Hepatic Stellate Cells

Autophagy is a metabolic process that degrades and recycles intracellular organelles and proteins with many connections to human disease and physiology. We studied the role of autophagy during hepatic stellate cell (HSC) activation, a key event in liver fibrogenesis. Analysis of the autophagic flux during in vitro activation of primary mouse HSCs was performed using a DsRed-GFP-LC3B encoding plasmid. The effect of autophagy inhibition by bafilomycin A1 on the in vitro activation process of human and mouse HSCs was examined by measuring proliferation, presence of activation markers by RT-qPCR, immunofluorescence, and Western blotting. Analysis of lipid droplet and microtubule-associated protein light chain 3 beta (LC3B) colocalization in the presence of PDGF-BB was investigated by immunocytochemistry. A significant increased autophagic flux was observed during culture induced mouse HSC activation. Treatment of mouse HSCs and human HSCs with autophagy inhibitor bafilomycin A1 results in a significant decreased proliferation and expression of activation markers. In addition, lipid droplets and LC3B colocalization was increased after PDGF-BB treatment in quiescent HSCs. During HSC activation, autophagic flux is increased. The demonstration of partly inhibition of in vitro HSC activation after treatment with an autophagy inhibitor unveils a potential new therapeutic strategy for liver fibrosis.

Doxorubicin (DOX) is a broad spectrum anthracycline antibiotic used
to treat multiple cancers. The use of DOX is limited by significant
cardiotoxicity,  hepatotoxicity  and  nephrotoxicity.  Quercetin  is  a
dietary-flavonoid found in plants which prevents oxidant injury and
protects against lipid peroxidation. The objective of the present study
was to assess the possible protective role of quercetin on doxorubicin
induced  hepatic,  cardiac  and  renal  toxicity  in  male  Wistar  rats.
Doxorubicin  (10mg/kg  body  weight)  was  administered  twice  and
quercetin  (100mg/kg  body  weight)  was  administered  on  all  the  21
days of the experimental period. Body weight, heart weight, creatine
kinase in serum and heart, the activities of the antioxidant enzymes in
liver,  heart  and  kidney  were  decreased  in doxorubicin  administered
rats. Liver and kidney weight, liver marker enzymes in serum, liver
and  kidney,  lactate  dehyrogenase  in  serum,  liver,  heart  and  kidney,
urea and creatinine in serum, lipid peroxide content in liver, heart and
kidney were increased. All the biochemical parameters mentioned
above  were  restored  to  near  normal  levels  on  quercetin
administration with doxorubicin. Administration of doxorubicin in
rats  altered  the  biochemical  parameters  but,  did  not  cause  much
effect on the tissues such as liver, heart and kidney which is evident
with histological studies.

Chinese herbal medicine (CHM), an alternative and complementary medicine, has been applied in various diseases. Recently, a number of anti-liver fibrogenesis compounds exhibiting antiliver fibrosis effects have been discovered in CHM. In this review, we reviewed the published data on their anti-fibrosis effects and discussed the possible underlying mechanisms. More investigations are needed to improve the insight into therapeutic effect of CHM on liver fibrosis.

Although a plethora of signaling pathways are known to drive the activation of hepatic stellate cells in liver fibrosis, the involvement of connexin-based communication in this process remains elusive. Connexin43 expression is enhanced in activated hepatic stellate cells and constitutes the molecular building stone of hemichannels and gap junctions. While gap junctions support intercellular communication, and hence the maintenance of liver homeostasis, hemichannels provide a circuit for extracellular communication and are typically opened by pathological stimuli, such as oxidative stress and inflammation. The present study was set up to investigate the effects of inhibition of connexin43-based hemichannels and gap junctions on liver fibrosis in mice. Liver fibrosis was induced by administration of thioacetamide to Balb/c mice for eight weeks. Thereafter, mice were treated for two weeks with TAT-Gap19, a specific connexin43 hemichannel inhibitor, or carbenoxolone, a general hemichann...

Background and Aim: Curcumin, the major polyphenolic compound in turmeric, has been shown to attenuate hepatic damage in several animal models of liver injury. The aim of the present study was to examine the efficacy of curcumin in preventing thioacetamide-induced cirrhosis and to unravel the mechanism of curcumin's effect on hepatic fibrosis in rats.Methods: Liver cirrhosis was induced by thioacetamide (TAA; 200 mg/kg, i.p.) twice weekly for 12 weeks. One group of rats concomitantly received curcumin (300 mg/kg/day, by gavage for 12 weeks); the control group received the solvent at identical amounts and duration.Results: TAA administration induced liver cirrhosis, which was inhibited by curcumin. Liver histopathology, hydroxyproline levels and spleen weights were significantly lower in the rats treated with TAA+curcumin compared with TAA only (P<0.001). Immunohistochemical studies and in situ hybridization demonstrated inhibition of hepatic stellate cell (α smooth muscle actin-positive) activation and collagen αI (I) gene expression in the livers of the TAA+curcumin-treated rats. Curcumin reduced oxidative stress as shown by the decreased hepatic nitrotyrosine staining in the curcumin+TAA-treated rats. Curcumin treatment had no effect on pre existing liver cirrhosis. As determined by in vitro studies using the rat HSC-T6 cell line, curcumin had no direct inhibitory effect on collagen α1 (I) messenger RNA expression. Further studies in these cells using reverse transcriptase-polymerase chain reaction demonstrated that curcumin had no effect on the expression of PDGF-induced TIMP-1 and TIMP-2, TGFβ1, TGFβ2 and MCP-1 but significantly inhibited tumor necrosis factor alpha expression. Curcumin had no effect on hepatic stellate cells proliferation. Zymography showed that curcumin had no effect on matrix metalloproteinase-2 activity.Conclusions: Curcumin inhibited the development of TAA-induced liver cirrhosis mainly due to its anti-inflammatory activities and not by a direct anti-fibrotic effect. As curcumin ingestion is safe in humans, it may be reasonable to assess in clinical studies the beneficial effect of curcumin in slowing the development of liver cirrhosis.

Cytokines are mediators of cellular communication produced by multiple liver cell types. Cytokines can directly induce either necrosis or apoptosis. They can also recruit such cells as neutrophils and lymphocytes, which can mediate liver damage. Increased levels of hepatotoxic cytokines such as tumor necrosis factor-’are documented in alcoholic liver disease (ALD) and nonalcoholic steatohepatitis (NASH) and have been shown to play a mechanistic role in both of these disease processes. Transforming growth factor-βs a profibrotic cytokine that is critical in hepatic fibrosis. Beneficial cytokines, such as interleukin (IL)-10 and-6, also exist. Such beneficial cytokines as adiponectin are made outside the liver and appear to protect against ALD and NASH. This article reviews the relevance of cytokines in human and experimental forms of liver injury, focusing on modulation of cytokines and the use of beneficial cytokines in treatment and prevention of liver injury in ALD, NASH, and hepatitis C.

Liver synthetic and metabolic function can only be optimised by the growth of cells within a supportive liver matrix. This can be achieved by the utilisation of decellularised human liver tissue. Here we demonstrate complete decellularization of whole human liver and lobes to form an extracellular matrix scaffold with a preserved architecture. Decellularized human liver cubic scaffolds were repopulated for up to 21 days using human cell lines hepatic stellate cells (LX2), hepatocellular carcinoma (Sk-Hep-1) and hepatoblastoma (HepG2), with excellent viability, motility and proliferation and remodelling of the extracellular matrix. Biocompatibility was demonstrated by either omental or subcutaneous xenotransplantation of liver scaffold cubes (5 × 5 × 5 mm) into immune competent mice resulting in absent foreign body responses. We demonstrate decellularization of human liver and repopulation with derived human liver cells. This is a key advance in bioartificial liver development.

Liver fibrosis progresses to cirrhosis in several settings, for example, severe acute alcoholic hepatitis, and hepatitis C virus (HCV) reinfection after liver transplantation. Cirrhosis produces hepatocellular dysfunction, which is also a risk factor for hepatocellular carcinoma. We studied verapamil as a prophylactic, therapeutic antifibrotic drug alone and in combination with silymarin in experimental rat&#39;s liver-induced fibrosis. Liver fibrosis was induced by intra-peritoneal injection of rats with pig serum 0.5ml twice weekly for 6 weeks, which resulted in score three fibrosis. Prophylactic verapamil alone and silymarin alone and a combination of both were administered at the same time of induction of liver fibrosis and continued for the duration of induction. Therapeutic verapamil was started on the last day of fibrosis induction and continued for 4 weeks. The extent of liver fibrosis was evaluated using Ishak&#39;s fibrosis score. Serum alanine aminotransferase (ALT) was m...

Lipopolysaccharide (LPS) is currently considered one of the major players in non-alcoholic fatty liver disease (NAFLD) pathogenesis and progression. Here, we aim to investigate the possible role of LPS-induced TNF-α factor (LITAF) in inducing a pro-inflammatory and pro-fibrogenic phenotype of non-alcoholic steatohepatitis (NASH).We found that children with NAFLD displayed, in different liver-resident cells, an increased expression of LITAF which correlated with histological traits of hepatic inflammation and fibrosis. Total and nuclear LITAF expression increased in mouse and human hepatic stellate cells (HSCs). Moreover, LPS induced LITAF-dependent transcription of IL-1β, IL-6 and TNF-α in the clonal myofibroblastic HSC LX-2 cell line, and this effect was hampered by LITAF silencing. We showed, for the first time in HSCs, that LITAF recruitment to these cytokine promoters is LPS dependent. However, preventing LITAF nuclear translocation by p38MAPK inhibitor, the expression of IL-6 a...

Liver fibrosis is a major cause of liver failure, but treatment remains ineffective. In the present study, we investigated the mechanisms and anti-hepatofibrotic activities of asiatic acid (AA) in a rat model of liver fibrosis induced by carbon tetrachloride (CCl(4)) and in vitro in TGF-beta1-stimulated rat hepatic stellate cell line (HSC-T6). Treatment with AA significantly attenuated CCl(4)-induced liver fibrosis and functional impairment in a dosage-dependent manner, including blockade of the activation of HSC as determined by inhibiting de novo alpha smooth muscle actin (a-SMA) and collagen matrix expression, and an increase in ALT and AST (all p&lt;0.01). The hepatoprotective effects of AA on fibrosis were associated with upregulation of hepatic Smad7, an inhibitor of TGF-beta signaling, thereby blocking upregulation of TGF-beta1 and CTGF and the activation of TGF-beta/Smad signaling. The anti-fibrosis activity and mechanisms of AA were further detected in vitro in HSC-T6. Addi...

Senescence marker protein 30 (SMP30), an important aging marker molecule that is highly expressed in the liver, has been known to protect hepatocytes from apoptosis by the synthesis of vitamin C. To explore the function of SMP30 in liver fibrosis, the effect of SMP30 deficiency on liver fibrosis was investigated in SMP30 knockout (KO) mice. Moreover, the in vivo results were further confirmed by way of hepatic stellate cell (HSC) isolation. We demonstrated that carbon tetrachloride (CCl4)-induced liver fibrosis and the nuclear translocation of p-Smad2/3, the immediate downstream of transforming growth factor beta (TGF-β), were significantly inhibited in the liver of SMP30 KO mice compared with wildtype (WT) mice. We also confirmed that both WT and SMP30 KO HSCs did not express SMP30. Finally, we further confirmed that up-regulation of peroxisome proliferator-activated receptor-gamma (PPAR-γ) caused by a lack of vitamin C was the pivotal factor in the mechanisms for attenuated liver fibrosis of SMP30 KO mice, and feeding with vitamin C restored CCl4-induced liver fibrosis in SMP30 KO mice. Conclusion: Vitamin C deficiency by SMP30 depletion attenuated liver fibrosis by way of up-regulated PPAR-γ expression in SMP30 KO mice. Our results provide, for the first time, the possible mechanisms underlying inhibition of HSC activation associated with vitamin C and PPAR-γ up-regulation in liver fibrosis of SMP30 KO mice. (HEPATOLOGY 2010.)

Histone acetylation and deacetylation have been thought to be related to gene expression, and there are many reports indicating that histone deacetylase inhibitors (HDACis) exert antifibrogenic effects in several organs. In injured livers, hepatic stellate cells (HSCs) are activated in response to profibrogenic mediators and produce large amounts of extracellular matrix. In particular, transforming growth factor-β1 (TGF-β1) is considered as a key factor in accelerating hepatic fibrosis because it is released from activated HSCs and further stimulates them. The present study aimed to clarify whether sodium valproate (VPA) has suppressive effects on cultured human HSCs (LI90). We showed that treatment with VPA had no significantly suppressive effect on cell proliferation at a concentration of 1 mM, which corresponded approximately to the serum concentration obtained by the administration of a clinical dose. However, VPA prevented the morphological changes characteristic for activation...