Urinary exosomal CD26 is associated with recovery from acute kidney injury in intensive care units: a prospective cohort study

Objectives: Currently there is no validated method to predict renal reversal and recovery after acute kidney injury (AKI). As exosomes have the potential for AKI prognosis and CD26 is involved in the mechanisms in AKI, this study aims to investigate whether urinary exosomal CD26 is associated with renal-related outcomes and explore its prospect as a novel prognosis biomarker. Methods: This was a single-center, prospective cohort study. A total of 133 AKI patients and 68 non-AKI patients admitted to ICU in Qilu Hospital Shandong University from January 2017 to January 2018. Urine samples were collected at enrollment and the relative expression of CD26 (CD26 percentage) in urinary exosomes was examined, that was then categorized into a low-CD26 level and a high-CD26 level. Results: CD26 percentage was significantly lower in the AKI cohort than in the control cohort. Within the AKI cohort, a high-CD26 level was associated with lower incidence of major adverse kidney events within 90 days, but higher incidence of reversal within 28 days. In AKI survivors, a high-CD26 level had a 4.67-, 3.50- and 4.66-fold higher odds than a low-CD26 level for early reversal, recovery and reversal, respectively, after adjustment for clinical factors. Prediction performance was moderate for AKI survivors but improved for non-septic AKI survivors. Conclusions: Urinary exosomal CD26 is associated with renal reversal and recovery from AKI and is thus a promising prognosis biomarker.