Abstract
Background Endotoxin-associated acute kidney injury (AKI), a disease characterized by marked oxidative stress and inflammation disease, is a major cause of mortality in critically ill patients. Mitochondrial fission and pyroptosis often occur in AKI. However, the underlying biological pathways involved in endotoxin AKI remain poorly understood, especially those related to mitochondrial dynamics equilibrium disregulation and pyroptosis. Previous studies suggest that heme oxygenase- (HO-) 1 confers cytoprotection against AKI during endotoxic shock, and PTEN-induced putative kinase 1 (PINK1) takes part in mitochondrial dysfunction. Thus, in this study, we examine the roles of HO-1/PINK1 in maintaining the dynamic process of mitochondrial fusion/fission to inhibit pyroptosis and mitigate acute kidney injury in rats exposed to endotoxin. Methods An endotoxin-associated AKI model induced by lipopolysaccharide (LPS) was used in our study. Wild-type (WT) rats and PINK1 knockout (PINK1KO) rats, respectively, were divided into four groups: the control, LPS, Znpp+LPS, and Hemin+LPS groups. Rats were sacrificed 6 h after intraperitoneal injecting LPS to assess renal function, oxidative stress, and inflammation by plasma. Mitochondrial dynamics, morphology, and pyroptosis were evaluated by histological examinations. Results In the rats with LPS-induced endotoxemia, the expression of HO-1 and PINK1 were upregulated at both mRNA and protein levels. These rats also exhibited inflammatory response, oxidative stress, mitochondrial fission, pyroptosis, and decreased renal function. After upregulating HO-1 in normal rats, pyroptosis was inhibited; mitochondrial fission and inflammatory response to oxidative stress were decreased; and the renal function was improved. The effects were reversed by adding Znpp (a type of HO-1 inhibitor). Finally, after PINK1 knockout, there is no statistical difference in the LPS-treated group and Hemin or Znpp pretreated group. Conclusions HO-1 inhibits inflammation response and oxidative stress and regulates mitochondria fusion/fission to inhibit pyroptosis, which can alleviate endotoxin-induced AKI by PINK1.
Highlights
Endotoxin is a common cause of morbidity and mortality of critically ill patients in clinical practice [1]
To prove the relationship between heme oxygenase- (HO-)1 and PINK1 in endotoxin acute kidney injury (AKI), we examined the expression of Heme oxygenase-1 (HO-1) and PINK1 in LPS-induced AKI
The expression of HO-1 and PINK1 proteins and mRNA was increased when WT rats were treated with LPS
Summary
Endotoxin is a common cause of morbidity and mortality of critically ill patients in clinical practice [1]. Endotoxin-associated acute kidney injury (AKI), a disease characterized by marked oxidative stress and inflammation disease, is a major cause of mortality in critically ill patients. In this study, we examine the roles of HO-1/PINK1 in maintaining the dynamic process of mitochondrial fusion/fission to inhibit pyroptosis and mitigate acute kidney injury in rats exposed to endotoxin. In the rats with LPSinduced endotoxemia, the expression of HO-1 and PINK1 were upregulated at both mRNA and protein levels These rats exhibited inflammatory response, oxidative stress, mitochondrial fission, pyroptosis, and decreased renal function. After upregulating HO-1 in normal rats, pyroptosis was inhibited; mitochondrial fission and inflammatory response to oxidative stress were decreased; and the renal function was improved. HO-1 inhibits inflammation response and oxidative stress and regulates mitochondria fusion/fission to inhibit pyroptosis, which can alleviate endotoxin-induced AKI by PINK1
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