Shedding Light on tRNA-Derived Fragment Repertoire in Facs Blood Cells

tRNA-derived fragments function as markers additionally to playing the role key of signalling molecules in a number of disorders. It is known that the repertoire of these molecules differs greatly in different cell types and varies depending on the physiological condition. The aim of our research was to compare the pattern of tRF expression in the main blood cell types and to determine how the composition of these molecules changes during COVID-19-induced cytokine storm. Erythrocytes, monocytes, lymphocytes, neutrophils, basophils, and eosinophils from control donors and patients with severe COVID-19 were obtained by fluorescence sorting. We extracted RNA from FACS sorted cells and performed NGS of short RNAs. The composition of tRNA-derived fragments was analysed applying a semi-custom bioinformatic pipeline. In this study, we assessed the length and type distribution of TRFs and reported the 150 most prevalent TRF sequences across all cell types. Additionally we demonstrate a significant (p<0.05, fold change>16) change in the pattern of tRFs in erythrocytes (21 downregulated, 12 upregulated), monocytes (53 downregulated, 38 upregulated) and lymphocytes (49 upregulated) in patients with severe COVID-19. Thus, different blood cell types exhibit a significant variety of TRFs and react to cytokine storm by dramatically changing their differential expression patterns. We suppose that the observed phenomenon occurs due to the regulation of nucleotide modifications and alterations in activity of various Rnases.