Small airway inflammation in atypical asthma

Area of Science:

• Pulmonology
• Respiratory Medicine
• Clinical Investigation

Background:

• Atypical asthma, including cough variant asthma (CVA) and chest tightness variant asthma (CTVA), receives less attention regarding its pathophysiology.
• Airway obstruction, particularly in small airways, is a key factor in asthma development.
• This study investigates the link between small airway inflammation (SAI) and small airway dysfunction (SAD) in atypical asthma.

Purpose of the Study:

• To determine if small airway inflammation (SAI) leads to small airway dysfunction (SAD) in patients with atypical asthma (CVA and CTVA).
• To compare airway inflammation levels in classic asthma, CVA, CTVA, and control groups.
• To identify risk factors associated with airway inflammation and dysfunction in different asthma types.

Main Methods:

• Fractional exhaled nitric oxide (FeNO) measurements (FeNO50, FeNO200, CaNOdual) were used to assess partitioned airway inflammation.
• Correlations between FeNO levels and SAD variables were analyzed.
• Binary logistic regression models were employed to assess risks in classic asthma, CVA, and CTVA, with cell classification evaluated by Spearman's rank tests.

Main Results:

• Whole airway inflammation was elevated in classic and atypical asthma compared to controls.
• Central and peripheral airway inflammation were higher in CVA and CTVA groups than in the classic asthma group.
• FeNO200 was a significant risk factor for classic asthma and CVA. Blood eosinophil levels correlated with FeNO50 and FeNO200 in both classic and atypical asthma.

Conclusions:

• CVA and CTVA exhibit more severe central and peripheral airway inflammation, potentially indicating a pre-asthmatic state.
• Small airway inflammation (SAI) is identified as the predominant risk factor preceding small airway dysfunction (SAD) in asthma development.
• Findings suggest a crucial role for managing SAI in preventing SAD, especially in atypical asthma presentations.