Suppression of proinflammatory cytokines and induction of IL-10 in human monocytes after coxsackievirus B3 infection

Antiviral and immunoregulatory effects of curcumin on coxsackievirus B3-infected hepatitis

Fulminant hepatitis is a life-threatening complication of coxsackievirus B (CVB) 3 infections. The condition may deteriorate to disseminated intravascular coagulopathy with markedly increased liver enzymes, inflammatory cytokines, and chemokines, which significantly induce local and systemic inflammation. Curcumin exhibits anti-inflammatory and antiviral characteristics in inflammatory and infectious diseases. Here we determined effects of curcumin on viral replications, cytokine and chemokine expressions, and liver damage in CVB3-infected Huh-7 cells. The mouse-adapted CVB3 strain was used to investigate the antiviral and anti-inflammatory effects of curcumin on CVB3-induced hepatitis in a mouse model. In vitro studies showed that curcumin reduced viral protein and titer levels and increased cell viability. Curcumin enhanced the heme oxygenase-1 (HO-1) protein level and decreased the levels of cleaved caspase-3 protein and mRNA of gene encoding C-X-C motif chemokine 10 in infected cells. In vivo studies showed that curcumin improved the survival rate and clinical scores in mice and reduced the viral titer in the liver during CVB3 infection. Moreover, the HO-1 levels were increased, and the cleaved caspase-3 levels were diminished in the CVB3-infected liver. Curcumin reduced the levels of interferon (IFN)-γ and monokine induced by IFN-γ in liver and levels of interleukin (IL)-8 in serum, but increased levels of regulated activation, normal T cell expression in liver and levels of IL-10 in serum of CVB3-infected mice. In summary, curcumin presents antiviral and anti-inflammation efficacies in CVB3 infection in vitro and in vivo; these results provide potential evidence on the feasibility of curcumin for clinical treatment.

Type B coxsackieviruses and central nervous system disorders: critical review of reported associations

Type B coxsackieviruses (CV-B) frequently infect the central nervous system (CNS) causing neurological diseases notably meningitis and encephalitis. These infections occur principally among newborns and children. Epidemiological studies of patients with nervous system disorders demonstrate the presence of infectious virus, its components, or anti-CV-B antibodies. Some experimental studies conducted in vitro and in vivo support the potential association between CV-B and idiopathic neurodegenerative diseases such as amyotrophic lateral sclerosis and psychiatric illness such as schizophrenia. However, mechanisms explaining how CV-B infections may contribute to the genesis of CNS disorders remain unclear. The proposed mechanisms focus on the immune response following the viral infection as a contributor to pathogenesis. This review describes these epidemiological and experimental studies, the modes of transmission of CV-B with an emphasis on congenital transmission, the routes used by CV-B to reach the brain parenchyma, and plausible mechanisms by which CV-B may induce CNS diseases, with a focus on potential immunopathogenesis.

Myocarditis and inflammatory cardiomyopathy: current evidence and future directions

Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.

Enteroviral Pathogenesis of Type 1 Diabetes: The Role of Natural Killer Cells

Enteroviruses, especially group B coxsackieviruses (CV-B), have been associated with the development of chronic diseases such as type 1 diabetes (T1D). The pathological mechanisms that trigger virus-induced autoimmunity against islet antigens in T1D are not fully elucidated. Animal and human studies suggest that NK cells response to CV-B infection play a crucial role in the enteroviral pathogenesis of T1D. Indeed, CV-B-infected cells can escape from cytotoxic T cells recognition and destruction by inhibition of cell surface expression of HLA class I antigen through non-structural viral proteins, but they can nevertheless be killed by NK cells. Cytolytic activity of NK cells towards pancreatic beta cells persistently-infected with CV-B has been reported and defective viral clearance by NK cells of patients with T1D has been suggested as a mechanism leading to persistence of CV-B and triggering autoimmunity reported in these patients. The knowledge about host antiviral defense against CV-B infection is not only crucial to understand the susceptibility to virus-induced T1D but could also contribute to the design of new preventive or therapeutic approaches for individuals at risk for T1D or newly diagnosed patients.

Pancreatic beta cells persistently infected with coxsackievirus B4 are targets of NK cell-mediated cytolytic activity

It has been suggested that the persistence of coxsackieviruses-B (CV-B) in pancreatic beta cells plays a role in the pathogenesis of type 1 diabetes (T1D). Yet, immunological effectors, especially natural killer (NK) cells, are supposed to clear virus-infected cells. Therefore, an evaluation of the response of NK cells to pancreatic beta cells persistently infected with CV-B4 was conducted. A persistent CV-B4 infection was established in 1.1B4 pancreatic beta cells. Infectious particles were found in supernatants throughout the culture period. The proportion of cells containing viral protein VP1 was low (< 5%), although a large proportion of cells harbored viral RNA (around 50%), whilst cell viability was preserved. HLA class I cell surface expression was downregulated in persistently infected cultures, but HLA class I mRNA levels were unchanged in comparison with mock-infected cells. The cytolytic activities of IL-2-activated non-adherent peripheral blood mononuclear cells (PBMCs) and of NK cells were higher towards persistently infected cells than towards mock-infected cells, as assessed by an LDH release assay. Impaired cytolytic activity of IL-2-activated non-adherent PBMCs from patients with T1D towards infected beta cells was observed. In conclusion, pancreatic beta cells persistently infected with CV-B4 can be lysed by NK cells, implying that impaired cytolytic activity of these effector cells may play a role in the persistence of CV-B in the host and thus in the viral pathogenesis of T1D.

Genetic and Environmental Interaction in Type 1 Diabetes: a Relationship Between Genetic Risk Alleles and Molecular Traits of Enterovirus Infection?

PURPOSE OF REVIEW

We provide an overview of the current knowledge regarding the natural history of human type 1 diabetes (T1D) and the documented associations between virus infections (in particular the enteroviruses) and disease development. We review studies that examine whether T1D-specific risk alleles in genes involved in the function of the immune system can alter susceptibility to virus infections or affect the magnitude of the host antiviral response. We also highlight where the major gaps in our knowledge exist and consider possible implications that new insights gained from the discussed gene-environment interaction studies may bring.

RECENT FINDINGS

A commonality between several of the studied T1D risk variants studied is their role in modulating the host immune response to viral infection. Generally, little support exists indicating that the risk variants increase susceptibility to infection and moreover, they usually appear to predispose the immune system towards a hyper-reactive state, decrease the risk of infection, and/or favor the establishment of viral persistence. In conclusion, although the current number of studies is limited, this type of research can provide important insights into the mechanisms that are central to disease pathogenesis and further describe how genetic and environmental factors jointly influence the risk of T1D development. The latter may provide genetic markers that could be used for patient stratification and for the selection of method(s) for disease prevention.

Diagnostic and prognostic biomarkers in acute myocarditis. Interleukin-10

Acute myocarditis is a major inflammatory heart disease with a variety of clinical courses from the acute to chronic phases represented by unexpected circulatory deterioration during hospitalization and progression to dilated cardiomyopathy. Predicting these disease courses is important for patient management. However, biomarkers have not been fully investigated. In addition, clinical profiles including symptoms, serological data, and electrocardiographic findings in acute myocarditis often mimic more common disorders such as coronary artery disease, which have reduced the diagnostic accuracy of acute myocarditis. These issues hamper the development of safer and earlier therapeutic interventions specific for acute myocarditis. Against this background, identifying simple prognostic and diagnostic biomarkers would contribute dramatically to the improvement in outcomes. Interleukin-10 may be a strong candidate for an excellent biomarker.

Highly pathogenic influenza viruses inhibit inflammatory response in monocytes via activation of rar-related orphan receptor RORα

Infections with highly pathogenic avian influenza viruses (HPAIV) in humans lead to systemic disease associated with cytokine storm and multiorgan failure. In this study we aimed to identify the role of monocytes for the host response to HPAIV infection. Using genome-wide microarray analysis, we surprisingly demonstrate a reduced immune response of human monocytes to HPAIV H5N1 compared to human influenza A viruses. In bioinformatic analyses we could reveal a potential role of the Rar-related orphan receptor alpha (RORα) for the gene expression pattern induced by H5N1. RORα is known as an inhibitor of NF-κB signaling. We provide evidence that in monocytes RORα is activated by H5N1, resulting in inhibited NF-κB signaling. Using murine Hoxb8-immortalized RORα⁻/⁻, monocytes rescued NF-κB signaling upon H5N1 infection, confirming the biological relevance of RORα as an H5N1-induced mediator of monocytic immunosuppression. In summary, our study reveals a novel RORα-dependent escape mechanism by which H5N1 prevents an effective inflammatory response of monocytes blocking NF-κB-dependent gene expression.

Coxsackievirus B3 infection leads to the generation of cardiac myosin heavy chain-α-reactive CD4 T cells in A/J mice

Enteroviruses like coxsackievirus B3 (CVB3) are common suspects in myocarditis/dilated cardiomyopathy patients. Autoimmunity has been proposed as an underlying mechanism, but direct evidence of its role is lacking. To delineate autoimmune response in CVB3 myocarditis, we used IA(k) dextramers for cardiac myosin heavy chain (Myhc)-α 334-352. We have demonstrated that myocarditis-susceptible A/J mice infected with CVB3 generate Myhc-α-reactive CD4 T cells and such a repertoire was absent in naïve mice as measured by proliferative response to Myhc-α 334-352 and IA(k) dextramer staining. We also detected Myhc-α 334-352 dextramer(+) cells in the hearts of CVB3-infected mice. The autoreactive T cell repertoire derived from infected mice contained a high frequency of interleukin-17-producing cells capable of inducing myocarditis in naïve recipients. The data suggest that CVB3, a bona fide pathogen of cardiovascular system that primarily infects the heart can lead to the secondary generation of autoreactive T cells and contribute to cardiac pathology.

Role of enterovirus infections in IgE sensitization

Among other infectious agents, enteroviruses have been associated with protection against allergic diseases. The aim of the present study was to confirm these findings using a highly sensitive and specific neutralization antibody assay and to investigate whether the protective effect is related to certain enterovirus serotypes. Antibodies against 12 enterovirus serotypes were measured in 60 children who were positive for allergen-specific IgE and in 190 control children. Echoviruses seemed to be more protective than coxsackie-B-viruses and echovirus 11 had the strongest independent protective effect (P = 0.001; OR = 0.35, 95% CI: 0.18-0.67). The results support previous observations suggesting that infections by certain enterovirus types are associated with protection against IgE sensitization.

In VitroActivity ofParis polyphyllaSmith Against Enterovirus 71 and Coxsackievirus B3 and Its Immune Modulation

Enterovirus 71 (EV71) and coxsackievirus B3 (CVB3) have resulted in severe pathogenesis caused by the host's immune response, including the cytokine cascade. Paris polyphylla Smith is a folk medicinal plant in Asia traditionally prescribed for the reduction of pain and elimination of poisoning. In this study, we investigated the anti-EV71 and CVB3 activity of P. polyphylla Smith as well as its immune modulation. The IC50for the P. polyphylla Smith 95% ethanol extract against EV71 and CVB3 were 12.5–23% and 99–156% of that of ribavirin, a positive control. Prevention of viral infection, viral inactivation, and anti-viral replication effects against both EV71 and CVB3 were demonstrated by the extract, the anti-viral replication effect being dominant. The extract significantly increased IL-6 production in both EV71- and CVB3-infected cells. A high correlation was possibly demonstrated between the high amounts of IL-6 induction in the EV71 and CVB3-infected cells and the anti-viral replication activity of the extract. In conclusion, good anti-EV71 and CVB3 activity was observed in the P. polyphylla Smith 95% ethanol extract. The high amounts of IL-6 induction in the virus-infected cells played a key role in the anti-viral activity of the extract.

Lack of IL-6 during coxsackievirus infection heightens the early immune response resulting in increased severity of chronic autoimmune myocarditis

BACKGROUND

Chronic myocarditis is often initiated by viral infection, the most common of which is coxsackievirus infection. The precise mechanism by which viral infection leads to chronic autoimmune pathology is poorly understood, however it is clear that the early immune response plays a critical role. Previous results have shown that the inflammatory cytokine interleukin (IL)-6 is integral to the development of experimental-induced autoimmune myocarditis. However, the function of IL-6 during viral-mediated autoimmunity has yet to be elucidated.

METHODS AND RESULTS

To address the requirement of IL-6 during disease induction, IL-6 deficient mice were infected with coxsackievirus B3 (CB3). Following infection, mice lacking IL-6 developed increased chronic autoimmune disease pathology compared to wild type controls without a corresponding change in the level of viral replication in the heart. This increase in disease severity was accompanied by elevated levels of TNF-alpha, MCP-1, IL-10, activated T cells and cardiac infiltrating macrophage/monocytes. Injection of recombinant IL-6 early following infection in the IL-6 deficient mice was sufficient to lower the serum cytokines TNF-alpha and IL-10 as well as the serum chemokines MCP-1, MIP-1beta, RANTES and MIG with a corresponding decrease in the chronic disease pathology strongly suggests an important regulatory role for IL-6 during the early response.

CONCLUSIONS

While IL-6 plays a pathogenic role in experimental-induced autoimmune disease, its function following viral-induced autoimmunity is not reprised. By regulating the early immune response and thereby controlling the severity of chronic disease, IL-6 directs the outcome of chronic autoimmune myocarditis.

Recent enterovirus infection in type 1 diabetes: evidence with a novel IgM method

Enterovirus (EV) infection has been associated with Type 1 (T1D) diabetes and on a few occasions virus could be isolated at onset of the disease. Using two such isolates as antigens in a quantitative PCR enhanced immunoassay (T1D-EV-QPIA) we have measured IgM antibodies against such potentially diabetogenic viruses in serum from 33 newly diagnosed T1D children, 24 siblings, and 27 healthy children. Sera were also analysed with regard to autoantibodies against GAD65, the cytokine TNF-alpha and the chemokine IP-10. EV-RNA detection was performed on peripheral blood mononuclear cells (PBMC). IgM antibodies against this "new" EV antigen were more frequent in serum from T1D children than in serum from siblings and/or controls (P < 0.001). EV-RNA was detected more frequently in PBMC from T1D children than in healthy control children (P < 0.001) and also compared to the siblings (P < 0.003). The cytokine TNF-alpha was less frequently detected in serum from the T1D children compared with serum from siblings and/controls (P < 0.001). A positive correlation was found between the results obtained with the T1D-EV-QPIA and the EV-PCR (P < 0.001). These findings are in line with earlier findings of an increased frequency of enteroviral infections in newly diagnosed T1D patients. In addition, we found that T1D children at onset of the disease had lower frequencies of the chemokine TNF-alpha in their serum than age- and sex-matched controls had, suggesting an impaired immune response.

Coxsackie B4 virus infection of beta cells and natural killer cell insulitis in recent-onset type 1 diabetic patients

Type 1 diabetes is characterized by T cell-mediated autoimmune destruction of pancreatic beta cells. Several studies have suggested an association between Coxsackie enterovirus seroconversion and onset of disease. However, a direct link between beta cell viral infection and islet inflammation has not been established. We analyzed pancreatic tissue from six type 1 diabetic and 26 control organ donors. Immunohistochemical, electron microscopy, whole-genome ex vivo nucleotide sequencing, cell culture, and immunological studies demonstrated Coxsackie B4 enterovirus in specimens from three of the six diabetic patients. Infection was specific of beta cells, which showed nondestructive islet inflammation mediated mainly by natural killer cells. Islets from enterovirus-positive samples displayed reduced insulin secretion in response to glucose and other secretagogues. In addition, virus extracted from positive islets was able to infect beta cells from human islets of nondiabetic donors, causing viral inclusions and signs of pyknosis. None of the control organ donors showed signs of viral infection. These studies provide direct evidence that enterovirus can infect beta cells in patients with type 1 diabetes and that infection is associated with inflammation and functional impairment.

Echovirus infection causes rapid loss-of-function and cell death in human dendritic cells

Coxsackie B viruses (CVB) and Echoviruses (EV) form a single species; Human enterovirus B (HeV-B), within the genus Enterovirus. Although HeV-B infections are usually mild or asymptomatic, they can cause serious acute illnesses. In addition, HeV-B infections have been associated with chronic immune disorders, such as type 1 diabetes mellitus and chronic myocarditis/dilated cardiomyopathy. It has therefore been suggested that these viruses may trigger an autoimmune process. Here, we demonstrate that human dendritic cells (DCs), which play an essential role in orchestration of the immune response, are productively infected by EV, but not CVB strains, in vitro. Infection does not result in DC activation or the induction of antiviral immune responses. Instead, EV infection rapidly impedes Toll-like receptor-mediated production of cytokines and upregulation of maturation markers, and ultimately causes loss of DC viability. These results describe for the first time the effect of EV on the function and viability of human DCs and suggest that infection of DCs in vivo can impede regulation of immune responses.

Sustained nitric oxide synthesis contributes to immunopathology in ongoing myocarditis attributable to interleukin-10 disorders

Ongoing coxsackievirus B3 (CVB3) myocarditis is characterized by persistence of viral RNA and chronic inflammation primarily mediated by macrophages and T cells. Activated macrophages produce anti-viral effector molecules comprising reactive nitrogen intermediates; however, reactive nitrogen intermediates also contribute to host tissue damage. Controlled activation of macrophages depends on interferon (IFN)-gamma and interleukin (IL)-10. To evaluate mechanisms involved in CVB3-induced pathogenesis of myocarditis, we determined the relationship of inducible nitric-oxide synthase (iNOS) mRNA expression with IFN-gamma and IL-10 secretion during CVB3 infection in different mouse strains. We found in susceptible A.BY/SnJ mice that develop ongoing myocarditis, a low and delayed IFN-gamma secretion and highly diminished IL-10 production compared with resistant C57BL/6 mice. Consequently, iNOS mRNA synthesis was delayed but clearly prolonged in susceptible mice. IL-10 gene-deficient mice confirmed the regulatory role of IL-10 in the outcome of CVB3 myocarditis. These mice did not establish a persistent cardiac infection and revealed IFN-gamma secretion kinetics similar to resistant mice but showed a slightly elongated cardiac iNOS mRNA expression resulting in extended myocarditis. We conclude that coordinated secretion of IFN-gamma and IL-10 is crucial for the effective resolution of CVB3 myocarditis. Moreover, lack of regulatory IL-10 leads to uncontrolled iNOS mRNA production, thus contributing to ongoing myocardial injury.

Serum levels of interleukin-10 on admission as a prognostic predictor of human fulminant myocarditis

OBJECTIVES

We assessed the significance of serum cytokine levels in patients with fulminant myocarditis.

BACKGROUND

Although many investigations have demonstrated the crucial role of cytokines in the development of myocarditis, it remains uncertain whether serum levels of cytokines enable one to predict the prognosis of human myocarditis, especially concerning cardiogenic shock (CS) requiring a mechanical cardiopulmonary support system (MCSS).

METHODS

We studied 22 consecutive patients with fulminant myocarditis and compared them with 15 patients with acute myocardial infarction (AMI) requiring MCSS. The patients with myocarditis were classified into three groups: eight patients with CS requiring MCSS on admission (group 1); six patients who unexpectedly lapsed into CS requiring MCSS more than two days after catecholamine had been initiated (group 2); and eight patients without MCSS (group 3). Furthermore, 14 patients with myocarditis requiring MCSS were divided into a fatal group (n = 5) and a survival group (n = 9). Biochemical markers, including serum cytokine levels and hemodynamic variables on admission, were analyzed.

RESULTS

Serum levels of interleukin (IL)-10 and tumor necrosis factor-alpha, but not other cytokines, were significantly higher in myocarditis than in AMI. Only serum levels of IL-10 were significantly higher in group 1 and 2 than in group 3 (49.1 +/- 37.5/20.7 +/- 17.6 pg/ml vs. 2.4 +/- 1.1 pg/ml; p = 0.0008/0.0012). Serum IL-10 levels were also significantly higher in the fatal group than in the survival group with myocarditis (74.0 +/- 27.0 pg/ml vs. 16.4 +/- 8.8 pg/ml; p = 0.003).

CONCLUSIONS

Serum IL-10 levels on admission enabled one to predict subsequent CS requiring MCSS and mortality of fulminant myocarditis patients.

A formidable challenge: the diagnosis and treatment of viral myocarditis in children

It is generally well accepted that one third of patients with viral myocarditis experience a complete recovery of normal cardiac function, one third improve clinically but show residual cardiac dysfunction, and one third experience chronic heart failure and die or require heart transplantation. It is hoped that a better understanding of the underlying cause and pathogenesis of this disease will increase the number of patients who experience a complete recovery. New advances in both the diagnosis and treatment of viral myocarditis continue to enter clinical practice at a rapid pace, and it is likely that a genomic approach to the diagnostic evaluation and treatment of this disease will become possible in the near future. Viral myocarditis, however, will remain a significant diagnosticand therapeutic challenge to both physicians and scientists alike.

Suppression of lipopolysaccharide-induced antiviral transcription factor (STAT-1 and NF-kappa B) complexes by antibody-dependent enhancement of macrophage infection by Ross River virus

Subneutralizing concentrations of antibody may enhance virus infection by bringing the virus-antibody complex into contact with the cell surface Fc receptors; this interaction facilitates entry of virus into the cell and is referred to as antibody-dependent enhancement (ADE) of infection. Northern analysis of macrophage RNA demonstrated that ADE infection by the indigenous Australian alphavirus Ross River (RRV-ADE) ablated or diminished message for tumor necrosis factor alpha (TNF-alpha), nitric-oxide synthase 2 (NOS2), and IFN regulatory factor 1 (IRF-1), as well as for IFN-inducible protein 10 (IP-10) and IFN-beta; the transcription of a control gene was unaffected. Additionally, electrophoretic mobility-shift assay (EMSA) studies showed that transcription factor IFN-alpha-activated factor (AAF), IFN-stimulated gene factor 3 (ISGF3), and nuclear factor-kappaB (NF-kappaB) complex formation in macrophage nuclear extracts were specifically suppressed post-RRV-ADE infection, emphasizing the capacity for ADE infections to compromise antiviral responses at the transcriptional level. The suppression of antiviral transcription factor complexes was shown to depend on replicating virus and was not simply a result of general antibody-Fc-receptor interaction. Although only a minority of cells ( approximately 15%) were shown to be positive for RRV by immunostaining techniques post ADE, molecular (RT-PCR) analysis showed that unstained cells carried RRV-RNA, indicating a higher level of viral infectivity than previously suspected. Electron microscopy studies confirmed this observation. Furthermore, levels of cellular IL-10 protein were dramatically elevated in RRV-ADE cultures. This evidence demonstrates that RRV can potently disrupt the activation of specific antiviral pathways via ADE infection pathways, and may suggest a significant mechanism in the infection and pathogenesis of other ADE viruses.