We examined the in vivo immune response of infants to natural respiratory syncytial virus (RSV) infection through analysis of cytokine levels in nasal lavage fluid and stimulated peripheral blood mononuclear cells. Eighty-eight babies with at least one parent with atopy and asthma were prospectively studied through their first winter. Twenty-eight infants had an upper respiratory tract infection where RSV was detected, of whom nine developed signs of acute bronchiolitis. Nasal lavage specimens were assayed for interferon-gamma, interleukin (IL)-4, IL-10, and IL-12 and the RSV load determined by quantitative polymerase chain reaction. Messenger RNA (mRNA) was extracted from stimulated peripheral blood mononuclear cells and interferon-gamma, IL-4, IL-12, and IL-18 mRNA levels determined by polymerase chain reaction. Cytokine profiles were analyzed in relation to clinical outcome. The IL-4/interferon-gamma ratio for infants with acute bronchiolitis was elevated in nasal lavage fluid on both Days 1-2 (p = 0.014) and Days 5-7 (p = 0.001) of the illness compared with infants with upper respiratory tract infection alone. Those with acute bronchiolitis demonstrated a higher IL-10/IL-12 ratio (p = 0.0015) on Days 1-2. IL-18 mRNA levels were reduced (p = 0.019) and the IL-4/interferon-gamma ratio elevated (p = 0.01) in stimulated peripheral blood mononuclear cells from infants with acute bronchiolitis. There was no difference in initial RSV load. These data strongly implicate excess type 2 and/or deficient type 1 immune responses in the pathogenesis of RSV bronchiolitis.

Background: The fractional concentration of nitric oxide (NO) in exhaled breath (Fe NO ) is increased in asthma. There is a general assumption that NO synthase (NOS) 2 in epithelium is the main source of NO in exhaled breath. However, there is no direct evidence to support the assumption and data from animal models suggest that non-inducible NOS systems have important roles in determining airway reactivity, regulating inflammation, and might contribute significantly to NO measured in exhaled breath. Methods: Bronchial epithelial cells were obtained from healthy, atopic, and asthmatic children by nonbronchoscopic brushing. Exhaled NO (Fe NO ) was measured directly using a fast response chemiluminescence NO analyser. RNA was extracted from the epithelial cells and real time polymerase chain reaction was used to determine the expression of NOS isoenzymes. NOS2 was examined in macrophages and epithelial cells by immunohistochemistry. Results: NOS1 mRNA was not detectable. NOS3 mRNA was detected in 36 of 43 samples at lower levels than NOS2 mRNA which was detectable in all samples. The median Fe NO was 15.5 ppb (95% CI 10 to 18.1). There was a significant correlation between Fe NO and NOS2 expression (R = 0.672, p,0.001). All epithelial cells exhibited NOS2 staining, whereas staining in the macrophages was variable and not related to phenotype. Conclusions: Only NOS2 expression was associated with Fe NO in respiratory epithelial cells obtained from children (R = 0.672; p,0.001). This suggests that Fe NO variability is largely determined by epithelial NOS2 expression with little contribution from other isoforms.

Despite aggressive antibiotic therapy, bronchopulmonary colonization by Pseudomonas aeruginosa causes persistent morbidity and mortality in cystic fibrosis (CF). Chronic P. aeruginosa infection in the CF lung is associated with structured, antibiotic-tolerant bacterial aggregates known as biofilms. We have demonstrated the effects of non-bactericidal, low-dose nitric oxide (NO), a signaling molecule that induces biofilm dispersal, as a novel adjunctive therapy for P. aeruginosa biofilm infection in CF in an ex vivo model and a proof-of-concept double-blind clinical trial. Submicromolar NO concentrations alone caused disruption of biofilms within ex vivo CF sputum and a statistically significant decrease in ex vivo biofilm tolerance to tobramycin and tobramycin combined with ceftazidime. In the 12-patient randomized clinical trial, 10 ppm NO inhalation caused significant reduction in P. aeruginosa biofilm aggregates compared with placebo across 7 days of treatment. Our results suggest a benefit of using low-dose NO as adjunctive therapy to enhance the efficacy of antibiotics used to treat acute P. aeruginosa exacerbations in CF. Strategies to induce the disruption of biofilms have the potential to overcome biofilm-associated antibiotic tolerance in CF and other biofilm-related diseases.

Picornaviruses are the predominant cause of community-acquired respiratory tract infection in the first year of life. Large prospective community-based studies will be needed to fully evaluate the contribution of picornaviruses, both in isolation and in combination with other respiratory pathogens, to the various clinical syndromes of respiratory infection observed during infancy.

Rationale The triple-combination regimen elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to be safe and efficacious in children aged 6 through 11 years with cystic fibrosis and at least one F508del-CFTR allele in a phase 3, open-label, single-arm study. Objectives To further evaluate the efficacy and safety of ELX/TEZ/IVA in children 6 through 11 years of age with cystic fibrosis heterozygous for F508del and a minimal function CFTR mutation ( F /MF genotypes) in a randomized, double-blind, placebo-controlled phase 3b trial. Methods Children were randomized to receive either ELX/TEZ/IVA ( n = 60) or placebo ( n = 61) during a 24-week treatment period. The dose of ELX/TEZ/IVA administered was based on weight at screening, with children <30 kg receiving ELX 100 mg once daily, TEZ 50 mg once daily, and IVA 75 mg every 12 hours, and children ⩾30 kg receiving ELX 200 mg once daily, TEZ 100 mg once daily, and IVA 150 mg every 12 hours (adult dose). Measurements and Main Results The primary endpoint was absolute change in lung clearance index 2.5 from baseline through Week 24. Children given ELX/TEZ/IVA had a mean decrease in lung clearance index 2.5 of 2.29 units (95% confidence interval [CI], 1.97–2.60) compared with 0.02 units (95% CI, −0.29 to 0.34) in children given placebo (between-group treatment difference, −2.26 units; 95% CI, −2.71 to −1.81; P < 0.0001). ELX/TEZ/IVA treatment also led to improvements in the secondary endpoint of sweat chloride concentration (between-group treatment difference, −51.2 mmol/L; 95% CI, −55.3 to −47.1) and in the other endpoints of percent predicted FEV 1 (between-group treatment difference, 11.0 percentage points; 95% CI, 6.9–15.1) and Cystic Fibrosis Questionnaire-Revised Respiratory domain score (between-group treatment difference, 5.5 points; 95% CI, 1.0–10.0) compared with placebo from baseline through Week 24. The most common adverse events in children receiving ELX/TEZ/IVA were headache and cough (30.0% and 23.3%, respectively); most adverse events were mild or moderate in severity. Conclusions In this first randomized, controlled study of a cystic fibrosis transmembrane conductance regulator modulator conducted in children 6 through 11 years of age with F /MF genotypes, ELX/TEZ/IVA treatment led to significant improvements in lung function, as well as robust improvements in respiratory symptoms and cystic fibrosis transmembrane conductance regulator function. ELX/TEZ/IVA was generally safe and well tolerated in this pediatric population with no new safety findings.

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Antibiotic treatment directed at P. aeruginosa has an additional significant impact on non-pseudomonal, co-colonising species.

FENO-guided ICS titration does not appear to reduce corticosteroid usage or exacerbation frequency in paediatric outpatients with moderate to severe asthma. This may reflect limitations in FENO-driven management algorithms, as there are now concerns that FENO levels relate to atopy as much as they relate to asthma control.