Acute Kidney Injury Associates with Long-Term Increases in Plasma TNFR1, TNFR2, and KIM-1: Findings from the CRIC Study

Background: Some markers of inflammation-TNF receptors 1 and 2 (TNFR1 and TNFR2)-are independently associated with progressive CKD, as is a marker of proximal tubule injury, kidney injury molecule 1 (KIM-1). However, whether an episode of hospitalized AKI may cause long-term changes in these biomarkers is unknown.

Methods: Among adult participants in the Chronic Renal Insufficiency Cohort (CRIC) study, we identified 198 episodes of hospitalized AKI (defined as peak/nadir inpatient serum creatinine values ≥1.5). For each AKI hospitalization, we found the best matched non-AKI hospitalization (unique patients), using prehospitalization characteristics, including eGFR and urine protein/creatinine ratio. We measured TNFR1, TNFR2, and KIM-1 in banked plasma samples collected at annual CRIC study visits before and after the hospitalization (a median of 7 months before and 5 months after hospitalization).

Results: In the AKI and non-AKI groups, we found similar prehospitalization median levels of TNFR1 (1373 pg/ml versus 1371 pg/ml, for AKI and non-AKI, respectively), TNFR2 (47,141 pg/ml versus 46,135 pg/ml, respectively), and KIM-1 (857 pg/ml versus 719 pg/ml, respectively). Compared with matched study participants who did not experience AKI, study participants who did experience AKI had greater increases in TNFR1 (23% versus 10%, P<0.01), TNFR2 (10% versus 3%, P<0.01), and KIM-1 (13% versus -2%, P<0.01).

Conclusions: Among patients with CKD, AKI during hospitalization was associated with increases in plasma TNFR1, TNFR2, and KIM-1 several months after their hospitalization. These results highlight a potential mechanism by which AKI may contribute to more rapid loss of kidney function months to years after the acute insult.