The nose and nitric oxide: a review

Diagnostic Value and Clinical Application of Nasal Fractional Exhaled Nitric Oxide in Subjects with Allergic Rhinitis

Purpose

Nitric oxide (NO) is a potential marker in the diagnosis and monitoring of treatment for the management of patients with allergic rhinitis (AR). The study aimed to determine the value of nasal fractional exhaled nitric oxide (FeNO) in the diagnosis and treatment response of AR patients.

Methods

The participants were divided into control and allergic rhinitis groups based on the clinical symptoms and skin prick tests. The AR group was treated with intranasal corticosteroid after the diagnosis. The nasal fractional exhaled nitric oxide (FENO) levels were compared between control and AR groups. In the AR group, the visual analogue scale (VAS), Nasal Obstruction Symptoms Evaluation (NOSE) questionnaire, and nasal fractional exhaled nitric oxide (FeNO) were assessed pre- and post-treatment.

Results

One hundred ten adults were enrolled. The nasal FeNO level was significantly higher in AR compared to control ( p < 0.001). Both the subjective (VAS and NOSE), both ( p  < 0.01) and objective (nasal FeNO, p < 0.001) assessments showed significant different pre- and post-treatment. The threshold level of nasal FeNO in the diagnosis of AR was 390.0 ppb (sensitivity of 73% and specificity of 80%) based on the receiver operator characteristic curve.

Conclusion

Nasal FeNO level is significantly higher in AR compared to control group with significant difference pre- and post-treatment. The findings suggest nasal FeNO can serve as an adjunct diagnostic tool together with the monitoring of treatment response in AR.

Overexpression of Inducible Nitric Oxide Synthase in Allergic and Nonallergic Nasal Polyp

Sinonasal polyps are very common benign lesions of the nasal mucosa. Most of nasal polyps (NP) are idiopathic, and the pathophysiology of this disease is still incompletely understood. Nitric oxide (NO) is a reactive molecule generated by nitric oxide synthase (NOS). NO has been identified as an important mediator in airway function and pathogenesis of several respiratory system diseases. Histological and genetical expression of iNOS was detected to evaluate the role of NO in the pathogenesis of allergic (ANP) and nonallergic nasal polyps (NANP). Forty patients with nasal polyps (20 allergic and 20 nonallergic) were identified by history, clinical examination, and investigation. NPs were obtained from the middle turbinate (MT) during concha bullosa surgery. Twenty normal MT nasal tissues were taken as the control from patients undergoing concha bullosa surgery, without any evidence of allergy or inflammation. A nasal polyp specimen from each patient was subjected for immune-histochemical study followed by histological examination to detect the expression of iNOS. RT-PCR was used to evaluate the iNOS gene expression in isolated tissues. The expression of iNOS in both epithelial and stromal layers was greater in NP than in MT tissues. The ANP group showed more iNOS expression than those of the NANP group. The relative mRNA levels of iNOS gene were significantly higher in ANP (2.5-fold) compared to the normal (1.02-fold, P < 0.001) and NANP (1.5-fold, P < 0.01) groups. NP exhibited a significantly high expression of iNOS at both histological and genetical levels. NO might be an essential factor in the life history of NP. Further studies in a larger sample size are required to explain the probable mechanisms of NO in pathogenesis of NP.

Decreased Expression of TLR-9 and Cytokines in the Presence of Bacteria in Patients with Otitis Media with Effusion

Objectives

Toll-like receptor (TLR)-9 recognizes unmethylated cytidine-phosphate-guanosine (CpG) motifs in bacteria. Therefore, the expression of TLR-9 may differ according to the results of bacterial culture, and thus a change in proinflammatory cytokine induction can also be expected. The authors aimed to assess the differences and relationships between the expression of TLR-9, cytokines, and nitric oxide synthase (NOS) in otitis media with effusion (OME) based on bacterial culture results.

Methods

Sixty-eight patients with OME were divided into culture-positive and culture-negative groups based on middle ear culture results. mRNA expression of TLR-9, NOS, and cytokines was measured and analyzed.

Results

Bacteria were detected in 38.2% of patients, and the distribution was as follows: coagulase negative Staphylococcus (10.3%), Staphylococcus aureus (8.8%), Streptococcus pneumonia (5.9%), and Bacillus spp. and Haemophilus influenza combined (2.9%). There were no significant differences in epidemiologic characteristics according to the culture results. Down-regulation of TLR-9 was observed in the culture-positive group (P=0.019). Cytokines including interleukin (IL)-12 (r=-0.582), tumor necrosis factor (TNF)-α (r=-0.569), interferon (IFN)-γ (r=-0.442), IL-6 (r=-0.395) and inducible NOS (r=-0.256) tended to decrease with the detection of bacteria.

Conclusion

The expression of TLR-9 significantly decreased in OME with confirmed bacterial pathogens. IL-12, TNF-α, IFN-β, IL-6 expression tended to decrease with the detection of bacteria. The presence of bacterial pathogens in OME may be related to abnormalities in the innate immune system.

Increased expression of pattern recognition receptors and nitric oxide synthase in patients with endometriosis

OBJECTIVE

Endometriosis is characterized by repeated inflammatory changes and serious adhesions, inducing innate and adaptive immune responses within the abdominal cavity. To assess these immune responses, we evaluated the levels of expression of Toll-like receptors (TLR)-1, -2, -4, -5, and -9; nucleotide-binding oligomerization domains (NOD)-1 and -2; interleukins-1β, -6, -8, -10, and -12; interferon-γ; tumor necrosis factor-α; inducible nitric oxide synthase (iNOS) and endothelial NOS (eNOS); and immunoglobulins (Igs) in patients with endometriosis.

METHODS

The levels of TLRs, NODs, cytokines, and NOS mRNAs in peritoneal effusions were assessed by real time reverse transcription-polymerase chain reaction; and IgG, IgA and IgM concentrations were measured by enzyme-linked immunosorbent assays (ELISA) in 40 patients with and 40 without endometriosis. Findings from the two groups were compared.

RESULTS

We observed expression of all pattern recognition receptors (PRRs), cytokines, and NOS mRNAs and Igs in the effusion fluid of patients with and without endometriosis. The levels of TLR-2 and -9; NOD-1 and -2; iNOS and eNOS mRNAs and CA 125 were significantly higher in the endometriosis than in the non-endometriosis group (p<0.05 each). Moreover, PRR, cytokine, and NOS expression showed significant correlations (p<0.05).

CONCLUSIONS

PRRs, cytokines, and NOS, which act cooperatively in the innate immune response, are closely associated with endometriosis. Increased expression of TLR-2, TLR -9, NOD-1, NOD-2, and NOS mRNA in peritoneal fluid may be associated with endometriosis.

[Clinical anatomy of the paranasal sinuses. Descriptive anatomy, topography and important variations]

Detailed knowledge of the complicated anatomy and topography of the paranasal sinuses is an essential requirement for successful surgery in this region. The topographical relationship to essential neighbouring structures (vessels, nerves and spaces) must be borne in mind. Typical landmarks play a particularly important role, especially for reliable orientation in endoscopic procedures. Therefore, it must be stressed that detailed anatomical knowledge of the complicated nasal and paranasal architecture is very important for the success of nasal and paranasal surgery, as well as for the avoidance of serious complications. However, this knowledge can only be acquired by performing numerous dissections of the nasal and paranasal system once a good theoretical grasp of the various structures, regions and their nomenclature has been gained. Common anatomical variations, which may lead to complicated and hazardous changes in normal anatomy, are also of particular importance and the surgeon must be familiar with these variations.

Exhaled nitric oxide and other major exhaled compounds for the diagnosis of metabolic diseases

BACKGROUND

Many metabolic diseases including obesity, cardiovascular disease and diabetes share common pathogenetic pathways, which may involve chronic oxidative stress and inflammation. There is increasing evidence that assessment of biomarkers on exhaled gases or exhaled breath condensate may serve as a non-invasive tool to detect abnormalities in metabolic diseases mirroring increased in oxidative stress, systemic inflammation and endothelial dysfunction.

METHODS

Among commonly used exhaled biomarkers, nitric oxide (NO) on exhaled air and some constituents of exhaled breath condensate in volatile or non-volatile form may represent suitable markers. Nasal, bronchial and alveolar NO could be analyzed separately, with implications in the assessment of systemic disease and endothelial dysfunction. Moreover, the profiles of several exhaled gases have a place in phenotyping diabetic patients and their risk of complications. Accordingly, metabolomics of the airway fluid using exhaled breath condensate has recently confirmed the value of this biological matrix for the evaluation of both volatile and non-volatile biomarkers.

CONCLUSION

Normative studies for reference values are, however, lacking, and the influence of preanalytical variables on the methodology warrants further studies.

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.

Nitric oxide level in the nasal and sinus mucosa after exposure to electromagnetic field

OBJECTIVE

The purpose of this study was to examine the changes in nitric oxide (NO) level in the nasal and paranasal sinus mucosa after exposure radiofrequency electromagnetic fields (EMF).

STUDY DESIGN AND SETTING

Thirty male Sprague-Dawley rats were randomly grouped as follows: EMF group (group I; n, 10), EMF group in which melatonin received (group II; n, 10) and the control (sham operated) group (group III; n, 10). Groups I and II were exposed to a 900 MHz. Oral melatonin was given in group II. Control rats (group III) were also placed in the tube as the exposure groups, but without exposure to EMF. At the end of 2 weeks, the rats were sacrificed, and the nasal and paranasal sinus mucosa dissected. NO was measured in nasal and paranasal mucosa.

RESULTS

The nasal and paranasal sinus mucosa NO levels of group I were significantly higher than those of the control group (group III) ( P < 0.05). However, there was no statistically significant difference between group II and the control group (group III) regarding NO output ( P > 0.05).

CONCLUSION

Exposure to EMF released by mobile phones (900 MHz) increase NO levels in the sinus and nasal mucosa.

SIGNIFICANCE

Increased NO levels may act as a defense mechanism and presumably related to tissue damage. In addition, melatonin may have beneficial effect to prevent these changes in the mucosa.

Localisation of heme oxygenase isoforms in allergic human nasal mucosa

Carbon monoxide (CO) is an endogenously produced gas mediator produced by heme oxygenase (HO). Like nitric oxide (NO), CO is produced in the nasal mucosa. Given that induced NO synthase (iNOS) expression in nasal mucosa has been found to be up-regulated in allergic rhinitis, the current study investigated the expression of HO isoforms in allergic human nasal mucosa. Immunohistochemical staining for type 1 and 2 HO isoforms were carried out in nasal inferior turbinate mucosa from six patients with persistent allergic rhinitis, and compared with six control patients without nasal allergy. Focal and weak expression of HO-1 was observed in seromucous glands, with no difference between allergic and control specimens. Vascular endothelium, erythrocytes, smooth muscle and inflammatory cells (except macrophages) in the allergic group exhibited stronger HO-1 immunoreactivity compared to the control. Minimal expression was found in the respiratory epithelium in either group. Intravascular HO-1 expression was found in the allergic mucosa only. Intense HO-2 immunoreactivity was observed in the respiratory epithelium, vascular endothelium and seromucous glands in both allergic and control groups with no differences in intensity. In conclusion, unlike iNOS, HO-1 is minimally expressed in the nasal respiratory epithelium of either group. However, our findings suggest that it may be involved in the inflammatory process of allergic rhinitis at the submucosal level.

Expression of inducible nitric oxide synthase in antrochoanal polyps

OBJECTIVE

Antrochoanal polyp (ACP) is a polypoid lesion originating from the maxillary sinus, emerging from the ostium and extending to the choana. Although the etiologic causes of ACP are not known completely, it presents a fairly uniform clinical appearance. Nitric oxide (NO) has an important role in non-specific immunoreactions and inflammation in various tissues and has a main regulatory role in airway function and seems to involve in pathomechanism of several respiratory system diseases. NO is synthesized by the effect of three isoforms of nitric oxide synthase i.e. inducible NOS (iNOS). Some studies revealed that ACP has some different characteristics from the ordinary nasal polyps. In the present study, in order to compare ACP with allergic and non-allergic nasal polyps (NANP), we detected and localized the iNOS expression and also evaluate some histological parameters.

METHODS

Twenty-six cases were chosen from the files and four controls were used. The cases were separated as follows: normal inferior turbinate mucosa as control (n=4) ACPs (n=8), allergic nasal polyps (ANP) (n=9), and NANP (n=9). Five-micrometer thick sections were prepared from the paraffin sections of polyps and normal nasal mucosa to quantify the iNOS expression. iNOS protein was observed in the cytoplasm of epithelial and stromal inflammatory cells. iNOS protein expression in the groups was assessed according to the intensity of staining and histomorphological parameters, oedema, lymphocytic and eosinophilic cell infiltration were detected semi quantitatively.

RESULTS

iNOS expressions, either stromal or epithelial, were not different from each other among the four groups. Although it is not statistically significant, we noted that ANP and ACP frequently showed moderate and severe iNOS protein expression in epithelial and stromal parts when compared with NANPs and controls. Also, iNOS expression was significantly higher in the stroma of the ANPs than NANPs (P=0.012).

CONCLUSIONS

ACPs and ANPs have frequently showed moderate and significant epithelial and stromal iNOS expression. Further studies are needed in large groups to elucidate differences between ACP and the other nasal polyps.

Effect of nitric oxide donation on mucin production in vitro

Otitis media with effusion (OME) is characterized by the accumulation of a viscous fluid rich in mucins in the middle ear cleft. There is increasing evidence that this fluid is the result of an inflammatory reaction and that nitric oxide (NO) is an important mediator in this reaction. The goblet cell line HT29-MTX produces principally MUC5AC, an important mucin in middle ear effusions, and thus is a good model for the study of mucus-secreting epithelia. Confluent cell cultures were trypsinized, subcultured and incubated with isosorbide dinitrate (ISDN), a NO donor, for 0.5, 1 and 2 h at a concentration of 1 mm and in concentrations of 0.01, 0.1, 0.5, 1 and 2 mm for 1 h. Experiments were performed four times. Mucin production was detected by a slot blot ELISA assay, using a monoclonal mouse antibody to human MUC5AC mucin. Statistical significance was tested using a one-way analysis of variance. NO donation by ISDN caused a consistent rise in mucin production above control. Maximal mucin production of 35% above control occurred at 1 h with 1 mm ISDN. Mucin production increased from 12% above control with 0.1 mm ISDN dinitrate to 45% above baseline with 2 mm ISDN. NO donation by ISDN results in an increase in mucus production, which is both dose and time related. This adds further evidence to an inflammatory model for mucus secretion in OME.

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.