Sputum Cellularity and MRI Ventilation Defects in Severe Asthma.

Area of Science:

• Pulmonary Medicine
• Medical Imaging
• Immunology

Background:

• Airway inflammation, marked by eosinophils or neutrophils, is central to asthma.
• While eosinophils in sputum correlate with ventilation defects, the impact of other cellular types remains unclear.

Purpose of the Study:

• To investigate the relationship between distinct sputum cellular phenotypes and abnormal airway ventilation in severe asthma patients using 129Xe MRI.

Main Methods:

• Eighty-five severe asthma patients and 15 controls underwent 129Xe ventilation MRI.
• Sputum cytometry classified asthma patients into paucigranulocytic, eosinophilic, neutrophilic, and mixed-granulocytic phenotypes.
• Ventilation defect percent (VDP) was quantified and compared across phenotypes and with controls.

Main Results:

• Abnormal ventilation (elevated VDP) was observed in 44% of paucigranulocytic, 64% of eosinophilic, 75% of neutrophilic, and 89% of mixed-granulocytic asthma phenotypes.
• Asthma patients with eosinophilic, neutrophilic, and mixed phenotypes showed significantly higher VDP compared to controls (P < .0001).
• Paucigranulocytic asthma patients with abnormal ventilation were older and had higher fractional exhaled nitric oxide and CT mucus scores.

Conclusions:

• Intraluminal cellular inflammation in severe asthma is associated with abnormal airway ventilation, regardless of the specific cellular phenotype.
• Airway mucus and elevated fractional exhaled nitric oxide may contribute to ventilation abnormalities in paucigranulocytic asthma.