Antimalarial artesunate protects sepsis model mice against heat-killed Escherichia coli challenge by decreasing TLR4, TLR9 mRNA expressions and transcription factor NF-κB activation

• Published in: International immunopharmacology Vol. 8; no. 3; pp. 379 - 389
• Main Authors: Li, Bin, Zhang, Rong, Li, Jun, Zhang, Lezhi, Ding, Guofu, Luo, Ping, He, Shengqi, Dong, Yan, Jiang, Weiwei, Lu, Yongling, Cao, Hongwei, Zheng, Jiang, Zhou, Hong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-03-2008; Elsevier
• Subjects: Animals; Antimalarials - pharmacology; Artemisinins - pharmacology; Artemisinins - therapeutic use; Artesunate; Bacteremia - drug therapy; Biological and medical sciences; Cells, Cultured; CpG ODN; Endotoxins - blood; Escherichia coli Infections - drug therapy; Female; Heat-killed Escherichia coli; Interleukin-6 - biosynthesis; LPS; Male; Medical sciences; Mice; NF-kappa B - metabolism; Oligodeoxyribonucleotides - metabolism; Pharmacology. Drug treatments; Proinflammatory cytokines; RNA, Messenger - analysis; Sepsis; Sesquiterpenes - pharmacology; Sesquiterpenes - therapeutic use; TLR4; TLR9; Toll-Like Receptor 4 - antagonists & inhibitors; Toll-Like Receptor 4 - genetics; Toll-Like Receptor 9 - antagonists & inhibitors; Toll-Like Receptor 9 - genetics; Tumor Necrosis Factor-alpha - biosynthesis; Artesunate; Heat-killed Escherichia coli; TLR9; Sepsis; CpG ODN; Proinflammatory cytokines; TLR4; LPS; Antimalarial; Animal model; Temperature; Toll like receptor 4; Escherichia coli; Environmental factor; Activation; Toll like receptor 9; Prevention; Sepsis syndrome; Signal transduction; Messenger RNA; GC rich sequence; Lipopolysaccharide; Bacteria; Transcription factor NFκB; Transcription factor; Enterobacteriaceae; Nucleotide sequence; Rodentia; Cytokine; Inflammation; Infection; Vertebrata; Heat; Mammalia; Mouse; Parasiticide
• ISSN: 1567-5769; 1878-1705
• DOI: 10.1016/j.intimp.2007.10.024

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-α) 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-α and measurable endotoxin levels. In addition, the treatment of murine peritoneal macrophage cells with AS strongly inhibited the release of TNF-α 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-κB 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-κB activation.