Clusterin expression level correlates with increased oxidative stress in asthmatics.

BACKGROUND: Oxidative stress is thought to play a role in the pathogenesis of asthma. Clusterin is a sensitive cellular biosensor of oxidative stress and has antioxidant properties. The function and expression of clusterin in patients with asthma have not been fully investigated. OBJECTIVE: To investigate whether the expression of clusterin in patients with asthma is regulated by increased oxidative burden and whether clusterin expression could be used to assess the response to inhaled corticosteroids. METHODS: Clusterin levels in serum, induced sputum, and peripheral blood mononuclear cells of patients with asthma were measured by enzyme-linked immunosorbent assay and western blotting and compared with pulmonary function and levels of expression of hyperoxidized peroxiredoxins. Serum concentrations of clusterin in treatment-naive patients were compared before and after inhaled corticosteroid use. RESULTS: Serum clusterin concentration was significantly elevated in patients with severe asthma and was inversely correlated with pulmonary function. The expression of hyperoxidized peroxiredoxins was greatly increased in peripheral blood mononuclear cells of patients with asthma and was strongly correlated with clusterin expression. Serum clusterin concentrations in treatment-naive patients with asthma were decreased significantly after initial treatment with inhaled corticosteroids. CONCLUSION: Clusterin may be a biomarker of asthma severity and the burden of oxidative stress in patients with asthma. Moreover, clusterin may be useful for the prompt assessment of airway inflammation.