Cystic Fibrosis Mucus Research Articles

Abnormal fucosylation of ileal mucus in cystic fibrosis: I. A histochemical study using peroxidase labelled lectins.

Peroxidase conjugated lectins were used to analyse the glycoproteins of small intestinal mucins in normal infants and those with cystic fibrosis to ascertain whether there are any detectable histochemical differences in saccharide composition. A significant decrease in Lotus tetragonolobus (LTG) binding fucose was shown in normal small intestinal mucin starting around 36 weeks' gestation with total absence of staining at term and beyond. In contrast, the age matched patients with cystic fibrosis showed persistent and intense LTG binding of fucose. These results provide the first clear histochemical evidence that cystic fibrosis mucin is abnormal and confirm the findings of previous biochemical studies.

Abnormal fucosylation of-ileal mucus in cystic fibrosis: II. A histochemical study using monoclonal antibodies to fucosyl oligosaccharides.

Abnormal fucosylation of cystic fibrosis mucin was previously shown using peroxidase conjugated lectins on ileal tissue sections. These abnormally fucosylated glycoproteins were investigated further using monoclonal antibodies to fucosyl oligosaccharides based on type 1 and type 2 blood group precursor chains. The results of this study, using monoclonal antibodies to blood group glycoproteins in cystic fibrosis, were negative, yet abnormal fucosylation had been found using lectin histochemistry. Using monoclonal antibodies, lectins, and appropriate enzymes, such as glycosyl hydrolases, it should be possible to delineate further the abnormality found in glycoproteins in cystic fibrosis on appropriately fixed ileal sections, obtained from infants at term presenting with meconium ileus.

The Role of Mucous Glycoproteins in the Rheologic Properties of Cystic Fibrosis Sputum

Cystic fibrosis (CF) is characterized by excessive amounts of thick and tenacious mucous secretions that obstruct organ ducts and passages. In the respiratory tract this is associated with chronic infection resulting in the hypersecretion of purulent sputum, which the patient finds difficult to clear. We have studied the rheologic properties of purulent sputum from six patients with CF and five patients with chronic bronchitis to assess whether CF is associated with increased sputum viscoelasticity. In addition, we have isolated the major rheologic determinants, mucous glycoproteins, from CF and chronic bronchitis sputa and, using a magnetic microrheometer, investigated the possibility that the altered properties of mucus in CF are associated with abnormalities in these glycoproteins. Creep compliance analysis indicated that the CF sputa possessed raised levels of both elasticity (p less than 0.01) and viscosity (p less than 0.01). These increases in both rheologic parameters were found to be associated with increases in the DNA content (p less than 0.01) and dry weight (p less than 0.05). Mucous glycoproteins were isolated from CF and chronic bronchitis sputum samples by gel filtration on Sepharose CL4B, followed by concentration to form 8% wt/wt gels. In the absence of other sputum components, no abnormality in the rheologic properties of CF mucin gels could be detected. However, when DNA was added, the CF gels responded with increases in both elasticity and viscosity of as much as 30% (p less than 0.05), an effect not observed in the chronic bronchitis gels. These results suggest that a subtle abnormality may exist in CF mucous glycoproteins and that this could have a role in the altered physical properties of mucous secretions in CF.

X-Ray Microanalysis of Respiratory Epithelial Cells in the Study of Cystic Fibrosis

One of the most important clinical symptoms associated with cystic fibrosis (CF) is obstructive airway disease and recurrent airway infections. The smaller airways in CF patients are blocked by viscous mucus, and infections are common and difficult to manage. Generally, lung disease is directly or indirectly the cause of death in CF. The viscous mucus in CF is likely to be a result of defective water transport in the respiratory epithelium. Water transport is coupled to chloride secretion, and it is strongly suspected that a defective chloride channel in the apical membrane of the respiratory epithelial cells is the basic error in CF. We therefore studied changes in the intracellular concentration of chloride (and other ions) by x-ray microanalysis of cultured respiratory epithelial cells under a variety of conditions.Tissues were obtained from material excised during polypectomy. The tracheal mucosa was digested with collagenase and the dispersed cells were plated onto Milliporefilters coated with human placental collagen.

Acute and Long-term Amiloride Inhalation in Cystic Fibrosis Lung Disease: A Rational Approach to Cystic Fibrosis Therapy

Cystic fibrosis (CF) is the most common inherited fatal disorder among Caucasians. Bronchial mucus in CF contains more potassium and less sodium, which may be due to increased sodium absorption, resulting in a reduced airway water content. We studied 23 patients with CF after inhalation of normal saline or amiloride (10(-3) M), a sodium transport blocker. Mucociliary clearance (MC) and cough clearance (CC) were determined with a gamma camera that traced the movement of 99mTc-labeled, hardened erythrocytes over a 1-h period after the patients inhaled these particles as an aerosol. Before and after each investigation pulmonary function tests (PFT) and blood pressure (BP) were measured. Sputum thread formation was measured by means of a filancemeter. Six of the patients also completed a 3-wk trial of amiloride inhalation therapy. MC increased significantly (p less than 0.001) after acute amiloride inhalation (bronchial deposition, 0.07 mg amiloride) compared with that in the saline control. CC also increased, but not as much as MC. After 3 wk of amiloride inhalation (2 times a day) clearance values (both MC and CC) were markedly enhanced (p less than 0.01); after a similar period of saline inhalation, clearance values were not different from baseline. Sputum filance values also decreased significantly after amiloride inhalation. There were no adverse effects of the amiloride inhalation compared with saline. We conclude that amiloride inhalation administered as a single dose or as long-term therapy is able to increase MC and CC in CF airways and that the effect of 10(-3) M amiloride inhalation on MC lasts at least 40 min. (ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of Staphylococcus aureus in cystic fibrosis

Staphylococcus aureus is usually the first bacterial pathogen detected in the respiratory secretions of patients with cystic fibrosis. This review briefly examines the characteristics of this host-parasite relationship in terms of current knowledge about the toxicity of the organism, mechanisms of respiratory tract injury, therapy and prevention. Recent evidence indicates that viral infection plays a role in the initial damage of the respiratory epithelial cells and staphylococcal colonization ensues. Affinity of staphylococcus for cystic fibrosis mucus, mucociliary abnormalities and unknown factors contribute to persistent colonization with this organism causing progressive pulmonary damage and possibly influencing Pseudomonas infection. Most of the evidence today indicates that aggressive antibiotic management directed against S. aureus is warranted in all stages of bronchopulmonary infection in cystic fibrosis. Future efforts to prevent colonization and the toxic and immunopathic consequences of staphylococcal infection are also important. One study is in progress that examines antibiotic prevention in the early stages of cystic fibrosis. Future investigations need to address other strategies including vaccines, antitoxins, anti-inflammatory agents, immunomodulators, and antibiotic regimens.

Effect of Covalently Bound Fatty Acids and Associated Lipids on the Viscosity of Gastric Mucus Glycoprotein in Cystic Fibrosis

The contribution of associated and covalently bound lipids to the viscosity of gastric mucus glycoprotein in healthy and cystic fibrosis (CF) individuals was investigated. While both preparations exhibited similar contents of protein and carbohydrate, the CF glycoprotein contained 1.3 times more associated lipids and 6 times more covalently bound fatty acids. The viscosity of CF mucus glycoprotein was about 1.8 times higher than that of normal glycoprotein. Extraction of associated lipids lead to 3-fold drop in the viscosity of CF glycoprotein and 5-fold drop in the case of normal glycoprotein. Removal of covalently bound fatty acids caused further 1.6-fold reduction in the viscosity of normal mucus glycoprotein and 6-fold in CF glycoprotein. The viscosity of the delipidated and deacylated CF mucus glycoprotein was only about 10% higher than that of the similarly treated normal glycoprotein. The results suggest that the elevated level of covalently bound and associated lipids is responsible for the increased viscosity of CF mucin.

Mucus glycoprotein fatty acyltransferase in patients with cystic fibrosis: Effect on the glycoprotein viscosity

The presence of an acyltransferase activity which catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to mucus glycoprotein has been demonstrated in the microsomal fraction of human rectal mucosa. The activity of this enzyme in the mucosa of patients with cystic fibrosis (CF) was found to be 3.5 times higher than that from normal individuals. The CF mucus glycoprotein in comparison to that of normal contained 1.3 times more associated lipids and 6 times more covalently bound fatty acids. The viscosity of the intact CF glycoprotein was 1.8 times higher than that of normal glycoprotein. Extraction of associated lipids led to 3-fold drop in the viscosity of CF glycoprotein and 5-fold drop in the case of normal glycoprotein. Further loss in the viscosity occurred following removal of the covalently bound fatty acids. The viscosity of such modified CF mucus glycoprotein was only about 10% higher than that of similarly treated normal glycoprotein.

Isolation of fatty acids covalently bound to the gastric mucus glycoprotein of normal and cystic fibrosis patients

Covalently bound fatty acids were found in strictly purified and delipidated gastric mucus glycoprotein of normal and cystic fibrosis individuals. The susceptibility of this linkage to methanolic KOH and hydroxylamine treatment indicated the ester bond between fatty acids and glycoprotein. On the average, 2.9 nmol fatty acid/mg glycoprotein were found in normal samples, and 12.2 nmol/mg glycoprotein in samples derived from cystic fibrosis. In normal gastric mucus glycoprotein the covalently linked fatty acids consisted of hexadecanoate (47.0%), octadecanoate (22.0%), tetracosanoate (5.9%), octadecenoate (14.5%) and tetracosenoate (6.0%). In cystic fibrosis mucus glycoprotein the covalently bound fatty acids were comprised mainly of hexadecanoate (36.5%), octadecanoate (48.7%) and octadecenoate (8.6%). These data indicate that cystic fibrosis gastric mucus glycoprotein is highly acylated and perhaps this is the major defect of glycoproteins in this disease.

Isolation of bronchial mucins from cystic fibrosis sputum by use of citraconic anhydride

Citraconylation was used to solubilize cystic fibrosis sputum and to dissociate its mucus glycoproteins from extraneous proteins. The mucin fraction was isolated by precipitation with Cetavlon, and characterized in terms of amino acid and carbohydrate composition. The data suggest that, in determining the physical properties of glycoproteins of cystic fibrosis mucus, aggregation by noncovalent forces may be as important as (or more important than) disulfide bonds.

Is cystic fibrosis mucus abnormal?

It has been known for some time that the viscosity of sputum from cystic fibrosis (CF) patients differs from that in other disease types characterized by pulmonary hypersecretion. However, it has never been established that there is in fact any abnormalities in the rheologic properties of CF sputum. We have recently developed techniques to examine the rheology and mucociliary transportability of tracheal secretions from dogs utilizing the small quantities of mucus available from a healthy animal. In the present study, these in vitro techniques were applied to sputum samples obtained from 15 adult CF patients. For mucoid and mucopurulent CF sputum samples, the viscoelastic properties were remarkably similar to those observed for control canine tracheal mucus samples. For purulent CF sputum, elasticity and viscosity tended to be higher and the viscosity/elasticity ratio lower than for either the nonpurulent sputum or the canine tracheal mucus. The logarithm of elasticity at 1 rad/sec was 2.55 +/- 0.35 (S.D.) for purulent sputum, 2.05 +/- 0.49 for mucoid and mucopurulent sputum, and 2.17 +/- 0.36 for canine tracheal mucus. From the viscoelastic properties of CF sputum, one would have predicted the in vitro mucociliary transportability, at least for the nonpurulent samples, to be the same as that of canine tracheal mucus. However, the frog palate assay indicated a consistently lower rate of transport (mean difference, 13%) than that predicted from previous studies. This result would, therefore, suggest that if the prediction from canine tracheal mucus is applicable there is a factor in the CF sputum that results in a temporary inhibition of frog palate ciliary beating. This apparent inhibition of mucociliary transport is, however, relatively minor, and it is perhaps more remarkable that for none of the sputum samples collected was the in vitro ciliary transport rate particularly low; i.e., observed values ranged from 65 to 100% of frog palate control.

Control of Mucus Secretion and Ion Transport in Airways

The output of secretions from the airway submucosal glands is regulated by vagal efferent nerves. Stimulation of cough receptors increases mucus output reflexly via the vagus nerves. Adrenergic agonists increase submucosal gland secretions in some species, which indicates that adrenergic receptors are present in these cells. However, evidence for adrenergic nervous pathways to the glands is limited. Irritants and drugs stimulate secretion from epithelial cells by direct effects. There is also evidence that the secretion of epithelial cells can be stimulated by parasympathetic nervous pathways in birds but not in mammals. Active ion transport of Cl- toward the lumen and of Na+ toward the submucosa results in net ion movement toward the airway lumen in unstimulated tracheal epithelia. Drugs and mediators increase the net movement of ions toward the lumen. No agents have yet been found that increase net ion movement toward the submucosa. The link between ion transport and water secretion in airway epithelia, although speculative, seems likely in view of the evidence from other epithelia. Since airway epithelium is a "tight junction" epithelium, modification of the tight junction may alter the transepithelial movement of water and ions. We suggest that the depth and consistency of the periciliary layer of airway secretions determine the ability of the cilia to propel the mucoprotein gel and thereby modify mucociliary transport. To achieve this, secretion of mucus must be controlled separately from the secretion of water. Studies are needed to determine which of the specialized functions of the epithelial cells interact to regulate the clearance of secretions from the airway. Is the sol maintained by secretion and reabsorption of fluid across the epithelium? Does the sol move with the gel by ciliary action or does it remain stationary? Do changes in the epithelial tight junctions influence net water movement and thus indirectly alter the depth of the sol layer? To answer these questions, techniques are needed to study subunits of the airway, including isolated surface cells and submucosal glands; and sensitive methods are required to analyze the very small samples of secretions for glycoprotein and electrolyte content. Intracellular measurements of electrolyte concentrations and electrical potentials may help to elucidate the mechanisms of transepithelial ion and water movement. The control system for the production and removal of respiratory tract secretions may be altered in disease. For instance, chronic stimulation of cough receptors causes reflex secretion and may be the cause of the hyperplasia of submucosal glands and of the abnormal secretions that occur in chronic bronchitis and asthma (50, 58). The abnormally viscid mucus in cystic fibrosis may be due to a defect in Cl- transport, which provides too little water for both the gel and sol layers. These speculations are intended to identify areas for further research, which hopefully will reduce the morbidity and mortality in these common lung diseases.

The Electron Microscopic Appearance of Presecreted Gastric Mucus in Cystic Fibrosis

Gastric mucosal biopsies from eight new untreated patients with cystic fibrosis (CF) and two normal subjects were studied by quantitative techniques of electron microscopy (EM) to determine whether presecreted gastric mucus was more compact (viscid) than normal. Analysis of variance techniques show no differences between means of all groups studied. These observations suggest that mucus may not be viscid prior to secretion. Electron microscopy of gastric mucus does not appear to be of diagnostic value in CF.

Mucus, Calcium, Sweat, Water, and Permeability in Cystic Fibrosis

Gibson et al.1 have proposed that mucus normally inhibits passive flow of water and small ions, but fails to perform this function adequately in patients with cystic fibrosis (CF), due to excessive secretion of calcium for exocrine glands. Negus2 first suggested, without adequate experimental data, that epithelial mucins control water and electrolyte permeability. For reasons discussed here, this concept, and other facets of the Gibson hypothesis, are not supported by Gibson's investigations. The authors developed an assay (Exp. I) for movement of water through films of submaxillary saliva (SMS) layered on dialysis membranes. When movement through CF and control films was compared, disparate relationships between film thickness and water permeability were observed.

Cervical mucus in cystic fibrosis: A possible cause of infertility

Cervical mucus in cystic fibrosis: A possible cause of infertility

Histochemistry of rectal mucus in cystic fibrosis of the pancreas.

Histochemistry of rectal mucus in cystic fibrosis of the pancreas.

The composition of rectal mucus in cystic fibrosis.

CYSTIC FIBROSIS is sometimes called mucoviscidosis, which implies that the basic defect is an abnormality of the mucus. Abnormal viscosity of pulmonary mucus secretions is considered to be the cause of the tendency to bronchial infection. Mucus secretions of other organs show evidence of abnormality. An example of this is the histological appearance of rectal mucus glands, as demonstrated by Parkins et al. 1 The present study was undertaken to determine whether the supposedly abnormal mucus in cystic fibrosis has a detectable alteration of the sugar components of the mucoprotein. Rectal mucus seemed favorable for investigation because it could be obtained with relative ease and in an uncontaminated form, ie, free of other secretions and of exudate. Elevated ratios of fucose to sialic acid have been reported in mucoprotein from sweat, urine, and gastric mucus of cystic fibrosis patients. 2-4 An elevated ratio of fucose to hexosamine has been noted

BRONCHIAL OBSTRUCTION IN CYSTIC FIBROSIS: RHEOLOGICAL FACTORS

Rheological studies of the respiratory secretions from patients with cystic fibrosis and from controls are presented. The apparent viscosities of mucous secretions were obtained in five patients with cystic fibrosis and in seven control subjects. The viscosity values for cystic fibrosis mucus after shearing were found to be about 5 times that of controls. The structure of the mucous molecule is discussed, and the various factors affecting its viscosity and flow characteristics are described. The effect of 0.5 molar NaCl solution in dispersing cystic fibrosis mucus is presented. This effect suggests the theory that the high viscosity of mucus in cystic fibrosis is due to a decreased concentration of sodium ions in the structure of the mucous molecule. A link between the high concentration of salt in the sweat and the high viscosity of mucus of patients with cystic fibrosis could thereby be provided.