Different expression levels of interleukin-35 in asthma phenotypes

Area of Science:

• Immunology
• Respiratory Medicine
• Cytokine Biology

Background:

• Interleukin-35 (IL-35) is an inhibitory cytokine produced by regulatory lymphocytes.
• IL-35 plays a suppressive role in inflammatory diseases, but its function in asthma phenotypes is not well understood.
• This study investigates sputum IL-35 levels and their association with airway inflammation in different asthma subtypes.

Purpose of the Study:

• To quantify sputum IL-35 levels in asthma patients in clinical remission and healthy controls.
• To explore correlations between sputum IL-35 and clinical parameters like lung function, FeNO, age, sex, and smoking history.
• To determine the role of IL-35 in various asthma phenotypes.

Main Methods:

• Induced sputum samples were collected from 89 asthma patients and 19 healthy controls.
• Sputum inflammatory cell counts were assessed.
• Sputum IL-35 levels were measured using ELISA and Cytometric Bead Array.

Main Results:

• Sputum IL-35 levels were comparable between asthma patients and healthy controls.
• A significant reduction in sputum IL-35 was observed in eosinophilic asthma (EA) compared to neutrophilic asthma (NA), paucigranulocytic asthma (PA), and mixed granulocytic asthma (MA).
• Sputum IL-35 correlated positively with neutrophils and negatively with FeNO, FEV1% predicted, and FVC predicted, showing associations with Th1 and Th2 factors.

Conclusions:

• Sputum IL-35 levels differ across asthma phenotypes, particularly being lower in eosinophilic asthma.
• IL-35 appears to be involved in the distinct pathophysiological mechanisms of neutrophilic and eosinophilic asthma.
• These findings suggest differential roles and effects of IL-35 in managing various asthma subtypes.