Cell-type specific expression of TSLP & its regulation by smoking in human airway epithelium

<bold>I:</bold> Thymic Stromal Lymphopoietin (TSLP) is an alarmin, mainly secreted by airway epithelial cells upon inhalation of cigarette smoke-like insults. Higher TSLP levels seen in COPD airways & anti-TSLP may constitute a novel therapeutic strategy. However, it is unclear which epithelial cell subtypes express TSLP & whether it is affected by smoking. <bold>M:</bold> Single-cell RNA expression of TSLP, investigated in integrated human lung cell atlas (HLCA) and air-liquid-interface (ALI)-differentiated primary bronchial epithelial cells dataset. Trajectory analysis examines the TSLP expression shift throughout the cell differentiation. Cellular deconvolution (CD) determines cell type-specific expression of TSLP in bronchial biopsy bulk sequence data of current(n=33) vs ex-smoking(n=46) COPD patients(GLUCOLD)& current(n=37) vs never(n=40) smokers with normal lung function (NORM) & bronchial brushes microarray dataset of current(n=30) vs ex-smoking(n=57) COPD patients. Data were analysed in R statistical software. <bold>R:</bold> TSLP gene expression was found to be specific to resting basal epithelial cells in both HLCA and ALI datasets. The trajectory analysis confirmed loss of TSLP expression when cells differentiate from resting basal into suprabasal. CD demonstrated that TSLP expression highly correlates with basal cells(p<0.0001) in all 3 cohorts. TSLP was significantly lower expressed in current smokers than ex-/never smokers in 3 cohorts (p<0.05). <bold>C:</bold> TSLP is expressed in resting basal cells, which are known to lower in current smokers vs ex-smokers/ never-smokers. Accordingly, TSLP expression is lower in current smokers. Thus, separating the patient population based on smoking status would be importent in anti-TSLP therapy