BACKGROUND-A new approach in the treatment of cystic fibrosis involves improving the function of mutant cystic fibrosis transmembrane conductance regulator (CFTR). VX-770, a CFTR potentiator, has been shown to increase the activity of wild-type and defective cell-surface CFTR in vitro.

SummaryPrimary ciliary dyskinesia (PCD) is a genetically heterogeneous, rare lung disease resulting in chronic oto‐sino‐pulmonary disease in both children and adults. Many physicians incorrectly diagnose PCD or eliminate PCD from their differential diagnosis due to inexperience with diagnostic testing methods. Thus far, all therapies used for PCD are unproven through large clinical trials. This review article outlines consensus recommendations from PCD physicians in North America who have been engaged in a PCD centered research consortium for the last 10 years. These recommendations have been adopted by the governing board of the PCD Foundation to provide guidance for PCD clinical centers for diagnostic testing, monitoring, and appropriate short and long‐term therapeutics in PCD patients. Pediatr Pulmonol. 2016;51:115–132. © 2015 The Authors. Pediatric Pulmonology Published by Wiley Periodicals, Inc.

Rationale: Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator recently approved for patients with CF age 6 and older with the G551D mutation.Objectives: To evaluate ivacaftor in a postapproval setting and determine mechanism of action and response of clinically relevant markers.Methods: We conducted a longitudinal cohort study in 2012-2013 in G551D CF patients age 6 and older with no prior exposure to ivacaftor. Study assessments were performed at baseline, 1, 3, and 6 months after ivacaftor initiation. Substudies evaluated mucociliary clearance, b-adrenergic sweat secretion rate, gastrointestinal pH, and sputum inflammation and microbiology Measurements and Main Results: A total of 151 of 153 subjects were prescribed ivacaftor and 88% completed the study through 6 months. FEV 1 % predicted improved from baseline to 6 months (mean absolute change, 6.7%; P , 0.001). Similarly, body mass index improved from baseline to 6 months (mean change, 0.8 kg/m 2 ; P , 0.001). Sweat chloride decreased from baseline to 6 months (mean change, 253.8 mmol/L; 95% confidence interval, 257.7 to 249.9; P , 0.001), reflecting augmented CFTR function. There was significant improvement in hospitalization rate (P , 0.001) and Pseudomonas aeruginosa burden (P , 0.01). Significant improvements in mucociliary clearance (P , 0.001), gastrointestinal pH (P = 0.001), and microbiome were also observed, providing clinical mechanisms underlying the therapeutic benefit of ivacaftor.Conclusions: Significant clinical and physiologic improvements were observed on initiation of ivacaftor in a broad patient population, including reduced infection with P. aeruginosa. Biomarker studies substantially improve the understanding of the mechanistic consequences of CFTR modulation on pulmonary and gastrointestinal physiology.

Culture of bronchoalveolar lavage fluid (BALF) is the gold standard for detection of pathogens in the lower airways in cystic fibrosis (CF). However, current culture results do not explain all clinical observations in CF, including negative culture results during pulmonary exacerbation and inflammation in the absence of pathogens. We hypothesize that organisms not routinely identified by culture occur in the CF airway and may contribute to disease. To test this hypothesis we used a culture-independent molecular approach, based on use of rRNA sequence analysis, to assess the bacterial composition of BALF from children with CF and disease controls (DC). Specimens from 42 subjects (28 CF) were examined, and Ϸ6,600 total clones were screened to identify 121 species of bacteria. In general, a single rRNA type dominated clone libraries from CF specimens, but not DC. Thirteen CF subjects contained bacteria that are not routinely assessed by culture. In four CF subjects, candidate pathogens were identified and include the anaerobe Prevotella denticola, a Lysobacter sp., and members of the Rickettsiales. The presumptive pathogens Tropheryma whipplei and Granulicatella elegans were identified in cases from the DC group. The presence of unexpected bacteria in CF may explain inflammation without documented pathogens and consequent failure to respond to standard treatment. These results show that molecular techniques provide a broader perspective on airway bacteria than do routine clinical cultures and thus can identify targets for further clinical evaluation. pulmonary microbiology ͉ ribosomal RNA C ystic fibrosis (CF), the most common autosomal lethal disease in Caucasians, is caused by mutation in the CF transmembrane conductance regulator gene, which results in a generalized exocrinopathy (1). Thickened secretions caused by improper regulation of airway surface liquid contribute to the accumulation of mucus in the airway and defective mucociliary clearance (2). Retained mucus plugs provide a niche for bacterial colonization and persistence. Most morbidity and mortality associated with CF is attributed to microbial infections in the airway and the persistent inflammatory response (3).A small number of pathogens are recognized traditionally in CF airway disease. These include Pseudomonas aeruginosa, Staphylococcus aureus, Haemophilus influenzae, and the Burkholderia cepacia complex (4-7). Other bacteria, including Stenotrophomonas maltophilia and Achromobacter xylosoxidans, also are associated with CF, but there is controversy as to their roles as pathogens (8)(9)(10). This view of bacteria associated with CF is based on culture, however, which may not recover or identify all bacteria present in a specimen. Although known pathogens clearly are important in airway disease, a more comprehensive picture of the bacterial community in the CF airway potentially could lead to improved insight about the disease and thus better treatment. For instance, ''normal'' microbiota that are commonly present, but not considered pathogenic, ...

The panel formulated and provided a rationale for the direction as well as for the strength of each recommendation to establish the diagnosis of PCD.

Rationale: Several studies suggest that nasal nitric oxide (nNO) measurement could be a test for primary ciliary dyskinesia (PCD), but the procedure and interpretation have not been standardized.Objectives: To use a standard protocol for measuring nNO to establish a diseasespecific cutoff value at one site, and then validate at six other sites.Methods: At the lead site, nNO was prospectively measured in individuals later confirmed to have PCD by ciliary ultrastructural defects (n = 143) or DNAH11 mutations (n = 6); and in 78 healthy and 146 disease control subjects, including individuals with asthma (n = 37), cystic fibrosis (n = 77), and chronic obstructive pulmonary disease (n = 32). A disease-specific cutoff value was determined, using generalized estimating equations (GEEs). Six other sites prospectively measured nNO in 155 consecutive individuals enrolled for evaluation for possible PCD. Measurements and Main Results:At the lead site, nNO values in PCD (mean 6 standard deviation, 20.7 6 24.1 nl/min; range, 1.5-207.3 nl/min) only rarely overlapped with the nNO values of healthy control subjects (304.6 6 118.8; 125.5-867.0 nl/min), asthma (267.8 6 103.2; 125.0-589.7 nl/min), or chronic obstructive pulmonary disease (223.7 6 87.1; 109.7-449.1 nl/min); however, there was overlap with cystic fibrosis (134.0 6 73.5; 15.6-386.1 nl/min). The disease-specific nNO cutoff value was defined at 77 nl/minute (sensitivity, 0.98; specificity, .0.999). At six other sites, this cutoff identified 70 of the 71 (98.6%) participants with confirmed PCD.Conclusions: Using a standardized protocol in multicenter studies, nNO measurement accurately identifies individuals with PCD, and supports its usefulness as a test to support the clinical diagnosis of PCD.

Rationale: The relationship between clinical phenotype of childhood primary ciliary dyskinesia (PCD) and ultrastructural defects and genotype is poorly defined.Objectives: To delineate clinical features of childhood PCD and their associations with ultrastructural defects and genotype.Methods: A total of 118 participants younger than 19 years old with PCD were evaluated prospectively at six centers in North America using standardized procedures for diagnostic testing, spirometry, chest computed tomography, respiratory cultures, and clinical phenotyping.Measurements and Main Results: Clinical features included neonatal respiratory distress (82%), chronic cough (99%), and chronic nasal congestion (97%). There were no differences in clinical features or respiratory pathogens in subjects with outer dynein arm (ODA) defects (ODA alone; n = 54) and ODA plus inner dynein arm (IDA) defects (ODA 1 IDA; n = 18) versus subjects with IDA and central apparatus defects with microtubular disorganization (IDA/ CA/MTD; n = 40). Median FEV 1 was worse in the IDA/CA/MTD group (72% predicted) versus the combined ODA groups (92% predicted; P = 0.003). Median body mass index was lower in the IDA/ CA/MTD group (46th percentile) versus the ODA groups (70th percentile; P = 0.003). For all 118 subjects, median number of lobes with bronchiectasis was three and alveolar consolidation was two. However, the 5-to 11-year-old IDA/CA/MTD group had more lobes of bronchiectasis (median, 5; P = 0.0008) and consolidation (median, 3; P = 0.0001) compared with the ODA groups (median, 3 and 2, respectively). Similar findings were observed when limited to participants with biallelic mutations.Conclusions: Lung disease was heterogeneous across all ultrastructural and genotype groups, but worse in those with IDA/ CA/MTD ultrastructural defects, most of whom had biallelic mutations in CCDC39 or CCDC40.

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