[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.
General Experimental Research Center, Southwest Hospital, The Third Military Medical University, Chongqing 400038, P.R. China.
Yi-bin
YB
Guo
Jiang
J
Zheng
Gen-fa
GF
Lv
Guo
G
Wei
Liang-xi
LX
Wang
Guang-xia
GX
Xiao
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