Cytokine Expression and Promoter Methylation Signatures Underlying Immune Dysregulation in Mild and Severe COPD

Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory lung condition and a leading cause of morbidity and mortality worldwide. Despite well-established links to smoking, emerging evidence highlights the involvement of complex immune and epigenetic mechanisms in its pathogenesis. This study aimed to investigate the expression, secretion, and promoter methylation status of key pro- and anti-inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) of patients with mild and severe COPD, compared with healthy individuals. PBMCs were isolated from 90 participants divided into three groups: severe COPD, mild COPD, and healthy controls. Quantitative polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and methylation-specific PCR were employed to evaluate gene expression, protein secretion, and promoter methylation of inflammatory cytokines. Patients with COPD exhibited significant upregulation of pro-inflammatory cytokines (Interleukin1β (IL-1β), IL-6, IL-18, IFN-γ, and TNF-α) at both transcript and protein levels, with more pronounced alterations in the severe group. Conversely, anti-inflammatory mediators (IL-10 and TGF-β) were significantly downregulated. Promoter methylation analysis revealed hypomethylation in pro-inflammatory cytokine genes and hypermethylation in anti-inflammatory ones, correlating with disease severity. The findings demonstrate that COPD progression is associated with a shift toward a hyper-inflammatory, hypo-regulatory immune phenotype sustained by epigenetic modifications. These results support the potential for integrating cytokine-methylation signatures into clinical staging and for targeting epigenetic and immune pathways in future therapeutic strategies.