Angiopoietin-2 outperforms other endothelial biomarkers associated with severe acute kidney injury in patients with severe sepsis and respiratory failure

BACKGROUND: Endothelial dysfunction and injury is a major pathophysiologic feature of sepsis. Sepsis is also the most frequent cause of acute kidney injury (AKI) in critically ill patients. Though most studies of AKI in sepsis have focused on tubular epithelial injury, the role of endothelial dysfunction and injury is less well studied. The goal of this study was first to investigate whether endothelial dysfunction and injury biomarkers were associated with severe AKI in sepsis patients. The second goal was to determine the best performing biomarker for severe AKI and whether this biomarker was associated with severe AKI across different etiologies of sepsis and clinical outcomes. METHODS: We studied adults with severe sepsis and acute respiratory failure (ARF) enrolled in the prospective observational Validating Acute Lung Injury markers for Diagnosis (VALID) study. Plasma endothelial dysfunction and injury biomarkers, including angiopoietin-2, soluble vascular endothelial cadherin (sVE-cadherin), endocan and syndecan-1, were measured at study enrollment. Primary analysis focused on the association between endothelial biomarker levels with severe AKI (defined as Kidney Disease: Improving Global Outcomes [KDIGO] AKI stage 2 or 3), other organ dysfunctions (defined by Brussels organ failure scores), and comparison of pulmonary versus non-pulmonary sepsis. RESULTS: Among 228 sepsis patients enrolled, 141 developed severe AKI. Plasma levels of angiopoietin-2, endocan, sVE-cadherin, and syndecan-1 were significantly higher in sepsis patients with severe AKI compared to those without severe AKI. Among four endothelial biomarkers, only angiopoietin-2 was independently associated with severe AKI (odds ratio 6.07 per log increase, 95% CI 2.34–15.78, p < 0.001). Plasma angiopoietin-2 levels by quartile were significantly higher in sepsis patients with hepatic, coagulation, and circulatory failure. Plasma angiopoietin-2 levels were also significantly higher in patients with non-pulmonary sepsis compared to subjects with pulmonary sepsis. CONCLUSION: Among four biomarkers of endothelial dysfunction and injury, angiopoietin-2 had the most robust independent association with development of severe AKI in patients with severe sepsis and ARF. Plasma angiopoietin-2 levels were also associated with other organ dysfunctions, non-pulmonary sepsis, and death. These findings highlight the importance of early endothelial dysfunction and injury in the pathogenesis of sepsis-induced AKI.