TLR2 modulates bronchial epithelial cell senescence in smoking-induced COPD via IGFBP3 through ERK and NF-κB pathways

Chronic obstructive pulmonary disease (COPD) is a major health concern worldwide and a leading cause of mortality. Despite advances in clinical treatment, no therapies exist that can halt disease progression. Cellular senescence, driven by oxidative stress from cigarette smoke (CS) exposure, is a key feature in COPD pathogenesis, influencing disease progression and prognosis. This research investigated how cigarette smoke causes cellular senescence in bronchial epithelial cells associated with COPD, highlighting the importance of toll-like receptor 2 (TLR2), insulin-like growth factor-binding protein 3 (IGFBP3), and the activation of ERK and NF-κB signaling pathways. Lung tissues from non-smokers and smokers in COPD was used for senescence-associated β-galactosidase (SA-β-gal) staining and immunohistochemistry of p16, p21, TLR2, and IGFBP3. A COPD mouse model was established via chronic CS exposure. Human bronchial epithelial BEAS-2B cells were treated with cigarette smoke extract (CSE), and senescence was assessed following TLR2 or IGFBP3 knockdown. Immunoprecipitation assays were used to examine protein interactions, and IGFBP3 overexpression was performed to validate its functional role. Western blot and IHC were employed to evaluate pathway activation. In lung tissues of smokers with COPD, levels of p16, p21, SA-β-gal, TLR2 and IGFBP3 were significantly higher than in non-smokers. CSE treatment of BEAS-2B cells led to comparable elevations in senescence-associated secretory phenotype (SASP) factors and senescence markers. TLR2 knockdown reduced senescence and IGFBP3 secretion. IP assays confirmed that IGFBP3 interacts with ERK and NF-κB under CSE treatment. IGFBP3 knockdown attenuated CSE-induced NF-κB and phosphorylation of ERK and senescence markers, while IGFBP3 overexpression enhanced these effects. The study reveals that TLR2 contributes to CS-induced senescence by regulating IGFBP3 in bronchial epithelial cells, with ERK and NF-κB pathway activation being pivotal. These findings offer valuable insights into the molecular mechanisms underlying COPD and suggest possible therapeutic targets to slow COPD progression by modulating senescence pathways. • TLR2 drives CSE-induced senescence in bronchial epithelium via IGFBP3. • IGFBP3 directly binds ERK and NF-κB and enhances their phosphorylation. • TLR2 or IGFBP3 knockdown reduces p16/p21, SASP factors, and SA-β-gal. • COPD mice and patient lungs show elevated TLR2, IGFBP3, and senescence markers.