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Liposomes and viruses for gene therapy of cystic fibrosis.

Cystic fibrosis (CF) is a common, life-threatening autosomal recessive disease caused by mutations in the CFTR gene. It affects the function of the lung, gut, and liver. Present strategies for CF aim to correct the defect by introducing a normal copy of the CFTR gene into affected epithelial cells. Two vector systems have been proposed for gene therapy trials, replication defective adenovirus and cationic liposome/DNA complexes. Adenoviral vectors have been used in Phase I trials and in most cases give transient molecular and/or electrophysiological restitution of the ion transport cellular defects of CF. However, a dose of 10(9) pfu/ml applied to the lung led, in one patient, to a transient inflammatory reaction. New adenoviral vectors are presently being developed to solve this problem. Our studies using liposome/DNA complexes to deliver CFTR cDNA to the nasal epithelium were carried out in the double blind trial and showed no treatment-related local or general adverse reactions and significant small but transient correction of the ion transport defect. The results for both current approaches demonstrate the need for substantial improvement of the efficiency and duration of transgene expression to reach therapeutically relevant levels.

Adenoviridae↗

Endothelial perturbation in cystic fibrosis.

Cystic fibrosis (CF) is characterized by a persistent inflammatory state, which can be secondary to chronic pulmonary infection and may affect vascular endothelium. We measured circulating levels of von Willebrand factor (vWF), tissue-plasminogen activator (t-PA), and P-selectin in 20 CF patients and 20 healthy subjects. vWF, t-PA and P-selectin levels were significantly higher in CF patients. Endothelial perturbation (>2 SD increase in both vWF and t-PA) was present in 65% of CF patients. These patients displayed lower FEV1 values compared to individuals without endothelial perturbation and an inverse correlation between FEV1 and P-selectin levels was observed. Tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6 levels were also increased in CF patients and significant direct correlations were found between TNF-alpha and vWF, t-PA or P-selectin levels. These results indicate that CF patients exhibit signs of endothelial dysfunction/perturbation, which are likely to be related to a persistent inflammatory state due to chronic pulmonary infection, and may play a role in the progression of this disease.

Adolescent↗

Glutathione aerosol suppresses lung epithelial surface inflammatory cell-derived oxidants in cystic fibrosis.

Cystic fibrosis (CF) is characterized by accumulation of activated neutrophils and macrophages on the respiratory epithelial surface (RES); these cells release toxic oxidants, which contribute to the marked epithelial derangements seen in CF. These deleterious consequences are magnified, since reduced glutathione (GSH), an antioxidant present in high concentrations in normal respiratory epithelial lining fluid (ELF), is deficient in CF ELF. To evaluate the feasibility of increasing ELF GSH levels and enhancing RES antioxidant protection, GSH aerosol was delivered (600 mg twice daily for 3 days) to seven patients with CF. ELF total, reduced, and oxidized GSH increased (P < 0.05, all compared with before GSH therapy), suggesting adequate RES delivery and utilization of GSH. Phorbol 12-myristate 13-acetate-stimulated superoxide anion (O2-.) release by ELF inflammatory cells decreased after GSH therapy (P < 0.002). This paralleled observations that GSH added in vitro to CF ELF inflammatory cells suppressed O2-. release (P < 0.001). No adverse effects were noted during treatment. Together, these observations demonstrate the feasibility of using GSH aerosol to restore RES oxidant-antioxidant balance in CF and support the rationale for further clinical evaluation.

Adult↗

Relationship between intestinal function and chloride secretion in patients with cystic fibrosis.

Cystic fibrosis (CF) is the most frequent inheritable disease with a lethal course. One of the major problems of the disease is malabsorption and malnutrition, due to pancreatic insufficiency which is already present at birth in more than 85% of the patients. Characteristically the mucoid secretion products of the epithelial tissues in lung, pancreas, liver and intestine have a high viscosity. The pathophysiology is characterized by obstruction of these organs with secondary damage and finally destruction. For a long period intestinal obstruction syndromes in CF were ascribed only to the pancreatic insufficiency. Malabsorption is not only caused by enzyme deficiency but is also related to transport processes to the surface of the enterocytes. This indicates that the intestinal disorders in CF are partly the result of mucoid plugging and not only of pancreatic insufficiency. Recently in vitro studies have shown a blockade of secretion through chloride channels in the mucosal membrane of CF tissues. In vivo measurements of chloride fluxes in the rectum showed a disturbed regulation in CF patients. The high viscosity of the mucus and plugging is directly related to the diminished chloride secretion. So it is postulated that the abnormal chloride secretion is responsible for the intestinal obstruction and partially also for the malabsorption.

Chlorides↗

Pharmacologic treatment of abnormal ion transport in the airway epithelium in cystic fibrosis.

Cystic fibrosis (CF) is a recessive genetic disease reflecting mutations in the gene coding for the CF transmembrane regulator (CFTR) protein, which normally functions as a cyclic adenosine monophosphate (cAMP)-regulated chloride (Cl-) channel. Functional abnormalities include thick airway secretions resulting from defective cAMP-mediated Cl- (liquid) secretion and a related defect, excessive sodium (Na+) (liquid) absorption. Novel pharmacologic agents are being tested as therapy for these ion transport defects. Aerosolized amiloride inhibits excessive Na+ absorption, and pilot studies in adult patients with CF show slowing of the disease-associated decline in lung function. Clinical trials of amiloride are currently underway in adults and adolescents, and short-term safety studies have been initiated in children. Aerosolized uridine triphosphate (UTP) induces Cl- (and liquid) secretion in CF airway epithelia via non-CFTR Cl- channels. Short-term aerosolized UTP is well tolerated by normal subjects and patients with CF, and pilot studies in normal subjects show that aerosolized UTP is an effective stimulator of mucociliary clearance. Pharmacotherapy that modifies airway epithelial ion transport may provide new opportunities for treatment of CF lung disease.

Adolescent↗

Characterization of small-colony-variant Stenotrophomonas maltophilia isolated from the sputum specimens of five patients with cystic fibrosis.

Cystic fibrosis (CF) patients are predisposed to chronic respiratory infection by nonfermentative gram-negative bacilli, including Stenotrophomonas maltophilia. S. maltophilia is highly resistant to most antibiotics, with the exception of sulfamethoxazole-trimethoprim (SXT). SXT-resistant S. maltophilia has been reported, but the mechanism of resistance is not well defined. Repeated findings of suspected small-colony-variant (SCV) S. maltophilia isolates from the sputa of five CF patients were confirmed by partial 16S rRNA gene sequencing. The SCV S. maltophilia isolates were the only S. maltophilia isolates in these cultures, and none were clonally related. DNA fingerprint analysis confirmed that once established, the SCV S. maltophilia strains persisted. Nutritional studies of SCV S. maltophilia have suggested auxotrophy in hemin, methionine, and thymidine associated with resistance to multiple antibiotics, including SXT. The phenotypic switch from wild-type to SCV S. maltophilia was reproducible in vitro by exposure to SXT, suggesting that prolonged exposure to antibiotics may select for both the SCV S. maltophilia phenotype and SXT resistance by interference with the dihydrofolate reductase pathway. Recovery of SCV S. maltophilia from the sputum of CF patients has implications for both laboratory testing and patient management.

Anti-Bacterial Agents↗

[DNA analysis and prenatal diagnosis in cystic fibrosis].

Cystic fibrosis (CF) is the most common autosomal recessive lethal genetic disorder in man, affecting 1 in 2,000 live births. The carrier frequency in Caucasians is 1 in 20. Approximately 70 per cent of the mutations correspond to a specific deletion on chromosome 7 (region 7q31). This delta F 508 mutation of the CF gene results in the loss of phenylalanine at position 508 in the gene product. About 50 per cent of the individuals with CF are homozygous for this deletion and suffer from pancreatic insufficiency. The remaining half are mostly compound heterozygotes between this deletion and another mutation. They exhibit less severe symptoms. Several simple polymerase chain reaction (PCR) tests are available to detect the delta F 508 mutation, allowing rapid prenatal diagnosis of the disease. In those families where other mutations of the CF gene are involved prenatal diagnosis is performed by means of tightly linked restriction fragment length polymorphisms (RFLPs). PCR tests are available for RFLP analysis too. Testing for the delta F 508 deletion, present in about 3 per cent of the normal population, may prove invaluable for extensive carrier screening. Thus, half of the couples at risk could be recognized before the first affected child is born.

Amino Acid Sequence↗

Glucose tolerance and insulin receptor binding to monocytes and erythrocytes in patients with cystic fibrosis.

Cystic fibrosis (CF) is the most frequent life threatening hereditary disease in the Western World with an incidence of approximately 1:2000. Due to increasing survival rates the high frequency of abnormal glucose tolerance has become an important problem. We compared insulin concentrations during oral glucose tolerance test and insulin receptor binding to both monocytes and erythrocytes from 9 patients with CF, with results from 10 healthy controls of similar body weight. The insulin: glucose ratio was increased in the fasting state (p less than 0.05) in patients with CF compared to controls, indicating an increased insulin resistance in CF-patients. The total insulin secretion during oral glucose tolerance test as judged by the area beneath the insulin curve was similar in the two groups, but insulin secretion was significantly delayed in patients with CF. Insulin receptor binding to monocytes and the number of receptors were significantly increased (p less than 0.01 and 0.02, respectively) in patients with CF whereas the dissociation constant was similar in patients with CF and controls. No difference was observed in insulin receptor binding to erythrocytes between the two groups. No correlations were found between insulin receptor binding to monocytes or erythrocytes and glucose tolerance or insulin concentrations.

Adolescent↗

The application of PCR amplification and the polymorphic marker KM.19 to dried blood spots: comparison with deletion 508 for the confirmation of the neonatal screening test for cystic fibrosis.

Cystic fibrosis (CF) screening by measurement of immunoreactive trypsin (IRT) lacks specificity: only 9% of hypertrypsinemic neonates have CF. We have studied retrospectively 114 hypertrypsinemic samples (including 37 CF) for KM.19 polymorphic DNA marker and made risk calculations. If the neonate is homozygous for KM.19 allele 2, the risk of CF rises to 55%; if homozygous for allele 1, the risk is very low (less than 1%) and if heterozygous, the risk is intermediate (4%). In a prospective study including 28,000 IRT tests, 76 neonates with IRT greater than 800 micrograms/L have been identified: 16 were homozygous for allele 2 (8 CF), 30 for allele 1 (1 CF), and 30 were heterozygotes (no CF). Deletion 508 was present in 10 neonates: 4 homozygotes (4 CF) and 6 heterozygotes (3 CF). Two CF did not carry any copy of deletion 508. We have studied 181 (presumably non-CF) neonates with IRT greater than 600 micrograms/L. The KM.19 genotypes distribution is significantly different from the one expected in the French population: homozygotes for allele 2 are more numerous. Furthermore, heterozygotes for deletion 508 are 1 in 15 (expected: 1 in 42). In conclusion, molecular biology in dried blood spots can enhance the specificity of CF neonatal screening, but IRT and genotype may not be independent.

Blood Specimen Collection↗

Effect of uridine 5'-triphosphate plus amiloride on mucociliary clearance in adult cystic fibrosis.

Cystic fibrosis (CF) is characterized by abnormal airway epithelial electrolyte transport leading to viscous airway secretions that are difficult to clear. By enhancing Cl- secretion onto and blocking Na+ absorption from the airway surface, treatment with aerosolized uridine 5'-triphosphate (UTP) plus amiloride may improve the rheology of airway secretions and enhance mucociliary clearance in patients with CF. After performing safety studies of aerosolized UTP/amiloride in adult patients with CF, we investigated the effects of inhaled vehicle and UTP/amiloride on mucociliary clearance of [99mTc] iron oxide particles from the airways of adult patients with CF (n = 14). We found no clinically significant adverse effects from inhalation of therapeutic doses of UTP/amiloride. Mean baseline peripheral clearance rates during the first 40 min of clearance measurements were significantly less in patients with CF than in normal subjects (mean +/- SE: 0.30 +/- 0.05 versus 0.54 +/- 0.07%/min, respectively; p = 0.01). Aerosolized UTP and amiloride in combination improved mucociliary clearance from the peripheral airways of the CF lungs to near normal values (0.51 +/- 0.09%/min; p = 0.04) during this period. These data support the concept for the use of UTP in combination with amiloride as therapy to improve clearance of secretions from the lungs of patients with CF.

Adult↗

Increased sulfation of glycoconjugates by cultured nasal epithelial cells from patients with cystic fibrosis.

Cystic fibrosis (CF) respiratory epithelia exhibit abnormal anion transport that may be linked to abnormal lung defense. In these studies, we investigated whether primary cultures of CF respiratory epithelial cells regulate abnormally the sulfate content of high molecular weight glycoconjugates (HMG) participating in airways' mucosal defense. HMG, including glycosaminoglycans and mucin-type glycoproteins released spontaneously into medium and HMG released from cell surfaces by trypsin, were metabolically labeled with 35SO4- and [6-3H]-glucosamine (GlcN) or 35SO4- and [3H]serine. All three classes of HMG from CF cells exhibited 35S/3H labeling ratios 1.5-4-fold greater than HMG from normal or disease control cells. Differences for labeling ratios of HMG from CF cells were shown to be the consequence of increased 35SO4- incorporation rather than decreased peptide synthesis and release or HMG glycosylation. The buoyant density of CF mucin-type HMG also was increased, consistent with increased sulfation. These observations suggest that oversulfation of a spectrum of HMG is a genetically determined characteristic of CF epithelial cells and may play an important pathophysiological role by altering the properties of mucous secretions and/or the interactions between selected bacteria and HMG at the airways' surface.

Adolescent↗

Myeloperoxidase and protein oxidation in the airways of young children with cystic fibrosis.

Cystic fibrosis (CF) is characterized by considerable oxidative stress. However, it is not known whether oxidative stress is an important feature early in this disease. We have investigated a group of infants and young children with CF to establish whether oxidants are produced in their airways. Bronchoalveolar lavage fluid (BALF) was assayed for myeloperoxidase as a measure of neutrophilic inflammation, and 3-chlorotyrosine as a biomarker of the potent oxidant hypochlorous acid, which is formed by myeloperoxidase. Protein carbonyls were also measured as a nonspecific indicator of reactive oxidant production. Myeloperoxidase and 3-chlorotyrosine levels in BALF from children with CF were 10- and fivefold higher, respectively, than in disease control subjects. There was a strong correlation between myeloperoxidase and 3-chlorotyrosine. Myeloperoxidase levels were fourfold higher in children with infections in their airways. Median protein carbonyls were elevated by only twofold compared with disease control subjects, but some children had extremely high levels of protein oxidation. We conclude that hypochlorous acid is produced early in CF and that it is a candidate for precipitating the fatal decline in lung function associated with this disease. Also, there must be other sourcesof oxidants because protein carbonyls were not related to either inflammation or infection.

Bronchoalveolar Lavage Fluid↗

Elevated plasma levels of F2 alpha isoprostane in cystic fibrosis.

Cystic fibrosis (CF) is associated with chronic lung infection, inflammation, and elevated indices of oxidative stress. Recently, isoprostanes were shown to be a reliable in vivo marker of oxidant injury with 8-iso-PGF2 alpha, shown to cause airflow obstruction and plasma exudation in guinea pig lung. The present study was designed to examine the relationship between 8-iso-PGF2 alpha levels, plasma antioxidants, and clinical status in CF. We hypothesized that plasma 8-iso-PGF2 alpha levels would be higher in subjects with CF compared to healthy controls. Plasma 8-iso-PGF2 alpha levels were prospectively measured in 22 subjects with CF and nine healthy controls using an 8-isoprostane enzyme immunoassay kit along with plasma vitamins A, E, and beta-carotene. Plasma 8-iso-PGF2 alpha levels were shown to be significantly elevated in the CF subjects compared to controls (319.6 +/- 52.6 vs. 145.0 +/- 21.0 pg/mL, P = 0.005). Plasma levels of antioxidants were significantly lower for the CF subjects compared to the controls (vitamin A, P < 0.003; vitamin E, P < 0.001; and beta-carotene, P < 0.01). This study confirms significantly elevated lipid peroxidation in CF using 8-iso-PGF2 alpha levels.

Adolescent↗

Drug management of noninfective complications of cystic fibrosis.

Cystic fibrosis (CF) is the commonest lethal hereditary disease in Caucasians. The disease involves a gene mutation located at the long arm of chromosome 7, and more than 300 mutations have been identified. CF is a systemic illness affecting the upper respiratory tract and airways, sweat and salivary glands, pancreas, gastrointestinal tract, liver and male reproductive system. The course is highly variable depending on the specific molecular abnormalities in the mutant gene. The current approach to therapy now involves the use of: (i) chest physiotherapy; (ii) bronchodilators when there is evidence of airways hyperreactivity; (iii) oral and intravenous antibiotics for acute pulmonary exacerbations and aerosolised antibiotics for prevention; (iv) recombinant human deoxyribonuclease I (dornase alfa) to promote airways clearance; (v) amiloride to improve sputum viscosity; (vi) pancreatic enzyme replacement therapy along with nutritional support and supplements; (vi) vitamins; and (vii) ursodeoxycholic acid in selected patients. The use of antiprotease and anti-inflammatory agents has been shown to be useful in preventing the damage secondary to chronic lung infection. In patients with severely impaired lung function, lung transplantations have been performed with good results. Finally, it seems probable that lung disease in CF patients will be ameliorated or prevented in the future with early gene therapy, using vectors such as recombinant adenoviruses, adeno-associated virus, lipofection or retrovirus. However, this require extensive basic and clinical research.

Cystic Fibrosis↗

New insights into the pathogenesis of cystic fibrosis.

Cystic fibrosis (CF) is the most frequent inheritable disease with a lethal course during childhood. The characteristic high viscosity of the mucoid secretion products in the lungs, pancreas, and gut cause plugging and secondary damage of these organs. In the past 20 years effective treatment of intestinal obstruction in the neonatal period and the infections of the lungs has improved the prognosis significantly. Many patients will reach adulthood in the near future. In the past 10 years new insights into the cause of the disease changed diagnostic procedures and, it is to be hoped, soon also treatment. The first development was the estimation of brush-border enzymes in amniotic fluid. With this method prenatal diagnosis is possible in the 17th-18th week of pregnancy. The recent discovery of the gene on chromosome 7 and its structure is the most important breakthrough. At the same time the process of Cl- transport across the mucosal membrane of many types of epithelium was subject to investigation by several laboratories. We have studied the transport of ions in the small and large intestines of CF patients. The effect of all three types of intracellular signal transfer is abnormal, although the second messengers themselves (cAMP, cGMP, and Ca2+) are present. Evidence is found for K+ instead of Cl- secretion after addition of secretagogues.

Biological Transport↗

Pulmonary surfactant, lung function, and endobronchial inflammation in cystic fibrosis.

Cystic fibrosis (CF) lung disease is primarily a disease of the small airways. We hypothesized that even in patients with normal lung function, a reduced surfactant function would be present and favor small airway obstruction. Bronchoalveolar lavages from 76 patients with CF (5-31 years, median 11) with well-conserved lung function (FEV1 94% predicted, range 78-121) and from 10 healthy control subjects were investigated. The deviation of the biophysical surfactant performance from normal, assessed in a bubble surfactometer, was small; however, the ability of the surfactant to maintain the patency of a narrow airway (% open) was significantly reduced. Surfactant protein (SP)-C level was increased, SP-B and SP-D were unchanged, whereas SP-A was decreased. Among the patients with CF, neutrophilic inflammation was modestly related to a poorer surfactant activity, but not to lung function. SP-D was reduced in proportion to the degree of inflammation and in the presence of bacteria. These findings in a large cohort of patients with CF with normal lung function show that the endobronchial airway inflammation is linked to early perturbations of the biophysical properties and immunologic components of pulmonary surfactant and opens fields for novel therapeutic interventions.

Adolescent↗

The 3849 + 10 kB C-->T mutation in a 21-year-old patient with cystic fibrosis.

Cystic fibrosis (CF) is the most common lethal inherited disease in the white population. It is characterized by exocrine gland epithelia dysfunction, which leads to pulmonary and pancreatic insufficiency. Since the cloning of the CF gene in 1989 and the identification of the most common CF mutation (delta F508), more than 400 different mutations have been described. These mutations appear to contribute to the heterogeneity of the CF phenotype and several reports have speculated on the relationship between the most common CF mutations and the patient's clinical status. We report the case of a 21-year-old woman with longstanding chronic pansinusitis, nasal polyposis, chronic cough and severe nasal crusting. During a period of five years she had been followed by her otolaryngologist and pediatric pulmonologist. Sweat tests performed at the age of 17 and 18 were within normal limits and she underwent repeated conventional sinonasal procedures, with no improvement in her clinical status. On her present admission, sweat tests showed a 70 meq/l chloride concentration. The diagnosis of CF was then confirmed by DNA analysis and the patient was found to carry the 3849 + 10 kB C-->T mutation. The early detection of this newly recognized form of CF in adults as well as in children presenting with sinonasal symptoms is critical for life expectancy and quality.

Adult↗

Systemic deficiency of glutathione in cystic fibrosis.

Cystic fibrosis (CF), a disorder characterized by mutations of the CF transmembrane regulator gene, is characterized in the lung by chronic inflammation, leading to progressive damage to the airway epithelium, bronchiectasis, and chronic obstructive lung disease. One process contributing to the airway derangement is the chronic burden of oxidants released by inflammatory cells on the respiratory epithelial surface. With this background, we hypothesized that glutathione in respiratory epithelial lining fluid (ELF) in CF patients might be oxidized and/or diminished in amount compared with that in normal subjects. Recovery of ELF by bronchoalveolar lavage from young adults with CF (n = 21) and normal subjects (n = 25) demonstrated marked neutrophil-dominated inflammation in ELF in CF patients. As predicted, ELF in CF patients was characterized by a deficiency of glutathione (P < 0.001), but this was secondary to a reduction in reduced glutathione (P < 0.001), inasmuch as there were no differences in ELF levels of oxidized glutathione (P > 0.2). Unexpectedly, there was also a marked deficiency of reduced glutathione in plasma (P < 0.02); i.e., the glutathione "deficiency" observed in ELF in CF patients is not limited to the site of the inflammation but is systemic. Although the etiology of this generalized deficiency of extracellular glutathione is unknown, it is important in considering options for treating the concomitant and devastating lung pathology in this disorder.

Adult↗