Antimicrobial peptide mpx alleviates the lethal attack of Escherichia Coli in mice

Abstract

Escherichia coli is an important zoonotic pathogen causing intestinal diseases. In recent years, due to the unreasonable use of antibiotics, the drug resistance of bacteria has been increasing, and the proportion of multi-drug resistant strains has also been rising, which directly threatens the health of animals and humans. 80% of E. coli are multi-drug resistant strains, with strong resistance to aminoglycosides, sulfonamides, tetracyclines, and chloramphenicol. E. coli is extremely harmful and difficult to control. Therefore, there is an urgent need to find new antibacterial drugs that against E. coli infection and not easy to develop drug resistance. Antimicrobial peptides are a type of small molecule peptides that can resist the invasion of pathogenic microorganisms into the body. They are an important part of the innate immune system. With their small molecular weight, good water solubility, and resistance to resistance, they are considered the best alternative to antibiotics and become a research hotspot in recent years. The antimicrobial peptide MPX was isolated from wasp venom and had better antibacterial activity against both Gram-positive and Gram-negative bacteria. Studies have found that MPX had better bactericidal activity against E. coli in vitro. However, whether MPX also has better bactericidal activity in mice still unknown. In this study, the results found that E. coli infected mice loss of appetite, diarrhea, and grouping together, while MPX treatment significantly alleviated these symptoms. The results of autopsy found that the intestinal congestion, bleeding, thinning of the intestinal wall, yellow viscous fluid in the intestinal cavity, congestion of the lungs, necrosis in the liver, congestion and bleeding of the spleen, and MPX treatment effectively relieved the above symptoms. The qRT-PCR results found that MPX could increase the mRNA expression of the antibacterial protein TFF3 in the jejunum and colon, and reduce the expression of the antibacterial protein Remlβ and REG3γ in the jejunum and colon. H&E staining results further found that MPX could alleviate the pathological damage of mouse intestines and organs caused by E. coli infection. The above results show that MPX has good bactericidal activity against E. coli infection in mice, providing an important reference for the screening of drugs for the clinical treatment of E. coli infection.