Our previous studies have shown that BRD4 is increased and correlated with interleukin (IL)-8 expression levels in the lung of stable COPD patients, and in vitro studies have also suggested that BRD4 inhibition suppresses CS extract (CSE)-induced IL-8 expression in bronchial epithelial cells [18]. This evidence concerns the gene CXCL8 and chronic obstructive pulmonary disease.