Susceptibility and cellular responses of COPD airway epithelium to cigarette smoke in stem cell-derived ALI models

Despite cigarette smoke being the chief driver of chronic obstructive pulmonary disease (COPD), numerous patients maintain their smoking habits by opting for low-yield or slim cigarettes under the misconception of diminished health risks. Differential effects of high-tar conventional versus low-tar slim cigarettes on COPD airway epithelium remain poorly defined. We established an air-liquid interface (ALI) model using patient-derived COPD airway epithelial stem cells and exposed cultures to high-tar conventional smoke (TC), low-tar slim smoke (SC), or filtered air (NC). Both regimens induced IL-1β inflammation, ciliary structural changes, and oxidative stress, with TC eliciting stronger responses. Single-cell RNA sequencing resolved six epithelial populations. In ciliated cells, hdWGCNA showed NC modules associated with cilium organization and assembly, SC adaptive defense responses, and TC more extensive reprogramming of ciliary functional networks. Basal cells displayed stress-pathway activation, squamous metaplasia signatures, and developmental regression toward a stem-like state, with TC producing approximately 1.7-fold stronger regression than SC. Secretory cells exhibited identity erosion, antimicrobial program downregulation, and a shift toward keratinization and squamous-oriented programs, again more pronounced under TC. These findings indicate that high-tar conventional smoke exerts greater influence than low-tar slim smoke on COPD airway epithelium across inflammatory, structural, and lineage-specific molecular dimensions, providing high-resolution insight into cell-type-specific responses to continued smoke exposure.