Portal hypertension due to schistosomiasis mansoni

Bsep/Abcb11 knockout ameliorates Schistosoma mansoni liver pathology by reducing parasite fecundity

BACKGROUND AND AIMS

Schistosoma mansoni infection is one of the worldwide leading causes of liver fibrosis and portal hypertension. The objective of this study was to evaluate whether polyhydroxylated bile acids (BAs), known to protect mice from the development of acquired cholestatic liver injury, counteract S. mansoni-induced inflammation and fibrosis.

METHODS

Adult FVB/N wild type (WT) and Abcb11/Bsep-/- mice were infected with either 25 or 50 S. mansoni cercariae. Eight weeks post infection, effects on liver histology, serum biochemistry, gene expression profile of proinflammatory cytokines and fibrotic markers, hepatic hydroxyproline content and FACS analysis were performed.

RESULTS

Bsep-/- mice infected with S. mansoni showed significantly less hepatic inflammation and tendentially less fibrosis compared to infected WT mice. Despite elevated alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase levels in infected Bsep-/- mice, inflammatory cells such as M2 macrophages and Mac-2/galectin-3+ cells were reduced in these animals. Accordingly, mRNA-expression levels of anti-inflammatory cytokines (IL-4 and IL-13) were increased in Bsep-/- mice upon infection. Furthermore, infected Bsep-/- mice exhibited decreased hepatic egg load and parasite fecundity, consequently affecting the worm reproduction rate. This outcome could arise from elevated serum BA levels and lower blood pH in Bsep-/- mice.

CONCLUSIONS

The loss of Bsep and the resulting changes in bile acid composition and blood pH are associated with the reduction of parasite fecundity, thus attenuating the development of S. mansoni-induced hepatic inflammation and fibrosis.

Relation between liver pathology and prognosis in patients with portal hypertension

The most common causes of variceal bleeding are cirrhosis, schistosomiasis, and extrahepatic portal venous obstruction. The prognosis for an individual patient depends on the severity of the bleeding episode and the underlying liver function. Liver function is determined to a large extent by the underlying liver pathology. Patients with noncirrhotic portal hypertension or cirrhosis with good liver function have good short- and long-term prognoses. In patients with established cirrhosis, the presence of alcoholic hepatitis, hepatocellular carcinoma, or portal venous thrombosis may adversely affect prognosis. In addition to affecting prognosis, the underlying pathology may also influence choice of treatment. This point is particularly true for treatments such as shunt surgery, liver transplantation, or transjugular intrahepatic shunts.

Hemodynamic mechanisms of emerging portal hypertension caused by schistosomiasis in the hamster

A hamster model of schistosomiasis has provided the first opportunity to sequentially examine the early phases of the development of portal hypertension in a natural model of chronic liver disease. Groups of hamsters were infected with 50 cercariae of Schistosoma mansoni and underwent hemodynamic evaluation at intervals of 5, 8, 12 and 20 wk after infection. A progressive rise in intrahepatic resistance (from 4.0 +/- 0.4 to 8.4 +/- 1.0 mm Hg min.ml-1.gm liver weight [p less than 0.01]) appeared to play a major role in the initial stages of evolving portal hypertension. A gradual decline in portal blood flow (from 2.1 +/- 0.3 to 1.3 +/- 0.1 ml.min-1.gm-1 liver weight [p less than 0.01]) was only partially compensated for by an increase in hepatic arterial flow. Accordingly, by week 20, total hepatic blood flow decreased 23%. Liver weight that increased markedly between 5 and 12 wk after infection, as a result of the acute accumulation of obstructing granulomas, stabilized between wk 12 and 20, while a gradual but progressive rise in hepatic collagen content was seen. Portal pressure increased 75% during the study period. Chronic examination of this natural model should help define the pathogenesis of the complications of portal hypertension and contribute to the basis for effective intervention in this disease process.

Hepatoportal sclerosis in childhood

The clinical, angiographic, and pathologic features of hepatoportal sclerosis in five children are presented. Hepatosplenomegaly with preservation of liver function and esophageal varices were demonstrated. Histologically, portal alterations were consistent and prominent and included subintimal sclerosis of the intrahepatic venous branches and telangiectases. Angiographic patterns were variable, but all exhibited intrahepatic portal venous obstruction. In three patients, there was an association with extrahepatic portal vein obstruction at different sites. Our data suggest that intrahepatic portal vein thrombosis could be the primary disorder in hepatoportal sclerosis, which may vary in extent and site, involving the intrahepatic branches of the portal vein with or without the involvement of the portal trunk. Combined clinical, angiographic, and pathologic data can contribute to a better understanding of hepatoportal sclerosis in children.