Antimicrobial peptide Mastoparan X has good activity against Escherichia coli in vitro and alleviates its pathogenicity in mice

Background: Escherichia coli is a facultative anaerobic bacterium that exists in the gastrointestinal tract of humans and animals and can cause diarrhoea and enteritis. The antimicrobial peptide MPX is extracted from wasp venom and has a strong bactericidal effect on many bacteria. The aim of this study was to explore the mechanism by whichMPX kills E. coli in vitro, its effect on IPEC-J2 cells apoptosis and barrier function, and itstherapeutic effect on E. coli infection in mice. Methods: : In this study, the effects of MPX on E. coli were investigated in vitro , at cellular level and in vivo . Results: : The results showedthat the minimum inhibitory concentration (MIC) of MPX against E. coli was 31.25 µg/mL. Scanning electron microscopy results showed that the bacteria became smaller in size and the contents leaked after treatment with MPX. In addition, theNPN, PI and DiSC3(5) results showed that the fluorescence intensity was positively correlated with MPX. MPX significantly inhibited E. coli biofilm formation. Moreover, MPX effectively alleviated IPEC-J2 cell apoptosis, regulated ZO-1, Occludin, and Claudin-1 through theRac1 pathway. H&E staining results further found that MPX could alleviate the pathological damage in intestine. qRT–PCR results showed that MPX could increase the mRNA expression of TFF3 in the jejunum and colon. Conclusions: : This study is the first time to explore the mechanism by which MPX kills E. coli in vitro , laying the foundation for the development of new drugs for the treatment of bacterial infections.