The Clinical Significance of Nasal Nitric Oxide Concentrations in Preschool Children with Nasal Inflammatory Disease

Role of Nasal Nitric Oxide in Primary Ciliary Dyskinesia and Other Respiratory Conditions in Children

Nitric oxide (NO) is produced within the airways and released with exhalation. Nasal NO (nNO) can be measured in a non-invasive way, with different devices and techniques according to the age and cooperation of the patients. Here, we conducted a narrative review of the literature to examine the relationship between nNO and some respiratory diseases with a particular focus on primary ciliary dyskinesia (PCD). A total of 115 papers were assessed, and 50 were eventually included in the review. nNO in PCD is low (below 77 nL/min), and its measurement has a clear diagnostic value when evaluated in a clinically suggestive phenotype. Many studies have evaluated the role of NO as a molecular mediator as well as the association between nNO values and genotype or ciliary function. As far as other respiratory diseases are concerned, nNO is low in chronic rhinosinusitis and cystic fibrosis, while increased values have been found in allergic rhinitis. Nonetheless, the role in the diagnosis and prognosis of these conditions has not been fully clarified.

Allergic Rhinitis in Preschoolers: A Systematic Review of Diagnostics

BACKGROUND

Most studies that seek to analyze the prevalence of allergic rhinitis do not include preschool children and the diagnosis in this age group is difficult.

OBJECTIVE

Identify complementary tests to the diagnosis of allergic rhinitis in preschool children and verify if there is scientific robustness to propose a diagnostic algorithm for this condition in this age group.

METHODS

Systematic review of the literature in four databases: SCIELO, PubMed/MEDLINE, LILACS and SCOPUS. Each article was initially chosen by title, abstract and by the keywords "allergic rhinitis," "diagnosis" and "preschool." Those articles selected entered the complete reading and data extraction phase. The study was registered in the International Prospective Register of Systematic Reviews under number CRD42020207053.

RESULTS

Fourteen articles were suitable for analysis. In the assessment using Quality Assessment of Diagnostic Accuracy Studies - 2, all studies had at least one domain considered "high risk" or "undetermined risk." Seven reports of nasal cytology, seven of specific IgE, four of immediate hypersensitivity skin test, one of nasal nitric oxide, three of total IgE and one of urinary leukotriene E4 were found. Eight articles evaluated more than one diagnostic test.

CONCLUSION

There are no defined criteria for the diagnosis of allergic rhinitis in preschool children. Nasal cytology, serum specific IgE and immediate hypersensitivity skin test were the most used tests. A reliable diagnostic criterion in this age group is necessary so that in the future it is possible to propose a diagnostic algorithm for allergic rhinitis in preschool children.

Numerical study on the distribution of nitric oxide concentration in the nasal cavity of healthy people during breathing

BACKGROUND

In the nasal cavity, nitric oxide (NO) is involved in many physiological functions, including antibacterial and antiviral activity, promotion of nasal mucociliary clearance, and regulation of blood vessel expansion in the nasal mucosa. We investigated the distribution of NO concentration in the nasal cavity of healthy individuals during breathing.

METHODS

A three-dimensional numerical model of the nasal airway, including the bilateral maxillary sinuses, was created to simulate NO distribution in the nasal cavity during normal breathing. The effect of different nasal airflow velocities and NO concentrations in the maxillary sinus on NO distribution in the nasal cavity was evaluated. The NO concentration in the nasal exhalation of 50 healthy people in Dalian was measured using an NO analyzer, and the growth rate of the NO concentration in the nasal cavity was measured under breath-holding conditions.

RESULTS

The distribution of NO concentration in the nasal cavity of healthy people during breathing was obtained from numerical simulation results. Lower the airflow rate, higher was the NO concentration and greater was the diffusion range in the nasal cavity. The NO concentration in the nasal cavity increased with an increase in its concentration in the maxillary sinus, indicating a linear relationship. The NO concentration in the nasal exhalation of healthy people in Dalian and the growth rate of the NO concentration in the nasal cavity under breath-holding conditions were obtained through experiments. The numerical results correspond with the experimental results.

CONCLUSIONS

The NO entered the nasal cavity mainly by diffusion and followed the convection flow of the respiratory air in the nasal cavity. NO concentration in the nasal cavity was related to the respiratory airflow velocity and NO concentration in the maxillary sinus. During inspiration, NO was present only in the nasal airway posterior to the maxillary sinus ostium, whereas during exhalation, the exhaled NO diffusely distributed throughout the nasal cavity.

Defenses of multidrug resistant pathogens against reactive nitrogen species produced in infected hosts

Bacterial pathogens have sophisticated systems that allow them to survive in hosts in which innate immunity is the frontline of defense. One of the substances produced by infected hosts is nitric oxide (NO) that together with its derived species leads to the so-called nitrosative stress, which has antimicrobial properties. In this review, we summarize the current knowledge on targets and protective systems that bacteria have to survive host-generated nitrosative stress. We focus on bacterial pathogens that pose serious health concerns due to the growing increase in resistance to currently available antimicrobials. We describe the role of nitrosative stress as a weapon for pathogen eradication, the detoxification enzymes, protein/DNA repair systems and metabolic strategies that contribute to limiting NO damage and ultimately allow survival of the pathogen in the host. Additionally, this systematization highlights the lack of available data for some of the most important human pathogens, a gap that urgently needs to be addressed.

Application of fractional exhaled nitric oxide and nasal nitric oxide in control evaluation of bronchial asthma and diagnosis of allergic rhinitis in children

OBJECTIVES

To study the association of fractional exhaled nitric oxide (FeNO) and nasal nitric oxide (nNO) with asthma control and their value in the diagnosis of allergic rhinitis in children.

METHODS

A total of 186 children aged 5-12 years, who attended the outpatient service of the Department of Respiration, Shanghai Children's Hospital due to bronchial asthma and/or allergic rhinitis or who underwent physical examination, were enrolled as subjects, with 52 children in the asthma group, 60 children in the asthma+allergic rhinitis group, 36 children in the allergic rhinitis group, and 38 children in the control group. FeNO, nNO, and pulmonary function were compared between groups.

RESULTS

The asthma+allergic rhinitis, asthma, and allergic rhinitis groups had a significantly higher level of FeNO than the control group (P<0.05). The asthma+allergic rhinitis and allergic rhinitis groups had a significantly higher level of nNO than the asthma and control groups (P<0.05). The uncontrolled asthma and partially controlled asthma groups had significantly higher levels of FeNO and nNO than the completely controlled asthma group (P<0.05). The receiver operating characteristic (ROC) curve analysis showed that nNO had an area under the ROC curve of 0.91, with a sensitivity of 80.0% and a specificity of 89.5% in the diagnosis of allergic rhinitis in children with asthma (P<0.05).

CONCLUSIONS

The combined measurement of nNO and FeNO can be used to evaluate the control of asthma, and the measurement of nNO can help with the diagnosis of allergic rhinitis in children with bronchial asthma.

Clinical application of fractional exhaled nitric oxide and nasal nitric oxide levels for the assess eosinophilic inflammation of allergic rhinitis among children

BACKGROUND

Allergic rhinitis is one of the most common nasal inflammatory diseases among children. Assessment of clinical symptoms, skin prick test and serum immunoglobulin E (IgE) are common methods used to diagnose allergic rhinitis and assess inflammation degree in clinical settings. However, via blood tests assess eosinophils inflammation is invasive, and may cause fear in children. It makes have burden of the diagnosis of allergic rhinitis. Nasal nitric oxide (nNO) and fractional exhaled nitric oxide (FeNO) are noninvasive, inexpensive, and can provide immediate results. These methods may therefore be preferable to assess the inflammation of allergic rhinitis.

METHODS

This study was a retrospective analysis. We recruited 61 children with allergic rhinitis from November 2019 to March 2020. The participants were assessed using the FeNO and nNO tests. We also administered questionnaires and carried out traditional allergen and blood tests. We analyzed the relationship between diagnosis results and FeNO and nNO levels before and after the treatment of allergic rhinitis, to investigate the clinical application of FeNO and nNO levels for assess eosinophilic inflammation of allergic rhinitis in children.

RESULTS

We observed a significant association both FeNO, nNO level with eosinophils, total IgE. In different levels of eosinophils (EOS), the correlation of detection parameters had obvious change. FeNO and nNO levels were obvious higher compared to pre-treatment.

CONCLUSIONS

Using NO concentration can indicates the extent of allergic inflammation and can measure allergy treatment effects combine other influence indexes. The combined use of FeNO and nNO levels may be a useful method for assess the degree of eosinophilic inflammation of allergic rhinitis in children.

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.

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

BACKGROUND

Nasal nitric oxide (nNO) is considered a biomarker of nasal inflammation.

OBJECTIVE

To perform a systematic review with meta-analysis and meta-regressions on the association between nNO levels and allergic rhinitis (AR).

METHODS

PubMed, Web of Science, Scopus, and EMBASE databases were systematically searched. Differences between cases and controls were expressed as standardized mean differences (SMD) with 95% confidence intervals (CI).

RESULTS

Overall, 39 articles were included: 30 containing data on nNO measured by nasal aspiration (1881 patients with AR and 1337 controls) and 12 assessing nNO by nasal exhalation (525 patients with AR and 350 controls). Compared with controls, AR presented significantly higher nNO values both during nasal aspiration (SMD, 1.309; 95% CI, 0.841-1.777; P < .001) and nasal exhalation (SMD, 0.708; 95% CI, 0.303-1.114; P = .001). Sensitivity and subgroup analyses confirmed that the results for the evaluated outcomes were not affected by the presence of clinical confounding factors (asthma, nasal polyps, inhaled corticosteroids, smoking history), this being valid for both perennial and seasonal diseases during exposure to allergens. For the aspiration method, meta-regressions indicated that older age and a better pulmonary function were associated with a lower difference in nNO levels between patients with AR and controls, whereas an increasing aspiration flow was associated with a high effect size.

CONCLUSION

nNO levels are higher in AR, particularly when using high aspiration flows and in younger patients, who often perceive this condition as a source of disability. Further studies are needed to evaluate the usefulness of this biomarker for monitoring airway disorders and optimizing strategies in different settings (community, hospital, rehabilitation).