Cell calcium levels of normal and cystic fibrosis nasal epithelium

To determine whether epithelial ion transport abnormalities in cystic fibrosis (CF) might reflect abnormal regulation of intracellular Ca2+ levels, cytosolic free calcium (Cai2+) was measured using fura-2 or quin2 in suspensions of normal or CF nasal epithelial cells derived from primary cell culture. The basal Cai2+ level measured with fura-2 in CF nasal epithelia was 155 +/- 9 nM (n = 5), a value not significantly different from normal nasal epithelia (143 +/- 16 nM, n = 5). Total cell calcium was measured by atomic absorption spectroscopy and no differences were observed between CF (6.3 +/- 0.5 nmol/mg protein; n = 3) and normal (6.2 +/- 1.2 nmol/mg protein; n = 3) nasal epithelial cells. Placing Na+ loaded cells in a low (10 mM) extracellular Na+ solution resulted in a rapid increase in Cai2+ consistent with Ca2+ uptake via a plasmalemmal Na+-Ca2+ exchanger. The level of Cai2+ achieved by this low Na+ maneuver was not significantly different in CF cells compared to normal cells. Neither isoproterenol (10(-5) M) nor forskolin (10(-6) M) had any effect on Cai2+ in normal or CF nasal epithelial cells. Thus, it appears that differences in cell Cai2+, as measured by fluorescent chelators in suspensions of cultured cells, do not account for the abnormalities in basal or isoproterenol stimulated ion transport in CF tissues.     

Increased nasal potential difference and amiloride sensitivity in neonates with cystic fibrosis

Patients with cystic fibrosis (CF) have an increased nasal transepithelial potential difference (PD) which reflects increased sodium absorption across epithelium relatively impermeable to chloride. To evaluate nasal epithelial function in neonates with CF, the PD was recorded and the voltage response to superfusion of 10(-5M) amiloride, an inhibitor of sodium transport, measured between a Ringer perfused bridge on the nasal mucosa and a reference electrode in the subcutaneous space. We studied three neonates with CF with meconium ileus and compared the results with those in 24 term healthy neonates, including one obligate heterozygote for CF, and 27 control neonates with disease. All three CF neonates had raised sweat chloride values (mean 100 mEq/L) at 2 months. The CF neonates had higher PDs (-64.0 +/- 8.4 mV) than those in normal (-24.4 +/- 2.0 mV) or control (-25.8 +/- 2.0 mV) neonates. Superfusion with amiloride induced a 72% reduction in PD in the CF neonates as compared with healthy (37.5 +/- 1.0%) and diseased (36.0 +/- 1.3%) neonates. The PD and amiloride response in CF neonates are similar to those in CF infants (2.24 months), older CF children (greater than 6 years), and CF adults (-64.9 +/- 9.3 mV; 77.7 +/- 1.8%, n = 51). These results suggest that (1) nasal epithelial dysfunction is present in patients with CF shortly after birth, and (2) the nasal PD may be a diagnostic adjunct to the sweat test in the early diagnosis of CF.     

Oxygen free radicals and antioxidants in cystic fibrosis: the concept of an oxidant-antioxidant imbalance

Patients with cystic fibrosis frequently exhibit increased oxygen free radical generation from activated neutrophils due to chronic lung inflammation on the one hand and antioxidant deficiencies due to exocrine pancreatic insufficiency on the other, resulting in an oxidant–antioxidant imbalance in favor of the former. As a consequence, free radical attack on unsaturated fatty acids of lipid structures leading to lipid peroxidation and damaging effects on proteins may occur. In the lung, antiproteases are thought to be inactivated by oxygen free radicals released from inflammatory cells. In the cholestatic liver, bile acids may propagate lipid peroxidation. An efficient antioxidant supply is suggested to control tissue injury by restoring the oxidant-antioxidant balance. Mechanisms involved in the generation of oxygen free radicals are described and data on the antioxidant defense system in cystic fibrosis patients are presented, together with evidence of increased lipid peroxidation. Possible implications for disease processes are discussed as well as therapeutic concepts to reconstitute the oxidant-antioxidant balance.     

RSV mediates Pseudomonas aeruginosa binding to cystic fibrosis and normal epithelial cells

Cystic fibrosis lung disease typically has a course of exacerbations and remissions, suggesting that external factors like viral infections can influence this course. Clinical data suggest synergism between respiratory syncytial virus (RSV) infections and Pseudomonas aeruginosa in cystic fibrosis (CF) lung disease. We studied the influence of RSV infection on adherence of P. aeruginosa to IB3-1, HEp-2, and A549 epithelial cell monolayers in vitro. RSV infection of epithelial cells as well as simultaneous addition of RSV and P. aeruginosa to noninfected cells both strongly enhanced the pseudomonal adherence to epithelial cells. The increased adherence varied from 1.2- to 8.2-fold in case of previous RSV infection, and from 1.7- to 16.1-fold in case of simultaneous addition. We observed direct binding of RSV to P. aeruginosa, and blocking of RSV with heparin eliminated the effect on increased adherence. This suggests that RSV possibly acts as a coupling agent between P. aeruginosa and epithelial cells. In conclusion, RSV enhances P. aeruginosa infection of respiratory epithelial cells. It suggests a role of specific viral-bacterial interactions in exacerbations of CF lung disease, which could have important implications on prevention and treatment.     

Using computer based data acquisition and analysis system for nasal potential difference measurement in cystic fibrosis

Nasal potential difference (PD) measurement has been used as a diagnostic test for cystic fibrosis (CF). It has been shown that large differences in reproducibility of nasal PD measurement can exist between different study sites. These differences reduce the validity of studies. In our study we tried to measure nasal PD values for a group of Turkish CF patients by using a computer based data acquisition system, which could eliminate the bias due to using different voltmeters. The CF group (n=40, mean age 9.3 years) value was -39.21+/-1.74 mV, and the control group (n=36, mean age 17.08 years) value was -18.24+/-1.48 mV (mean+/-SEM). Using the electronic data acquisition and analysis systems gave reliable results with high specificity (92%), sensitivity (79%), positive predictive value (95%) and negative predictive value (72%). Computer based data acquisition and analysis system provides suitable monitoring and continuous recording during measurements and facilitates repeat readings at the same distances along the nasal floor. Using electronic data acquisition may help to minimize the subjectivity in voltmeter measurements and hand analysis.     

Osteoporosis in cystic fibrosis

To determine if osteoporosis is prevalent among patients with cystic fibrosis, we compared the vertebral bone density measured by quantitative computed tomography in 57 such patients (29 male, 28 female, aged 3 to 21 years) with those of an age-, race-, and sex-matched control group of 57 healthy subjects. Patients with cystic fibrosis had significantly lower bone density (10% lower, p less than 0.001) than in controls. The decrease in bone density in patients with cystic fibrosis was unrelated to age. Shwachman clinical evaluation scores (based on case history, pulmonary physical findings, growth, and x-ray findings) correlated positively with age-standardized bone density values (p less than 0.01). Male patients had substantially lower bone density than did female patients (p less than 0.02), but bone density differences related to gender were not significant when effects of disease severity were controlled for. Decreased bone density was more common in patients with poor nutritional status as determined by anthropometric measurements (p less than 0.05). We conclude that osteoporosis is a frequent complication in children with cystic fibrosis regardless of their age and is more prevalent in patients with greater disease severity.     

Pneumonectomy in cystic fibrosis

We present the case of a 13-year-old boy with cystic fibrosis (CF) who developed severe right-sided lung infection with formation of abscess and localized bronchiectasis. The boy's lung disease was complicated by nephrotic syndrome and secondary amyloidosis. Unilateral pneumonectomy was performed, producing significant clinical improvement with a remarkable increase in quality of life which has lasted to the present date, 15 years later. Most patients with CF develop lung disease, which is the main cause of adult mortality in this population. Lung transplantation is currently considered the treatment of choice in severe bilateral lung disease in CF. However, in severe unilateral lung disease such as localized bronchiectasis, surgical resection of the affected lobe or lung is still a worthwhile option as a rescue therapy for patients who are at high risk of dying while waiting for lung transplantation.     

Complement in cystic fibrosis

Quantitative and functional assessments were made of both the classical and alternative pathways of complement activation in sera from 23 patients with cystic fibrosis. The classical pathway functioned similarly in patients and controls as measured by CH50 titre. Alternative pathway function, initiated in patient sera by incubation with inulin, was equal to that of controls as determined by cleavage of Factor B and C3, and by the consumption of terminal components. Factor B, however, was more readily activated in patient than in control sera. This rapid alteration of Factor B did not lead to accelerated or more extensive activation of the terminal complement components via the alternative pathway when assessed by C3 cleavage and the consumption of terminal components. Thus, a complement deficiency was not found. The importance of the easily activated Factor B is undefined.     

Mucolytics in cystic fibrosis

Mucus accumulation in the lower airways is a key feature of cystic fibrosis (CF) lung disease. The major component of mucus in CF is not mucin derived from mucus producing cells but rather pus that includes viscous material such as polymerized DNA derived from degraded neutrophils. This has important implications for mucolytic therapy aiming to improve mucus clearance from the airways, since degradation of mucin may not be a suitable treatment strategy. In addition, thinning of secretions may not always be beneficial, since it may negatively affect certain aspects of mucus transport such as cough clearance. While inhaled N-acetylcysteine has been used as a mucolytic drug in CF for decades, there is little evidence that it has any beneficial effect. Dornase alfa has been shown to reduce pulmonary exacerbations and improve lung function and is currently the only mucolytic agent with proven efficacy in CF. Newer agents targeting other components of CF mucus, such as filamentous actin, are currently in development. Ultimately, drugs that are mucokinetic, which preserve viscoelasticity, rather than mucolytic may prove to be beneficial for CF lung disease in the future.     

Complement in cystic fibrosis

Complement components C3, C4, and C3A were estimated in 30 patients with cystic fibrosis aged 1 to 21 years (MF=1614) and were compared with results in 40 healthy, age-matched subjects. The influences of the clinical score, sputum microbiology, and the patients' sex were also investigated. In contrast to most previous communications, this paper shows that, compared to the control group, a significant decrease of C3 (P<0.001) and C4 (P<0.02) was observed whereas C3A levels were not altered. There were no increases in complement. Shwachman-scores above or below 70 did not influence the complement levels, nor did exacerbations of the disease change the levels. No influence of the patients' sex could be shown. Pseudomonas aer. in the sputum was clearly associated with complement defects (14/18). Alternative-pathway involvement of complement activation could be demonstrated in 32%. The results make complement activation due to pulmonary infection most likely. The defects observed probably represent secondary changes.Presented at the VIIth Annual Meeting of the European Working Group for Cystic Fibrosis, Dresden, June 20–21, 1977Dedicated to Professor E. Zweymüller on the occasion of his 60th birtday     

Tuberculosis and cystic fibrosis

Mycobacterial infections are rarely reported in Cystic Fibrosis patients although they quite often develop predisposing risk factors such as underweight, secondary diabetes mellitus and chronic inflammatory pulmonary disease. Furthermore glucocorticoid therapy is mandatory in some patients. CF heterozygotes are said to have a selective advantage due to an increased host resistance against Mycobacterium tuberculosis. In this survey 1926 CF patients were investigated for the incidence of tuberculin conversion and manifest infection with mycobacterium tuberculosis in the Federal Republic of Germany (FRG). The results do not support the hypothesis of increased host resistance nor do they show any evidence of a higher risk for tuberculosis in CF. Implications for prophylactic, diagnostic and therapeutic measures are discussed in accordance to the recent epidemiologic data of tuberculosis in the FRG.