Editorial: Platelet and megakaryocyte dysfunctions in infectious diseases, 2023, Alice Assinger et al

Platelets constantly patrol the vasculature to prevent blood loss upon injury in a process termed haemostasis. Upon rapid adhesion to sub-endothelial matrixes, platelets become activated and recruit further platelets to form aggregates which, after stabilizaton by the fibrin mesh generated via the coagulation system, ultimately seal the injured vessels. Apart from their central role in haemostasis, platelets also regulate vascular integrity as well as tissue repair mechanisms and are crucially involved in immune-regulation. It is therefore not surprising that platelets play an important role in infectious diseases.

More evidence emerges as to their unexpected and experimentally poorly explored roles. On the edge between beneficial or harmful activities, platelets are capable of harbouring infectious viral and non-viral pathogens, therefore acting as Trojan horses for pathogen dissemination. They can directly participate and actively interfere with immune responses to these pathogens, allowing antigen presentation or serve as shelters for these pathogens to protect them against immune surveillance. Platelets are thus an invaluable physiological cellular model for fundamental research on host-pathogen interaction such as antigen presentation, pathogen endocytosis, and exocytosis of virulence factors or inflammatory mediators, as well as cell-to-cell transfer of microorganisms.

https://www.frontiersin.org/articles/10.3389/fimmu.2023.1175200/full