Phenotypic analysis of circulating and intrahepatic dendritic cell subsets in patients with chronic liver diseases

Hepatocellular carcinoma immune microenvironment and check point inhibitors-current status

Hepatocellular carcinoma (HCC) is the most common primary tumor of the liver and has a high mortality rate. The Barcelona Clinic Liver Cancer staging system in addition to tumor staging also links the modality of treatment available to a particular stage. The recent description of the tumor microenvironment (TME) in HCC has provided a new concept of immunogenicity within the HCC. Virus-related HCC has been shown to be more immunogenic with higher expression of cytotoxic T lymphocytes and decreased elements for immunosuppression such as regulatory T cells. This immunogenic milieu provides a better response to immunotherapy especially immune checkpoint inhibitors (ICIs). In addition, the recent data on combining locoregional therapies and other strategies may convert the less immunogenic state of the TME towards higher immunogenicity. Therefore, data are emerging on the use of combinations of locoregional therapy and ICIs in unresectable or advanced HCC and has shown better survival outcomes in this difficult population.

The liver cancer immune microenvironment: Therapeutic implications for hepatocellular carcinoma

The liver is the sixth most common site of primary cancer in humans and the fourth leading cause of cancer-related death in the world. Hepatocellular carcinoma (HCC) accounts for 90% of liver cancers. HCC is a prevalent disease with a progression that is modulated by the immune system. Half of the patients with HCC receive systemic therapies, traditionally sorafenib or lenvatinib, as a first-line therapy. In the last few years, immune-checkpoint inhibitors (ICIs) have revolutionized cancer therapy and have gained an increased interest in the treatment of HCC. In 2020, the combination of atezolizumab (anti-programmed death-ligand 1) and bevacizumab (anti-vascular endothelial growth factor) improved overall survival over sorafenib, resulting in Food and Drug Administration (FDA) approval as a first-line treatment for patients with advanced HCC. Despite these major advances, a better molecular and cellular characterization of the tumor microenvironment is still needed because it has a crucial role in the development and progression of HCC. Inflamed (hot) and noninflamed (cold) HCC tumors and genomic signatures have been associated with response to ICIs. However, there are no additional biomarkers to guide clinical decision-making. Other immune-targeting strategies, such as adoptive T-cell transfer, vaccination, and virotherapy, are currently under development. This review provides an overview on the HCC immune microenvironment, different cellular players, current available immunotherapies, and potential immunotherapy modalities.

The Mechanism of Interleukin-35 in Chronic Hepatitis B

Interleukin-35 (IL-35) is a newly identified inhibitory cytokine. It has recently been found to play an extremely important role in chronic hepatitis B disease, which makes it likely to be a target for new therapies for hepatitis B malady. IL-35 modulates a variety of immune mechanisms to cause persistent viral infections, such as affecting the ratio of helper T cells, reducing the activity of cytotoxic T cells, hindering the antigen presentation capacity for dendritic cells, and increasing the transcription level of hepatitis B virus. On the other hand, IL-35 can control the inflammation caused by hepatitis B liver injury. Therefore, to seek a breakthrough in curing hepatitis B disease, the contradictory part of IL-35 in the occurrence and development of this sickness is worthy of further discussion and research. This article will systematically review the biological effects of IL-35 and the specific mechanisms affecting the disease.

Identification of miRNAs associated with dendritic cell dysfunction during acute and chronic hepatitis B virus infection

The uptake or expression of hepatitis B virus (HBV) proteins by dendritic cells (DCs) is considered important for disease outcome. Differential expression of microRNA (miRNA) may have a role in viral persistence and hepatocellular injury. The miRNA expression was investigated by microarray in DCs from different stages of HBV infection and liver disease namely, immune active (IA; n = 20); low replicative (LR; n = 20); HBeAg negative (n = 20); acute viral hepatitis (AVH, n = 20) and healthy controls (n = 20). miRNA levels were analyzed by unsupervised hierarchical clustering and principal component analyses and validated by quantitative polymerase Chain Reaction (qPCR). The miRNA-messenger RNA (mRNA)regulatory networks identified 19 miRNAs and 12 target gene interactions in major histocompatibility complex and other immune pathways. miR-2278, miR-615-3p, and miR-3681-3p were downregulated in the IA group compared to healthy control, miR-152-3p and miR-3613-3p in the LR group compared to IA group and miR-152-3p and miR-503-3p in HBe negative compared to LR group. However, miR-7-1-1-3p, miR-192-5p, miR-195-5p, and miR-32-5p in LR, miR-342-3p, and miR-940 in HBe negative, and miR-34a-5p, miR-130b-3p, miR-221-3p, miR-320a, miR-324-5p, and miR-484 in AVH were upregulated. Further, qPCR confirmed changes in miRNA levels and their target genes associated with antigen processing and presentation. Thus, a deregulated network of miRNAs-mRNAs in DCs seems responsible for an impaired immune response during HBV pathogenesis.

Natural Killer-Dendritic Cell Interactions in Liver Cancer: Implications for Immunotherapy

Simple Summary

The reciprocal crosstalk between dendritic cells (DCs) and natural killer (NK) cells plays a pivotal role in regulating immune defense against viruses and tumors. The Th-cell polarizing ability, cytokine-producing capacity, chemokine expression, and migration of DCs are regulated by activated NK cells. Conversely, the effector functions including lysis and cytokine production, proliferation, and migration of NK cells are influenced by close interactions with activated DCs. In this review, we explore the impact of DC–NK cell crosstalk and its therapeutic potential in immune control of liver malignances.

Abstract

Natural killer (NK) and dendritic cells (DCs) are innate immune cells that play a crucial role in anti-tumor immunity. NK cells kill tumor cells through direct cytotoxicity and cytokine secretion. DCs are needed for the activation of adaptive immune responses against tumor cells. Both NK cells and DCs are subdivided in several subsets endowed with specialized effector functions. Crosstalk between NK cells and DCs leads to the reciprocal control of their activation and polarization of immune responses. In this review, we describe the role of NK cells and DCs in liver cancer, focusing on the mechanisms involved in their reciprocal control and activation. In this context, intrahepatic NK cells and DCs present unique immunological features, due to the constant exposure to non-self-circulating antigens. These interactions might play a fundamental role in the pathology of primary liver cancer, namely hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). Additionally, the implications of these immune changes are relevant from the perspective of improving the cancer immunotherapy strategies in HCC and ICC patients.

Strategies Targeting the Innate Immune Response for the Treatment of Hepatitis C Virus-Associated Liver Fibrosis

Direct-acting antivirals eliminate hepatitis C virus (HCV) in more than 95% of treated individuals and may abolish liver injury, arrest fibrogenesis, and reverse fibrosis and cirrhosis. However, liver regeneration is usually a slow process that is less effective in the late stages of fibrosis. What is more, fibrogenesis may prevail in patients with advanced cirrhosis, where it can progress to liver failure and hepatocellular carcinoma. Therefore, the development of antifibrotic drugs that halt and reverse fibrosis progression is urgently needed. Fibrosis occurs due to the repair process of damaged hepatic tissue, which eventually leads to scarring. The innate immune response against HCV is essential in the initiation and progression of liver fibrosis. HCV-infected hepatocytes and liver macrophages secrete proinflammatory cytokines and chemokines that promote the activation and differentiation of hepatic stellate cells (HSCs) to myofibroblasts that produce extracellular matrix (ECM) components. Prolonged ECM production by myofibroblasts due to chronic inflammation is essential to the development of fibrosis. While no antifibrotic therapy is approved to date, several drugs are being tested in phase 2 and phase 3 trials with promising results. This review discusses current state-of-the-art knowledge on treatments targeting the innate immune system to revert chronic hepatitis C-associated liver fibrosis. Agents that cause liver damage may vary (alcohol, virus infection, etc.), but fibrosis progression shows common patterns among them, including chronic inflammation and immune dysregulation, hepatocyte injury, HSC activation, and excessive ECM deposition. Therefore, mechanisms underlying these processes are promising targets for general antifibrotic therapies.

The hepatic microenvironment and regulatory T cells

The human liver is regarded as a lymphoid organ that contributes to both local and systemic immune response. Intrahepatic immune cells including regulatory T cells (Tregs) reside in the hepatic microenvironment which is enriched with proinflammatory cytokines, chemokines and metabolites. In addition, the hepatic microenvironment has the unique ability to establish and maintain immune tolerance despite the continuous influx of the gut derived microbial products via the portal vein. Regulatory T cells play a crucial role in maintaining the hepatic tolerogenic state; however, the phenotypic stability, function and survival of Tregs in the inflamed liver microenvironment is still poorly understood. Despite this, Tregs immunotherapy remains as an appealing therapeutic option in autoimmune and immune mediated liver diseases. In order to advance cell therapy, it is important for us to further our understanding of the hepatic microenvironment, with the aim of developing ways to modify the hostile, inflamed environment to one which is more favourable. By doing so, T cell stability and function would be enhanced, resulting in improved clinical outcomes.

Characterization of dendritic cells in human and experimental myocarditis

Aims

Dendritic cells (DCs) are central mediators of adaptive immunity, and there is growing evidence of their role in myocardial inflammatory disease. We hypothesized that plasmacytoid and myeloid DCs are involved in the mechanisms of myocarditis and analysed these two main subtypes in human myocarditis subjects, as well as in a murine model of experimental autoimmune myocarditis (EAM).

Methods and results

Circulating DCs were analysed by flow cytometry in patients with acute myocarditis, dilated cardiomyopathy, and controls. Myocardial biopsies were immunostained for the presence of DCs and compared with non‐diseased controls. In a mouse model of acute myocarditis induced through synthetic cardiac myosine peptide injection, effects of immunomodulation including DC inhibition through MCS‐18 versus placebo treatment were tested at the peak of inflammation (Day 21), as well as 1 week later (partial recovery). Circulatory pDCs and mDCs were significantly reduced in myocarditis patients compared with controls (P < 0.01 for both) and remained so even after 6 months of follow‐up. Human myocarditis biopsies showed accumulation of pDCs (two‐fold CD304+/three‐fold CD123+, all P < 0.05) compared with controls. Myocardial pDCs and mDCs accumulated in EAM (P for both <0.0001). MCS‐18 treatment reduced pDC levels (P = 0.009), reduced myocardial inflammation (myocarditis score reduction from 2.6 to 1.8, P = 0.026), and improved ejection fraction (P = 0.03) in EAM at Day 21 (peak of inflammation). This effect was not observed during the partial recovery of inflammation on Day 28.

Conclusions

Circulating DCs are reduced in human myocarditis and accumulate in the inflamed myocardium. MCS‐18 treatment reduces DCs in EAM, leading to amelioration of inflammation and left ventricular remodelling during the acute phase of myocarditis. Our data further elucidate the role of DCs and their specific subsets in acute inflammatory cardiomyopathies.

Protective Effect of Eckol against Acute Hepatic Injury Induced by Carbon Tetrachloride in Mice

Several in vitro studies have shown the potential hepatoprotective properties of eckol, a natural phlorotannin derived from the brown alga. However, the in vivo hepatoprotective potential of eckol has not been determined. In this study, we performed an in vivo study to investigate the protective effect of eckol and its possible mechanisms on the carbon tetrachloride (CCl₄)-induced acute liver injury model in mice. Results revealed that eckol pre-treatment at the dose of 0.5 and 1.0 mg/kg/day for 7 days significantly suppressed the CCl₄-induced increases of alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum and meliorated morphological liver injury. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) analysis showed that the number of positive apoptotic hepatocytes in the eckol-treated group was lower than that in the CCl₄ model group. Western blotting analysis also demonstrated the enhanced expression of bcl-2 and suppressed expression of cleaved caspase-3 by eckol. The CCl₄-induced oxidative stress in liver was significantly ameliorated by eckol, which was characterized by reduced malondialdehyde (MDA) formations, and enhanced superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and glutathione (GSH) content. Moreover, the CCl₄-induced elevations of pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 were markedly suppressed in the eckol-treated group. However, eckol enhanced the level of IL-10, a potent anti-inflammatory cytokine, and recruited CD11c⁺ dendritic cells into the liver tissues of CCl₄-treated mice. These results indicated that eckol has the protective effect on CCl₄-induced acute liver injury via multiple mechanisms including anti-apoptosis, anti-oxidation, anti-inflammation and immune regulation.

Effects of disodium cantharidinate on dendritic cells of patients with bladder carcinoma

The present study explored the effects of disodium cantharidinate (DC) on the peripheral blood-derived dendritic cells of patients with bladder carcinoma. The peripheral blood mononuclear cells from the 15 cases of urinary bladder carcinoma of middle and advanced stage were separated, and dendritic cells were prepared. The morphological changes of dendritic cells were observed. Flow cytometry was used to detect the expression levels of CD1a and CD83 on dendritic cell surface. MTT assay was utilized to measure the proliferation ability of allogeneic lymphocyte stimulated by DC. Annexin V-FITC/propidium iodide (PI) double staining flow cytometry method was carried out to detect cell apoptosis after treatment with DC. The changes in caspase-3 and PARP expression levels were investigated by western blot method. The high-dose DC resulted in a significant increase in the expressions of dendritic cell phenotyptic molecules CDla and CD83 as compared to control group. In addition, the proliferation index of allogenic lymphocyte stimulated by DC was significantly higher than that of control group. Moreover, MTT assay showed significant inhibition of the growth of BIU-87 cells. After 24 h of DC treatment, double staining flow cytometry confirmed the ability of DC to induce cell apoptosis. Further, western blot method showed a significant elevation of caspase-3 and PARP protein expression after DC treatment. In conclusion, DC treatment could induce dendritic cell maturation of patient with carcinoma of urinary bladder and promote its functional changes. Furthermore, DC was able to inhibit the proliferation of cell BIU-87 and also has the ability to induce cell apoptosis.

Acute Liver Damage Associated with Innate Immune Activation in a Small Nonhuman Primate Model of Hepacivirus Infection

Despite its importance in shaping adaptive immune responses, viral clearance, and immune-based inflammation, tissue-specific innate immunity remains poorly characterized for hepatitis C virus (HCV) infection due to the lack of access to acutely infected tissues. In this study, we evaluated the impact of natural killer (NK) cells and myeloid (mDCs) and plasmacytoid (pDCs) dendritic cells on control of virus replication and virus-induced pathology caused by another, more rapidly resolving hepacivirus, GB virus B (GBV-B), in infections of common marmosets. High plasma and liver viral loads and robust hepatitis characterized acute GBV-B infection, and while viremia was generally cleared by 2 to 3 months postinfection, hepatitis and liver fibrosis persisted after clearance. Coinciding with peak viral loads and liver pathology, the levels of NK cells, mDCs, and pDCs in the liver increased up to 3-fold. Although no obvious numerical changes in peripheral innate cells occurred, circulating NK cells exhibited increased perforin and Ki67 expression levels and increased surface expression of CXCR3. These data suggested that increased NK cell arming and proliferation as well as tissue trafficking may be associated with influx into the liver during acute infection. Indeed, NK cell frequencies in the liver positively correlated with plasma (R = 0.698; P = 0.015) and liver (R = 0.567; P = 0.057) viral loads. Finally, soluble factors associated with NK cells and DCs, including gamma interferon (IFN-γ) and RANTES, were increased in acute infection and also were associated with viral loads and hepatitis. Collectively, the findings showed that mobilization of local and circulating innate immune responses was linked to acute virus-induced hepatitis, and potentially to resolution of GBV-B infection, and our results may provide insight into similar mechanisms in HCV infection.

IMPORTANCE

Hepatitis C virus (HCV) infection has created a global health crisis, and despite new effective antivirals, it is still a leading cause of liver disease and death worldwide. Recent evidence suggests that innate immunity may be a potential therapeutic target for HCV, but it may also be a correlate of increased disease. Due to a lack of access to human tissues with acute HCV infection, in this study we evaluated the role of innate immunity in resolving infection with a hepacivirus, GBV-B, in common marmosets. Collectively, our data suggest that NK cell and DC mobilization in acute hepacivirus infection can dampen virus replication but also regulate acute and chronic liver damage. How these two opposing effects on the host may be modulated in future therapeutic and vaccine approaches warrants further study.

Intrahepatic Toll-Like Receptor 3 in Chronic HBV Infection Subjects: Asymptomatic Carriers, Active Chronic Hepatitis, Cirrhosis, and Hepatocellular Carcinoma

BACKGROUND

The entire disease spectrum of chronic HBV infection (CHB) includes asymptomatic carriers (AC), active chronic hepatitis (ACH), cirrhosis (Cir), and hepatocellular carcinoma (HCC). Previous study have demonstrated that the costimulation profiles from the livers of patients influenced immune responses and played various immunological roles in AC, ACH, Cir, and HCC. In addition, activation of TLR3 signaling in the liver may contribute to HBV clearance, although some HBV components are able to block TLR3 signaling and counteract HBV clearance through positive or negative feedback loops. Previous clinical studies have demonstrated that different TLR3 expressions are present in ACH patients, but no studies investigated the expression of TLR3 proteins in the livers of patients with AC, Cir, or HCC.

OBJECTIVES

This study investigated intrahepatic TLR3 expression throughout the entire disease spectrum of CHB patients and assessed the interrelations between TLR3 and costimulation proteins.

PATIENTS AND METHODS

Patients with ACH, Cir, HCC, and AC and healthy donors (HD) were recruited. TLR3 expression in the livers of patients were investigated using western blot analysis and immunohistochemistry. Correlations between TLR3 and costimulation proteins, including CD80, CD86, CD83, CD28, CTLA-4, CD40, and ICAM-1, were assessed.

RESULTS

The TLR3 protein in the ACH group tended toward reduction although the P Value of the comparison between the ACH group and HD group was not statistically significant. The TLR3 levels in the HCC, AC, and Cir groups were higher than those in the HD and ACH groups. TLR3 was not interrelated with all costimulation proteins in the DCs and T cells in all five groups. No group presented any interrelation between TLR3 and CD40, except the AC group.

CONCLUSIONS

The AC, HCC, and Cir patients displayed increased levels of the intrahepatic TLR3 protein compared to the HD and AC patients. Both activation of TLR3/INF-β signaling and inhibition of TLR3/INF-β signaling by HBV components influenced TLR3 expression in the AC, ACH, Cir, and HCC subjects. However, TLR3 signaling did not influence the expression of costimulatory protein in the ACH, Cir, or HCC patients. TLR3/ IFN-β signaling did influence immune responses in the livers of CHB patients.

Analysis of peripheral blood dendritic cells as a non-invasive tool in the follow-up of patients with chronic hepatitis C

Hepatitis C virus (HCV) has a high propensity to establish chronic infections. Failure of HCV-infected individuals to activate effective antiviral immune responses is at least in part related to HCV-induced impairment of dendritic cells (DCs) that play a central role in activating T cell responses. Although the impact of HCV on DC phenotype and function is likely to be more prominent in the liver, major HCV-induced alterations are detectable in peripheral blood DCs (pbDCs) that represent the most accessible source of DCs. These alterations include numerical reduction, impaired production of inflammatory cytokines and increased production of immunosuppressive IL10. These changes in DCs are relevant to our understanding the immune mechanisms underlying the propensity of HCV to establish persistent infection. Importantly, the non-invasive accessibility of pbDCs renders the analysis of these cells a convenient procedure that can be serially repeated in patient follow-up. Accordingly, the study of pbDCs in HCV-infected patients during conventional treatment with pegylated interferon and ribavirin indicated that restoration of normal plasmacytoid DC count may represent an additional mechanism contributing to the efficacy of the dual therapy. It also identified the pre-treatment levels of plasmacytoid DCs and IL10 as putative predictors of response to therapy. Treatment of chronic HCV infection is changing, as new generation direct-acting antiviral agents will soon be available for use in interferon-free therapeutic strategies. The phenotypic and functional analysis of pbDCs in this novel therapeutic setting will provide a valuable tool for investigating mechanisms underlying treatment efficacy and for identifying predictors of treatment response.

Indolamine 2,3-dioxygenase expression by monocytes and dendritic cell populations in hepatitis C patients

Dendritic cells (DCs) play an important role in the induction of the primary immune response to infection. DCs may express the tryptophan-catabolizing enzyme indolamine2,3-dioxygenase (IDO), which is an inducer of immune tolerance. Because there is evidence that chronic hepatitis C virus (HCV) infection leads to functional impairment of certain DC populations, we analysed IDO expression in DCs and monocytes from chronically infected and recovered HCV patients. The IDO1 and -2 expression was increased significantly in the monocytes of chronic HCV patients but, interestingly, not in those from recovered patients. The myeloid DCs from chronically infected HCV patients also showed enhanced IDO1 expression, while no change in either IDO1 or -2 was found for plasmacytoid DCs. Up-regulation of IDO1 gene expression was confirmed by the presence of enhanced kynurenine/tryptophan ratios in the plasma from chronic HCV patients. Increased IDO1 and -2 expression was also observed in monocytes from healthy donors infected with an adapted mutant of the HCV JFH-1 strain ex vivo, confirming a direct effect of HCV infection. These changes in IDO expression could be prevented by treatment with the IDO inhibitor 1-methyl tryptophan (1-mT). Furthermore, maturation of monocyte-derived DCs from chronically infected HCV patients, as well as well as monocyte-derived DCs infected ex vivo with HCV, was impaired, but this was reversed by 1-mT treatment. This suggests that IDO inhibitors may be used to treat chronic HCV patients in vivo, in conjunction with current therapies, or to activate DCs from patients ex vivo, such that they can be administered back as a DC-based therapeutic vaccine.

Dendritic cell maturation in HCV infection: altered regulation of MHC class I antigen processing-presenting machinery

BACKGROUND & AIMS

Modulation of dendritic cell (DC) function has been theorized as one of the mechanisms used by hepatitis C virus (HCV) to evade the host immune response and cause persistent infection.

METHODS

We used a range of cell and molecular biology techniques to study DC subsets from uninfected and HCV-infected individuals.

RESULTS

We found that patients with persistent HCV infection have lower numbers of circulating myeloid DC and plasmacytoid DC than healthy controls or patients who spontaneously recovered from HCV infection. Nonetheless, DC from patients with persistent HCV infection display normal phagocytic activity, typical expression of the class I and II HLA and co-stimulatory molecules, and conventional cytokine production when stimulated to mature in vitro. In contrast, they do not display the strong switch from immunoproteasome to standard proteasome subunit expression and the upregulation of the transporter-associated proteins following stimulation, which were instead observed in DC from uninfected individuals. This different modulation of components of the HLA class I antigen processing-presenting machinery results in a differential ability to present a CD8(+) T cell epitope whose generation is dependent on the LMP7 immunoproteasome subunit.

CONCLUSIONS

Overall, these findings establish that under conditions of persistent HCV antigenemia, HLA class I antigen processing and presentation are distinctively regulated during DC maturation.

Host Genetic Factors and Dendritic Cell Responses Associated with the Outcome of Interferon/Ribavirin Treatment in HIV-1/HCV Co-Infected Individuals

HIV-1/HCV co-infection is a significant health problem. Highly active antiretroviral treatment (HAART) against HIV-1 has proved to be fairly successful. On the other hand, direct acting antiviral drugs against HCV have improved cure rates but high cost and development of drug resistance are important concerns. Therefore PEGylated interferon (PEG-IFN) and ribavirin (RBV) still remain essential components of HCV treatment, and identification of host factors that predict IFN/RBV treatment response is necessary for effective clinical management of HCV infection. Impaired dendritic cell (DC) and T cell responses are associated with HCV persistence. It has been shown that IFN/RBV treatment enhances HCV-specific T cell functions and it is likely that functional restoration of DCs is the underlying cause. To test this hypothesis, we utilized an antibody cocktail (consisting of DC maturation, adhesion and other surface markers) to perform comprehensive phenotypic characterization of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in a cohort of HIV-1/HCV co-infected individuals undergoing IFN/RBV treatment. Our results show that pre-treatment frequencies of mDCs are lower in non-responders (NRs) compared to responders (SVRs) and healthy controls. Although, the treatment was able to restore the frequency of mDCs in NRs, it downregulated the frequency of CCR7⁺, CD54⁺ and CD62L⁺ mDCs. Pre-treatment frequencies of pDCs were lower in NRs and decreased further upon treatment. Compared to SVRs, NRs exhibited higher ratio of PD-L1⁺/CD86⁺ pDCs prior to treatment; and this ratio remained high even after treatment. These findings demonstrate that enumeration and phenotypic assessment of DCs before/during therapy can help predict the treatment outcome. We also show that before treatment, PBMCs from SVRs secrete higher amounts of IFN-γ compared to controls and NRs. Upon genotyping IFNL3 polymorphisms rs12979860, rs4803217 and ss469415590, we found rs12979860 to be a better predictor of treatment outcome. Collectively, our study led to identification of important correlates of IFN/RBV treatment response in HIV-1/HCV co-infected individuals.

Effects of costimulation on intrahepatic immunopathogenesis in patients with chronic HBV infection

Objective

Chronic HBV infection can lead to “immune tolerance” in asymptomatic carriers (ACs), “immune injury” in active chronic hepatitis (ACH) patients or “immune abnormality” in cirrhosis (Cir) and hepatocellular carcinoma (HCC) patients. Previous investigations reported that chronic hepatitis presented abnormal expression of costimulatory molecules. We investigated the costimulation profile in the liver of ACs and patients with ACH, Cir and HCC.

Methods

Patients with ACH, Cir and HCC, ACs and normal controls were recruited into the present study. The costimulation profiles and cytokines in the liver of patients were investigated by Western blotting, immunohistochemistry and real-time quantitative PCR. Correlations between serum alanime aminotransferase (ALT) levels, necroinflammation scores, cytokines and costimulatory proteins were assessed.

Results

The ACs presented decreased inflammatory and increased inhibitory costimulation, which was negatively correlated with inflammatory costimulatory proteins and ALT, whereas the ACH patients exhibited increased inflammatory costimulation and decreased inhibitory costimulation, which was correlated with increased ALT. The Cir patients showed both increased inhibitory and inflammatory costimulation. The HCC patients exhibited both decreased inhibitory and inflammatory costimulation.

Conclusion

Costimulation participates in intrahepatic immune responses, and plays important roles in immune tolerance, immune injury and immune abnormalities in patients with chronic HBV infection.

Electronic supplementary material

The online version of this article (doi:10.1007/s00011-013-0691-3) contains supplementary material, which is available to authorized users.

Relationship of TGF-β1 and Smad7 expression with decreased dendritic cell infiltration in liver gastrointestinal cancer metastasis

Immune responses and their modulation within the liver are critical to the outcome of liver malignancies. In late-stage tumors, secreted TGF-β promotes oncogenic functions and can confer tolerogenicity to some immune cells like DCs. The TGF-β signaling pathway is involved in the control of several biological processes, including immunosurveillance. The aim of the present study was to assess CD1a(+) and CD83(+) DCs and to evaluate the impact of TGF-β pathway on DCs maturation and distribution in the liver metastases from gastric and colorectal tumors. The percentage of CD83(+) DCs in the liver tissue, surrounding metastasis and in the metastasis-free liver was measured by flow cytometry, and TGF-β levels were assessed in the tissue supernatant from the peritumoral liver after mononuclear cell isolation and in the sera of the same patients. CD1a(+) and CD83(+) DCs were observed in the tumor stroma and border. Out of 73 patients, there was cytoplasmic reactivity: of TGF-β1 in 37 (50.7%); of Smad4 in 62 (84.9%); of Smad7 in 46 (63%), and of TGFβRII in 39 (53.4%) of the metastases. The TGF-β1 expression in tumor cell cytoplasm correlated with low CD1a(+) and low CD83(+) DCs infiltration. The tissue levels of TGF-β1, measured by ELISA in the supernatant were significantly increased in metastases than in normal liver. Using a two-color FACS analysis, we found that the percentage of HLA-DR(+) CD83(+) DCs in metastases was significantly decreased as compared with metastasis-free liver tissue. In conclusion, the positive and negative correlations between the mediators from the TGF-β pathway implied the existence of imbalance and suppression of this cytokine activity. The presence of increased TGF-β expression by immunohistochemistry in tumor cells was confirmed by detection of increased TGF-β tissue level in the supernatant from the tissue homogenate. The observation of low numbers of CD1a(+) and CD83(+) DCs in tumor stroma correlated with TGF-β overexpression in tumor cells, a fact that well documents the immunosuppressive role of TGF-β in metastasis development. The increased percentage of CD83(+) DCs in the peritumoral tissue supposes that there could be active recruitment or local differentiation of DCs in the metastasis border, but inside the tumor the immune cells recruitment and activity are suppressed by TGF-β and by other cytokines.

Blood dendritic cell frequency declines in idiopathic Parkinson's disease and is associated with motor symptom severity

The role of inflammation in Parkinson’s Disease (PD) is well appreciated, but its underlying mechanisms are still unclear. Our objective was to determine whether dendritic cells (DC), a unique type of migratory immune cells that regulate immunological response and inflammation have an impact on PD. In a case-control study including 80 PD patients and 80 age- and gender-matched healthy control subjects, the two main blood subsets of plasmacytoid and myeloid DC were defined by flow cytometry analysis. Clinical evaluation of subjects consisting of cognition and depression assessment was performed using the Mini Mental State Examination and the Beck Depression Inventory. The severity of motor symptoms was measured using the Unified Parkinson’s Disease Rating Scale-Part III. Comparison between patient and control DC measures and their relationships with clinical assessments were evaluated.The following main results were obtained: 1) the level of circulating DC (mainly the myeloid subset) was significantly reduced in PD patients in comparison with healthy controls; 2) after controlling for depressive and cognitive characteristics, the frequency of myeloid DC was confirmed as one of the independent determinants of PD; 3) the number of both myeloid and plasmacytoid DC was negatively associated with motor symptom severity. Overall, the decline of blood DC, perhaps due to the recruitment of immune cells to the site of disease-specific lesions, can be considered a clue of the immune alteration that characterizes PD, suggesting innovative exploitations of DC monitoring as a clinically significant tool for PD treatment. Indeed, this study suggests that reduced peripheral blood DC are a pathologically-relevant factor of PD and also displays the urgency to better understand DC role in PD for unraveling the immune system contribution to disease progression and thus favoring the development of innovative therapies ideally based on immunomodulation.

Divergent contributions of regulatory T cells to the pathogenesis of chronic hepatitis C

Hepatitis C virus, a small single-stranded RNA virus, is a major cause of chronic liver disease. Resolution of primary hepatitis C virus infections depends upon the vigorous responses of CD4(+) and CD8(+) T cells to multiple viral epitopes. Although such broad CD4(+) and CD8(+) T-cell responses are readily detected early during the course of infection regardless of clinical outcome, they are not maintained in individuals who develop chronic disease. Purportedly, a variety of factors contribute to the diminished T-cell responses observed in chronic, virus-infected patients including the induction of and biological suppression by CD4(+)FoxP3(+) regulatory T cells. Indeed, a wealth of evidence suggests that regulatory T cells play diverse roles in the pathogenesis of chronic hepatitis C, impairing the effector T-cell response and viral clearance early during the course of infection and suppressing liver injury as the disease progresses. The factors that affect the generation and biological response of regulatory T cells in chronic, hepatitis C virus-infected patients is discussed.

Dendritic cell biology in human cytomegalovirus infection and the clinical consequences for host immunity and pathology

Human cytomegalovirus (HCMV), a member of the herpesvirus family, establishes life-long persistence and latency after primary infection and can be reactivated later in life. In immunosuppressed patients, it is an important pathogen that can cause severe disease. HCMV is also thought to play a causative role in inflammatory diseases and cancer. The virus can infect different immune cells, including dendritic cells (DCs) and can take advantage of host immune functions to avoid immune recognition. These characteristics have sparked major interest in understanding HCMV and its interaction with immune cells and their relevance to disease pathogenesis. In this review, we focus on the complex host-pathogen relationship between HCMV and DCs, including the persistence of the virus in these cells, their function in the immune response to HCMV infection and the potential clinical consequences of HCMV infection in DCs.

Dendritic cells, regulatory T cells and the pathogenesis of chronic hepatitis C

Hepatitis C virus (HCV) is a small, enveloped RNA virus and a major cause of chronic liver disease. Resolution of primary HCV infections depends upon the vigorous responses of CD4⁺ and CD8⁺ T cells to multiple viral epitopes. Although such broad-based responses are readily detected early during the course of infection regardless of clinical outcome, they are not maintained in individuals who develop chronic disease. Ostensibly, a variety of factors contribute to the diminished T cell responses observed in chronic, HCV-infected patients including impaired dendritic cell function and the induction of CD4⁺FoxP3⁺ regulatory T cells. Overwhelming evidence suggests that the complex interaction of dendritic cells and regulatory T cells plays a critical role in the pathogenesis of chronic hepatitis C.

High TNF-alpha and IL-8 levels predict low blood dendritic cell counts in primary cytomegalovirus infection

BACKGROUND

In vitro studies suggest that human cytomegalovirus (CMV) modulates the functions of dendritic cells (DCs). However, there are limited data on DC homeostasis in CMV-infected patients.

OBJECTIVES

The aim of this study was to characterize circulating DCs and plasma cytokine levels in immunocompetent patients with primary, symptomatic CMV infections.

STUDY DESIGN

The study population consisted of 14 patients suffering of CMV mononucleosis and 14 healthy volunteers (11 CMV-seropositive and 3 CMV-seronegative subjects) included as controls. Peripheral blood mononuclear cells were isolated and used to characterize DCs and to quantify CMV in the blood. Plasma levels of pro-inflammatory and anti-inflammatory cytokines were also measured.

RESULTS

We observed that patients who were developing CMV mononucleosis presented lower myeloid and plasmacytoid DC counts in peripheral blood compared with healthy controls. We also noted elevated levels of inflammatory mediators, of which tumor necrosis factor-α (TNF-α)-which activates DCs and endothelial cells-was the highest. Notably, the decrease in blood DCs correlated with high TNF-α and IL-8 levels by a hyperbolic function.

CONCLUSIONS

Our results suggest that increased levels of inflammatory factors facilitate alterations in DC homeostasis during primary CMV infection, which may contribute to viral-induced modulation of host immunity.

Peripheral blood dendritic cells in alcoholic and autoimmune liver disorders

Little is known about effects of alcohol consumption on dendritic cell (DC) function and resultant immune response. However, quantitative and qualitative disturbances of DCs are speculated to be involved in alcohol-related as well as in other liver pathology. The present study aimed to evaluate changes in circulating DC subsets in alcoholic liver disease (N = 43), autoimmune hepatitis (N = 26) and primary biliary cirrhosis (N = 20). DCs isolated from the peripheral blood of recruited participants were stained with monoclonal antibodies against blood dendritic cell antigens (BDCAs) and estimated using the flow cytometry. Myeloid DCs were defined as BDCA-1(+)/CD19(-) cells, and lymphoid DCs as BDCA-2(+)/CD123(+) cells. Total numbers of circulating DCs in subjects with some liver diseases were markedly lower than in the healthy participants (p = 0.03). There was a significantly lower percentage of circulating BDCA-2(+)/CD123(+) (p = 0.02), and a tendency for the percentage of circulating BDCA-1(+)/CD19(-) cells to decrease in patients with liver diseases compared to the controls (p = 0.09). These results may suggest that decreased numbers of DCs may be responsible for reduced adaptive immune responses and increased susceptibility to infections and cancer development observed in patients exposed to alcohol. Moreover, numerical abnormalities of DCs may contribute to the breakdown of self-tolerance, a feature of autoimmune diseases.

The tug-of-war between dendritic cells and human chronic viruses

The human immune system is under constant challenge from many viruses, some of which the body is successfully able to clear. Other viruses have evolved to escape the host immune responses and thus persist, leading to the development of chronic diseases. Dendritic cells are professional antigen-presenting cells that play a major role in both innate and adaptive immunity against different pathogens. This review focuses on the interaction of different chronic viruses with dendritic cells and the viruses' ability to exploit this critical cell type to their advantage so as to establish persistence within the host.

α-Fetoprotein impairs activation of natural killer cells by inhibiting the function of dendritic cells

α-Fetoprotein (AFP) is a tumour-associated antigen in hepatocellular carcinoma (HCC). The biological properties of AFP have been identified in its regulatory effects on immune responses of T cells and B cells. However, AFP effects on natural killer (NK) cells are still unclear. In this study, we examined the immunoregulation of AFP on NK activity. The cytolytic activity against K562 cells and Huh7 cells of NK cells co-cultured with AFP-treated dendritic cells (DCs) (AFP-DCs) was lower than that with albumin-treated DCs (Alb-DCs). Direct addition of AFP to NK cells did not alter the cytolytic activity of NK cells. Adding AFP inhibited the interleukin (IL)-12 production of DCs after stimulation with lipopolysaccharide (LPS) [Toll-like receptor (TLR)-4 ligand], or Poly(I:C) (TLR-3 ligand), but not IL-18 production. The mRNAs of IL-12p35 and IL-12p40 were significantly inhibited in AFP-DCs compared with Alb-DCs, but those of TLR-4 or TLR-3 were not. Transwell experiments revealed that soluble factors derived from DCs played roles in inhibition of the ability of activating NK cells by AFP-DCs. Adding the neutralizing antibody of IL-12 to NK cells co-cultured with Alb-DCs resulted in a decrease of cytolytic activity to the levels of NK cells co-cultured with AFP-DCs. Adding IL-12 to NK cells co-cultured with AFP-DCs resulted in an increase of cytolytic activity to the levels of NK cells co-cultured with Alb-DCs. These demonstrated that the impairment of IL-12 production from AFP-DCs resulted in inhibition of the ability of the activation of NK cells by DCs, and thus suggests a role of AFP in HCC development.

Semi mature blood dendritic cells exist in patients with ductal pancreatic adenocarcinoma owing to inflammatory factors released from the tumor

Background

Much evidence exists regarding the fact that blood DCs, both myeloid DCs (MDCs) and plasmacytoid DCs (PDCs), are negatively affected in different types of cancer, with both reduced numbers and impaired functionality. Functional impairment of DCs in patients with pancreatic ductal adenocarcinoma (PDAC), may contribute to the poor clinical outcome. The aim of this study was to examine the effects PDAC had on blood DCs and elucidate the underlying mechanism responsible for the DC impairment.

Methodology/Principal Findings

We examined the systemic influence PDAC exerted on blood DCs by ex vivo measuring numerous activation and maturation markers expressed on these cells. Furthermore, the effect patient plasma and the inflammatory factors CXCL8 and PGE₂ had on purified MDCs and PDCs from healthy donors was assessed and compared to the DCs existing in PDAC patients. We found a partial maturation of the blood MDCs and PDCs in PDAC patients with significantly enhanced expression of CD83, CD40, B7H3, PDL-1, CCR6, and CCR7 and decreased expression of ICOSL, and DCIR. These changes lead to impairment in their immunostimulatory function. Furthermore, chronic pancreatitis gave rise to DCs with similar semi-mature phenotype as seen in PDAC. Low expression of ICOSL was associated with poor prognosis. We found that the mechanism underlying this semi-maturation of DCs was inflammatory factors existing in the PDAC patients' plasma. Of note, PGE₂, which is elevated PDAC patient plasma, was one contributing factor to the changes seen in MDCs and PDCs phenotype.

Conclusion/Significance

Our findings point to a role for the systemic inflammation in transforming blood MDCs and PDCs into semi-mature cells in PDAC patients and we show a correlation between maturation status and clinical outcome. Thus, means to preserve a functional blood DC compartment in PDAC patients by diminishing the inflammation could facilitate their ability to control the disease and improve survival.

A look behind closed doors: interaction of persistent viruses with dendritic cells

Persistent infections with HIV, hepatitis B virus and hepatitis C virus are major causes of morbidity and mortality worldwide. As sentinels of the immune system, dendritic cells (DCs) are crucial for the generation of protective antiviral immunity. Recent advances in our understanding of the role of DCs during infection with these viruses provide insights into the mechanisms used by these viruses to exploit DC function and evade innate and adaptive immunity. In this Review we highlight the current knowledge about the interaction between DCs and these viruses and the underlying mechanisms that might influence the outcome of viral infections.

Pancreatic adenocarcinoma exerts systemic effects on the peripheral blood myeloid and plasmacytoid dendritic cells: an indicator of disease severity?

BACKGROUND

Dendritic cells (DCs) isolated from tumor bearing animals or from individuals with solid tumors display functional abnormalities and the DC impairment has emerged as one mechanism for tumor evasion from the control of the immune system. Ductal pancreatic adenocarcinoma (PDAC), the most common pancreatic cancer, is recognized as a very aggressive cancer type with a mortality that almost matches the rate of incidence.

METHODS

We examined the systemic influence ductal pancreatic adenocarcinoma (PDAC) exerted on levels of peripheral blood DCs and inflammatory mediators in comparison to the effects exerted by other pancreatic tumors, chronic pancreatitis, and age-matched controls.

RESULTS

All groups examined, including PDAC, had decreased levels of myeloid DCs (MDC) and plasmacytoid DCs (PDC) and enhanced apoptosis in these cells as compared to controls. We found elevated levels of PGE2 and CXCL8 in subjects with PDAC, and chronic pancreatitis. Levels of these inflammatory factors were in part restored in PDAC after tumor resection, whereas the levels of DCs were impaired in the majority of these patients approximately 12 weeks after tumor removal. Our results prove that solid pancreatic tumors, including PDAC, systemically affect blood DCs. The impairments do not seem to be tumor-specific, since similar results were obtained in subjects with chronic pancreatitis. Furthermore, we found that PDAC patients with a survival over 2 years had significant higher levels of blood DCs compared to patients with less than one year survival.

CONCLUSIONS

Our findings points to the involvement of inflammation in the destruction of the blood MDCs and PDCs. Furthermore, the preservation of the blood DCs compartment in PDAC patients seems to benefit their ability to control the disease and survival.

Host immunity influences disease progression and antiviral efficacy in humans infected with hepatitis B virus

Hepatitis B virus (HBV) infection can lead to several severe liver diseases, including hepatitis, cirrhosis and hepatocellular carcinoma, although the underlying mechanisms responsible for the clinical outcome have not been well characterized. In this review, we retrospectively examine the history of immunological responses to HBV infection and summarize the current understanding of innate and adaptive immunity in the context of HBV-associated liver disease. Recent data indicate that the interaction between HBV and the host immune response not only substantially drives disease progression, but also significantly influences antiviral efficacy in HBV-infected individuals. Advances in the field have provided insight into the immunopathology of HBV infection. Based on the characteristics of host immune responses in patients with HBV infection, a 'climbing slope hypothesis' is proposed to suggest that therapeutic strategies aimed at modulating the immune activity of the host may represent a complementary approach to antiviral drug treatment for the management of chronically HBV-infected patients.

Clinical response to interferon-beta-1a may be linked to low baseline circulating BDCA1 myeloid dendritic cells Differential role of circulating dendritic cells and CD4+ regulatory T-cells in relapsing-remitting multiple sclerosis: a 1-year longitudinal study

Many variables with association with better response to interferon-beta-1a (IFNbeta-1a) have been described, but none has yet been shown to be predictive of clinical response. In this real-life observational 1-year longitudinal study of 23 relapsing-remitting multiple sclerosis (RRMS) patients treated with subcutaneous IFNbeta-1a, we have shown a lower proportion of circulating myeloid dendritic cells (mDCs) than in healthy controls at baseline. Both univariate (Kaplan-Meier) and multivariate (Cox regression) analyses were conducted to determine which variables (age, sex, baseline EDSS, MS relapse rates 1 year and 2 years before initiating IFNbeta-1a, mDCs and plasmacytoid (pDCs) subsets, activated and regulatory CD4(+) T-cells (T(Reg))) were associated with clinical response to IFNbeta-1a. During 1 year of treatment, we observed a shift towards lower proportions of CD123(+) pDCs expression and higher numbers and function of the T(Reg). Univariate analysis disclosed that MS activity was significantly associated with baseline BDCA1(+) mDCs below < or = 0.4% (p<0.0025). Cox model analysis revealed that baseline BDCA1(+) mDCs was the most closely associated factor with MS activity on IFN treatment during the 1-year follow-up (p<0.01). A better understanding of the rules that govern the T(Reg)-DC relationship will enable scientists to better manage the immune response in MS patients.

Dendritic cells and chronic hepatitis B

The immune function disorders in patients with chronic hepatitis B (CHB) lead to persistent damage of their liver cells and have impact on the ability to clear the virus. Dendritic cells (DCs) are the most important antigen-presenting cells in body. They help to generate sufficient immune response by the invasion of pathogens. The quantity and functionality of DCs directly correlate with the normal function of the host's immune response. Not only can DCs be resistant to the virus, but also serve as vehicles for the virus to spread and escape immune injury. Therefore the research on DCs and improving their function under the state of CHB is quite significant.

Immunology of hepatitis B and hepatitis C virus infections

Hepatitis B (HBV) and hepatitis C (HCV) viruses are the two major causes of chronic liver inflammation worldwide. Despite distinct virologic features, both viruses are preferentially hepatotropic, not directly cytopathic, and elicit liver diseases that share several aspects of their natural history. HBV and HCV infections also share some important features of the adaptive antiviral immune response. We describe the innate immune response in the early phase following infection, and how these early events may influence the development of the adaptive immune response in these two important viral infections. The mechanisms by which high levels of viral antigens, liver immunological features, the presence of regulatory T cells and impaired dendritic cell functions may maintain the HBV- and HCV-specific immunological failure, characteristic of chronic hepatitis B and C patients, are also evaluated.

Severe dendritic cell perturbation is actively involved in the pathogenesis of acute-on-chronic hepatitis B liver failure

BACKGROUND/AIMS

Functionally impaired dendritic cells (DCs) play important roles in suppressing host immune responses and facilitating viral persistence in chronic hepatitis B virus (HBV) infection. However, little is known regarding the status of intrahepatic DCs in HBV infection.

METHODS

Based on availability, 11 recipient liver samples were obtained from acute-on-chronic hepatitis B liver failure (ACHBLF) patients who had undergone liver transplantation. The frequencies, phenotypes, and functions of intrahepatic DC subsets were analyzed.

RESULTS

Both plasmacytoid dendritic cells (pDCs) and myeloid dendritic cells (mDCs) extensively infiltrated the liver of the ACHBLF patients and expressed mature phenotypes therein. In particular, activated hepatic pDCs produced interferon (IFN)-alpha, which subsequently induced interleukin (IL)-12 and IL-10 production via toll-like receptor-9 ligation in liver-infiltrating lymphocytes cultured in vitro. However, blockade of IFN-alpha production significantly reduced the cytokine production of the LILs. Further, a significantly low frequency of peripheral pDCs and highly reduced IFN-alpha production were observed in a large cohort of the ACHBLF patients, particularly in the non-survivors. Moreover, a persistently upregulated expression of hepatic IFN-alpha-associated genes was observed in the ACHBLF patients during disease progression.

CONCLUSIONS

Activated pDCs accumulated in large numbers in the liver of the ACHBLF patients and regulated local immune responses in chronic HBV infection.

Changes in frequency and phenotype of circulating CD11c+ myeloid dendritic cells in patients with chronic hepatitis B

AIM: To investigate the frequency and phenotype of circulating myeloid dendritic cells (mDCs) in patients with persistent hepatitis B virus (HBV) infection.

METHODS: Peripheral blood was collected from 28 chronic hepatitis B patients and 21 healthy blood donors (used as controls). CD11c⁺ mDCs were isolated by immunomagnetic selection. Flow cytometry was used to analyze the frequency of circulating CD11c⁺ mDCs and costimulatory molecules CD80 and CD86 on freshly isolated mDCs.

RESULTS: The frequency of peripheral mDCs in patients with chronic HBV infection was significantly decreased as compared with that in the healthy controls (0.38% ± 0.61% vs 0.77% ± 0.56%, P < 0.05). Respectively, mDCs frequency inversely was correlated with ALT levels (r = -0.374, P < 0.05) and HBV DNA level (r = -0.435, P < 0.05). Statistic differences of the mDCs frequency also existed among patients with different liver inflammatory levels. Both CD80 and CD86 expression on freshly isolated mDCs surface were lower; however, CD86 expression in the patients was relatively higher than that in the control (45.26% ± 21.54% vs 18.71% ± 10.93%, P < 0.05).

CONCLUSION: The percentage of CD11c⁺ mDCs decreases but its CD80 and CD86 expression levels are not impaired in chronic HBV patients. Serum HBV DNA load and liver inflammatory level may have some influences on the percentage of peripheral mDCs.

Altered chemotactic response of myeloid and plasmacytoid dendritic cells from patients with chronic hepatitis C: role of alpha interferon

Dendritic cell (DC) frequencies in the blood of patients with chronic hepatitis C virus (HCV) infection have been shown to be reduced significantly compared with those in healthy individuals. There is a further reduction of circulating myeloid DCs (MDCs) and plasmacytoid DCs (PDCs) in HCV patients receiving alpha interferon (IFN-alpha)-based antiviral therapy. Altered homing behaviour of DCs may be a possible mechanism for their 'loss' in peripheral blood in these clinical conditions. Systemic chemokine levels were measured by ELISA. Phenotypes and migratory properties of MDCs and PDCs from HCV patients were analysed by flow cytometry and chemotaxis assay. Compared with healthy controls, HCV patients had increased serum levels of inflammatory and constitutively expressed chemokines. Spontaneously generated MDCs from HCV patients were less mature, and both MDCs and PDCs showed intrinsic activation of receptors for inflammatory chemokines, thus suggesting an increased propensity to migrate towards inflammatory sites. IFN-alpha treatment in vitro induced MDC maturation and skewed the migratory response of both MDCs and PDCs towards chemokines expressed constitutively in secondary lymphoid organs. In conclusion, our results hint at altered homing behaviour of DCs during chronic HCV infection. IFN-alpha therapy may redirect DC migration from inflamed hepatic portal areas towards secondary lymphoid tissue.

Entecavir up-regulates dendritic cell function in patients with chronic hepatitis B

AIM

To investigate the in vitro effect of entecavir (ETV) on the function of dendritic cells (DCs) derived from chronic hepatitis B (CHB) patients.

METHODS

Mononuclear cells were isolated from peripheral blood of patients with CHB. DCs were incubated with RPMI-1640 medium supplemented with fetal bovine serum, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF). DCs were treated with or without ETV on the fourth day. Cell surface molecules, including CD1a, CD80, CD83 and HLA-DR, were assessed by flow cytometry. Concentrations of IL-6 and IL-12 in the supernatant were assayed by enzyme-linked immunosorbent assay (ELISA). The ability of the generated DCs to stimulate lymphocyte proliferation was observed.

RESULTS

Compared with CHB control group, the expression levels of CD1a (29.07 +/- 3.20 vs 26.85 +/- 2.80), CD83 (25.66 +/- 3.19 vs 23.21 +/- 3.10), CD80 (28.00 +/- 2.76 vs 25.75 +/- 2.51) and HLA-DR (41.96 +/- 3.81 vs 32.20 +/- 3.04) in ETV-treated group were higher (P < 0.05). ETV-treated group secreted significantly more IL-12 (157.60 +/- 26.85 pg/mL vs 132.60 +/- 22.00 pg/mL (P < 0.05) and had a lower level of IL-6 in the culture supernatant (83.05 +/- 13.88 pg/mL vs 93.60 +/- 13.61 pg/mL, P < 0.05) than CHB control group. The ability of DCs to stimulate the proliferation of allogeneic lymphocytes was increased in ETV-treated group compared with CHB control group (1.53 +/- 0.09 vs 1.42 +/- 0.08, P < 0.05).

CONCLUSION

Entecavir can enhance the biological activity of DCs derived from CHB patients.

Response to interferon-alpha treatment correlates with recovery of blood plasmacytoid dendritic cells in children with chronic hepatitis B

BACKGROUND/AIMS

To investigate whether dendritic cell changes are associated with the efficacy of interferon-alpha treatment we longitudinally analyzed circulating dendritic cells in children chronically infected with hepatitis B virus (HBV) undergoing interferon-alpha treatment.

METHODS

Thirty-one children with chronic hepatitis B (CHB) received interferon-alpha antiviral treatment for 52 weeks. Myeloid and plasmacytoid dendritic cell (pDCs) frequency and function were analyzed at weeks 0, 2, 12, 24, 36 and 52 in 22 CHB patients.

RESULTS

All patients exhibited an initially rapid decrease of circulating pDC numbers and CpG-induced endogenous interferon-alpha production within 2 weeks of interferon-alpha treatment. Subsequently, all responders displayed a continuous increase of both pDC numbers and function peaking around week 12. These responses were consequently accompanied by viral clearance, hepatitis B e antigen seroconversion, and the improvement of circulating myeloid dendritic cells and type 1T helper cytokine levels. However, non-responders lacked these sequential responses compared with responders.

CONCLUSIONS

pDCs may actively correlate with interferon-alpha therapy-induced viral clearance in pediatric patients with CHB. The recovery of blood pDC number and function may represent a prognostic marker for favourable response to interferon-alpha treatment in chronic hepatitis B.

Effects of lamivudine on the function of dendritic cells derived from patients with chronic hepatitis B virus infection

AIM: To investigate if the nucleoside analogue lamivudine (LAM), a potent inhibitor of HBV replication, could restore the function of dendritic cells derived from patients with chronic hepatitis B (CHB) in an Asian population.

METHODS: Dendritic cells (DCs) derived from mononuclearcytes of patients with chronic HBV infection were cultured in the presence of IL-4, granulocyte-macrophage colony-stimulating factors (GM-CSF) and gradient concentrations of LAM (0-2 mmol/L). Cell morphology was observed under light microscopy. Cell surface molecules, including HLA-DR, CD80, CD83, and CD1α, were analyzed with flow cytometry. The concentrations of IL-6 and IL-12 in the supernatant were assayed by ELISA. T cell proliferation was assayed by methyl thiazolyl tetrazolium (MTT).

RESULTS: The expression of CD1α on DC treated with 0.5 mmol/L LAM (LAM-DC 0.5 mmol/L) was significantly higher than that of DC untreated with LAM (54.1 ± 4.21 vs 33.57 ± 3.14, P < 0.05), and so was the expression of CD83 (20.24 ± 2.51 vs 12.83 ± 2.12, P < 0.05) as well as the expression of HLA-DR (74.5 ± 5.16 vs 52.8 ± 2.51, P < 0.05). Compared with control group, LAM-DC group (0.5 mmol/L) secreted significantly more IL-12 (910 ± 91.5 vs 268 ± 34.3 pg/mL, P < 0.05), had lower levels of IL-6 in the culture supernatant (28 ± 2.6 vs 55 ± 7.36 pg/mL, P < 0.05), markedly enhanced the stimulatory capacity in the allogeneic mixed leukocyte reaction (MLR) (1.87 ± 0.6 vs 1.24 ± 0.51, P < 0.05).

CONCLUSION: The lower expression of phenotypic molecules and impaired allogeneic mixed lymphocyte reaction function of dendritic cells derived from patients with HBV infection could be restored in vitro by incubation with LAM.

Decrease and dysfunction of dendritic cells correlate with impaired hepatitis C virus-specific CD4+ T-cell proliferation in patients with hepatitis C virus infection

Through the production of stimulatory and suppressive cytokines, dendritic cells (DCs) regulate virus-specific immune responses that are crucial to virus eradication. To explore a possible role of DCs in the persistence of hepatitis C virus (HCV) infection, in this study we analysed peripheral blood DCs (PBDCs) in patients with chronic hepatitis C (CHC) compared with those in both healthy seronegative (HSN) controls and a group of subjects who had spontaneously resolved infection, defined as healthy HCV-seropositive (HSP), and we evaluated the relationships between PBDCs and HCV-specific CD4(+) T-cell reactivity. The number of PBDCs, their immunophenotype and expression of regulatory cytokines were evaluated by flow cytometry on whole-blood samples. HCV-specific CD4(+) T-cell activation, proliferation and cytokine production were evaluated in cultures of peripheral blood mononuclear cells (PBMCs) stimulated in vitro with HCV peptides. We found that PBDCs from CHC subjects were numerically reduced and showed lower interleukin-12 (IL-12) and higher IL-10 expression than those from HSN controls. PBDCs from HSP subjects were similar to those from HSN controls. HCV-specific CD4(+) T-cell proliferation was less frequent and vigorous in CHC than in HSP patients and was directly related to the number of PBDCs and their IL-12 production but inversely related to their IL-10 production. Taken together, these results seem to suggest that cytokines of DC origin contribute to the regulation of HCV-specific immunity in CHC patients and indicate that PBDCs may represent a novel non-invasive tool for immune monitoring of these patients.

Engulfment of apoptotic cells expressing HCV proteins leads to differential chemokine expression and STAT signaling in human dendritic cells

In the majority of cases, infection with hepatitis C virus (HCV) becomes chronic and is often associated with impaired innate and adaptive immune responses. The mechanisms underlying viral persistence and lack of protective immunity are poorly understood. Considering that dendritic cells (DCs) play critical roles in initiating and modulating immune responses, we explored the effect of HCV proteins on DC gene and protein expression, phenotype, and function. Human DCs were generated following plastic adherence of monocytes and culture with granulocyte-macrophage colony-stimulating factor and interleukin-4 (IL-4) from normal subjects. Autologous nonadherent peripheral blood mononuclear cells were infected with vaccinia constructs expressing various HCV proteins (core-E1, NS5A, NS5B) or an irrelevant protein beta-galactosidase (beta-gal) as the control, induced to undergo apoptosis, then co-cultured with DCs. Between 2% and 10% of the genes probed in a cDNA nylon array were differentially regulated within DCs that had engulfed HCV proteins. In particular, the presence of intracellular NS5A led to increased transcriptional and protein expression of IL-8 (CXCL-8), a chemokine with proinflammatory and anti-interferon properties, and impaired interferon induction of signal transducers and activators of transcription 1 (STAT1) serine and tyrosine and STAT2 tyrosine phosphorylation.

CONCLUSION

These data provide novel mechanisms by which HCV subverts antiviral host immunity.

In vitro effect of entecavir on the function of dendritic cells derived from chronic hepatitis B patients

AIM: To investigate the effect of entecavir (ETV) on the function of dendritic cells (DC) derived from patients with chronic hepatitis B (CHB) in vitro.

METHODS: Peripheral blood mononuclear cells were isolated from CHB patients and healthy controls. After proliferation under induction, the cells were cultured by routine method. Then ETV was added to co-incubate with the cells on the 4^th day. On day 8, DC were collected for the detection of phenotypes and mixed lymphocytic reactions.

RESULTS: After 8 d of cultivation, the differentiation of DC in the healthy controls was better than that in ETV-treated group, while ETV-treated group had a better differentiation than CHB group. In comparison with those in the healthy controls, the levels of CD1a (35.73 ± 3.12 vs 62.31 ± 5.22), CD80 (28.19 ± 1.64 vs 45.38 ± 3.10), CD83 (22.24 ± 2.14 vs 40.63 ± 7.21) and HLA-DR (36.74 ± 0.98 vs 56.05 ± 3.89) expression were significantly decreased in CHB group (all P < 0.01). However, the levels of CD83 (27.41 ± 9.23 vs 22.24 ± 2.14, P < 0.05), CD80 (32.67 ± 7.82 vs 28.19 ± 1.64, P < 0.05) and HLA-DR (40.84 ± 5.57 vs 36.74 ± 0.98, P < 0.01) expression were markedly increased in ETV-treated group as compared with those in CHB group. The capacity to stimulate proliferation of the allogeneic lymphocytes in ETV-treated group was higher than that in CHB group (1.53 ± 0.09 vs 1.45 ± 0.12, P < 0.05).

CONCLUSION: Entecavir can enhance the biological activity of DC derived from CHB patients and play an indirect antivirus function by regulating the host's immune system.

Chronic alcohol consumption is associated with changes in the distribution, immunophenotype, and the inflammatory cytokine secretion profile of circulating dendritic cells

BACKGROUND

Alcoholism is frequently associated with altered immune responses, limited information being available on its effects on dendritic cells (DC). In the present study we analyze the effects of chronic alcoholism on circulating DC.

METHODS

For the first time we studied the numerical distribution of DC in peripheral blood (PB), their immunophenotype, and their ex vivo pattern of spontaneous cytokine secretion, in chronic alcoholic patients without liver disease (AWLD group; n=17) and active ethanol (EtOH) intake, as well as in subjects with alcohol liver cirrhosis (ALC group; n=21).

RESULTS

A significantly decreased HLADR expression and an increased reactivity for CD123 was observed on PB DC from AWLD patients; additionally, increased secretion of interleukin (IL) 1beta, IL6, IL12, and tumor necrosis factor-alpha (TNFalpha) by DC was also noted in this group. Conversely, patients with ALC and at least 1 year of alcohol withdrawal (ALCAW group) showed a decreased number of total circulating DC, whereas ALC patients with active EtOH intake (ALCET group) had an abnormally low production of IL1beta and TNFalpha by PB DC.

CONCLUSION

Chronic alcoholism in the absence of liver disease is associated with an increased secretion of inflammatory cytokines by PB DC, whereas ALCAW and ALCET patients show decreased numbers of circulating DC and reduced secretion of these cytokines, respectively.

Increased infiltration of intrahepatic DC subsets closely correlate with viral control and liver injury in immune active pediatric patients with chronic hepatitis B

The roles of functionally impaired dendritic cells (DCs) in natural history of chronic hepatitis B (CHB) are unknown. We therefore characterized circulating DC subsets in 15 immune tolerant (IT) and 31 immune active (IA) HBV-infected children. Additionally, intrahepatic DC subsets were also analyzed in 4 IT and 9 IA individuals. The results showed that circulating DC subset numbers were decreased, but the intrahepatic DC counts were concomitantly increased in IA patients versus IT patients or healthy children. This results in the reduction of overall IFN-alpha but not IL-12 production by peripheral blood mononuclear cells of IA patients, although the capacity of single DC in producing cytokines was unchanged in these children. Moreover, there is a significantly inverse correlation of intrahepatic DC subsets with plasma HBV load and a positive correlation with serum ALT levels. These findings suggest that the increased infiltration of intrahepatic DC subsets may participate in the local antiviral immune response in pediatric patients with CHB.

Favorable effect of adefovir on the number and functionality of myeloid dendritic cells of patients with chronic HBV

In patients with chronic hepatitis B virus (HBV), 2 predominant precursor dendritic cell (DC) subtypes, the myeloid dendritic cell (mDC) and the plasmacytoid dendritic cell (pDC), were recently found to be functionally impaired. HBV DNA was found to be present in the DC subtypes, but no viral replication could be detected. The question remains whether simply the presence of the virus and viral proteins causes this dysfunction of DCs. To address this issue, the effect of viral load reduction resulting from treatment with the nucleotide analogue adefovir dipivoxil on the number and functionality of circulating DCs was studied during 6 months of treatment. Treatment resulted in a mean 5 log(10) decrease in the viral load and normalization of alanine aminotransferase within 3 months. The number of mDCs, but not of pDCs, increased significantly over 6 months of treatment to a level comparable to that of uninfected healthy controls. The allostimulatory capacity of isolated and in vitro matured mDCs increased significantly after 3 months of treatment. Accordingly, mDCs exhibited an increased capacity to produce tumor necrosis factor alpha and interleukin-12 after 3-6 months of treatment. There was no change in interferon alpha production by pDCs during treatment. In conclusion, adefovir treatment results in an improvement in the number and functionality of mDCs, but not of pDCs. Our findings provide clues for the reasons why current antiviral therapy does not lead to consistently sustained viral eradication.