Cystic fibrosis: Priorities and progress for future therapies

Cystic Fibrosis Human Organs-on-a-Chip

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane regulator (CFTR) gene: the gene product responsible for transporting chloride and bicarbonate ions through the apical membrane of most epithelial cells. Major clinical features of CF include respiratory failure, pancreatic exocrine insufficiency, and intestinal disease. Many CF animal models have been generated, but some models fail to fully capture the phenotypic manifestations of human CF disease. Other models that better capture the key characteristics of the human CF phenotype are cost prohibitive or require special care to maintain. Important differences have been reported between the pathophysiology seen in human CF patients and in animal models. These limitations present significant limitations to translational research. This review outlines the study of CF using patient-derived organs-on-a-chip to overcome some of these limitations. Recently developed microfluidic-based organs-on-a-chip provide a human experimental model that allows researchers to manipulate environmental factors and mimic in vivo conditions. These chips may be scaled to support pharmaceutical studies and may also be used to study organ systems and human disease. The use of these chips in CF discovery science enables researchers to avoid the barriers inherent in animal models and promote the advancement of personalized medicine.

New Therapeutic Approaches in Cystic Fibrosis

Cystic fibrosis (CF) is a hereditary, multisystemic disease caused by different mutations in the CFTR gene encoding CF transmembrane conductance regulator. CF is mainly characterized by pulmonary dysfunction as a result of deterioration in the mucociliary clearance and anion transport of airways. Mortality is mostly caused by bronchiectasis, bronchiole obstruction, and progressive respiratory dysfunction in the early years of life. Over the last decade, new therapeutic strategies rather than symptomatic treatment have been proposed, such as the small molecule approach, ion channel therapy, and pulmonary gene therapy. Due to considerable progress in the treatment options, CF has become an adult disease rather than a pediatric disease in recent years. Pulmonary gene therapy has gained special attention due to its mutation type independent aspect, therefore being applicable to all CF patients. On the other hand, the major obstacle for CF treatment is to predict the drug response of patients due to genetic complexity and heterogeneity. The advancement of 3D culture systems has made it possible to extrapolate the disease modeling and individual drug response in vitro by producing mini adult organs called "organoids" obtained from rectal cell biopsies. In this review, we summarize the advances in the novel therapeutic approaches, clinical interventions, and precision medicine concept for CF.

Clinical manifestation, laboratory findings, and outcome of children with cystic fibrosis over a 10-year period in South Iran

Background

Cystic fibrosis (CF) is a monogenic hereditary disease with diverse complications, which substantially reduce the quality of life and longevity of patients. With regard to the scarcity of information on epidemiological aspects of this disease in Iran, we aimed to examine the current status of pediatric CF patients in a tertiary referral center in south Iran.

Results

Medical records of 105 patients (51% female) with the mean age of 16.3 ± 34.4 months were reviewed. Twelve patients (13.3%) had siblings with CF. Failure to thrive and respiratory symptoms were the most common presentations. Elevated liver enzymes and steatorrhea were detected in over half of tested patients, while abnormal serum albumin level, urinalysis, positive urine cultures, and positive acute phase reactants were noticed in less than half of the patients. Mild increase in pulmonary artery blood pressure was the most common finding of echocardiography. Increased liver echogenicity was the top finding of abdominopelvic sonography. Out of 42 available patients, 19 (45.2%) died with the mean age of 54.4 ± 101.8 months. The highest rate of mortality was observed in the 2–6 years old age group (42.9%).

Conclusion

Increased liver echogenicity was the most common finding in hepatobiliary evaluation. Mild increase in pulmonary artery blood pressure was the most common finding of echocardiography.

High-resolution computed tomography findings in young infants with cystic fibrosis detected by newborn screening

OBJECTIVE

High-resolution computed tomography (HRCT) allows the early detection of pathological changes in the lung structure, and reproducible scoring systems can be used to quantify chest computed tomography (CT) findings in patients with cystic fibrosis (CF). The aim of the study was to describe early HRCT findings according to a validated scoring system in infants with CF diagnosed by newborn screening (NBS).

METHODS

This cross-sectional study included infants with CF diagnosed by NBS who were born between January 2013 and January 2017 and who underwent HRCT scanning within the first year after diagnosis when they were clinically stable. The CT scans were evaluated using the modified Bhalla score.

RESULTS

Thirty-two subjects underwent HRCT scanning. The mean total-modified Bhalla score was 3.6±2.1, and 93.8% of the scans were abnormal. Pseudomonas aeruginosa airway colonization was associated with increased modified Bhalla score values. Bronchial wall thickening was the most common feature (90.6%), followed by bronchial collapse/consolidation (59.4%), mosaic attenuation/perfusion (50%), bronchiectasis (37.5%) and mucus plugging (15.6%). Bronchial wall thickening was diffuse in most of the patients.

CONCLUSION

A substantial proportion of infants diagnosed with CF after detection by NBS already showed evidence of lung disease. P. aeruginosa colonization was associated with increased Bhalla scores, highlighting the importance of this CF pathogen in early structural lung disease. The presence of bronchial wall thickening at such a young age may reflect the presence of airway inflammatory processes. The detection and quantification of structural abnormalities with the modified Bhalla score may aid in the identification of lung disease before it is clinically apparent.

Peptide dendrimers as "lead compounds" for the treatment of chronic lung infections by Pseudomonas aeruginosa in cystic fibrosis patients: in vitro and in vivo studies

Aim

In the present work, the potential of the D-enantiomeric dendrimers dG3KL and dTNS18 was evaluated in relation to tobramycin (Tob), for the development of novel antibacterials to treat Pseudomonas aeruginosa chronic lung infections in patients with cystic fibrosis.

Results

The activity of dendrimers against planktonic P. aeruginosa cells was less than Tob against three of the four strains tested (median minimum inhibitory concentration [MIC] 8 vs 1 µg/mL, respectively), but 32-fold higher against the PaPh32 strain isolated at posttransplantation stage. Results from comparative minimum bactericidal concentration/MIC evaluation and time-kill assay suggested a bactericidal mechanism for all test agents. Subinhibitory concentrations of both dendrimers and Tob significantly affected biofilm formation by all strains in a dose-dependent manner, although the PaPh26 strain, isolated during the chronic stage of infection, was particularly susceptible to dendrimers. The activity of dendrimers against preformed P. aeruginosa biofilm was generally comparable to Tob, considering both dispersion and viability of biofilm. Particularly, exposure to the test agent at 10 × MIC caused significant biofilm death (>90%, even to eradication), though with strain-specific differences. Single administration of dendrimers or Tob at 10 × MIC was not toxic in Galleria mellonella wax-moth larvae over 96 hours. However, contrarily to Tob, dendrimers were not protective against systemic infection caused by P. aeruginosa in G. mellonella. Kinetics of P. aeruginosa growth in hemolymph showed that bacterial load increased over time in the presence of dendrimers.

Conclusion

Overall, our findings indicated that dG3KL and dTNS18 peptide dendrimers show in vitro activity comparable to Tob against both P. aeruginosa planktonic and biofilm cells at concentrations not toxic in vivo. Further studies are warranted to explore different dosages and to increase the bioavailability of the peptides to solve the lack of protective effect observed in G. mellonella larvae.

Electrochemically Synthesized Silver Nanoparticles Are Active Against Planktonic and Biofilm Cells of Pseudomonas aeruginosa and Other Cystic Fibrosis-Associated Bacterial Pathogens

A novel, electrochemically synthesized, silver nanoparticles (AgNPs) formulation was evaluated in vitro against Pseudomonas aeruginosa, Burkholderia cepacia, Stenotrophomonas maltophilia, and Staphylococcus aureus strains from cystic fibrosis (CF) patients. AgNPs were particularly active against P. aeruginosa and B. cepacia planktonic cells (median MIC: 1.06 and 2.12 μg/ml, respectively) by a rapid, bactericidal and concentration-dependent effect. AgNPs showed to be particularly effective against P. aeruginosa and S. aureus biofilm causing a viability reduction ranging from 50% (1×MIC) to >99.9% (4×MIC). Electron microscopy showed that AgNPs deconstruct extracellular matrix of P. aeruginosa biofilm, and accumulate at the cell surface causing cell death secondary to membrane damage. Compared to Tobramycin, AgNPs showed comparable, or even better, activity against planktonic and biofilm P. aeruginosa cells. AgNPs at concentrations effective against B. cepacia and P. aeruginosa were not toxic to G. mellonella larvae. Our silver-based formulation might be an alternative to antibiotics in CF patients. Further in vitro and in vivo studies are warranted to confirm this therapeutic potential.