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Kidney Week

Abstract: TH-PO111

Lowering of Pathological Asymmetric Dimethyl Arginine by a Novel Dimethylarginine Dimethylaminohydrolase Improves Kidney Function After Ischemia-Reperfusion Injury

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Lee, Young, Indiana Center for Biomedical Innovation, Indianapolis, Indiana, United States
  • Mehrotra, Purvi, Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Basile, David P., Indiana University School of Medicine, Indianapolis, Indiana, United States
  • Singh, Jaipal, Indiana University School of Medicine, Indianapolis, Indiana, United States
Background

Asymmetric dimethyl arginine (ADMA) is an endogenously produced inhibitor of nitric oxide synthase (NOS) which contributes to endothelial dysfunction, endothelial to mesenchymal transition, reduced organ perfusion, and fibrosis. High levels of ADMA are produced in patients with kidney disease and in response to renal ischemia which may contribute to the pathogenesis of kidney disease. In this study, we have investigated ADMA lowering and therapeutic efficacy of novel dimethylarginine dimethylaminohydrolase (DDAH) in the setting of acute kidney injury produced by ischemia-reperfusion (I/R).

Methods

DDAH gene was cloned and expressed in E. coli to generate recombinant DDAH (rDDAH). In vivo circulating DDAH activity was determined at various times after i.v. administration to rats using a colorimetric assay. I/R injury in rats was produced by renal artery ligation for 40 min followed by reperfusion in male Sprague-Dawley rats. The effect of I/R injury on renal DDAH was measured by changes in DDAH mRNA and enzymatic activity. rDDAH was post-translationally modified by PEGylation (M-DDAH) to achieve prolonged in vivo activity. The effect of M-DDAH on I/R injury in rats was determined by changes in creatinine and histology.

Results

DDAH mRNA expression and activity rapidly declined following renal I/R injury in rats, and were ~20% of the values in sham-operated controls within 6 hours (P<0.05). Reduction in DDAH was accompanied by increased ADMA in the kidney from 0.14±0.05 uM/mg protein at baseline to 0.42±0.09 uM/mg protein at 6h (P<0.05). Native rDDAH was rapidly cleared within 15 min after i.v. administration to rats, whereas PEGylated DDAH (M-DDAH) exhibited 15-fold greater in vivo half-life than the native rDDAH. M-DDAH treatment attenuated the degree of renal injury in the I/R model as indicated by reduced serum creatinine (2.23±0.38 mg/dL I/R vs 1.15±0.17 mg/dL M-DDAH, P<0.05) and the degree of renal tubular damage.

Conclusion

Our studies are first to synthesize a novel pharmacologically viable DDAH molecule which lowered ADMA in rats. M-DDAH significantly improved renal function in a model of I/R in rats, suggesting that M-DDAH may offer a new therapeutic approach for improving endothelial function in the setting of AKI.