Type B coxsackieviruses and their interactions with the innate and adaptive immune systems

Baicalein suppresses Coxsackievirus B3 replication by inhibiting caspase-1 and viral protease 2A

Myocarditis is an inflammatory disease of the cardiac muscle and one of the primary causes of dilated cardiomyopathy. Group B coxsackievirus (CVB) is one of the leading causative pathogens of viral myocarditis, which primarily affects children and young adults. Due to the lack of vaccines, the development of antiviral medicines is crucial to controlling CVB infection and the progression of myocarditis. In this study, we investigated the antiviral effect of baicalein, a flavonoid extracted from Scutellaria baicaleinsis. Our results demonstrated that baicalein treatment significantly reduced cytopathic effect and increased cell viability in CVB3-infected cells. In addition, significant reductions in viral protein 3D, viral RNA, and viral particles were observed in CVB3-infected cells treated with baicalein. We found that baicalein exerted its inhibitory effect in the early stages of CVB3 infection. Baicalein also suppressed viral replication in the myocardium and effectively alleviated myocarditis induced by CVB3 infection. Our study revealed that baicalein exerts its antiviral effect by inhibiting the activity of caspase-1 and viral protease 2A. Taken together, our findings demonstrate that baicalein has antiviral activity against CVB3 infection and may serve as a potential therapeutic option for the myocarditis caused by enterovirus infection.

Antiviral activity of sulphated specialized metabolites from sea urchin Clypeaster humilis: in vitro and in silico studies

Chemical investigations of the sea urchin Clypeaster humilis has led to separation of twelve compounds including one new sulfonic acid derivative (7R) tridec-1-en-7-yl hydrogen sulphate (1), first isolated from natural source, pyridine-3-yl methane sulfonate (2), and first isolated from marine organisms, boldine (12), in addition to nine known compounds (3-11), which were isolated for the first time from the genus Clypeaster. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR), HR-ESI-MS as well as comparison with the previously reported data. The antiviral activity of the crude extract and sulphated compounds were evaluated using MTT colorimetric assay against Coxsackie B4 virus. The crude extract and compound 1 showed very potent antiviral activity with a percentage of inhibition equal to 89.7 ± 0.53% and 86.1 ± 0.92%, respectively. Results of the molecular docking analysis of the isolated compounds within Coxsackie Virus B4 (COX-B4) X-ray crystal structure and quantum chemical calculation for three sulphated compounds are in a consistent adaptation with the in vitro antiviral results. The pharmacokinetic properties (ADME) of isolated compounds were determined.

Breaking the barriers in cancer care: The next generation of herpes simplex virus-based oncolytic immunotherapies for cancer treatment

Since the US Food and Drug Administration first approved talimogene laherparepvec for the treatment of melanoma in 2015, the field of oncolytic immunotherapy (OI) has rapidly evolved. There are numerous ongoing clinical studies assessing the clinical activity of OIs across a wide range of tumor types. Further understanding of the mechanisms underlying the anti-tumor immune response has led to the development of OIs with improved immune-mediated preclinical efficacy. In this review, we discuss the key approaches for developing the next generation of herpes simplex virus-based OIs. Modifications to the viral genome and incorporation of transgenes to promote safety, tumor-selective replication, and immune stimulation are reviewed. We also review the advantages and disadvantages of intratumoral versus intravenous administration, summarize clinical evidence supporting the use of OIs as a strategy to overcome resistance to immune checkpoint blockade, and consider emerging opportunities to improve OI efficacy in the combination setting.

Antiviral Activity of trans-Hexenoic Acid against Coxsackievirus B and Enterovirus A71

Enterovirus infections are life-threatening viral infections which occur mainly among children and are possible causes of viral outbreak. Until now, treatment and management of infections caused by members of the genus Enterovirus largely depended on supportive care, and no antiviral medications are currently approved for the treatment of most of these infections. The urgency of discovering new therapeutic options for the treatment of enterovirus infection is increasing. In the present study, we identified that trans-2-hexenoic acid (THA), a natural product from a dietary source, possesses antiviral activity against coxsackievirus B (CVB) and enterovirus A71 (EV-A71) in a dose-dependent manner. We found that THA possesses antiviral activity at 50% effective concentrations (EC50) of 2.9 μM and 3.21 μM against CVB3 and EV-A71 infections, respectively. The time of addition assay revealed that THA inhibits both CVB3 and EV-A71 replication at the entry stage of infection. Additional results from this study further suggest that THA inhibits viral replication by blocking viral entry. Given that THA has received approval as a food additive, treatment of enterovirus infections with THA might be a safe therapeutic option or could pave the way for semisynthetic manufacturing of more antiviral drugs in the future.

Exosomes mediate Coxsackievirus B3 transmission and expand the viral tropism

Specific virus-receptor interactions are important determinants in viral host range, tropism and pathogenesis, influencing the location and initiation of primary infection as well as viral spread to other target organs/tissues in the postviremic phase. Coxsackieviruses of Group B (CVB) and its six serotypes (CVB1-6) specifically interact with two receptor proteins, coxsackievirus-adenovirus receptor (CAR) and decay-accelerating factor (DAF), and cause various lesions in most permissive tissues. However, our previous data and other studies revealed that virus receptor-negative cells or tissues can be infected with CVB type 3 (CVB3), which can also effectively replicate. To study this interesting finding, we explored the possibility that exosomes are involved in CVB3 tropism and that exosomes functionally enhance CVB3 transmission. We found that exosomes carried and delivered CVB3 virions, resulting in efficient infection in receptor-negative host cells. We also found that delivery of CVB3 virions attached to exosomes depended on the virus receptor CAR. Importantly, exosomes carrying CVB3 virions exhibited greater infection efficiency than free virions because they accessed various entry routes, overcoming restrictions to viral tropism. In vivo experiments demonstrated that inhibition of exosome coupling with virions attenuated CVB3-induced immunological system dysfunction and reduced mortality. Our study describes a new mechanism in which exosomes contribute to viral tropism, spread, and pathogenesis.

Association of toll-like receptors single nucleotide polymorphisms with HBV and HCV infection: research status

Background

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections have become increasingly severe worldwide and are a threat to public health. There have been a number of studies conducted recently on the relationship of single nucleotide polymorphisms (SNPs) to innate immune receptor genes such as toll-like receptors (TLRs). Some literature suggests that SNPs of TLRs are associated with HBV and HCV infection. We summarized the role of TLRs gene polymorphisms associated with HBV and HCV infections and explored their possible mechanisms of action.

Methodology

PubMed and Web of Science were used to perform the literature review. Related articles and references were identified and used to analyze the role of TLRs gene polymorphism in HBV and HCV infection.

Results

TLRs gene polymorphisms may have beneficial or detrimental effects in HBV and HCV infection, and some SNPs can affect disease progression or prognosis. They affect the disease state by altering gene expression or protein synthesis; however, the mechanism of action is not clearly understood.

Conclusions

Single nucleotide polymorphisms of TLRs play a role in HBV and HCV infection, but the mechanism of action still needs to be explored in future studies.

Interaction between non-coding RNAs and Toll-like receptors

Toll-like receptors (TLRs) are a large group of pattern recognition receptors which are involved in the regulation of innate immune responses. Based on the interplay between TLRs and adapter molecules, two distinctive signaling cascades, namely the MyD88-dependent and TRIF-dependent pathways have been recognized. TLRs are involved in the development of a wide variety of diseases including cancer and autoimmune disorders. A large body of evidence has shown interaction between two classes of non-coding RNAs, namely microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). These interactions have prominent roles in the pathogenesis of several disorders including infectious disorders, autoimmune conditions and neoplastic disorders. This review aims at description of the interaction between these non-coding RNAs and TLRs.

Essential Role of Non-Coding RNAs in Enterovirus Infection: From Basic Mechanisms to Clinical Prospects

Enteroviruses (EVs) are common RNA viruses that can cause various types of human diseases and conditions such as hand, foot, and mouth disease (HFMD), myocarditis, meningitis, sepsis, and respiratory disorders. Although EV infections in most patients are generally mild and self-limiting, a small number of young children can develop serious complications such as encephalitis, acute flaccid paralysis, myocarditis, and cardiorespiratory failure, resulting in fatalities. Established evidence has suggested that certain non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs) are involved in the occurrence and progression of many human diseases. Recently, the involvement of ncRNAs in the course of EV infection has been reported. Herein, the authors focus on recent advances in the understanding of ncRNAs in EV infection from basic viral pathogenesis to clinical prospects, providing a reference basis and new ideas for disease prevention and research directions.

Mitigated viral myocarditis in A/J mice by the immunoproteasome inhibitor ONX 0914 depends on inhibition of systemic inflammatory responses in CoxsackievirusB3 infection

A preclinical model of troponin I-induced myocarditis (AM) revealed a prominent role of the immunoproteasome (ip), the main immune cell-resident proteasome isoform, in heart-directed autoimmunity. Viral infection of the heart is a known trigger of cardiac autoimmunity, with the ip enhancing systemic inflammatory responses after infection with a cardiotropic coxsackievirusB3 (CV). Here, we used ip-deficient A/J-LMP7-/- mice to investigate the role of ip-mediated effects on adaptive immunity in CV-triggered myocarditis and found no alteration of the inflammatory heart tissue damage or cardiac function in comparison to wild-type controls. Aiming to define the impact of the systemic inflammatory storm under the control of ip proteolysis during CV infection, we targeted the ip in A/J mice with the inhibitor ONX 0914 after the first cycle of infection, when systemic inflammation has set in, well before cardiac inflammation. During established acute myocarditis, the ONX 0914 treatment group had the same reduction in cardiac output as the controls, with inflammatory responses in heart tissue being unaffected by the compound. Based on these findings and with regard to the known anti-inflammatory role of ONX 0914 in CV infection, we conclude that the efficacy of ip inhibitors for CV-triggered myocarditis in A/J mice relies on their immunomodulatory effects on the systemic inflammatory reaction.

Inhibition of Type III Interferon Expression in Intestinal Epithelial Cells-A Strategy Used by Coxsackie B Virus to Evade the Host's Innate Immune Response at the Primary Site of Infection?

Increasing evidence highlights the importance of the antiviral activities of the type III interferons (IFNλs; IL-28A, IL-28B, IL29, and IFNλ4) in the intestine. However, many viruses have developed strategies to counteract these defense mechanisms by preventing the production of IFNs. Here we use infection models, a clinical virus isolate, and several molecular biology techniques to demonstrate that both type I and III IFNs induce an antiviral state and attenuate Coxsackievirus group B (CVB) replication in human intestinal epithelial cells (IECs). While treatment of IECs with a viral mimic (poly (I:C)) induced a robust expression of both type I and III IFNs, no such up-regulation was observed after CVB infection. The blunted IFN response was paralleled by a reduction in the abundance of proteins involved in the induction of interferon gene transcription, including TIR-domain-containing adapter-inducing interferon-β (TRIF), mitochondrial antiviral-signaling protein (MAVS), and the global protein translation initiator eukaryotic translation initiation factor 4G (eIF4G). Taken together, this study highlights a potent anti-Coxsackieviral effect of both type I and III IFNs in cells located at the primary site of infection. Furthermore, we show for the first time that the production of type I and III IFNs in IECs is blocked by CVBs. These findings suggest that CVBs evade the host immune response in order to successfully infect the intestine.

Enterovirus D68 molecular and cellular biology and pathogenesis

In recent years, enterovirus D68 (EV-D68) has advanced from a rarely detected respiratory virus to a widespread pathogen responsible for increasing rates of severe respiratory illness and acute flaccid myelitis (AFM) in children worldwide. In this review, we discuss the accumulating data on the molecular features of EV-D68 and place these into the context of enterovirus biology in general. We highlight similarities and differences with other enteroviruses and genetic divergence from own historical prototype strains of EV-D68. These include changes in capsid antigens, host cell receptor usage, and viral RNA metabolism collectively leading to increased virulence. Furthermore, we discuss the impact of EV-D68 infection on the biology of its host cells, and how these changes are hypothesized to contribute to motor neuron toxicity in AFM. We highlight areas in need of further research, including the identification of its primary receptor and an understanding of the pathogenic cascade leading to motor neuron injury in AFM. Finally, we discuss the epidemiology of the EV-D68 and potential therapeutic approaches.

The Oncolytic Virus in Cancer Diagnosis and Treatment

Cancer has always been an enormous threat to human health and survival. Surgery, radiotherapy, and chemotherapy could improve the survival of cancer patients, but most patients with advanced cancer usually have a poor survival or could not afford the high cost of chemotherapy. The emergence of oncolytic viruses provided a new strategy for us to alleviate or even cure malignant tumors. An oncolytic virus can be described as a genetically engineered or naturally existing virus that can selectively replicate in cancer cells and then kill them without damaging the healthy cells. There have been many kinds of oncolytic viruses, such as herpes simplex virus, adenovirus, and Coxsackievirus. Moreover, they have different clinical applications in cancer treatment. This review focused on the clinical application of oncolytic virus and predicted the prospect by analyzing the advantages and disadvantages of oncolytic virotherapy.

NLRP3 deficiency exacerbates enterovirus infection in mice

The role for the NOD-like receptor (NLR) P3 inflammasome in enterovirus infection remains controversial. Available data suggest that the NLRP3 inflammasome is protective against enterovirus A71 but detrimental to the host during coxsackievirus B3 (CVB3) infection. CVB3 is a common etiologic agent associated with myocarditis and pancreatitis. Previous findings on the role of NLRP3 in CVB3 were based primarily on indirect evidence. Here, we utilized NLRP3 knockout mice as well as immune and cardiac cells to investigate the direct interplay between CVB3 infection and NLRP3 activation. We demonstrated that NLRP3 knockout mice exhibited more severe disease phenotype after CVB3 infection (significantly higher virus titers), increased myocardial, and pancreatic damage, as well as markedly impaired cardiac function compared to nontransgenic control mice. We further showed that NLRP3 activity was enhanced during early stage of CVB3 infection, as evidenced by increased gene expression and/or secretion of IL-1β and caspase-1. Finally, we demonstrated that CVB3 inactivates the NLRP3 inflammasome by degrading NLRP3 and its upstream serine/threonine-protein kinase receptor-interacting protein 1/3 via the proteolytic activity of virus-encoded proteinases. Taken together, our results reveal the functional significance of NLRP3 in host antiviral immunity against CVB3 infection and the mechanisms by which CVB3 has evolved to counteract the host defense response.-Wang, C., Fung, G., Deng, H., Jagdeo, J., Mohamud, Y., Xue, Y. C., Jan, E., Hirota, J. A., Luo, H. NLRP3 deficiency exacerbates enterovirus infection in mice.

Proteasomal Protein Degradation: Adaptation of Cellular Proteolysis With Impact on Virus-and Cytokine-Mediated Damage of Heart Tissue During Myocarditis

Viral myocarditis is an inflammation of the heart muscle triggered by direct virus-induced cytolysis and immune response mechanisms with most severe consequences during early childhood. Acute and long-term manifestation of damaged heart tissue and disturbances of cardiac performance involve virus-triggered adverse activation of the immune response and both immunopathology, as well as, autoimmunity account for such immune-destructive processes. It is a matter of ongoing debate to what extent subclinical virus infection contributes to the debilitating sequela of the acute disease. In this review, we conceptualize the many functions of the proteasome in viral myocarditis and discuss the adaptation of this multi-catalytic protease complex together with its implications on the course of disease. Inhibition of proteasome function is already highly relevant as a strategy in treating various malignancies. However, cardiotoxicity and immune-related adverse effects have proven significant hurdles, representative of the target's wide-ranging functions. Thus, we further discuss the molecular details of proteasome-mediated activity of the immune response for virus-mediated inflammatory heart disease. We summarize how the spatiotemporal flexibility of the proteasome might be tackled for therapeutic purposes aiming to mitigate virus-mediated adverse activation of the immune response in the heart.

Synthesis and Biological Evaluation of Novel Indole-Derived Thioureas

A series of 2-(1H-indol-3-yl)ethylthiourea derivatives were prepared by condensation of 2-(1H-indol-3-yl)ethanamine with appropriate aryl/alkylisothiocyanates in anhydrous media. The structures of the newly synthesized compounds were confirmed by spectroscopic analysis and the molecular structures of 8 and 28 were confirmed by X-ray crystallography. All obtained compounds were tested for antimicrobial activity against Gram-positive cocci, Gram-negative rods and for antifungal activity. Microbiological evaluation was carried out over 20 standard strains and 30 hospital strains. Compound 6 showed significant inhibition against Gram-positive cocci and had inhibitory effect on the S. aureus topoisomerase IV decatenation activity and S. aureus DNA gyrase supercoiling activity. Compounds were tested for cytotoxicity and antiviral activity against a large panel of DNA and RNA viruses, including HIV-1 and other several important human pathogens. Interestingly, derivative 8 showed potent activity against HIV-1 wild type and variants bearing clinically relevant mutations. Newly synthesized tryptamine derivatives showed also a wide spectrum activity, proving to be active against positive- and negative-sense RNA viruses.

Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Background and main text

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and controversial clinical condition without having established causative factors. Increasing numbers of cases during past decade have created awareness among patients as well as healthcare professionals. Chronic viral infection as a cause of ME/CFS has long been debated. However, lack of large studies involving well-designed patient groups and validated experimental set ups have hindered our knowledge about this disease. Moreover, recent developments regarding molecular mechanism of pathogenesis of various infectious agents cast doubts over validity of several of the past studies.

Conclusions

This review aims to compile all the studies done so far to investigate various viral agents that could be associated with ME/CFS. Furthermore, we suggest strategies to better design future studies on the role of viral infections in ME/CFS.

Cellular N-myristoyltransferases play a crucial picornavirus genus-specific role in viral assembly, virion maturation, and infectivity

In nearly all picornaviruses the precursor of the smallest capsid protein VP4 undergoes co-translational N-terminal myristoylation by host cell N-myristoyltransferases (NMTs). Curtailing this modification by mutation of the myristoylation signal in poliovirus has been shown to result in severe assembly defects and very little, if any, progeny virus production. Avoiding possible pleiotropic effects of such mutations, we here used pharmacological abrogation of myristoylation with the NMT inhibitor DDD85646, a pyrazole sulfonamide originally developed against trypanosomal NMT. Infection of HeLa cells with coxsackievirus B3 in the presence of this drug decreased VP0 acylation at least 100-fold, resulting in a defect both early and late in virus morphogenesis, which diminishes the yield of viral progeny by about 90%. Virus particles still produced consisted mainly of provirions containing RNA and uncleaved VP0 and, to a substantially lesser extent, of mature virions with cleaved VP0. This indicates an important role of myristoylation in the viral maturation cleavage. By electron microscopy, these RNA-filled particles were indistinguishable from virus produced under control conditions. Nevertheless, their specific infectivity decreased by about five hundred fold. Since host cell-attachment was not markedly impaired, their defect must lie in the inability to transfer their genomic RNA into the cytosol, likely at the level of endosomal pore formation. Strikingly, neither parechoviruses nor kobuviruses are affected by DDD85646, which appears to correlate with their native capsid containing only unprocessed VP0. Individual knockout of the genes encoding the two human NMT isozymes in haploid HAP1 cells further demonstrated the pivotal role for HsNMT1, with little contribution by HsNMT2, in the virus replication cycle. Our results also indicate that inhibition of NMT can possibly be exploited for controlling the infection by a wide spectrum of picornaviruses.

Picornaviruses are important human and animal pathogens. Protective vaccines are only available against very few representatives. Furthermore, antiviral drugs have not made it to the market because of serious side effects and viral mutational escape. We here show that pharmacological inhibition of cellular myristoyltransferases severely decreased myristoylation of enteroviral structural proteins as exemplified by coxsackievirus B3, a prominent pathogen causing virus-induced acute and chronic heart disease. The drug DDD85646 substantially diminished virus yield and almost abolished the infectivity of the residual progeny virus. It is highly effective against several other picornaviruses, except those two included in our study that naturally do not process VP0. Our work provides new insight into the role of myristoylation in the life cycle of picornaviruses and identifies the responsible cellular enzyme as a promising candidate for antiviral therapy.

Osteoglycin-induced VEGF Inhibition Enhances T Lymphocytes Infiltrating in Colorectal Cancer

BACKGROUND

OGN could modify tissue inflammation and immune response via local and circulating innate immune cells, which was suggestive of a reciprocal relationship between OGN and T cell infiltration in cancer. Hence, we aim to measure the OGN expression patterns and immune cells response in colorectal cancer(CRC).

METHODS

This study enrolled three independent sets of patients from TCGA and the Fudan University Shanghai Cancer Center(FUSCC). The effect of OGN on T cell infiltration and the mechanism were examined in vitro and in vivo.

FINDINGS

Tumor OGN expression levels were positively associated with CD3, CD8, and PTPRC expressions in the training and testing sets from TCGA, respectively. In validation set from FUSCC, OGN expression level also paralleled positively with CD8+ cell density in colorectal cancer tissue (p < .001). For a unit decrease in outcome quartile categories, multivariable OR in the lowest (vs highest) OGN expression was 0.17 (95% CI 0.08-0.33). Consistently, immunofluorescence validated that OGN was preferentially expressed with CD8+ cells in both normal epithelium and cancer tissue. Xenograft tumors arising from MC38 cells with OGN-over-expression displayed a significant increase in CD8+ cells recruitment. Hence, high expression of OGN was associated with a profound longer survival (P = .009). In mechanism, elevated OGN expression inhibited the activation of the transcriptional genes HIF-1α in CRC cells, then significantly impeded the expression of VEGF. As a result of this, T cell tumor infiltration was reduced.

INTERPRETATION

OGN expression is positively associated with CD8+ cell density in colorectal cancer tissue, suggesting a possible influence of OGN expression on tumor reactive T cells in the tumor niche. FUND: No.

A novel 72-kDa leukocyte-derived osteoglycin enhances the activation of toll-like receptor 4 and exacerbates cardiac inflammation during viral myocarditis

Background

Viral myocarditis can severely damage the myocardium through excessive infiltration of immune cells. Osteoglycin (OGN) is part of the small leucine-rich repeat proteoglycan (SLRP) family. SLRP’s may affect inflammatory and fibrotic processes, but the implication of OGN in cardiac inflammation and the resulting injury upon viral myocarditis is unknown.

Methods and results

This study uncovered a previously unidentified 72-kDa variant of OGN that is predominant in cardiac human and mouse samples of viral myocarditis. Its absence in mice significantly decreased cardiac inflammation and injury in Coxsackievirus-B3-induced myocarditis. It also delayed mortality in lipopolysaccharide-induced endotoxemia going along with a reduced systemic production of pro-inflammatory cytokines. This 72-kDa OGN is expressed in the cell membrane of circulating and resident cardiac macrophages and neutrophils. Co-immunoprecipitation and OGN siRNA experiments revealed that this 72-kDa variant activates the toll-like receptor-4 (TLR4) with a concomitant increase in IL-6, TNF-α, IL-1β, and IL-12 expression. This immune cell activation by OGN occurred via MyD88 and increased phosphorylation of c-jun. Finally, the 72-kDa chondroitin sulfate is the result of O-linked glycosylation of the 32-kDa protein core of OGN. In contrast, the 34-kDa dermatan sulfate-OGN, involved in collagen cross linking, was also the result of O-linked glycosylation.

Conclusion

The current study discovered a novel 72-kDa chondroitin sulfate-OGN that is specific for innate immune cells. This variant is able to bind and activate TLR4. The absence of OGN decreases cytokine production by both circulating and cardiac leukocytes upon (systemic) LPS exposure, and reduces cardiac inflammation and injury in viral myocarditis.

Electronic supplementary material

The online version of this article (doi:10.1007/s00018-016-2423-7) contains supplementary material, which is available to authorized users.

Coxsackievirus B3 induces the formation of autophagosomes in cardiac fibroblasts both in vitro and in vivo

Coxsackievirus group B (CVB) is one of the common pathogens that cause myocarditis and cardiomyopathy. Evidence has shown that CVB replication in cardiomyocytes is responsible for the damage and loss of cardiac muscle and the dysfunction of the heart. However, it remains largely undefined how CVB would directly impact cardiac fibroblasts, the most abundant cells in human heart. In this study, cardiac fibroblasts were isolated from Balb/c mice and infected with CVB type 3 (CVB3). Increased double-membraned, autophagosome-like vesicles in the CVB3-infected cardiac fibroblasts were observed with electron microscope. Punctate distribution of LC3 and increased level of LC3-II were also detected in the infected cardiac fibroblasts. Furthermore, we observed that the expression of pro-inflammatory cytokines, IL-6 and TNF-α, was increased in the CVB3-infected cardiac fibroblasts, while suppressed autophagy by 3-MA and Atg7-siRNA inhibited cytokine expression. Consistent with the in vitro findings, increased formation of autophagosomes was observed in the cardiac fibroblasts of Balb/c mice infected with CVB3. In conclusion, our data demonstrated that cardiac fibroblasts respond to CVB3 infection with the formation of autophagosomes and the release of the pro-inflammatory cytokines. These results suggest that the autophagic response of cardiac fibroblasts may play a role in the pathogenesis of myocarditis caused by CVB3 infection.

Microarray analysis reveals altered circulating microRNA expression in mice infected with Coxsackievirus B3

Coxsackievirus B3 (CVB3) is a common causative agent in the development of inflammatory cardiomyopathy. However, whether the expression of peripheral blood microRNAs (miRNAs) is altered in this process is unknown. The present study investigated changes to miRNA expression in the peripheral blood of CVB3-infected mice. Utilizing miRNA microarray technology, differential miRNA expression was examined between normal and CVB3-infected mice. The present results suggest that specific miRNAs were differentially expressed in the peripheral blood of mice infected with CVB3, varying with infection duration. Using miRNA microarray analysis, a total of 96 and 89 differentially expressed miRNAs were identified in the peripheral blood of mice infected with CVB3 for 3 and 6 days, respectively. Quantitative polymerase chain reaction was used to validate differentially expressed miRNAs, revealing a consistency of these results with the miRNA microarray analysis results. The biological functions of the differentially expressed miRNAs were then predicted by bioinformatics analysis. The potential biological roles of differentially expressed miRNAs included hypertrophic cardiomyopathy, dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. These results may provide important insights into the mechanisms responsible for the progression of CVB3 infection.

Antimicrobial and anti-biofilm activity of thiourea derivatives incorporating a 2-aminothiazole scaffold

A series of new thiourea derivatives of 1,3-thiazole have been synthesized. All obtained compounds were tested in vitro against a number of microorganisms, including Gram-positive cocci, Gram-negative rods and Candida albicans. Compounds were also tested for their in vitro tuberculostatic activity against the Mycobacterium tuberculosis H37Rv strain, as well as two 'wild' strains isolated from tuberculosis patients. Compounds 3 and 9 showed significant inhibition against Gram-positive cocci (standard strains and hospital strain). The range of MIC values is 2-32 µg/mL. Products 3 and 9 effectively inhibited the biofilm formation of both methicillin-resistant and standard strains of S. epidermidis. The halogen atom, especially at the 3rd position of the phenyl group, is significantly important for this antimicrobial activity. Moreover, all obtained compounds resulted in cytotoxicity and antiviral activity on a large set of DNA and RNA viruses, including Human Immunodeficiency Virus type 1 (HIV-1) and other several important human pathogens. Compound 4 showed activity against HIV-1 and Coxsackievirus type B5. Seven compounds resulted in cytotoxicity against MT-4 cells (CC50<10 µM).

Recent progress in understanding coxsackievirus replication, dissemination, and pathogenesis

Coxsackieviruses (CVs) are relatively common viruses associated with a number of serious human diseases, including myocarditis and meningo-encephalitis. These viruses are considered cytolytic yet can persist for extended periods of time within certain host tissues requiring evasion from the host immune response and a greatly reduced rate of replication. A member of Picornaviridae family, CVs have been historically considered non-enveloped viruses - although recent evidence suggest that CV and other picornaviruses hijack host membranes and acquire an envelope. Acquisition of an envelope might provide distinct benefits to CV virions, such as resistance to neutralizing antibodies and efficient nonlytic viral spread. CV exhibits a unique tropism for progenitor cells in the host which may help to explain the susceptibility of the young host to infection and the establishment of chronic disease in adults. CVs have also been shown to exploit autophagy to maximize viral replication and assist in unconventional release from target cells. In this article, we review recent progress in clarifying virus replication and dissemination within the host cell, identifying determinants of tropism, and defining strategies utilized by the virus to evade the host immune response. Also, we will highlight unanswered questions and provide future perspectives regarding the potential mechanisms of CV pathogenesis.

Roles of PAR1 and PAR2 in viral myocarditis

Viral myocarditis is estimated to cause ~20% of sudden death in people under the age of 40. A variety of viruses have been found to cause myocarditis including coxsackievirus B3 (CVB3). Many studies have been performed with CVB3 because there is a mouse model of CVB3-induced myocarditis. Studies have shown that the TLR3-IFNβ pathway plays a central role in the innate immune response to CVB3 infection. Our laboratory studies the role of protease activated receptors (PAR) in different biological responses including viral infection. We examined the effect of a deficiency in either PAR1 or PAR2 on CVB3-induced myocarditis. Interestingly, we found that PAR1 knockout mice had increased cardiac injury whereas PAR2 knockout mice had decreased cardiac injury. Our studies support the notion that PARs modulate the innate immune response and can have both positive and negative effects on TLR-dependent responses.

Coxsackievirus B1 reveals strain specific differences in plasmacytoid dendritic cell mediated immunogenicity

Enterovirus infections are usually mild but can also cause severe illnesses and play a role in chronic diseases, such as cardiomyopathies and type 1 diabetes. Host response to the invading virus can markedly modulate the course of the infection, and this response varies between individuals due to the polymorphism of immune response genes. However, it is currently not known if virus strains also differ in their ability to stimulate the host immune system. Coxsackievirus B1 (CBV1) causes severe epidemics in young infants and it has recently been connected with type 1 diabetes in seroepidemiological studies. This study evaluated the ability of different field isolates of CBV1 to induce innate immune responses in PBMCs. CBV1 strains differed markedly in their capacity to induce innate immune responses. Out of the 18 tested CBV1 strains two induced exceptionally strong alpha interferon (IFN-α) response in PBMC cultures. The responding cell type was found to be the plasmacytoid dendritic cell. Such a strong innate immune response was accompanied by an up-regulation of several other immune response genes and secretion of cytokines, which modulate inflammation, and adaptive immune responses. These results suggest that enterovirus-induced immune activation depends on the virus strain. It is possible that the immunotype of the virus modulates the course of the infection and plays a role in the pathogenesis of chronic immune-mediated enterovirus diseases.

Yakammaoto inhibited human coxsackievirus B4 (CVB4)-induced airway and renal tubular injuries by preventing viral attachment, internalization, and replication

ETHNOPHARMACOLOGICAL RELEVANCE

Yakammaoto is a prescription of traditional Chinese medicine (TCM) containing nine ingredients, including Ephedra sinica, Pinellia ternate, Zingiber officinale, Tussilago farfara, Aster tataricus, Ziziphus jujube, Belamcanda chinensis, Asarum sieboldii, and Schisandra chinensis. Yakammaoto has been used against flu-like symptoms for more than two thousand years in China and Japan. Coxsackievirus B4 (CVB4) causes not only flu-like symptoms but life-threatening diseases, such as pneumonia, acute kidney injury, and so forth with severe morbidity and mortality. There is no effective therapeutic modality against CVB4 infection. It is unknown whether yakammaoto is effective against CVB4 infection. We tested the hypothesis that yakammaoto can effectively inhibit CVB4-induced plaque formation in human airway and renal tubular cell lines by preventing viral attachment, internalization, and replication.

MATERIALS AND METHODS

The fingerprint of yakammaoto was assessed by HPLC. Effects of yakammaoto on CVB4 infection were tested by plaque reduction assay, reverse transcription polymerase chain reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Yakammaoto dose-dependently inhibited CVB4-induced plaque formation in HK-2, A549, and HEp-2 cells (p<0.0001). Yakammaoto was both effective when supplemented prior to and after viral inoculation (p<0.0001) by preventing viral attachment (p<0.0001), internalization (p<0.0001), and replication (p<0.0001). Yakammaoto could decrease NGAL secretion before cytolysis to protect against viral injury.

CONCLUSIONS

Yakammaoto had antiviral activity against CVB4-induced cellular injuries in airway mucosa and renal tubular epithelia by preventing viral attachment, internalization, and replication. The current study provides a basic support of its potential use against CVB4-induced airway and concomitant renal injuries.

The role of sex differences in autophagy in the heart during coxsackievirus B3-induced myocarditis

Under normal conditions, autophagy maintains cardiomyocyte health and integrity through turnover of organelles. During stress, oxygen and nutrient deprivation, or microbial infection, autophagy prolongs cardiomyocyte survival. Sex differences in induction of cell death may to some extent explain the disparity between the sexes in many human diseases. However, sex differences in gene expression, which regulate cell death and autophagy, were so far not taken in consideration to explain the sex bias of viral myocarditis. Coxsackievirus B3 (CVB3)-induced myocarditis is a sex-biased disease, with females being substantially less susceptible than males and sex hormones largely determine this bias. CVB3 was shown to induce and subvert the autophagosome for its optimal viral RNA replication. Gene expression analysis on mouse and human, healthy and CVB3-infected, cardiac samples of both sexes, suggests sex differences in autophagy-related gene expression. This review discusses the aspects of sex bias in autophagy induction in cardiomyocytes.

Coagulation, protease-activated receptors, and viral myocarditis

The coagulation protease cascade plays an essential role in hemostasis. In addition, a clot contributes to host defense by limiting the spread of pathogens. Coagulation proteases induce intracellular signaling by cleavage of cell surface receptors called protease-activated receptors (PARs). These receptors allow cells to sense changes in the extracellular environment, such as infection. Viruses activate the coagulation cascade by inducing tissue factor expression and by disrupting the endothelium. Virus infection of the heart can cause myocarditis, cardiac remodeling, and heart failure. A recent study using a mouse model have shown that tissue factor, thrombin, and PAR-1 signaling all positively regulate the innate immune during viral myocarditis. In contrast, PAR-2 signaling was found to inhibit interferon-β expression and the innate immune response. These observations suggest that anticoagulants may impair the innate immune response to viral infection and that inhibition of PAR-2 may be a new strategy to reduce viral myocarditis.

IK induced by coxsackievirus B3 infection transiently downregulates expression of MHC class II through increasing cAMP

Major histocompatibility complex (MHC) class II expression is critical for the presentation of antigens in the immune response to viral infection. Consequently, some viruses regulate the MHC class II-mediated presentation of viral antigens as a mechanism of immune escape. In this study, we found that Coxsackievirus B3 (CVB3) infection transiently increased IK expression, which reduced the expression of MHC class II (I-A/I-E) on splenic B cells. Interestingly, CVB3-induced IK elevated cAMP, a downstream molecule of the G protein-coupled receptors, which inhibited MHC class II presentation on B cells. Transgenic mice expressing truncated IK showed lower expression of MHC class II on B cells than did wild-type mice after CVB3 infection. Taken together, these results imply that IK plays a role in downregulating MHC class II expression on B cells during CVB3 infection through the induction of cAMP.

MiR-10a* up-regulates coxsackievirus B3 biosynthesis by targeting the 3D-coding sequence

MicroRNAs (miRNAs) are small non-coding RNAs that can posttranscriptionally regulate gene expression by targeting messenger RNAs. During miRNA biogenesis, the star strand (miRNA*) is generally degraded to a low level in the cells. However, certain miRNA* express abundantly and can be recruited into the silencing complex to regulate gene expression. Most miRNAs function as suppressive regulators on gene expression. Group B coxsackieviruses (CVB) are the major pathogens of human viral myocarditis and dilated cardiomyopathy. CVB genome is a positive-sense, single-stranded RNA. Our previous study shows that miR-342-5p can suppress CVB biogenesis by targeting its 2C-coding sequence. In this study, we found that the miR-10a duplex could significantly up-regulate the biosynthesis of CVB type 3 (CVB3). Further study showed that it was the miR-10a star strand (miR-10a*) that augmented CVB3 biosynthesis. Site-directed mutagenesis showed that the miR-10a* target was located in the nt6818–nt6941 sequence of the viral 3D-coding region. MiR-10a* was detectable in the cardiac tissues of suckling Balb/c mice, suggesting that miR-10a* may impact CVB3 replication during its cardiac infection. Taken together, these data for the first time show that miRNA* can positively modulate gene expression. MiR-10a* might be involved in the CVB3 cardiac pathogenesis.

Caspase-8 and FLIP regulate RIG-I/MDA5-induced innate immune host responses to picornaviruses

Picornaviruses are small, nonenveloped, positive-stranded RNA viruses, which cause a wide range of animal and human diseases, based on their distinct tissue and cell type tropisms. Myocarditis, poliomyelitis, hepatitis and the common cold are the most significant human illnesses caused by picornaviruses. The host response to picornaviruses is complex, and the damage to tissues occurs not only from direct viral replication within infected cells. Picornaviruses exhibit an exceptional ability to evade the early innate immune response, resulting in chronic infection and autoimmunity. This review discusses the detailed aspects of the early innate host response to picornaviruses infection mediated by RIG-I-like helicases, their adaptor, mitochondrial ant iviral signaling protein, innate immune-induced apoptosis, and the role of caspase-8 and its regulatory paralog, FLIP, in these processes.

Manipulating intestinal immunity and microflora: an alternative solution to viral myocarditis?

Viral myocarditis (VMC) is an important cause of heart failure and dilated cardiomyopathy with no effective clinical diagnosis and treatment, and has been commonly associated with Coxsackievirus B3 (CVB3) infection. Current evidence from CVB3 myocarditis in mice indicates that acute myocarditis is mainly mediated by the host immune responses, including Th1, Th17 and type I macrophages. Recently, innate immunity triggered by TLR3, TLR4, TLR8 and MDA5 has also been demonstrated to participate in the induction of inflammatory cytokines in response to CVB3. Apart from the heart tissue, the intestine, which is the assumed initial infection and important replication site for CVB3, needs to be investigated, where induction of innate immunity and interactions with microflora may shape the immune response involved in the pathogenesis of VMC. This review presents recent advances in research into innate and adaptive immunity to CVB3, and provides insights into developing new strategies for the future treatment for VMC.

Innate and adaptive immune responses against picornaviruses and their counteractions: An overview

Picornaviruses, small positive-stranded RNA viruses, cause a wide range of diseases which is based on their differential tissue and cell type tropisms. This diversity is reflected by the immune responses, both innate and adaptive, induced after infection, and the subsequent interactions of the viruses with the immune system. The defense mechanisms of the host and the countermeasures of the virus significantly contribute to the pathogenesis of the infections. Important human pathogens are poliovirus, coxsackievirus, human rhinovirus and hepatitis A virus. These viruses are the best-studied members of the family, and in this review we want to present the major aspects of the reciprocal effects between the immune system and these viruses.

Immunology in the clinic review series; focus on type 1 diabetes and viruses: the enterovirus link to type 1 diabetes: critical review of human studies

The hypothesis that under some circumstances enteroviral infections can lead to type 1 diabetes (T1D) was proposed several decades ago, based initially on evidence from animal studies and sero-epidemiology. Subsequently, enterovirus RNA has been detected more frequently in serum of patients than in control subjects, but such studies are susceptible to selection bias and reverse causality. Here, we review critically recent evidence from human studies, focusing on longitudinal studies with potential to demonstrate temporal association. Among seven longitudinal birth cohort studies, the evidence that enterovirus infections predict islet autoimmunity is quite inconsistent in our interpretation, due partially, perhaps, to heterogeneity in study design and a limited number of subjects studied. An association between enterovirus and rapid progression from autoimmunity to T1D was reported by one longitudinal study, but although consistent with evidence from animal models, this novel observation awaits replication. It is possible that a potential association with initiation and/or progression of islet autoimmunity can be ascribed to a subgroup of the many enterovirus serotypes, but this has still not been investigated properly. There is a need for larger studies with frequent sample intervals and collection of specimens of sufficient quality and quantity for detailed characterization of enterovirus. More research into the molecular epidemiology of enteroviruses and enterovirus immunity in human populations is also warranted. Ultimately, this knowledge may be used to devise strategies to reduce the risk of T1D in humans.

Wild-type coxsackievirus infection dramatically alters the abundance, heterogeneity, and immunostimulatory capacity of conventional dendritic cells in vivo

In vitro studies have shown that enteroviruses employ strategies that may impair the ability of DCs to trigger T cell immunity, but it is unclear how these viruses affect DCs in vivo. Here, we evaluate the effects of wild-type (wt) coxsackievirus B3 on DCs in vitro and in a murine model in vivo. Although CVB3 does not productively infect the vast majority of DCs, virus infection profoundly reduces splenic conventional DC numbers and diminishes their capacity to prime naïve CD8(+) T cells in vitro. In contrast to recombinant CVB3, highly pathogenic wt virus infection significantly diminishes the host's capacity to mount T cell responses, which is temporally associated with the loss of CD8α(+) DCs. Our findings demonstrate that enterovirus infection substantially alters the number, heterogeneity, and stimulatory capacity of DCs in vivo, and these dramatic immunomodulatory effects may weaken the host's capacity to mount antiviral T cell responses.

Polymorphisms in the innate immune IFIH1 gene, frequency of enterovirus in monthly fecal samples during infancy, and islet autoimmunity

Interferon induced with helicase C domain 1 (IFIH1) senses and initiates antiviral activity against enteroviruses. Genetic variants of IFIH1, one common and four rare SNPs have been associated with lower risk for type 1 diabetes. Our aim was to test whether these type 1 diabetes-associated IFIH1 polymorphisms are associated with the occurrence of enterovirus infection in the gut of healthy children, or influence the lack of association between gut enterovirus infection and islet autoimmunity.

After testing of 46,939 Norwegian newborns, 421 children carrying the high risk genotype for type 1 diabetes (HLA-DR4-DQ8/DR3-DQ2) as well as 375 children without this genotype were included for monthly fecal collections from 3 to 35 months of age, and genotyped for the IFIH1 polymorphisms. A total of 7,793 fecal samples were tested for presence of enterovirus RNA using real time reverse transcriptase PCR.

We found no association with frequency of enterovirus in the gut for the common IFIH1 polymorphism rs1990760, or either of the rare variants of rs35744605, rs35667974, rs35337543, while the enterovirus prevalence marginally differed in samples from the 8 carriers of a rare allele of rs35732034 (26.1%, 18/69 samples) as compared to wild-type homozygotes (12.4%, 955/7724 samples); odds ratio 2.5, p = 0.06. The association was stronger when infections were restricted to those with high viral loads (odds ratio 3.3, 95% CI 1.3–8.4, p = 0.01). The lack of association between enterovirus frequency and islet autoimmunity reported in our previous study was not materially influenced by the IFIH1 SNPs.

We conclude that the type 1 diabetes-associated IFIH1 polymorphisms have no, or only minor influence on the occurrence, quantity or duration of enterovirus infection in the gut. Its effect on the risk of diabetes is likely to lie elsewhere in the pathogenic process than in the modification of gut infection.