[The role of activated hepatic stellate cells in liver fibrosis, portal hypertension and cancer angiogenesis]

Ductular reaction promotes intrahepatic angiogenesis through Slit2-Roundabout 1 signaling

BACKGROUND AND AIMS

Ductular reaction (DR) expands in chronic liver diseases and correlates with disease severity. Besides its potential role in liver regeneration, DR plays a role in the wound-healing response of the liver, promoting periductular fibrosis and inflammatory cell recruitment. However, there is no information regarding its role in intrahepatic angiogenesis. In the current study we investigated the potential contribution of DR cells to hepatic vascular remodeling during chronic liver disease.

APPROACH AND RESULTS

In mouse models of liver injury, DR cells express genes involved in angiogenesis. Among angiogenesis-related genes, the expression of Slit2 and its receptor Roundabout 1 (Robo1) was localized in DR cells and neoangiogenic vessels, respectively. The angiogenic role of the Slit2-Robo1 pathway in chronic liver disease was confirmed in ROBO1/2-/+ mice treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine, which displayed reduced intrahepatic neovascular density compared to wild-type mice. However, ROBO1/2 deficiency did not affect angiogenesis in partial hepatectomy. In patients with advanced alcohol-associated disease, angiogenesis was associated with DR, and up-regulation of SLIT2-ROBO1 correlated with DR and disease severity. In vitro, human liver-derived organoids produced SLIT2 and induced tube formation of endothelial cells.

CONCLUSIONS

Overall, our data indicate that DR expansion promotes angiogenesis through the Slit2-Robo1 pathway and recognize DR cells as key players in the liver wound-healing response.

Preparation of long-acting microspheres loaded with octreotide for the treatment of portal hypertensive

The purpose of this study was to optimize the preparation method of injectable Octreotide microspheres. To explore the correlation between the solvent system and the general properties of microspheres to reduce burst release and enable them to be used for portal hypertension. Octreotide microspheres were prepared by modified double emulsion solution evaporation method after optimizing preparation conditions. The results showed that Octreotide microspheres had a particle size of 57.48 ± 15.24 μm, and the initial release was significantly reduced. In vitro release and in vivo pharmacokinetic data indicated that Octreotide was released stably within 1200 h. The effects on portal vein pressure, liver tissue morphology and other related indexes were observed after administration. As obvious results, injection of Octreotide microspheres could significantly reduce portal vein pressure and reduce the portal vein lumen area in experimental cirrhotic portal hypertensive rats. The optimized Octreotide PLGA microsphere preparation has been proved to have a good effect on PHT in vivo after detecting aminotransferase (AST) and alanine aminotransferase (ALT) activity, liver tissue hydroxyproline (Hyp) content, serum and liver tissue malondialdehyde (MDA) levels, plasma prostacyclin (PGI₂) levels, and liver tissue tumor necrosis factor (TNFα) content. In addition, serum and liver tissue superoxide dismutase (SOD) activity and liver tissue glutathione (GSH) content, plasma thromboxane (TXA₂), serum nitric oxide (NO), liver tissue nitric oxide synthase (NOS), and plasma and liver tissue endothelin (ET) were significantly increased.

Tyrosine kinase inhibitors: friends or foe in treatment of hepatic fibrosis?

Aberrant activity of tyrosine kinases has been proved to be associated with multiple diseases including fibrotic diseases. Tyrosine kinases inhibitors (TKIs) might be a novel approach to transform the anti-fibrotic treatment. However, both beneficial and adverse effects are observed by researchers when using these TKIs in either preclinical animal models or patients with hepatic fibrosis. Since hepatotoxicity of TKIs is the leading cause for drug withdrawals thus limits its application in anti-fibrosis, not only efficacy but also safety of TKIs should be paid great concerns. It has been observed in a few studies that TKIs could induce relatively high rate of hepatic biochemical markers elevations and even result in liver failure. Fortunately, several strategies have been adopt to handle with the hepatotoxicity. Accumulating evidences suggest that hepatic stellate cells (HSC) play a pivotal role in hepatic fibrogenesis, so it might be a good option to develop selective TKIs specifically targeting HSCs. The present review will briefly summarize the anti-fibrotic mechanism of TKIs, adverse effects of TKIs as well as the novel developed selective delivery of TKIs.

The herbal compound Songyou Yin (SYY) inhibits hepatocellular carcinoma growth and improves survival in models of chronic fibrosis via paracrine inhibition of activated hepatic stellate cells

Chronic fibrosis is a major risk factor for the development of hepatocellular carcinoma (HCC). The pathological progression of hepatic fibrosis has been linked to cellular processes that promote tumor growth and metastasis. Several recent studies have highlighted the cross-talk between tumor cells and activated hepatic stellate cells (aHSCs) in HCC. The herbal compound Songyou Yin (SYY) is known to attenuate hepatoma cell invasion and metastasis via down-regulation of cytokine secretion by aHSCs. However the underlying mechanism of SYY treatment in reversal of hepatic fibrosis and metastasis of liver cancers is not known. In the current study, a nude mouse model with liver fibrosis bearing orthotopic xenograft was established and we found that SYY could reduce associated fibrosis, inhibit tumor growth and improve survival. In the subcutaneous tumor model with fibrosis, we found that SYY could inhibit liver cancer. In vitro, hepatoma cells incubated with conditioned media (CM) from SYY treated aHSCs showed reduced proliferation, decrease in colony formation and invasive potential. SYY treated group showed altered gene expression, with 1205 genes up-regulated and 1323 genes down-regulated. Gene cluster analysis indicated that phosphatidylinositol-3-kinase (PI3K) was one of the key genes altered in the expression profiles. PI3K related markers were all significantly down-regulated. ELISA also indicated decreased secretion of cytokines which were regulated by PI3K/AKT signaling after SYY treatment in the hepatic stellate cell line, LX2. These data clearly demonstrate that SYY therapy inhibits HCC invasive and metastatic potential and improves survival in nude mice models with chronic fibrosis background via inhibition of cytokine secretion by activated hepatic stellate cells.

New Insight into the Anti-liver Fibrosis Effect of Multitargeted Tyrosine Kinase Inhibitors: From Molecular Target to Clinical Trials

Tyrosine kinases (TKs) is a family of tyrosine protein kinases with important functions in the regulation of a broad variety of physiological cell processes. Overactivity of TK disturbs cellular homeostasis and has been linked to the development of certain diseases, including various fibrotic diseases. In regard to liver fibrosis, several TKs, such as vascular endothelial growth factor receptor, platelet-derived growth factor receptor, fibroblast growth factor receptor, and epidermal growth factor receptor kinases, have been identified as central mediators in collagen production and potential targets for anti-liver fibrosis therapies. Given the essential role of TKs during liver fibrogenesis, multitargeted inhibitors of aberrant TK activity, including sorafenib, erlotinib, imatinib, sunitinib, nilotinib, brivanib and vatalanib, have been shown to have potential for treating liver fibrosis. Beneficial effects are observed by researchers of this field using these multitargeted TK inhibitors in preclinical animal models and in patients with liver fibrosis. The present review will briefly summarize the anti-liver fibrosis effects of multitargeted TK inhibitors and molecular mechanisms.

Therapeutic potential of microRNA: a new target to treat intrahepatic portal hypertension?

Intrahepatic portal hypertension accounts for most of the morbidity and mortality encountered in patients with liver cirrhosis, due to increased portal inflow and intrahepatic vascular resistance. Most treatments have focused only on portal inflow or vascular resistance. However, miRNA multitarget regulation therapy may potentially intervene in these two processes for therapeutic benefit in cirrhosis and portal hypertension. This review presents an overview of the most recent knowledge of and future possibilities for the use of miRNA therapy. The benefits of this therapeutic modality--which is poorly applied in the clinical setting--are still uncertain. Increasing the knowledge and current understanding of the roles of miRNAs in the development of intrahepatic portal hypertension and hepatic stellate cells (HSCs) functions, as well as their potential as novel drug targets, is critical.

Herbal compound "Songyou Yin" attenuates hepatoma cell invasiveness and metastasis through downregulation of cytokines secreted by activated hepatic stellate cells

Background

Activated hepatic stellate cells (aHSCs) play an important role in the progression of hepatocellular carcinoma (HCC). Here, we determined if cytokines secreted in response to the herbal compound “Songyou Yin” (SYY) treatment of aHSCs could influence invasiveness and metastatic capabilities of hepatoma cells.

Methods

Primary rat hepatic stellate cells (HSCs) were isolated, activated, divided into SYY treated and untreated (nSYY) groups, and conditioned media (CM-SYY and CM-nSYY, respectively) were collected. The hepatoma cell line, McA-RH7777 was cultured for 4 weeks with SYY, CM-SYY, and CM-nSYY, designated McA-SYY, McA-SYYCM and McA-nSYYCM. The invasiveness and metastatic capabilities were evaluated using Matrigel invasion assay in vitro and pulmonary metastasis in vivo. Matrix metalloproteinase-2 (MMP-2), MMP-9, E-cadherin, N-cadherin, and vimentin protein levels in McA-SYYCM and McA-nSYYCM were evaluated by Western blot. Cytokine levels in conditioned media were tested using enzyme-linked immunosorbent assay (ELISA).

Results

Matrigel invasion assay indicated that the number of McA-SYYCM cells passing through the basement membrane was less than in McA-nSYYCM cells (P < 0.01). Similar results were also observed in vivo for lung metastasis. McA-SYYCM cells showed less pulmonary metastasis capabilities than McA-nSYYCM cells (P < 0.001). The reduced expression of MMP-2 and reversed epithelial to mesenchymal transition with E-cadherin upregulation, and N-cadherin and vimentin downregulation were also found in McA-SYYCM compared to McA-nSYYCM. Metastasis-promoting cytokines hepatocyte growth factor, interleukin-6, transforming growth factor-β1, and vascular endothelial growth factor were markedly decreased in CM-SYY compared to CM-nSYY.

Conclusions

SYY attenuates hepatoma cell invasiveness and metastasis capabilities through downregulating cytokines secreted by activated hepatic stellate cells.

MicroRNA-29 family, a crucial therapeutic target for fibrosis diseases

MicroRNAs (miRNAs) are a class of approximately 20-nucleotides single-stranded endogenous RNAs that regulate gene expression at the post-transcriptional level. miRNAs have recently been known to regulate cell proliferation, differentiation, and apoptosis. Fibrosis is the leading cause of organ dysfunction in diseases and results from an imbalance in the turnover of extracellular matrix components. Accumulating studies have demonstrated that miR-29 family participates in the development of liver fibrosis, renal fibrosis, pulmonary fibrosis, cardiac fibrosis. In this review, we are discussing the comprehensive role of miR-29 family in moderating profibrotic effect and its potential as therapeutic approach to fibrosis diseases.

Sodium nitrite therapy rescues ischemia-induced neovascularization and blood flow recovery in hypertension

Arterial hypertension is a major risk factor that can lead to complication of peripheral vascular disease due, in part, to endothelial dysfunction. Because sodium nitrite (SN) can be converted to nitric oxide (NO), which counteracts endothelial dysfunction, we explored the effect of nitrite on neovascularization following hind limb ischemia in different models of hypertension (HT). Chronic delivery of angiotensin II (Ang II, 400 ng/kg/min) or N(omega)-nitro-L-arginine-methyl-ester (L-NAME, 0.1 g/L) was used for a 2-week period to induce hypertension. Mice were subjected to femoral artery ligation-induced ischemia in the hind limb followed by treatment with SN (50 mg/L) for 2 weeks. SN significantly reduced systolic arterial blood pressure in mice receiving Ang II and L-NAME but had no effect in sham animals. After 2 weeks, blood flow and microangiography showed 60 % ± 1.0 recovery in sham compared with 40 % ± 1.3 in HT mice. Importantly, sham and HT mice treated with SN showed a 100 % blood flow recovery associated with normalization in capillary density. The inhibition of xanthine-oxido-reductase (allopurinol) or VEGFR (SU-5416) prevented the neovascularization in HT mice treated with SN. Cyclic GMP (cGMP) content in the hind limb was significantly increased in mice treated with SN compared with non-treated mice. Nitrite/nitrate content was only increased in the sham group treated with SN. Immunoprecipitation and Western blot analysis revealed an increase in eNOS/Akt/VEGFR phosphorylation in skeletal muscle from mice treated with SN compared with non-treated mice. Our findings indicate that SN therapy rescues the neovascularization and blood flow recovery in the ischemic hind limb of sham and HT mice likely through the Akt/NO/cGMP and VEGFR pathways.

[Treatment update on portal hypertension and complications]

Current understanding of the pathophysiology of portal hypertension has resulted in therapeutic approaches aimed at correcting the increased splanchnic blood flow and some of which have been already used in clinical practice. Recently new perspectives opened and erstwhile paradigm has been changed to focus on increased resistance to portal blood flow and the formation of portosystemic collateralization. Several studies revealed the clear-cut mechanisms of hepatic endothelial dysfunction and abnormal angiogenesis contributing to the development of portal hypertension. Thus the modulations of hyperdynamic circulation or angiogenesis seem to be valuable therapeutic targets. In the current review update, we discuss the multidisciplinary management of modulating hepatic vascular resistance and abnormal angiogenesis associated with portal hypertension. However, these new pharmacological approaches are still under investigation and widescale clinical application are needed to develop effective strategies.

Current status of liver diseases in Korea: liver cirrhosis

Liver cirrhosis represents the final common pathway of virtually all chronic liver diseases, and is characterized by an accumulation of extracellular matrix rich in fibrillar collagens. Patients with cirrhosis are at risk of developing many potential complications. The most common complication seen in patients with liver cirrhosis is ascites, and the most lethal one is bleeding varices. Other intermediate and late stage complications include spontaneous bacterial peritonitis, hepatic encephalopathy, and hepatorenal syndrome. The mortality and morbidity attributable to liver disease in Korea have decreased continuously over the past decades, probably due to the implementation of universal vaccination and potent antiviral therapies. In addition, recent advances in the understanding of the pathophysiology of cirrhosis and in various management approaches to cirrhosis complications will contribute to the steady improvement in patient outcomes in this country. This review article outlines recent changes in etiologies and prognosis, and the advances in management of cirrhosis in Korea.