Longitudinal fluctuations in PD1 and PD-L1 expression in association with changes in anti-viral immune response in chronic hepatitis B. BMC Gastroenterol. 2012;12:109. [PMID: 22894700 PMCID: PMC3514338 DOI: 10.1186/1471-230x-12-109]

From hepatitis B virus infection to acute-on-chronic liver failure: The dynamic role of hepatic macrophages

Acute-on-chronic liver failure (ACLF) is a progressive disease that is associated with rapid worsening of clinical symptoms and high mortality. A multicentre prospective study from China demonstrated that patients with hepatitis B virus-related ACLF (HBV-ACLF) exhibited worse clinical characteristics and higher mortality rates compared to non-HBV-ACLF patients. Immune dysregulation is closely linked to the potential mechanisms of initiation and progression of ACLF. Innate immune response, which is represented by monocytes/macrophages, is up-regulated across ACLF development. This suggests that monocytes/macrophages play an essential role in maintaining the immune homeostasis of ACLF. Information that has been published in recent years shows that the immune status and function of monocytes/macrophages vary in ACLF precipitated by different chronic liver diseases. Monocytes/macrophages have an immune activation effect in hepatitis B-precipitated-ACLF, but they exhibit an immune suppression in cirrhosis-precipitated-ACLF. Therefore, this review aims to explain whether this difference affects the clinical outcome in HBV-ACLF patients as well as the mechanisms involved. We summarize the novel findings that highlight the dynamic polarization phenotype and functional status of hepatic macrophages from the stage of HBV infection to ACLF development. Moreover, we discuss how different HBV-related liver disease tissue microenvironments affect the phenotype and function of hepatic macrophages. In summary, increasing developments in understanding the differences in immune phenotype and functional status of hepatic macrophages in ACLF patients will provide new perspectives towards the effective restoration of ACLF immune homeostasis.

Engineered anti-PDL1 with IFNα targets both immunoinhibitory and activating signals in the liver to break HBV immune tolerance

OBJECTIVE

The purpose of this study is to develop an anti-PDL1-based interferon (IFN) fusion protein to overcome the chronic hepatitis B virus (HBV)-induced immune tolerance, and combine this immunotherapy with a HBV vaccine to achieve the functional cure of chronic hepatitis B (CHB) infection.

DESIGN

We designed an anti-PDL1-IFNα heterodimeric fusion protein, in which one arm was derived from anti-PDL1 antibody and the other arm was IFNα, to allow targeted delivery of IFNα into the liver by anti-PDL1 antibody. The effect of the anti-PDL1-IFNα heterodimer on overcoming hepatitis B surface antigen (HBsAg) vaccine resistance was evaluated in chronic HBV carrier mice.

RESULTS

The anti-PDL1-IFNα heterodimer preferentially targeted the liver and resulted in viral suppression, the PD1/PDL1 immune checkpoint blockade and dendritic cell activation/antigen presentation to activate HBsAg-specific T cells, thus breaking immune tolerance in chronic HBV carrier mice. When an HBsAg vaccine was administered soon after anti-PDL1-IFNα heterodimer treatment, we observed strong anti-HBsAg antibody and HBsAg-specific T cell responses for efficient HBsAg clearance in chronic HBV carrier mice that received the combination treatment but not in those that received either single treatment.

CONCLUSIONS

Targeting the liver with an engineered anti-PDL1-IFNα heterodimer can break HBV-induced immune tolerance to an HBsAg vaccine, offering a promising translatable therapeutic strategy for the functional cure of 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.

Immune predictors of hepatitis B surface antigen seroconversion in patients with hepatitis B reactivation

BACKGROUND

Hepatitis B surface antigen (HBsAg) seroconversion is sometimes observed in hepatitis B reactivation (rHBV), probably due to immune resetting and differentiation.

AIMS

To investigate sequential immune differentiation and abrogation of tolerance in patients with rHBV who achieved HBsAg seroconversion.

METHODS

We included 19 patients with chronic hepatitis B (CHBV; HBV DNA log10^3-8 ), 67 with rHBV (raised ALT [>5XULN], HBV DNAlog10^4-8 ) and 10 healthy controls. Immune differentiation, tolerance and functional status of CD4, CD8, T regulatory cells (Tregs), B cells and follicular T helper (Tfh) cells were assessed at baseline and 24 weeks.

RESULTS

At 24 weeks, 81% rHBV (n = 67) lost HBV DNA and HBeAg (41%), and 12 (19%) lost HBsAg and made anti-HBs titers >10 IU/ml. rHBV patients had higher Th1/17, T_EM , Tfh, Tfh1/17, plasma and ATM B cells, and lower Tregs, Th2, Th17 and TEMRA expression. rHBV showed lower PD1, TIM3, LAG3, SLAM and TOX compared to CHBV. There was a significant increase in CD8, CD8EM, Tfh, Tfh1/17 and plasma B cells in seroconverters than non-seroconverters. At 24 weeks, we also observed increased plasma B cell frequency in seroconverters. While non-seroconverters showed higher expression of PD1, TIM3, LAG3, SLAM and TOX on CD4/CD8 T cells, blockade of PD1, TIM3, LAG3 and CTLA4 significantly enhanced IFN-γ, TNF-α, IL-4 and IL-21 expression on CD4/CD8 and Tfh cells in non-seroconverters.

CONCLUSIONS

Non-seroconverters have increased inhibitory markers on CD4/CD8 T cells. There is a critical play of CD8, Tfh and B cells and subsets in seroclearance, along with checkpoint molecules as a potential therapy for non-seroconverters in HBV infection.

Pathogenicity and virulence of Hepatitis B virus

Hepatitis B virus (HBV) is a hepatotropic virus and an important human pathogen. There are an estimated 296 million people in the world that are chronically infected by this virus, and many of them will develop severe liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). HBV is a small DNA virus that replicates via the reverse transcription pathway. In this review, we summarize the molecular pathways that govern the replication of HBV and its interactions with host cells. We also discuss viral and non-viral factors that are associated with HBV-induced carcinogenesis and pathogenesis, as well as the role of host immune responses in HBV persistence and liver pathogenesis.

Impact of tumor programmed death ligand-1 expression on osimertinib efficacy in untreated EGFR-mutated advanced non-small cell lung cancer: a prospective observational study

Background

Osimertinib monotherapy is currently the standard of care as a first-line treatment for patients harboring epidermal growth factor receptor (EGFR) mutations; however, some EGFR-mutated non-small cell lung cancer (NSCLC) patients exhibit primary resistance and an insufficient response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Elevated programmed death-ligand 1 (PD-L1) expression in tumors was reported as a negative predictive factor for outcomes of first- or second-generation EGFR-TKIs.

Methods

We prospectively assessed advanced NSCLC patients with EGFR mutations who were treated with osimertinib at 14 institutions in Japan between September 2019 and December 2020. Relationships between outcomes of osimertinib monotherapy and patients’ characteristics were reviewed.

Results

Seventy-one patients who underwent the tumor PD-L1 test were enrolled. Multivariate analysis identified tumor PD-L1 expression as an independent predictor for progression-free survival (PFS) with osimertinib treatment (P=0.029). The objective-response and disease-control rates for osimertinib treatment were significantly lower in patients demonstrating elevated PD-L1 levels relative to those with low or negative PD-L1 level (P=0.043 and P=0.007, respectively). Furthermore, among patients treated with osimertinib, those with high PD-L1 levels exhibited shorter PFS relative to those with low plus negative PD-L1 level (median PFS: 5.0 vs. 17.4 months; P<0.001).

Conclusions

Elevated tumor PD-L1 expression is associated with poor outcomes of osimertinib monotherapy in previously untreated advanced NSCLC patients with EGFR mutation. Further clinical trials are warranted to accumulate evidence demonstrating the effectiveness of combination therapy with osimertinib for EGFR-mutated advanced NSCLC patients with elevated tumor PD-L1 expression.

Trial Registration

UMIN000043942.

Associations of PD-L1, PD-L2, and HLA class I expression with responses to immunotherapy in patients with advanced sarcoma: post hoc analysis of a phase 1/2 trial

BACKGROUND

Although immunotherapy is thought to be a promising cancer treatment, most patients do not respond to immunotherapy. In this post hoc analysis of a phase 1/2 study, associations of programmed death ligand 1 (PD-L1), PD-L2, and HLA class I expressions with responses to dendritic cells (DCs)-based immunotherapy were investigated in patients with advanced sarcoma.

METHODS

This study enrolled 35 patients with metastatic and/or recurrent sarcomas who underwent DC-based immunotherapy. The associations of PD-L1, PD-L2, and HLA class I expressions in tumor specimens, which were resected before immunotherapy, with immune responses (increases of IFN-γ and IL-12) and oncological outcomes were evaluated.

RESULTS

Patients who were PD-L2 (+) showed lower increases of IFN-γ and IL-12 after DC-based immunotherapy than patients who were PD-L2 (-). The disease control (partial response or stable disease) rates of patients who were PD-L1 (+) and PD-L1 (-) were 0% and 22%, respectively. Disease control rates of patients who were PD-L2 (+) and PD-L2 (-) were 13% and 22%, respectively. Patients who were PD-L1 (+) tumors had significantly poorer overall survival compared with patients who were PD-L1 (-). No associations of HLA class I expression with the immune response or oncological outcomes were observed.

CONCLUSIONS

This study suggests that PD-L1 and PD-L2 are promising biomarkers of DC-based immunotherapy, and that addition of immune checkpoint inhibitors to DC-based immunotherapy may improve the outcomes of DC-based immunotherapy.

Programmed cell death protein 1 on natural killer cells: fact or fiction?

Programmed cell death protein 1 (PD-1) has become one of the most investigated targets for cancer immunotherapy. Most research has centered on inhibiting PD-1 on T cells, but there is increased interest in understanding the role of PD-1 on NK cells. While the expression of PD-1 on NK cells has been controversial, with papers publishing contradictory results in multiple models, there is increased clinical interest in NK and PD-1 immunotherapy. In this issue of the JCI, Judge et al. comprehensively explore the lack of PD-1 expression on murine, canine, and human NK cells and the clinical implication of these findings.

Effectiveness and safety of toripalimab, camrelizumab, and sintilimab in a real-world cohort of hepatitis B virus associated hepatocellular carcinoma patients

BACKGROUND

The clinical significance of programmed cell death protein-1 (PD-1)-targeted immunotherapy in Chinese patients is understudied. We thus aimed to evaluate the safety and efficacy of PD-1 inhibitors with toripalimab, camrelizumab or sintilimab for Chinese hepatocellular carcinoma (HCC) patients in a real-life cohort.

METHODS

We analysed hepatitis B virus (HBV)-associated HCC patients treated with toripalimab, camrelizumab, or sintilimab in a retrospective single-center cohort from November 2018 to June 2020. Efficacy was evaluated with objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), time to tumor progression (TTP), and overall survival (OS). Safety data were also recorded.

RESULTS

Seventy patients were finally included in the analysis: 23 were treated with toripalimab, 33 with camrelizumab, and 14 with sintilimab. The mean duration of follow-up was 44.7 (95% CI: 39.9-49.6) weeks and the mean cycles of PD-1 at cutoff were 8.3±8.0 for all patients. The ORR and DCR for the whole cohort were 30% and 72.9%, respectively. Overall, 25 (35.7%) patients had radiological disease progression and 10 (14.3%) patients died during follow-up. Median PFS, median TTP, and median OS had not yet been reached. Most frequent drug-related adverse events (AEs) were rash (27.1%), hypertension (18.6%), fatigue (17.1%), diarrhea (17.1%), paresthesia (15.7%), and nausea (15.7%).

CONCLUSIONS

Our findings suggest that (I) PD-1 targeted immunotherapy with toripalimab, camrelizumab, or sintilimab yielded a promising outcome in Chinese HBV patients with HCC and that (II) immunotherapy was well tolerated generally and had manageable side effects. This approach thus warrants further popularization and application in clinical practice.

Hepatitis B Virus Infection: Overview

Hepatitis B virus (HBV) is a DNA virus, belonging to the Hepadnaviridae family. It is a partially double-stranded DNA virus with a small viral genome (3.2 kb). Chronic HBV infection remains a global public health problem. If left untreated, chronic HBV infection can progress to end-stage liver disease, such as liver cirrhosis and hepatocellular carcinoma (HCC). In recent years, tremendous advances in the field of HBV basic and clinical research have been achieved, ranging from the HBV biological characteristics, immunopathogenesis, and animal models to the development of new therapeutic strategies and new drugs against HBV. In this overview, we begin with a brief history of HBV discovery and treatment milestones. We then briefly summarize the HBV research advances, which will be detailed in the following chapters.

Retrospective analysis of docetaxel in combination with ramucirumab for previously treated non-small cell lung cancer patients

Background

Current clinical trials demonstrated that combination regimens comprising chemotherapy and immunotherapy lead to better patient outcomes compared to chemotherapy alone as the first line of treatment for non-small cell lung cancer (NSCLC). In addition, the combination therapy of docetaxel (Doc) and ramucirumab (Ram) was considered one of the standard treatments for advanced or relapsed NSCLC patients. However, little is known about the therapeutic responders of this combination therapy among previously treated NSCLC patients. In the present study, we aimed to identify predictive factors for therapeutic response, including programmed death-ligand 1 (PD-L1) expression in tumors, for Doc treatment in combination with Ram.

Methods

We retrospectively analyzed a total of 135 advanced or relapsed NSCLC patients who were refractory to platinum-based chemotherapy at eleven institutions in Japan between July 2016 and November 2018.

Results

Our observations showed that PD-L1 expression in tumors is not associated with the efficacy of combined therapy of Doc and Ram in previously treated NSCLC patients. Analysis of the patient clinical profiles indicated that prior treatment with immune checkpoint inhibitors (ICIs) is a reliable predictor for the good progression-free survival (PFS) to this combination therapy (P=0.041).

Conclusions

Our retrospective study indicated that combination regimens comprising chemotherapy and ICIs followed by Doc and Ram could be an optimal therapeutic option for NSCLC patients regardless of the PD-L1 status of tumors. Further investigations are required to strengthen clinical evidence demonstrating the effectiveness of the combination therapy of Doc plus Ram in previously treated NSCLC patients.

Prognostic value of PD-1 and PD-L1 expression in patients with metastatic clear cell renal cell carcinoma

OBJECTIVE

In renal cell carcinoma (RCC), several prognostic biomarkers have been identified and are under investigation. Several reports have shown that the expression of programmed death 1 (PD-1) and its ligand PD-L1 is associated with poor outcome for patients with RCC. The present study is aimed at evaluating the expression of PD-1 and PD-L1 and to investigate their clinical and prognostic significance in patients with clear cell RCC (CCRCC) having received molecular targeted therapies. In addition, we also evaluated the relationship between the expression of PD-1 and PD-L1 and intratumoral tumor infiltrating lymphocytes (TILs).

METHODS

A total of 33 patients with metastatic CCRCC who underwent surgery and received molecular targeted therapies from March 2008 to April 2016 were retrospectively reviewed and analyzed. Tissue specimens from the patients were analyzed for PD-1 and PD-L1 expression by immunohistochemistry.

RESULTS

The median patient age was 64 years old (range=53-78). The majority of patients were male (81.8%). All Memorial Sloan Kettering Cancer Center risk groups were represented among the patients with 39.4% with favorable-, 51.5% with intermediate- and 9.1% with poor-risk. The expression of PD-1 and PD-L1 was observed in 16 (48.5%) and 9 (27.3%) patients, respectively. The expression of PD-1 and PD-L1 was associated with a larger primary renal tumor size, higher nuclear grade and sarcomatoid feature. Kaplan-Meier analysis revealed that no significant difference in progression free survival of first line molecular targeted therapy was found for PD-1 (P=0.2396) and PD-L1 (P=0.5919) expression. However, PD-1 expression has a significant worse impact on overall survival (OS) (P=0.0385), while for PD-L1 expression only a trend is seen for OS (P=0.1542). The patients with PD-1 and PD-L1 expression showed higher infiltration of CD4 (P<0.0001 and P<0.0001, respectively), CD8 (P=0.0328 and P=0.0044, respectively) and FOXP3 (P<0.0001 and P=0.0033, respectively) positive TILs.

CONCLUSION

PD-1 and PD-L1 expression is significantly associated with adverse clinicopathological features in CCRCC. Furthermore, PD-1 expression could be one of the biomarkers suggesting poor outcome in patients with metastatic CCRCC receiving molecular targeted therapies.

Characterization of Pattern Recognition Receptor Expression and Functionality in Liver Primary Cells and Derived Cell Lines

Different liver cell types are endowed with immunological properties, including cell-intrinsic innate immune functions that are important to initially control pathogen infections. However, a full landscape of expression and functionality of the innate immune signaling pathways in the major human liver cells is still missing. In order to comparatively characterize these pathways, we purified primary human hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells (LSEC), and Kupffer cells (KC) from human liver resections. We assessed mRNA and protein expression level of the major innate immune sensors, as well as checkpoint-inhibitor ligands in the purified cells, and found Toll-like receptors (TLR), RIG-I-like receptors, as well as several DNA cytosolic sensors to be expressed in the liver microenvironment. Amongst the cells tested, KC were shown to be most broadly active upon stimulation with PRR ligands emphasizing their predominant role in innate immune sensing the liver microenvironment. By KC immortalization, we generated a cell line that retained higher innate immune functionality as compared to THP1 cells, which are routinely used to study monocyte/macrophages functions. Our findings and the establishment of the KC line will help to understand immune mechanisms behind antiviral effects of TLR agonists or checkpoint inhibitors, which are in current preclinical or clinical development.

Clinicopathological and prognostic significance of PD-L1 expression in sarcoma: A systematic review and meta-analysis

Programmed cell death-ligands 1 (PD-L1) is a key immune checkpoint protein and a promising therapeutic target for malignancy tumor immunotherapy. The prognostic value of PD-L1 in patients with bone and soft tissue sarcoma remains controversial. Therefore, this meta-analysis is conducted to evaluate the associations of PD-L1 expression with overall survival (OS), progression-free survival (PFS), and clinicopathological characteristics of sarcomaA comprehensive literature search of PubMed, Web of Science, Embase, and Cochrane Library was conducted for relevant studies. A total of 14 studies published from 2013 to 2017 were included. The pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were extracted from included studies to assess the association between PD-L1 expression and OS, PFS of patients with sarcoma. Other relevant data were extracted to evaluate the correlations of PD-L1 expression with risk and clinicopathological characteristics of sarcoma. Stata 12.0 software was applied to calculate the strength of association between PD-L1 expression and sarcoma.In total, 14 articles containing 15 independent studies and 1,451 patients were included in this meta-analysis. We found that the high PD-L1 expression was associated with poorer overall survival (HR 1.27, 95% CI: 0.70-1.84 P = .000) and poorer events-free survival (HR 2.05, 95% CI: 1.55-2.70, P = .000) in bone and soft-tissue sarcoma patients. Additionally, we conducted subgroup analysis according to histology type, ethnicity, target of PD-L1 assessment, cutoff, the significant correlations with poor overall survival and events-free survival were also observed. In contrast none of the clinicopathological characteristics (gender, age, tumor site, tumor grade, tumor depth, tumor necrosis rate, metastasis, recurrence, chemotherapy, radiotherapy) was found to be associated with PD-L1 expression in our analysis.The findings from this meta-analysis indicate that PD-L1 expression might be a useful predicative factor of poor prognosis for patients with bone and soft tissue sarcoma.

Hyper-Expression of PD-1 Is Associated with the Levels of Exhausted and Dysfunctional Phenotypes of Circulating CD161++TCR iVα7.2+ Mucosal-Associated Invariant T Cells in Chronic Hepatitis B Virus Infection

Mucosal-associated invariant T (MAIT) cells, defined as CD161⁺⁺TCR iVα7.2⁺ T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection. The peripheral CD3⁺CD161⁺⁺TCR iVα7.2⁺ MAIT cells in chronic HBV-infected patients and healthy controls were phenotypically characterized based on CD57, PD-1, TIM-3, and CTLA-4, as well as HLA-DR and CD38 expression. The frequency of MAIT cells was significantly decreased among chronic HBV-infected individuals as compared to controls. Expression of CD57, PD-1, CTLA-4, as well as HLA-DR and CD38 on MAIT cells was significantly elevated in chronic HBV-infected individuals relative to controls. The percentage of T cell receptor (TCR) iVα7.2⁺ CD161⁺ MAIT cells did not correlate with HBV viral load but inversely with HLA-DR on CD4⁺ T cells and MAIT cells and with CD57 on CD8⁺ T cells suggesting that decrease of MAIT cells may not be attributed to direct infection by HBV but driven by HBV-induced chronic immune activation. The percentage and expression levels of PD-1 as well as CTLA-4 on MAIT cells inversely correlated with plasma HBV-DNA levels, which may suggest either a role for MAIT cells in the control of HBV infection or the effect of HBV replication in the liver on MAIT cell phenotype. We report that decrease of TCR iVα7.2⁺ MAIT cells in the peripheral blood and their functions were seemingly impaired in chronic HBV-infected patients likely because of the increased expression of PD-1.

Mechanisms of Hepatitis B Virus Persistence

Hepatitis B virus (HBV) chronically infects 250 million people worldwide, resulting in nearly one million deaths annually. Studies in recent years have significantly improved our knowledge on the mechanisms of HBV persistence. HBV uses multiple pathways to harness host innate immunity to enhance its replication. It can also take advantage of the developing immune system and the not-yet-stabilized gut microbiota of young children to facilitate its persistence, and use maternal viral e antigen to educate immunity of the offspring to support its persistence after vertical transmission. The knowledge gained from these recent studies paves the way for the development of new therapies for the treatment of chronic HBV infection, which has so far been very challenging.

PD-L1 Expression Is Associated with FOXP3+ Regulatory T-Cell Infiltration of Soft Tissue Sarcoma and Poor Patient Prognosis

Background: Programmed death ligand-1(PD-L1) functions as a negative mediator of immune response through different pathways in anti-tumor immunity. Recent studies have reported that PD-L1 plays a pivotal role in the function of regulatory T-cells (Tregs). Although increases in FOXP3+ Tregs infiltration and PD-L1 expression have been revealed in several cancers, their correlation with soft tissue sarcoma remains unknown.

Methods: We included 163 cases of soft tissue sarcoma who were diagnosed and underwent extensive and radical resection at the Sun Yat-sen University Cancer Center, Guangzhou, China, from 2000-2010. PD-L1 and FOXP3 expression was evaluated by immunohistochemistry. Correlation between their expressions and associations with clinicopathological features were studied.

Results: Among 163 STS samples, 19 (11.7%) exhibited PD-L1 positivity, and 41 (25.2%) cases expressed high FOXP3+ Treg infiltration. Significant correlation between PD-L1 expression and FOXP3+Treg infiltration in STS was identified (r=0.450, p<0.001). In univariate analysis, PD-L1 expression was significantly associated with high tumor grade and the age of patients, while the presence of FOXP3+ in tumor infiltrating Tregs was significantly associated with the age of patients, high tumor stage, higher tumor grade and tumor depth. Multivariate analysis revealed PD-L1 and FOXP3 as independent prognostic indicators significantly associated with OS and DFS.

Conclusions: Our study revealed that PD-L1 and FOXP3+Tregs may work synergistically in promoting immune evasion of the tumors in soft tissue sarcoma. A combined strategy to block PD-L1/PD-1 with simultaneous depletion of Tregs may show promise in enhancing the therapeutic efficacy of these patients.

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.

Features of Memory-Like and PD-1(+) Human NK Cell Subsets

Human NK cells are distinguished into CD56^brightCD16⁻ cells and CD56^dimCD16⁺ cells. These two subsets are conventionally associated with differential functional outcomes and are heterogeneous with respect to the expression of KIR and CD94/NKG2 heterodimers that represent the two major types of HLA-class I-specific receptors. Recent studies indicated that immature CD56^bright NK cells, homogeneously expressing the inhibitory CD94/NKG2A receptor, are precursors of CD56^dim NK cells that, in turn, during their process of differentiation, lose expression of CD94/NKG2A and subsequentially acquire inhibitory KIRs and LIR-1. The terminally differentiated phenotype of CD56^dim cells is marked by the expression of the CD57 molecule that is associated with poor responsiveness to cytokine stimulation, but retained cytolytic capacity. Remarkably, this NKG2A⁻KIR⁺LIR-1⁺CD57⁺CD56^dim NK cell subset when derived from individuals previously exposed to pathogens, such as human cytomegalovirus (HCMV), may contain “memory-like” NK cells. These cells are generally characterized by an upregulation of the activating receptor CD94/NKG2C and a downregulation of the inhibitory receptor Siglec-7. The “memory-like” NK cells are persistent over time and display some hallmarks of adaptive immunity, i.e., clonal expansion, more effective antitumor and antiviral immune responses, longevity, as well as given epigenetic modifications. Interestingly, unknown cofactors associated with HCMV infection may induce the onset of a recently identified fully mature NK cell subset, characterized by marked downregulation of the activating receptors NKp30 and NKp46 and by the unexpected expression of the inhibitory PD-1 receptor. This phenotype correlates with an impaired antitumor NK cell activity that can be partially restored by antibody-mediated disruption of PD-1/PD-L interaction.

Specific CD8+ T cell response immunotherapy for hepatocellular carcinoma and viral hepatitis

Hepatocellular carcinoma (HCC), chronic hepatitis B (CHB) and chronic hepatitis C (CHC) are characterized by exhaustion of the specific CD8⁺ T cell response. This process involves enhancement of negative co-stimulatory molecules, such as programmed cell death protein-1 (PD-1), cytotoxic T-lymphocyte antigen-4 (CTLA-4), 2B4, Tim-3, CD160 and LAG-3, which is linked to intrahepatic overexpression of some of the cognate ligands, such as PD-L1, on antigen presenting cells and thereby favouring a tolerogenic environment. Therapies that disrupt these negative signalling mechanisms represent promising therapeutic tools with the potential to restore reactivity of the specific CD8⁺ T cell response. In this review we discuss the impressive in vitro and in vivo results that have been recently achieved in HCC, CHB and CHC by blocking these negative receptors with monoclonal antibodies against these immune checkpoint modulators. The article mainly focuses on the role of CTLA-4 and PD-1 blocking monoclonal antibodies, the first ones to have reached clinical practice. The humanized monoclonal antibodies against CTLA-4 (tremelimumab and ipilimumab) and PD-1 (nivolumab and pembrolizumab) have yielded good results in testing of HCC and chronic viral hepatitis patients. Trelimumab, in particular, has shown a significant increase in the time to progression in HCC, while nivolumab has shown a remarkable effect on hepatitis C viral load reduction. The research on the role of ipilimumab, nivolumab and pembrolizumab on HCC is currently underway.

Increased CD86 but Not CD80 and PD-L1 Expression on Liver CD68+ Cells during Chronic HBV Infection

BACKGROUND

The failure to establish potent anti-HBV T cell responses suggests the absence of an effective innate immune activation. Kupffer cells and liver-infiltrating monocytes/macrophages have an essential role in establishing anti-HBV responses. These cells express the costimulatory molecules CD80 and CD86. CD80 expression on antigen-presenting cells (APCs) induces Th1 cell differentiation, whereas CD86 expression drives the differentiation towards a Th2 profile. The relative expression of CD80, CD86 and PD-L1 on APCs, regulates T cell activation. Few studies investigated CD80 and CD86 expression on KCs and infiltrating monocytes/macrophages in HBV-infected liver and knowledge about the expression of PD-L1 on these cells is controversial. The expression of these molecules together in CD68+ cells has not been explored in HBV-infected livers.

METHODS

Double staining immunohistochemistry was applied to liver biopsies of HBV-infected and control donors to explore CD80, CD86 and PD-L1 expression in the lobular and portal areas.

RESULTS

Chronic HBV infection was associated with increased CD68+CD86+ cell count and percentage in the lobular areas, and no changes in the count and percentage of CD68+CD80+ and CD68+PD-L1+ cells, compared to the control group. While CD68+CD80+ cell count in portal areas correlated with the fibrosis score, CD68+CD80+ cell percentage in lobular areas correlated with the inflammation grade.

CONCLUSION

The upregulation of CD86 but not CD80 and PD-L1 on CD68+ cells in HBV-infected livers, suggests that these cells do not support the induction of potent Th1. Moreover, the expression of CD80 on CD68+ cells correlates with liver inflammation and fibrosis.

Identification of a subset of human natural killer cells expressing high levels of programmed death 1: A phenotypic and functional characterization

BACKGROUND

Programmed death 1 (PD-1) is an immunologic checkpoint that limits immune responses by delivering potent inhibitory signals to T cells on interaction with specific ligands expressed on tumor/virus-infected cells, thus contributing to immune escape mechanisms. Therapeutic PD-1 blockade has been shown to mediate tumor eradication with impressive clinical results. Little is known about the expression/function of PD-1 on human natural killer (NK) cells.

OBJECTIVE

We sought to clarify whether human NK cells can express PD-1 and analyze their phenotypic/functional features.

METHODS

We performed multiparametric cytofluorimetric analysis of PD-1⁺ NK cells and their functional characterization using degranulation, cytokine production, and proliferation assays.

RESULTS

We provide unequivocal evidence that PD-1 is highly expressed (PD-1^bright) on an NK cell subset detectable in the peripheral blood of approximately one fourth of healthy subjects. These donors are always serologically positive for human cytomegalovirus. PD-1 is expressed by CD56^dim but not CD56^bright NK cells and is confined to fully mature NK cells characterized by the NKG2A^-KIR⁺CD57⁺ phenotype. Proportions of PD-1^bright NK cells were higher in the ascites of a cohort of patients with ovarian carcinoma, suggesting their possible induction/expansion in tumor environments. Functional analysis revealed a reduced proliferative capability in response to cytokines, low degranulation, and impaired cytokine production on interaction with tumor targets.

CONCLUSIONS

We have identified and characterized a novel subpopulation of human NK cells expressing high levels of PD-1. These cells have the phenotypic characteristics of fully mature NK cells and are increased in patients with ovarian carcinoma. They display low proliferative responses and impaired antitumor activity that can be partially restored by antibody-mediated disruption of PD-1/programmed death ligand interaction.

Chronic Hepatitis B with Spontaneous Severe Acute Exacerbation

Chronic hepatitis B virus (HBV) infection is a major global health problem with an estimated 400 million HBV carriers worldwide. In the natural history of chronic hepatitis B (CHB), spontaneous acute exacerbation (AE) is not uncommon, with a cumulative incidence of 10%–30% every year. While exacerbations can be mild, some patients may develop hepatic decompensation and even die. The underlying pathogenesis is possibly related to the activation of cytotoxic T lymphocyte-mediated immune response against HBV. An upsurge of serum HBV DNA usually precedes the rise of alanine aminotransferase (ALT) and bilirubin. Whether antiviral treatment can benefit CHB with severe AE remains controversial, but early nucleos(t)ide analogues treatment seemed to be associated with an improved outcome. There has been no randomized study that compared the effects of different nucleos(t)ide analogues (NA) in the setting of CHB with severe AE. However, potent NAs with good resistance profiles are recommended. In this review, we summarized current knowledge regarding the natural history, pathogenetic mechanisms, and therapeutic options of CHB with severe AE.

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.

Hepatitis B flares in chronic hepatitis B: pathogenesis, natural course, and management

Hepatitis B flare, defined as an event with abrupt rise of alanine aminotransferase (ALT) levels to >5 times the upper limit of normal during chronic hepatitis B virus (HBV) infection, is considered to be the result of a human leukocyte antigen-I restricted, cytotoxic T lymphocyte mediated immune response against HBV and its downstream mechanisms. It may occur spontaneously, during or after antiviral therapy and in the setting of immunosuppression and/or chemotherapy. The clinical spectrum of hepatitis B flares varies from asymptomatic to symptomatic and typical overt acute hepatitis, even with hepatic decompensation or failure. Flares may also occur in viraemic patients with cirrhosis with higher incidence of decompensation/mortality, hence requiring immediate antiviral therapy. An upsurge of serum HBV DNA and hepatitis B surface antigen levels usually precedes the abrupt rise of ALT levels. Rising or stable and high HBV DNA during flares represent ineffective immune clearance and further hepatocytolysis, even hepatic decompensation, may occur. Such patients require immediate antiviral therapy. In contrast, bridging hepatic necrosis and/or alpha-fetoprotein levels >100 ng/ml or decreasing HBV DNA during flares represent a more effective immune clearance and frequently leads to seroclearance of HBV DNA and/or hepatitis B e antigen with remission. If patients are non-cirrhotic and there is no concern of developing decompensation, patients may be observed for 3-6 months before deciding on the need of antiviral therapy. Severe and repeated flares are prone to develop into decompensation or lead to the development of cirrhosis, thus a timely treatment to prevent the hepatitis B flare is better than to cope with the flare. Screening, monitoring and prophylactic or pre-emptive antiviral therapy is mandatory for patients who are going to receive immunosuppressants or chemotherapy.

Correlation between infiltration of FOXP3+ regulatory T cells and expression of B7-H1 in the tumor tissues of gastric cancer

BACKGROUND

Substantial evidence suggests that the expansion of regulatory T cells (T(regs)) plays a pivotal role in immunological evasion of tumors. Recent studies have demonstrated that a majority of tumor cells overexpress B7-H1, and this overexpression is associated with poor disease prognosis. Although an increase of T(regs) and B7-H1 has been revealed in several malignancies, their correlation in gastric cancer has not been studied.

METHODS

Tumor sections from 111 gastric cancer patients were stained for FOXP3 and B7-H1 by immunohistochemistry. The expression levels of these two molecules were statistically associated with various factors involved in disease progression and prognosis. The correlation between their expression levels was analyzed.

RESULTS

The infiltration of FOXP3(+) T(regs) and expression of B7-H1 were observed in gastric cancer tissues, and there was a highly significant correlation between these two molecules (P < 0.01). The expression of FOXP3(+) T(regs) and B7-H1 was associated with lymph node metastasis and the clinicopathological stage and prognosis of gastric cancer patients. The expression levels of these two determinants in patients with lymph node metastasis and an advanced clinicopathological stage were distinctly higher (P < 0.05). The patients with enhanced expression of FOXP3(+) T(regs) and B7-H1 exhibited a lower overall survival rate and a worse prognosis (P < 0.05).

CONCLUSIONS

Increased expression of FOXP3(+) T(regs) and B7-H1 was observed in gastric cancer tissues; the two molecules were closely correlated with each other, suggesting that they might be used as new biomarkers to predict the disease progression and prognosis. Combinatorial immunotherapeutic approaches based on depleting the T(regs) and blocking B7-H1 might improve therapeutic efficacy in gastric cancer.