Activated immune cells in the coronary arteries of the heart release fatal "NETs"

(Vienna, 27th March 2015) Special immune cells - neutrophilic granulocytes - have multiple functions designed to fight bacteria in the body. One of them is the formation of neutrophil extracellular traps (NETs). A group of researchers from the MedUni Vienna has now discovered that NETting plays a key role in the severity of a heart attack. This finding could be implemented into the treatment of cardiac arrests.

More than half of the white blood cells in the human body are neutrophilic granulocytes. They have multiple functions designed to fight harmful bacteria in the body. One of them is the formation of neutrophil extracellular traps (NETs). During this process, neutrophilic granulocytes are able to expel chromatin (= DNA) from their cell nucleus into the extracellular space which expands like a net. These NETs are bactericidal, cytotoxic and promote inflammation and thrombosis. This effectively captures and fights bacteria. However, these properties also make NETs harmful in many ways and even allow them to cause damage to organs.

In a study carried out in the Department of Cardiology and the Department of Dermatology at the MedUni Vienna within the Vienna General Hospital, in cooperation with the Institute of Biochemistry at the Justus Liebig University in Giessen, scientists have been able to demonstrate that neutrophils of heart attack patients are specifically activated locally in the coronary arteries by bacteria from the oral mucosa, producing NETs. Clots in the coronary vessels are made up of NETs. NETs correlate directly with the extent of the infarct, in other words, the more NETs, the more extensive the myocardial infarction.

DNase as a possible treatment
The researchers were also able to measure the enzyme DNase, which is able to break up NETs, in the plasma of coronary patients. DNase activity has a direct, negative relationship to the volume of NETs, in other words where there is more DNase activity, the number of NETs formed is lower. It was also discovered that DNase activity has a significantly negative correlation to the size of the infarction, which means it can protect against heart attacks. In vitro, blood clots from patients' coronary vessels were quickly dissolved with DNase.

Service: Circulation Research
Coronary Neutrophil Extracellular Trap Burden and DNase Activity in ST-Elevation Acute Coronary Syndrome are Predictors of ST-Segment Resolution and Infarct Size.  Andreas Mangold, Sherin Alias, Thomas Scherz, Thomas Hofbauer, Johannes Jakowitsch, Adelheid Panzenboeck, Daniel Simon, Daniela Laimer, Christine Bangert, Andreas Kammerlander, Julia Mascherbauer, Max-Paul Winter, Klaus Distelmaier, Christopher Adlbrecht, Klaus T Preissner and Irene M Lang http://www.ncbi.nlm.nih.gov/pubmed/25547404