Coxsackie B3 myocarditis in 4 cases of suspected sudden infant death syndrome: diagnosis by immunohistochemical and molecular-pathologic investigations

[Lethal lymphocytic myocarditis-an underestimated diagnosis in infancy and childhood?]

In the past, histological diagnosis of (post-)viral myocarditis was based on the so-called Dallas criteria, which have been criticized because of high interobserver variability and sampling error. Immunohistochemical qualification and quantification of interstitial intramyocardial leucocytes was established and standard values concerning adults were published. Fatal casualties due to a viral myocarditis are rare as far as babies and children are concerned (sudden unexpected death in infancy; SUDI). Cases of sudden unexpected death in the first year of life are frequently regarded as sudden infant death syndrome (SIDS). To diagnose myocarditis when there are only single focal lymphocytic infiltrates in the myocardium, the number of samples taken by autopsy is relevant. But even in babies, immunohistochemical qualification and quantification of interstitial lymphocytes and macrophages can lead to standard values allowing diagnosis of myocarditis. Depending on the course of a viral infection, molecular pathological detection of viral genome in the myocardium is possible to support the diagnosis. Using the mentioned methods gradually, there are more cases of suspected SIDS, which are in fact cases of virus-induced myocarditis as cause of death. Primary enteroviruses (coxsackie viruses) and adenoviruses were found but also Epstein-Barr virus and PVB-19.

Immunohistochemical diagnosis of human infectious diseases: a review

BACKGROUND

Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.

MAIN BODY

Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined. A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.

CONCLUSION

IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.

Myocarditis Presenting as Sudden Death in Infants and Children: A Single Centre Analysis by ESGFOR Study Group

BACKGROUND

Acute myocarditis is an inflammatory disease of the heart mostly diagnosed in young people, which can present as sudden death. The etiology includes infectious agents (mostly viruses), systemic diseases and toxins. We aim to characterize infants and children with myocarditis at post-mortem presenting as sudden deaths.

METHODS

Retrospective evaluation of 813 post-mortems in infants and children dying suddenly and unexpectedly between 2009-2019. Data retrieved included histological features, microbiology and clinical history.

RESULTS

23 of 813 post-mortems reviewed corresponded to acute myocarditis and 1 to dilated cardiomyopathy related to remote Parvovirus infection. PCR identified enterovirus (7), parvovirus (7 cases, 2 also with HHV6 and 1 case with EVB), Influenza A (1), Parainfluenza type 3 (1). Two cases corresponded to hypersensitivity myocarditis, 1 was Group A Streptococcus and 5 idiopathic myocarditis. Enterovirus was frequent in infants (7/10), and in newborns was associated with meningoencephalitis or congenital myocarditis. More than 50% were less than 2 years of age and all remained clinically unsuspected.

CONCLUSION

Myocarditis represents almost 3% of all sudden pediatric deaths. Enterovirus and parvovirus were the most common viruses. This retrospective analysis showed that patients experienced viral symptoms but remained unsuspected, highlighting the need for more clinical awareness of myocarditis.

The use of extracorporeal membrane oxygenation in children with acute fulminant myocarditis

Acute fulminant myocarditis (AFM) occurs as an inflammatory response to an initial myocardial insult. Its rapid and deadly progression calls for prompt diagnosis with aggressive treatment measures. The demonstration of its excellent recovery potential has led to increasing use of mechanical circulatory support, especially extracorporeal membrane oxygenation (ECMO). Arrhythmias, organ failure, elevated cardiac biomarkers, and decreased ventricular function at presentation predict requirement for ECMO. In these patients, ECMO should be considered earlier as the clinical course of AFM can be unpredictable and can lead to rapid haemodynamic collapse. Key uncertainties that clinicians face when managing children with AFM such as timing of initiation of ECMO and left ventricular decompression need further investigation.

Factors Associated With In-hospital Mortality of Children With Acute Fulminant Myocarditis on Extracorporeal Membrane Oxygenation

Aim: To analyze the factors associated with in-hospital mortality of children with acute fulminant myocarditis on venoarterial extracorporeal membrane oxygenation (VA-ECMO). Methods: This was a retrospective cohort study using chart reviews of patients diagnosed with acute fulminant myocarditis at the pediatric intensive care unit of two tertiary medical centers between January 1, 2005 and December 31, 2017. The inclusion criteria for this study were: (1) age from 1 month to 18 years; (2) diagnosed with acute myocarditis; (3) cardiogenic shock and need vasoactive-inotropic score ≥20 within 48 h after the use of vasoactive-inotropic agents; and (4) the need for ECMO placement. Results: Thirty-three children with acute fulminant myocarditis who needed ECMO were included. Clinical parameters were retrospectively reviewed. The overall survival rate was 69.6%. Higher levels of pre-ECMO troponin-I and pre-ECMO lactate, and lower post-ECMO left ventricular ejection fraction (LVEF) were significantly associated with in-hospital mortality in univariate analysis. Only higher pre-ECMO lactate and lower post-ECMO LVEF remained as predictors for in-hospital mortality in multivariate analysis. The areas under the curve of pre-ECMO lactate and post-ECMO LVEF in predicting survival were 0.848 (95% CI, 0.697-0.999, p = 0.002) and 0.824 (95% CI, 0.704-0.996, p = 0.01), respectively. A pre-ECMO lactate level of 79.8 mg/dL and post-ECMO LVEF of 39% were appropriate cutoff points to predict mortality. Conclusion: Pre-ECMO lactate level was associated with mortality in children with acute fulminant myocarditis, with an optimal cutoff value of 79.8 mg/dL. After VA-ECMO implantation, post-ECMO LVEF was associated with mortality, with an optimal cutoff value of 39%. The use of LVADs or urgent heart transplantation should be considered if the post-ECMO LVEF does not improve.

Differential expression profiles and functional analysis of circular RNAs in children with fulminant myocarditis

Aim: To assess differential expression profiles of circular RNAs (circRNAs) and explore their possible functions in children with fulminant myocarditis. Materials & methods: circRNA microarray experiments were carried out for determining differential expression profiles of circRNAs in three children with fulminant myocarditis and three healthy volunteers. Functional analysis and circRNA-miRNA-mRNA interaction network building were conducted to study biological functions. Results: This work identified 2281 upregulated and 892 downregulated circRNAs. Further assessment confirmed hsa_circ_0071542 upregulation (2.5-fold) in fulminant myocarditis. Functional analysis demonstrated the differentially expressed circRNAs mainly contributed to inflammation and immunity. Conclusion: circRNAs might have substantial roles in pediatric fulminant myocarditis, and hsa_circ_0071542 could serve as a promising biomarker.

Clinical and experimental aspects of breathing modulation by inflammation

Neuroinflammation is produced by local or systemic alterations and mediated mainly by glia, affecting the activity of various neural circuits including those involved in breathing rhythm generation and control. Several pathological conditions, such as sudden infant death syndrome, obstructive sleep apnea and asthma exert an inflammatory influence on breathing-related circuits. Consequently breathing (both resting and ventilatory responses to physiological challenges), is affected; e.g., responses to hypoxia and hypercapnia are compromised. Moreover, inflammation can induce long-lasting changes in breathing and affect adaptive plasticity; e.g., hypoxic acclimatization or long-term facilitation. Mediators of the influences of inflammation on breathing are most likely proinflammatory molecules such as cytokines and prostaglandins. The focus of this review is to summarize the available information concerning the modulation of the breathing function by inflammation and the cellular and molecular aspects of this process. I will consider: 1) some clinical and experimental conditions in which inflammation influences breathing; 2) the variety of experimental approaches used to understand this inflammatory modulation; 3) the likely cellular and molecular mechanisms.

A systematic review exploring the relationship between infection and sudden unexpected death between 2000 and 2016: A forensic perspective

Death due to infectious diseases is a major health concern worldwide. This is of particular concern in developing countries where poor-socio economic status and a lack of healthcare resources contribute to the high burden of disease. In some cases death due to infection can be acute and aggressive, and death may occur without a diagnosis whilst the person is still alive. These deaths may ultimately lead to a medico-legal autopsy being performed. There are various mechanisms by which sudden death due to infection may occur. In addition, there are many risk factors associated with sudden death due to infection, which differ between infants and older individuals. However, it is unclear which pathogens and risk factors are most frequently associated with sudden death due to infection. Therefore a systematic review of articles and case reports published between 1 January 2000 and 30 June 2016 was undertaken in order to (1) explore the relationship between pathogens and their causative role and (2) identify the relationship between predisposing and/or risk factors associated with sudden death due to infection. Major databases were searched and after critical appraisal 143 articles were identified. It was found that respiratory infections and deaths involving bacterial pathogens were most commonly associated with these deaths. In addition the most common risk factors in infants were exposure to tobacco smoke and co-sleeping. In adults the most common risk factors were co-morbid conditions and illnesses. This information aids in a better understanding of these deaths and highlights the need for more research in this field, particularly in developing countries.

Myocarditis in Paediatric Patients: Unveiling the Progression to Dilated Cardiomyopathy and Heart Failure

Myocarditis is a challenging and potentially life-threatening disease associated with high morbidity in some paediatric patients, due to its ability to present as an acute and fulminant disease and to ultimately progress to dilated cardiomyopathy. It has been described as an inflammatory disease of the myocardium caused by diverse aetiologies. Viral infection is the most frequent cause of myocarditis in developed countries, but bacterial and protozoal infections or drug hypersensitivity may also be causative agents. The prompt diagnosis in paediatric patients is difficult, as the spectrum of clinical manifestation can range from no myocardial dysfunction to sudden cardiac death. Recent studies on myocarditis pathogenesis have revealed a triphasic nature of this disease, which influences the diagnostic and therapeutic strategies to adopt in each patient. Endomyocardial biopsy remains the gold standard for diagnosing myocarditis, and several non-invasive diagnostic tools can be used to support the diagnosis. Intravenous immunoglobulin has become part of routine practice in the treatment of myocarditis in paediatric patients at many centres, but its true effect on the cardiac function has been the target of many studies. The aim of this review is to approach the recently discovered facets of paediatric myocarditis regarding its progression to dilated cardiomyopathy.

Coxsackievirus B heart infections and their putative contribution to sudden unexpected death: An 8-year review of patients and victims in the coastal region of Tunisia

Coxsackieviruses B (CV B) are known as the most common viral cause of human heart infections. Cardiac inflammations contribute to sudden unexpected death (SUD) significantly. The diagnosis remains difficult with the traditional diagnostic tests and must be substantially improved. This has prompted health professionals to seek new diagnostic procedures which may provide important clues regarding underlying etiology. The present study is based on patients with infectious heart diseases and SUD victims with no relevant pathologies. They were investigated for possible CV-B infection. Patients with coronary artery diseases and unnatural road and domestic accident victims served as controls. The samples were studied for CV-B applying PCR. Histopathology for inflammatory markers, immunohistochemistry (IHC) for immune inflammatory cells and the enteroviral VP1-capsid protein were performed. Overall, 102 patients and 87 SUD victims were studied. As controls, 100 patients and 54 SUD unnatural accident victims were enrolled. CV-B were detected in 28 patients and 15 SUD victims. The control group samples were completely virus negative. Compared to controls, IHC revealed a significant presence of T and B lymphocytes within the myocardium. Furthermore, enteroviral VP1-capsid protein were detected from samples by IHC. Applying a comprehensive combination of methods, our results demonstrate the involvement of CV-B in cases of heart infection suggesting they play a significant role in SUD. Our results emphasize the importance of opting for a combination of methods.

Postmortem diagnosis of infectious heart diseases: A mystifying cause of Sudden Infant Death

Sudden infant death (SID) is an unresolved problem of high relevance and previous studies have indicated a role of viral heart infections. The diagnosis remains difficult in clinical practice using routine diagnostic tests and must be substantially improved. A prospective study based on post-mortem samples from SID victims whose heart disease was not clinically recognized was conducted for 4 years in a Tunisian University Hospital. Pediatric cases of unnatural death served as controls. Both SID victims and controls were investigated for possible coxsackievirus-B (CV-B) infection in heart tissue. During the study period, 39 cases with a male predominance (77%) were reported. There was no positive family history of coronary artery disease among the victims. In 35 cases (90%), low birth weight and/or critical development period were reported. All SID victims had complained of mild fever and insomnia for a few days preceding death, which required infectious laboratory investigations marked with an elevated white blood cell count (WBC) and C-reactive protein (CRP). The cardiac biomarkers were also elevated. The histopathological investigations of the heart tissue samples revealed signs of myocardial and pericardial inflammation. Enterovirus was detected by immunohistochemistry (IHC) and PCR from myocardial samples from 6 cases (15.3%) having myocarditis and 3 cases (7.7%) having perimyocarditis. The current study is of great interest and is aimed at urging health professionals to adopt systematically long intensive heart care in infants with underlying vulnerability as well as new diagnostic approaches including histopathology complemented with IHC and molecular pathology.

Coxsackievirus B detection in cases of myocarditis, myopericarditis, pericarditis and dilated cardiomyopathy in hospitalized patients

Coxsackieviruses B (CV-B) are known as the most common viral cause of human heart infections. The aim of the present study was to assess the potential role of CV-B in the etiology of infectious heart disease in hospitalized patients. The present study is based on blood, pericardial fluid and heart biopsies from 102 patients and 100 control subjects. All of the samples were examined for the detection of specific enteroviral genome using the reverse transcription polymerase chain reaction (RT-PCR) and sequence analysis. Immunohistochemical investigations for the detection of the enteroviral capsid protein, VP1, from the biopsies were performed. The samples were cultured on confluent KB monolayer cell line for possible virus isolation. The epidemiological data were also collected. CV-B was detected in 28 of the 102 patients. The sequence analysis demonstrated that 27 strains were identical to CV-B3 and only one strain was identical to CV-B1. Furthermore, VP1 in the heart biopsies was detected in enterovirus-positive cases, as revealed by RT-PCR. Pericarditis infection was more frequent than myocarditis (P<0.05) or myopericarditis (P=0.05). The epidemiological data demonstrate that CV-B heart infections occur mainly during autumn and winter, and young male adults are more susceptible than adolescents or adults (P<0.5). The present findings demonstrate a higher prevalence of viral heart infections, suggesting that CV-B may significantly contribute to heart infections.

Post-mortem diagnosis, of cytomegalovirus and varicella zoster virus co-infection by combined histology and tissue molecular biology, in a sudden unexplained infant death

BACKGROUND

An autopsy case of a two-month-old male infant who suddenly and unexpectedly died during his sleep, eight days after the onset of benign varicella.

OBJECTIVES

To describe post-mortem combined histological and tissue molecular biological techniques for the diagnosis of cytomegalovirus and varicella zoster virus co-infection as a cause of death.

STUDY DESIGN

Real-time quantitative PCR and RT-PCR assays for Herpesviruses, respiratory viruses, Adenovirus, Enterovirus and Parvovirus B19 were performed on multi-organ frozen samples and paraffin-embedded tissues in combination with histology.

RESULTS

Cytomegalovirus and varicella zoster virus were detected by molecular biology with highest viral loads detected in the lungs (4.6×10(7) and 1.9×10(5) genome copies per million of cells, respectively). Pulmonary extensive necrotizing inflammation and immunohistochemistry correlated to virological data. Virological molecular biology was negative on paraffin-embedded tissues.

CONCLUSIONS

This case shows that thorough quantitative virological investigations on frozen tissues must be performed in combination with histology and immunohistochemistry for the determination of the cause of a sudden unexplained infant death.

Infant Heart Dissection in a Forensic Context: Babies are Not Just Small Adults

Medical examiners who investigate infant deaths are required to consider a large number of natural and non-natural causes due to the broad differential diagnosis of unexpected infant death. Among the myriad of causes are those related to disorders in structure and function of the cardiovascular system. Adult hearts are routinely and efficiently evaluated by medical examiners because of the large anatomic structures and limited spectrum of commonly encountered diseases. Infant deaths are comparatively rare. Although infant hearts may be evaluated with similar efficiency, the pathologist must first have a detailed knowledge of developmental cardiovascular anatomy and of the subtleties of a broad spectrum of infantile cardiovascular pathology. Furthermore, the pathologist must be aware of additional details to be observed and documented in infant cardiac studies, and of the dissection techniques that facilitate acquisition of that data. Rote dissection of an infant heart as if it were an adult heart may lead to overlooked malformations and diseases that may have been the underlying cause of death. This brief review paper covers the fundamentals of pediatric cardiovascular anatomy and dissection techniques as they apply to the practice of pediatric forensic pathology.

The management of myocarditis

Despite considerable advances in our understanding of myocarditis pathogenesis, the clinical management of myocarditis has changed relatively little in the last few years. This review aims to help bridge the widening gap between recent mechanistic insights, which are largely derived from animal models, and their potential impact on disease burden. We illustrate the pathogenetic mechanisms that are prime targets for novel therapeutic interventions. Pathway and pathogen-specific molecular diagnostic tests have expanded the role for endomyocardial biopsy. State of the art cardiac magnetic resonance imaging can now provide non-invasive tissue characterization and localize inflammatory infiltrates but imaging techniques are misleading if infectious agents are involved. We emphasize the gaps in our current clinical knowledge, particularly with respect to aetiology-based therapy, and suggest opportunities for high impact, translational investigations.

Investigating sudden unexpected death in infancy and early childhood

Sudden unexpected death is one of the most frequent ways of dying in the first year of life after the neonatal period. It is however, much less frequent after the first birthday. Investigations into the cause of death are very important, for a significant proportion of these sudden deaths can be explained only after a thorough investigation. Of the causes identified, infection is the most frequent cause; metabolic disorders and cardiovascular diseases play a role as well, although the proportion of cases is much smaller. There is now evidence that cardiac channel gene mutations also play an important role; however, identification of these conditions relies on costly testing that is not readily or widely available. The physician's role as primary care provider is critical in ensuring that families understand the results of the investigation into their child's death. It is important that everything be done to identify the cause of death so that no such tragedy recurs in the same family.

Ljungan virus: a commentary on its association with fetal and infant morbidity and mortality in animals and humans

Epidemiologic and experimental data support the notion that Ljungan virus (LV), endemic in some rodent populations in Sweden, Denmark, and the United States, can cause morbidity and mortality in animals and humans. LV infection can cause type I diabetes mellitus, myocarditis, and encephalitis in bank voles and experimental mice, and lemmings. Mouse dams infected with LV experience high rates of stillbirth that may persist across generations, and their fetuses may develop cranial, brain, and limb malformations. In humans, epidemiologic and serologic data suggest that LV infection correlates with intrauterine fetal death, malformations, placental inflammation, myocarditis, encephalitis, and Guillain-Barré syndrome. The proposed role of LV infection in SIDS is unconvincing. Further research is necessary to clarify the role of LV infection in animal and human disease.

Cardiomyopathies--misdiagnosed as Sudden Infant Death Syndrome (SIDS)

Cardiomyopathies are an important and heterogenous group of diseases. With the identification of several new disease entities over the past decade, advances in diagnosis and precise causation, some disease definitions have become outdated. The past decade has witnessed a rapid evolution of molecular genetics in cardiology, e.g. myocardial diseases (Hypertrophic cardiomyopathy-HCM, Arrhythmogenic right ventricular cardiomyopathy-ARVCM) and channelopathies (Long QT syndrome-LQTS, Brugada syndrome-BrS, Catecholaminergic Polymorphic Ventricular Tachycardia-CPVT and Short QT syndrome-SQTS) as diseases predisposing to potentially lethal ventricular tachyarrhythmias. Beside the detection of mutations in several genes, histological and immunohistochemical findings can point to a cardiomyopathy as underlying disease. Therefore, previous microscopical investigations of different parts of the myocardium can help to select those cases of suspected Sudden Infant Death Syndrome (SIDS), where a search for genetic mutations can lead to a diagnosis explaining the sudden and unexpected death.

Myocardial inflammation, cellular death, and viral detection in sudden infant death caused by SIDS, suffocation, or myocarditis

The significance of minor myocardial inflammatory infiltrates and viral detection in SIDS is controversial. We retrospectively compared the demographic profiles, myocardial inflammation, cardiomyocyte necrosis, and myocardial virus detection in infants who died of SIDS in a safe sleep environment, accidental suffocation, or myocarditis. Formalin-fixed, paraffin-embedded myocardial sections were semiquantitatively assessed for CD3 lymphocytes and CD68 macrophages using immunohistochemistry and for cardiomyocyte cell death in H&E-stained sections. Enteroviruses and adenoviruses were searched for using PCR technology. The means of lymphocytes, macrophages, and necrotic cardiomyocytes were not statistically different in SIDS and suffocation cases. Enterovirus, not otherwise specified, was detected in one suffocation case and was the only virus detected in the three groups. Very mild myocardial lymphocyte and macrophage infiltration and scattered necrotic cardiomyocytes in SIDS are not pathologic, but may occur after the developing heart is exposed to environmental pathogens, including viruses.

Cytomegalovirus-induced pneumonia and myocarditis in three cases of suspected sudden infant death syndrome (SIDS): Diagnosis by immunohistochemical techniques and molecularpathologic methods

Immunohistochemical and molecularpathologic techniques have improved the diagnosis of myocarditis as compared with conventional histologic staining methods done according to the Dallas criteria. Additionally, immunohistochemistry and in situ-hybridization are able to demonstrate viral infection, e.g. cytomegaloviruses in salivary glands and lungs, locations both known to be involved in cytomegalovirusinfection. However, in many cases of proved cytomegalovirusinfection the cause of death remains unclear. We report on three children younger than 1-year of age, who died suddenly without prodromal symptoms. Their deaths were attributed to SIDS (sudden infant death syndrome). In situ-hybridization, immunohistochemical (LCA, CD45R0, CD68, MHC-class-II-molecules, E-selectine) and molecularpathologic investigations (PCR), however, suggested that death was caused by a cytomegalovirus-induced pneumonia or myocarditis. In the future, these methods should be used for investigating cases with suspicion of SIDS.

Lethal enterovirus-induced myocarditis and pancreatitis in a 4-month-old boy

After inconspicuous pregnancy and birth, a 16-year-old mother presented her male baby 5 days later with severe diarrhoea and vomiting. During the following weeks, the child temporarily showed hypotension, hypothermia and increased body temperature, bradyarrythmia with apnoea, continuing diarrhoea, sometimes vomiting and developed signs of pancreatic insufficiency. Due to increasing loss of weight and obviously severe dystrophia, parenteral nutrition had to be initiated. All clinical investigations revealed no underlying disease. Numerous biopsies, mainly from the gastrointestinal tract were taken, but no relevant pathological findings were disclosed. The baby was found lifeless by his mother, 4 months after birth. According to the death certificate, the physicians regarded the lethal outcome as a case of sudden infant death syndrome (SIDS). Histological and immunohistochemical investigations of organ samples revealed signs of myocarditis, pancreatitis and focal pneumonia. Molecularpathological techniques were used to detect enterovirus RNA from tissue samples from the myocardium, liver and pancreas. Enteroviral myocarditis with concomitant pancreatitis was determined as cause of death.

Coxsackievirus B3 sequences in the myocardium of fatal cases in a cluster of acute myocarditis in Greece

AIM

The investigation of three fatal cases during a nationwide cluster of cases of an upper respiratory tract infection (URTI) associated with myocarditis and/or pericarditis in Greece in 2002.

METHODS

In the three women who died, necropsies were performed and tissue sections were taken for histological examination, antigen detection by immunohistochemistry and indirect immunofluorescence assay (IFA), amplification of viral genomes by nested reverse transcription polymerase chain reaction (RT-PCR), and sequence analysis.

RESULTS

All samples showed histological signs of active myocarditis. Immunohistochemistry revealed the presence of the enterovirus VP1 family of proteins and IFA revealed the presence of coxsackievirus B3 antigen. Nested RT-PCR amplified enteroviral alleles of the 5'-untranslated region which were identical to each other and to the coxsackievirus B3 sequences.

CONCLUSIONS

This study provides pathological evidence of enteroviral infection among fatal myocarditis cases in a nationwide URTI cluster of cases associated with myocarditis and/or pericarditis.

Generation and analysis of an RNA vaccine that protects against coxsackievirus B3 challenge

Coxsackievirus B3 (CVB3) is an important human pathogen that causes substantial morbidity and mortality but, to date, no vaccine is available. We have generated an RNA-based vaccine against CVB3 and have evaluated it in the murine model of infection. The vaccine was designed to allow production of the viral polyprotein, which should be cleaved to generate most of the viral proteins in their mature form; but infectious virus should not be produced. In vitro translation studies indicated that the mutant polyprotein was efficiently translated and was processed as expected. The mutant RNA was not amplified in transfected cells, and infectious particles were not produced. Furthermore, the candidate RNA vaccine appeared safe in vivo, causing no detectable pathology following injection. Finally, despite failing to induce detectable neutralizing antibodies, the candidate RNA vaccine conferred substantial protection against virus challenge, either with an attenuated recombinant CVB3, or with the highly pathogenic wt virus.

Possible pathomechanisms of sudden infant death syndrome: key role of chronic hypoxia, infection/inflammation states, cytokine irregularities, and metabolic trauma in genetically predisposed infants

Chronic hypoxia, viral infections/bacterial toxins, inflammation states, biochemical disorders, and genetic abnormalities are the most likely trigger of sudden infant death syndrome (SIDS). Autopsy studies have shown increased pulmonary density of macrophages and markedly more eosinophils in the lungs accompanied by increased T and B lymphocytes. The elevated levels of immunoglobulins, about 20% more muscle in the pulmonary arteries, increased airway smooth muscle cells, and increased fetal hemoglobin and erythropoietin are evidence of chronic hypoxia before death. Other abnormal findings included mucosal immune stimulation of the tracheal wall, duodenal mucosa, and palatine tonsils, and circulating interferon. Low normal or higher blood levels of cortisol often with petechiae on intrathoracic organs, depleted maternal IgG antibodies to endotoxin core (EndoCAb) and early IgM EndoCAb triggered, partial deletions of the C4 gene, and frequent IL-10-592*A polymorphism in SIDS victims as well as possible hypoxia-induced decreased production of antiinflammatory, antiimmune, and antifibrotic cytokine IL-10, may be responsible for the excessive reactions to otherwise harmless infections. In SIDS infants, during chronic hypoxia and times of infection/inflammation, several proinflammatory cytokines are released in large quantities, sometimes also representing a potential source of tissue damage if their production is not sufficiently well controlled, eg, by pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP). These proinflammatory cytokines down-regulate gene expression of major cytochrome P-450 and/or other enzymes with the specific effects on mRNA levels, protein expression, and enzyme activity, thus affecting metabolism of several endogenous lipophilic substances, such as steroids, lipid-soluble vitamins, prostaglandins, leukotrienes, thromboxanes, and exogenous substances. In SIDS victims, chronic hypoxia, TNF-alpha and other inflammatory cytokines, and arachidonic acid (AA) as well as n-3 polyunsaturated fatty acids (FA), stimulated and/or augmented superoxide generation by polymorphonuclear leukocytes, which contributed to tissue damage. Chronic hypoxia, increased amounts of nonheme iron in the liver and adrenals of these infants, enhanced activity of CYP2C9 regarded as the functional source of reactive oxygen species (ROS) in some endothelial cells, and nicotine accumulation in tissues also intensified production of ROS. These increased quantities of proinflammatory cytokines, ROS, AA, and nitric oxide (NO) also resulted in suppression of many CYP450 and other enzymes, eg, phosphoenolpyruvate carboxykinase (PEPCK), an enzyme important in the metabolism of FA during gluconeogenesis and glyceroneogenesis. PEPCK deficit found in SIDS infants (caused also by vitamin A deficiency) and eventually enhanced by PACAP lipolysis of adipocyte triglycerides resulted in an increased FA level in blood because of their impaired reesterification to triacylglycerol in adipocytes. In turn, the overproduction and release of FA into the blood of SIDS victims could lead to the metabolic syndrome and an early phase of type 2 diabetes. This is probably the reason for the secondary overexpression of the hepatic CYP2C8/9 content and activity reported in SIDS infants, which intensified AA metabolism. Pulmonary edema and petechial hemorrhages often present in SIDS victims may be the result of the vascular leak syndrome caused by IL-2 and IFN-alpha. Chronic hypoxia with the release of proinflammatory mediators IL-1alpha, IL-1beta and IL-6, and overloading of the cardiovascular and respiratory systems due to the narrowing airways and small pulmonary arteries of these children could also contribute to the development of these abnormalities. Moreover, chronic hypoxia of SIDS infants induced also production of hypoxia-inducible factor 1alpha (HIF-1alpha), which stimulated synthesis and release of different growth factors by vascular endothelial cells and intensified subclinical inflammatory reactions in the central nervous system, perhaps potentiated also by PACAP and VIP gene mutations. These processes could lead to the development of brainstem gliosis and disorders in the release of neuromediators important for physiologic sleep regulation. All these changes as well as eventual PACAP abnormalities could result in disturbed homeostatic control of the cardiovascular and respiratory responses of SIDS victims, which, combined with the nicotine effects and metabolic trauma, finally lead to death in these often genetically predisposed children.

Fulminant myocarditis demonstrating uncommon morphology--a report of two autopsy cases

Two autopsy cases of fulminant myocarditis demonstrating uncommon morphology were studied. Subjects included two male patients: a 42-year-old (case 1) and a 39-year-old (case 2). Both cases had fever, chest or epigastric pain, electrocardiographic abnormalities, prominent elevation of serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactic dehydrogenase and creatine phosphokinase. They were treated with intra-aortic balloon pumping and percutaneous cardiopulmonary support, and they died at 3 days and 4 days after admission (total course of 10 days and 9 days), respectively. Case 1 showed focal necrosis, severe myocardial dystrophic calcification positive for Kossa stain, inflammatory edema, lymphocyte and macrophage infiltration and extravasation of erythrocytes. Case 2 showed acute inflammation and severe myocardial necrosis with neutrophilic abscess, lymphocyte and macrophage infiltration, cell debris and purulent exudate. Calcified, degenerative and necrotic cardiac myocytes and macrophages were reacted with anti-Enterovirus antibody (clone 5-D8/1), which recognizes an epitope on the VP1 peptide of most Coxsackievirus, echovirus, poliovirus and enterovirus strains. Therefore, the present two cases may be compatible with fulminant enterovirus-associated myocarditis. Using reverse transcriptase-semi-nested polymerase chain reaction, picornaviral RNA was detected in the amplified products extracted from the paraffin-embedded myocardial sample of case 1 but not in case 2.

Role of virus-induced myocardial affections in sudden infant death syndrome: a prospective postmortem study

The cause of sudden infant death syndrome (SIDS) is an unresolved problem of high relevance. Previous studies indicate a role of infections. In our prospective study, we investigated the frequency of virus-induced myocardial affections in SIDS. Postmortem samples from SIDS victims and control subjects were investigated prospectively. Pediatric cases of unnatural death served as controls. Samples were studied for enteroviruses, adenoviruses, parvovirus B19, and Epstein-Barr virus applying PCR. Immunohistochemical investigations for inflammatory cells, the necrosis marker C5b-9((m)) complement complex, and the enteroviral capsid protein VP1 were performed. Overall, 62 SIDS victims were studied. As controls, 11 infants were enrolled. Enteroviruses were detected in 14 (22.5%), adenoviruses in 2 (3.2%), Epstein-Barr viruses in 3 (4.8%), and parvovirus B19 in 7 (11.2%) cases of SIDS. Control group samples were completely virus negative. Compared with controls, immunohistochemical investigations partially revealed a significant increase in the number of T lymphocytes in SIDS myocardial samples (p < 0.05). Furthermore, cases with elevated numbers of leukocytes and macrophages, microfocal C5b-9((m))(+) necroses, and enteroviral VP1 capsid protein within the myocardium were detected. Applying a comprehensive combination of molecular and immunohistochemical techniques, our results demonstrate a clearly higher prevalence of viral myocardial affections in SIDS. Our results emphasize the importance of PCR-based diagnosis of viral myocardial affections. We suggest preliminary criteria for cellular immunohistochemical diagnosis of viral myocardial affections derived from our findings. For future investigations in SIDS, we suggest a comprehensive approach that includes PCR and immunohistochemistry. Our results offer novel strategies for diagnosis of pediatric myocardial viral affections.

Coxsackievirus B3 and the neonatal CNS: the roles of stem cells, developing neurons, and apoptosis in infection, viral dissemination, and disease

Neonates are particularly susceptible to coxsackievirus infections of the central nervous system (CNS), which can cause meningitis, encephalitis, and long-term neurological deficits. However, viral tropism and mechanism of spread in the CNS have not been examined. Here we investigate coxsackievirus B3 (CVB3) tropism and pathology in the CNS of neonatal mice, using a recombinant virus expressing the enhanced green fluorescent protein (eGFP). Newborn pups were extremely vulnerable to coxsackievirus CNS infection, and this susceptibility decreased dramatically by 7 days of age. Twenty-four hours after intracranial infection of newborn mice, viral genomic RNA and viral protein expression were detected in the choroid plexus, the olfactory bulb, and in cells bordering the cerebral ventricles. Many of the infected cells bore the anatomical characteristics of type B stem cells, which can give rise to neurons and astrocytes, and expressed the intermediate filament protein nestin, a marker for progenitor cells. As the infection progressed, viral protein was identified in the brain parenchyma, first in cells expressing neuron-specific class III beta-tubulin, an early marker of neuronal differentiation, and subsequently in cells expressing NeuN, a marker of mature neurons. At later time points, viral protein expression was restricted to neurons in specific regions of the brain, including the hippocampus, the entorhinal and temporal cortex, and the olfactory bulb. Extensive neuronal death was visible, and appeared to result from virus-induced apoptosis. We propose that the increased susceptibility of the neonatal CNS to CVB infection may be explained by the virus' targeting neonatal stem cells; and that CVB is carried into the brain parenchyma by developing neurons, which continue to migrate and differentiate despite the infection. On full maturation, some or all of the infected neurons undergo apoptosis, and the resulting neuronal loss can explain the longer-term clinical picture.