Measurement of fractional exhaled nitric oxide and nasal nitric oxide in male patients with obstructive sleep apnea

Exhaled Nitric Oxide fraction in asthma and obstructive sleep apnea among children at high altitudes. A cross-sectional study

INTRODUCTION

Exhaled nitric oxide fraction (FeNO) is employed for the diagnosis and phenotyping of asthma as an inflammatory biomarker of the airway. Limited evidence exists regarding its behavior in the presence of asthma and obstructive sleep apnea (OSA). Our objective was to determine whether FeNO levels are associated with the severity of OSA or the coexistence of asthma and OSA in residents at high altitudes.

MATERIALS AND METHODS

Observational, analytical, cross-sectional study in children aged 5-16 years residing at 2600 m above sea level treated at a Sleep Study Center between 2019 and 2021. We conducted a medical history, polysomnogram, and measurement of FeNO levels. The children were categorized into four groups: OSA, asthma, asthma with OSA, and controls (without asthma or OSA). FeNO levels among the groups were compared using the Kruskal-Wallis test, and correlations were explored using the Spearman correlation coefficient. Analyses considered statistical significance at a two-tailed p-value <0.05.

RESULTS

Among the 261 included children, 68 (26.1 %) had OSA, 42 (16.1 %) were diagnosed with asthma, 109 (41.8 %) had both asthma and OSA, and 42 (16.1 %) were controls. Their FeNO medians were 10 ppb, 18.5 ppb, 15 ppb, and 14 ppb, respectively, with no significant differences between the evaluated groups (p = 0.263). We found no correlation between FeNO and apnea-hypopnea index and obstructive apnea index even for the groups of patients with FeNO >20 ppb and FeNO >35 ppb (>75th percentile). In the adjusted model, a significant association was observed between asthma and FeNO levels.

CONCLUSIONS

Our findings suggest that FeNO measurements in children would not allow establishing this biomarker as part of the diagnosis of OSA. However, these findings may be related to high altitude.

The Effect of Varying Fatty Acid Composition on Postprandial Airway Inflammation, Pulmonary Function, and Airway Resistance in Healthy, Young Adults

OBJECTIVE

To examine the effect of varying fatty acid composition in a HFM on eNO, pulmonary function, and airway resistance.

METHODS

Fifteen individuals [6 M/9 F; 21.9 ± 1.5 years old] each completed three HFM conditions {SF, O6FA, and O3FA; 12 kcal/kg body weight, 63% total fat, and 0.72 g/kg sugar smoothies} in random order separated by at least 48 h. Airway inflammation assessed via eNO, pulmonary function measured using the maximum flow volume loop (MFVL) and airway resistance measured using impulse oscillometry (iOS) were taken at baseline, 2h and 4h postprandially.

RESULTS

There was no difference in eNO or iOS across time in any condition or between conditions (p > 0.05). There was a significant time by condition effect for FEV1 post-HFM in the SF and O6FA conditions (p < 0.05).

CONCLUSION

Different fatty acid compositions do not increase eNO or iOS in healthy, college-aged participants after consumption of a HFM, though the minimally processed meals with fruit added may contribute to these findings.

Fractional nitric oxide measurement in exhaled air (FeNO): perspectives in the management of respiratory diseases

Exhaled nitric oxide (NO) production, upregulated by inflammatory cytokines and mediators in central and peripheral airways, can be easily and non-invasively detected in exhaled air in asthma and other respiratory conditions as a promising tool for disease monitoring. The American Thoracic Society and European Respiratory Society released recommendations that standardize the measurement of the fractional exhaled NO (FeNO). In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways and, as a biomarker of T2 inflammation can be used to identify asthma T2 phenotype. In this setting its measurement has shown to be an important tool especially in the diagnostic process, in the assessment and evaluation of poor adherence or predicting positive response to inhaled corticosteroids treatment, in phenotyping severe asthma patients and as a biomarker to predict the response to biologic treatments. The discovery of the role of NO in the pathogenesis of different diseases affecting the airways and the possibility to estimate the predominant site of increased NO production has provided new insight on its regulatory role in the airways, making it suitable for a potential extended use in clinical practice for different pulmonary diseases, even though its role remains less clear than in asthma. Monitoring FeNO in pulmonary obstructive lung diseases including chronic bronchitis and emphysema, interstitial lung diseases, obstructive sleep apnea and other pulmonary diseases is still under debate but has opened up a window to the role NO may play in the management of these diseases. The use of FeNO is reliable, cost effective and recommendable in both adults and children, and should be implemented in the management of patients with asthma and other respiratory conditions.

Adipocytokines in obstructive sleep apnea: A systematic review and meta-analysis

BACKGROUND AND AIM

Adipocytokines play an important role in obstructive sleep apnea (OSA) by mediating inflammatory responses. Previous studies have reported that OSA is related to a change in the serum levels of adipocytokines; however, the results are still controversial. This meta-analysis aimed to assess the relationship between OSA and circulating level of adipocytokines in adults and children.

METHODS

A comprehensive search was conducted in databases of Medline/PubMed and Scopus for pertinent articles published since their inception to July 2022. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to assess the strength of the relationship between the concentrations of adipocytokines with OSA.

RESULTS

In the overall analysis, contrary to IL-10, which showed a significant reduction, IL-1β, IL-4, IL-8, IL-17, and IFN- gamma showed higher levels in OSA patients in comparison with control groups (p <0.05). For adults, IL-1β, IL-8, IL-17, IL-18, vaspin, visfatin, and chemerin were linked to a greater serum levels in patients with OSA, while, IL-5 and IL-10 were detected significantly lower in adults with OSA in comparison with healthy adults (p <0.05). In children with OSA, the serum levels of IL-4, IL-8, IL-12, IL-17, IL-23, and IFN-gamma were significantly higher than healthy children (p <0.05).

CONCLUSION

The levels of inflammatory markers were found to be higher in OSA patients compared with control individuals, suggesting that adipocytokines may contribute to the pathology of OSA.

Association of matrix metalloproteinase‐9 and nitric oxide with hypertension in obstructive sleep apnea

Background

Patients with obstructive sleep apnea (OSA) are more likely to suffer from hypertension. At the same time, the serum levels of matrix metalloproteinase‐9 (MMP‐9) and nitric oxide (NO) in patients with OSA are also changed in OSA patients. We investigated the correlation between serum levels of MMP‐9, NO in patients with OSA and their association with hypertension in those patients, and the effects of continuous positive airway pressure therapy (CPAP) on these serum biomarkers and blood pressure.

Methods

Serum MMP‐9 and NO levels and blood pressure of 57 patients with newly diagnosed OSA and 30 controls were measured; among them, 30 patients with moderate to severe OSA underwent 3‐month CPAP treatment.

Results

In comparison to the control group, the MMP‐9 serum levels were higher (232.8 ± 103.2 ng/ml versus 161.6 ± 56.5 ng/ml, p < .001*), there was no statistical significance difference among serum NO (26.7 ± 9.1 IU/ml versus 31.0 ± 11.7 IU/ml, p = .06), and MMP‐9 was negatively correlated to NO, especially in patients with hypertension (r = −.644, p = .02*). MMP‐9, NO, and blood pressure were significantly recovered in the patients with OSA after CPAP treatment for 3 months (p < .05*).

Conclusion

The MMP‐9 level and the NO level were altered in OSA patients. The relationship between the two especially in patients with hypertension suggests the potential mechanism of OSA‐induced hypertension.

Manuscript Title: A 4-miRNAs Serum Panel for Obstructive Sleep Apnea Syndrome Screening

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a common chronic sleep disorder. OSAS is closely related to cardiovascular disease, metabolic disorders, cancer risk, and sudden death. This association has special significance in young people. Although it is known that OSAS has a great impact on physical health, it is estimated that 70-80% of patients with moderate-to-severe OSAS remain undiagnosed. Therefore, a new method for early diagnosis of the disease, the therapeutic effect of OSAS and prevention of complications to important.

METHODS

A total of 110 patients with moderate-to-severe OSAS diagnosed in the Sleep Disorders Diagnosis and Treatment Center of Peking University Shenzhen Hospital were selected. After excluding other diseases, 59 patients were finally selected as the OSAS group. In addition, 60 healthy people were selected as the control group. Serum RNA was then extracted. Eight RNA samples were randomly selected from the two groups for high-throughput miRNA sequencing. The 10 miRNAs with the greatest differences were selected as preselected markers from the results. Then, qRT-PCR was performed on the remaining RNA samples of the two groups to extract and verify the 10 miRNAs, and statistical analysis was performed between groups.

RESULTS

A diagnostic panel was constructed by a stepwise logistic regression model combined with the expression data of miRNAs in the validation phase. A four-miRNA panel was identified to better predict OSAS, and the model was calculated using the following formula: Logit (P)= 0.77-1.65 × miR-486-5p - 4.56 × miR-148a-3p + 1.79 × miR-744-5p + 1.13 × let-7d-3p. The AUC for the four-miRNA panel was 0.955 (95% CI: 0.899 to 0.985; sensitivity = 91.38%, specificity = 91.38%). Gene Ontology (GO) annotation and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis was included in bioinformatic analysis.

CONCLUSION

A 4-miRNAs panel as a diagnostic biomarker for OSAS screening is feasible.

Interleukin-8 concentrations in obstructive sleep apnea syndrome: a systematic review and meta-analysis

Interleukin (IL)-8 has been shown to play an important role in obstructive sleep apnea syndrome (OSAS). However, its role in OSAS development is still controversial. This meta-analysis was to explore the correlation between interleukin (IL)-8 concentration and OSAS. Database (from the inception to July 2021) searches on PubMed, Web of Science, Medline, EMBASE, and Cochrane Library were conducted for studies analyzing the correlation between IL-8 concentration and OSAS, regardless of the language of publication. Standardized mean difference (SMD) and 95% confidence intervals (CI) were used to analyze any prospective association between IL-8 concentration and OSAS. A total of 25 eligible studies, including 2301 participants and 1123 controls, were included in this meta-analysis. The included studies evaluating the association between serum IL-8 concentration and OSAS indicated that adults and children with OSAS had elevated serum concentrations of IL-8 compared with controls (SMD = 0.997, 95% CI = 0.437–1.517, P < 0.001; SMD = 0.431, 95% CI = 0.104–0.759, P = 0.01). Categorization of the study population into subgroups according to body mass index, apnea–hypopnea index (AHI), ethnicity, and sample size also showed that individuals with OSAS had elevated serum concentrations of IL-8 compared with controls. Additionally, the results demonstrated that the higher the AHI, higher was the IL-8 concentration. Similar results were observed in the literature on the association between plasma IL-8 concentration and OSAS. This meta-analysis verified that compared with controls, children and adults with OSAS have significantly elevated IL-8 concentrations.

A Novel Pyroptosis-Related Gene Signature for Early-Stage Lung Squamous Cell Carcinoma

Background

Diagnosis of early stage lung squamous cell carcinoma (LUSC) has improved; however, a comprehensive analysis of prognostic signatures is needed.

Purpose

To identify, establish, and validate a signature model based on pyroptosis-related genes for prognostic predictions of early stage LUSC.

Patients and Methods

Two independent cohorts were included. RNA-seq transcriptome data from patients with early stage LUSC were obtained from The Cancer Genome Atlas (TCGA) database. Thirty-three pyroptosis-related genes were analyzed between early stage LUSC and normal lung tissues. Cox regression analysis, random survival forest, and least absolute shrinkage and selection operator algorithms established a three-gene signature. Kaplan–Meier survival and receiver-operating characteristic curves assessed the prognostic efficacy of the model. Single-sample gene set enrichment analysis (ssGSEA) assessed the relationship between pyroptosis and immune cells. Patients with early stage LUSC from the GSE74777 dataset were used for validation. Pyroptosis-related genes were verified by RT-qPCR and Western blotting.

Results

Twenty-three differentially expressed pyroptosis-related genes were identified in the LUSC and adjacent normal tissues. Three differentially expressed pyroptosis-related genes were identified as hub genes in early stage LUSC. Patients with early stage LUSC in the TCGA cohort were classified into low- and high-risk subgroups according to the risk score. Overall survival (OS) was significantly short in the high-risk subgroup versus the low-risk subgroup. A similar result was found for the GSE74777 dataset. ssGSEA of immune cells and immune-related pathways between the low- and high-risk subgroups may explain the different OS for patients with early-stage LUSC. IL-6 expression was upregulated, which was inconsistent with the bioinformatic analysis. NOD1 and CASP4 were downregulated in LUSC (all P < 0.05) versus normal lung tissues.

Conclusion

Differentially expressed pyroptosis-related genes may be involved in early stage LUSC. Pyroptosis-related genes are important in tumor immunity and may be potential prognostic predictors for early stage LUSC.

Nasal Nitric Oxide in the Upper Airway Inflammatory Diseases

Exhaled nitric oxide (eNO) from the lower respiratory tract is used commonly in diagnosis and treatment monitoring of asthma patients. However, nasal nitric oxide (nNO) has not been widely used in patients with upper airway inflammatory diseases due to its lack of standardized measurement methods. Nasal nitric oxide is produced mainly by the paranasal sinus mucosa and partially by the nasal mucosa and increases with inflammation. Nasal nitric oxide not only locally supports the defensive mechanism of the upper respiratory tract, but also remotely controls pulmonary function by acting as an aerocrine. Nasal NO can be affected by various physiologic and pathologic factors of the upper respiratory tract. This article will review the origin of nNO, its function, various measurement methods, and difference in presentation among upper respiratory tract inflammatory diseases such as allergic rhinitis, upper respiratory tract infection, nasal polyp, rhinosinusitis, primary ciliary dyskinesia, cystic fibrosis, Young’s syndrome, diffuse panbronchiolitis, empty nose syndrome, and obstructive sleep apnea. Future studies should identify the mechanism of action of nNO in various upper respiratory tract inflammatory diseases and obtain highly reproducible normal values of nNO based on a standardized measurement method with a deeper understanding of factors affecting nNO. Then, nNO will be useful for more rapid and simpler diagnosis of various upper respiratory tract diseases and for monitoring their treatment.

Exhaled volatilome analysis as a useful tool to discriminate asthma with other coexisting atopic diseases in women of childbearing age

The prevalence of asthma is considerably high among women of childbearing age. Most asthmatic women also often have other atopic disorders. Therefore, the differentiation between patients with atopic diseases without asthma and asthmatics with coexisting diseases is essential to avoid underdiagnosis of asthma and to design strategies to reduce symptom severity and improve quality of life of patients. Hence, we aimed for the first time to conduct an analysis of volatile organic compounds in exhaled breath of women of childbearing age as a new approach to discriminate between asthmatics with other coexisting atopic diseases and non-asthmatics (with or without atopic diseases), which could be a helpful tool for more accurate asthma detection and monitoring using a noninvasive technique in the near future. In this study, exhaled air samples of 336 women (training set (n = 211) and validation set (n = 125)) were collected and analyzed by thermal desorption coupled with gas chromatography-mass spectrometry. ASCA (ANOVA (analysis of variance) simultaneous component analysis) and LASSO + LS (least absolute shrinkage and selection operator + logistic regression) were employed for data analysis. Fifteen statistically significant models (p-value < 0.05 in permutation tests) that discriminated asthma with other coexisting atopic diseases in women of childbearing age were generated. Acetone, 2-ethyl-1-hexanol and a tetrahydroisoquinoline derivative were selected as discriminants of asthma with other coexisting atopic diseases. In addition, carbon disulfide, a tetrahydroisoquinoline derivative, 2-ethyl-1-hexanol and decane discriminated asthma disease among patients with other atopic disorders. Results of this study indicate that refined metabolomic analysis of exhaled breath allows asthma with other coexisting atopic diseases discrimination in women of reproductive age.

Prevalence and impact of comorbid obstructive sleep apnoea in diffuse parenchymal lung diseases

Objective

Obstructive sleep apnea (OSA) are increasingly recognized as important features in diffuse parenchymal lung diseases (DPLDs) with differed prevalence and impact reported. The aim of this study is to systematically review the prevalence of comorbid OSA and characterize its impact on clinical and outcome measurements in adults with DPLDs.

Methods

Publications addressing the prevalence of OSA in DPLDs and its impacts on DPLDs were selected from electronic databases. A random-effect model was used to estimate the pooled prevalence of OSA. Odds ratios (ORs) or mean differences (MDs) were used to assess the associations of OSA with clinical and outcome measurements. Heterogeneity was quantified by I² with 95% confidence interval (95% CI).

Results

4 studies comprising 643 participants were included. Overall, the pooled prevalence of OSA among DPLDs was 72% (95% CI: 65–79%; I² = 75.4%). Moderate-severe OSA was observed in 40% patients (95% CI: 28–52%; I² = 90.8%). The prevalence was higher as 76% in idiopathic pulmonary fibrosis (IPF) patients than in connective tissue associated-ILD or sarcoidosis (60%). Although oxygen desaturation during sleep was greater in OSA group compared with non-OSA patients, there was no difference in lung function or systematic comorbidities between the two groups. The associations between OSA and the mortality or disease progression of DPLDs were also systematically reviewed.

Conclusion

In conclusion, OSA is a common comorbidity in DPLD patients, affecting approximately three in four patients, which may exacerbate the nocturnal desaturation and have negative influence on the outcomes. Larger studies with more homogeneous samples are warranted.

Extended Exhaled Nitric Oxide Analysis in Interstitial Lung Diseases: A Systematic Review

Fractional exhaled nitric oxide (FeNO) is a well-known and widely accepted biomarker of airways inflammation that can be useful in the therapeutic management, and adherence to inhalation therapy control, in asthmatic patients. However, the multiple-flows assessment of FeNO can provide a reliable measurement of bronchial and alveolar production of NO, supporting its potential value as biomarker also in peripheral lung diseases, such as interstitial lung diseases (ILD). In this review, we first discuss the role of NO in the pathobiology of lung fibrosis and the technique currently approved for the measurement of maximum bronchial flux of NO (J'awNO) and alveolar concentration of NO (CaNO). We systematically report the published evidence regarding extended FeNO analysis in the management of patients with different ILDs, focusing on its potential role in differential diagnosis, prognostic evaluation and severity assessment of disease. The few available data concerning extended FeNO analysis, and the most common comorbidities of ILD, are explored too. In conclusion, multiple-flows FeNO analysis, and CaNO in particular, appears to be a promising tool to be implemented in the diagnostic and prognostic pathways of patients affected with ILDs.

Intermittent hypoxia induces turbinate mucosal hypertrophy via upregulating the gene expression related to inflammation and EMT in rats

PURPOSE

Chronic intermittent hypoxia (IH) plays a pivotal role in the consequences of obstructive sleep apnea (OSA). It has been demonstrated that IH impairs nasomaxillary complex growth to reduce nasal airway cavity size in rodent models. Although turbinate dysfunction with inflammatory mucosal hypertrophy is related to OSA, the role of IH in turbinate hypertrophy with inflammation-driven fibrosis is unknown. Here, we aimed to clarify the pathogenesis of inflammatory mucosal hypertrophy and epithelial-mesenchymal transition (EMT) in the nasal turbinate under IH.

METHODS

Seven-week-old male Sprague-Dawley rats were exposed to IH (4% O₂ to 21% O₂ with 0% CO₂) at a rate of 20 cycles/h.

RESULTS

Hypertrophy of the turbinate mucosa occurred after 3 weeks, with the turbinate mucosa of the experimental group becoming significantly thicker than in the control group. Immunostaining showed that IH increased the expression of TGFβ and N-cadherin and decreased E-cadherin expression in the turbinate mucosa. Quantitative PCR analysis demonstrated that IH enhanced the expression of not only the inflammatory markers Tnf-a, Il-1b, and Nos2 but also the EMT markers Tgf-b1, Col1a1, and Postn.

CONCLUSIONS

Collectively, these results suggest that IH induced turbinate hypertrophy via upregulation of gene expression related to inflammation and EMT in the nasal mucosa.

Exhaled Breath Analysis in Obstructive Sleep Apnea Syndrome: A Review of the Literature

Background and Objectives: Obstructive sleep apnea syndrome (OSAS) represents an independent risk factor for cardiovascular, metabolic and neurological events. Polysomnography is the gold-standard for the diagnosis, however is expensive and time-consuming and not suitable for widespread use. Breath analysis is an innovative, non-invasive technique, able to provide clinically relevant information about OSAS. This systematic review was aimed to outline available evidence on the role of exhaled breath analysis in OSAS, taking into account the techniques’ level of adherence to the recently proposed technical standards. Materials and Methods: Articles reporting original data on exhaled breath analysis in OSAS were identified through a computerized and manual literature search and screened. Duplicate publications, case reports, case series, conference papers, expert opinions, comments, reviews and meta-analysis were excluded. Results: Fractional exhaled Nitric Oxide (FeNO) is higher in OSAS patients than controls, however its absolute value is within reported normal ranges. FeNO association with AHI is controversial, as well as its change after continuous positive airway pressure (C-PAP) therapy. Exhaled breath condensate (EBC) is acid in OSAS, cytokines and oxidative stress markers are elevated, they positively correlate with AHI and normalize after treatment. The analysis of volatile organic compounds (VOCs) by spectrometry or electronic nose is able to discriminate OSAS from healthy controls. The main technical issues regards the dilution of EBC and the lack of external validation in VOCs studies. Conclusions: Exhaled breath analysis has a promising role in the understanding of mechanisms underpinning OSAS and has demonstrated a clinical relevance in identifying individuals affected by the disease, in assessing the response to treatment and, potentially, to monitor patient’s adherence to mechanical ventilation. Albeit the majority of the technical standards proposed by the ERS committee have been followed by existing papers, further work is needed to uniform the methodology.