Biomarker Signatures of Severe Acute Kidney Injury in a Critically Ill Cohort of COVID-19 and Non-COVID-19 Acute Respiratory Illness.

Kidney and lung injury are closely inter-related during acute respiratory illness, but the molecular risk factors that these organ injuries share are not well defined.

Objectives: We identified plasma biomarkers associated with severe acute kidney injury (AKI) during acute respiratory illness, and compared them to biomarkers associated with severe acute respiratory failure (ARF).

Design settings and participants: Prospective observational cohort study enrolling March 2020 through May 2021, at three hospitals in a large academic health system. We analyzed 301 patients admitted to an ICU with acute respiratory illness.

Main outcomes and measures: Outcomes were ascertained between ICU admission and day 14, and included: 1) severe AKI, defined as doubling of serum creatinine or new dialysis and 2) severe ARF, which included new or persistent need for high-flow oxygen or mechanical ventilation. We measured biomarkers of immune response and endothelial function, pathways related to adverse kidney and lung outcomes, in plasma collected within 24 hours of ICU admission. Severe AKI occurred in 48 (16%), severe ARF occurred in 147 (49%), and 40 (13%) patients experienced both. Two-fold higher concentrations of soluble tumor necrosis factor receptor-1 (sTNFR-1) (adjusted relative risk [aRR], 1.56; 95% CI, 1.24-1.96) and soluble triggering receptor on myeloid cells-1 (sTREM-1) (aRR, 1.85; 95% CI, 1.42-2.41), biomarkers of innate immune activation, were associated with higher risk for severe AKI after adjustment for age, sex, COVID-19, and Acute Physiology and Chronic Health Evaluation-III. These biomarkers were not significantly associated with severe ARF. Soluble programmed cell death receptor-1 (sPDL-1), a checkpoint pathway molecule, as well as soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule-1 (sVCAM-1), molecules involved with endothelial-vascular leukocyte adhesion, were associated with both severe AKI and ARF.

Conclusions and relevance: sTNFR-1 and sTREM-1 were linked strongly to severe AKI during respiratory illness, while sPDL-1, sICAM-1 and sVCAM-1 were associated with both severe AKI and ARF. These biomarker signatures may shed light on pathophysiology of lung-kidney interactions, and inform precision medicine strategies for identifying patients at high risk for these organ injuries.