Neutral and acidic human tracheobronchial mucin. Isolation and characterization of core protein.

Human bronchial mucin from a patient suffering from chronic bronchitis was solubilized in aqueous solution containing sodium azide and protease inhibitors and purified by Sepharose 4B and 2B column chromatography. The mucin was further purified by cesium bromide density gradient centrifugation. Sodium dodecyl sulfate-polyacrylamide gel (7.5%) electrophoresis of this material showed high-molecular-weight mucin component(s) at the top of the gel. Chemical analysis of this preparation indicated a typical mucin profile of amino acids and carbohydrates. Ion-exchange chromatography resulted in resolution of the purified mucin into neutral and acidic fractions. Comparison of the chemical composition of these two fractions showed higher mole percentage of threonine, serine, sialic acid, and sulfate in the acidic fraction. Chemical deglycosylation of the purified mucin preparation with trifluoromethane sulfonic acid was carried out at 20 degrees C for 3 1/2 h. Sialic acid, fucose, galactose, and N-acetylglucosamine were completely removed, whereas traces of N-acetylgalactosamine were still detected. High-pressure liquid chromatography of the deglycosylated products from native, neutral, and acidic mucin preparations resulted in a principal peptide, P1, with identical amino acid composition. Cyanogen bromide (CNBr) treatment of the peptide P1 from neutral and acidic mucins and subsequent fractionation of the fragments by high-pressure liquid chromatography resulted in similar peptide profiles. The P1 peptide fraction was further subjected to high-pressure liquid chromatography in a second solvent system, which resulted in two peaks, P1a and P1b. Gel filtration of both peptides in 6 M guanidine hydrochloride indicated a single peak with molecular weight of approximately 97 kDa. The amino acid profile of the two peptides was dominated by high levels of threonine, serine, and proline, which combined accounted for nearly 39% of the total residues, and in most respects, the profile resembled that of native mucin. End-group analysis of the peptide P1a indicated a blocked N-terminus, whereas serine was found to be the N-terminal amino acid in the peptide P1b. Rabbit antibodies prepared against the peptide P1 from native tracheal mucin reacted strongly with neutral and acidic mucin as well as the mucin from human colon. Both neutral and acidic human tracheal mucins were immunologically reactive with mouse monoclonal antibody HMPFG-2, which was prepared against human mammary mucin. However, the response of this antibody to human colonic mucin was rather weak.

Evidence of hydrophobic domains in human respiratory mucins. Effect of sodium chloride on hydrophobic binding properties.

Hydrophobic binding properties of purified human respiratory mucins were studied by the fluorescence probe technique using mansylphenylalanine (Mns-Phe) as the fluorescent probe. Mucins were purified from tracheobronchial secretions of cystic fibrosis (CF) and asthmatic patients, as well as from individuals with normal lungs, according to a protocol earlier established in our laboratory. Purified mucins were subjected to reduction-alkylation and Pronase digestion to study the effects of these treatments on the hydrophobic properties of the mucins. In addition, the effects of increased NaCl concentration on the hydrophobic properties of native and reduced-alkylated mucins were also investigated. Native mucins showed evidence of a large number of low-affinity (KD approximately 10(-5) M) binding sites for the hydrophobic ligand Mns-Phe and had between 40 and 50 binding sites/mg of mucin. Reduction of mucin using dithiothreitol in the presence of 6 M guanidine hydrochloride and subsequent alkylation with iodoacetamide apparently caused marked conformational changes in the mucin molecules as revealed by the presence of both high-affinity (KD approximately 10(-6) M) and low-affinity (KD approximately 10(-5) M) binding sites for the probe and an increase in the number of probe binding sites. Pronase digestion of the native and reduced-alkylated mucins almost completely eliminated binding of the fluorescent probe to the mucins, showing that the binding sites are on the nonglycosylated, Pronase-sensitive portion of the mucin molecules. Increasing NaCl concentrations (0.03-1.0 M) did not appreciably alter the native mucin-induced Mns-Phe fluorescence, while that of the reduced-alkylated mucin-induced Mns-Phe fluorescence was progressively increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Concentrations of cefixime in bronchial mucosa and sputum after three oral multiple dose regimens.

In a study of 58 patients the concentrations of cefixime, a new oral cephem antibiotic, in bronchial mucosa were 35-40% of the concentrations found in simultaneously collected serum samples. The antibiotic was often undetectable in sputum despite a highly sensitive assay.

[Degree of mineralization of pulmonary, tracheal and bronchial tissues in healthy persons of different age]. / Stepen' mineralizatsii tkanei legkikh, trakhei i bronkhov u zdorovykh liudei raznogo vozrasta.

In persons died an accidental or sudden death tissues of the lungs, bronchi of various caliber and trachea have been investigated by means of light microscopy and infrared (IR) spectroscopy. The IR spectra of the bronchial and tracheal tissue are identical and differ from the IR spectra of the pulmonary tissues. The mineralization degree (ratio of inorganic to organic components of the tissue) of the pulmonary tissue increases with age, in bronchi and trachea this dependence is expressed not so distinctly. The absolute mineralization degree in the bronchial tissue is 1.3-1.8 times higher than in the lungs. A suggestion is made that mineralization level of the tissue increases with aggravation of sclerosis processes.

Distribution of substance P receptors in rabbit airways, functional and autoradiographic studies.

We have studied systematically the distribution of receptors for substance P in the airway smooth muscle of the rabbit using both functional studies and light-microscopic autoradiography. Four areas of the respiratory tract were examined: the midtrachea (T1) and proximal, middle and distal portions of the right main bronchus (B1, B2 and B3, respectively). The magnitude of the contractile response to substance P in preparations from six to eight animals was location-dependent, increasing significantly from proximal to distal areas. Maximal tension expressed as a function of tissue weight +/- S.E.M. was 24.8 +/- 3 for T1, 39 +/- 10 for B1, 108 +/- 31 for B2 and 160 +/- 42 for B3. The potency of substance P in B2 and B3 was significantly greater (EC50 = 4.8 x 10(-7) M; 2.8 x 10(-7) M, respectively) than that in T1 (2.5 x 10(-6) M). After inhibition of endogenous enkephalinase by phosphoramidon there was an increase in sensitivity to substance P in both T1 (EC50 = 2.3 x 10(-7) M, n = 5) and B3 (2.6 x 10(-9) M, n = 5). There was remarkable agreement in the results obtained with autoradiography. No binding sites (0) were visualized to Bolton Hunter substance P in T1. Sparse but specific binding (+) was seen in B1, whereas it was marked ( ) in B2 and very dense ( ++) in B3. Thus, our results have shown that receptors for substance P are more numerous in the distal than proximal airways of the rabbit. This may indicate a physiological role for substance P in the regulation of airway smooth muscle tone in the distal airways.

Origin and colocalization of CGRP- and SP-reactive nerves in cat airway epithelium.

A combination of neuroanatomic techniques was used to examine the origin and neuropeptide content of nerve fibers in the airway epithelium of adult cats. By the use of immunocytochemical methods, the peptides substance P (SP) and calcitonin gene-related peptide (CGRP) were colocalized in airway epithelial nerve fibers. Two days after wheat germ agglutinin (WGA) was injected into the nodose ganglion, fibers containing WGA immunoreactivity (IR) were detected in the airway epithelium. SP-like immunoreactivity (LI) and CGRP-LI were demonstrated separately in the WGA-IR fibers, establishing their origin from nerve cell bodies of nodose ganglion. Vagal transection inferior to the nodose ganglion reduced the number of SP- and CGRP-IR fibers by greater than 90% in ipsilateral airways. In contralateral airways, SP-IR fibers were substantially reduced, whereas the effect on CGRP-IR fibers was not statistically significant. Vagotomy superior to the nodose ganglion did not alter the density of peptide-IR fibers. The results prove that SP- and CGRP-IR nerve fibers of cat airway epithelium originate from nerve cell bodies in the nodose ganglion and that SP- and CGRP-like peptides may be stored together in some nerve fibers of the airway epithelium.

Chemical structure of phospholipids in the lungs and airways of sheep.

Experiments on phospholipids from the alveolar lining, bronchi and trachea were conducted to support the concept that different lipid complexes are synthesized and released at different sites in the pulmonary system. Tracheal, bronchial and bronchioalveolar lavages were obtained from healthy adult Merino breed ewes following euthanasia and a structural analysis of the phospholipid fraction made by fast atom bombardment mass spectrometry. The major components in tracheal lavage were: 72% phosphatidylcholines (PC), 8% phosphatidylethanolamines (PE) and 11% phosphatidylglycerols (PG) compared to 78% PC, 13% PE and 3% PG in bronchioalveolar lavage. The fatty acid profile of tracheal lavage showed that 73% of the PG and 3% of the PC contained an arachidonic acid side chain. These species were not found in bronchioalveolar lavage. The nearly four-fold increase in PG, and the different molecular species identified in tracheal compared to bronchioalveolar lavage, suggest local synthesis and release of phospholipids by tracheal epithelial cells. The distribution of these phospholipids may have functional properties desirable for normal mucociliary function and are consistent with published measurements from cultured tracheal epithelia cells.

Identification of three muscarinic receptor subtypes in rat lung using binding studies with selective antagonists.

Heterogeneity of the muscarinic receptor population in the rat central and peripheral lung was found in competition binding experiments against [3H]quinuclidinyl benzilate [( 3H]QNB) using the selective antagonists pirenzepine, AF-DX 116 and hexahydrosiladifenidol (HHSiD). Pirenzepine displaced [3H]QNB with low affinity from preparations of central airways indicating the absence of M1 receptors in the trachea and bronchi. Muscarinic receptors in the central airways are comprised of both M2 and M3 receptors since AF-DX 116, an M2-selective antagonist, bound with high affinity to 70% of the available sites while HHSiD, an M3-selective antagonist bound with high affinity to the remaining binding sites. In the peripheral lung, pirenzepine bound with high affinity to 14% of the receptor population, AF-DX 116 bound with high affinity to 79% of the binding sites while HHSiD bound with high affinity to 18% of the binding sites. The presence of M1 receptors in the peripheral airways but not in the central airways was confirmed using [3H]telenzepine, an M1 receptor ligand. [3H]Telenzepine showed specific saturable binding to 8% of [3H]QNB labeled binding sites in homogenates of rat peripheral lung, while there was no detectable specific binding in homogenates of rat trachea or heart. The results presented here demonstrate that there are three muscarinic receptor subtypes in rat lungs, and that the distribution of the different subtypes varies within the lungs. Throughout the airways, the dominant muscarinic receptor subtype is M2. In the trachea and bronchi the remaining receptors are M3, while in the peripheral lungs, the remaining receptors are both M1 and M3.

Immunohistochemical study of lung adenocarcinoma using monoclonal antibody for 60-kilodalton antigen in type II pneumocytes and nonciliated bronchiolar epithelial cells. Comparison with two antisurfactant apoprotein antibodies.

Monoclonal antibody KP16D3 was produced by immunizing mice with monkey bronchoalveolar lavage. KP16D3 revealed the immunohistochemical reactivity in the cytoplasm of some nonciliated bronchiolar epithelial cells and type II pneumocytes and thereby recognized specifically a protein with an apparent molecular weight of 60 kD with the use of Western blotting and immunoaffinity column chromatography followed by SDS-PAGE. Examination of 76 primary and 4 metastatic lung carcinomas in primary lung carcinoma KP16D3 showed immunohistochemical positivity only to mucin-nonproducing papillary adenocarcinoma (27/28) and bronchioloalveolar carcinoma (2/2), except for one case of large cell carcinoma. All other primary lung carcinomas such as squamous cell carcinoma, acinar adenocarcinoma, and small cell carcinoma had negative results. From these findings, KP16D3 seems to be an effective immunohistochemical marker of mucin-nonproducing papillary adenocarcinoma and bronchioloalveolar carcinoma of the lung and it appears to be useful to investigate both the histogenesis and functional expression of primary lung adenocarcinoma.

Use of an antiserum against deglycosylated human mucins for cellular localization of their peptide precursors: antigenic similarities between bronchial and intestinal mucins.

Highly glycosylated regions of mucins, or glycopeptides, were obtained by proteolysis of human bronchial mucins. They were deglycosylated by treatment with a trifluoromethane sulfonic acid/anisole mixture and subsequent solvolysis with anhydrous liquid hydrogen fluoride. The resulting peptides were then used to raise an immune serum in rabbit. This immune serum was used to localize the peptide precursors of human respiratory mucins within bronchial cells, using an immunohistochemical method. Two main patterns of labeling were observed in the goblet cells: the entire cytoplasm of some goblet cells was immunoreactive, whereas in other cells the labeling was concentrated around the nucleus. In the respiratory mucous glands, the labeling was localized around or below the nucleus. The serous cells were not stained. Similar labeling was observed in human colon goblet cells. This immune serum seems to be specific for mucin-secreting cells and has a strong affinity for the perinuclear region of these cells.

The distribution of heavy-chain isoforms of myosin in airways smooth muscle from adult and neonate humans.

Changes in the expression of heavy chains of myosin during development determine the functional characteristics of striated muscles. The distribution of heavy-chain isoforms of smooth-muscle myosin was determined in the airways of adult and infant humans to see whether it might underlie the hyperreactivity of human airways. The protein bands corresponding to myosin were separated using SDS/polyacrylamide-gel electrophoresis (4% gels) and identified by immunoblotting using both monoclonal and polyclonal antibodies against smooth-muscle myosin and non-muscle myosin. The relative proportion of each heavy chain stained by Coomassie Blue was measured by densitometric scanning. Three major bands corresponding to myosin heavy-chain isoforms were found; the two slower migrating bands (MHC1 and MHC2) were smooth-muscle myosin, and the third band was non-muscle myosin. The MHC1/MHC2 ratio was 0.69:1 in adult bronchus, and in infant bronchus and trachea. This contrasted with the airway smooth muscle in pigs, which was run concurrently, where the smooth-muscle heavy-chain ratio changed with development [Mohammad & Sparrow (1988) FEBS Lett. 228, 109-112]. The non-muscle myosin heavy chain comprised 63% of the smooth-muscle myosin. In both adult and infant lungs an additional putative myosin heavy chain which migrated slightly more rapidly than non-muscle myosin heavy chain was identified using the monoclonal smooth-muscle myosin antibody BF 48. This was unique to the human species.

Antileukoprotease-containing bronchiolar cells. Relationship with morphologic disease of small airways and parenchyma.

Twenty-seven surgically removed lungs and lobes were studied to assess the relation between the abundance of bronchiolar epithelial cells containing antileukoprotease (ALP) (ALP-pos/mm) and the degree of small airways disease (SADscore) and emphysema (destructive index = DI, and number of normal alveolar attachments on membranous bronchioles = normal AA/min). Between subjects, ALPpos/mm correlated with SADscore in membranous bronchioles (rs = 0.75; p less than 0.001) and with normal AA/mm (rs = -0.38; p = 0.05). Evaluation within each subject revealed significant correlations of ALPpos/mm with SADscore in membranous as well as in respiratory bronchioles (p less than 0.001), and also with normal AA/mm (p = 0.005). In membranous and in respiratory bronchioles, ALPpos/mm correlated significantly with the ALP concentration in homogenized tissue, as measured by ELISA (rs = 0.55 and 0.57, respectively; p less than 0.01). It is concluded that disease in small airways and destruction of their alveolar attachments are associated with a rise of the number of ALP-containing epithelial cells. We hypothesize that this cellular increase is part of the general defense against inflammatory and destructive processes in distal human airways, leading to higher levels of proteinase inhibitor in order to minimize tissue damage.

Covalent DNA damage in tissues of cigarette smokers as determined by 32P-postlabeling assay.

Covalent DNA addition products (adducts) formed by the reaction of chemical carcinogens or their metabolites with DNA are critically involved in the initiation of chemical carcinogenesis and may serve as molecular markers and dosimeters for environmental carcinogen exposures. Using a highly sensitive 32P-postlabeling assay for DNA adduct analysis, we studied DNA damage elicited by cigarette smoke in tissues of smokers. A multitude of characteristic smoking-induced, presumably aromatic DNA adducts were found to occur in a dose- and time-dependent manner in the lung, bronchus, and larynx of smokers with cancer of these organs and to decline only slowly after cessation of smoking. Low levels of adducts appeared to persist for up to 14 years in the lungs of exsmokers with high previous exposures. These results corroborate data of epidemiological studies showing that the lung cancer risk and mortality of smokers increase with the intensity and duration of smoking and decline only slowly after cessation of smoking. Tissue distribution studies in autopsy samples revealed the presence of smoking-associated DNA lesions also in the kidney, bladder, esophagus, heart, ascending aorta, and liver. The most extensive DNA damage was found in lung and heart, i.e., 1 aromatic adduct in about 10(7) DNA nucleotides. Our results suggest that cigarette smoking-induced DNA adduct formation is causally related to cancer in the target organs.

Distribution of vitamin B12 R-binder in lung tumors. Implications for cell differentiation.

Expression of vitamin B12 R-binder, a specific binding protein for vitamin B12, was studied immunohistochemically in normal lung tissues and 107 lung tumors of various types. In normal tissues, vitamin B12 R-binder (R-binder) expression was restricted to the mucous cells of bronchial or bronchiolar epithelium and submucosal glands as well as to nonciliated bronchiolar (Clara) cells. Among lung carcinomas, 38% of squamous cell carcinomas, 42% of adenocarcinomas and 23% of large cell carcinomas showed positive staining for R-binder whereas small cell carcinomas did not. These findings offer the possibility that a majority of the histologic types of lung carcinoma have common histogenetical characteristics with mucous or Clara cells. Of the bronchial gland tumors, R-binder could be detected in a mucoepidermoid carcinoma but not in adenoid cystic carcinomas. Epithelial components in both pulmonary blastomas and hamartomas showed a reactivity for R-binder, suggesting that these tumors contained components composed of cells with bronchiolar cell differentiation. The immunohistochemical examination of lung tumors, using anti-R-binder antibody, may have some implications in the cell differentiation of lung tumors.

[Immunomorphological determination of secretory immunoglobulin A in the bronchial mucous membrane in chronic bronchitis]. / Immunomorfologicheskoe opredelenie sekretornogo immunoglobulina A v slizistoi obolochke bronkhov pri khronicheskom bronkhite.

The disappearance of the secretory immunoglobulin A in chronic bronchitis is shown to result from the disappearance of the epitheliocytes capable of secreting this substance. The secondary immunoglobulin A deficiency is followed by its accumulation in the basal epithelial cells. The absence of the secretory component probably prevents the immunoglobulin A diffusion to the epithelium surface this decreasing the local immunity against various antigens and the possibility of their elimination. It is suggested that the epithelial alterations described in patients with chronic bronchitis are among the causes for non-specific lung diseases to become chronic.

Effects of serum, transforming growth factor type beta, or 12-O-tetradecanoyl-phorbol-13-acetate on ionized cytosolic calcium concentration in normal and transformed human bronchial epithelial cells.

Fluctuations in ionized cytosolic calcium ([Ca2+]i) are considered important signals for induction of growth or differentiation in mammalian cells. The resting concentrations of [Ca2+]i in normal and adenovirus 12-SV40 hybrid virus-transformed (BEAS-2B) human bronchial epithelial cells were 63 +/- 15 nM (SD) and 44 +/- 15 nM, respectively. Eight % calcium-free fetal bovine serum rapidly caused a significant increase in [Ca2+]i, while causing both cell types to undergo squamous differentiation. When treated with 8% calcium-free fetal bovine serum, a serum-sensitive subclone of BEAS-2B cells exhibited a higher elevation of [Ca2+]i than a serum-resistant (i.e., not stimulated to differentiate by serum) subclone. However, a serum component involved in the induction of squamous differentiation, transforming growth factor type beta, did not increase [Ca2+]i in either normal cells or BEAS-2B cells. 12-O-Tetradecanoyl-phorbol-13-acetate, an exogenous inducer of squamous differentiation and activator of protein kinase C, did not increase [Ca2+]i, but did attenuate serum-induced elevation of [Ca2+]i. These results suggest that while an increase in [Ca2+]i is associated with serum-induced squamous differentiation, a cytosolic ionized calcium signal is not required for the initiation of the squamous differentiation pathway induced by either transforming growth factor type beta or 12-O-tetradecanoylphorbol-13-acetate.

Macromolecular and lipid constituents of bronchial epithelial mucus.

The physical and chemical properties of bronchial epithelial mucus depend on its special mix of macromolecules and lipid constituents: these are different in the normal airway under baseline conditions from one stimulated acutely, and show major modification in disease. Since the last conference, density gradient ultracentrifugation has been extended to the study of normal bronchial mucus in addition to that of sputum from patients with chronic bronchitis, cystic fibrosis and asthma, and has revealed striking differences between the chemical profiles of normal and hypersecretory mucus. Normal mucus represented individual bronchial aspirates, obtained at fiberoptic bronchoscopy from healthy human volunteers (non-smokers), aspirates from normal dogs (before SO2 exposure in a canine model of SO2 induced bronchitis) and secretions released in vitro by human bronchial and canine tracheal explants. Mucus 'in transition' included aspirates from otherwise healthy smokers and from dogs early in irritation. Hypersecretory mucus included, besides those mentioned above, aspirates from dogs that had developed bronchitis and the excessive mucus produced by some patients with acute quadriplegia. Lipids. In normal mucus, human (unpooled) and canine, neutral lipids are the predominant species, with lesser amount of phospholipids: no glycolipids are detected. The first qualitative change on irritation, even before macromolecular yield increases, is appearance of glycolipids. In hypersecretory mucus, human (including quadriplegics) or canine, glycolipids are detected in appreciable amounts and often are the predominant species: they include complex forms such as sialic acid containing gangliosides. Organ and cell culture studies establish that these lipids are produced by airway epithelial cells. These lipids are important to gel formation. Glycoconjugates. A major recent advance is the recognition that normal mucus does not contain typical epithelial glycoprotein. Its glycoconjugate is of higher density with sugars typical of both glycoprotein (GP) and proteoglycan (PG) and with an amino acid profile more akin to PG (glycine greater than serine greater than threonine). In transition to hypersecretion, a 'mixed molecule' changes its sugar mix to produce a density typical of GP. In hypersecretion, the epithelial GP develops a typical buoyant density and amino acid profile (threonine greater than serine greater than glycine). Organ culture of bronchial explants, and more recently cell culture, establish that the PGs are major products of airway secretory cells. The normal airway is capable of producing glycoprotein on cholinergic stimulation. The range of glycoconjugates present in the secretion support the wide range of granule and cell features identified in vivo. Monoclonal antibody raised to a pure preparation of bronchial epithelial glycoprotein reacts with mucous cells in the surface epithelium and also in the submucosal gland in both human and canine airways.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of human tracheo-bronchial mucin precursors.

Bronchial mucin peptide chains were obtained by performing a two-step chemical deglycosylation of the highly glycosylated regions (or glycopeptides) which are the most characteristic part of bronchial mucins. The deglycosylated preparation was used to prepare an antiserum directed against mucin peptide epitopes. This antiserum reacted with the area containing rough endoplasmic reticulum of goblet cells and of mucous gland of human bronchial mucosa but not with secretory vesicles. The antiserum was used for immunoprecipitation of radiolabelled mucin precursors in pulse-chase experiments with explants of human bronchial mucosa. SDS-polyacrylamide gel electrophoresis followed by fluorography revealed precursors with a molecular mass in the range of 200 to 400 kDa as early as after 10 min pulse labeling with [3H]threonine. These results suggest that the mucin polydispersity previously visualized by electron microscopy may be explained by the synthesis of several respiratory mucin peptide precursors with different molecular sizes and/or that precursors with different amounts of carbohydrate are rapidly formed.