[Effects of the cell wall of Streptococcus mutans on the expression of TLR4, IL-6 and IL-8 by EAhy926 cells].
OBJECTIVE
To investigate the effects of the cell wall of Streptococcus mutans on the expression of Toll-like receptor 4 (TLR4), IL-6 and IL-8 in EAhy926 cells (The human endothelial hybridoma of human umbilical vein endothelial cells (HUVEC) and the human epithelial cell line A549, characterized by endothelial phenotype and biology).


METHODS
EAhy926 cells were treated with different concentrations of the cell wall of Streptococcus mutans. The proliferation of EAhy926 cells was determined by MTT assay. The mRNA expression of TLR4, IL-6 and IL-8 in EAhy926 cells was detected by reverse transcription polymerase chain reaction (RT-PCR). TLR4 was analyzed by flow cytometry. The production of IL-6 and IL-8 in the cultured supernatants was measured by biochemical method and ELISA respectively. TLR4 blocking assay was used to investigate the relationship between IL-6, IL-8 and TLR4 mRNA expression.


RESULTS
The proliferation of EAhy926 cells was significantly enhanced by the cell wall of Streptococcus mutans at 6 h (P<0.05), and inhibited after 12 h (P<0.05), both time- and dose-dependent. The expression of mRNA and protein for TLR4 in EAhy926 cells was increased after stimulated by the cell wall of Streptococcus mutans, peaking at 16 h (P<0.05), and then decreased. The expression of IL-6 and IL-8 mRNA was significantly induced when exposed to the cell wall, reaching the maximal level at 16 h and 24 h, respectively (P<0.05). Meanwhile, the cell wall of Streptococcus mutans induced the production of IL-6 and IL-8 (P<0.05). The expression of IL-6 and IL-8 mRNA in EAhy926 cells was blocked by anti-human TLR4 antibodies significantly.


CONCLUSIONS
The cell wall of Streptococcus mutans upregulated the expression of TLR4 and induced the production of inflammatory cytokines IL-6 and IL-8, indicating that the expression of TLR4 of EAhy926 cells may elicit a TLR4-mediated innate immune response and contribute to production of inflammatory cytokines IL-6 and IL-8.
Li
Qin
Q
Department of Microbiology, Capital Medical University, Beijing 100069, China. liqinsnow@163.com
Wang
Yisong
Y
Zheng
Qun
Q
Zhao
Zhipeng
Z
Ping
Guoling
G
Zhang
Liping
L
D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002473:Cell Wall / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics* / Q000276:immunology; D016209:Interleukin-8 / Q000235:genetics* / Q000276:immunology; D009154:Mutation; D013290:Streptococcal Infections / Q000276:immunology* / Q000382:microbiology; D013295:Streptococcus mutans / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000235:genetics* / Q000276:immunology
D001426:Bacterial Proteins; D015850:Interleukin-6; D016209:Interleukin-8; D051197:Toll-Like Receptor 4