Interleukin-17: Could it be a key player in COVID-19 infection severity?

Background: Exaggerated cytokines response with release of proinflammatory cytokines i.e., cytokine storm has been described with COVID-19 infection. This cytokine storm plays an important role in lung injury and development of acute respiratory distress syndrome (ARDS) in severely ill patients. One important cytokine that participates in the cytokine storm is interleukin (IL) -17. Aim of the study: Assess serum levels of IL-17 in COVID-19 patients and its correlation with disease severity. Methods: Sixty-six COVID-19 infected patients (33 moderate cases and 33 severe cases) and 20 healthy controls (HCs) were included in the study. Serum IL-17 level was assessed by ELISA in patients and HCs. Results: IL-17 levels were remarkably higher in patients' groups compared to HCs and also there was statistically significant difference between the patients’ subgroups (p < /em><0.0001). IL-17 was correlated with different laboratory and clinical parameters. At a cut-off value of >25 ng/ml, IL-17 was able to differentiate between the patients’ groups and HCs with 93.94% sensitivity and 65% specificity. Conclusion: Serum IL-17 level correlates to more severe disease courses in COVID 19 patients. Higher levels were associated with devastating outcomes.