Primary prophylaxis of esophageal variceal bleeding in cirrhosis

Murine study of portal hypertension associated endothelin-1 hypo-response

AIM: To investigate endothelin-1 hypo-responsive associated with portal hypertension in order to improve patient treatment outcomes.

METHODS: Wild type, eNOS^-/- and iNOS^-/- mice received partial portal vein ligation surgery to induce portal hypertension or sham surgery. Development of portal hypertension was determined by measuring the splenic pulp pressure, abdominal aortic flow and portal systemic shunting. To measure splenic pulp pressure, a microtip pressure transducer was inserted into the spleen pulp. Abdominal aortic flow was measured by placing an ultrasonic Doppler flow probe around the abdominal aorta between the diaphragm and celiac artery. Portal systemic shunting was calculated by injection of fluorescent microspheres in to the splenic vein and determining the percentage accumulation of spheres in liver and pulmonary beds. Endothelin-1 hypo-response was evaluated by measuring the change in abdominal aortic flow in response to endothelin-1 intravenous administration. In addition, thoracic aorta endothelin-1 contraction was measured in 5 mm isolated thoracic aorta rings ex-vivo using an ADI small vessel myograph.

RESULTS: In wild type and iNOS^-/- mice splenic pulp pressure increased from 7.5 ± 1.1 mmHg and 7.2 ± 1 mmHg to 25.4 ± 3.1 mmHg and 22 ± 4 mmHg respectively. In eNOS^-/- mice splenic pulp pressure was increased after 1 d (P = NS), after which it decreased and by 7 d was not significantly elevated when compared to 7 d sham operated controls (6.9 ± 0.6 mmHg and 7.3 ± 0.8 mmHg respectively, P = 0.3). Abdominal aortic flow was increased by 80% and 73% in 7 d portal vein ligated wild type and iNOS when compared to shams, whereas there was no significant difference in 7 d portal vein ligated eNOS^-/- mice when compared to shams. Endothelin-1 induced a rapid reduction in abdominal aortic blood flow in wild type, eNOS^-/- and iNOS^-/- sham mice (50% ± 8%, 73% ± 9% and 47% ± 9% respectively). Following portal vein ligation endothelin-1 reduction in blood flow was significantly diminished in each mouse group. Abdominal aortic flow was reduced by 19% ± 9%, 32% ± 10% and 9% ± 9% in wild type, eNOS^-/- and iNOS^-/- mice respectively.

CONCLUSION: Aberrant endothelin-1 response in murine portal hypertension is NOS isoform independent. Moreover, portal hypertension in the portal vein ligation model is independent of ET-1 function.

Thalidomide ameliorates portal hypertension via nitric oxide synthase independent reduced systolic blood pressure

AIM: Portal hypertension is a common complication of liver cirrhosis and significantly increases mortality and morbidity. Previous reports have suggested that the compound thalidomide attenuates portal hypertension (PHT). However, the mechanism for this action is not fully elucidated. One hypothesis is that thalidomide destabilizes tumor necrosis factor α (TNFα) mRNA and therefore diminishes TNFα induction of nitric oxide synthase (NOS) and the production of nitric oxide (NO). To examine this hypothesis, we utilized the murine partial portal vein ligation (PVL) PHT model in combination with endothelial or inducible NOS isoform gene knockout mice.

METHODS: Wild type, inducible nitric oxide synthase (iNOS)^-/- and endothelial nitric oxide synthase (eNOS)^-/- mice received either PVL or sham surgery and were given either thalidomide or vehicle. Serum nitrate (total nitrate, NOx) was measured daily for 7 d as a surrogate of NO synthesis. Serum TNFα level was quantified by enzyme-linked immunosorbent assay. TNFα mRNA was quantified in liver and aorta tissue by reverse transcription-polymerase chain reaction. PHT was determined by recording splenic pulp pressure (SPP) and abdominal aortic flow after 0-7 d. Response to thalidomide was determined by measurement of SPP and mean arterial pressure (MAP).

RESULTS: SPP, abdominal aortic flow (Qao) and plasma NOx were increased in wild type and iNOS^-/- PVL mice when compared to sham operated control mice. In contrast, SPP, Qao and plasma NOx were not increased in eNOS^-/- PVL mice when compared to sham controls. Serum TNFα level in both sham and PVL mice was below the detection limit of the commercial ELISA used. Therefore, the effect of thalidomide on serum TNFα levels was undetermined in wild type, eNOS^-/- or iNOS^-/- mice. Thalidomide acutely increased plasma NOx in wild type and eNOS^-/- mice but not iNOS^-/- mice. Moreover, thalidomide temporarily (0-90 min) decreased mean arterial pressure, SPP and Qao in wild type, eNOS^-/- and iNOS^-/- PVL mice, after which time levels returned to the respective baseline.

CONCLUSION: Thalidomide does not reduce portal pressure in the murine PVL model by modulation of NO biosynthesis. Rather, thalidomide reduces PHT by decreasing MAP by an undetermined mechanism.

Risk factors for hepatic encephalopathy in patients with cirrhosis and refractory ascites: relevance of serum sodium concentration

Hyponatraemia is common in patients with advanced cirrhosis and is associated with remarkable changes in brain cells, particularly a reduction in myoinositol and other intracellular organic osmolytes related to the hypo-osmolality of the extracellular fluid. It has been recently suggested that hyponatraemia may be an important factor associated with the development of overt hepatic encephalopathy (HE). To test this hypothesis, we retrospectively analysed the incidence and predictive factors of overt HE using a database of 70 patients with cirrhosis included in a prospective study comparing transjugular intrahepatic portosystemic shunts (TIPS) vs large-volume paracentesis in the management of refractory of ascites. Variables used in the analysis included age, sex, previous history of HE, treatment assignment (TIPS vs large volume paracentesis plus albumin), treatment with diuretics, serum bilirubin, serum creatinine and serum sodium concentration. Laboratory parameters were measured at entry, at 1 month and every 3 months during follow-up and at the time of development of HE in patients who developed this complication. During a mean follow-up of 10 months, 50 patients (71%) developed 117 episodes of HE. In the whole population of patients, the occurrence of HE was independently associated with serum hyponatraemia, serum bilirubin and serum creatinine. In conclusion, in patients with refractory ascites, the occurrence of HE is related to the impairment of liver and renal function and presence of hyponatraemia.

Current and future treatments of autoimmune hepatitis

Corticosteroid therapy induces clinical, laboratory and histological improvements in 80% of patients with autoimmune hepatitis. Prednisone, alone or at a lower dose in combination with azathioprine, increases the 20-year life expectancy to 80% and prevents or reduces hepatic fibrosis in 79% of patients. The combination regimen is preferred and treatment should be considered in all patients with active disease. The duration of therapy is finite and the medication should be discontinued after resolution of all manifestations of inflammatory activity, including the histological changes. Relapse after drug withdrawal occurs in 50-79% of patients, and it should be treated with long-term azathioprine (2 mg/kg daily). Salvage therapies for individuals intolerant of or refractory to the conventional regimens include high-dose corticosteroids, with or without high-dose azathioprine, 6-mercaptopurine, mycophenolate mofetil, tacrolimus or ciclosporin. Liver transplantation should be considered in patients with hepatic failure unresponsive to corticosteroid treatment, decompensated cirrhosis with a Model for End-Stage Liver Disease score of at least 15 points, or hepatocellular carcinoma that meets transplantation criteria. Autoimmune hepatitis recurs after transplantation in at least 17% of patients, and it typically improves after adjustments in the immunosuppressive regimen. Future therapies are likely to include mesenchymal stem cell transplantation, adoptive transfer of T regulatory cells, and cytokine manipulation. The emergence of new treatments will require the development of a collaborative network of clinical and basic investigators, as the complexity and specificity of current management problems require solutions that exceed the capabilities of single institutions.