Soluble urokinase plasminogen activator receptor (suPAR) in bronchoalveolar fluid and blood in critically ill patients—a prospective cohort study

Abstract

IntroductionSoluble urokinase plasminogen activator receptor (suPAR) is a biologically active protein and increased levels are associated with worse outcomes in critically ill patients. suPAR in bronchoalveolar fluid (BALF) may be helpful to differentiate between types of acute respiratory distress syndrome (ARDS) and may have potential for early detection of fungal infection.MethodsWe prospectively investigated levels of suPAR in BALF and serum in critically ill patients who underwent bronchoscopy for any reason at the ICU of the Department of Internal Medicine, Medical University of Graz, Graz, Austria.ResultsSeventy-five patients were available for analyses. Median age was 60 [25th–75th percentile: 50–69] years, 27% were female, and median SOFA score was 12 [11–14] points. Serum suPAR levels were significantly associated with ICU mortality in univariable logistic regression analysis. There was no correlation between BALF and serum suPAR. Serum suPAR was higher in ARDS patients at 11.2 [8.0–17.2] ng/mL compared to those without ARDS at 7.1 [3.7–10.1] (p < 0.001). BALF-suPAR was significantly higher in patients with evidence of fungal lung infection compared to patients without fungal infection both in the general cohort (7.6 [3.2–9.4] vs 2.5 [1.1–5.3], p = 0.013) and in the subgroup of ARDS (7.2 [3.1–39.2] vs 2.5 [1.0–5.2], p = 0.022). All patients were classified as putative/probable invasive aspergillosis.ConclusionWe found significant higher levels of serum suPAR in ARDS patients compared to those not fulfilling ARDS criteria. Serum and BALF-suPAR were significantly higher in those patients with evidence for invasive pulmonary aspergillosis. These findings may suggest testing this biomarker for early diagnosis of fungal infection in a greater cohort.