Activities and concentration of alpha-1 antitrypsin and cystatin C in serum from patients with house dust mite asthma

Background: The proteolytic activities of house dust mite (HDM) allergens are involved in the pathogenesis of asthma by cleaving T-junction protein complexes, increasing the permeability of airway epithelial cells, and enabling the allergens to reach the interstitial tissue. The human body contains natural protease inhibitors such as alpha-1 antitrypsin (AAT) with antiserine protease activity and cystatin C with anticysteine protease activity. Objective: This study aimed to investigate the behavior of serum AAT and cystatin C levels in patients with HDM-allergic asthma. Methods: Ten individuals with HDM-allergic asthma and 10 healthy volunteers participated in a cross-sectional study. The serum AAT and cystatin C inhibitory activities were measured using enzymatic assays. ELISA was used to determine the serum AAT and cystatin C concentrations. Results: Serum AAT inhibitory activity (P = 0.445; P > 0.05), AAT concentration (P = 0.290; P > 0.05), and cystatin C concentration (P = 0.419; P > 0.05) did not significantly differ between the patient and control groups. However, serum cystatin C inhibitory activity in the asthmatic patient group was significantly higher than in the healthy subjects (P = 0.001; P < 0.05). There was no correlation between AAT inhibitory activity and AAT concentration or between cystatin C inhibitory activity and cystatin C concentration. Conclusion: These findings suggest that serum cystatin C activity is involved in asthma pathogenesis. Additional research is required to address this issue.