Use of aquaporins 1 and 5 levels as a diagnostic marker in mild-to-moderate adult-onset asthma

Characteristic features of asthma include airway inflammation and hyperactivity, mucus hypersecretion, mucosal edema, and airway remodeling. These features could be due to pathological water transport across pulmonary epithelia and aquaporins (AQPs) have recently been isolated as key proteins in fluid transportation in the human respiratory tract. We aimed to evaluate the role of aquaporins in the pathogenesis of asthma and their possible use a diagnostic marker of the disease. A total of 110 hospitalized and outpatients with mild to moderate adult-onset asthma were invited to participate in this study and 34 submitted an induced sputum sample adequate for analysis. The amount of AQP1, AQP5 and MUC5AC were measured with ELISA assay. The amount of IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17 in both serum and sputum were measured with Cytometry Bead Array (CBA kit). Our results suggest that sputum AQP5, AQP1 and MUC5AC are all in a good correlation (r=0.498 between AQP5 and AQP1, r=0.529 and r=0.661 between MUC5AC and AQP5 or AQP1, respectively, all P<0.05). The AUC value for AQP1 and AQP5 to diagnose asthma were 0.729 and 0.745, respectively. In conclusion, water homeostasis plays an important role in maintaining adequate fluid transportation within the lung and is involved in the pathogenesis of asthma. Our results suggest that AQP may influence pulmonary physiology that their dysfunction can contribute to pulmonary pathogenesis, such as asthma. Moreover, their quantification could serve as biomarkers for the diagnosis of asthma.