Atorvastatin inhibits proliferation and apoptosis, but induces senescence in hepatic myofibroblasts and thereby attenuates hepatic fibrosis in rats

Pathophysiology and therapeutic options for cirrhotic portal hypertension

Portal hypertension represents the primary non-neoplastic complication of liver cirrhosis and has life-threatening consequences, such as oesophageal variceal bleeding, ascites, and hepatic encephalopathy. Portal hypertension occurs due to increased resistance of the cirrhotic liver vasculature to portal blood flow and is further aggravated by the hyperdynamic circulatory syndrome. Existing knowledge indicates that the profibrogenic phenotype acquired by sinusoidal cells is the initial factor leading to increased hepatic vascular tone and fibrosis, which cause increased vascular resistance and portal hypertension. Data also suggest that the phenotype of hepatic cells could be further impaired due to the altered mechanical properties of the cirrhotic liver itself, creating a deleterious cycle that worsens portal hypertension in the advanced stages of liver disease. In this Review, we discuss recent discoveries in the pathophysiology and treatment of cirrhotic portal hypertension, a condition with few pharmacological treatment options.

Statins, metformin, and RAS inhibitors did not reduce variceal bleeding risk and mortality in a large, real-life cohort of patients with cirrhosis

BACKGROUND

Previous experimental and clinical studies suggested a beneficial effect of statins, metformin, angiotensin-converting-enzyme inhibitors and angiotensin II receptor blockers (RASi) on portal hypertension. Still, their effects on hard cirrhosis-related clinical endpoints, such as variceal bleeding and bleeding-related mortality, remain to be investigated.

METHODS

Thus, we recorded the use of statins, metformin and RASi in a large cohort of cirrhotic patients undergoing endoscopic band ligation (EBL) for primary (PP, n = 440) and secondary bleeding prophylaxis (SP, n = 480) between 01/2000 and 05/2020. Variceal (re-) bleeding and survival rates were compared between patients with vs. without these co-medications.

RESULTS

A total of 920 cirrhotic patients with varices were included. At first EBL, median MELD was 13 and 515 (56%) patients showed ascites. Statins, metformin and RASi were used by 49 (5.3%), 74 (8%), and 91 (9.9%) patients, respectively. MELD and platelet counts were similar in patients with and without the co-medications of interest. Rates of first variceal bleeding and variceal rebleeding at 2 years were 5.2% and 11.7%, respectively. Neither of the co-medications were associated with decreased first bleeding rates (log-rank tests in PP: statins p = 0.813, metformin p = 0.862, RASi p = 0.919) nor rebleeding rates (log-rank tests in SP: statin p = 0.113, metformin p = 0.348, RASi p = 0.273). Similar mortality rates were documented in patients with and without co-medications for PP (log-rank tests: statins p = 0.630, metformin p = 0.591, RASi p = 0.064) and for SP (statins p = 0.720, metformin p = 0.584, RASi p = 0.118).

CONCLUSION

In clinical practice, variceal bleeding and mortality rates of cirrhotic patients were not reduced by co-medication with statins, metformin or RASi. Nevertheless, we recommend the use of these co-medications by indication, as they may still exert beneficial effects on non-bleeding complications in patients with liver cirrhosis.

Statins in Chronic Liver Disease: Review of the Literature and Future Role

Chronic liver disease (CLD) is a major contributor to global mortality, morbidity, and healthcare burden. Progress in pharmacotherapeutic for CLD management is lagging given its impact on the global population. While statins are indicated for the management of dyslipidemia and cardiovascular disease, their role in CLD prevention and treatment is emerging. Beyond their lipid-lowering effects, their liver-related mechanisms of action are multifactorial and include anti-inflammatory, antiproliferative, and immune-protective effects. In this review, we highlight what is known about the clinical benefits of statins in viral and nonviral etiologies of CLD and hepatocellular carcinoma (HCC), and explore key mechanisms and pathways targeted by statins. While their benefits may span the spectrum of CLD and potentially HCC treatment, their role in CLD chemoprevention is likely to have the largest impact. As emerging data suggest that genetic variants may impact their benefits, the role of statins in precision hepatology will need to be further explored.

Mechanobiology of portal hypertension

The interplay between mechanical stimuli and cellular mechanobiology orchestrates the physiology of tissues and organs in a dynamic balance characterized by constant remodelling and adaptative processes. Environmental mechanical properties can be interpreted as a complex set of information and instructions that cells read continuously, and to which they respond. In cirrhosis, chronic inflammation and injury drive liver cells dysfunction, leading to excessive extracellular matrix deposition, sinusoidal pseudocapillarization, vascular occlusion and parenchymal extinction. These pathological events result in marked remodelling of the liver microarchitecture, which is cause and result of abnormal environmental mechanical forces, triggering and sustaining the long-standing and progressive process of liver fibrosis. Multiple mechanical forces such as strain, shear stress, and hydrostatic pressure can converge at different stages of the disease until reaching a point of no return where the fibrosis is considered non-reversible. Thereafter, reciprocal communication between cells and their niches becomes the driving force for disease progression. Accumulating evidence supports the idea that, rather than being a passive consequence of fibrosis and portal hypertension (PH), mechanical force-mediated pathways could themselves represent strategic targets for novel therapeutic approaches. In this manuscript, we aim to provide a comprehensive review of the mechanobiology of PH, by furnishing an introduction on the most important mechanisms, integrating these concepts into a discussion on the pathogenesis of PH, and exploring potential therapeutic strategies.

Simvastatin inhibits hepatic stellate cells activation by regulating the ferroptosis signaling pathway

BACKGROUND & AIMS

Ferroptosis is a form of regulated cell death and its promotion in hepatic stellate cells (HSCs) attenuates liver fibrosis. Statins, which are 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, may induce ferroptosis via the downregulation of glutathione peroxidase 4 (GPX4) by inhibiting the mevalonate pathway. However, little evidence is available regarding the association between statins and ferroptosis. Therefore, we investigated the association between statins and ferroptosis in HSCs.

METHODS

Two human HSC cell lines, LX-2 and TWNT-1, were treated with simvastatin, an HMG-CoA reductase inhibitor. Mevalonic acid (MVA), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP) were used to determine the involvement of the mevalonate pathway. We performed a detailed analysis of the ferroptosis signaling pathway. We also investigated human liver tissue samples from patients with nonalcoholic steatohepatitis to clarify the effect of statins on GPX4 expression.

RESULTS

Simvastatin reduced cell mortality and inhibited HSCs activation, accompanied by iron accumulation, oxidative stress, lipid peroxidation, and reduced GPX4 protein expression. These results indicate that simvastatin inhibits HSCs activation by promoting ferroptosis. Furthermore, treatment with MVA, FPP, or GGPP attenuated simvastatin-induced ferroptosis. These results suggest that simvastatin promotes ferroptosis in HSCs by inhibiting the mevalonate pathway. In human liver tissue samples, statins downregulated the expression of GPX4 in HSCs without affecting hepatocytes.

CONCLUSIONS

Simvastatin inhibits the activation of HSCs by regulating the ferroptosis signaling pathway.

Neprilysin-dependent neuropeptide Y cleavage in the liver promotes fibrosis by blocking NPY-receptor 1

Development of liver fibrosis is paralleled by contraction of hepatic stellate cells (HSCs), the main profibrotic hepatic cells. Yet, little is known about the interplay of neprilysin (NEP) and its substrate neuropeptide Y (NPY), a potent enhancer of contraction, in liver fibrosis. We demonstrate that HSCs are the source of NEP. Importantly, NPY originates majorly from the splanchnic region and is cleaved by NEP in order to terminate contraction. Interestingly, NEP deficiency (Nep-/-) showed less fibrosis but portal hypertension upon liver injury in two different fibrosis models in mice. We demonstrate the incremental benefit of Nep-/- in addition to AT1R blocker (ARB) or ACE inhibitors for fibrosis and portal hypertension. Finally, oral administration of Entresto, a combination of ARB and NEP inhibitor, decreased hepatic fibrosis and portal pressure in mice. These results provide a mechanistic rationale for translation of NEP-AT1R-blockade in human liver fibrosis and portal hypertension.

Statin-Induced Geranylgeranyl Pyrophosphate Depletion Promotes Ferroptosis-Related Senescence in Adipose Tissue

Statin treatment is accepted to prevent adverse cardiovascular events. However, atorvastatin, an HMG-CoA reductase inhibitor, has been reported to exhibit distinct effects on senescent phenotypes. Whether atorvastatin can induce adipose tissue senescence and the mechanisms involved are unknown. The effects of atorvastatin-induced senescence were examined in mouse adipose tissue explants. Here, we showed that statin initiated higher levels of mRNA related to cellular senescence markers and senescence-associated secretory phenotype (SASP), as well as increased accumulation of the senescence-associated β-galactosidase (SA-β-gal) stain in adipose tissues. Furthermore, we found that the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and Fe²⁺ were elevated in adipose tissues treated with atorvastatin, accompanied by a decrease in the expression of glutathione (GSH), and glutathione peroxidase 4 (GPX4), indicating an iron-dependent ferroptosis. Atorvastatin-induced was prevented by a selective ferroptosis inhibitor (Fer-1). Moreover, supplementation with geranylgeranyl pyrophosphate (GGPP), a metabolic intermediate, reversed atorvastatin-induced senescence, SASP, and lipid peroxidation in adipose tissue explants. Atorvastatin depleted GGPP production, but not Fer-1. Atorvastatin was able to induce ferroptosis in adipose tissue, which was due to increased ROS and an increase in cellular senescence. Moreover, this effect could be reversed by the supplement of GGPP. Taken together, our results suggest that the induction of ferroptosis contributed to statin-induced cell senescence in adipose tissue.

Current and investigational drugs in early clinical development for portal hypertension

Introduction

The development of portal hypertension leads to a majority of complications associated with chronic liver disease. Therefore, adequate treatment of portal hypertension is crucial in the management of such patients. Current treatment options are limited and consist mainly of medications that decrease the hyperdynamic circulation, such as non-selective beta blockers, and treatment of hypervolemia with diuretics. Despite these options, mortality rates have not improved over the last two decades. Newer, more effective treatment options are necessary to help improve survival and quality of life in these patients.

Areas covered

Multiple preclinical models and clinical studies have demonstrated potential efficacy of a variety of new treatment modalities. We introduce treatment options including the use of vasodilation promotors, vasoconstriction inhibitors, anticoagulants, antiangiogenics, and anti-inflammatory drugs. We examine the most recent studies for treatment options within these drug classes and offer insights as to which show the most promise in this field.

Methodology

Published studies that identified novel medical treatment options of portal hypertension were searched using PubMed (https://pubmed.ncbi.nlm.nih.gov/). Clinical trials listed in Clinicaltrials.gov were also searched with a focus on more recent and ongoing studies, including those with completed recruitment. Searching with key terms including "portal hypertension" as well as individually searching specific treatment medications that were listed in other publications was carried out. Finally, current societal guidelines and recent review articles relevant to the management of portal hypertension were evaluated, and listed references of interest were included.

Conclusion

Many ongoing early phase studies demonstrate promising results and may shape the field of portal hypertension management in future. As concrete results become available, larger RCTs will be required before making definitive conclusions regarding safety and efficacy and whether or not they can be incorporated into routine clinical practice. Statins, anticoagulants, and PDE inhibitors have been among the most studied and appear to be most promising.

Myofibroblasts: A key promoter of tumorigenesis following radiofrequency tumor ablation

Radiofrequency ablation (RFA) of intrahepatic tumors induces distant tumor growth through activation of interleukin 6/signal transducer and activator of transcription 3 (STAT3)/hepatocyte growth factor (HGF)/tyrosine-protein kinase Met (c-MET) pathway. Yet, the predominant cellular source still needs to be identified as specific roles of the many types of periablational infiltrating immune cells requires further clarification. Here we report the key role of activated myofibroblasts in RFA-induced tumorigenesis and successful pharmacologic blockade. Murine models simulating RF tumorigenic effects on a macrometastatic tumor and intrahepatic micrometastatic deposits after liver ablation and a macrometastatic tumor after kidney ablation were used. Immune assays of ablated normal parenchyma demonstrated significantly increased numbers of activated myofibroblasts in the periablational rim, as well as increased HGF levels, recruitment other cellular infiltrates; macrophages, dendritic cells and natural killer cells, HGF dependent growth factors; fibroblast growth factor-19 (FGF-19) and receptor of Vascular Endothelial Growth Factor-1 (VEGFR-1), and proliferative indices; Ki-67 and CD34 for microvascular density. Furthermore, macrometastatic models demonstrated accelerated distant tumor growth at 7d post-RFA while micrometastatic models demonstrated increased intrahepatic deposit size and number at 14 and 21 days post-RFA. Multi-day atorvastatin, a selective fibroblast inhibitor, inhibited RFA-induced HGF and downstream growth factors, cellular markers and proliferative indices. Specifically, atorvastatin treatment reduced cellular and proliferative indices to baseline levels in the micrometastatic models, however only partially in macrometastatic models. Furthermore, adjuvant atorvastatin completely inhibited accelerated growth of macrometastasis and negated increased micrometastatic intrahepatic burden. Thus, activated myofibroblasts drive RF-induced tumorigenesis at a cellular level via induction of the HGF/c-MET/STAT3 axis, and can be successfully pharmacologically suppressed.

Pleiotropic Long-Term Effects of Atorvastatin on Posttraumatic Joint Contracture in a Rat Model

The antifibrotic effect of atorvastatin has already been demonstrated in several organ systems. In the present study, a rat model was used to investigate the effect of atorvastatin on posttraumatic joint contracture. Forty-eight Sprague Dawley rats were equally randomized into an atorvastatin group and a control group. After initial joint trauma, knee joints were immobilized for intervals of 2 weeks (n = 16) or 4 weeks (n = 16) or immobilized for 4 weeks with subsequent remobilization for another 4 weeks (n = 16). Starting from the day of surgery, animals received either atorvastatin or placebo daily. After euthanasia at week 2, 4 or 8, joint contracture was determined, histological examinations were performed, and gene expression was assessed. The results suggest that the joint contracture was primarily arthrogenic. Atorvastatin failed to significantly affect contracture formation and showed a reduction in myofibroblast numbers to 98 ± 58 (control: 319 ± 113, p < 0.01) and a reduction in joint capsule collagen to 60 ± 8% (control: 73 ± 9%, p < 0.05) at week 2. Gene expression of α-smooth muscle actin (α-SMA), collagen type I, transforming growth factor β1 (TGF-β1) and interleukin-6 (IL-6) was not significantly affected by atorvastatin. Atorvastatin decreases myofibroblast number and collagen deposition but does not result in an improvement in joint mobility.

Liver Fibrosis-From Mechanisms of Injury to Modulation of Disease

The Transregional Collaborative Research Center "Organ Fibrosis: From Mechanisms of Injury to Modulation of Disease" (referred to as SFB/TRR57) was funded for 13 years (2009-2021) by the German Research Council (DFG). This consortium was hosted by the Medical Schools of the RWTH Aachen University and Bonn University in Germany. The SFB/TRR57 implemented combined basic and clinical research to achieve detailed knowledge in three selected key questions: (i) What are the relevant mechanisms and signal pathways required for initiating organ fibrosis? (ii) Which immunological mechanisms and molecules contribute to organ fibrosis? and (iii) How can organ fibrosis be modulated, e.g., by interventional strategies including imaging and pharmacological approaches? In this review we will summarize the liver-related key findings of this consortium gained within the last 12 years on these three aspects of liver fibrogenesis. We will highlight the role of cell death and cell cycle pathways as well as nutritional and iron-related mechanisms for liver fibrosis initiation. Moreover, we will define and characterize the major immune cell compartments relevant for liver fibrogenesis, and finally point to potential signaling pathways and pharmacological targets that turned out to be suitable to develop novel approaches for improved therapy and diagnosis of liver fibrosis. In summary, this review will provide a comprehensive overview about the knowledge on liver fibrogenesis and its potential therapy gained by the SFB/TRR57 consortium within the last decade. The kidney-related research results obtained by the same consortium are highlighted in an article published back-to-back in Frontiers in Medicine.

Addition of statins to the standard treatment in patients with cirrhosis: Safety and efficacy

This review summarizes the safety and efficacy of statins in patients with cirrhosis. Due to concerns about the safety of statins in patients with impaired liver function, they have recently been investigated as a potential treatment option in cirrhosis. The most clinically significant adverse event is statin-related myopathy, and this may be related to the high serum statin concentrations in the setting of severely impaired liver function. Rhabdomyolysis is the most serious and potentially life-threatening manifestation. It has recently been demonstrated that the recommended dose of simvastatin in patients with decompensated cirrhosis would be 20 mg/d because higher values, such as 40 mg/d, are associated with many adverse events, especially muscle injury. Likewise, simvastatin should not be administered to patients with Model for End-stage Liver Disease score > 12 and/or Child-Pugh class C because of the high risk of severe muscle injury. Due to the pleiotropic effects, the focus on statins has shifted from being considered harmful to something useful. Through these effects, statins could prevent liver-related morbidity and mortality in cirrhotic patients. Observational studies in large populations of patients with cirrhosis have shown that treatment with statins to decrease high cholesterol levels was associated with a reduced risk of hepatic decompensation, hepatocellular carcinoma development and death. The few randomized controlled trials in patients with cirrhosis and portal hypertension showed that statins lower portal pressure, quite likely through a reduction in hepatic resistance. Another large randomized controlled trial in patients with variceal bleeding showed that simvastatin in addition to standard of care did not prevent rebleeding but improved survival rate. Despite these encouraging outcomes, the quality of the evidence regarding the use of statins is low or very low due to the observational characteristics of most of the studies involved. Therefore, it is advisable to perform further randomized controlled trials on a large series of patients with hard clinical endpoints, using different statin types and varying doses. The objectives would be to prevent liver-related morbidity and mortality rather than treating cirrhosis complications to take additional information that makes it possible to add statins to the standard of care of these patients.

Liver stiffness across different chronic liver disease under therapy with statin in a real life cohort

INTRODUCTION

Statins have been associated with improved clinical outcomes in patients with viral hepatitis and after variceal bleeding. Still, the clinical benefit of statins is not well defined for different liver diseases. Moreover, associations between statin use and liver stiffness as well as event free survival have not been established.

METHODS

Liver stiffness was evaluated in 6490 patients with liver disease (January 2012 till December 2016). Two hundred thirty-four of those received statin therapy, 468 controls without statins were selected by a 1:2 case by case matching using age, sex, underlying liver disease and BMI.

RESULTS

Statins were given to 234 patients with chronic virus hepatitis (n = 104), nonalcoholic fatty liver disease (n = 52), autoimmune liver disease including autoimmune hepatitis, primary biliary cholangitis and primary sclerosing cholangitis (n = 31) and hepatitis of unknown origin (n = 47). Follow-up data were available for 96 and 119 pairs (mean follow-up 2 years). Statin users showed reduced inflammatory activity. Elevated liver enzymes were reported in 57% of statin-treated compared with 70% of controls (mean alanine aminotransferase level 53 vs. 74 U/l; P < 0.001). Statin use was well tolerated in this cohort. Mean liver stiffness values were 10.7 kPa (SEM 0.7) and 15.5 kPa (SEM 0.7) accordingly (P < 0.0001). Decompensation was less likely to occur in the statin group, both groups do not defer in the incidence of liver tumor occurrence, transplantation or death (odds ratio = 1, P = nonsignificant).

CONCLUSIONS

Use of statins was well tolerated irrespective of liver disease. Statin users showed reduced hepatic inflammatory activity, less severe markers of liver stiffness and portal hypertension. There might be a beneficial effect of statin on the risk to experience hepatic decompensation.

Combination of phosphodiesterase-5-inhibitors and beta blockers improves experimental portal hypertension and erectile dysfunction

BACKGROUND & AIMS

Phosphodiesterase-5 inhibitors (PDE-5-I) are used for treatment of erectile dysfunction (ED), which is common in patients with cirrhosis. They may improve portal hypertension (PH), but contradictory data on efficacy and side-effects have been reported. Non-selective beta blockers (NSBB) reduce portal pressure, but might aggravate ED. Thus, we evaluated the combination of PDE-5-I with NSBB and its impact on PH and ED in experimental cirrhosis.

METHODS

ED was assessed in cirrhotic patients (n = 86) using standardized questionnaire. Experimental cirrhosis was induced by bile-duct-ligation or carbon-tetrachloride intoxication in rats. Corpus cavernosum pressure - a surrogate of ED -, as well as systemic and portal haemodynamics, were measured in vivo and in situ after acute administration of udenafil alone or in combination with propranolol. mRNA and protein levels of PDE-5 signalling were analysed using PCR and western Blot.

RESULTS

ED in humans was related to severity of liver disease and to NSBB treatment. PDE-5 was mainly expressed in hepatic stellate cells and upregulated in human and experimental cirrhosis. Propranolol reduced corpus cavernosum pressure in cirrhotic rats and it was restored by udenafil. Even though udenafil treatment improved PH, it led to a reduction of mean arterial pressure. The combination of udenafil and propranolol reduced portal pressure and hepatic resistance without systemic side-effects.

CONCLUSIONS

ED is common with advanced cirrhosis and concomitant NSBB treatment. The combination of PDE-5-I and NSBB improves ED and PH in experimental cirrhosis.

The preventive effect of atorvastatin on liver fibrosis in the bile duct ligation rats via antioxidant activity and down-regulation of Rac1 and NOX1

Objectives

Atorvastatin is a cholesterol-lowering agent capable of inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase. Recent studies have demonstrated new facets of atorvastatin, such as antioxidant and anti-fibrotic properties. We investigated the effect of atorvastatin on hepatic injury via the measurement of the antioxidant capacity and protein expression of NOX1, Rac1-GTP, and Rac1 in a rat biliary duct ligation (BDL) model.

Materials and Methods

This study is regarded as experimental interventional research in which a total of 32 adult male Wistar rats (200-250 g) were assigned to 4 groups (eight rats per group) as follows: Control group; Control + At group (15 mg\kg\day atorvastatin); BDL group, and BDL+ At group (15 mg\kg\day atorvastatin). Expression levels of Rac1, NOX1, and Rac1-GTP were determined by western blot analysis. Besides, specific biomarkers of oxidative stress in hepatic tissues of all animals were also analyzed.

Results

Atorvastatin reduced liver injury via a decrease in the expression of NOX1, Rac1-GTP, and Rac1 in the BDL group (P<0.05), while the increased contents of protein thiol groups were observed, and the protein carbonylation was decreased in atorvastatin-treated BDL rats compared to the BDL group (P<0.05). Also, administration of atorvastatin in the BDL group significantly lowered oxidative stress through increasing the activity of catalase and superoxide dismutase in comparison with the BDL group (P<0.05).

Conclusion

It seems that atorvastatin has potential advantages in mitigation of liver fibrosis by a decrease in the expression of NOX1, Rac1-GTP, and Rac1, along with, a reduction in oxidative stress of liver tissues in rats induced by BDL.

Atorvastatin-induced senescence of hepatocellular carcinoma is mediated by downregulation of hTERT through the suppression of the IL-6/STAT3 pathway

Hepatocellular carcinoma (HCC), a hepatic malignancy, has a poor prognosis and contributes to cancer-related death worldwide. Cellular senescence is an anticancer therapeutic strategy that causes irreversible cell cycle arrest and enables immune-mediated clearance of cancer cells. Atorvastatin, an HMG-CoA reductase inhibitor, has been shown to inhibit tumor growth and induce apoptosis or autophagy in malignant tumors. However, whether atorvastatin can induce HCC cell senescence and the mechanisms involved are poorly understood. The effects of atorvastatin-induced senescence were examined in both HCC cells and mouse xenograft models. The phenomenon and mechanism of senescence were examined by cell cycle analysis, senescence-associated β-galactosidase (SA-β-gal) staining and western blotting in HCC cells, and HCC tissues from mice were analyzed by immunohistochemical (IHC) staining. We demonstrated that atorvastatin induced cell growth inhibition and G0/G1 phase cell cycle arrest, leading to senescence in HCC cells. Atorvastatin-induced senescence was independent of p53, p14, and p16, and atorvastatin not only decreased the secretion of IL-6, a major senescence-associated secretory phenotype (SASP) factor, and the phosphorylation of STAT3 but also inhibited the expression of hTERT, a catalytic subunit of telomerase. Supplementation with exogenous IL-6 reversed both atorvastatin-induced suppression of STAT3 phosphorylation and hTERT expression and atorvastatin-induced senescence. Overexpression of constitutively activated STAT3 rescued HCC cells from atorvastatin-induced hTERT suppression and senescence. Moreover, atorvastatin decreased tumor growth in mouse xenograft models. Consistent with these results, atorvastatin decreased the IL-6, p-STAT3, and hTERT levels and increased β-gal expression in tumor sections. Taken together, these data indicate that atorvastatin can induce atypical cellular senescence in HCC cells to inhibit tumor growth, an effect mediated by downregulation of hTERT through suppression of the IL-6/STAT3 pathway.

The potential role of senescence in limiting fibrosis caused by aging

Fibrosis-related diseases carry with them a high mortality rate and their morbidity increases with age. Recent findings indicate that induced senescence in myofibroblasts can limit or reduce myocardial fibrosis, cirrhosis, and idiopathic pulmonary fibrosis, while also accelerating wound healing. However, more senescent cells are accumulated as organisms age, which exacerbates aging-related diseases. These two contradictory theories inspired us to summarize papers on the restrictive effect of senescence on fibrosis and to input the key findings into simple software that we developed to assist with data organization and presentation. In this review, we illustrate that senescent cells secrete more matrix metalloproteinases to solubilize excess collagen, while chemokines and cytokines activate immune cells to eliminate senescent cells. In the elderly, it is perhaps more effective to limit fibrosis by inducing myofibroblast senescence and then removing senescent cells that are not cleared via normal mechanisms by antisenescence therapies.

Increasing the effectiveness of tyrosine kinase inhibitor (TKI) in combination with a statin in reducing liver fibrosis

It has been shown that both nilotinib as a tyrosine kinase inhibitor, and atorvastatin as a rho-kinase inhibitor, have antifibrotic effects. Therefore, considering the relationship between these two pathways, this study aimed to investigate the effects of their co-treatment against hepatic stellate cells (HSCs) activation and liver fibrosis. For this purpose, the activation of HSCs coincided with these therapies. Also, liver fibrosis by carbon tetrachloride (CCl₄ ) was induced in male Wistar rats and treated simultaneously with these compounds. The expression of alpha-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), Ras homolog gene family, and member A (RhoA)/Rho-associated protein kinase (ROCK) in HSCs were measured. The expression of transforming growth factor beta-1 (TGF-β1), its receptor (TβRII), CTGF, and platelets derived growth factor (PDGF), in the livers, were also investigated, all by real-time PCR and western blot analysis. Also, histopathologic and immunohistochemical evaluations were performed to evaluate changes in liver fibrosis during treatment. The results indicated the down-regulation of RhoA/ROCK, CTGF, and α-SMA, and inhibition of the HSCs activation toward myofibroblasts. The results also showed that the combined use of atorvastatin and nilotinib has significantly higher inhibitory effects. The antifibrotic effects of atorvastatin and nilotinib co-administration were also observed by histopathologic and immunohistochemical observations, and inhibiting the expression of TGF-β1, TβRII, CTGF, and PDGF. Taken together, this study revealed that co-administration of nilotinib-atorvastatin has novel antifibrotic effects, by inhibiting RhoA/ROCK, and CTGF pathway. Therefore, the importance of the common pathway of RhoA/ROCK and CTGF, in reducing fibrosis may almost be concluded.

Effects of losartan and atorvastatin on the development of early posttraumatic joint stiffness in a rat model

BACKGROUND

After a trauma, exuberant tissue healing with fibrosis of the joint capsule can lead to posttraumatic joint stiffness (PTJS). Losartan and atorvastatin have both shown their antifibrotic effects in different organ systems.

OBJECTIVE

The purpose of this study was the evaluation of the influence of losartan and atorvastatin on the early development of joint contracture. In addition to joint angles, the change in myofibroblast numbers and the distribution of bone sialoprotein (BSP) were assessed.

STUDY DESIGN AND METHODS

In this randomized and blinded experimental study with 24 rats, losartan and atorvastatin were compared to a placebo. After an initial joint injury, rat knees were immobilized with a Kirschner wire. Rats received either losartan, atorvastatin or a placebo orally daily. After 14 days, joint angle measurements and histological assessments were performed.

RESULTS

Losartan increased the length of the inferior joint capsule. Joint angle and other capsule length measurements did not reveal significant differences between both drugs and the placebo. At cellular level both losartan and atorvastatin reduced the total number of myofibroblasts (losartan: 191±77, atorvastatin: 98±58, placebo: 319±113 per counting field, p<0.01) and the percentage area of myofibroblasts (losartan: 2.8±1.8% [p<0.05], atorvastatin: 2.5±1.7% [p<0.01], vs control [6.4±4%], respectively). BSP was detectable in equivalent amounts in the joint capsules of all groups with only a trend toward a reduction of the BSP-stained area by atorvastatin.

CONCLUSION

Both atorvastatin and losartan reduced the number of myofibroblasts in the posterior knee joint capsule of rat knees 2 weeks after trauma and losartan increased the length of the inferior joint capsule. However, these changes at the cellular level did not translate an increase in range of motion of the rats´ knee joints during early contracture development.

Potential Molecular Targets of Statins in the Prevention of Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) represents 90% of liver tumors. Statins, may reduce the incidence of various tumors, including HCC. Antitumoral activities may be mediated by changes in transforming growth factor-beta (TGF-β1) and thyroid hormones (TH) regulation.

INTRODUCTION AND AIM

Hepatocellular carcinoma (HCC) represents 90% of liver tumors. Statins, may reduce the incidence of various tumors, including HCC. Antitumoral activities may be mediated by changes in transforming growth factor-beta (TGF-β1) and thyroid hormones (TH) regulation. Aim. The aim of our study is to establish the statins mechanism of action and the potential key molecules involved in an in vivo and in vitro HCC model.

MATERIALS AND METHODS

We used two models: in vivo (in rats) using diethylnitrosamine (DEN) and hexachlorobenzene (HCB) to develop HCC. We analyzed cell proliferation parameters (proliferating cel nuclear antigen, PCNA) and cholesterol metabolism (hydroxy-methylglutaryl-CoA reductase, HMGCoAR). In vitro (Hep-G2 cells) we evaluated the effects of different doses of Atorvastatin (AT) and Simvastatin (SM) on HCB induced proliferation and analyzed proliferative parameters, cholesterol metabolism, TGF-β1 mRNA, c-Src and TH levels.

RESULTS

In vivo, we observed that cell proliferation significantly increased as well as cholesterol serum levels in rats treated with HCB. In vitro, we observed the same results on PCNA as in vivo. The statins prevented the increase in HMG-CoAR mRNA levels induced by HCB, reaching levels similar to controls at maximum doses: AT (30 μM), and SM (20 μM). Increases in PCNA, TGF-β1, and pc-Src, and decreases in deiodinase I mRNA levels induced by HCB were not observed when cells were pre-treated with AT and SM at maximum doses.

CONCLUSION

Statins can prevent the proliferative HCB effects on Hep-G2 cells. TGF-β1, c-Src and TH may be the statins molecular targets in hepatocarcinogenesis.

Effects of apoptosis on liver aging

As an irreversible and perennial process, aging is accompanied by functional and morphological declines in organs. Generally, aging liver exhibits a decline in volume and hepatic blood flow. Even with a preeminent regenerative capacity to restore its functions after liver cell loss, its biosynthesis and metabolism abilities decline, and these are difficult to restore to previous standards. Apoptosis is a programmed death process via intrinsic and extrinsic pathways, in which Bcl-2 family proteins and apoptosis-related genes, such as p21 and p53, are involved. Apoptosis inflicts both favorable and adverse influences on liver aging. Apoptosis eliminates transformed abnormal cells but promotes age-related liver diseases, such as nonalcoholic fatty liver disease, liver fibrosis, cirrhosis, and liver cancer. We summarize the roles of apoptosis in liver aging and age-related liver diseases.

Statins: Old drugs as new therapy for liver diseases?

In addition to lowering cholesterol levels, statins have pleiotropic effects, particularly anti-inflammatory, antiangiogenic, and antifibrotic, that may be beneficial in some chronic inflammatory conditions. Statins have only recently been investigated as a potential treatment option in chronic liver diseases because of concerns related to their safety in patients with impaired liver function. A number of experimental studies in animal models of liver diseases have shown that statins decrease hepatic inflammation, fibrogenesis and portal pressure. In addition, retrospective cohort studies in large populations of patients with cirrhosis and pre-cirrhotic conditions have shown that treatment with statins, with the purpose of decreasing high cholesterol levels, was associated with a reduced risk of disease progression, hepatic decompensation, hepatocellular carcinoma development, and death. These beneficial effects persisted after adjustment for disease severity and other potential confounders. Finally, a few randomised controlled trials have shown that treatment with simvastatin decreases portal pressure (two studies) and mortality (one study). Statin treatment was generally well tolerated but a few patients developed severe side effects, particularly rhabdomyolysis. Despite these promising beneficial effects, further randomised controlled trials in large series of patients with hard clinical endpoints should be performed before statins can be recommended for use in clinical practice.

Advances in therapeutic options for portal hypertension

Portal hypertension represents one of the major clinical consequences of chronic liver disease, having a deep impact on patients' prognosis and survival. Its pathophysiology defines a pathological increase in the intrahepatic vascular resistance as the primary factor in its development, being subsequently aggravated by a paradoxical increase in portal blood inflow. Although extensive preclinical and clinical research in the field has been developed in recent decades, no effective treatment targeting its primary mechanism has been defined. The present review critically summarizes the current knowledge in portal hypertension therapeutics, focusing on those strategies driven by the disease pathophysiology and underlying cellular mechanisms.

The multikinase inhibitor regorafenib decreases angiogenesis and improves portal hypertension

Background and Aims

Angiogenesis is critically involved in the development of liver fibrosis, portal hypertension (PHT) and hepatocellular carcinoma (HCC). Regorafenib is a novel second-line therapy for HCC, but might also be beneficial in fibrosis and PHT even in absence of HCC. This study investigated the effects of regorafenib in experimental models without HCC.

Methods

Fibrosis (in vivo and in vitro), inflammation, liver damage (aminotransferases), angiogenesis (matrigel implantation) and in vivo systemic and portal hemodynamics were assessed in different mouse and rat models (bile duct ligation, CCl₄, partial portal vein ligation) after acute and chronic treatment with regorafenib.

Results

Long-term treatment with regorafenib improved portal hypertension most likely due to blunted angiogenesis, without affecting fibrosis progression or regression. Interestingly, acute administration of regorafenib also ameliorated portal hemodynamics. Although regorafenib treatment led to hepatotoxic side effects in long-term treated fibrotic animals, in partial portal vein ligated rats, no liver toxicity due to regorafenib was observed.

Discussion

Regorafenib might be especially suitable as therapy in patients with PHT and preserved liver function.

Role of Metabolism in Hepatic Stellate Cell Activation and Fibrogenesis

Activation of hepatic stellate cell (HSC) involves the transition from a quiescent to a proliferative, migratory, and fibrogenic phenotype (i.e., myofibroblast), which is characteristic of liver fibrogenesis. Multiple cellular and molecular signals which contribute to HSC activation have been identified. This review specially focuses on the metabolic changes which impact on HSC activation and fibrogenesis.

The Secretin/Secretin Receptor Axis Modulates Ductular Reaction and Liver Fibrosis through Changes in Transforming Growth Factor-β1-Mediated Biliary Senescence

Activation of the secretin (Sct)/secretin receptor (SR) axis stimulates ductular reaction and liver fibrosis, which are hallmarks of cholangiopathies. Our aim was to define the role of Sct-regulated cellular senescence, and we demonstrated that both ductular reaction and liver fibrosis are significantly reduced in Sct-/-, SR-/-, and Sct-/-/SR-/- bile duct ligated (BDL) mice compared with BDL wild-type mice. The reduction in hepatic fibrosis in Sct-/-, SR-/-, and Sct-/-/SR-/- BDL mice was accompanied by reduced transforming growth factor-β1 levels in serum and cholangiocyte supernatant, as well as decreased expression of markers of cellular senescence in cholangiocytes in contrast to enhanced cellular senescence in hepatic stellate cells compared with BDL wild-type mice. Secretin directly stimulated the senescence of cholangiocytes and regulated, by a paracrine mechanism, the senescence of hepatic stellate cells and liver fibrosis via modulation of transforming growth factor-β1 biliary secretion. Targeting senescent cholangiocytes may represent a novel therapeutic approach for ameliorating hepatic fibrosis during cholestatic liver injury.

linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin

The biologic roles of long noncoding RNAs (lncRNAs) in liver fibrosis remained unknown. Through microarray analysis, linc-SCRG1 (a lncRNA with transcript length 3118 bp) was found up-regulated 13.62-fold in human cirrhotic tissues. Quantitative PCR verified that linc-SCRG1 increased along with liver fibrosis progression in human tissues and in activated LX2 cells induced by TGF-β1. Knockdown of linc-SCRG1 significantly reversed the effects of TGF-β1 on LX2, including inhibiting activation, promoting apoptosis, reducing proliferation, lessening invasion, and down-regulating genes [fibrosis-related mRNA: α-smooth muscle actin ( α-SMA), type I collagen, and B-cell lymphoma-2; invasion-related mRNA: matrix metallopeptidase-2 ( MMP-2), MMP-9, and MMP-13; inflammation-related mRNA: TNF-α, IL-6, and IL-10]. linc-SCRG1 had binding sites with tristetraprolin (TTP), a kind of RNA-binding protein, and specifically combined to TTP proteins. Overexpression of linc-SCRG1 would cause TTP mRNA unstably and proteins decreasing. TTP mRNA was proved having negative relevance with linc-SCRG1 and was gradually reduced during human liver fibrosis progression. Overexpressing TTP resulted in knockdown of lincSCRG1 and degraded downstream target genes ( MMP-2 and TNF-α) in activated LX2. Overexpressing TTP had the same effects as small interfering RNA-lincSCRG1 (si- lincSCRG1), whereas knockdown of TTP had reversal effects on si- lincSCRG1 in activated LX2. In summary, linc-SCRG1 reduced TTP and restricted its degradation of target genes TNF-α and MMP-2. Therefore, linc-SCRG1 had a repressing TTP-elicited inactivation effect on hepatic stellate cell (HSC) phenotypes. Inhibition of linc-SCRG1 may be a novel therapeutic approach to inactivate HSCs and extenuate human liver fibrosis.-Wu, J.-C., Luo, S.-Z., Liu, T., Lu, L.-G., Xu, M.-Y. linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin.

Managing portal hypertension in patients with liver cirrhosis

Portal hypertension is one cause and a part of a dynamic process triggered by chronic liver disease, mostly induced by alcohol or incorrect nutrition and less often by viral infections and autoimmune or genetic disease. Adequate staging - continuously modified by current knowledge - should guide the prevention and treatment of portal hypertension with defined endpoints. The main goals are interruption of etiology and prevention of complications followed, if necessary, by treatment of these. For the past few decades, shunts, mostly as intrahepatic stent bypass between portal and hepatic vein branches, have played an important role in the prevention of recurrent bleeding and ascites formation, although their impact on survival remains ambiguous. Systemic drugs, such as non-selective beta-blockers, statins, or antibiotics, reduce portal hypertension by decreasing intrahepatic resistance or portal tributary blood flow or by blunting inflammatory stimuli inside and outside the liver. Here, the interactions among the gut, liver, and brain are increasingly examined for new therapeutic options. There is no general panacea. The interruption of initiating factors is key. If not possible or if not possible in a timely manner, combined approaches should receive more attention before considering liver transplantation.

Acute decompensation boosts hepatic collagen type III deposition and deteriorates experimental and human cirrhosis

Patients with end-stage liver disease develop acute decompensation (AD) episodes, which become more frequent and might develop into acute-on-chronic liver failure (ACLF). However, it remains unknown how AD induces acceleration of liver disease. We hypothesized that remodeling of collagen type III plays a role in the acceleration of liver cirrhosis after AD and analyzed its formation (Pro-C3) and degradation (matrix metalloproteinase-degraded type III collagen [C3M]) markers in animal models and human disease. Bile duct ligation induced different stages of liver fibrosis in rats. Fibrosis development (hydroxyprolin content, sirius red staining, α-smooth muscle actin immunohistochemistry, messenger RNA of profibrotic cytokines), necroinflammation (aminotransferases levels), fibrolysis (matrix metalloproteinase 2 expression and activity, C1M, C4M), and Pro-C3 and C3M were analyzed 2, 3, 4, 5, and 6 weeks after bile duct ligation (n = 5 each group). In 110 patients with decompensated liver cirrhosis who underwent a transjugular intrahepatic portosystemic shunt procedure for AD, clinical and laboratory parameters as well as Pro-C3 and C3M were measured in blood samples from portal and hepatic veins and were collected just before the transjugular intrahepatic portosystemic shunt placement and 1-3 weeks later. Animal studies showed increased markers of collagen type III deposition with fibrosis, necroinflammation, and decompensation of liver cirrhosis, defined as ascites development. Higher Pro-C3 levels were associated with injury, disease severity scores (Model for End-Stage Liver Disease, Child-Pugh, chronic liver failure-C AD), ACLF development, and mortality. C3M decreased with AD and the chronic liver failure-C AD score. Collagen type III deposition ratio increased with the risk of ACLF development and mortality. Conclusion: We show for the first time that AD boosts collagen type III deposition in experimental and human cirrhosis, possibly contributing to the worsened outcome in patients with decompensated cirrhosis. (Hepatology Communications 2018;2:211-222).

Hepatic stellate cells as key target in liver fibrosis

Progressive liver fibrosis, induced by chronic viral and metabolic disorders, leads to more than one million deaths annually via development of cirrhosis, although no antifibrotic therapy has been approved to date. Transdifferentiation (or "activation") of hepatic stellate cells is the major cellular source of matrix protein-secreting myofibroblasts, the major driver of liver fibrogenesis. Paracrine signals from injured epithelial cells, fibrotic tissue microenvironment, immune and systemic metabolic dysregulation, enteric dysbiosis, and hepatitis viral products can directly or indirectly induce stellate cell activation. Dysregulated intracellular signaling, epigenetic changes, and cellular stress response represent candidate targets to deactivate stellate cells by inducing reversion to inactivated state, cellular senescence, apoptosis, and/or clearance by immune cells. Cell type- and target-specific pharmacological intervention to therapeutically induce the deactivation will enable more effective and less toxic precision antifibrotic therapies.

Use of Statins in Patients with Chronic Liver Disease and Cirrhosis: Current Views and Prospects

PURPOSE OF REVIEW

The purpose of this study is to analyze the current evidence regarding the use of statins in patients with chronic liver disease and cirrhosis.

RECENT FINDINGS

Chronic liver disease (CLD), cirrhosis, and its complications, including hepatocellular carcinoma (HCC), are significant public health problems. The use of statins in patients with CLD has been a matter of concern, and physicians are often reluctant to its prescription in these patients. This mainly relates to the potential occurrence of drug-induced liver injury. However, newer evidence from pre-clinical and clinical research has shown that statins are drugs with a potentially beneficial impact on the natural history of cirrhosis, on portal hypertension, and in HCC prevention. In this review, we summarize current evidence regarding the influence of statins in endothelial dysfunction in CLD, their ability to modulate hepatic fibrogenesis, and their vasoprotective effects in portal hypertension; we also focus on existing data about the impact of statins in cirrhosis development, progression, and complications and critically assess the current concerns about its use in patients with CLD.

Beneficial Effects of Statins on the Rates of Hepatic Fibrosis, Hepatic Decompensation, and Mortality in Chronic Liver Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

Statins may improve outcomes in patients with chronic liver disease (CLD). We conducted a systematic review and meta-analysis to evaluate the impact of statins in the setting of CLD.

METHODS

We searched several databases from inception to 17 October 2016 to identify comparative studies evaluating the role of statins in CLD. Outcomes of interest were the associations between statin use and progression of fibrosis, development of hepatic decompensation in cirrhosis, and mortality in CLD. Adjusted hazard ratios (HRs) were pooled and analyzed using a random effects model. Subgroup analyses were performed based on the method of detection for progression of hepatic fibrosis and quality of studies.

RESULTS

We included 10 studies (1 randomized controlled trial and 9 observational) with 259,453 patients (54,441 statin users and 205,012 nonusers). For progression of hepatic fibrosis, pooled HR (95% confidence interval) was 0.49 (0.39-0.62). On subgroup analysis of studies using ICD-9 (The International Classification of Diseases, Ninth Revision) coding and a second method to detect cirrhosis, pooled HR was 0.58 (0.51-0.65); pooled HR for studies using ICD-9 coding only was 0.36 (0.29-0.44). For progression of fibrosis in patients with hepatitis C virus (HCV) infection, pooled HR was 0.52 (0.37-0.73). For hepatic decompensation in cirrhosis, pooled HR was 0.54 (0.46-0.65). For mortality, pooled HR based on observational studies was 0.67 (0.46-0.98); in the randomized controlled trial, HR was 0.39 (0.15-0.99). However, the quality of evidence for these associations is low as most included studies were retrospective in nature and limited by residual confounding.

CONCLUSIONS

Statins may retard the progression of hepatic fibrosis, may prevent hepatic decompensation in cirrhosis, and may reduce all-cause mortality in patients with CLD. As the quality (certainty) of evidence is low, further studies are needed before statins can be routinely recommended.

Statin use and virus-related cirrhosis: A systemic review and meta-analysis

BACKGROUND/OBJECTIVES

Liver cirrhosis and its complications are important factors contributing to mortality worldwide. Statin use is probably associated with lower risk of hepatic decompensation and mortality, but not with cirrhosis or fibrosis progression according to a recent systematic review. We aimed to evaluate the definite effects of statins on the risk of virus-related cirrhosis.

METHODS

We systematically searched four databases up to May 7, 2017, without language restriction. Studies were included if they evaluated and clearly defined exposure to statins, reported fibrosis progression, risk of cirrhosis in patients with chronic viral hepatitis or decompensation in cirrhotic patients, and reported relative risks (RRs) or odds ratios (ORs), or provided data for their estimation. Pooled RRs (or ORs) with 95% confidence intervals were calculated using the random-effects models irrespective of statistical heterogeneity assessed with the Cochran's Q statistic and I² statistic.

RESULTS

Ten observational studies involving 12,3445 patients (8 cohort studies, n=12,1823; 1 nested case-control, n=1350; and 1 abstract, n=272) were included. Statin use was associated with a statistically significant 51% reduction in the risk of virus-related cirrhosis (pooled RRs, 0.49; 95% CI, 0.30-0.80; P=0.004), with substantial heterogeneity (I²=98.3%; P<0.001). Statin use was also associated with a 51% reduction in the risk of decompensation (pooled RRs, 0.49; 95% CI, 0.41-0.59; P<0.001), which was statistically significant, with no heterogeneity (I²=33.8%; P=0.210).

CONCLUSIONS

The meta-analysis showed that statin use was associated with a significantly reduced risk of virus-related cirrhosis and decompensation. However, these results should be interpreted with caution given the possibility of residual confounding. Large randomized controlled trials are warranted in future studies.

Liraglutide improves liver microvascular dysfunction in cirrhosis: Evidence from translational studies

Hepatic stellate cells (HSC) play a key role in the development of chronic liver disease (CLD). Liraglutide, well-established in type 2 diabetes, showed anti-inflammatory and anti-oxidant properties. We evaluated the effects of liraglutide on HSC phenotype and hepatic microvascular function using diverse pre-clinical models of CLD. Human and rat HSC were in vitro treated with liraglutide, or vehicle, and their phenotype, viability and proliferation were evaluated. In addition, liraglutide or vehicle was administered to rats with CLD. Liver microvascular function, fibrosis, HSC phenotype and sinusoidal endothelial phenotype were determined. Additionally, the effects of liraglutide on HSC phenotype were analysed in human precision-cut liver slices. Liraglutide markedly improved HSC phenotype and diminished cell proliferation. Cirrhotic rats receiving liraglutide exhibited significantly improved liver microvascular function, as evidenced by lower portal pressure, improved intrahepatic vascular resistance, and marked ameliorations in fibrosis, HSC phenotype and endothelial function. The anti-fibrotic effects of liraglutide were confirmed in human liver tissue and, although requiring further investigation, its underlying molecular mechanisms suggested a GLP1-R-independent and NF-κB-Sox9-dependent one. This study demonstrates for the first time that liraglutide improves the liver sinusoidal milieu in pre-clinical models of cirrhosis, encouraging its clinical evaluation in the treatment of chronic liver disease.

Double Knockdown of PHD1 and Keap1 Attenuated Hypoxia-Induced Injuries in Hepatocytes

Background and Aims: Hypoxia and oxidative stress contribute toward liver fibrosis. In this experiment, we used small hairpin RNA (shRNA) to interfere with the intracellular oxygen sensor—prolyl hydroxylase 1 (PHD1) and the intracellular oxidative stress sensor—kelch-like ECH associated protein 1 (Keap1) in the hypoxic hepatocytes in order to investigate the function of PHD1and Keap1.

Methods: We first established the CCl₄-induced liver fibrosis model, subsequently, the levels of the PHD1, hypoxia-inducible factor-1α (HIF-1α), hypoxia-inducible factor-2α (HIF-2α), Keap1, and nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) were detected in liver tissues. Simultaneously, AML12 cells co-transfected with PHD1 and Keap1shRNAs were constructed in vitro, then the intracellular oxidative stress, the proportion of cells undergoing apoptosis, and cell viability were measured. The expression of pro-fibrogenic molecules were analyzed via quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. The level of alpha-1 type I collagen (COL1A1) was determined using an enzyme-linked immunosorbent assay (ELISA). Finally, serum-free “conditioned medium” (CM) from the supernatant of hypoxic AML12 hepatocytes was used to culture rat hepatic stellate cells (HSC-T6), and the levels of fibrosis-related molecules, apoptosis, and cell proliferation were determined.

Results: The marker of hypoxia—HIF-1α and HIF-2α in the livers with fibrosis were upregulated, however, the increase in PHD1 expression was not statistically significant in comparison to the control group. Sign of oxidative stress—Keap1 was increased, while the expression of Nrf2, one of the Keap1 main downstream molecules, was reduced in the hepatocytes. And in vitro, the double-knockdown of PHD1 and Keap1 in AML12 hepatocytes presented with decreased hypoxia-induced oxidative stress and apoptosis, furthermore, these hypoxic AML12 cells showed the increased cell viability and the doweregulated expression of pro-fibrogenic molecules. In addition, HSC-T6 cells cultured in the hypoxic double-knockdown CM demonstrated the downregulation of fibrosis-related molecules, diminished cell proliferation, and enhanced apoptosis.

Conclusions: Our study demonstrated that double-knockdown of PHD1 and Keap1 attenuated hypoxia and oxidative stress induced injury in the hepatocytes, and subsequently inhibited HSC activation, which offers a novel therapeutic strategy in the prophylaxis and treatment of liver fibrosis.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications, such as variceal bleeding, ascites or hepatic encephalopathy. As such, clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis. At present, non-selective β-blockers, vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia. In contrast, safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue. In recent years, several preclinical and clinical trials have focused on this latter component and other therapeutic avenues. In this review, we highlight novel data in this context and address potentially interesting therapeutic options for the future.

Rationale for the use of statins in liver disease

The evolution of chronic liver injuries from benign and manageable dysfunction to life threatening end-stage liver disease with severe complications renders chronic liver disease a global health burden. Because of the lack of effective medication, transplantation remains the only and final curative option for end-stage liver disease. Since the demand for organ transplants by far exceeds the supply, other treatment options are urgently required to prevent progression and improve end-stage liver disease. Statins are primarily cholesterol-lowering drugs used for primary or secondary prevention of cardiovascular diseases. In addition to the primary effect, statins act beneficially through different pleiotropic mechanisms on inflammation, fibrosis, endothelial function, thrombosis, and coagulation to improve chronic liver diseases. However, concerns remain about the efficacy and safety of statin treatment because of their potential hepatotoxic risks, and as of now, these risks impede broader use of statins in the treatment of chronic liver diseases. The aim of this review is to comprehensively describe the mechanisms by which statins improve prospects for different chronic liver diseases with special focus on the pathophysiological rationale and the clinical experience of statin use in the treatment of liver diseases.

Loss of pericyte smoothened activity in mice with genetic deficiency of leptin

BACKGROUND

Obesity is associated with multiple diseases, but it is unclear how obesity promotes progressive tissue damage. Recovery from injury requires repair, an energy-expensive process that is coupled to energy availability at the cellular level. The satiety factor, leptin, is a key component of the sensor that matches cellular energy utilization to available energy supplies. Leptin deficiency signals energy depletion, whereas activating the Hedgehog pathway drives energy-consuming activities. Tissue repair is impaired in mice that are obese due to genetic leptin deficiency. Tissue repair is also blocked and obesity enhanced by inhibiting Hedgehog activity. We evaluated the hypothesis that loss of leptin silences Hedgehog signaling in pericytes, multipotent leptin-target cells that regulate a variety of responses that are often defective in obesity, including tissue repair and adipocyte differentiation.

RESULTS

We found that pericytes from liver and white adipose tissue require leptin to maintain expression of the Hedgehog co-receptor, Smoothened, which controls the activities of Hedgehog-regulated Gli transcription factors that orchestrate gene expression programs that dictate pericyte fate. Smoothened suppression prevents liver pericytes from being reprogrammed into myofibroblasts, but stimulates adipose-derived pericytes to become white adipocytes. Progressive Hedgehog pathway decay promotes senescence in leptin-deficient liver pericytes, which, in turn, generate paracrine signals that cause neighboring hepatocytes to become fatty and less proliferative, enhancing vulnerability to liver damage.

CONCLUSIONS

Leptin-responsive pericytes evaluate energy availability to inform tissue construction by modulating Hedgehog pathway activity and thus, are at the root of progressive obesity-related tissue pathology. Leptin deficiency inhibits Hedgehog signaling in pericytes to trigger a pericytopathy that promotes both adiposity and obesity-related tissue damage.

Reversal of liver fibrosis: From fiction to reality

In chronic liver diseases, an ongoing hepatocellular injury together with inflammatory reaction results in activation of hepatic stellate cells (HSCs) and increased deposition of extracellular matrix (ECM) termed as liver fibrosis. It can progress to cirrhosis that is characterized by parenchymal and vascular architectural changes together with the presence of regenerative nodules. Even at late stage, liver fibrosis is reversible and the underlying mechanisms include a switch in the inflammatory environment, elimination or regression of activated HSCs and degradation of ECM. While animal models have been indispensable for our understanding of liver fibrosis, they possess several important limitations and need to be further refined. A better insight into the liver fibrogenesis resulted in a large number of clinical trials aiming at reversing liver fibrosis, particularly in patients with non-alcoholic steatohepatitis. Collectively, the current developments demonstrate that reversal of liver fibrosis is turning from fiction to reality.

A Nitric Oxide-Donating Statin Decreases Portal Pressure with a Better Toxicity Profile than Conventional Statins in Cirrhotic Rats

Statins present many beneficial effects in chronic liver disease, but concerns about safety exist. We evaluated the hepatic effects of a nitric oxide-releasing atorvastatin (NCX 6560) compared to conventional statins. Simvastatin, atorvastatin and NCX 6560 were evaluated in four-week bile duct-ligated rats (BDL) simulating decompensated cirrhosis and in thirteen-week carbon tetrachloride (CCl₄) intoxicated rats, a model of early cirrhosis. In the BDL model, simvastatin treated rats showed high mortality and the remaining animals presented muscular and hepatic toxicity. At equivalent doses, NCX 6560 eliminated hepatic toxicity and reduced muscular toxicity (60–74%) caused by atorvastatin in the more advanced BDL model; toxicity was minimal in the CCl₄ model. Atorvastatin and NCX 6560 similarly reduced portal pressure without changing systemic hemodynamics in both models. Atorvastatin and NCX 6560 caused a mild decrease in liver fibrosis and inflammation and a significant increase in intrahepatic cyclic guanosine monophosphate. NCX 6560 induced a higher intrahepatic vasoprotective profile (activated endothelial nitric oxide synthase and decreased platelet/endothelial cell adhesion molecule-1), especially in the CCl₄ model, suggesting a higher benefit in early cirrhosis. In conclusion, NCX 6560 improves the liver profile and portal hypertension of cirrhotic rats similarly to conventional statins, but with a much better safety profile.

Antifibrotics in chronic liver disease: tractable targets and translational challenges

Chronic liver disease prevalence is increasing globally. Iterative liver damage, secondary to any cause of liver injury, results in progressive fibrosis, disrupted hepatic architecture, and aberrant regeneration, which are defining characteristics of liver cirrhosis. Liver transplantation is an effective treatment for end-stage liver disease; however, demand greatly outweighs donor organ supply, and in many parts of the world liver transplantation is unavailable. Hence, effective antifibrotic therapies are urgently required. In the past decade, rapid progress has been made in our understanding of the pathophysiology of liver fibrosis and a large number of potential cellular and molecular antifibrotic targets have been identified. This has led to numerous clinical trials of antifibrotic agents in patients with chronic liver disease. However, none of these have resulted in a robust and reproducible effect on fibrosis. It is therefore imperative that the ongoing translational challenges are addressed, to convert scientific discoveries into potent antifibrotics and enable bridging of the translational gap between putative therapeutic targets and effective treatments for patients with chronic liver disease.

Statins improve NASH via inhibition of RhoA and Ras

Nonalcoholic steatohepatitis (NASH), especially as part of the metabolic syndrome (MS), is an increasing burden in Western countries. Statins are already used in MS and seem to be beneficial in liver diseases. The aim of this study was to investigate the molecular mechanisms underlying pleiotropic effects on small GTPases of statins in NASH. NASH within MS was induced in 12-wk-old apoE^-/- mice after 7 wk of Western diet (NASH mice). Small GTPases were inhibited by activated simvastatin (SMV), NSC23766 (NSC), or Clostridium sordellii lethal toxin (LT) by using subcutaneous osmotic minipumps. Hepatic steatosis, inflammation, and fibrosis were assessed by histology, Western blot, and RT-PCR measurements of cholesterol and hydroxyproline content. SMV treatment significantly decreased hepatic inflammation and fibrosis, but had no significant effect on steatosis and hepatic cholesterol content in NASH. SMV blunted fibrosis due to inhibition of both RhoA/Rho kinase and Ras/ERK pathways. Interestingly, inhibition of RAC1 and Ras (by LT) failed to decrease fibrosis to the same extent. Inhibition of RAC1 (by NSC) showed no significant effect at all. Inhibition of RhoA and Ras downstream signaling by statins is responsible for the beneficial hepatic effects in NASH.

FXR agonist obeticholic acid reduces hepatic inflammation and fibrosis in a rat model of toxic cirrhosis

Hepatic inflammation drives hepatic stellate cells (HSC), resulting in liver fibrosis. The Farnesoid-X receptor (FXR) antagonizes inflammation through NF-κB inhibition. We investigated preventive and therapeutic effects of FXR agonist obeticholic acid (OCA) on hepatic inflammation and fibrosis in toxic cirrhotic rats. Cirrhosis was induced by thioacetamide (TAA) intoxication. OCA was given during or after intoxication with vehicle-treated rats as controls. At sacrifice, fibrosis, hemodynamic and biochemical parameters were assessed. HSC activation, cell turn-over, hepatic NF-κB activation, pro-inflammatory and pro-fibrotic cytokines were determined. The effect of OCA was further evaluated in isolated HSC, Kupffer cells, hepatocytes and liver sinusoidal endothelial cells (LSEC). OCA decreased hepatic inflammation and fibrogenesis during TAA-administration and reversed fibrosis in established cirrhosis. Portal pressure decreased through reduced intrahepatic vascular resistance. This was paralleled by decreased expression of pro-fibrotic cytokines (transforming growth-factor β, connective tissue growth factor, platelet-derived growth factor β-receptor) as well as markers of hepatic cell turn-over, by blunting effects of pro-inflammatory cytokines (e.g. monocyte chemo-attractant protein-1). In vitro, OCA inhibited both LSEC and Kupffer cell activation; while HSC remained unaffected. This related to NF-κB inhibition via up-regulated IκBα. In conclusion, OCA inhibits hepatic inflammation in toxic cirrhotic rats resulting in decreased HSC activation and fibrosis.

Sinusoidal communication in liver fibrosis and regeneration

Cellular crosstalk is a process through which a message is transmitted within an individual cell (intracellular crosstalk) or between different cells (intercellular crosstalk). Intercellular crosstalk within the liver microenvironment is critical for the maintenance of normal hepatic functions and for cells survival. Hepatic cells are closely connected to each other, work in synergy, and produce molecules that modulate their differentiation and activity. This review summarises the current knowledge regarding paracrine communication networks in parenchymal and non-parenchymal cells in liver fibrosis due to chronic injury, and regeneration after partial hepatectomy.

The calcium-activated potassium channel KCa3.1 is an important modulator of hepatic injury

The calcium-activated potassium channel KCa3.1 controls different cellular processes such as proliferation and volume homeostasis. We investigated the role of KCa3.1 in experimental and human liver fibrosis. KCa3.1 gene expression was investigated in healthy and injured human and rodent liver. Effect of genetic depletion and pharmacological inhibition of KCa3.1 was evaluated in mice during carbon tetrachloride induced hepatic fibrogenesis. Transcription, protein expression and localisation of KCa3.1 was analysed by reverse transcription polymerase chain reaction, Western blot and immunohistochemistry. Hemodynamic effects of KCa3.1 inhibition were investigated in bile duct-ligated and carbon tetrachloride intoxicated rats. In vitro experiments were performed in rat hepatic stellate cells and hepatocytes. KCa3.1 expression was increased in rodent and human liver fibrosis and was predominantly observed in the hepatocytes. Inhibition of KCa3.1 aggravated liver fibrosis during carbon tetrachloride challenge but did not change hemodynamic parameters in portal hypertensive rats. In vitro, KCa3.1 inhibition leads to increased hepatocyte apoptosis and DNA damage, whereas proliferation of hepatic stellate cells was stimulated by KCa3.1 inhibition. Our data identifies KCa3.1 channels as important modulators in hepatocellular homeostasis. In contrast to previous studies in vitro and other tissues this channel appears to be anti-fibrotic and protective during liver injury.

Evolving Insights on Metabolism, Autophagy, and Epigenetics in Liver Myofibroblasts

Liver myofibroblasts (MFB) are crucial mediators of extracellular matrix (ECM) deposition in liver fibrosis. They arise mainly from hepatic stellate cells (HSCs) upon a process termed “activation.” To a lesser extent, and depending on the cause of liver damage, portal fibroblasts, mesothelial cells, and fibrocytes may also contribute to the MFB population. Targeting MFB to reduce liver fibrosis is currently an area of intense research. Unfortunately, a clog in the wheel of antifibrotic therapies is the fact that although MFB are known to mediate scar formation, and participate in liver inflammatory response, many of their molecular portraits are currently unknown. In this review, we discuss recent understanding of MFB in health and diseases, focusing specifically on three evolving research fields: metabolism, autophagy, and epigenetics. We have emphasized on therapeutic prospects where applicable and mentioned techniques for use in MFB studies. Subsequently, we highlighted uncharted territories in MFB research to help direct future efforts aimed at bridging gaps in current knowledge.