Serum Reactive Oxygen Metabolite Levels Predict Severe Exacerbations of Asthma

Background and Purpose

Bronchial asthma (BA) is a chronic airway disease characterized by airway hyperresponsiveness and remodeling, which are intimately linked to chronic airway inflammation. Reactive oxygen species (ROS) such as hydrogen peroxide are generated by inflammatory cells that are involved in the pathogenesis of BA. However, the role of ROS in the management of BA patients is not yet clear. We attempted to determine the role of ROS as a biomarker in the clinical setting of BA.

Subjects and Methods

We enrolled patients with BA from 2013 through 2015 and studied the degrees of asthma control, anti-asthma treatment, pulmonary function test results, fractional exhaled nitric oxide (FeNO), serum reactive oxygen metabolite (ROM) levels, and serum levels of interleukin (IL)-6 and IL-8.

Results

We recruited 110 patients with BA. Serum ROM levels correlated with white blood cell (WBC) count (rs = 0.273, p = 0.004), neutrophil count (rs = 0.235, p = 0.014), CRP (rs = 0.403, p < 0.001), and IL-6 (rs = 0.339, p < 0.001). Serum ROM levels and IL-8 and CRP levels negatively correlated with %FEV₁ (rs = -0.240, p = 0.012, rs = -0.362, p < 0.001, rs = -0.197, p = 0.039, respectively). Serum ROM levels were significantly higher in patients who experienced severe exacerbation within 3 months than in patients who did not (339 [302–381] vs. 376 [352–414] CARR U, p < 0.025). Receiver-operating characteristics analysis showed that ROM levels correlated significantly with the occurrence of severe exacerbation (area under the curve: 0.699, 95% CI: 0.597–0.801, p = 0.025).

Conclusions

Serum levels of ROM were significantly associated with the degrees of airway obstruction, WBC counts, neutrophil counts, IL-6, and severe exacerbations. This biomarker may be useful in predicting severe exacerbations of BA.

[Allergic lung diseases other than asthma]

It is implicated that allergic reactions are involved in a variety of lung diseases except for bronchial asthma. These include hypersensitivity pneumonia (HP) induced by type III and IV hypersensitivity reactions to molds and other allergens, and eosinophilic pneumonia caused by known as well as unknown etiology. In Japan, summer type-hypersensitivity pneumonia is the most common disease, consisting approximately 70% of the HP cases. Eosinophilic pneumonia, originally reported as Löffler syndrome, has once been called pulmonary infiltration with eosinophilia or pulmonary eosinophilia. It is now recommended that acute and chronic eosinophilic pneumonia should first be diagnosed upon clinical and laboratory findings including bronchoscopic approaches. Then, causative agents such as drugs, allergens, parasites and fungi should be searched for further differentiated diagnosis. Corticosteroid treatment usually show marked beneficial effects with good prognosis, but in more chronically progressed cases, the outcome might be poor.