Defective acid sphingomyelinase pathway with Pseudomonas aeruginosa infection in cystic fibrosis.

Acid sphingomyelinase (ASMase) is a key enzyme in sphingolipid metabolism, which can be activated by various cellular stress mechanisms including bacterial pathogens. Activation of ASMase generates ceramide, which is important for innate immune response to eliminate infected pathogens. The current study reveals a defective ASMase pathway after Pseudomonas aeruginosa infection in both a cystic fibrosis (CF) bronchial epithelial cell line (IB3-1 cell) and in the lungs of CF transmembrane conductance regulator (CFTR) knockout (KO) mice as compared with S9 cells and wild-type C57BL/6 mice. ASMase activity and total ceramide levels significantly increased in S9 cells and C57BL/6 mice with P. aeruginosa infection, but not in IB3-1 cells and CFTR KO mice. The silencing of CFTR by CFTR RNAi in S9 cells significantly decreased ASMase activity after bacterial infection as compared with controls. This study also demonstrates that induction of ASMase is responsible for modulating the immune response to bacterial infection. Blocking ASMase activity with specific ASMase RNAi, an ASMase inhibitor, or an ASMase antibody in S9 cells significantly increased IL-8 levels with P. aeruginosa infection compared with controls. Reciprocally, adding exogenous bacterial sphingomyelinase to IB3-1 cells significantly decreased IL-8 levels compared with untreated cells. In addition, silencing of ASMase in S9 cells also significantly decreased bacterial internalization. Adding exogenous bacterial sphingomyelinase to IB3-1 cells reconstituted the cell death response to P. aeruginosa infection. This study demonstrates that the defective ASMase pathway in CF is a key contributor to the unabated IL-8 response with P. aeruginosa infection and to the compromised host response failing to eradicate bacteria.

Cost-effective airway cultures in the cystic fibrosis patient.

BACKGROUND: Cystic fibrosis (CF) patients have a high incidence of multidrug-resistant infections, rendering CF patients a treatment challenge. OBJECTIVE: To evaluate culture protocols for CF patients and develop a cost-effective culture regimen that identifies clinically relevant pathogens. STUDY DESIGN: Retrospective review. METHODS: At the time of endoscopic sinus surgery, CF patients underwent both sinus and bronchial lavage cultures. Medical records from 2002 to 2006 were reviewed. RESULTS: Twenty-four cases were identified; 12 had complete sets of cultures. Seven of 12 had sinus aerobic bacteria that were also present in bronchial culture. Anaerobic cultures from both sites were all negative (42%) or nondiagnostic (58%). Thirty-three percent of sinus fungal cultures and 91.6% of bronchial fungal cultures were positive. Sinus acid fast bacillus cultures were all negative. CONCLUSION: CF culture protocols may be streamlined by eliminating all anaerobic cultures, as well as sinus acid fast bacillus and fungal cultures for a 52% reduction in cost.

Potential pathogenicity of Inquilinus limosus in a pediatric patient with cystic fibrosis.

PRESENTATION: Patient is a 6-year-old male with CF, MRSA colonization, and pancreatic insufficiency that presented with worsening ppFEV1 and systemic symptoms despite multiple interventions. BAL grew NTM, Stenotrophomonas maltophilia, and Inquilinus limosus, a rare organism found in patients with CF. COURSE: I. limosus treatment was deferred. Despite treatment of other pathogens, symptoms worsened. I. limosus was targeted with meropenem, amikacin, and ciprofloxacin along with clindamycin for MRSA colonization. Within weeks, symptoms had resolved with ppFEV1 improvement. DISCUSSION: This case discusses the importance of a rare organism in the CF population. Targeting I. limosus was key to recovery, revealing its potential pathogenicity.

Age-related heterogeneity in dental caries and associated risk factors in individuals with cystic fibrosis ages 6-20 years: A pilot study.

BACKGROUND: The literature conflicts regarding dental caries risk in cystic fibrosis (CF) relative to controls. METHODS: Prospective, observational study of age-related heterogeneity in caries rates and potential risk factors in individuals with CF ages 6-20 at a single clinic in Washington state (N=85). Caries rates for enrolled CF participants and historical controls from NHANES were compared using cubic spline regression models. Generalized linear regression models identified correlates of age and caries in CF. RESULTS: Children ages 6-9 with CF had significantly lower caries than controls (Holm's P<0.05). There was no difference for ages 10-20 by CF status (Holm's P>0.05). Various biological/intraoral, medical, and behavioral factors were associated with caries and age in CF. CONCLUSIONS: Younger children with CF may be protected from caries, but there is apparent loss of protection in early adolescence associated with multiple risk factors. Additional studies are needed to confirm these findings.

Long-term safety of tobramycin inhalation powder in patients with cystic fibrosis: phase IV (ETOILES) study.

OBJECTIVE: Long-term treatment with inhaled antibiotics is recommended for chronic Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) patients. The ETOILES study (Clinicaltrials.gov identifier: NCT01519661) evaluated the safety of tobramycin inhalation powder (TIP) for 1 year. RESEARCH DESIGN AND METHODS: This single-arm, open-label, multicenter, phase IV trial, enrolled CF patients aged ≥6 years, with baseline FEV1 ≥25%-≤75% predicted and Pa infection, and assessed the safety of TIP over six cycles in terms of the incidence of treatment-emergent adverse events (AEs) and serious AEs (SAEs). Secondary endpoints included presence of airway reactivity, relative change in FEV1% predicted, and change in sputum Pa density (log10 colony forming units/g sputum). RESULTS: A total of 157 patients were enrolled, and 96 patients (61.1%) completed the study. The most commonly reported AE was infective pulmonary exacerbation of CF (55.4%). Cough was reported as an AE in 23.6% of patients; a majority were mild or moderate and two were severe (1.3%). SAEs were reported by 31.2% of patients. No deaths were reported during the study. There were no clinically meaningful changes reported in airway reactivity. Most frequently reported post-inhalation event was cough at all time points; however, it was of short duration (<4 minutes) and decreased over the course of the study, possibly due to patients becoming more experienced with the administration of TIP. The post-inhalation events resolved without intervention in most cases. FEV1% predicted remained stable from Cycles 1 to 4 and tended to decrease thereafter, although it was not statistically significant (change from baseline to study end mean [SD] = -1.9% [14.55]; P = 0.199). CONCLUSIONS: This was one of the largest studies with long-term TIP exposure. The majority of patients enrolled were adults with more advanced CF lung disease than those in previous TIP studies. No new emerging safety signals were seen and efficacy was sustained during the year.

Quantitative sinonasal symptom assessment in an unselected pediatric population with cystic fibrosis.

INTRODUCTION: The aim of this study was to establish baseline sinonasal quality of life scores in an unselected pediatric population with cystic fibrosis (CF) and to test the correlation of those scores with various clinical outcome measurements. METHODS: A total of 50 consecutive children, ages 2-12 years, seen routinely in a large CF clinic were evaluated by using the Sinus and Nasal Quality of Life Survey (SN-5) tool at the time of their visit. At this time, the parent or guardian of the child was also questioned about recent episodes of sinusitis, antibiotic prescriptions for sinusitis, recent hospitalizations, and days missed from school or recreational activities due to sinonasal symptoms. CF genotype, pulmonary function, recent sinus surgeries, and computed tomography scores were established by thorough chart review. RESULTS: The average SN-5 score of this group was lower than published averages in children with baseline, preoperative, or postoperative chronic sinusitis, and demonstrated significant correlations with a visual analog scale, recent episodes of sinusitis, antibiotic prescriptions for sinusitis, and the number of days missed from school or recreational activities due to sinonasal symptoms, with a nonsignificant trend observed with previous sinus surgery. No correlations were seen with CF genotype, pulmonary function, or hospitalization days. Computed tomography results were overwhelmingly abnormal, and Lund-MacKay scores did not correlate with SN-5 scores or clinical outcome measurements. CONCLUSIONS: The SN-5 tool provides a quick, safe, and reliable qualitative metric for monitoring sinonasal symptoms in young children with CF.

Enhancing rAAV vector expression in the lung.

Despite favorable DNA transfer efficiency, gene expression from recombinant adeno-associated virus (rAAV2) vectors in the lung has been variable in the context of cystic fibrosis (CF) gene therapy. This is due, in part, to the large size of the CF transmembrane regulator (CFTR)-coding sequence which necessitates the use of compact endogenous promoter elements versus stronger exogenous promoters. We evaluated the possibility that gene expression from rAAV could be improved by using AAV capsid serotypes with greater tropism for the apical surface of airway cells (i.e. rAAV5 or rAAV1) and/or using strong promoters such as the cytomegalovirus (CMV) enhancer/chicken beta-actin hybrid (Cbeta) promoter. The relative activity of the CMV immediate-early (CMVie) promoter, the Cbeta promoter, and the Cbeta promoter with a downstream woodchuck hepatitis virus post-transcriptional regulatory element (wpre) were assessed in vitro and in vivo in C57\Bl6 mice using human alpha-1 antitrypsin (hAAT) as a secreted reporter. In vivo, the Cbeta-AAT-wpre group achieved maximum serum levels of 1.5 mg/ml of hAAT. AAV capsid serotypes were then compared in vivo utilizing the transcriptionally optimized CB-wpre cassette in rAAV serotype 1, 2 or 5 capsids (rAAV1, rAAV2, and rAAV5), utilizing luciferase as a reporter to compare expression over a wide dynamic range. The pulmonary luciferase levels at 8 weeks were similar in rAAV5 and rAAV1 groups (2.9 x 10(6) relative light units (RLU)/g tissue and 2.7 x 10(6) RLU/g tissue, respectively), both of which were much higher than rAAV2. Although the advantage of rAAV5 over rAAV2 in the lung has already been described, the availability of another serotype (rAAV1) capable of efficient gene transfer in the lung could be useful.

Effects of CFTR, interleukin-10, and Pseudomonas aeruginosa on gene expression profiles in a CF bronchial epithelial cell Line.

Mutations in CFTR lead to a complex phenotype that includes increased susceptibility to Pseudomonas infections, a functional deficiency of IL-10, and an exaggerated proinflammatory cytokine response. We examined the effects of CFTR gene correction on the gene expression profile of a CF bronchial epithelial cell line (IB3-1) and determined which CF-related gene expression changes could be reversed by IL-10 expression. We performed microarray experiments to monitor the gene expression profile of three cell lines over a time course of exposure to Pseudomonas. At baseline, we identified 843 genes with statistically different levels of expression in CFTR-corrected (S9) cells compared to the IB3-1 line or the IL-10-expressing line. K-means clustering and functional group analysis revealed a primary up-regulation of ubiquitination enzymes and TNF pathway components and a primary down-regulation of protease inhibitors and protein glycosylation enzymes in CF. Key gene expression changes were confirmed by real-time RT-PCR. Massive reprogramming of gene expression occurred 3 h after Pseudomonas exposure. Changes specific to CF included exaggerated activation of cytokines, blunted activation of anti-proteases, and repression of protein glycosylation enzymes. In conclusion, the CFTR genotype changes the expression of multiple genes at baseline and in response to bacterial challenge, and only a subset of these changes is secondary to IL-10 deficiency.