Diamine Oxidase Activity Deficit and Idiopathic Rhinitis: A New Subgroup of Non-Allergic Rhinitis?

Area of Science:

• Immunology
• Otorhinolaryngology
• Pharmacology

Background:

• Idiopathic rhinitis is a common condition characterized by nasal inflammation.
• The TRPV1 receptor and histamine are implicated in rhinitis pathophysiology.
• Diamine oxidase (DAO) is the primary enzyme responsible for histamine breakdown.

Purpose of the Study:

• To investigate DAO enzyme activity deficits in idiopathic rhinitis patients.
• To determine the correlation between DAO activity and rhinitis symptom severity.
• To explore the role of DAO deficiency in idiopathic rhinitis and TRPV1 activation.

Main Methods:

• A cross-sectional study involving 116 idiopathic rhinitis patients.
• Measurement of DAO enzyme activity.
• Assessment of nasal peak inspiratory flow (NPIF) and rhinitis severity.

Main Results:

• A DAO activity deficit was observed in 41.38% of patients.
• DAO activity levels correlated significantly with rhinitis severity (p = 0.006).
• Patients with DAO deficiency exhibited significantly higher NPIF (p < 0.001), indicating less nasal obstruction.

Conclusions:

• A significant prevalence of DAO deficiency exists in idiopathic rhinitis.
• DAO deficiency is associated with milder rhinitis symptoms and reduced nasal obstruction.
• TRPV1 receptor desensitization due to histamine may explain the milder disease course in DAO-deficient patients, presenting a potential therapeutic target.