COPD cells showed decreased mRNA expression of CLDN1, CLDN8 and TJP1, and increased expression of CLDN10 compared to healthy cells, but the differences were not statistically significant for CLDN1, and CLDN8. With overexpression of CDH1 in COPD cells, the mRNA expression of CLDN1, CLDN8, and TJP1 was increased, and CLDN10 was decreased (Fig. 7d, g, and j). The gene discussed is CLDN1; the disease is chronic obstructive pulmonary disease.