Circulating extracellular vesicle content reveals de novo DNA methyltransferase expression as a molecular method to predict septic shock

ABSTRACT

Extracellular vesicles (EVs) are mRNA-containing cell fragments shed into circulation during pathophysiological events. DNA methyltransferases (DNMT1, DNMT3A, and DNMT3B) regulate gene expression by modifying DNA methylation and altering transcription. Sepsis is a systemic insult resulting in vascular dysfunction, which can lead to shock and death. We analysed plasma from ICU patients for circulating EV numbers, defined as particles isolated from 1 mL plasma at 21,000xg, and DNMTs mRNA content as prognostic markers of septic shock. Compared to plasma from critically ill patients with or without sepsis, plasma from septic shock patients contained more EVs per mL, expressed as total DNMTs mRNAs over 5 days, and more individual DNMT mRNAs at each day. A comparison of EV-DNMT1 (maintenance methylation) with EV-DNMT3A+DNMT3B (de novo methylation) expression correlated highly with severity, and EVs from septic shock patients carried more total DNMT mRNAs and more DNMT3A+DNMT3B mRNAs than control or sepsis EVs. Total plasma EVs also correlated with sepsis severity. EV-DNMT mRNAs load, when coupled with total plasma EV number, may be a novel method to diagnose septic shock upon ICU admittance and offer opportunities to more precisely intervene with standard therapy or other targeted interventions to regulate EV release and/or specific DNMT activity.

KEYWORDS:

• Sepsis
• DNA methyltransferases (DNMT)
• extracellular vesicles (EVs)
• diagnostic marker
• epigenetics
• septic shock

Acknowledgments

This study was supported in part with funding from a WVCTSI grant (GM104942) as start-up to TDE, West Virginia State Startup Funds and NHLBI R01HL109481 to CBM, UL1RR025755 to JW from the National Centre for Advancing Translational Science, the Stroke CoBRE grant GM109098 and WVCTS grant GM104942 for use of the NanoSight NS 300, and the WVCTS GM104942 and WV-INBRE GM103434 grants for the ARIA III at the WVU Flow Cytometry Core Facility. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Centre for Advancing Translational Sciences or the National Institutes of Health.

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Funding

This work was supported by the National Heart, Lung, and Blood Institute [HL109581]. WVCTSI grant (GM104942) as start-up to TDE, West Virginia State Startup Funds and NHLBI R01HL109481 to CBM, UL1RR025755 to JW from the National Centre for Advancing Translational Science, the Stroke CoBRE grant GM109098 and WVCTS grant GM104942 for use of the NanoSight NS 300, and the WVCTS GM104942 and WV-INBRE GM103434 grants for the ARIA III at the WVU Flow Cytometry Core Facility.