Potential role of hepatic progenitor cells expression in cases of chronic hepatitis C and their relation to response to therapy: a clinicopathologic study

The role of hepatic progenitor cells in predicting response to therapy in Egyptian patients with chronic hepatitis C, genotype 4

Background

Interferon therapy is used as a line of treatment of chronic hepatitis C virus (HCV) in several areas of the world including Egypt.

Objective

Our aim was to investigate the value of hepatic progenitor cells (HPCs) in predicting response of patients with chronic HCV, genotype 4 to pegylated interferon (PEGIFN) plus ribavirin (RBV) therapy.

Methods

Pre-treatment liver biopsies obtained from 110 patients with chronic HCV, genotype 4 were examined immunohistochemically for HPCs using cytokeratin19. The mean number of HPCs as ductular reaction (DR) and as isolated progenitor cells (IPCs) was counted in each case. The patients were classified into: those with sustained virological response (SVR) and those who did not achieve SVR. The results were compared between the two groups. Also, the relationships between HPCs and other clinico-pathologic variables were estimated using multivariate analysis.

Results

The mean number of HPCs was the only independent predictor of therapeutic response, being significantly higher in non-responders (P = 0 for DR and P = 0.03 for IPCs). On the other hand, fibrosis stage and steatosis were the only independent factors which showed a significant direct association with the mean number of HPCs in the form of DR and IPCs (P = 0 for each).

Conclusion

The number of HPCs provides prognostic information in chronic HCV since it is significantly associated with stage of fibrosis. More importantly, it can be used as a marker to predict response of patients with chronic HCV to PEGIFN plus RBV therapy.

Expression of hepatic progenitor cell markers in acute cellular rejection of liver allografts-An immunohistochemical study

BACKGROUND

Hepatic progenitor cells (HPC) are induced following liver injury to facilitate regeneration. Acute cellular rejection (ACR) is a common complication after liver transplantation as a result of immune-mediated liver injury. In this study, we characterized HPC phenotype in liver allograft biopsy with ACR. We also explored the correlation between expression HPC immunophenotype and clinicopathological parameters.

METHODS

Forty-four liver allograft biopsies performed between 2008 and 2016 in a single center with histologically proven ACR were examined for immunohistochemical expression of HPC markers CK19 and Sox9. The number of positive-staining cells was assessed and correlated with clinicopathological features by statistical analysis.

RESULTS

HPC phenotype expression as denoted by CK19 and Sox9 staining was detected in the liver tissue with ACR. The numbers of CK19+ and Sox9+ cells were positively correlated. A larger number of CK19+ cells were associated with higher serum aspartate aminotransferase (AST) level at biopsy. By histological rejection score, a larger number of Sox9+ cells were associated with a higher score of bile duct damage.

CONCLUSION

Expression HPC markers were correlated with clinical and histological parameters in ACR. Expression of each individual marker may be more tightly associated with a particular component of the ACR process.

Relationship between hepatic progenitor cells and stellate cells in chronic hepatitis C genotype 4

Hepatitis C virus (HCV) infection represents a major health problem in many areas of the world, especially Egypt. Hepatic progenitor cells (HPCs) and hepatic stellate cells (HSCs) have been implicated in fibrosis progression in chronic HCV. The aim of this study was to investigate the role of HPCs and HSCs in chronic HCV infection and the relationship between both cell types. This retrospective study was conducted on 100 chronic HCV patients. Immunohistochemistry was performed on liver tissue sections for cytokeratin 19 (progenitor cell markers), smooth muscle actin (stellate cell markers), matrix metalloproteinase-9 (MMP-9), and transforming growth factor beta (TGF-ß). The necroinflammatory activity was significantly related to the number of isolated HPCs and TGF-ß expression (p = 0.003 and p = 0.001 respectively). Advanced stages of fibrosis showed significantly increase number of HPCs (p = 0.001), higher ratio of HSCs (p = 0.004), more expression of TGF-ß (p = 0.001) and MMP-9 (p = 0.001). There was a significant direct correlation between immunoexpression of HPCs and HSCs for isolated cells (r = 0.569, p = 0.001) and ductular reaction (r = 0.519, p = 0.001). Hepatic progenitor cells and stellate cells play a significant role in the development and progression of fibrosis in chronic HCV. More interestingly, the significant direct correlation between HPCs and HSCs suggests a synergistic interrelation.

Increased hepatic progenitor cell response and ductular reaction in patients with severe recurrent HCV post-liver transplantation

OBJECTIVES

Post-liver transplant (LT) hepatitis C virus (HCV) patients may develop allograft cirrhosis and rarely fibrosing cholestatic hepatitis (FCH), while others have a stable course. Hepatic progenitor cells (HPC) may be implicated in liver injury and fibrogenesis through ductular reaction (DR). We studied HPC response and DR in three distinct post-LT patterns of HCV: stable recurrence, allograft cirrhosis, and FCH.

METHODS

We identified 52 patients with untreated recurrent HCV and longitudinal liver biopsies (20 stable/23 cirrhosis/9 FCH) and eight healthy controls. Archived liver biopsy specimens for three time points (LT; initial recurrence; and clinical outcome) were stained for cytokeratin-7. Manual HPC counts and DR quantification using image analysis were performed.

RESULTS

HCV counts and DR at LT did not differ across groups. At initial recurrence, HPC expansion occurred only in patients who developed cirrhosis, while prominent DR was present in those who developed FCH vs. stable and controls (p < 0.05). At outcome biopsies, HPC response and DR were increased in cirrhosis and FCH vs. stable and controls (p < 0.05). HPC response and DR did not differ in stable vs.

CONCLUSIONS

These findings suggest that an altered HPC response assessed by cytokeratin-7 stain after LT may predict severity of HCV recurrence.

Integrative role of vitamin D related and Interleukin-28B genes polymorphism in predicting treatment outcomes of Chronic Hepatitis C

BACKGROUND

Improving prediction of treatment outcomes in chronic hepatitis C (CHC) genotype 4 (G4) is necessary to increase sustained viral response (SVR) rates. Vitamin D related and interferon stimulated genes are good candidates as they are recently crosstalk altering interferon response. Thus single nucleotide polymorphisms (SNPs) within some of these genes and multiple stepwise regression analysis including other independent predictors (IL28B(rs12979860), serum 25OH-vitamin D, serum alfa-fetoprotein (AFP)) were performed on a cohort of 200 Egyptian CHC patients treated with Pegylated interferon-alpha (Peg-IFN) plus ribavirin.

METHODS

SNPs in cytochrome P-450 (CYP2R1)(rs10741657AG), vitamin D receptor (VDR)(rs2228570AG, rs1544410CT), oligoadenylate synthetases-like (OASL)(rs1169279CT) and adenosine deaminases acting on RNA (ADAR)(rs1127309TC) genes were analyzed by real-time PCR.

RESULTS

The carrier state of A allele in VDR rs2228570 and CYP2R1 rs10741657 genes were independently associated with SVR [OR 6.453 & 3.536, p < 0.01 respectively]. Combining carriers of A allele in CYP2R1 and VDR genes with IL28B C/C genotype increased the probability of SVR from 80 % to reach 87.8 %, 93 % and 100 %. No relation was found between VDR rs1544410CT, ADAR rs1127309TC, OASL rs1169279CT polymorphisms and treatment outcome. Combining VDR rs2228570 A/A genotype with IL28B C/C genotype increased the probability of SVR from 82 % to reach 100 % and from 29 % to reach 80 % in C/T+ T/T IL28B genotype in none F4 liver disease patients.

CONCLUSION

Vitamin D related (VDR rs2228570 and CYP2R1 rs10741657) and IL28B rs12979860 genes polymorphisms accurately assure SVR in naïve CHC G4 patients treated with low cost standard therapy.

Hepatic progenitor cells in children with chronic hepatitis C: correlation with histopathology, viremia, and treatment response

OBJECTIVE

Hepatic progenitor cells (HPCs) are bipotential stem cells that can differentiate towards the hepatocytic and cholangiocytic lineages. Many studies have investigated HPCs in adults with hepatitis C virus infection; however, none has been carried out in the pediatric population. Therefore, this work aimed to investigate HPCs expansion in children with chronic hepatitis C (CHC) and its correlation with histopathology, viremia, and treatment response.

PATIENTS AND METHODS

Eighty children with CHC, 73 of whom received interferon-based therapy, were recruited. Sections of their liver biopsies were prepared for immunostaining of HPCs using cytokeratin-7 antibody.

RESULTS

HPCs were expanded in most children (81.3%) with CHC. Expansion occurred in two forms: intraparenchymal isolated hepatic progenitor cell form and periportal ductular reaction form. There was a significant increase in HPCs expansion in higher stages of fibrosis (50, 81.8, and 100% in no, mild, and moderate fibrosis, respectively, with P=0.029). Also, HPCs expansion increased with increased grade of necroinflammatory activity (0, 77.8, 81.8, and 100%, in no, minimal, mild, and moderate activity, respectively), although this was statistically insignificant. Moreover, a significant positive correlation was found between the isolated hepatic progenitor cell number and ductular reaction grade (r=0.755, P<0.0001), and both were significantly correlated with the level of viremia and the grade of necroinflammatory activity. Finally, HPCs expansion was not related to the treatment response.

CONCLUSION

The relationship of HPCs with both the severity of hepatitis and the stage of fibrosis may be because of a role of HPCs in their pathogenesis.

Hepatic fibrosis and serum alpha-fetoprotein (AFP) as predictors of response to HCV treatment and factors associated with serum AFP normalisation after treatment

BACKGROUND AND STUDY AIM

Elevated levels of alpha-fetoprotein (AFP) can be seen in patients with chronic hepatitis C (CHC) and liver cirrhosis without hepatocellular carcinoma and were negatively associated with treatment response. However, factors associated with its changes are not identified. We aimed in this study to verify a cut-off value for AFP as a predictor of response to standard of care (SOC) antiviral therapy in Egyptian chronic hepatitis C virus (HCV)-infected patients and identify factors associated with its changes post treatment.

PATIENTS AND METHODS

A total of 175 chronic non-cirrhotic HCV-infected patients were evaluated for baseline serum AFP and liver biopsy were classified according to Ishak scoring system of hepatic fibrosis. All patients were scheduled to receive SOC antiviral therapy for 48weeks and had been followed up to week 72. Reassessment of AFP and repeated liver biopsy at week 72 were feasible only in 79 patients.

RESULTS

High baseline AFP levels were observed in non-respondents (non-sustained virological respondents (non-SVRs)) (P<0.01); the AFP level decreased in all patients post treatment (P=0.01), especially in the SVRs (P<0.01). In multivariate analysis, hepatic fibrosis was a predictor of response to treatment (P=0.02), while body mass index (BMI) (25-30kgm(-2)), hepatic activity (A2), hepatic fibrosis stage (F2-F4) and fibrosis improvement were predictors of AFP difference (P=0.007, 0.01, 0.012, <0.001, 0.030, and 0.018), respectively. The diagnostic performance to predict the HCV treatment response was best by adding both AFP and hepatic fibrosis stage factors; the best cut-off value for AFP was 3.57ngdl(-1) with 50% sensitivity and 68% specificity with area under the curve (AUC) of 0.55 and for hepatic fibrosis stage was 3, with a sensitivity of 88%, a specificity of 30% with an AUC of 0.58.

CONCLUSION

In chronic HCV-infected patients, serum AFP below 3.57ngdl(-1) and hepatic fibrosis ⩽stage 3 are expected to have good response to treatment; BMI (25-30kgm(-1)), A2, fibrosis >2 and fibrosis improvement predict AFP change post treatment.

A morphometric and immunohistochemical study to assess the benefit of a sustained virological response in hepatitis C virus patients with cirrhosis

Although annular fibrosis is the hallmark of cirrhosis, other microscopic changes that affect liver function such as sinusoid capillarization or loss of metabolic zonation are common. A sustained virological response (SVR) may halt fibrosis deposition in hepatitis C virus (HCV)-infected patients, but its impact on the other cirrhosis-associated lesions is unknown. The aim of this study was to assess the impact of an SVR on cirrhosis-related histopathological features. Paired pre- and posttreatment liver biopsies from 38 HCV patients with cirrhosis with an SVR were analyzed. Fibrosis was staged using the METAVIR scoring system, and the area of fibrosis was measured using morphometry. Ductular proliferation, metabolic zonation, sinusoid capillarization, and hepatic stellate cell activation were assessed by anti-cytokeratin-7, anti-glutamine synthetase (GS), anti-cytochrome P4502E1 (CYP2E1), anti-CD34, and anti α-smooth muscle actin (αSMA). After 61 months from an SVR, cirrhosis regression was observed in 61%, and the collagen content decreased in 89%. Although periportal and lobular necroinflammation vanished, portal inflammation persisted in 66%. Ductular proliferation decreased in 92%. Before treatment, metabolic zonation was lost, as shown by GS and CYP2E1, in 71% and 88%, respectively, with normalization in 79% and 73%, after an SVR. Conversely, no changes in sinusoidal capillarization were observed after treatment, as assessed by CD34 (P = 0.41) and αSMA (P = 0.95). Finally, no differences in all the immunohistochemical scores emerged whether or not cirrhosis persisted.

CONCLUSION

Cirrhosis regression and decreased fibrosis are frequently observed among HCV patients with cirrhosis with an SVR. Despite ductular proliferation vanishing and lobular zonation restoration, portal inflammation and sinusoidal capillarization may not regress after viral eradication.

Increased α-Fetoprotein Predicts Steatosis among Patients with Chronic Hepatitis C Genotype 4

Background. The prognostic importance of α-fetoprotein (AFP) level elevation in patients with chronic hepatitis C and its clinical significance in steatosis associated with HCV infection remain to be determined. The present paper assessed clinical significance of elevated AFP in patients with CHC with and without steatosis. Methods. One hundred patients with CHC were divided into 50 patients with CHC and steatosis and 50 patients with CHC and no steatosis based on liver biopsy. Results. AFP was significantly increased in CHC with steatosis than patients without steatosis (P < 0.001). Highly significant positive correlation was found between serum AFP and necroinflammation as well as the severity of fibrosis/cirrhosis and negative significant correlation with albumin level in chronic HCV with steatosis (P < 0.001) but negative nonsignificant correlation with ALT and AST level (P ≤ 0.778 and 0.398), respectively. Highly significant increase was found in chronic hepatitis patients with steatosis than CHC without steatosis regarding necroinflammation as well as the severity of fibrosis/cirrhosis and AFP (P < 0.001). Conclusion. Patients with chronic HCV and steatosis have a higher AFP levels than those without steatosis. In chronic HCV with steatosis, elevated AFP levels correlated positively with HAI and negative significant correlation with albumin level.

Stimulation of oval cell and hepatocyte proliferation by exogenous bombesin and neurotensin in partially hepatectomized rats

AIM: To investigate the effect of the neuropeptides bombesin (BBS) and neurotensin (NT) on oval cell proliferation in partially hepatectomized rats not pretreated with a known hepatocyte inhibitor.

METHODS: Seventy male Wistar rats were randomly divided into five groups: I = controls, II = sham operated, III = partial hepatectomy 70% (PHx), IV = PHx + BBS (30 μg/kg per day), V = PHx + NT (300 μg/kg per day). Forty eight hours after liver resection, portal endotoxin levels and hepatic glutathione redox state were determined. α-fetoprotein (AFP) mRNA (in situ hybridisation), cytokeratin-19 and Ki67 antigen expression (immunohistochemistry) and apoptosis (TUNEL) were evaluated on liver tissue samples. Cells with morphological features of oval cells that were cytokeratin-19 (+) and AFP mRNA (+) were scored in morphometric analysis and their proliferation was recorded. In addition, the proliferation and apoptotic rates of hepatocytes were determined.

RESULTS: In the control and sham operated groups, oval cells were significantly less compared to groups III, IV and V (P < 0.001). The neuropeptides BBS and NT significantly increased the proliferation of oval cells compared to group III (P < 0.001). In addition, BBS and NT induced a significant increase of hepatocyte proliferation (P < 0.001), whereas it decreased their apoptotic activity (P < 0.001) compared to group III. BBS and NT significantly decreased portal endotoxemia (P < 0.001) and increased the hepatic GSH: GSSG ratio (P < 0.05 and P < 0.001, respectively) compared to group III.

CONCLUSION: BBS and NT stimulated oval cell proliferation in a model of liver regeneration, without use of concomitant suppression of hepatocyte proliferation as oval cell activation stimuli, and improved the hepatocyte regenerative response. This peptides-induced combined stimulation of oval cell and hepatocyte proliferation might serve as a possible treatment modality for several liver diseases.

Hepatitis C virus-induced cancer stem cell-like signatures in cell culture and murine tumor xenografts

Hepatitis C virus (HCV) infection is a prominent risk factor for the development of hepatocellular carcinoma (HCC). Similar to most solid tumors, HCCs are believed to contain poorly differentiated cancer stem cell-like cells (CSCs) that initiate tumorigenesis and confer resistance to chemotherapy. In these studies, we demonstrate that the expression of an HCV subgenomic replicon in cultured cells results in the acquisition of CSC traits. These traits include enhanced expression of doublecortin and CaM kinase-like-1 (DCAMKL-1), Lgr5, CD133, α-fetoprotein, cytokeratin-19 (CK19), Lin28, and c-Myc. Conversely, curing of the replicon from these cells results in diminished expression of these factors. The putative stem cell marker DCAMKL-1 is also elevated in response to the overexpression of a cassette of pluripotency factors. The DCAMKL-1-positive cells isolated from hepatoma cell lines by fluorescence-activated cell sorting (FACS) form spheroids in Matrigel. The HCV RNA abundance and NS5B levels are significantly reduced by the small interfering RNA (siRNA)-led depletion of DCAMKL-1. We further demonstrate that HCV replicon-expressing cells initiate distinct tumor phenotypes compared to the tumors initiated by parent cells lacking the replicon. This HCV-induced phenotype is characterized by high-level expression/coexpression of DCAMKL-1, CK19, α-fetoprotein, and active c-Src. The results obtained by the analysis of liver tissues from HCV-positive patients and liver tissue microarrays reiterate these observations. In conclusion, chronic HCV infection appears to predispose cells toward the path of acquiring cancer stem cell-like traits by inducing DCAMKL-1 and hepatic progenitor and stem cell-related factors. DCAMKL-1 also represents a novel cellular target for combating HCV-induced hepatocarcinogenesis.

Dendritic cells in hepatitis C infection: can they (help) win the battle?

Infection with hepatitis C virus (HCV) is a public health problem; it establishes a chronic course in ~85% of infected patients and increases their risk for developing liver cirrhosis, hepatocellular carcinoma, and significant extrahepatic manifestations. The mechanisms of HCV persistence remain elusive and are largely related to inefficient clearance of the virus by the host immune system. Dendritic cells (DCs) are the most efficient inducers of immune responses; they are capable of triggering productive immunity and maintaining the state of tolerance to self- and non-self antigens. During the past decade, multiple research groups have focused on DCs, in hopes of unraveling an HCV-specific DC signature or DC-dependent mechanisms of antiviral immunity which would lead to a successful HCV elimination strategy. This review incorporates the latest update in the current status of knowledge on the role of DCs in anti-HCV immunity as it relates to several challenging questions: (a) the phenotype and function of diverse DC subsets in HCV-infected patients; (b) the characteristics of non-human HCV infection models from the DCs' point of view; (c) how can in vitro systems, ranging from HCV protein- or peptide-exposed DC to HCV protein-expressing DCs, and in vivo systems, ranging from HCV protein-expressing transgenic mice to HCV-infected non-human primates, be employed to dissect the role of DCs in triggering/maintaining a robust antiviral response; and (d) the prospect of DC-based strategy for managing and finding a cure for HCV infection.

Bombesin and neurotensin exert antiproliferative effects on oval cells and augment the regenerative response of the cholestatic rat liver

The regenerative capacity of the cholestatic liver is significantly attenuated. Oval cells are hepatic stem cells involved in liver's regeneration following diverse types of injury. The present study investigated the effect of the neuropeptides bombesin (BBS) and neurotensin (NT) on oval cell proliferation as well as on hepatocyte and cholangiocyte proliferation and apoptosis in the cholestatic rat liver. Seventy male Wistar rats were randomly divided into five groups: controls, sham operated, bile duct ligated (BDL), BDL+BBS (30 μg/kg/d), BDL+NT (300 μg/kg/d). Ten days later, alpha-fetoprotein (AFP) mRNA (in situ hybridization), cytokeratin-19 and Ki67 antigen expression (immunohistochemistry) and apoptosis (TUNEL) were evaluated on liver tissue samples. Cells with morphologic features of oval cells that were cytokeratin-19(+) and AFP mRNA(+) were scored in morphometric analysis and their proliferation was recorded. In addition, the proliferation and apoptotic rates of hepatocytes and cholangiocytes were determined. Alanine aminotransferase (ALT) levels and hepatic oxidative stress (lipid peroxidation and glutathione redox state) were also estimated. The neuropeptides BBS and NT significantly reduced ALT levels and hepatic oxidative stress. Both agents exerted similar and cell type-specific effects on oval cells, hepatocytes and cholangiocytes: (a) oval cell proliferation and accumulation in the cholestatic liver was attenuated, (b) hepatocyte proliferation was increased along with a decreased rate of their apoptosis and (c) cholangiocyte proliferation was attenuated and their apoptosis was increased. These observations might be of potential value in patients with extrahepatic cholestasis.

Hepatocyte transplantation and the differentiation fate of host oval cells in acute severe hepatic injury

Oval cells and hepatocytes rarely proliferate simultaneously. This study aimed to determine the impacts of hepatocyte transplantation on the response and fate of oval cells that are activated to proliferate in acute severe hepatic injury. Retrorsine + D-galactosamine (R+D-gal) treatment was used to induce acute hepatic injury and to elicit extensive activation of oval cells in male dipeptidyl peptidase IV-deficient F344 rats. These rats were then randomized to receive wild-type hepatocyte transplantation or vehicle intraportally. The kinetics of oval cell response and their differentiation fate were analyzed. Results showed that oval cells were activated early and differentiated into hepatocytes in R+D-gal-treated rats without hepatocyte transplantation. With hepatocyte transplantation, the oval cells were recruited later and continued to proliferate in parallel with the massive proliferation of transplanted hepatocytes. They formed ductules and differentiated into biliary cells. When hepatocytes were transplanted at the day when oval cells were at their peak response, the numerous activated oval cells ceased to differentiate into hepatocytes and remained in ductular form. The ductular oval cells were capable of differentiating into hepatocytes again when the donor hepatocytes were inhibited to proliferate. We conclude that hepatocyte transplantation changes the mechanism of liver reconstitution and affects the differentiation fate of host oval cells in acute severe hepatic injury.

Cross-species immunohistochemical investigation of the activation of the liver progenitor cell niche in different types of liver disease

BACKGROUND

When hepatocyte replication during liver disease is insufficient for regeneration, liver progenitor cells (LPCs) are activated. The cells and stroma in the immediate environment of LPCs, together termed the LPC niche, are thought to play an important role in this activation. Among these cells are the hepatic stellate cells (HSCs)/myofibroblasts (MFs).

AIMS/METHODS

We assessed the activation of HSC/MFs and LPCs in relation to the histological location and extent of liver disease in immunohistochemically (double) stained serial sections. Markers of HSC/MFs [alpha-smooth muscle actin, glial fibrillary acidic protein (GFAP), neurotrophin 3 and neural-cell adhesion molecule], markers of LPCs (keratin 7 and keratin 19) and a proliferation marker (Ki67) were used. A very relevant spontaneous model to evaluate LPC niche activation in a translational approach seems to be the dog. Therefore, both human and canine liver diseases with different degree of fibrosis and disease activity were included.

RESULTS

In human and canine liver disease, type and extent of LPC niche activation depended on type and severity of disease (P<0.05) and corresponded to the main location of disease. Activated HSCs surrounded the activated LPCs. In chronic hepatitis and non-alcoholic steatohepatitis lobular-type HSCs were activated, while during biliary disease portal/septal MFs were mainly activated. In canine liver, GFAP further presented as an early marker of HSC activation. Activation of the LPCs correlated with disease location and severity (P<0.01), and was inversely related to hepatocyte proliferation, as was previously shown in man.

CONCLUSION

A shared involvement of HSC/MFs, LPCs and disease severity during hepatic disease processes is shown, which is highly similar in man and dog.

Relation between liver progenitor cell expansion and extracellular matrix deposition in a CDE-induced murine model of chronic liver injury

In chronic liver injury, liver progenitor cells (LPCs) proliferate in the periportal area, migrate inside the lobule, and undergo further differentiation. This process is associated with extracellular matrix (ECM) remodeling. We analyzed LPC expansion and matrix accumulation in a choline-deficient, ethionine-supplemented (CDE) model of LPC proliferation. After day 3, CDE induced collagen deposits in the periportal area. Expansion of LPCs as assessed by increased number of cytokeratin 19 (CK19)-positive cells was first observed at day 7, while ECM accumulated 10 times more than in controls. Thereafter, LPCs and ECM increased in parallel. Furthermore, ECM not only accumulates prior to the increase in number of LPCs, but is also found in front of LPCs along the porto-venous gradient of lobular invasion. Double immunostaining revealed that LPCs are embedded in ECM at all times. Moreover, LPCs infiltrating the liver parenchyma are chaperoned by alpha-smooth muscle actin (alpha-SMA)-positive cells. Gene expression analyses confirmed these observations. The expression of CK19, alpha-fetoprotein, E-cadherin, and CD49f messenger RNA (mRNA), largely overexpressed by LPCs, significantly increased between day 7 and day 10. By contrast, at day 3 there was a rapid burst in the expression of components of the ECM, collagen I and laminin, as well as in alpha-SMA and connective tissue growth factor expression.

CONCLUSION

Our data demonstrate that, in a CDE model, ECM deposition and activation of matrix-producing cells occurred as an initial phase, prior to LPC expansion, and in front of LPCs along the porto-venous gradient of lobular invasion. Those observations may reveal a fundamental role for the established hepatic microenvironment or niche during the process of activation and differentiation of liver progenitor cells.

Serum alpha-fetoprotein predicts virologic response to hepatitis C treatment in HIV coinfected patients

We explored the link between serum alpha-fetoprotein levels and virologic response in 383 HIV-hepatitis C virus coinfected patients. A low alpha-fetoprotein level (<5.0 ng/ml) was an independent predictor of sustained virologic response (odds ratio = 1.83; 95% confidence interval 1.05-3.20). Serum alpha-fetoprotein measurement should be integrated in the pretreatment assessment of prognostic factors of a virologic response.

Serum alpha-fetoprotein predicts treatment outcome in chronic hepatitis C patients regardless of HCV genotype

We examined the association between serum alpha-fetoprotein (AFP) level and sustained virological response (SVR) in 93 chronic hepatitis C patients. The SVR rate was much higher among patients with serum AFP levels below rather than above the median value (5.7 ng/ml) (58.7% and 19.2%, respectively; P<0.0001). Serum AFP should be added to the list of factors predictive of treatment response in chronic hepatitis C.

Activation of stem cells in hepatic diseases

The liver has enormous regenerative capacity. Following acute liver injury, hepatocyte division regenerates the parenchyma but, if this capacity is overwhelmed during massive or chronic liver injury, the intrinsic hepatic progenitor cells (HPCs) termed oval cells are activated. These HPCs are bipotential and can regenerate both biliary epithelia and hepatocytes. Multiple signalling pathways contribute to the complex mechanism controlling the behaviour of the HPCs. These signals are delivered primarily by the surrounding microenvironment. During liver disease, stem cells extrinsic to the liver are activated and bone-marrow-derived cells play a role in the generation of fibrosis during liver injury and its resolution. Here, we review our current understanding of the role of stem cells during liver disease and their mechanisms of activation.

Oval cell proliferation in cirrhosis in rats. An experimental study

AIM

Oval cells are liver stem cells involved in liver regeneration following liver damage. Previous studies have shown that pretreatment with a hepatocyte inhibitor is required to allow full oval cell activation. This study investigates whether oval cells develop and proliferate in a model of experimental liver fibrosis without pretreatment with a known hepatocyte inhibitor.

METHODS

The study comprised 66 male Wistar rats divided into two groups: A (n = 6): controls; and B (n = 60): CCl(4) injection (intraperitoneally 2 mL/kg bodyweight 1:1 volume in corn oil twice weekly). Rats were sacrificed at four, eight and 12 weeks. Liver tissues were evaluated for the degree of fibrosis (Masson's trichrome), cell proliferation (Ki67 antigen), expression of alpha-fetoprotein (AFP) mRNA (RT-PCR and in situ hybridization), AFP protein (Western blot) and cytokeratin-19. Cells with morphologic features of oval cells that were cytokeratin 19 (CK19)+ and AFP mRNA+ were scored in morphometric analysis.

RESULTS

Oval cells were present in all 66 specimens; their percentage was higher in group B compared to group A (P < 0.001). AFP mRNA and protein expression increased as fibrosis advanced. Similarly, the numbers of CK19+, AFP mRNA+ and Ki67+ oval cells were higher in advanced fibrosis stages.

CONCLUSION

This study demonstrates that oval cells develop and proliferate in a model of experimental liver fibrosis without pretreatment with a known hepatocytic inhibitor. However, further research is warranted in order to identify the exact molecular mechanisms involved in this process.

Hepatobiliary pathology

PURPOSE OF REVIEW

Recent papers on disorders of the liver and biliary tract which clarify their pathogenesis and attendant morphologic changes are highlighted.

RECENT FINDINGS

The concept of 'bystander hepatitis' was cited in studies showing hepatic infiltration of CD8-positive T cells in the setting of extrahepatic infections such as influenza virus and severe acute respiratory syndrome. Diabetic liver lesions include glycogenic hepatopathy (in which poor diabetic control leads to swollen, glycogen-filled hepatocytes without fat, steatohepatitis or fibrosis) and diabetic hepatosclerosis in which there is diffuse perisinusoidal fibrosis (type IV collagen) without zonal predilection. Ground-glass hepatocellular inclusions (positive with periodic acid-Schiff stain for glycogen) were reported in three separate series of patients who were hepatitis B virus-negative, often transplant recipients, immunosuppressed and on multiple medications. A Banff consensus paper expertly compared and contrasted the histologic features which characterize the various causes of late liver allograft dysfunction.

SUMMARY

Informative papers emerged this past year concerning collateral damage to the liver in extrahepatic infections, diabetic lesions and causes of liver dysfunction after transplantation, among other topics.