title: Binding of a venom Lys-49 phospholipase A(2) to LPS and suppression of its effects on mouse macrophages.
abstract: The Lys49-phospholipases A(2) (K49-PLAs) are abundant in many pit vipers' venom. They are highly basic myotoxins and capable of binding membranes but lack hydrolytic activity. Considerable attention has been directed to its antibacterial activity but the exact mechanisms remain unclear. We now evaluate the roles of a K49-PLA from Trimeresurus stejnegeri venom in antagonizing the effects of lipopolysaccharide (LPS) on mouse macrophages (RAW264.7 cells). The K49-PLA markedly reduced LPS-stimulated production of NO, MCP-1, RANTES, and iNOS. RT-PCR analysis also confirmed its suppression of LPS-induced transcription of these cellular proteins. Moreover, LPS-induced activation of NFkappaB was dramatically abolished, while phosphorylation and degradation of IkappaB were also inhibited. Other types of venom phospholipases tested did not show the same effects as K49-PLA. Finally, strong binding between K49-PLA and LPS with a dissociation constant at the order of 10nM was shown by microcalorimetry titration. These findings provide unprecedented evidence that a low dose of K49-PLA possesses potent anti-inflammatory and antibacterial properties, which raises the prospect of a new therapeutic approach against sepsis.
authors.affiliation: Department of Orthopaedics and Traumatology, School of Medicine, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Shu-Huei
authors.initials: SH
authors.lastname: Tsai
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
authors.forename: Linda
authors.initials: L
authors.lastname: Chen
authors.forename: Ying-Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Inn-Ho
authors.initials: IH
authors.lastname: Tsai
mesh_terms: D000818:Animals; D002460:Cell Line; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D018946:Chemokine CCL5 / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D054501:Group II Phospholipases A2 / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D020033:Protein Isoforms; D030162:Reptilian Proteins / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity