Dendritic cells: The warriors upfront-turned defunct in chronic hepatitis C infection

Recent Advances in Anticancer Activity of Novel Plant Extracts and Compounds from Curcuma longa in Hepatocellular Carcinoma

PURPOSE

Among all forms of cancers, hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. There are several treatment options for HCC ranging from loco-regional therapy to surgical treatment. Yet, there is high morbidity and mortality. Recent research focus has shifted towards more effective and less toxic cancer treatment options. Curcumin, the active ingredient in the Curcuma longa plant, has gained widespread attention in recent years because of its multifunctional properties as an antioxidant, anti-inflammatory, antimicrobial, and anticancer agent.

METHODS

A systematic search of PubMed, Embase and Google Scholar was performed for studies reporting incidence of HCC, risk factors associated with cirrhosis and experimental use of curcumin as an anti-cancer agent.

RESULTS

This review exclusively encompasses the anti-cancer properties of curcumin in HCC globally and it's postulated molecular targets of curcumin when used against liver cancers.

CONCLUSIONS

This review is concluded by presenting the current challenges and future perspectives of novel plant extracts derived from C. longa and the treatment options against cancers.

Effect of Direct Acting Antivirals (DAAs) on Myeloid-Derived Suppressor Cells Population in Egyptian Chronic Hepatitis C Virus Patients: A Potential Immunomodulatory Role of DAAs

Chronic hepatitis C is a major health concern with high morbidity and mortality rates. The introduction of direct acting antivirals (DAAs) as a first-line treatment for hepatitis C virus (HCV) has significantly enhanced HCV eradication. However, DAA therapy is facing rising concerns regarding long-term safety, viral resistance, and reinfection. HCV is associated with different immune alteration mechanisms that can evade immunity and establish persistent infection. One of these suggested mechanisms is the accumulation of myeloid-derived suppressor cells (MDSCs), which is known to accumulate in chronic inflammatory conditions. Moreover, the role of DAA in restoring immunity after successful viral eradication is still unclear and needs further investigations. Thus, we aimed to investigate the role of MDSCs in chronic HCV Egyptian patients and its response to DAA in treated compared with untreated patients. Fifty untreated chronic hepatitis C (CHC) patients, 50 DAA-treated CHC patients, and 30 healthy individuals were recruited. We used flow cytometer analysis to measure MDSCs frequency and enzyme-linked immunosorbent assay analysis to evaluate the serum level of interferon (IFN)-γ. We found a significant elevation in MDSC% among the untreated group (34.5 ± 12.4%) compared with the DAA-treated group (18.3 ± 6.7%), while the control group had a mean of (3.8 ± 1.6%). IFN-γ concentration was higher in treated patients compared with untreated. We also found a significant negative correlation (rs -0.662) (p < 0.001) between MDSC% and IFN-γ concentration among treated HCV patients. Our results revealed important evidence of MDSCs accumulation in CHC patients and partial retrieval of the immune system regulatory function after DAA therapy.

Changes in Serum Interferon Gamma and Interleukin-10 in Relation to Direct-Acting Antiviral Therapy of Chronic Hepatitis C Genotype 4: A Pilot Study

Introduction

This study analyzes the changing levels of circulating inflammatory cytokines Interferon gamma (IFN-γ) and interleukin (IL)-10 (as the main cytokines of T-helper-1 and T-helper-2 immune responses) in patients with chronic hepatitis C virus (HCV) infection undergoing therapy with direct-acting antivirals (DAAs) and to correlate them with laboratory markers.

Methods

This Pilot study included 50 HCV monoinfected patients who received DAAs for 12 or 24 weeks. They were followed up monthly during therapy and 3 months after the end of the treatment. Liver disease was determined by transient elastography, in addition to FIB-4 indices. Analysis of IFN-gamma and IL-10 was carried out using an enzyme-linked immunosorbent assay.

Results

All patients carried HCV genotype 4. The Sustained virological response was 100% and 92% in cirrhotics and noncirrhotics, respectively. There was no significant difference between groups in baseline IL-10 or IFN-gamma. In noncirrhotics, IL-10 showed a significant reduction at Week 4 after treatment start. In cirrhotics, IL-10 showed a significant reduction at Week 4 after treatment starts and a significant reduction at Week 12 after the end of the treatment. At Week 12 after the end of the treatment, serum IL-10 levels were significantly lower in cirrhotics. IFN-γ showed nonsignificant changes in noncirrhotics. A significant increase of IFN-γ occurred in cirrhotics from Week 4 after treatment starts to 12 weeks after the end of the treatment. IFN-γ was significantly higher in cirrhotics at Week 12 after the end of the treatment. IFN-γ and IL-10 showed different correlations with laboratory markers.

Conclusion

Viral eradication induced by DAAs caused a significant change in IL-10 and IFN-gamma.

Chronic hepatitis C virus infection impairs natural killer cells-dendritic cells cross-talk: An in vitro culture study

To examine the cross-talk between NK cells and DCs in hepatitis C virus (HCV) infection, we isolated monocytes and NK cells from 20 chronic HCV patients and 20 healthy controls. Monocytes were used to generate immature DCs which were pulsed with HCV peptides (core, NS3-NS4, and NS5). Four different cocultures were carried out: E1, both DCs and NK cells were from a chronic HCV patient; E2, NK cells from a healthy control cocultured with DCs from a chronic HCV patient; E3, NK cells from a chronic HCV patient cocultured with DCs from a healthy control; and E4, both DCs and NK cells were from a healthy control. Using flow cytometry, we assessed the effect of these different cocultures on levels of maturation markers on DCs and levels of activation/inhibition markers on NK cells. Results showed that peptide-pulsed HCV DCs showed a maturation defect in the form of decreased HLA-DR, decreased CD86, and increased CD83 expression especially when cocultured with HCV NK. This was mainly due to core peptide pulsing and to a lesser extent due to NS5 pulsing, whereas there was no effect with NS3-NS4 pulsing. Alternatively, HCV NK cells upregulated both activation and inhibition markers especially when cocultured with healthy DCs. Compared with E2, E1 resulted in higher apoptosis of both NK cells and DCs with the percentage of NK apoptosis higher than that of DCs. Taken together, the data indicate that HCV infection impairs NK-DC cross-talk which may be a leading cause in viral persistence and chronicity.

Adaptive Immune Response against Hepatitis C Virus

A functional adaptive immune response is the major determinant for clearance of hepatitis C virus (HCV) infection. However, in the majority of patients, this response fails and persistent infection evolves. Here, we dissect the HCV-specific key players of adaptive immunity, namely B cells and T cells, and describe factors that affect infection outcome. Once chronic infection is established, continuous exposure to HCV antigens affects functionality, phenotype, transcriptional program, metabolism, and the epigenetics of the adaptive immune cells. In addition, viral escape mutations contribute to the failure of adaptive antiviral immunity. Direct-acting antivirals (DAA) can mediate HCV clearance in almost all patients with chronic HCV infection, however, defects in adaptive immune cell populations remain, only limited functional memory is obtained and reinfection of cured individuals is possible. Thus, to avoid potential reinfection and achieve global elimination of HCV infections, a prophylactic vaccine is needed. Recent vaccine trials could induce HCV-specific immunity but failed to protect from persistent infection. Thus, lessons from natural protection from persistent infection, DAA-mediated cure, and non-protective vaccination trials might lead the way to successful vaccination strategies in the future.

Hepatocellular Carcinoma Mechanisms Associated with Chronic HCV Infection and the Impact of Direct-Acting Antiviral Treatment

Hepatitis C virus (HCV) infection is the major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). The mechanisms of HCC initiation, growth, and metastasis appear to be highly complex due to the decade-long interactions between the virus, immune system, and overlapping bystander effects of host metabolic liver disease. The lack of a readily accessible animal model system for HCV is a significant obstacle to understand the mechanisms of viral carcinogenesis. Traditionally, the primary prevention strategy of HCC has been to eliminate infection by antiviral therapy. The success of virus elimination by antiviral treatment is determined by the SVR when the HCV is no longer detectable in serum. Interferon-alpha (IFN-α) and its analogs, pegylated IFN-α (PEG-IFN-α) alone with ribavirin (RBV), have been the primary antiviral treatment of HCV for many years with a low cure rate. The cloning and sequencing of HCV have allowed the development of cell culture models, which accelerated antiviral drug discovery. It resulted in the selection of highly effective direct-acting antiviral (DAA)-based combination therapy that now offers incredible success in curing HCV infection in more than 95% of all patients, including those with cirrhosis. However, several emerging recent publications claim that patients who have liver cirrhosis at the time of DAAs treatment face the risk of HCC occurrence and recurrence after viral cure. This remains a substantial challenge while addressing the long-term benefit of antiviral medicine. The host-related mechanisms that drive the risk of HCC in the absence of the virus are unknown. This review describes the multifaceted mechanisms that create a tumorigenic environment during chronic HCV infection. In addition to the potential oncogenic programming that drives HCC after viral clearance by DAAs, the current status of a biomarker development for early prediction of cirrhosis regression and HCC detection post viral treatment is discussed. Since DAAs treatment does not provide full protection against reinfection or viral transmission to other individuals, the recent studies for a vaccine development are also reviewed.

Immunotherapy with interferon-α-induced dendritic cells for chronic HCV infection (the results of pilot clinical trial)

The key role of T cells in hepatitis C virus (HCV) elimination and the ability of dendritic cells (DCs) to induce antiviral T cell responses suggest that DC vaccines could be a promising approach in the treatment of chronic HCV infection. The aim of our study was to evaluate, whether immunotherapy with DCs is safe and elicits anti-HCV T cell responses. Ten patients with HCV (genotype 1) were vaccinated with monocyte-derived DCs, generated in the presence of IFN-α (IFN-DCs) and pulsed with recombinant HCV Core and NS3 proteins. Treatment schedule included four subcutaneous vaccinations with 1 week interval and six vaccinations with month interval. No serious adverse events or an increase in hepatitis C biochemical activity were registered after vaccination. Using ex vivo assays for the detection of proliferative responses, IFN-γ production and CD8⁺ degranulation have shown that immunotherapy elicited antigen-specific responses in all patients although individual heterogeneity existed within their types, magnitude, and timing. Core/NS3-specific proliferative response and CD8⁺ T cell degranulation have already been registered after the first course of vaccination. Of note, Core-specific responses had higher magnitude. The appearance of antigen-specific IFN-γ responses was registered after the second vaccination course. Vaccination did not cause Th2 response and expansion of the CD4⁺CD25⁺CD127^- regulatory T cells. Generated immune responses failed to provide virus elimination. Nevertheless, there were inverse correlations between viral load and NS3-specific proliferation (R _S = 0.62; p = 0.05) and IFN-γ secretion (R _S = - 0.82; p = 0.001) at 6-month post-treatment period. Immunotherapy with IFN-DCs was safe and elicited HCV-specific T cell responses which were insufficient to eliminate viruses but could be implicated in the restriction of viral replication.

Reversing immune dysfunction and liver damage after direct-acting antiviral treatment for hepatitis C

The introduction of small molecules targeting viral functions has caused a paradigm shift in hepatitis C virus (HCV) treatment. Administration of these direct-acting antivirals (DAAs) achieves a complete cure in almost all treated patients with short-duration therapy and minimal side effects. Although this is a major improvement over the previous pegylated interferon plus ribavirin (PEG-IFNα/RBV) standard-of-care treatment for HCV, remaining questions address several aspects of the long-term benefits of DAA therapy. Interferon (IFN)-based treatment with successful outcome was associated with substantial reduction in liver disease–related mortality. However, emerging data suggest a complex picture and several confounding factors that influence the effect of both IFN-based and DAA therapies on immune restoration and limiting liver disease progression. We review current knowledge of restoration of innate and HCV-specific immune responses in DAA-mediated viral elimination in chronic HCV infection, and we identify future research directions to achieve long-term benefits in all cured patients and reduce HCV-related liver disease morbidity and mortality.

Current progress in host innate and adaptive immunity against hepatitis C virus infection

Hepatitis C virus (HCV) infects more than 170 million people worldwide and is the main cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. Although the newly developed direct-acting antivirals (DAAs) have transformed the treatment of HCV infection, controlling HCV infection on a global scale remains a challenge because of the high cost, low resistance barrier of DAAs and lack of HCV vaccine. The host immune responses associated with HCV infection, especially HCV-specific T cellular immunity, determine the outcome of HCV infection: either acute or chronic infection. It is important to fully interpret the immunopathogenesis of HCV infection and consequently to exploit effective strategies to eliminate HCV. Here, we review the current progress in HCV immunology, which will deepen our understanding of the spectrum of HCV infection and immunity in humans.