Lactiplantibacillus plantarum Membrane Vesicles (MVs) Exhibit Immunomodulatory and Bactericidal Effects Against Escherichia coli and Salmonella Typhimurium

Abstract

The indiscriminate use of antibiotics has led to an increase in multidrug-resistant bacteria, necessitating the search for effective alternative therapies to reduce antimicrobial use. Lactic Acid Bacteria (LAB) have been explored as an alternative to antibiotics due to their multiple beneficial properties. These bacteria secrete membrane vesicles (MVs), key acellular components in combating pathogens. This study aimed to evaluate the effects of Lactiplantibacillus plantarum MVs co-cultured with Escherichia coli (MVsplE) or Salmonella Typhimurium (MVsplS) through inhibition assays using disk diffusion on agar plates, as well as their activation and cytokine expression in the RAW 264.7 macrophage cell line. The results showed that MVsplE and MVsplS were produced in greater quantity and size than non-co-cultured L. plantarum MVs (MVspl). Additionally, MVsplE and MVsplS exhibited a dose-dependent inhibitory effect on the growth of enteropathogenic bacteria. Furthermore, RAW 264.7 cells stimulated with these MVs demonstrated that the expression of IL-1{beta}, TNF-, and IL-10 depended on the enteropathogenic strain with which L. plantarum was previously co-cultured. Following a challenge with enteropathogenic bacteria, the MVs induced an immunomodulatory response. These findings demonstrate that L. plantarum MVs exert bactericidal and immunomodulatory effects against enteropathogenic bacteria, suggesting their potential use as an alternative treatment to antimicrobials. Author summaryLactic acid bacteria have been widely used as probiotics in therapies aimed at controlling or treating infectious diseases. However, it has been reported that these bacteria can replicate in immunocompromised individuals, as well as in clinically healthy individuals, potentially disrupting the intestinal microbiota and contributing to disease progression. In recent years, bacterial membrane vesicles (MVs) have emerged as promising alternatives, demonstrating superior effects compared to whole bacteria. These MVs are nanostructures derived from the cytoplasmic membrane and are released at various stages of bacterial growth. They contain multiple biomolecules and structural membrane proteins that enable them to exert biological effects on the host. Notably, MVs do not replicate, and therefore do not disturb the intestinal microbiota, leading to their classification as acellular probiotics. Research on these biological agents is crucial to minimizing risks to host health and developing alternative treatments for gastrointestinal diseases. In this study for first time, we demonstrated the bactericidal and immunomodulatory effects of Lactiplantibacillus plantarum MVs against Escherichia coli and Salmonella Typhimurium, supporting their potential as an effective alternative in the treatment of gastrointestinal infections.