Association of eosinophilic inflammation with FKBP51 expression in sputum cells in asthma

Airway eosinophilia is a predictor of steroid responsiveness in steroid-naïve asthma. However, the relationship between airway eosinophilia and the expression of FK506-binding protein 51 (FKBP51), a glucocorticoid receptor co-chaperone that plays a role in steroid insensitivity in asthma, remains unknown. To evaluate the relationship between eosinophilic inflammation and FKBP51 expression in sputum cells in asthma. The FKBP51 mRNA levels in sputum cells from steroid-naïve patients with asthma (n = 31) and stable asthmatic patients on inhaled corticosteroid (ICS) (n = 28) were cross-sectionally examined using real-time PCR. Associations between FKBP51 levels and clinical indices were analyzed. In steroid-naïve patients, the FKBP51 levels were negatively correlated with eosinophil proportions in blood (r = -0.52) and sputum (r = -0.57), and exhaled nitric oxide levels (r = -0.42) (all p