LAUSR

Background: The altered expression of monocyte chemotactic protein 1 (MCP1) in bronchoalveolar fluid was observed in patients and animal models of allergic asthma. However, the correlation between induced sputum MCP1 level and asthma clinical features remains poorly understood. Objective: This study aims to explore the relationship of MCP1 protein expression in induced sputum with Th2 inflammation and asthma clinical features. Methods: MCP1 protein expression in induced sputum and serum was detected by ELISA in patients with asthma, and its correlation with Th2 inflammation and lung function was analyzed. The effect of inhaled corticosteroids (ICSs) on MCP1 expression was also evaluated. Results: The MCP1 level in induced sputum (p = 0.0006) and serum (p = 0.0035) was markedly increased and negatively correlated with forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC)% (r = −0.3674, p = 0.0001) and PC-20 (r = −0.5746, p < 0.0001) in patients with asthma. The area under the curve (AUC) of MCP1 level receiver operating characteristic curve in induced sputum and serum was 0.7134 (p = 0.0007) and 0.7589 (p = 0.0042), respectively. The patients with asthma were grouped into four according to their induced sputum MCP1 level and Th2 signature categories (Th2Hi MCP1Hi, Th2Hi MCP1Low, Th2Low MCP1Hi, and Th2Low MCP1Low). The Th2Low MCP1Hi subgroup had the lowest FEV1/FVC% and histamine concentration required to cause a 20% decline in FEV1. After 4 weeks of ICS treatment, the MCP1 levels in induced sputum and serum were significantly reduced. Conclusions: The MCP1 level in induced sputum and serum increased in patients with asthma but decreased after ICS treatment. The Th2Low MCP1Hi subgroup had the worst lung function and highest airway hyperresponsiveness. The combination of MCP1 level in induced sputum and Th2 inflammation defines a new phenotype that can be used to predict lung function and treatment response in patients with asthma.