High-throughput Screening For Peptides Targeting A Pathogenic Bacterium And Its Application In The Treatment Of Sepsis

Sepsis is a systemic inflammatory response syndrome caused by pathogen infections.Sepsis can further develop into septic shock,multiple organ failure(MOF),which is the prominent cause for the mortality of patients in intensive care units(ICU).Pathogen infections are the fundamental cause for sepsis.Clinical evidence suggests that controlling pathogen infections untimely and ineffectively is a major cause of sepsis death.Therefore,early and effective inhibition or killing pathogen is the key to prevent and treat sepsis.Various pathogens are involved in the pathogenesis of sepsis,but different pathogens have different sensitivities to antibacterial drugs,organ distributions as well as other biological behaviors,which leads to different clinical manifestation and prognosis.Therefore,it is urgent to establish individualized medical strategy targeting a specific pathogen for the prevention and treatment of sepsis.At present,there are many kinds of antibacterial drugs in the market.Lacking of targeted antibacterial activity and low concentration within the lesion had led to low efficiency,high toxicity,side effects and multidrug resistance.Contemporary,the designs of antibacterial drugs have been developed into the era of "precise targeted drug design"along with the priming of precision medicine.In order to improve the antibacterial effects and reduce the side effects of antimicrobial agents,development of targeted antimicrobial drug delivery system will be a novel strategy of prevention and treatment of sepsis in the future which can thoroughly kill pathogen for its precise targeted antibacterial activity.In order to study targeting antibacterial strategy for sepsis,the research had successfully isolated and identified pathogen(E.coli)from blood of mice with sepsis.And the pathogen(E.coli)was took as targeted research bacterium.The 4.4 G DNA sequence data of peptides binding to pathogen was obtained exactly and quickly by phage display and high-throughput sequencing.The frequency and rank of peptides were acquired by bioinformatics.The bias of peptides distribution was found in the phage library.For the purpose of eliminating the influence of phage library bias on the research,the frequency of peptides combined with the bacterium were adjusted by the frequency of library peptides.And then the relationship between the frequency and binding force was studied.The result showed shat the correlation(p>0.05)was low before adjusting,whereas the correlation(p<0.05)had been improved after adjusting.Thus,adjusting could increase the opportunity to obtain the specific and high affinity peptides binding to bacterium.Peptides binding to pathogen had been chosen to construct fusion proteins(BPLL37)with LL37.Not only early bacteriostatic activity of VTK-LL37 was superior to LL37,but the biofilm inhibition of VTK-LL37 was superior to LL37 in vitro.Which may be related with the targeting peptide of VTK-LL3 7.Meanwhile,VTK-LL3 7 could improve sepsis mice survival through inhibiting pathogen growth,decreasing HMGB1 expression and alleviating important organs lesion of mice.In a word,targeted antimicrobial peptides of our research could raise antimicrobial efficiency and survival of mice with sepsis.This research provided technical scheme for targeted killing pathogen and a novel strategy for individual precise medicine of sepsis.