Study Identifies Potential Predictors of Poorly Controlled Asthma

Results of a prospective cohort study revealed patients with asthma—and particularly those with uncontrolled asthma—have a high degree of reactive oxygen species (ROS) formation which causes considerable oxidative stress, authors wrote.

In addition, increased levels of malondialdehyde (MDA) and superoxide dismutase (SOD) activity, as well as reduced glutathione peroxidase (GPx) activity, serve as predictors of poorly controlled asthma, according to the findings published in the Journal of Clinical Laboratory Analysis.

Asthma symptoms can include wheezing, shortness or breath, chest tightness, and coughing, and although medication exists to appropriately control the condition, when uncontrolled, asthma can lead to severe disruptions in daily life.

“The sustained activation of phagocytic cells and inflammatory mediators in the airways of asthmatic patients lead to high levels of oxidative stress in the lungs,” researchers explained. “This increased oxidative stress affects mucus hypersecretion and alters capillary endothelium, which may cause a leak of reactive oxygen species (ROS) into the systemic circulation.”

In an effort to better understand oxidant and antioxidant status in patients with asthma compared with healthy controls, and to investigate any correlation with the level of asthma control, 60 patients were recruited from a Tunisian hospital between January and March of 2018.

All participants were over the age of 18, had received an asthma diagnosis at least 6 months prior and were treated with an inhaled corticosteroid oral or inhaled beta 2-agonist. Forty-eight individuals were included in the study as age- and sex-matched controls.

“Asthma is defined as ‘controlled’ if the ACT [Asthma Control Test] score is ≥20, ‘partly controlled’ if the ACT score is between 16 and 19, and ‘uncontrolled’ if the ACT score is ≤15,” researchers wrote.

Analyses revealed:

• Asthmatic patients have significantly higher plasmatic levels of MDA and advanced oxidation protein products (AOPP) than healthy controls (P < .001)
• Lower glutathione (GSH) level and GPx activity were found in patients with asthma compared with controls (P < .001)
• Higher SOD activity was noted in asthmatic patients (P < .001)
• Comparing patients with controlled asthma and those with uncontrolled asthma showed increased MDA and AOPP levels and SOD activity (P < .001) as well as a decreased GSH level and GPx activity (P = .004, P = .019) in patients with uncontrolled asthma
• Spirometry level was significantly correlated with SOD activity (r = 0.447; P = 0.010), whereas no significant correlations were found with the other parameters (MDA, AOPP, GSH, and GPx)

Researchers hypothesized the contrasting outcomes seen for AOPP and SOD, and no significant variation in AOPP levels, could be due to differences in lifestyle variations, dietary factors, or additional confounding influences.

Based on the findings, “we inferred that conditions of uncontrolled asthma strongly evoke oxidative damages,” they wrote. “According to the multivariate logistic regression analysis results, we concluded that plasma MDA level is a potential and predictive biomarker of asthma control level in patients with asthma.”

Analyses between patient subgroups also showed asthma is never completely controlled, even when patients are on medication. Additional studies among larger cohorts are warranted to validate results, authors concluded.

Reference

Ammar M, Bahloul N, Amri O, et al. Oxidative stress in patients with asthma and its relation to uncontrolled asthma. J Clin Lab Anal. Published online March 22, 2022. doi:10.1002/jcla.24345