Heated tobacco products induced IL-8 overexpression with increased nicotinic acetylcholine receptor in human monocyte THP-1 cells

Abstract

<b>Introduction:</b> Cigarette smoke induces neutrophilic airway inflammation by releasing neutrophil chemoattractant including IL-8 from monocytes, which could be a major pathogenesis of chronic obstructive pulmonary disease. The impact of heated tobacco products on IL-8 production in monocytes have not been investigated. <b>Aims and objectives:</b> To investigate the effect of heated tobacco smoke on IL-8 production in monocytes. <b>Methods:</b> THP-1, human monocyte cell line, were exposed to cigarette smoke extract (CSE) or heated tobacco extract (HTE) for 24 hours before harvest. CSE and HTE were made from the 3R4F Kentucky reference cigarettes and the Marlboro iQOS heatsticks regular®, respectively. Cells were analyzed for LDH cytotoxic assay, quantitative real-time PCR for IL-8, CHRNA7, and NFKB1, and protein expression analysis using ELISA for IL-8 in culture supernatant and FACS for nicotinic acetylcholine receptor (nACh) expression in THP-1 cells. <b>Results:</b> Both CSE and HTE showed cytotoxicity, which was more extent in CSE than HTE. IL-8, NFKB1, and CHRNA7 gene expressions among THP-1 cells were up-regulated by CSE and HTE stimulation, respectively. In culture supernatant, the amount of IL-8 protein was increased by CSE and HTE stimulation. In FACS analysis, α-bungarotoxin positive cells were increased by CSE and HTE stimulation, which would indicate the increased expression nACh including CHRNA7 by CSE or HTE exposures. <b>Conclusions:</b> HTE induced IL-8 overproduction upon smoking stimulation as well as CSE, which might be related to the upregulation of nACh pathway in monocytes.