The characteristics and clinical significance of mucin levels in bronchoalveolar lavage fluid of patients with interstitial lung disease

To investigate the expression and clinical significance of secretory mucins in patients with interstitial lung disease (ILD). The bronchoalveolar lavage fluid (BALF) concentrations of mucins (MUCs) from 27 patients with ILD, 6 patients with lung cancer, 8 patients with pleural effusion and 9 patients with bronchiectasis were determined by ELISA. The concentration of MUC5AC was significantly increased in patients with ILD (12.84±15.02 ng/mL) compared with patients with pleural effusion (4.33±2.51 ng/mL), lung cancer (8.02±5.57 ng/mL) or bronchiectasis (6.08±2.40 ng/mL) (p<0.01). The MUC2 level (10.23±9.27 ng/mL) was significantly elevated in patients with ILD than in those with pleural effusion (6.21±3.28 ng/mL) or bronchiectasis (5.73±1.51 ng/mL) (both p<0.05). Patients with ILD (104.64±61.61 ng/mL), lung cancer (148.45±169.24 ng/mL) or bronchiectasis (123.68±63.28 ng/mL) had significantly greater IL-8 levels than in those with pleural effusion (76.46±2.16 ng/mL) (p<0.05). A significant positive correlation was detected between the MUC5AC concentration and the lymphocyte percentage in BALF of patients with ILD (r=0.504, p=0.007). Lung function tests of patients with ILD exhibited various degrees of restrictive ventilation dysfunction and reduced diffusing capacity. The MUC5AC levels in BALF were negatively correlated with forced expiratory volume in 1 second (FEV(1))/forced vital capacity (r=−0.761, p=0.000), FEV(1) predicted value (FEV(1)/pred) (r=−0.668, p=0.002), and diffusing capacity (r=−0.606, p=0.006). Secretory mucins MUC5AC, MUC2 and IL-8 were highly expressed in ILD. MUC5AC level was closely correlated with the amount of inflammatory cells in BALF and the lung function parameters.