Localization of nitric oxide synthase in human nasal mucosa with nasal allergy

Levels of nasal nitric oxide and nitric oxide synthase expression in chronic rhinosinusitis with nasal polyposis

KEY POINTS

CRSwNP patients had decreased nNO and increased SNOT-22, endoscopy, and CT scores. CRSwNP patients exhibited decreased nNO despite elevated iNOS and eNOS mRNA expression. The mechanism behind lowered nNO in CRSwNP may not be related to NOS expression.

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.

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).

Fractional Exhaled Nitric Oxide (FENO) in the management of asthma: a position paper of the Italian Respiratory Society (SIP/IRS) and Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC)

Asthma prevalence in Italy is on the rise and is estimated to be over 6% of the general population. The diagnosis of asthma can be challenging and elusive, especially in children and the last two decades has brought evidences that asthma is not a single disease but consists of various phenotypes. Symptoms can be underestimated by the patient or underreported to the clinician and physical signs can be scanty. Usual objective measures, like spirometry, are necessary but sometimes not significant. Despite proper treatment, asthma can be a very severe condition (even leading to death), however new drugs have recently become available which can be very effective in its control. Since asthma is currently thought to be caused by inflammation, a direct measure of the latter can be of paramount importance. For this purpose, the measurement of Fractional Exhaled Nitric Oxide (FE_NO) has been used since the early years of the current century as a non-invasive, easy-to-assess tool useful for diagnosing and managing asthma. This SIP-IRS/SIAAIC Position Paper is a narrative review which summarizes the evidence behind the usefulness of FE_NO in the diagnosis, management and phenotypization of asthma.

Nasal Nitric Oxide in Chronic Rhinosinusitis with or without Nasal Polyps: A Systematic Review with Meta-Analysis

Background and Aims: There has been a recent growing interest in the role of nasal nitric oxide (nNO) as a biomarker for osteomeatal complex obstruction in paranasal sinus diseases. By using meta-analysis, we systematically reviewed the literature to establish the possible link between nNO concentration and chronic rhinosinusitis with nasal polyps (CRSwNP) or without (CRSsNP). Methods: We systematically searched the EMBASE, PubMed, Scopus, and Web of Science databases for related studies. Differences between controls and cases were reported as standardized mean difference (SMD), with 95% confidence intervals (95% CI), using the random-effects method. Results: We selected 23 articles for the final analysis: 15 with data on 461 CRSwNP patients and 384 healthy controls, 10 with data on 183 CRSsNP patients and 260 controls, and 14 studies on 372 CRSwNP and 297 CRSsNP patients. CRSwNP patients showed significantly lower nNO values when compared to both healthy controls (SMD: −1.495; 95% CI: −2.135, −0.854; p < 0.0001) and CRSsNP patients (SMD: −1.448; 95% CI: −2.046, −0.850; p < 0.0001). Sensitivity and subgroup analyses confirmed the results, which were further refined by regression models. They showed that an increasing aspiration flow is related to a greater difference in nNO levels between cases and control subjects. We also documented lower nNO levels in CRSsNP patients with respect to controls (SMD: −0.696; 95% CI: −1.189, −0.202; p = 0.006), being this result no longer significant when excluding patients in therapy with intranasal corticosteroids. As shown by regression models, the increased Lund–Mackay score indicates a high effect size. Conclusions: nNO levels are significantly lower in CRSwNP, especially when using higher aspiration flows. Additional studies are needed to define one single standardized method and normal reference values for nNO.

Clinical Utility Of The Exhaled Nitric Oxide (NO) Measurement With Portable Devices In The Management Of Allergic Airway Inflammation And Asthma

Nitric oxide (NO) is a potential bioactive gas produced continuously and constantly in the airways of healthy subjects. In allergic airway inflammation, the level of exhaled NO is usually increased and mediated by inducible nitric oxide synthase (iNOS) enzyme presenting in the epithelium and different inflammatory cells. The measurement of NO concentration in the airway is possible with portable devices which use an electroluminescence technique. In subjects with upper airway with allergic inflammation such as in allergic rhinitis, the measurement of nasal NO (nNO) may help to diagnose and manage the disease. In the lower airway, increased fractional exhaled NO (FENO) reflects directly the inflammatory process that occurs in the airways that are typically seen in asthma. It has been shown that there is a strong correlation between FENO levels and increased activity of airway inflammation mediated by immuno-allergic cells and mediators. Thus, FENO has higher specificity and sensitivity than other methods in diagnosing the severity of inflammation in asthmatic patients. Moreover, the correlation between increased FENO levels and a high risk of bronchial hyperresponsiveness has also been demonstrated. FENO is also a relevant biomarker to evaluate asthma status due to the change of its values occurring earlier than clinical manifestations and spirometry parameters. In addition, the measurement of FENO with portable devices helps to support the diagnosis of asthma, to follow-up the control of asthma and to personalize asthmatic patients for target treatment with biologic therapy. Therefore, measuring FENO with portable devices in the diagnosis and treatment of allergic airway inflammation, especially in asthma, is one of the most essential applications of NO biomarkers in exhaled breath.

Nasal Nitric Oxide Is Correlated With Nasal Patency and Nasal Symptoms

PURPOSE

Nitric oxide (NO) is an important endogenous mediator in both upper and lower respiratory systems. The purpose of the present study was to extract nasal NO (nNO) normal range of Chinese adults and the internal influencing factors. The differences in nNO levels between rhinitis and asymptomatic atopic subjects, and the diagnostic value of nNO in allergic rhinitis (AR) were further investigated.

METHODS

One thousand adults were recruited from the general public. Participants were divided into different subgroups according to the questionnaires and skin prick tests. In all of these subjects, nNO, fractional exhaled NO (FeNO) and nasal airflow resistance were measured. The normal ranges of nNO and FeNO, the differences between subgroups, and the correlations between NO (nNO and FeNO) and other internal factors were analyzed.

RESULTS

Both nNO and FeNO levels were significantly higher in AR patients than in healthy and asymptomatic atopic subjects. The nNO levels were significantly lower in asymptomatic atopic subjects than in normal adults. FeNO levels were significantly higher in non-AR patients than in the healthy and asymptomatic atopic adults. The cutoff value of nNO for the diagnosis of AR was 117.5 ppb (sensitivity, 50.9%; specificity, 63.9%). The nNO levels were correlated with FeNO levels, total nasal resistance measured at 75Pa, nasal volume within 0-7 cm from the anterior nares (V_0-7cm) and nasal symptom visual analogue scale (VAS) scores, while the FeNO levels were correlated with age, height, weight, body surface area, nasal volume of V_0-7cm and the nasal symptom VAS score.

CONCLUSIONS

The nNO level can be significantly different between healthy and AR patients and may be significantly correlated with nasal symptoms and nasal patency of rhinitis patients. However, the clinical value of nNO is still in the exploration stage.

Physiology of nitric oxide in the respiratory system

Nitric oxide (NO) is an important endogenous neurotransmitter and mediator. It participates in regulation of physiological processes in different organ systems including airways. Therefore, it is important to clarify its role in the regulation of both airway and vascular smooth muscle, neurotransmission and neurotoxicity, mucus transport, lung development and in the. surfactant production. The bioactivity of NO is highly variable and depends on many factors: the presence and activity of NO-producing enzymes, activity of competitive enzymes (e.g. arginase), the amount of substrate for the NO production, the presence of reactive oxygen species and others. All of these can change NO primary physiological role into potentially harmful. The borderline between them is very fragile and in many cases not entirely clear. For this reason, the research focuses on a comprehensive understanding of NO synthesis and its metabolic pathways, genetic polymorphisms of NO synthesizing enzymes and related effects. Research is also motivated by frequent use of exhaled NO monitoring in the clinical manifestations of respiratory diseases. The review focuses on the latest knowledge about the production and function of this mediator and understanding the basic physiological processes in the airways.

Expression of TLR2 and TLR4 Messenger RNA in the Epithelial Cells of the Nasal Airway

Background

Epithelium of nasal mucosa is the first line of defense against invading pathogens. This study investigated the expression of Toll-like receptor (TLR) 2 and TLR4 in epithelial cells of nasal mucosa and understood the role of TLRs in the innate immunity of nasal mucosa.

Methods

Human nasal epithelial cells were obtained by scraping the middle one-third of inferior turbinates from 30 patients with chronic rhinosinusitis and 20 healthy adult volunteers. The epithelial cells are made into smears. In situ hybridization was performed for TLR2 and TLR4 messenger RNA (mRNA).

Results

TLR2 and TLR4 mRNA were expressed in the nasal epithelial cells. The expression of the two genes was significantly higher in the chronic rhinosinusitis group than in the normal control (TLR2, t = 8.605, p < 0.0005; TLR4, t = 9.050, p < 0.0005).

Conclusion

This study is the first to establish the presence of both TLR2 and TLR4 mRNA on epithelial cells of nasal mucosa, and their expression can be up-regulated in infectious conditions. These results show that TLR2 and TLR4 may play a important role in local host defense of nasal mucosa.

Interleukin-13 stimulates production of nitric oxide in cultured human nasal epithelium

The diversity and extent of signaling functions of nitric oxide (NO) in cell physiology as well as its presence and influence as a common component of ambient air pollution and tobacco smoke are gaining increasing research attention relative to both health and disease. While cellular NO production is typically associated with inflammatory cells and processes, the airway epithelium particularly of the paranasal sinuses, has been documented to be a rich source of excreted NO. Inasmuch as excreted NO derives from both mucosal and inflammatory cell sources, distinguishing the individual contribution of these compartments to total excreted cellular NO is potentially problematic. We simulated an inflammatory mucosal environment by stimulating human nasal epithelial cultures with interleukin-13 (IL-13), a mediator produced by eosinophils in asthma, allergic rhinitis, and sinusitis. While a consistent baseline of NO excretion in control cultures was documented, widely variable individual responses to IL-13 exposure were observed in companion cultures maintained under identical conditions and tested at the same time. These studies suggest that cellular NO excretion by the healthy epithelial mucosa is subject to considerable individual variability and may be significantly elevated among some individuals in the presence of IL-13 stimulation.

Xylitol nasal irrigation in the treatment of chronic rhinosinusitis

OBJECTIVE

To evaluate the efficacy of xylitol nasal irrigation (XNI) treatment on chronic rhinosinusitis (CRS) and to investigate the effect of XNI on nasal nitric oxide (NO) and inducible nitric oxide synthase (iNOS) mRNA in maxillary sinus.

MATERIALS AND METHODS

Patients with CRS were enrolled and symptoms were assessed by Visual Analog Scale (VAS) and Sino-Nasal Outcome Test 22 (SNOT-22). Nasal NO and iNOS mRNA in the right maxillary sinus were also examined. Then, they were treated with XNI (XNI group) or saline nasal irrigation (SNI, SNI group) for 30days, after which their symptoms were reassessed using VAS and SNOT-22, and nasal NO and iNOS mRNA in the right maxillary sinus were also reexamined.

RESULTS

Twenty-five out of 30 patients completed this study. The scores of VAS and SNOT-22 were all reduced significantly after XNI treatment, but not after SNI. The concentrations of nasal NO and iNOS mRNA in the right maxillary sinus were increased significantly in XNI group. However, significant changes were not found after SNI treatment. Furthermore, there were statistical differences in the assessments of VAS and SNOT-22 and the contents of nasal NO and iNOS mRNA in the right maxillary sinus between two groups.

CONCLUSIONS

XNI results in greater improvement of symptoms of CRS and greater enhancement of nasal NO and iNOS mRNA in maxillary sinus as compared to SNI.

Antiallergic effects of anti-interleukin-33 are associated with suppression of immunoglobulin light chain and inducible nitric oxide synthase

OBJECTIVE

We aimed to find novel genes that are significantly induced in allergic mice and that are significantly downregulated with anti-interleukin (IL) 33 treatment.

METHODS

Thirty-six mice were allocated into each of group A (intraperitoneal [i.p.]) sensitized and intranasally challenged to saline solution), group B (sensitized and challenged to ovalbumin), group C (sensitized and challenged with ovalbumin, and null treatment with i.p. saline solution), and group D (sensitized and challenged with ovalbumin, and treatment with anti-IL-33 i.p. injection). We counted the number of nose-scratching in 10 minutes, serum ovalbumin-specific immunoglobulin E (IgE), and titers of cytokines (IL-1, IL-4, IL-5, IL-10, IL-13) in bronchoalveolar lavage fluid. By using one whole lung from each mouse, we performed microarray analysis and real-time polymerase chain reaction.

RESULTS

group D showed a significantly reduced nose-scratching events and lower serum ovalbumin-specific IgE compared with groups B and C. All the cytokines in the bronchoalveolar lavage fluid were significantly decreased after anti-IL-33 treatment. Microarray analysis revealed that group B (immunoglobulin free light chain [IgFLC], 89.1 times; nitric oxide synthase [NOS] 2, 11.5 times) and group C (IgFLC, 141.6 times; NOS2, 11.7 times) had significantly increased expression of IgFLC and NOS2 genes compared with group A. After anti-IL-33 treatment, group D showed significantly decreased expression of both IgFLC (49.3 times) and NOS2 (6.5 times). In real-time polymerase chain reaction, groups B and C had significantly increased expression of these genes (IgFLC, 10.4 times and 29 times, respectively; NOS2, 3.8 times and 4.5 times, respectively). After treatment, group D showed significantly decreased expression of IgFLC (5.0 times) and NOS2 (2.5 times).

CONCLUSION

The antiallergic effect of anti-IL-33 can be explained by suppression of IgFLC and NOS2 in a murine model of allergic rhinitis.

Correlation of nasal nitric oxide measurement with computed tomography findings in chronic rhinosinusitis

Nitric oxide (NO) is a biological messenger produced by mammalian cells serving various functions including regulation of blood flow, platelet function, immunity, and neurotransmission. The paranasal sinuses and nasal mucosa are a major source of exhaled NO. The aim of the study is to compare the nasal NO (nNO) levels in patients with chronic rhinosinusitis with those of common cold patients and controls and to correlate CT scores with nNO levels. The nasal concentration of NO was measured by electroluminescence in 13 healthy volunteers, in 13 patients suffering from common cold and 13 patients with chronic rhinosinusitis. The concentration of NO was correlated with symptom scores, endoscopic findings and CT findings. The measured levels of NO did not differ between healthy volunteers and common cold patients, but they were significantly lower in patients suffering from chronic rhinosinusitis. As NO is a regulator of mucociliary activity and has bacteriostatic and antiviral effects, the decreased concentration of nNO in patients suffering from sinusitis suggests that lack of NO may contribute to the pathogenesis of this disease. Thus, nNO, which is easily measured, provides a valuable non-invasive objective measure of chronic rhinosinusitis.

Elevated guanylate cyclase and cyclic-guanosine monophosphate-dependent protein kinase levels in nasal mucosae of antigen-challenged rats

OBJECTIVE

In patients with severe allergic rhinitis, the most serious symptom is rhinostenosis, which is considered to be induced by a dilatation of plexus cavernosum. The vascular relaxing responses to chemical mediators are mainly mediated by the production of nitric oxide (NO). However, the exact mechanism(s) in nasal venoresponsiveness of allergic rhinitis is not fully understood. In the present study, we investigated the roles of soluble guanylate cyclase (sGC) and cyclic-guanosine monophosphate (c-GMP)-dependent protein kinase G (PKG) in venodilatation of nasal mucosae of antigen-challenged rats.

METHODS

Actively sensitized rats were repeatedly challenged with aerosolized antigen (2,4-dinitrophenylated Ascaris suum). Twenty-four hours after the final antigen challenge, nasal septum mucosa was exposed surgically and observed directly in vivo under a stereoscopic microscope. The sodium nitroprusside (SNP) and 8-Br-cGMP (a PKG activator) were administered into arterial injection, and the venous diameters of nasal mucosa were observed.

RESULTS

The intra-arterial injections of SNP and 8-Br-cGMP-induced venodilatation were significantly augmented in the nasal mucosae of repeatedly antigen-challenged rats. Furthermore, protein expressions of sGC and PKG were significantly increased in nasal mucosae of the antigen-challenged rats.

CONCLUSION

The present findings suggest the idea that the promoted cGMP/PKG pathway may be involved in the enhanced NO-induced venodilatation in nasal mucosae of antigen-challenged rats.

N-acetylcysteine exerts therapeutic action in a rat model of allergic rhinitis

BACKGROUND

The pathophysiologic mechanism of allergy is dependent on the action of many redox-sensitive proinflammatory mediators. However, even though redox disturbances are believed to be a hallmark of inflammation, little is known of the effect of redox imbalance to the pathophysiology of allergic rhinitis. We thus opted to investigate the relation of oxidative stress and allergic rhinitis, through the utilization of a potent antioxidant substance (N-acetylcysteine [NAC]) in a rat model of allergic rhinitis and the evaluation of its action on specific markers of inflammation.

METHODS

NAC (50 mg/kg and 250 mg/kg) was intraperitoneally administered to ovalbumin (OVA)-sensitized rats prior to intranasal challenge with OVA. Mucosal congregation of inflammatory cells (eosinophils and mast cells), mucosal expression of redox-sensitive enzymes (inducible nitric oxide synthase [iNOS] and cyclooxygenase 2 [COX-2]), and the blood levels of a key proinflammatory mediator (tumor necrosis factor-α [TNF-α]) were evaluated.

RESULTS

Intranasal OVA challenges lead to mucosal inflammation, induction of the mucosal expression of iNOS and COX-2 and elevation of TNF-α blood levels. NAC significantly inhibited accumulation of inflammatory cells and downregulated iNOS expression and TNF-α serum levels. The role of COX-2 appeared to be 2-fold and its expression was divergently modulated by NAC.

CONCLUSION

Our findings suggest that redox balance is involved in the pathophysiology of allergic rhinitis in rats and that NAC can potentially suppress the allergen-induced nasal inflammatory cascade. The investigation of the role of oxidative stress in atopy could help in the evaluation of the therapeutic potential of antioxidant substances in allergic diseases.

Nasal and exhaled nitric oxide in allergic rhinitis

Objectives

The primary aim of this study was to assess whether one can use levels of nasal nitric oxide (nNO) and exhaled nitric oxide (eNO) as a means of evaluation in allergic rhinitis.

Methods

We used a chemiluminescence analyzer to measure nNO and eNO in normal controls (n=34) and allergic rhinitis patients (n=35), and compared these measurements with various parameters of clinical symptoms and laboratory data.

Results

Mean nNO (389±119 ppb) in allergic rhinitis patients was significantly higher than normal controls (276±88 ppb). Without asthma, mean eNO (64.8±55.9 ppb) in allergic rhinitis patients was significantly higher than normal controls (33.0±24.0 ppb). In the persistent allergic rhinitis group, eNO concentration was significantly higher, while nNO concentration was significantly lower than the intermittent group.

Conclusion

We can use nNO and eNO levels for evaluation of allergic rhinitis. However, we should consider the fact that nNO levels can be reduced, when symptoms are severe and long-lasting. Additionally, in allergic rhinitis, eNO can be elevated without asthma.

Inducible nitric oxide synthase plays important roles in allergic reactions of pollinosis in mice sensitized with pollen allergy

To elucidate the possible involvement of nitric oxide (NO) derived from inducible NO-synthase (iNOS) in the pathogenesis of patients with allergic rhinitis, we analyzed changes in the frequency of sneezing, plasma levels of NO metabolites, α-melanocyte-stimulating hormone (MSH) and immunoglobulin E and tracheal expression of IgA and mast cell tryptase in control and iNOS^−/− mice. Eight-week-old control and iNOS^−/− male C57BL/6j mice were sensitized with Cry j I antigen. After the last intranasal challenge of antigen, changes in the frequency of sneezing and plasma levels of IgE, α-MSH and NO metabolites and tracheal expression of iNOS, IgA and mast cell tryptase were analyzed by ELISA and immunohistochemistry using specific antibodies. The sensitization of mice with Cry j I antigen increased plasma levels of NO metabolites, α-MSH and IgE and tracheal expression of iNOS, IgA and mast cell tryptase in control not but in iNOS^−/− mice. Administration of N^G-nitro-L-arginine methyl ester strongly inhibited all these changes occurred in control mice. These results indicate that the symptom of pollinosis including sneezing is enhanced by iNOS derived NO through activation of α-MSH-receptor containing mast cells enriched with tryptase.

Expression of nitric oxide synthases in leukocytes in nasal polyps

BACKGROUND

Nitric oxide (NO) has various roles in airway physiology and pathophysiology. Monitoring exhaled NO levels is increasingly common to measure airways inflammation and inhaled NO studied for its therapeutic value in premature infants and adult respiratory distress syndrome. NO is produced by 3 isoforms of NO synthase (NOS1, 2, 3), and each can play distinct and perhaps overlapping roles in the airways. However, the distribution, regulation, and functions of NOS in various cells in the upper airways, particularly in leukocytes, are incompletely understood.

OBJECTIVE

To characterize the expression of NOS isoforms in leukocytes in normal middle turbinate tissues (MT) and in inflammatory nasal tissue (nasal polyps, NP).

METHODS

Normal MT tissue was collected from surgical specimens that were to be discarded. The NP samples were from surgical tissue archives of 15 patients with chronic rhinosinusitis. Isoforms of NOS in cells were identified by double immunostaining using NOS isoform-specific and leukocyte-specific (mast cell, eosinophil, macrophage, neutrophil, or T cell) antibodies.

RESULTS

The proportion of total cells below the epithelium that were positive for each isoform of NOS was higher in NP than in MT. Each isoform of NOS was found in all leukocyte populations studied, and there were significant differences in the percentage of leukocytes expressing NOS isoforms between MT and NP.

CONCLUSION

All isoforms of NOS are expressed in leukocytes in MT and NP, and their expression varies among leukocyte types. Our data provide a basis to investigate the regulation, cell distribution, and distinct functions of NOS isoforms in normal and inflamed nasal tissues.

Analysis of nicotine-induced DNA damage in cells of the human respiratory tract

Epithelium of the upper and lower airways is a common origin of tobacco-related cancer. The main tobacco alkaloid nicotine may be associated with tumor progression. The potential of nicotine in inducing DNA mutations as a step towards cancer initiation is still controversially discussed. Different subtypes of nicotinic acetylcholine receptors (nAChR) are expressed in human nasal mucosa and a human bronchial cell line representing respiratory mucosa as a possible target for receptor-mediated pathways. In the present study, both cell systems were investigated with respect to DNA damage induced by nicotine and its mechanisms. Specimens of human nasal mucosa were harvested during surgery of the nasal air passage. After enzymatic digestion over night, single cells were exposed to an increasing nicotine concentration between 0.001 mM and 4.0mM. In a second step co-incubation was performed using the antioxidant N-acetylcysteine (NAC) and the nAChR antagonist mecamylamine. DNA damage was assessed using the alkali version of the comet assay. Dose finding experiments for mecamylamine to evaluate the maximal inhibitory effect were performed in the human bronchial cell line BEAS-2B with an increasing mecamylamine concentration and a constant nicotine concentration. The influence of nicotine in the apoptotic pathway was evaluated in BEAS-2B cells with the TUNEL assay combined with flow cytometry. After 1h of nicotine exposure with 0.001, 0.01, 0.1, 1.0 and 4.0mM, significant DNA damage was determined at 1.0mM. Further co-incubation experiments with mecamylamine and NAC were performed using 1.0mM of nicotine. The strongest inhibitory effect was measured at 1.0mM mecamylamine and this concentration was used for co-incubation. Both, the antioxidant NAC at a concentration of 1.0mM, based on the literature, as well as the receptor antagonist were capable of complete inhibition of the nicotine-induced DNA migration in the comet assay. A nicotine-induced increase or decrease in apoptosis as assessed by the TUNEL assay in BEAS-2B could not be detected. These results support the hypothesis that oxidative stress is responsible for nicotine-induced DNA damage. Similar results exist for other antioxidants in different cell systems. The decrease in DNA damage after co-incubation with a nAChR antagonist indicates a receptor-dependent pathway of induction for oxidative stress. Further investigations concerning pathways of receptor-mediated DNA damage via nAChR, the role of reactive oxygen species and apoptosis in this cell system will elucidate underlying mechanisms.

Diagnostic tools in Rhinology EAACI position paper

This EAACI Task Force document aims at providing the readers with a comprehensive and complete overview of the currently available tools for diagnosis of nasal and sino-nasal disease. We have tried to logically order the different important issues related to history taking, clinical examination and additional investigative tools for evaluation of the severity of sinonasal disease into a consensus document. A panel of European experts in the field of Rhinology has contributed to this consensus document on Diagnostic Tools in Rhinology.

Bordetella avium causes induction of apoptosis and nitric oxide synthase in turkey tracheal explant cultures

Bordetellosis is an upper respiratory disease of turkeys caused by Bordetella avium in which the bacteria attach specifically to ciliated respiratory epithelial cells. Little is known about the mechanisms of pathogenesis of this disease, which has a negative impact in the commercial turkey industry. In this study, we produced a novel explant organ culture system that was able to successfully reproduce pathogenesis of B. avium in vitro, using tracheal tissue derived from 26 day-old turkey embryos. Treatment of the explants with whole cells of B. avium virulent strain 197N and culture supernatant, but not lipopolysaccharide (LPS) or tracheal cytotoxin (TCT), specifically induced apoptosis in ciliated cells, as shown by annexin V and TUNEL staining. LPS and TCT are known virulence factors of Bordetella pertussis, the causative agent of whooping cough. Treatment with whole cells of B. avium and LPS specifically induced NO response in ciliated cells, shown by uNOS staining and diaphorase activity. The explant system is being used as a model to elucidate specific molecules responsible for the symptoms of bordetellosis.

Augmented venous responsiveness to leukotriene D(4) in nasal septal mucosae of repeatedly antigen-challenged rats

One possible mechanism of the nasal obstruction observed in allergic rhinitis is thought to be a dilatation of veins in nasal mucosa, although the exact mechanism(s) is not fully understood. An involvement of cysteinyl leukotrienes (CysLTs) in the nasal obstruction has also been suggested. In addition to the specific antigen-induced nasal symptoms, nasal hyperresponsiveness to non-specific stimuli is one of the characteristic features of patients with allergic rhinitis. Augmentation of LTD(4)-induced venodilatation (a part of nasal hyperresponsiveness) of nasal mucosae in antigen-challenged rats was investigated. The LTD(4)-induced venodilatation was significantly increased in antigen-challenged rats, although venodilatation by application of LTD(4) was not induced in nasal mucosae of control rats. The LTD(4)-induced venodilatation was significantly inhibited by pretreatment with L-NMMA [an inhibitor of nitrix oxide synthase (NOS)]. Although mRNA of CysLT1 receptor of nasal mucosa was within control level, the LTD(4)-induced production of NOx in nasal cavity was augmented in repeatedly antigen challenge rats. In addition, the level of iNOS mRNA was also significantly augmented in nasal mucosae of repeatedly antigen-challenged rats. Interestingly, sodium nitroprusside (SNP; an NO donor)-induced venodilatation itself was significantly augmented in nasal mucosae of repeatedly antigen challenge rats. In conclusion, we here suggest that the sensitivity of venodilatation to LTD(4) was augmented in nasal mucosae of challenged rats. Therein, not only increased NO production but also enhanced NO responsiveness might be involved in the development of nasal hyperresponsiveness in allergic rhinitis.

The association of oxidative stress and nasal polyposis

Many diseases are linked to damage from reactive oxygen species that occurs from an imbalance between reactive oxygen species and antioxidants, a condition called oxidative stress. Nasal polyposis is considered to be an inflammatory condition in nasal and paranasal sinus cavities and its aetiology is still unclear. There are very few data on epithelial changes in nasal polyposis and their relationship with free radical damage. Malondialdehyde as a major end-product of lipid peroxidation, and superoxide dismutase and nitric oxide as antioxidants play important roles in oxidative stress. In this study, the concentrations of malondialdehyde, superoxide dismutase and nitric oxide were compared in normal and nasal polyposis-affected tissue samples. Malondialdehyde levels were significantly higher, and superoxide dismutase and nitric oxide levels were significantly lower in patients with nasal polyposis compared with the control group. This study demonstrates that there is a strong relationship between oxidative stress and the pathogenesis of nasal polyposis.

Allergic and idiopathic rhinitis: an ultrastructural study

Nasal hyperreactivity is one of the most important underlying mechanisms in both allergic (AR) and idiopathic rhinitis (IR). In order to study the pathomorphological changes in this entity, tissue samples from patients with AR, IR, and from patients without chronic inflammation were taken during nasal surgery. Primary antibodies against Substance P (SP), calcitonin gene-related peptide (CGRP), and endothelial nitric oxide synthases (NOS III) were applied and the immunocomplexes were visualized by immunocytochemistry. The nasal mucosa of patients with AR and IR showed similarities on the ultrastructural level. Neurogenic inflammation was indicated by a strong innervation pattern with sensory nerve fibers containing SP and CGRP. We could show that extensive edema and cellular infiltration might be characteristic for AR. On other hand there was no evidence of eosinophilic or NO involvement in IR. Finally, on the ultrastructural level, AR and IR showed many similarities. Based on these findings anti-inflammatory therapy modalities could be recommended for both types of rhinitis.

[Ultrastructural changes in allergic rhinitis vs. idiopathic rhinitis]

BACKGROUND

Nasal hyperreactivity is one of the most important underlying mechanisms in allergic rhinitis (AR) as well as idiopathic rhinitis (IR). The aim of the present study was to examine pathomorphological changes in nasal mucosa in these subgroups of rhinitis.

PATIENTS AND METHODS

Tissue samples of human inferior turbinates from 20 patients with AR and 16 patients with IR were taken during nasal surgery and preserved in glutaraldehyde or paraformaldehyde. Ultrathin sections of specimens from 15 patients without chronic inflammation of nasal mucosa were used as controls. Primary antibodies against substance P (SP), calcitonin-gene-related peptide (CGRP), and endothelial nitric oxide synthase (NOS III) were applied, and the immunocomplexes were visualized by an immunocytochemical staining technique using gold-labeled antibodies. Immunostained structures were photodocumented using light and transmission electron microscopy.

RESULTS

The nasal mucosa of patients with AR and IR showed similarities on the ultrastructural level. A strong innervation pattern with sensory nerve fibers containing SP and CGRP demonstrated neurogenic inflammation. Extensive edema and cellular infiltrations were found in AR. A decreased presence of eosinophils and nitric oxide was observed in IR.

CONCLUSIONS

On the ultrastructural level, AR and IR showed many similarities but also some differences. Based on these findings, anti-inflammatory therapy could be recommended for both types of rhinitis.

Nasal mucosal expression of nitric oxide synthases in patients with allergic rhinitis and its relation to asthma

BACKGROUND

Nitric oxide (NO) has contradictory roles in the pathophysiology of allergic inflammation in both allergic rhinitis (AR) and asthma. Small amounts of NO produced by constitutive NO synthase (NOS) is anti-inflammatory, whereas large amounts produced by inducible NOS (iNOS) are proinflammatory.

OBJECTIVE

To investigate the difference in constitutive endothelial NOS (eNOS) and iNOS expression in nonallergic and allergic mucosa and the possible relation of this to the coexistence of asthma in seasonal AR.

METHODS

Seventeen patients (10 women and 7 men) with seasonal AR and 9 nonallergic patients (5 women and 4 men) with nasal septum deviation were enrolled. Inferior turbinate nasal biopsy specimens were obtained in all. Levels of eNOS and iNOS expressed as immunohistochemical scores (HSCOREs) were determined immunohistochemically from the specimens.

RESULTS

The mean +/- SD HSCOREs for eNOS in patients with seasonal AR were not significantly different from those of the nonallergic controls (1.85 +/- 0.78 vs 1.63 +/- 0.54; P = .12). On the other hand, the mean +/- SD HSCOREs for iNOS were significantly higher in patients with seasonal AR (1.75 +/- 0.75 vs 0.71 +/- 0.6; P = .004). Furthermore, although eNOS expression was not different between seasonal AR patients with and without asthma, the mean +/- SD HSCOREs for iNOS were significantly higher in the patients with asthma (1.93 +/- 0.78 vs 1.65 +/- 0.55; P = .01).

CONCLUSION

Increased expression of iNOS might have a role in the development of allergic inflammation in upper and lower airways and in comorbidity of AR and asthma.

Involvements of cysteinyl leukotrienes and nitric oxide in antigen-induced venodilatation of nasal mucosa in sensitized rats in vivo

To determine an in vivo venodilatation of nasal mucosa, which is thought to be one of the causes of nasal obstruction in allergic rhinitis, venous diameters of nasal septa were directly measured in anesthetized rats. An application of antigen to nasal mucosa of sensitized rats caused an increase in diameters of mucosal veins, that is, venodilatation: the maximal response (about 20% increase in diameters) was observed at 55 min after antigen challenge. The antigen-induced increase in venous diameter of nasal mucosa was significantly inhibited by pretreatment with a cysteinyl leukotrienes (CysLTs) receptor antagonist, SR2640, and a nitric oxide (NO) synthase inhibitor, N(G)-monomethyl-L-arginine, indicating that CysLTs and NO might be involved in the venodilatation of nasal mucosa induced by antigen challenge. Blocking the action of CysLTs and NO might be therefore useful for the therapy of nasal obstruction in allergic rhinitis.

Serum Nitrite/Nitrate and Arginase Levels in Patients with Allergic Rhinitis

Nitric oxide (NO) plays an important role in the regulation of upper respiratory function. Patients with untreated allergic rhinitis (AR) have an increased level of NO in the nasal cavity compared to normal individuals. We aimed to investigate serum levels of arginase and NO metabolites nitrite/nitrate in patients with AR during the symptomatic period. The patient and control groups consisted of 14 males and 12 females (mean age: 29, range: 20-40 years), and 10 males and 10 females (mean age: 27, range: 22-38 years), respectively. Nitrite/nitrate levels were 0.98 +/- 0.33 ng/ml in the patients with AR, and 0.78 +/- 0.26 ng/ml in the control group (p = 0.03). Arginase levels were 28.8 +/- 14.1 ng/ml in the patients with AR, and 20.8 +/- 13.5 ng/ml in the control group. The difference between the groups was statistically insignificant (p = 0.24). Our results support the view that NO plays an important role in the pathogenesis of AR, and NO metabolites may be used as a marker for monitoring the disease activity and therapy.

Increased expression of inducible nitric oxide synthase in nasal mucosae of guinea pigs with induced allergic rhinitis

BACKGROUND

Nitric oxide (NO) is produced by the action of NO synthase (NOS) isoforms and is considered an important mediator of inflammatory response including airways. In this study, the changes in the expression levels of NOS isoforms in nasal mucosae were determined in a guinea pig model of allergic rhinitis.

METHODS

An allergic rhinitis model was prepared in guinea pigs by repeated challenge with aerosolized dinitrophenylated ovalbumin antigen. Twenty-four hours after the last antigen challenge, the expression levels of NOS isoforms in nasal mucosae were determined by immunoblottings. Changes in the isometrical tension of isolated mucosal tissues of nasal septa induced by histamine were measured also.

RESULTS

Although the expression levels of endothelial NOS (eNOS) and neuronal NOS (nNOS) in nasal mucosae were not affected by the repeated antigen exposure, the inducible NOS (iNOS) level was markedly and significantly increased in the challenged animals. In isolated nasal mucosal tissues, histamine induced a concentration-dependent relaxation, which was sensitive to an H1-receptor antagonist, mepyramine, and an NOS inhibitor, L-NMMA. No significant change in the histamine responsiveness was observed between the sensitized control and repeatedly antigen-challenged groups.

CONCLUSION

The expression of three isoforms of NOS, including eNOS, nNOS, and iNOS, was presented in guinea pig nasal mucosa. A marked increase in iNOS expression in the repeatedly antigen-challenged animals suggests an important role of iNOS in the pathogenesis of allergic rhinitis. However, the pathophysiological role(s) of NO generated by iNOS in nasal allergy is still unclear.

Pathophysiology of nasal obstruction and meta-analysis of early and late effects of levocetirizine

Nasal obstruction, also referred to as congestion, blockage or stuffiness, is a crucial symptom in allergic rhinitis (AR) and may affect sleep as well as quality of life. Early- and late-phase-allergic reactions both contribute to nasal obstruction, although it primarily represents a major symptom in the chronic allergic reaction. A complex network of inflammatory and neurogenic phenomena relates to chronic nasal obstruction, including the subepithelial accumulation of inflammatory cells, particularly mast cells and eosinophils, and the release of neuropeptides. Nasal obstruction is a difficult-to-treat symptom. Vasoconstrictors (decongestants) and intranasal corticosteroids, due to their anti-inflammatory properties, have mainly been used for relieving the nasal passages from the congested mucosa. However, there is accumulating evidence recently that the latest-generation potent antihistamines have decongestant properties in AR. This paper aims to review the pathophysiologic background of nasal obstruction and the evidence for an antihistamine, levocetirizine, in relieving nasal congestion. A meta-analysis on the early and late effects of levocetirizine on nasal obstruction under artificial and natural allergen exposure conditions is presented, demonstrating convincingly that levocetirizine shows a consistent effect on nasal obstruction as early as over the first 2 h and sustained over 6 weeks.

Effect of a Chinese herbal formula, Shi-Bi-Lin, on an experimental model of allergic rhinitis

BACKGROUND

Jia Wei Cang Er Zi San, a traditional Chinese herbal formula, has been used to treat allergic rhinitis (AR) for several centuries. However, its effect on experimental animal models and its therapeutic mechanism remain unclear.

OBJECTIVE

To study the effect of Shu-Bi-Lin, a modified Jia Wei Cang Er Zi San, on an animal model of AR.

METHODS

Shu-Bi-Lin was administered to the guinea pig model of AR. Meanwhile, an antihistamine-treated group for the treatment control, an ovalbumin-sensitized and untreated group for the positive control, and a sham-sensitized, sham-challenged group for the sham control were studied in parallel. Symptomatic and some pathophysiologic variables were evaluated.

RESULTS

Sneezing and nasal scratching after challenges were significantly ameliorated in the Shu-Bi-Lin-treated group compared with the ovalbumin-sensitized and untreated group, but rhinorrhea volume was not reduced. Shu-Bi-Lin significantly suppressed the production of IgG1 in the passive cutaneous anaphylaxis test. The thromboxane B2 level in nasal lavage fluid was significantly deceased in the Shu-Bi-Lin-treated group; however, the reduction in histamine and peptide leukotriene levels did not reach statistical significance. In addition, eosinophil infiltration and endothelial nitric oxide synthase immunoreactivity in the nasal tissues were reduced in the Shu-Bi-Lin-treated group.

CONCLUSIONS

Shu-Bi-Lin could alleviate the nasal symptoms of AR, and its mechanism might be related to its inhibitory effect on type I anaphylaxis reactions and eosinophil infiltration in the nasal tissues, as well as the inhibition of some mediators related to AR.

Nasal nitric oxide and nasal allergy

Measurements of nasal nitric oxide (nNO) are attractive because they are completely noninvasive and can easily be performed. The measurements may be useful in the early diagnosis of patients with chronic airway disorders such as Kartager's syndrome and cystic fibrosis. The possible use of nNO measurements in the diagnosis and treatment of allergic rhinitis still needs to be further evaluated because of the variable and also contradicting findings of nNO concentrations in this disease. In this review we will discuss the origin, production and measurement of nNO as well as the effect of allergic rhinitis, nasal allergen challenge and medication on nNO. Subsequently, we examine published data on allergic rhinitis and nNO, and summarize the effect of treatment of rhinitis on nNO. Finally, we discuss the potential future role for nNO in the diagnosis and management of allergic rhinitis.

Reactive nitrogen species in the respiratory tract

Endogenous Nitric Oxide (NO) plays a key role in the physiological regulation of airway functions. In response to various stimuli activated inflammatory cells (e.g., eosinophils and neutrophils) generate oxidants ("oxidative stress") which in conjunction with exaggerated enzymatic release of NO and augmented NO metabolites produce the formation of strong oxidizing reactive nitrogen species, such as peroxynitrite, in various airway diseases including asthma, chronic obstructive pulmonary diseases (COPD), cystic fibrosis and acute respiratory distress syndrome (ARDS). Reactive nitrogen species provoke amplification of inflammatory processes in the airways and lung parenchyma causing DNA damage, inhibition of mitochondrial respiration, protein dysfunction and cell damage ("nitrosative stress"). These effects alter respiratory homeostasis (such as bronchomotor tone and pulmonary surfactant activity) and the long-term persistence of "nitrosative stress" may contribute to the progressive deterioration of pulmonary functions leading to respiratory failure. Recent studies showing that protein nitration can be dynamic and reversible ("denitration mechanisms") open new horizons in the treatment of chronic respiratory diseases affected by the deleterious actions of "nitrosative stress".

Effects of 1400W, a potent selective inducible NOS inhibitor, on histamine- and leukotriene D4-induced relaxation of isolated guinea pig nasal mucosa

To clarify the role of inducible nitric oxide synthase (iNOS) in the relaxation of nasal vasculature, the effects of a potent selective iNOS inhibitor, N-[(3-aminomethyl)benzyl]acetamidine (1400W), on histamine- and leukotriene D4 (LTD4)-induced relaxations of isolated nasal septal mucosae were examined in naive guinea pigs. In addition to eNOS and nNOS, Western blots demonstrated a distinct expression of iNOS in nasal mucosal tissues of naive guinea pigs. In isolated nasal septal mucosae precontracted with norepinephrine (3 x 10(-5)M), both histamine (10(-7)-10(-3)M) and LTD4 (10(-10)-10(-7)M) exhibited relaxations, which were inhibited by a NOS inhibitor NG-monomethyl-L-arginine (L-NMMA; 10(-4)M). The inhibitory effect of L-NMMA was reversed by L-arginine (10(-3)M), indicating that the relaxations induced by histamine and LTD4 are mediated by NO. Furthermore, both the histamine- and LTD4-induced relaxations were also significantly attenuated by 1400W (10(-5)M). These findings suggest an involvement of NO generated by iNOS in agonist-induced relaxation of nasal mucosal vasculature in naive guinea pigs.

Silent and humming nasal NO measurements in adults aged 18-70 years

BACKGROUND

The concentration of nitric oxide (NO) measured from the nose is much higher than in the lower airways and increases during humming. We assessed nasal NO (nNO) normal values during breath hold and during humming in healthy adults.

MATERIALS AND METHODS

Nasal NO concentrations were measured in healthy adults (ages 18-70). They held their breath for 10 s and thereafter hummed as loud as possible with their mouths closed also for 10 s. During breath hold, air was passively extracted from one nostril with 700 mL min(-1). The average NO concentration at the plateau after 7-10 s was recorded and the mean of three consecutive measurements was calculated. During humming, air was extracted with 1200 mL min(-1), the peak NO values were recorded.

RESULTS

One hundred healthy adults participated (37 men). The nNO concentrations during breath hold were distributed normally (mean: 455 parts per billion (p.p.b.), SD 147). A random subgroup of 40 out of the 100 subjects (15 men) performed nNO measurement during humming. The median peak NO value was 1019 p.p.b. (SD 561) at the first, and 837 p.p.b. (SD 408) at the second measurement. There was a significant difference between the peak NO values of first and second humming.

CONCLUSION

We present normal values for nNO in adults, which can be used to assess the value of nNO in respiratory illnesses. The peak nNO values during humming are variable, and their clinical relevance remains to be shown.

Ultrastructural detection of nitric oxide in human nasal mucosa

OBJECTIVE

Nasal vasculature and seromucous glands are exposed to complex mechanisms influenced by external as well as internal stimuli. In addition to classic and peptidergic neurotransmitters, nitric oxide (NO) was increasingly found to be important in the control of various physiologic functions. NO modulates nasal immunology, influences macrophage activity, and has antiviral and bacteriostatic properties. The aim of this study was to show the localization of nitric oxide synthases (NOS) I and III in the normal human nasal mucosa by using immunoelectron microscopical techniques.

STUDY DESIGN

Specimens of noninflammed inferior turbinates from 35 patients who underwent nasal surgery were fixed in phosphate-buffered glutaraldehyde. After dehydration, incubation in unicryl and polymerization, ultrathin sections were cut. Primary antibodies against NOS I and III were applied and the immunocomplexes were visualized by an immunocytochemical staining-technique using gold-labeled antibodies. Immunostained structures were photodocumented using a transmission electron microscope.

RESULTS

NOS-immunoreactive nerve fibers were mainly co-located in parasympathetic nerves in the adventitia of arterial vessels and in periglandular axons. Electron microscopy showed that NOS-positive axons were in close contact with acinus cells. A strong NOS III-immunoreactivity was found in endothelial cells of capillaries near the glands as well as in arterial vessels. Furthermore, immunoreaction products were deposited throughout the cytoplasm of fibroblasts.

CONCLUSION

Nitric oxide in nerve fibers, seromucous glands, and endothelial cells of capillaries and arterial vessels suggest that NO takes part in the regulation of physiologic processes of the human nasal mucosa. NOS was co-localized in parasympathetic nerves and plays a role in the neurotransmission and neuromodulation of the vascular tone and glandular secretion. Arteries showed a distinctly developed nitrergic innervation and endothelial accumulation. The NO production in axons of the adventitia and in the endothelium of arteries demonstrated that these vessels are influenced by a dual NO system. NO could mainly act on these structures with vasodilatatory effects. Finally, NO would be able to influence the functions of perivascular fibroblasts.

Endothelial nitric oxide synthase/soluble guanylate cyclase system in human nasal polyps

The aim of our study was to analyze the level of expression of the endothelial nitric oxide synthase (eNOS)/soluble guanylate cyclase (sGC) system in nasal polyps and control nasal mucosae. The study was performed in polyps from 15 patients and nasal mucosae from 11 subjects operated on the nasal septum (control group). The expression of endothelial nitric oxide synthase (eNOS) and soluble guanylate cyclase (sGC) was determined in nasal mucosae. Western blot analysis demonstrated that eNOS protein was overexpressed in the nasal polyps with respect to control nasal mucosae. Immunohistochemistry also demonstrated that the vascular endothelium of nasal polyps contained higher amounts of eNOS protein than control nasal mucosae. Moreover, the beta(1) subunit of sGC was also overexpressed in the nasal polyps, which was associated with an increased content of cyclic GMP in the nasal polyps with respect to nasal control mucosae. In human nasal polyposis, there is an overexpression of the eNOS/sGC system. Further studies are needed to assess whether this overexpression is involved in the genesis of nasal polyposis.

Open supraglottic laryngectomy

Open supraglottic laryngectomy is an oncologically sound surgical procedure for selected cases of laryngeal cancer which maintains physiologic speech and swallowing without the need for a permanent tracheostoma. The oncologic principles, techniques for resection and reconstruction, postoperative management and complications are discussed.

Nitric oxide in health and disease of the respiratory system

During the past decade a plethora of studies have unravelled the multiple roles of nitric oxide (NO) in airway physiology and pathophysiology. In the respiratory tract, NO is produced by a wide variety of cell types and is generated via oxidation of l-arginine that is catalyzed by the enzyme NO synthase (NOS). NOS exists in three distinct isoforms: neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS). NO derived from the constitutive isoforms of NOS (nNOS and eNOS) and other NO-adduct molecules (nitrosothiols) have been shown to be modulators of bronchomotor tone. On the other hand, NO derived from iNOS seems to be a proinflammatory mediator with immunomodulatory effects. The concentration of this molecule in exhaled air is abnormal in activated states of different inflammatory airway diseases, and its monitoring is potentially a major advance in the management of, e.g., asthma. Finally, the production of NO under oxidative stress conditions secondarily generates strong oxidizing agents (reactive nitrogen species) that may modulate the development of chronic inflammatory airway diseases and/or amplify the inflammatory response. The fundamental mechanisms driving the altered NO bioactivity under pathological conditions still need to be fully clarified, because their regulation provides a novel target in the prevention and treatment of chronic inflammatory diseases of the airways.

Distribution of 3-nitrotyrosine in the nasal polyps of atopic patients

OBJECTIVE

To investigate whether formation of nitrotyrosine in the nasal polyps of atopic patients occurs.

STUDY DESIGN

A nonrandomized, retrospective, controlled qualitative and quantitative study.

METHODS

Nasal polyp tissue samples were acquired from 12 atopic patients. Control fragments of nasal mucosa were taken from 10 patients undergoing corrective surgery of the nasal septum. For routine histologic examinations, hematoxylin-eosin staining was used. Low-magnification microscopy was designed to yield pathologic characteristics and high magnification to quantify the number of eosinophils in the subepithelial connective tissue. Presence of nitrotyrosine was assessed by immunohistochemical method.

RESULTS

Hematoxylin-eosin staining revealed presence of numerous eosinophils in the epithelium and in the subepithelial connective tissue. All polyps were characterized by epithelial damage. Nitrotyrosine was present in the eosinophils, in the ciliated cell, and in cells of the damaged epithelium. Goblet cells, glands, and vessels were found to be negative. No significant differences concerning the localization of nitrotyrosine were recognized among the examined nasal polyps.

CONCLUSIONS

Nitrotyrosine immunohistochemical staining in nasal-polyp tissues suggested the existence of progressive epithelium injury caused by peroxynitrite. Consequences of peroxynitrite formation in eosinophils remain to be precisely established. The lack of nitrotyrosine in glands and blood vessels indicated that peroxynitrite does not have a significant role in the vascular and glandular dysfunction of nasal polyps.

Characterization of airway nitric oxide in allergic rhinitis: the effect of intranasal administration of L-NAME

BACKGROUND

Several studies have attempted to assess nasal nitric oxide (NO) levels in allergic rhinitis (AR). However, there seem to be differences in the results obtained. We therefore wanted to investigate this further by studying airway NO in AR and controls at several modalities, and also the effect of intranasal administration of the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine-methyl ester.HCl (L-NAME).

METHODS

Airway NO was determined through repeated measurements at three flow rates of air (0.5, 3, and 9 l/min), using a single-breath method and a method of nasal aspiration, in 18 patients with birch pollen AR during season and in 18 controls.

RESULTS

Patients with AR were characterized by no difference in nasal but higher orally exhaled NO and a larger interindividual spread in nasal and orally exhaled NO compared to controls. We also found a greater reduction in nasal NO after L-NAME in patients compared to controls.

DISCUSSION

These results indicate that several factors determine the levels of nasal NO in rhinitis. NO production in the nasal mucosa of patients with AR may be upregulated. On the other hand, this increase could be counteracted by swelling of the mucosa and secretions resulting in impaired NO diffusion from, for example, the paranasal sinuses, where particularly high levels of NO have been found. Also, the high background levels of NO from constitutive sources in the nose may blunt smaller increases in mucosal NO output.

CONCLUSION

It seems that the methods for measurement of nasal NO need to be improved and standardized before we can consider to use this test in monitoring inflammation in AR.

Heme oxygenase and nitric oxide synthase in human middle ear epithelium indicates local carbon monoxide and nitric oxide production

The gas mixture of the middle ear differs from that of the atmosphere, a fact that has been attributed to gas exchange across the middle ear mucosa. Several diseases of the middle ear seem to be related to impaired ventilation together with conjunctional changes in pressure and gas composition. Carbon monoxide (CO) and nitric oxide (NO) have recently been shown to be endogenously produced in the human lung as well as in the nasal airways. The production of CO and NO is enzymatically regulated by heme oxygenase (HO) and NO synthase (NOS), respectively. These enzymes display isoforms that are both constitutively expressed [HO-2, endothelial NOS (eNOS), neuronal NOS (nNOS)] and inducible [HO-1, inducible NOS (iNOS)] following different types of stimulation. The present study was designed to investigate the presence of HO-1, HO-2 and eNOS in the middle ear epithelium, using immunocytochemistry. Specimens from human middle ear mucosa obtained at autopsy and during surgery revealed HO-1-, HO-2- and eNOS-like immunoreactivity, indicating the possibility of local CO and NO production in the middle ear. If this assumption is true, it may affect our understanding of middle ear physiology and give new insights into the mechanisms behind middle ear pathology.

A decrease in maxillary sinus pressure, as seen in upper airway allergy or infection, results in an increase in upper airway nitric oxide levels

The paranasal sinuses are connected to the nasal cavity via small osties. Ostial occlusion, caused by mucosal swelling, will result in a slowly increasing negative pressure inside the sinus cavity. In parallel, the oxygen content in the sinus will decrease, resulting in the development of relative hypoxia. Hypoxia is a powerful inducer of nitric oxide (NO) synthase, and inducible NO synthase has been shown to be present in considerable amounts in the upper airways, including the sinuses. The present study was designed to investigate whether a reduction in sinus pressure would affect upper airway NO production. Thirteen healthy volunteers were investigated. A pressure chamber was used to lower the ambient pressure to -4.9 kPa. NO was sampled from one nostril or via a drainage tube inserted into the maxillary sinus before, during and after the hypobaric exposure. When the pressure was decreased, NO levels increased from 256 +/- 15 to 316 +/- 19 ppb (n = 13, p < 0.001). The NO levels remained elevated (282 +/- 21 ppb; p < 0.05) when measurements were repeated 20 min after leaving the chamber. The nasal airway resistance (V2tot) also increased as a result of the chamber session (from 16 +/- 2 degrees before to 21 +/- 3 degrees after; p < 0.05). An increase in NO levels was also found when the experiments were repeated with NO sampled directly from the maxillary sinus (225 +/- 6 before and 265 +/- 9 ppb after; n = 6, p < 0.001). For control purposes the nasal analyses were repeated again, this time under hyperbaric conditions (+ 4.9 kPa). This resulted in a slight decrease in the NO levels (from 273 +/- 22 to 241 +/- 17 ppb; n = 10, p < 0.001), but there was no change in the nasal airway resistance. We conclude that a reduction in sinus pressure, as seen in upper airway allergy or infection, may result in an increase in upper airway NO production.

Expression of nitric oxide synthases and in vitro migration of eosinophils from allergic rhinitis subjects

The expression of nitric oxide (NO) synthases and the role of the NO cyclic GMP pathway on the migration of eosinophils from untreated patients with allergic rhinitis were investigated. Inducible NO synthase was strongly expressed in eosinophils from healthy individuals, but not in eosinophils from allergic rhinitis patients. The neuronal isoform was observed in eosinophils from each group studied, whereas no staining for the endothelial isoform was detected in either group. The chemotaxis to N-formyl-methionyl-leucyl-phenylalanine (fMLP, 5 x 10(-7) M) and eotaxin (100 ng/ml) was significantly potentiated in allergic rhinitis eosinophils. In both groups, N(omega)-nitro-L-arginine methyl ester (L-NAME, 1.0 mM) or 1H(1,2,4)-oxadiazolo(4,3,-a)quinoxalin-1-one (ODQ, 0.2 mM) markedly reduced the chemotaxis. The selective iNOS inhibitor N-(3-(aminomethyl)benzyl)acetamidine (1400 W, 0.1-1.0 mM) significantly reduced the chemotaxis of eosinophils from healthy but not from allergic rhinitis subjects. The inhibition by L-NAME was restored by 3-morpholinosydnonimine (SIN-1) and S-nitroso-N-acetyl-penicillamine, whereas the inhibition by ODQ was restored by dibutyryl cyclic GMP. In conclusion, both endothelial and inducible NO synthase isoforms are absent in allergic rhinitis eosinophils, suggesting that the NO cyclic GMP pathway in this cell type is maintained through the activity of a neuronal isoform.

High levels of nitric oxide synthase activity are associated with nasal polyp tissue from aspirin-sensitive asthmatics

The pathogenesis of aspirin intolerance remains unclear. Inducible nitric oxide synthase (iNOS) expression is upregulated in nasal polyp epithelium, implying a role for nitric oxide (NO) in its formation. We decided to compare iNOS activity in polyp tissue from patients with and without aspirin intolerance. Nasal polyp tissue was collected from 15 patients undergoing routine nasal polypectomy. These patients were classified into three groups: Group A comprised patients with nasal polyps without asthma; Group B contained patients with nasal polyps and asthma; and Group C comprised patients with nasal polyps, asthma and aspirin sensitivity. All subjects in Group C had a history of aspirin-induced reaction and a confirmatory intranasal challenge with lysine-aspirin. NOS activity was measured by the ability of tissue homogenates to convert 3,4-L-arginine to L-citrulline in an L-N(G)-nitro-L-arginine-inhibitable fashion. The iNOS activity (picomoles) in polyp tissue from the 3 groups was: A, 248.72+/-220.79; B, 23.71+/-41.06; and C, 549.71+/-132.11. Thus, nasal polyps from patients with Samter's triad had a significantly higher iNOS activity (p = 0.004; one-way ANOVA). This finding does not correlate simply with disease severity or with the occurrence of asthma and could indicate another important facet of aspirin-induced airways disease.

Involvement of nitric oxide in pollen-induced biphasic nasal blockage in sensitised guinea pigs

We have developed a reproducible allergic rhinitis model showing biphasic nasal blockage on repetitive inhalation challenge with Japanese cedar pollen in sensitised guinea pigs. The role of nitric oxide (NO) in inducing nasal blockage was evaluated with this model. N(omega)-nitro-L-arginine methyl ester (L-NAME), a non-selective NO synthase (NOS) inhibitor, intravenously administered before the challenge, significantly inhibited both early and late nasal blockage by approximately 80% and 50%, respectively. When L-NAME treatment was performed after the challenge, the late response was inhibited by approximately 70%. This inhibition was completely reversed by co-administration of L-arginine. However, aminoguanidine and L-N(6)-(1-iminoethyl)lysine, selective inhibitors of inducible NOS, negligibly influenced the degree of nasal blockage. Meanwhile, the alpha-adrenergic agonist, naphazoline, strongly suppressed both early and late nasal blockage. These results indicate that NO, likely produced by constitutive rather than inducible NOS, plays a major role in the occurrence of biphasic nasal blockage, primarily by inducing vasodilatation.

Increased nitric oxide production in nasal epithelial cells from allergic patients--RT-PCR analysis and direct imaging by a fluorescence indicator: DAF-2 DA

BACKGROUND

Nitric oxide (NO) is believed to participate in the regulation of airway clearance and non-specific cellular immunity. Recent studies have suggested that airway epithelial cells of allergic and non-allergic individuals may differ in their ability to produce this molecule.

OBJECTIVE

The aim of this study was to detect the difference in NO production in human nasal epithelial cells between normal subjects and patients with perennial allergic rhinitis (AR), and to assess the relationship between the expression of nitric oxide synthase (NOS) isoforms and the severity of the disease.

METHODS

Nasal epithelial cells were obtained from the inferior turbinate. The expression of mRNAs encoding constitutive endothelial NOS (eNOS) and inducible NOS (iNOS) was studied by reverse transcription-polymerase chain reaction (RT-PCR). Direct NO production in living cells was visualized and quantified by a fluorescent indicator, DAF-2 DA.

RESULTS

RT-PCR analysis demonstrated that AR patients with a RAST score of 5 or 6 showed significant increases in the levels of iNOS mRNA and slight reductions in those of eNOS mRNA. Patients with a RAST score of 2-4 also revealed the same tendency however, the difference was not significant. DAF-2 DA imaging demonstrated that epithelial cells, especially the ciliated cells, produced a larger amount of NO than non-epithelial inflammatory cells. Preincubation with L-NAME resulted in an approximate 40% decrease in both groups.

CONCLUSION

These results directly indicate that nasal epithelial cells of AR patients overall produce higher levels of NO through the concomitant expression of different NOS isoforms. Continuous NO production by the epithelial cells in normal subjects further support the hypothesis that NO derived from epithelium may play dual roles in the regulation of nasal airway clearance and in the host defense. In addition, the use of DAF-2 DA provides a reliable method to visualize and quantify the direct NO production of living cells.

Nitric oxide-dependent neutrophil recruitment: role in nasal secretion

Leukotriene B4 (LTB4), an inflammatory mediator, is a potent chemoattractant for neutrophils that plays an important role in nasal secretion via release of elastase. Nitric oxide (NO) is an important modulator of leucocyte-endothelial cell interactions, endogenously produced in large quantities in the paranasal sinuses. To examine the role of NO in LTB4-stimulated nasal secretion. A newly-developed method for isolating and superfusing a nasal segment in dogs was used. Instillation of LTB4 into the nasal segment caused a time-dependent increase in the volume of airway fluid and in the recruitment of neutrophils. N(G)-nitro-L-arginine-methylester (L-NAME), an inhibitor of NO synthase, prevented LTB4-induced neutrophil recruitment and nasal secretion. These studies show that NO modulates LTB4-induced neutrophil recruitment and subsequent fluid secretion in the nose, and they suggest a therapeutic role for NO inhibitors in modulating neutrophil-dependent nasal secretion.

Exhaled nitric oxide production by nitric oxide synthase-deficient mice

Nitric oxide (NO) is produced in the nasal cavities, airways, and lungs and is exhaled by normal animals and humans. Although increased exhaled NO concentrations in airway inflammation have been associated with increased airway expression of nitric oxide synthase 2 (NOS 2), it is uncertain which NOS isoform is responsible for baseline levels of exhaled NO. We therefore studied wild-type mice and mice with a congenital deficiency of NOS 1, NOS 2, or NOS 3. By studying a closed chamber in which the exhaled gas of a group of mice was collected, gaseous NO production rates were measured. Wild-type mice exhaled 362 +/- 35 x 10(-15) mol g(-1) min(-1) NO (mean +/- SE, n = 16 groups of five mice), NOS 1-deficient mice exhaled 592 +/- 74 x 10(-15) mol g(-1) min(-1) NO (n = 15 groups, p < 0.05 versus wild-type and NOS 2-deficient mice), NOS 2-deficient mice 330 +/- 74 x 10(-15) mol g(-1) min(-1) NO (n = 14 groups) and NOS 3-deficient mice 766 +/- 101 x 10(-15) mol g(-1) min(-1) NO (n = 16 groups, p < 0.001 versus wild-type and NOS 2-deficient mice). Pharmacological NOS inhibition with L-NAME decreased (p < 0.05) the exhaled NO production rate of wild-type and NOS 3-deficient but not of NOS 2-deficient mice. L-Arginine administration increased exhaled NO production rate in all but NOS 2-deficient mice. Absence of NOS 1 or 3 is associated with increased murine exhaled NO production rates. Since NOS 2-deficient mice were the only genotype to lack substrate- and inhibitor-regulated changes of NO exhalation, we suggest that NOS 2 is an important isoform contributing to exhaled NO exhalation in healthy mice.