Oxidative stress enables Epstein-Barr virus-induced B-cell transformation by posttranscriptional regulation of viral and cellular growth-promoting factors

From infection to infertility: a review of the role of human papillomavirus-induced oxidative stress on reproductive health and infertility

Infertility has emerged as a significant global health concern, affecting nearby 8-12% of couples in reproductive age worldwide. Increasing evidence suggests a potential link between human papillomavirus (HPV) and infertility in both men and women. Some research indicate that HPV can infect various components of semen, potentially affecting sperm quality by decreasing motility, viability, and increasing DNA fragmentation, all of which may contribute to male infertility. The virus can attach to the equatorial region of the sperm head, enabling infected sperm to transmit the virus to the oocyte or placenta. Consequently, HPV potentially induces apoptosis in trophoblastic cells and disrupts their adhesion to endometrial cells, which raises the risk of miscarriage. HPV may also affect ovarian reserve by causing chronic inflammation, which can impair granulosa cell function and lower serum anti-Müllerian hormone (AMH) levels. Besides, HPV-related immune responses also contribute to infertility by producing anti-sperm antibodies (ASAs), which cause sperm clumping, reduce motility through cervical mucus, activate the complement system that damages sperm in the female reproductive tract and interfere with sperm-egg interactions. Moreover, HPV infection has been linked to reduced success rates in assisted reproductive technologies (ART), potentially disrupting critical processes such as the acrosome reaction, sperm-oocyte interaction, and fusion. One potential mechanism through which HPV contributes to infertility is oxidative stress (OS). Triggered OS can negatively impact sperm quality and cause damage to the female reproductive system, ultimately contributing to infertility. Despite these associations, the precise mechanisms and the strength of the relationship remain uncertain. Thus, this review seeks to investigate the potential impact of HPV on infertility, particularly its effects on the reproductive system through OS. A clearer understanding of these processes could inform future health strategies for addressing HPV-related infertility.

Epstein-Barr Virus-Driven B-Cell Transformation under Germinal Center Hypoxia Requires External Unsaturated Fatty Acids

Epstein-Barr virus (EBV) contributes to over 200,000 cancers annually, predominantly aggressive lymphomas originating from hypoxic germinal centers (< 1% O2). However, conventional models fail to recapitulate the physiologically relevant hypoxic microenvironment which profoundly influences B-cell metabolic remodeling during transformation. Here, we establish an ex vivo model of EBV-driven B-cell transformation under 1% O2, demonstrating robust transformation and super-enhancer activation of oncogenic regulators, including MYC. Multi-omic analyses reveal distinct metabolic adaptations to hypoxia. Unlike normoxic B-cells, which rely on fatty acid desaturases and oxidation to mitigate lipotoxicity, hypoxically transformed B-cells suppress fatty acid synthesis while upregulating glycerophospholipid metabolism and lipid droplet formation to buffer excess saturated lipids. Consequently, these cells exhibit heightened dependence on external unsaturated fatty acids to support proliferation. Our findings provide the first physiologically relevant ex vivo model of EBV-driven B-cell transformation under hypoxia, uncovering metabolic vulnerabilities that could inform targeted therapeutic strategies for EBV-associated malignancies.

RNA expression profiling in lymphoblastoid cell lines from mutated and non-mutated amyotrophic lateral sclerosis patients

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the death of upper and lower motor neurons with an unknown etiology. The difficulty of recovering biological material from patients led to employ lymphoblastoid cell lines (LCLs) as a model for ALS because many pathways, typically located in neurons, are also activated in these cells.

METHODS

To investigate the expression of coding and long non-coding RNAs in LCLs, a transcriptomic profiling of sporadic ALS (SALS) and mutated patients (FUS, TARDBP, C9ORF72 and SOD1) and matched controls was realized. Thus, differentially expressed genes (DEGs) were investigated among the different subgroups of patients. Peripheral blood mononuclear cells (PBMCs) were isolated and immortalized into LCLs via Epstein-Barr virus infection; RNA was extracted, and RNA-sequencing analysis was performed.

RESULTS

Gene expression profiles of LCLs were genetic-background-specific; indeed, only 12 genes were commonly deregulated in all groups. Nonetheless, pathways enriched by DEGs in each group were also compared, and a total of 89 Kyoto Encyclopedia of Genes and Genomes (KEGG) terms were shared among all patients. Eventually, the similarity of affected pathways was also assessed when our data were matched with a transcriptomic profile realized in the PBMCs of the same patients.

CONCLUSIONS

We conclude that LCLs are a good model for the study of RNA deregulation in ALS.

Germinal center cytokine driven epigenetic control of Epstein-Barr virus latency gene expression

Epstein-Barr virus (EBV) persistently infects 95% of adults worldwide and is associated with multiple human lymphomas that express characteristic EBV latency programs used by the virus to navigate the B-cell compartment. Upon primary infection, the EBV latency III program, comprised of six Epstein-Barr Nuclear Antigens (EBNA) and two Latent Membrane Protein (LMP) antigens, drives infected B-cells into germinal center (GC). By incompletely understood mechanisms, GC microenvironmental cues trigger the EBV genome to switch to the latency II program, comprised of EBNA1, LMP1 and LMP2A and observed in GC-derived Hodgkin lymphoma. To gain insights into pathways and epigenetic mechanisms that control EBV latency reprogramming as EBV-infected B-cells encounter microenvironmental cues, we characterized GC cytokine effects on EBV latency protein expression and on the EBV epigenome. We confirmed and extended prior studies highlighting GC cytokine effects in support of the latency II transition. The T-follicular helper cytokine interleukin 21 (IL-21), which is a major regulator of GC responses, and to a lesser extent IL-4 and IL-10, hyper-induced LMP1 expression, while repressing EBNA expression. However, follicular dendritic cell cytokines including IL-15 and IL-27 downmodulate EBNA but not LMP1 expression. CRISPR editing highlighted that STAT3 and STAT5 were necessary for cytokine mediated EBNA silencing via epigenetic effects at the EBV genomic C promoter. By contrast, STAT3 was instead necessary for LMP1 promoter epigenetic remodeling, including gain of activating histone chromatin marks and loss of repressive polycomb repressive complex silencing marks. Thus, EBV has evolved to coopt STAT signaling to oppositely regulate the epigenetic status of key viral genomic promoters in response to GC cytokine cues.

G. Germinal Center Cytokines Driven Epigenetic Control of Epstein-Barr Virus Latency Gene Expression

Epstein-Barr virus (EBV) persistently infects 95% of adults worldwide and is associated with multiple human lymphomas that express characteristic EBV latency programs used by the virus to navigate the B-cell compartment. Upon primary infection, the EBV latency III program, comprised of six Epstein-Barr Nuclear Antigens (EBNA) and two Latent Membrane Protein (LMP) antigens, drives infected B-cells into germinal center (GC). By incompletely understood mechanisms, GC microenvironmental cues trigger the EBV genome to switch to the latency II program, comprised of EBNA1, LMP1 and LMP2A and observed in GC-derived Hodgkin lymphoma. To gain insights into pathways and epigenetic mechanisms that control EBV latency reprogramming as EBV-infected B-cells encounter microenvironmental cues, we characterized GC cytokine effects on EBV latency protein expression and on the EBV epigenome. We confirmed and extended prior studies highlighting GC cytokine effects in support of the latency II transition. The T-follicular helper cytokine interleukin 21 (IL-21), which is a major regulator of GC responses, and to a lesser extent IL-4 and IL-10, hyper-induced LMP1 expression, while repressing EBNA expression. However, follicular dendritic cell cytokines including IL-15 and IL-27 downmodulate EBNA but not LMP1 expression. CRISPR editing highlighted that STAT3 and STAT5 were necessary for cytokine mediated EBNA silencing via epigenetic effects at the EBV genomic C promoter. By contrast, STAT3 was instead necessary for LMP1 promoter epigenetic remodeling, including gain of activating histone chromatin marks and loss of repressive polycomb repressive complex silencing marks. Thus, EBV has evolved to coopt STAT signaling to oppositely regulate the epigenetic status of key viral genomic promoters in response to GC cytokine cues.

The Research Progress on Immortalization of Human B Cells

Human B cell immortalization that maintains the constant growth characteristics and antibody expression of B cells in vitro is very critical for the development of antibody drugs and products for the diagnosis and bio-therapeutics of human diseases. Human B cell immortalization methods include Epstein-Barr virus (EBV) transformation, Simian virus 40 (SV40) virus infection, in vitro genetic modification, and activating CD40, etc. Immortalized human B cells produce monoclonal antibodies (mAbs) very efficiently, and the antibodies produced in this way can overcome the immune rejection caused by heterologous antibodies. It is an effective way to prepare mAbs and an important method for developing therapeutic monoclonal antibodies. Currently, the US FDA has approved more than 100 mAbs against a wide range of illnesses such as cancer, autoimmune diseases, infectious diseases, and neurological disorders. This paper reviews the research progress of human B cell immortalization, its methods, and future directions as it is a powerful tool for the development of monoclonal antibody preparation technology.

The master antioxidant defense is activated during EBV latent infection

IMPORTANCE

To our knowledge, this is the first report delineating the activation of the master antioxidant defense during EBV latency. We show that EBV-triggered reactive oxygen species production activates the Keap1-NRF2 pathway in EBV-transformed cells, and LMP1 plays a major role in this event, and the stress-related kinase TBK1 is required for NRF2 activation. Moreover, we show that the Keap1-NRF2 pathway is important for cell proliferation and EBV latency maintenance. Our findings disclose how EBV controls the balance between oxidative stress and antioxidant defense, which greatly improve our understanding of EBV latency and pathogenesis and may be leveraged to opportunities toward the improvement of therapeutic outcomes in EBV-associated diseases.

The Impact of Co-Infections for Human Gammaherpesvirus Infection and Associated Pathologies

The two oncogenic human gammaherpesviruses Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) cause significant disease burden, particularly in immunosuppressed individuals. Both viruses display latent and lytic phases of their life cycle with different outcomes for their associated pathologies. The high prevalence of infectious diseases in Sub-Saharan Africa (SSA), particularly HIV/AIDS, tuberculosis, malaria, and more recently, COVID-19, as well as their associated inflammatory responses, could potentially impact either virus' infectious course. However, acute or lytically active EBV and/or KSHV infections often present with symptoms mimicking these predominant diseases leading to misdiagnosis or underdiagnosis of oncogenic herpesvirus-associated pathologies. EBV and/or KSHV infections are generally acquired early in life and remain latent until lytic reactivation is triggered by various stimuli. This review summarizes known associations between infectious agents prevalent in SSA and underlying EBV and/or KSHV infection. While presenting an overview of both viruses' biphasic life cycles, this review aims to highlight the importance of co-infections in the correct identification of risk factors for and diagnoses of EBV- and/or KSHV-associated pathologies, particularly in SSA, where both oncogenic herpesviruses as well as other infectious agents are highly pervasive and can lead to substantial morbidity and mortality.

EBV and Lymphomagenesis

The clinical significance of Epstein–Barr virus (EBV) cannot be understated. Not only does it infect approximately 90% of the world’s population, but it is also associated with numerous pathologies. Diseases linked to this virus include hematologic malignancies such as diffuse large B-cell lymphoma, Hodgkin lymphoma, Burkitt lymphoma, primary CNS lymphoma, and NK/T-cell lymphoma, epithelial malignancies such as nasopharyngeal carcinoma and gastric cancer, autoimmune diseases such as multiple sclerosis, Graves’ disease, and lupus. While treatment for these disease states is ever evolving, much work remains to more fully elucidate the relationship between EBV, its associated disease states, and their treatments. This paper begins with an overview of EBV latency and latency-associated proteins. It will then review EBV’s contributions to select hematologic malignancies with a focus on the contribution of latent proteins as well as their associated management.

p62/SQSTM1 promotes mitophagy and activates the NRF2-mediated anti-oxidant and anti-inflammatory response restraining EBV-driven B lymphocyte proliferation

Reactive oxygen species (ROS) and DNA repair respectively promote and limit oncogenic transformation of B cells driven by Epstein-Barr virus (EBV). We have previously shown that EBV infection reduced autophagy in primary B lymphocytes and enhanced ROS and interleukin 6 (IL-6) release, promoting B cell proliferation and immortalization. In this study, we explored the role of p62/SQSTM1, accumulated as a consequence of autophagy reduction in EBV-infected B lymphocytes, and found that it exerted a growth suppressive effect in these cells. At molecular level, we found that p62 counteracted IL-6 production and ROS increase by interacting with NRF2 and promoting mitophagy. Moreover, p62/NRF2 axis sustained the expression level of H2AX and ataxia-telangiectasia mutated (ATM), whose activation has been shown to have growth-suppressive effects during the first steps of EBV-infection, before latency is established. In conclusion, this study shows for the first time that the accumulation of p62 and the activation of p62/axis counteracted EBV-driven proliferation of primary B lymphocytes.

The Ubiquitin Sensor and Adaptor Protein p62 Mediates Signal Transduction of a Viral Oncogenic Pathway

The Epstein-Barr virus (EBV) protein LMP1 serves as a paradigm that engages complicated ubiquitination-mediated mechanisms to activate multiple transcription factors. p62 is a ubiquitin sensor and a signal-transducing adaptor that has multiple functions in diverse contexts. However, the interaction between p62 and oncogenic viruses is poorly understood. We recently reported a crucial role for p62 in oncovirus-mediated oxidative stress by acting as a selective autophagy receptor. In this following pursuit, we further discovered that p62 is upregulated in EBV type 3 compared to type 1 latency, with a significant contribution from NF-κB and AP1 activities downstream of LMP1 signaling. In turn, p62 participates in LMP1 signal transduction through its interaction with TRAF6, promoting TRAF6 ubiquitination and activation. As expected, short hairpin RNA (shRNA)-mediated knockdown (KD) of p62 transcripts reduces LMP1-TRAF6 interaction and TRAF6 ubiquitination, as well as p65 nuclear translocation, which was assessed by Amnis imaging flow cytometry. Strikingly, LMP1-stimulated NF-κB, AP1, and Akt activities are all markedly reduced in p62-/- mouse embryo fibroblasts (MEFs) and in EBV-negative Burkitt's lymphoma (BL) cell lines with CRISPR-mediated knockout (KO) of the p62-encoding gene. However, EBV-positive BL cell lines (type 3 latency) with CRISPR-mediated KO of the p62-encoding gene failed to survive. In consequence, shRNA-mediated p62 KD impairs the ability of LMP1 to regulate its target gene expression, promotes etoposide-induced apoptosis, and reduces the proliferation of lymphoblastic cell lines (LCLs). These important findings have revealed a previously unrecognized novel role for p62 in EBV latency and oncogenesis, which advances our understanding of the mechanism underlying virus-mediated oncogenesis. IMPORTANCE As a ubiquitin sensor and a signal-transducing adaptor, p62 is crucial for NF-κB activation, which involves the ubiquitin machinery, in diverse contexts. However, whether p62 is required for EBV LMP1 activation of NF-κB is an open question. In this study, we provide evidence that p62 is upregulated in EBV type 3 latency and, in turn, p62 mediates LMP1 signal transduction to NF-κB, AP1, and Akt by promoting TRAF6 ubiquitination and activation. In consequence, p62 deficiency negatively regulates LMP1-mediated gene expression, promotes etoposide-induced apoptosis, and reduces the proliferation of LCLs. These important findings identified p62 as a novel signaling component of the key viral oncogenic signaling pathway.

Stress-Induced Epstein-Barr Virus Reactivation

Epstein-Barr virus (EBV) is typically found in a latent, asymptomatic state in immunocompetent individuals. Perturbations of the host immune system can stimulate viral reactivation. Furthermore, there are a myriad of EBV-associated illnesses including various cancers, post-transplant lymphoproliferative disease, and autoimmune conditions. A thorough understanding of this virus, and the interplay between stress and the immune system, is essential to establish effective treatment. This review will provide a summary of the interaction between both psychological and cellular stressors resulting in EBV reactivation. It will examine mechanisms by which EBV establishes and maintains latency and will conclude with a brief overview of treatments targeting EBV.

Targeting K-Ras and apoptosis-driven cellular transformation in cancer

Cellular transformation is a major event that helps cells to evade apoptosis, genomic instability checkpoints, and immune surveillance to initiate tumorigenesis and to promote progression by cancer stem cell expansion. However, the key molecular players that govern cellular transformation and ways to target cellular transformation for therapy are poorly understood to date. Here we draw key evidences from the literature on K-Ras-driven cellular transformation in the context of apoptosis to shed light on the key players that are required for cellular transformation and explain how aiming p53 could be useful to target cellular transformation. The defects in key apoptosis regulators such as p53, Bax, and Bak lead to apoptosis evasion, cellular transformation, and genomic instability to further lead to stemness, tumorigenesis, and metastasis via c-Myc-dependent transcription. Therefore enabling key apoptotic checkpoints in combination with K-Ras inhibitors will be a promising therapeutic target in cancer therapy.

Antiviral Effects of Polyphenols from Marine Algae

The disease-preventive and medicinal properties of plant polyphenolic compounds have long been known. As active ingredients, they are used to prevent and treat many noncommunicable diseases. In recent decades, marine macroalgae have attracted the attention of biotechnologists and pharmacologists as a promising and almost inexhaustible source of polyphenols. This heterogeneous group of compounds contains many biopolymers with unique structure and biological properties that exhibit high anti-infective activity. In the present review, the authors focus on the antiviral potential of polyphenolic compounds (phlorotannins) from marine algae and consider the mechanisms of their action as well as other biological properties of these compounds that have effects on the progress and outcome of viral infections. Effective nutraceuticals, to be potentially developed on the basis of algal polyphenols, can also be used in the complex therapy of viral diseases. It is necessary to extend in vivo studies on laboratory animals, which subsequently will allow proceeding to clinical tests. Polyphenolic compounds have a great potential as active ingredients to be used for the creation of new antiviral pharmaceutical substances.

Investigating the Thioredoxin and Glutathione Systems' Response in Lymphoma Cells after Treatment with [Au(d2pype)2]CL

Lymphoma is a blood cancer comprising various subtypes. Although effective therapies are available, some patients fail to respond to treatment and can suffer from side effects. Antioxidant systems, especially the thioredoxin (Trx) and glutathione (GSH) systems, are known to enhance cancer cell survival, with thioredoxin reductase (TrxR) recently reported as a potential anticancer target. Since the GSH system can compensate for some Trx system functions, we investigated its response in three lymphoma cell lines after inhibiting TrxR activity with [Au(d2pype)2]Cl, a known TrxR inhibitor. [Au(d2pype)2]Cl increased intracellular reactive oxygen species (ROS) levels and induced caspase-3 activity leading to cell apoptosis through inhibiting both TrxR and glutathione peroxidase (Gpx) activity. Expression of the tumour suppresser gene TXNIP increased, while GPX1 and GPX4 expression, which are related to poor prognosis of lymphoma patients, decreased. Unlike SUDHL2 and SUDHL4 cells, which exhibited a decreased GSH/GSSG ratio after treatment, in KMH2 cells the ratio remained unchanged, while glutathione reductase and glutaredoxin expression increased. Since KMH2 cells were less sensitive to treatment with [Au(d2pype)2]Cl, the GSH system may play a role in protecting cells from apoptosis after TrxR inhibition. Overall, our study demonstrates that inhibition of TrxR represents a valid therapeutic approach for lymphoma.

Nicotinamide adenine dinucleotide phosphate oxidase inhibitor induces apoptosis on Epstein-Barr virus positive B lymphoma cells

Over-expression of nicotinamide adenine dinucleotide phosphate oxidase (Nox) isoform enzymes was recently reported in various cancers including Burkitt’s lymphoma (BL). However, the functions of Nox isoform enzymes in BL remain poorly understood. In this study, Nox isoform expression and the effects of a Nox-specific inhibitor were evaluated in Epstein-Barr virus (EBV)-positive Raji BL cells in comparison with EBV-negative Ramos BL cells. To evaluate Nox enzyme expression in Raji and Ramos BL cells, polymerase chain reaction (PCR) and western blot analysis were performed. To verify the intracellular signaling mechanism of the Nox inhibitor-induced apoptosis of Raji cells, WST-1 assay, trypan blue exclusion method, flow cytometry, PCR, western blotting, and bromodeoxyuridine staining were conducted. Experiments using the pan-caspase inhibitor z-VAD, reactive oxygen species scavenger N-acetyl-L-cysteine (NAC), and Bim inhibitor 1 were performed. PCR and western blot results showed that Nox isoform enzymes were highly expressed in EBV-positive BL Raji cells compared with EBV-negative BL Ramos cells. The Nox2 inhibitor induced apoptosis of Raji cells in time- and dose-dependent manners. The Nox2 inhibitor also caused up-regulation of Bim and Noxa, down-regulation of Mcl-1, translocation of Bax, release of cytochrome c, and caspase cascade activation, resulting in apoptosis. Furthermore, z-VAD, NAC, and BI-1 effectively blocked the Nox2 inhibitor-induced apoptosis of Raji cells. Taken together, these results provide a novel insight into the mechanism of Nox inhibitor-induced apoptosis and evidence for Nox as a therapeutic target to treat EBV-positive malignancies.

Viral Infection and Autophagy Dysregulation: The Case of HHV-6, EBV and KSHV

Human Herpes Virus-6 (HHV-6), Epstein-Barr Virus (EBV) and Kaposi Sarcoma Herpes Virus (KSHV) are viruses that share with other member of the Herpesvirus family the capacity to interfere with the autophagic process. In this paper, mainly based on the findings of our laboratory, we describe how, through different mechanisms, these viruses converge in reducing autophagy to impair DC immune function and how, by infecting and dysregulating autophagy in different cell types, they promote the pathologies associated with their infection, from the neurodegenerative diseases such Alzheimer’s disease to cancer.

Marine Algal Antioxidants as Potential Vectors for Controlling Viral Diseases

As the COVID-19 epidemic expands in the world, and with the previous SARS epidemic, avian flu, Ebola and AIDS serving as a warning, biomedical and biotechnological research has the task to find solutions to counteract viral entry and pathogenesis. A novel approach can come from marine chemodiversity, recognized as a relevant source for developing a future natural "antiviral pharmacy". Activities of antioxidants against viruses can be exploited to cope with human viral infection, from single individual infections to protection of populations. There is a potentially rich and fruitful reservoir of such compounds thanks to the plethora of bioactive molecules and families present in marine microorganisms. The aim of this communication is to present the state-of-play of what is known on the antiviral activities recognized in (micro)algae, highlighting the different molecules from various algae and their mechanisms of actions, when known. Given the ability of various algal molecules-mainly sulfated polysaccharides-to inhibit viral infection at Stage I (adsorption and invasion of cells), we envisage a need to further investigate the antiviral ability of algae, and their mechanisms of action. Given the advantages of microalgal production compared to other organisms, the opportunity might become reality in a short period of time.

APX-115A, a pan-NADPH Oxidase Inhibitor, Induces Caspase-dependent Cell Death by Suppressing NOX4-ROS Signaling in EBV-infected Retinal Epithelial Cells

PURPOSE

Epstein-Barr virus is a γ-herpes virus that infects primary B cells and can transform infected cells into immortalized lymphoblastoid cell lines (LCL). The role of EBV in malignancies such as Burkitt's lymphoma and nasopharyngeal carcinoma is well understood, however, its role in EBV-infected retinal cells remains poorly understood. Therefore, we investigated the effect of EBV on the growth of retinal cells.

METHODS

Previously, we established and reported a cell line model to address the relationship between EBV infection and retinal cell proliferation that used adult retinal pigment epithelium (ARPE-19) and EBV infection. To determine the effect of EBV on ARPE-19 cells, cell death was measured by propidium iodine/annexin V staining and reactive oxygen species (ROS) were measured by FACS, and protein expression was evaluated using western blot analysis. Also, downregulation of LMP1 and NADPH oxidase 4 (NOX4) expression was accomplished using siRNA technology.

RESULTS

We found that ROS were dramatically increased in EBV-infected ARPE19 cells (APRE19/EBV) relative to the parental cell line. Additionally, the expression level of NOX4, a main source of ROS, was upregulated by EBV infection. Interestingly, downregulation of LMP1, one of the EBV viral onco-proteins, completely decreased EBV-induced ROS accumulation and the upregulation of NOX4. Treatment with APX-115A, a pan-NOX inhibitor, induced apoptotic cell death of only the EBV-infected ARPE19 cells but not the parental cell line. Pretreatment with z-VAD, a pan-caspase inhibitor, inhibited NOX inhibitor-induced cell death in ARPE19/EBV cells. Furthermore, APX-115A-induced cell death mediated the activation of JNK and ERK. Finally, we confirmed the expression level of NOX4, and APX-115A induced cell death of EBV-infected human primary retina epithelial cells and the activation of JNK and ERK.

CONCLUSION

Taken together, these our results suggest that APX-115A could be a therapeutic agent for treating EBV-infected retinal cells or diseases by inhibiting LMP1-NOX4-ROS signaling.

The Epstein-Barr virus nuclear antigen-1 upregulates the cellular antioxidant defense to enable B-cell growth transformation and immortalization

Epstein-Barr virus (EBV) immortalizes human B-lymphocytes and is implicated in the pathogenesis of lymphoid and epithelial cell malignancies. The EBV nuclear antigen (EBNA)-1 induces the accumulation of reactive oxygen species (ROS), which enables B-cell immortalization but causes oxidative DNA damage and triggers antiproliferative DNA damage responses. By comparing pairs of EBV-negative and -positive tumor cell lines we found that, while associated with the accumulation of oxidized nucleotides, EBV carriage promotes the concomitant activation of oxo-dNTP sanitization and purging pathways, including upregulation of the nucleoside triphosphatase mut-T homolog 1 (MTH1) and the DNA glycosylases 8-oxoguanine-glycosylase-1 (OGG1) and mut-Y homolog (MUTYH). Expression of EBNA1 was reversibly associated with transcriptional activation of this cellular response. DNA damage and apoptosis were preferentially induced in EBNA1-positive cell lines by treatment with MTH1 inhibitors, suggesting that virus carriage is linked to enhanced vulnerability to oxidative stress. MTH1, OGG1, and MUTYH were upregulated upon EBV infection in primary B-cells and treatment with MTH1 inhibitors prevented B-cell immortalization. These findings highlight an important role of the cellular antioxidant response in sustaining EBV infection, and suggests that targeting this cellular defense may offer a novel approach to antiviral therapy and could reduce the burden of EBV associated cancer.

Towards a comprehensive etiopathogenetic and pathophysiological theory of multiple sclerosis

Background: Multiple sclerosis (MS) is a neurodegenerative disease caused by dysfunction of the immune system that affects the central nervous system (CNS). It is characterized by demyelination, chronic inflammation, neuronal and oligodendrocyte loss and reactive astrogliosis. It can result in physical disability and acute neurological and cognitive problems. Despite the gains in knowledge of immunology, cell biology, and genetics in the last five decades, the ultimate etiology or specific elements that trigger MS remain unknown. The objective of this review is to propose a theoretical basis for MS etiopathogenesis.Methods: Search was done by accessing PubMed/Medline, EBSCO, and PsycINFO databases. The search string used was "(multiple sclerosis* OR EAE) AND (pathophysiology* OR etiopathogenesis)". The electronic databases were searched for titles or abstracts containing these terms in all published articles between January 1, 1960, and June 30, 2019. The search was filtered down to 362 articles which were included in this review.Results: A framework to better understand the etiopathogenesis and pathophysiology of MS can be derived from four essential factors; mitochondria dysfunction (MtD) & oxidative stress (OS), vitamin D (VD), sex hormones and thyroid hormones. These factors play a direct role in MS etiopathogenesis and have a modulatory effect on many other factors involved in the disease.Conclusions: For better MS prevention and treatment outcomes, efforts should be geared towards treating thyroid problems, sex hormone alterations, VD deficiency, sleep problems and melatonin alterations. MS patients should be encouraged to engage in activities that boost total antioxidant capacity (TAC) including diet and regular exercise and discouraged from activities that promote OS including smoking and alcohol consumption.

Quercetin Interrupts the Positive Feedback Loop Between STAT3 and IL-6, Promotes Autophagy, and Reduces ROS, Preventing EBV-Driven B Cell Immortalization

The oncogenic gammaherpesvirus Epstein–Barr virus (EBV) immortalizes in vitro B lymphocytes into lymphoblastoid cell lines (LCLs), a model that gives the opportunity to explore the molecular mechanisms driving viral tumorigenesis. In this study, we addressed the potential of quercetin, a widely distributed flavonoid displaying antioxidant, anti-inflammatory, and anti-cancer properties, in preventing EBV-driven B cell immortalization. The results obtained indicated that quercetin inhibited thectivation of signal transducer and activator of transcription 3 (STAT3) induced by EBV infection and reduced molecules such as interleukin-6 (IL-6) and reactive oxidative species (ROS) known to be essential for the immortalization process. Moreover, we found that quercetin promoted autophagy and counteracted the accumulation of sequestosome1/p62 (SQSTM1/p62), ultimately leading to the prevention of B cell immortalization. These findings suggest that quercetin may have the potential to be used to counteract EBV-driven lymphomagenesis, especially if its stability is improved.

Marek's Disease Virus Disables the ATR-Chk1 Pathway by Activating STAT3

Oncogenic virus replication often leads to genomic instability, causing DNA damage and inducing the DNA damage response (DDR) pathway. The DDR pathway is a cellular pathway that senses DNA damage and regulates the cell cycle to maintain genomic stability. Therefore, the DDR pathway is critical for the viral lifecycle and tumorigenesis. Marek's disease virus (MDV), an alphaherpesvirus that causes lymphoma in chickens, has been shown to induce DNA damage in infected cells. However, the interaction between MDV and the host DDR is unclear. In this study, we observed that MDV infection causes DNA strand breakage in chicken fibroblast (CEF) cells along with an increase in the DNA damage markers p53 and p21. Interestingly, we showed that phosphorylation of STAT3 was increased during MDV infection, concomitantly with a decrease of Chk1 phosphorylation. In addition, we found that MDV infection was enhanced by VE-821, an ATR-specific inhibitor, but attenuated by hydroxyurea, an ATR activator. Moreover, inhibition of STAT3 phosphorylation by Stattic eliminates the ability of MDV to inhibit Chk1 phosphorylation. Finally, we showed that MDV replication was decreased by Stattic treatment. Taken together, these results suggest that MDV disables the ATR-Chk1 pathway through STAT3 activation to benefit its replication.IMPORTANCE MDV is used as a biomedical model to study virus-induced lymphoma due to the similar genomic structures and physiological characteristics of MDV and human herpesviruses. Upon infection, MDV induces DNA damage, which may activate the DDR pathway. The DDR pathway has a dual impact on viruses because it manipulates repair and recombination factors to facilitate viral replication and also initiates antiviral action by regulating other signaling pathways. Many DNA viruses evolve to manipulate the DDR pathway to promote virus replication. In this study, we identified a mechanism used by MDV to inhibit ATR-Chk1 pathways. ATR is a cellular kinase that responds to broken single-stranded DNA, which has been less studied in MDV infection. Our results suggest that MDV infection activates STAT3 to disable the ATR-Chk1 pathway, which is conducive to viral replication. This finding provides new insight into the role of STAT3 in interrupting the ATR-Chk1 pathway during MDV replication.

Epstein-Barr Virus Latent Membrane Protein-1 Induces the Expression of SUMO-1 and SUMO-2/3 in LMP1-positive Lymphomas and Cells

Epstein-Barr Virus latent membrane protein-1 (LMP1) interacts with the SUMO-conjugating enzyme Ubc9, which induces protein sumoylation and may contribute to LMP1-mediated oncogenesis. After analyzing human lymphoma tissues and EBV-positive cell lines, we now document a strong correlation between LMP1 and sumo-1/2/3 or SUMO-1/2/3 levels, and show that LMP1-induced sumo expression requires the activation of NF-κB signaling through CTAR1 and CTAR2. Together, these results point to a second mechanism by which LMP1 dysregulates sumoylation processes and adds EBV-associated lymphomas to the list of malignancies associated with increased SUMO expression.

Therapeutic Strategies against Epstein-Barr Virus-Associated Cancers Using Proteasome Inhibitors

Epstein-Barr virus (EBV) is closely associated with several lymphomas (endemic Burkitt lymphoma, Hodgkin lymphoma and nasal NK/T-cell lymphoma) and epithelial cancers (nasopharyngeal carcinoma and gastric carcinoma). To maintain its persistence in the host cells, the virus manipulates the ubiquitin-proteasome system to regulate viral lytic reactivation, modify cell cycle checkpoints, prevent apoptosis and evade immune surveillance. In this review, we aim to provide an overview of the mechanisms by which the virus manipulates the ubiquitin-proteasome system in EBV-associated lymphoid and epithelial malignancies, to evaluate the efficacy of proteasome inhibitors on the treatment of these cancers and discuss potential novel viral-targeted treatment strategies against the EBV-associated cancers.

The Translesion Polymerase Pol η Is Required for Efficient Epstein-Barr Virus Infectivity and Is Regulated by the Viral Deubiquitinating Enzyme BPLF1

Epstein-Barr virus (EBV) infection and lytic replication are known to induce a cellular DNA damage response. We previously showed that the virally encoded BPLF1 protein interacts with and regulates several members of the translesion synthesis (TLS) pathway, a DNA damage tolerance pathway, and that these cellular factors enhance viral infectivity. BPLF1 is a late lytic cycle gene, but the protein is also packaged in the viral tegument, indicating that BPLF1 may function both early and late during infection. The BPLF1 protein expresses deubiquitinating activity that is strictly conserved across the Herpesviridae; mutation of the active site cysteine results in a loss of enzymatic activity. Infection with an EBV BPLF1 knockout virus results in decreased EBV infectivity. Polymerase eta (Pol η), a specialized DNA repair polymerase, functions in TLS and allows for DNA replication complexes to bypass lesions in DNA. Here we report that BPLF1 interacts with Pol η and that Pol η protein levels are increased in the presence of functional BPLF1. BPLF1 promotes a nuclear relocalization of Pol η molecules which are focus-like in appearance, consistent with the localization observed when Pol η is recruited to sites of DNA damage. Knockdown of Pol η resulted in decreased production of infectious virus, and further, Pol η was found to bind to EBV DNA, suggesting that it may allow for bypass of damaged viral DNA during its replication. The results suggest a mechanism by which EBV recruits cellular repair factors, such as Pol η, to sites of viral DNA damage via BPLF1, thereby allowing for efficient viral DNA replication.IMPORTANCE Epstein-Barr virus is the causative agent of infectious mononucleosis and infects approximately 90% of the world's population. It causes lymphomas in individuals with acquired and innate immune disorders and is strongly associated with Hodgkin's lymphoma, Burkitt's lymphoma, diffuse large B-cell lymphomas, nasopharyngeal carcinoma (NPC), and lymphomas that develop in organ transplant recipients. Cellular DNA damage is a major determinant in the establishment of oncogenic processes and is well studied, but there are few studies of endogenous repair of viral DNA. This work evaluates how EBV's BPLF1 protein and its conserved deubiquitinating activity regulate the cellular DNA repair enzyme polymerase eta and recruit it to potential sites of viral damage and replication, resulting in enhanced production of infectious virus. These findings help to establish how EBV enlists and manipulates cellular DNA repair factors during the viral lytic cycle, contributing to efficient infectious virion production.

Very early onset inflammatory bowel disease: Investigation of the IL-10 signaling pathway in Iranian children

BACKGROUND & AIM

Comparing to adult inflammatory bowel disease (IBD), those with early onset manifestations have different features in terms of the underlying molecular pathology, the course of disease and the response to therapy. We investigated the IL-10 signaling pathway previously reported as an important cause of infantile (Very Early Onset) IBD to find any possible variants.

METHOD

With the next generation sequencing technique we screened IL-10, IL-10RA and IL10RB genes of 15 children affected by very early onset-GI (gastrointestinal) disorders. Additionally, we analyzed them based on Thermo Fisher immune deficiency panel for genes either having a known role in IBD pathogenesis or cause the disorders with overlapping manifestations. We performed multiple functional analyses only for the cases showing variants in IL-10- related genes.

RESULT

In 3 out of 15 patients we identified variants including a homozygous and heterozygote mutations in IL-10RA and a novel homozygous mutation in IL-12RB1. Our functional studies reveal that in contrast to the IL-10RA heterozygote mutation that does not have deleterious effects, the homozygous mutation abrogates the IL-10 signaling pathway.

CONCLUSION

Our study suggests we need to modify the classical diagnostic approach from functional assays followed by candidate- gene or genes sequencing to the firstly parallel genomic screening followed by functional studies.

Regulation of Telomere Homeostasis during Epstein-Barr virus Infection and Immortalization

The acquisition of unlimited proliferative potential is dependent on the activation of mechanisms for telomere maintenance, which counteracts telomere shortening and the consequent triggering of the DNA damage response, cell cycle arrest, and apoptosis. The capacity of Epstein Barr virus (EBV) to infect B-lymphocytes in vitro and transform the infected cells into autonomously proliferating immortal cell lines underlies the association of this human gamma-herpesvirus with a broad variety of lymphoid and epithelial cell malignancies. Current evidence suggests that both telomerase-dependent and -independent pathways of telomere elongation are activated in the infected cells during the early and late phases of virus-induced immortalization. Here we review the interaction of EBV with different components of the telomere maintenance machinery and the mechanisms by which the virus regulates telomere homeostasis in proliferating cells. We also discuss how these viral strategies may contribute to malignant transformation.

Disruption of direct 3D telomere-TRF2 interaction through two molecularly disparate mechanisms is a hallmark of primary Hodgkin and Reed-Sternberg cells

In classical Hodgkin's lymphoma (cHL), specific changes in the 3D telomere organization cause progression from mononuclear Hodgkin cells (H) to multinucleated Reed-Sternberg cells (RS). In a post-germinal center B-cell in vitro model, permanent latent membrane protein 1 (LMP1) expression, as observed in Epstein-Barr virus (EBV)-associated cHL, results in multinuclearity and complex chromosomal aberrations through downregulation of key element of the shelterin complex, the telomere repeat binding factor 2 (TRF2). Thus, we hypothesized that the three-dimensional (3D) telomere-TRF2 interaction was progressively disturbed during transition from H to RS cells. To this end, we developed and applied for the first time a combined quantitative 3D TRF2-telomere immune fluorescent in situ hybridization (3D TRF2/Telo-Q-FISH) technique to monolayers of primary H and RS cells, and adjacent benign internal control lymphocytes of lymph node biopsy suspensions from diagnostic lymph node biopsies of 14 patients with cHL. We show that H and RS cells are characterized by two distinct patterns of disruption of 3D telomere-TRF2 interaction. Disruption pattern A is defined by massive attrition of telomere signals and a considerable increase of TRF2 signals not associated with telomeres. This pattern is restricted to EBV-negative cHL. Disruption pattern B is defined by telomere de-protection due to an impressive loss of TRF2 signals, physically linked to telomeres. This pattern is typical of, but is not restricted to, LMP1+EBV-associated cHL. In the disruption pattern B group, so-called 'ghost' end-stage RS cells, void of both TRF2 and telomere signals, were identified, whether or not associated with EBV. Our findings demonstrate that two molecularly disparate mechanisms converge on the level of 3D telomere-TRF2 interaction in the formation of RS cells.

DNA Oncogenic Virus-Induced Oxidative Stress, Genomic Damage, and Aberrant Epigenetic Alterations

Approximately 20% of human cancers is attributable to DNA oncogenic viruses such as human papillomavirus (HPV), hepatitis B virus (HBV), and Epstein-Barr virus (EBV). Unrepaired DNA damage is the most common and overlapping feature of these DNA oncogenic viruses and a source of genomic instability and tumour development. Sustained DNA damage results from unceasing production of reactive oxygen species and activation of inflammasome cascades that trigger genomic changes and increased propensity of epigenetic alterations. Accumulation of epigenetic alterations may interfere with genome-wide cellular signalling machineries and promote malignant transformation leading to cancer development. Untangling and understanding the underlying mechanisms that promote these detrimental effects remain the major objectives for ongoing research and hope for effective virus-induced cancer therapy. Here, we review current literature with an emphasis on how DNA damage influences HPV, HVB, and EBV replication and epigenetic alterations that are associated with carcinogenesis.

Combination of betulinic acid and chidamide synergistically inhibits Epstein-Barr virus replication through over-generation of reactive oxygen species

Epstein-Barr virus (EBV) has widely infected more than 90% of human populations. Currently, there is no efficient way to remove the virus because the EBV carriers are usually in a latent stage that allows them to escape the immune system and common antiviral drugs. In the effort to develop an efficient strategy for the removal of the EBV virus, we have shown that betulinic acid (BA) slightly suppresses EBV replication through SOD2 suppression with subsequent reactive oxygen species (ROS) generation and DNA damage in EBV-transformed LCL (lymphoblastoid cell line) cells. Chidamide (CDM, CS055), a novel histone deacetylase inhibitor (HDACi), could significantly switch EBV from the latent stage to the lytic stage with increased gene expression of BZLF1 and BMRF1, but has a small effect on EBV replication due to the suppression effect of CDM-mediated ROS generation. Interestingly, a combination of BA and CDM synergistically inhibits EBV replication with ROS over-generation and subsequent DNA damage and apoptosis. Overexpression of SOD2 diminishes this effect, while SOD2 knockdown mimics this effect. An in vivo xenograft tumor development study with the tail vein injection of EBV-transformed LCL cells in nude mice proves that the combination of BA and CDM synergistically increases superoxide anion release in tumor tissues and suppresses EBV replication and tumor growth, and significantly prolongs mouse survival. We conclude that the combination of BA and CDM could be an efficient strategy for clinical EBV removal.

Limited nucleotide pools restrict Epstein-Barr virus-mediated B-cell immortalization

Activation of cellular oncogenes as well as infection with tumor viruses can promote aberrant proliferation and activation of the host DNA damage response. Epstein-Barr virus (EBV) infection of primary human B cells induces a transient period of hyper-proliferation, but many of these infected cells succumb to an ataxia telangiectasia mutated/checkpoint kinase 2 (ATM/Chk2)-mediated senescence-like growth arrest. In this study, we assessed the role of DNA replicative stress and nucleotide pool levels in limiting EBV-infected B-cell outgrowth. We found that EBV triggered activation of the ataxia telangiectasia and Rad3-related (ATR) signaling pathway in the early rapidly proliferating cells, which were also significantly more sensitive to inhibition of the ATR pathway than late attenuated proliferating cells. Through nuclear halo assays, we determined that early EBV-infected cells displayed increased replicative stress and DNA damage relative to late proliferating cells. Finally, we found that early after infection, hyper-proliferating B cells exhibited limited deoxyribonucleotide triphosphate (dNTP) pools compared with late proliferating and EBV-immortalized lymphoblastoid cell lines with a specific loss of purine dNTPs. Importantly, supplementation with exogenous nucleosides before the period of hyper-proliferation markedly enhanced B-cell immortalization by EBV and rescued replicative stress. Together our results suggest that purine dNTP biosynthesis has a critical role in the early stages of EBV-mediated B-cell immortalization.

Effect of mitochondrially targeted carboxy proxyl nitroxide on Akt-mediated survival in Daudi cells: Significance of a dual mode of action

Vicious cycles of mutations and reactive oxygen species (ROS) generation contribute to cancer progression. The use of antioxidants to inhibit ROS generation promotes cytostasis by affecting the mutation cycle and ROS-dependent survival signaling. However, cancer cells select mutations to elevate ROS albeit maintaining mitochondrial hyperpolarization (Δψm), even under hypoxia. From this perspective, the use of drugs that disrupt both ROS generation and Δψm is a viable anticancer strategy. Hence, we studied the effects of mitochondrially targeted carboxy proxyl nitroxide (Mito-CP) and a control ten carbon TPP moiety (Dec-TPP⁺) in the human Burkitt lymphoma cell line (Daudi) and normal peripheral blood mononuclear cells under hypoxia and normoxia. We found preferential localization, Δψm and adenosine triphosphate loss, and significant cytotoxicity by Mito-CP in Daudi cells alone. Interestingly, ROS levels were decreased and maintained in hypoxic and normoxic cancer cells, respectively, by Mito-CP but not Dec-TPP⁺, therefore preventing any adaptive signaling. Moreover, dual effects on mitochondrial bioenergetics and ROS by Mito-CP curtailed the cancer survival via Akt inhibition, AMPK-HIF-1α activation and promoted apoptosis via increased BCL2-associated X protein and poly (ADP-ribose) polymerase expression. This dual mode of action by Mito-CP provides a better explanation of the application of antioxidants with specific relevance to cancerous transformation and adaptations in the Daudi cell line.

Epstein-Barr virus gene expression and latency pattern in gastric carcinomas: a systematic review

METHODS

A systematic review of literature was conducted to identify all published reports regarding the expression of Epstein-Barr Virus (EBV) proteins/transcripts and EBV latency patterns in EBV-associated gastric carcinomas (EBVaGC).

RESULTS

The literature search retrieved 247 papers, of which 25 papers matched the inclusion criteria. The analysis reveals that the most frequently expressed EBV latent proteins are EBNA1 (98.1%) and LMP2A (53.8%), while LMP1 and LMP2B are present in only 10% of cases. Lytic proteins, such as BARF0 and BARF1, and other lytic transcripts are present in almost half of cases.

CONCLUSION

EBVaGC seems to display a unique transcription/latency pattern that does not fit the 'standard' EBV latency patterns and therefore should be further studied to better understand EBVaGC carcinogenesis.

A Central Role for STAT3 in Gammaherpesvirus-Life Cycle and -Diseases

Having co-evolved with humans, herpesviruses have adapted to exploit the host molecular machinery to ensure viral persistence. The cellular protein Signal Transducer and Activator of Transcription 3 (STAT3) is a leading example. STAT3 is a prominent transcription factor that functions in a variety of physiologic processes including embryonic development, inflammation, immunity, and wound healing. Generally activated via growth factor and cytokine signaling, STAT3 can transcriptionally drive oncoproteins, pro-survival and pro-proliferative proteins as well as angiogenic factors, thereby contributing to cancer. As in most non-viral cancers, STAT3 is constitutively active in EBV-related B and epithelial cell cancers and in animal models of KSHV-cancers. Again, similar to non-viral cancers, STAT3 contributes to gammaherpesvirus (EBV and KSHV)-mediated cancers by driving cell proliferation, invasion and angiogenesis. Being herpesviruses, EBV and KSHV establish latency in humans with episodic lytic activation. Importantly, both viruses activate STAT3 almost immediately upon infection of primary cells. In the setting of infection of primary B cells by EBV, this rapidly activated STAT3 plays a key role in suppressing the DNA damage response (DDR) to EBV-oncogene triggered replication stress, thereby facilitating B cell proliferation and ultimately establishment of latency. STAT3 also contributes to maintenance of latency by curbing lytic activation of EBV and KSHV in latent cells that express high levels of STAT3. In this way, gammaherpesviruses exploit STAT3 to overcome cellular anti-proliferative and anti-lytic barriers to promote viral persistence. These investigations into gammaherpesviruses and STAT3 have simultaneously revealed a novel function for STAT3 in suppression of the DDR, a process fundamental to physiologic cell proliferation as well as development of cancer.