Exploring the role of circulating exosome-derived transfer RNA fragments in patients with ischemic stroke

Abstract Objectives : to investigate exosome-derived transfer RNAs (tRNAs) in the plasma of patients in the chronic phase of ischemic stroke (IS). tRFs may be disease biomarkers, especially for disorders linked to hypoxic and extracellular stress. Material and methods : We assessed samples from ten patients who had ischemic stroke (IS), collected them six months after the ictus, and compared to samples obtained from ten controls. We used small RNA sequencing for tRNA identification and quantification. Results : We found that the most abundant class of tRFs identified in the patients’ samples were 3′ fragments (37.7%). Most interestingly, we found increased levels of two tRFs in patients, namely Phe- GAA (p = 0.0146) and Leu- TAG (p = 0.0331). These two fragments originate from mitochondrial tRNAs and may be related to mechanisms leading to abnormal regulation of cellular energy, DNA transcription, and oxidative stress. We also identified decreased tRNA-Gly and tRNA-Val derivatives in patients. Furthermore, we found that the expression signature of tRNA Phe- GAA differentiates patients from controls with an area under the receiver operating characteristics (ROC) curve (AUC) = 0.78. Conclusions: Our results indicate differential expression of circulating exosome-derived tRFs in the chronic stages of IS. The tRFs with the greatest differences in expression identified in this study may be linked to the mechanisms leading to disease, most likely related to underlying risk factors that may persist after the acute event. Thus, we provide suggestive evidence that tRFs may assist in risk stratification for individuals with increased susceptibility to IS.