Human neutrophil peptide 1 promotes immune sterilization in vivo by reducing the virulence of multidrug-resistant Klebsiella pneumoniae and increasing the ability of macrophages.

By studying the expression in patients and cell modeling in vitro, antimicrobial peptides for Klebsiella were screened. Killing curve and membrane permeability experiments are used to study the antibacterial effect of antimicrobial peptides in vitro. Cytotoxicity related indicators including lipopolysaccharide (LPS), Capsule polysaccharide (CPS) and outer membrane protein expression were measured. Intranasal inoculation of Pneumoconiosis was used to construct a mouse infection model, and the survival rate and cytokine expression level were tested. Human Neutrophil Peptide 1 (HNP-1) showed significant antibacterial effect, which improved the permeability of the outer membrane of K. pneumoniae. Moreover, HNP-1 decreased LPS, CPS content and outer membrane proteins. K. pneumoniae infection decreased antimicrobial peptide, oxidative stress and autophagy-related genes, while HNP-1 increased these genes. After co-culture with macrophages, the endocytosis of macrophages is enhanced and the bacterial load is greater in K. pneumoniae + peptide group. Besides, higher levels of pp38 and pp65 in K. pneumoniae + peptide group. HNP-1 rescued the cytotoxicity induced by K. pneumoniae. Survival rate is significantly improved after K. pneumoniae treated by HNP-1. All cytokines in the peptide group were significantly higher. HNP-1 promotes immune sterilization by reducing the virulence of multidrug-resistant K. pneumoniae and increasing the ability of macrophages. This article is protected by copyright. All rights reserved.