While cigarette smoke extracts increase GDF15 production (Jiang et al., 2018), the concentrations of circulating GDF15 are generally increased in chronic obstructive pulmonary disease (COPD) compared with healthy individuals, where GDF15 contributes to mucin production in ciliated epithelial cells (Wu et al., 2012; Jiang et al., 2018), and the deletion of GDF15 leads to the amelioration of cigarette smoke-related pulmonary inflammation (Verhamme et al., 2017). This evidence concerns the gene MUC5AC and chronic obstructive pulmonary disease.