Cystic fibrosis: ultrastructural changes of nasal mucosa

Quorum-sensing inhibition abrogates the deleterious impact of Pseudomonas aeruginosa on airway epithelial repair

Chronic Pseudomonas aeruginosa lung infections are associated with progressive epithelial damage and lung function decline. In addition to its role in tissue injury, the persistent presence of P. aeruginosa-secreted products may also affect epithelial repair ability, raising the need for new antivirulence therapies. The purpose of our study was to better understand the outcomes of P. aeruginosa exoproducts exposure on airway epithelial repair processes to identify a strategy to counteract their deleterious effect. We found that P. aeruginosa exoproducts significantly decreased wound healing, migration, and proliferation rates, and impaired the ability of directional migration of primary non-cystic fibrosis (CF) human airway epithelial cells. Impact of exoproducts was inhibited after mutations in P. aeruginosa genes that encoded for the quorum-sensing (QS) transcriptional regulator, LasR, and the elastase, LasB, whereas impact was restored by LasB induction in ΔlasR mutants. P. aeruginosa purified elastase also induced a significant decrease in non-CF epithelial repair, whereas protease inhibition with phosphoramidon prevented the effect of P. aeruginosa exoproducts. Furthermore, treatment of P. aeruginosa cultures with 4-hydroxy-2,5-dimethyl-3(2H)-furanone, a QS inhibitor, abrogated the negative impact of P. aeruginosa exoproducts on airway epithelial repair. Finally, we confirmed our findings in human airway epithelial cells from patients with CF, a disease featuring P. aeruginosa chronic respiratory infection. These data demonstrate that secreted proteases under the control of the LasR QS system impair airway epithelial repair and that QS inhibitors could be of benefit to counteract the deleterious effect of P. aeruginosa in infected patients.-Ruffin, M., Bilodeau, C., Maillé, É., LaFayette, S. L., McKay, G. A., Trinh, N. T. N., Beaudoin, T., Desrosiers, M.-Y., Rousseau, S., Nguyen, D., Brochiero, E. Quorum-sensing inhibition abrogates the deleterious impact of Pseudomonas aeruginosa on airway epithelial repair.

Considerations for a Pediatric Biopharmaceutics Classification System (BCS): application to five drugs

It has been advocated that biopharmaceutic risk assessment should be conducted early in pediatric product development and synchronized with the adult product development program. However, we are unaware of efforts to classify drugs into a Biopharmaceutics Classification System (BCS) framework for pediatric patients. The objective was to classify five drugs into a potential BCS. These five drugs were selected since both oral and intravenous pharmacokinetic data were available for each drug, and covered the four BCS classes in adults. Literature searches for each drug were conducted using Medline and applied to classify drugs with respect to solubility and permeability in pediatric subpopulations. Four pediatric subpopulations were considered: neonates, infants, children, and adolescents. Regarding solubility, dose numbers were calculated using a volume for each subpopulation based on body surface area (BSA) relative to 250 ml for a 1.73 m(2) adult. Dose numbers spanned a range of values, depending upon the pediatric dose formula and subpopulation. Regarding permeability, pharmacokinetic literature data required assumptions and decisions about data collection. Using a devised pediatric BCS framework, there was agreement in adult and pediatric BCS class for two drugs, azithromycin (class 3) and ciprofloxacin (class 4). There was discordance for the three drugs that have high adult permeability since all pediatric permeabilities were low: dolasetron (class 3 in pediatric), ketoprofen (class 4 in pediatric), and voriconazole (class 4 in pediatric). A main contribution of this work is the identification of critical factors required for a pediatric BCS.

Pathogenesis and management of nasal polyposis in cystic fibrosis

Beginning in preschool age, during their lives, up to 50% of cystic fibrosis (CF) patients experience obstructing nasal polyposis (NP), which is rare in non-CF children. Pathogenetic factors of NP in general and especially in CF are still obscure. However, defective epithelial ion transport from mucosal glands plays a central role in CF, and viscous secretions impair mucociliary clearance, promoting chronic pathogen colonization and neutrophil-dominated chronic inflammation. Presently, CF-NP is not curable but can be clinically stabilized, though the large variety of proposed treatment modalities indicates a lack of standardization and of evidence of treatment efficacy. When conservative measures are exhausted, surgical intervention combining individually adapted endoscopic sinus surgery and supportive conservative treatment is performed. Topical steroids, approved as the gold standard for non-CF NP, may be beneficial, but they are discussed to be less effective in neutrophilic inflammation, and CF-specific antimicrobial and mucolytic therapy, as is true of all treatment modalities, urgently requires evaluation by controlled clinical trials within interdisciplinary networks.

Prevalence and histopathology of chronic polypoid sinusitis in pediatric patients with cystic fibrosis

BACKGROUND

Chronic sinusitis is almost invariably a feature of cystic fibrosis. However, data on the endoscopically confirmed prevalence of chronic polypoid sinusitis (CPS) and its histological features are limited.

METHODS

Single centre prospective observational study. Unselected pediatric CF patients (n=81; ≤ 18 years) were endoscopically assessed for the prevalence of CPS. Sixteen of these underwent sinus surgery. The surgically obtained sinus specimens were compared to sinus specimen of non-CF-patients undergoing sinus surgery (n=61), using conventional histology and immunohistochemistry.

RESULTS

The prevalence of endoscopically confirmed CPS increased with age from 19% in infants younger than six years reaching 45% in adolescents. In CF patients, histology typically showed dilated glandular ducts and a predominance of mucous glands. The number of plasma cells and mast cells but not of eosinophils was significantly elevated compared to non-CF patients.

CONCLUSION

Prevalence of CPS in pediatric CF patients increases with age. Our findings indicate that chronic bacterial infection rather than allergic mechanisms may forward this pathology.

Pulsating aerosols for drug delivery to the sinuses in healthy volunteers

OBJECTIVE

Approximately 10 to 15 percent of the European and U.S. population have chronic rhinosinusitis, but effective treatment remains a challenge. There has been limited success using topical drug delivery to the nose and the paranasal cavities/sinuses, in part because most nasally administered aerosol drug formulations are efficiently filtered at the nasal valve and fail to reach the osteomeatal area and sinuses.

STUDY DESIGN

Feasibility study.

SETTING

Nuclear medicine department.

SUBJECTS AND METHODS

Pulsating airflows were applied to the nasal cavity and sinus ventilation was studied in five healthy human volunteers using dynamic (81m)Kr-gas gamma camera imaging. Furthermore, deposition and retention of (99m)Tc-DTPA radiolabeled aerosols delivered by nasal pump sprays or by pulsating aerosols was assessed in each volunteer over a 24-hour period.

RESULTS

Only the pulsating airflow demonstrated efficient (81m)Kr-gas ventilation of the paranasal sinuses. No drug was deposited into the sinuses using nasal pump sprays, but up to 6.5 percent of the nasally administered drug was deposited into the sinuses using pulsating airflow. Clearance kinetics of the drug was reduced after pulsating aerosol delivery compared to nasal pump sprays. Residence time of the drug at the site of deposition was up to three-fold longer with pulsating aerosol delivery than with nasal pump sprays.

CONCLUSION

Our data support the hypothesis that topical drug delivery in relevant quantities to the nose and osteomeatal areas, including the paranasal sinuses, is possible using pulsating airflows. Furthermore, the frequency of drug applications may be reduced due to a delayed clearance and longer residence time.