PADI4 and chronic obstructive pulmonary disease: Specifically, following Dex treatment, the expression levels of PADI4 and CitH3 in the lung tissues of GPX4-cko COPD mice decreased (Fig. 7C and D), serum NE levels declined (Fig. 7E), and immunofluorescence analysis revealed reduced expression levels of CitH3 and Ly6G in lung tissues (Fig. 7F to H).