Abstract
Bacterial extracellular vesicles are membranous ultrastructures released from the cell surface. They play important roles in the interaction between the host and the bacteria. In this work, we show how extracellular vesicles produced by four different serotypes of the important human pathogen, Streptococcus pneumoniae, are internalized by murine J774A.1 macrophages via fusion with the membrane of the host cells. We also evaluated the capacity of pneumococcal extracellular vesicles to elicit an immune response by macrophages. Macrophages treated with the vesicles underwent a serotype-dependent transient loss of viability, which was further reverted. The vesicles induced the production of proinflammatory cytokines, which was higher for serotype 1 and serotype 8-derived vesicles. These results demonstrate the biological activity of extracellular vesicles of clinically important pneumococcal serotypes.
Highlights
Pathogenic microorganisms have developed numerous strategies to survive within their hosts, defending from the immune system and evading its action
We investigated whether extracellular vesicles (EV) from the reference S. pneumoniae R6 non-encapsulated strain and three other encapsulated strains, belonging to clinically relevant serotypes, transferred their cargo to infected cells and the mechanism by which this occurred
We incubated murine J774A.1 macrophages with EVs and assessed the presence of pneumococcal proteins within cells at different times by immunoblot of macrophage cell lysates using an anti-bacterin serum. These experiments revealed that the EV content was transferred to the macrophages as early as 30 min after incubation (Figure 1A)
Summary
Pathogenic microorganisms have developed numerous strategies to survive within their hosts, defending from the immune system and evading its action. EVs of diseasecausing bacteria are important factors in host–pathogen interplay, as they can increase the pathogenicity of microbes by transferring virulence factors into host cells and exert cytotoxic effects [1,3] In their cargo, EVs transport proteins, and other molecules such as metabolites and nucleic acids, which can play important roles in microbe-microbe interaction, biofilm formation or acquisition of resistance to antibiotics [4,5]. EVs transport proteins, and other molecules such as metabolites and nucleic acids, which can play important roles in microbe-microbe interaction, biofilm formation or acquisition of resistance to antibiotics [4,5] They can have a beneficial effect by triggering an immune response in the host that induces cytokines to fight against infections caused by the bacteria that release them [6]. These results demonstrate that EVs from clinically relevant pneumococcal serotypes are able to induce an immune response, as previously described for reference strains
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
