Role of inflammation in non-allergic rhinitis

Clinical Evidence of Type 2 Inflammation in Non-allergic Rhinitis with Eosinophilia Syndrome: a Systematic Review

PURPOSE OF REVIEW

Non-allergic rhinitis (NAR) includes different subtypes, among which NAR with eosinophilia syndrome (NARES) is the most important because of severity of symptoms and the high risk of comorbidities. Its pathophysiology is still object of debate, but a crucial role of chronic eosinophilic inflammation has been recognized. The aim of this review is to critically analyze the current evidence regarding the hypothesis that NARES may be considered a type 2 inflammatory disorder.

RECENT FINDINGS

The definition and diagnostic criteria for NARES are not universally shared and adopted, thus generating difficulties in reproducing the results. At present, there is extreme heterogeneity in sampling methods and disagreement in the cut-off of local eosinophilic count to determine a diagnosis of NARES. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) standard was applied to identify English-language experimental and clinical articles regarding NARES. The search was performed in April 2021. Twenty-six articles were included. Our data suggest a particular heterogeneity regarding sampling and specific cut-offs adopted for diagnosis of NARES and consensus should be reached. We suggest that eosinophil count should be reported as an absolute value for at least 10 observed rich fields in order to increase the level of standardization. Consensus among authors on this topic should be reached with particular attention to the cut-off for diagnosis. In the future, this limitation may be overcome by the identification of repeatable biomarkers to refine diagnosis and prognosis of NARES. Furthermore, our data strongly suggest that NARES have numerous similarities with clinical features of the most common type 2 diseases such as eosinophilic asthma and chronic rhinosinusitis with nasal polyps (CRSwNP): late onset, association with type 2 comorbidities, selective eosinophilic tissue infiltration, remarkable response to oral and intranasal corticosteroids, and progression in a type 2 CRSwNP.

Biologics for severe uncontrolled chronic rhinosinusitis with nasal polyps: a change management approach. Consensus of the Joint Committee of Italian Society of Otorhinolaryngology on biologics in rhinology

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a heterogeneous inflammatory condition of nasal mucosa and paranasal sinuses, predominantly mediated by type 2 inflammation and often associated with comorbid asthma and/or Exacerbated Respiratory Disease (N-ERD). The standard of care involves local and systemic corticosteroids and/or sinonasal surgery, although these options may be associated with recurrences and patients may require revision surgery. Difficult-to-treat patients, in fact, have a more severe disease requiring high systemic corticosteroid use and/or multiple sinonasal surgeries. Literature data suggests that biologic agents targeting specific key effectors of type 2 inflammation may offer supplemental therapy for patients with severe and uncontrolled CRSwNP, leading to significant improvement in several outcomes. For these reasons, over the years the endotyping of the disease has become increasingly important. Herein, we provide not only an update on the existing studies about the most promising biologics in CRSwNP, but also critical discussion on controversies about the use of biologics in severe uncontrolled CRSwNP. We finally provide consensus on strategic issues gathered among experts of the Joint Committee of Italian Society of Otorhinolaryngology on biologics in order to offer the best care for difficult to treat patients.

Rhinitis Phenotypes

Rhinitis is an umbrella term of a group of upper airway diseases with nasal symptoms and signs with different etiologies and various clinical features or traits. It can be classified into different "phenotypes," based on these observable traits. A proper differential diagnosis is necessary to adequately manage the disease. The objective of this review is to clarify the concept of rhinitis phenotypes while analyzing the clinical features and/or traits of each in order to determine a proper differential diagnosis and appropriate treatment.

Radiofrequency volumetric inferior turbinate reduction: long-term clinical results

The aim of our study was to assess long-term results of radiofrequency volumetric tissue reduction of inferior turbinates (RVTR). We performed a prospective long-term longitudinal evaluation of 305 patients affected by rhinitis (114 allergic and 191 non-allergic) who were unresponsive to medical treatment and underwent RVTR (January 2004 - December 2010). Subjects were followed for a mean period of 39.70 ± 19.41 months (range 24-60). Patients completed the NOSE-scale questionnaire pre- and post-operatively after 1 month and yearly for 5-years. Recurrence was assumed if the post-operative total NOSE score increased by at least 75% during follow-up and the patient restarted medical treatments. Estimation of relapse over time was performed by Kaplan-Meyer analyses. We documented overall good satisfaction of patients regarding the procedure, with a good rate of pain control and a low rate of complications. Post-operatively there was a significant improvement in nasal stuffiness, nasal obstruction and mouth breathing (p < 0.05). We observed a worsening trend for symptoms after 36 months with progressive increasing rate of recurrences that were significantly higher in allergic than non-allergic patients (p < 0.05). We also observed a slight worsening trend of global satisfaction of patients. Our study confirms the minor discomfort and low risk of side effects of RVTR. Our data showed good efficacy of the procedure in the majority of patients for at least 36 months after surgery, and in fact in this time period the cumulative probability to remain relapse-free was up to 0.8. In the following 2 years, we observed a worse temporal trend in term of recurrence rate, and in particular in allergic patients with a significant difference vs non-allergic individuals (p < 0.05).

Capsaicin for Rhinitis

Rhinitis is a multifactorial disease characterized by symptoms of sneezing, rhinorrhea, postnasal drip, and nasal congestion. Non-allergic rhinitis is characterized by rhinitis symptoms without systemic sensitization of infectious etiology. Based on endotypes, we can categorize non-allergic rhinitis into an inflammatory endotype with usually eosinophilic inflammation encompassing at least NARES and LAR and part of the drug induced rhinitis (e.g., aspirin intolerance) and a neurogenic endotype encompassing idiopathic rhinitis, gustatory rhinitis, and rhinitis of the elderly. Patients with idiopathic rhinitis have a higher baseline TRPV1 expression in the nasal mucosa than healthy controls. Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is the active component of chili peppers, plants of the genus Capsicum. Capsaicin is unique among naturally occurring irritant compounds because the initial neuronal excitation evoked by it is followed by a long-lasting refractory period, during which the previously excited neurons are no longer responsive to a broad range of stimuli. Patients with idiopathic rhinitis benefit from intranasal treatment with capsaicin. Expression of TRPV1 is reduced in patients with idiopathic rhinitis after capsaicin treatment. Recently, in a Cochrane review, the effectiveness of capsaicin in the management of idiopathic rhinitis was evaluated and the authors concluded that given that many other options do not work well in non-allergic rhinitis, capsaicin is a reasonable option to try under physician supervision. Capsaicin has not been shown to be effective in allergic rhinitis nor in other forms of non-allergic rhinitis like the inflammatory endotypes or other neurogenic endotypes like rhinitis of the elderly or smoking induced rhinitis.

Granulocyte-Macrophage Colony-Stimulating Factor Production and Tissue Eosinophilia in Chronic Rhinitis

Introduction Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a strong proinflammatory cytokine that takes part in allergic nasal inflammation as an eosinophil colony-stimulating factor. However, the role of GM-CSF in non-allergic rhinitis has not been fully explored.

Objectives The aim of this investigation was to assess the concentration of GM-CSF in nasal secretions of patients with non-allergic rhinitis with eosinophilia syndrome (NARES) in comparison to patients with perennial allergic rhinitis (PAR) and healthy subjects, as well as to assess the relationship with the degree of eosinophilic inflammation and clinical characteristics of the patients.

Methods Fourteen patients with diagnosis of NARES, 14 PAR patients, and 14 healthy subjects were included in this cross-sectional study. All patients underwent symptom score assessment, nasal endoscopy, allergy testing, and cytological evaluation. The concentration of GM-CSF in nasal secretions of all participants was measured by enzyme-linked immunosorbent assay (ELISA).

Results We found significantly higher levels of GM-CSF in patients with NARES than in the control group (p = 0.035). The percent of eosinophils in nasal mucosa was higher in NARES patients in comparison to patients with PAR (p < 0.001) and control patients (p < 0.0001). We found positive correlations between GM-CSF levels and eosinophil counts only in NARES patients.

Conclusion The concentrations of GM-CSF in nasal secretions correlate well with eosinophil counts in the nasal mucosa of NARES patients. These facts indicate a possible role of GM-CSF as a favorable marker for assessment of nasal disease severity and the degree of chronic eosinophilic inflammation in the nasal mucosa.

Neural Abnormalities in Nonallergic Rhinitis

Sensory nerve endings within the airway epithelial cells and the solitary chemoreceptor cells, synapsing with sensory nerves, respond to airborne irritants. Transient receptor potential (TRP) channels (A1 and V1 subtypes, specifically) on these nerve endings initiate local antidromic reflexes resulting in the release of neuropeptides such as substance P and calcitonin G-related peptides. These neuropeptides dilate epithelial submucosal blood vessels and may therefore increase transudation across these vessels resulting in submucosal edema, congestion, and rhinitis. Altered expression or activity of these TRP channels can therefore influence responsiveness to irritants. Besides these pathogenic mechanisms, additional mechanisms such as dysautonomia resulting in diminished sympathetic activity and comparative parasympathetic overactivity have also been suggested as a probable mechanism. Therapeutic effectiveness for this condition has been demonstrated through desensitization of TRPV1 channels with typical agonists such as capsaicin. Other agents effective in treating nonallergic rhinitis (NAR) such as azelastine have been demonstrated to exhibit TRPV1 channel activity through the modulation of Ca(2+) signaling on sensory neurons and in nasal epithelial cells. Roles of antimuscarinic agents such as tiotropium in NAR have been suggested by associations of muscarinic cholinergic receptors with TRPV1. The associations between these channels have also been suggested as mechanisms of airway hyperreactivity in asthma. The concept of the united airway disease hypothesis suggests a significant association between rhinitis and asthma. This concept is supported by the development of late-onset asthma in about 10-40 % of NAR patients who also exhibit a greater severity in their asthma. The factors and mechanisms associating NAR with nonallergic asthma are currently unknown. Nonetheless, free immunoglobulin light chains and microRNA alteration as mediators of these inflammatory conditions may play key roles in this association.

Proallergic cytokines and group 2 innate lymphoid cells in allergic nasal diseases

Recent advances in our understanding of proallergic cytokines and group 2 innate lymphoid cells (ILC2s) indicate their critical roles in type 2 immunity-mediated disorders. Proallergic cytokines, interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin, are released from epithelial cells in inflamed tissues and drive type 2 inflammation by acting on innate and acquired immune systems. ILC2s are an innate immune population that responds to proallergic cytokines by producing type 2 cytokines. In line with allergic disorders in the lung, skin, and intestine, emerging evidence suggests the involvement of proallergic cytokines and ILC2s in allergic nasal diseases such as chronic rhinosinusitis with polyps (CRSwNP), allergic fungal rhinosinusitis, and allergic rhinitis (AR). In CRSwNP patients, both proallergic cytokine levels and ILC2s frequency are increased in the nasal mucosa. Increased proallergic cytokine levels correlate with poorer disease outcomes in CRSwNP. Levels of nasal proallergic cytokines are also elevated in AR patients. In addition, animal studies demonstrate that cytokines are essential for the development of AR. It is becoming clear that the proallergic cytokine/ILC2s axis participates in allergic diseases by multiple mechanisms dependent upon the inflammatory context. Thus, a thorough understanding of these cytokines and ILC2s including their tissue- and disease-specific roles is essential for targeting the pathways to achieve therapeutic applications.