Antimalarial artesunate protects sepsis model mice against heat-killed Escherichia coli challenge by decreasing TLR4, TLR9 mRNA expressions and transcription factor NF-kappa B activation.
Bacterial DNA (bDNA) and lipopolysaccharide (LPS) are potent activators of immune cells such as monocytes and macrophages, which contribute to systemic inflammatory response syndrome (SIRS) and sepsis. Unfortunately, many experimental inflammatory antagonist-based therapies have failed in sepsis trials, and currently there is only one adjuvant therapy in clinical use, e.g. activated protein C. Artesunate (AS), a water-soluble derivative of dihydroartemisinin, has recently been demonstrated to protect against LPS-induced human umbilical vein endothelial cell (HUVEC) activation and injury by inhibiting tumor necrosis factor-alpha (TNF-alpha) mRNA expression. In the present study, heat-killed Escherichia coli was used to induce sepsis in the animal models. We observed that AS could protect mice against a lethal challenge with heat-killed E. coli in a dose-dependent manner. This protection was associated with reductions in serum TNF-alpha and measurable endotoxin levels. In addition, the treatment of murine peritoneal macrophage cells with AS strongly inhibited the release of TNF-alpha and IL-6 induced by CpG oligodeoxynucleotide (CpG ODN), LPS, or heat-killed E. coli in a dose-dependent manner. Experiments using affinity sensor technology revealed that AS could not directly bind to CpG ODN or LPS. Moreover, AS could not neutralize LPS in vitro. Further, flow cytometry revealed that AS could not alter the binding of CpG ODN to cell surfaces but could promote CpG ODN accumulation within RAW264.7 cells. Furthermore, AS reduced the expressions of TLR4 and TLR9 mRNA that were stimulated by LPS, CpG ODN, or heat-killed E. coli and inhibited heat killed E. coli-induced NF-kappaB activation. In conclusion, our results demonstrated that AS-mediated protection against a lethal heat-killed E. coli challenge was associated with a reduction in proinflammatory cytokine release and endotoxin levels via a mechanism involving a decrease in TLR4, TLR9 mRNA expression and NF-kappaB activation.
Li
Bin
B
Department of Pharmacology, College of Pharmaceutical, Third Military Medical University, Chongqing 400038, China.
Zhang
Rong
R
Li
Jun
J
Zhang
Lezhi
L
Ding
Guofu
G
Luo
Ping
P
He
Shengqi
S
Dong
Yan
Y
Jiang
Weiwei
W
Lu
Yongling
Y
Cao
Hongwei
H
Zheng
Jiang
J
Zhou
Hong
H
D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D037621:Artemisinins / Q000494:pharmacology* / Q000627:therapeutic use; D000077332:Artesunate; D016470:Bacteremia / Q000188:drug therapy*; D002478:Cells, Cultured; D004731:Endotoxins / Q000097:blood; D004927:Escherichia coli Infections / Q000188:drug therapy*; D005260:Female; D015850:Interleukin-6 / Q000096:biosynthesis; D008297:Male; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis*; D012717:Sesquiterpenes / Q000494:pharmacology* / Q000627:therapeutic use; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors / Q000235:genetics*; D051217:Toll-Like Receptor 9 / Q000037:antagonists & inhibitors / Q000235:genetics*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D000962:Antimalarials; D037621:Artemisinins; C408982:CPG-oligonucleotide; D004731:Endotoxins; D015850:Interleukin-6; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D012717:Sesquiterpenes; C493487:Tlr4 protein, mouse; C495370:Tlr9 protein, mouse; D051197:Toll-Like Receptor 4; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha; D000077332:Artesunate