Platelets and inflammation: insights from platelet non-coding RNA content and release in the Bruneck Study

Platelets contain non-coding RNAs (ncRNAs), and their measurement may complement aggregometry. In the community-based Bruneck Study (N = 338), we conducted over 2,700 aggregometry measurements and over 65,000 RT-qPCR measurements in platelet releasates, platelet-poor plasma and isolated platelets. We show agonist-specific, dose-dependent platelet ncRNA release that is inhibited by aspirin. Collagen induces the strongest release for most ncRNAs, while miR-150 is hyperresponsive to ADP and miR-21 is hyperresponsive to arachidonic acid. Inflammation and high leukocyte-derived RNA content in platelets correlate inversely with platelet aggregation and platelet ncRNA release after stimulation. This inverse correlation is not observed in aspirin users. Finally, we reveal that platelet-derived microRNAs and YRNAs are carried by proteins and readily released, while circular RNAs, long non-coding RNAs and messenger RNAs are carried by vesicles and preferentially retained. Our findings provide evidence that inflammation leads to platelet pre-activation in vivo resulting in platelet exhaustion ex vivo. Overall design: To identify lncRNA candidates, we conducted an additional RNA-Seq experiment in platelets collected from 4 healthy volunteers. RNA-seq results were validated by RT-qPCR measurements in platelet poor plasma, platelet-rich plasma (PRP) and platelets, and selected lncRNA candidates based on abundance (14 lncRNAs) as well as lncRNAs with the gene ontology term platelet.