Hepatic dimethylarginine-dimethylaminohydrolase1 is reduced in cirrhosis and is a target for therapy in portal hypertension - PubMed (original) (raw)

Hepatic dimethylarginine-dimethylaminohydrolase1 is reduced in cirrhosis and is a target for therapy in portal hypertension

Rajeshwar P Mookerjee et al. J Hepatol. 2015 Feb.

Erratum in

Corrigendum to "Hepatic dimethylarginine-dimethylaminohydrolase1 is reduced in cirrhosis and is a target for therapy in portal hypertension" [J Hepatol 62 (2015) 325-331].
Mookerjee RP, Mehta G, Balasubramaniyan V, Mohamed FEZ, Davies N, Sharma V, Iwakiri Y, Jalan R. Mookerjee RP, et al. J Hepatol. 2017 Nov;67(5):1124. doi: 10.1016/j.jhep.2017.08.004. J Hepatol. 2017. PMID: 28893453 No abstract available.

Abstract

Background & aims: Portal hypertension is characterized by reduced hepatic eNOS activity. Asymmetric-dimethylarginine (ADMA), an eNOS inhibitor, is elevated in cirrhosis and correlates with the severity of portal hypertension. Dimethylarginine dimethylaminohydrolase-1 (DDAH-1) is the key enzyme metabolizing hepatic ADMA. This study characterized DDAH-1 in cirrhosis, and explored hepatic DDAH-1 reconstitution through farnesoid X receptor (FXR) agonism and DDAH-1 gene therapy.

Methods: DDAH-1 immunohistochemistry was conducted on human cirrhosis and healthy liver tissue. Subsequently, sham-operated or bile-duct-ligated (BDL) cirrhosis rats were treated with the FXR agonist obeticholic acid (OA, 5 mg/kg) or vehicle for 5 days. Further, animals underwent hydrodynamic injection with DDAH-1-expressing plasmid or saline control, which resulted in the following groups: sham+saline, BDL+saline, BDL+DDAH-1-plasmid. Portal pressure (PP) measurements were performed. Plasma ALT was measured by COBAS INTEGRA, DDAH-1 expression by qPCR and Western blot, eNOS activity by radiometric assay.

Results: Immunohistochemistry and Western-blotting confirmed hepatic DDAH-1 was restricted to hepatocytes, and expression decreased significantly in cirrhosis. In BDL rats, reduced DDAH-1 expression was associated with elevated hepatic ADMA, reduced eNOS activity and high PP. OA treatment significantly increased DDAH-1 expression, reduced hepatic tissue ADMA, and increased liver NO generation. PP was significantly reduced in BDL+OA vs. BDL+vehicle (8±1 vs. 13.5±0.6 mmHg; p<0.01) with no change in the mean arterial pressure (MAP). Similarly, DDAH-1 hydrodynamic injection significantly increased hepatic DDAH-1 gene and protein expression, and significantly reduced PP in BDL+DDAH-1 vs. BDL+saline (p<0.01).

Conclusions: This study demonstrates DDAH-1 is a specific molecular target for portal pressure reduction, through actions on ADMA-mediated regulation of eNOS activity. Our data support translational studies, targeting DDAH-1 in cirrhosis and portal hypertension.

Keywords: ADMA; DDAH-1; Nitric oxide; Portal hypertension.

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Figures

Figure 1

1a: top panel- Hepatic DDAH-1 is located within the cytoplasm of hepatocytes of human liver; DDAH-1 levels are markedly decreased in cirrhotic liver (right side image) compared to a healthy liver (left side image). Similarly, in the BDL rat model of cirrhosis, DDAH-1 is predominantly located in the hepatocyte cell fraction from rat liver as compared with the non-hepatocyte cell (NPC) fraction (1b: left panel), and DDAH-1 protein levels are markedly reduced in BDL rat liver compared to sham (1c: centre panel). By contrast, hepatic DDAH-2 protein levels are increased in BDL rat liver compared to sham (1d: right panel).

Figure 1

Figure 2

The FXR agonist Obeticholic Acid (OA): induces DDAH-1 mRNA expression in HepG2 cells in vitro (2a: left panel), and when used in vivo it significantly increases hepatic DDAH-1 protein expression in BDL rats (2b: centre panel), and significantly reduces portal pressure in BDL rats (2c: centre right panel). eNOS activity was significantly reduced in BDL rats compared to sham animals. This reduction in eNOS activity is restored to sham levels after OA therapy (2d: right panel)

Figure 3

Hydrodynamic gene delivery of DDAH-1 expressing plasmid into BDL rats leads to increased DDAH-1 mRNA (3a: left panel), and protein (3b: centre panel), and decreased portal pressure (3c: right panel) relative to control plasmid.

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Hepatic dimethylarginine-dimethylaminohydrolase1 is reduced in cirrhosis and is a target for therapy in portal hypertension - PubMed (original) (raw)