Roles of Mitochondrial Dysfunction in Maleic Acid‐induced Acute Kidney Injury

Abstract

BackgroundAcute kidney injury (AKI) is a growing public health burden globally. Mitochondrial function plays the key role in the progress of AKI. Maleic acid (MA) has been proofed to induce various renal dysfunctions include AKI. In our previous study, there were MA affinity proteins, including ATP synthase subunits, mitochondrial glyceraldehydes‐3‐phosphate, been identified in human kidney proximal tubular cells (HK2 cells) (1). The goal of this study is investigating mitochondria roles in AKI using our MA‐induced mitochondrial dysfunction AKI modelMethodsFor the in vitro study, HK2 cells were induced with MA with 2mM and 5mM for 24 hours separately. For the in vivo study, we induced AKI in c57BL/6 mice by intraperitoneal MA injection with 400mg/kg body weight and sacrificed after 24 hours of injection.ResultsWe found that the MA treatment induces HK2 cell death with dosage responsive in MA 2mM (p<0.01) and MA 5mM (p<0.001). Serum BUN and creatinine were all increased (p<0.05) in the MA‐treated mice when compared to the vehicle treated mice. The histological analysis showed increased tubule injury index Jablonski score (p<0.001), tubular dilatation areas (p<0.001) and greater casting area (p<0.001) in MA‐treated as compared to vehicle‐treated mice. AKI marker, Kidney Injury Molecule‐1 was increased (p<0.001) in MA‐treated as compared to vehicle‐treated mice. The flow cytometry analysis indicated increased apoptosis (p<0.001), cell reactive oxidative stress (ROS) (p<0.001), mitochondrial ROS (p<0.001), and decreased mitochondria membrane potential (p<0.001) in MA‐treated compared to vehicle‐treated in vitro. In O2 respiration, MA‐treated HK2 cells decreased the capacity of electro transfer system activity (p<0.001) and nonphosphorylating LEAK respiration (electron flow coupled to proton pumping to compensate for proton leaks) (p<0.001), compared to vehicle‐treated. There was also significantly decreased ATP production in MA‐treated compared to vehicle‐treated in vitro. In mitochondria structure, the cristae of mitochondria were lost in MA‐treated compared to vehicle‐treated under transmission electron miscroscope examination. The gene expression was confirmed with the significant lower of ATPase6 in MA‐treated compared to vehicle‐treated. Moreover, renal mitochondrial protein of ATP subunit C (p<0.05) were significantly decreased in MA‐treated compared to vehicle treated in vivo.ConclusionThere results demonstrated that MA‐induced AKI through targeting renal proximal tubular mitochondrial ATP Synthase. Mitochondria may represent a novel therapeutic target for MA‐induced AKI.Support or Funding Information