α5 Nicotinic Receptor Polymorphism affects cigarette smoke-induced inflammation and COPD development

RATIONALE: COPD is the third leading cause of death globally. Although cigarette smoke is the dominant risk factor, only a subset of smokers develop COPD, pointing to a significant role for genetic susceptibility. The α5 nicotinic acetylcholine receptor polymorphism (α5SNP; rs16969968), is expressed in the majority of COPD patients and may modulate immune responses to cigarette smoke. OBJECTIVES: To determine how α5SNP influences CS-induced inflammation and COPD pathogenesis in both experimental and clinical settings. METHODS: A murine knock-in model expressing wild-type (WT), heterozygous (HE), or homozygous (HO) α5SNP alleles was exposed to cigarette smoke or ambient air for one or three months. Lung function, histopathology, immune cell profiling, and cytokine expression were evaluated. In a human COPD cohort, we assessed α5SNP prevalence and the cytokine concentrations. MEASUREMENTS AND MAIN RESULTS: Cigarette smoke impaired lung function across all genotypes, but HE mice developed the most severe airflow limitation, inflammation, and airway remodeling. This phenotype was linked to heightened γδ T cell activation and increased TNF-α, associated with altered nAChR signaling in macrophages. Alteration of nicotine-induced cell signaling including adenylate cyclase and protein kinase-C is involved in modulation of cytokine production by macrophages. In humans, α5SNP was highly prevalent among COPD patients and strongly correlated with elevated systemic inflammation. CONCLUSIONS: α5SNP enhances susceptibility to cigarette smoke-driven lung injury and is present in the majority of COPD patients. These findings support α5SNP as a key genetic marker of susceptibility for COPD and its presence should be associated with precise follow-up in smokers.