Searching for Inflammatory and Oxidative Stress Markers Capable of Clustering Severe Asthma

Asthma inflammation may feature an imbalance between oxidative stress and antioxidant defenses. Oxidative stress induces propagation of airways inflammation and corticosteroid insensitivity contributing to poor asthma control, and frequent severe acute exacerbations. This study assessed inflammation and oxidative stress in severe asthmatic subjects and evaluated the possible correlations between inflammatory and oxidative stress markers investigated and asthma severity.

Fifty-three patients with severe asthma, 11 patients with mild-moderate asthma and 12 healthy subjects were enrolled and underwent fractional exhaled nitric oxide (FENO) analysis and blood and sputum count cell collection. The content of mitochondrial DNA (MtDNA) and nuclear DNA (nDNA) was measured in exhaled breath condensate (EBC) by Real Time PCR and the ratio between MtDNA/nDNA was calculated. We detected MtDNA/nDNA in the EBC of severe asthmatics.

We found higher exhaled MtDNA/nDNA in severe asthmatics respectively compared to mild-moderate ones and to healthy controls (10.4±2.2 vs 7.9±2.5, p<0.05 and 10.4±2.2 vs 6.51±0.21, p<0.05). The level of exhaled MtDNA/nDNA was significantly higher in Non-T2 endotype severe asthmatics than T2 (14.07±10. 8 vs 6.5±5.5, p<0.05).

Oxidative stress marker (MtDNA/nDNA) is increased significantly with asthma severity and may be useful for endotyping severe asthma.