Survival And Anti-inflammatory Effects Of A Novel Antimicrobial Peptide G3KL On Mice Infected With Escherichia Coli

Objective:To explore the protective effect and the anti-inflammatory of new antibacterial peptides G3KL subtypes M166 and TNS122 for mice with intra-abdominal infection induced by multi-drug resistant Escherichia coli,liver and kidney functions of mice infected with abdominal cavity.New ideas will be provided for the treatment of multi-drug resistant bacteria from a new point of view.Methods:1.By two-fold dilution method determined the minimum inhibitory concentration of M166,TNS122 and Imipenem against multi-drug resistant Escherichia coli,judged the antibacterial ability of each drug in vitro.2.Balb/c mice were randomly divided into 10 groups.In groups 1-9,each of the mice was intraperitoneally injected with a concentration of 1.00,1.25,1.50,…,3.00×10~8cfu/ml ESBLs.E.c.0.5 ml,and the 10th group was administered with 0.5 ml of physiological saline as a control group.Observed the death of the mice for 24 hour;used the minimum lethal dose of 100%of the mice as the modeled concentration.3.Balb/c mice were randomly divided into 5 groups:control group,model group,M166experimental group,TNS122 experimental group and Imipenem experimental group,10 in each group.After successful modeling,the experimental groups were intraperitoneally administered TNS122,M166 and Imipenem drugs was 5,5,0.5 mg/kg,Once every 8 hours.The control group and the model group were supplemented with sodium chloride injection.Observed the activity of each group of mice for 48hour and calculated the mortality.4.The mice were grouped,modeled and administered in the same way as Method 3.After 1 hour,6 hours,and 10 hours of infection in each group,by eyeball extraction collected the blood of each group.Used the blood bacterial concentration,inflammatory factors(IL-6,CRP),liver and kidney function(ALT,AST and BUN)levels to analyze the anti-inflammatory effects and liver and kidney function of each drug in mice with intra-abdominal infection.Results:1.By double dilution method,the minimum inhibitory concentrations of Imipenem,M166and TNS166 were 0.5ug/ml,16ug/ml and 8ug/ml.2.After intra-abdominal infection of different gradients of Escherichia coli in each group of mice,each group of mice appeared negative activity,contracted into a mass,did not feed into the water;hair erected wet,irregular,luster,eye purulent discharge,thin stools and so on.Mice died after 10 hour,and most of the deaths were concentrated between 12 and 17 hour,and no longer died after 20 hour.According to the number of deaths in each group of mice,established the concentration of 1.75×10~8cfu/ml for the model of mouse intra-abdominal infection.3.The 48 hour survival rates of the control group,TNS122 group,M166 group,Imipenem group and model group were:100%,100%,90%,80%,0%.4.Blood bacterial concentration at different time points after drug treatment of intra-abdominal infection in each group:the model group changed with time,the bacterial concentration in the blood of the mice was higher and higher;after the treatment with Imipenem,M166 and TNS122,the blood bacteria concentration of each groups have decreased.Compared with the model group,the blood bacteria concentration of M166 group,TNS122 group and Imipenem group decreased significantly.Compared with M166,the blood concentration of TNS122 group and Imipenem group increased,the differences were statistically significant(P<0.05).IL-6 levels of mice after drugs treatment 1 hour:Compared with the control group,plasma IL-6 levels of mice were significantly increased in the other four groups;there was no significant difference between the other four groups(P>0.05).IL-6 levels of mice after drugs treatment 6 hour and 10 hour:Compared with the model group,plasma IL-6 levels of M166group,TNS122 group and Imipenem group were significantly decreased.IL-6 levels of mice after drugs treatment 10 hour:Compared with the M166 group,the IL-6 levels of Imipenem and TNS122 increased,the differences were statistically significant(P<0.05).In the model group and the experimental groups,the liver function ALT and AST of the mice were not significantly changed after drugs treatment 1 hour.There were no significant differences in plasma ALT and AST between the each two groups(P>0.05).AST levels of mice after drugs treatment 6hour:Compared with the control group,the model group,and the Imipenem group,the plasma levels of AST in the M166 group and the TNS122 group were significantly increased.In the 10 hour after intra-abdominal infection,the ALT level in the blood of mice:compared with the TNS122 group,the ALT levels in other groups were significantly lower;AST level after drugs treatment 10 hour:compared with the control group and the model group,the plasma AST levels of M166 group,TNS122 group and Imipenem group were significantly increased,and the differences were statistically significant(P<0.05).Detected the blood inflammatory factors IL-6 and CRP at different time points:In the model group,the inflammatory factors were gradually increased after the infection of the mice with intra-abdominal infection;in other experimental groups the inflammatory factors increased or decreased with time.Compared with the control group,the IL-6 and CRP of other four groups were elevated;the levels of IL-6 and CRP in each experimental group were significantly lower at 1 hour(P>0.05);detected IL-6 and CRP levels after drugs treatment 6hour and 10 hour:Compared with the model group,the levels of IL-6 and CRP of the experimental group were significantly lower.After 10 hours of intra-abdominal infection in mice,the levels of IL-6 and CRP of the TNS122 group and the Imipenem group were higher than the M166 group.The differences were statistically significant(P<0.05).BUN levels of mice at different time points:There was no significant difference in BUN between the each two groups(P>0.05).Conclusions:1.In vitro the novel antibacterial peptide G3KL subtypes M166 and TNS122have antibacterial activity for the ESBLs.E.c;2.M166,TNS122 can reduce the mortality of abdominal infection of mice,and have a survival protection effect;3.M166,TNS122 can reduce the levels of inflammatory factors IL-6 and CRP for the mice infected with abdominal cavity,and reduce the inflammatory response;4.M166 and TNS122 may have toxic and side effects on liver function in mice.