Pathophysiology of Cardiac Inflammation: Molecular Mechanisms

Background: Inflammatory processes induced by rival infection are believed to be one of the major pathogenetic mechanisms in inflammatory dialted cardiomyopathy. Although the reason for progression to myocardial failure is not fully understood, postulated mechanisms include persistent viral infection alone or in combination with autoimmune processes. Pathophysiology: Murine models of myocarditis have provided insight into the mechanisms by which autoimmune responses to cardiac antigens, probably in response to viral infection of the myocardium, arise and cause tissue pathology. Organ-specificity, cross-reactivity between microbial agents and cardiac tissue, and induction of tolerance to self-antigen are issues still at stake. In addition, cytokines mediate activation and effector phase of innate and specific immunity, which are both important in controlling viral infection. The innate immune response not only has an important protective function but also serves to initiate and regulate subsequent specific immune responses. In man, on the one hand specific T cells and antibodies against different cardiac tissue components have been demonstrated in myocardium and sera of patients with inflammatory cardiomyopathy, and on the other hand viral genome has been identified in endomyocardial biopsies due to the rapid development of new molecular biological techniques such as polymerase chain reaction (PCR), southern blot analysis and in-situ hybridization. But it is still a mater of debate whether virus infection itself, the ensuing immune response, or both, contribute to the deterioration of left ventricular function. Conclusion: Taking these mechanisms into account, screening for viral genome by PCR and detection of inflammatory infiltrates by immunohistochemistry are considered cricual for the establishment of a definite diagnosis thereby allowing for the initiation of specific therapeutic strategies. Hintergrund: In der Pathogenese entzündlicher Herzmuskelerkrankungen werden seit geraumer Zeit unterschiedliche Mechanismen diskutiert. Zum einen führt die Infektion des Myokards mit kardiotropen Erregern, hervorgerufen durch eine Reihe unterschiedlicher Viren, aber auch bakterielle Infektionen mit Chlamydien oder Borrelien, zu einer Entzündung des Herzmuskels. Auf der anderen Seite kommt dem Immunsystem mit seinen Effektormolekülen wie T- und B-Lymphozyten und Zytokinen im Hinblick auf die Entzündungsreaktion eine wichtige Rolle zu. Bisher sind jedoch die Ursachen für eine zunehmende Herzinsuffizienz bei Patienten mit entzündlicher Herzmuskelerkrankung noch nicht im einzelnen verstanden. Pathophysiologie: Tiermodelle zur Pathogenese der Myokarditis haben viel zum Verständnis der antikardialen Immunreaktion, möglicherweise ausgelöst als Antwort auf virale oder bakterielle Infektionen, beigetragen. Organspezifität, Kreuzreaktivität zwischen mikrobiellen Oberflächen und kardialen Antigenen und die Induktion einer Toleranz gegenüber Selbstantigenen sind Gegenstand der Diskussion. Zytokine, freigesetzt von einer Reihe von kardialen Zellen, und Zellen des Immunsystems aktivieren und modulieren sowohl das angeborene als auch das spezifische Immunsystem, wobei beide an der Kontrolle einer Virusinfektion beteiligt sind. Das angeborene Immunsystem mit bestimmten, für jedes Individuum festgelegten Möglichkeiten der Abwehr initiiert und kontrolliert alle weiteren Abwehrfunktionen des spezifischen Immunsystems. In Seren und Myokardgewebe von Patienten mit entzündlicher Herzmuskelerkrankung konnten inzwischen Antikörper und T-Lymphozyten nachgewiesen werden, die gegen Bestandteile des myokardialen Gewebes gerichtet sind. Durch moderne Untersuchungsmethoden wie Polymerasekettenreaktion (PCR), Southern-Blot-Hybridisierung und In-situ-Hybridisierung konnte außerdem der Nachweis von unterschiedlichen kardiotropen Erregern im Myokard geführt werden. Bisher ist es weiterhin Gegenstand der Diskussion, ob das Virus oder Bakterium selbst, der sich aus der Infektion entwickelnde Entzündungsprozess oder beide Mechanismen für die Einschränkung der Ventrikelfunktion und das Voranschreiten der Erkrankung bis zur schweren Herzinsuffizienz verantwortlich sind. Schlussfolgerung: Legt man diese pathogenetischen Mechanismen zugrunde, ist die Untersuchung der Endomyokardbiopsie durch moderne molekularbiologische und immunhistochemische Verfahren zum Nachweis kardiotroper Erreger und der Entzündungsreaktion inzwischen unbestritten die Methode der Wahl. Die differenzierte ätiologische Diagnostik aus Myokardgewebe ist die unverzichtbare Voraussetzung für klinische Therapiestudien, die die unterschiedlichen pathogenetischen Aspekte der Erkrankung berücksichtigen.     

Idiopathic dilated cardiomyopathy: a persistent viral infection or an organ-specific autoimmune disease? The trial of 2 major pathogenetic hypotheses]

Aetiology and pathogenesis of idiopathic dilated cardiomyopathy (DCM) are uncertain. The two major pathogenetic hypotheses are: 1) autoimmunity; 2) persistent viral infection. Indirect evidence for virus association comes from the finding of raised titres of antibody to coxsackievirus in DCM, but infectious virus has never been isolated in myocardium from DCM patients. Bowles et al. using the slot-blotting technique reported that enteroviral RNA was commonly detectable in the myocardium of patients with myocarditis (53%) and with DCM (52%). Other groups using this as well as more refined hybridization techniques have failed to confirm such a high prevalence. Detection of enteroviral genomic RNA in cardiac tissue does not, however, imply active infection or pathogenicity. Thus the mechanisms of chronic myocardial damage in the absence of whole competent infectious virus remain uncertain. The other major pathogenetic hypothesis in DCM involves autoimmune mediated damage to myocytes. Circulating organ specific autoantibodies have been reported in a quarter of a group of patients with idiopathic DCM. This suggests that there may be autoimmune mechanisms operating at least in this subset of patients, but the exact relation of these antibodies to the pathogenesis and prognosis needs to be defined. The abnormal expression of major histocompatibility complex class II antigens on cardiac microvascular endothelium in endomyocardial biopsy tissue from DCM patients, and the reported association with HLA-DR4 phenotype lend further support to the autoimmune hypothesis. The viral and the autoimmune hypothesis in chronic myocarditis and in DCM are not mutually exclusive. In experimentally murine virus-induced myocarditis infectious virus can no longer be recovered from the myocardium after two weeks, although nucleic acid sequences of the viral genome are still detectable. The development of chronic inflammation takes place only in mice with a predisposing genetic background. Chronic myocyte damage is associated with the production of circulating heart-specific autoantibodies and autoreactive lymphocytes. In this animal model chronic myocarditis appears to be a virus-triggered or precipitated autoimmune disease, rather than a persistent viral infection with tissue damage due to active virus synthesis and replication. A similar transition from acute myocarditis into DCM may occur in man.     

Genetically determined myocarditis: clinical presentation and immunological characteristics

PURPOSE OF REVIEW: Myocarditis is a clinically heterogeneous myocardial inflammatory disease, diagnosed by endomyocardial biopsy; it may be idiopathic, infectious, or autoimmune and may lead to dilated cardiomyopathy. Myocarditis and dilated cardiomyopathy represent different stages of an organ-specific autoimmune disease in genetically predisposed individuals. RECENT FINDINGS: In animal models, cell-mediated or antibody-mediated autoimmune myocarditis/dilated cardiomyopathy can be induced by viral infection or immunization with heart-specific autoantigens, or can develop spontaneously in genetically predisposed strains. Susceptibility is based on multiple major histocompatibility complex and nonmajor histocompatibility complex genes. In patients the diagnosis of autoimmune myocarditis/dilated cardiomyopathy requires exclusion of viral genome on endomyocardial biopsy and detection of serum heart-reactive autoantibodies. They are directed against multiple antigens that are found in patients and relatives from about 60% of familial and nonfamilial pedigrees. They predict dilated cardiomyopathy development among relatives, years before disease. Some antibodies have functional effects on cardiac myocytes in vitro, in animals and possibly in a dilated cardiomyopathy subset, responsive to extracorporeal immunoadsorption. SUMMARY: In myocarditis/dilated cardiomyopathy, cardiac-specific and disease-specific antibodies of IgG class are potential biomarkers for identifying 'at risk' relatives as well as those patients in whom, in the absence of active infection of the myocardium, immunosuppression, and/or immunomodulation may be beneficial. Future studies should better define the genetic basis of human autoimmune myocarditis/dilated cardiomyopathy.     

Immune-mediated and autoimmune myocarditis: clinical presentation, diagnosis and management

According to the current WHO classification of cardiomyopathies, myocarditis is an inflammatory disease of the myocardium and is diagnosed by endomyocardial biopsy using established histological, immunological and immunohistochemical criteria; it may be idiopathic, infectious or autoimmune and may heal or lead to dilated cardiomyopathy (DCM). DCM is characterized by dilatation and impaired contraction of the left or both ventricles; it may be idiopathic, familial/genetic, viral and/or immune. The diagnosis of DCM requires exclusion of known, specific causes of heart failure, including coronary artery disease. On endomyocardial biopsy, there is myocyte loss, compensatory hypertrophy, fibrous tissue and immunohistochemical findings consistent with chronic inflammation (myocarditis) in 30–40 % of cases. In a patient subset, myocarditis and DCM represent the acute and chronic stages of an inflammatory disease of the myocardium, which can be viral, post-infectious immune or primarily organ-specific autoimmune. Here, we review the clinical presentation, etiopathogenetic diagnostic criteria, and management of immune-mediated and autoimmune myocarditis.     

Regulation of innate immunity against hepatitis C virus infection.

Chronic hepatitis C virus (HCV) infection is a global public health problem. HCV infection is treated with type I interferon (IFN), a natural product that is produced by cells during virus infection as a result of innate immune signaling events. The secreted IFN alert the surrounding cells to turn on an "antiviral state" that resists infection. In general, the role of innate immune response is to suppress viral replication and to induce cytokines and other factors that promote adaptive immunity and the resolution of infection. The mechanisms by which the innate immune response and IFN actions limit HCV infection are not well defined, but are likely to involve the function of specific IFN-stimulated genes. HCV also copesintensively with immune responses in order to establish persistent infection. Recent studies reveal that a other viruses use similar tactics to regulate the antiviral innate immune response. In the case of HCV, innate immune signaling is strictly controlled by the viral NS3/4A protease, resulting in the disruption of IFN production. Here, we summarize the current understanding of how HCV evades the innate immune system.     

Inflammation in Dilated Cardiomyopathy

Inflammation is an important component in the pathogenesis of many common cardiovascular diseases. In most cases, the role of inflammation is a natural response to injury, and an important mechanism for healing and tissue repair. However, the inflammatory response can be either inadequate or overwhelming, leading to direct injury or severe host disease. Accumulating data has revealed an important inflammatory component in the pathogenesis of dilated cardiomyopathy (DCM), and there is growing evidence, that myocarditis and DCM are closely related. Many faces of DCM coexist, while different phases of the disease progress simultaneously: phase 1 is dominated by viral infection itself, phase 2 by the onset of (probably) multiple autoimmune reactions, and phase 3 by the progression to cardiac dilatation without an infectious agent and cardiac inflammation. Separation between the phases is not always distinct, they may overlap one another and phase 1 and 2 may recur after progression of DCM. Appropriate treatment during phase 1 includes eradication of virus and amelioration of injury caused by the virus. During phase 2, which is characterized by autoimmune processes, immunosuppression is the most appropriate therapy and warrants sophisticated diagnostic strategies including molecular biological and immunohistochemical techniques. Phase 3, DCM, although a result of viral and autoimmune injury, may then progress independently. The more attention given to serologic, molecular and immunologic factors to characterize and diagnose DCM lead to several changes in the terminology. The term cardiomyopathy is no longer reserved for the idiopathic forms but can be used interchangeably with the term heart muscle diseases including specific, secondary forms. Right ventricular cardiomyopathy (RVCM), valvular, hypertensive, ischemic, and inflammatory cardiomyopathy have been introduced. Idiopathic, autoimmune, and infectious forms of inflammatory cardiomyopathy were recognized. Viral cardiomyopathy is defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and is then termed inflammatory viral cardiomyopathy. Because of the overlap of pathophysiological stages in DCM, design of the appropriate therapy is important. It requires the immunohistochemical and molecular biological investigation of endomyocardial biopsies in parallel. In the modern molecular era the infective agent-immune system-host interaction has to be clarified leading to a better knowledge of the etiology of DCM. This may change the management of the disease in the future. One of the hopes is to discern the underlying dominant mechanism in a given patient to make a decision for the most promising therapy.     

Persistence of viral genome into late stages of murine myocarditis detected by polymerase chain reaction.

BACKGROUND. Enteroviruses have been considered as the most common etiologic agents in clinical myocarditis and dilated cardiomyopathy; however, their pathogenetic role remains unknown. Hence, the relation of viral replication and development of cardiomyopathy has been determined in a murine model of myocarditis by evaluating the persistence of viral genome during acute and chronic stages of myocarditis by means of Northern blot hybridization and polymerase chain reaction (PCR). METHODS AND RESULTS. DBA/2 mice (n = 146) were injected peritoneally with 10 plaque-forming units of encephalomyocarditis (EMC) virus, and the control mice (n = 33) were injected with normal saline. Animals were randomly killed at 4, 7, 10, 14, 21, 28, 35, and 42 days after infection. Histology revealed acute myocardial necrosis with massive inflammatory cell infiltrate peaking on day 14 followed by increasing fibrosis and declining chronic inflammation features compatible with dilated cardiomyopathy between days 21 and 42. Northern blot analysis of control and infected hearts showed detectable viral RNA in the infected hearts initially at day 4, peaking by day 7, diminishing between day 7 and day 14, and absent at day 21 and day 28. However, potential viral remnants present in low quantities and undetectable by Northern blot were further detected by PCR followed by confirmation with an internal oligonucleotide probe after day 14 up to day 42. CONCLUSIONS. Viral RNA signals on Northern blot showed a strong correlation with massive myocyte necrosis on day 14, but the viral RNA fragment was consistently detectable into late stages of cardiomyopathy on days 21, 28, 35, and 42 by PCR. This indicated that the mature virions are fully developed early in infection and are capable of persisting in the myocardium after virus-mediated myocytolysis stage. Therefore, PCR is an extremely sensitive method for detecting residual viral genome and viral persistence in the myocardium and may offer insights into the pathogenesis of chronic myocarditis leading to dilated cardiomyopathy.     

Dilated cardiomyopathy update: infectious-immune theory revisited

Dilated cardiomyopathy is characterized by dilatation of the left or right ventricle, or both ventricles. The degree of myocardial dysfunction is not attributable to abnormal loading conditions. The infectious-immune theory has long been hypothesized to explain the pathogenesis of many etiologically unrecognized dilated cardiomyopathies. Inflammations followed by immune reactions, which may be excessive, in the myocardium, evoked by external triggers such as viral infections and/or autoimmune antibodies, continue insidiously, and lead to the process of cardiac remodeling with ventricular dilatation and systolic dysfunction. This ultimately results in dilated cardiomyopathy. Hepatitis C virus-associated heart diseases are good examples of cardiac lesions definitely induced by viral infections in humans that progress to a chronic stage through complicated immune mechanisms. Therapeutic strategies for myocarditis and dilated cardiomyopathy have been obtained through analyses of the acute, subacute, and chronic phases of experimental viral myocarditis in mice. The appropriate modulation of excessive immune reactions during myocarditis, rather than their complete elimination, appears to be a key option in the prevention and treatment of dilated cardiomyopathy. The clinical application of an NF-κB decoy and immune adsorption of IgG3 cardiac autoantibodies have been used as immunomodulating therapies and may provide novel approaches for the treatment of refractory patients with dilated cardiomyopathy. Conventional therapeutic agents for chronic heart failure such as β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists in particular should be re-evaluated on the basis of their anti-inflammatory properties in the treatment of dilated cardiomyopathy.     

Duality of innate stress responses in cardiac injury, repair, and remodeling

The ability of the myocardium to successfully adapt to cardiac injury ultimately determines whether the heart will decompensate and fail, or whether instead it will maintain preserved function. Despite the importance of the myocardial response to cardiac injury, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we will summarize recent experimental material which suggests that the heart possess a germ-line encoded "innate" stress response that is activated in response to diverse forms of tissue injury. The extant literature suggests that this innate stress response plays an important role in initiating and integrating homeostatic responses within the heart. Nonetheless, as will be discussed further herein, these inflammatory mediators all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations.     

Role of host genetic factors in the outcome of hepatitis C virus infection

The natural history of hepatitis C virus (HCV) infection is determined by a complex interplay between host genetic, immunological and viral factors. This review highlights genes involved in innate and adaptive immune responses associated with different outcomes of HCV infection. For example, an association of HCV clearance with certain HLA alleles has been demonstrated. The mechanisms responsible for these associations have been linked to specific T cell responses for some particular alleles (e.g., HLA-B27). Genetic associations involved in T cell regulation and function further underline the role of the adaptive immune response in the natural history of HCV infection. In addition, some genes involved in innate NK cell responses demonstrate the complex interplay between components of the immune system necessary for a successful host response to HCV infection.     

Regulatory T cells in viral hepatitis

The pathogenesis and outcome of viral infections are significantly influenced by the host immune response. The immune system is able to eliminate many viruses in the acute phase of infection. However, some viruses, like hepatitis C virus (HCV) and hepatitis B virus (HBV), can evade the host immune responses and establish a persistent infection. HCV and HBV persistence is caused by various mechanisms, like subversion of innate immune responses by viral factors, the emergence of T cell escape mutations, or T cell dysfunction and suppression. Recently, it has become evident that regulatory T cells may contribute to the pathogenesis and outcome of viral infections by suppressing antiviral immune responses. Indeed, the control of HCV and HBV specific immune responses mediated by regulatory T cells may be one mechanism that favors viral persistence, but it may also prevent the host from overwhelming T cell activity and liver damage. This review will focus on the role of regulatory T cells in viral hepatitis.     

Hyper innate responses in neonates lead to increased morbidity and mortality after infection

Neonates suffer high morbidity and mortality in infection, presumably because of the lack of a fully developed adaptive and innate immune system. Evidence of poor innate responses in neonates has been shown by using a model that sensitizes the host to Toll-like receptor (TLR)-mediated inflammation with d-galactosamine (d-GalN). However, we show that neonatal mice demonstrate much stronger inflammatory responses than adult mice in response to LPS stimulation, and such hypersensitivity extends to other TLR agonists including actual viral infection. Our study reveals that the ensuing inflammatory reaction after d-GalN sensitization reflects preferential toxicity of d-GalN to adult liver cells, rather than accurately reflecting the TLR response to LPS. We show further that an uncontrolled proinflammatory innate response due to inadequate T cells makes neonates more vulnerable to TLR agonists or viral infection. Remarkably, through transfer of T cells into neonates or depletion of T cells in adult mice, we show that T cells are sufficient and necessary to control the early inflammatory response to LPS. Therefore, neonates might suffer from the unleashed innate responses caused by an insufficient number of T cells, which leads to increased morbidity and mortality.     

Innate Immunity and Immune Evasion by Enterovirus 71

Enterovirus 71 (EV71) is a major infectious disease affecting millions of people worldwide and it is the main etiological agent for outbreaks of hand foot and mouth disease (HFMD). Infection is often associated with severe gastroenterological, pulmonary, and neurological diseases that are most prevalent in children. Currently, no effective vaccine or antiviral drugs exist against EV71 infection. A lack of knowledge on the molecular mechanisms of EV71 infection in the host and the virus-host interactions is a major constraint to developing specific antiviral strategies against this infection. Previous studies have identified and characterized the function of several viral proteins produced by EV71 that interact with the host innate immune proteins, including type I interferon signaling and microRNAs. These interactions eventually promote efficient viral replication and increased susceptibility to the disease. In this review we discuss the functions of EV71 viral proteins in the modulation of host innate immune responses to facilitate viral replication.     

Crosstalk between innate and adaptive immunity in hepatitis B virus infection

Hepatitis B virus(HBV) infection is a major public healthproblem worldwide. HBV is not directly cytotoxic to infected hepatocytes; the clinical outcome of infection results from complicated interactions between the virus and the host immune system. In acute HBV infection, initiation of a broad, vigorous immune response is res-ponsible for viral clearance and self-limited inflammatory liver disease. Effective and coordinated innate and adaptive immune responses are critical for viral clearance and the development of long-lasting immunity. Chronic hepatitis B patients fail to mount efficient innate and adaptive immune responses to the virus. In particular, HBV-specific cytotoxic T cells, which are crucial for HBV clearance, are hyporesponsiveness to HBV infection. Accumulating experimental evidence obtained from the development of animal and cell line models has highlighted the importance of innate immunity in the early control of HBV spread. The virus has evolved immune escape strategies, with higher HBV loads and HBV protein concentrations associated with increasing impairment of immune function. Therefore, treatment of HBV infection requires inhibition of HBV replication and protein expression to restore the suppressed host immunity. Complicated interactions exist not only between innate and adaptive responses, but also among innate immune cells and different components of adaptive responses. Improved insight into these complex interactions are important in designing new therapeutic strategies for the treatment HBV infection. In this review, we summarize the current knowledge regarding the cross-talk between the innate and adaptive immune responses and among different immunocytes in HBV infection.     

从病毒性心肌炎演变为扩张型心肌病:病毒的作用

病毒感染、宿主免疫反应、以及遗传和环境变化是决定病毒性心肌炎向扩张型心肌病演变的重要因素,其中病毒感染既是启动又是影响疾病发生发展的关键环节。近年研究发现,病毒不仅对心肌细胞有直接和间接损伤作用,而且还通过逃逸宿主先天免疫、诱导免疫因子分泌或表达异常等机制推动疾病进程。抗病毒治疗有益于病毒性心肌炎患者的恢复,在一定程度上抑制扩张型心肌病的发生。     

Inflammatory Dilated Cardiomyopathy (DCMI)

Cardiomyopathies are heart muscle diseases, which have been defined by their central hemodynamics and macropathology and divided in five major forms: dilated (DCM), hypertrophic (HCM), restrictive (RCM), right ventricular (RVCM), and nonclassifiable cardiomyopathies (NCCM). Furthermore, the most recent WHO/WHF definition also comprises, among the specific cardiomyopathies, inflammatory cardiomyopathy as a distinct entity, defined as myocarditis in association with cardiac dysfunction. Idiopathic, autoimmune, and infectious forms of inflammatory cardiomyopathy were recognized. Viral cardiomyopathy has been defined as viral persistence in a dilated heart. It may be accompanied by myocardial inflammation and then termed inflammatory viral cardiomyopathy (or viral myocarditis with cardiomegaly). If no inflammation is observed in the biopsy of a dilated heart (< 14 lymphocytes and macrophages/mm(2)), the term viral cardiomyopathy or viral persistence in DCM should be applied according to the WHF Task Force recommendations.Within the German heart failure net it is the authors' working hypothesis, that DCM shares genetic risk factors with other diseases of presumed autoimmune etiology and, therefore, the same multiple genes in combination with environmental factors lead to numerous different autoimmune diseases including DCM. Therefore, the authors' primary goal is to acquire epidemiologic data of patients with DCM regarding an infectious and inflammatory etiology of the disease. Circumstantial evidence points to a major role of viral myocarditis in the etiology of DCM. The common presence of viral genetic material in the myocardium of patients with DCM provides the most compelling evidence, but proof of causality is still lacking. In addition, autoimmune reactions have been described in many studies, indicating them as an important etiologic factor. Nevertheless, data on the proportion of patients, in whom both mechanisms play a role are still missing.A pivotal role for autoimmunity in a substantial proportion of patients with DCM is supported by the presence of organ-specific autoantibodies, inflammatory infiltrates and pro-inflammatory cytotoxic cytokines. Furthermore, familial occurrence of DCM has been described in about 20-30% of cases, with the presence of autoantibodies and abnormal cytokine profiles in first-degree relatives with asymptomatic left ventricular enlargement. This suggests the involvement of a disrupted humoral and cellular immunity early in the development of the disease. A similar pattern of humoral and cellular immune dysregulation has been described in other autoimmune diseases. There is considerable evidence that genetic factors play an important role in the pathogenesis of DCM, either as contributors to the susceptibility to environmental factors or as determinants of functional and structural changes that characterize the phenotypic expression of the disease.Yet, it is not known whether the susceptibility to immunologically mediated myocardial damage reflects the presence of genetic risk factors shared by other autoimmune diseases. Preliminary investigations suggest, that this is the case, because the frequency of autoimmune disorders other than DCM was higher in first-degree relatives of the subjects with DCM including juvenile diabetes, rheumatoid arthritis, thyroiditis, psoriasis, and asthma.The nature of the genetic risk is undetermined and probably involves genes in the major histocompatibility (MHC) locus as well as other susceptibility loci. Therefore, the authors started their investigation with the search for MHC class 2 DQ polymorphisms in the peripheral blood of patients with DCM in parallel to the search for new interesting susceptibility loci by the use of the microarray analysis regarding genes responsible for inflammatory and autoimmune diseases. By this approach a new insight in the familial clustering of other autoimmune diseases in patients with DCM and in genetic predisposition can be expected.     

Classification and histological, immunohistochemical, and molecular diagnosis of inflammatory myocardial disease

In the WHO 1996 classification of cardiomyopathies, myocarditis is defined as an “inflammatory disease of the myocardium associated with cardiac dysfunction” and is listed among “specific cardiomyopathies”. Myocarditis is diagnosed on endomyocardial biopsy (EMB) by established histological, immunological, and immunohistochemical criteria, and molecular techniques are recommended to identify viral etiology. Infectious, autoimmune, and idiopathic forms of inflammatory cardiomyopathy are recognized that may lead to dilated cardiomyopathy. According to Dallas criteria, myocarditis is diagnosed in the setting of an “inflammatory infiltrate of the myocardium with necrosis and/or degeneration of adjacent myocytes, not typical of ischemic damage associated with coronary artery disease”. The majority of experts in the field agree that an actual increase in sensitivity of EMB has now been reached by using immunohistochemistry together with histology. A value of >14 leukocytes/mm² with the presence of T lymphocytes >7 cells/mm² has been considered a realistic cut off to reach a diagnosis of myocarditis. The development of molecular biological techniques, particularly amplification methods like polymerase chain reaction (PCR) or nested-PCR, allows the detection of low copy viral genomes even from an extremely small amount of tissue such as in EMB specimens. Positive PCR results obtained on EMB should always be accompanied by a parallel investigation on blood samples collected at the time of the EMB. According to the recent Association for European Cardiovascular Pathology guidelines, optimal specimen procurement and triage indicates at least three, preferably four, EMB fragments, each 1–2 mm in size, that should immediately be fixed in 10 % buffered formalin at room temperature for light microscopic examination. In expected focal myocardial lesions, additional sampling is recommended. Moreover, one or two specimens should be snap-frozen in liquid nitrogen and stored at ?80 °C or alternatively stored in RNA-later for possible molecular tests or specific stains. A sample of peripheral blood (5–10 ml) in EDTA or citrate from patients with suspected myocarditis allows molecular testing for the same viral genomes sought in the myocardial tissue.     

Basis of HBV persistence and new treatment options

The majority of the morbidity and mortality associated with hepatitis B virus infection is due to viral persistence and its consequences. The heterogeneity of outcomes from HBV infection suggests that both viral and host factors influence the development of chronic infection. Study of host genetic susceptibility has revealed a number of genes including MHC class II loci and cytokine receptors, which decrease the risk of persistence. On the viral side, the replication system is adapted to generate high levels of virions without stimulating the innate immune system. Secreted viral proteins (HBsAg and HBeAg) suppress innate responses through inhibition of TLR signaling, which leads to a weak adaptive immune response with an exhausted phenotype that is incapable of inducing viral elimination. However, even when the adaptive immune system begins to take effect after HBe seroconversion, the ability of the virus to mutate and evade T and B cell-mediated responses helps to sustain persistent infection. Understanding the mechanisms of persistence is important for the design of therapeutic strategies. Although there are currently no specific drugs that target the viral minichromosome (cccDNA), it is expected that in the future we will be able to use existing drugs more effectively to eliminate the infection.