Cystic fibrosis: an overview

Progress in non-viral localized delivery of siRNA therapeutics for pulmonary diseases

Emerging therapies based on localized delivery of siRNA to lungs have opened up exciting possibilities for treatment of different lung diseases. Localized delivery of siRNA to lungs has shown to result in severalfold higher lung accumulation than systemic route, while minimizing non-specific distribution in other organs. However, to date, only 2 clinical trials have explored localized delivery of siRNA for pulmonary diseases. Here we systematically reviewed recent advances in the field of pulmonary delivery of siRNA using non-viral approaches. We firstly introduce the routes of local administration and analyze the anatomical and physiological barriers towards effective local delivery of siRNA in lungs. We then discuss current progress in pulmonary delivery of siRNA for respiratory tract infections, chronic obstructive pulmonary diseases, acute lung injury, and lung cancer, list outstanding questions, and highlight directions for future research. We expect this review to provide a comprehensive understanding of current advances in pulmonary delivery of siRNA.

Nanomedicine Approaches for the Pulmonary Treatment of Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disease affecting today nearly 70,000 patients worldwide and characterized by a hypersecretion of thick mucus difficult to clear arising from the defective CFTR protein. The over-production of the mucus secreted in the lungs, along with its altered composition and consistency, results in airway obstruction that makes the lungs susceptible to recurrent and persistent bacterial infections and endobronchial chronic inflammation, which are considered the primary cause of bronchiectasis, respiratory failure, and consequent death of patients. Despite the difficulty of treating the continuous infections caused by pathogens in CF patients, various strategies focused on the symptomatic therapy have been developed during the last few decades, showing significant positive impact on prognosis. Moreover, nowadays, the discovery of CFTR modulators as well as the development of gene therapy have provided new opportunity to treat CF. However, the lack of effective methods for delivery and especially targeted delivery of therapeutics specifically to lung tissues and cells limits the efficiency of the treatments. Nanomedicine represents an extraordinary opportunity for the improvement of current therapies and for the development of innovative treatment options for CF previously considered hard or impossible to treat. Due to the peculiar environment in which the therapies have to operate characterized by several biological barriers (pulmonary tract, mucus, epithelia, bacterial biofilm) the use of nanotechnologies to improve and enhance drug delivery or gene therapies is an extremely promising way to be pursued. The aim of this review is to revise the currently used treatments and to outline the most recent progresses about the use of nanotechnology for the management of CF.

Transnasal Humidified Rapid-Insufflation Ventilatory Exchange for Deep Sedation in a Lung Transplant Candidate With Severe Cystic Fibrosis: A Case Report

Transnasal humidified rapid-insufflation ventilatory exchange is a recently described technique for safer management of difficult airways and a novel ventilation technique under anesthesia. Its full potential in patient safety and benefits are still being investigated. We describe the use of transnasal humidified rapid-insufflation ventilatory exchange for deep sedation during dental extractions in a patient with severe cystic fibrosis as a precondition for lung transplantation. Patient wanted to have the procedure under general anesthesia with intubation due to extreme anxiety. However, we advocated deep IV sedation with transnasal humidified rapid-insufflation ventilatory exchange. Oxygenation was maintained without airway obstruction and pulmonary complications during the entire procedure of 110 minutes.

Air stacking: effects of Pilates mat exercises on muscle strength and on pulmonary function in patients with cystic fibrosis

OBJECTIVE:

To analyze the effects of Pilates mat exercises in patients with cystic fibrosis (CF).

METHODS:

This was a clinical trial involving 19 CF patients recruited from either the CF Outpatient Clinic of the State University at Campinas Hospital de Clínicas or the Children's Institute of the University of São Paulo School of Medicine Hospital das Clínicas. All of the patients performed Pilates mat exercises for four months (one 60-min session per week). The variables studied (before and after the intervention) were respiratory muscle strength, MIP, MEP, FVC, and FEV₁.

RESULTS:

After the intervention, MIP was significantly higher in the male patients (p = 0.017), as were MIP and MEP in the female patients (p = 0.005 and p = 0.007, respectively). There were no significant differences between the pre- and post-intervention values of FVC or FEV₁, neither in the sample as a whole nor among the patients of either gender.

CONCLUSIONS:

Our results show that Pilates mat exercises have beneficial effects on respiratory muscle strength in CF patients.

VIP regulates CFTR membrane expression and function in Calu-3 cells by increasing its interaction with NHERF1 and P-ERM in a VPAC1- and PKCε-dependent manner

Vasoactive intestinal peptide (VIP) is a topical airway gland secretagogue regulating fluid secretions, primarily by stimulating cystic fibrosis transmembrane conductance regulator (CFTR)-dependent chloride secretion that contributes to the airways innate defense mechanism. We previously reported that prolonged VIP stimulation of pituitary adenylate cyclase-activating peptide receptors (VPAC1) in airway cells enhances CFTR function by increasing its membrane stability. In the present study, we identified the key effectors in the VIP signaling cascade in the human bronchial serous cell line Calu-3. Using immunocytochemistry and in situ proximity ligation assays, we found that VIP stimulation increased CFTR membrane localization by promoting its colocalization and interaction with the scaffolding protein Na+/H+ exchange factor 1 (NHERF1), a PDZ protein known as a positive regulator for CFTR membrane localization. VIP stimulation also increased phosphorylation, by protein kinase Cε of the actin-binding protein complex ezrin/radixin/moesin (ERM) and its interaction with NHERF1 and CFTR complex. On the other hand, it reduced intracellular CFTR colocalization and interaction with CFTR associated ligand, another PDZ protein known to compete with NHERF1 for CFTR interaction, inducing cytoplasmic retention and lysosomal degradation. Reducing NHERF1 or ERM expression levels by specific siRNAs prevented the VIP effect on CFTR membrane stability. Furthermore, iodide efflux assays confirmed that NHERF1 and P-ERM are necessary for VIP regulation of the stability and sustained activity of membrane CFTR. This study shows the cellular mechanism by which prolonged VIP stimulation of airway epithelial cells regulates CFTR-dependent secretions.

A rapid membrane potential assay to monitor CFTR function and inhibition

The cystic fibrosis transmembrane conductance regulator (CFTR) protein is an important regulator of ion transport and fluid secretion in humans. Mutations to CFTR cause cystic fibrosis, which is a common recessive genetic disorder in Caucasians. Involvement of CFTR has been noted in other important diseases, such as secretory diarrhea and polycystic kidney disease. The assays to monitor CFTR function that have been described to date either are complicated or require specialized instrumentation and training for execution. In this report, we describe a rapid FlexStation-based membrane potential assay to monitor CFTR function. In this assay, agonist-mediated activation of CFTR results in membrane depolarization that can be monitored using a fluorescent membrane potential probe. Availability of a simple mix-and-read assay to monitor the function of this important protein might accelerate the discovery of CFTR ligands to study a variety of conditions.

Transport of nanoparticles in cystic fibrosis sputum and bacterial biofilms by single-particle tracking microscopy

Aim: The aim of this study was to evaluate the effect of the surface functionalization of model nanoparticles on their mobility in bacterial biofilms and cystic fibrosis sputum. Materials & methods: With single-particle tracking microscopy, the mobility of 0.1- and 0.2-µm fluorescent polyethylene glycol (PEG) modified, carboxylate- and N,N-dimethylethylenediamine-modified polystyrene nanospheres were evaluated in fresh cystic fibrosis sputum, as well as Burkholderia multivorans and Pseudomonas aeruginosa biofilms. Results: PEGylation increased the mobility of the particles in sputum and biofilms, while the charged nanospheres were strongly immobilized. However, the transport of the PEGylated nanoparticles was lower in sputum compared with biofilms. Furthermore, the particle transport showed heterogeneity in samples originating from different patients. Conclusion: This study’s data suggest that for future nanocarrier design it will be essential to combine PEGylation with a targeting moiety to ensure sufficient mobility in mucus and a better accumulation of the nanoparticles in the biofilm.

Original submitted 14 February 2012; Revised submitted 24 July 2012; Published online 5 October 2012

Delayed release pancrelipase for the treatment of pancreatic exocrine insufficiency associated with cystic fibrosis

Pancreatic enzyme replacement therapy (PERT) is the only treatment for malabsorption in cystic fibrosis (CF) caused by pancreatic insufficiency (PI). PI occurs in approximately 85% of patients with CF. PERT overcomes some, but not all the signs and symptoms of malabsorption. Clinical parameters such as growth, abdominal pain, diarrhea and gassiness, commonly used to adjust PERT dosing, are shown not to be good indicators of their effectiveness. The FDA does not provide oversight of preparations of pancreatic enzymes consistent with the oversight it provides for all other drugs. The FDA intends to rectify this situation. Measures of the effectiveness of PERT are limited to the coefficient of fat absorption, a difficult and unpleasant exercise for patients.

A disease-relevant high-content screening assay to identify anti-inflammatory compounds for use in cystic fibrosis

Chronic lung inflammation caused by bacterial pathogenesis through activation of nuclear factor kappa B (NFκB)-responsive proinflammatory genes is a major hurdle in the management of lung disease in cystic fibrosis (CF) patients. The authors generated a disease-relevant cell-based high-content screen to identify novel anti-inflammatory compounds for treating lung inflammation in CF. The human bronchial epithelial cell line KKLEB, harboring the most common form of mutation that causes CF, was modified to express an NFκB-responsive green fluorescent protein (GFP) reporter. After creation, the cell line was tested for its ability to respond to disease-relevant inflammatory stimuli elicited by treatment of cells with filtrates of Pseudomonas aeruginosa isolated from the airways of a CF patient. P. aeruginosa filtrates potently activated NFκB-responsive GFP reporter expression in cells. Subsequently, the assay was optimized for high-throughput screening (HTS) through generation of a Z factor (~0.5) and by testing its tolerance to the commonly used solvents ethanol and DMSO. A pilot library of clinically approved compounds was screened for assay validation. Several compounds with known NFκB inhibitory activity were identified, including several steroidal compounds that have been clinically tested in CF. Thus, the assay can be used in a broader HTS campaign to find anti-inflammatory agents for use in CF.

Twenty questions in genetic medicine--an assessment of World Wide Web databases for genetics information at the point of care

PURPOSE

The aim of this article was to determine the accuracy and efficiency of World Wide Web ("Web") resources to help nongeneticists answer four clinical questions about each of five common genetic conditions.

METHODS

Correct answers were established by literature review. Two open-access genetics resources and seven general subscription resources were reviewed. Scoring criteria were established to define complete, partial, vague, inconsistent, not found, and wrong answers. The main outcome measures were number of answers found, accuracy, and completeness of answers. Efficiency (time per answer found) was a secondary measure.

RESULTS

Overall, the databases contained complete answers 33.3% of the time but contained no information as frequently (33.9%). The best database had complete answers 70% of the time, whereas the worst contained no complete answers. Five of the seven subscription databases had a total of eight wrong answers. The other two subscription databases and the two open-access genetics databases had no wrong answers. Search time ranged from 3.2 to 18.3 minutes per complete answer.

CONCLUSIONS

Nongeneticist providers do not have a Web resource that is accessible, accurate, and efficient to answer genetic questions that might arise in practice.

Costs, quality of life and treatment compliance associated with antibiotic therapies in patients with cystic fibrosis: a review of the literature

BACKGROUND

Cystic fibrosis is the most common incurable hereditary disease in the US. Persistent respiratory infection is the leading cause of morbidity and mortality in cystic fibrosis patients.

OBJECTIVE

This study aimed to review the literature on economic and quality of life outcomes and treatment compliance associated with antibiotic therapies for cystic fibrosis patients.

METHODS

A systematic literature review was conducted using keyword searches of the MEDLINE database and selected conference abstracts. The review covered studies published between January 1990 and May 2007.

RESULTS/CONCLUSIONS

Evidence suggests that inhaled tobramycin, a key chronic suppressive therapy, can reduce other healthcare costs. The main determinants of the cost of care include disease severity and respiratory infection. Costs vary widely by country. There is evidence that inhaled tobramycin and oral azithromycin improve quality of life and that treatment setting and patient convenience may also impact on quality of life. Antibiotic treatment compliance varied significantly and depended on the method of measurement, with more subjective measures tending to be higher. This review concludes by offering directions for future research.

Altered biogenesis of deltaF508-CFTR following treatment with doxorubicin

Cystic fibrosis (CF) is caused by mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The most common of these mutations is deletion of a phenylalanine residue at position 508 (Delta F508), which accounts for approximately 70% of all CF alleles. This mutation interferes with the biogenesis and maturation of Delta F508-CFTR to the plasma membrane. However, Delta F508-CFTR can partially function upon proper localization. Thus, pharmacological correction of Delta F508-CFTR maturation holds promise in CF therapy. Our previous studies indicate that a single non-cytotoxic dose of the anthracycline doxorubicin (Dox) significantly increase Delta F508-CFTR-associated chloride secretion in MDCK cells by increasing the expression of this protein at the apical plasma membrane. We report here that Dox alters the biogenesis of Delta F508-CFTR. Treatment with Dox increases the resistance of Delta F508-CFTR to trypsin digestion, possibly by expediting protein folding. Further, treatment with Dox reduces the amount of polyubiquitinated Delta F508-CFTR in cells and prolongs the half-life of this protein. Concomitantly, treatment with Dox decreases the association of Delta F508-CFTR with HSP70 but does not alter the expression of major HSP70 family members. Based on these results, we propose that Dox expedites the folding and maturation of Delta F508-CFTR by acting as a pharmacological chaperone, which consequently promotes the functional expression of this protein in MDCK cells.

Genetic screening for cystic fibrosis: An overview of the science and the economics

The aim of this paper is to provide an overview of the current scientific and economic thinking on the use of genetic technologies for cystic fibrosis (CF) screening. The paper takes a public health genetics viewpoint and gives an overview of the genetics behind CF, then describes current practices in screening for the disease. We then discuss the current literature on the economic evaluations of screening for CF. As the "wet" science improves, there are direct implications for health service. Therefore, it is important to keep examining both clinical practice and economics behind the technologies.

Nasal immunization with Burkholderia multivorans outer membrane proteins and the mucosal adjuvant adamantylamide dipeptide confers efficient protection against experimental lung infections with B. multivorans and B. cenocepacia

Chronic lung infection by opportunistic pathogens, such as Pseudomonas aeruginosa and members of the Burkholderia cepacia complex, is a major cause of morbidity and mortality in patients with cystic fibrosis. Outer membrane proteins (OMPs) of gram-negative bacteria are promising vaccine antigen candidates. In this study, we evaluated the immunogenicity, protection, and cross-protection conferred by intranasal vaccination of mice with OMPs from B. multivorans plus the mucosal adjuvant adamantylamide dipeptide (AdDP). Robust mucosal and systemic immune responses were stimulated by vaccination of naive animals with OMPs from B. multivorans and B. cenocepacia plus AdDP. Using a mouse model of chronic pulmonary infection, we observed enhanced clearance of B. multivorans from the lungs of vaccinated animals, which correlated with OMP-specific secretory immunoglobulin A responses. Furthermore, OMP-immunized mice showed rapid resolution of the pulmonary infection with virtually no lung pathology after bacterial challenge with B. multivorans. In addition, we demonstrated that administration of B. multivorans OMP vaccine conferred protection against B. cenocepacia challenge in this mouse infection model, suggesting that OMPs provide cross-protection against the B. cepacia complex. Therefore, we concluded that mucosal immunity to B. multivorans elicited by intranasal vaccination with OMPs plus AdDP could prevent early steps of colonization and infection with B. multivorans and also ameliorate lung tissue damage, while eliciting cross-protection against B. cenocepacia. These results support the notion that therapies leading to increased mucosal immunity in the airways may help patients with cystic fibrosis.

High Incidence of Gastric Bezoars in Cystic Fibrosis Patients after Lung Transplantation

BACKGROUND

Bezoars are concretions of ingested matter which accumulate in the gastrointestinal tract and manifest as symptomatic foreign bodies. The aim of this study is to evaluate the incidence of gastric bezoars after lung transplantation and identify associated risk factors.

METHODS

We performed a retrospective analysis of patients who underwent lung transplantation from December, 1992 through July, 2005 at our tertiary care medical center. Patients who had endoscopically confirmed gastrointestinal bezoars in the posttransplant setting were identified and compared with patients without bezoars.

RESULTS

Of the 215 patients who received lung transplantation, 17 (7.9%) developed gastric bezoars confirmed by upper endoscopy. Cystic fibrosis was the leading indication for lung transplantation (n=145), and 11% of cystic fibrosis patients (16 of 145) formed gastric bezoars after transplant. Additionally, 94% of patients with bezoars (16 of 17) had cystic fibrosis (P=0.02), with the exception being a subject with primary ciliary dyskinesia. No patient who underwent lung transplant for another indication was found to have a bezoar. The mean time to diagnosis was 34 days, with two-thirds of bezoars diagnosed within one month after transplant. The annual incidence was unchanged during the study period.

CONCLUSIONS

Gastric bezoars are common in cystic fibrosis patients after lung transplantation. The etiology is likely multifactorial, related to gastric motility, respiratory secretions, and medications. Further investigation is needed to understand the pathogenesis of bezoar formation in this selected population, and strategies for primary prevention may be beneficial.

Differential expression of calcium-activated chloride channels (CLCA) gene family members in the small intestine of cystic fibrosis mouse models

Members of the family of calcium-activated chloride channels (CLCA) have been implicated as modulators of the phenotype in cystic fibrosis (CF). Here, the expression levels of the murine mCLCA1, mCLCA2, mCLCA3 and mCLCA4 were quantified by real-time RT-PCR in the small intestines of CF (cftr (tm1Cam), cftr (TgH(neoim)1Hgu)) and wild type C57BL/6, BALB/c, DBA/2 and NMRI mice. Markedly different expression levels of all four CLCA homologs were observed between the different wild type strains. Expression of mCLCA1 and mCLCA4 was similar in CF versus wild type. In contrast, mCLCA3 mRNA copy numbers were increased up to threefold in all CF models. Immunohistochemical detection of mCLCA3 and PAS reactions on consecutive tissue sections identified a similar increase in mCLCA3 expressing goblet cells, suggesting that elevated mRNA copy numbers of mCLCA3 are due to goblet cell hyperplasia rather than transcriptional regulatory events. Increased mCLCA2 mRNA copy numbers, however, were considered more likely to be due to transcriptional upregulation. Changes in mRNA copy numbers were not associated with altered cell kinetics as determined by immunohistochemistry using antibodies to phospho-histone 3 and activated caspase-3. The results suggest that both mCLCA2 and mCLCA3 may act as modifiers of the intestinal phenotype in CF.

Electroconvulsive therapy for treatment of refractory depression in a patient with cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive inherited disease that is usually first diagnosed in early childhood. It is a chronic and progressive disease in which mucus builds up and clogs passages in many body organs, but primarily the lungs and pancreas. We present a case report of a 42-year-old man with CF who was treated with electroconvulsive therapy for treatment-refractory major depressive disorder. For patients with CF, the primary issue is anesthetic management in a patient with impaired pulmonary function. Our patient received prednisone and intravenous antibiotics to optimize pulmonary status. He responded positively to the electroconvulsive therapy and was able to tolerate it without significant problems.