Exhaled nitrogen oxides and carbon monoxide in asthma and cystic fibrosis : Markers of Inflammation?

Background: Exhaled markers of airway inflammation have attracted much interest as potential tools for monitoring the bronchial inflammation of respiratory disease. Exhaled nitric oxide (NO), its metabolites nitrite and nitrate in breath condensate (EBC), and exhaled carbon monoxide (CO), have been suggested for this purpose. However, their site of origin has not been fully investigated and the enterosalivary circuit of nitrate, with its possible off springs of nitrite and NO, could constitute a confounding factor. Exhaled NO is increased in asthma, but its levels are unexpectedly low in cystic fibrosis (CF). Exhaled CO and EBC nitrite are instead elevated in both these conditions, where the latter could reflect an increased NO activity also in CF. Aims: The aim of study I was to compare the profiles and possible origins of exhaled NO and CO in children and adults with asthma and CF by the introduction of highly specific infrared technique and controlled flow rate for CO measurements. In study II we wanted to investigate the possible influence from salivary formation of NO on measurements in exhaled air. Study III was designed to evaluate the postulated link between nitrite and nitrate in EBC and exhaled NO in children with allergic asthma, also in relation to other disease markers. In study IV, these EBC metabolites were examined in relation to the salivary contents of the same in subjects with CF, to evaluate a possible influence from oral bacteria, which may reduce nitrate to nitrite. Methods: In study I, 56 children and adults with asthma, 16 with allergic rhinitis, 9 CF patients and 30 age-matched controls performed exhaled CO and NO measurements with two different flow rates. Study II was performed on ten healthy adults who ingested 240 mg of nitrate on empty stomach for consecutive measurements of exhaled and nasal NO and salivary nitrate and nitrite, followed by a series of mouthwash experiments. In study III, 27 children with allergic asthma and 21 age-matched controls were examined with exhaled NO, EBC nitrite and nitrate, blood eosinophils, spirometry and methacholine challenge. Whereas EBC and salivary nitrite and nitrate, together with exhaled NO, were studied before and after mouthwash with the anti-bacterial solution of chlorhexidine in15 CF patients and 15 controls in study IV. Results: Exhaled CO, was in contrast to NO, not elevated in asthma and allergic rhinitis, and both markers were negative in CF. The change of exhalation flow rate did, furthermore, not affect the levels of CO but gave a proportional change of NO. The intake of nitrate resulted in a 150% increase of exhaled NO after 2 h, whereas nasal NO was unaffected. This increase was largely abolished by chlorhexidine mouthwash, which also decreased baseline NO levels with 30%. EBC nitrite, but not nitrate, was significantly elevated in the children with allergic asthma, but no correlation was found to increased levels of NO or other disease markers. EBC nitrite was also significantly higher in the CF patients, as was salivary nitrite, but these levels were almost eradicated by chlorhexidine, which in addition reduced exhaled NO more in CF than in controls. Conclusions: The flow independence of exhaled CO proves that it has its origin in the alveoli and is therefore not a suitable marker for bronchial inflammation. There is a substantial salivary contribution to exhaled NO from the non-enzymatic reduction of nitrite, which can be greatly increased by the intake of nitrate-rich foods. There is also a most prominent salivary contribution to EBC nitrite in CF, and probably even in asthma, which indicates an altered activity of oral bacteria in these conditions, rather than increased NO metabolism, as an explanation for their higher levels of EBC nitrite

Oral bacteria – The missing link to ambiguous findings of exhaled nitrogen oxides in cystic fibrosis

SummaryBackgroundNitrite in exhaled breath condensate (EBC) has been shown to be elevated in cystic fibrosis (CF), while exhaled nitric oxide (FENO) is paradoxically low. This has been argued to reflect increased metabolism of NO while its diffusion is obstructed by mucus. However, we wanted to study the possible influence of salivary nitrite and bacterial nitrate reduction on these parameters in CF patients by the intervention of an anti-bacterial mouthwash.MethodsEBC and saliva were collected from 15 CF patients (10–43 years) and 15 controls (9–44 years) before and 5min after a 30s chlorhexidine mouthwash, in parallel with measurements of FENO. Nitrite and nitrate concentrations were measured fluorometrically.ResultsEBC nitrite, but not nitrate, was significantly higher in the CF patients (median 3.6 vs 1.3μM in controls, p<0.05) and decreased after mouthwash in both groups (3.6–1.4μM, p<0.01; 1.3–0.5μM, p<0.01). Salivary nitrite correlated significantly to EBC nitrite (r=0.60, p<0.001) and decreased correspondingly after chlorhexidine, whereas salivary nitrate increased. FENO was lower in CF and the difference between patients and controls was accentuated after mouthwash (5.4 vs 8.4ppb in controls, p<0.05).ConclusionEBC nitrite mainly originates in the pharyngo-oral tract and its increase in CF is possibly explained by a regional change in bacterial activity. The limited lower airway contribution supports the view of a genuinely impaired formation and metabolism of NO in CF, rather than poor diffusion of the molecule

ERNICA Consensus Conference on the Management of Patients with Long-Gap Esophageal Atresia: Perioperative, Surgical, and Long-Term Management

Introduction Evidence supporting best practice for long-gap esophageal atresia is limited. The European Reference Network for Rare Inherited Congenital Anomalies (ERNICA) organized a consensus conference on the management of patients with long-gap esophageal atresia based on expert opinion referring to the latest literature aiming to provide clear and uniform statements in this respect. Materials and Methods Twenty-four ERNICA representatives from nine European countries participated. The conference was prepared by item generation, item prioritization by online survey, formulation of a final list containing items on perioperative, surgical, and long-term management, and literature review. The 2-day conference was held in Berlin in November 2019. Anonymous voting was conducted via an internet-based system using a 1 to 9 scale. Consensus was defined as ≥75% of those voting scoring 6 to 9. Results Ninety-seven items were generated. Complete consensus (100%) was achieved on 56 items (58%), e.g., avoidance of a cervical esophagostomy, promotion of sham feeding, details of delayed anastomosis, thoracoscopic pouch mobilization and placement of traction sutures as novel technique, replacement techniques, and follow-up. Consensus ≥75% was achieved on 90 items (93%), e.g., definition of long gap, routine pyloroplasty in gastric transposition, and avoidance of preoperative bougienage to enable delayed anastomosis. Nineteen items (20%), e.g., methods of gap measurement were discussed controversially (range 1-9). Conclusion This is the first consensus conference on the perioperative, surgical, and long-term management of patients with long-gap esophageal atresia. Substantial statements regarding esophageal reconstruction or replacement and follow-up were formulated which may contribute to improve patient care

Pathway discovery using transcriptomic profiles in adult-onset severe asthma

Background: Adult-onset severe asthma is characterized by highly symptomatic disease despite high-intensity asthma treatments. Understanding of the underlying pathways of this heterogeneous disease is needed for the development of targeted treatments. Gene set variation analysis is a statistical technique used to identify gene profiles in heterogeneous samples. Objective: We sought to identify gene profiles associated with adult-onset severe asthma. Methods: This was a cross-sectional, observational study in which adult patients with adult-onset of asthma (defined as starting at age >18 years) as compared with childhood-onset severe asthma (<18 years) were selected from the U-BIOPRED cohort. Gene expression was assessed on the total RNA of induced sputum (n 5 83), nasal brushings (n 5 41), and endobronchial brushings (n 5 65) and biopsies (n 5 47) (Affymetrix HT HG-U1331 PM). Gene set variation analysis was used to identify differentially enriched predefined gene signatures of leukocyte lineage, inflammatory and induced lung injury pathways. Results: Significant differentially enriched gene signatures in patients with adult-onset as compared with childhood-onset severe asthma were identified in nasal brushings (5 signatures), sputum (3 signatures), and endobronchial brushings (6 signatures). Signatures associated with eosinophilic airway inflammation, mast cells, and group 3 innate lymphoid cells were more enriched in adult-onset severe asthma, whereas signatures associated with induced lung injury were less enriched in adult-onset severe asthma. Conclusions: Adult-onset severe asthma is characterized by inflammatory pathways involving eosinophils, mast cells, and group 3 innate lymphoid cells. These pathways could represent useful targets for the treatment of adult-onset severe asthma

U-BIOPRED clinical adult asthma clusters linked to a subset of sputum omics

Background: Asthma is a heterogeneous disease in which there is a differential response to asthma treatments. This heterogeneity needs to be evaluated so that a personalized management approach can be provided. Objectives: We stratified patients with moderate-to-severe asthma based on clinicophysiologic parameters and performed an omics analysis of sputum. Methods: Partition-around-medoids clustering was applied to a training set of 266 asthmatic participants from the European Unbiased Biomarkers for the Prediction of Respiratory Diseases Outcomes (U-BIOPRED) adult cohort using 8 prespecified clinic-physiologic variables. This was repeated in a separate validation set of 152 asthmatic patients. The clusters were compared based on sputum proteomics and transcriptomics data. Results: Four reproducible and stable clusters of asthmatic patients were identified. The training set cluster T1 consists of patients with well-controlled moderate-to-severe asthma, whereas cluster T2 is a group of patients with late-onset severe asthma with a history of smoking and chronic airflow obstruction. Cluster T3 is similar to cluster T2 in terms of chronic airflow obstruction but is composed of nonsmokers. Cluster T4 is predominantly composed of obese female patients with uncontrolled severe asthma with increased exacerbations but with normal lung function. The validation set exhibited similar clusters, demonstrating reproducibility of the classification. There were significant differences in sputum proteomics and transcriptomics between the clusters. The severe asthma clusters (T2, T3, and T4) had higher sputum eosinophilia than cluster T1, with no differences in sputum neutrophil counts and exhaled nitric oxide and serum IgE levels. Conclusion: Clustering based on clinicophysiologic parameters yielded 4 stable and reproducible clusters that associate with different pathobiological pathways