion molecules for inflammatory cells. The epithelium, thus, may actively participate in the inflammatory changes in asthma, where it may be a source as well as a target. Drug therapy aimed at preventing inflammatory changes in the epithelium, such as cytokine and adhesion molecule expression, may be an important step forward in halting disease progression in asthma.

Expression of phenotypic markers during regeneration of rat tracheal epithelium following mechanical injury.

Abstract: We examined epithelial regeneration in mechanically injured rat trachea using phenotypic markers that identify unique differentiated stages of epithelial cells. Following a focal denuding wound, the cells from the adjacent nonwounded epithelium flattened and migrated into the wounded site during the first 12 h. At 24 h, these cells dedifferentiated into poorly differentiated (PD) cells that did not precisely resemble any of the mature tracheal cells. Proliferation of PD cells produced a multilayered epithelium by 48 h. Mitotic activity, measured as mitotic rate (MR) following a 6-h colchicine metaphase blockade, was high at 24 h (MR 23.4%) and 48 h (MR 24.0%). These PD cells expressed keratin 14 and Griffonia simplicifolia I-isolectin B4 (GSI-B4) lectin binding sites, which are specific for basal cells in normal epithelium but did not react with secretory or ciliated cell markers. At 72 h, MR fell to 1.8% (control MR 0.38%). The wound was covered with a pseudostratified epithelium; secretory cell markers ...