fg-4592 and Reperfusion-Injury

Ischaemia-reperfusion (I/R) is one of the main factors of acute kidney injury (AKI). mitochondrial damage pathway are important features of I/R induced-acute kidney injury (IRI-AKI). Hypoxia-inducible factor (HIF) expression in renal tubule segments is up-regulated during AKI. Herein, we investigated the role of FG-4592 in a mouse model of IRI-AKI to confirm whether FG-4592 is beneficial in AKI. We found that pretreatment with FG-4592 significantly ameliorated renal function and renal histological damage in mice after IRI. Furthermore, these results suggest that pretreatment with FG-4592 significantly reduced the tubular cells apoptosis (decreased TUNEL-positive cells, Bax, caspase12 levels), attenuated mitochondrial damage (increased ATPβ, PPARγ, mitochondrial DNA copy number, and decreased cytoplasmic cytochrome C), and alleviated DNA damage after IRI. In conclusion, pretreatment with FG-4592 may effectively prevent kidney from IRI possibly by via diminishing tubular cells injuries and protection of mitochondrial damage pathway. These results further validate that FG-4592 may be an effective drug in the clinical treatment of IRI-AKI.

Topics: Acute Kidney Injury; Animals; Apoptosis; Glycine; Ischemia; Isoquinolines; Kidney; Mice; Mice, Inbred C57BL; Reperfusion; Reperfusion Injury

During the reperfusion phase of ischemia‑reperfusion injury, reactive oxygen species (ROS) production aggravates the course of many diseases, including acute kidney injury. Among the various enzymes implicated in ROS production are the enzymes of the cytochromes P450 superfamily (CYPs). Since arylhydrocarbon receptor (AhR) controls the expression of certain CYPs, the involvement of this pathway was evaluated in reperfusion injury. Because AhR may interact with the nuclear factor erythroid 2‑related factor 2 (Nrf2) and the hypoxia‑inducible factor‑1α (HIF‑1α), whether such an interaction takes place and affects reperfusion injury was also assessed. Proximal renal proximal tubular epithelial cells were subjected to anoxia and subsequent reoxygenation. At the onset of reoxygenation, the AhR inhibitor CH223191, the HIF‑1α activator roxadustat, or the ferroptosis inhibitor α‑tocopherol were used. The activity of AhR, Nrf2, HIF‑1α, and their transcriptional targets were assessed with western blotting. ROS production, lipid peroxidation and cell death were measured with colorimetric assays or cell imaging. Reoxygenation induced ROS production, lipid peroxidation and cell ferroptosis, whereas CH223191 prevented all. Roxadustat did not affect the above parameters. Reoxygenation activated AhR and increased CYP1A1, while CH223191 prevented both. Reoxygenation with or without CH223191 did not alter Nrf2 or HIF‑1α activity. Thus, AhR is activated during reoxygenation and induces ROS production, lipid peroxidation and ferroptotic cell death. These detrimental effects may be mediated by AhR‑induced CYP overexpression, while the Nrf2 or the HIF‑1α pathways remain unaffected. Accordingly, the AhR pathway may represent a promising therapeutic target for the prevention of reperfusion injury.

Topics: alpha-Tocopherol; Animals; Azo Compounds; Basic Helix-Loop-Helix Transcription Factors; Cell Hypoxia; Cells, Cultured; Cytochrome P-450 CYP1A1; Epithelial Cells; Ferroptosis; Glycine; Hypoxia-Inducible Factor 1, alpha Subunit; Isoquinolines; Kidney Tubules, Proximal; Lipid Peroxidation; Mice; Models, Biological; NF-E2-Related Factor 2; Oxygen; Pyrazoles; Reactive Oxygen Species; Receptors, Aryl Hydrocarbon; Reperfusion Injury

Acute kidney injury (AKI) is a known risk factor for the development of chronic kidney disease (CKD), with no satisfactory strategy to prevent the progression of AKI to CKD. Damage to the renal vascular system and subsequent hypoxia are common contributors to both AKI and CKD. Hypoxia-inducible factor (HIF) is reported to protect the kidney from acute ischemic damage and a novel HIF stabilizer, FG4592 (Roxadustat), has become available in the clinic as an anti-anemia drug. However, the role of FG4592 in the AKI-to-CKD transition remains elusive. In the present study, we investigated the role of FG4592 in the AKI-to-CKD transition induced by unilateral kidney ischemia-reperfusion (UIR). The results showed that FG4592, given to mice 3 days after UIR, markedly alleviated kidney fibrosis and enhanced renal vascular regeneration, possibly via activating the HIF-1α/vascular endothelial growth factor A (VEGFA)/VEGF receptor 1 (VEGFR1) signaling pathway and driving the expression of the endogenous antioxidant superoxide dismutase 2 (SOD2). In accordance with the improved renal vascular regeneration and redox balance, the metabolic disorders of the UIR mice kidneys were also attenuated by treatment with FG4592. However, the inflammatory response in the UIR kidneys was not affected significantly by FG4592. Importantly, in the kidneys of CKD patients, we also observed enhanced HIF-1α expression which was positively correlated with the renal levels of VEGFA and SOD2. Together, these findings demonstrated the therapeutic effect of the anti-anemia drug FG4592 in preventing the AKI-to-CKD transition related to ischemia and the redox imbalance.

Topics: Acute Kidney Injury; Animals; Antioxidants; Disease Models, Animal; Fibrosis; Glycine; Isoquinolines; Kidney; Male; Mice, Inbred C57BL; Pharmaceutical Preparations; Regeneration; Renal Insufficiency, Chronic; Reperfusion Injury; Vascular Endothelial Growth Factor A