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Digitoxin mimics gene therapy with CFTR and suppresses hypersecretion of IL-8 from cystic fibrosis lung epithelial cells.

Cystic fibrosis (CF) is a fatal, autosomal, recessive genetic disease that is characterized by profound lung inflammation. The inflammatory process is believed to be caused by massive overproduction of the proinflammatory protein IL-8, and the high levels of IL-8 in the CF lung are therefore believed to be the central mechanism behind CF lung pathophysiology. We show here that digitoxin, at sub nM concentrations, can suppress hypersecretion of IL-8 from cultured CF lung epithelial cells. Certain other cardiac glycosides are also active but with much less potency. The specific mechanism of digitoxin action is to block phosphorylation of the inhibitor of NF-kappa B (I kappa B alpha). I kappa B alpha phosphorylation is a required step in the activation of the NF-kappa B signaling pathway and the subsequent expression of IL-8. Digitoxin also has effects on global gene expression in CF cells. Of the informative genes expressed by the CF epithelial cell line IB-3, 58 are significantly (P < 0.05) affected by gene therapy with wild-type (CFTR CF transmembrane conductance regulator). Of these 58 genes, 36 (62%) are similarly affected by digitoxin and related active analogues. We interpret this result to suggest that digitoxin can also partially mimic the genomic consequences of gene therapy with CF transmembrane conductance regulator. We therefore suggest that digitoxin, with its lengthy history of human use, deserves consideration as a candidate drug for suppressing IL-8-dependent lung inflammation in CF.

Cardiac Glycosides↗

Activity of fucosyltransferases and altered glycosylation in cystic fibrosis airway epithelial cells.

Cystic fibrosis (CF) glycoconjugates have a glycosylation phenotype of increased fucosylation and/or decreased sialylation when compared with non-CF. A major increase in fucosyl residues linked alpha 1,3 to antennary GlcNAc was observed when surface membrane glycoproteins of CF airway epithelial cells were compared to those of non-CF airway cells. Importantly, the increase in the fucosyl residues was reversed with transfection of CF cells with wild type CFTR cDNA under conditions which brought about a functional correction of the Cl(-) channel defect in the CF cells. In contrast, examination of fucosyl residues in alpha 1,2 linkage by a specific alpha 1,2 fucosidase showed that cell surface glycoproteins of the non-CF cells had a higher percentage of fucose in alpha 1,2 linkage than the CF cells. Airway epithelial cells in primary culture had a similar reciprocal relationship of alpha 1,2- and alpha 1,3-fucosylation when CF and non-CF surface membrane glycoconjugates were compared. In striking contrast, the enzyme activity and the mRNA of alpha 1,2 fucosyltransferase did not reflect the difference in glycoconjugates observed between the CF and non-CF cells. We hypothesize that mutated CFTR may cause faulty compartmentalization in the Golgi so that the nascent glycoproteins encounter alpha 1,3FucT before either the sialyl- or alpha 1,2 fucosyltransferases. In subsequent compartments, little or no terminal glycosylation can take place since the sialyl- or alpha 1,2 fucosyltransferases are unable to utilize a substrate, which is fucosylated in alpha 1,3 position on antennary GlcNAc. This hypothesis, if proven correct, could account for the CF glycophenotype.

Bronchi↗

Effect of IBMX and alkaline phosphatase inhibitors on Cl- secretion in G551D cystic fibrosis mutant mice.

Some cystic fibrosis transmembrane conductance regulator (CFTR) mutations, such as G551D, result in a correctly localized Cl- channel at the cell apical membrane, albeit with markedly reduced function. Patch-clamp studies have indicated that both phosphatase inhibitors and 3-isobutyl-1-methylxanthine (IBMX) can induce Cl- secretion through the G551D mutant protein. We have now assessed whether these agents can induce Cl- secretion in cftrG551D mutant mice. No induction of Cl- secretion was seen with the alkaline phosphatase inhibitors bromotetramisole or levamisole in either the respiratory or intestinal tracts of wild-type or cftrG551D mice. In contrast, in G551D intestinal tissues, IBMX was able to produce a small CFTR-related secretory response [means +/- SE: jejunum, 1.8 +/- 0.9 microA/cm2, n = 7; cecum, 3.7 +/- 0.8 microA/cm2, n = 7; rectum (in vivo), 1.9 +/- 0.9 mV, n = 5]. This was approximately one order of magnitude less than the wild-type response to this agent and, in the cecum, was significantly greater than that seen in null mice (cftrUNC). In the trachea, IBMX produced a transient Cl- secretory response (37.3 +/- 14.7 microA/cm2, n = 6) of a magnitude similar to that seen in wild-type mice (33.7 +/- 4.7 microA/cm2, n = 9). This response was also present in null mice and therefore is likely to be independent of CFTR. No effect of IBMX on Cl- secretion was seen in the nasal epithelium of cftrG551D mice. We conclude that IBMX is able to induce detectable levels of CFTR-related Cl- secretion in the intestinal tract but not the respiratory tract through the G551D mutant protein.

1-Methyl-3-isobutylxanthine↗

A 32-bp deletion (2991del32) in the cystic fibrosis gene associated with CFTR mRNA reduction.

Cystic fibrosis, a common recessive disorder of exocrine glands, is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. We describe the identification of a 32-bp deletion within the coding region of CFTR that involves the nucleotides 2991-3022 in exon 15 (2991del32). This unusual frameshift mutation was confirmed in three unrelated German families, accounting for a frequency of 0.3% in 1,028 CF chromosomes. All identified patients are compound heterozygotes for 2991del32 and for the most frequent cystic fibrosis mutation, delta F508. The evaluation of clinical data revealed typical symptoms of cystic fibrosis, including pancreatic insufficiency, in all three index cases. To characterize further the mutation in the CFTR transcript, we analysed RNA from lymphocytes by reverse transcription and PCR amplification. 2991del32 transcripts were detectable neither in the RNA sample from a patient compound heterozygous delta F508/2991del32 nor in the parental sample heterozygous wild-type/2991del32. These data indicate that the 32-bp deletion causes a pancreas insufficient cystic fibrosis phenotype by a severe reduction of CFTR mRNA.

Adolescent↗

Contribution of genetic factors other than CFTR to disease severity in cystic fibrosis.

BACKGROUND: Disease severity in patients with cystic fibrosis shows marked variability. Attempts to explain this phenotypic heterogeneity on the basis of CFTR genotype have had limited success. A study was undertaken to test the hypothesis that naturally occurring variants of the pro-inflammatory cytokine tumour necrosis factor alpha (TNF-alpha) and the detoxifying enzyme glutathione S-transferase M1 (GSTM1) could influence disease severity in cystic fibrosis. METHODS: Fifty-three children with cystic fibrosis were studied. To allow for the effect of age, all clinical details were collected during the eighth year of age. The subjects were divided into groups, both according to the presence or absence of the TNF2 TNF-alpha -308 promoter polymorphism (n = 20), and by homozygosity for the null allele of GSTM1 (n = 26). RESULTS: Percentage predicted forced expiratory volume in one second (FEV1) and weight z scores were significantly lower in the TNF2 group (mean difference (95% confidence intervals) for FEV1 11.6% (1.7 to 21.5) and 0.59 (0.06 to 1.12) for weight z score). The Chrispin-Norman chest radiographic score was significantly higher and the Shwachman score was significantly lower in patients homozygous for the GSTM1 null allele. CONCLUSIONS: Two independent genetic factors have been identified which appear to influence disease severity in cystic fibrosis. These results support the contention that inflammation in cystic fibrosis contributes to tissue damage. Isolation of further such factors may lead to identification of patients at risk of more severe disease and allow targeted aggressive therapy in this group.

Alleles↗

Maldigestion and malabsorption of 13C labelled tripalmitin in gastrostomy-fed patients with cystic fibrosis.

BACKGROUND & AIMS: Some patients with cystic fibrosis continue to have excessive losses of stool lipid, despite the use of pancreatic enzyme replacement therapy to improve digestion. The aim of this study was to explore the residual capacity of the gastrointestinal tract to digest and absorb dietary lipid using stable isotopic methodology in ten patients with cystic fibrosis who were gastrostomy fed in comparison to eight healthy children. We sought to test the hypothesis that a reduction in the availability of dietary lipid may arise from malabsorption of the products of digestion, rather than maldigestion alone. METHODS: All subjects consumed [1,1,1-(13)C] tripalmitin (10mg/kg body weight) with a standardised meal but the patients with cystic fibrosis did not take their habitual pancreatic enzymes. Total enrichment of (13)C was measured by isotope ratio mass spectrometry in stools collected over 3 days. Maldigestion and malabsorption was differentiated by measuring (13)C-label excretion in stool triglyceride and fatty acid fractions, respectively. RESULTS: The patients with cystic fibrosis had elevated (13)C-label losses in total stools (56.7%, 6.8-77.9%)(median and range; % administered dose), triglyceride (6.6%, 0-31.2%) and fatty acid (16.7%, 3.4-50.3%) fractions compared to healthy children (1.9%, 0-10.9%, P<0.001; triglyceride: 0.2%, 0-0.6%, p<0.01; fatty acid 0.9%, 0-6.5%, P<0.001). CONCLUSIONS: These results highlight differences between gastrostomy fed patients with cystic fibrosis to both digest and absorb dietary lipid. There is a need to extend these observations and apply this approach to patients both with and without pancreatic enzyme replacement therapy.

Adolescent↗

Neuropathy and vasculopathy in colonic strictures from children with cystic fibrosis.

Colonic strictures are rare in patients who have cystic fibrosis, but recently have developed in those who have been treated with delayed-release high-dose pancreatic enzyme supplements. Colonic strictures from eight such pediatric patients showed neural abnormalities consisting of ganglion cell hyperplasia and ectopia, and intermyenteric plexus hyperplasia. Cholinergic and adrenergic stains of mucosal nerve fibers were more prominent in histological sections of the cystic fibrosis strictures than in sections from colons of children without cystic fibrosis. The mean grade of staining with acetylcholinesterase in the lamina propria of the strictured cystic fibrosis colons was 2.38 +/- 1.25, compared with .93 +/- .93 (P < .055) in bowels from children without cystic fibrosis. The mean grade for tyrosine hydroxylase staining in the lamina propria was 2 +/- .97 in the strictures and was .79 +/- .81 (P < .05) in the bowels of children who did not have cystic fibrosis. Vasoactive intestinal peptide staining in bowels from children with cystic fibrosis with and without stricture did not differ significantly from that of children without cystic fibrosis. Vasculopathy consisting of fibrointimal hyperplasia in submucosal veins and mesenteric arteries was found only in colonic strictures owing to cystic fibrosis. Colonic strictures in patients with cystic fibrosis who received high-dose pancreatic enzyme supplements contain ganglion cell abnormalities, and mucosal cholinergic and adrenergic activity may be increased in these strictures. The stricture vasculopathy may be drug-related and/or related to increased catecholamine activity.

Acetylcholinesterase↗

Analysis of risk factors for the development of liver disease associated with cystic fibrosis.

We prospectively screened for liver disease patients with cystic fibrosis who were more than 3 years of age and who were followed at the cystic fibrosis center of the University of Milan. From January 1991 to December 1992, we screened 189 patients; clinical, biochemical, and echographic abnormalities suggestive of overt liver disease were present in 34 (18%). To define risk factors for the development of liver disease associated with cystic fibrosis, we evaluated the possible role of specific mutations of the CFTR (cystic fibrosis transmembrane regulator) gene and of different clinical and demographic characteristics (sex, pancreatic status, meconium ileus or its equivalent) through a comparison of patients with cystic fibrosis and overt liver disease (n = 34) and those without liver disease (n = 155). Genetic analysis failed to reveal any significant difference in the allele frequencies of defined (delta F508, 1717-1G-A, G542X, N1303K, W1282X, R553X) and undefined mutations of the CFTR gene in the two groups of patients; genotype frequencies were also not significantly different. Pancreatic insufficiency was present in all patients with liver disease and in 87.3% of those without liver disease. A male predominance was found in the group with liver disease. The frequency of meconium ileus or its equivalent was significantly higher in patients with cystic fibrosis and liver disease (35.3%) than in patients without liver disease (12.3%) (p = 0.0025). In the 31 patients with a history of meconium ileus or its equivalent, the following hepatic abnormalities occurred more frequently than in the 155 patients with cystic fibrosis who did not have meconium ileus: hepatomegaly, biochemical abnormalities, heterogeneous echographic pattern of the liver, and microgallbladder. Twenty-four patients with a history of meconium ileus or its equivalent underwent hepatobiliary scintigraphy (with technetium-labeled iminodiacetic acid derivatives), which showed morphologic abnormalities suggestive of impaired biliary drainage in 21 patients and abnormalities in function in 11. The risk of acquiring liver disease was increased almost fourfold in patients with a history of meconium ileus or its equivalent, in comparison with patients who had cystic fibrosis but were unaffected by these complications (odds ratio, 3.9043; 95% confidence interval, 1.666 to 9.149). We conclude that patients with cystic fibrosis and meconium ileus or its equivalent may benefit from prophylactic treatment with ursodeoxycholic acid; genetic analysis of the major mutations present in this population failed to provide evidence of the existence of a specific genetic marker for the development of liver disease in patients with cystic fibrosis.

Adolescent↗

An update on cystic fibrosis and implications for anesthesia.

Cystic fibrosis is a recessive inherited disorder that affects about 30,000 Americans. The majority of infants born with cystic fibrosis now reach adulthood, making surgical procedures performed in this patient group more common. The disease is a heterogeneous disorder caused by widespread dysfunction of exocrine glands and involving salivary, sweat, digestive, and pulmonary secretions. The broad, variable, and sometimes confusing array of clinical manifestations of cystic fibrosis include obstructive pulmonary disease, pancreatic insufficiency, abnormally high sweat electrolyte concentrations, nasal polyps, infertility, and pansinusitis. In this article, the epidemiology, genetics, and pathophysiology of the disease are outlined briefly. Preoperative assessment is reviewed, and guidelines are submitted regarding anesthetic management.

Anesthesia↗

Evidence against the acidification hypothesis in cystic fibrosis.

The pleiotropic effects of cystic fibrosis (CF) result from the mislocalization or inactivity of an apical membrane chloride channel, the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR may also modulate intracellular chloride conductances and thus affect organelle pH. To test the role of CFTR in organelle pH regulation, we developed a model system to selectively perturb the pH of a subset of acidified compartments in polarized cells and determined the effects on various protein trafficking steps. We then tested whether these effects were observed in cells lacking wild-type CFTR and whether reintroduction of CFTR affected trafficking in these cells. Our model system involves adenovirus-mediated expression of the influenza virus M2 protein, an acid-activated ion channel. M2 expression selectively slows traffic through the trans-Golgi network (TGN) and apical endocytic compartments in polarized Madin-Darby canine kidney (MDCK) cells. Expression of M2 or treatment with other pH perturbants also slowed protein traffic in the CF cell line CFPAC, suggesting that the TGN in this cell line is normally acidified. Expression of functional CFTR had no effect on traffic and failed to rescue the effect of M2. Our results argue against a role for CFTR in the regulation of organelle pH and protein trafficking in epithelial cells.

Acids↗

Chest physiotherapy compared to no chest physiotherapy for cystic fibrosis.

BACKGROUND: Chest physiotherapy is widely used in patients with cystic fibrosis in order to clear mucus from the airways. OBJECTIVES: To determine the effectiveness and acceptability of chest physiotherapy compared to no treatment or spontaneous cough alone to improve mucus clearance in cystic fibrosis. SEARCH STRATEGY: Relevant trials are identified in the Cochrane Cystic Fibrosis and Genetic Disorders Group Specialised Register of Controlled Trials. This register was compiled by conducting computerised searches of Medline from 1966 to present and from Embase from 1974 to 1995. The register of randomised controlled trials is updated every three months. Unpublished work has been identified by searching through the abstract books of the three major cystic fibrosis conferences; the International Cystic Fibrosis Conference: the European Cystic Fibrosis Conference and the North American Cystic Fibrosis Conference. Date of the most recent search of the Group's specialised register: November 1999. SELECTION CRITERIA: Randomised or quasi-randomised clinical trials in which a form of chest physiotherapy (airway clearance technique) were taken for consideration in patients with cystic fibrosis compared with either no physiotherapy treatment or spontaneous cough alone. DATA COLLECTION AND ANALYSIS: There were no randomised controlled trials or cross over trials eligible for inclusion in the review. MAIN RESULTS: There were no randomised controlled trials or cross over trials eligible for inclusion in the review. REVIEWER'S CONCLUSIONS: Short-term crossover trials, which had to be excluded from this review, suggest that airway clearance regimens could have beneficial effects in patients with cystic fibrosis. However based on this review there is currently no robust scientific evidence to support the hypothesis that chest physiotherapy for the purpose of clearing airway secretions has a beneficial effect in patients with cystic fibrosis.

Cystic Fibrosis↗

Relationships among digital clubbing, disease severity, and serum prostaglandins F2alpha and E concentrations in cystic fibrosis patients.

Nine patients with cystic fibrosis but without digital clubbing (Group A) were matched, prospectively, by sex and approximate age to 9 cystic fibrosis patients with digital clubbing (Group B) and to 9 normal persons (control subjects). Patients in Group B had significantly (P less than 0.05) lower clinical scores and forced vital capacity than did those in Group A, indicating more severe pulmonary disease in the former; however, other spirometer tests of pulmonary function revealed no differences between Groups A and B. The degree of digital clubbing had significant (P less than 0.05) linear relationships to forced vital capacity (r = -0.73) and clinical scores (r = 0.853) for Groups A and B. Plasma concentrations of prostaglandins F2alpha and E were significantly increased (P less than 0.05) in both Group A (X +/- SE, 0.48 +/- 0.03 and 0.87 +/- 0.10 ng per ml, respectively) and Group B (X +/- SE, 0.68 +/- 0.04 and 1.81 +/- 0.16 ng per ml, respectively) compared to the control group (X +/- SE, 0.14 +/- 0.01 and 0.39 +/- 0.02 ng per ml, respectively). Group B had significantly larger concentrations than did Group A; however, plasma concentrations of prostaglandin 15-keto-13, 14-dihydro metabolite were not different in Groups A and B, and were significantly smaller than in the control group. These studies suggest that the degree of digital clubbing in cystic fibrosis is related to the severity of the pulmonary involvement and that the prostaglandin system may play an important role in this disease.

Adolescent↗

Neonatal cholestasis as the presenting feature in cystic fibrosis.

Between 1960 and 1994 cystic fibrosis was found in nine out of 1474 infants investigated for neonatal cholestasis. Four had delay in passing meconium. In all patients cholestatic jaundice was present during the first 48 hours and in three patients cholestasis was complete, mimicking biliary atresia. Serum cholesterol concentrations were normal in all but two children. Sweat chloride was repeatedly above 95 mmol/l in all instances. Three children had another condition enhancing the risk of cholestasis (alpha1-antitrypsin deficiency, hypopituitarism, perinatal asphyxia, and total parenteral nutrition). Liver histology displayed portal fibrosis and inflammation with bile duct proliferation; mucous plugs in bile ducts were observed in only one patient. Only one child died from cirrhosis. These results indicate that cystic fibrosis is not a major cause of neonatal cholestasis. However early signs of intestinal obstruction and low concentrations of serum cholesterol may indicate cystic fibrosis, regardless of liver histology. Neonatal cholestasis has no prognostic value concerning evolution to cirrhosis.

Cholestasis↗

Urolithiasis and cystic fibrosis.

PURPOSE: We determined whether cystic fibrosis patients are at increased risk for the development of urolithiasis. MATERIALS AND METHODS: Telephone interviews were conducted with 201 cystic fibrosis patients older than 15 years to identify those with a history of urolithiasis. Histories were confirmed by chart review, and only patients with urolithiasis documented by excretory urography, renal ultrasound or spontaneous passage of a stone were included. RESULTS: A total of 11 patients (5.5%) had documented urolithiasis, with 2 or more episodes in 7. Mean age at initial episode was 27.0 years (range 19 to 33). CONCLUSIONS: Cystic fibrosis patients may be at increased risk for urolithiasis compared to age-specific prevalence rates for stone disease in the general population.

Adult↗

[Anomalies of the sperm, vas deferens and epididymis in cystic fibrosis].

Ten adult patients with cystic fibrosis presented with lesions of the genital tract at different levels. Bilateral lesions of the vas deferens were constant and resulted in azoospermia in 9 cases; the fertile patient had a son. The sperm of these 10 patients was compared to that of 5 adult controls. A decrease in sperm volume, pH and fructose and an increase in citric acid and acid phosphatase were observed in the cystic fibrosis group. It is concluded that all subjects with azoospermia should be investigated for cystic fibrosis by means of the sweat test.

Adolescent↗

Pregnancy in patients with cystic fibrosis.

As more patients with cystic fibrosis reach adulthood, questions arise about the potential hazards of pregnancy. We reviewed the medical records of eight women with cystic fibrosis who had a total of 11 completed pregnancies and had been evaluated within 1 year before conception. In five women (Group 1), the overall maternal condition was little affected by the pregnancy, and in three women (Group 2), the mother's condition deteriorated during and after pregnancy and did not return to the pregravid state. With regard to pregravid status, significant differences between patients in Group 1 and Group 2 were found in Shwachman-Kulczycki clinical scores, weight for height values, Brasfield chest radiograph scores, and pulmonary function. A quantitative assessment of pregravid nutritional and pulmonary status is useful in counseling women with cystic fibrosis about the risk of pregnancy.

Adolescent↗

Independent genetic determinants of pancreatic and pulmonary status in cystic fibrosis.

The concordance of pancreatic and pulmonary status among siblings with cystic fibrosis, the cystic fibrosis genotype, and non-genetic factors were analysed in adult patients with cystic fibrosis. Genetic factors were more important than non-genetic factors in affecting the severity of pancreatic and lung disease. The genetic factors were independent of each other and did not invariably cosegregate with specific mutations at the cystic fibrosis locus.

Adult↗

Clinical implications of cystic fibrosis transmembrane conductance regulator mutations.

Cystic fibrosis (CF) phenotypes are determined by mutations in the CF gene, genetic background, and environment. The nature of the cystic fibrosis transmembrane conductance regulator (CFTR) mutation determines the extent of protein function. CFTR mutations that abolish protein function are associated with severe CF phenotypes. Mutants that retain partial function of CFTR are associated with mild phenotypes. The effect of CFTR dysfunction is variable in different tissues. Atypical phenotypes caused by mutations in the CF gene may be revealed by CFTR mutation analysis and family studies. These phenotypes help to define the spectrum of clinical manifestations caused by CFTR mutations.

Cystic Fibrosis↗