Platelet mitochondrial transfer via extracellular vesicles modulates neutrophil phenotype and function
Harriet E Allan1, Nicola Dark2, Paul Vulliamy3
1Centre for Immunobiology, Blizard Institute, Queen Mary University of London, Faculty of Medicine and Dentistry, London, UK.
Background:
Platelet activation causes the release of extracellular vesicles, of which a small proportion contain respiratory competent mitochondria. Mitochondria are integral for energy production and in the regulation of apoptotic pathways; however, the existence of extracellular mitochondria highlights a potential new role in intercellular communication. Indeed, mitochondrial transfer has gained significant research interest in recent years, highlighting mechanisms through which cellular function and metabolism may be augmented.
Objectives:
This study aimed to characterize changes in neutrophil function and phenotype that occur because of interactions with mitochondria-positive or mitochondria-negative platelet extracellular vesicles.
Methods:
Platelet extracellular vesicle subpopulations were separated based on mitochondrial content using cell sorting and subsequently incubated with isolated neutrophils. Alterations in surface receptor repertoire were analyzed by flow cytometry, and functional characterization was performed by immunofluorescence, flow cytometry, and Seahorse XF metabolic flux assays.
Results:
Platelet extracellular vesicles containing mitochondria interacted with and were internalized by neutrophils, subsequently increasing their metabolic capacity. These interactions promoted changes in neutrophil receptor repertoire, indicative of enhanced neutrophil activation, adhesion, and migration pathways. The internalization of platelet mitochondria rendered neutrophils unable to subsequently engulf bacteria, demonstrating reduced phagocytic capacity, but enhancesd the formation of neutrophil extracellular traps, both alone and in the presence of additional stimuli.
Conclusion:
Our findings show that platelet mitochondria released in extracellular vesicles can be transferred into neutrophils, altering their metabolic function and activity. This research highlights an important role for platelet mitochondria as intercellular communicators and modulators of inflammatory and immune responses.
