The Convergent Immunopathogenesis of Cigarette Smoke Exposure: From Oxidative Stress to Epigenetic Reprogramming in Chronic Disease.

Cigarette smoking is the leading preventable cause of chronic diseases (e.g., COPD, cardiovascular disease, cancer), largely driven by persistent immune-inflammatory mechanisms. This review synthesizes the molecular and cellular cascades linking cigarette smoke (CS) exposure to chronic pathology. CS constituents, particularly ROS/RNS, induce rapid oxidative stress that overwhelms antioxidant defenses and generates damage-associated molecular patterns (DAMPs). These DAMPs activate pattern recognition receptors (PRRs) and the NLRP3 inflammasome, initiating NF-κB signaling and the release of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). CS exposure causes profound innate immune dysregulation, including airway epithelial barrier disruption, hyperactivated neutrophils, and dysfunctional alveolar macrophages (AMs) that release destructive proteases (e.g., MMP-12) and acquire foam-cell-like characteristics. Furthermore, CS drives adaptive immunity toward a Th1/Th17-dominant phenotype while suppressing regulatory T-cell (Treg) function, thereby promoting autoimmunity and chronic tissue injury. Critically, CS induces epigenetic reprogramming (e.g., DNA methylation, miRNA dysregulation), locking immune cells into a persistent pro-inflammatory state. This convergence of oxidative stress, innate and adaptive immune dysregulation, and epigenetic alterations underlies the systemic low-grade inflammation that fuels smoking-related chronic diseases, highlighting key targets for novel therapeutic interventions.