New findings could improve understanding of Long-COVID
Vienna (OTS) – A research team from MedUni Vienna shows in a study recently published in the renowned journal “Allergy” that COVID-19 leads to considerable long-term changes in the immune system, even in mild cases. The findings could help to better understand the long-term consequences of an infection with SARS-CoV-2.
As part of the study, the team led by lead authors Bernhard Kratzer and Pia Gattinger and study leaders Rudolf Valenta and Winfried Pickl (all from the Center for Pathophysiology, Infectiology and Immunology at MedUni Vienna) examined relevant immune parameters of 133 COVID-19 survivors and 98 people without the corresponding infection. Ten weeks and ten months after the illness, the number and composition of various immune cells as well as the growth factors in the blood of those who had recovered were analyzed, which play a crucial role in regulating cell growth, among other things. Since no COVID-19 vaccines were available when the research began in 2020, all participants were unvaccinated. This made it possible to examine the long-term effects of SARS-CoV-2 infections without the influence of vaccines.
Significant reduction of immune cells in the blood
“Not entirely unexpectedly, ten weeks after the infection, those who had recovered showed clear signs of immune activation in both T and B cells, in contrast to healthy subjects,” reports Winfried Pickl. In addition, the growth factors in the blood took on the pattern of an acute inflammatory process. When comparing them with the patient samples that had been obtained ten months after the COVID-19 disease, the researchers saw an unexpected picture: “Even after mild courses of the disease, we found a significant reduction in immune cells in the blood,” says Winfried Pickl, giving details from the study. In addition, the well-known drop in SARS-CoV-2-specific antibodies and an astonishing change in the growth factor patterns in the blood were observed. For those who have recovered from COVID-19, this means that their immune system may no longer respond optimally. This could provide an explanation for long COVID.
According to the researchers, the long-term consequences of the disease are probably caused by an infection and the resulting long-term impairment of the function of the bone marrow, the central production site of immune cells. “Our results provide a possible explanation that certain long-term consequences of COVID-19 could be related to the damage to the cellular immune system by SARS-CoV-2 and the apparently reduced maturation and/or emigration of immune cells from the bone marrow,” Winfried Pickl and Rudolf Valenta summarize the study results. This hypothesis forms the basis for further research to achieve a better understanding of the mechanisms underlying long COVID.
Publikation: Allergy
Differential decline of SARS-CoV-2-specific antibody levels, innate and adaptive immune cells and shift of Th1/inflammatory to Th2 serum cytokine levels long after first COVID-19.
Bernhard Kratzer, Pia Gattinger, Doris Trapin, Paul Ettel, Ulrike Körmöczi, Arno Rottal, Robert B. Stieger, Al Nasar Ahmed Sehgal, Melanie Feichter, Kristina Borochova, Inna Tulaeva, Katharina Grabmeier-Pfistershammer, Peter A. Tauber, Thomas Perkmann, Ingrid Fae, Sabine Wenda, Michael Kundi, Gottfried F. Fischer, Rudolf Valenta and Winfried F. Pickl.
DOI: 10.1111/all.16210
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