Cellular senescence is increasingly recognized as a hallmark of Chronic Obstructive Pulmonary Disease (COPD), with higher levels in lung fibroblasts from COPD patients. Upon senescence, both hypomethylation and hypermethylation have been described, but not in COPD-derived fibroblasts yet. This study investigated whether altered DNA methylation can be a driver of fibroblasts senescence in COPD. Genome wide gene expression and DNA methylation data was generated from primary lung fibroblasts of 11 COPD stage IV patients and 10 matched controls. Gene expression of six well-known senescence genes was compared between COPD and control. COPD-associated senescence genes were correlated with their related CpG sites in an expression quantitative trait methylation (eQTM) analysis. Methylation levels of significant eQTMs were compared between COPD and control fibroblasts. A causal relationship between altered DNA methylation and senescence was validated in 5-Aza-2'-deoxycytidine (5-Aza-2'-dC)-treated primary lung fibroblasts. Gene expression of CDKN1A, CDKN2A, and CDKN2B was higher, while LMNB1 expression was lower in COPD-derived fibroblasts compared to control. A total of 19 eQTMs were found for the COPD-associated senescence genes CDKN1A (9), CDKN2A (1), and LMNB1 (9). Among these, seven CpG sites (four for CDKN1A and three for LMNB1) exhibited differential methylation between COPD and control. Treatment with 5-Aza-2'-dC led to global demethylation and increased senescence and importantly, confirmed the association between senescence and hypomethylation of the COPD-associated CpG site cg04924375. Altered DNA methylation is linked to fibroblast senescence in COPD and seven CpG sites are identified as potential epigenetic regulators of the senescence genes CDKN1A and LMNB1.
