Pathophysiological features of the nasal mucosa in patients with idiopathic rhinitis compared to allergic rhinitis

Prevalence, comorbidities, diagnosis, and treatment of nonallergic rhinitis: real-world comparison with allergic rhinitis

Rhinitis is among the most common respiratory diseases in children. Nonallergic rhinitis, which involves nasal symptoms without evidence of systemic allergic inflammation or infection, is a heterogeneous entity with diverse manifestations and intensities. Nonallergic rhinitis accounts for 16%-89% of the chronic rhinitis cases, affecting 1%-50% (median 10%) of the total pediatric population. The clinical course of nonallergic rhinitis is generally rather mild and less likely to be associated with allergic comorbidities than allergic rhinitis. Here, we aimed to estimate the rate of coexisting comorbidities of nonallergic rhinitis. Nonallergic rhinitis is more prevalent during the first 2 years of life; however, its underestimation for children with atopic tendencies is likely due to low positive rates of specific allergic tests during early childhood. Local allergic rhinitis is a recently noted phenotype with rates similar to those in adults (median, 44%; range, 4%-67%), among patients previously diagnosed with nonallergic rhinitis. Idiopathic rhinitis, a subtype of nonallergic rhinitis, has been poorly studied in children, and its rates are known to be lower than those in adults. The prevalence of nonallergic rhinitis with eosinophilia syndrome is even lower. A correlation between nonallergic rhinitis and pollution has been suggested owing to the recent increase in nonallergic rhinitis rates in highly developing regions such as some Asian countries, but many aspects remain unknown. Conventional treatments include antihistamines, intranasal corticosteroids, and recent treatments include combination of intranasal corticosteroids with azelastin or decongestants. Here we review the prevalence, diagnosis, comorbidities, and treatment recommendations for nonallergic rhinitis versus allergic rhinitis in children.

Nonallergic Rhinitis: Treatment

Chronic nonallergic rhinitis (NAR) is a syndrome rather than a specific disease. A lack of understanding of the pathogenesis of this condition has led to imprecise terminology with several alternate names for the condition, including vasomotor rhinitis, nonallergic rhinopathy, and idiopathic rhinitis. The therapy for NAR is best based on the underlying pathology, which typically exists in a form whereby an abnormality of the autonomic nervous system is dominant or a form in which inflammation seems to be the cause of symptoms. In general the most effective therapy is the combination of an intranasal antihistamine and an intranasal corticosteroid.

What are the primary clinical symptoms of rhinitis and what causes them?

The nose has a limited repertoire of responses regardless of the triggers. These responses primarily serve as a protective mechanism for the lower respiratory tract. Although the nasal reactions to pollens, particles, and pollution may have a beneficial effect for the lower airway, they create symptoms in some individuals that lead to significant morbidity. The symptoms of allergic rhinitis extend far beyond the nose, and the morbidity associated with rhinitis is significant. The nasal symptoms of rhinitis and their causes are the focus of this review.

Historical, pathophysiological, and therapeutic aspects of vidian neurectomy

Vidian neurectomy yields dramatic relief of nasal hypersecretion in patients with allergic rhinitis. Clinical studies conducted on vidian neurectomized nasal mucosa have shown that nasal hypersecretion observed after challenging the nasal mucosa with antigen is caused by reflexively induced activation of the parasympathetic center secondary to stimulation of the sensory nerve terminals in the nasal mucosa by histamine. On the contrary, nasal mucosal swelling is caused mostly by the direct effects of chemical mediators on the nasal vasculature, although vascular reflex mediated by the noncholinergic parasympathetic nerve may be partially involved in the onset of nasal mucosal swelling after antigen challenge. Considering the long-term side effects of inhibition of lacrimation and possible partial recurrence of hyperreactive nasal symptoms observed after vidian neurectomy, less invasive endoscopic posterior nasal neurectomy is considered the treatment of choice for patients with allergic rhinitis who require surgical intervention.

Leukotriene receptor antagonist in the treatment of childhood allergic rhinitis--a randomized placebo-controlled study

OBJECTIVE

This study was designed to assess the hypothesis that leukotriene receptor antagonists (LTRAs) would provide additional symptom relief in asthmatic children with persistent AR already taking regular antihistamine. The effects of 16-week treatment of LTRA in addition to fexofenadine (FEX) on persistent AR in asthmatic children were examined.

STUDY DESIGN

Consecutive children with stable asthma and persistent AR were invited in this randomized, double-blind, placebo-controlled study. After a 2-week run-in period in which subjects were given FEX alone, they were randomly assigned to take LTRA or placebo in addition to FEX for 16 weeks, followed by 8 weeks of follow-up phase with FEX taken alone. Symptom scoring, rhinoscopy, acoustic rhinometry, spirometry, nasal secretion extraction and blood taking for IL-4 and IL-13 analysis were performed after a 2-week run-in and at the end of treatment.

RESULTS

Forty-four subjects with a median (IQR) age of 12.2 (10.1-14.1) years were recruited. At week 4 of treatment, the between-group differences in the mean changes of daytime sneezing score (mean difference (95% CI) = -0.35 (-0.59, -0.12), P = 0.004), nighttime sneezing score (mean difference (95% CI) = -0.37 (-0.62, -0.11), P = 0.007) and daytime composite score (mean difference (95% CI) = -1.08 (-1.92, -0.25), P = 0.013) were significant. Acoustic rhinometry also demonstrated a nearly significant difference in nasal volume change between groups at 16 weeks of treatment (mean difference (95% CI) = 0.572 (0.090-1.054), P = 0.021). IL-4 and IL-13 were not detected in the majority of nasal secretion or serum samples.

CONCLUSIONS

Additional LTRA provided a more rapid relief on sneezing at the 4-week time point. This combination therapy also maintained a greater nasal volume and this might translate to lesser nasal congestion.

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.

Idiopathic rhinitis, the ongoing quest

The term rhinitis in daily practice is used for nasal dysfunction causing symptoms-like nasal itching, sneezing, rhinorrhea and or nasal blockage. Chronic rhinitis can roughly be classified into allergic, infectious or nonallergic/noninfectious. When allergy, mechanical obstruction and infections have been excluded as the cause of rhinitis, a number of poorly defined nasal conditions of partly unknown aetiology and pathophysiology remain. The differential diagnosis of nonallergic noninfectious rhinitis is extensive. Although the percentage of patients with nonallergic noninfectious rhinitis with a known cause has increased the last decades, still about 50% of the patients with nonallergic noninfectious rhinitis has to be classified as suffering from idiopathic rhinitis (IR), or rather e causa ignota. Specific immunological, clinical and sometimes radiological and functional tests are required to distinguish known causes. Research to the underlying pathophysiology of IR has moved from autonomic neural dysbalans to inflammatory disorders (local allergy), the nonadrenergic noncholinergic (NANC) sensory peptidergic neural system and central neural hyperaesthesia, still without solid ground or proof. This review summarizes the currently known causes for nonallergic noninfectious rhinitis and possible treatments. Also possible pathophysiological mechanisms of IR are discussed.

Nasal wall compliance in vasomotor rhinitis

Nasal compliance is a measure related to the blood volume in the nasal mucosa. The objective of this study was to better understand the vascular response in vasomotor rhinitis by measuring nasal cross-sectional area and nasal compliance before and after mucosal decongestion in 10 patients with vasomotor rhinitis compared with 10 healthy subjects. Nasal compliance was inferred by measuring nasal area by acoustic rhinometry at pressures ranging from atmospheric pressure to a negative pressure of -10 cmH2O. Mucosal decongestion was obtained with one puff per nostril of 0.05% oxymetazoline. At atmospheric pressure, nasal cross-sectional areas were similar in the vasomotor rhinitis group and the healthy subject group. Mucosal decongestion did not induce any decrease of nasal compliance in patients with vasomotor rhinitis in contrast with healthy subjects. Our results support the hypothesis, already proposed, of an autonomic dysfunction based on a paradoxical response of the nasal mucosa in vasomotor rhinitis. Moreover, the clearly different behavior between healthy subjects and vasomotor rhinitis subjects suggests that nasal compliance measurement may therefore represent a potential line of research to develop a diagnostic tool for vasomotor rhinitis, which remains a diagnosis of exclusion.

Immunohistochemical localization of 3-nitrotyrosine in the nasal respiratory mucosa of patients with vasomotor rhinitis

CONCLUSION

This study demonstrates that, in the nasal respiratory mucosa of patients with vasomotor rhinitis, oxidative stress following peroxynitrite formation is confined to the respiratory epithelium. This suggests that the role of peroxynitrite in vasomotor rhinitis differs from its role in other diseases of the respiratory tract. The results of this study also support the concept that different pathogenetic mechanisms are probably involved in vasomotor rhinitis.

OBJECTIVE

Previous studies indicated that nitric oxide (NO) is involved in the pathogenesis of vasomotor rhinitis, strong expression of NO synthase being detected in the smooth muscle cells of the cavernous sinuses and in the respiratory epithelium. However, most adverse effects of high levels of NO originate from the reaction of NO with superoxide anions to form peroxynitrite. Therefore, in this study we evaluated the involvement of peroxynitrite in the pathogenesis of vasomotor rhinitis.

MATERIAL AND METHODS

Sites of peroxynitrite formation were identified by immunolabelling for 3-nitrotyrosine (3NT), its footprint in tissues. Samples of nasal mucosa were obtained from vasomotor rhinitis patients and from control subjects who had undergone corrective surgery of the nasal septum. All samples were obtained by reduction of the inferior turbinate.

RESULTS

Examination of specimens from vasomotor rhinitis patients revealed that 3NT is absent in epithelium with a normal appearance, cells of the subepithelial connective tissue, the glands and the blood vessels, including the cavernous sinuses. In contrast, intense 3NT immunolabelling was found in the disrupted respiratory epithelium. 3NT was not present in any of the specimens from control subjects.

Vasomotor rhinitis update

PURPOSE OF REVIEW

This review was conducted to examine new data on vasomotor rhinitis, a common clinical problem.

RECENT FINDINGS

Recent publications highlight advances in the study of the pathophysiology of vasomotor rhinitis. Electron microscopic and ultracytochemical evaluation of the nasal mucosa in vasomotor rhinitis demonstrates an emerging role of neuropeptides and nitric oxide in the pathogenesis of vasomotor rhinitis. Ozone, cigarette smoke, and other environmental factors may trigger neurogenic mechanisms that lead to vasomotor rhinitis. Objective tests have documented the presence of hypoactive sympathetic autonomic dysfunction. Such assessments also suggest autonomic dysfunction as a possible link between vasomotor rhinitis and gastroesophageal reflux disease. Recent publications propose nasal secretory protein analysis as a possible diagnostic tool. Evidence-based review of treatment outcomes shows topical sprays of azelastine, budesonide, and ipratropium to be of benefit in vasomotor rhinitis.

SUMMARY

A better understanding of the role of nitric oxide and neuropeptides in the pathogenesis of vasomotor rhinitis has opened new avenues in research, diagnosis, and management. Clinical diagnosis may be aided by the analysis of nasal secretory proteins. Effective treatments include antihistamine, anticholinergics, and steroid nasal sprays.

Thoughts on the pathophysiology of nonallergic rhinitis

Nonallergic noninfectious rhinitis is a diagnosis by exclusion, meaning that a number of poorly defined nasal conditions that have in common allergy and infection as a cause of the rhinitis have been excluded. The etiology of some subgroups of nonallergic noninfectious rhinitis, like nonallergic rhinitis with eosinophilia (NARES) and drug-induced rhinitis, are quite well defined, but in the majority of the patients, the etiology and pathophysiology are unknown. These patients are classified as idiopathic rhinitis patients. A careful determination of the intensity of the symptoms combined with modern diagnostic tools enables us to discriminate idiopathic rhinitis patients from normal controls. This review discusses the possible pathophysicologic mechanisms of nonallergic noninfectious rhinitis, with emphasis on idiopathic rhinitis.

Inflammatory patterns of allergic and nonallergic rhinitis

Rhinitis is a chronic condition of the nasal mucosa that affects a large segment of the population. The symptoms of rhinitis occur in a variety of sinonasal conditions, which may be broadly classified as allergic (seasonal or perennial) or nonallergic (infectious or a number of noninfectious etiologies) based on the presence or absence of atopy. The cytokine profile and inflammatory patterns underlying these two conditions vary because of certain differences in their pathophysiology as discussed in this review.

Autonomic nervous system evaluation of patients with vasomotor rhinitis

OBJECTIVE

To demonstrate the utility of quantitative neurological laboratory testing of autonomic nervous system dysfunction and to apply this methodology to further study the relation of chronic vasomotor (nonallergic) rhinitis to the autonomic nervous system.

METHODS

It has been suspected that vasomotor rhinitis is due either to a hyperactive parasympathetic nervous system or an imbalance between it and the sympathetic nervous system. The exact relation has not been determined. Recently neurological laboratories have been developed in which a battery of tests can be performed to determine reactivity of the autonomic nervous system.

RESULTS

Autonomic nervous system testing was performed on 19 patients with symptoms fulfilling the diagnostic criteria for vasomotor rhinitis and the results were compared with 75 sex- and age-matched control subjects. Patients with vasomotor rhinitis had significant abnormalities of their sudomotor, cardiovagal, and adrenergic subscores. Their composite autonomic scale score was significantly impaired at 2.43, as compared with 0.11 for controls (P < .005).

CONCLUSION

Autonomic nervous system dysfunction is significant in patients with vasomotor rhinitis. Possible factors that trigger this dysfunction including nasal trauma and extraesophageal manifestations of gastroesophageal reflux are discussed.