Sepsis-associated severe interleukin-6 storm in critical coronavirus disease 2019

Abstract

Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by a novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Due to its high transmission and the lack of effective vaccines or antiviral drugs, this novel infectious disease has changed the social and economic lives of human beings in unprecedented ways. Most COVID-19 infections are mild or even asymptomatic, but the poor prognosis of severe or critically ill patients is still a major challenge. The host immune response is a key determinant for viral clearance. Accumulating evidence suggests that typical lymphopenia and cytokine release syndrome are two features that predict poor prognosis in COVID-19. In particular, the levels of blood interleukin-6 (IL-6) are closely correlated with the severity of COVID-19 and have been considered an independent biomarker for predicting poor prognosis. However, the sources and dynamics of increased IL-6 in COVID-19 patients remain largely unknown. Here, we reported that septic shock or sepsis was strongly associated with a dramatic rise in blood IL-6 in critical cases and further demonstrated maximal IL-6 levels over a certain threshold as a powerful biomarker for fatal outcomes in COVID-19 patients.