Neutralization of transforming growth factor beta 1 augments hepatitis C virus-specific cytotoxic T lymphocyte induction in vitro

Host immune response in chronic hepatitis C infection: involvement of cytokines and inflammasomes

Chronic liver disease is a major health issue worldwide and chronic hepatitis C (CHC) is associated with an increased risk of cirrhosis and hepatocellular carcinoma (HCC). There is evidence that the hepatitis C virus (HCV) infection is correlated with immune senescence by way of immune activation and chronic inflammation, which lead to increased metabolic and cardiovascular risk, as well as progressive liver damage. Both the innate and adaptive immunity are firmly tied to the prognosis of an infection with HCV and its response to antiviral therapy. HCV is therefore associated with increased pro-inflammatory status, heightened production of cytokines, prolonged systemic inflammation, as well as increased morbidity and mortality, mainly due to the progression of hepatic fibrosis and HCC, but also secondary to cardiovascular diseases. Viral hepatic pathology is increasingly considered a disease that is no longer merely limited to the liver, but one with multiple metabolic consequences. Numerous in vitro studies, using experimental models of acute or chronic inflammation of the liver, has brought new information on immunopathological mechanisms resulting from viral infections and have highlighted the importance of involving complex structures, inflammasomes complex, in these mechanisms, in addition to the involvement of numerous proinflammatory cytokines. Beyond obtaining a sustained viral response and halting the aforementioned hepatic fibrosis, the current therapeutic “treat-to-target” strategies are presently focused on immune-mediated and metabolic disorders, to improve the quality of life and long-term prognosis of CHC patients.

Serum cytokines, adipokines and ferritin for non-invasive assessment of liver fibrosis in chronic liver disease: a systematic review

Chronic liver disease (CLD) is a major health problem worldwide. Non-alcoholic fatty liver disease (NAFLD), chronic hepatitis C (CHC), chronic hepatitis B (CHB), and alcoholic liver disease (ALD) are the most common etiologies of CLD. Liver biopsy is the gold standard for assessment of liver fibrosis, however, it is an invasive method. This review attempts to evaluate the usefulness of serum adiponectin, serum leptin, serum ferritin, serum transforming growth factor-β1 (TGF-β1), and serum platelet derived growth factor-BB (PDGF-BB) as non-invasive markers in the diagnosis of liver fibrosis/cirrhosis. A systematic search in MEDLINE, Web of Science, Scopus, and local databases was performed to identify articles published in English or Persian as of November 2017. Studies conducted among CLD patients, with biopsy proven fibrosis/cirrhosis, and providing sufficient details of patients' clinicopathological characteristics were included. In the 95 studies included, there were a total of 15,548 CLD patients. More than 83% of studies were carried out in Asia and Europe. The relationship between liver fibrosis/cirrhosis and serum levels of ferritin, adiponectin, leptin, TGF-β1, and PDGF-BB was assessed in 42, 33, 27, nine, and three studies, respectively. Serum levels of the markers, particularly ferritin, could successfully predict liver fibrosis/cirrhosis, however, these data might not be clinically replicated and further studies are needed.

Overexpression of cyclooxygenase-2 and transforming growth factor-beta 1 is an independent predictor of poor virological response to interferon therapy in chronic HCV genotype 4 patients

BACKGROUND/AIMS

COX-2 and TGF-β1 are overexpressed in hepatitis C virus (HCV) infection and are related to hepatitis pathogenesis and hepatic fibrosis. The current study investigated the relationship between pretreatment COX-2 and TGF-β1 hepatic expression in HCV genotype 4 and the virological response to interferon therapy.

PATIENTS AND METHODS

Liver biopsies of 55 patients with HCV infection genotype 4 were selected together with 10 liver biopsies as control. The patients' clinicopathological data were collected. Immunohistochemistry was done using anti-COX-2 and anti-TGF-β1 antibodies. Statistical tests were used to determine the association between both COX-2 and TGF-β1 expression in relation to clinicopathological parameters and response to interferon therapy.

RESULTS

COX-2 was upregulated especially in nonresponders and was an independent predictor of poor virological response. However, COX-2 showed no association with other clinicopathological features. TGF-β1 was upregulated and associated with nonresponders, histological activity, and fibrosis stage. There was no association between TGF-β1 and other clinicopathological features. There was an association between COX-2 and TGF-β1 immunoexpression.

CONCLUSION

Overexpression of COX-2 and TGF-β1 is an independent predictor for poor outcome of interferon and ribavirin therapy and these might be useful markers for the response to treatment. Both molecules are associated together; however, their role during hepatitis treatment has to be clarified.

Immunology of hepatitis C virus infections

The immune response in patients chronically infected with HCV plays a unique role during the infection because of its potential to contribute not only to viral clearance and, in some cases, protective immunity, but also to liver injury. A detailed understanding of the immunological mechanisms involved in persistence to HCV is essential to fully appreciate the complexity of the disease. In recent years, enormous progress has been made to characterize the dysfunctional natural killer cells and T cells during the chronic phase of infection. This information is important to further optimize treatment strategies based on the strengthening antiviral and immunomodulatory activities in patients chronically infected with HCV.

Association of TGF-beta1 codon 25 (G915C) polymorphism with hepatitis C virus infection

Cytokines play a key role in the regulation of immune responses. In hepatitis C virus infection (HCV), the production of abnormal cytokine levels appears to contribute to the progression of the disease, viral persistence, and affects response to therapy. Cytokine genes are polymorphic at specific sites, and certain polymorphisms located within coding/regulatory regions have been shown to affect the overall expression and secretion of cytokines. The aim of the present study was to identify potential markers of cytokines genes associated with the susceptibility to HCV infection. The cohort was composed of 128 individuals infected by HCV and 94 healthy controls. Genotyping was carried out by PCR-SSP. The distributions of the following polymorphisms were compared in these groups: TNF-alpha (-308G/A [rs1800629]), TGF-beta1 (codon 10 T/C [rs1982073], codon 25 G/C [rs1800471]), IL-10 (-1082 A/G [rs 1800896]; -819T/C [rs1800871]; -592A/C [rs 1800872]), IL-6 (-174G/C [rs1800795]), and IFN-gamma (+874T/A [rs2430561]). This study demonstrated a statistically significant difference in the frequency of TGF-beta1 codon 25 polymorphism between healthy subjects and those infected with HCV. No associations were observed between polymorphisms of TNF-alpha, IFN-gamma, IL-10, TGF-beta1 codon 10, and IL-6 and HCV infection. These findings suggest that TGF-beta1 codon 25 polymorphism could be a host genetic factor associated with susceptibility to HCV infection.

Role of cytokine gene polymorphism and hepatic transforming growth factor β1 expression in recurrent hepatitis C after liver transplantation

Recurrent hepatitis C virus (HCV) infection after orthotopic liver transplantation (OLT) is nearly universal. Cytokines play an important role in the immune response to viral infection, and cytokine gene polymorphism affects the overall expression and secretion of cytokines. The objective of this study was to define the relationship between cytokine polymorphism and recurrent hepatitis C after OLT. Blood samples were collected from 36 patients at a mean of 44.6+/-30.4 months after OLT for chronic HCV infection. DNA was extracted from peripheral blood mononuclear cells, and polymerase chain reaction-sequence specific primers (PCR-SSP) analysis was performed on promoter sequences of transforming growth factor beta1 (TGF-beta1), interleukin 6 (IL-6) interleukin 10 (IL-10), tumor necrosis factor alpha (TNF-alpha) and interferon gamma (INF-gamma). Liver biopsies performed at diagnosis of recurrent disease were graded with the Knodell score, and hepatic TGF-beta1 expression was determined semiquantitatively by immunohistochemistry. The gene polymorphism of TGF-beta1 was correlated with its expression on hepatocytes and sinusoids. Polymorphism in all studied cytokine genes was correlated with recurrence, and interval to recurrence (>12 or < or =12 months post-OLT), and clinical (ascites, Child-Pugh score and death), biochemical parameters of recurrent HCV (serum alanine aminotransferase (ALT)), INR, albumin, bilirubin), and virological parameters (HCV genotype and load). Biopsies revealed recurrent HCV in 31 patients (86.1%); in 21 (67.7%), the interval to recurrence was 12 months. There was a statistically significant correlation between TGF-beta1 gene polymorphism, i.e., the genetic ability to produce high levels of TGF-beta1, and the intensity of TGF-beta1 staining on hepatocytes (p=0.003) and sinusoids (p=0.003), and the degree of fibrosis (p=0.02). A borderline correlation was found with the presence of ascites (p=0.007), but not with Child-Pugh score, synthetic liver function tests or HCV genotype and load. The genetic ability to produce low levels of IFN-gamma was correlated with recurrent disease (p=0.015). No such correlation was found for TGF-beta1 gene polymorphism. In conclusion, polymorphism in the TGF-beta1 gene correlates with its in situ hepatic expression in patients with recurrent HCV after liver transplantation. INF-gamma, but not TGF-beta1 gene polymorphism, correlates with early recurrent hepatitis C after transplantation. These findings might help to design preemptive prevention therapy in selected patients at risk.

Cyclosporin A induces proliferation in human gingival fibroblasts via induction of transforming growth factor-beta1

BACKGROUND

Cyclosporin A (CsA) is a widely used immunosuppressant that causes significant side effects including gingival overgrowth. The pathogenesis of this condition is not fully understood; however, recent studies show that CsA regulates the transcription of several cytokines including transforming growth factor-beta 1 (TGF-beta1). In this study, we evaluated the effects of CsA and TGF-beta1 on human normal gingival (NG) fibroblast proliferation, and explored a possible autocrine stimulation of TGF-beta1 as a cellular regulator of proliferation induced by CsA in NG fibroblasts.

METHODS

NG fibroblast cell lines were incubated with increasing concentrations of CsA or TGF-beta1 and the proliferation index determined by automatic cell counting, BrdU incorporation, PCNA expression, and mitotic potential. To determine the effect of TGF-beta1 on the proliferation rate of NG fibroblasts under CsA treatment, NG fibroblast cultures were simultaneously treated with CsA and antisense oligonucleotides against the translation-start site of the TGF-beta1 mRNA.

RESULTS

Treatment of NG fibroblasts with CsA or TGF-beta1 significantly stimulated the cell proliferation in a dose-dependent manner. Furthermore, neutralization of TGF-beta1 production in CsA-treated NG fibroblasts inhibited CsA's effect on NG fibroblast proliferation, demonstrating an autocrine stimulatory effect of TGF-beta1 in CsA-treated NG fibroblast proliferation.

CONCLUSION

The results presented here suggest that CsA stimulatory induction of NG fibroblast proliferation is mediated via TGF-beta1 in an autocrine fashion.

Transforming growth factor beta in hepatitis C virus infection: in vivo and in vitro findings

BACKGROUND

Hepatitis C virus (HCV) is a leading cause of chronic liver disease (CLD) worldwide. The chronicity is a result of viral persistence and the ability of the virus to escape from the immune mechanisms of the host. Transforming growth factor (TGF)-beta is a cytokine thought to be responsible for viral persistence and liver fibrogenesis.

METHODS

The present study examined the levels of TGF-beta messenger (m)RNA by reverse transcription polymerase chain reaction (RT-PCR) in 35 liver biopsies and HCV-transfected HepG2 cells.

RESULTS

Transforming growth factor-beta mRNA was detected in nine liver biopsies from patients with chronic HCV infection, but was not detected in patients with non-HCV-related CLD or controls. On quantitation by semiquantitative PCR, TGF-beta mRNA levels ranged from 10-4.75 to 10-12.8 amol (10-7.46 +/- 3.771) in liver biopsies of HCV-related CLD. No significant difference in TGF-beta receptor levels was observed by RT-PCR in HCV- or non-HCV-related CLD by immunohistochemistry. To correlate these findings with in vitro experiments, levels of TGF-beta mRNA and its receptors were determined by RT-PCR in HepG2 cells transfected with HCV and hepatitis B virus (HBV) constructs, using mock-transfected cells as control. The TGF-beta protein levels were quantitated in these cell supernatants by enzyme immunoassay. The TGF-beta mRNA and protein levels were two logs and approximately 30 times higher in HCV-transfected HepG2 cells than in HBV- and mock-transfected cells, respectively. The TGF-beta receptors in HepG2 cells were also downregulated in HCV-transfected cells as compared with mock-transfected cells.

CONCLUSION

These observations suggest upregulation of TGF-beta in HCV infection and a probable role for TGF-beta in the pathogenesis of HCV-related CLD.

STAT1 and STAT3 alpha/beta splice form activation predicts host responses in mouse hepatitis virus type 3 infection

Signal transducer and activator of transcription 1alpha (STAT1 alpha) is reported to be essential for IFN-gamma and IFN-alpha regulated gene expression, while STAT1 beta, an alternate splice-form, mediates only IFN-alpha-dependent gene expression. STAT3 alpha and STAT3 beta splice forms are also differentially activated in response to cytokines including IL-6 and IL-10. The aim of this study was to investigate whether the STAT activation will predict the host immune response to viral infection and possibly a therapeutic target for the treatment of viral infection. Mouse hepatitis virus type 3 (MHV-3) resistant strain (A/J) and sensitive mouse strains (BalB/cJ) were infected intraperitoneally (i.p.) with 100 plaque form units (pfu) of MHV-3. The mice were sacrificed at the indicated times, and livers and spleens were immediately frozen in liquid nitrogen. Nuclear extracts proteins were detected by immunoblotting. STAT1 and STAT3 activation in spleen increased 24 to 72 hr following MHV-3 infections in both sensitive and resistant mouse strains. However, over this time period, the ratio of activated alpha to beta splice-form for STAT1 and STAT3 increased above 1.0 in resistant A/J mice, while the ratio fell to <0.3 in MHV-3 sensitive Balb/cJ and C3H/HeJ strains. Activated STAT1 alpha/beta and STAT3 alpha/beta ratio in liver were similar in resistant and sensitive mouse strains. Treatment of sensitive Balb/cJ mice with neutralizing anti-TGF-beta antibody could increase the STAT1 alpha/beta ratio to <1.0 in spleens, predicting enhanced rates of survival. These results suggested that ratio of activated STAT1 alpha/beta and STAT3 alpha/beta in mixed leukocytes from spleen predict the outcome to MHV-3 infection, and may be an important marker and therapeutic target for modification of host immune response to virus infection.

Expression of matrix metalloproteinases in cyclosporin-treated gingival fibroblasts is regulated by transforming growth factor (TGF)-beta1 autocrine stimulation

BACKGROUND

Gingival overgrowth is a common side effect following the administration of cyclosporin A (CsA). The pathogenesis of this condition is not fully understood; however, recent studies show that CsA regulates the transcription of several cytokines including transforming growth factor-beta1 (TGF-beta1). The aim of this study was to investigate the potential role of TGF-beta1 in the pathogenesis of CsA-induced gingival overgrowth, exploring a possible autocrine stimulation of TGF-beta1 as a cellular regulator of synthesis of matrix metalloproteinases (MMPs) and its tissue inhibitors (TIMPs).

METHODS

Gingival fibroblasts from human normal gingiva were incubated with increasing concentrations of CsA, cultured for 24 hours, and the expression and production of TGF-beta1 determined by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. MMP and TIMP mRNA expression levels were also analyzed by RT-PCR. To determine the effect of TGF-beta1 on the expression of MMP and TIMP by human gingival fibroblasts under CsA treatment, human gingival fibroblast cultures were treated with sense oligonucleotides (SON) or antisense oligonucleotides (AON).

RESULTS

CsA simultaneously stimulated TGF-beta1 expression and production and inhibited expression of MMP-1 and MMP-2 by human gingival fibroblasts, whereas CsA has a slight effect on TIMP-1 and TIMP-2 expression. AON reduced TGF-beta1 production as demonstrated by ELISA, whereas TGF-beta1 mRNA expression levels were not significantly modified. The inhibition of TGF-beta1 production by AON modulated MMP expression, demonstrating the autocrine inhibitory effect of TGF-beta1 in CsA-treated human gingival fibroblasts.

CONCLUSIONS

The data presented here suggest that TGF-beta1 in an autocrine fashion may contribute to a reduction of proteolytic activity of human gingival fibroblasts in CsA-induced gingival overgrowth, which favors the accumulation of extracellular matrix.

Transforming growth factor-beta1 autocrine stimulation regulates fibroblast proliferation in hereditary gingival fibromatosis

BACKGROUND

Hereditary gingival fibromatosis (HGF) is a rare oral disease characterized by a slow and progressive enlargement of both the maxilla and mandible gingiva. Increased proliferation, elevated synthesis of extracellular matrix, particularly collagen, and reduced levels of matrix metalloproteinases seem to contribute to the pathogenesis of gingival overgrowth in HGF patients. Transforming growth factor-beta1 (TGF-beta1) is an important cytokine thought to play a major role in fibrotic disorders such as HGF due to its ability to stimulate the synthesis and reduce the degradation of extracellular matrix. In HGF fibroblasts, TGF-beta1 autocrine stimulation reduces expression and production of matrix metalloproteinases. However, the role of TGF-beta1 in fibroblast growth modulation has not been established in this disease.

METHODS

The aim of this study was to confirm the increased proliferation rate of HGF fibroblast cell lines and to explore a possible autocrine role of TGF-beta1 as a cell growth stimulator by blocking production of this endogenous cytokine using 2 well-established systems: antisense oligonucleotides and neutralizing antibodies.

RESULTS

Four different cellular proliferation assays, bromodeoxyuridine labeling, argyrophilic nucleolar organizing region staining, proliferating cell nuclear antigen, and mitotic indexes, confirmed that fibroblasts from HGF proliferate significantly faster than those from normal gingiva. Antisense oligonucleotides reduced TGF-beta1 production as demonstrated by capture enzyme-linked immunosorbent assay, whereas TGF-beta1 expression levels were not significantly modified. Blocking TGF-beta1 synthesis with oligonucleotides or its activity with specific antibodies resulted in a decreased magnitude of HGF fibroblast proliferation.

CONCLUSION

These results are consistent with the existence of an autocrine role of TGF-beta1 as a stimulator of HGF fibroblast proliferation.

Prediction of progressive liver fibrosis in hepatitis C infection by serum and tissue levels of transforming growth factor-beta

Although many patients with chronic viral hepatitis C infection suffer from progressive liver disease, the rate of fibrosis progression is highly variable and some patients do not show any measurable progression. However, our ability to predict which patients progress is very limited. Since transforming growth factor-beta (TGF-beta) is a key mediator of liver fibrogenesis, we assessed the predictive role of TGF-beta for fibrogenesis in chronic hepatitis C. We studied 39 patients with chronic hepatitis C in whom two liver biopsies were taken at least 12 months apart, and who did not receive therapy during this period. TGF-beta was measured by bioassay and by ELISA in serum samples taken at the time of the first biopsies, and TGF-beta was determined semiquantitatively by immunostaining of liver biopsy sections. Fibrosis was scored blinded in the biopsy samples by two pathologists independently. There was a close correlation between TGF-beta serum levels and the rate of fibrosis progression. Patients with no progression of fibrosis had significantly lower (59 ng/mL +/- 22) TGF-beta serum levels than patients with progressive disease (115 ng/mL +/- 20), and a TGF-beta level below 75 ng/mL was predictive for stable disease. Immunohistology for TGF-beta in biopsy samples was also predictive for progressive liver disease with fibrosis progression found in those patients displaying staining of hepatocytes and sinusoidal cells. No such correlation was found with other markers such as procollagen III peptide, viral load or transaminase levels. These results further support the role of TGF-beta in liver fibrogenesis, and offer an opportunity to predict clinical disease progression, which may help in selecting patients who are in need of therapeutic interventions.

Significance of serum soluble Fas antigen level in chronic hepatitis C patients treated with interferon: relationship to the therapeutic response

BACKGROUND AND AIM

Fas system-mediated cytotoxicity is thought to be involved in the development of liver injury in hepatitis C virus (HCV) infection. In this study, we investigated serum soluble Fas antigen levels in chronic hepatitis C patients treated with interferon and their correlation with the therapeutic response.

METHODS

The subjects were 67 chronic hepatitis C patients who underwent a 24-week course of alpha-interferon therapy. Patients were categorized into three groups; sustained responders (n = 22), transient responders (n = 24), and non-responders (n = 21), according to changes in the serum alanine aminotransferase level during and after therapy. The viral genotype, viremic level and diversity in the hypervariable region were examined before therapy. Serum soluble Fas antigen levels were assayed by using serum samples taken at the beginning and the end of therapy.

RESULTS

In the univariate analysis, serum soluble Fas antigen levels tended to be higher in non-responders (10.0 +/- 3.4 ng/mL) than in sustained responders (8.5 +/- 3.0 ng/mL) and transient responders (8.2 +/- 2.1 ng/mL; P = 0.13 and P < 0.05). The non-response to therapy was observed in eight of the 15 (53%) patients with serum soluble Fas antigen > or = 11 ng/mL, compared with 13 of the 52 (25%) patients with serum soluble Fas antigen < 11 ng/mL (P < 0.05). As for the multivariate analysis, the only significant factor contributing to the sustained response was a low HCV viremic level (P = 0.0046). Significant factors contributing to the non-response were a high serum alanine aminotransferase (P = 0.0407) and a high serum soluble Fas antigen level (P = 0.0483).

CONCLUSIONS

High production levels of soluble Fas antigen may be associated with a poor response to interferon therapy in chronic hepatitis C patients.

TGF-beta in infections and infectious diseases

Since it was first described as having the ability to inhibit macrophage activation, transforming growth factor-beta (TGF-beta) has been analyzed for its role in regulating immune responses to a variety of pathogens, including viruses, bacteria, yeast, and protozoa. Most of the studies have involved organisms that infect macrophages, and this discussion will attempt to highlight these findings. Perhaps the most work has been performed with protozoan pathogens, including Trypanosoma cruzi and a variety of Leishmania species, so the discussion will begin with these organisms. Other studies have focused on mycobacteria and viruses, including human immunodeficiency virus, so these areas will also be emphasized in the discussion. For the most part, investigators have reported that TGF-beta has, as expected, a negative influence on host responses and a beneficial effect on the survival and growth of intracellular pathogens. However, other studies have found that TGF-beta may have a positive or beneficial effect in some models of infection. This review will attempt to highlight studies and conclusions on the roles of TGF-beta in infection.

Downregulation of innate and acquired antitumor immunity by bystander gammadelta and alphabeta T lymphocytes with Th2 or Tr1 cytokine profiles

It has been thought that natural killer (NK) cells appearing early in tumor lesions play a pivotal role in the innate immunity against tumor cells. Although NK cells serve as the first tumoricidal effector cells, they subsequently promote a shift in effectors from themselves to tumor-specific cytotoxic T lymphocytes (CTLs) that mediate the acquired immunity. The mechanism of this shift has not been fully elucidated, however, NK cell-derived T helper (Th) 1 cytokines such as interferon (IFN)-gamma seem to play a key role. Another NK-lineage, termed natural killer T (NK T) cells, may also participate in the innate period when they acquire the ability to secrete Th1 cytokines. Interleukin-4 (IL-4) and IL-10, belonging to Th2, and transforming growth factor-beta (TGF-beta), belonging to T regulatory (Tr) 1 cytokines, are known to suppress the development of NK, NK T cells, as well as CTLs and to block Th0 cell differentiation to Th1 cells, suggesting that tumor cells can evade the innate and acquired immunity by virtue of cells producing these inhibitory cytokines. In early tumor lesions of murine B16 melanoma, gammadelta T and alphabeta intermediate (int) T cells that co-infiltrate with NK and NK T cells can produce Th2 cytokines and inhibit the innate immunity. In MM2 mammary tumor-bearing mice, gammadelta T cells appearing both lesionally and systemically secrete Tr1-type cytokines and depress the acquired immunity. These Th2- or Tr1-type gammadelta T and alphabeta(int) T cells downregulate the tumoricidal cells by means of both their secreted cytokines and express major histocompatibility complex (MHC) class I molecules.