According to researchers at Sweden’s Karolinska Institutet, patients with acute COVID-19 infection had greater levels of the cytokine IL-26 in their blood. Furthermore, elevated IL-26 levels are associated with an enhanced inflammatory response, indicating that the condition is serious. The findings, published in the journal Frontiers in Immunology, show that IL-26 might be a biomarker for severe COVID-19.
SARS-CoV-2 vaccines have been beneficial in lowering the number of severe COVID-19 infections. However, the advent of novel virus strains, restricted vaccine dissemination, and waning immunity are issues that are driving scientists to develop more effective therapies for the disease. “In order to identify effective therapies, we need to learn more about the underlying immunological pathways.”
There is also a need for improved diagnostics in COVID 19-patients,” says Eduardo Cardenas, postdoc researcher at the Institute of Environmental Medicine, Karolinska Institutet, and principal author of the new pilot study.
The researchers have tried, for the first time, to ascertain whether immune signalling via the cytokine interleukin-26 (IL-26) is involved in severe COVID-19.
“We already know that IL-26 is engaged in mobilising immune cells that combat bacterial infections in the lungs and also in chronic respiratory disease in humans,” says the study’s last author Anders Linden, consultant and professor at the Institute of Environmental Medicine, Karolinska Institutet. “What’s more, IL-26 has antiviral and antibacterial effects.”
The authors selected 49 individuals who had been hospitalised with SARS-CoV-2 infection, 44 of whom had severe symptoms and required oxygen treatment, to explore how the molecule is implicated in COVID-19. From June 2020 to January 2021, patients were recruited in a hospital in Stockholm. During the same time span, a control group of 27 healthy people was also recruited. The researchers next examined IL-26 protein levels as well as other inflammatory chemicals in the blood.
“We can show for the first time that blood levels of the cytokine IL-26 are much higher in patients with COVID-19 than in healthy controls,” says Dr Cardenas.
The researchers could also detect that the rise was linked to a cytokine storm, which is an extreme and deadly inflammatory response associated with severe COVID-19 instances. “Our discovery gives us a potential biomarker for severe COVID-19, but given the antiviral effects of IL-26, we may also have identified a new therapeutic target,” says Professor Linden.
The results, according to Dr. Cardenas, are intriguing but preliminary and suggest additional research with a larger patient group. “Such a research is in the works and will provide further information on the clinical utility of monitoring IL-26 in COVID patients, such as whether the levels indicate disease severity.”