Reversal of hepatic fibrosis -- fact or fantasy?

MicroRNAs in Liver Health and Disease

MicroRNAs (miRNAs), a class of short non-coding RNAs, have been studied intensely and extensively in the past decade in every aspect of biological processes, including cell differentiation, proliferation and death. These findings pointed out the pivotal role of miRNA in posttranscriptional control of gene expression in animals and established miRNAs as therapeutic targets for different pathophysiological processes, including liver disease. Here we have discussed the recent advances made in identifying the miRNAs deregulated in different liver diseases such as obesity, hepatitis, alcoholic and nonalcoholic steatohepatitis, cirrhosis and hepatocellular carcinoma, as well as pathophysiological conditions such as developmental abnormality. We have specifically reviewed the role of miRNAs in these diseases and discussed critically potential impacts of these miRNAs as biomarkers and/or therapeutic targets in liver pathobiology in the clinical setting. Finally, we have highlighted the latest techniques or preclinical and/or clinical trials that are being developed to replenish or inhibit the deregulated miRNAs.

A prospective experimental study of liver fibrosis with ultrasound and its correlation with hepatic reserve function and hemodynamics

Background

Progressive hepatic fibrosis is the eventual cause of liver cirrhosis. Doppler ultrasound has been used to detect hemodynamic changes that are known to be present during the pre-cirrhotic stages of hepatic fibrogenesis. However, the relationship between the Doppler ultrasound parameters and the impairment of the liver function has not been fully investigated. The purpose of this study was to explore the hepatic function reserve and its relationship with the hepatic hemodynamics in a rabbit model of liver fibrosis using Doppler ultrasound.

Methods

A prospective study was performed. Sixty healthy New Zealand rabbits were included in this study. Eleven of them served as controls and were normally fed and provided with water drink; the rest of 49 rabbits that served as fibrosis group were normally fed but provided with 1.2 g/L of thioacetamide to create liver fibrosis model. Doppler measurements were performed in the portal trunk, proper hepatic artery and proper splenic artery. The hepatic circulation index (HCI) was calculated. Hepatic function reverse was evaluated by measuring the indocyanine green clearance and retention rate at 15 min (ICG R15) test. Portal venous pressure (PVP) was measured using the portal vein punctuation equipment.

Results

HCI was significantly decreased and PVP increased in the advanced fibrotic stage (F4) compared to mild and moderate fibrotic stage (F1-3), respectively (p<0.05). PVP and ICG R15 in the fibrotic group were significantly higher than that in the control group (ICG: 0.209±0.086 vs. 0.093±0.023, p<0.01). Within the fibrotic groups, PVP was higher in advanced fibrotic stage (F4) than those in mild (F1-2) or moderate (F3) fibrotic stages (p<0.05). Both HCI and PVP correlated well with ICG R15 (r = −0.890, and r = 0.780, p <0.01).

Conclusions

Hepatic function reserve closely relates to the hepatic hemodynamics in the rabbit model of liver fibrosis. Doppler Ultrasound could be reliably used to assess the hepatic function reserve and hemodynamic changes in different stages of liver fibrosis.

Therapeutic immunomodulation using a virus--the potential of inactivated orf virus

Viruses can manipulate the immune response against them by various strategies to influence immune cells, i.e. by over-activation leading to functional inactivation, bypassing antigen presentation or even suppression of effector functions. Little is known, however, about how these features of immune regulation and modulation could be used for therapeutic purposes. Reasons for this include the complexity of immune regulatory mechanisms under certain disease conditions and the risks that infections with viruses pose to human beings. The orf virus (ORFV), a member of the Parapoxvirus genus of the poxvirus family, is known as a common pathogen in sheep and goats worldwide. The inactivated ORFV, however, has been used as a preventative as well as therapeutic immunomodulator in veterinary medicine in different species. Here, we review the key results obtained in pre-clinical studies or clinical studies in veterinary medicine to characterise the therapeutic potential of inactivated ORFV. Inactivated ORFV has strong effects on cytokine secretion in mice and human immune cells, leading to an auto-regulated loop of initial up-regulation of inflammatory and Th1-related cytokines, followed by Th2-related cytokines that attenuate immunopathology. The therapeutic potential of inactivated ORFV has been recognised in several difficult-to-treat disease areas, such as chronic viral diseases, liver fibrosis or various forms of cancer. Further research will be required in order to evaluate the full beneficial potential of inactivated ORFV for therapeutic immunomodulation.

Liver T1ρ MRI measurement in healthy human subjects at 3 T: a preliminary study with a two-dimensional fast-field echo sequence

OBJECTIVES

The aim of this study was to explore the technical feasibility of T(1)ρ MRI for the liver, and to determine the normal range of liver T(1)ρ in healthy subjects at clinical 3 T.

METHODS

There were 15 healthy volunteers. Three representative axial slices were selected to cut through the upper, middle and lower liver. A rotary echo spin-lock pulse was implemented in a two-dimensional fast-field echo sequence. Spin-lock frequency was 500 Hz, and the spin-lock times of 1, 10, 20, 30, 40 and 50 ms were used for T(1)ρ mapping. The images were acquired slice by slice during breath-holding. Regions of interest (ROIs; n=5) were manually placed on each slice of the liver parenchyma region, excluding artefacts and vessels. The mean value of these ROIs (n=15) was regarded as the liver T(1)ρ value for the subject. Six subjects were scanned once at fasting status; six subjects were scanned once 2 h post meal; three subjects were scanned twice at fasting status; and seven subjects were scanned twice 2 h post meal.

RESULTS

When two readers measured the same 10 data sets, the interreader reproducibility (ICC: intraclass correlation coefficient) was 0.955. With the 10 subjects scanned twice, the ICC for scan-rescan reproducibility was 0.764. There was no significant difference for the liver T(1)ρ value at the fasting status (43.08±1.41 ms) and post-meal status (42.97±2.38 ms, p=0.867). Pooling together all the 32 scans in this study, the normal liver T(1)ρ value ranged from 38.6 to 48.3 ms (mean 43.0 ms, median 42.6 ms).

CONCLUSION

It is feasible to obtain consistent liver T(1)ρ measurement for human subjects at 3 T.

Performance of magnetic resonance elastography and diffusion-weighted imaging for the staging of hepatic fibrosis: A meta-analysis

A meta-analysis was performed to assess and compare the accuracies of magnetic resonance elastography (MRE) and diffusion-weighted imaging (DWI) for the staging of hepatic fibrosis. Online journal databases and a manual search from January 2000 to May 2011 were used. We identified 41 studies, but only 14 met the criteria to perform a meta-analysis assessing MRE (five trials) or DWI (10 trials). Fibrosis was categorized by redistribution into five stages according to histopathological description. A bivariate binomial model was used to combine the sensitivity and specificity and their 95% confidence intervals (CIs), from which diagnostic odds ratio (DOR), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and summary receiver operating characteristic (sROC) were derived to indicate the diagnostic accuracy of imaging modalities. With MRE, the sensitivity, specificity, DOR, PLR, NLR, and area under sROC curve (with 95% CIs) for staging F0 ∼ F1 versus F2 ∼ F4 and F0 ∼ F2 versus F3 ∼ F4 were 0.94 (0.81-0.98), 0.95 (0.87-0.98), 20 (7-57), 0.06 (0.02-0.22), 317 (55-1,796), 0.98 (0.97-0.99) and 0.92 (0.85-0.96), 0.96 (0.91-0.98), 21 (10-45), 0.08 (0.04-0.16), 251 (103-609), and 0.98 (0.96-0.99), respectively; and with DWI, these values were 0.77 (0.71-0.82), 0.78 (0.69-0.85), 3 (2-5), 0.30 (0.22-0.40), 12 (6-21), 0.83 (0.79-0.86) and 0.72 (0.60-0.81), 0.84 (0.77-0.89), 5 (3-7), 0.34 (0.23-0.50), 13 (6-29), and 0.86 (0.83-0.89), respectively. A z test demonstrated that MRE had a significantly higher accuracy than DWI in those indicators (P < 0.05).

CONCLUSION

MRE is more reliable for staging hepatic fibrosis, compared with DWI, with a high combination of sensitivity, specificity, likelihood ratios, DOR, and area under sROC curve.

Anti-fibrotic therapy: lost in translation?

While preclinical development of potential anti-fibrotics is far advanced, with numerous pharmacological targets and promising agents, almost none has entered clinical validation. Reasons are manifold, including the usually slow progression of liver fibrosis, requiring high numbers of well-stratified patients undergoing long-term treatment when conventional liver biopsy based parameters or hard liver-related endpoints are used. Importantly, there is a notorious lack of sensitive and specific surrogate markers or imaging technologies for liver fibrosis progression or regression that would permit a rapid clinical screening for potential anti-fibrotics. Nonetheless, in view of an urgent need for anti-fibrotics that positively impact morbidity and mortality from chronic liver diseases, the field is now moving more quickly towards clinical translation. This development is driven by thoughtful preclinical validation, a better study design and improved surrogate readouts using currently available methodologies. Moreover, upcoming novel biomarkers and imaging technologies will soon permit a more exact and efficient assessment of fibrosis progression and regression.

Accuracy of MR elastography and anatomic MR imaging features in the diagnosis of severe hepatic fibrosis and cirrhosis

PURPOSE

To compare the diagnostic accuracy of magnetic resonance imaging elastography (MRE) and anatomic MRI features in the diagnosis of severe hepatic fibrosis and cirrhosis.

MATERIALS AND METHODS

Three readers independently assessed presence of morphological changes associated with hepatic fibrosis in 72 patients with liver biopsy including: caudate to right lobe ratios, nodularity, portal venous hypertension (PVH) stigmata, posterior hepatic notch, expanded gallbladder fossa, and right hepatic vein caliber. Three readers measured shear stiffness values using quantitative shear stiffness maps (elastograms). Sensitivity, specificity, and diagnostic accuracy of stiffness values and each morphological feature were calculated. Interreader agreement was summarized using weighted kappa statistics. Intraclass correlation coefficient was used to assess interreader reproducibility of stiffness measurements. Binary logistic regression was used to assess interreader variability for dichotomized stiffness values and each morphological feature.

RESULTS

Using 5.9 kPa as a cutoff for differentiating F3-F4 from F0-2 stages, overall sensitivity, specificity, and diagnostic accuracy for MRE were 85.4%, 88.4%, and 87%, respectively. Overall interreader agreement for stiffness values was substantial, with an insignificant difference (P = 0.74) in the frequency of differentiating F3-4 from F0-2 fibrosis. Only hepatic nodularity and PVH stigmata showed moderately high overall accuracy of 69.4% and 72.2%. Interreader agreement was substantial only for PVH stigmata, moderate for C/R m, deep notch, and expanded gallbladder fossa. Only posterior hepatic notch (P = 0.82) showed no significant difference in reader rating.

CONCLUSION

MRE is a noninvasive, accurate, and reproducible technique compared with conventional features of detecting severe hepatic fibrosis.

Effect of recombinant human growth hormone and interferon gamma on hepatic collagen synthesis and proliferation of hepatic stellate cells in cirrhotic rats

BACKGROUND

Fibrosis plays a key role in the development of liver cirrhosis. In this study, we investigated the effect of growth hormone and interferon gamma on hepatic collagen synthesis and the proliferation of hepatic stellate cells in a cirrhotic rat model.

METHODS

Cirrhosis was induced in rats using carbon tetrachloride. Rats were simultaneously treated with daily subcutaneous injections of recombinant human growth hormone or interferon gamma combined with recombinant human growth hormone. The control group was given saline. The relative content of type I and type IV collagen was assessed by indirect immunofluorescence analysis. Activated hepatic stellate cells were prepared from cirrhotic rats. The 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide (MTT) method was used to assess the effects of recombinant human growth hormone and interferon gamma on these cells in vitro.

RESULTS

Both qualitative and quantitative analysis showed that type I and type IV collagen secretion increased with time after recombinant human growth hormone administration and was significantly higher than control and recombinant human growth hormone combined with interferon gamma administration. In vitro, recombinant human growth hormone significantly stimulated hepatic stellate cell proliferation in a concentration-dependent manner (10(-3)-10(-1) mg/100 μL), and interferon gamma (10(-2)-10(-1) μg/100 μL) significantly inhibited their growth compared to the control group. Interferon gamma combined with recombinant human growth hormone eliminated this growth-promoting effect to a certain degree in a concentration-dependent manner (10(-1) μg/100 μL, P<0.05, 10(-2)-10(-3) μg/100 μL, P>0.05) and a time-dependent manner (P<0.05).

CONCLUSIONS

Recombinant human growth hormone increased collagen secretion in cirrhotic rats in vivo and promoted the proliferation of hepatic stellate cells from cirrhotic rats in vitro. It is possible that concurrent interferon gamma therapy can offset these side-effects of recombinant human growth hormone.

PEGylation of interleukin-10 improves the pharmacokinetic profile and enhances the antifibrotic effectivity in CCl₄-induced fibrogenesis in mice

Liver fibrosis represents a scar formation process as a response to chronic injury and a major cause of death worldwide. To date, no drug is available for this condition. Interleukin-10 (IL-10) has potent anti-inflammatory and antifibrotic properties but its short half-life in the circulation hampers its clinical use. Our aim was therefore to modify IL-10 with polyethylene glycol (PEG) to prolong its circulation time and enhance its effectivity. IL-10 was modified with 5 or 20 kDa PEG. The biological activity was preserved after PEGylation as assessed by inhibition of TNF-α production by macrophages. In vivo, during CCl(4)-induced fibrogenesis in mice, both 5PEG-IL-10 and 20PEG-IL-10 showed a longer circulation time compared to IL-10, which was associated with a significant increased liver accumulation. Immunohistochemical analysis of fibrotic livers of mice receiving treatment with IL-10 or its PEGylated forms, revealed a decrease in markers reflecting HSC and KC activation induced by 5PEG-IL10. Transcription levels of IL-6 were decreased upon treatment with IL-10 and both PEGylated forms, whereas IL-1β levels were only down-regulated by 5PEGIL-10 and 20PEGIL-10. We conclude that PEGylation of IL-10 is a good strategy to attenuate liver fibrosis and that 5PEGIL-10 is the most effective conjugate.

Evaluation of the spontaneous reversibility of carbon tetrachloride-induced liver cirrhosis in rabbits

There is a general consensus that liver fibrosis in humans is potentially reversible, while scepticism prevails on the concept that cirrhosis can be truly reversed. The availability of suitable experimental models is fundamental for disease research. The experimental murine model of liver cirrhosis induced by carbon tetrachloride (CCl(4)) reproduces both the histological picture of the postnecrotic cirrhosis and its biochemical and clinical parameters. Normal hepatic structure is modified by formation of regeneration nodules. Fibrosis represents a morphological element of disease and an effect of hepatocyte necrosis. However, the relevance for research of this well-established model of liver cirrhosis is hampered by some spontaneous cirrhosis regression reported in mice and rats. It has been reported that CCl(4) also induces experimental liver cirrhosis in rabbits, but it is not known whether the process is reversible in this species. The aim of our study was to investigate this question. Male New Zealand White rabbits were treated intragastrically with CCl(4) or the vehicle only for 19 weeks and groups were sacrificed three and five months after treatment interruption. Cirrhotic and control livers were processed for routine light microscopy and for morphometric study of fibrosis by semiquantitative evaluation. The degree of fibrosis was based on the Knodell's scoring system.

MR T1ρ as an imaging biomarker for monitoring liver injury progression and regression: an experimental study in rats with carbon tetrachloride intoxication

OBJECTIVES

Recently it was shown that the magnetic resonance imaging (MRI) T1ρ value increased with the severity of liver fibrosis in rats with bile duct ligation. Using a rat carbon tetrachloride (CCl(4)) liver injury model, this study further investigated the merit of T1ρ relaxation for liver fibrosis evaluation.

METHODS

Male Sprague-Dawley rats received intraperitoneal injection of 2 ml/kg CCl(4) twice weekly for up to 6 weeks. Then CCl(4) was withdrawn and the animals were allowed to recover. Liver T1ρ MRI and conventional T2-weighted images were acquired. Animals underwent MRI at baseline and at 2 days, 2 weeks, 4 weeks and 6 weeks post CCl(4) injection, and they were also examined at 1 week and 4 weeks post CCl(4) withdrawal. Liver histology was also sampled at these time points.

RESULTS

Liver T1ρ values increased slightly, though significantly, on day 2, and then increased further and were highest at week 6 post CCl(4) insults. The relative liver signal intensity change on T2-weighted images followed a different time course compared with that of T1ρ. Liver T1ρ values decreased upon the withdrawal of the CCl(4) insult. Histology confirmed the animals had typical CCl(4) liver injury and fibrosis progression and regression processes.

CONCLUSIONS

MR T1ρ imaging can monitor CCl(4)-induced liver injury and fibrosis.

KEY POINTS

• MR T1ρ is a valuable imaging biomarker for liver injury/fibrosis. • Liver T1ρ was only mildly affected by oedema and acute inflammation. • Liver MR T1ρ decreased when liver fibrosis and injury regressed.

What's new in liver fibrosis? The origin of myofibroblasts in liver fibrosis

Chronic liver injury of many etiologies produces liver fibrosis and may eventually lead to the formation of cirrhosis. Fibrosis is part of a dynamic process associated with the continuous deposition and resorption of extracellular matrix, mainly fibrillar collagen. Studies of fibrogenesis conducted in many organs including the liver demonstrate that the primary source of the extracellular matrix in fibrosis is the myofibroblast. Hepatic myofibroblasts are not present in the normal liver but transdifferentiate from heterogeneous cell populations in response to a variety of fibrogenic stimuli. Debate still exists regarding the origin of hepatic myofibroblasts. It is considered that hepatic stellate cells and portal fibroblasts have fibrogenic potential and are the major origin of hepatic myofibroblasts. Depending on the primary site of injury the fibrosis may be present in the hepatic parenchyma as seen in chronic hepatitis or may be restricted to the portal areas as in most biliary diseases. It is suggested that hepatic injury of different etiology triggers the transdifferentiation to myofibroblasts from distinct cell populations. Here we discuss the origin and fate of myofibroblast in liver fibrosis.

Imatinib mesylate improves liver regeneration and attenuates liver fibrogenesis in CCL4-treated mice

BACKGROUNDS

Imatinib mesylate (STI-571), a tyrosine kinase inhibitor, has previously been demonstrated to attenuate liver fibrogenesis through inhibition of the activation of hepatic stellate cells (HSCs) in CCL(4)-treated rat models.

AIMS

This study aimed to further evaluate the role of STI-571 in liver regeneration.

MATERIALS AND METHODS

All animals were divided into four groups, and mice were treated with or without CCL(4) and STI-571 (n = 6 for each group).

RESULTS

Activated cultured HSCs in vitro with STI-571 administration showed increased apoptosis and reduced proliferation, as determined by flow cytometric analysis, 3-(4, 5-cimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay, and confocal microscopy. STI-571 treatment attenuated liver fibrosis in vivo, as was evident in the results of histology, mRNA level, and expression analysis of smooth muscle actin and type I collagen. Mice treated with STI-571 had increased liver weight ratio and the improvement in liver regeneration was compatible with the change of serum interleukin 6 levels (p < 0.05). Further, increased apoptosis and a reduced proliferation were observed in the CCL(4)-treated mice after STI-571 treatment based on the immunohistochemical staining of Annexin V, phosphorylated STAT3, and PCNA.

CONCLUSION

STI-571 treatment effectively attenuated liver fibrogenesis and improved in liver regeneration in vivo and induced apoptosis in HSCs both in vitro and in vivo.

The precarious state of the liver after a Fontan operation: summary of a multidisciplinary symposium

As the cohort of survivors with the single-ventricle type of congenital heart disease grows, it becomes increasingly evident that the state of chronically elevated venous pressure and decreased cardiac output inherent in the Fontan circulation provides the substrate for a progressive decline in functional status. One organ at great risk is the liver. Wedged between two capillary beds, with the pulmonary venous bed downstream, which typically has no pulsatile energy added in the absence of a functional right ventricle, and the splanchnic bed upstream, which may have compromised inflow due to inherent cardiac output restriction characteristic of the Fontan circulation, the liver exists in a precarious state. This review summarizes a consensus view achieved at a multidisciplinary symposium held at The Children's Hospital of Philadelphia in June 2011. The discussion includes current knowledge concerning the hemodynamic foundations of liver problems, the diagnostic tools available, the unique histopathology of the liver after the Fontan operation, and proposed mechanisms for hepatic fibrosis at the cellular level. At the completion of the symposium, a consensus recommendation was made by the authors' group to pursue a new prospective protocol for clinical evaluation of the liver for all patients in our practice 10 years after the Fontan operation.

A methionine-choline-deficient diet elicits NASH in the immunodeficient mouse featuring a model for hepatic cell transplantation

Non-alcoholic staetohepatitis (NASH) is associated with fat deposition in the liver favoring inflammatory processes and development of fibrosis, cirrhosis and finally hepatocellular cancer. In Western lifestyle countries, NASH has reached a 20% prevalence in the obese population with escalating tendency in the future. Very often, liver transplantation is the only therapeutic option. Recently, transplantation of hepatocyte-like cells differentiated from mesenchymal stem cells was suggested a feasible alternative to whole organ transplantation to ameliorate donor organ shortage. Hence, in the present work an animal model of NASH was established in immunodeficient mice to investigate the feasibility of human stem cell-derived hepatocyte-like cell transplantation. NASH was induced by feeding a methionine/choline-deficient diet (MCD-diet) for up to 5 weeks. Animals developed a fatty liver featuring fibrosis and elevation of the proinflammatory markers serum amyloid A (SAA) and tumor necrosis factor alpha (TNFα). Hepatic triglycerides were significantly increased as well as alanine aminotransferase demonstrating inflammation-linked hepatocyte damage. Elevation of αSMA mRNA and collagen I as well as liver architecture deterioation indicated massive fibrosis. Both short- and long-term post-transplantation human hepatocyte-like cells resided in the mouse host liver indicating parenchymal penetration and most likely functional engraftment. Hence, the NASH model in the immunodeficient mouse is the first to allow for the assessment of the therapeutic impact of human stem cell-derived hepatocyte transplantation.

Current status of novel antifibrotic therapies in patients with chronic liver disease

Fibrosis accumulation is a dynamic process resulting from a wound-healing response to acute or chronic liver injury of all causes. The cascade starts with hepatocyte necrosis and apoptosis, which instigate inflammatory signaling by chemokines and cytokines, recruitment of immune cell populations, and activation of fibrogenic cells, culminating in the deposition of extracellular matrix. These key elements, along with pathways of transcriptional and epigenetic regulation, represent fertile therapeutic targets. New therapies include drugs specifically designed as antifibrotics, as well as drugs already available with well-established safety profiles, whose mechanism of action may also be antifibrotic. At the same time, the development of noninvasive fibrogenic markers, and techniques (e.g. fibroscan), as well as combined scoring systems incorporating serum and clinical features will allow improved assessment of therapy response. In aggregate, the advances in the elucidation of the biology of fibrosis, combined with improved technologies for assessment will provide a comprehensive framework for design of antifibrotics and their analysis in well-designed clinical trials. These efforts may ultimately yield success in halting the progression of, or reversing, liver fibrosis.

Melittin attenuates liver injury in thioacetamide-treated mice through modulating inflammation and fibrogenesis

Liver fibrosis represents a process of healing and scarring in response to chronic liver injury. Following injury, an acute inflammation response takes place resulting in moderate cell necrosis and extracellular matrix damage. Melittin, the major bioactive component in the venom of honey bee Apis mellifera, is a 26-residue amphipathic peptide with well-known cytolytic, antimicrobial and proinflammatory properties. However, the molecular mechanisms responsible for the anti-inflammatory activity of melittin have not been elucidated in liver fibrosis. We investigated whether melittin ameliorates liver inflammation and fibrosis in thioacetamide (TAA)-induced liver fibrosis. Two groups of mice were treated with TAA (200 mg/L, in drinking water), one of the groups of mice was co-treated with melittin (0.1 mg/kg) for 12 weeks while the other was not. Hepatic stellate cells (HSCs) were cultured with tumor necrosis factor α in the absence or presence of melittin. Melittin suppresses the expression of proinflammatory cytokines through the nuclear factor (NF)-κB signaling pathway. Moreover, melittin reduces the activity of HSCs in vitro, and decreases the expression of fibrotic gene responses in TAA-induced liver fibrosis. Taken together, melittin prevents TAA-induced liver fibrosis by inhibiting liver inflammation and fibrosis, the mechanism of which is the interruption of the NF-κB signaling pathway. These results suggest that melittin could be an effective agent for preventing liver fibrosis.

Indole-3-carbinol enhances the resolution of rat liver fibrosis and stimulates hepatic stellate cell apoptosis by blocking the inhibitor of κB kinase α/inhibitor of κB-α/nuclear factor-κB pathway

Hepatic stellate cells (HSC) play a pivotal role in liver fibrosis, and the clearance of activated HSC by apoptosis is associated with the resolution of liver fibrosis. The development of strategies that promote this process in a selective way is therefore important. We evaluated the effects of indole-3-carbinol (I3C), a nutritional component derived from vegetables from the Brassica family, on liver fibrosis and HSC apoptosis. The in vivo therapeutic effects of I3C were monitored in three rat models of liver fibrosis induced by porcine serum, bile duct ligation, or multiple hepatotoxic factors, and its proapoptotic effect and molecular mechanism were studied in vitro in HSC-T6, a rat HSC line. The results showed that I3C treatment significantly reduced the number of activated HSC in the livers of rats with liver fibrosis. In histopathology, I3C reduced hepatocyte degeneration and necrosis, accelerated collagen degradation, and promoted the reversal of liver fibrosis. I3C prescribed to HSC-T6 resulted in morphologic alterations typical of apoptosis and DNA cleavage to a nucleosomal ladder. Moreover, I3C significantly increased the HSC-T6 apoptosis rate and the expression ratio of Bax to Bcl-2. High-throughput protein array analysis indicated that the tumor necrosis factor-α/nuclear factor-κB (NF-κB) signal pathway participated in I3C-induced HSC-T6 apoptosis. Western blot and electrophoretic mobility-shift assay confirmed that I3C inhibited the phosphorylation of inhibitor of κB kinase α and inhibitor of κB-α and NF-κB DNA binding activity. In conclusion, I3C could promote the reverse process of liver fibrosis in vivo and induce apoptosis of activated HSC in vitro, which indicates the use of I3C as a potential therapeutic agent in liver fibrosis treatment.

Transient elastography for assessment of fibrosis in paediatric liver disease

The prognosis and management of chronic liver diseases in children largely depend on the extent and progression of liver fibrosis, which is often the most important predictor of disease outcome, and thus influences the indication for potential therapy. Unfortunately, liver biopsy continues to be the gold standard for the staging and grading of fibrosis. Liver biopsy is an invasive and painful technique with several limitations. These limitations have led to the development of alternative noninvasive methods for the accurate assessment of fibrosis and for the maintenance of an acceptable risk/benefit ratio. In the last decades, transient elastography (TE) has received increasing consideration as a means of evaluating disease progression in paediatric chronic liver disease. TE is an accurate and reproducible methodology for identifying subjects without fibrosis or significant fibrosis, or with advanced fibrosis. In this review, we provide an outline of liver fibrosis in paediatric liver diseases, including fibrogenesis, and noninvasive techniques for the diagnosis and follow-up of fibrosis, and then focus on the characteristics of TE and on its strength in the assessment of liver fibrosis, paying particular attention to studies conducted in children.

Comparison of early treatment with low doses of nilotinib, imatinib and a clinically relevant dose of silymarin in thioacetamide-induced liver fibrosis

Our previous study has already confirmed a promising anti-fibrotic activity especially for nilotinib; when given at a daily dose of 10 mg/kg during the last 4 weeks of thioacetamide (TAA)-induced liver fibrosis for 12 weeks in rats. Therefore, this study was carried out to compare the prophylactic potential of low dose of nilotinib to that of its predecessor, imatinib, and a clinically relevant dose of the standard hepatoprotective treatment, silymarin, in TAA-intoxication. Male Wistar rats received intraperitoneal injections of TAA (150 mg/kg, twice weekly) for 8 weeks, as well as oral treatments with imatinib (5 mg/kg/day), nilotinib (5 mg/kg/day) and silymarin (50 mg/kg/day) from the first day of TAA-intoxication. At the end of the study, chronic hepatic injury was evaluated by analysis of liver function tests in serum. Hepatic oxidative stress was assessed by measuring malondialdehyde, 4-hydroxynonenal, total nitrate/nitrite and reduced glutathione contents, as well as myeloperoxidase and superoxide dismutase activities. Hepatic fibrosis was evaluated by histopathology and collagen content. Our results suggest that the prophylactic potential of nilotinib (5 mg/kg/day), imatinib (5mg/kg/day) and silymarin (50 mg/kg/day) in TAA-intoxication for 8 weeks is lower than the late treatments of nilotinib (10 mg/kg/day), imatinib (10mg/kg/day) and silymarin (100 mg/kg/day) during the last 4 weeks of TAA-intoxication for 12 weeks in rats. Taken together, this study suggests that nilotinib may have higher anti-fibrotic activity when administered at a significant stage of fibrosis as a result of impairment of its metabolism in the fibrotic livers.

Role of integrins in fibrosing liver diseases

Integrins and other cell adhesion molecules regulate numerous physiological and pathological mechanisms by mediating the interaction between cells and their extracellular environment. Although the significance of integrins in the evolution and progression of certain cancers is well recognized, their involvement in nonmalignant processes, such as organ fibrosis or inflammation, is only beginning to emerge. However, accumulating evidence points to an instrumental role of integrin-mediated signaling in a variety of chronic and acute noncancerous diseases, particularly of the liver.

Development of a large animal model of cirrhosis and portal hypertension using hepatic transarterial embolization: a study in swine

PURPOSE

To develop a clinically relevant porcine model of liver cirrhosis with portal hypertension by means of hepatic transarterial embolization.

MATERIALS AND METHODS

Institutional animal care and use committee approval was obtained for all experiments. Pigs received transcatheter arterial infusion of a 3:1 mixture of iodized oil and ethanol into the hepatic artery in volumes of 16 mL in group 1 (n = 4), 28 mL in group 2 (n = 4), and 40 mL in group 3 (n = 4) with intent of bilobar distribution. Hepatic venous pressure gradient (HVPG) measurement, liver function tests, and volumetry were performed at baseline, at 2 weeks, and before necropsy.

RESULTS

Cirrhosis was successfully induced in three animals that received 16 mL of the embolic mixture and in all four animals that received 28 mL. The animals in the 40-mL group did not recover from the procedure and were euthanized within 48 h. Increases in HVPG after 6-8 weeks versus baseline reached statistical significance (P < .05). Correlation between degree of fibrosis and volume of embolic agent did not reach statistical significance, but there was a trend toward increased fibrosis in the 28-mL group compared with the 16-mL group.

CONCLUSIONS

Transcatheter hepatic arterial embolization can be used to create a reliable and reproducible porcine model of liver cirrhosis and portal hypertension.

Sustained virologic response to antiviral therapy for chronic hepatitis C virus infection: a cure and so much more

Sustained virologic response (SVR) is defined as aviremia 24 weeks after completion of antiviral therapy for chronic hepatitis C virus (HCV) infection. In analyses of SVR durability, the incidence of late relapse is extremely low (<1%). Histologic regression of both necroinflammation and fibrosis has been demonstrated in paired liver biopsy samples in SVR-achieving patients. More noteworthy is the sustained responder's favorable prognosis even with baseline cirrhosis; despite mostly retrospective analyses, relative to nonresponders or to those untreated, patients with SVR have significantly fewer liver-related complications, less hepatocellular carcinoma, and fewer liver-related deaths. Although HCV is associated with insulin resistance, successful eradication of HCV appears to reduce the risk of impaired fasting glucose and diabetes development. In summary, chronic HCV infection is curable with SVR attainment, and with cure comes improved liver histology and more favorable clinical outcomes, in comparison with patients who do not achieve the same therapeutic milestone.

Therapeutics Based on microRNA: A New Approach for Liver Cancer

Hepatocellular carcinoma (HCC) is a serious public health hazard. Polygenes involvement, accumulation of genetic and epigenetic changes and immune response of viral vector during gene therapy have resulted in the high mortality rate without marked change. To provide a safeguard for gene therapy and the feasibility for a clinical application, efforts have been focused predominantly upon constructing liver-targeted vector recently. MicroRNAs (miRNAs), a class of short endogenous RNAs, regulate the gene expression at the post-transcriptional level through imperfect base pairing with the 3′-untranslated region of target mRNAs. miRNAs, especially the liver-specific miRNA: miR-122, have multiple functions in liver development and abnormal expression of miRNAs could lead to liver diseases. Altered miRNA expressions have been observed in HCCs, viral hepatitis and hepatic fibrosis. The different expression profiles of miRNAs in HCC suggest that miRNAs may serve as either novel potential targets acting directly as oncogenes or therapeutic molecules working as tumor suppressor genes. Moreover, the abundance in general and liver specificity in particular, all together make them attractive to be considered as elements for hepatic specific targeting viral vector. This review describes recent progress in miRNA investigation on liver associated for better understanding the relationship between miRNA and liver cancer in order to raise prospects for therapy.

Cannabidiol causes activated hepatic stellate cell death through a mechanism of endoplasmic reticulum stress-induced apoptosis

The major cellular event in the development and progression of liver fibrosis is the activation of hepatic stellate cells (HSCs). Activated HSCs proliferate and produce excess collagen, leading to accumulation of scar matrix and fibrotic liver. As such, the induction of activated HSC death has been proposed as a means to achieve resolution of liver fibrosis. Here we demonstrate that cannabidiol (CBD), a major non-psychoactive component of the plant Cannabis sativa, induces apoptosis in activated HSCs through a cannabinoid receptor-independent mechanism. CBD elicits an endoplasmic reticulum (ER) stress response, characterized by changes in ER morphology and the initiation of RNA-dependent protein kinase-like ER kinase-, activating transcription factor-6-, and inositol-requiring ER-to-nucleus signal kinase-1 (IRE1)-mediated signaling cascades. Furthermore, CBD induces downstream activation of the pro-apoptotic IRE1/ASK1/c-Jun N-terminal kinase pathway, leading to HSC death. Importantly, we show that this mechanism of CBD-induced ER stress-mediated apoptosis is specific to activated HSCs, as it occurs in activated human and rat HSC lines, and in primary in vivo-activated mouse HSCs, but not in quiescent HSCs or primary hepatocytes from rat. Finally, we provide evidence that the elevated basal level of ER stress in activated HSCs has a role in their susceptibility to the pro-apoptotic effect of CBD. We propose that CBD, by selectively inducing death of activated HSCs, represents a potential therapeutic agent for the treatment of liver fibrosis.

Pathogenesis of liver fibrosis

Liver fibrosis is a major cause of morbidity and mortality worldwide due to chronic viral hepatitis and, more recently, from fatty liver disease associated with obesity. Hepatic stellate cell activation represents a critical event in fibrosis because these cells become the primary source of extracellular matrix in liver upon injury. Use of cell-culture and animal models has expanded our understanding of the mechanisms underlying stellate cell activation and has shed new light on genetic regulation, the contribution of immune signaling, and the potential reversibility of the disease. As pathways of fibrogenesis are increasingly clarified, the key challenge will be translating new advances into the development of antifibrotic therapies for patients with chronic liver disease.

Effects of postprandial state and mesenteric blood flow on the repeatability of MR elastography in asymptomatic subjects

PURPOSE

To determine the repeatability of stiffness measurements in the liver using MR elastography (MRE) during the fasted and fed states. MRE has gained increased recognition as a noninvasive method to quantify fibrotic changes in the liver. It is well known that eating increases splanchnic blood flow, and fasting status of patients has been recognized as a factor that may affect hepatic stiffness measured with MRE.

MATERIALS AND METHODS

Hepatic MRE stiffness and flow through the superior mesenteric vein (SMV) were measured in 12 healthy subjects in fasted and fed states, and measurements were repeated 5 weeks later. A linear mixed effects model was used to estimate the sources of variability in the data, which included day (exams on different days) and subject. Sources were combined to calculate the overall standard deviation of a single MRE measurement.

RESULTS

The total within-subject standard deviation of an MRE exam is 8.5% (standard error [SE] = 1.7%) or 9.0% (SE = 1.8%) for fasted and fed states, respectively. No significant differences between fasted/fed state stiffness and no correlation between hepatic stiffness and SMV flow were observed.

CONCLUSION

As seen in this smaller population, healthy subjects scanned in a known fasted or fed state provide repeatable stiffness estimates with no relationship to SMV flow.

Anti-fibrogenic strategies and the regression of fibrosis

Liver fibrosis is an outcome of many chronic diseases, and often results in cirrhosis, liver failure, and portal hypertension. Liver transplantation is the only treatment available for patients with advanced stage of fibrosis. Therefore, alternative methods are required to develop new strategies for anti-fibrotic therapy. Available treatments are designed to substitute for liver transplantation or bridge the patients, they include inhibitors of fibrogenic cytokines such as TGF-β1 and EGF, inhibitors of rennin angiotensin system, and blockers of TLR4 signalling. Development of liver fibrosis is orchestrated by many cell types. However, activated myofibroblasts remain the primary target for anti-fibrotic therapy. Hepatic stellate cells and portal fibroblasts are considered to play a major role in development of liver fibrosis. Here we discuss the origin of activated myofibroblasts and different aspects of their activation, differentiation and potential inactivation during regression of liver fibrosis.

Liver stiffness assessment by tagged MRI of cardiac-induced liver motion

Cirrhosis is an important and growing public health problem, affecting millions of Americans and many more people internationally. A pathological hallmark of the progression to cirrhosis is the development of liver fibrosis, so that monitoring the appearance and progression of liver fibrosis can be used to guide therapy. Here, we report a method to use magnetization-tagged magnetic resonance imaging to measure the cardiac-induced motion and deformation in the liver, as a means for noninvasively assessing liver stiffness, which is related to fibrosis. The initial results show statistically significant differences between healthy and cirrhotic subjects in the direct comparisons of the maximum displacement (mm), and the maximum (P1) and minimum (P2) two-dimensional strains, through the cardiac cycle (3.514 ± 0.793, 2.184 ± 0.611; 0.116 ± 0.043, 0.048 ± 0.011; -0.094 ± 0.020, -0.041 ± 0.015; healthy, cirrhosis, respectively; P < 0.005 for all). There are also significant differences in the displacement-normalized P1 and P2 strains (mm(-1) ) (0.030 ± 0.008, 0.017 ± 0.007; -0.024 ± 0.006, -0.013 ± 0.004; healthy, cirrhosis, respectively; P < 0.005 for all). Therefore, this noninvasive imaging-based method is a promising means to assess liver stiffness using clinically available imaging tools.

T1rho MR imaging is sensitive to evaluate liver fibrosis: an experimental study in a rat biliary duct ligation model

PURPOSE

To correlate spin-lattice relaxation time in the rotating frame (T1ρ) measurements with degree of liver fibrosis in a rat model.

MATERIALS AND METHODS

The protocols and procedures were approved by the local Animal Experimentation Ethics Committee. Liver fibrosis was induced with biliary duct ligation (BDL). Two studies, 1 month apart, were performed with a 3-T clinical imager. The first study involved longitudinal magnetic resonance (MR) imaging follow-up of BDL rats (n = 8) and control rats (n = 4) on days 8, 15, 21, and 29 after BDL. The second study involved MR imaging of another group of BDL and control rats (n = 5 for each) on days 24 and 38 after BDL. Hematoxylin-eosin and picrosirius red staining were performed in liver specimens from days 8, 15, 24, and 38 after BDL. Repeated-measures analysis of variance was used, and treatment groups were compared (Bonferroni adjustment).

RESULTS

On day 8, there were proliferation of bile duct and inflammatory cell infiltration around portal triads. While there was overlap, BDL rats (n = 8) demonstrated higher mean liver T1ρ values than did control rats (n = 4) on day 8 (46.7 msec ± 2.9 [standard deviation] vs 44.7 msec ± 1.2, P = .4). On day 15, BDL rats demonstrated liver fibrosis with a background of inflammatory infiltration. On day 15, mean T1ρ values in BDL rats could be largely separated from those in control rats (52.6 msec ± 6.0 vs 43.8 msec ± 1.5, P = .02). On day 24, BDL rats had liver T1ρ values 23.5% higher than in control rats (n = 5 for each group, P = .0007). Histomorphometric analysis showed that collagen content increased after surgery from days 8 to 24 (n = 6 for each group, P < .0001), with no further increase between days 24 and 38 (n = 6 for each group, P >.99).

CONCLUSION

In this model, liver fibrosis was detected with T1ρ MR imaging; the degree of fibrosis was correlated with degree of increase in T1ρ measurements.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101638/-/DC1.

Hepatitis C virus RNA replication in human stellate cells regulates gene expression of extracellular matrix-related molecules

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease, including chronic hepatitis, fibrosis, and cirrhosis. Fibrosis often develops in HCV-infected livers and ultimately leads to cirrhosis and carcinoma. During fibrosis, hepatic stellate cells (HSC) play important roles in the control of extracellular matrix synthesis and degradation in fibrotic livers. In this study, we established a subgenomic replicon (SGR) cell line with human hepatic stellate cells to investigate the effect of HCV RNA replication on HSC. Isolated SGR clones contained HCV RNA copy numbers ranging from 10(4) to 10(7) per μg total RNA, and long-term culture of low-copy number SGR clones resulted in markedly increased HCV RNA copy numbers. Furthermore, HCV RNA replication affected gene expression of extracellular matrix-related molecules in both hepatic stellate cells and hepatic cells, suggesting that HCV RNA replication and/or HCV proteins directly contribute to liver fibrosis. The HCV RNA-replicating hepatic stellate cell line isolated in this study will be useful for investigating hepatic stellate cell functions and HCV replication machinery.

Texture analysis of liver fibrosis microscopic images: a study on the effect of biomarkers

Chronic hepatic injury results in liver fibrosis with eventual progression to irreversible cirrhosis. Liver fibrogenesis involves the activation of the quiescent hepatic stellate cell into an activated myofibroblast that is characterized by α-smooth muscle actin (α-SMA) expression and the production of collagens (types I and III). In the present study, rats were randomly divided into three groups: (i) control group, where rats were only treated with a vehicle; (ii) fibrosis group, where rats were treated with carbon tetrachloride (CCl(4)) to induce liver fibrosis; and (iii) silymarin group, where rats were protected with silymarin during CCl(4) treatment. Rats were sacrificed and sections of liver tissue were counterstained with hematoxylin and eosin and Masson's trichrome. Other sections were immunostained using collagens and α-SMA primary antibodies. Fibrosis was confirmed using serum marker measurements. Microscopic images of the stained sections were acquired and digitized. The Biomarker Index of Fibrosis (BIF) was calculated from the images by quantifying the percentage of stained fibers. Statistical methods of texture analysis (TA), namely co-occurrence and run-length matrices, were applied on the digital images followed by classification using agglomerative hierarchical clustering and linear discriminant analysis with cross validation. TA applied on different biomarkers was successful in discriminating between the groups, showing 100% sensitivity and specificity for classification between the control and fibrosis groups using any biomarker. Some classification attempts showed dependence on the biomarker used, especially for classification between the silymarin and fibrosis groups, which showed optimal results using Masson's trichrome. TA results were consistent with both BIF and serum marker measurements.

Expression of survivin in activated hepatic stellate cells and effect of transfection of antisense oligonucleotide targeting the survivin gene on apoptosis of HSC-T6 cells

AIM: To investigate the expression of survivin in activated hepatic stellate cell (HSC) and the effect of transfection of antisense oligonucleotide (ASODN) targeting the survivin gene on apoptosis of HSC-T6 cells.

METHODS: The experiment set the control group which not added liposome and oligonucleotide (ODN), liposome group which only added liposome, sense oligonucleotide (SODN) group (1 000 nmol/L) and 400, 800, 1 000 nmol/L ASODN group. The expression of survivin protein in activated HSC, hepatic carcinoma cells, and normal liver cells was detected by immunofluorescence. ASODN targeting the survivin gene was transfected into HSC-T6 cells with LipofectamineTM 2000, and transfection efficiency was detected by fluorescence microscopy. Forty-eight hours after transfection, the changes in survivin mRNA and protein expression were assessed by RT-PCR and Western blot, respectively, and cell apoptosis was measured by PI staining and flow cytometry.

RESULTS: The positive rate of survivin expression in activated HSC was significantly higher than that in normal liver cells (66.07% ± 8.55% vs 9.74% ± 2.68%, P < 0.05). The positive rate of survivin expression was highest in hepatic carcinoma cells among the three groups of cells (69.41% ± 9.10%). Strong green fluorescence was observed by fluorescence microscopy in cells transfected with different concentrations of ASODN, and the transfection efficiency reached 80%. Compared with blank control cells and cells transfected with empty lipofectamineTM 2000 or control oligonucleotide, the expression levels of survivin mRNA (0.94 ± 0.03, 0.95 ± 0.04 and 0.92 ± 0.04 vs 0.64 ± 0.02, 0.54 ± 0.02 and 0.26 ± 0.01) and protein (0.84 ± 0.02, 0.82 ± 0.03 and 0.81 ± 0.02 vs 0.53 ± 0.02, 0.38 ± 0.01 and 0.20 ± 0.01) were significantly decreased (all P < 0.01), and the apoptosis rate (19.00% ± 0.53%, 29.80% ± 1.54% and 48.70% ± 2.00%, respectively) significantly increased (all P < 0.01) in cells transfected with different concentrations of ASODN.

CONCLUSION: Survivin is highly expressed in activated HSC-T6 cells. Down-regulation of survivin expression by transfection of ASODN targeting the survivin gene can induce apoptosis of HSC-T6 cells.

Fibrogenic cell phenotype modifications during remodelling of normal and pathological human liver in cultured slices

BACKGROUND

The debate concerning the potential remodelling and/or reversibility of cirrhotic lesions and biliary fibrosis is still open.

AIMS/METHODS

In this work, we have used the precision-cut liver slice (PCLS) model, which maintains cell-cell and cell-matrix interactions to study, by immunohistochemistry, the behaviour of the different fibrogenic cells, i.e. hepatic stellate cells (HSC) and portal fibroblasts, in cultured (for 1 week) PCLS derived from normal and fibrotic human livers.

RESULTS

In normal liver, before and after culture, α-smooth muscle (SM) actin was present only in the vessel walls. Platelet-derived growth factor (PDGF) receptor-β was expressed before and after culture by portal fibroblasts, and appeared after culture in HSC. Before culture, CD 34 was not expressed in parenchyma, but appeared after culture in sinusoidal endothelial cells. In cirrhotic lesions, before culture, α-SM actin, PDGF receptor-β and Thy-1 were expressed in septa; after culture, α-SM actin expression disappeared but the expression of the PDGF receptor-β and Thy-1 was maintained. In cholestatic liver specimens, α-SM actin, PDGF receptor-β and Thy-1 expression, which was present before culture in enlarged portal areas, disappeared after culture, and apoptosis was detected. In the parenchyma of both cirrhotic and cholestatic livers, the expression of the PDGF receptor-β and of CD 34, which was not observed before culture, was present in HSC and sinusoidal endothelial cells, respectively, after culture.

CONCLUSIONS

These results indicate that during remodelling of pathological tissues in cultured liver slices, the myofibroblastic cells derived from HSC or from portal fibroblasts show different behaviours, suggesting different mechanisms of activation/deactivation.

A Chinese Herbal Decoction, Modified Yi Guan Jian, Induces Apoptosis in Hepatic Stellate Cells through an ROS-Mediated Mitochondrial/Caspase Pathway

The Chinese herb modified Yi Guan Jian (mYGJ) is an effective regimen that is usually used in outpatients with chronic liver diseases such as fibrosis and cirrhosis. However, the mechanism for the action of mYGJ on liver fibrosis is not yet clear. In this study, we found that mYGJ induced hepatic stellate cells (HSCs) apoptosis concomitant with the downregulation of Bcl-2 expression and slight elevation of Bax level. Moreover, the reactive oxygen species (ROS) were generated in the early stages of mYGJ-induced HSCs apoptosis to facilitate calcium and cytochrome c release from the mitochondria to cytosol. Subsequently, caspase 9 and caspase 3 were activated. Furthermore, the activation of ER stress-associated caspase 12 in HSCs was also evaluated. Together, we report the first evidence-based study to demonstrate that mYGJ decoction induces HSCs apoptosis through ROS accumulation and the intrinsic apoptosis pathway. These findings provide rationale for further clinical investigation of traditional Chinese medicine recipes against liver fibrosis.

Toward surface quantification of liver fibrosis progression

Monitoring liver fibrosis progression by liver biopsy is important for certain treatment decisions, but repeated biopsy is invasive. We envision redefinition or elimination of liver biopsy with surface scanning of the liver with minimally invasive optical methods. This would be possible only if the information contained on or near liver surfaces accurately reflects the liver fibrosis progression in the liver interior. In our study, we acquired the second-harmonic generation and two-photon excitation fluorescence microscopy images of liver tissues from bile duct-ligated rat model of liver fibrosis. We extracted morphology-based features, such as total collagen, collagen in bile duct areas, bile duct proliferation, and areas occupied by remnant hepatocytes, and defined the capsule and subcapsular regions on the liver surface based on image analysis of features. We discovered a strong correlation between the liver fibrosis progression on the anterior surface and interior in both liver lobes, where biopsy is typically obtained. The posterior surface exhibits less correlation with the rest of the liver. Therefore, scanning the anterior liver surface would obtain similar information to that obtained from biopsy for monitoring liver fibrosis progression.

Acute liver failure is associated with elevated liver stiffness and hepatic stellate cell activation

Acute liver failure (ALF) is associated with massive short-term cell death, whereas chronic liver injury is accompanied by continuous cell death. Hepatic stellate cells (HSCs) contribute to tissue repair and liver fibrosis in chronic liver injury, although their role in ALF remains unexplained. Twenty-nine patients (median age = 43 years, 17 females and 12 males) with ALF according to the Acute Liver Failure Study Group criteria were included. Upon the diagnosis of ALF and after 7 days, we determined liver stiffness (LS) with FibroScan, standard laboratory parameters, and serum levels of matrix metalloproteinase 1 (MMP-1), MMP-2, MMP-9, tissue inhibitor of metalloproteinases 1 (TIMP-1), TIMP-2, hyaluronic acid, and markers of overall cell death (M65) and apoptosis (M30). Stellate cell activation and progenitor response were analyzed immunohistochemically in biopsy samples of 12 patients with alpha-smooth muscle actin (alpha-SMA), keratin-17, and keratin-19 staining, respectively. Cell death markers (M30 level = 2243 +/- 559.6 U/L, M65 level = 3732 +/- 839.9 U/L) and fibrosis markers (TIMP-1 level = 629.9 +/- 69.4 U/mL, MMP-2 level = 264 +/- 32.5 U/mL, hyaluronic acid level = 438.5 +/- 69.3 microg/mL) were significantly increased in patients versus healthy controls. This was paralleled by collagen deposition, elevated alpha-SMA expression, and higher LS (25.6 +/- 3.0 kPa). ALF was associated with ductular progenitor proliferation.

CONCLUSION

Our results demonstrate HSC activation and a progenitor response in ALF. Positive correlations between LS, the degree of liver cell damage, and the intensity of HSC activation suggest that fibrosis is a response to ALF in an attempt to repair damaged tissue.

Nonmuscle myosin-dependent synthesis of type I collagen

Type I collagen, synthesized in all tissues as the heterotrimer of two alpha1(I) polypeptides and one alpha2(I) polypeptide, is the most abundant protein in the human body. Here we show that intact nonmuscle myosin filaments are required for the synthesis of heterotrimeric type I collagen. Conserved 5' stem-loop in collagen alpha1(I) and alpha2(I) mRNAs binds the RNA-binding protein LARP6. LARP6 interacts with nonmuscle myosin through its C-terminal domain and associates collagen mRNAs with the filaments. Dissociation of nonmuscle myosin filaments results in secretion of collagen alpha1(I) homotrimer, diminished intracellular colocalization of collagen alpha1(I) and alpha2(I) polypeptides (required for folding of the heterotrimer), and their increased intracellular degradation. Inhibition of the motor function of myosin has similar collagen-specific effects, while disruption of actin filaments has a general effect on protein secretion. Nonmuscle myosin copurifies with polysomes, and there is a subset of polysomes involved in myosin-dependent translation of collagen mRNAs. These results indicate that association of collagen mRNAs with nonmuscle myosin filaments is necessary to coordinately synthesize collagen alpha1(I) and alpha2(I) polypeptides. We postulate that LARP6/myosin-dependent mechanism regulates the synthesis of heterotrimeric type I collagen by coordinating the translation of collagen mRNAs.

Advances in research of the reversal of liver fibrosis by transplantation of bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) are a group of stem cells capable of multilineage differentiation. Under given conditions, BMSCs can differentiate into a variety of cells, such as osteoblasts, chondrocytes, adipocytes, neuron-like cells and hepatocytes. In recent years, numerous studies have shown that BMSCs can not only inhibit and reduce liver fibrosis but also induce immunosuppression and immune tolerance. Therefore, transplantation of BMSCs can be used to treat end-stage liver disease.