Effect of lamivudine treatment on plasma levels of transforming growth factor β1, tissue inhibitor of metalloproteinases-1 and metalloproteinase-1 in patients with chronic hepatitis B

Enzymes of Fibrosis in Chronic Liver Disease

Introduction: Liver fibrosis has been extensively studied at the cellular and molecular level, but very few data exist on the final enzymatic stages of collagen synthesis (prolyl hydroxylase, PH) and degradation (matrix metalloproteinases, MMPs), particularly in primary biliary cholangitis (PBC). Aim: We studied enzyme activities in liver tissue from patients with chronic liver diseases and compared them to normal livers. Patients: Eighteen patients with PBC of early and late stages (Ludwig’s classification) and seven on treatment with ursodeoxycholate (UDCA) were studied and compared to 34 patients with alcoholic liver disease (ALD), 25 patients with chronic viral liver disease and five normal biopsies. Sera were available from a total of 140 patients. Methods: The tritiated water released from the tritiated proline was measured in PH assessment. 14C intact and heat-denatured collagen substrates were used to measure collagenase and gelatinases, respectively. 3H Elastin was the substrate for elastase. In serum, ELISAs were used for MMP-1, TIMP-1, and TIMP-2 measurements while MMP-2 and MMP-9 were estimated by zymography. Results: PH was significantly increased in early and late PBC. Collagenase was reduced only in the late stages (p < 0.01), where the ratio PH/collagenase was increased. UDCA treatment restored values to almost normal. Gelatinases were reduced in late stages (p < 0.05). In contrast to PBC and ALD fibrosis, collagen synthesis is not increased in viral fibrosis. The balance shifted towards collagen deposition due to reduced degradation. Interestingly, gelatinolytic activity is not impaired in ALD. Elastase was similar to controls in all diseases studied. TIMP-1 was reduced in early PBC and viral and alcoholic hepatitis and cirrhosis (p < 0.001). Conclusions: (1) There is evidence that collagen synthesis increases in the early stages of PBC, but the collagenolytic mechanism may compensate for the increased synthesis. (2) In viral disease, fibrosis may be due to decreased degradation rather than increased synthesis. (3) The final biochemical stages of liver fibrosis may be quantitatively different according to underlying etiology.

The Role of Sinusoidal Endothelial Cells in the Axis of Inflammation and Cancer Within the Liver

Liver sinusoidal endothelial cells (LSEC) form a unique barrier between the liver sinusoids and the underlying parenchyma, and thus play a crucial role in maintaining metabolic and immune homeostasis, as well as actively contributing to disease pathophysiology. Whilst their endocytic and scavenging function is integral for nutrient exchange and clearance of waste products, their capillarisation and dysfunction precedes fibrogenesis. Furthermore, their ability to promote immune tolerance and recruit distinct immunosuppressive leukocyte subsets can allow persistence of chronic viral infections and facilitate tumour development. In this review, we present the immunological and barrier functions of LSEC, along with their role in orchestrating fibrotic processes which precede tumourigenesis. We also summarise the role of LSEC in modulating the tumour microenvironment, and promoting development of a pre-metastatic niche, which can drive formation of secondary liver tumours. Finally, we summarise closely inter-linked disease pathways which collectively perpetuate pathogenesis, highlighting LSEC as novel targets for therapeutic intervention.

Serum soluble CD40 is associated with liver injury in patients with chronic hepatitis B

Soluble cluster of differentiation 40 (sCD40) is proteolytically cleaved from membrane-bound CD40 and binds to CD154, thereby inhibiting CD40-CD154-mediated immune responses. The aim of the present study was to clarify the role of sCD40 in chronic hepatitis B (CHB). The sCD40 levels in sera from 132 patients with CHB and 33 healthy individuals were retrospectively measured. sCD40 concentrations in patients with CHB were higher than those in healthy controls, and sCD40 levels correlated positively with serum levels of the liver dysfunction biomarkers alanine transaminase (ALT) and aspartate transaminase (AST). sCD40 concentrations increased with a rise in the severity of liver necroinflammation and fibrosis. Patients with >75% liver tissue staining positive for hepatitis B virus (HBV) antigen expression showed significantly lower sCD40 levels than those who stained negative for the HBV antigen. The area under the receiver operating characteristic curve of sCD40 was greater than that of ALT and AST; thus, sCD40 levels have a high diagnostic accuracy for detecting severe liver inflammation in patients with CHB, and could serve as an immunological marker of hepatic tissue injury.

Restoration of albumin production by nucleoside analogue therapy in patients with chronic hepatitis B

The clinical course of patients with chronic hepatitis B (CH-B) was greatly changed by the introduction of nucleoside analogues. We often encounter patients where the serum level of albumin recovers quickly following the treatment. In this study, we focused carefully on the changes in serum albumin level noted during nucleoside analogue therapy, in an effort to clarify the mechanism behind the restoration of albumin production. We observed changes in serum albumin levels during nucleoside analogue therapy in 12 patients with CH-B and studied the mechanism behind the restoration of albumin production following the therapy. The serum level of albumin was significantly increased very soon after the treatment was started. Prior to treatment with nucleoside analogues, the albumin signal for mRNA was only slightly seen in the peri-portal area, whereas 12 months after the treatment, the liver tissue presented an obvious signal of albumin mRNA. Serum levels of hepatocyte growth factor (HGF) were significantly decreased 12 months after the treatment. In this study, we demonstrated that nucleoside analogues decrease HGF through the suppression of hepatocyte damage, leading to the restoration of albumin production in patients with CH-B.

Blockade of immunosuppressive cytokines restores NK cell antiviral function in chronic hepatitis B virus infection

NK cells are enriched in the liver, constituting around a third of intrahepatic lymphocytes. We have previously demonstrated that they upregulate the death ligand TRAIL in patients with chronic hepatitis B virus infection (CHB), allowing them to kill hepatocytes bearing TRAIL receptors. In this study we investigated whether, in addition to their pathogenic role, NK cells have antiviral potential in CHB. We characterised NK cell subsets and effector function in 64 patients with CHB compared to 31 healthy controls. We found that, in contrast to their upregulated TRAIL expression and maintenance of cytolytic function, NK cells had a markedly impaired capacity to produce IFN-γ in CHB. This functional dichotomy of NK cells could be recapitulated in vitro by exposure to the immunosuppressive cytokine IL-10, which was induced in patients with active CHB. IL-10 selectively suppressed NK cell IFN-γ production without altering cytotoxicity or death ligand expression. Potent antiviral therapy reduced TRAIL-expressing CD56^bright NK cells, consistent with the reduction in liver inflammation it induced; however, it was not able to normalise IL-10 levels or the capacity of NK cells to produce the antiviral cytokine IFN-γ. Blockade of IL-10 +/− TGF-β restored the capacity of NK cells from both the periphery and liver of patients with CHB to produce IFN-γ, thereby enhancing their non-cytolytic antiviral capacity. In conclusion, NK cells may be driven to a state of partial functional tolerance by the immunosuppressive cytokine environment in CHB. Their defective capacity to produce the antiviral cytokine IFN-γ persists in patients on antiviral therapy but can be corrected in vitro by IL-10+/− TGF-β blockade.

Hepatitis B virus (HBV) infection is responsible for more than a million deaths annually as a result of the immune-mediated chronic liver damage it induces. One of the key immune players in the liver is the natural killer (NK) cell, which we have recently found can cause liver damage in HBV infection. Here we address the antiviral potential of NK cells in the HBV-infected liver and demonstrate that they have a specific impairment in their ability to produce the cytokine IFN-γ, which could limit their capacity to control HBV. We find that the potent antiviral drugs currently being used to treat HBV infection are unable to fully reverse this NK cell functional defect. We define a role for the immunosuppressive cytokine environment in HBV in down-regulating NK cell antiviral function, which can be restored by specific blockade of IL-10 and TGF-β. This work therefore highlights a mechanism contributing to the failure of immune control in chronic HBV infection, paving the way to new therapeutic options.

Putative roles of hepatitis B x antigen in the pathogenesis of chronic liver disease

Under most circumstances, hepatitis B virus (HBV) is noncytopathic. However, hepatocellular regeneration that accompanies each bout of hepatitis appears to be associated with increased integration of HBV DNA fragments expressing the virus encoded hepatitis B x antigen (HBxAg). Intrahepatic HBxAg staining correlates with the intensity and progression of chronic liver disease (CLD), and additional work has shown that HBxAg blocks immune mediated killing by Fas and by tumor necrosis factor alpha (TNFalpha). This is not only associated with the blockage of caspase activities by HBxAg, but also by the constitutive stimulation of hepatoprotective pathways, such as nuclear factor kappa B (NF-kappaB), phosphoinositol 3-kinase (PI3K), and beta-catenin (beta-catenin). HBxAg also appears to promote fibrogenesis, by stimulating the production of fibronectin. HBxAg also stimulates the production and activity of transforming growth factor beta1 (TGFbeta1) by several mechanisms, thereby promoting the profibrogenic and tumorigenic properties of this important cytokine. In addition, HBxAg appears to remodel the extracellular matrix (ECM) by altering the expression of several matrix metalloproteinases (MMPs), which may promote tumor metastasis. Hence, HBxAg appears to promote chronic infection by preventing immune mediated apoptosis of infected hepatocytes, by promoting the establishment and persistence of fibrosis and cirrhosis preceding the development of HCC, and by promoting the remodeling of EMC during tumor progression.

Expression of MMPs and TIMPs in liver fibrosis - a systematic review with special emphasis on anti-fibrotic strategies

In liver tissue matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitors of metalloproteinases, TIMPs) play a pivotal role in both, fibrogenesis and fibrolysis. The current knowledge of the pathophysiology of liver fibrogenesis with special emphasis on MMPs and TIMPs is presented. A systematic literature search was conducted. All experimental models of liver fibrosis that evaluated a defined anti-fibrotic intervention in vivo or in vitro considering MMPs and TIMPs were selected. The methodological quality of all these publications has been critically appraised using an objective scoring system and the content has been summarized in a table.

Effect of pegylated interferon alpha 2b plus ribavirin treatment on plasma transforming growth factor-β1, metalloproteinase-1, and tissue metalloproteinase inhibitor-1 in patients with chronic hepatitis C

AIM: To evaluate the effect of antiviral treatment on plasma levels of transforming growth factor-β1 (TGF-β1), metalloproteinase 1 (MMP-1), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in patients with chronic hepatitis C.

METHODS: TGF-β1, MMP-1, and TIMP-1 plasma concentrations were measured by an enzyme immunoassay in 28 patients, during 48 wk of treatment with pegylated interferon-alpha 2b (PEG-IFN-α2b) plus ribavirin (RBV) and after 24 wk of follow-up. Patients were divided into two groups: responders (R) and non-responders (NR) related to achieved sustained virologic response. Normal values were evaluated in plasma samples of 13 healthy volunteers.

RESULTS: Baseline plasma concentrations of TGF-β1 and TIMP-1 (30.9±3.7 and 1 506±61 ng/mL respectively) measured in all subjects significantly exceeded the normal values (TGF-β1: 18.3±1.6 ng/mL and TIMP-1: 1 102±67 ng/mL). In contrast, pretreatment MMP-1 mean level (6.5±0.9 ng/mL) was significantly lower than normal values (11.9±0.9 ng/mL). Response to the treatment was observed in 12 patients (43%). TGF-β1 mean concentration measured during the treatment phase decreased to the control level in both groups. However at wk 72, values of NR patients increased and became significantly higher than in R group. TIMP-1 concentrations in R group decreased during the treatment to the level similar to normal. In NR group, TIMP-1 remained significantly elevated during treatment and follow-up phase and significant difference between both groups was demonstrated at wk 48 and 72. MMP-1 levels were significantly decreased in both groups at baseline. Treatment caused rise of its concentration only in the R group, whereas values in NR group remained on the level similar to baseline. Statistically significant difference between groups was noted at wk 48 and 72.

CONCLUSION: These findings support the usefulness of TGF-β1, TIMP-1, and MMP-1 in the management of chronic hepatitis C. Elevated TIMP-1 and low MMP-1 plasma concentrations during antiviral therapy may indicate medication failure.

Plasma transforming growth factor β1, metalloproteinase-1 and tissue inhibitor of metalloproteinases-1 in acute viral hepatitis type B

AIM

Antiproliferative, pro-apoptotic and immunosuppressive activity effects suggest crucial role of transforming growth factor (TGF)-beta1, metalloproteinase (MMP)-1 and its tissue inhibitor (TIMP)-1 in the pathogenesis of acute liver injury that in some patients precede development of chronic liver diseases and fibrogenesis. The aim of this study was to evaluate effect of acute HBV infection on plasma TGF-beta1, MMP-1 and TIMP-1 levels.

METHODS

TGF-beta1, MMP-1 and TIMP-1 plasma concentrations were measured with an enzyme immunoassay in 39 patients with acute viral hepatitis type B. Baseline measurement was performed within the first week of jaundice and then weekly up to the fourth week of the disease. Results were compared to baseline and normal values and to liver function tests.

RESULTS

Plasma concentrations of TGF-beta1, TIMP-1 and MMP-1 were significantly elevated in the first week of acute viral B hepatitis in comparison to normal. Analysis of individual values demonstrated significant positive correlation between plasma concentrations of TGF-beta1 and TIMP-1. There was no correlation between MMP-1 and TGF-beta1 or TIMP-1. Significant correlation was demonstrated between both TGF-beta1 and ALT or AST as well as between TIMP-1 and ALT, AST or bilirubin. Elevated baseline levels of both TGF-beta1 and TIMP-1 decreased gradually in consecutive weeks of the disease. TGF-beta1 but not TIMP-1 plasma concentrations were significantly lower in 3rd and 4th week than baseline values. MMP-1 concentration remained on baseline level in the 2nd week of the disease. However in the 3rd week its values increased suddenly but the significant difference in comparison to baseline was observed only in 4th week.

CONCLUSIONS

These results indicate important role of TGF-beta1, TIMP-1 and MMP-1 in acute viral hepatitis, that seems to be connected first of all with hepatocytes damage. Their role in extracellular matrix metabolism during acute liver injury needs further evaluation.