Soluble CD25 is increased in patients with sepsis-induced acute kidney injury

Aim Sepsis has been shown to induce the expansion of CD4+CD25+ regulatory T cells (Tregs), and this paradoxical immune suppression has been suggested to be closely associated with the development of sepsis-induced organ dysfunction. In the present study, we aimed to investigate the possible link between immune suppression and the development of septic acute kidney injury (AKI). Methods We prospectively enrolled patients with a diagnosis of sepsis, with or without AKI and as well as patients with AKI but without sepsis. Serum and urine samples at the time of the diagnosis were collected to measure neutrophil gelatinase-associated lipocalin (NGAL), cytokines, and soluble CD25 (sCD25). Results Of the 82 patients enrolled, 44, 18, and 20 patients were classified into septic-AKI, sepsis-non AKI and non-septic AKI groups. There were no differences in the baseline characteristics in all three groups and the severity of infection in the two sepsis groups. Serum levels of interleukin (IL)-10 were significantly elevated in patients with septic-AKI compared to the other two groups. Serum and urine NGAL levels and the level of serum sCD25, a marker of regulatory T cells, were significantly elevated in patients with septic AKI group, indicating the potential association of paradoxical immune suppression and the development of septic-AKI. Conclusions These results suggest that immune suppression in sepsis may be closely linked to the development of AKI and that sCD25 or IL-10 may be useful as novel biomarkers for the development of septic AKI.