Renal Ischemia/Reperfusion Early Induces Myostatin and PCSK9 Expression in Rat Kidneys and HK-2 Cells

Abstract

During visceral interventions, the transient clampage of supraceliac aorta causes ischemia/reperfusion (I/R) in kidneys, sometime resulting in acute renal failure; preclinical studies identified redox imbalance as the main driver of I/R injury. However, in humans, the metabolic/inflammatory responses seem to prevail on oxidative stress. We investigated myostatin (Mstn) and proprotein convertase subtilisin/kexin type 9 (PCSK9), proatherogenic mediators, during renal I/R. Compared to sham-operated animals, the kidneys of rats who had experienced ischemia (30 min) had higher Mstn and PCSK9 expression after 4 h of reperfusion. After 24 h, they displayed tubular necrosis, increased nitrotyrosine positivity, and nuclear peroxisome proliferator-activated receptor gamma coactivator-1alpha relocation, markers of oxidative stress and mitochondria imbalance. Mstn immunopositivity was increased in tubuli, while PCSK9 immunosignal was depleted; systemically, PCSK9 was higher in plasma from I/R rats. In HK-2 cells, both ischemia and reperfusion enhanced reactive oxygen species production and mitochondrial dysfunction. H2O2 upregulated Mstn and PCSK9 mRNA after 1 and 3.5 h, respectively. Accordingly, ischemia early induced Mstn and PCSK9 mRNA; during reperfusion Mstn was augmented and PCSK9 decreased. Mstn treatment early increased PCSK9 expression (within 8 h), to diminish over time; finally, Mstn silencing restrained ischemia-induced PCSK9. Our study demonstrates that renal I/R enhances Mstn and PCSK9 expression and that Mstn induces PCSK9, suggesting them as therapeutic targets for vascular protection during visceral surgery.