Malena Cohen-Cymberknoh

Managing Cystic Fibrosis Strategies That Increase Life Expectancy and Improve Quality of Life

The survival of patients with cystic fibrosis (CF) continues to improve. The discovery and cloning of the CFTR gene more than 21 years ago led to the identification of the structure and function of the CFTR chloride channel. New therapies based on the understanding of the function of CFTR are currently under development. The better clinical status and improved survival of patients with CF is not only a result of understanding of the molecular mechanisms of CF but also a result of the development of therapeutic strategies that are based on insights into the natural course of the disease. Current CF treatments that target respiratory infections, inflammation, mucociliary clearance, and nutritional status are associated with improved pulmonary function and reduced exacerbations. Patients benefit from treatment at a specialized CF center by a multidisciplinary dedicated team with emphasis being placed on frequent visits, periodic testing, and monitoring adherence to therapy. The purpose of this review is to survey recent developments in CF care that are responsible for the improved survival and quality of life of patients with CF.

Chronic ataluren (PTC124) treatment of nonsense mutation cystic fibrosis

In a subset of patients with cystic fibrosis (CF), nonsense mutations (premature stop codons) disrupt production of full-length, functional CF transmembrane conductance regulator (CFTR). Ataluren (PTC124) allows ribosomal readthrough of premature stop codons in mRNA. We evaluated drug activity and safety in patients with nonsense mutation CF who took ataluren three times daily (morning, midday and evening) for 12 weeks at either a lower dose (4, 4 and 8 mg·kg−1) or higher dose (10, 10 and 20 mg·kg−1). The study enrolled 19 patients (10 males and nine females aged 19–57 yrs; dose: lower 12, higher seven) with a classic CF phenotype, at least one CFTR nonsense mutation allele, and an abnormal nasal total chloride transport. Both ataluren doses were similarly active, improving total chloride transport with a combined mean change of -5.4 mV (p<0.001), and on-treatment responses (at least -5 mV improvement) and hyperpolarisations (values more electrically negative than -5 mV) in 61% (p<0.001) and 56% (p = 0.002) of patients. CFTR function was greater with time and was accompanied by trends toward improvements in pulmonary function and CF-related coughing. Adverse clinical and laboratory findings were uncommon and usually mild. Chronic ataluren administration produced time-dependent improvements in CFTR activity and clinical parameters with generally good tolerability.

Airway inflammation in cystic fibrosis: molecular mechanisms and clinical implications

Airway epithelial cells and immune cells participate in the inflammatory process responsible for much of the pathology found in the lung of patients with cystic fibrosis (CF). Intense bronchial neutrophilic inflammation and release of proteases and oxygen radicals perpetuate the vicious cycle and progressively damage the airways. In vitro studies suggest that CF transmembrane conductance regulator (CFTR)-deficient airway epithelial cells display signalling abnormalities and aberrant intracellular processes which lead to transcription of inflammatory mediators. Several transcription factors, especially nuclear factor-κB, are activated. In addition, the accumulation of abnormally processed CFTR in the endoplasmic reticulum results in unfolded protein responses that trigger ‘cell stress’ and apoptosis leading to dysregulation of the epithelial cells and innate immune function in the lung, resulting in exaggerated and ineffective airway inflammation. Measuring airway inflammation is crucial for initiating treatment and monitoring its effect. No inflammatory biomarker predictive for the clinical course of CF lung disease is currently known, although neutrophil elastase seems to correlate with lung function decline. CF animal models mimicking human lung disease may provide an important insight into the pathogenesis of lung inflammation in CF and identify new therapeutic targets.

CCDC65 mutation causes primary ciliary dyskinesia with normal ultrastructure and hyperkinetic cilia

Background Primary ciliary dyskinesia (PCD) is a genetic disorder characterized by impaired ciliary function, leading to chronic sinopulmonary disease. The genetic causes of PCD are still evolving, while the diagnosis is often dependent on finding a ciliary ultrastructural abnormality and immotile cilia. Here we report a novel gene associated with PCD but without ciliary ultrastructural abnormalities evident by transmission electron microscopy, but with dyskinetic cilia beating. Methods Genetic linkage analysis was performed in a family with a PCD subject. Gene expression was studied in Chlamydomonas reinhardtii and human airway epithelial cells, using RNA assays and immunostaining. The phenotypic effects of candidate gene mutations were determined in primary culture human tracheobronchial epithelial cells transduced with gene targeted shRNA sequences. Video-microscopy was used to evaluate cilia motion. Results A single novel mutation in CCDC65, which created a termination codon at position 293, was identified in a subject with typical clinical features of PCD. CCDC65, an orthologue of the Chlamydomonas nexin-dynein regulatory complex protein DRC2, was localized to the cilia of normal nasal epithelial cells but was absent in those from the proband. CCDC65 expression was up-regulated during ciliogenesis in cultured airway epithelial cells, as was DRC2 in C. reinhardtii following deflagellation. Nasal epithelial cells from the affected individual and CCDC65-specific shRNA transduced normal airway epithelial cells had stiff and dyskinetic cilia beating patterns compared to control cells. Moreover, Gas8, a nexin-dynein regulatory complex component previously identified to associate with CCDC65, was absent in airway cells from the PCD subject and CCDC65-silenced cells. Conclusion Mutation in CCDC65, a nexin-dynein regulatory complex member, resulted in a frameshift mutation and PCD. The affected individual had altered cilia beating patterns, and no detectable ultrastructural defects of the ciliary axoneme, emphasizing the role of the nexin-dynein regulatory complex and the limitations of certain methods for PCD diagnosis.

LRRC6 mutation causes primary ciliary dyskinesia with dynein arm defects.

Despite recent progress in defining the ciliome, the genetic basis for many cases of primary ciliary dyskinesia (PCD) remains elusive. We evaluated five children from two unrelated, consanguineous Palestinian families who had PCD with typical clinical features, reduced nasal nitric oxide concentrations, and absent dynein arms. Linkage analyses revealed a single common homozygous region on chromosome 8 and one candidate was conserved in organisms with motile cilia. Sequencing revealed a single novel mutation in LRRC6 (Leucine-rich repeat containing protein 6) that fit the model of autosomal recessive genetic transmission, leading to a change of a highly conserved amino acid from aspartic acid to histidine (Asp146His). LRRC6 was localized to the cytoplasm and was up-regulated during ciliogenesis in human airway epithelial cells in a Foxj1-dependent fashion. Nasal epithelial cells isolated from affected individuals and shRNA-mediated silencing in human airway epithelial cells, showed reduced LRRC6 expression, absent dynein arms, and slowed cilia beat frequency. Dynein arm proteins were either absent or mislocalized to the cytoplasm in airway epithelial cells from a primary ciliary dyskinesia subject. These findings suggest that LRRC6 plays a role in dynein arm assembly or trafficking and when mutated leads to primary ciliary dyskinesia with laterality defects.

18F-Fluorodeoxyglucose-PET/CT Imaging of Lungs in Patients With Cystic Fibrosis

BACKGROUND Airway inflammation plays a critical role in the progression of cystic fibrosis (CF) lung disease, and in the destruction of airways and lung parenchyma. Current methods to assess CF lung disease (BAL, spirometry, and high-resolution CT scanning), do not always accurately reflect actual disease states. Fluorodeoxyglucose (FDG)-PET scanning has been used previously to image infection and inflammation. In this study, we assessed the use of (18)F-FDG PET/CT scanning to evaluate and monitor lung inflammation and/or infection in patients with CF. METHODS PET/CT scans were performed in 20 patients with CF (age range, 14 to 54 years); 7 of 20 patients underwent repeat PET/CT scans during and after acute exacerbations. The results were compared with clinical information and with images from eight control subjects with no known lung disease. RESULTS Foci of enhanced activity were observed on FDG-PET scans of patients with CF but not those of control subjects. Higher focal activity (standardized uptake value, > 3.0) was seen during disease exacerbation and infection. Coregistered CT scan images assisted in the localization of PET foci and showed corresponding CT scan findings, with many additional findings on CT scans that were not seen on PET scans. Foci seen on high-intensity PET scans during exacerbations disappeared after antibiotic therapy and the resolution of exacerbation, while corresponding CT scan findings remained unchanged. CONCLUSIONS PET/CT imaging demonstrated the presence of foci of enhanced uptake that may reflect active focal infectious or inflammatory processes in the lungs. These foci can be cleared with antibiotic therapy. Further studies are needed to validate these results and to determine whether FDG-PET/CT scanning can predict the nature/severity of disease in patients with CF.

Differences in Disease Expression Between Primary Ciliary Dyskinesia and Cystic Fibrosis With and Without Pancreatic Insufficiency

BACKGROUND Impaired mucociliary clearance causes pulmonary disease in primary ciliary dyskinesia (PCD) and contributes to cystic fibrosis (CF) lung disease. Although the sinopulmonary disease is similar, morbidity and mortality are different. Both patients with PCD and patients with CF with pancreatic sufficiency (CF-PS) show no nutrient malabsorption and are diagnosed at a later age compared with patients with CF with pancreatic insufficiency (CF-PI). METHODS Clinical status, microbiology, FEV1, and high-resolution CT (HRCT) scans presented as total Brody score (CT-TBS) were compared for patients with PCD, CF-PI, and CF-PS, all treated at the same medical center, by the same team, and by a similar routine follow-up. RESULTS One hundred sixty-four patients, 34 with PCD, 88 with CF-PI, and 42 with CF-PS were enrolled. PCD was diagnosed at a similar age as CF-PS but significantly later than CF-PI. Mean FEV1 % predicted was similar for the three groups. The rate of FEV1 change with age in PCD was similar to CF-PS but significantly lower than in CF-PI. Severity of structural lung disease (CT-TBS) was similar for PCD and CF-PS and significantly higher in CF-PI. No correlation between TBS or Pseudomonas aeruginosa infection and FEV1 in PCD was seen, whereas a negative correlation with FEV1 was observed for both CF groups. CONCLUSIONS Although in our study PCD was similar to CF-PS, the lack of correlation between FEV1 and age, CT-TBS, and P aeruginosa infection in PCD suggests that impaired mucociliary clearance is not the only cause for inducing pulmonary damage in these diseases. Furthermore, a comparison of disease characteristics for PCD and CF should distinguish between CF-PI and CF-PS as different entities.

Meconium ileus in patients with cystic fibrosis is not a risk factor for clinical deterioration and survival: the Israeli Multicenter Study.

Objectives: Patients with cystic fibrosis (CF) presenting with meconium ileus (MI) tend to have worse outcomes than those without MI. We evaluated the clinical characteristics and survival rates among Israeli patients with CF with and without MI after a prolonged follow-up (15–30 years). Patients and Methods: A multicenter retrospective study. Forty-nine patients with CF, representing 13.8% of all patients with CF in Israel, presented with MI (current age 17.4 ± 7.9 years) between 1975 and 2006. They were compared with 38 patients with CF (current age 19.3 ± 6.5 years) without MI matched by sex and CF transmembrane conductance regulator mutation. Results: A total of 66.2% of patients with MI and 73.6% without MI were followed for a prolonged period (24.9 ± 2.7 years). Of the patients with MI, 31 were managed operatively, whereas 18 were treated successfully with gastrograffin enema, with similar clinical outcomes. Five patients in the MI group and 3 in the control group died during the study period. Bacterial colonization, z score of body mass index, and pulmonary function tests were similar in patients with and without MI in the long term. In younger patients, many clinical parameters were more prevalent in patients with MI (P = 0.004). However, these differences disappeared after the long-term follow-up (up to 31-years). Conclusions: Patients with CF presenting with MI had similar pulmonary function and nutritional status, as well as survival rates as did the control patients without MI. The distinct genetic mutation found in our population may explain in part the favorable results compared with other studies. In addition, it seems that early diagnosis and treatment of MI in patients with CF may be beneficial, subsequently lowering morbidity, and increasing survival.

Evaluation of the intestinal current measurement method as a diagnostic test for cystic fibrosis

The sweat test and nasal potential difference measurement are now established tools in the diagnostic work up of cystic fibrosis (CF). Intestinal current measurement (ICM) is under consideration as an aid in the diagnosis of CF especially in young children. The aim of this study is to evaluate the diagnostic reliability of ICM.

Association of chronic Candida albicans respiratory infection with a more severe lung disease in patients with cystic fibrosis

Despite the increase in fungal isolates, the significance of chronic Candida albicans airway colonization in CF is unclear.