Clinical application of nasal nitric oxide measurement in allergic rhinitis: A systematic review and meta-analysis

Nasal nitric oxide measurement in allergic rhinitis and non-allergic rhinitis: a meta-analysis

The goal of this meta-analysis was to study nasal nitric oxide (nNO) measurements in allergic rhinitis (AR) and non-allergic rhinitis (non-AR). The protocol was registered with PROSPERO (no: CRD4202124828). Electronic databases from PubMed, Google Scholar, Scopus, Web of Science, and Cochrane were all thoroughly searched and studies were chosen based on the qualifying requirements. The quality of the studies was evaluated by Joanna Briggs Institute evaluation tools, and publication bias using funnel plots. The meta-analysis included 18 studies, whereas the systematic review included 20 studies, totaling 3097 participants (1581 AR, 458 non-AR, and 1058 healthy/control). Patients with AR had significantly greater nNO levels than the control group, although this did not change significantly before or after treatment. AR patients had significantly greater nNO levels than non-AR patients, but there was no significant difference between non-AR patients and healthy controls. Nineteen of the studies were of high quality and the remaining one was of moderate quality. nNO measurement has a promising role in the management of AR and non-AR patients, but more investigations are needed to document clinical benefits.

Nitric oxide as a double-edged sword in pulmonary viral infections: Mechanistic insights and potential therapeutic implications

In the face of the global pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), researchers are tirelessly exploring novel therapeutic approaches to combat coronavirus disease 2019 (COVID-19) and its associated complications. Nitric oxide (NO) has appeared as a multifaceted signaling mediator with diverse and often contrasting biological activities. Its intricate biochemistry renders it a crucial regulator of cardiovascular and pulmonary functions, immunity, and neurotransmission. Perturbations in NO production, whether excessive or insufficient, contribute to the pathogenesis of various diseases, encompassing cardiovascular disease, pulmonary hypertension, asthma, diabetes, and cancer. Recent investigations have unveiled the potential of NO donors to impede SARS-CoV- 2 replication, while inhaled NO demonstrates promise as a therapeutic avenue for improving oxygenation in COVID-19-related hypoxic pulmonary conditions. Interestingly, NO's association with the inflammatory response in asthma suggests a potential protective role against SARS-CoV-2 infection. Furthermore, compelling evidence indicates the benefits of inhaled NO in optimizing ventilation-perfusion ratios and mitigating the need for mechanical ventilation in COVID-19 patients. In this review, we delve into the molecular targets of NO, its utility as a diagnostic marker, the mechanisms underlying its action in COVID-19, and the potential of inhaled NO as a therapeutic intervention against viral infections. The topmost significant pathway, gene ontology (GO)-biological process (BP), GO-molecular function (MF) and GO-cellular compartment (CC) terms associated with Nitric Oxide Synthase (NOS)1, NOS2, NOS3 were arginine biosynthesis (p-value = 1.15 x 10-9) regulation of guanylate cyclase activity (p-value = 7.5 x 10-12), arginine binding (p-value = 2.62 x 10-11), vesicle membrane (p-value = 3.93 x 10-8). Transcriptomics analysis further validates the significant presence of NOS1, NOS2, NOS3 in independent COVID-19 and pulmonary hypertension cohorts with respect to controls. This review investigates NO's molecular targets, diagnostic potentials, and therapeutic role in COVID-19, employing bioinformatics to identify key pathways and NOS isoforms' significance.

Nasal Nitric Oxide in Children: A Review of Current Outreach in Pediatric Respiratory Medicine

Nasal nitric oxide (nNO) is a gas synthesized by the inducible and constitutive NO synthase (NOS) enzyme in the airway cells of the nasal mucosa. Like lung nitric oxide, it is thought to be associated with airway inflammation in various respiratory diseases in children. The aim of our review was to investigate the current state of use of nNO measurement in children. A comprehensive search was conducted using the Web of Science and PubMed databases specifically targeting publications in the English language, with the following keywords: nasal NO, children, allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, primary ciliary dyskinesia (PCD), and cystic fibrosis (CF). We describe the use of nNO in pediatric allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, PCD, and CF based on the latest literature. nNO is a noninvasive, clinically applicable test for use in pediatric allergic rhinitis, chronic rhinosinusitis, acute rhinosinusitis, PCD, and CF. It can be used as a complementary method in the diagnosis of these respiratory diseases and as a monitoring method for the treatment of allergic rhinitis and acute and chronic rhinosinusitis.

Clinical Applications of Nasal Nitric Oxide in Allergic Rhinitis: A Review of the Literature

Allergic rhinitis, a common allergic disease affecting a significant number of individuals worldwide, is observed in 25% of children and 40% of adults, with its highest occurrence between the ages of 20 and 40. Its pathogenesis, like other allergic diseases, involves innate and adaptive immune responses, characterized by immunologic hypersensitivity to environmental substances. This response is mediated by type 2 immunity. Within type 2 allergic diseases, certain molecules have been identified as clinical biomarkers that contribute to diagnosis, prognosis, and therapy monitoring. Among these biomarkers, nitric oxide has shown to play a key role in various physiological and pathological processes, including neurotransmission, immunity, inflammation, regulation of mucus and cilia, inhibition of microorganisms, and tumor cell growth. Therefore, measurement of nasal nitric oxide has been proposed as an objective method for monitoring airway obstruction and inflammation in different settings (community, hospital, rehabilitation) and in various clinical conditions, including upper airways diseases of the nose and paranasal sinuses. The purpose of this review is to analyze the potential mechanisms contributing to the production of nasal nitric oxide in allergic rhinitis and other related health issues. Additionally, this review aims to identify potential implications for future research, treatment strategies, and long-term management of symptoms.

Nasal Nitric Oxide as a Biomarker in the Diagnosis and Treatment of Sinonasal Inflammatory Diseases: A Review of the Literature

OBJECTIVE

To critically review the literature on nasal nitric oxide (nNO) and its current clinical and research applicability in the diagnosis and treatment of different sinonasal inflammatory diseases, including acute bacterial rhinosinusitis (ABRS), allergic rhinitis (AR), and chronic rhinosinusitis (CRS).

METHODS

A search of the PubMed database was conducted to include articles on nNO and sinonasal diseases from January 2003 to January 2020. All article titles and abstracts were reviewed to assess their relevance to nNO and ABRS, AR, or CRS. After selection of the manuscripts, full-text reviews were performed to synthesize current understandings of nNO and its applications to the various sinonasal inflammatory diseases.

RESULTS

A total of 79 relevant studies from an initial 559 articles were identified using our focused search and review criteria. nNO has been consistently shown to be decreased in ABRS and CRS, especially in cases with nasal polyps. While AR is associated with elevations in nNO, nNO levels have also been found to be lower in AR cases with higher symptom severity. The obstruction of the paranasal sinuses is speculated to be an important variable in the relationship between nNO and the sinonasal diseases. Treatment of these diseases appears to affect nNO through the reduction of inflammatory disease burden and also mitigation of sinus obstruction.

CONCLUSION

nNO has been of increasing interest to researchers and clinicians over the last decade. The most compelling data for nNO as a clinical tool involve CRS. nNO can be used as a marker of ostiomeatal complex patency. Variations in measurement techniques and technology continue to impede standardized interpretation and implementation of nNO as a biomarker for sinonasal inflammatory diseases.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Nasal nitric oxide flux from the paranasal sinuses

PURPOSE OF REVIEW

Upper airway nitric oxide (NO) is physiologically important in airway regulation and defense, and can be modulated by various airway inflammatory conditions, including allergic rhinitis and chronic rhinosinusitis - with and without polyposis. Paranasal sinuses serve as a NO 'reservoir', with concentrations typically exceeding those measured in lower airway (fractional exhaled NO or FeNO) by a few orders of magnitude. However, the dynamics of NO flux between the paranasal sinuses and main nasal airway, which are critical to respiratory NO emission, are poorly understood.

RECENT FINDINGS

Historically, NO emissions were thought to be contributed mostly by the maxillary sinuses (the largest sinuses) and active air movement (convection). However, recent anatomically-accurate computational modeling studies based on patients' CT scans showed that the ethmoid sinuses and diffusive transport dominate the process.

SUMMARY

These new findings may have a substantial impact on our view of nasal NO emission mechanisms and sinus physiopathology in general.

Endotyping Seasonal Allergic Rhinitis in Children: A Cluster Analysis

Background

Seasonal Allergic Rhinitis (SAR) is a heterogeneous inflammatory disease. We hypothesized that a cluster analysis based on the evaluation of cytokines in nasal lavage (NL) could characterize distinctive SAR endotypes in children.

Methods

This cross-sectional study enrolled 88 children with SAR. Detailed medical history was obtained by well-trained physicians. Quality of life and sleep quality were assessed through standardized questionnaires [Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ) and Pittsburgh Sleep Quality Index (PSQI) respectively]. Children were grouped through K-means clustering using Interleukin (IL)-5, IL-17, IL-23, and Interferon (INF)-γ in NL.

Results

Out of the 88 patients enrolled, 80 were included in the cluster analysis, which revealed three SAR endotypes. Cluster 1 showed lower levels of IL-5 and IL-17 and intermediate levels of IL-23 and IFN-γ; Cluster 2 had higher levels of IL-5 and intermediate levels of IL-17, IL-23, and IFN-γ; Cluster 3 showed higher levels of IL-17, IL-23, and IFN-γ and intermediate levels of IL-5. Cluster 1 showed intermediate values of nasal pH and nasal nitric oxide (nNO), and a lower percentage of neutrophils at nasal cytology than Clusters 2 and 3. Cluster 2 had a lower level of nasal pH, a higher nNO, higher scores in the ocular domain of PRQLQ, and worse sleep quality than Clusters 1 and 3. Cluster 3 showed a higher percentage of neutrophils at nasal cytology than Clusters 1 and 2.

Conclusions

Our study identified three endotypes based on the evaluation of cytokines in NL, highlighting that childhood SAR is characterized by heterogeneous inflammatory cytokines.

Performance of fractional exhaled nitric oxide in predicting response to inhaled corticosteroids in chronic cough: a meta-analysis

Background. Chronic cough is a disabling condition with a high proportion of diagnostic and therapeutic failures. Fractional exhaled nitric oxide (FeNO) has been considered a useful biomarker for predicting inhaled corticosteroids (ICS) response. We evaluated the relationship between FeNO and ICS response in chronic cough by performing a systematic review with meta-analysis.Methods. PubMed, Web of Science, Scopus and EMBASE databases were systematically searched. Differences were expressed as Odds Ratio (OR) with 95% confidence intervals (95%CI). Pooled sensitivity, specificity, positive (PLR) and negative likelihood ratio (NLR), and area under the hierarchical summary receiver operating characteristic curve (HSROCAUC) were estimated.Results. Nine articles on 740 chronic-cough patients showed that the response rate to ICS was 87.4% (95%CI: 83.8-91.0) in 317 patients with a high FeNO and 46.3% (95%CI: 41.6-51.0) in 423 controls, with an attributable proportion of 47.0% and a diagnostic OR of 9.1 (95%CI: 3.7-22.4, p < .001). The pooled estimate of diagnostic indexes resulted in a sensitivity of 68.5% (95%CI: 46.7-84.4) and specificity of 81.9% (95%CI: 63.0-92.3), with a HSROCAUC of 0.82 (95%CI: 0.64-0.90). In a realistic scenario with a pre-test probability set at 30%, based on a pooled PLR of 3.79 (95%CI: 1.24-7.47) and NLR of 0.38 (95%CI: 0.22-0.66), the post-test probability was 62% with a high FeNO and 14% if the test was negative. Subgroup analyses confirmed a better performance for the recommended FeNO cut-off greater than 25 ppb. Meta-regression and sensitivity analyses showed no impact of major demographic and clinic variables on results.Conclusions. A high FeNO before starting ICS therapy may help identify chronic-cough patients responding to treatment, with a better performance ofhigher cut-off values. Further studies are needed to evaluate the real usefulness of this biomarker to guide cough therapy and optimise strategies in different healthcare settings (community, hospital, rehabilitation).Key messagesChronic cough is a disabling condition with a high proportion of diagnostic and therapeutic failures.Fractional exhaled nitric oxide (FeNO) may be a useful biomarker for identifying chronic cough patients who respond to steroid treatment.A FeNO cut-off lower than 25 ppb should be considered irrelevant for this clinical application.

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.

The Role of Nasal Nitric Oxide and Anterior Active Rhinomanometry in the Diagnosis of Allergic Rhinitis and Asthma: A Message for Pediatric Clinical Practice

Background

Allergic rhinitis (AR) and asthma are two common atopic diseases, often associated with a common ethiopathogenesis characterized by a Th2 inflammatory response with the release of many biomarkers, such as nitric oxide (NO).

Purpose

To evaluate and compare inflammatory (nFeNO and eFeNO) and functional (mNF and FEV1) parameters in AR children with or without asthma in comparison to controls. Secondly, we aimed to identify nFeNO cut-off values and verify their reliability to predict the presence of rhinitis or asthma alone or in combination.

Patients and Methods

We enrolled 160 children (6-12 years of age) with AR and/or asthma divided into four groups: controls, AR, asthma, and AR + asthma. All children underwent the following inflammatory and functional measurements: nFeNO, eFeNO, mNF and FEV1.

Results

We observed that levels of nFeNO were extremely higher in children with AR and even more in those with AR + asthma in respect to controls. Notably, all the pathological conditions, especially AR + asthma, showed significantly lower values of mNF compared to healthy children. A negative correlation linked mNF and nFeNO. Then, we found eFeNO values significantly higher in all the pathological groups compared to controls, with major values of this marker in patients affected by asthma and AR + asthma, as well as FEV1 values significantly lower in all the disease groups, especially in children with asthma and AR+ asthma. ROC curve analysis showed that nFeNO was a great predictor for rhinitis alone or with asthma, revealing an accurate cut-off of 662 ppb.

Conclusion

nFeNO measurement is non-invasive, easy to perform, economic and a valuable test in case of AR alone or in association with asthma. Thus, it should be used in patients with rhinitis, together with anterior active rhinomanometry (AAR) to diagnose and estimate the degree of nasal obstruction but also in children with asthma to assess their nasal involvement and improve the therapeutic management.