Portal hypertension in patients with nonalcoholic fatty liver disease:Current knowledge and challenges

Portal hypertension(PH)has traditionally been observed as a consequence of significant fibrosis and cirrhosis in advanced non-alcoholic fatty liver disease(NAFLD).However,recent studies have provided evidence that PH may develop in earlier stages of NAFLD,suggesting that there are additional pathogenetic mechanisms at work in addition to liver fibrosis.The early development of PH in NAFLD is associated with hepatocellular lipid accumulation and ballooning,leading to the compression of liver sinusoids.External compression and intraluminal obstacles cause mechanical forces such as strain,shear stress and elevated hydrostatic pressure that in turn activate mechanotransduction pathways,resulting in endothelial dysfunction and the development of fibrosis.The spatial distribution of histological and functional changes in the periportal and perisinusoidal areas of the liver lobule are considered responsible for the pre-sinusoidal component of PH in patients with NAFLD.Thus,current diagnostic methods such as hepatic venous pressure gradient(HVPG)measurement tend to underestimate portal pressure(PP)in NAFLD patients,who might decompensate below the HVPG threshold of 10 mmHg,which is traditionally considered the most relevant indicator of clinically significant portal hypertension(CSPH).This creates further challenges in finding a reliable diagnostic method to stratify the prognostic risk in this population of patients.In theory,the measurement of the portal pressure gradient guided by endoscopic ultrasound might overcome the limitations of HVPG measurement by avoiding the influence of the pre-sinusoidal component,but more investigations are needed to test its clinical utility for this indication.Liver and spleen stiffness measurement in combination with platelet count is currently the best-validated non-invasive approach for diagnosing CSPH and varices needing treatment.Lifestyle change remains the cornerstone of the treatment of PH in NAFLD,together with correcting the components of metabolic syndrome,using nonselective beta blockers,whereas emerging candidate drugs require more robust confirmation from clinical trials.

Thiazolidinedione treatment inhibits bile duct proliferation and fibrosis in a rat model of chronic cholestasis

AIM: To investigate the effects of troglitazone (TGZ), an anti-diabetic drug which activates peroxisome proliferatoractivated receptor-γ (PPAR-γ), for liver tissue repair, and the development of ductular reaction, following common bile duct ligation (BDL) in rats.METHODS: Rats were supplemented with TGZ (0.2% w/w in the pelleted food) for 1 wk before BDL or sham operation.Animals were killed at 1, 2, or 4 wk after surgery.RESULTS: The development of liver fibrosis was reduced in rats receiving TGZ, as indicated by significant decreases of procollagen type Ⅰ gene expression and liver hydroxyproline levels. Accumulation of α-smooth-muscle actin (SMA)-expressing cells surrounding newly formed bile ducts following BDL, as well as total hepatic levels of SMA were partially inhibited by TGZ treatment, indicating the presence of a reduced number and/or activation of hepatic stellate cells (HSC) and myofibroblasts. Development of the ductular reaction was inhibited by TGZ, as indicated by histochemical evaluation and hepatic activity of γ-glutamyltransferase (GGT).CONCLUSION: Treatment with thiazolidinedione reduces ductular proliferation and fibrosis in a model of chronic cholestasis, and suggests that limiting cholangiocyte proliferation may contribute to the lower development of scarring in this system.

Small diameter H-graft porta-caval shunt performed at different stages of liver disease

BACKGROUND: Partial porto-systemic shunts have been popularized because of reported low rate of mortality and morbidity (especially encephalopathy, liver failure and oc- clusion). To further investigate these assumptions, we ret- rospectively reviewed the results of partial porta-caval shunts performed at different stages of liver disease. METHODS: Twenty-nine cirrhotic patients underwent a partial porta-caval shunt with a ringed polytetrafluoroethy- lene interposition prosthesis of 8-mm ( 20 patients) or 10- mm (9 patients) in diameter. Pre- and post-shunt porta- caval pressure was measured in all patients. Twelve patients (41.4%) belonged to Child A, 11 Child B (37.9%), and 6 Child C (20.7%). Eleven patients (37.9%) suffered from hepatic encephalopathy preoperatively. Twelve patients (41%) were operated on in emergency/urgency. RESULTS: Porta-caval pressure gradient, reduced signifi- cantly using either 8- or 10-mm prosthesis. The overall ear- ly mortality and morbidity were 13. 8% and 48% respec- tively. The early mortality and morbidity were different be- tween patients of Child A and B when compared to those of Child C (0 vs 66.6% and 34.8% vs 66.6% respectively). No patient re-bled early from varices. The overall late mor- tality and morbidity were 40% and 64% respectively. Shunt thrombosis and stenosis took place in 16% and 8% of the two groups of patients respectively; variceal re-bleeding oc- curred in 4 patients (16%). Encephalopathy occurred post- operatively in 5 patients (20%), acute in 3 patients (12%), and chronic in 2 (8%). The actuarial survival rate at 3 and 5 years was 92% and 75% for patients of Child A, 70% and 60% for patients of Child B, and 0% for patients of Child C. CONCLUSIONS: Our results indicate that partial porta-ca- val shunt with a small diameter interposition H-graft is an effective procedure for the treatment of variceal bleeding, as well as for the prevention of re-bleeding in patients of Child A and those of Child B, as an elective or emergency/ urgency procedure, with a low rate of complications and encephalopathy. This technique could be used safely in pa- tients with good liver function but they should be moni- tored closely because of the risk of shunt occlusion.