Exhaled nitric oxide in pulmonary diseases: a comprehensive review

Sources, trigger points, and effect size of associations between PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and fractional exhaled nitric oxide (FeNO): A panel study with 16 follow-up visits over 4 years

Exposure to fine particulate matter (PM2.5) is a significant concern for respiratory health. However, the sources, trigger points, and effect size of specific associations between PM2.5 components, particularly polycyclic aromatic hydrocarbons (PAHs) and the airway inflammatory marker fractional exhaled nitric oxide (FeNO) have not been fully explored. In this study, 69 healthy college students were enrolled and followed up 16 times from 2014 to 2018. Individual FeNO was measured and ambient air PM2.5 samples were collected for 7 consecutive days before each follow-up. PAHs were quantified using Gas Chromatography-Mass Spectrometry. Linear mixed-effect regression models were employed to evaluate the associations between PM2.5-bound PAHs and FeNO. Additionally, PMF (Positive Matrix Factorization) was utilized to identify sources of PM2.5-bound PAHs and assess their impact on FeNO. Throughout the study, the average (SD) of ΣPAHs concentrations was 78.50 (128.9) ng/m3. PM2.5 and PM2.5-bound PAHs were significantly associated with FeNO at various lag days. Single-day lag analyses revealed maximum effects of PM2.5 on FeNO, with an increase of 7.71% (95% CI: 4.67%, 10.83%) per interquartile range (IQR) (48.10 μg/m3) increase of PM2.5 at lag2, and ΣPAHs showed a maximum elevation in FeNO of 6.40% (95% CI: 2.33%, 10.63%) at lag4 per IQR (57.39 ng/m3) increase. Individual PAHs exhibited diversity peak effects on FeNO at lag3 (6 of 17), lag4 (9 of 17) in the single-day model, and lag0-5 (8 of 17) (from lag0-1 to lag0-6) in the cumulative model. Source apportionment indicated coal combustion as the primary contributor (accounting for 30.7%). However, a maximum effect on FeNO (an increase of 21.57% (95% CI: 13.58%, 30.13%) per IQR increase) was observed with traffic emissions at lag4. The findings imply that strategic regulation of particular sources of PAHs, like traffic emissions, during specific periods could significantly contribute to safeguarding public health.

Contribution of small airway inflammation to the development of COPD

BACKGROUND

Little attention has been paid to the pathophysiological changes in the natural history of chronic obstructive pulmonary disease (COPD). The destructions of the small airways were visualized on thoracic micro-computed tomography scan. We investigated whether small airway inflammation (SAI) was the risk for the development of COPD.

METHODS

A total of 1062 patients were enrolled and analyzed in the study. The partitioned airway inflammation was determined by exhaled nitric oxide (NO) of FnNO, FeNO50, FeNO200, and calculated CaNOdual. Both FeNO200 and CaNOdual were compared to detect the promising predictor for peripheral airway/alveolar inflammation in COPD. The correlation between exhaled NO and white cell classification was evaluated to determine the inflammation type during the development of COPD.

RESULTS

Exhaled NO levels (FnNO, FeNO50, FeNO200, and CaNOdual) were the highest in the COPD group compared with all other groups. Furthermore, compared with controls, exhaled NO levels (FeNO50, FeNO200, and CaNOdual) were also significantly higher in the emphysema, chronic bronchitis, and smoking groups. FeNO200 was found to be a promising predictor for peripheral airway/alveolar inflammation (area under the curve [AUC] of the receiver operating characteristic [ROC] curve, area under the curve [AUC] = 0.841) compared with CaNOdual (AUC ROC = 0.707) in COPD. FeNO200 was the main risk factor (adjusted odds ratio, 2.191; 95% CI, 1.797-2.671; p = 0.002) for the development of COPD. The blood eosinophil and basophil levels were correlated with FeNO50 and FeNO200.

CONCLUSION

The complete airway inflammations were shown in COPD, whereas SAI was the main risk factor for the development of COPD, which might relate to eosinophil and basophil levels.

Fraction of exhaled nitric oxide is higher in liver transplant recipients than in controls from the general population: a cohort study

Background

Fraction of exhaled nitric oxide with an expiratory flow of 50 mL/s (FENO50) is a biomarker of eosinophilic airway inflammation. Liver transplant recipients have an increased risk of pulmonary infections, but little is known about the burden of chronic pulmonary diseases in this group. We aimed to assess the prevalence of elevated FENO50 in liver transplant recipients and compare it to controls from the general population.

Methods

FENO50 was measured in 271 liver transplant recipients from The Danish Comorbidity in Liver Transplant Recipients (DACOLT) study and 1,018 age- and sex-matched controls from The Copenhagen General Population Study (CGPS). Elevated FENO50 was defined as ≥25 or ≥50 parts per billion (ppb). The analyses were adjusted for known and suspected confounders.

Results

The median age of the liver transplant recipients was 55 years (interquartile range (IQR) 46-64), and 58% were men. The liver transplant recipients had a higher median FENO50 than the controls [16 ppb (IQR 10-26) vs. 13 ppb (IQR 8-18.), p < 0.001]. Furthermore, the liver transplant recipients had a higher prevalence of elevated FENO50 (for FENO50 ≥25 ppb 27% vs. 11%, p < 0.001 and ≥50 ppb 4% vs. 2%, p = 0.02). The results were similar after adjusting for age, sex, smoking status, use of airway medication, and blood eosinophil counts [the adjusted odds ratio (OR) for FENO50 ≥25 ppb was 3.58 (95% CI: 2.50-5.15, p < 0.0001) and the adjusted OR for FENO50 ≥50 ppb was 3.14 (95% CI: 1.37-7.20, p = 0.007)].

Conclusion

The liver transplant recipients had elevated FENO50, implying increased eosinophilic airway inflammation. The clinical impact of this finding needs further investigation.

Exhaled nitric oxide is associated with inflammatory biomarkers and risk of acute respiratory exacerbations in children with HIV-associated chronic lung disease

OBJECTIVES

Chronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels.

METHODS

Individuals aged 6-19 years with HIV-associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo-controlled randomized trial investigating the effect of 48-week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels.

RESULTS

In total, 172 participants were included in this sub-study, 86 from the placebo group and 86 from the azithromycin group. Participants experiencing at least one ARE during follow-up had significantly higher eNO levels at baseline than participants who did not (geometric mean ratio 1.13, 95% confidence interval [CI] 1.03-1.24, p = 0.015), adjusted for trial arm, age, sex and history of tuberculosis. Matrix metalloproteinase (MMP)-3, -7, and -10 were significantly associated with higher baseline eNO levels. At 48 weeks, azithromycin treatment did not affect eNO levels (geometric mean ratio 0.86, 95% CI 0.72-1.03, p = 0.103).

CONCLUSION

Higher baseline eNO levels were a risk factor for ARE. eNO was associated with proinflammatory biomarkers previously found to contribute to the development of chronic lung disease. The potential use of eNO as a marker of inflammation and risk factor for ARE in HIV-associated chronic lung disease needs further investigation.

[Biologic agents in COPD management]

Chronic obstructive pulmonary disease (COPD) is a frequently occurring disease entailing high morbidity and mortality, and relevant therapeutic resources are limited. As is the case with asthma, the current trend consists in the phenotyping of COPD patients so as to develop personalized medicine tailored to a given individual's inflammatory profile. The aim of this review is to summarize the role of biologic agents in the management of COPD, taking into consideration not only COPD pathophysiology, but also the previously published studies and the relatively encouraging prospects for the future.

Effects of Endoscopic Sinus Surgery for Eosinophilic Chronic Rhinosinusitis on Respiratory Functions and FeNO Production in the Lower Respiratory Tract

OBJECTIVE

To confirm the relevance of upper and lower airway inflammation in eosinophilic chronic rhinosinusitis (ECRS), the effects of endoscopic sinus surgery (ESS) on lower airway functions and inflammation need to be examined in ECRS patients.

METHODS

Chronic rhinosinusitis patients with nasal polyps (25 non-ECRS, 28 ECRS) were enrolled. The 12 patients in the ECRS group had comorbid asthma, in contrast to none in the non-ECRS group. We divided ECRS patients into 2 groups of ECRS with and without asthma. Clinical markers, including fraction of exhaled nitric oxide (FeNO), respiratory functions, and the Asthma Control Test (ACT) questionnaire, were investigated before and after ESS.

RESULTS

The FeNO levels in the ECRS with asthma group decreased after ESS. The mean FeNO levels in this group were 56.3 ppb before ESS and 24.9, 25.1, 25.0, and 15.5 ppb 1, 2, 3, and 4 months, respectively, after ESS. The mean forced expiratory rates in 1 second before and after ESS were 67.6% and 73.0%, respectively. The mean maximal expiratory flow rates at 50% of the vital capacity before and after ESS were 45.8% and 58.0%, respectively. Significant differences were observed in respiratory functions before and after ESS. The mean ACT scores in the ECRS with asthma group before and after ESS were 17.5 and 23.5, respectively. The ACT scores were significantly higher after than before ESS.

CONCLUSIONS

The present results indicate that ECRS and bronchial asthma are common eosinophilic airway inflammatory diseases, and ESS for eosinophilic sinusitis may improve lower airway function.

Gasotransmitter Research Advances in Respiratory Diseases

Significance: Gasotransmitters are small gas molecules that are endogenously generated and have well-defined physiological functions. The most well-defined gasotransmitters currently are nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S), while other potent gasotransmitters include ammonia, methane, cyanide, hydrogen gas, and sulfur dioxide. Gasotransmitters play a role in various respiratory diseases such as asthma, chronic obstructive pulmonary disease, obstructive sleep apnea, lung infection, bronchiectasis, cystic fibrosis, primary ciliary dyskinesia, and COVID-19. Recent Advances: Gasotransmitters can act as biomarkers that facilitate disease diagnosis, indicate disease severity, predict disease exacerbation, and evaluate disease outcomes. They also have cell-protective properties, and many studies have been conducted to explore their pharmacological applications. Innovative drug donors and drug delivery methods have been invented to amplify their therapeutic effects. Critical Issues: In this article, we briefly reviewed the physiological and pathophysiological functions of some gasotransmitters in the respiratory system, the progress in detecting exhaled gasotransmitters, as well as innovative drugs derived from these molecules. Future Directions: The current challenge for gasotransmitter research includes further exploring their physiological and pathological functions, clarifying their complicated interactions, exploring suitable drug donors and delivery devices, and characterizing new members of gasotransmitters. Antioxid. Redox Signal. 40, 168-185.

Managing Asthma During Pregnancy and the Postpartum Period

Asthma is one of the most common chronic diseases in pregnancy and is associated with adverse perinatal outcomes. Asthma symptoms worsen in approximately 40% of women, and exacerbations requiring medical intervention occur in at least 20% of women. Factors associated with exacerbation and worsening asthma include multiparity, obesity, Black race, exacerbations before pregnancy, and poor asthma control. Exacerbations are associated with further increased risks for poor perinatal outcomes, including low birth weight, preterm birth, and small for gestational age (SGA) status, as well as an increase in the development of asthma in early childhood. Common medications used for asthma, including short-acting β-agonists and inhaled corticosteroids, are considered safe to use in pregnancy. Whereas guidelines generally suggest traditional step therapy for managing asthma in pregnancy, there are alternative models of care and management approaches that may be effective in pregnancy, but require more research. These include single-inhaler maintenance and reliever therapy, treatment adjustment with FeNO, treatable traits personalized medicine approaches, and telemedicine. Little is known about changes to asthma in the postpartum period. However, low adherence to medication and the potential effects of postpartum depression on asthma exacerbation risk warrant further research.

Association of inflammatory cytokines with obesity and pulmonary function testing

BACKGROUND

The World Health Organization (WHO) reported that the prevalence of obesity in the Kingdom of Saudi Arabia (KSA) is 33.7% (women 39.5% and men 29.5%), respectively. The effects of obesity on airway inflammation and respiratory mechanics as well as the function of adipose tissue has a key role in the development of various lung diseases. Therefore, this study aimed to compare the level of cytokines between obese (BMI ≥ 30) and non-obese participants and to assess their association with BMI, airways inflammation and pulmonary function.

METHOD

One-hundred and seven non-smoking students (18-25 years of age) were recruited using convenience sampling technique for comparative cross-sectional study. Of them, 80 students were eligible and included in the analysis; 54 were non-obese (BMI<30) and 26 were obese (BMI ≥ 30). All the participants underwent anthropometric measurements, fractional exhaled nitric oxide (FeNO) measurement, spirometry and cytokines measurement (IL-6, IL-1β, GM-CSF, IL-7, IL-8 and IL-10). Measurements were compared between obese and non-obese groups. Then a correlation test was made between pro- and anti-inflammatory cytokines with BMI, pulmonary function test finding and FeNO.

RESULTS

The prevalence of obesity was 32.5% in the study population. Levels of pro-inflammatory cytokine IL-6 levels was significantly higher in obese than non-obese participants (p = 0.044). The level of FeNO log was significantly higher in obese participants than non-obese (p = 0.002). The pro-inflammatory cytokine IL-6 showed positive correlation with BMI while GMCSF showed negative correlation with FVC (p<0.05).

CONCLUSION

The levels of pro-inflammatory cytokine IL-6 was found to be significantly higher in obese participants than non-obese participants. Furthermore, it showed positive correlation with BMI whereas pro-inflammatory cytokine GMCSF showed negative correlation with FVC.

Exhaled Nitric Oxide and Olfactory Dysfunction in Patients with Asthma: Association with Chronic Rhinosinusitis

Objectives: Olfactory dysfunction is a clinical sign that is important to detect with coexistent upper airway comorbidities in patients with asthma. This study aimed to investigate the etiology of olfactory dysfunction in patients with asthma and the relationship between fractional exhaled nitric oxide (FeNO) levels. Materials and Methods: This study included 47 asthma patients who were evaluated for olfactory dysfunction at Hiroshima University Hospital between 2012 and 2020. The etiologies of olfactory dysfunction were evaluated, and they were classified according to the FeNO levels of patients with asthma. Results: Olfactory dysfunction was observed in 30 patients with asthma, with chronic rhinosinusitis (77%) being the most prevalent etiology. Eosinophilic chronic rhinosinusitis (ECRS) was the most prevalent etiology of olfactory dysfunction in asthma patients with high FeNO levels (≥25 ppb), while non-eosinophilic chronic rhinosinusitis (NCRS) was the most prevalent etiology in asthma patients with low FeNO levels (<25 ppb). Additionally, the prevalence of ECRS was significantly higher in asthma patients with olfactory dysfunction and high FeNO levels (74%) than in those with either high FeNO levels or olfactory dysfunction and those with low FeNO levels and no olfactory dysfunction (12% and 9%, respectively). Conclusions: We found that ECRS was the predominant cause of olfactory dysfunction in patients with high FeNO levels, while NCRS was more common in those with low FeNO levels. The present study showed that both ECRS and NCRS are common etiologies of olfactory dysfunction in patients with asthma. Additionally, this study supports the link between upper and lower airway inflammation in patients with asthma complicated with olfactory dysfunction.

Investigating the Effects of a New Peptide, Derived from the Enterolobium contortisiliquum Proteinase Inhibitor (EcTI), on Inflammation, Remodeling, and Oxidative Stress in an Experimental Mouse Model of Asthma-Chronic Obstructive Pulmonary Disease Overlap (ACO)

The synthesized peptide derived from Enterolobium contortisiliquum (pep3-EcTI) has been associated with potent anti-inflammatory and antioxidant effects, and it may be a potential new treatment for asthma-COPD overlap-ACO). Purpose: To investigate the primary sequence effects of pep3-EcTI in an experimental ACO. BALB/c mice were divided into eight groups: SAL (saline), OVA (ovalbumin), ELA (elastase), ACO (ovalbumin + elastase), ACO-pep3-EcTI (treated with inhibitor), ACO-DX (treated with dexamethasone), ACO-DX-pep3-EcTI (treated with dexamethasone and inhibitor), and SAL-pep3-EcTI (saline group treated with inhibitor). We evaluated the hyperresponsiveness to methacholine, exhaled nitric oxide, bronchoalveolar lavage fluid (BALF), mean linear intercept (Lm), inflammatory markers, tumor necrosis factor (TNF-α), interferon (IFN)), matrix metalloproteinases (MMPs), growth factor (TGF-β), collagen fibers, the oxidative stress marker inducible nitric oxide synthase (iNOS), transcription factors, and the signaling pathway NF-κB in the airways (AW) and alveolar septa (AS). Statistical analysis was conducted using one-way ANOVA and t-tests, significant when p < 0.05. ACO caused alterations in the airways and alveolar septa. Compared with SAL, ACO-pep3-EcTI reversed the changes in the percentage of resistance of the respiratory system (%Rrs), the elastance of the respiratory system (%Ers), tissue resistance (%Gtis), tissue elastance (%Htis), airway resistance (%Raw), Lm, exhaled nitric oxide (ENO), lymphocytes, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, TNF-α, INF-γ, MMP-12, transforming growth factor (TGF)-β, collagen fibers, and iNOS. ACO-DX reversed the changes in %Rrs, %Ers, %Gtis, %Htis, %Raw, total cells, eosinophils, neutrophils, lymphocytes, macrophages, IL-1β, IL-6, IL-10, IL-13, IL-17, TNF-α, INF-γ, MMP-12, TGF-β, collagen fibers, and iNOS. ACO-DX-pep3-EcTI reversed the changes, as was also observed for the pep3-EcTI and the ACO-DX-pep3-EcTI. Significance: The pep3-EcTI was revealed to be a promising strategy for the treatment of ACO, asthma, and COPD.

The Effect of the COVID-19 Pandemic on Self-Reported Health Status and Smoking and Drinking Habits in the General Urban Population

The coronavirus disease 2019 pandemic created a significant crisis in global health. The aim of the study was to compare the impact of the COVID-19 pandemic on self-rated health status and smoking and alcohol habits. The Bialystok PLUS cohort study was conducted in 2018-2022. A total of 1222 randomly selected city residents were examined and divided into two groups: before and during the COVID-19 pandemic. The participants' lifestyle habits and medical history were collected from self-reported questionnaires. The Alcohol Use Disorders Identification Test (AUDIT) and the Fagerström Test for Nicotine Dependence (FTND) were used to assess the degree of alcohol and nicotine dependence. The survey revealed a reduced frequency of reported allergies vs. an increased frequency of reported sinusitis and asthma; increased incidence of declared hypercholesterolemia and visual impairment; a reduced number of cigarettes smoked per day, lower FTND score, and a greater desire to quit smoking in the next six months; and an increase in hs-CRP and FeNO levels in the population during the pandemic compared to the pre-pandemic population. The COVID-19 pandemic had a measurable impact on the general population's prevalence of certain medical conditions and lifestyle habits. Further research should continue to examine the long-term health implications of the pandemic.

Targeting Type 2 Inflammation and Epithelial Alarmins in Chronic Obstructive Pulmonary Disease: A Biologics Outlook

Chronic obstructive pulmonary disease (COPD) is a complex, heterogeneous, progressive inflammatory airway disease associated with a significant impact on patients' lives, including morbidity and mortality, and significant healthcare costs. Current pharmacologic strategies, including first- and second-line therapies such as long-acting β2-agonists, long-acting muscarinic antagonists, inhaled corticosteroids, phosphodiesterase-4 inhibitors, and macrolides, provide relief to patients with COPD. However, many patients remain symptomatic, with persistent symptoms and/or acute exacerbations and progressive lung function loss. Although neutrophilic inflammation is the most common type of inflammation in COPD, 20-40% of patients with COPD exhibit type 2 inflammation, with roles for CD4+ (cluster of differentiation 4) T-helper cell type 1 cells, type 2 innate lymphoid cells, eosinophils, and alternatively activated macrophages. On the basis of the current limitations of available therapies, a significant unmet need exists in COPD management, including the need for targeted therapies to address the underlying pathophysiology leading to disease progression, such as type 2 inflammation, as well as biomarkers to help select the patients who would most benefit from the new therapies. Significant progress is being made, with evolving understanding of the pathobiology of COPD leading to novel therapeutic targets including epithelial alarmins. In this review, we describe the current therapeutic landscape in COPD, discuss unmet treatment needs, review the current knowledge of type 2 inflammation and epithelial alarmins in COPD, explore potential biomarkers of type 2 inflammation in COPD, and finally provide a rationale for incorporating therapies targeting type 2 inflammation and epithelial alarmins in COPD. Video Abstract available online at www.atsjournals.org.

Diagnostic role of fractional exhaled nitric oxide in pediatric eosinophilic esophagitis, relationship with gastric and duodenal eosinophils

BACKGROUND

Eosinophilic esophagitis (EoE) is an eosinophilic-predominant inflammation of the esophagus diagnosed by upper endoscopy and biopsies. A non-invasive and cost-effective alternative for management of EoE is being researched. Previous studies assessing utility of fractional exhaled nitric oxide (FeNO) in EoE were low powered. None investigated the contribution of eosinophilic inflammation of the stomach and duodenum to FeNO.

AIM

To assess the utility of FeNO as a non-invasive biomarker of esophageal eosinophilic inflammation for monitoring disease activity.

METHODS

Patients aged 6-21 years undergoing scheduled upper endoscopy with biopsy for suspected EoE were recruited in our observational study. Patients on steroids and with persistent asthma requiring daily controller medication were excluded. FeNO measurements were obtained in duplicate using a chemiluminescence nitric oxide analyzer (NIOX MINO, Aerocrine, Inc.; Stockholm, Sweden) prior to endoscopy. Based on the esophageal peak eosinophil count (PEC)/high power field on biopsy, patients were classified as EoE (PEC ≥ 15) or control (PEC ≤ 14). Mean FeNO levels were correlated with presence or absence of EoE, eosinophil counts on esophageal biopsy, and abnormal downstream eosinophilia in the stomach (PEC ≥ 10) and duodenum (PEC ≥ 20). Wilcoxon rank-sum test, Spearman correlation, and logistic regression were used for analysis. P value < 0.05 was considered significant.

RESULTS

We recruited a total of 134 patients, of which 45 were diagnosed with EoE by histopathology. The median interquartile range FeNO level was 17 parts per billion (11-37, range: 7-81) in the EoE group and 12 parts per billion (8-19, range: 5-71) in the control group. After adjusting for atopic diseases, EoE patients had significantly higher FeNO levels as compared to patients without EoE (Z = 3.33, P < 0.001). A weak yet statistically significant positive association was found between the number of esophageal eosinophils and FeNO levels (r = 0.30, P < 0.005). On subgroup analysis within the EoE cohort, higher FeNO levels were noted in patients with abnormal gastric (n = 23, 18 vs 15) and duodenal eosinophilia (n = 28, 21 vs 14); however, the difference was not statistically significant.

CONCLUSION

After ruling out atopy as possible confounder, we found significantly higher FeNO levels in the EoE cohort than in the control group.

Fractional exhaled nitric oxide in the assessment of exercise-induced bronchoconstriction: A multicenter retrospective analysis of UK-based athletes

INTRODUCTION

Exercise-induced bronchoconstriction (EIB) is not only highly prevalent in people with asthma, but can also occur independently, particularly in athletes. Fractional exhaled nitric oxide (FeNO) is an indirect biomarker of type 2 airway inflammation that has an established role in the assessment and management of asthma. The aim was to evaluate the value of FeNO in the assessment of EIB in athletes.

METHOD

Multicenter retrospective analysis. In total, 488 athletes (male: 76%) performed baseline FeNO, and spirometry pre- and post-indirect bronchial provocation via eucapnic voluntary hyperpnea (EVH). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for established FeNO thresholds-that is, intermediate (≥25 ppb) and high FeNO (≥40 ppb and ≥ 50 ppb)-and were evaluated against objective evidence of EIB (≥10% fall in FEV₁ ). The diagnostic accuracy of FeNO was calculated using receiver operating characteristics area under the curve (ROC-AUC).

RESULTS

Thirty-nine percent of the athletes had a post-EVH fall in FEV₁ consistent with EIB. FeNO values ≥25 ppb, ≥40 ppb, and ≥ 50 ppb were observed in 42%, 23%, and 17% of the cohort, respectively. The sensitivity of FeNO ≥25 ppb was 55%, which decreased to 37% and 27% at ≥40 ppb and ≥ 50 ppb, respectively. The specificity of FeNO ≥25 ppb, ≥40 ppb, and ≥ 50 ppb was 66%, 86%, and 89%, respectively. The ROC-AUC for FeNO was 0.656.

CONCLUSIONS

FeNO ≥40 ppb provides good specificity, that is, the ability to rule-in a diagnosis of EIB. However, due to the poor sensitivity and predictive values, FeNO should not be employed as a replacement for indirect bronchial provocation in athletes.

Biomarkers of Exposure and Potential Harm in Exclusive Users of Nicotine Pouches and Current, Former, and Never Smokers: Protocol for a Cross-sectional Clinical Study

Background

Tobacco harm reduction (THR) aims to reduce the health burden of cigarettes by encouraging smokers to switch to using alternative tobacco or nicotine products. Nicotine pouches (NPs) are smokeless, tobacco-free, oral products that may be beneficial as part of a THR strategy.

Objective

This 2-center, cross-sectional confinement study conducted in Denmark and Sweden aimed to determine whether biomarkers of exposure (BoEs) to tobacco toxicants and biomarkers of potential harm (BoPHs) in exclusive users of NPs show favorable differences compared with current smokers.

Methods

Participants were healthy NP users (target n=100) and current, former, or never smokers (target n=40 each), as confirmed by urinary cotinine and exhaled carbon monoxide concentrations. During a 24-hour confinement period, participants were asked to use their usual product (NP or cigarette) as normal, and BoEs and BoPHs were measured in blood and 24-hour urine samples, with compliance determined using anabasine, anatabine, and N-(2-cyanoethyl)valine. BoEs and BoPHs were compared between NP users and current, former, and never smokers. Urinary total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (BoE to nicotine-derived nitrosamine ketone) and urinary 8-epi-prostaglandin F2α type III, exhaled nitric oxide, blood carboxyhemoglobin, white blood cell count, soluble intercellular adhesion molecule-1, and high-density lipoprotein cholesterol (BoPHs) were evaluated as primary outcomes. Other measures included urinary 11-dehydrothromboxane B2, forced expiratory volume, carotid intima-media thickness, self-reported quality of life, and oral health.

Results

The results of this study were received in mid-2022 and will be published in late 2022 to early 2023.

Conclusions

The results of this study will provide information on toxicant exposure and biomarkers associated with the development of smoking-related diseases among users of NPs compared with smokers, as well as on the potential role of NPs in THR.

Trial Registration

International Standard Randomised Controlled Trial Number (ISRCTN) ISRCTN16988167; https://www.isrctn.com/ISRCTN16988167

International Registered Report Identifier (IRRID)

DERR1-10.2196/39785

Blood Eosinophils and Exhaled Nitric Oxide: Surrogate Biomarkers of Airway Eosinophilia in Stable COPD and Exacerbation

In recent years, tremendous efforts have been devoted to characterizing the inflammatory processes in chronic obstructive pulmonary disease (COPD) in order to provide more personalized treatment for COPD patients. While it has proved difficult to identify COPD-specific inflammatory pathways, the distinction between eosinophilic and non-eosinophilic airway inflammation has gained clinical relevance. Evidence has shown that sputum eosinophil counts are increased in a subset of COPD patients and that these patients are more responsive to oral or inhaled corticosteroid therapy. Due to feasibility issues associated with sputum cell profiling in daily clinical practice, peripheral blood eosinophil counts and fractional exhaled nitric oxide levels have been evaluated as surrogate biomarkers for assessing the extent of airway eosinophilia in COPD patients, both in stable disease and acute exacerbations. The diagnostic value of these markers is not equivalent and depends heavily on the patient’s condition at the time of sample collection. Additionally, the sensitivity and specificity of these tests may be influenced by the patient’s maintenance treatment. Overall, eosinophilic COPD may represent a distinct disease phenotype that needs to be further investigated in terms of prognosis and treatment outcomes.

Pathophysiological Concepts and Management of Pulmonary Manifestation of Pediatric Inflammatory Bowel Disease

Pulmonary manifestation (PM) of inflammatory bowel disease (IBD) in children is a rare condition. The exact pathogenesis is still unclear, but several explanatory concepts were postulated and several case reports in children were published. We performed a systematic Medline search between April 1976 and April 2022. Different pathophysiological concepts were identified, including the shared embryological origin, "miss-homing" of intestinal based neutrophils and T lymphocytes, inflammatory triggering via certain molecules (tripeptide proline-glycine-proline, interleukin 25), genetic factors and alterations in the microbiome. Most pediatric IBD patients with PM are asymptomatic, but can show alterations in pulmonary function tests and breathing tests. In children, the pulmonary parenchyma is more affected than the airways, leading histologically mainly to organizing pneumonia. Medication-associated lung injury has to be considered in pulmonary symptomatic pediatric IBD patients treated with certain agents (i.e., mesalamine, sulfasalazine or infliximab). Furthermore, the risk of pulmonary embolism is generally increased in pediatric IBD patients. The initial treatment of PM is based on corticosteroids, either inhaled for the larger airways or systemic for smaller airways and parenchymal disease. In summary, this review article summarizes the current knowledge about PM in pediatric IBD patients, focusing on pathophysiological and clinical aspects.

The Combined Value of Type2 Inflammatory Markers in Chronic Obstructive Pulmonary Disease

The roles of type2 inflammatory markers in chronic airway diseases have been assessed in previous studies. However, the relationship between the combined value of these biomarkers and chronic obstructive pulmonary disease (COPD) has not been fully elucidated. We aimed to investigate the roles of the combined value of the fraction of exhaled nitric oxide (FeNO) level and blood eosinophil count in COPD and the predictive capability of these biomarkers. In total, 266 patients were included in our analysis. When the two type2 biomarkers were assessed separately, there were limited correlations between either increased FeNO level or blood eosinophil count and decreased incidence of total exacerbation or frequency of mild exacerbation. Combining these two biomarkers strengthened their association with both incidence and frequency of acute exacerbation. In addition, during further assessment, simultaneously increased FeNO level and blood eosinophil count were associated with both mild and moderate acute exacerbation. Among the subjects included in this analysis, although the predictive capability was improved when these two biomarkers were combined, the improvement was not statistically significant, indicating the need to increase the sample size. The combination of FeNO level and blood eosinophil count exhibited strong and independent additive value in the assessment of acute exacerbation in COPD; simultaneously increased FeNO level and blood eosinophil count played a protective role in progression of COPD.

A Fully Integrated Flexible Tunable Chemical Sensor Based on Gold-Modified Indium Selenide Nanosheets

In this work, a novel light-modulated bifunctional gas sensor based on Au nanoparticles-modified 2D InSe nanosheets was demonstrated. The prepared sensor displayed a reversible and extremely high response for recognition of nitrogen dioxide (NO₂) under visible-light illumination. The sensitivity (1192%) was about 10 times higher than that under dark condition, and the limit of detection (LOD) was 0.17 ppb. In contrast, when sensing ammonia (NH₃), higher sensitivity and selectivity were obtained in darkness rather than in light, with sensitivity and LOD of 11% and 0.2 ppm. Furthermore, the sensor possesses decent stability, repeatability, and anti-interference ability. The tunable sensing behavior with light modulation has been clearly studied with the help of density functional theory. A new principle called "carrier storage box" of Au nanoparticles was proposed to explain the change in surface state of InSe under light modulation. Finally, the prepared sensor has been successfully applied to construct a fully integrated wearable device to measure NH₃ and NO₂ in ambient environment. In all, this work provides a highly competitive gas detection method and paves the way for designing 2D materials-based optoelectronic devices with tunable and multifunctional features.

Urinary levels of Phthalate metabolite mixtures and pulmonary function in adolescents

Although an association between urinary phthalate (PAE) metabolites and respiratory symptoms and diseases has been reported, knowledge regarding its effect on pulmonary function is limited, especially in adolescents. Using cross-sectional data from 1389 adolescents (aged 10-19 years) in the 2007-2012 National Health and Nutrition Examination Survey, the association of mixed urinary PAE metabolites with pulmonary function was evaluated using the weighted quantile sum. Moreover, multivariate linear regression was performed to investigate associations between each urinary PAE metabolite and pulmonary function indicators and to estimate the interaction effects between urinary PAE metabolites and demographic characteristics. We found that mixed urinary PAE metabolites were negatively associated with forced expiratory volume at the 1 s (FEV1, p < 0.001) and forced vital capacity (FVC, p = 0.008) levels. In individual PAE metabolite analyses, mono (carboxynonyl) pthalate (MCNP), mono-n-butyl pthalate (MnBP), mono-isobutyl pthalate (MiBP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono-benzyl phthalate (MBzP) correlated negatively with both FVC and FEV1 values (Holm-Bonferroni corrected p < 0.05). Mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was negatively associated with the FVC value. Significant interactions between sex and urinary MnBP or MBzP levels for the risk of FEV1 decrease in girls were found (p = 0.005), as was a significant interaction between sex and urinary MBzP level for the risk of FVC decline. Our findings suggest that higher PAE exposure is associated with respiratory dysfunction; the association is more pronounced among girls.

Photoexcited NO2 Enables Accelerated Response and Recovery Kinetics in Light-Activated NO2 Gas Sensing

Slow response and recovery kinetics is a major challenge for practical room-temperature NO₂ gas sensing. Here, we report the use of visible light illumination to significantly shorten the response and recovery times of a PbSe quantum dot (QD) gel sensor by 21% (to 27 s) and 63% (to 102 s), respectively. When combined with its high response (0.04%/ppb) and ultralow limit of detection (3 ppb), the reduction in response and recovery time makes the PbSe QD gel sensor among the best p-type room-temperature NO₂ sensors reported to date. A combined experimental and theoretical investigation reveals that the accelerated response and recovery time is primarily due to photoexcitation of NO₂ gaseous molecules and adsorbed NO₂ on the gel surface, rather than the excitation of the semiconductor sensing material, as suggested by the currently prevailing light-activated gas-sensing theory. Furthermore, we find that the extent of improvement attained in the recovery speed also depends on the distribution of excited electrons in the adsorbed NO₂/QD gel system. This work suggests that the design of light-activated sensor platforms may benefit from a careful assessment of the photophysics of the analyte in the gas phase and when adsorbed onto the semiconductor surface.

Mineral Micronutrients in Asthma

Asthma represents one of the most common medical issues in the modern world. It is a chronic inflammatory disease characterized by persistent inflammation of the airways and disturbances in redox status, leading to hyperresponsiveness of bronchi and airway obstruction. Apart from classical risk factors such as air pollution, family history, allergies, or obesity, disturbances of the levels of micronutrients lead to impairments in the defense mechanisms of the affected organism against oxidative stress and proinflammatory stimuli. In the present review, the impact of micronutrients on the prevalence, severity, and possible risk factors of asthma is discussed. Although the influence of classical micronutrients such as selenium, copper, or zinc are well known, the effects of those such as iodine or manganese are only rarely mentioned. As a consequence, the aim of this paper is to demonstrate how disturbances in the levels of micronutrients and their supplementation might affect the course of asthma.

Th1/Th2 cytokines profile in overweight/obese young adults and their correlation with airways inflammation

Objectives

Methods

Results

Conclusion

Is small airway dysfunction an abnormal phenomenon for patients with normal forced expiratory volume in 1 second and the ratio of forced expiratory volume in 1 second to forced vital capacity?

BACKGROUND

The clinical significance of small airway dysfunction (SAD) determined with spirometry in patients with normal forced expiratory volume in 1 second (FEV1) and the ratio of FEV1 to forced vital capacity (FVC) is controversial.

OBJECTIVE

To determine whether SAD presents histologic abnormalities in the setting of normal computed tomography (CT) imaging and FEV1 and FEV1/FVC.

METHODS

A cross-sectional study was performed in 64 patients undergoing thoracotomy for pulmonary nodules. Thoracic high-resolution CT (HRCT), bronchodilation test, and fractional exhaled nitric oxide (FENO) and its alveolar component (nitric oxide alveolar concentration [CANO]) were obtained before surgery. Lung pathology and levels of cytokines in lung tissue were measured. The patients were divided into SAD and small airway normal function groups according to forced expiratory flow at 75% and 50% of the FVC (maximal expiratory flow [MEF] 25, MEF50) and maximum midexpiratory flow.

RESULTS

The MEF50, MEF25, and maximum midexpiratory flow were strongly negatively correlated with CANO (r, -0.42, -0.42, -0.40, respectively; P ≤ .001 for all). The MEFs were mildly negatively correlated with interleukin (IL)-6 and macrophages in lung tissue (r < -0.25, P < .001 for all). The CANO (P < .001), airspace size (mean linear intercept) (P = .02), macrophages (P = .003), IL-6 (P = .003), and IL-8 (P = .008) in lung tissue were higher in patients with SAD (n = 35) than those with small airway normal function (n = 29). A total of 8 patients (22.86%) with SAD and 2 (6.90%) without SAD had pneumatoceles (P = .10).

CONCLUSION

Patients with pulmonary nodules and SAD were more likely to have abnormal inflammation and emphysematous destruction than patients without SAD. Thus, SAD indicates histologic abnormalities in patients with normal CT imaging and FEV1 and FEV1/FVC.

The Functional Diversity of Nitric Oxide Synthase Isoforms in Human Nose and Paranasal Sinuses: Contrasting Pathophysiological Aspects in Nasal Allergy and Chronic Rhinosinusitis

The human paranasal sinuses are the major source of intrinsic nitric oxide (NO) production in the human airway. NO plays several roles in the maintenance of physiological homeostasis and the regulation of airway inflammation through the expression of three NO synthase (NOS) isoforms. Measuring NO levels can contribute to the diagnosis and assessment of allergic rhinitis (AR) and chronic rhinosinusitis (CRS). In symptomatic AR patients, pro-inflammatory cytokines upregulate the expression of inducible NOS (iNOS) in the inferior turbinate. Excessive amounts of NO cause oxidative damage to cellular components, leading to the deposition of cytotoxic substances. CRS phenotype and endotype classifications have provided insights into modern treatment strategies. Analyses of the production of sinus NO and its metabolites revealed pathobiological diversity that can be exploited for useful biomarkers. Measuring nasal NO based on different NOS activities is a potent tool for specific interventions targeting molecular pathways underlying CRS endotype-specific inflammation. We provide a comprehensive review of the functional diversity of NOS isoforms in the human sinonasal system in relation to these two major nasal disorders' pathologies. The regulatory mechanisms of NOS expression associated with the substrate bioavailability indicate the involvement of both type 1 and type 2 immune responses.

Boosting nitric oxide in stress and respiratory infection: Potential relevance for asthma and COVID-19

Nitric oxide (NO) is a ubiquitous signaling molecule that is critical for supporting a plethora of processes in biological organisms. Among these, its role in the innate immune system as a first line of defense against pathogens has received less attention. In asthma, levels of exhaled NO have been utilized as a window into airway inflammation caused by allergic processes. However, respiratory infections count among the most important triggers of disease exacerbations. Among the multitude of factors that affect NO levels are psychological processes. In particular, longer lasting states of psychological stress and depression have been shown to attenuate NO production. The novel SARS-CoV-2 virus, which has caused a pandemic, and with that, sustained levels of psychological stress globally, also adversely affects NO signaling. We review evidence on the role of NO in respiratory infection, including COVID-19, and stress, and argue that boosting NO bioavailability may be beneficial in protection from infections, thus benefitting individuals who suffer from stress in asthma or SARS-CoV-2 infection.

Nitric Oxide System and Bronchial Epithelium: More Than a Barrier

Airway epithelium forms a physical barrier that protects the lung from the entrance of inhaled allergens, irritants, or microorganisms. This epithelial structure is maintained by tight junctions, adherens junctions and desmosomes that prevent the diffusion of soluble mediators or proteins between apical and basolateral cell surfaces. This apical junctional complex also participates in several signaling pathways involved in gene expression, cell proliferation and cell differentiation. In addition, the airway epithelium can produce chemokines and cytokines that trigger the activation of the immune response. Disruption of this complex by some inflammatory, profibrotic, and carcinogens agents can provoke epithelial barrier dysfunction that not only contributes to an increase of viral and bacterial infection, but also alters the normal function of epithelial cells provoking several lung diseases such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) or lung cancer, among others. While nitric oxide (NO) molecular pathway has been linked with endothelial function, less is known about the role of the NO system on the bronchial epithelium and airway epithelial cells function in physiological and different pathologic scenarios. Several data indicate that the fraction of exhaled nitric oxide (FENO) is altered in lung diseases such as asthma, COPD, lung fibrosis, and cancer among others, and that reactive oxygen species mediate uncoupling NO to promote the increase of peroxynitrite levels, thus inducing bronchial epithelial barrier dysfunction. Furthermore, iNOS and the intracellular pathway sGC-cGMP-PKG are dysregulated in bronchial epithelial cells from patients with lung inflammation, fibrosis, and malignancies which represents an attractive drug molecular target. In this review we describe in detail current knowledge of the effect of NOS-NO-GC-cGMP-PKG pathway activation and disruption in bronchial epithelial cells barrier integrity and its contribution in different lung diseases, focusing on bronchial epithelial cell permeability, inflammation, transformation, migration, apoptosis/necrosis, and proliferation, as well as the specific NO molecular pathways involved.

Utility of fractional exhaled nitric oxide in interstitial lung disease

The majority of interstitial lung diseases (ILDs) develop rapidly and are associated with a poor prognosis. Therefore, new noninvasive markers are needed to guide the classification and prognostication of ILD. We enrolled 95 patients with ILD, including dermatomyositis-associated ILD (n =69), Sjögren's syndrome-associated ILD (n= 7), mixed connective tissue disease-associated ILD (n= 9), idiopathic pulmonary fibrosis (n= 5) and hypersensitivity pneumonitis (n= 5), 82 patients with connective tissue disease but without ILD as well as 24 healthy controls, then evaluated fractional exhaled nitric oxide (FeNO50; 50 ml s^-1) (Bisenkovet al2006Vestn. Khir. Im. I. I. Grek.1659-14), pulmonary function and high-resolution computed tomography (HRCT) scores. Blood samples were analyzed and bronchoalveolar lavage fluid parameters were measured. There was no significant difference in FeNO50 values between different subgroups of ILD patients or between different subgroups of ILD patients and healthy controls. However, we found that FeNO50 was negatively correlated with the HRCT score and positively correlated with forced vital capacity. FeNO50 values did not play a clinical role in the diagnosis, differential diagnosis or prognostication of ILD.

Fraction of Exhaled Nitric Oxide Levels Are Elevated in People Living With Human Immunodeficiency Virus Compared to Uninfected Controls, Suggesting Increased Eosinophilic Airway Inflammation

BACKGROUND

Increased risk of asthma and chronic obstructive pulmonary disease has been reported in people living with human immunodeficiency virus (PLWH). Fraction of exhaled nitric oxide (FeNO) is a marker of eosinophilic airway inflammation. We assessed FeNO levels in PLWH and matched uninfected controls and investigated whether human immunodeficiency virus (HIV) status is independently associated with elevated FeNO.

METHODS

FeNO was quantified by NIOX Vero and pulmonary function was assessed by spirometry in 432 PLWH from the Copenhagen Comorbidity in HIV Infection Study and in 1618 age- and sex-matched uninfected controls from the Copenhagen General Population Study. Elevated FeNO was defined as ≥25 parts per billion. Associations between FeNO and HIV status were adjusted for known potential confounders.

RESULTS

Mean age of PLWH was 50.7 (standard deviation [SD], 11.1) years and 97.4% received combination antiretroviral therapy. PLWH had higher FeNO than uninfected controls (median, 17.0 [interquartile range {IQR}, 11.0-26.0] vs 13.0 [IQR, 9.0-19.0]; P < .001). Also, PLWH had a higher prevalence of elevated FeNO than uninfected controls (27.5% vs 12.3%; P < .001). This association remained after adjusting for age, sex, height, smoking status, use of airway medication, blood eosinophils, and immunoglobulin E (adjusted OR [aOR], 3.56 [95% CI, 2.51-5.04]; P < .001). Elevated FeNO was associated with self-reported asthma (aOR, 2.65 [95% CI, 1.66-4.24]; P < .001) but not with airflow limitation (aOR, 1.07 [95% CI, .71-1.62]; P = .745).

CONCLUSIONS

HIV status was independently associated with elevated FeNO, suggesting increased eosinophilic airway inflammation. The potential impact on chronic lung disease pathogenesis needs further investigation.

Therapeutic Effects of Benralizumab Assessed in Patients with Severe Eosinophilic Asthma: Real-Life Evaluation Correlated with Allergic and Non-Allergic Phenotype Expression

BACKGROUND

Benralizumab can be utilized as add-on biological treatment of severe eosinophilic asthma. However, so far only a few real-life studies have been published with regard to the use of this anti-IL-5 receptor humanized monoclonal antibody.

OBJECTIVE

The primary aim of this multicenter observational investigation has been to assess the therapeutic effects of benralizumab in patients with severe uncontrolled, corticosteroid refractory eosinophilic asthma. The secondary objective was to evaluate the efficacy of benralizumab with regard to positive or negative skin prick test (SPT).

METHODS

Clinical, functional, and laboratory parameters were evaluated in order to verify the therapeutic actions of benralizumab in atopic and non atopic subjects with difficult-to-treat eosinophilic asthma. Moreover, a comparative evaluation was carried out in relation to the presence or absence of SPT positivity.

RESULTS

After 6 months of add-on biological therapy with benralizumab, our 111 patients experienced a marked improvement of their severe eosinophilic asthma, expressed by significant changes in asthma exacerbation rate, prednisone intake, daily use of short-acting β2-adrenergic agonists (SABA), asthma control test (ACT) score, asthma quality of life questionnaire (AQLQ) score (56 patients), forced expiratory volume in one second (FEV1), forced vital capacity (FVC), blood eosinophil count, blood basophil count (59 patients), and fractional exhaled nitric oxide (FeNO) levels (39 patients). In addition, significantly more effective outcomes were detected in patients with positive SPT, when compared to subjects with negative SPT, only in regard to asthma exacerbation number, ACT score, and daily SABA utilization. No significant correlation was found between serum IgE concentrations and each of all measured parameters.

CONCLUSION AND CLINICAL RELEVANCE

Taken together, the results of this real-world study indicate that in both allergic and non-allergic subjects benralizumab can be used as a valuable pharmacotherapeutic option for add-on biological therapy of severe eosinophilic asthma, regardless of SPT positivity or negativity.

The Nitric Oxide Pathway in Pulmonary Arterial Hypertension: Pathomechanism, Biomarkers and Drug Targets

The altered Nitric Oxide (NO) pathway in the pulmonary endothelium leads to increased vascular smooth muscle tone and vascular remodelling, and thus contributes to the development and progression of pulmonary arterial hypertension (PAH). The pulmonary NO signalling is abrogated by the decreased expression and dysfunction of the endothelial NO synthase (eNOS) and the accumulation of factors blocking eNOS functionality. The NO deficiency of the pulmonary vasculature can be assessed by detecting nitric oxide in the exhaled breath or measuring the degradation products of NO (nitrite, nitrate, S-nitrosothiol) in blood or urine. These non-invasive biomarkers might show the potential to correlate with changes in pulmonary haemodynamics and predict response to therapies. Current pharmacological therapies aim to stimulate pulmonary NO signalling by suppressing the degradation of NO (phosphodiesterase- 5 inhibitors) or increasing the formation of the endothelial cyclic guanosine monophosphate, which mediates the downstream effects of the pathway (soluble guanylate cyclase sensitizers). Recent data support that nitrite compounds and dietary supplements rich in nitrate might increase pulmonary NO availability and lessen vascular resistance. This review summarizes current knowledge on the involvement of the NO pathway in the pathomechanism of PAH, explores novel and easy-to-detect biomarkers of the pulmonary NO.

Genetic Delivery and Gene Therapy in Pulmonary Hypertension

Pulmonary hypertension (PH) is a progressive complex fatal disease of multiple etiologies. Hyperproliferation and resistance to apoptosis of vascular cells of intimal, medial, and adventitial layers of pulmonary vessels trigger excessive pulmonary vascular remodeling and vasoconstriction in the course of pulmonary arterial hypertension (PAH), a subgroup of PH. Multiple gene mutation/s or dysregulated gene expression contribute to the pathogenesis of PAH by endorsing the proliferation and promoting the resistance to apoptosis of pulmonary vascular cells. Given the vital role of these cells in PAH progression, the development of safe and efficient-gene therapeutic approaches that lead to restoration or down-regulation of gene expression, generally involved in the etiology of the disease is the need of the hour. Currently, none of the FDA-approved drugs provides a cure against PH, hence innovative tools may offer a novel treatment paradigm for this progressive and lethal disorder by silencing pathological genes, expressing therapeutic proteins, or through gene-editing applications. Here, we review the effectiveness and limitations of the presently available gene therapy approaches for PH. We provide a brief survey of commonly existing and currently applicable gene transfer methods for pulmonary vascular cells in vitro and describe some more recent developments for gene delivery existing in the field of PH in vivo.

Assessing the Respiratory Effects of Air Pollution from Biomass Cookstoves on Pregnant Women in Rural India

Background: In India, biomass fuel is burned in many homes under inefficient conditions, leading to a complex milieu of particulate matter and environmental toxins known as household air pollution (HAP). Pregnant women are particularly vulnerable as they and their fetus may suffer from adverse consequences of HAP. Fractional exhaled nitric oxide (FeNO) is a noninvasive, underutilized tool that can serve as a surrogate for airway inflammation. We evaluated the prevalence of respiratory illness, using pulmonary questionnaires and FeNO measurements, among pregnant women in rural India who utilize biomass fuel as a source of energy within their home. Methods: We prospectively studied 60 pregnant women in their 1st and 2nd trimester residing in villages near Nagpur, Central India. We measured FeNO levels in parts per billion (ppb), St. George’s Respiratory Questionnaire (SGRQ-C) scores, and the Modified Medical Research Council (mMRC) Dyspnea Scale. We evaluated the difference in the outcome distributions between women using biomass fuels and those using liquefied petroleum gas (LPG) using two-tailed t-tests. Results: Sixty-five subjects (32 in Biomass households; 28 in LPG households; 5 unable to complete) were enrolled in the study. Age, education level, and second-hand smoke exposure were comparable between both groups. FeNO levels were higher in the Biomass vs. LPG group (25.4 ppb vs. 8.6 ppb; p-value = 0.001). There was a difference in mean composite SGRQ-C score (27.1 Biomass vs. 10.8 LPG; p-value < 0.001) including three subtotal scores for Symptoms (47.0 Biomass vs. 20.2 LPG; p-value< 0.001), Activity (36.4 Biomass vs. 16.5 LPG; p-value < 0.001) and Impact (15.9 Biomass vs. 5.2 LPG; p-value < 0.001). The mMRC Dyspnea Scale was higher in the Biomass vs. LPG group as well (2.9 vs. 0.5; p < 0.001). Conclusion: Increased FeNO levels and higher dyspnea scores in biomass-fuel-exposed subjects confirm the adverse respiratory effects of this exposure during pregnancy. More so, FeNO may be a useful, noninvasive biomarker of inflammation that can help better understand the physiologic effects of biomass smoke on pregnant women. In the future, larger studies are needed to characterize the utility of FeNO in a population exposed to HAP.

Acute Exposure to Environmental Tobacco Smoke: A Controlled Study in Adults with Asthma

BACKGROUND

Short-term, indoor exposure to environmental tobacco smoke (ETS) is still highly prevalent; however, little is known about the acute lung response in adult asthma.

OBJECTIVES

We investigated whether acute, experimental ETS exposure influences symptoms, lung function, and inflammatory parameters.

METHODS

Human subjects with asthma (n = 23) were exposed for 180 min to either room air or ETS at 250, 450, or 850 µg/m3. Respiratory symptoms, lung function, and exhaled nitric oxide (FeNO) were measured. Additionally, blood samples were analyzed for pro- and anti-inflammatory cytokines.

RESULTS

Humans with asthma demonstrate an increase in respiratory symptoms at all levels of ETS exposure, while the forced expiratory volume in 1 s (FEV1) and FeNO decrease with increasing ETS. The anti-inflammatory cytokine interleukin (IL)-10 increases at intermediate ETS concentrations, whereas tumor necrosis factor (TNF)-α and IL-8 increase only at the highest ETS concentration.

CONCLUSION

Following 180 min of acute, experimental ETS exposure, we observed a significant increase in respiratory symptoms, a decrease in lung function, and an increase in inflammatory cytokines, indicating an acute lung response in asthma.

Addressing Reduced Laboratory-Based Pulmonary Function Testing During a Pandemic

To reduce the spread of the severe acute respiratory syndrome coronavirus 2, many pulmonary function testing (PFT) laboratories have been closed or have significantly reduced their testing capacity. Because these mitigation strategies may be necessary for the next 6 to 18 months to prevent recurrent peaks in disease prevalence, fewer objective measurements of lung function will alter the diagnosis and care of patients with chronic respiratory diseases. PFT, which includes spirometry, lung volume, and diffusion capacity measurement, is essential to the diagnosis and management of patients with asthma, COPD, and other chronic lung conditions. Both traditional and innovative alternatives to conventional testing must now be explored. These may include peak expiratory flow devices, electronic portable spirometers, portable exhaled nitric oxide measurement, airwave oscillometry devices, and novel digital health tools such as smartphone microphone spirometers and mobile health technologies along with integration of machine learning approaches. The adoption of some novel approaches may not merely replace but could improve existing management strategies and alter common diagnostic paradigms. With these options comes important technical, privacy, ethical, financial, and medicolegal barriers that must be addressed. However, the coronavirus disease 19 pandemic also presents a unique opportunity to augment conventional testing by including innovative and emerging approaches to measuring lung function remotely in patients with respiratory disease. The benefits of such an approach have the potential to enhance respiratory care and empower patient self-management well beyond the current global pandemic.

Co-exposure to polycyclic aromatic hydrocarbons, benzene and toluene may impair lung function by increasing oxidative damage and airway inflammation in asthmatic children

As previous studies found that the direct associations between urinary polycyclic aromatic hydrocarbon (PAH), benzene and toluene (BT) metabolites and the decreased lung function were not conclusive, we further investigated relationship of oxidative damage and airway inflammation induced by PAHs and BTs exposure with lung function. A total of 262 children diagnosed with asthma and 72 heathy children were recruited. Results showed that asthmatic children had higher levels of PAHs and BTs exposure, as well as Malonaldehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) compared with healthy children. Furthermore, binary logistic regression showed that each unit increases in level of urinary 2-&3-hydroxyfluorene (2-&3-OHF), 2-hydroxyphenanthrene (2-OHPhe), 1-hydroxyphenanthrene (1-OHP) and S-phenylmercapturic acid (S-PMA) were significantly associated with an elevated risk of asthma in children with odds ratios of 1.5, 2.3, 1.7 and 1.4, respectively, suggesting that PAHs and BTs exposure could increase the risk of asthma for children. Neither PAH nor BT metabolite could comprehensively indicate the decreased lung function as only 2-&3-OHF and 1-OHP were significantly and negatively correlated with forced vital capacity (FVC). Moreover, levels of most individual PAH and BT metabolite were significantly correlated to MDA and 8-OHdG. Further hierarchical regression analysis indicated that MDA and 8-OHdG levels did not show significant effects on the decreased lung function, suggesting that they are not the suitable biomarkers to indirectly indicate the altered lung function induced by PAHs and BTs. Urinary 2-OHPhe and 1-&9-hydroxyphenanthrene (1-&9-OHPhe) were significantly correlated with fractional exhaled nitric oxide (FeNO). Moreover, FeNO significantly contributed to decreased lung function and explained 7.7% of variance in ratio of forced expiratory volume in 1 s (FEV₁) and FVC (FEV₁/FVC%). Hence, FeNO, rather than oxidative damage indicators or any urinary PAH and BT metabolite, is more sensitive to indirectly reflect the decreased lung function induced by PAHs and BTs exposure for asthmatic children.

The Effect of Adiposity Markers on Fractional Exhaled Nitric Oxide (FeNO) and Pulmonary Function Measurements

Background

The effect of increasing body weight on pulmonary function and the fractional exhaled nitric oxide (FeNO) remains controversial and the role of different body compositions in the relationship between obesity with pulmonary function and FeNO is still unrevealed. Thus, we aim to determine the effect of overweight/obesity on lung function and FeNO, focusing on the relationship with different body compositions.

Methods

Eighty-two non-smoker students (20 ± 1.9 years) were divided into two groups: 38 subjects with normal weight (BMI = 18.5–24.99) and 44 overweight/obese subjects (BMI ≥ 25). Spirometric parameters and FeNO were measured and compared between groups and were correlated with different adiposity markers.

Results

FeNO measurements were elevated in the overweight/obese group [median (IQR) 19.5 (13)] in comparison to the normal weight group [11 (10), p value = 0.017]. A positive correlation was found between FeNO measurements and body mass index (BMI), waist circumference, hip circumference, waist-hip ratio, and visceral fat percentage (all p values < 0.01). The absolute values of forced vital capacity (FVC) forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF), forced expiratory flow during mid-expiration (FEF_25–75%), and FEV₁/FVC ratio showed no significant differences between groups. However, the percentage of the predicted values of FEV₁ and FVC was significantly higher and the value of percentage predicted FEF_25–75% was reduced significantly in the overweight/obese subjects.

Conclusion

Increase in BMI could significantly increase airway inflammation as measured by FeNO, as well as on distal airway function as determined by the percentage predicted values of FEF_25–75%. A significant correlation was also identified between visceral fat and FeNO measurement.

Predictive Value of Exhaled Nitric Oxide and Blood Eosinophil Count in the Assessment of Airway Eosinophilia in COPD

Purpose

Fractional exhaled nitric oxide (FENO50) level and peripheral blood eosinophil count may serve as indicators of airway eosinophilia. The aim of this study was to estimate the diagnostic value of these markers for detecting airway eosinophilia in patients with stable chronic obstructive pulmonary disease (COPD) and those experiencing an acute exacerbation (AECOPD).

Patients and Methods

FENO50 levels, sputum and blood eosinophil counts were assessed in 53 clinically stable ex-smoker COPD patients and 67 ex-smoker COPD patients experiencing a severe exacerbation. In AECOPD, clinical variables were measured at the time of hospital admission and discharge following treatment.

Results

In stable COPD, blood eosinophil count but not FENO50 level was found to be a good predictor of airway eosinophilia (area under the receiver operating characteristic curve [ROC AUC]: ≥0.82). The sensitivity and the specificity of the test ranged between 75% and 98%, the negative predictive value (NPV) was high (>90%). In AECOPD, FENO50 was predictive for airway eosinophilia (ROC AUC: >0.8) with high NPV (>88%), but with lower sensitivity and specificity (64-70%). In contrast, the predictive accuracy of blood eosinophil count for airway eosinophilia in AECOPD was modest (ROC AUC: 0.54-0.63). The combined use of the two markers provided only limited additional benefit. Correlation analyses supported ROC curve findings.

Conclusion

In stable COPD the peripheral blood eosinophil count, while in AECOPD the FENO50 level is a good surrogate marker of airway eosinophilia.

Biomarkers of Type 2 Airway Inflammation as Predictors of Loss of Asthma Control During Step-Down Therapy for Well-Controlled Disease: The Long-Acting Beta-Agonist Step-Down Study (LASST)

BACKGROUND

Biomarkers that can predict loss of asthma control among patients being considered for step-down therapy in well-controlled disease are lacking.

OBJECTIVE

To evaluate whether baseline biomarkers of type 2 airway inflammation and/or serial measurement of fractional exhaled nitric oxide (Feno) predict loss of asthma control as therapy is stepped down.

METHODS

In subanalyses of a multicenter randomized, double-blind, parallel 3-arm trial comparing strategies for step-down therapy in well-controlled asthma (Long-Acting Beta-Agonist Step-Down Study), we assessed whether baseline atopy as determined by serum aeroallergen allergy screening test (Phadiatop), baseline serum eosinophil peroxidase, or baseline or serial Feno measurements during follow-up predicted the time to loss of asthma control among participants. Loss of asthma control was defined in the study protocol. We analyzed these associations in adjusted models including all participants, after testing for interactions with assignment to each of the 3 treatment groups (continuation of stable dose of combination inhaled corticosteroid-long-acting beta-agonist, step-down of inhaled corticosteroid, or discontinuation of long-acting bronchodilator).

RESULTS

Four hundred forty-seven of the 553 Long-Acting Beta-Agonist Step-Down Study participants who were randomized to 1 of 3 treatment arms and had at least 1 biomarker measurement were included in this analysis. At baseline, higher levels of Feno were significantly associated with greater levels of multiallergen IgE levels (P < .001), but not with serum eosinophil peroxidase (P = .742). Among all participants as a group, elevations in baseline biomarkers were not predictive of a higher risk of treatment failure. In addition, Feno levels measured serially at 6-week intervals demonstrated that compared with participants with low levels (<25 parts per billion), those with intermediate (25-50 parts per billion) and high (>50 parts per billion) levels did not have significantly increased likelihood of subsequent treatment failure (hazard ratios, 1.03 [95% CI, 0.59-1.78] and 1.29 [95% CI, 0.65-2.54], respectively). There were no significant interactions of treatment group and baseline biomarkers.

CONCLUSIONS

In patients with well-controlled asthma, neither baseline levels of type 2 airway inflammatory biomarkers nor serial measures of Feno are strong predictors of treatment failure.

Asthma rehabilitation at high vs. low altitude and its impact on exhaled nitric oxide and sensitization patterns: Randomized parallel-group trial

BACKGROUND

Allergens and pollution are reduced at high altitude. We investigated the effect of asthma rehabilitation at high altitude (HA, 3100 m) compared to low altitude (LA, 760 m) on exhaled nitric oxide (FeNO) and on specific IgE levels for house dust mites (HDM,d1) and common pollen (sx1).

METHODS

For this randomized controlled trial adult asthmatics living <1000 m were randomly assigned to a 3-week in-hospital-rehabilitation (education, physical- and breathing-exercises) at either LA or HA. Changes in FeNO, d1 and sx1 from baseline to end-rehabilitation were measured.

RESULTS

50 asthmatics (34 females) were randomized [mean ± standard deviation LA: n = 25, 44 ± 11 years, total IgE 267 ± 365kU/l; HA: n = 25, 43 ± 13 years, total IgE 350 ± 445kU/l]. FeNO significantly improved at HA from 69 ± 56 ppb at baseline to the first day at altitude 23 ± 19 ppb and remained decreased until end-rehabilitation with 37 ± 23 ppb, mean difference 95%CI -31(-50 to -13, p = 0.001) whereas at LA FeNO did not change. A significant decrease in d1 and sx1 at end-rehabilitation was observed in the LA-group [mean difference 95%CI -10.2 kUA/l (-18.9 to -1.4) for d1 and -4.95 kUA/l(-9.69 to -0.21) for sx1] but not in the HA-group. No significant difference between groups [d1 5.9 kUA/l(-4.2 to 16.2) and sx1 4.4 kUA/l(-3.5 to 12.4)] was found.

CONCLUSION

Rehabilitation at HA led to significant FeNO reduction starting from the first day until end-rehabilitation despite unchanged levels of specific IgE. The significant decrease in d1 and sx1 at end-rehabilitation in the LA group might be explained by less HDM in the hospital and/or reduced seasonal pollen, as this decrease was not observed at HA.

Phenotypes and endotypes of adult asthma: Moving toward precision medicine

Asthma is a chronic inflammatory disease of the airways that is challenging to dissect into subgroups because of the heterogeneity present across the spectrum of the disease. Efforts to subclassify asthma using advanced computational methods have identified a number of different phenotypes that suggest that multiple pathobiologically driven clusters of disease exist. The main phenotypes that have been identified include (1) early-onset allergic asthma, (2) early-onset allergic moderate-to-severe remodeled asthma, (3) late-onset nonallergic eosinophilic asthma, and (4) late-onset nonallergic noneosinophilic asthma. Subgroups of these phenotypes also exist but have not been as consistently identified. Advances in our understanding of the diverse immunologic perturbations that drive airway inflammation are consistent with clinical traits associated with these phenotypes and their response to biologic therapies. This has improved the clinician's approach to characterizing asthmatic patients in the clinic. Being able to define asthma endotypes using clinical characteristics and biomarkers will move physicians toward even more personalized management of asthma and precision-based care in the future. Here we will review the most prominent phenotypes and immunologic advances that suggest these disease subtypes represent asthma endotypes.

Augmentation of Cystic Fibrosis Transmembrane Conductance Regulator Function in Human Bronchial Epithelial Cells via SLC6A14-Dependent Amino Acid Uptake. Implications for Treatment of Cystic Fibrosis

SLC6A14-mediated l-arginine transport has been shown to augment the residual anion channel activity of the major mutant, F508del-CFTR, in the murine gastrointestinal tract. It is not yet known if this transporter augments residual and pharmacological corrected F508del-CFTR in primary airway epithelia. We sought to determine the role of l-arginine uptake via SLC6A14 in modifying F508del-CFTR channel activity in airway cells from patients with cystic fibrosis (CF). Human bronchial epithelial (HBE) cells from lung explants of patients without CF (HBE) and those with CF (CF-HBE) were used for H³-flux, airway surface liquid, and Ussing chamber studies. We used α-methyltryptophan as a specific inhibitor for SLC6A14. CFBE41o^-, a commonly used CF airway cell line, was employed for studying the mechanism of the functional interaction between SLC6A14 and F508del-CFTR. SLC6A14 is functionally expressed in CF-HBE cells. l-arginine uptake via SLC6A14 augmented F508del-CFTR function at baseline and after treatment with lumacaftor. SLC6A14-mediated l-arginine uptake also increased the airway surface liquid in CF-HBE cells. Using CFBE41o cells, we showed that the positive SLC6A14 effect was mainly dependent on the nitric oxide (NO) synthase activity, nitrogen oxides, including NO, and phosphorylation by protein kinase G. These finding were confirmed in CF-HBE, as inducible NO synthase inhibition abrogated the functional interaction between SLC6A14 and pharmacological corrected F508del-CFTR. In summary, SLC6A14-mediated l-arginine transport augments residual F508del-CFTR channel function via a noncanonical, NO pathway. This effect is enhanced with increasing pharmacological rescue of F508del-CFTR to the membrane. The current study demonstrates how endogenous pathways can be used for the development of companion therapy in CF.

Increased Tissue Expression of Lectin-Like Oxidized LDL Receptor-1 (LOX-1) Is Associated with Disease Severity in Chronic Rhinosinusitis with Nasal Polyps

Background: The oxidative stress, induced by both environmental and intrinsic stimuli, underlies the onset and persistency of chronic rhinosinusitis (CRS). Scavenger receptors (SRs) are a broad family of transmembrane receptors involved in a dysfunctional host–environment interaction through a reaction with reactive oxygen species (ROS) production. Objective: We hypothesized possible roles of two major SRs in CRS pathology that can translate to clinical phenotypes or histological subtypes: lectin-like oxidized low-density lipoproteins (LDL) receptor-1 (LOX-1) and scavenger receptor class B type 1 (SR-B1). Patients and Methods: We collected ethmoid sinus mucosa specimens and blood samples from patients with CRS with nasal polyps (CRSwNP; n = 31) or CRS without NP (CRSsNP; n = 13) and 19 control subjects. We performed an RT-PCR analysis, ELISA assay, and immunostaining to determine the expressions and distributions of LOX-1 and SR-B1. Results: The CRSwNP group showed a significant increase in LOX-1 mRNA expression compared to the control group. There was no significant difference in SR-B1 mRNA levels among the three groups. The LOX-1 mRNA levels were positively correlated with the sinus computed tomography (CT) scores. Sinus tissue, but not serum samples, showed elevated concentrations of LOX-1 protein in the CRSwNP group versus the control group. The LOX-1 protein distribution was localized in inflammatory cells and vascular endothelial cells. Conclusion: LOX-1 is a major receptor for oxidized low-density lipoprotein produced by oxidative stress. This is the first study to report alterations in LOX-1 expression and production triggered by persistent inflammatory processes in CRSwNP patients. Our findings reveal complex but important roles for SRs that may contribute to the onset of different CRS phenotypes.

Factors associated with exhaled nitric oxide in children with asthma and allergic rhinitis

BACKGROUND

Factors attributable to the level of fraction of exhaled nitric oxide (FeNO) in different age groups of asthmatic children are still lack of report.

OBJECTIVE

To evaluate factors associated with FeNO and the response of FeNO to inhaled steroid in different age groups of asthmatic children with allergic rhinitis.

METHODS

Asthmatic children aged 5 to 12 years were recruited. FeNO, lung function and bronchial hyperresponsiveness (BHR) to methacholine, skin prick testing to a panel of aeroallergens, total immunoglobulin E (T-IgE) in serum and eosinophils in blood were tested. Correlations between FeNO and the measured parameters were assessed. FeNO was measured again after the treatment of combined inhaled corticosteroid and long-acting beta-agonist (ICS/LABA) for 4 weeks. Changes in FeNO between different age groups were compared.

RESULTS

A total of 121 eligible subjects were enrolled in and completed this study. Asthmatic children aged 10 to 12 years old had significantly higher FeNO than those between 8 and 9 years and 5 to 7 years of children (both P < 0.01). Greater height/age (P < 0.01) and higher level of total allergen IgE (P < 0.01) are associated with a higher value of FeNO. After 4 weeks of treatment with ICS/LABA, asthma control test scores were significantly increased in all age groups (P < 0.01), while the level of FeNO significantly decreased in the elder age group only (P < 0.01).

CONCLUSIONS

Height and T-IgE are well correlated with FeNO in asthmatic children aged 5 to 12 years. Measurement of FeNO is more suitable for evaluating the efficacy of ICS/LABA in elder asthmatic children.

Fractional exhaled nitric oxide as a potential biomarker for radiation pneumonitis in patients with non-small cell lung cancer: A pilot study

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Weekly FeNO during radiotherapy can be useful in predicting radiation pneumonitis.

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6 months of clinical follow-up is necessary to detect delayed radiation pneumonitis.

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Pulmonary function tests are not predictable for radiation pneumonitis.

Introduction

The aim of the study was to investigate repetitive fractional exhaled nitric oxide (FeNO) measurements during high-dose radiation therapy (HDRT) and to evaluate the use of FeNO to predict symptomatic radiation pneumonitis (RP) in patients being treated for non-small cell lung cancer (NSCLC).

Materials and methods

A total of 50 patients with NSCLC referred for HDRT were enrolled. FeNO was measured at baseline, weekly during HDRT, one month- and every third month after HDRT for a one-year follow-up period. The mean FeNO_{(visit 0-6)} was calculated using the arithmetic mean of the baseline and weekly measurements during HDRT. Patients with grade ≥ 2 of RP according to the Common Terminology Criteria for Adverse Events (CTCAE) were considered symptomatic.

Results

A total of 42 patients completed HDRT and weekly FeNO measurements. Grade ≥ 2 of RP was diagnosed in 24 (57%) patients. The mean FeNO_{(visit 0-6)} ± standard deviation in patients with and without RP was 15.0 ± 7.1 ppb (95%CI: 12.0–18.0) and 10.3 ± 3.4 ppb (95%CI: 8.6–11.9) respectively with significant differences between the groups (p = 0.0169, 95%CI: 2.3–2.6). The leave-one-out cross-validated cut-off value of the mean FeNO_{(visit 0-6)} ≥ 14.8 ppb was predictive of grade ≥ 2 RP with a specificity of 71% and a positive predictive value of 78%.

Conclusions

The mean FeNO_{(visit 0-6)} in patients with symptomatic RP after HDRT for NSCLC was significantly higher than in patients without RP and may serve as a potential biomarker for RP.