[Experimental study on the antagonistic activity of cationic multi-peptide mastoparan-1 against lipopolysaccharide].
OBJECTIVE
To explore the mechanism of cationic multi-peptide mastoparan-1 (MP-1) on the protection of mice from lipopolysaccharide (LPS) challenge.


METHODS
Thirty Kunming mice were divided randomly into MP-1, injury, protection groups with 10 mice in each group. The mice in MP-1 group were injected with 3 mg/kg MP-1 by tail vein, while those in injury group were injected with 20 mg/kg LPS by tail vein, and those in protection group 3 mg/kg MP-1 within 20 seconds after 20 mg/kg LPS injection were injected. The effects of MP-1 on the protection of mice from LPS challenge were observed. In vitro, the affinity of MP-1 and PMB to LPS was compared by biosensor and FAST fit construct and expressed as Kd. And the neutralizing activity of MP-1 and PMB in dose of 5, 10, 20, 40 micromol/L on LPS (2 microg/L) was detected by dynamic turbidimetric limulus test with LPS neutralizing 0 micromol/L MP-1 and PMB as control. The mRNA expression levels of TLR4, TNF-alpha and IL-6 in murine peritoneal macrophages (PM phi) after exposure to LPS (100 ng/ml) were assayed by RT-PCR.


RESULTS
MP-1 could significantly protect mice from LPS challenging with protection rate of 90%. In vitro, MP-1 had a high affinity (Kd value: 484.0 nmol/L) and neutralizing ability with LPS, but it was lower than that of PMB (Kd value: 18.9 nmol/L). The neutralizing effect of 20 and 40 micromol/L MP-1 was obviously stronger than that in 0 micromol/L (P < 0.01). MP could obviously inhibit the expression of TLR4, TNF-alpha and IL-6 mRNA in LPS-stimulated murine PM phi.


CONCLUSIONS
MP-1 can evidently protect mice from lethal LPS challenge, and the mechanism might be related to the activity of MP-1 which binding and neutralizing LPS, blocking the combination LPS with its receptors. So the murine macrophage activation induced by LPS was inhibited.
Guo
Yi-bin
YB
General Experimental Research Center, Southwest Hospital, The Third Military Medical University, Chongqing 400038, P.R. China.
Zheng
Jiang
J
Lv
Gen-fa
GF
Wei
Guo
G
Wang
Liang-xi
LX
Xiao
Guang-xia
GX
D000818:Animals; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D010455:Peptides / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism; D014862:Wasp Venoms / Q000494:pharmacology*
D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D010455:Peptides; D012333:RNA, Messenger; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D014862:Wasp Venoms; C037500:mastoparan