Contrast‐Induced Acute Kidney Injury is Modulated by Circadian CLOCK/NRF2 Pathway

ABSTRACT Numerous kidney functions exhibit substantial circadian oscillations, such as renal blood flow, glomerular filtration rate, tubular reabsorption function, and erythropoietin production. The onset and the injury of acute kidney injury caused by ischemia or drugs also have a circadian rhythmicity. Contrast media are widely used in clinical diagnosis and treatment; however, whether contrast‐induced kidney injury exhibits a time‐of‐day dependence is unknown. We retrospectively analyzed 33 patients who underwent percutaneous coronary angiography and found that contrast induced the increase of serum neutrophil gelatinase‐associated lipocalin (NGAL) was more obvious in the group who underwent operation during 6:00 ~ 13:00 than the group who underwent operation between 13:00 ~ 20:00. In addition, C57BL/6J mice were injected with iohexol at different times. The kidney injury of mice injected with iohexol at ZT12 was more severe than that at ZT0, which was manifested in the increase of urinary KIM1 and NGAL, enhanced renal tubular lipid peroxidation, and increased tubular ferroptosis. Inhibition of ferroptosis could alleviate kidney injury induced by iohexol at ZT12. Mechanistically, we found that nuclear factor erythrocyte 2‐associated factor 2 (NRF2) expression has a 24‐h circadian rhythm and is directly regulated by CLOCK. Administration of 4‐Octyl itaconate at ZT12 to increase NRF2 expression could attenuate iohexol‐induced tubular ferroptosis. These findings provide a new insight into the pathology of contrast medium‐induced kidney injury, in which oscillatory NRF2 expression regulated by CLOCK contributes to the susceptibility of contrast‐induced kidney injury in a time‐of‐day–specific fashion.