Severe cases of COVID-19 can now be detected at an early stage. Researchers at the University of Zurich have identified the first biomarker capable of reliably predicting which patients will develop severe symptoms. This may help improve the treatment of severe cases of COVID-19.
Most people infected with SARS-CoV-2 have no or only mild symptoms. However, some patients suffer from severe, life-threatening cases of COVID-19 and require intensive medical care and a ventilator to help them breathe. Many of these patients either die of the disease or suffer significant long-term health consequences. To identify and treat these patients at an early stage, a kind of ‘measuring stick’ is needed – predictive biomarkers capable of recognizing those at risk of developing severe COVID-19.
First biomarker to predict disease severity
A team led by Professor Burkhard Becher of the Institute for Experimental Immunology at the University of Zurich, in collaboration with researchers from Tübingen, Toulouse and Nantes, has now discovered such a biomarker – the number of natural killer T cells in the blood. These cells are a type of white blood cell and are part of the early immune response. “The number of natural killer T cells in the blood can be used to predict severe cases of COVID-19 with a high degree of certainty – even on a patient’s first day in hospital,” says Burkhard Becher.
Targeted therapy through precise immunopathogenesis
The new biomarker test helps clinicians decide what organizational and treatment measures should be taken for patients with COVID-19, such as transfer to the ICU, frequency of oxygen measurements, type of therapy and the start of treatment. “Predictive biomarkers are very helpful in making these decisions. They help clinicians provide patients with severe symptoms the best possible care, ”says Stefanie Kreutmair, first author of the study. “Our findings also allow the study of new therapies against COVID-19.”
With the help of high technology
The rapid deterioration in the health of patients with COVID-19 is caused by an overreaction of the body’s immune system. “The body produces small proteins called cytokines at a much higher rate, which leads to a ‘cytokine storm’ and triggers massive inflammation. Immune cells invade the lungs, where they disrupt gas exchange, ”explains Becher. To detect immune cells and cytokines in patient samples, researchers at UZH used high-dimensional cytometry. This technology allows researchers to characterize numerous surface and intracellular proteins in millions of individual cells and process them using computer algorithms.
SARS-CoV-2 specific immune signature deciphered
Many other pathogens besides SARS-CoV-2 can cause pneumonia – and therefore trigger an immune response. The immune response elicited by COVID-19 has been extensively studied, but the exact nature of the immune response to SARS-CoV-2 has not, to date, been clear. To characterize this response, the researchers also analyzed blood samples from patients with severe pneumonia caused by a pathogen other than the novel coronavirus. By comparing the immune responses of COVID-19 patients to those in the control group, the researchers were able to determine the unique characteristics of the SARS-CoV-2 immune response.
“The immune responses to various pneumonias are very similar and are part of the body’s general inflammatory response, as often seen in intensive care patients. When it comes to COVID-19, however, T cells and natural killer cells display a unique behavior and describe a kind of pattern in the immune system – the COVID-19-specific immune signature, ”Becher explains.
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