ISG15 blocks cardiac glycolysis and ensures sufficient mitochondrial energy production during Coxsackievirus B3 infection

AIMS

Virus infection triggers inflammation and, may impose nutrient shortage to the heart. Supported by type I interferon (IFN) signalling, cardiomyocytes counteract infection by various effector processes, with the IFN-stimulated gene of 15 kDa (ISG15) system being intensively regulated and protein modification with ISG15 protecting mice Coxsackievirus B3 (CVB3) infection. The underlying molecular aspects how the ISG15 system affects the functional properties of respective protein substrates in the heart are unknown.

METHODS AND RESULTS

Based on the protective properties due to protein ISGylation, we set out a study investigating CVB3-infected mice in depth and found cardiac atrophy with lower cardiac output in ISG15-/- mice. By mass spectrometry, we identified the protein targets of the ISG15 conjugation machinery in heart tissue and explored how ISGylation affects their function. The cardiac ISGylome showed a strong enrichment of ISGylation substrates within glycolytic metabolic processes. Two control enzymes of the glycolytic pathway, hexokinase 2 (HK2) and phosphofructokinase muscle form (PFK1), were identified as bona fide ISGylation targets during infection. In an integrative approach complemented with enzymatic functional testing and structural modelling, we demonstrate that protein ISGylation obstructs the activity of HK2 and PFK1. Seahorse-based investigation of glycolysis in cardiomyocytes revealed that, by conjugating proteins, the ISG15 system prevents the infection-/IFN-induced up-regulation of glycolysis. We complemented our analysis with proteomics-based advanced computational modelling of cardiac energy metabolism. Our calculations revealed an ISG15-dependent preservation of the metabolic capacity in cardiac tissue during CVB3 infection. Functional profiling of mitochondrial respiration in cardiomyocytes and mouse heart tissue by Seahorse technology showed an enhanced oxidative activity in cells with a competent ISG15 system.

CONCLUSION

Our study demonstrates that ISG15 controls critical nodes in cardiac metabolism. ISG15 reduces the glucose demand, supports higher ATP production capacity in the heart, despite nutrient shortage in infection, and counteracts cardiac atrophy and dysfunction.

Fast Track Adaptation of Oncolytic Coxsackie B3 Virus to Resistant Colorectal Cancer Cells - a Method to Personalize Virotherapy

BACKGROUND

The efficacy of oncolytic viruses (OV) in cancer treatment depends on their ability to successfully infect and destroy tumor cells. However, patients' tumors vary, and in the case of individual insensitivity to an OV, therapeutic efficacy is limited. Here, we present a protocol for rapid generation of tumor cell-specific adapted oncolytic coxsackievirus B3 (CVB3) with enhanced oncolytic potential and a satisfactory safety profile. This is achieved by combining directed viral evolution (DVE) with genetic modification of the viral genome and the use of a microRNA-dependent regulatory tool.

METHODS

The oncolytic CVB3 variant PD-H was adapted to the refractory colorectal carcinoma cell line Colo320 through serial passaging. XTT assays and virus plaque assays were used to determine virus cytotoxicity and virus replication in vitro. Recombinant PD-H variants were generated through virus mutagenesis. Apoptosis was detected by Western blots, Caspase 3/7 assays, and DAPI staining. The therapeutic efficacy and safety of the adapted recombinant OV PD-SK-375TS were assessed in vivo using a subcutaneous Colo320 xenograft mouse model.

RESULTS

PD-H was adapted to the colorectal cancer cell line Colo320 within 10 passages. Sequencing of passage 10 virus P-10 revealed a heterogenous virus population with five nucleotide mutations resulting in amino acid substitutions. The genotypically homogeneous OV PD-SK was generated by inserting the five detected mutations of P-10 into the genome of PD-H. PD-SK showed significantly stronger replication and cytotoxicity than PD-H in Colo320 cells, but not in other colorectal carcinoma cell lines. Increase of apoptosis induction was detected as key mechanisms of Colo320 cell-specific adaptation of PD-SK. For in vivo safety PD-SK was engineered with target sites of the miR-375 (miR-375TS) to exclude virus replication in normal tissues. PD-SK-375TS, unlike the PD-H-375TS not adapted homolog suppressed the growth of subcutaneous Colo320 tumors in nude mice without causing any side effects.

CONCLUSION

Taken together, here we present an optimized protocol for the rapid generation of tumor cell-specific adapted oncolytic CVB3 based on the oncolytic CVB3 strain PD-H. The protocol is promising for the generation of personalized OV for tumor therapy and has the potential to be applied to other OV.

Transthyretin amyloid cardiomyopathy among patients with heart failure and preserved ejection fraction: the AMY score

AIMS

Transthyretin 'wild-type' amyloid cardiomyopathy (ATTRwt-CM) is a differential diagnosis of heart failure with preserved ejection fraction (HFpEF). The clinical work-up for ATTRwt-CM is challenging. Considering a combination of clinical variables specific for ATTRwt-CM might aid in identifying patients at risk.

METHODS AND RESULTS

Sixty patients (78 ± 6 years, 8% female) were diagnosed with ATTRwt-CM by endomyocardial biopsy. Preserved ejection fraction (LVEF >45%) was present in 41 of the patients. Those were 1:1 propensity score age- and sex-matched to a cohort of patients with HFpEF. ATTRwt-CM patients had less obesity (P = 0.01) and higher septal thickness (IVSd, P < 0.01) as well as more diastolic dysfunction (E/e', P < 0.01). On multivariable regression IVSd > 14 mm, E/e' > 14 and absence of obesity (P > 0.01 for all) were identified as predictors for ATTRwt-CM. A weighted point-based score was derived with IVSd > 14 mm = 1 point; absence of obesity = 2 points; and E/e' > 14 = 3 points. Area under the curve (AUC) for the summation score was 0.91 (0.84-0.97, P < 0.01) and a score of more than 3 points predicted ATTRwt-CM with good sensitivity (78%) and specificity (90%). The score was validated in an external cohort of 142 patients with ATTRwt-CM and 419 HFpEF patients showing sufficient accuracy (AUC 0.91, 0.88-0.94, P < 0.01). A value greater than 3 points demonstrated a high sensitivity (93%) and a negative predictive value of 97%.

CONCLUSIONS

A score based on basic clinical and echocardiographic features helps to distinguish ATTRwt-CM from typical HFpEF. This could facilitate the diagnostic work-up for these patients and enable earlier disease screening on a large scale.

The inflammatory spectrum of cardiomyopathies

Infiltration of the myocardium with various cell types, cytokines and chemokines plays a crucial role in the pathogenesis of cardiomyopathies including inflammatory cardiomyopathies and myocarditis. A more comprehensive understanding of the precise immune mechanisms involved in acute and chronic myocarditis is essential to develop novel therapeutic approaches. This review offers a comprehensive overview of the current knowledge of the immune landscape in cardiomyopathies based on etiology. It identifies gaps in our knowledge about cardiac inflammation and emphasizes the need for new translational approaches to improve our understanding thus enabling development of novel early detection methods and more effective treatments.

TF-FVIIa PAR2-β-Arrestin in Mouse Signaling Sustains Organ Dysfunction in Coxsackievirus B3 Infection

BACKGROUND

Accumulating evidence implicates the activation of G-protein-coupled PARs (protease-activated receptors) by coagulation proteases in the regulation of innate immune responses.

METHODS

Using mouse models with genetic alterations of the PAR2 signaling platform, we have explored contributions of PAR2 signaling to infection with coxsackievirus B3, a single-stranded RNA virus provoking multiorgan tissue damage, including the heart.

RESULTS

We show that PAR2 activation sustains correlates of severe morbidity-hemodynamic compromise, aggravated hypothermia, and hypoglycemia-despite intact control of the virus. Following acute viral liver injury, canonical PAR2 signaling impairs the restoration process associated with exaggerated type I IFN (interferon) signatures in response to viral RNA recognition. Metabolic profiling in combination with proteomics of liver tissue shows PAR2-dependent reprogramming of liver metabolism, increased lipid droplet storage, and gluconeogenesis. PAR2-sustained hypodynamic compromise, reprograming of liver metabolism, as well as imbalanced IFN responses are prevented in β-arrestin coupling-deficient PAR2 C-terminal phosphorylation mutant mice. Thus, wiring between upstream proteases and immune-metabolic responses results from biased PAR2 signaling mediated by intracellular recruitment of β-arrestin. Importantly, blockade of the TF (tissue factor)-FVIIa (coagulation factor VIIa) complex capable of PAR2 proteolysis with the NAPc2 (nematode anticoagulant protein c2) mitigated virus-triggered pathology, recapitulating effects seen in protease cleavage-resistant PAR2 mice.

CONCLUSIONS

These data provide insights into a TF-FVIIa signaling axis through PAR2-β-arrestin coupling that is a regulator of inflammation-triggered tissue repair and hemodynamic compromise in coxsackievirus B3 infection and can potentially be targeted with selective coagulation inhibitors.

Case Report: Sudden very late-onset near fatal PD1 inhibitor-associated myocarditis with out-of-hospital cardiac arrest after >2.5 years of pembrolizumab treatment

Introduction

Immune checkpoint inhibitors have advanced the outcomes of many different types of cancer. A rare but extraordinarily severe complication of these agents resembles immune checkpoint inhibitor-related myocarditis, which typically occurs within the first few weeks after treatment initiation with a mortality of 25%-50%.

Case report

A 57-year-old woman had uneventfully received pembrolizumab for metastatic non-small cell lung cancer for over 2.5 years and was admitted after an out-of-hospital cardiac arrest due to ventricular fibrillation. After successful cardiopulmonary resuscitation, the initial diagnostic work-up showed elevated cardiac enzymes and a limited left-ventricular ejection fraction, while coronary angiography did not show relevant stenosis. Despite cardiac MRI being unsuggestive of myocarditis, myocardial biopsies were obtained and histologically confirmed anti-PD-1 antibody-associated myocarditis. After the initiation of prednisone at 1 mg/kg body weight, the patient gradually recovered and was discharged three weeks later with markedly improved cardiac function.

Conclusion

This case resembles the first description of a very late onset irMyocarditis, occurring over 2.5 years after the start of treatment. It demonstrates the importance of contemplating that severe immune-related toxicities with a sudden onset clinical presentation may occur even after long uneventful periods of anti-PD-1 immune checkpoint inhibitor treatment. Furthermore, it underlines the critical importance of myocardial biopsies in this setting, especially when cardiac MRI remains inconclusive. Moreover, it demonstrates the necessity and benefits of early immunosuppressive treatment if immune-related myocarditis is considered a differential diagnosis.

Right heart and left atrial strain to differentiate cardiac amyloidosis and Fabry disease

Echocardiographic differentiation of cardiac amyloidosis (CA) and Fabry disease (FD) is often challenging using standard echocardiographic parameters. We retrospectively analyzed the diagnostic accuracy of right heart and left atrial strain parameters to discriminate CA from FD using receiver operating characteristic curve analyses and logistic regression models. A total of 47 FD and 88 CA patients with left ventricular wall thickening were analyzed. The comparison of both cardiomyopathies revealed significantly reduced global and free wall longitudinal right ventricular strain (RVS; global RVS: CA - 13 ± 4%, n = 67, vs. FD - 18 ± 4%, n = 39, p < 0.001) as well as right atrial strain (RAS; reservoir RAS: CA 12 ± 8%, n = 70, vs. FD 26 ± 9%, n = 40, p < 0.001) and left atrial strain (LAS) in CA patients. Individually, global RVS as well as phasic LAS and RAS showed the highest diagnostic accuracy to distinguish CA and FD. The best diagnostic accuracy was achieved by combining the age, basal RV diameter, global RVS, and reservoir and conduit RAS (area under the curve 0.96 [95% CI 0.90-1.00]). Differential echocardiographic diagnostic work-up of patients with suspected CA or FD can be improved by integrating structural and functional parameters of the right heart and the left atrium.Trial registration: DRKS00027403.

Clinical course and follow-up of pediatric patients with COVID-19 vaccine-associated myocarditis compared to non-vaccine-associated myocarditis within the prospective multicenter registry-"MYKKE"

BACKGROUND

Since the onset of widespread COVID-19 vaccination, increased incidence of COVID-19 vaccine-associated myocarditis (VA-myocarditis) has been noted, particularly in male adolescents.

METHODS

Patients <18 years with suspected myocarditis following COVID-19 vaccination within 21 days were enrolled in the PedMYCVAC cohort, a substudy within the prospective multicenter registry for pediatric myocarditis "MYKKE." Clinical data at initial admission, 3- and 9-months follow-up were monitored and compared to pediatric patients with confirmed non-vaccine-associated myocarditis (NVA-myocarditis) adjusting for various baseline characteristics.

RESULTS

From July 2021 to December 2022, 56 patients with VA-myocarditis across 15 centers were enrolled (median age 16.3 years, 91% male). Initially, 11 patients (20%) had mildly reduced left ventricular ejection fraction (LVEF; 45%-54%). No incidents of severe heart failure, transplantation or death were observed. Of 49 patients at 3-months follow-up (median (IQR) 94 (63-118) days), residual symptoms were registered in 14 patients (29%), most commonly atypical intermittent chest pain and fatigue. Diagnostic abnormalities remained in 23 patients (47%). Of 21 patients at 9-months follow-up (259 (218-319) days), all were free of symptoms and diagnostic abnormalities remained in 9 patients (43%). These residuals were mostly residual late gadolinium enhancement in magnetic resonance imaging. Patients with NVA-myocarditis (n=108) more often had symptoms of heart failure (P = .003), arrhythmias (P = .031), left ventricular dilatation (P = .045), lower LVEF (P < .001) and major cardiac adverse events (P = .102).

CONCLUSIONS

Course of COVID-19 vaccine-associated myocarditis in pediatric patients seems to be mild and differs from non-vaccine-associated myocarditis. Due to a considerable number of residual symptoms and diagnostic abnormalities at follow-up, further studies are needed to define its long-term implications.

CYP19A1 mediates severe SARS-CoV-2 disease outcome in males

Male sex represents one of the major risk factors for severe COVID-19 outcome. However, underlying mechanisms that mediate sex-dependent disease outcome are as yet unknown. Here, we identify the CYP19A1 gene encoding for the testosterone-to-estradiol metabolizing enzyme CYP19A1 (also known as aromatase) as a host factor that contributes to worsened disease outcome in SARS-CoV-2-infected males. We analyzed exome sequencing data obtained from a human COVID-19 cohort (n = 2,866) using a machine-learning approach and identify a CYP19A1-activity-increasing mutation to be associated with the development of severe disease in men but not women. We further analyzed human autopsy-derived lungs (n = 86) and detect increased pulmonary CYP19A1 expression at the time point of death in men compared with women. In the golden hamster model, we show that SARS-CoV-2 infection causes increased CYP19A1 expression in the lung that is associated with dysregulated plasma sex hormone levels and reduced long-term pulmonary function in males but not females. Treatment of SARS-CoV-2-infected hamsters with a clinically approved CYP19A1 inhibitor (letrozole) improves impaired lung function and supports recovery of imbalanced sex hormones specifically in males. Our study identifies CYP19A1 as a contributor to sex-specific SARS-CoV-2 disease outcome in males. Furthermore, inhibition of CYP19A1 by the clinically approved drug letrozole may furnish a new therapeutic strategy for individualized patient management and treatment.

Dilated cardiomyopathy: causes, mechanisms, and current and future treatment approaches

Dilated cardiomyopathy is conventionally defined as the presence of left ventricular or biventricular dilatation or systolic dysfunction in the absence of abnormal loading conditions (eg, primary valve disease) or significant coronary artery disease sufficient to cause ventricular remodelling. This definition has been recognised as overly restrictive, as left ventricular hypokinesis without dilation could be the initial presentation of dilated cardiomyopathy. The causes of dilated cardiomyopathy comprise genetic (primary dilated cardiomyopathy) or acquired factors (secondary dilated cardiomyopathy). Acquired factors include infections, toxins, cancer treatment, endocrinopathies, pregnancy, tachyarrhythmias, and immune-mediated diseases. 5-15% of patients with acquired dilated cardiomyopathy harbour a likely pathogenic or pathogenic gene variant (ie, gene mutation). Therefore, the diagnostic tests and therapeutic approach should always consider both genetic and acquired factors. This Seminar will focus on the current multidimensional diagnostic and therapeutic approach and discuss the underlying pathophysiology that could drive future treatments aiming to repair or replace the existing gene mutation, or target the specific inflammatory, metabolic, or pro-fibrotic drivers of genetic or acquired dilated cardiomyopathy.

Unicentric Castleman's disease associated with malignant cardiac Amyloid-A amyloidosis: a case report

Background

Unicentric Castleman's disease (UCD), a lymphoproliferative disorder characterized by enlargement of the lymph nodes, is a rare cause of Amyloid-A amyloidosis. While patients usually present with impaired kidney function and proteinuria, heart involvement is neither common nor the main cause of signs and symptoms.

Case summary

We present a patient who was admitted to the hospital for impaired exercise capacity. Diagnostic work-up revealed severe left ventricular hypertrophy suggestive of cardiac amyloidosis. Although Congo red staining of endomyocardial biopsies was initially negative, subsequent immunohistochemical staining against serum amyloid A finally confirmed the diagnosis of cardiac amyloidosis. 18F-fluorodeoxyglucose positron emission tomography/computed tomography revealed a tumour located in dorsal of the duodenum. Fine-needle aspiration biopsy of the tumour was suggestive but could not confirm the presence of UCD beyond reasonable doubt. Rapid worsening of heart failure symptoms warranted urgent surgical tumourectomy, which resulted in immediate post-operative lowering of serum amyloid protein. However, post-operative cardiogenic shock could not be stabilized even with veno-arterial extracorporeal membrane oxygenation, and the patient eventually died. The UCD of the hyaline vascular (HV) subtype was confirmed by pathologic work-up of the excised tumour.

Discussion

This case report presents for the first time a patient with malignant cardiac Amyloid-A amyloidosis caused by unicentric Castleman's disease of the HV subtype. Since the disease progresses swiftly, rapid diagnosis is essential for potential curative treatment.

Endomyocardial substrate of ventricular arrhythmias in patients with autoimmune rheumatic diseases

INTRODUCTION

Delayed enhancement-magnetic resonance imaging (DE-MRI) has demonstrated that nonischemic cardiomyopathy is mainly characterized by intramural or epicardial fibrosis whereas global endomyocardial fibrosis suggests cardiac involvement in autoimmune rheumatic diseases or amyloidosis. Conduction disorders and sudden cardiac death are important manifestations of autoimmune rheumatic diseases with cardiac involvement but the substrates of ventricular arrhythmias in autoimmune rheumatic diseases have not been fully elucidated.

METHODS AND RESULTS

20 patients with autoimmune rheumatic diseases presenting with ventricular tachycardia (VT) (n = 11) or frequent ventricular extrasystoles (n = 9) underwent DE-MRI and/or endocardial electroanatomical mapping of the left ventricle (LV). Ten patients with autoimmune rheumatic diseases underwent VT ablation. Global endomyocardial fibrosis without myocardial thickening and unrelated to coronary territories was detected by DE-MRI or electroanatomical voltage mapping in 9 of 20 patients with autoimmune rheumatic diseases. In the other patients with autoimmune rheumatic diseases, limited regions of predominantly epicardial (n = 4) and intramyocardial (n = 5) fibrosis or only minimal fibrosis (n = 2) were found using DE-MRI. Endocardial low-amplitude diastolic potentials and pre-systolic Purkinje or fascicular potentials, mostly within fibrotic areas, were identified as the targets of successful VT ablation in 7 of 10 patients with autoimmune rheumatic diseases.

CONCLUSION

Global endomyocardial fibrosis can be a tool to diagnose severe cardiac involvement in autoimmune rheumatic diseases and may serve as the substrate of ventricular arrhythmias in a substantial part of patients.

Blood taken immediately after fatal resuscitation attempts yields higher quality DNA for genetic studies as compared to autopsy samples

BACKGROUND

The out-of-hospital cardiac arrest (OHCA) in the young may be associated with a genetic predisposition which is relevant even for genetic counseling of relatives. The identification of genetic variants depends on the availability of intact genomic DNA. DNA from autopsy may be not available due to low autopsy frequencies or not suitable for high-throughput DNA sequencing (NGS). The emergency medical service (EMS) plays an important role to save biomaterial for subsequent molecular autopsy. It is not known whether the DNA integrity of samples collected by the EMS is better suited for NGS than autopsy specimens.

MATERIAL AND METHODS

DNA integrity was analyzed by standardized protocols. Fourteen blood samples collected by the EMS and biomaterials from autopsy were compared. We collected 172 autopsy samples from different tissues and blood with postmortem intervals of 14-168 h. For comparison, DNA integrity derived from blood stored under experimental conditions was checked against autopsy blood after different time intervals.

RESULTS

DNA integrity and extraction yield were higher in EMS blood compared to any autopsy tissue. DNA stability in autopsy specimens was highly variable and had unpredictable quality. In contrast, collecting blood samples by the EMS is feasible and delivered comparably the highest DNA integrity.

CONCLUSIONS

Isolation yield and DNA integrity from blood samples collected by the EMS is superior in comparison to autopsy specimens. DNA from blood samples collected by the EMS on scene is stable at room temperature or even for days at 4 °C. We conclude that the EMS personnel should always save a blood sample of young fatal OHCA cases died on scene to enable subsequent genetic analysis.

Impact of P-selectin-PSGL-1 Axis on Platelet-Endothelium-Leukocyte Interactions in Fatal COVID-19

In critically ill patients infected with SARS-CoV-2, early leukocyte recruitment to the respiratory system was found to be orchestrated by leukocyte trafficking molecules accompanied by massive secretion of proinflammatory cytokines and hypercoagulability. Our study aimed to explore the interplay between leukocyte activation and pulmonary endothelium in different disease stages of fatal COVID-19. Our study comprised 10 COVID-19 postmortem lung specimens and 20 control lung samples (5 acute respiratory distress syndrome, 2 viral pneumonia, 3 bacterial pneumonia, and 10 normal), which were stained for antigens representing the different steps of leukocyte migration: E-selectin, P-selectin, PSGL-1, ICAM1, VCAM1, and CD11b. Image analysis software QuPath was used for quantification of positive leukocytes (PSGL-1 and CD11b) and endothelium (E-selectin, P-selectin, ICAM1, VCAM1). Expression of IL-6 and IL-1β was quantified by RT-qPCR. Expression of P-selectin and PSGL-1 was strongly increased in the COVID-19 cohort compared with all control groups (COVID-19:Controls, 17:23, P < .0001; COVID-19:Controls, 2:75, P < .0001, respectively). Importantly, P-selectin was found in endothelial cells and associated with aggregates of activated platelets adherent to the endothelial surface in COVID-19 cases. In addition, PSGL-1 staining disclosed positive perivascular leukocyte cuffs, reflecting capillaritis. Moreover, CD11b showed a strongly increased positivity in COVID-19 compared with all controls (COVID-19:Controls, 2:89; P = .0002), indicating a proinflammatory immune microenvironment. Of note, CD11b exhibited distinct staining patterns at different stages of COVID-19 disease. Only in cases with very short disease course, high levels of IL-1β and IL-6 mRNA were observed in lung tissue. The striking upregulation of PSGL-1 and P-selectin reflects the activation of this receptor-ligand pair in COVID-19, increasing the efficiency of initial leukocyte recruitment, thus promoting tissue damage and immunothrombosis. Our results show that endothelial activation and unbalanced leukocyte migration play a central role in COVID-19 involving the P-selectin-PSGL-1 axis.

Left Ventricular Physiology and Ventricular-Vascular Interactions in Young Patients After Heart Transplantation

Background In patients after heart transplantation, systemic arterial hypertension and enhanced central aortic stiffness contribute to increased ventricular afterload, which might lead to graft dysfunction. The aim of our study was to characterize systemic arterial elastance and its impact on left ventricular function and ventriculo-arterial coupling in a cohort of children, adolescents, and young adults after heart transplantation using invasive conductance catheter technique. Methods and Results Thirty patients who had heart transplants (age, 20.0±6.5 years, 7 female) underwent invasive cardiac catheterization including pressure-volume loop analysis. Load-independent parameters of systolic (ventricular elastance [Ees]) and diastolic (ventricular compliance) function as well as systemic arterial elastance (Ea, end-systolic pressure/stroke volume) and ventriculo-arterial coupling (Ea/Ees) were assessed at baseline level and during dobutamine infusion (10 μg/kg/min). Ees showed an appropriate increase under inotropic stimulation from 0.43 (0.11-2.52) to 1.00 (0.20-5.10) mm Hg/mL/m² (P<0.0001), whereas ventricular compliance remained rather unchanged (0.16±0.10 mm Hg/mL/m² to 0.12±0.07 mm Hg/mL/m²; P=0.10). Ventriculo-arterial coupling Ea/Ees was abnormal at rest and did not improve significantly under dobutamine (1.7 [0.6-6.7] to 1.3 [0.5-4.9], P=0.70) due to a simultaneous rise in Ea from 0.71 (0.37-2.82) to 1.10 (0.52-4.03) mm Hg/mL/m² (P<0.0001). Both Ees and ventricular compliance were significantly associated with Ea at baseline and under dobutamine infusion. Conclusions Patients who underwent heart transplantation show impaired ventriculo-arterial coupling at rest and under inotropic stimulation despite preserved left ventricular contractile reserve. An abnormal response in vascular function resulting in increased afterload seems to represent an important factor that may play a role for the development of late graft failure.

Acute Lymphocytic Myocarditis in a Young Male Post-COVID-19

Background

Lymphocytic myocarditis is a rare form of myocarditis, associated with a high mortality rate due to a high risk of sudden cardiac death. Lymphocytic myocarditis might present as a relevant extrapulmonary manifestation after coronavirus disease 2019 (COVID-19) infection. Case presentation. We report a case of a 26-year-old male with lymphocytic myocarditis, presenting with a 1-month history of increasing fatigue, palpitations, and shortness of breath. Eight weeks before, he was tested positive for SARS-CoV-2. He had received 2-dose schedule of the COVID-19 mRNA vaccine Comirnaty® (BioNTech/Pfizer) 6 months prior to his admission. Diagnostic work-up by echocardiography and cardiac magnetic resonance (CMR) imaging demonstrated a severely reduced left ventricular function and a strong midmyocardial late gadolinium enhancement (LGE). Histology and immunohistology of the endomyocardial biopsies revealed an acute lymphocytic myocarditis. Immunosuppressive therapy with a steroid taper in combination with azathioprine 300 mg/day was initiated. The patient was equipped with a LifeVest®. On day 17, a non-sustained ventricular tachycardia was documented. Follow-up CMR imaging after 3 months showed a slightly improved systolic left ventricular function, and a strong LGE was still detectable.

Conclusions

The case highlights the significance of recognizing lymphocytic myocarditis correlated to COVID-19. It is important to be vigilant also of a later presentation of cardiomyopathy in patients diagnosed with COVID-19 due to high mortality without immediate support.

Lipid nanoparticle-encapsulated, chemically modified anti-adenoviral siRNAs inhibit hepatic adenovirus infection in immunosuppressed Syrian hamsters

RNA interference has demonstrated its potential as an antiviral therapy for treatment of human adenovirus (hAd) infections. The only existing viral vector-based system for delivery of anti-adenoviral artificial microRNAs available for in vivo use, however, has proven to be inefficient in therapeutic applications. In this study, we investigated the potential of stabilized small interfering RNA (siRNA) encapsulated in lipid nanoparticles (LNPs) for treatment of hepatic hAd serotype 5 (hAd5) infection in an hAd infection model using immunosuppressed Syrian hamsters. The siRNA sipTP_mod directed against the adenoviral pre-terminal protein (pTP) and containing 2'-O-methyl modifications as well as phosphorothioate linkages effectively inhibited hAd5 infection in vitro. In light of this success, sipTP_mod was encapsulated in LNPs containing the cationic lipid XL-10, which enables hepatocyte-specific siRNA transfer, and injected intravenously into hAd5-infected immunosuppressed Syrian hamsters. This resulted in a significant reduction of liver hAd5 titers, a trend toward reduced liver injury and inflammation, and reduction of viral titers in the blood and spleen compared with hAd5-infected animals that received a non-silencing siRNA. These effects were demonstrated in animals infected with low and moderate doses of hAd5. These data demonstrate that hepatic hAd5 infection can be successfully treated with anti-adenoviral sipTP_mod encapsulated in LNPs.

Commentary on why implementing and standardizing histologic diagnosis of myocarditis is crucial for the clinical setting and patient care

Histological examination of endomyocardial biopsy or myocardium at autopsy is key to the diagnosis of myocarditis. Among pathologists there is currently extensive variability in routine practice and criteria used to define, diagnose, and report myocarditis as well as to achieve consensus on cases. Two manuscripts emphasizing the need to standardize and implement histopathological diagnostic criteria for myocarditis are reviewed.

Leitlinie Myokarditis der Deutschen Gesellschaft für Pädiatrische Kardiologie

This consensus statement presents updated recommendations on diagnosis and treatment of myocarditis in childhood.

Pathophysiological Gaps, Diagnostic Challenges, and Uncertainties in Cardiac Sarcoidosis

Cardiac sarcoidosis can mimic any cardiomyopathy in different stages. Noncaseating granulomatous inflammation can be missed, because of the nonhomogeneous distribution in the heart. The current diagnostic criteria show discrepancies and are partly nonspecific and insensitive. Besides the diagnostic pitfalls, there are controversies in the understanding of the causes, genetic and environmental background, and the natural evolution of the disease. Here, we review the current pathophysiological aspects and gaps that are relevant for future cardiac sarcoidosis diagnostics and research.

Pathophysiological Mechanisms of Cardiac Dysfunction in Transgenic Mice with Viral Myocarditis

Viral myocarditis is pathologically associated with RNA viruses such as coxsackievirus B3 (CVB3), or more recently, with SARS-CoV-2, but despite intensive research, clinically proven treatment is limited. Here, by use of a transgenic mouse strain (TG) containing a CVB3ΔVP0 genome we unravel virus-mediated cardiac pathophysiological processes in vivo and in vitro. Cardiac function, pathologic ECG alterations, calcium homeostasis, intracellular organization and gene expression were significantly altered in transgenic mice. A marked alteration of mitochondrial structure and gene expression indicates mitochondrial impairment potentially contributing to cardiac contractile dysfunction. An extended picture on viral myocarditis emerges that may help to develop new treatment strategies and to counter cardiac failure.

Comprehensive analysis of SARS-CoV-2 receptor proteins in human respiratory tissues identifies alveolar macrophages as potential virus entry site

AIMS

COVID-19 has had enormous consequences on global health-care and has resulted in millions of fatalities. The exact mechanism and site of SARS-CoV-2 entry into the body remains insufficiently understood. Recently, novel virus receptors were identified, and alveolar macrophages were suggested as a potential viral entry cell type and vector for intra-alveolar virus transmission. Here, we investigated the protein expression of 10 well-known and novel virus entry molecules along potential entry sites in humans using immunohistochemistry.

METHODS AND RESULTS

Samples of different anatomical sites from up to 93 patients were incorporated into tissue microarrays. Protein expression of ACE2, TMPRSS2, furin, CD147, C-type lectin receptors (CD169, CD209, CD299), neuropilin-1, ASGR1 and KREMEN1 were analysed. In lung tissues, at least one of the three receptors ACE2, ASGR1 or KREMEN1 was expressed in the majority of cases. Moreover, all the investigated molecules were found to be expressed in alveolar macrophages, and co-localisation with SARS-CoV-2 N-protein was demonstrated using dual immunohistochemistry in lung tissue from a COVID-19 autopsy. While CD169 and CD209 showed consistent protein expression in sinonasal, conjunctival and bronchiolar tissues, neuropilin-1 and ASGR1 were mostly absent, suggesting a minor relevance of these two molecules at these specific sites.

CONCLUSION

Our results extend recent discoveries indicating a role for these molecules in virus entry at different anatomical sites. Moreover, they support the notion of alveolar macrophages being a potential entry cell for SARS-CoV-2.

Myocarditis and endomyocardial biopsy: achieving consensus diagnosis on 100 cases

The two histopathology benchmarks used to diagnose myocarditis are the Dallas Criteria, developed in 1984 and the European Society of Cardiology criteria, developed in 2013, which added immunohistochemistry for the detection of CD3+ T cells (lymphocytes) and CD68+ macrophages. Despite their near universal acceptance, the extent to which pathologists use these criteria or their own criteria to consistently render the diagnosis of myocarditis on endomyocardial biopsy (EMB) is unknown. We digitally scanned slides from 100 heart biopsies, including a trichrome stain and immunostaining, that were chosen as representative of myocarditis, non-myocarditis, and borderline myocarditis, as diagnosed per one institution's use of the Dallas Criteria. Eight blinded international cardiovascular experts were asked to render diagnoses and offer a confidence score on each case. No clinical histories were shared. There was full initial agreement across all experts on 37 cases (16 myocarditis and 21 non-myocarditis) and moderate consensus on 35 cases. After individual inquiries and group discussion, consensus was reached on 90 cases. Diagnostic confidence was highest among the myocarditis diagnoses, lowest for borderline cases, and significantly different between the three diagnostic categories (myocarditis, borderline myocarditis, non-myocarditis; P-value=8.49 × 10^-57; ANOVA). Diagnosing myocarditis, particularly in cases with limited inflammation and injury, remains a challenge even for experts in the field. Intermediate cases, termed "borderline" in the Dallas Criteria, represent those for which consensus is particularly hard to achieve. To increase consistency for the histopathologic diagnosis of myocarditis, we will need more specifically defined criteria, more granular descriptions of positive and negative features, clarity on how to incorporate immunohistochemistry findings, and improved nomenclature.

Systemic thrombo-embolic events in a middle-aged male with Loeffler endocarditis without peripheral eosinophilia-a case report

BACKGROUND

Loeffler-endocarditis (LE) is considered a chronic restrictive cardiomyopathy and manifestation of eosinophilic myocarditis characterized by eosinophilic infiltration. LE is a rare underdiagnosed disease and associated with high morbidity and mortality.

CASE PRESENTATION

We report a case of a 46-year-old man suffering from LE associated with thromboembolic events without peripheral eosinophilia. The patient presented with typical clinical signs of acute onset of limb ischaemia, predominantly on the right limb, indicating immediate iliacal thrombectomy and due to a severe compartment syndrome additional fasciotomy. Total occlusion also of left popliteal artery suggesting an impaired chronic and aggravated impaired perfusion indicated also urgent left sided revascularization. Subsequent echocardiography revealed severe left ventricular dysfunction with a striking amount of spontaneous echo-contrast, noticeable in the left ventricular cavity. Furthermore the initial CT scan demonstrated asymptomatic left kidney- and brain infarctions. Diagnostic workup including endomyocardial biopsy (EMB) of the left ventricle, uncovered an underlying LE without peripheral eosinophilia.

CONCLUSIONS

This case demonstrates and highlights the findings, treatment and outcome of a patient with LE and associated thrombo-embolic events without peripheral eosinophilia and emphazises the importance of awareness for LE in patients presenting with an acute cardiac decompensation and thrombo-embolic events. EMB should be performed early in unstable patients unsuitable for cardiovascular magnetic resonance imaging.