Researchers Point to IL-26 as Biomarker of Severe COVID-19

A study published by researchers in Sweden indicates that systemic interleukin (IL)-26 is a possible biomarker of severe COVID-19. The findings were published in Frontiers in Immunology. According to the authors at Sweden’s Karolinska Institutet, high IL-26 levels correlate with an exaggerated inflammatory response that signifies severe cases of the disease. IL-26 has antiviral and antibacterial effects and mobilizes immune cells to fight bacterial infections in the lungs as well as chronic respiratory disease. However, the researchers said they conducted the study because the role of IL-26 in COVID-19 has not been thoroughly investigated. There is also a need to know more about these underlying immunological mechanisms in order to find better treatments as well as improved diagnostics. To conduct the study, researchers recruited 49 patients who had been hospitalized with SARS-CoV-2-infection, 44 of whom had severe symptoms and needed oxygen therapy. The patients were recruited at a hospital in Stockholm from June 2020 to January 2021. A control group of 27 healthy individuals was also recruited during the same period. The researchers then measured levels of IL-26 protein and other inflammatory compounds in the blood. The concentration of IL-26 correlates with those of the neutrophil-mobilizing cytokines IL-8 and TNFα, the authors said. Healthy controls had much lower levels of IL-26. In addition, "the increase in blood IL-26 correlates with enhanced surface expression of the “don’t eat me” signal CD47 on blood neutrophils isolated from patients with acute COVID-19," the researchers wrote. In addition, the blood concentration of IL-26 correlates with that of increased lactate dehydrogenase, a marker of tissue damage, and decreased mean corpuscular hemoglobin, which signals hematological abnormalities in COVID-19; both of those are linked with severe disease. The higher IL-26 levels were also linked with cytokine storm, another signal of severe COVID-19. The authors said the results are promising but need further study with a larger patient sample. Reference Increased IL26 associates with markers of hyperinflammation and tissue damage in patients with acute COVID19. Cardenas EI, Ekstedt S, Piersiala K, et al Front Immunol. Published online November 17, 2022. doi:10.3389/fimmu.2022.1016991