Antimicrobial peptide MPX alleviates the lethal attack of Escherichia coli in mice

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. The antimicrobial peptide MPX was isolated from wasp venom and had better antibacterial activity against 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 is still unknown. This study found that E. coli infected mice lost appetite, diarrhea, and grouping together, while MPX treatment significantly alleviated these symptoms. The autopsy results 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 essential reference for screening drugs for the clinical treatment of E. coli infection.