Scientists have discovered strange clots and immune system changes in the blood of long Covid patients, which could lead to new treatments to cure the persistent condition.
Most people recover completely from Covid-19 infection after a short bout of cold, sore throat, or cough and fever, but many patients may suffer a clutch of symptoms related to the virus, termed long Covid.
Studies have identified these symptoms to include fatigue, brain fog, body pain, and breathlessness.
However, the exact reason for these persisting symptoms remains unclear.
Now, scientists have identified underlying interactions in long Covid patients between tiny clots in their blood called microclots and changes to immune system cells called neutrophils that could explain the condition.
Microclots are abnormal clumps of blood-clotting proteins circulating in a patient’s bloodstream, which were first found in the blood samples of Covid-19 patients.
Researchers also found that in long Covid patients, that a type of white blood immune cells called neutrophils undergo a special change that causes them to expel their DNA to form filamentous structures.
These structures then get embedded with cell-dissolving enzymes to form what are called neutrophil extracellular traps (NETs) that rapidly capture and kill pathogens.
Researchers suspect an interaction between microclots and NETs in some Covid patients leads to a cascade of system-wide changes that ultimately cause long Covid.
Microclots may be causing excessive NET formation, which contributes to a range of inflammatory and blood-clotting conditions that exacerbate and prolong Covid-like symptoms, scientists say.
They conduced a structural analysis of microclots and NETs in the plasma of long Covid patients and compared them to those in healthy patients.
Researchers found significantly higher signs of microclots and NETs in patient samples.
The microclots also appeared larger in size among patients, the study noted.
“This finding suggests the existence of underlying physiological interactions between microclots and NETs that, when dysregulated, may become pathogenic,” said Alain Thierry, an author of the study from the Montpellier Cancer Research Institute in France.
The interaction between microclots and NETs could be making these tiny clots more resistant to being broken down by the body’s natural clot-breaking process, and promoting their persistence in circulation, said Resia Pretorius, another author of the study.
This could be contributing to chronic blood vessel complications seen in long Covid patients, she explained.
“We suggest that higher NETs formation might promote the stabilisation of microclots in the circulation, potentially leading to deleterious effects which contribute causally to the long Covid syndrome,” scientists wrote in the study published in the Journal of Medical Virology.
The findings provide new explanation for long Covid symptoms and may lead to the development of targeted treatment strategies, researchers say.
