Sepsis is the leading cause of death among critically ill patients in intensive care units (ICU), with a continuously increasing incidence and a high mortality rate.
Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. It arises when the body’s response to an infection (bacterial, fungal or viral) starts to injure its own tissues and organs. If this response is not recognised early and treated promptly it might lead to septic shock with multi-organ failure and death. You can find more information about sepsis at www.worldsepsisday.org.
Biomarkers for early detection
Early detection and intervention are critical to prevent the development of sepsis and severe events, as it is the most common cause of death in critically ill patients1.
Calprotectin is one of the earliest biomarkers for detection of the inflammatory response to infections2,3. The biomarker is predominantly expressed in neutrophil granulocytes, and it is released upon neutrophil activation in response to inflammation and infection.
Calprotectin’s benefits have been linked to the assessment of sepsis as the biomarker shows early diagnostic and predictive value4-10. In addition, calprotectin also gradually increases with disease severity in septic patients3,5. High calprotectin levels can be predictive for disease severity and clinical course of septic patients6,7 as well as mortality5,7-9 and can also improve classical risk scoring8. Early assessment is important to prevent sepsis, and calprotectin's predictive value can therefore play an important role.
Sepsis in COVID-19
SARS-CoV-2 has been described to cause viral sepsis11-17, and the reported diagnostic value of calprotectin in SARS-CoV-2 infection is related to the hyperinflammatory response in severe COVID-19 leading to viral sepsis14-25.
Neutrophils are upregulated and activated in COVID-19 patients as potential driver of disease severity26-28. Hospitalised COVID-19 patients with severe form of the disease show dysregulated immune response and induction of cytokine response (also called cytokine storm or hyperinflammation), which is a reaction very similar to bacterial sepsis15, 28-31.
Following the pathology of neutrophil activation and hyperinflammation in COVID-19, it is conceivable that calprotectin is a sensitive risk marker both in the viral infection resulting in severe COVID-19 and bacterial infections. Calprotectin’s diagnostic value lies within an early risk assessment and prediction of severe events and thereby aid to prevent the development sepsis.