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

ABSTRACT: 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.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.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).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.

SUBMITTER: Mookerjee RP

PROVIDER: S-EPMC4530584 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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

Mookerjee Rajeshwar P RP Mehta Gautam G Balasubramaniyan Vairappan V Mohamed Fatma El Zahraa Fel Z Davies Nathan N Sharma Vikram V Iwakiri Yasuko Y Jalan Rajiv R

Journal of hepatology 20140823 2

<h4>Background & aims</h4>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.<h4>Methods</h ...[more]

PMID: 25152204

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Project description:Background and aimsStudies in animal models have suggested that hepatic steatosis impacts on portal pressure, potentially by inducing liver sinusoidal endothelial dysfunction and thereby increasing intrahepatic resistance. Thus, we aimed to evaluate the impact of hepatic steatosis on hepatic venous pressure gradient (HVPG) in patients with chronic liver disease.Method261 patients undergoing simultaneous HVPG measurements and controlled attenuation parameter (CAP)-based steatosis assessment were included in this retrospective study.ResultsThe majority of patients had cirrhosis (n = 205; 78.5%) and n = 191 (73.2%) had clinically significant portal hypertension (CSPH; HVPG≥10mmHg). Hepatic steatosis (S1/2/3; CAP ≥248dB/m) was present in n = 102 (39.1%). Overall, HVPG was comparable between patients with vs. without hepatic steatosis (15.5±7.5 vs. 14.8±7.7mmHg; p = 0.465). Neither in patients with HVPG (<6mmHg; p = 0.371) nor in patients with mild portal hypertension (HVPG 6-9mmHg; p = 0.716) or CSPH (HVPG≥10mmHg; p = 0.311) any correlation between CAP and HVPG was found. Interestingly, in patients with liver fibrosis F2/3, there was a negative correlation between CAP and HVPG (Pearson's ρ:-0.522; p≤0.001). In multivariate analysis, higher CAP was an independent 'protective' factor for the presence of CSPH (odds ratio [OR] per 10dB/m: 0.92, 95% confidence interval [CI]:0.85-1.00; p = 0.045), while liver stiffness was associated with the presence of CSPH (OR per kPa: 1.26, 95%CI: 1.17-1.36; p≤0.001). In 78 patients, in whom liver biopsy was performed, HVPG was neither correlated with percentage of histological steatosis (p = 0.714) nor with histological steatosis grade (p = 0.957).ConclusionHepatic steatosis, as assessed by CAP and liver histology, did not impact on HVPG in our cohort comprising a high proportion of patients with advanced chronic liver disease. However, high CAP values (i.e. pronounced hepatic steatosis) might lead to overestimation of liver fibrosis by 'artificially' increasing transient elastography-based liver stiffness measurements.

Project description:BackgroundAlthough several risk factors for erectile dysfunction may be present in patients with cirrhosis, data on the actual prevalence and cause of erectile dysfunction is limited. The International Index of Erectile Function-5 (IIEF-5) is a well-validated survey to determine the presence and severity of erectile dysfunction in men. We assessed (i) the prevalence and severity of erectile dysfunction, and (ii) risk factors for erectile dysfunction in patients with cirrhosis.MethodsIn this prospective study, erectile dysfunction was defined as: absent (>21 IIEF-5-points), mild (12-21) and severe (5-11). Patients with overt hepatic encephalopathy, active alcohol abuse, extrahepatic malignancy, previous urologic surgery, previous liver transplantation and severe cardiac conditions were excluded.ResultsAmong n = 151 screened patients, n = 41 met exclusion criteria and n = 30 were sexually inactive. Thus, a final number of n = 80 male patients with cirrhosis were included. Patient characteristics: age: 53 ± 9 years; model for end-stage liver disease score (MELD): 12.7 ± 3.9; Child-Pugh score (CPS) A: 30 (37.5%), B: 35 (43.8%), C: 15 (18.7%); alcohol: 38 (47.5%), viral: 25 (31.3%), alcohol/viral: 7 (8.8%) and others: 10 (12.5%). The presence of erectile dysfunction was found in 51 (63.8%) patients with 44 (55%) and 7 (8.8%) suffering from mild-to-moderate and moderate-to-severe erectile dysfunction. Mean MELD and hepatic venous pressure gradient (HVPG) were significantly higher in patients with erectile dysfunction (P = .021; P = .028). Child-Pugh score C, MELD, creatinine, age, arterial hypertension, diabetes, low libido, low testosterone and high HVPG were associated with the presence of erectile dysfunction. Interestingly, beta-blocker therapy was not associated with an increased risk. In multivariate models, arterial hypertension (OR: 6.36 [1.16-34.85]; P = .033), diabetes (OR: 7.40 [1.31-41.75]; P = .023), MELD (OR: 1.19 [1.03-1.36]; P = .015) and increasing HVPG (n = 48; OR: 1.11 [1.002-1.23]; P = .045) were independent risk factors for the presence of erectile dysfunction.ConclusionAbout two-thirds of male patients with cirrhosis show erectile dysfunction. Severity of liver dysfunction, portal hypertension, arterial hypertension and diabetes were identified as risk factors for erectile dysfunction.

Dataset Information

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

Publications

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

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