#FEMSmicroBlog: Host extracellular vesicles to keep microbes in check

01-05-2021

One might think that nasty pathogens like Mycobacterium tuberculosis, Cryptococcus neoformans, or Yersinia pestis have the upper hand when confronting their hosts. However, humans are able to defend themselves against the vast majority of pathogenic challenges. The short review “Host-derived extracellular vesicles for antimicrobial defense” published in microLife presents one emerging aspect of host defense: the production of antimicrobial extracellular vesicles. Matthew Blango explains for the #FEMSmicroBlog how recent work on these small cellular containers is changing the way we think about pathogenesis and the future diagnosis and treatment of infectious diseases. #FascinatingMicrobes

 

Microbial fights within and around us

Microbes dominate our world, thriving in environments that plants and animals call home, as well as more extreme environments such as deep-sea thermal vents or even ice-covered polar regions. In nearly every case, life for microbes is challenging, and winning access to nutrients is key. Hence, it is no surprise that microbes have evolved sophisticated strategies to cope with these conditions.

For example, microbes produce toxins or chemical deterrents to dissuade competitors from a nutrient source. In other cases, pathogenic microbes employ a range of tactics to outmaneuver their hosts. In response, the host has evolved an immune system exquisitely tuned to detect and prevent microbial infections.

Over the past few decades, experimental evidence showed that extracellular vesicles participate in these information exchanges in various systems. This includes communication strategies between different microbes and also between host and pathogen.

Hosts and pathogens constantly exchange information

Extracellular vesicles are small lipid bilayer containers, reminiscent of a balloon filled with a “cargo”. They are capable of delivering molecular cargoes between cells. The review “Host-derived extracellular vesicles for antimicrobial defense” published in microLife highlights recent advances in understanding the antimicrobial potential of this diverse group of extracellular containers.

These containers can be killer vesicles sent between microbes during the competition for resources. Other extracellular vesicles are released from human immune cells to inhibit the growth of bacteria like Staphylococcus aureus or fungi like Aspergillus fumigatus. The review further describes the ability of plants to hinder fungal and oomycete infections with small RNA-filled vesicles and discusses the unanswered questions that will drive the field in the coming years.

Extracellular vesicles with antimicrobial cargo are routinely produced as a response to microbial competitors or in response to infection of a host
Antimicrobial functions of extracellular vesicles from Brakhage et al. (2021) in microLife.

 

Extracellular vesicles hold vast potential for therapeutics

Extracellular vesicles represent exciting therapeutics due to their stability and specificity. This is similar to sending chocolate croissants to your favorite scientist (highly recommended!). You wouldn’t just throw the croissants out your window. Instead, you would put them in a box to protect them from the local wildlife and affix a shipping label to direct them to your scientist.

Extracellular vesicles provide similar protection to their cargo. Molecules on the surface of the vesicle act as a molecular shipping label to help the container find the right target cell. Therapeutically, the ability to specifically deliver antimicrobial cargo to a pathogen is quite intriguing and could revolutionize the treatment of infectious diseases.

Extracellular vesicles provide protection to their cargo, while molecules on their surface act as molecular labels to help find the right target cell.

 

Researchers are now working on defining the molecules required to deliver host antimicrobial extracellular vesicles to pathogens. Based on this, they aim to create designer synthetic antimicrobial extracellular vesicles against our most dangerous adversaries.

Additional efforts to eavesdrop on the molecular exchange facilitated by extracellular vesicles during infection will hopefully improve our ability to diagnose infections that are often difficult to detect. As presented in the review, extracellular vesicles will likely play an important role in diagnosing and treating important human infections in the future.

 

About the author of this blogMatthew Blango

Matthew Blango is a Junior Research Group Leader at the Leibniz Institute for Natural Product Research and Infection Biology: Hans Knöll Institute (Leibniz-HKI) in Jena, Germany. The research in his group focuses on understanding how host and fungal RNA is regulated and trafficked during infections, with the long-term goal of providing targets for the development of RNA-based diagnostics and therapeutics against fungal pathogens.

About this blog section

The section #FascinatingMicrobes for the #FEMSmicroBlog explains the science behind a paper and highlights the significance and broader context of a recent finding. One of the main goals is to share the fascinating spectrum of microbes across all fields of microbiology.

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