Activation of Immune System May Cause Pathophysiological Changes in the Myocardium of SARS-CoV-2 Infected Monkey Model

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is an extremely contagious disease whereby the virus damages the host’s respiratory tract via entering through the ACE2 receptor. Cardiovascular disorder is being recognized in the majority of COVID-19 patients; yet, the relationship between SARS-CoV-2 and heart failure has not been established. In the present study, SARS-CoV-2 infection was induced in the monkey model. Thereafter, heart tissue samples were collected, and pathological changes were analyzed in the left ventricular tissue by hematoxylin and eosin, trichrome, and immunohistochemical staining specific to T lymphocytes and macrophages. The findings revealed that SARS-CoV-2 infection induces several pathological changes in the heart, which cause cardiomyocyte disarray, mononuclear infiltrates of inflammatory cells, and hypertrophy. Furthermore, collagen-specific staining showed the development of cardiac fibrosis in the interstitial and perivascular regions in the hearts of infected primates. Moreover, the myocardial tissue samples displayed multiple foci of inflammatory cells positive for T lymphocytes and macrophages within the myocardium. These findings suggest the progression of the disease, which can lead to the development of severe complications, including heart failure. Additionally, SARS-CoV-2 antigen staining detected the presence of virus particles in the myocardium. Thus, we found that SARS-CoV-2 infection is characterized by an exaggerated inflammatory immune response in the heart, which possibly contributes to myocardial remodeling and subsequent fibrosis.

CCR5 inhibition prevents cardiac dysfunction in the SIV/macaque model of HIV

Background

Diastolic dysfunction is a highly prevalent cardiac abnormality in asymptomatic as well as ART‐treated human immunodeficiency virus (HIV) patients. Although the mechanisms underlying depressed cardiac function remain obscure, diastolic dysfunction in SIV‐infected rhesus macaques is highly correlated with myocardial viral load. As cardiomyocytes are not productively infected, damage may be an indirect process attributable to a combination of pro‐inflammatory mediators and viral proteins.

Methods and Results

Given the diverse roles of CCR5 in mediating recruitment of leukocytes to inflammatory sites and serving as a receptor for HIV entry into cells, we investigated the role of CCR5 in the SIV/macaque model of diastolic dysfunction. We found that in SIV‐infected macaques, CCR5 inhibition dramatically impacted myocardial viral load measured by qRT‐PCR and prevented diastolic dysfunction measured by echocardiography. Complementary in vitro experiments using fluorescence microscopy showed that CCR5 ligands impaired contractile function of isolated cardiomyocytes, thus identifying CCR5 signaling as a novel mediator of impaired cardiac mechanical function.

Conclusions

Together, these findings incriminate SIV/HIV gp120‐CCR5 as well as chemokine‐CCR5 interactions in HIV‐associated cardiac dysfunction. These findings also have important implications for the treatment of HIV‐infected individuals: in addition to antiviral properties and reduced chemokine‐mediated recruitment and activation of inflammatory cells, CCR5 inhibition may provide a cardioprotective benefit by preventing cardiomyocyte CCR5 signaling.

Detection of herplex simplex virus-1 and -2 in cardiac myxomas

The etiology of sporadic cardiac myxomas remains elusive. The tendency for these lesions to recur following resection, their immunopathological characteristics, along with their histological and molecular profile, may implicate the presence of an infective agent in this type of tumor. In this study, we investigated the presence of herpes simplex virus (HSV) DNA in a cohort of cardiac myxomas in a tertiary referral centre. Twenty-nine formalin-fixed paraffin-embedded (FFPE) sporadic cardiac myxomas were obtained, 17 of which were shown to be informative. These were compared to 19 macroscopically and microscopically normal heart tissue specimens. The detection of HSV-1 and -2 genomic sequences was achieved with the use of a combined nested PCR-Restriction Fragment Length Polymorphism methodology. The presence of HSV-1 and/or -2 DNA was demonstrated in 6 of 17 (35%) informative sporadic cardiac myxomas, whereas no HSV DNA was detected in normal heart tissues (P < 0.01). The existence of HSV-1/2 DNA in sporadic cardiac myxomas, along with its absence from normal heart tissues, reinforces the possibility that HSV infection might be involved in the development of these lesions. Our findings raise the point of anti-HSV medication postsurgically with a potential benefit in reducing the rate of recurrences.

Adenoviral expression of IKs contributes to wavebreak and fibrillatory conduction in neonatal rat ventricular cardiomyocyte monolayers

Previous studies have shown that the gating kinetics of the slow component of the delayed rectifier K(+) current (I(Ks)) contribute to postrepolarization refractoriness in isolated cardiomyocytes. However, the impact of such kinetics on arrhythmogenesis remains unknown. We surmised that expression of I(Ks) in rat cardiomyocyte monolayers contributes to wavebreak formation and facilitates fibrillatory conduction by promoting postrepolarization refractoriness. Optical mapping was performed in 44 rat ventricular myocyte monolayers infected with an adenovirus carrying the genomic sequences of KvLQT1 and minK (molecular correlates of I(Ks)) and 41 littermate controls infected with a GFP adenovirus. Repetitive bipolar stimulation was applied at increasing frequencies, starting at 1 Hz until loss of 1:1 capture or initiation of reentry. Action potential duration (APD) was significantly shorter in I(Ks)-infected monolayers than in controls at 1 to 3 Hz (P<0.05), whereas differences at higher pacing frequencies did not reach statistical significance. Stable rotors occurred in both groups, with significantly higher rotation frequencies, lower conduction velocities, and shorter action potentials in the I(Ks) group. Wavelengths in the latter were significantly shorter than in controls at all rotation frequencies. Wavebreaks leading to fibrillatory conduction occurred in 45% of the I(Ks) reentry episodes but in none of the controls. Moreover, the density of wavebreaks increased with time as long as a stable source sustained the fibrillatory activity. These results provide the first demonstration that I(Ks)-mediated postrepolarization refractoriness can promote wavebreak formation and fibrillatory conduction during pacing and sustained reentry and may have important implications in tachyarrhythmias.

Tissue tropism of salmonid alphaviruses (subtypes SAV1 and SAV3) in experimentally challenged Atlantic salmon (Salmo salar L.)

Diagnosis of SAV infections has traditionally been based upon clinical observations together with a set of histopathological findings in exocrine pancreas, heart and skeletal muscle, but recently, real-time RT-PCR assays have been developed as a supplement for the detection of SAV. The aim of this study was to determine tissue tropism of SAV1 and SAV3 in Atlantic salmon Salmo salar L. in order to identify the most suitable tissues for real-time RT-PCR diagnostic assays. The results indicated that the pseudobranch and the heart (ventricle) are the most useful tissues for such assays, regardless of disease status. The pyloric caecae with associated pancreatic tissue is unsuitable for diagnosis using this method. The use of real-time RT-PCR enabled viral RNA detection at all stages of the disease, including in surviving fish six months after infection. Considering the short production cycle of farmed salmonids, this suggests that surviving Atlantic salmon may become life-long asymptomatic carriers of SAV after an infection.

In vivo gene delivery of HSP70i by adenovirus and adeno-associated virus preserves contractile function in mouse heart following ischemia-reperfusion

Inducible heat shock protein 70 (HSP70i) has been shown to exert a protective effect in hearts subjected to ischemia-reperfusion. Although studied in heat-shocked animals and in transgenic mice that constitutively overexpress the protein, the therapeutic application of the protein in the form of a viral vector-mediated HSP70i expression has not been widely examined. Accordingly, we have examined the effects of HSP70i delivered in vivo to the left ventricular free wall of the heart via viral gene therapy in mice. The affect of virally mediated HSP70i expression in preserving cardiac function following ischemia-reperfusion was examined after short-term expression (5-day adenovirus mediated) and long-term expression (8-mo adeno-associated virus mediated) in mice by subjecting ex vivo Langendorff perfused hearts to a regime of ischemia-reperfusion. Both vectors were capable of increasing HSP70i expression in the heart, and neither vector had any effect on cardiac function during aerobic (preischemic) perfusion when compared with corresponding controls. In contrast, both adenovirus-mediated and adeno-associated virus-mediated expression of HSP70i improved the contractile recovery of the heart after 120 min of reperfusion following ischemia. This study demonstrates the feasibility of using both short- and long-term expression of virally mediated HSP70i as a therapeutic intervention against cardiac ischemia-reperfusion injury.

Acute parvovirus B19 infection associated with myocarditis in an immunocompetent adult

Inflammatory heart disease is causally linked with progressive left ventricular dysfunction and congestive heart failure. In childhood, infection with parvovirus B19 (PVB19) is usually benign, causing erythema infectiosum. However, severe fetal PVB19 infection may be associated with hydrops fetalis and fetal death caused by myocarditis. Here we report a PVB19-induced myocarditis in a previously healthy 37-year-old patient admitted to the hospital because of chest pain and dyspnea due to left ventricular dysfunction. Four weeks after the onset of symptoms, we found lymphocytic infiltrates and PVB19 genome in left ventricular endomyocardial biopsy specimens. Consistently, acute PVB19 infection was indicated serologically by elevated IgM titers and the presence of PVB19 genome in peripheral blood lymphocytes. In conclusion, PVB19 infection may be complicated by acute myocarditis in immunocompetent adults. Because PVB19 myocarditis may progress to chronic dilated cardiomyopathy, early diagnosis by endomyocardial biopsy is important to initiate anti-inflammatory treatment.

Inflammatory left ventricular microaneurysms as a cause of apparently idiopathic ventricular tachyarrhythmias

BACKGROUND

We sought to investigate the arrhythmogenic role, incidence, treatment, and prognosis of inflammatory left ventricular (LV) microaneurysms in patients with apparently idiopathic ventricular tachyarrhythmias. Methods and Results-- We studied 156 consecutive patients (71 men, 85 women; mean age, 44.1+/-11.8 years) with severe ventricular arrhythmias and normal 2D echo cardiac parameters by coronary and ventricular angiography, biventricular endomyocardial biopsy, and electrophysiological study. Polymerase chain reaction was used to detect genomic sequences of enterovirus, adenovirus, Epstein Barr virus, cytomegalovirus, herpes simplex viruses, influenza A and B viruses, and hepatitis C virus in frozen endomyocardial samples. Of these patients, 15 (9.6%) showed angiographic evidence of single or multiple LV microaneurysms. All 15 patients had recurrent episodes of ventricular tachycardia with right bundle-branch block morphology, and the arrhythmias originated within or close to the aneurysms in those patients (n=6) undergoing ventricular mapping. A lymphocytic myocarditis was observed in LV biopsies of all patients and in the right ventricles of 3 patients. Polymerase chain reaction analysis was performed in 12 and viral genomes were found in 5 (42%): hepatitis C virus in 2, enterovirus in 2, and influenza virus A in 1. The patients were treated with antiarrhythmics, and cardiac function was preserved for the next 47+/-39.5 months of follow-up. No major clinical event was registered, and arrhythmias were successfully treated by antiarrhythmics.

CONCLUSIONS

Inflammatory LV microaneurysms, often of viral origin, are a consistent cause of apparently idiopathic ventricular arrhythmias. Their prognosis so far has been benign, and aggressive therapeutic strategies have been unnecessary.

[Hypertrophic cardiomyopathy and viral, idiopathic myopericarditis]

Among 64 patients followed up for 3 to 24 years after acute viral or idiopathic myopericarditis 10 patients were found to have hypertrophic cardiomyopathy. At echo-CG they had asymmetric hypertrophy of the septum. Manifestations of acute myopericarditis, results of laboratory and functional investigations are presented. Hypertrophic cardiomyopathy runs asymptomatically or with few symptoms. The relations between cardiomyopathy and viral infection are discussed.

[Pathogen detection in the myocardial lesion using in situ RT-PCR in mice induced by experimental CoxB(3m) virus infection]

OBJECTIVE

To detect the location of pathogens in myocardium using in situ RT-PCR technique in order to study the pathogenetic course of the myocardial lesion induced by CoxB(3m) virus infection in mice.

METHODS

(1) Thirty and fifty Balb/c mice were used respectively to establish the acute and chronic CoxB(3m) infected models, with another 25 healthy mice as the controls; (2) KS400 image analysis system (Germany) was used to measure the cardiac chamber area and the left ventricular wall thickness of the chronic infected mice and the controls; (3) CoxB(3m) virus in myocardial tissue was detected using in situ RT-PCR by direct incorporated technique which employed nucleotide labeling by anti-digoxin antibody and bonded with alkaline phosphatase (anti-dig-AKP method).

RESULTS

Picture analysis indicated that the left ventricular chamber area was enlarged and the left ventricular wall was thinner in the chronic repeated virus infected models than those of the controls. With in situ RT-PCR, positive signals for Coxsackie virus B(3m) RNA were detected not only in the myocardium of the acute Balb/c mice models but also in the myocardium of the chronic mice models.

CONCLUSION

Coxsackie virus B(3m) is able to induce pathologic lesions by exhibiting positive CVB-RNA signals in both acute and chronic models in mice. In the chronic experimental models, the cardiac chamber is enlarged while the ventricular wall is thinned which demonstrates the association with persistent infection of Coxsackie virus B(3m) virus.

Effect of coxsackievirus b3 on ion channel currents in rat ventricular myocytes

OBJECTIVE

To investigate the effects of coxsackievirus B3(CVB3) on ion channel currents in rat ventricular myocytes.

METHODS

Rat hearts were isolated with collagenase to acquire single ventricular myocytes, L-type voltage-dependent calcium channel (VDCC) current (I(Ca)), Na+ current (I(Na)), outward potassium current (I(out)), inwardly rectifying potassium current(I(KI)) were recorded using whole cell patch clamp techniques.

RESULTS

CVB3 infection increased I(Ca) and I(out), while decreased I(KI); but it had no obvious effect on I(Na).

CONCLUSION

The effects of CVB3 an I(Ca), I(out), I(KI) may be one of the mechanisms of myocytes damage and the occurrence of abnormal electroactivities induced by CVB3 infection.

Requirement of type III TGF-beta receptor for endocardial cell transformation in the heart

Transforming growth factor-beta (TGF-beta) signaling is mediated by a complex of type I (TBRI) and type II (TBRII) receptors. The type III receptor (TBRIII) lacks a recognizable signaling domain and has no clearly defined role in TGF-beta signaling. Cardiac endothelial cells that undergo epithelial-mesenchymal transformation express TBRIII, and here TBRIII-specific antisera were found to inhibit mesenchyme formation and migration in atrioventricular cushion explants. Misexpression of TBRIII in nontransforming ventricular endothelial cells conferred transformation in response to TGF-beta2. These results support a model where TBRIII localizes transformation in the heart and plays an essential, nonredundant role in TGF-beta signaling.

Regulation of chamber-specific gene expression in the developing heart by Irx4

The vertebrate heart consists of two types of chambers, the atria and the ventricles, which differ in their contractile and electrophysiological properties. Little is known of the molecular mechanisms by which these chambers are specified during embryogenesis. Here a chicken iroquois-related homeobox gene, Irx4, was identified that has a ventricle-restricted expression pattern at all stages of heart development. Irx4 protein was shown to regulate the chamber-specific expression of myosin isoforms by activating the expression of the ventricle myosin heavy chain-1 (VMHC1) and suppressing the expression of the atrial myosin heavy chain-1 (AMHC1) in the ventricles. Thus, Irx4 may play a critical role in establishing chamber-specific gene expression in the developing heart.

Microglial nodular encephalitis and ventriculoencephalitis due to cytomegalovirus infection in patients with AIDS: two distinct clinical patterns

In patients with AIDS, cerebral infection due to cytomegalovirus (CMV) results in two distinct neuropathological patterns: microglial nodular encephalitis (MGNE) and ventriculoencephalitis (VE). In order to identify clinical features to facilitate the differential diagnosis of these two forms of CMV encephalopathy in living patients, we retrospectively reviewed the clinical records of 18 patients with MGNE or VE diagnosed at autopsy. We identified the following clinical features as distinguishing the two encephalopathies: (1) MGNE manifests earlier than VE; (2) the onset of MGNE is acute, whereas the onset of VE is insidious; (3) the onset of MGNE is marked by confusion and delirium, which do not occur in VE; (4) VE is frequently associated with radiculopathy, which is absent in MGNE; and (5) VE is associated with more marked alterations in cerebrospinal fluid (high protein levels and pleocytosis). The early neurological manifestations of MGNE should prompt a search for systemic CMV infection, which may lead to earlier treatment.

Stability of the contractile assembly and Ca2+-activated tension in adenovirus infected adult cardiac myocytes

Adenovirus-mediated gene transfer into adult cardiac myocytes in primary culture is a potentially useful method to study the structure and function of the contractile apparatus. However, the consequences of adenovirus infection on the highly differentiated state of the cultured myocyte have not been determined. We report here a detailed analysis of myofilament structure and function over time in primary culture and after adenovirus infection. Adult rat ventricular myocytes in primary culture were infected with a recombinant adenovirus vector expressing either the LacZ or alkaline phosphatase reporter gene. Control and infected myocytes were collected at days 0-7 post-isolation/infection, and myofilament isoform expression was determined by SDS-PAGE and Western blot. Laser scanning densitometry showed that the alpha- to beta-myosin heavy chain ratio, the stoichiometry of the myosin light chains and the expression of the adult troponin T isoform did not change over time in culture or with adenovirus treatment. Importantly, examination of Ca2+-activated tension in single myocytes showed no change in the shape or position of the tension-pCa relationship in the control and adenovirus infected myocytes during primary culture. These results indicate that the structure and function of adult cardiac myocytes are stable in short term primary culture and are not affected by adenovirus infection per se, and therefore provide the foundation for the use of adenovirus-mediated myofilament gene transfer to study contractile apparatus structure and function in adult cardiac myocytes.

Primary cardiac lymphoma. No evidence for an etiologic association with Epstein-Barr virus

OBJECTIVES

To report two cases of primary cardiac lymphoma, a rare extranodal lymphoma with an unknown pathogenesis, and to compare them to secondary B-cell cardiac lymphoma.

DESIGN

Clinicopathologic features are described, using histologic and immunophenotypic examinations. The Epstein-Barr virus genome is detected by in situ hybridization.

PATIENTS

Of 80 autopsied cases of malignant lymphoma identified at Nagoya (Japan) University Hospital, two patients with primary cardiac lymphoma and five patients with secondary cardiac B-cell lymphoma were selected.

RESULTS

None of the seven selected cases showed immunodeficiency, autoimmune disorders, or chronic inflammatory processes. Primary cardiac lymphomas had B-cell phenotypes with mu and lambda chain monoclonality. Immunostaining for Epstein-Barr virus (latent membrane protein-1) and Epstein-Barr virus-encoded RNA-1 in situ hybridization did not demonstrate an association of these lymphoma with Epstein-Barr virus infection. The majority of secondary cardiac B-cell lymphomas were extranodal lymphomas and extranodal or serosal involvement was more prominent than nodal involvement.

CONCLUSION

These findings suggest that primary cardiac lymphoma, unlike pyothorax-associated pleural lymphoma, appears to have no association with chronic inflammation or Epstein-Barr virus infection.