Systemic and splanchnic endothelin-1 plasma levels in liver cirrhosis before and after transjugular intrahepatic portosystemic shunt (TIPS)

Endothelial Dysfunction in Acute Hepatic Porphyrias

Background Acute hepatic porphyrias (AHPs) are a group of rare diseases caused by dysfunctions in the pathway of heme biosynthesis. Although acute neurovisceral attacks are the most dramatic manifestations, patients are at risk of developing long-term complications, several of which are of a vascular nature. The accumulation of non-porphyrin heme precursors is deemed to cause most clinical symptoms. Aim We measured the serum levels of endothelin-1 (ET-1) and nitric oxide (NO) to assess the presence of endothelial dysfunction (ED) in patients with AHPs. Forty-six patients were classified, according to their clinical phenotype, as symptomatic (AP-SP), asymptomatic with biochemical alterations (AP-BA), and asymptomatic without biochemical alterations (AP-AC). Results Even excluding those under hemin treatment, AP-SP patients had the lowest NO and highest ET-1 levels, whereas no significant differences were found between AP-BA and AP-AC patients. AP-SP patients had significantly more often abnormal levels of ED markers. Patients with the highest heme precursor urinary levels had the greatest alterations in ED markers, although no significant correlation was detected. Conclusions ED is more closely related to the clinical phenotype of AHPs than to their classical biochemical alterations. Some still undefined disease modifiers may possibly determine the clinical picture of AHPs through an effect on endothelial functions.

The transhepatic endotoxin gradient is present despite liver cirrhosis and is attenuated after transjugular portosystemic shunt (TIPS)

BACKGROUND

Translocation of gut-derived bacterial products such as endotoxin is a major problem in liver cirrhosis.

METHODS

To assess the hepatic clearance of bacterial products in individuals with cirrhosis, we tested concentrations of Gram-negative bacterial lipopolysaccharide (LPS), LPS-binding protein (LBP), and the precursor of nitric oxide (NO), L-arginine, in a cohort of 8 stable patients with liver cirrhosis before and after elective transjugular portosystemic shunt (TIPS) implantation, including central venous, hepatic venous, and portal venous measurements.

RESULTS

Using an adapted LPS assay, we detected high portal venous LPS concentrations (mean 1743 ± 819 pg/mL). High concentrations of LPS were detectable in the central venous blood (931 ± 551 pg/mL), as expected in persons with cirrhosis. The transhepatic LPS gradient was found to be 438 ± 287 pg/mL, and 25 ± 12% of portal LPS was cleared by the cirrhotic liver. After TIPS, central venous LPS concentrations increased in the hepatic and central veins, indicating shunting of LPS with the portal blood through the stent. This paralleled a systemic increase of L-arginine, whereas the NO synthase inhibitor asymmetric dimethylarginine (ADMA) remained unchanged, suggesting that bacterial translocation may contribute to the pathogenesis of circulatory dysfunction post-TIPS.

CONCLUSIONS

This study provides quantitative estimates of the role of the liver in the pathophysiology of bacterial translocation. The data indicate that the cirrhotic liver retains the capacity for clearance of bacterial endotoxin from the portal venous blood and that TIPS implantation attenuates this clearance. Thus, increased endotoxin concentrations in the systemic circulation provide a possible link to the increased encephalopathy in TIPS patients.

Plasma Cytokines and Portopulmonary Hypertension in Patients With Cirrhosis Waiting for Orthotopic Liver Transplantation

Portopulmonary hypertension (PPHTN) is a rare complication in patients with portal hypertension. A role of endothelin 1 (ET-1) and other cytokines was demonstrated in primary pulmonary hypertension but not in PPHTN. We evaluated the possible role of ET-1, interleukin 6 (IL-6), interleukin 1β (IL-1β), and tumor necrosis factor alpha (TNF-α) in the pathogenesis of PPHTN. Plasmatic concentrations of ET-1, IL-6, IL-1β, and TNF-α were measured in patients with pulmonary systolic arterial pressure (PAPs) >30 mm Hg and in patients with cirrhosis. In all, Six out of 11 patients with PAPs >30 mm Hg had PPHTN on right heart catheterization. The remaining 10 patients had an hyperdynamic circulation (HC). In PPHTN patients, ET-1 and IL-6 were significantly higher compared with HC and patients with cirrhosis. Endothelin 1 and IL-6 could be implicated in the pathogenesis of PPHTN. On the basis of these results, ET-1 receptor antagonists or anti-IL-6 could have a rationale in the treatment of PPHTN.

Transjugular intrahepatic portosystemic shunt in refractory ascites: a meta-analysis

Transjugular intrahepatic portosystemic shunt (TIPS) is a more effective treatment for refractory ascites than large volume paracentesis (LVP), but the magnitude of its effect in terms of control of ascites, encephalopathy and survival has not been established.

AIM

This meta-analysis compare TIPS to LVP in terms of control of ascites at 4 and 12 months, encephalopathy and survival at 1 and 2 years.

RESULTS

Five randomized controlled trials involving 330 patients were included. In the TIPS group, control of ascites was more frequently achieved at 4 months (66% vs 23.8%, mean difference: 41.4%, 95% confidence interval (CI): 29.5-53.2%, P < 0.001) and 12 months (54.8% vs 18.9%, mean difference: 35%, 95% CI: 24.9-45.1%, P < 0.001), whereas encephalopathy was higher (54.9% vs 38.1%, mean difference: 17%, 95% CI: 7.3-26.6%, P < 0.001). Survival at 1 year (61.7% vs 56.5%, mean difference: 3.2%, 95% CI: -14.7 to 21.9%) and 2 years (50% vs 42.8%, mean difference: 6.8%, 95% CI: -10 to 23.6%) were not significantly different.

CONCLUSIONS

TIPS is a more effective treatment for refractory ascites than LVP. However, TIPS increase encephalopathy and does not improve survival.

Systemic and regional changes in plasma endothelin following transient increase in portal pressure

An acute increase in portal pressure or reduction in portal inflow has been shown to decrease renal plasma flow (RPF). The aim of the study was to evaluate regional and systemic hemodynamics after acute occlusion of a transjugular intrahepatic portosystemic stent-shunt (TIPSS) and study the effect of the same on plasma endothelin (ET-1) levels in the systemic circulation, renal vein, and hepatic vein. Sixteen patients attending for portography after previous TIPSS placement were studied. The shunt was acutely occluded with an angioplasty balloon for 12 minutes. Changes in portal pressure gradient (PPG), hepatic plasma flow (HPF), RPF, cardiac output (CO), and systemic vascular resistance (SVR) were measured before and after shunt occlusion. Blood was collected from the femoral artery and hepatic and renal veins for ET-1 measurement. At T = 0, SVR correlated with circulating arterial ET-1 level (r = 0.74; P <.05). After shunt occlusion (T = 12 minutes), heart rate, CO, and mean arterial pressure decreased (P <.05), whereas PPG increased (P <.05). RPF decreased from 485 +/- 55 to 282 +/- 47 mL/min (P <.01), whereas HPF increased from 700 +/- 39 to 779 +/- 33 mL/min (P <.001). There was a significant increase in arterial concentration and renal production, and decrease in hepatic production of ET-1. Veno-arterial (V-A) concentration difference in ET-1 level in the renal vein, as well as renal flux of ET-1, increased significantly, whereas hepatic vein V-A concentration difference and hepatic flux of ET-1 decreased significantly. At T = 12 minutes, ET-1 renal output correlated negatively with RPF (r = 0.72; P <.05). Results of this study show that an acute increase in portal pressure and reduction in portal inflow brought about by occlusion of a TIPSS shunt decreases RPF and increases HPF. These hemodynamic changes are accompanied by increases in arterial, renal vein, and hepatic vein ET-1 concentrations, which may possibly mediate the observed findings.