Contribution of plasma-derived molecules to mucosal immune defence, disease and repair in the airways

This review discusses recent observations, in health and disease, on the release and distribution of plasma-derived molecules in the airway mucosa. Briefly, the new data on airway mucosal exudation mechanisms suggest that the protein systems of plasma contribute significantly to the mucosal biology, not only in injured airways but also in such mildly inflamed airways that lack oedema and exhibit no sign of epithelial derangement. Plasma as a source of pluripotent growth factor, adhesive, leucocyte-activating, etc., molecules may deserve a prominent position in schemes that claim to illustrate immunological and inflammatory mechanisms of the airway mucosa in vivo.     

Conserved domains in DNA repair proteins and evolution of repair systems

A detailed analysis of protein domains involved in DNA repair was performed by comparing the sequences of the repair proteins from two well-studied model organisms, the bacterium Escherichia coli and yeast Saccharomyces cerevisiae, to the entire sets of protein sequences encoded in completely sequenced genomes of bacteria, archaea and eukaryotes. Previously uncharacterized conserved domains involved in repair were identified, namely four families of nucleases and a family of eukaryotic repair proteins related to the proliferating cell nuclear antigen. In addition, a number of previously undetected occurrences of known conserved domains were detected; for example, a modified helix-hairpin-helix nucleic acid-binding domain in archaeal and eukaryotic RecA homologs. There is a limited repertoire of conserved domains, primarily ATPases and nucleases, nucleic acid-binding domains and adaptor (protein-protein interaction) domains that comprise the repair machinery in all cells, but very few of the repair proteins are represented by orthologs with conserved domain architecture across the three superkingdoms of life. Both the external environment of an organism and the internal environment of the cell, such as the chromatin superstructure in eukaryotes, seem to have a profound effect on the layout of the repair systems. Another factor that apparently has made a major contribution to the composition of the repair machinery is horizontal gene transfer, particularly the invasion of eukaryotic genomes by organellar genes, but also a number of likely transfer events between bacteria and archaea. Several additional general trends in the evolution of repair proteins were noticed; in particular, multiple, independent fusions of helicase and nuclease domains, and independent inactivation of enzymatic domains that apparently retain adaptor or regulatory functions.     

Responses of rat nasal epithelium to short- and long-term exposures of ozone: image analysis of epithelial injury, adaptation and repair

This article reviews the use of computerized image analysis and standard morphologic techniques to characterize the responses of nasal epithelium in laboratory rats to single or repeated exposures to a common urban air-pollutant, ozone. Alterations in the number and composition of the epithelial cell populations after either short- or long-term exposures are described. The principal nasal epithelial alteration induced by repeated exposures to this irritating, oxidant pollutant is mucous cell metaplasia (i.e., transformation of airway epithelium, normally devoid of mucous cells, to a secretory epithelium containing numerous mucus-secreting cells). This metaplastic change, induced by acute or chronic ozone exposures, has been morphometrically examined at various times post-exposure. In this article, we describe our current understanding of the pathogenesis and persistence of ozone-induced mucous cell metaplasia in nasal epithelium based on the results of these morphometric studies.     

Pediatric airway in health and disease

The most common cause of pediatric anesthetic morbidity is the failure to adequately oxygenate. Problems with pediatric airways are the major cause of this inability to provide adequate oxygenation. Problems with pediatric airways and the diseases that affect them require not only knowledge about their pathophysiology but also considerable hands-on experience and respect for the complications that subsequently occur. It is hoped that by sharing knowledge and experiences, pediatricians can improve the care all of us strive to give our young patients.     

Recognition of normal, neoplastic, and fetal airway epithelial cell membranes by two monoclonal antibodies

The reactivity of two rat monoclonal antibodies was studied. These antibodies, A2R and A2C, bind a 32 kDa alveolar type II cell membrane receptor for surfactant protein A. A2R and A2C also bind apical cell membranes of ciliated and nonciliated cells of the conducting airways. Because this reactivity suggested possible utility in targeting those cells for therapeutic gene transfer, the binding activity of these two antibodies was examined in human tissues. In conducting airways, A2R and A2C bound apical epithelial cell membranes throughout the embryologic period studied: from 15 weeks of gestation, through maturity. Reactivity was more restricted to ciliated cells of the airways as maturation progressed. In the peripheral lung, A2C and A2R only bound most cells in the early developing lung, but mainly type II cells in mature lungs. Other normal tissues recognized by these antibodies included crypt lining cells of the adult and fetal stomach, large bile duct epithelium, and pancreatic acinar cells. All of these cells derive from embryonic foregut endoderm. Other normal tissues, both of endodermal and nonendodermal origin, were negative. Pulmonary carcinomas were studied. A2C and A2R recognized all non-small cell carcinomas of the lung tested. In contrast, none of the small cell carcinomas or carcinoid tumors of the lung were recognized by these antibodies. The function of p32 in these diverse cell types is not clear, but whatever its role in these tissues, antibodies versus p32 may potentially be used to target gene or drug therapy to the normal or malignant cells they recognize.     

Distribution of epidermal growth factor receptor and ligands during bronchiolar epithelial repair from naphthalene-induced Clara cell injury in the mouse

Clara cells are primary targets for metabolically activated pulmonary toxicants because they contain an abundance of the cytochrome P450 monooxygenases required for generation of toxic metabolites. The factors that regulate bronchiolar regeneration after Clara cell injury are not known. Previous studies of naphthalene-induced bronchiolar injury and repair in the mouse have shown that epithelial cell proliferation is maximal 1 to 2 days after injury and complete 4 days after injury. Proliferation is followed by epithelial re-differentiation (4 to 14 days). In this study, mice were treated with the environmental pollutant naphthalene to induce massive Clara cell injury. The distribution and abundance of three growth-regulatory peptides (epidermal growth factor receptor (EGFR), epidermal growth factor (EGF), and transforming growth factor (TGF)-alpha) was determined immunochemically during repair of this acute bronchiolar injury. EGFR and its ligands were detected at low levels in cells throughout the lung including peribronchiolar interstitial cells, blood vessels, and conducting airway epithelium. Immediately after naphthalene injury (1 to 2 days), EGFR, EGF, and TGF-alpha are expressed in increased abundance in squamous epithelial cells of the injury target zone, distal bronchioles. These immunopositive squamous cells are detected in clumps in the distal bronchioles at the time when cell proliferation is maximal. EGFR protein expression is decreased slightly 4 to 7 days after injury and continues to decrease below control levels of abundance 14 to 21 days after injury. This down-regulation of EGFR is not reflected in a corresponding decrease in EGF and TGF-alpha protein expression, indicating that control of cell proliferation is regulated at the receptor level. Co-localization of EGFR and bromodeoxyuridine-positive proliferating cells in the same bronchiole indicates that EGFR is up-regulated within the proliferative microenvironment as well as in specific proliferating cells within the injury target zone. The coincident localization within terminal bronchioles of EGFR, EGF, and TGF-alpha to groups of squamous epithelial cells 2 days after naphthalene injury suggests that these peptides are important in up-regulating cell proliferation after Clara cell injury in the mouse.     

Gastroesophageal reflux and airway disease

Gastroesophageal reflux may cause a variety of airway diseases such as asthma, aspiration pneumonia, chronic bronchitis, posterior laryngitis, and ulceration or polyp formation on the vocal cords. Among these asthma seems most common and important clinically. Reflux not only may trigger and aggravate an episode of airway obstruction but also may contribute to nocturnal symptoms. Both clinical and experimental observations suggest that the pathogenetic mechanism may be a vagal reflux following stimulation of lower esophageal receptors and/or microaspiration of gastric acid into the trachea. Diagnosis is usually based on clinical history of asthma and symptoms of gastroesophageal reflux, but in some cases, diagnostic tests such as 24-hour esophageal pH monitoring may be necessary. General measures to avoid reflux and an H2-receptor antagonist together with supportive gastric medications may be the standard treatment. If symptoms persist, proton pump inhibitor may be helpful. Antireflux surgery may provide long-term improvements. Although surgical treatment is indicated only in patients with intractable esophagitis at present, it may be used more commonly through a laparoscopic approach in the near future.     

Identification and function of cyclic nucleotide phosphodiesterase isoenzymes in airway epithelial cells

Epithelial cells actively participate in inflammatory airway disease by liberating mediators such as arachidonate metabolites and cytokines. Inhibition of phosphodiesterases (PDEs) may be a useful anti-inflammatory approach. The PDE isoenzyme pattern and the effects of PDE inhibition on mediator generation were analyzed in primary cultures of human and porcine airway epithelial cells (AEC) and in the bronchial epithelial cell line BEAS-2B. PDE4 and PDE5 were detected in lysates of all cell types studied. In primary cultures of human AEC, the PDE4 variants PDE4A5, PDE4C1, PDE4D2, and PDE4D3 were identified by polymerase chain reaction analysis. Evidence of the recently described PDE7 was obtained by rolipram- insensitive cyclic adenosine monophosphate (cAMP) degradation, and its presence was verified by the demonstration of PDE7 messenger RNA. Primary cultures of human airway epithelium also expressed PDE1. Enhanced epithelial cAMP levels, induced by forskolin and PDE4 inhibition, increased formation of prostaglandin E2 (PGE2), but not of interleukin (IL)-8 or 15-hydroxyeicosatetraenoic acid (15-HETE) in airway epithelial cells. Increased cyclic guanosine monophosphate levels in these cells provoked by sodium nitroprusside and the PDE5 inhibitor zaprinast reduced the PGE2 synthesis, whereas 15-HETE and IL-8 formation were unchanged. The data suggest that PDE isoenzymes are important in airway inflammation and that PDE inhibitors exert anti-inflammatory effects by acting on AEC.     

Receptor-mediated gene transfer to airway epithelial cells in primary culture

The reproducibility of tooth tapping frequencies was measured in young and elderly dentate subjects. Six rates of tapping, i.e. 40, 60, 90, 120, 160 and 200 times per min, were practised to the accompaniment of a metronome for 15 s before recording. After a 15-s break, subjects were asked to reproduce the same rate of tapping without metronome accompaniment, and these movements were recorded. It was determined that the young subjects regulated tooth tapping frequencies by controlling velocity of mandibular movement. On the other hand, the elderly subjects regulated tooth tapping frequency by controlling opening width.     

Sorting of two polytopic proteins, the gamma-aminobutyric acid and betaine transporters, in polarized epithelial cells

The gamma-aminobutyric acid transporter (GAT-1) isoform of the gamma-aminobutyric acid and the betaine (BGT) transporters exhibit distinct apical and basolateral distributions when introduced into Madin-Darby canine kidney cells (Pietrini, G., Suh, Y. J., Edelman, L., Rudnick, G., and Caplan, M. J. (1994) J. Biol. Chem. 269, 4668-4674). We have investigated the presence of sorting signals in their COOH-terminal cytosolic domains by expression in Madin-Darby canine kidney cells of mutated and chimeric transporters. Whereas truncated GAT-1 (DeltaC-GAT) maintained the original functional activity and apical localization, either the removal (DeltaC-myc BGT) or the substitution (BGS chimera) of the cytosolic tail of BGT generated proteins that accumulated in the endoplasmic reticulum. Moreover, we have found that the cytosolic tail of BGT redirected apical proteins, the polytopic GAT-1 (GBS chimera) and the monotopic human nerve growth factor receptor, to the basolateral surface. These results suggest the presence of basolateral sorting information in the cytosolic tail of BGT. We have further shown that information necessary for the exit of BGT from the endoplasmic reticulum and for the basolateral localization of the GBS chimera is contained in a short segment, rich in basic residues, within the cytosolic tail of BGT.     

Tendon injury repair in a war wound

During 18 months of the 1991-1992 war against Croatia, 4425 injured were treated at the Department of Surgery, Osijek University Hospital. Among them 46 had tendon injuries, 20 with tendon laceration and 26 with total rupture. In 12 wounded primary repair was performed, 4 of an extensor tendon, 7 of a flexor tendon and 1 of both flexor and extensor. Four patients with primary flexor tendon repair had a good functional result. In other 34 no primary repair was done. Good function was achieved in 18 cases.     

Scavenger receptor family proteins: roles for atherosclerosis, host defence and disorders of the central nervous system

In this review, we summarize the structure and function of the scavenger receptor family of proteins including class A (type I and II macrophage scavenger receptors, MARCO), class B (CD36, scavenger receptor class BI), mucinlike (CD68/macrosialin, dSR-CI) and endothelial (LOX-1) receptors. Two motifs have been identified as ligand-binding domains: a charged collagen structure of type I and II receptors, and an immunodominant domain of CD36. These structures can recognize a wide range of negatively charged macromolecules, including oxidized low-density lipoproteins, damaged or apoptotic cells, and pathogenic microorganisms. After binding, these ligands can be either internalized by endocytosis or phagocytosis, or remain at the cell surface and mediate adhesion or lipid transfer through caveolae. Under physiological conditions, scavenger receptors serve to scavenge or clean up cellular debris and other related materials, and they play a role in host defence. In pathological states, they mediate the recruitment, activation and transformation of macrophages and other cells which may be related to the development of atherosclerosis and to disorders caused by the accumulation of denatured materials, such as Alzheimer's disease.     

Tracheobronchial epithelial multinucleation, viral inclusion bodies and malignant disease

A national anti-echinococcosis campaign was started in 1971, in which education of the public, the control of dogs and the control of slaughter were emphasised. The campaign has already achieved almost total elimination of infection in food animals born subsequent to its initiation. Stray dogs are rare and all others are registered and examined three or four times a year. Infection in dogs has decreased by over 80 per cent (from 6-8 in 1972 to 1-1 in 1976). Legislation governing abattoir functioning and dog control is in force. Violation of legislation is penalised, although the level of awareness of the problem by the public, who co-operate willingly, does not often warrant this.     

Surface proteins of normal and transformed epithelial liver cells

Surface protein patterns of 12 various tumorigenic and non-tumorigenic liver epithelial cell lines (IAR series) were studied by means of lactoperoxidase catalyzed iodination followed by the gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis. These patterns were found to be very similar except a protein with an apparent mol. wt. about 150 kilodaltons which appeared in cells of tumors derived from in vitro transformed epithelial liver cells. Surface fibronectin was present in all the three non-tumorigenic lines, and in 7 of 9 tumorigenic cell lines examined. The indirect immunofluorescence revealed that in non-tumorigenic lines this protein was localized predominantly in the regions of cell-to-cell contacts, while in tumorigenic cells fibronectin often formed fibrillar networks similar to those of fibroblasts.     

Sorting and trafficking of ion transport proteins in polarized epithelial cells

We reported a rare case who had hypoxic-encephalopathy causing frontal apraxia of gait. The patient, a 34-year-old female, was admitted in July, 1994, complaining of difficulty in walking after anoxic brain damage caused by ventricular arrhythmia. She had difficulty in raising her feet, which appeared to be rooted to the floor. There was no evidence of motor paralysis, spasticity, rigidity or sensory loss, but she did show frontal lobe signs such as foot grasp reflex and Gegenhalten. Cranial MRI showed slight atrophy of the frontal lobe. On T2 weighted image, high-intensity areas were detected at the posterior internal capsule and corona radiata. Single photon emission CT (123I-IMP) demonstrated a low perfusion area which included the inferomedical part of the frontal lobe. After 8 months of hospitalization, her postural instability and unsteady gait slowly improved without treatment as frontal signs such as foot grasp reflex disappeared. We speculate that her apraxia of gait may result from grasp reflex and Gegenhalten.     

Elevated levels of cytokeratin 19 in the bronchoalveolar lavage fluid of patients with chronic airway inflammatory diseases--a specific marker for bronchial epithelial injury

Cytokeratin 19 (CK19) is a specific cytoskeletal structure of simple epithelia, including bronchial epithelial cells (BEC). Since CK19 is released from injured bronchial epithelium, we investigated the levels of CK19 fragments in the bronchoalveolar lavage fluid (BALF) of eight patients with chronic airway inflammatory diseases (CAID) using an enzyme-linked immunosorbent assay (ELISA). Included in our test group were four cases of chronic bronchitis, three cases of bronchiectasis, and one case of diffuse panbronchiolitis. There were also 15 control subjects (five asymptomatic smokers and 10 nonsmokers). BALF from the nonsmokers as well as from the asymptomatic smokers contained few CK19 fragments (0.2 +/- 0.2 and 1.9 +/- 0.8 pg/ml, respectively). In contrast, significantly high levels of CK19 were present in the BALF of patients with CAID (21.7 +/- 5.7 pg/ml; p < 0.01 versus nonsmoking controls). In addition, CK19 fragment concentrations in BALF correlated significantly with the number of neutrophils (r = 0.722, p < 0.01) but not with the numbers of macrophages or lymphocytes in BALF. BALF from patients with CAID contained high levels of neutrophil elastase (NE) activity, suggesting that NE might be an important stimulus for the release of CK19 from BEC. To prove this, we incubated BET-1A cells, a human immortalized bronchial epithelial cell line, both in the absence and the presence of inflammatory mediators (including NE, tumor necrosis factor-alpha [TNF-alpha], and hydrogen peroxide). We then measured the concentration of CK19 fragments in the culture supernatants with ELISA. BET-1A cells released CK19 fragments into their culture supernatants after treatment with NE but not after treatment with TNF or hydrogen peroxide. Further, we demonstrated that CK19 cleaved by NE could not be detected by ELISA. Our results suggest that CK19 measurement in BALF is useful for assessing the presence of bronchial epithelial injuries.     

Analysis of DNA mismatch repair proteins in human medulloblastoma

During replication, the primary function of the eukaryotic DNA mismatch repair (MMR) system is to recognize and correct mismatched base pairs within the DNA helix. Deficiencies in MMR have been reported previously in cases of hereditary nonpolyposis colorectal cancer and sporadic tumors occurring in a variety of tissues including gliomas. Furthermore, recent evidence indicates that the MMR system may be involved in mediating therapeutic sensitivity to alkylating agents. In this study, 22 neoplastic tissue samples from 22 patients who underwent surgical resection for medulloblastoma, a common cerebellar tumor of childhood, were assayed for the presence or absence of MMR polypeptides using Western blot and immunohistochemical techniques. Results from these experiments indicate that the MMR system is not commonly deficient in medulloblastoma.