Cigarette smoke extract enhances rhinovirus-induced toll-like receptor 3 expression and interleukin-8 secretion in A549 cells.
BACKGROUND
Using A549 alveolar epithelial type II-like cells, we investigated the effects of cigarette smoke on the expression of rhinovirus (RV)-induced Toll-like receptor (TLR) 3, interleukin (IL)-6, and IL-8 secretion and viral replication.


METHODS
Cigarette smoke extract (CSE) was prepared by smoking two commercial cigarettes with filters (0.9-mg of nicotine and 8.5-mg of tar per cigarette). Cells were infected with RV serotype 16 (RV-16) and cultured for 2 days (RV group), pretreated with 1, 2.5, or 5% CSE for 1 day before RV infection, and culture with CSE for 2 days after infection (RV plus CSE group), or were cultured in medium for 3 days (control group), treated with 1, 2.5, or 5% CSE for 3 days (CSE group). Changes in TLR3, IL-6, and IL-8 mRNA expression were assayed by real-time polymerase chain reaction and TLR3 protein expression were assessed by flow cytometry; IL-6 and IL-8 secretions were measured by ELISA; and RV replication was assessed by viral culture.


RESULTS
CSE increased RV-induced TLR3 expression and RV-induced IL-8 secretion at lower concentrations in A549 cells. On the contrary, CSE dose dependently inhibited RV-induced IL-6 secretions and had no effect on RV replications.


CONCLUSIONS
Our results suggest that cigarette smoke may potentiate viral common cold symptoms by enhancing IL-8 secretion at lower concentrations, but not by increasing viral replication.
Wang
Jong Hwan
JH
Department of Otolaryngology, Asan Medical Center, University of Ulsan, College of Medicine, Seoul, Korea.
Kim
Hyuk
H
Jang
Yong Ju
YJ
D045744:Cell Line, Tumor; D045424:Complex Mixtures / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D010850:Picornaviridae Infections / Q000276:immunology* / Q000473:pathology; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000276:immunology / Q000473:pathology / Q000821:virology; D012229:Rhinovirus / Q000472:pathogenicity / Q000502:physiology*; D012907:Smoking / Q000009:adverse effects; D051196:Toll-Like Receptor 3 / Q000096:biosynthesis* / Q000235:genetics; D015854:Up-Regulation; D014779:Virus Replication
D045424:Complex Mixtures; D015850:Interleukin-6; D016209:Interleukin-8; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3