DNA methylation as a driver of lung fibroblast senescence in COPD

<bold>Rationale:</bold> COPD lung fibroblasts have higher levels of cellular senescence compared to control fibroblasts. Likely this is related to DNA methylation changes given its importance in inducing and maintaining senescence. <bold>Aim:</bold> To investigate whether DNA methylation is involved in fibroblast senescence in COPD. <bold>Methods:</bold> RNA-seq and DNA methylation data (EPICv2 array) was generated from primary lung fibroblasts from 11 COPD patients and 10 controls. Gene expression of six well-known senescence genes (CDKN1A, CDKN1B, CDKN2A, CDKN2B, TP53, and LMNB1) was compared between COPD and control. To assess the regulatory role of DNA methylation, expression quantitative trait methylation (eQTM) analyses in which the expression of the significant senescence genes was correlated with the methylation of all CpG sites located within a 2 Mb window around the gene was performed. <bold>Results:</bold> Three out of six senescence genes were differentially expressed in COPD-derived lung fibroblasts compared to controls, including higher expression of CDKN1A, CDKN2B, and lower expression of LMNB1, confirming higher levels of senescence. Two CpG sites, cg04924375_TC21 (CDKN1A) and cg17805864_BC21 (LMNB1) were significantly correlated with the expression of their relevant gene and also showed differential methylation levels in COPD fibroblasts in the opposite direction of the gene expression. <bold>Conclusion:</bold> In line with previous observations, we showed differential expression of three senescence marker genes in COPD-derived lung fibroblasts. For CDKN1A and LMNB1, we identified two negatively associated CpG sites, which could be potential epigenetic drivers of fibroblast senescence in COPD.