Pigment Epithelium-Derived Factor (PEDF) Prevents Hepatic Fat Storage, Inflammation, and Fibrosis in Dietary Steatohepatitis of Mice.

BACKGROUND AND AIMS: Pigment epithelium-derived factor (PEDF) has been shown to be a potent inhibitor of inflammation through its anti-oxidative property. Since oxidative response is considered to play the pivotal role of the development and progression of nonalcoholic steatohepatitis (NASH), it is conceivable that PEDF may play a protective role against NASH. In this study, we examined whether administration of PEDF slowed the progression of NASH in mice models. METHODS: Mice were fed methionine- and choline-deficient (MCD) diet with or without intramuscular administration of adenovirus-expressing PEDF (Ad-PEDF). Effects of PEDF administration on NASH were histologically and biochemically evaluated. RESULTS: Administration of Ad-PEDF significantly decreased hepatic fat storage as well as serum levels of ALT in MCD diet-fed mice. Dihydroethidium staining showed that MCD diet-triggered oxidative stress was reduced in the liver of Ad-PEDF-administered mice compared to that of PBS- or Ad-LacZ-administered mice. Activation of Kupffer cells and hepatic fibrosis was also inhibited by Ad-PEDF administration. Quantitative real-time RT-PCR revealed that MCD diet up-regulated expressions of TNF-α, IL-1ß, IL-6, TGF-ß, collagen-1, and collagen-3 mRNA, which were also attenuated with Ad-PEDF administration, whereas MCD diet-induced down-regulation of expressions of PPAR-γ mRNA was restored with Ad-PEDF administration. Furthermore, immunoblotting analysis showed that MCD diet-induced up-regulation of NADPH oxidase components was significantly decreased in Ad-PEDF-administered mice. CONCLUSIONS: The present results demonstrated for the first time that PEDF could slow the development and progression of steatohepatitis through the suppression of steatosis and inflammatory response in MCD diet-fed mice. Our study suggests that PEDF supplementation may be a novel therapeutic strategy for the treatment of NASH.

The ratio of serum placenta growth factor to soluble vascular endothelial growth factor receptor-1 predicts the prognosis of hepatocellular carcinoma.

Angiogenesis plays crucial roles in development and progression of hepatocellular carcinoma (HCC). Placenta growth factor (PLGF), belonging to vascular endothelial growth factor (VEGF) family, is involved in angiogenesis associated with cancer. Soluble VEGF receptor-1 (sVEGFR1) has been thought to be an intrinsic negative regulator for PLGF. We investigated whether serum PLGF and serum sVEGFR1 is associated with prognosis of HCC. Serum PLGF and sVEGFR1 levels were measured in 145 patients with HCC using enzyme-linked immunosorbent assay. The levels of these factors and the ratio of PLGF to sVEGFR1 were analyzed in relation with clinical parameters. The higher level of sVEGFR1 and the lower ratio of PLGF/sVEGFR1 were significantly associated with poor survival in HCC. Cox regression analysis revealed that the lower ratio of PLGF/sVEGFR1 independently correlated to prognosis of patients with HCC. The ratio of PLGF/sVEGFR1 was independent prognostic indicator for HCC. The ratio of PLGF/sVEGFR1 should be addressed in anti-angiogenic therapy for HCC.

Oxidative stress induces the endoplasmic reticulum stress and facilitates inclusion formation in cultured cells.

BACKGROUND/AIMS: The precise mechanism of formation and significance of Mallory bodies (MBs) are poorly understood. The endoplasmic reticulum (ER) is the organelle responsible for proper folding and elimination of unfolded proteins. Therefore, failure of this function increases defective proteins in the cell. METHODS: We examined the effects of oxidative stress on induction of ER stress and keratin 8 and 18 (K8/18)-containing inclusion formation in cultured human hepatoma cells and hepatocytes by immunofluorescence and immunoblot analyses. RESULTS: Generation of H(2)O(2) was detected in glucose oxidase (GO)-treated cells by 2',7'-dichlorodihydrofluorescein diacetate and co-treatment with GO and acetyl-leucyl-leucyl-norleucinal (ALLN), a proteasome inhibitor, induced formation of extensive keratin inclusions that were inhibited by pre-treatment with N-acetyl-cysteine. These inclusions shared similar features with MBs by immunofluorescence analysis. Electron microscopy showed that these structures appeared near the nuclei, surrounded by filamentous structures. GO and ALLN upregulated the expression of ER stress markers, however, 4-phenylbutyrate, a chemical chaperone, reduced formation of inclusions and expression of the ER stress markers. CONCLUSIONS: The oxidative stress coupled with limited inhibition of the proteasome induces dysfunction of the ER and results in inclusion formation in cultured cells. This suggests that ER stress plays a role in MB formation in liver disease.

Endothelial progenitor cell transplantation improves the survival following liver injury in mice.

BACKGROUND & AIMS: Neovascularization, which is vital to the healing of injured tissues, recently has been found to include both angiogenesis, which involves in mature endothelial cells, and vasculogenesis, involving endothelial progenitor cells. The aim of this study was to clarify the possible roles of endothelial progenitor cells during postnatal liver regeneration. METHODS: To determine how endothelial progenitor cells participate in liver regeneration, human or mouse endothelial progenitor cells were transplanted into the mice with carbon tetrachloride-induced acute liver injury. Survival rate of the mice in endothelial progenitor cell-transplanted and control groups was calculated. Separately, livers removed temporally from both groups were examined. RESULTS: At an early stage, transplanted human endothelial progenitor cells were seen mainly surrounding hepatic central veins where hepatocytes showed extensive necrosis; later, the transplanted cells formed tubular structures. More of these cells were observed along hepatic sinusoids. Transplantation of human or mouse endothelial progenitor cells improved survival of the mice following liver injury (from 28.6% to 85.7%, P < .0005 and from 33.3% to 80.0%, P < .001, respectively), accompanied by greater proliferation of hepatocytes. Human endothelial progenitor cells produced several growth factors, such as hepatocyte growth factor, transforming growth factor-alpha, heparin-binding epidermal growth factor-like growth factor, and vascular endothelial growth factor, and also elicited endogenous growth factors. CONCLUSIONS: Endogenous and exogenous growth factors and direct neovascularization after endothelial progenitor cell transplantation promoted liver regeneration, thus improving survival after liver injury. Transplantation of endothelial progenitor cells could represent a new therapeutic strategy for promoting liver regeneration.

Ratio of serum vascular endothelial growth factor to platelet count correlates with disease activity in a patient with POEMS syndrome.

Vascular endothelial growth factor (VEGF) is known to be involved in the pathogenesis of POEMS (polyneuropathy, organomegaly, endocrine disorder, M-protein, and skin lesion) syndrome. Because platelets have recently been recognized as transporters of VEGF, enhanced blood coagulation activity in this syndrome may accelerate vasopermeability by releasing VEGF from platelets in vivo. Here we report a case of POEMS syndrome with anasarca showing a high ratio of serum VEGF to platelet count, indicative of massive VEGF release from aggregated platelets in vivo. Changes in the ratio clearly reflected disease activity. This observation suggests that the ratio of serum VEGF to platelet count is more precise in monitoring disease activity than serum VEGF alone, and that VEGF released in vivo is critically involved in the pathogenesis of POEMS syndrome, causing hypervasopermeability.

Hepatitis C virus down-regulates insulin receptor substrates 1 and 2 through up-regulation of suppressor of cytokine signaling 3.

The pathogenesis of hepatitis C virus (HCV)-associated insulin resistance remains unclear. Therefore, we investigated mechanisms for HCV-associated insulin resistance. Homeostasis model assessment for insulin resistance was increased in patients with HCV infection. An increase in fasting insulin levels was associated with the presence of serum HCV core, the severity of hepatic fibrosis and a decrease in expression of insulin receptor substrate (IRS) 1 and IRS2, central molecules of the insulin-signaling cascade, in patients with HCV infection. Down-regulation of IRS1 and IRS2 was also seen in HCV core-transgenic mice livers and HCV core-transfected human hepatoma cells. Carbobenzoxy-l-leucyl-l-leucyl-l-leucinal, a potent proteosomal proteolysis inhibitor, blocked down-regulation of IRS1 and IRS2 in HCV core-transfected hepatoma cells. In human hepatoma cells, HCV core up-regulated suppressor of cytokine signaling (SOCS) 3 and caused ubiquitination of IRS1 and IRS2. HCV core-induced down-regulation of IRS1 and IRS2 was not seen in SOCS3(-/-) mouse embryonic fibroblast cells. Furthermore, HCV core suppressed insulin-induced phosphorylation of p85 subunit of phosphatidylinositol 3-kinase and Akt, activation of 6-phosphofructo-2-kinase, and glucose uptake. In conclusion, HCV infection changes a subset of hepatic molecules regulating glucose metabolism. A possible mechanism is that HCV core-induced SOCS3 promotes proteosomal degradation of IRS1 and IRS2 through ubiquitination.