Circulating cardiomyocyte-derived extracellular vesicles reflect cardiac injury during systemic inflammatory response
Hargita Hegyesi1, Éva Pallinger2, Szabina Mecsei2
1Department of Genetics, Cell- and Immunobiology, Semmelweis University, Budapest, Hungary. hegyesi.hargita@med.semmelweis-univ.hu.
Insights
Cardiomyocyte-derived extracellular vesicles (EVs) enter circulation and increase during cardiac injury. Their elevated levels in blood, identified using green fluorescent protein (GFP) tagging, reflect systemic inflammation and heart damage.
Area of Science:
- Cardiovascular Biology
- Extracellular Vesicle Research
- Inflammation and Immunity
Background:
- Extracellular vesicles (EVs) are released under cellular stress, but their origin and circulation from cardiomyocytes are unclear.
- The diagnostic potential of cardiomyocyte-derived EVs in reflecting cardiac injury remains unexplored.
Purpose of the Study:
- To determine if cardiomyocyte-derived EVs reach systemic circulation.
- To investigate if circulating EV levels correlate with cardiac injury in a model of systemic inflammation.
Main Methods:
- Utilized green fluorescent protein (GFP)-expressing transgenic mice with cardiomyocytes as the source of EVs.
- Isolated EVs from plasma and cardiomyocyte cultures, analyzing concentration and size via Nanoparticle Tracking Analysis.
- Monitored GFP-positive EVs using flow cytometry and assessed cardiac function through echocardiography.
Main Results:
- Lipopolysaccharide (LPS) administration induced systemic inflammation, cardiomyopathy, and elevated cardiac injury markers (TNFα, GDF-15, cardiac troponin I).
- Circulating small and medium EVs increased in LPS-treated mice.
- Significantly higher numbers of cardiomyocyte-derived GFP-positive EVs were detected in circulation post-LPS treatment, containing cardiac troponin I and PYGM.
Conclusions:
- This study provides the first direct evidence of cardiomyocyte-derived EVs in circulation.
- Increased circulating cardiac-derived EVs serve as a biomarker for cardiac injury during LPS-induced systemic inflammation (SIRS).
Abstract:
The release of extracellular vesicles (EVs) is increased under cellular stress and cardiomyocyte damaging conditions. However, whether the cardiomyocyte-derived EVs eventually reach the systemic circulation and whether their number in the bloodstream reflects cardiac injury, remains unknown. Wild type C57B/6 and conditional transgenic mice expressing green fluorescent protein (GFP) by cardiomyocytes were studied in lipopolysaccharide (LPS)-induced systemic inflammatory response syndrome (SIRS). EVs were separated both from platelet-free plasma and from the conditioned medium of isolated cardiomyocytes of the left ventricular wall. Size distribution and concentration of the released particles were determined by Nanoparticle Tracking Analysis. The presence of GFP + cardiomyocyte-derived circulating EVs was monitored by flow cytometry and cardiac function was assessed by echocardiography. In LPS-treated mice, systemic inflammation and the consequent cardiomyopathy were verified by elevated plasma levels of TNFα, GDF-15, and cardiac troponin I, and by a decrease in the ejection fraction. Furthermore, we demonstrated elevated levels of circulating small- and medium-sized EVs in the LPS-injected mice. Importantly, we detected GFP+ cardiomyocyte-derived EVs in the circulation of control mice, and the number of these circulating GFP+ vesicles increased significantly upon intraperitoneal LPS administration (P = 0.029). The cardiomyocyte-derived GFP+ EVs were also positive for intravesicular troponin I (cTnI) and muscle-associated glycogen phosphorylase (PYGM). This is the first direct demonstration that cardiomyocyte-derived EVs are present in the circulation and that the increased number of cardiac-derived EVs in the blood reflects cardiac injury in LPS-induced systemic inflammation (SIRS).
