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A1207 - Characterizing the Impact of Cigarette Smoking on Human Small Airway Club Cell Transcriptome by Single Cell RNA-Sequencing
Author Block: W. Zuo, S. A. Shenoy, M. Rostami, G. Wang, S. L. O'Beirne, R. J. Kaner, P. L. Leopold, J. G. Mezey, R. G. Crystal; Weill Cornell Medical College, New York, NY, United States.
RATIONALE: Club cells, secretory cells representing ~20% of the human small airway epithelium (SAE), function in host defense, metabolism of xenobiotics, anti-protease defense and physical barrier. Cigarette smoking, the major cause of COPD, is associated with a deficit in SAE club cell numbers, but little is known about the effects of cigarette smoking on the transcriptome/biology of the club cells. The focus of this study is to identify changes in human SAE club cell-specific genes in response to cigarette smoking.
METHODS: Human small airway cells were obtained from 3 healthy nonsmokers and 3 smokers by bronchoscopy and brushing 10th-12th order bronchi. The cells were dissociated by trypsin and processed through FACS sorting to generate a single alive cell suspension. Drop-seq single-cell RNA-sequencing was used to characterize the transcriptome of single cells from the human small airway.
RESULTS: The unbiased clustering on the single cell transcriptome identified total 11 distinct cell populations in the human small airways. Using cell-specific signature genes to identify the clusters, a cell population that uniquely expressed the club cell marker SCGB1A1 was defined as the club cell cluster. Consistent with previous studies, the cellular proportion of club cell cluster in non-smokers (~20%) was significantly lower in smokers (~10%). Comparison of the transcriptomes of club cell clusters in non-smokers vs smokers identified a club cell-specific transcriptome reprogrammed by cigarette smoking. Genes that function in defense against toxins (ALDN3A1, CYP26A1 and AKR1C2), oxidative stress response (CYP1B1, NQO1 and PRDX1), signaling transduction (SFRP2 and TSPAN1) and transcriptional regulation (JUN) were significantly up-regulated in the club cells from smokers. In contrast, expression of several host defense genes, including SCGB1A1, MUC5B, PIGR, CXCL6 and C3, as well as the anti-protease SLPI, and the cell proliferation-related genes SCGB3A1 and TMEM45, were decreased in the club cells from smokers.
CONCLUSIONS: The human small airway epithelium club cell is reprogrammed by cigarette smoking to up-regulate genes that defend against toxins and oxidative stress. However, smoking also causes a suppression of genes relating to defending against inflammation, pathogens and proteases, i.e., not only is smoking associated with a loss of club cell numbers, but also a suppression of many functions in host defense.