Human hepatitis C virus NS5A protein alters intracellular calcium levels, induces oxidative stress, and activates STAT-3 and NF-kappa B

SARS-CoV-2 aberrantly elevates mitochondrial bioenergetics to induce robust virus propagation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a 'highly transmissible respiratory pathogen, leading to severe multi-organ damage. However, knowledge regarding SARS-CoV-2-induced cellular alterations is limited. In this study, we report that SARS-CoV-2 aberrantly elevates mitochondrial bioenergetics and activates the EGFR-mediated cell survival signal cascade during the early stage of viral infection. SARS-CoV-2 causes an increase in mitochondrial transmembrane potential via the SARS-CoV-2 RNA-nucleocapsid cluster, thereby abnormally promoting mitochondrial elongation and the OXPHOS process, followed by enhancing ATP production. Furthermore, SARS-CoV-2 activates the EGFR signal cascade and subsequently induces mitochondrial EGFR trafficking, contributing to abnormal OXPHOS process and viral propagation. Approved EGFR inhibitors remarkably reduce SARS-CoV-2 propagation, among which vandetanib exhibits the highest antiviral efficacy. Treatment of SARS-CoV-2-infected cells with vandetanib decreases SARS-CoV-2-induced EGFR trafficking to the mitochondria and restores SARS-CoV-2-induced aberrant elevation in OXPHOS process and ATP generation, thereby resulting in the reduction of SARS-CoV-2 propagation. Furthermore, oral administration of vandetanib to SARS-CoV-2-infected hACE2 transgenic mice reduces SARS-CoV-2 propagation in lung tissue and mitigates SARS-CoV-2-induced lung inflammation. Vandetanib also exhibits potent antiviral activity against various SARS-CoV-2 variants of concern, including alpha, beta, delta and omicron, in in vitro cell culture experiments. Taken together, our findings provide novel insight into SARS-CoV-2-induced alterations in mitochondrial dynamics and EGFR trafficking during the early stage of viral infection and their roles in robust SARS-CoV-2 propagation, suggesting that EGFR is an attractive host target for combating COVID-19.

Deciphering the Role of Post-Translational Modifications and Cellular Location of Hepatitis Delta Virus (HDV) Antigens in HDV-Mediated Liver Damage in Mice

Hepatitis D virus (HDV) infection represents the most severe form of chronic viral hepatitis. We have shown that the delivery of HDV replication-competent genomes to the hepatocytes using adeno-associated virus (AAV-HDV) as gene delivery vehicles offers a unique platform to investigate the molecular aspects of HDV and associated liver damage. For the purpose of this study, we generated HDV genomes modified by site-directed mutagenesis aimed to (i) prevent some post-translational modifications of HDV antigens (HDAgs) such as large-HDAg (L-HDAg) isoprenylation or short-HDAg (S-HDAg) phosphorylation; (ii) alter the localization of HDAgs within the subcellular compartments; and (iii) inhibit the right conformation of the delta ribozyme. First, the different HDV mutants were tested in vitro using plasmid-transfected Huh-7 cells and then in vivo in C57BL/6 mice using AAV vectors. We found that Ser177 phosphorylation and ribozymal activity are essential for HDV replication and HDAg expression. Mutations of the isoprenylation domain prevented the formation of infectious particles and increased cellular toxicity and liver damage. Furthermore, altering HDAg intracellular localization notably decreased viral replication, though liver damage remained unchanged versus normal HDAg distribution. In addition, a mutation in the nuclear export signal impaired the formation of infectious viral particles. These findings contribute valuable insights into the intricate mechanisms of HDV biology and have implications for therapeutic considerations.

Organelle stress and alterations in interorganelle crosstalk during liver fibrosis

The synchronous functioning and quality control of organelles ensure cell survival and function and are essential for maintaining homeostasis. Prolonged exposure to stressors (viruses, bacteria, parasitic infections, alcohol, drugs) or genetic mutations often disrupt the functional integrity of organelles which plays a critical role in the initiation and progression of several diseases including chronic liver diseases. One of the most important pathologic consequences of chronic liver diseases is liver fibrosis, characterized by tissue scarring due to the progressive accumulation of extracellular matrix components. Left untreated, fibrosis may advance to life-threatening complications such as cirrhosis, hepatic decompensation, and HCC, which collectively accounts for ∼1 million deaths per year worldwide. Owing to the lack of treatment options that can regress or reverse cirrhosis, liver transplantation is currently the only available treatment for end-stage liver disease. However, the limited supply of usable donor organs, adverse effects of lifelong immunosuppressive regimes, and financial considerations pose major challenges and limit its application. Hence, effective therapeutic strategies are urgently needed. An improved understanding of the organelle-level regulation of fibrosis can help devise effective antifibrotic therapies focused on reducing organelle stress, limiting organelle damage, improving interorganelle crosstalk, and restoring organelle homeostasis; and could be a potential clinical option to avoid transplantation. This review provides a timely update on the recent findings and mechanisms covering organelle-specific dysfunctions in liver fibrosis, highlights how correction of organelle functions opens new treatment avenues and discusses the potential challenges to clinical application.

Role of Immunological Cells in Hepatocellular Carcinoma Disease and Associated Pathways

Hepatocellular carcinoma (HCC) remains one of the predominant causes of cancer-related mortality across the globe. It is attributed to obesity, excessive alcohol consumption, smoking, and infection by the hepatitis virus. Early diagnosis of HCC is essential, and local treatments such as surgical excision and percutaneous ablation are effective. Palliative systemic therapy, primarily with the tyrosine kinase inhibitor Sorafenib, is used in advanced cases. However, the prognosis for advanced HCC remains poor. This Review additionally describes the pathophysiological mechanisms of HCC, which include aberrant molecular signaling, genomic instability, persistent inflammation, and the paradoxical position of the immune system in promoting and suppressing HCC. The paper concludes by discussing the growing body of research on the relationship between mitochondria and HCC, suggesting that mitochondrial dysfunction may contribute to the progression of HCC. This Review focuses on immunological interactions between different mechanisms of HCC progression, including obesity, viral infection, and alcohol consumption.

Mitochondrial Oxidative Phosphorylation in Viral Infections

Mitochondria have been identified as the "powerhouse" of the cell, generating the cellular energy, ATP, for almost seven decades. Research over time has uncovered a multifaceted role of the mitochondrion in processes such as cellular stress signaling, generating precursor molecules, immune response, and apoptosis to name a few. Dysfunctional mitochondria resulting from a departure in homeostasis results in cellular degeneration. Viruses hijack host cell machinery to facilitate their own replication in the absence of a bonafide replication machinery. Replication being an energy intensive process necessitates regulation of the host cell oxidative phosphorylation occurring at the electron transport chain in the mitochondria to generate energy. Mitochondria, therefore, can be an attractive therapeutic target by limiting energy for viral replication. In this review we focus on the physiology of oxidative phosphorylation and on the limited studies highlighting the regulatory effects viruses induce on the electron transport chain.

HCV and HCC Tango-Deciphering the Intricate Dance of Disease: A Review Article

Hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma (HCC) accounting for around one-third of all HCC cases. Prolonged inflammation in chronic hepatitis C (CHC), maintained through a variety of pro- and anti-inflammatory mediators, is one of the aspects of carcinogenesis, followed by mitochondrial dysfunction and oxidative stress. Immune response dysfunction including the innate and adaptive immunity also plays a role in the development, as well as in the recurrence of HCC after treatment. Some of the tumor suppressor genes inhibited by the HCV proteins are p53, p73, and retinoblastoma 1. Mutations in the telomerase reverse transcriptase promoter and the oncogene catenin beta 1 are two more important carcinogenic signaling pathways in HCC associated with HCV. Furthermore, in HCV-related HCC, numerous tumor suppressor and seven oncogenic genes are dysregulated by epigenetic changes. Epigenetic regulation of gene expression is considered as a lasting "epigenetic memory", suggesting that HCV-induced changes persist and are associated with liver carcinogenesis even after cure. Epigenetic changes and immune response dysfunction are recognized targets for potential therapy of HCC.

Direct and biologically significant interactions of human herpesvirus 8 interferon regulatory factor 1 with STAT3 and Janus kinase TYK2

Human herpesvirus 8 (HHV-8) encodes four viral interferon regulatory factors (vIRFs) that target cellular IRFs and/or other innate-immune and stress signaling regulators and suppress the cellular response to viral infection and replication. For vIRF-1, cellular protein targets include IRFs, p53, p53-activating ATM kinase, BH3-only proteins, and antiviral signaling effectors MAVS and STING; vIRF-1 inhibits each, with demonstrated or likely promotion of HHV-8 de novo infection and productive replication. Here, we identify direct interactions of vIRF-1 with STAT3 and STAT-activating Janus kinase TYK2 (the latter reported previously by us to be inhibited by vIRF-1) and suppression by vIRF-1 of cytokine-induced STAT3 activation. Suppression of active, phosphorylated STAT3 (pSTAT3) by vIRF-1 was evident in transfected cells and vIRF-1 ablation in lytically-reactivated recombinant-HHV-8-infected cells led to increased levels of pSTAT3. Using a panel of vIRF-1 deletion variants, regions of vIRF-1 required for interactions with STAT3 and TYK2 were identified, which enabled correlation of STAT3 signaling inhibition by vIRF-1 with TYK2 binding, independently of STAT3 interaction. A viral mutant expressing vIRF-1 deletion-variant Δ198-222 refractory for TYK2 interaction and pSTAT3 suppression was severely compromised for productive replication. Conversely, expression of phosphatase-resistant, protractedly-active STAT3 led to impaired HHV-8 replication. Cells infected with HHV-8 mutants expressing STAT3-refractory vIRF-1 deletion variants or depleted of STAT3 displayed reduced vIRF-1 expression, while custom-peptide-promoted STAT3 interaction could effect increased vIRF-1 expression and enhanced virus replication. Taken together, our data identify vIRF-1 targeting and inhibition of TYK2 as a mechanism of STAT3-signaling suppression and critical for HHV-8 productive replication, the importance of specific pSTAT3 levels for replication, positive roles of STAT3 and vIRF-1-STAT3 interaction in vIRF-1 expression, and significant contributions to lytic replication of STAT3 targeting by vIRF-1.

STAT3 regulates antiviral immunity by suppressing excessive interferon signaling

This study identifies interleukin-6 (IL-6)-independent phosphorylation of STAT3 Y705 at the early stage of infection with several viruses, including influenza A virus (IAV). Such activation of STAT3 is dependent on the retinoic acid-induced gene I/mitochondrial antiviral-signaling protein/spleen tyrosine kinase (RIG-I/MAVS/Syk) axis and critical for antiviral immunity. We generate STAT3^Y705F/+ knockin mice that display a remarkably suppressed antiviral response to IAV infection, as evidenced by impaired expression of several antiviral genes, severe lung tissue injury, and poor survival compared with wild-type animals. Mechanistically, STAT3 Y705 phosphorylation restrains IAV pathogenesis by repressing excessive production of interferons (IFNs). Blocking phosphorylation significantly augments the expression of type I and III IFNs, potentiating the virulence of IAV in mice. Importantly, knockout of IFNAR1 or IFNLR1 in STAT3^Y705F/+ mice protects the animals from lung injury and reduces viral load. The results indicate that activation of STAT3 by Y705 phosphorylation is vital for establishment of effective antiviral immunity by suppressing excessive IFN signaling induced by viral infection.

The Role of Glutathione in Selected Viral Diseases

During inflammatory processes, immunocompetent cells are exposed to substantial amounts of free radicals and toxic compounds. Glutathione is a cysteine-containing tripeptide that is an important and ubiquitous antioxidant molecule produced in human organs. The intracellular content of GSH regulates the detoxifying capacity of cells, as well as the inflammatory and immune response. GSH is particularly important in the liver, where it serves as the major non-protein thiol involved in cellular antioxidant defense. There are numerous causes of hepatitis. The inflammation of the liver can be caused by a variety of infectious viruses. The relationship between oxidative stress and the hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV) infection is not fully known. The aim of this study was to examine the relationship between hepatotropic viruses and glutathione status, including reduced glutathione (GSH) and oxidized glutathione (GSSG), as well as antioxidant enzymes, e.g., glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) in liver diseases.

Selected Aspects of the Intricate Background of Immune-Related Cholangiopathies-A Critical Overview

Primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are rare immune-related cholangiopathies with still poorly explained pathogenesis. Although triggers of chronic inflammation with subsequent fibrosis that affect cholangiocytes leading to obliteration of bile ducts and conversion to liver cirrhosis are unclear, both disorders are regarded to be multifactorial. Different factors can contribute to the development of hepatocellular injury in the course of progressive cholestasis, including (1) body accumulation of bile acids and their toxicity, (2) decreased food intake and nutrient absorption, (3) gut microbiota transformation, and (4) reorganized host metabolism. Growing evidence suggests that intestinal microbiome composition not only can be altered by liver dysfunction, but in turn, it actively impacts hepatic conditions. In this review, we highlight the role of key factors such as the gut-liver axis, intestinal barrier integrity, bile acid synthesis and circulation, and microbiome composition, which seem to be strongly related to PBC and PSC outcome. Emerging treatments and future therapeutic strategies are also presented.

Unraveling the Molecular Mechanisms Involved in HCV-Induced Carcinogenesis

Cancer induced by a viral infection is among the leading causes of cancer. Hepatitis C Virus (HCV) is a hepatotropic oncogenic positive-sense RNA virus that leads to chronic infection, exposing the liver to a continuous process of damage and regeneration and promoting hepatocarcinogenesis. The virus promotes the development of carcinogenesis through indirect and direct molecular mechanisms such as chronic inflammation, oxidative stress, steatosis, genetic alterations, epithelial-mesenchymal transition, proliferation, and apoptosis, among others. Recently, direct-acting antivirals (DAAs) showed sustained virologic response in 95% of cases. Nevertheless, patients treated with DAAs have reported an unexpected increase in the early incidence of Hepatocellular carcinoma (HCC). Studies suggest that HCV induces epigenetic regulation through non-coding RNAs, DNA methylation, and chromatin remodeling, which modify gene expressions and induce genomic instability related to HCC development that persists with the infection's clearance. The need for a better understanding of the molecular mechanisms associated with the development of carcinogenesis is evident. The aim of this review was to unravel the molecular pathways involved in the development of carcinogenesis before, during, and after the viral infection's resolution, and how these pathways were regulated by the virus, to find control points that can be used as potential therapeutic targets.

Hepatitis C virus replication requires integrity of mitochondria-associated ER membranes

Background & Aims

Chronic HCV infection causes cellular stress, fibrosis and predisposes to hepatocarcinogenesis. Mitochondria play key roles in orchestrating stress responses by regulating bioenergetics, inflammation and apoptosis. To better understand the role of mitochondria in the viral life cycle and disease progression of chronic hepatitis C, we studied morphological and functional mitochondrial alterations induced by HCV using productively infected hepatoma cells and patient livers.

Methods

Biochemical and imaging assays were used to assess localization of cellular and viral proteins and mitochondrial functions in cell cultures and liver biopsies. Cyclophilin D (CypD) knockout was performed using CRISPR/Cas9 technology. Viral replication was quantified by quantitative reverse-transcription PCR and western blotting.

Results

Several HCV proteins were found to associate with mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), the points of contact between the ER and mitochondria. Downregulation of CypD, which is known to disrupt MAM integrity, reduced viral replication, suggesting that MAMs play an important role in the viral life cycle. This process was rescued by ectopic CypD expression. Furthermore, HCV proteins were found to associate with voltage dependent anion channel 1 (VDAC1) at MAMs and to reduce VDAC1 protein levels at MAMs in vitro and in patient biopsies. This association did not affect MAM-associated functions in glucose homeostasis and Ca²⁺ signaling.

Conclusions

HCV proteins associate specifically with MAMs and MAMs play an important role in viral replication. The association between viral proteins and MAMs did not impact Ca²⁺ signaling between the ER and mitochondria or glucose homeostasis. Whether additional functions of MAMs and/or VDAC are impacted by HCV and contribute to the associated pathology remains to be assessed.

Impact and implications

Hepatitis C virus infects the liver, where it causes inflammation, cell damage and increases the long-term risk of liver cancer. We show that several HCV proteins interact with mitochondria in liver cells and alter the composition of mitochondrial subdomains. Importantly, HCV requires the architecture of these mitochondrial subdomains to remain intact for efficient viral replication.

Identification of key proteins of cytopathic biotype bovine viral diarrhoea virus involved in activating NF-κB pathway in BVDV-induced inflammatory response

Bovine viral diarrhoea virus (BVDV) is the etiologic agent of bovine viral diarrhea-mucosal disease, one of the most important viral diseases in cattle, with inflammatory diarrhea, enteritis, and mucosa necrosis as the major clinical manifestations. NF-κB is an important transcription complex that regulates the expression of genes involved in inflammation and immune responses. NLRP3 inflammasome plays a key role in the development of inflammatory diseases. However, whether the activation of NF-κB is crucial for BVDV infection-induced inflammatory responses remains unclear. The results of our present study showed that BVDV infection significantly activated the NF-κB pathway and promoted the expression of NLRP3 inflammasome components (NLRP3, ASC, pro-caspase 1) as well inflammatory cytokine pro-IL-1β in BVDV-infected bovine cells, resulting in the cleavage of pro-caspase 1 and pro-IL-1β into active form caspase 1 and IL-1β. However, the levels of the NLRP3 inflammasome components and inflammatory cytokines were obviously inhibited, as well the cleavage of pro-caspase 1 and pro-IL-1β in the pre-treated bovine cells with NF-κB-specific inhibitors after BVDV infection. Further, cytopathic biotype BVDV (cpBVDV) Erns and NS5A proteins with their key functional domains contributed to BVDV-induced inflammatory responses via activating the NF-κB pathway were confirmed experimentally. Especially, the NS5A can promote cholesterol synthesis and accelerate its augmentation, further activating the NF-κB signalling pathway. Conclusively, our data elucidate that the activation of NF-κB signaling pathway plays a crucial role in cpBVDV infection-induced inflammatory responses.

Canonical and Noncanonical ER Stress-Mediated Autophagy Is a Bite the Bullet in View of Cancer Therapy

Cancer cells adapt multiple mechanisms to counter intense stress on their way to growth. Tumor microenvironment stress leads to canonical and noncanonical endoplasmic stress (ER) responses, which mediate autophagy and are engaged during proteotoxic challenges to clear unfolded or misfolded proteins and damaged organelles to mitigate stress. In these conditions, autophagy functions as a cytoprotective mechanism in which malignant tumor cells reuse degraded materials to generate energy under adverse growing conditions. However, cellular protection by autophagy is thought to be complicated, contentious, and context-dependent; the stress response to autophagy is suggested to support tumorigenesis and drug resistance, which must be adequately addressed. This review describes significant findings that suggest accelerated autophagy in cancer, a novel obstacle for anticancer therapy, and discusses the UPR components that have been suggested to be untreatable. Thus, addressing the UPR or noncanonical ER stress components is the most effective approach to suppressing cytoprotective autophagy for better and more effective cancer treatment.

Female reproduction and viral infection in a long-lived mammal

For energetically limited organisms, life-history theory predicts trade-offs between reproductive effort and somatic maintenance. This is especially true of female mammals, for whom reproduction presents multifarious energetic and physiological demands. Here, we examine longitudinal changes in the gut virome (viral community) with respect to reproductive status in wild mature female chimpanzees Pan troglodytes schweinfurthii from two communities, Kanyawara and Ngogo, in Kibale National Park, Uganda. We used metagenomic methods to characterize viromes of individual chimpanzees while they were cycling, pregnant and lactating. Females from Kanyawara, whose territory abuts the park's boundary, had higher viral richness and loads (relative quantity of viral sequences) than females from Ngogo, whose territory is more energetically rich and located farther from large human settlements. Viral richness (total number of distinct viruses per sample) was higher when females were lactating than when cycling or pregnant. In pregnant females, viral richness increased with estimated day of gestation. Richness did not vary with age, in contrast to prior research showing increased viral abundance in older males from these same communities. Our results provide evidence of short-term physiological trade-offs between reproduction and infection, which are often hypothesized to constrain health in long-lived species.

Mechanism of selenomethionine inhibiting of PDCoV replication in LLC-PK1 cells based on STAT3/miR-125b-5p-1/HK2 signaling

There are no licensed therapeutics or vaccines available against porcine delta coronavirus (PDCoV) to eliminate its potential for congenital disease. In the absence of effective treatments, it has led to significant economic losses in the swine industry worldwide. Similar to the current coronavirus disease 2019 (COVID-19) pandemic, PDCoV is trans-species transmissible and there is still a large desert for scientific exploration. We have reported that selenomethionine (SeMet) has potent antiviral activity against PDCoV. Here, we systematically investigated the endogenous immune mechanism of SeMet and found that STAT3/miR-125b-5p-1/HK2 signalling is essential for the exertion of SeMet anti-PDCoV replication function. Meanwhile, HK2, a key rate-limiting enzyme of the glycolytic pathway, was able to control PDCoV replication in LLC-PK1 cells, suggesting a strategy for viruses to evade innate immunity using glucose metabolism pathways. Overall, based on the ability of selenomethionine to control PDCoV infection and transmission, we provide a molecular basis for the development of new therapeutic approaches.

Calcium Ions Signaling: Targets for Attack and Utilization by Viruses

Calcium, as a second intracellular messenger, participate in various physiological and biochemical processes, including cell growth and proliferation, energy metabolism, information transfer, cell death, and immune response. Ca2+ channels or pumps in plasma and organelle membranes and Ca2+-related proteins maintain Ca2+ homeostasis by regulating Ca2+ inflow, outflow and buffering to avoid any adverse effects caused by Ca2+ overload or depletion. Thus, Ca2+ signaling also provides a target for virus invasion, replication, proliferation and release. After hijacking the host cell, viruses exploit Ca2+ signaling to regulate apoptosis and resist host immunity to establish persistent infection. In this review, we discuss cellular Ca2+ signaling and channels, interaction of calcium-associated proteins with viruses, and host cell fate, as well as the role of Ca2+ in cell death and antiviral response during viral infection.

HIV-1-Mediated Acceleration of Oncovirus-Related Non-AIDS-Defining Cancers

With the advent of combination antiretroviral therapy (cART), overall survival has been improved, and the incidence of acquired immunodeficiency syndrome (AIDS)-defining cancers has also been remarkably reduced. However, non-AIDS-defining cancers among human immunodeficiency virus-1 (HIV-1)-associated malignancies have increased significantly so that cancer is the leading cause of death in people living with HIV in certain highly developed countries, such as France. However, it is currently unknown how HIV-1 infection raises oncogenic virus-mediated cancer risks in the HIV-1 and oncogenic virus co-infected patients, and thus elucidation of the molecular mechanisms for how HIV-1 expedites the oncogenic viruses-triggered tumorigenesis in the co-infected hosts is imperative for developing therapeutics to cure or impede the carcinogenesis. Hence, this review is focused on HIV-1 and oncogenic virus co-infection-mediated molecular processes in the acceleration of non-AIDS-defining cancers.

Inhibition of the IFN-α JAK/STAT Pathway by MERS-CoV and SARS-CoV-1 Proteins in Human Epithelial Cells

Coronaviruses (CoVs) have caused several global outbreaks with relatively high mortality rates, including Middle East Respiratory Syndrome coronavirus (MERS)-CoV, which emerged in 2012, and Severe Acute Respiratory Syndrome (SARS)-CoV-1, which appeared in 2002. The recent emergence of SARS-CoV-2 highlights the need for immediate and greater understanding of the immune evasion mechanisms used by CoVs. Interferon (IFN)-α is the body's natural antiviral agent, but its Janus kinase/signal transducer and activators of transcription (JAK/STAT) signalling pathway is often antagonized by viruses, thereby preventing the upregulation of essential IFN stimulated genes (ISGs). Therapeutic IFN-α has disappointingly weak clinical responses in MERS-CoV and SARS-CoV-1 infected patients, indicating that these CoVs inhibit the IFN-α JAK/STAT pathway. Here we show that in lung alveolar A549 epithelial cells expression of MERS-CoV-nsp2 and SARS-CoV-1-nsp14, but not MERS-CoV-nsp5, increased basal levels of total and phosphorylated STAT1 & STAT2 protein, but reduced IFN-α-mediated phosphorylation of STAT1-3 and induction of MxA. While MERS-CoV-nsp2 and SARS-CoV-1-nsp14 similarly increased basal levels of STAT1 and STAT2 in bronchial BEAS-2B epithelial cells, unlike in A549 cells, they did not enhance basal pSTAT1 nor pSTAT2. However, both viral proteins reduced IFN-α-mediated induction of pSTAT1-3 and ISGs (MxA, ISG15 and PKR) in BEAS-2B cells. Furthermore, even though IFN-α-mediated induction of pSTAT1-3 was not affected by MERS-CoV-nsp5 expression in BEAS-2B cells, downstream ISG induction was reduced, revealing that MERS-CoV-nsp5 may use an alternative mechanism to reduce antiviral ISG induction in this cell line. Indeed, we subsequently discovered that all three viral proteins inhibited STAT1 nuclear translocation in BEAS-2B cells, unveiling another layer of inhibition by which these viral proteins suppress responses to Type 1 IFNs. While these observations highlight cell line-specific differences in the immune evasion effects of MERS-CoV and SARS-CoV-1 proteins, they also demonstrate the broad spectrum of immune evasion strategies these deadly coronaviruses use to stunt antiviral responses to Type IFN.

Signaling Induced by Chronic Viral Hepatitis: Dependence and Consequences

Chronic viral hepatitis is a main cause of liver disease and hepatocellular carcinoma. There are striking similarities in the pathological impact of hepatitis B, C, and D, although these diseases are caused by very different viruses. Paired with the conventional study of protein-host interactions, the rapid technological development of -omics and bioinformatics has allowed highlighting the important role of signaling networks in viral pathogenesis. In this review, we provide an integrated look on the three major viruses associated with chronic viral hepatitis in patients, summarizing similarities and differences in virus-induced cellular signaling relevant to the viral life cycles and liver disease progression.

Viruses associated with ill health in wild chimpanzees

Viral infection is a major cause of ill health in wild chimpanzees (Pan troglodytes), but most evidence to date has come from conspicuous disease outbreaks with high morbidity and mortality. To examine the relationship between viral infection and ill health during periods not associated with disease outbreaks, we conducted a longitudinal study of wild eastern chimpanzees (P. t. schweinfurthii) in the Kanyawara and Ngogo communities of Kibale National Park, Uganda. We collected standardized, observational health data for 4 years and then used metagenomics to characterize gastrointestinal viromes (i.e., all viruses recovered from fecal samples) in individual chimpanzees before and during episodes of clinical disease. We restricted our analyses to viruses thought to infect mammals or primarily associated with mammals, discarding viruses associated with nonmammalian hosts. We found 18 viruses (nine of which were previously identified in this population) from at least five viral families. Viral richness (number of viruses per sample) did not vary by health status. By contrast, total viral load (normalized proportion of sequences mapping to viruses) was significantly higher in ill individuals compared with healthy individuals. Furthermore, when ill, Kanyawara chimpanzees exhibited higher viral loads than Ngogo chimpanzees, and males, but not females, exhibited higher infection rates with certain viruses and higher total viral loads as they aged. Post-hoc analyses, including the use of a machine-learning classification method, indicated that one virus, salivirus (Picornaviridae), was the main contributor to health-related and community-level variation in viral loads. Another virus, chimpanzee stool-associated virus (chisavirus; unclassified Picornavirales), was associated with ill health at Ngogo but not at Kanyawara. Chisavirus, chimpanzee adenovirus (Adenoviridae), and bufavirus (Parvoviridae) were also associated with increased age in males. Associations with sex and age are consistent with the hypothesis that nonlethal viral infections cumulatively reflect or contribute to senescence in long-lived species such as chimpanzees.

From Molecular Pathology of COVID 19 to Nigella Sativum as a Treatment Option: Scientific Based Evidence of Its Myth or Reality

COVID-19 virus is a causative agent of viral pandemic in human beings which specifically targets respiratory system of humans and causes viral pneumonia. This unusual viral pneumonia is rapidly spreading to all parts of the world, currently affecting about 105 million people with 2.3 million deaths. Current review described history, genomic characteristics, replication, and pathogenesis of COVID-19 with special emphasis on Nigella sativum (N. sativum) as a treatment option. N. sativum seeds are historically and religiously used over the centuries, both for prevention and treatment of different diseases. This review summarizes the potential role of N. sativum seeds against COVID-19 infection at levels of in silico, cell lines and animal models.

Genetic Variability in Patients with HCV-Related Hepatocellular Carcinoma

Background

The present paper evaluates the genetic variability of HCV in patients with hepatocellular carcinoma (HCC).

Methods

Amino acid substitutions (aas) in NS3, NS5A and core regions were analyzed in 17 patients with HCC (Cases) and 13 without HCC (Controls), all naïve to DAAs. For the Cases, a sample of neoplastic liver tissue, non-neoplastic liver tissue and a serum sample were collected; for the Controls, a sample of liver tissue was collected. Sanger sequencing of three regions was performed using homemade protocols.

Results

Phylogenetic trees showed that there was no difference in the virus populations in the three compartments analyzed for the three HCV regions in patients with HCC. Low variability and no difference between the Cases and Controls were observed in the core and NS5A regions; however, in the NS3 region, a higher variability was observed in the Cases. No difference was observed in the core region between Cases and Controls. In NS3, aa substitutions at positions 103 and 122 were more frequently found in Cases than Controls (in both cases 50% vs 9.1%, p<0.05); moreover, aas in positions 32, 44 (p=0.035 for both), 79 (p=0.008) and 121 (p=0.018) were observed in the Cases and absent in the Controls. Finally, considering the NS5A region, aa substitutions at positions 37 and 54 were more frequently identified in the Cases than the Controls, but without statistical significance.

Conclusion

These data may suggest a higher aa variability in patients with HCC than in those without, especially in the NS3 region.

Autophagy Modulation by Viral Infections Influences Tumor Development

Autophagy is a self-degradative process important for balancing cellular homeostasis at critical times in development and/or in response to nutrient stress. This is particularly relevant in tumor model in which autophagy has been demonstrated to have an important impact on tumor behavior. In one hand, autophagy limits tumor transformation of precancerous cells in early stage, and in the other hand, it favors the survival, proliferation, metastasis, and resistance to antitumor therapies in more advanced tumors. This catabolic machinery can be induced by an important variety of extra- and intracellular stimuli. For instance, viral infection has often been associated to autophagic modulation, and the role of autophagy in virus replication differs according to the virus studied. In the context of tumor development, virus-modulated autophagy can have an important impact on tumor cells' fate. Extensive analyses have shed light on the molecular and/or functional complex mechanisms by which virus-modulated autophagy influences precancerous or tumor cell development. This review includes an overview of discoveries describing the repercussions of an autophagy perturbation during viral infections on tumor behavior.

Mitochondrial Dysfunction and Oxidative Stress in Liver Transplantation and Underlying Diseases: New Insights and Therapeutics

Mitochondria are essential organelles for cellular energy and metabolism. Like with any organ, the liver highly depends on the function of these cellular powerhouses. Hepatotoxic insults often lead to an impairment of mitochondrial activity and an increase in oxidative stress, thereby compromising the metabolic and synthetic functions. Mitochondria play a critical role in ATP synthesis and the production or scavenging of free radicals. Mitochondria orchestrate many cellular signaling pathways involved in the regulation of cell death, metabolism, cell division, and progenitor cell differentiation. Mitochondrial dysfunction and oxidative stress are closely associated with ischemia-reperfusion injury during organ transplantation and with different liver diseases, including cholestasis, steatosis, viral hepatitis, and drug-induced liver injury. To develop novel mitochondria-targeting therapies or interventions, a better understanding of mitochondrial dysfunction and oxidative stress in hepatic pathogenesis is very much needed. Therapies targeting mitochondria impairment and oxidative imbalance in liver diseases have been extensively studied in preclinical and clinical research. In this review, we provide an overview of how oxidative stress and mitochondrial dysfunction affect liver diseases and liver transplantation. Furthermore, we summarize recent developments of antioxidant and mitochondria-targeted interventions.

Dysregulation of host cell calcium signaling during viral infections: Emerging paradigm with high clinical relevance

Viral infections are one of the leading causes of human illness. Viruses take over host cell signaling cascades for their replication and infection. Calcium (Ca2+) is a versatile and ubiquitous second messenger that modulates plethora of cellular functions. In last two decades, a critical role of host cell Ca2+ signaling in modulating viral infections has emerged. Furthermore, recent literature clearly implicates a vital role for the organellar Ca2+ dynamics (influx and efflux across organelles) in regulating virus entry, replication and severity of the infection. Therefore, it is not surprising that a number of viral infections including current SARS-CoV-2 driven COVID-19 pandemic are associated with dysregulated Ca2+ homeostasis. The focus of this review is to first discuss the role of host cell Ca2+ signaling in viral entry, replication and egress. We further deliberate on emerging literature demonstrating hijacking of the host cell Ca2+ dynamics by viruses. In particular, a variety of viruses including SARS-CoV-2 modulate lysosomal and cytosolic Ca2+ signaling for host cell entry and replication. Moreover, we delve into the recent studies, which have demonstrated the potential of several FDA-approved drugs targeting Ca2+ handling machinery in inhibiting viral infections. Importantly, we discuss the prospective of targeting intracellular Ca2+ signaling for better management and treatment of viral pathogenesis including COVID-19. Finally, we highlight the key outstanding questions in the field that demand critical and timely attention.

Hepatitis C virus induces oxidation and degradation of apolipoprotein B to enhance lipid accumulation and promote viral production

Hepatitis C virus (HCV) infection induces the degradation and decreases the secretion of apolipoprotein B (ApoB). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Therefore, HCV infection-induced degradation of ApoB may contribute to hepatic steatosis and decreased lipoprotein secretion, but the mechanism of HCV infection-induced ApoB degradation has not been completely elucidated. In this study, we found that the ApoB level in HCV-infected cells was regulated by proteasome-associated degradation but not autophagic degradation. ApoB was degraded by the 20S proteasome in a ubiquitin-independent manner. HCV induced the oxidation of ApoB via oxidative stress, and oxidized ApoB was recognized by the PSMA5 and PSMA6 subunits of the 20S proteasome for degradation. Further study showed that ApoB was degraded at endoplasmic reticulum (ER)-associated lipid droplets (LDs) and that the retrotranslocation and degradation of ApoB required Derlin-1 but not gp78 or p97. Moreover, we found that knockdown of ApoB before infection increased the cellular lipid content and enhanced HCV assembly. Overexpression of ApoB-50 inhibited lipid accumulation and repressed viral assembly in HCV-infected cells. Our study reveals a novel mechanism of ApoB degradation and lipid accumulation during HCV infection and might suggest new therapeutic strategies for hepatic steatosis.

Hepatitis C virus (HCV) infection induces the degradation of apolipoprotein B (ApoB), which is the primary apolipoprotein in low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL). Impaired production and secretion of ApoB-containing lipoprotein is associated with an increase in hepatic steatosis. Thus, ApoB degradation might contribute to HCV infection-induced fatty liver. Here, we found that ApoB was not degraded through endoplasmic reticulum-associated degradation (ERAD) or autophagy, as reported previously. Instead, HCV infection induced ApoB oxidation through oxidative stress, and oxidatively damaged ApoB could be recognized and directly degraded by the 20S proteasome. We also found that ApoB was retrotranslocated from the endoplasmic reticulum (ER) to lipid droplets (LDs) for degradation. Through overexpression of ApoB-50, which can mediate the assembly and secretion of LDL and VLDL, we confirmed that ApoB degradation contributed to hepatocellular lipid accumulation induced by HCV infection. Additionally, expression of ApoB-50 impaired HCV production due to the observed decrease in lipid accumulation. In this study, we identified new mechanisms of ApoB degradation and HCV-induced lipid accumulation, and our findings might facilitate the development of novel therapeutic strategies for HCV infection-induced fatty liver.

Deubiquitination and Activation of the NLRP3 Inflammasome by UCHL5 in HCV-Infected Cells

Chronic hepatitis C virus (HCV) infection induces liver inflammation that can lead to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). Inflammation is the outcome of the action of proinflammatory cytokines and chemokines, including interleukin-1 beta (IL-1β) and tumor necrosis factor alpha. Mature IL-1β production and secretion are facilitated by active inflammasome complexes, including the NACHT-LRR pyrin domain-containing protein 3 (NLRP3) inflammasome. Our study shows that the NLRP3 inflammasome is activated in HCV-infected hepatocytes and that the activation is regulated by posttranslational modifications. NLRP3 is modified by lysine-63 ubiquitin chains in hepatocytes and is deubiquitinated during HCV infection. Inhibition of deubiquitinases (DUBs) with chemical inhibitors or blocking UCHL5 DUB expression with small interfering RNA (siRNA) abrogated NLRP3 inflammasome assembly and activation. Inhibition of inflammasome deubiquitination was correlated with a reduction in IL-1β maturation, decrease in HCV protein expression, and reduction in release of HCV from the cells. Together, this study suggests that HCV-induced activation of the NLRP3 inflammasome through posttranslational modification is crucial for the HCV life cycle and pathogenesis. IMPORTANCE HCV infection induces inflammation leading to fibrosis, cirrhosis, and cancer. The current study identifies the mechanisms leading to the activation of the NLRP3 inflammasome in hepatocytes, which is an important site of viral replication. Deubiquitination of NLRP3 by UCHL5 is required for inflammasome activation. Inhibition of deubiquitination blocks NLRP3 inflammasome activation and IL-1β maturation and also decreases HCV replication, suggesting the importance of the NLRP3 inflammasome in inflammation as well as other signaling pathways.

Daclatasvir and Sofosbuvir Mitigate Hepatic Fibrosis Through Downregulation of TNF-α / NF-κB Signaling Pathway

BACKGROUND

Hepatic fibrosis is the major issue in chronic liver diseases such as chronic hepatitis C virus (HCV). The newly approved direct acting antiviral (DAA) agents such as Sofosbuvir (SOF) and daclatasvir (DAC) have been found to be associated with decreased fibrotic markers in HCV patients.

AIM

This study tried to explore whether the reported antifibrotic effect of these drugs is antiviral dependent or drug induced.

METHOD

Hepatic fibrosis was induced by (0.5ml/kg) CCl4 IP twice a week for six weeks. SOF (20 mg/kg/d) and DAC (30 mg/kg/d) were added in the last four weeks of treatments. Liver functions, fibrotic markers such as Hyaluronic acid and metalloproteinase-9 were detected using immunoassay. The expression of TNF-α/NF-κB signaling pathway as well as Bcl-2 were done using immunoassay.

RESULTS

SOF and DAC exerted a potent antifibrotic effect evidenced by their activity against hyaluronic acid HA and metalloproteinase MMP-9 significantly (P≤0.001). This effect was further proved histopathologically where liver tissues from rats treated by drugs showed marked inhibition of collagen precipitation as well as inhibition of HSCs activation. This antifibrotic action was associated with decreased expression of TNF-α /NF-κB signaling pathway and induction of Bcl-2.

CONCLUSION

SOF/ DAC antifibrotic effect is independent of its antiviral activity. The molecular events associated with this effect were the downregulation of TNF-α / NF-κB signaling pathway and induction of Bcl-2.

Oxidative stress specifically inhibits replication of dengue virus

Reactive oxygen species (ROS) are chemically active species which are involved in maintaining cellular and signalling processes at physiological concentrations. Therefore, cellular components that regulate redox balance are likely to play a crucial role in viral life-cycle either as promoters of viral replication or with antiviral functions. Zinc is an essential micronutrient associated with anti-oxidative systems and helps in maintaining a balanced cellular redox state. Here, we show that zinc chelation leads to induction of reactive oxygen species (ROS) in epithelial cells and addition of zinc restores ROS levels to basal state. Addition of ROS (H₂O₂) inhibited dengue virus (DENV) infection in a dose-dependent manner indicating that oxidative stress has adverse effects on DENV infection. ROS affects early stages of DENV replication as observed by quantitation of positive and negative strand viral RNA. We observed that addition of ROS specifically affected viral titres of positive strand RNA viruses. We further demonstrate that ROS specifically altered SEC31A expression at the ER suggesting a role for SEC31A-mediated pathways in the life-cycle of positive strand RNA viruses and provides an opportunity to identify drug targets regulating oxidative stress responses for antiviral development.

Hepatitis C virus and carpal tunnel syndrome in hemodialysis patients: a single center cross-sectional study

OBJECTIVES

Carpal tunnel syndrome (CTS) is a common complication in maintenance hemodialysis (MHD) patients and leads to disabilities and increased risk of mortality. Hepatitis C virus (HCV) infection is associated with inflammatory and oxidative stress, and HCV infection can be cured. This study aimed at evaluating the association of HCV infection with CTS.

METHODS

Using a cross-sectional design, anthropometric and laboratory data were collected. Serum β₂-microglobulin, HCV antibody and HCV-RNA were measured. CTS was diagnosed according to clinical manifestation, electrophysiological test or ultrasonography. The related factors for CTS were analyzed by multivariate logistic regression.

RESULTS

This study included 113 participants, of whom 33 (29.2%) patients were positive for HCV antibody and 18 (15.9%) were positive for HCV antibody and HCV-RNA. Thirty-two (28.3%) patients were diagnosed with CTS. There were significant differences in the dialysis vintage, age of onset of MHD, high-sensitivity C-reactive protein, serum β₂M, anti-HCV-positive, HCV-RNA-positive, HCV load values and urine volume category between the CTS group and non-CTS group (p < 0.05). High-sensitivity C-reactive protein (OR: 1.238, 95% CI: 1.071-1.431, p = 0.004), dialysis vintage (OR: 1.017, 95% CI: 1.008-1.026, p < 0.001) and HCV-RNA-positive (OR: 5.929, 95% CI: 1.295-27.132, p = 0.022) rather than anti-HCV-positive were related factors for CTS.

CONCLUSIONS

High-sensitivity C-reactive protein, dialysis vintage and HCV-RNA replication but not previous HCV-infection were related factors for CTS in MHD patients. Further studies are needed to clarify whether intervention is beneficial for preventing and delaying the progression of CTS in MHD patients with HCV-RNA replication.

Calcium signaling in cancer progression and therapy

The old Greek aphorism 'Panta Rhei' ('everything flows') is true for all living things in general. As a dynamic process, calcium signaling plays fundamental roles in cellular activities under both normal and pathological conditions, with recent researches uncovering its involvement in cell proliferation, migration, survival, gene expression, and more. The major question we address here is how calcium signaling affects cancer progression and whether it could be targeted to combine with classic chemotherapeutics or emerging immunotherapies to improve their efficacy.

Attenuation of the upregulation of NF‑κB and AP‑1 DNA‑binding activities induced by tunicamycin or hypoxia/reoxygenation in neonatal rat cardiomyocytes by SERCA2a overexpression

The present study aimed to investigate the effects of the overexpression of sarco/endoplasmic reticulum Ca2+‑ATPase (SERCA2a) on endoplasmic reticulum (ER) stress (ERS)‑associated inflammation in neonatal rat cardiomyocytes (NRCMs) induced by tunicamycin (TM) or hypoxia/reoxygenation (H/R). The optimal multiplicity of infection (MOI) was 2 pfu/cell. Neonatal Sprague‑Dawley rat cardiomyocytes cultured in vitro were infected with adenoviral vectors carrying SERCA2a or enhanced green fluorescent protein genes, the latter used as a control. At 48 h following gene transfer, the NRCMs were treated with TM (10 µg/ml) or subjected to H/R to induce ERS. The results of electrophoretic mobility shift assay (EMSA) revealed that overexpression of SERCA2a attenuated the upregulation of nuclear factor (NF)‑κB and activator protein‑1 (AP‑1) DNA‑binding activities induced by TM or H/R. Western blot analysis and semi‑quantitative RT‑PCR revealed that the overexpression of SERCA2a attenuated the activation of the inositol‑requiring 1α (IRE1α) signaling pathway and ERS‑associated apoptosis induced by TM. The overexpression of SERCA2a also decreased the level of phospho‑p65 (Ser536) in the nucleus, as assessed by western blot analysis. However, the overexpression of SERCA2a induced the further nuclear translocation of NF‑κB p65 and higher levels of tumor necrosis factor (TNF)‑α transcripts in the NRCMs, indicating the occurrence of the ER overload response (EOR). Therefore, the overexpression of SERCA2a has a 'double‑edged sword' effect on ERS‑associated inflammation. On the one hand, it attenuates ERS and the activation of the IRE1α signaling pathway induced by TM, resulting in the attenuation of the upregulation of NF‑κB and AP‑1 DNA‑binding activities in the nucleus, and on the other hand, it induces EOR, leading to the further nuclear translocation of NF‑κB and the transcription of TNF‑α. The preceding EOR may precondition the NRCMs against subsequent ERS induced by TM. Further studies using adult rat cardiomyocytes are required to prevent the interference of EOR. The findings of the present study may enhance the current understanding of the role of SERCA2a in cardiomyocytes.

Elevation of Plasminogen Activator Inhibitor-1 promotes differentiation of Cancer Stem-like Cell state by Hepatitis C Virus infection

Plasminogen activator inhibitor-1 (PAI-1) is a critical factor that regulates protein synthesis and degradation. The increased PAI-1 levels are detectable in the serum of patients with chronic hepatitis C virus (HCV) liver disease. The differentiation state and motility of HCV-induced cancer stem-like cells (CSC) play a major role in severe liver disease progression. However, the role of PAI-1 in the pathological process of chronic liver diseases remains unknown. In this study, we determined how PAI-1 affects the differentiation of CSC state in hepatocytes upon HCV infection. We found that HCV infection induced the expression of PAI-1 while decreasing miR-30c expression in Huh7.5.1 cells. Similar results were obtained from isolated hepatocytes from humanized liver mice after HCV infection. Moreover, decreased miR-30c expression in HCV-infected hepatocytes was associated with the increased levels of PAI-1 mRNA and protein. Notably, the increased PAI-1 levels resulted in the activation of Protein Kinase B/AKT, a major mediator of cell proliferation, in HCV-infected hepatocytes along with the increased expression of CSC markers such as Human Differentiated Protein (CD) 133, Epithelial cell adhesion molecule (EpCAM), Octamer 4 (Oct4), Nanog, Cyclin D1, and MYC. Moreover, blockade of PAI-1 activity by miR-30c mimic and anti-PAI-1 mAb abrogated the AKT activation with decreased expression of CSC markers. Our findings suggest that HCV infection induces the CSC state via PAI-1-mediated AKT activation in hepatocytes. It implicates that the manipulation of PAI-1 activity could provide potential therapeutics to prevent the development of HCV-associated chronic liver diseases.IMPORTANCEThe progression of chronic liver disease by HCV infection is considered a major risk factor for hepatocellular carcinoma (HCC), one of the major causes of death from cancer. Recent studies have demonstrated that increased CSC properties in HCV-infected hepatocytes are associated with the progression of HCC. Since proteins and miRNAs production by HCV-infected hepatocytes can play various roles in physiological processes, investigating these factors can potentially lead to new therapeutic targets. However, the mechanism of HCV associated progression of hepatocytes to CSC remains unclear. Here we identify the roles of PAI-1 and miR-30c in the progression of CSC during HCV infection in hepatocytes. Our data shows that increased secretion of PAI-1 following HCV infection promotes this CSC state and activation of AKT. We report that the inhibition of PAI-1 by miR-30c mimic reduces HCV associated CSC properties in hepatocytes. Taken together, targeting this interaction of secreted PAI-1 and miR-30c in HCV-infected hepatocytes may provide a potential therapeutic intervention against the progression to chronic liver diseases and HCC.

Signal transducer and activator of transcription 3 (STAT3) acts as a proviral factor for dengue virus propagation

Dengue fever is a significant mosquito-borne viral disease that affects millions of people every year. As a co-existing mechanism, DENV has evolved to evade elimination by the host antiviral immune system. DENV is reported to modulate host interferon response either by attenuating the factors that mediate interferon response like STAT1 and STAT2 or inhibiting the activation of STAT1 or by STAT2 degradation. Through this study we aim to understand how DENV modulates STAT3 mediated interferon response to its own advantage. We employed various techniques like Western blot, Confocal microscopy, RT-PCR to show that STAT3 acts as a pro-viral factor for DV-2 propagation. As per result of the present study STAT3 is upregulated as well as activated by phosphorylation in DV-2 infected A549 cells. Additionally, STAT3 knockdown led to a significant decrease in expression of viral proteins as well as viral replication. We show that DV-2 strategically tweaks STAT3 which is a negative regulator of Type I IFN signaling, in order to evade host Type I and Type III interferon response by upregulating its expression and activation. Our results demonstrate the proviral role of STAT3 for DV-2 propagation which is correlated to activation by tyrosine phosphorylation. Furthermore, since STAT3 is critical factor for DV-2 propagation, its modulation can facilitate targeted development of antivirals against Dengue.

Endoplasmic reticulum & mitochondrial calcium homeostasis: The interplay with viruses

Calcium ions (Ca²⁺) act as secondary messengers in a plethora of cellular processes and play crucial role in cellular organelle function and homeostasis. The average resting concentration of Ca²⁺ is nearly 100 nM and in certain cells it can reach up to 1 µM. The high range of Ca²⁺ concentration across the plasma membrane and intracellular Ca²⁺ stores demands a well-coordinated maintenance of free Ca²⁺ via influx, efflux, buffering and storage. Endoplasmic Reticulum (ER) and Mitochondria depend on Ca²⁺ for their function and also serve as major players in intracellular Ca²⁺ homeostasis. The ER-mitochondria interplay helps in orchestrating cellular calcium homeostasis to avoid any detrimental effect resulting from Ca²⁺ overload or depletion. Since Ca²⁺ plays a central role in many biological processes it is an essential component of the virus-host interactions. The large gradient across membranes enable the viruses to easily modulate this buffered environment to meet their needs. Viruses exploit Ca²⁺ signaling to establish productive infection and evade the host immune defense. In this review we will detail the interplay between the viruses and cellular & ER-mitochondrial calcium signaling and the significance of these events on viral life cycle and disease pathogenesis.

The endoplasmic reticulum unfolded protein response - homeostasis, cell death and evolution in virus infections

Viruses elicit cell and organismic stress, and offset homeostasis. They trigger intrinsic, innate and adaptive immune responses, which limit infection. Viruses restore homeostasis by harnessing evolutionary conserved stress responses, such as the endoplasmic reticulum (ER) unfolded protein response (UPR^ER). The canonical UPR^ER restores homeostasis based on a cell-autonomous signalling network modulating transcriptional and translational output. The UPR^ER remedies cell damage, but upon severe and chronic stress leads to cell death. Signals from the UPR^ER flow along three branches with distinct stress sensors, the inositol requiring enzyme (Ire) 1, protein kinase R (PKR)-like ER kinase (PERK), and the activating transcription factor 6 (ATF6). This review shows how both enveloped and non-enveloped viruses use the UPR^ER to control cell stress and metabolic pathways, and thereby enhance infection and progeny formation, or undergo cell death. We highlight how the Ire1 axis bypasses apoptosis, boosts viral transcription and maintains dormant viral genomes during latency and persistence periods concurrent with long term survival of infected cells. These considerations open new options for oncolytic virus therapies against cancer cells where the UPR^ER is frequently upregulated. We conclude with a discussion of the evolutionary impact that viruses, in particular retroviruses, and anti-viral defense has on the UPR^ER.

The Impact of Hepatitis C Virus Genotypes on Oxidative Stress Markers and Catalase Activity

Hepatitis C virus (HCV) is a major cause of liver disease worldwide. Chronic HCV infections are usually associated with increased oxidative stress in the liver tissue. The intensity of oxidative stress may be a detrimental factor in liver injury and may determine the severity of the disease. The aim of the present case-control study was to determine the level of lipid peroxidation (TBARS), protein oxidative modification (AOPP), and catalase activity in sera of patients infected with HCV, in relation to different HCV genotypes and viral load. Considering the HCV patients with chronic hepatitis C (52) and control subject (50) recruitment, the study was designed as a case-control-type. The HCV RNA isolation, viral load, and HCV genotyping were performed according to the standard protocols. A significant difference compared to control healthy subjects was reported for TBAR (p < 0.001), AOPP (p = 0.001), and catalase activity (p = 0.007). In a gender-based comparison, a significantly higher level of AOPP for females was reported (p < 0.001). As stratified by HCV genotype, the most common was HCV-1 (HCV-1a and HCV 1b), with the overall participation of more than 60%, followed by genotype 3, while the least represented was genotype 2. No significant difference was documented among genotypes in regard to oxidative stress markers, although somewhat higher TBARS level, but not significant, was registered in patients infected with genotype 1b. A statistically significant positive correlation was found between the concentration of HCV genome copies and AOPP (r = 0.344; p = 0.012). A high level of HCV viral load was more likely to have a higher TBARS, but still without statistical significance (p = 0.072). In conclusion, the results obtained confirmed an imbalance between the ROS production and antioxidative defense system in HCV-infected patients. Since oxidative stress may have a profound influence on disease progression, fibrosis, and carcinogenesis, our results may meet the aspirations of mandatory introduction of antioxidants as early HCV therapy to counteract ROS consequences.

Enhanced immune responses, PI3K/AKT and JAK/STAT signaling pathways following hepatitis C virus eradication by direct-acting antiviral therapy among Egyptian patients: a case control study

The use of direct-acting antivirals (DAAs) therapy for the treatment of hepatitis C virus (HCV) results in a high-sustained virological response (SVR) and subsequently alters liver immunologic environment. However, hepatocellular carcinoma (HCC) may occur after DAAs treatment. We aimed to clarify changes of immune responses, PI3K/AKT and JAK/STAT signaling pathways in HCV-induced liver diseases and HCC following DAAs treatment. Four cohorts were classified as chronic HCV patients, HCV-related cirrhosis without HCC, HCV-related cirrhosis and HCC, and healthy control group. The patient groups were further divided into treated or untreated with DAAs with SVR12. Increased percentages of CD3, CD8 and CD4, decreased CD4/FoxP3/CD25, CD8/PD-1 and CD19/PDL-1 were found in DAAs-treated patients in the three HCV groups. Following DAAs therapy, the levels of ROS, IL-1β, IL-6, IL-8 and TNF-α were significantly decreased in the three HCV groups. Treated HCV patients showed up regulation of p-AKT and p-STAT5 and down regulation of p-STAT3, HIF-1α and COX-2. In conclusion, DAAs enhance the immune response in chronic HCV and liver cirrhosis, hence our study is the first to show change in PI3K/AKT and JAK/STAT signaling pathways in different HCV-induced liver diseases after DAAs. In chronic HCV, DAAs have better impact on the immune response while in liver cirrhosis not all immune changes were prominent.

The Hepatitis C virus NS5A and core proteins exert antagonistic effects on HAMP gene expression: the hidden interplay with the MTF-1/MRE pathway

Hepcidin, a 25-amino acid peptide encoded by the HAMP gene and produced mainly by hepatocytes and macrophages, is a mediator of innate immunity and the central iron-regulatory hormone. Circulating hepcidin controls iron efflux by inducing degradation of the cellular iron exporter ferroportin. HCV infection is associated with hepatic iron overload and elevated serum iron, which correlate with poor antiviral responses. The HCV nonstructural NS5A protein is known to function in multiple aspects of the HCV life cycle, probably exerting its activity in concert with cellular factor(s). In this study, we attempted to delineate the effect of HCV NS5A on HAMP gene expression. We observed that transient transfection of hepatoma cell lines with HCV NS5A resulted in down-regulation of HAMP promoter activity. A similar effect was evident after transduction of Huh7 cells with a recombinant baculovirus vector expressing NS5A protein. We proceeded to construct an NS5A-expressing stable cell line, which also exhibited down-regulation of HAMP gene promoter activity and significant reduction of HAMP mRNA and hepcidin protein levels. Concurrent expression of HCV core protein, a well-characterized hepcidin inducer, revealed antagonism between those two proteins for hepcidin regulation. In attempting to identify the pathways involved in NS5A-driven reduction of hepcidin levels, we ruled out any NS5A-induced alterations in the expression of the well-known hepcidin inducers SMAD4 and STAT3. Further analysis linked the abundance of intracellular zinc ions and the deregulation of the MTF-1/MRE/hepcidin axis with the observed phenomenon. This effect could be associated with distinct phases in HCV life cycle.

Oxidative Stress Induces Mitochondrial Compromise in CD4 T Cells From Chronically HCV-Infected Individuals

We have previously shown that chronic Hepatitis C virus (HCV) infection can induce DNA damage and immune dysfunctions with excessive oxidative stress in T cells. Furthermore, evidence suggests that HCV contributes to increased susceptibility to metabolic disorders. However, the underlying mechanisms by which HCV infection impairs cellular metabolism in CD4 T cells remain unclear. In this study, we evaluated mitochondrial mass and intracellular and mitochondrial reactive oxygen species (ROS) production by flow cytometry, mitochondrial DNA (mtDNA) content by real-time qPCR, cellular respiration by seahorse analyzer, and dysregulated mitochondrial-localized proteins by Liquid Chromatography-Mass Spectrometry (LC-MS) in CD4 T cells from chronic HCV-infected individuals and health subjects. Mitochondrial mass was decreased while intracellular and mitochondrial ROS were increased, expressions of master mitochondrial regulators peroxisome proliferator-activated receptor 1 alpha (PGC-1α) and mitochondrial transcription factor A (mtTFA) were down-regulated, and oxidative stress was increased while mitochondrial DNA copy numbers were reduced. Importantly, CRISPR/Cas9-mediated knockdown of mtTFA impaired cellular respiration and reduced mtDNA copy number. Furthermore, proteins responsible for mediating oxidative stress, apoptosis, and mtDNA maintenance were significantly altered in HCV-CD4 T cells. These results indicate that mitochondrial functions are compromised in HCV-CD4 T cells, likely via the deregulation of several mitochondrial regulatory proteins.

Adenosylhomocysteinase like 1 interacts with nonstructural 5A and regulates hepatitis C virus propagation

Hepatitis C virus (HCV) life cycle is highly dependent on cellular proteins for viral propagation. In order to identify the cellular factors involved in HCV propagation, we previously performed a protein microarray assay using the HCV nonstructural 5A (NS5A) protein as a probe. Of ∼9,000 human cellular proteins immobilized in a microarray, adenosylhomocysteinase like 1 (AHCYL1) was among 90 proteins identified as NS5A interactors. Of these candidates, AHCYL1 was selected for further study. In the present study, we verified the physical interaction between NS5A and AHCYL1 by both in vitro pulldown and coimmunoprecipitation assays. Furthermore, HCV NS5A interacted with endogenous AHCYL1 in Jc1-infected cells. Both NS5A and AHCYL1 were colocalized in the cytoplasmic region in HCV-replicating cells. siRNAmediated knockdown of AHCYL1 abrogated HCV propagation. Exogenous expression of the siRNA-resistant AHCYL1 mutant, but not of the wild-type AHCYL1, restored HCV protein expression levels, indicating that AHCYL1 was required specifically for HCV propagation. Importantly, AHCYL1 was involved in the HCV internal ribosome entry site-mediated translation step of the HCV life cycle. Finally, we demonstrated that the proteasomal degradation pathway of AHCYL1 was modulated by persistent HCV infection. Collectively, these data suggest that HCV may modulate the AHCYL1 protein to promote viral propagation.

HCV-Associated Exosomes Upregulate RUNXOR and RUNX1 Expressions to Promote MDSC Expansion and Suppressive Functions through STAT3-miR124 Axis

RUNX1 overlapping RNA (RUNXOR) is a long non-coding RNA and plays a pivotal role in the differentiation of myeloid cells via targeting runt-related transcription factor 1 (RUNX1). We and others have previously reported that myeloid-derived suppressor cells (MDSCs) expand and inhibit host immune responses during chronic viral infections; however, the mechanisms responsible for MDSC differentiation and suppressive functions, in particular the role of RUNXOR–RUNX1, remain unclear. Here, we demonstrated that RUNXOR and RUNX1 expressions are significantly upregulated and associated with elevated levels of immunosuppressive molecules, such as arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), signal transducer and activator of transcription 3 (STAT3), and reactive oxygen species (ROS) in MDSCs during chronic hepatitis C virus (HCV) infection. Mechanistically, we discovered that HCV-associated exosomes (HCV-Exo) can induce the expressions of RUNXOR and RUNX1, which in turn regulates miR-124 expression via STAT3 signaling, thereby promoting MDSC differentiation and suppressive functions. Importantly, overexpression of RUNXOR in healthy CD33⁺ myeloid cells promoted differentiation and suppressive functions of MDSCs. Conversely, silencing RUNXOR or RUNX1 expression in HCV-derived CD33⁺ myeloid cells significantly inhibited their differentiation and expressions of suppressive molecules and improved the function of co-cultured autologous CD4 T cells. Taken together, these results indicate that the RUNXOR–RUNX1–STAT3–miR124 axis enhances the differentiation and suppressive functions of MDSCs and could be a potential target for immunomodulation in conjunction with antiviral therapy during chronic HCV infection.

Chronic hepatitis C infection induces cardiovascular disease and type 2 diabetes: mechanisms and management

Despite the availability of effective treatments, hepatitis C virus (HCV) still remains a threat to public health. HCV is capable to trigger, behind liver damage, extrahepatic manifestations, including cardiovascular disease and type 2 diabetes (T2DM). A close association has been reported between HCV infection and cardiovascular disease due to imbalances in metabolic pathways and chronic inflammation. HCV through both direct and indirect mechanisms causes a higher incidence of ischemic stroke, acute coronary syndrome, heart failure and peripheral arterial disease. In addition, a higher risk of death from cardiovascular events has been showed in HCV patients. Insulin resistance is a hallmark of HCV infection and represents the link between HCV and T2DM, which is one of the most frequent HCV-associated extrahepatic manifestations. The pathological basis of the increased risk of T2DM in HCV infection is provided by the alterations of the molecular mechanisms of IR induced both by the direct effects of the HCV proteins, and by the indirect effects mediated by chronic inflammation, oxidative stress and hepatic steatosis. T2DM increases the risk of compensated and decompensate cirrhosis and hepatocellular carcinoma as well as increases the risk of cardiovascular disease, lower limb amputation and end stage renal disease. Current evidence suggests that HCV eradication reduces the incidence and mortality of cardiovascular disease and T2DM, further underling the importance of public health strategies for eradication the infection. The aim of this review was to update evidence and management of interaction between HCV, cardiovascular disease, and T2DM in the era of DAA treatment.

Hepatitis C virus associated hepatocellular carcinoma

Liver cancer is a global problem and hepatocellular carcinoma (HCC) accounts for about 85% of this cancer. In the USA, etiologies and risk factors for HCC include chronic hepatitis C virus (HCV) infection, diabetes, non-alcoholic steatohepatitis (NASH), obesity, excessive alcohol drinking, exposure to tobacco smoke, and genetic factors. Chronic HCV infection appears to be associated with about 30% of HCC. Chronic HCV infection induces multistep changes in liver, involving metabolic disorders, steatosis, cirrhosis and HCC. Liver carcinogenesis requires initiation of neoplastic clones, and progression to clinically diagnose malignancy. Tumor progression associates with profound exhaustion of tumor-antigen-specific CD8⁺T cells, and accumulation of PD-1^hi CD8⁺T cells and Tregs. In this chapter, we provide a brief description of HCV and environmental/genetic factors, immune regulation, and highlight mechanisms of HCV associated HCC. We also underscore HCV treatment and recent paradigm of HCC progression, highlighted the current treatment and potential future therapeutic opportunities.

The Dynamic Interface of Viruses with STATs

Viruses commonly antagonize the antiviral type I interferon response by targeting signal transducer and activator of transcription 1 (STAT1) and STAT2, key mediators of interferon signaling. Other STAT family members mediate signaling by diverse cytokines important to infection, but their relationship with viruses is more complex. Importantly, virus-STAT interaction can be antagonistic or stimulatory depending on diverse viral and cellular factors. While STAT antagonism can suppress immune pathways, many viruses promote activation of specific STATs to support viral gene expression and/or produce cellular conditions conducive to infection. It is also becoming increasingly clear that viruses can hijack noncanonical STAT functions to benefit infection. For a number of viruses, STAT function is dynamically modulated through infection as requirements for replication change. Given the critical role of STATs in infection by diverse viruses, the virus-STAT interface is an attractive target for the development of antivirals and live-attenuated viral vaccines. Here, we review current understanding of the complex and dynamic virus-STAT interface and discuss how this relationship might be harnessed for medical applications.

Epstein-Barr Virus Promotes B Cell Lymphomas by Manipulating the Host Epigenetic Machinery

Simple Summary

Epstein-Barr Virus (EBV)-induced lymphomas have a significant global incidence, given the widespread infection to the human population. EBV adopts several mechanisms to replicate and persist in the host, by hijacking its epigenetic machinery. The main topic of this review details the current insights of EBV interactions with the host epigenetic system, and it will be discussed the potential relationship between the EBV-induced chronic inflammation and the dysregulation of epigenetic modifiers that might lead to tumorigenesis. Promising novel therapies against several types of cancer involve the use of epigenetic modifier inhibitors. To design new therapeutical strategies targeting lymphomas, it is crucial to conduct exhaustive reaserch on the regulation of these enzymes.

Abstract

During the past decade, the rapid development of high-throughput next-generation sequencing technologies has significantly reinforced our understanding of the role of epigenetics in health and disease. Altered functions of epigenetic modifiers lead to the disruption of the host epigenome, ultimately inducing carcinogenesis and disease progression. Epstein–Barr virus (EBV) is an endemic herpesvirus that is associated with several malignant tumours, including B-cell related lymphomas. In EBV-infected cells, the epigenomic landscape is extensively reshaped by viral oncoproteins, which directly interact with epigenetic modifiers and modulate their function. This process is fundamental for the EBV life cycle, particularly for the establishment and maintenance of latency in B cells; however, the alteration of the host epigenetic machinery also contributes to the dysregulated expression of several cellular genes, including tumour suppressor genes, which can drive lymphoma development. This review outlines the molecular mechanisms underlying the epigenetic manipulation induced by EBV that lead to transformed B cells, as well as novel therapeutic interventions to target EBV-associated B-cell lymphomas.

Mitochondria Targeted Viral Replication and Survival Strategies-Prospective on SARS-CoV-2

SARS-CoV-2 is a positive sense RNA coronavirus that constitutes a new threat for the global community and economy. While vaccines against SARS-CoV-2 are being developed, the mechanisms through which this virus takes control of an infected cell to replicate remains poorly understood. Upon infection, viruses completely rely on host cell molecular machinery to survive and replicate. To escape from the immune response and proliferate, viruses strategically modulate cellular metabolism and alter subcellular organelle architecture and functions. One way they do this is by modulating the structure and function of mitochondria, a critical cellular metabolic hub but also a key platform for the regulation of cellular immunity. This versatile nature of mitochondria defends host cells from viruses through several mechanisms including cellular apoptosis, ROS signaling, MAVS activation and mitochondrial DNA-dependent immune activation. These events are regulated by mitochondrial dynamics, a process by which mitochondria alter their structure (including their length and connectivity) in response to stress or other cues. It is therefore not surprising that viruses, including coronaviruses hijack these processes for their survival. In this review, we highlight how positive sense RNA viruses modulate mitochondrial dynamics and metabolism to evade mitochondrial mediated immune response in order to proliferate.

Molecular Mechanisms Underlying Hepatocellular Carcinoma Induction by Aberrant NRF2 Activation-Mediated Transcription Networks: Interaction of NRF2-KEAP1 Controls the Fate of Hepatocarcinogenesis

NF-E2-related factor 2 (NRF2) is a basic leucine zipper transcription factor, a master regulator of redox homeostasis regulating a variety of genes for antioxidant and detoxification enzymes. NRF2 was, therefore, initially thought to protect the liver from oxidative stress. Recent studies, however, have revealed that mutations in NRF2 cause aberrant accumulation of NRF2 in the nucleus and exert the upregulation of NRF2 target genes. Moreover, among all molecular changes in hepatocellular carcinoma (HCC), NRF2 activation has been revealed as a more prominent pathway contributing to the progression of precancerous lesions to malignancy. Nevertheless, how its activation leads to poor prognosis in HCC patients remains unclear. In this review, we provide an overview of how aberrant activation of NRF2 triggers HCC development. We also summarize the emerging roles of other NRF family members in liver cancer development.

Hepatitis C Virus and Hepatocellular Carcinoma: When the Host Loses Its Grip

Chronic infection with hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma (HCC). Novel treatments with direct-acting antivirals achieve high rates of sustained virologic response; however, the HCC risk remains elevated in cured patients, especially those with advanced liver disease. Long-term HCV infection causes a persistent and accumulating damage of the liver due to a combination of direct and indirect pro-oncogenic mechanisms. This review describes the processes involved in virus-induced disease progression by viral proteins, derailed signaling, immunity, and persistent epigenetic deregulation, which may be instrumental to develop urgently needed prognostic biomarkers and as targets for novel chemopreventive therapies.