Expression levels of CD28, CTLA-4, PD-1 and Tim-3 as novel indicators of T-cell immune function in patients with chronic hepatitis B virus infection

Differences in the intrahepatic expression of immune checkpoint molecules on T cells and natural killer cells in chronic HBV patients

Background

Patients with chronic hepatitis B virus (HBV) infection are characterized by impaired immune response that fails to eliminate HBV. Immune checkpoint molecules (ICMs) control the amplitude of the activation and function of immune cells, which makes them the key regulators of immune response.

Methods

We performed a multiparametric flow cytometry analysis of ICMs and determined their expression on intrahepatic lymphocyte subsets in untreated and treated patients with HBV in comparison with non-pathological liver tissue.

Results

The liver of untreated HBV patients exhibited a high accumulation of PD-1+CD8+ T cells, while the frequencies of 4-1BB+ T cells, 4-1BB+ natural killer (NK) cells, and TIM-3+CD8+ T cells were the highest in the chronic hepatitis phase. Our findings showed that the HBeAg status is linked to a distinct immune phenotype of intrahepatic CD8+ T cells and NK cells characterized by high expression of ICMs, particularly 4-1BB. Importantly, antiviral treatment partially restored the normal expression of ICMs. Finally, we described important differences in ICM expression between intrahepatic and circulating NK cells in HBV patients.

Conclusions

Our study shows clear differences in the intrahepatic expression of ICMs on NK cells and T cells in chronic HBV patients depending on their clinical stage.

Elimination of the hepatitis B virus: A goal, a challenge

The hepatitis B elimination is a goal proposed by the WHO to be achieved by 2030 through the adoption of synergistic measures for the prevention and chronic HBV infection treatment. Complete cure is characterized by the HBV elimination from the body and is the goal of the chronic hepatitis B treatment, which once achieved, will enable the hepatitis B elimination. This, today, has been a scientific challenge. The difficulty in achieving a complete cure is due to the indefinite maintenance of a covalently closed episomal circular DNA (cccDNA) reservoir and the maintenance and persistence of an insufficient and dysfunctional immune response in chronically infected patients. Among the measures adopted to eliminate hepatitis B, two have the potential to directly interfere with the virus cycle, but with limited effect on HBV control. These are conventional vaccines-blocking transmission and antiviral therapy-inhibiting replication. Vaccines, despite their effectiveness in protecting against horizontal transmission and preventing mother-to-child vertical transmission, have no effect on chronic infection or potential to eliminate the virus. Treatment with antivirals suppresses viral replication, but has no curative effect, as it has no action against cccDNA. Therapeutic vaccines comprise an additional approach in the chronic infection treatment, however, they have only a modest effect on the immune system, enhancing it temporarily. This manuscript aims to address (1) the cccDNA persistence in the hepatocyte nucleus and the immune response dysfunction in chronically infected individuals as two primary factors that have hampered the treatment and HBV elimination from the human body; (2) the limitations of antiviral therapy and therapeutic vaccines, as strategies to control hepatitis B; and (3) the possibly promising therapeutic approaches for the complete cure and elimination of hepatitis B.

The Role of CTLA-4 in T Cell Exhaustion in Chronic Hepatitis B Virus Infection

Patients with chronic hepatitis B (CHB) gradually develop T cell exhaustion, and the inhibitory receptor molecule, cytotoxic T-lymphocyte antigen-4 (CTLA-4), may play a role in this phenomenon. This systematic review investigates the role of CTLA-4 in the development of T cell exhaustion in CHB. A systematic literature search was conducted on PubMed and Embase on 31 March 2023 to identify relevant studies. Fifteen studies were included in this review. A majority of the studies investigating CD8⁺ T cells demonstrated increased expression of CTLA-4 in CHB patients, though one study found this only in HBeAg-positive patients. Three out of four studies investigating the expression of CTLA-4 on CD4⁺ T cells found upregulation of CTLA-4. Several studies showed constitutive expression of CLTA-4 on CD4⁺ regulatory T cells. CTLA-4 blockade resulted in heterogeneous responses for all T cell types, as it resulted in increased T cell proliferation and/or cytokine production in some studies, while other studies found this only when combining blockade of CTLA-4 with other inhibitory receptors. Although mounting evidence supports a role of CTLA-4 in T cell exhaustion, there is still insufficient documentation to describe the expression and exact role of CTLA-4 in T cell exhaustion in CHB.

Immune checkpoints on T and NK cells in the context of HBV infection: Landscape, pathophysiology and therapeutic exploitation

In hepatitis B virus (HBV) infection, the interplay between the virus and the host immune system is crucial in determining the pathogenesis of the disease. Patients who fail to mount a sufficient and sustained anti-viral immune response develop chronic hepatitis B (CHB). T cells and natural killer (NK) cells play decisive role in viral clearance, but they are defective in chronic HBV infection. The activation of immune cells is tightly controlled by a combination of activating and inhibitory receptors, called immune checkpoints (ICs), allowing the maintenance of immune homeostasis. Chronic exposure to viral antigens and the subsequent dysregulation of ICs actively contribute to the exhaustion of effector cells and viral persistence. The present review aims to summarize the function of various ICs and their expression in T lymphocytes and NK cells in the course of HBV infection as well as the use of immunotherapeutic strategies targeting ICs in chronic HBV infection.

Increase in Serum Soluble Tim-3 Level Is Related to the Progression of Diseases After Hepatitis Virus Infection

Background

Viral hepatitis is a widespread and serious infectious disease, and most patients with liver cirrhosis and hepatocellular carcinoma are prone to viral infections. T cell immunoglobulin-and mucin-domain-containing molecule-3 (Tim-3) is an immune checkpoint molecule that negatively regulates T cell responses, playing an extremely important role in controlling infectious diseases. However, reports about the role of serum soluble Tim-3 (sTim-3) in hepatitis virus infection are limited. Therefore, this study explored changes in sTim-3 levels in patients infected with hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV).

Methods

This study applied high-sensitivity time-resolved fluorescence immunoassay for the detection of sTim-3 levels. A total of 205 cases of viral hepatitis infection (68 cases of HBV infection, 60 cases of HCV infection, and 77 cases of HEV virus infection) and 88 healthy controls were quantitatively determined. The changes in serum sTim-3 level and its clinical value in hepatitis virus infection were analyzed.

Results

Patients with HBV infection (14.00, 10.78–20.45 ng/mL), HCV infection (15.99, 11.83–27.00 ng/mL), or HEV infection (19.09, 10.85–33.93 ng/mL) had significantly higher sTim-3 levels than that in the healthy control group (7.69, 6.14–10.22 ng/mL, P < 0.0001). Patients with hepatitis and fibrosis infected with HBV (22.76, 12.82–37.53 ng/mL), HCV (33.06, 16.36–39.30 ng/mL), and HEV (28.90, 17.95–35.94 ng/mL) had significantly higher sTim-3 levels than patients with hepatitis without fibrosis (13.29, 7.75–17.28; 13.86, 11.48–18.64; 14.77, 9.79–29.79 ng/mL; P < 0.05).

Conclusion

sTim-3 level was elevated in patients infected with HBV, HCV, or HEV and gradually increased in patients with either hepatitis or hepatitis with hepatic fibrosis. It has a certain role in the evaluation of the course of a disease after hepatitis virus infection.

Significance of T-Cell Subsets for Clinical Response to Peginterferon Alfa-2a Therapy in HBeAg-Positive Chronic Hepatitis B Patients

Introduction

The adaptive immune response may reflect the immunomodulatory efficacy during peginterferon alfa-2a (PEG-IFN α-2a) treatment in chronic hepatitis B (CHB) patients. We evaluated the predictive efficiency of T-cell subsets on patient's response to PEG-IFN α-2a treatment.

Methods

The proportions of CD8+PD-1+, CD8+Tim-3+ and CD4+CD25high T-cells were measured at baseline and week 52 in CHB patients who underwent PEG-IFN α-2a treatment. The proportions of T-cell subsets were compared among different responders and non-responders (determined by biochemical, serological, and virological responses).

Results

The baseline proportions of the three T-cell subsets were significantly higher in CHB patients (65 cases) than in healthy controls (28 cases), while the proportions declined significantly after 52 weeks of PEG-IFN treatment. Responders (ALT < 40 IU/L, 89.2% [58/65]; HBV DNA < 2.7 log10 IU/ml, 66.2% [43/65]; and HBeAg seroconversion [SR], 53.9% [35/65]) experienced more pronounced declines in the proportion of T-cell subsets compared to non-responders. In particular, the baseline proportions of CD4+CD25high T-cells displayed significant difference between SR and non-SR groups. The stepwise logistic regression analysis identified that CD4+CD25high T-cells combined with baseline HBV DNA and ALT can predict SR and CR (ALT < 40 IU/L, HBV DNA < 2.7 log10 IU/mL and HBeAg seroconversion) after 52 weeks of PEG-IFN treatment with high accuracy.

Conclusion

PEG-IFN therapy induces significant declines in the proportion of some key T-cell subsets in HBeAg-positive patients. The model constructed with CD4+CD25high T-cells combined with ATL and HBV DNA may help to predict the efficacy of PEG-IFN α-2a therapy.

Interleukin-33 Reinvigorates Antiviral Function of Viral-Specific CD8+ T Cells in Chronic Hepatitis B Virus Infection

Restoration of exhausted hepatitis B virus (HBV)-specific CD8⁺ T cells is one of the important strategies for inhibition of viral replication. The role of interleukin (IL)-33 to recovery of CD8⁺ T cell activity is not fully elucidated. We investigated the effect of IL-33 on viral-specific CD8⁺ T cell responses in chronic hepatitis B (CHB) patients in vitro by both phenotypic and functional analysis. Plasma IL-33 was downregulated in CHB patients, while effective antiviral therapy rescued IL-33 expression. There was no significant difference of IL-33 receptor mRNA relative level in CD8⁺ T cells between CHB patients and controls. IL-33 induced the proliferation of HBV-specific CD8⁺ T cells, and reduced programmed death-1 expression on HBV-specific CD8⁺ T cells. IL-33 promoted the direct cytolytic activity of CD8⁺ T cells against HepG2.2.15 cells through boosting perforin and granzyme B production. Furthermore, IL-33 administration increased HBV-specific CD8⁺ T cell-mediated HBV replication and HBV antigen secretion mainly via enhancement of interferon-γ and tumor necrosis factor-α. IL-33 reinvigorated antiviral activity of HBV-specific CD8⁺ T cells, revealing that IL-33 might contribute to viral clearance in persistent HBV infection.

Immunopathology of Chronic Hepatitis B Infection: Role of Innate and Adaptive Immune Response in Disease Progression

More than 250 million people are living with chronic hepatitis B despite the availability of highly effective vaccines and oral antivirals. Although innate and adaptive immune cells play crucial roles in controlling hepatitis B virus (HBV) infection, they are also accountable for inflammation and subsequently cause liver pathologies. During the initial phase of HBV infection, innate immunity is triggered leading to antiviral cytokines production, followed by activation and intrahepatic recruitment of the adaptive immune system resulting in successful virus elimination. In chronic HBV infection, significant alterations in both innate and adaptive immunity including expansion of regulatory cells, overexpression of co-inhibitory receptors, presence of abundant inflammatory mediators, and modifications in immune cell derived exosome release and function occurs, which overpower antiviral response leading to persistent viral infection and subsequent immune pathologies associated with disease progression towards fibrosis, cirrhosis, and hepatocellular carcinoma. In this review, we discuss the current knowledge of innate and adaptive immune cells transformations that are associated with immunopathogenesis and disease outcome in CHB patients.

Immune Checkpoints in Viral Infections

As evidence has mounted that virus-infected cells, such as cancer cells, negatively regulate the function of T-cells via immune checkpoints, it has become increasingly clear that viral infections similarly exploit immune checkpoints as an immune system escape mechanism. Although immune checkpoint therapy has been successfully used in cancer treatment, numerous studies have suggested that such therapy may also be highly relevant for treating viral infection, especially chronic viral infections. However, it has not yet been applied in this manner. Here, we reviewed recent findings regarding immune checkpoints in viral infections, including COVID-19, and discussed the role of immune checkpoints in different viral infections, as well as the potential for applying immune checkpoint blockades as antiviral therapy.

FoxP3, PD-1 and CTLA-4 are decreased significantly after a tenofovir therapy in patients with chronic hepatitis B

Background: FoxP3, PD-1 and CTLA-4 are upregulated in chronic viral infections, such as chronic HCV, chronic HBV and HIV infection. Materials & methods: During 1 year of tenofovir disoproxil fumarate (TDF) treatment in patients with chronic hepatitis B, we investigated the expression of FoxP3, PD-1 and CTLA-4. Peripheral blood mononuclear cells were isolated from the 30 study subjects at T0 (0 months), T3, T6 and T12 months after the commencement of TDF treatment. Results & conclusion: Expression of FoxP3, PD-1 and CTLA-4 was significantly decreased in T cells of patients with chronic hepatitis B under TDF treatment at T12, when compared with that at T0. A direct correlation was observed between FoxP3 and CTLA-4 expression in patients with chronic hepatitis B and the frequency of FoxP3 was positively associated with serum alanine aminotransferase levels.

The roles of PD-1/PD-L1 and its signalling pathway in gastrointestinal tract cancers

Cancer immunotherapy has been increasingly applied in the treatment of advanced malignancies. Consequently, immune checkpoints have become a major concern. As PD-1 is an important immunomodulatory protein, the blockade of PD-1 and its ligand PD-L1 is a promising tumour immunotherapy for human carcinoma. In this review, we first discuss the role of the PD-1/PD-L1 interaction in gastrointestinal tract cancers. Targeting PD-1 and PD-L1 in immune cells and tumour cells may show remarkable efficiency in gastrointestinal tract cancers. Second, the PD-1/PD-L1-associated signalling pathway involved in cancer immunotherapy in gastrointestinal tract cancers is discussed. Most importantly, this review summarizes the PD-1/PD-L1-targeted immunotherapy combinations with relevant signalling pathways, which may result in a breakthrough for the treatment of gastrointestinal tract cancers, such as gastric cancer, colorectal cancer and liver cancer. Meanwhile, the review provides a deeper insight into the mechanism of checkpoint blockade immunotherapies.

Downregulated Tim-3 expression is responsible for the incidence and development of colorectal cancer

The present study aimed to investigate the role of T cell immunoglobulin domain and mucin-3 (Tim-3) in its gene and protein forms in colorectal cancer (CRC), and to verify the significance of Tim-3 expression in patients with CRC. A prospective analysis of 258 patients with CRC and 246 normal controls was conducted between December 2012 and June 2015. Intestinal samples were collected, including of CRC tissues, paracancerous tissues and normal colon mucosa tissues. Peripheral venous blood samples were also collected. Polymerase chain reaction (PCR) amplification, reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis was performed for the detection and evaluation of Tim-3 gene and protein in various tissues. PCR analysis indicated that the T and G alleles of -882C/T and 4259T/G are associated with a significantly increased risk of CRC. Following the confirmation of Tim-3 expression in CRC tissues, RT-qPCR detection and western blot analysis revealed clear downregulation of Tim-3 mRNA and protein expression in the blood and tissue samples obtained from patients with CRC, as compared with in the corresponding control samples. Similar trends of decreased Tim-3 mRNA levels and protein expression were observed in CRC tissues compared with in the paracancerous and the normal colon mucosa tissues. In addition, the mRNA and protein expression levels in the paracancerous tissues were lower than those in the normal colon mucosa tissues. Furthermore, significantly lower Tim-3 mRNA levels were observed in patients with a tumor size >5 cm, a poor differentiation degree, higher tumor-node-metastasis stage (stage III-IV), and lymph node and distant metastasis. Collectively, genetic changes to Tim-3, expressed as polymorphisms in Tim-3, and decreased mRNA/protein expression may be partially responsible for the incidence and development of CRC.

Highly elevated soluble Tim-3 levels correlate with increased hepatocellular carcinoma risk and poor survival of hepatocellular carcinoma patients in chronic hepatitis B virus infection

Background and objective

Upregulated T-cell immunoglobulin and mucin domain containing molecule-3 (Tim-3) in hepatitis B virus (HBV)-specific CD8⁺ T-cells contributes to CD8⁺ T-cell exhaustion during chronic HBV infection. The membrane-bound Tim-3 can be cleaved from the cell surface by sheddase, yielding soluble Tim-3 (sTim-3). This study investigated serum sTim-3 levels in patients with chronic HBV infection of various liver diseases.

Methods

Serum sTim-3 levels were quantitatively determined in 288 patients with chronic HBV infection of various liver diseases. The sTim-3 levels were analyzed in relation to liver diseases including HBV-related hepatocellular carcinoma (HCC) and overall survival of HCC patients.

Results

Serum sTim-3 levels in the patients with chronic HBV infection were significantly elevated compared with healthy controls (P<0.001) and the levels from asymptomatic HBV carrier status, chronic hepatitis, liver cirrhosis to HCC were progressively increased. Serum sTim-3 levels were closely associated with the severity of liver function abnormalities. Importantly, serum sTim-3 levels were independently associated with HCC risk (OR, 4.310; 95% CI, 2.141–8.676, P<0.001) in comparison to non-HCC diseases in chronic HBV infection and significantly associated with the overall survival of HCC patients, with a level >3000 pg/mL being related to shorter overall survival than a level ≤3000 pg/mL (P=0.019).

Conclusion

Serum sTim-3 is involved in disease progression and HCC development in chronic HBV infection and its quantitative determination may be potentially used as a marker for monitoring the disease progression and predicting the HCC prognosis in chronic HBV infection.

Aberrant production of soluble inducible T cell co‑stimulator and soluble programmed cell death protein 1 in patients with chronic hepatitis B

Previous studies demonstrated that immune dysregulation is an important cause of hepatitis B virus (HBV)‑mediated liver damage. Co‑stimulators including programmed cell death protein 1 (PD‑1) and inducible T cell co‑stimulator (ICOS) are involved in the pathogenesis of HBV. In the present study, the serum levels of soluble (s)PD‑1 and sICOS in patients with chronic HBV infections, were investigated, and the association between sPD‑1 and sICOS levels and liver injury degree was investigated. Serum sPD‑1 and sICOS levels were increased in the HBV‑patient group particularly in the HBV external core antigen positive group. In the immune clearance group, sPD‑1 and sICOS were increased compared with the tolerance group. Furthermore, the relative mRNA expression levels were also increased in patients with HBV. However there was no correlation between sPD‑1 and sICOS levels and HBV antibodies or PD‑1/ICOS mRNA copies. The altered sPD‑1 and sICOS serum levels in the different HBV groups may reflect the dysregulation of T cell activation, and may be associated with the HBV pathological process.

Interaction between Galectin-9/TIM-3 pathway and follicular helper CD4+ T cells contributes to viral persistence in chronic hepatitis C

Both Galectin 9 (Gal-9)/T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) pathway and follicular helper CD4⁺ T (Tfh) cells play important roles in persistent hepatitis C virus (HCV) infection. Thus, we aimed to investigate the regulatory role of interaction between Gal-9/TIM-3 pathway and Tfh cells in chronic hepatitis C. A total of 44 chronic hepatitis C patients and 19 normal controls (NCs) were enrolled in this study. Purified CD4⁺ T cells were cultured by TIM-3 Fc protein, recombinant Gal-9, or IL-21 for 48h. TIM-3 expression, Tfh proportion, and IL-21 production was measured, respectively. The immunomodulatory role of Gal-9/TIM-3 and IL-21 was also investigated in HCV cell culture system in vitro. We found that the percentage corresponding to both TIM-3-positive and CXCR5⁺ICOS⁺ Tfh cells within CD4⁺ T cells, which correlated with HCV RNA replication, was significantly elevated in patients with chronic hepatitis C in comparison with those in NCs. Moreover, blockade of Gal-9/TIM-3 pathway by TIM-3 Fc protein increased Tfh cells proportion, IL-21 mRNA and protein expression within purified CD4⁺ T cells, while activation of Gal-9/TIM-3 signaling by Gal-9 stimulation decreased IL-21 production in both patients with chronic HCV infection and healthy individuals. Meanwhile, high concentrations (100 and 200ng/mL) of IL-21 stimulation also elevated TIM-3 expression on CD4⁺ T cells in chronic hepatitis C. Furthermore, TIM-3 blockage and IL-21 stimulation suppressed mRNA expressions of HCV-induced antiviral proteins (myxovirus resistance A and oligoadenylate synthetase) in Huh7.5 cells without affecting viral replication in HCV cell culture system. The interaction between Gal-9/TIM-3 pathway and Tfh cells contributed to viral persistent in chronic HCV infection, which might be pivotal for development of new therapeutic approaches for chronic hepatitis C.

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is associated with immune phases of patients with chronic hepatitis B

Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a newly negative immune regulator but its role in different immune phases of patients with chronic hepatitis B (CHB) is unknown. We determined the mRNA levels of TIPE2, interleukin-6, interleukin-10, tumor necrosis factors-α and interferon-γ in peripheral blood mononuclear cells from 205 naïve treated CHB patients and 15 healthy controls by quantitative real time polymerase chain reaction. Intrahepatic TIPE2 protein was also determined using immunohistochemistry staining. The TIPE2 mRNA level in CHB patients was significantly higher than that in healthy controls. Moreover, the TIPE2 mRNA level in immune clearance (IC) phases was significantly higher than that in immune tolerance (IT) phase; whereas TIPE2 mRNA in HBeAg negative hepatitis (ENH) was obviously higher than low replication (LR) phase. Furthermore, the optional cut off values of 2.02 and 1.59 for TIPE2 mRNA level have strong power in identifying IC and ENH from IT and LR. In addition, intrahepatic TIPE2 protein was predominantly located in hepatocyte plasma and correlated with hepatic inflammatory and fibrosis. Multivariate analysis showed tumor necrosis factors-α, interferon-γ and HBV DNA load were independently correlated with TIPE2 level. In conclusion, TIPE2 might be associated to the immune clearance of patients with chronic hepatitis B.

Phenotypic Characteristics of PD-1 and CTLA-4 Expression in Symptomatic Acute Hepatitis A

Background/Aims

The immunoregulatory molecules programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are associated with the dysfunction of antiviral effector T-cells, which leads to T-cell exhaustion and persistent viral infection in patients with chronic hepatitis C and chronic hepatitis B. Little is known about the role of PD-1 and CTLA-4 in patients with symptomatic acute hepatitis A (AHA).

Methods

Peripheral blood mononuclear cells were isolated from seven patients with AHA and from six patients with nonviral acute toxic hepatitis (ATH) during the symptomatic and convalescent phases of the respective diseases; five healthy subjects acted as controls. The expression of PD-1 and CTLA-4 on T-cells was measured by flow cytometry.

Results

PD-1 and CTLA-4 expression during the symptomatic phase was significantly higher in the T-cells of AHA patients than in those of ATH patients or healthy controls (PD-1: 18.3% vs 3.7% vs 1.6%, respectively, p<0.05; CTLA-4: 23.5% vs 6.1% vs 5.9%, respectively, p<0.05). The levels of both molecules decreased dramatically during the convalescent phase of AHA, whereas a similar pattern was not seen in ATH.

Conclusions

Our findings are consistent with a viral-protective effect of PD-1 and CTLA-4 as inhibitory molecules that suppress cytotoxic T-cells and thereby prevent the destruction of virus-infected hepatocytes in AHA.

Inhibitory receptor expression on memory CD8 T cells following Ad vector immunization

T cells are an important component of immune responses, and their function is influenced by their expression of inhibitory receptors. Immunization with alternative serotype adenovirus (Ad) vectors induces highly functional T cell responses with lower programmed cell death 1 (PD-1) expression and increased boostability relative to Ad5 vectors. However, a detailed phenotypic characterization of other inhibitory receptors is lacking, and it is unknown whether Ad5-induced CD8 T cells eventually recover function with time. In this report, we measure the expression of various inhibitory receptors and memory markers during early and late time points following vaccination with Ad5 and alternative serotype Ad vectors. CD8 T cells induced by Ad5 exhibited increased expression of the inhibitory receptor Tim-3 and showed decreased central memory differentiation as compared with alternative serotype Ad vectors, even a year following immunization. Moreover, relative to Ad5-primed mice, Ad26-primed mice exhibited substantially improved recall of SIV Gag-specific CD8 T cell responses following heterologous boosting with MVA or Ad35 vectors. We also demonstrate that low doses of Ad5 priming resulted in more boostable immune responses with lower PD-1 expression as compared to high Ad5 doses, suggesting a role for vector dose in influencing immune dysfunction following Ad5 vaccination. These data suggest that Ad5 vectors induce a long-term pattern of immune exhaustion that can be partly overcome by lowering vector dose and modulating inhibitory signals.

Abnormal expression of Tim-3 antigen on peripheral blood T cells is associated with progressive disease in osteosarcoma patients

T‐cell immunoglobulin and mucin‐domain‐3‐containing molecule 3 (TIM‐3) plays a pivotal role in immune regulation and has been found in various tumors. However, the prevalence and distribution of Tim‐3 in osteosarcoma (OS) is still unclear. The aim of this study was to investigate the prevalence and distribution of Tim‐3 in OS. Tim‐3 on peripheral T cells from 82 OS patients and 60 healthy controls were examined by flow cytometry. Plasma levels of IL‐2, IFN‐γ, and TNF‐α were measured by ELSIA. Tim‐3 on both CD4⁺ T and CD8⁺ T cells were significantly upregulated in OS patients compared with healthy controls, Tim‐3⁺ CD4⁺ T, and Tim‐3⁺ CD8⁺ T cells were both negatively associated with serum levels of IL‐2 and IFN‐γ and TNF‐α. In addition, Tim‐3 showed similar levels in patients with different tumor sites. Nevertheless, patients with advanced tumor stage, metastasis, and pathological tumor fracture displayed significantly higher Tim‐3 on both CD4⁺ T cells and CD8⁺ T cells than those with early tumor stage, without metastasis and pathological tumor fracture. Moreover, high Tim‐3 on peripheral CD4⁺ T cells or CD8⁺ T were significantly related to poor overall survival (P = 0.014, P = 0.035, respectively). In conclusion, Tim‐3 may be a potential diagnostic and prognostic biomarker for OS progression.

microRNA-4717 differentially interacts with its polymorphic target in the PD1 3' untranslated region: A mechanism for regulating PD-1 expression and function in HBV-associated liver diseases

Programmed cell death-1 (PD-1) is involved in hepatitis B virus (HBV) infection, the leading cause of hepatocellular carcinoma (HCC) worldwide. Single-nucleotide polymorphism, rs10204525, located in the PD1 3' untranslated regions (UTR), is associated with chronic HBV infection. MicroRNAs (miRNAs) regulate gene expression via specific binding to the target 3'UTR of mRNA. In this study, three miRNAs were predicted to putatively interact with PD1 rs10204525 polymorphic site of allele G. One of them, miRNA-4717, was demonstrated to allele-specifically affect luciferase activity in a dose-dependent manner in cells transfected with vectors containing different rs10204525 alleles. In lymphocytes from chronic HBV patients withrs10204525 genotype GG, miR-4717 mimics significantly decreased PD-1 expression and increased (TNF)-α and interferon (IFN)-γ production. miR-4717 inhibitor significantly increased PD-1 expression and decreased TNF-α and IFN-γ production although not significantly. In lymphocytes from chronic HBV patients with rs10204525 genotype AA, no similar effects were observed. miR-4717 levels in peripheral lymphocytes from patients with HBV-related chronic hepatitis, cirrhosis and HCC were significantly decreased. In conclusion, miR-4717 may allele-specifically regulate PD-1 expression through interaction with the 3' UTR of PD1 mRNA, leading to the alteration of immune regulation and affecting the susceptibility and disease course of chronic HBV infection.

Pretreatment Predictors of Response to PegIFN-RBV Therapy in Egyptian Patients with HCV Genotype 4

BACKGROUND

Egypt has the highest prevalence of a difficult to treat chronic hepatitis C virus (HCV), genotype 4. Pretreatment factors could guide individualization of therapy which aids in treatment optimization and interleukin IL28B gene polymorphism has been shown to closely relate to HCV treatment response. Polymorphisms in genes encoding inhibitors of T-cell response, which have role in disease progression as Programmed Cell Death 1 (PD-1), and Cytotoxic T-Lymphocytes Antigen-4 (CTLA-4), could be candidate markers predicting treatment response.

METHODS

This cohort study consisted of 200 chronic HCV genotype 4 infected patients treated with PegIFN α-2a and RBV in 2 hepatology centers. Genotyping of the polymorphisms in the IL28B gene region (rs12979860), PD1.3 (rs11568821) and CTLA-4 (rs231775) was performed on DNA collected from each patient using TaqMan® genotyping assay. Groups were classified according to response into sustained virological responders (SVR), or non-responders (NR). A multivariate logistic regression analysis was used to identify potential markers, host pretreatment clinical and viral predictive factors including viral load, insulin resistance, and alpha fetoprotein (AFP) related to treatment response.

RESULTS

Our results showed that in a multivariate analyses IL28B C/C genotype was the most significant predictor for SVR (OR = 10.86; p<0.0001) followed by AFP (OR = 0.915; p = 0.001) then CTLA-4/G genotypes (OR = 1.948; p = 0.022). However, PD-1.3/A genotypes and platelets count were significantly related to response in univariate analysis only (OR = 1.973; p = 0.023; OR = 1.007; p = 0.009 respectively).

CONCLUSION

IL28B SNP, AFP level, and CTLA-4 SNP could be used in conjunction to predict treatment response in HCV genotype 4 infected Egyptian patients.

Roles of PD-1, Tim-3 and CTLA-4 in immunoregulation in regulatory T cells among patients with sepsis

OBJECTIVE

This study aims to elucidate the roles of PD-1, Tim-3 and CTLA-4 in sepsis.

METHODS

Sepsis patients (n = 182) were selected as sepsis group and divided into three subgroups: mild sepsis group, severe sepsis group and septic shock group; 185 healthy volunteers were enrolled as control group. Flow cytometry and blood routine examination were performed for T lymphocytes and surface co-stimulatory molecules expressions. Pearson correlation test was applied for the correlation of co-stimulatory molecules expressions on T lymphocytes with critical illness in sepsis. Logistic regression analysis was conducted for risk factors in sepsis.

RESULTS

Heart rate and WBC in subgroups were higher than control group (P < 0.05). The differences in APACHE II, SAP II and SOFA score among subgroups were statistically significant (P < 0.05). Compared with control group, lymphocyte ratio and percentage of CD4(+) T cells reduced in subgroups (P < 0.05). The differences in expression levels of CD4(+)PD-1(+), CD8(+)PD-1(+), and CD8(+)CTLA-4(+) showed statistical significances (P < 0.05). Apparently, expression levels of CD4(+)TIM-3(+), CD8(+)TIM-3(+), CD4(+)PD-1(+), CD8(+)PD-1(+), and CD4(+)CTLA-4(+) were positively correlated with APACHE II score (all P < 0.05). Logistic regression analysis showed that heart rate and expression level of CD4(+)PD-1(+) might be risk factors while the percentage of CD4(+) T cells might be a protective factor for sepsis (P < 0.05).

CONCLUSION

PD-1 aggravates immune responses consistent with promotion of T cell exhaustion in sepsis. Expression level of CD4(+)PD-1(+) and heart rate are potential risk factors while percentage of CD4(+) T cells is a possible protective factor for sepsis.

Restoring homeostasis of CD4+ T cells in hepatitis-B-virus-related liver fibrosis

Immune-mediated liver injury is widely seen during hepatitis B virus (HBV) infection. Unsuccessful immune clearance of HBV results in chronic hepatitis and increases the risk of liver cirrhosis and hepatocellular carcinoma. HBV-related liver fibrosis (HBVLF), occurring as a result of HBV-induced chronic hepatitis, is a reversible, intermediate stage of chronic hepatitis B (CHB) and liver cirrhosis. Therefore, defining the pathogenesis of HBVLF is of practical significance for achieving better clinical outcomes. Recently, the homeostasis of CD4⁺ T cells was considered to be pivotal in the process of HBVLF. To better uncover the underlying mechanisms, in this review, we systematically retrospect the impacts of different CD4⁺ T-cell subsets on CHB and HBVLF. We emphasize CD4⁺ T-cell homeostasis and the important balance between regulatory T (Treg) and T helper 17 (Th17) cells. We discuss some cytokines associated with Treg and Th17 cells such as interleukin (IL)-17, IL-22, IL-21, IL-23, IL-10, IL-35 and IL-33, as well as surface molecules such as programmed cell death protein 1, cytotoxic T lymphocyte-associated antigen 4, T cell immunoglobulin domain and mucin domain-containing molecule 3 and cannabinoid receptor 2 that have potential therapeutic implications for the homeostasis of CD4⁺ T cells in CHB and HBVLF.

Regulation of HBV-specific CD8(+) T cell-mediated inflammation is diversified in different clinical presentations of HBV infection

Chronic HBV infection is the leading cause of liver cirrhosis and hepatic cancer, but the individual responses toward HBV infection are highly variable, ranging from asymptomatic to chronic active hepatitis B inflammation. In this study, we hypothesized that the different individual responses to HBV infection was associated with differences in HBV-specific CD8(+) T cell-mediated inflammation and cytotoxicity. Blood samples were collected from subjects with asymptomatic HBV-infection, subjects undergoing active chronic HBV flares (active CHB), and subjects with HBV-infected hepatocellular carcinoma (HBV-HCC). By tetramer staining, we found that all three groups had similar frequencies of HBVspecific CD8(+) T cells. However, after HBV peptide stimulation, the HBV-specific CD8(+) T cells in asymptomatic subjects had significantly stronger interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and CD107a expression than those in active CHB and HBV-HCC patients. Examination of surface marker expression revealed that the PD-1(-)Tim-3(-) double-negative cell population was the main contributor to HBV-specific inflammation. In active CHB patients and HBV-HCC patients, however, the frequencies of activated PD-1(-)Tim-3(-) cells were significantly reduced. Moreover, the serum HBV DNA titer was not correlated with the frequencies of HBV-specific CD8(+) T cells but was inversely correlated with the frequencies of IFN-g-expressing and CD107a-express cells in response to HBV stimulation. Together, our data demonstrated that the status of HBVspecific CD8(+) T cell exhaustion was associated with different clinical outcomes of chronic HBV infection.

Type I Interferon Elevates Co-Regulatory Receptor Expression on CMV- and EBV-Specific CD8 T Cells in Chronic Hepatitis C

Hepatitis C virus (HCV) readily sets up persistence in a large fraction of infected hosts. Mounting epidemiological and immunological evidence suggest that HCV's persistence could influence immune responses toward unrelated pathogens and vaccines. Nonetheless, the fundamental contribution of the inflammatory milieu during persistent HCV infection in impacting immune cells specific for common pathogens such as CMV and EBV has not been fully studied. As the co-regulatory receptors PD-1, Tim-3, and 2B4 have all been shown to be vital in regulating CD8(+) T cell function, we assessed their expression on CMV/EBV-specific CD8(+) T cells from patients with chronic hepatitis C (CHC) and healthy controls ex vivo and upon stimulation with virus-specific peptides in vitro. Total and CMV/EBV-specific CD8(+) T cells expressing PD-1, Tim-3, and 2B4 were highly enriched in patients with CHC compared to healthy individuals ex vivo. In vitro peptide stimulation further potentiated the differential co-regulatory receptor expression of PD-1, Tim-3, and 2B4, which then culminated in an enhanced functionality of CMV/EBV-specific CD8(+) T cells in CHC patients. Comprehensively analyzing plasma cytokines between the two cohorts, we observed that not only was IFNα-2a dominant among 21 other inflammatory mediators elevated in CHC patients but it also correlated with PD-1 and Tim-3 expressions ex vivo. Importantly, IFNα-2a further caused upregulation of these markers upon in vitro peptide stimulation. Finally, we could prospectively study patients receiving novel IFN-free antiviral therapy. Here, we observed that treatment-induced clearance of HCV resulted in a partial reversion of the phenotype of CMV/EBV-specific CD8(+) T cells in patients with CHC. These data reveal an alteration of the plasma concentrations of IFNα-2a together with other inflammatory mediators during CHC, which appeared to pervasively influence co-regulatory receptor expression on CMV/EBV-specific CD8(+) T cells.

Relationship between antiviral therapy and PD-1/PD-L1 expression on immune cells in chronic hepatitis B patients

In China, the immune pathological damage of hepatocytes induced by the persistent replication of hepatitis B virus (HBV) is regarded as the reason that leads to HBV infection chronicity and aggravates the patient's condition. Therefore, antiviral therapy is effective measures to prevent the aggravation of patient's condition after HBV infection. Among several pathogenic mechanisms associated with the host immune dysregulation, programmed death 1 (PD-1)/PD-1 ligand 1 (PD-L1) pathway is believed to be related with the outcome of HBV infection. This review will discuss the relationship between antiviral therapy and PD-1/PD-L1 expression on immune cells in chronic hepatitis B (CHB) patients.

The advantages of PD1 activating chimeric receptor (PD1-ACR) engineered lymphocytes for PDL1(+) cancer therapy

Tumors exploit immunoregulatory checkpoints to attenuate T cell responses as a means of circumventing immunologic rejection. By activating the inhibitory costimulatory pathway of Programmed Death 1 (PD1)/PDL1 which provides tumor cells an escape mechanism from immune surveillance, Programmed Death Ligand1 (PDL1)(+) tumors hamper activated tumor-specific T cell functions and render them functionally exhausted. To overcome the inhibitory costimulatory effects of PDL1 on the adoptively transferred T cells, we sought to convert PD1 to a T cell costimulatory receptor by exchanging its transmembrane and cytoplasmic tail with CD28 and 4-1BB signaling domains (PD1-CD28-4-1BB, PD1-ACR), anticipating the genetically modified effector T lymphocytes expressing PD1-ACR would exhibit enhanced functional attributes. And the results showed that PD1-ACR expressed T cells retained the ability to bind PDL1, resulting in T cell activation as evidenced by the elevated activity of phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), the augmentation of cytokine secretion and the increased proliferative capacity. Moreover, when systemically administered in the mouse model of glioblastoma metastases, PD1-ACR T cells localized at the area of U87 invasive tumor, which results in suppressed tumor growth and enhanced survival of mice with established U87 glioblastoma. Together, these data demonstrated that PD1-ACR has a high potential to serve as a novel strategy to overcome PDL1 mediated immunosuppression of T cells for cancer therapy.