Early hepatic stellate cell activation predicts severe hepatitis C recurrence after liver transplantation

A Comprehensive Review of Liver Allograft Fibrosis and Steatosis: From Cause to Diagnosis

Despite advances in posttransplant care, long-term outcomes for liver transplant recipients remain unchanged. Approximately 25% of recipients will advance to graft cirrhosis and require retransplantation. Graft fibrosis progresses in the context of de novo or recurrent disease. Recurrent hepatitis C virus infection was previously the most important cause of graft failure but is now curable in the majority of patients. However, with an increasing prevalence of obesity and diabetes and nonalcoholic fatty liver disease as the most rapidly increasing indication for liver transplantation, metabolic dysfunction-associated liver injury is anticipated to become an important cause of graft fibrosis alongside alloimmune hepatitis and alcoholic liver disease. To better understand the landscape of the graft fibrosis literature, we summarize the associated epidemiology, cause, potential mechanisms, diagnosis, and complications. We additionally highlight the need for better noninvasive methods to ameliorate the management of graft fibrosis. Some examples include leveraging the microbiome, genetic, and machine learning methods to address these limitations. Overall, graft fibrosis is routinely seen by transplant clinicians, but it requires a better understanding of its underlying biology and contributors that can help inform diagnostic and therapeutic practices.

Hepatic stellate cells - from past till present: morphology, human markers, human cell lines, behavior in normal and liver pathology

Hepatic stellate cell (HSC), initially analyzed by von Kupffer, in 1876, revealed to be an extraordinary mesenchymal cell, essential for both hepatocellular function and lesions, being the hallmark of hepatic fibrogenesis and carcinogenesis. Apart from their implications in hepatic injury, HSCs play a vital role in liver development and regeneration, xenobiotic response, intermediate metabolism, and regulation of immune response. In this review, we discuss the current state of knowledge regarding HSCs morphology, human HSCs markers and human HSC cell lines. We also summarize the latest findings concerning their roles in normal and liver pathology, focusing on their impact in fibrogenesis, chronic viral hepatitis and liver tumors.

Expression of 6 Biomarkers in Liver Grafts After Pediatric Liver Transplantation: Correlations with Histology, Biochemistry, and Outcome

Background

Subclinical graft inflammation and fibrosis after pediatric liver transplantation (LT) are common. Biomarkers are needed that precede and are associated with these changes and graft outcome.

Material/Methods

We evaluated immunohistochemical expression of 6 biomarkers [α-smooth muscle actin (α-SMA), collagen I, decorin, vimentin, P-selectin glycoprotein ligand-1 (PSGL-1), and CD34] in biopsies taken intraoperatively at LT (baseline) (n=29) and at 11.3 years after LT (first follow-up) (n=51). Liver biochemistry and graft histology were assessed at the first follow-up and at final assessment (19.6 years after LT) (n=48). Second follow-up biopsies for histology were available from 24 patients. The immunostainings were correlated with liver histology, biochemistry, and outcome at these time-points.

Results

Baseline levels of the biomarkers were unrelated to presence of fibrosis at follow-up. Increased α-SMA, collagen I levels, decorin, and vimentin were associated with simultaneous fibrosis at the first follow-up (p=0.001–0.027). Increased SMA, collagen I, decorin, vimentin, PSGL-1, and CD34 expression at first follow-up were associated with simultaneous portal inflammation (p=0.001–0.025). α-SMA, decorin, and vimentin expression were increased in patients without fibrosis at the first follow-up but who developed fibrosis in second follow-up (p=0.014 p=0.024 and p=0.024). Significant fibrosis (F2) and markedly increased α-SMA, collagen I, decorin, and vimentin levels at first follow-up were associated with suboptimal liver status at the final assessment (p=0.002–0.042).

Conclusions

The expression of the biomarkers at LT was unrelated to later development of graft fibrosis. α-SMA, decorin, and vimentin were associated with later graft fibrosis and suboptimal liver status.

Sinusoidal and pericellular fibrosis in adult post-transplant liver biopsies: association with hepatic stellate cell activation and patient outcome

Post-transplant sinusoidal fibrosis (SF) and pericellular fibrosis (PCF) have not been extensively investigated in adults. Fifty-two post-transplant liver biopsies from 28 consented patients (12 men, mean age 49, range 33–67 years) were studied. Tissue morphology, including an arbitrary summative fibrosis score was assessed in detail. Collagen proportionate area (CPA) and alpha-smooth muscle actin (α-SMA) immunostain were evaluated by digital image analysis (DIA). Anti-keratin 7, anti-C4d and anti-sonic hedgehog (Shh) immunostains were scored semi-quantitatively. SF was observed in 36/52 (69.2%) biopsies and most of these (20/36, 55.6%) had centrilobular fibrosis (CLF). PCF was seen in 7/52 (13.5%) biopsies exclusively in cases with CLF. CPA was significantly correlated with time since liver transplantation (p = 0.043), summative fibrosis score and its main components but not with α-SMA. α-SMA-positive area significantly correlated with the Banff rejection score (p = 0.022) and centrilobular inflammatory changes were more severe in cases with CLF (p = 0.003). Hepatocyte ballooning of cholestatic type was associated with PCF (p = 0.016) and Shh expression (p < 0.001). Sinusoidal fibrosis is a frequent occurrence in post-transplant adult livers, with predilection toward centrilobular areas. Graft age and oxidative stress may contribute to SF development, while hepatocyte ballooning may be implicated in PCF development. Hepatic stellate cell (HSC) activation is likely affected by centrilobular inflammation.

Reelin expression in human liver of patients with chronic hepatitis C infection

Reelin is a secreted extracellular glycoprotein that plays a critical role during brain development. Several studies have described Reelin expression in hepatic stellate cells of the human liver. In order to investigate the possible role of Reelin in the process of hepatic fibrogenesis, in this study we investigated Reelin expression in the liver tissue of patients infected with the Hepatitis C Virus (HCV). On this basis, Reelin expression was analysed by immunohistochemistry during liver biopsies of 81 patients with HCV-related chronic hepatitis. A Knodell score was used to stage liver fibrosis. Hepatic stellate cells/myofibroblast immunohistochemical markers (CRBP-1, alpha-SMA) were also evaluated. As further confirmed by co-localization experiments (Reelin +CRBP-1), Reelin protein was expressed by hepatic stellate cells/myofibroblasts, and a significant positive correlation was found between Reelin expression and the stage of liver fibrosis (P=0.002). Moreover, Reelin correlated with CRBP-1 positive cells (P=0.002), but not with alpha-SMA, suggesting that Reelin should not be regarded as a marker of hepatic stellate cells/myofibroblasts differentiation but rather as a functional protein expressed during some phases of liver fibrosis. Furthermore, Disabled-1 (Dab1), a Reelin adaptor protein, was expressed in cells of ductular reaction suggesting a paracrine role for Reelin with regards these elements. In conclusion, Reelin was expressed by human hepatic stellate cells/myofibroblasts and the number of these cells increased significantly in the lobule as the liver fibrosis progressed, suggesting a role for Reelin in the activation of hepatic stellate cells/myofibroblasts during liver injury. Reelin may potentially be incorporated into liver injury evaluations in combination with other histological data.

The histological quantification of alpha-smooth muscle actin predicts future graft fibrosis in pediatric liver transplant recipients

Activated hepatic stellate cells express cytoplasmic ASMA prior to secreting collagen and consequent liver fibrosis. We hypothesized that quantifying ASMA could predict severity of future fibrosis after LT. For this, 32 pairs of protocol biopsies, that is, "baseline" and "follow-up" biopsies taken at 1- to 2-year intervals from 18 stable pediatric LT recipients, transplanted between 2006 and 2012 were selected. Morphometric quantification of "ASMA-positive area percentage" was performed on the baseline biopsy. Histological and fibrosis assessment using Metavir and LAFSc was performed on all biopsies. The difference of fibrosis severity between the "baseline" and "follow-up" was termed "prospective change in fibrosis." Significant association was seen between extent of ASMA positivity on baseline biopsy and "prospective change in fibrosis" using Metavir (P=.02), cumulative LAFSc (P=.02), and portal LAFSc (P=.01) values. ASMA-positive area percentage >1.05 predicted increased fibrosis on next biopsy with 90.0% specificity. Additionally, an association was observed between extent of ASMA positivity and concomitant ductular reaction (P=.06), but not with histological inflammation in the portal tract or lobular area. Hence, ASMA quantification can predict the future course of fibrosis.

Functional Immune Anatomy of the Liver-As an Allograft

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

Development of an in vitro model to test antifibrotic drugs on primary human liver myofibroblasts

We have developed a culture model to assess antifibrotic drugs using normal human liver myofibroblasts (HLMFs) obtained from 31 subjects. Activation was evaluated in terms of α-smooth muscle actin (α-SMA) and collagen 1 (Coll1) expression using RT-PCR, and proliferation as the uptake of 5-ethynil-2'-deoxyuridine. Under analysis of variance, between-subject differences accounted for 70% of all variability and inter-experiment differences for 30%. The sensitivity of the model was determined by quantifying the effects in terms of relative expression, which were 0.74±0.03 for cyclosporine A (CsA) and 2.4±0.10 for transforming growth factor-beta (TGF-β) (P<0.0001 vs no treatment) for α-SMA expression. Inter-subject variations in α-SMA and Coll1 expression enabled the classification of subjects as potentially low or high fibrosers. Finally, we observed that pirfenidone (which has beneficial effects in vivo) significantly reduced the expressions of α-SMA and Coll1, whereas the angiotensin-converting enzyme inhibitor losartan (which has no effect in vivo) had no significant effect. Our model may thus detect the antifibrotic properties of drugs. Antifibrotic drugs with promising clinical relevance could possibly be selected using a bank of HLMFs from high fibrosers.

Relevance of activated hepatic stellate cells in predicting the development of pediatric liver allograft fibrosis

Activated hepatic stellate cells (HSCs) are the main collagen-producing cells in liver fibrogenesis. With the purpose of analyzing their presence and relevance in predicting liver allograft fibrosis development, 162 liver biopsies of 54 pediatric liver transplantation (LT) recipients were assessed at 6 months, 3 years, and 7 years after LT. The proportion of activated HSCs, identified by α-smooth muscle actin (ASMA) immunostaining, and the amount of fibrosis, identified by picrosirius red (PSR%) staining, were determined by computer-based morphometric analysis. Fibrosis was also staged by using the semiquantitative liver allograft fibrosis score (LAFSc), specifically designed to score fibrosis in the pediatric LT population. Liver allograft fibrosis displayed progression over time by PSR% (P < 0.001) and by LAFSc (P < 0.001). The ASMA expression decreased in the long term, with inverse evolution with respect to fibrosis (P < 0.01). Patients with ASMA-positive HSCs area ≥ 8% at 6 months (n = 20) developed a higher fibrosis proportion compared to those with ASMA-positive HSCs area ≤ 8% (n = 34) at the same period of time and in the long term (P = 0.03 and P < 0.01, respectively), but not at 3 years (P = 0.8). ASMA expression ≥ 8% at 6 months was found to be an independent risk factor for 7-year fibrosis development by PSR% (r(2) = 0.5; P < 0.01) and by LAFSc (r(2) = 0.3; P = 0.03). Furthermore, ASMA expression ≥ 8% at 3 years showed an association with the development of fibrosis at 7 years (P = 0.02). In conclusion, there is a high proportion of activated HSCs in pediatric LT recipients. ASMA ≥ 8% at 6 months seems to be a risk factor for early and longterm fibrosis development. In addition, activated HSCs showed inverse evolution with respect to fibrosis in the long term. Liver Transplantation 22 822-829 2016 AASLD.

Serum aspartate aminotransferase levels and previous histopathological findings enable reduction of protocol liver biopsies after liver transplantation for hepatitis C

BACKGROUND

Hepatitis C virus (HCV) infection remains the leading indication for liver transplantation (LT) worldwide. Recurrent hepatitis C following LT is universal, and significant fibrosis (SF, Metavir fibrosis stage ≥2) apparent on protocol biopsy typically prompts antiviral therapy.

OBJECTIVE

To determine the optimal timing of protocol liver biopsies in this setting.

METHODS

A total of 151 patients who underwent LT related to HCV infection between July 2004 and December 2009 were analyzed retrospectively. Data regarding protocol liver biopsies at six, 12 and 24 months post-LT, conventional laboratory parameters and demographic information were obtained.

RESULTS

The 151 patients included in the present study had significantly lower serum aspartate aminotransferase (AST) levels than the four patients who progressed to receive antiviral treatment for SF before six months post-LT (P<0.001). AST level, but not alanine aminotransferase level, histological activity or fibrosis stage at the six-month biopsy was independently associated with the progression to SF at 12 months (P<0.05). However, AST level, histological activity and fibrosis stage at the 12-month biopsy emerged as independent parameters associated with progression to SF at 24 months (P<0.05).

CONCLUSION

The protocol liver biopsy at six months could be eliminated, especially in patients who consistently exhibit low AST levels. Histological activity, the presence or absence of fibrosis, and AST values at the 12-month biopsy may lead to the decision to defer the protocol biopsy at 24 months or result in earlier introduction of antiviral therapy.

Recurrent HCV after liver transplantation-mechanisms, assessment and therapy

Chronic HCV infection is the leading indication for liver transplantation. However, as a result of HCV recurrence, patient and graft survival after liver transplantation are inferior compared with other indications for transplantation. HCV recurrence after liver transplantation is associated with considerable mortality and morbidity. The development of HCV-related fibrosis is accelerated after liver transplantation, which is influenced by a combination of factors related to the virus, donor, recipient, surgery and immunosuppression. Successful antiviral therapy is the only treatment that can attenuate fibrosis. The advent of direct-acting antiviral agents (DAAs) has changed the therapeutic landscape for the treatment of patients with HCV. DAAs have improved tolerability, and can potentially be used without PEG-IFN for a shorter time than previous therapies, which should result in better outcomes. In this Review, we describe the important risk factors that influence HCV recurrence after liver transplantation, highlighting the mechanisms of fibrosis and the integral role of hepatic stellate cells. Indirect and direct assessment of fibrosis, in addition to new antiviral therapies, are also discussed.

Analysis of the intrahepatic ductular reaction and progenitor cell responses in hepatitis C virus recurrence after liver transplantation

Fibrosis in livers with hepatitis C virus (HCV) recurrence after liver transplantation (LT) can be rapidly progressive, and the mechanisms underlying this process are poorly understood. In livers with HCV infections in the non-LT setting, there is a significant relationship between the development of structures known as the ductular reaction (DR), hepatic progenitor cells (HPCs), and fibrosis. This study characterizes the DR, HPCs, and fibrosis associated with HCV recurrence after LT. Immunohistochemistry and confocal microscopy were used to characterize the DR, HPC, and fibrosis in liver biopsy specimens. Key findings were confirmed in a separate, independent cohort. The initial characterization cohort had 194 biopsy samples from 105 individuals with HCV recurrence after LT. The immunophenotype, morphology, and location of the DR were consistent with an HPC origin. The DR correlated with intrahepatic fibrosis (rs  = 0.529, P < 0.001) and the number of activated hepatic stellate cells (HSCs; rs  = 0.446, P < 0.001). There was an early occurrence of hepatocyte replicative arrest as well as increased hepatocyte proliferation that correlated with the DR (rs  = 0.295, P < 0.001). Replicative arrest preceded hepatocyte proliferation in early-stage injury. Hepatocyte proliferation decreased with advanced fibrosis; in contrast, the extent of the DR and the number of activated HSCs continued to increase. In the second cohort of 37 individuals, the DR and the number of HPCs similarly correlated with fibrosis and inflammation after LT. In conclusion, this is the first characterization of the DR in HCV-associated liver injury after LT. There was a significant correlation between the DR and the development of progressive fibrosis in HCV recurrence. These results suggest a pivotal role for both the DR and the HPC responses in the aggressive fibrosis seen with HCV recurrence after LT.

Early periportal sinusoidal fibrosis is an accurate marker of accelerated HCV recurrence after liver transplantation

BACKGROUND & AIMS

Significant liver fibrosis (F ⩾ 2) and portal hypertension (hepatic venous pressure gradient [HVPG] ⩾ 6 mmHg) 1 year after liver transplantation (LT) are predictors of severe hepatitis C recurrence. Periportal sinusoidal fibrosis (SF) is an early expression of the fibrogenic process in response to liver injury. We aimed to evaluate whether SF in early liver biopsies represents an early and accurate marker for identifying patients with severe HCV recurrence after LT.

METHODS

A total of 101 HCV LT patients with early biopsy (<6 months), and HVPG measurement and/or liver biopsy one year after LT were included. Early biopsies were stained with Sirius Red and SF was graded semi-quantitatively. Results were compared between groups (significant SF vs. non-significant SF) and correlated with the development of severe HCV recurrence one year after LT.

RESULTS

Patients with early significant SF had older donor age and higher necroinflammatory activity (NIA). The presence of early significant SF enabled identification of 78.9% and 90.6% of patients with F ⩾ 2 and HVPG ⩾ 6 mmHg, respectively, one year after LT. Donor age and NIA were independent predictors of significant fibrosis (F ⩾ 2) one year after LT, whereas donor age, ALT (3 months), NIA, and SF grade were independent predictors of portal hypertension (HVPG ⩾ 6).

CONCLUSIONS

Significant SF in early biopsies is a good predictor of severe hepatitis C recurrence. This histological finding, when combined with simple variables, may be useful to select the best candidates for early antiviral therapy after LT.

A new strategy for treatment of liver fibrosis: letting MicroRNAs do the job

MicroRNAs (miRNAs) are short, endogenous, noncoding RNA molecules that regulate gene expression at a post-translational level. MiRNAs have been recognized in the regulation of physiological conditions. Moreover, awareness of the association between dysregulated miRNAs and human diseases is increasing, which consequently brings miRNAs to the frontline in the development of novel therapeutic strategies. We review the latest advances in our knowledge of the involvement of miRNAs in fibrosis with particular emphasis on hepatic fibrosis and the possibilities in the near future for miRNA-based therapy for targeted treatment of liver fibrosis. With recent advances in our understanding of the important role of senescence in the resolution of activated hepatic stellate cells (HSCs), we suggested the therapeutic potential of inducing activated HSCs into senescence by an miRNA-based strategy.

Digital image analysis of collagen assessment of progression of fibrosis in recurrent HCV after liver transplantation

BACKGROUND & AIMS

Histological assessment of fibrosis progression is currently performed by staging systems which are not continuous quantitative measurements. We aimed at assessing a quantitative measurement of fibrosis collagen proportionate area (CPA), to evaluate fibrosis progression and compare it to Ishak stage progression.

METHODS

We studied a consecutive cohort of 155 patients with recurrent HCV hepatitis after liver transplantation (LT), who had liver biopsies at one year and were subsequently evaluated for progression of fibrosis using CPA and Ishak staging, and correlated with clinical decompensation. The upper quartile of distribution of fibrosis rates (difference in CPA or Ishak stage between paired biopsies) defined fast fibrosers.

RESULTS

Patients had 610 biopsies and a median follow-up of 116 (18-252) months. Decompensation occurred in 29 (18%) patients. Median Ishak stage progression rate was 0.42 units/year: (24 (15%) fast fibrosers). Median CPA fibrosis progression rate was 0.71%/year (36 (23%) fast fibrosers). Clinical decompensation was independently associated by Cox regression only with CPA (p=0.007), with AUROCs of 0.81 (95% CI 0.71-0.91) compared to 0.68 (95% CI 0.56-0.81) for Ishak stage. Fast fibrosis defined by CPA progression was independently associated with histological de novo hepatitis (OR: 3.77), older donor age (OR: 1.03) and non-use/discontinuation of azathioprine before 1 year post-LT (OR: 3.85), whereas when defined by Ishak progression, fast fibrosers was only associated with histological de novo hepatitis.

CONCLUSIONS

CPA fibrosis progression rate is a better predictor of clinical outcome than progression by Ishak stage. Histological de novo hepatitis, older donor age and non-use/discontinuation of azathioprine are associated with rapid fibrosis progression in recurrent HCV chronic hepatitis after liver transplantation.

Serum biomarkers in type 2 diabetic patients with non-alcoholic steatohepatitis and advanced fibrosis

AIM

Advanced stages of non-alcoholic fatty liver disease (NAFLD) are highly prevalent in type 2 diabetes (T2DM), however, no diabetes-related or biochemical variable seems to be predictive of severity of NAFLD. The aim of this study was to investigate the association of several serum biomarkers with the more severe histopathological stages of NAFLD in T2DM.

METHODS

In a cross-sectional design, 84 T2DM patients with biopsy-proven NAFLD had adiponectin, tumor necrosis factor-α, transforming growth factor (TGF)-β1, interleukin (IL)-6, -8 and -10, and C-reactive protein measured. NAFLD severity was evaluated by two hepatopathologists according to the non-alcoholic steatohepatitis (NASH) Clinical Research Network scoring system. Independent associations of cytokines with NASH and advanced fibrosis were evaluated by multivariate logistic regressions.

RESULTS

Sixty-six patients (78.6%) had NASH, and 52 patients (61.9%) had advanced fibrosis considering the highest score between the two pathologists. Patients with NASH or with advanced fibrosis had equal cytokine levels to those without NASH or with absent/light fibrosis, except for a lower serum adiponectin (8.59 vs 12.77 μg/mL; P = 0.015) in patients with NASH and a lower TGF-β1 (170 vs 180 pg/mL; P = 0.026) in patients with advanced fibrosis. In multivariate analysis, lower adiponectin was independently associated with NASH (odds ratio = 7.7, 95% confidence interval = 1.5-39.9, P = 0.014, for the subgroup with adiponectin below the median value), whereas both lower adiponectin and lower TGF-β1 levels were associated with advanced fibrosis.

CONCLUSION

Low adiponectin and low TGF-β1 are associated with severest NAFLD stages in T2DM and may be a valuable tool to support liver biopsy indication in this setting.

Hepatic stellate cells preferentially induce Foxp3+ regulatory T cells by production of retinoic acid

The liver has long been described as immunosuppressive, although the mechanisms underlying this phenomenon are incompletely understood. Hepatic stellate cells (HSCs), a population of liver nonparenchymal cells, are potent producers of the regulatory T cell (Treg)-polarizing molecules TGF-β1 and all-trans retinoic acid, particularly during states of inflammation. HSCs are activated during hepatitis C virus infection and may therefore play a role in the enrichment of Tregs during infection. We hypothesized that Ag presentation in the context of HSC activation will induce naive T cells to differentiate into Foxp3(+) Tregs. To test this hypothesis, we investigated the molecular interactions between murine HSCs, dendritic cells, and naive CD4(+) T cells. We found that HSCs alone do not present Ag to naive CD4(+) T cells, but in the presence of dendritic cells and TGF-β1, preferentially induce functional Tregs. This Treg induction was associated with retinoid metabolism by HSCs and was dependent on all-trans retinoic acid. Thus, we conclude that HSCs preferentially generate Foxp3(+) Tregs and, therefore, may play a role in the tolerogenic nature of the liver.

Hepatic stellate cells preferentially induce Foxp3+ regulatory T cells by production of retinoic acid

The liver has long been described as immunosuppressive, although the mechanisms underlying this phenomenon are incompletely understood. Hepatic stellate cells (HSCs), a population of liver nonparenchymal cells, are potent producers of the regulatory T cell (Treg)-polarizing molecules TGF-β1 and all-trans retinoic acid, particularly during states of inflammation. HSCs are activated during hepatitis C virus infection and may therefore play a role in the enrichment of Tregs during infection. We hypothesized that Ag presentation in the context of HSC activation will induce naive T cells to differentiate into Foxp3(+) Tregs. To test this hypothesis, we investigated the molecular interactions between murine HSCs, dendritic cells, and naive CD4(+) T cells. We found that HSCs alone do not present Ag to naive CD4(+) T cells, but in the presence of dendritic cells and TGF-β1, preferentially induce functional Tregs. This Treg induction was associated with retinoid metabolism by HSCs and was dependent on all-trans retinoic acid. Thus, we conclude that HSCs preferentially generate Foxp3(+) Tregs and, therefore, may play a role in the tolerogenic nature of the liver.

Recurrent hepatitis C and acute allograft rejection: clinicopathologic features with emphasis on the differential diagnosis between these entities

Chronic hepatitis C virus infection is the leading etiology for liver transplantation in the United States. Recurrent hepatitis C occurs nearly universally in these patients and represents a serious posttransplantation complication. Despite the detailed characterization of the histologic features of both recurrent hepatitis C and acute cellular rejection (ACR) over the last decades, the pathologic distinction between these 2 conditions remains one of the greatest diagnostic challenges in liver pathology. An accurate diagnosis, nevertheless, plays an essential role in patient management, as different therapeutic strategies are used for these conditions. In this review, the clinicopathologic features of posttransplantation recurrent hepatitis C and ACR are discussed, with emphasis on distinguishing histopathologic features, morphologic variants, ancillary techniques, and diagnostic pitfalls.

Evolution of hepatic fibrosis research

Molecular analysis of hepatic fibrogenesis has progressed with respect to both fibrosis progression and regression by using cell biological, molecular biological and (epi)genetic approaches. Recent researches have revealed sources of collagen-producing cells other than hepatic stellate cells in the liver, and the involvement of the innate immune system and oxidative stress in the fibrotic process has attracted new attention. Together with these advancements in basic knowledge on the cellular and molecular biology of hepatic fibrosis, clinical researches have linked the clarification of the relationship between progression of the fibrosis stage and therapeutic efficacy for chronic viral hepatitis and non-alcoholic steatohepatitis and validation of the regression of advanced fibrosis, even cirrhosis, of appropriate therapies using modern medicines. Furthermore, non-invasive assessment of liver fibrosis using an ultrasound-based modality has become a focus in the clinical diagnosis of liver fibrosis instead of liver biopsy. Taken together, liver fibrosis research has been evolving both basically and clinically in the past three decades.

Transforming growth factor β1 polymorphisms and progression of graft fibrosis after liver transplantation for hepatitis C virus--induced liver disease

Re-infection with the hepatitis C virus (HCV) is an important development after liver transplantation (LT); it can lead to graft fibrosis. The aim of this study was to assess the role of transforming growth factor β1 (TGF-β1) polymorphisms in the development of HCV-related graft disease by evaluating protocol liver biopsies. A total of 192 patients with a recurrence of HCV infection after LT were genotyped for TGF-β1 codon 10 (C→T) and codon 25 (G→C) using the polymerase chain reaction. Histological evaluation of 614 protocol liver biopsies obtained from these patients was undertaken using the classification of Desmet and Scheuer to stage the degree of fibrosis. Mild stages of fibrosis (0-2) were compared to advanced stages of fibrosis (3-4) that developed during the period of infection with the virus. Correlations between the prevalence of TGF-β1 genotypes and the different degrees of fibrosis that developed were determined. No statistically significant differences were found for genotype distributions (codons 10 and 25) with respect to recipient age, donor sex, occurrence of acute cellular rejection, and response to antiviral therapy. However, the C allele at codon 25 was significantly less frequent in the group with advanced fibrosis (P = 0.001). Furthermore, a positive association was found between progression of fibrosis and male recipient sex (P = 0.024), donor age (P = 0.041), and viral genotype 1b (P = 0.002). In conclusion, this study, in which the evolution of hepatic fibrosis was assessed histologically in a large cohort of patients with HCV re-infection after LT, has demonstrated that the C allele at codon 25 of the TGF-β1 gene is a marker for the development of graft fibrosis.

Value of α-smooth muscle actin and glial fibrillary acidic protein in predicting early hepatic fibrosis in chronic hepatitis C virus infection

INTRODUCTION

α-Smooth muscle actin (α-SMA)-positive hepatic stellate cells (HSCs) are pericytes responsible for fibrosis in chronic liver injury. The glial fibrillary acidic protein (GFAP), commonly expressed by astrocytes in the central nervous system, is expressed in vivo in the liver in a subpopulation of quiescent stellate cells. The reports concerning GFAP expression in human liver are still conflicting. The aim of the study is investigation the utility of GFAP compared to α-SMA as an indicator of early activated HSCs, in predicting fibrosis in chronic hepatitis C (CHC) patients.

MATERIAL AND METHODS

With immunohistochemistry and a semi-quantitative scoring system, the expressions of α-SMA and GFAP on HSCs in liver biopsies from patients with pure CHC (n = 34), hepatitis C virus-induced cirrhosis (n = 24), mixed CHC/schistosomiasis (n = 11) and normal controls (n = 10) were analysed.

RESULTS

The immunoreactivity of α-SMA and GFAP in perisinusoidal, periportal and pericentral areas was assessed. α-Smooth muscle actin and GFAP-positive HSCs were significantly increased in all diseased groups compared with normal controls. In pure CHC with or without cirrhosis, perisinusoidal α-SMA-positive HSCs were predominant in relation to GFAP-positive cells. On the other hand, GFAP-positive cells were predominant in the group of schistosomiasis as compared with the other diseased groups. It was noticed that expression of GFAP on perisinusoidal HSCs in CHC patients sequentially decreased with the progression of fibrosis.

CONCLUSIONS

Glial fibrillary acidic protein could represent a more useful marker than α-SMA of early activation of HSCs in CHC patients and seems to be an early indicator of hepatic fibrogenesis.

Evolution of hepatitis C virus in liver allografts

1. Hepatitis C virus (HCV) RNA+ liver allograft recipients invariably reinfect the liver allograft within hours after transplantation, and the majority (>70%) develop chronic hepatitis. The rate at which these patients experience progression to cirrhosis and the overall percentage are significantly increased in comparison with HCV infection in the nontransplant setting. 2. Core needle biopsy evaluation is used to establish the diagnosis of recurrent HCV, which can be difficult to distinguish from acute cellular rejection and other causes of allograft dysfunction. In the vast majority of cases, however, distinguishing recurrent HCV from other posttransplant syndromes is reliably achieved by a careful examination of hematoxylin and eosin-stained sections and correlation with clinical and serological data. 3. Recurrent HCV often coexists with other causes of liver allograft dysfunction, and the determination of the most important cause of injury and whether other causes of injury are present is important. Included are residual changes of preservation/reperfusion injury, biliary sludging/structuring, acute cellular and chronic rejection, and autoimmune hepatitis. 4. The complex interplay between immunosuppression management, viral replication, and the recipient immune system results in distinct patterns of recurrent chronic HCV in the liver allograft: (1) conventional or usual acute and chronic HCV, which resembles that seen in the general population with HCV; (2) fibrosing cholestatic hepatitis; and (3) plasma cell-rich HCV, which might represent a variant of, or overlap with, autoimmune hepatitis and rejection. 5. The variable but usually hastened histopathological progression toward cirrhosis in HCV+ allografts is similar to that seen in the nontransplant setting, but in allografts, the overall severity of lymphocytic inflammation is less, and ductular reactions, stellate cell activation, and subsinusoidal fibrosis are accentuated. Hepatic stressors and causes of an impaired ability of hepatocytes to replicate include persistently high levels of viral replication, HCV-specific CD4+ T responses, advanced donor age, high levels or rapid withdrawal of immunosuppression, and coexistent liver damage from preservation/reperfusion injury, biliary structuring, or coexistent cytomegalovirus or herpes 6 viral infection. 6. Immunological effector mechanisms involved in the rejection and control of HCV replication/HCV elimination show significant overlap. Patients with very high levels of HCV RNA rarely show significant clinically significant acute or chronic rejection, whereas their occurrence is frequently associated with very low levels or clearance of HCV RNA. Studying the evolution from recurrent HCV to acute rejection in patients treated with interferon and/or weaned from immunosuppression might provide valuable insights into the relationship between these 2 processes as well as liver allograft acceptance.

Liver biopsy

Fibrosis, the excess deposition of extracellular matrix in the liver is a form of anatomical damage to the liver parenchyma, so that liver biopsy is the only approach for its direct assessment. Although liver biopsy has its limitations, appropriate precautions can reduce the flaws inherent in this method. The level of accuracy obtained with biopsy is particularly important for obtaining a starting point in patients with chronic liver disease who are to be followed-up over a number of years. Therefore, liver biopsy has been used as the gold standard to establish algorithm combinations of biological tests. As well as an accurate assessment of the extent of liver fibrosis, the biopsy can reveal other informations and associated features relevant to evaluation of the fibrotic process.

Molecular and cellular aspects of hepatitis C virus reinfection after liver transplantation: how the early phase impacts on outcomes

Hepatitis C virus (HCV)-related liver disease postliver transplantation is associated with an accelerated course in comparison with that observed in the nonimmunosuppressed individual. Outcomes in transplantation for this indication have, therefore, been a major area of clinical interest in the field of liver transplantation. The factors underlying the rapid progression of HCV-related liver disease posttransplantation are complex and multifactorial. Nevertheless, recent data indicate a range of parameters assessable early posttransplantation that may be useful in the prediction of outcome of transplantation for this condition. This overview, therefore, concentrates on the early events occurring postliver transplantation in the HCV-infected patient, and the implications of these recent observations for the pathogenesis of the various forms of HCV-related allograft injury.

Inverse association between hepatic stellate cell apoptosis and fibrosis in chronic hepatitis C virus infection

Perisinusoidal hepatic stellate cells (HSC) are the principal fibrogenic cells in the liver. In animal models, HSC apoptosis is the predominant clearance mechanism of activated HSC, although data evaluating whether the same processes occur in humans are limited. We conducted a cross-sectional study to evaluate the association between HSC apoptosis and fibrosis stage in subjects with chronic hepatitis C virus (HCV) infection (n = 44) and HCV-negative controls with normal liver histology (n = 9). We used immunohistochemical techniques to identify activated (alpha-smooth muscle actin+), proliferative (Ki-67+) and apoptotic (terminal deoxynucleotidyl transferase [TdT]-mediated dUTP nick end-labelling+) HSC in liver biopsy specimens from all subjects. The same pathologist enumerated positive cells per high-power field (HPF, x 200) in 20 periportal/lobular areas. HSC apoptosis was decreased in HCV-positive subjects compared with controls (median 0.4, range 0.0-3.1 vs 1.1, 0.2-3.5 cells/HPF, P = 0.02). Among HCV-positive subjects, HSC apoptosis was decreased in those with moderate to advanced fibrosis (P = 0.04) compared with those with mild fibrosis. By multivariate analysis, HSC apoptosis decreased by an average of 0.14 cells/HPF (95% confidence interval 0.01-0.28 cells/HPF) per increase in fibrosis stage (P = 0.04). While the number of activated and proliferative HSC was significantly increased in HCV-infected subjects compared with that in uninfected controls, the numbers of these cells did not differ between HCV-infected subjects with mild vs moderate/advanced fibrosis. In conclusion, the number of apoptotic HSC was significantly decreased in HCV-infected subjects with advanced fibrosis. In chronic HCV infection, inhibition of HSC apoptosis may be one mechanism by which fibrosis progresses.

Enhanced serum concentrations of transforming growth factor-beta1 in simple fatty liver: is it really benign?

Background

Inside the spectrum of non-alcoholic fatty liver disease, simple fatty liver is generally thought of as being "non progressive", differently from non-alcoholic steatohepatitis, which increases in severity due to the presence of apoptosis/inflammation and fibrosis. The "benignity" of fatty liver is widely accepted but conceptually difficult to maintain because the mechanisms underlying this entity are the same ones that determine the more severe form.

Findings provide evidence that iron overload is associated with increased liver damage and collagen deposition. Transforming growth factor-beta1 released by hepatic stellate cells during chronic liver injury plays a critical role in liver apoptosis and fibrogenesis.

Objective

To verify whether both the forms of non-alcoholic fatty liver disease were really dissimilar, evaluating the serum profile of two key parameters, indexes of severity.

Methods

A total of 123 patients (57 females) participated, forming three groups: forty five patients with fatty liver, 42 patients with non-alcoholic steatohepatitis and 36 with chronic hepatitis C. All had a biopsy-proven diagnosis.

Measurements

Serum concentrations of transforming growth factor-beta1 and ferritin.

Results

High concentrations of transforming growth factor-beta1 were noticed in patients suffering from both fatty liver and non-alcoholic steatohepatitis, 129.1 (45.4) versus 116.8 (42.2) ng/mL, P = 0.2; they were significantly superior to those of chronic hepatitis C patients 87.5 (39.5) ng/mL, P < 0.001. Ferritin levels were on average above normal values and similar in the three groups (P = 0.9), also when adjusted for gender (P = 0.5) and age (P = 0.3).

Conclusion

No difference between serum concentrations of transforming growth factor-beta1 and ferritin in fatty liver and non-alcoholic steatohepatitis suggests that these forms share more common aspects, regarding their progression, than previously thought.

Hepatic stellate cell activation and hepatic fibrosis induced by ischemia/reperfusion injury

OBJECTIVE

Warm ischemia causes severe allograft damage in liver transplantation. However, the long-term effects of ischemia/reperfusion injury (IRI) on fibrosis have not been fully elucidated. In this study, we used a partial warm hepatic ischemia mouse model to monitor fibrosis in the ischemic liver.

MATERIALS AND METHODS

Male BALB/c mice were divided into ischemic and sham groups (n = 30/group). Via a midline laparotomy, an atraumatic clip was used to interrupt the arterial and the portal venous blood supply to the left liver lobe. After 90 minutes of partial hepatic ischemia, the clip was removed initiating hepatic reperfusion. Samples from normal, sham, and ischemic liver tissues were collected at intervals of 1, 5, 10, 15, 20, or 30 days after operation (n = 5 for each time point) for hematoxylin-eosin (H&E), Mallory's trichrome, and alpha-smooth muscle actin (alpha-SMA) immunohistochemical stains for fibrosis and activation of hepatic stellate cell (HSCs).

RESULTS

IRI caused significant HSC activation in the ischemic liver tissues. Mallory's trichrome stain demonstrated that IRI caused hepatic parenchymal fibrosis near portal tracts and central veins. With prolonged reperfusion time hepatic parenchymal fibrosis was aggravated, showing the same pattern of HSC activation. IRI also caused increased portal tract fibrosis in ischemic liver tissues, especially around biliary tracts.

CONCLUSIONS

Hepatic IRI caused HSC activation, increasing hepatic parenchymal and portal tract fibrosis in ischemic liver tissues.

Virology and pathogenesis of hepatitis C virus recurrence

1. In hepatitis C virus (HCV)-infected patients undergoing liver transplantation (LT), the virus infects the liver graft immediately after transplantation. The main source of HCV infection is circulating virions. Nevertheless, some data suggest that HCV present in extrahepatic compartments may contribute to HCV infection in some cases of hepatitis C recurrence. 2. Studies on early kinetics have shown that HCV replication starts a few hours after transplantation and that HCV-RNA concentrations increase a few hours or days after the procedure, suggesting that HCV has an enormous ability to adapt to the new environment. 3. The quasispecies population may change significantly after transplantation, most likely because of the need to adapt to a new environment. There are no conclusive data supporting the role of HCV quasispecies composition and disease outcomes. 4. Persistence of HCV infection is the rule after transplantation. This is due to immunosuppression and to the immune exhaustion of the previously exposed immune system. 5. In general, HCV is not thought to be directly cytopathic. Thus, it is believed that the immune response against HCV causes liver damage. However, understanding the mechanisms of liver damage in HCV-infected LT recipients is extremely complex because of the existence of a human leukocyte antigen-mismatched organ, the preexisting virus-specific T cells that may be dysfunctional and/or tolerized, and the immunosuppression. 6. Despite the possible effect of immune-mediated liver damage, it is clear that strong immunosuppression is associated with severe forms of hepatitis C recurrence (cholestatic hepatitis, fibrosing cholestatic hepatitis, and accelerated fibrosis progression). Thus, in the absence of a strong anti-HCV immune response, HCV is able to directly (HCV proteins) or indirectly (cytokines) produce liver damage. 7. The activation of stellate cells and accelerated deposition of fibrosis are the final consequences of HCV infection in the graft. There are several mechanisms that may act synergistically to activate and perpetuate stellate cell activation in the setting of LT: ischemia-reperfusion damage, old donor age, HCV proteins, cholestasis, rejection, infection with other viruses (cytomegalovirus), and immune-mediated injury.

Serum fibrosis markers can predict rapid fibrosis progression after liver transplantation for hepatitis C

Although recurrent hepatitis C virus (HCV) after liver transplantation (LT) is universal, a minority of patients will develop cirrhosis within 5 years of surgery, which places them at risk for allograft failure. This retrospective study investigated whether 2 serum fibrosis markers, serum hyaluronic acid (HA) and YKL-40, could be used to predict rapid fibrosis progression (RFP) post-LT. These markers were compared with conventional laboratory tests, histological assessment, and hepatic stellate cell activity (HSCA), a key step in fibrogenesis, as assessed by immunohistochemical staining for alpha-smooth muscle actin. Serum and protocol liver biopsy samples were obtained from 46 LT recipients at means of 5 +/- 2 (biopsy 1) and 39 +/- 6 (biopsy 2) months post-LT, respectively. RFP was defined as an increase in the fibrosis score >or= 2 from biopsy 1 to biopsy 2 (a mean interval of 33 +/- 6 months). The ability of parameters at biopsy 1 to predict RFP was compared with the areas under receiver operating characteristic curves (AUROCs). Of the 46 subjects, 15 developed RFP. Serum HA and YKL-40 performed significantly better than conventional parameters and HSCA in predicting RFP post-LT for HCV at biopsy 1, with AUROCs of 0.89 and 0.92, respectively. The accuracy of serum HA >or= 90 microg/L and YKL-40 >or= 200 microg/L in predicting RFP at biopsy 1 was 80% and 96%, respectively. In conclusion, we found that elevated levels of serum HA and YKL-40 within the first 6 months after LT accurately predicted RFP. Larger studies evaluating the role of serum HA and YKL-40 in post-LT management are warranted.

Glial fibrillary acidic protein as an early marker of hepatic stellate cell activation in chronic and posttransplant recurrent hepatitis C

Activated alpha-smooth muscle actin (alpha-SMA)-positive hepatic stellate cells (HSCs) are pericytes responsible for fibrosis in chronic liver injury. The glial fibrillary acidic protein (GFAP), commonly expressed by astrocytes in the central nervous system, is expressed in vivo in the liver in a subpopulation of quiescent stellate cells. In the rat, increased GFAP expression in the acute response to injury and down-regulation in the chronic response have been observed, whereas reports concerning GFAP expression in human liver are still conflicting. We investigated the utility of GFAP compared to alpha-SMA as an immunohistochemical marker of early activated HSCs in chronic and posttransplant recurrent hepatitis C and correlated GFAP expression with vascular remodeling and fibrosis progression. With immunohistochemistry and a semiquantitative scoring system, the expression of GFAP and alpha-SMA in HSCs and the microvessel density were analyzed in biopsies from normal livers obtained from cadaveric donors [donor liver (DL); n = 21] and from livers from posttransplant hepatitis C virus recurrent hepatitis (HCV-PTR) patients (n = 19), hepatitis C virus chronic hepatitis (HCV-CH) patients, (n = 12), and hepatitis C virus cirrhosis (HCV-C) patients (n = 16). The percentage of alpha-SMA-positive HSCs was significantly higher in the HCV-PTR, HCV-CH, and HCV-C groups compared to the DL group (P < 0.01). The percentage of GFAP-positive HSCs was significantly higher in the HCV-PTR group compared to the DL, HCV-C (P < 0.01), and HCV-CH (P < 0.05) groups and in the HCV-CH group compared to the DL group (P < 0.01), inversely correlating with the extent of fibrosis and microvessel density (P < 0.01). In the HCV-PTR group, the percentage of GFAP-positive HSCs correlated with fibrosis progression (P < 0.01). In conclusion, GFAP could represent a useful marker of early activation of HSCs in HCV-CH and seems to predict fibrosis progression in HCV-PTR.

Correlation between liver fibrosis and inflammation in patients transplanted for HCV liver disease

Hepatitis C virus (HCV) re-infection after liver transplantation (LT) is characterized by an accelerated disease progression in recent years with unclear mechanisms. We evaluate the relationship between progression of liver fibrosis and histological necro-inflammation in HCV recipients, according to age of transplant. Fifty-five patients transplanted (1993-2002) for HCV liver disease, were included in the study. Recipients were retrospectively stratified in three different age of transplant, of 40 months each: group 1) from January 1993 to May 1996; group 2) from June 1996 to august 1999; group 3) from September 1999 to December 2002. Grading (necro-inflammation) and staging (fibrosis) scores were evaluated in liver biopsies at 1, 2 and 3 years from LT (Ishak classification). For all age of transplant the main factor associated with fibrosis progression, was grading score (p < 0.05). However mean staging score for each point of grading increased from 0.3 +/- 0.2 in older LT to 0.7 +/- 0.5 in newer ones (p = 0.01). In conclusion in HCV-LT patients (1) liver fibrosis is strictly associated to histological necro-inflammation; (2) the proportion of this relationship has been changing in recent years since newer LT patients, show an increased amount of fibrosis in comparison with the older ones, for similar grading score.

Hepatic stellate cells: protean, multifunctional, and enigmatic cells of the liver

The hepatic stellate cell has surprised and engaged physiologists, pathologists, and hepatologists for over 130 years, yet clear evidence of its role in hepatic injury and fibrosis only emerged following the refinement of methods for its isolation and characterization. The paradigm in liver injury of activation of quiescent vitamin A-rich stellate cells into proliferative, contractile, and fibrogenic myofibroblasts has launched an era of astonishing progress in understanding the mechanistic basis of hepatic fibrosis progression and regression. But this simple paradigm has now yielded to a remarkably broad appreciation of the cell's functions not only in liver injury, but also in hepatic development, regeneration, xenobiotic responses, intermediary metabolism, and immunoregulation. Among the most exciting prospects is that stellate cells are essential for hepatic progenitor cell amplification and differentiation. Equally intriguing is the remarkable plasticity of stellate cells, not only in their variable intermediate filament phenotype, but also in their functions. Stellate cells can be viewed as the nexus in a complex sinusoidal milieu that requires tightly regulated autocrine and paracrine cross-talk, rapid responses to evolving extracellular matrix content, and exquisite responsiveness to the metabolic needs imposed by liver growth and repair. Moreover, roles vital to systemic homeostasis include their storage and mobilization of retinoids, their emerging capacity for antigen presentation and induction of tolerance, as well as their emerging relationship to bone marrow-derived cells. As interest in this cell type intensifies, more surprises and mysteries are sure to unfold that will ultimately benefit our understanding of liver physiology and the diagnosis and treatment of liver disease.

Hepatic stellate cells and liver fibrosis

Substantial evidence now exists to recognize hepatic stellate cells (HSCs) as the main matrix-producing cells in the process of liver fibrosis. Liver injury of any etiology will ultimately lead to activation of HSCs, which undergo transdifferentiation to fibrogenic myofibroblast-like cells. Quantitative analysis of HSC activation by immunohistochemistry has been shown to be useful in predicting the rate of progression of liver fibrosis in some clinical situations. In the activation process, transforming growth factor beta is thought to be the main mediator of fibrogenesis and platelet-derived growth factor is the major inducer of HSC proliferation. Different platelet-derived growth factor and transforming growth factor beta inhibitors have been shown to effectively prevent liver fibrosis in animal models and represent promising therapeutic agents for humans.

Risk factors for hepatitis C recurrence after liver transplantation

Hepatitis C virus (HCV)-related end-stage liver disease is the main indication for liver transplantation performed in Europe and the United States. Recurrence of hepatitis C in the graft is universal and may lead to chronic hepatitis in most patients and to cirrhosis in 20-30% of patients within 5-10 years of transplantation. The natural history of HCV recurrence is highly variable but leads to a lower survival rate than other recurrent liver diseases. The immunosuppressed status and several other factors have been linked with the pattern and severity of recurrence. What remains controversial are those factors associated with fibrosis progression and how these could be modified to improve outcome of recurrent hepatitis C. No single factor but a combination of several factors is associated with fibrosis progression on the graft. The major factors associated with accelerated disease recurrence include: high viral load pre- (>10(6) IU / mL) and / or early post-transplantation (>10(7) IU / mL at 4 months), donor older than 40-50 years, prolonged ischaemic time, cytomegalovirus coinfection, over immunosuppression and / or abrupt changes in immunosuppression, HIV coinfection, infection by genotype 1b. Cautious follow-up of the pathology of the graft is mandatory including routine biopsies and / or noninvasive monitoring of fibrosis.

Recurrent viral liver disease (hepatitis B and C) after liver transplantation

Hepatitis C represents more than 35% of liver transplant candidates worldwide. Meanwhile, hepatitis B continues to be an important cause of end-stage liver disease and hepatocellular carcinoma in Asia and Africa. Recurrent viral liver disease is a significant event after liver transplantation and continues to be one of the main causes of graft dysfunction and loss in the middle and long-term follow-up. Mechanisms of liver reinfection and disease recurrence vary between these two viruses and pre-emptive as well as the therapeutic approaches are different. Hepatitis B patients can be managed with immune globulin immediately after liver transplant and various agents such as nucleotide and nucleoside analogues can be associated. As a result, disease recurrence has been delayed or prevented in these patients. Individuals transplanted for hepatitis C are known to have universal reinfection and a high rate of disease recurrence has been reported in the literature. Strategies to treat hepatitis C recurrence are limited to the use of pegylated interferon and ribavirin when disease is demonstrated histologically and biochemically, although other strategies have been described with limited or no success. We herein review the mechanisms of disease recurrence and the current as well as the future therapeutic approaches to prevent and to treat these diseases.

Hepatic stellate cell activation in liver transplant patients with hepatitis C recurrence and in non-transplanted patients with chronic hepatitis C

The pathogenic mechanisms of accelerated graft fibrosis in hepatitis C recurrence after liver transplantation (LT) are not well established. The aim of the study was to assess whether a greater activation of hepatic stellate cells (HSC), the major collagen-producing cells in the liver, can occur in these patients as compared to non-LT patients with chronic hepatitis C. We determined the amount of activated HSC by computer-based morphometric analysis of alpha-smooth muscle actin (alphaSMA)-positive cells and the hepatic TGFbeta(1) expression by immunohistochemistry in 46 LT patients with hepatitis C recurrence, 35 non-LT patients with chronic hepatitis C, and 16 controls. Hepatic alphaSMA and TGFbeta(1) expression was higher in LT patients with hepatitis C recurrence than in controls and was correlated with fibrosis stage and progression rate. No significant difference in alphaSMA and TGFbeta(1) expression was observed between LT and non-LT patients with hepatitis C, with the exception of a higher transforming growth factor beta-1 (TGFbeta(1)) expression in non-LT patients in the early stages of fibrosis. LT patients receiving cyclosporine (CsA) or tacrolimus (FK) had a similar fibrosis progression rate and alphaSMA and TGFbeta(1) expression. In conclusion, the accelerated fibrosis observed in LT patients with hepatitis C recurrence does not seem to be related to a greater amount of activated HSC and TGFbeta(1) expression in the grafts of these patients as compared to non-LT patients with chronic hepatitis C. In LT patients, the amount of activated HSC and TGFbeta(1) expression correlated with fibrosis stage and progression, without any apparent influence of the type of calcineurin inhibitor administered.

Management of hepatitis C virus in the transplant patient

Hepatitis C virus (HCV) is a leading cause of chronic hepatitis, with 170 to 190 million people infected worldwide. The treatment of choice for patients who have HCV-related cirrhosis with or without hepatocellular carcinoma is liver transplantation. Virologic recurrence is constant after transplantation and results in chronic hepatitis in the vast majority. HCV infection now can be cured in a substantial proportion of liver transplant recipients. This review highlights the available strategies to improve outcome, including modification of factors that affect disease progression and the efficacy of antiviral therapy.

Early histologic changes in fibrosing cholestatic hepatitis C

Recurrent hepatitis C (RHCV) after liver transplantation is almost universal, and occasional patients will have an aggressive course characterized histologically by pericellular/sinusoidal fibrosis and cholestasis, known as fibrosing cholestatic hepatitis (FCH). The early stages and evolution of this disease have not been well characterized. A total of 77 liver biopsies performed for indication (nonprotocol) were evaluated for necroinflammation, rejection, cholestasis, and fibrosis. Control groups were composed of protocol biopsies from HCV transplant patients (10 biopsies) as well as non-HCV transplant patients (6 biopsies). Scoring for necroinflammation, rejection, and fibrosis were compiled using standard criteria (hepatic activity index, Banff, Ishak, METAVIR). Pericellular fibrosis was staged with a novel "sinusoidal" system. A cholestasis scoring system was developed to quantitate parenchymal and portal features of cholestasis. Biopsies were categorized as rejection, RHCV, FCH, and stable based on histology and clinical information. FCH was found to have a higher fibrosis stage overall when compared to most diagnostic groups, regardless of the staging system used. Additionally, sinusoidal fibrosis was significantly higher in the FCH diagnosis group. Cholestasis was more prominent in biopsies of FCH in all comparisons. In conclusion, the presence of cholestasis and fibrosis with mild to moderate RHCV should raise the suspicion of FCH. When studying the evolution of these cases, the first abnormality to appear is RHCV and cholestasis, fibrosis develops soon after, and both continue to worsen until the point of allograft failure or patient death.

Early Antiviral Treatment of Hepatitis C Virus Recurrence after Liver Transplantation in HIV-Infected Patients

Objective

To investigate the efficacy of early antiviral treatment for hepatitis C virus (HCV) recurrence in HIV/HCV-coinfected patients undergoing liver transplantation for end-stage liver disease.

Methods

Open prospective trial of early treatment of HCV recurrence in consecutive HIV/HCV-coinfected patients transplanted at a tertiary hospital in Barcelona between 2002 and 2004. All patients had indication for liver transplantation, no previous CDC class C HIV-associated opportunistic events, a CD4+ T-cell count >100 cells/fxl, and undetectable plasma HIV RNA on highly active antiretroviral therapy. Treatment with pegylated interferon-a2b (1.5 μg/kg/week) and ribavirin (800–1000 mg/day) was given for 24 to 48 weeks, as soon as HCV recurrence was histologically documented.

Results

Of six patients who underwent transplant, five patients surviving the early post-transplantation period developed HCV recurrence, presenting as severe cholestatic hepatitis in three, and were started on antiviral treatment a median of 12 weeks (range: 5–31) after transplantation. After a median follow-up of 24 months all treated patients were alive. Biochemical response was achieved in all patients, although only one achieved a sustained virological response. Mild rejection before HCV recurrence occurred in two cases. Treatment was well tolerated with no episodes of rejection or mitochondrial toxicity. No patient required modification of the antiretroviral regimen. Liver biopsies performed in patients without virological response, 12–34 months after transplantation, showed cirrhosis in two and moderate chronic active hepatitis in the remainder.

Conclusions

Despite early antiviral treatment, severe HCV recurrence after liver transplantation may compromise long-term survival in HIV-infected patients. Improved treatment strategies for these patients are urgently required.

Thalidomide in Rat Liver Cirrhosis: Blockade of Tumor Necrosis Factor-α via Inhibition of Degradation of an Inhibitor of Nuclear Factor-κB

BACKGROUND/AIMS

Thalidomide inhibited tumor necrosis factor-alpha (TNF-alpha) effectively in many trials. The aim of this study was to investigate the effect of thalidomide on the expression of nuclear factor-kappaB (NF-kappaB), inhibitor of NF-kappaB (IkappaB) and TNF-alpha in a rat model of liver cirrhosis.

METHODS

Liver cirrhosis was achieved by intraperitoneal injection of carbon tetrachloride thrice weekly, and thalidomide (10 or 100 mg/kg/day) was given daily by intragastric route for 8 weeks. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), prealbumin (PA), hyaluronic acid (HA) and laminin (LN), and hydroxyproline (HYP), NF-kappaBp65, alpha-smooth muscle actin (alpha-SMA) protein and TNF-alpha mRNA were studied in the liver, IkappaBalpha and TNF-alpha protein in the cytoplasm and NF-kappaBp65 protein in the nucleus.

RESULTS

Compared with nontreated cirrhotic rats, the histopathology of rats given thalidomide (100 mg/kg) was significantly better. Serum ALT, AST, HA and LN and HYP content in the liver were significantly decreased and PA was elevated (p < 0.01) in this group; the expression of TNF-alpha mRNA and protein, NF-kappaBp65 and alpha-SMA were significantly decreased and IkappaBalpha protein was also elevated (p < 0.01).

CONCLUSION

Thalidomide downregulates NF-kappaB-induced TNF-alpha and activates hepatic stellate cells (HSC) via inhibition of IkappaB degradation to prevent liver cirrhosis.

Hepatobiliary pathology

PURPOSE OF REVIEW

Publications concerning liver histopathology in fatty liver disease and chronic hepatitis C, iron and copper overload, and liver transplantation from the past year have been surveyed to highlight useful concepts and diagnostic information.

RECENT FINDINGS

Two microscopic forms of pediatric nonalcoholic steatohepatitis have been described: type 1 in which hepatocyte ballooning and/or pericellular fibrosis accompany the steatosis; and type 2 which has portal tract inflammation and/or fibrosis as the salient accompanying feature. In chronic hepatitis C, the ductular reaction appears to be a major factor associated with fibrosis. In patients transplanted for hepatitis C virus-related cirrhosis, immunostaining of post-transplant liver biopsies for alpha-smooth muscle actin (i.e. in activated hepatic stellate cells) may identify those individuals at risk for severe recurrence. Clinicopathological papers on several forms of non-HFE hemochromatosis were published and Wilson's disease was described in individuals of 60 years or more in age. Cholestasis in childhood was expertly reviewed and histopathologic precursor lesions of hepatocellular carcinoma were also examined in a comprehensive article.

SUMMARY

Recent publications with impact on liver biopsy interpretation include a morphologic classification of nonalcoholic steatohepatitis in childhood, the differential diagnosis of childhood cholestasis and pathogenetic factors involved in fibrogenesis in chronic hepatitis C.