The Plasma Level of Proprotein Convertase FURIN in Patients with Suspected Infection in the Emergency Room: A Prospective Cohort Study

There is an increasing need for novel biomarkers that enable better diagnostic and prognostic stratification of patients with suspected infection. A proprotein convertase enzyme FURIN is upregulated upon immune cell activation, and it promotes infectivity by cleaving and activating pathogens. In this study, we determined FURIN levels in plasma using ELISA from 537 patients that were admitted to emergency room with suspected infection. Patients were sorted to high- and low-level FURIN groups with a cut-off level of 370 pg/ml. The study cohort included five diagnostic groups: Group 1, no systemic inflammatory response syndrome (SIRS, n = 59 patients); Group 2, bacterial infection without SIRS (n = 67); Group 3, SIRS, but no bacterial infection (n = 308); Group 4, sepsis without organ failure (n = 308); and Group 5, severe sepsis (n = 49). Statistically significant associations were not found between the plasma level of FURIN and the prevalence of sepsis (P = 0.957), diagnostic group of a patient (P = 0.737) or the bacteria in blood culture (P = 0.499). Additionally, the concentration of FURIN did not predict the severity or case fatality of the infectious disease. However, statistically significant associations were found between high plasma level of FURIN and diagnosed rheumatic disease (P < 0.001) as well as with the prevalence of non-smokers (P = 0.034). Thus, albeit the plasma level of FURIN does not predict the severity of infectious disease, it may be of use in the diagnostics of autoimmune diseases.