Deregulated intracellular pathways define novel molecular targets for HBV-specific CD8 T cell reconstitution in chronic hepatitis B

Viral oncogenesis in cancer: from mechanisms to therapeutics

The year 2024 marks the 60th anniversary of the discovery of the Epstein-Barr virus (EBV), the first virus confirmed to cause human cancer. Viral infections significantly contribute to the global cancer burden, with seven known Group 1 oncogenic viruses, including hepatitis B virus (HBV), human papillomavirus (HPV), EBV, Kaposi sarcoma-associated herpesvirus (KSHV), hepatitis C virus (HCV), human T-cell leukemia virus type 1 (HTLV-1), and human immunodeficiency virus (HIV). These oncogenic viruses induce cellular transformation and cancer development by altering various biological processes within host cells, particularly under immunosuppression or co-carcinogenic exposures. These viruses are primarily associated with hepatocellular carcinoma, gastric cancer, cervical cancer, nasopharyngeal carcinoma, Kaposi sarcoma, lymphoma, and adult T-cell leukemia/lymphoma. Understanding the mechanisms of viral oncogenesis is crucial for identifying and characterizing the early biological processes of virus-related cancers, providing new targets and strategies for treatment or prevention. This review first outlines the global epidemiology of virus-related tumors, milestone events in research, and the process by which oncogenic viruses infect target cells. It then focuses on the molecular mechanisms by which these viruses induce tumors directly or indirectly, including the regulation of oncogenes or tumor suppressor genes, induction of genomic instability, disruption of regular life cycle of cells, immune suppression, chronic inflammation, and inducing angiogenesis. Finally, current therapeutic strategies for virus-related tumors and recent advances in preclinical and clinical research are discussed.

Molecular mechanisms of viral oncogenesis in haematological malignancies: perspectives from metabolic reprogramming, epigenetic regulation and immune microenvironment remodeling

Haematological malignancies are one of the most common tumors, with a rising incidence noted over recent decades. Viral infections play significant roles in the pathogenesis of these malignancies globally. This review delves into the contributions of various known viruses-specifically Epstein-Barr virus (EBV), human immunodeficiency virus (HIV), human T-cell leukemia virus type 1 (HTLV-1), Kaposi's sarcoma-associated herpesvirus (KSHV), human cytomegalovirus (HCMV), hepatitis B virus (HBV), hepatitis C virus (HCV), and human papillomavirus (HPV)-in the development of haematological malignancies. These viruses are shown to drive tumorigenesis through mechanisms, such as metabolic reprogramming, epigenetic modifications, and remodeling of the immune microenvironment. By directly disrupting fundamental cellular functions and altering metabolic and epigenetic pathways, these viruses foster an immune milieu that supports both viral persistence and tumor growth. A thorough understanding of these viral oncogenic processes is crucial not only for etiological discovery but also for developing targeted interventions. This review emphasizes the need for continued research into the specific ways these viruses manipulate the host cell's metabolic and epigenetic environments, aiming to provide insights that could guide future advancements in treatment modalities.

FTY720 alleviates HBV-mediated inflammatory liver injury through a dual role of inhibiting lymphocyte trafficking and viral replication

BACKGROUND

The host immune response plays a critical role in clearing hepatitis B virus infection. However, in chronic hepatitis B, this response fails to eliminate the virus, leading to recurrent inflammation, liver tissue damage, and a gradual progression from hepatitis to fibrosis, and eventually, hepatocellular carcinoma. Reducing liver injury while enhancing antiviral efficacy remains a key objective in hepatitis B virus treatment development. Our previous research revealed a close association between hepatitis B virus infection and the sphingosine 1-phosphate signaling pathway. Consequently, this study aims to explore the dual role of FTY720, an immune modulator that targets sphingosine- 1-phosphate receptor, in hepatitis B virus-related liver injury.

METHODS

In this study, The peripheral blood leukocyte count and the expression of sphingosine 1-phosphate receptor on lymphocytes were compared between chronic hepatitis B patients and healthy controls. In vitro experiments were conducted to evaluate the direct antiviral effects of FTY720 on two hepatitis B virus models: HepG2.2.15 and Huh7 cells transfected with pUC19-HBV1.3. Additionally, the study investigated the influence of FTY720 on the chemotaxis of peripheral blood mononuclear cells induced by the supernatant of hepatitis B virus-infected HepG2-NTCP cells. An in vivo model using hepatitis B virus hyperbaric hydrodynamic injection in mice was also employed to assess the impact of FTY720 on both HBV replication and hepatic lymphocyte infiltration.

RESULTS

Peripheral blood lymphocyte counts were reduced, while sphingosine 1-phosphate receptor expression was elevated in chronic hepatitis B patients compared to healthy controls. Simultaneously, antiviral therapy solely utilizing nucleotide analogues could not fully restore the peripheral blood lymphocyte count in patients with chronic hepatitis B. In vitro, FTY720 effectively inhibited hepatitis B virus replication in two models: HepG2.2.15 cells containing hepatitis B virus virions and pUC19-HBV1.3-transfected Huh7 cells. Furthermore, supernatants from hepatitis B virus-infected HepG2-NTCP cells induced increased lymphocyte chemotaxis, which was suppressed by FTY720. In a hepatitis B virus mouse model, FTY720 significantly reduced viral DNA and protein levels, while also decreasing inflammatory hepatocyte necrosis, liver lymphocyte infiltration, and sphingosine 1-phosphate receptor expression on circulating lymphocytes.

CONCLUSIONS

These findings suggest that FTY720 can inhibit both hepatitis B virus replication and hepatitis B virus-related liver damage by modulating lymphocyte migration. Further investigation into the specific mechanisms underlying the interaction between FTY720 and hepatitis B virus is warranted.

Nicotinamide mononucleotide promotes female germline stem cell proliferation by activating the H4K16ac-Hmgb1-Fyn-PLD signaling pathway through epigenetic remodeling

BACKGROUND

Nicotinamide mononucleotide (NMN), an endogenous nucleotide essential for various physiological processes, has an unclear role and regulatory mechanisms in female germline stem cell (FGSC) development.

RESULTS

We demonstrate that NMN significantly enhances FGSC viability and proliferation. Quantitative acetylation proteomics revealed that NMN markedly increases the acetylation of histone H4 at lysine 16 (H4K16ac). Subsequent chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) identified high mobility group box 1 (Hmgb1) as a downstream target of H4K16ac, a finding further validated by ChIP-qPCR. Knockdown of Hmgb1 reduced FGSC proliferation by disrupting cell cycle progression, inducing apoptosis, and decreasing chromatin accessibility. High-throughput chromosome conformation capture (Hi-C) analysis showed that Hmgb1 knockdown induced A/B compartment switching, increased the number of topologically associating domains (TADs), and decreased chromatin loop formation in FGSCs. Notably, the chromatin loop at the promoter region of Fyn proto-oncogene (Fyn) disappeared following Hmgb1 knockdown. ChIP-qPCR and dual-luciferase reporter assays further confirmed the interaction between Hmgb1 and the Fyn promoter. Importantly, Fyn overexpression reversed the inhibitory effects of Hmgb1 knockdown on FGSC proliferation. Proteomic analysis suggested this rescue was mediated through the phospholipase D (PLD) signaling pathway, as Fyn overexpression selectively enhanced the phosphorylation of PLD1 at threonine 147 without affecting serine 561. Furthermore, treatment with 5-fluoro-2-indolyldechlorohaloamide, a PLD inhibitor, nullified the pro-proliferative effects of Fyn overexpression.

CONCLUSIONS

Our findings reveal that NMN promotes FGSC proliferation by activating the H4K16ac-Hmgb1-Fyn-PLD signaling pathway through epigenetic remodeling. These results deepen our understanding of FGSC proliferation and highlight potential therapeutic avenues for advancing FGSC applications in reproductive medicine.

PGLYRP2 drives hepatocyte-intrinsic innate immunity by trapping and clearing hepatitis B virus

Spontaneous clearance of hepatitis B virus (HBV) is frequent in adults (95%) but rare in infants (5%), emphasizing the critical role of age-related hepatic immunocompetence. However, the underlying mechanisms of hepatocyte-specific immunosurveillance and age-dependent HBV clearance remain unclear. Here, we identified PGLYRP2 as a hepatocyte-specific pattern recognition receptor with age-dependent expression, and demonstrated that phase separation of PGLYRP2 was a critical driver of spontaneous HBV clearance in hepatocytes. Mechanistically, PGLYRP2 recognized and potentially eliminated covalently closed circular DNA via phase separation, coordinated by its intrinsically disordered region and HBV DNA-binding domain (PGLYRP2IDR/209-377) in the nucleus. Additionally, PGLYRP2 suppressed HBV capsid assembly by directly interacting with the viral capsid, mediated by its PGRP domain. This interaction promoted the nucleocytoplasmic translocation of PGLYRP2 and subsequent secretion of the PGLYRP2/HBV capsid complex, thereby bolstering the hepatic antiviral response. Pathogenic variants or deletions in PGLYRP2 impaired its ability to inhibit HBV replication, highlighting its essential role in hepatocyte-intrinsic immunity. These findings suggest that targeting the PGLYRP2-mediated host-virus interaction may offer a potential therapeutic strategy for the development of anti-HBV treatments, representing a promising avenue for achieving a functional cure for HBV infection.

Decoding NAD+ Metabolism in COVID-19: Implications for Immune Modulation and Therapy

The persistent threat of COVID-19, particularly with the emergence of new variants, underscores the urgency for innovative therapeutic strategies beyond conventional antiviral treatments. Current immunotherapies, including IL-6/IL-6R monoclonal antibodies and JAK inhibitors, exhibit suboptimal efficacy, necessitating alternative approaches. Our review delves into the significance of NAD+ metabolism in COVID-19 pathology, marked by decreased NAD+ levels and upregulated NAD+-consuming enzymes such as CD38 and poly (ADP-ribose) polymerases (PARPs). Recognizing NAD+'s pivotal role in energy metabolism and immune modulation, we propose modulating NAD+ homeostasis could bolster the host's defensive capabilities against the virus. The article reviews the scientific rationale behind targeting NAD+ pathways for therapeutic benefit, utilizing strategies such as NAD+ precursor supplementation and enzyme inhibition to modulate immune function. While preliminary data are encouraging, the challenge lies in optimizing these interventions for clinical use. Future research should aim to unravel the intricate roles of key metabolites and enzymes in NAD+ metabolism and to elucidate their specific mechanisms of action. This will be essential for developing targeted NAD+ therapies, potentially transforming the management of COVID-19 and setting a precedent for addressing other infectious diseases.

The immune response in chronic HBV infection

Hepatitis B virus (HBV) is an ancient virus that has evolved unique strategies to persist as a chronic infection in humans. Here, I summarize the innate and adaptive features of the HBV-host interaction, and I discuss how different profiles of antiviral immunity cannot be predicted only on the basis of virological and clinical parameters.

Altered mitochondrial mass and low mitochondrial membrane potential of immune cells in patients with HBV infection and correlation with liver inflammation

Introduction

Mitochondrial membrane potential (MMP) and mitochondrial mass (MM) affect mitochondrial function and lymphocyte activation, but few studies on HBV infection exist. This study aimed to investigate the regulatory mechanism of mitochondrial dysfunction during HBV infection and its clinical significance by analyzing the alterations of MM and MMPlow in peripheral blood immune cells.

Methods

The study enrolled 90 participants, including healthy volunteers(HC) and patients with HBV infection, HBV patients were divided into chronic hepatitis B patients (CHB) and liver cirrhosis (LC) according to the study, and CHB was also divided into an inflammation group and a non-inflammation group. Flow cytometry was used to analyze the changes of MM and MMPlow in peripheral blood immune cells. These analyses were correlated with the presence of CHB and LC and indexes related to liver inflammation.

Results

The study revealed significant variations in the percentage of MMPlow and MM of CD8+T cells associated with the progression of the disease. The MMPlow percentage of CD8+T cells in the LC group exhibited a notable decrease compared to the HC group and CHB groups. Moreover, MMPlow of CD8+T cells demonstrated potential in distinguishing CHB and LC (AUC=0.7341, P=0.0032). Furthermore, in exploring the link between mitochondrial function of immune cells and liver inflammation, the study found a negative correlation between the MMPlow ratio of CD4+T and CD8+T cells and AST (p=0.0039 and P=0.0070, r=-0.4405 and r=-0.4146), while the MM of CD8+T cells displayed a positive correlation with AST (p=0.0013, r=0.4865). In CHB patients with normal ALT but liver inflammation detected on B-scan ultrasonography, a significant decrease was observed in the MMPlow percentage of CD8+T (66.13 ± 14.27), CD56+NK(57.77 ± 17.40) and CD4-CD8-T (61.98 ± 15.98) cells. Furthermore, it was also found that the percentage of MMPlow in CD4-CD8-T cells could serve as an indicator for early liver inflammation and injury (AUC=0.8408, P=0.0052).

Discussion

In this study, we conducted a systematic analysis of the percentage of lymphocyte MMPlow and MM in various stages of HBV infection. Our findings revealed a correlation between MMPlow and MM and early liver inflammation, as well as the progression of the infection. This study marked the first demonstration of the clinical diagnostic value of MMPlow and MM in HBV infection. Furthermore, this was the first study to discuss the mitochondria of lymphocytes and liver inflammation in HBV infection. It enhanced the understanding of the role of T cells in liver inflammation, and elucidated potential markers for the early detection of liver injury and clinical cirrhosis.

Optimization of culture conditions for HBV-specific T cell expansion in vitro from chronically infected patients

BACKGROUND

Hepatitis B virus (HBV) clearance depends on an effective adaptive immune response, especially HBV-specific T cell-mediated cellular immunity; however, it is difficult to produce enough HBV-specific T cells effectively.

RESULTS

In this work, we investigated the proportions of stimulated cells, serum, and culture media as the three primary factors to determine the most effective procedure and applied it to HLA-A2 (+) people. In parallel, we also examined the correlation between clinical parameters and HBV-specific immunity. Concerning amplification efficiency, 4 × 105 cells stimulation was superior to 2 × 106 cells stimulation, AIM-V medium outperformed 1640 medium, and fetal bovine serum (FBS) exceeded human AB serum under comparable conditions. As expected, this procedure is also suitable for developing HBV-specific CD8 + T cells in HLA-A2(+) individuals. Expanded HBV-specific T cell responses decreased with treatment time and were negatively correlated with HBV DNA and HBsAg. Furthermore, the number of HBV-specific IFN-γ + SFCs was strongly correlated with the ALT level and negatively correlated with the absolute lymphocyte count and the ALB concentration.

CONCLUSIONS

We confirm that stimulating 4 × 105 PBMCs in AIM-V medium supplemented with 10% FBS is the best approach and that HBeAg, HBsAg, and ALB are independent predictors of HBV-specific T-cell responses.

Inhibition of CD38 enzymatic activity enhances CAR-T cell immune-therapeutic efficacy by repressing glycolytic metabolism

Chimeric antigen receptor (CAR)-T therapy has shown superior efficacy against hematopoietic malignancies. However, many patients failed to achieve sustainable tumor control partially due to CAR-T cell exhaustion and limited persistence. In this study, by performing single-cell multi-omics data analysis on patient-derived CAR-T cells, we identify CD38 as a potential hallmark of exhausted CAR-T cells, which is positively correlated with exhaustion-related transcription factors and further confirmed with in vitro exhaustion models. Moreover, inhibiting CD38 activity reverses tonic signaling- or tumor antigen-induced exhaustion independent of single-chain variable fragment design or costimulatory domain, resulting in improved CAR-T cell cytotoxicity and antitumor response. Mechanistically, CD38 inhibition synergizes the downregulation of CD38-cADPR -Ca2+ signaling and activation of the CD38-NAD+-SIRT1 axis to suppress glycolysis. Collectively, our findings shed light on the role of CD38 in CAR-T cell exhaustion and suggest potential clinical applications of CD38 inhibition in enhancing the efficacy and persistence of CAR-T cell therapy.

Regulation of Mitochondrial Metabolism by Hepatitis B Virus

Mitochondria play important roles in the synthesis of ATP, the production of reactive oxygen species, and the regulation of innate immune response and apoptosis. Many viruses perturb mitochondrial activities to promote their replication and cause cell damage. Hepatitis B virus (HBV) is a hepatotropic virus that can cause severe liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). This virus can also alter mitochondrial functions and metabolism to promote its replication and persistence. In this report, we summarize recent research progress on the interaction between HBV and mitochondrial metabolism, as well as the effect this interaction has on HBV replication and persistence.

What Is the Current Status of Hepatitis B Virus Viro-Immunology?

The natural history of hepatitis B virus (HBV) infection is closely dependent on the dynamic interplay between the host immune response and viral replication. Spontaneous HBV clearance in acute self-limited infection is the result of an adequate and efficient antiviral immune response. Instead, it is widely recognized that in chronic HBV infection, immunologic dysfunction contributes to viral persistence. Long-lasting exposure to high viral antigens, upregulation of multiple co-inhibitory receptors, dysfunctional intracellular signaling pathways and metabolic alterations, and intrahepatic regulatory mechanisms have been described as features ultimately leading to a hierarchical loss of effector functions up to full T-cell exhaustion.