The Effect of Oral Administration of the Antibacterial Peptide MPX on Intestinal Inflammation of Mice in Experimental Infection with Escherichia Coli Strain O157: H7

Abstract

Escherichia coli is a gram-negative bacterium, an intestinal pathogen that can cause intestinal inflammation. Antimicrobial peptides are a class of small molecule peptides, which has good antibacterial activity against a variety of gram-positive and negative bacteria. In this regard, the authors aimed to study the effect of the antimicrobial peptide MPX, which was administered orally, on the intestinal wall of mice infected with the intestinal barrier function, which were infected with E. coli. Synthesis and purification of the antimicrobial peptide MPX (H-INWKGIAAMAKKLL-NH2) was performed by Jier Sheng Hua (Shanghai, China). Mass spectrometry and liquid chromatography (HPLC) were used for this purpose. Escherichia Coli (O157: H7 ATCC43889) was isolated from human faeces in which haemolytic uremic syndrome was reported. Solid LB agar (Solarbio, China) was used to isolate enterohemorrhagic E. coli. The culture was obtained from the Chinese Institute of Veterinary Drug Control (Beijing, China). The results of necropsy found that using of an orally administered MPX could alleviate the damage of E. coli to the liver, spleen, and the lungs were less affected. According to H&E results in case of an orally administered MPX group considerably relieved duodenum and organs on day 7 and day 28. qRT-PCR results showed orally administered MPX could reduce the inflammation-related factors in the mRNA expression of IL-2 and IL-6 and TNF-α on day 7 and day 28. In addition, orally administered MPX could significantly increase them RNA expression of tight junction proteins Occludin and Zo-1 on day 7 and day 28. The results of immune histochemistry further showed that an orally administered MPX could increase the mRNA expression of MUC2 in jejunum. The above results showed that orally administered MPX could alleviate the attack of E. coli on the intestinal tract of mice, relieve intestinal inflammation, and improve the intestinal barrier function. This study lays a theoretical foundation for adding antimicrobial peptides to food. In orally administered MPX authors can see reducing the mRNA expression of inflammation-related factors, thereby alleviating the intestinal inflammation caused by E. coli infection in mice. Authors can add that orally administered MPX shows an increase in mRNA expression of tight junction protein in intestines and improves the intestinal barrier function. This study lays the foundation for adding antimicrobial peptides to food to relieve inflammation and improve barrier function in clinical practices