Persistent viral infections and their role in heart disease

New insights gained from cellular landscape changes in myocarditis and inflammatory cardiomyopathy

Advances in the etiological classification of myocarditis and inflammatory cardiomyopathy (ICM) have reached a consensus. However, the mechanism of myocarditis/ICM remains unclear, which affects the development of treatment and the improvement of outcome. Cellular transcription and metabolic reprogramming, and the interactions between cardiomyocytes and non-cardiomyocytes, such as the immune cells, contribute to the process of myocarditis/ICM. Recent efforts have been made by multi-omics techniques, particularly in single-cell RNA sequencing, to gain a better understanding of the cellular landscape alteration occurring in disease during the progression. This article aims to provide a comprehensive overview of the latest studies in myocarditis/ICM, particularly as revealed by single-cell sequencing.

Epidemiology of Adenovirus Infection in Hospitalized Children in the United States From 1997 to 2019

OBJECTIVE

The study aimed to explore the prevalence, clinical features, resource utilization, temporal trends and outcomes associated with adenoviral infections in hospitalized children.

METHODS

A retrospective analysis using the Healthcare Cost and Utilization Project's Kids' Inpatient Database from 1997 to 2019 was performed. Children 29 days to 17 years of age with adenoviral infection were selected. Chi-square, Kruskal-Wallis tests, linear trend analysis and multivariable analysis were used for data analysis.

RESULTS

A total of 40,135 children under 18 years of age with adenoviral infection were discharged in the United States with an overall prevalence of 18.9 per 10,000 discharges and 6.9 children per 100,000 population. By linear trend analysis, the hospitalization rate has significantly increased with the highest prevalence in 2019. Adenoviral infection was more prevalent in Black children, in winter months, in the Midwest region, in children with government insurance and in the lowest income quartile. The majority (85%) of adenovirus-related hospitalizations occurred under 6 years of age. Mechanical ventilation, extracorporeal membrane oxygenation support, acute kidney injury and liver failure were documented in 11.9%, 0.4%, 2.7% and 0.4%, respectively. The overall case fatality rate was 1.4%, which decreased from 1997 to 2019 ( P < 0.05). By regression analysis, an increased mortality rate was associated with the need for mechanical ventilation, the presence of complex chronic conditions, immune deficiency, central nervous system infection and pneumonia/bronchiolitis.

CONCLUSIONS

Most human adenovirus infections occur in children under 6 years of age and cause mild illness. Human adenovirus can lead to serious illness in children with complex chronic conditions and immune deficiency conditions.

Viral Myocarditis as a Factor Leading to the Development of Heart Failure Symptoms, Including the Role of Parvovirus B19 Infection-Systematic Review

Myocarditis (MC) is defined as an immunological inflammatory reaction with various etiologies, clinical presentations and prognoses within the myocardium. Currently, parvovirus B19 (PVB19) has become the main factor leading to this disease, replacing the previously dominant viruses A and B. In the case of chronic heart failure with subsequent dilated cardiomyopathy, approximately 67% have a viral etiology, and most of them are the result of PVB19 infection. However, the analysis showed a correlation between PVB19 infection and the risk of developing inflammatory dilated cardiomyopathy (DCMi). PVB19 is detected in 23% of patients with DCMi. Chronic infection may also contribute to progressive left ventricular failure in patients with a history of MC. The above effect suggests the active replication of PVB19 only in heart biopsies with inflammation due to MC or DCMi. Moreover, the supply of IFN-β to suppress the active transcription of PVB19 accompanied by DCMi over a period of 6 months results in the normalization of NT-proBNP and an improvement in LVEF along with NYHA performance. The small number of reports on this topic and inaccuracies resulting from constantly conducted research and ongoing changes make it impossible to clearly answer the question of whether PVB19 is a factor inducing de novo MC and DCM or only accompanies the above conditions. However, large clinical cohort studies lead to the perception of PVB19 as a viral etiological agent capable of causing de novo MC together with DCMi.

DNA Virome in Cardiac Tissue from Green Sea Turtles (Chelonia mydas) with Myocarditis

As part of a sea turtle health monitoring program on the central east coast of Queensland, Australia, stranded and sick green sea turtles (Chelonia mydas) were subjected to necropsy and histopathology. A subset of these turtles had myocarditis of varying severity, which could not be attributed to parasitism by spirorchid flukes or bacterial infections. We, therefore, undertook an investigation to determine whether virus infections might be part of the pathogenesis. Deep sequencing revealed abundant DNA virus contigs in the heart tissue, of which CRESS and circoviruses appeared to be the most consistently present. Further analysis revealed the homology of some of the circoviruses to the beak and feather disease virus. While a causative link to myocarditis could not be established, the presence of these viruses may play a contributing role by affecting the immune system and overall health of animals exposed to pollutants, higher water temperatures, and decreasing nutrition.

Global landscape of coxsackieviruses in human health

Coxsackieviruses-induced infections, particularly in infants and young children, are one of the most important public health issues in low- and middle-income countries, where the surveillance system varies substantially, and these manifestations have been disregarded. They are widespread throughout the world and are responsible for a broad spectrum of human diseases, from mildly symptomatic conditions to severe acute and chronic disorders. Coxsackieviruses (CV) have been found to have 27 identified genotypes, with overlaps in clinical phenotypes between genotypes. In this review, we present a concise overview of the most recent studies and findings of coxsackieviruses-associated disorders, along with epidemiological data that provides comprehensive details on the distribution, variability, and clinical manifestations of different CV types. We also highlight the significant roles that CV infections play in the emergence of neurodegenerative illnesses and their effects on neurocognition. The current role of CVs in oncolytic virotherapy is also mentioned. This review provides readers with a better understanding of coxsackieviruses-associated disorders and pointing the impact that CV infections can have on different organs with variable pathogenicity. A deeper knowledge of these infections could have implications in designing current surveillance and prevention strategies related to severe CVs-caused infections, as well as encourage studies to identify the emergence of more pathogenic types and the etiology of the most common and most severe disorders associated with coxsackievirus infection.

RNA sequencing provides novel insights into the pathogenesis of naturally occurring myxomatous mitral valve disease stage B1 in beagle dogs

Myxomatous mitral valve disease (MMVD) is the most common cardiovascular disorder in dogs with a high prevalence, accounting for approximately 75% of all canine heart disease cases. MMVD is a complex disease and shows variable progression from mild valve leakage to severe regurgitation, potentially leading to heart failure. However, the molecular mechanisms and age-related changes that govern disease progression, especially at the early stage (B1) before the development of discernable clinical signs, remain poorly understood. In this prospective study, we aimed to compare gene expression differences between blood samples of aged beagle dogs with stage B1 MMVD and those of healthy controls using RNA sequencing. Clinical evaluation was also conducted, which revealed minimal differences in radiographic and echocardiographic measurements despite distinct biomarker variations between the two groups. Comparative transcriptomics revealed differentially expressed genes associated with extracellular matrix remodeling, prostaglandin metabolism, immune modulation, and interferon-related pathways, which bear functional relevance for MMVD. In particular, the top 10 over- and under-expressed genes represent promising candidates for influencing pathogenic changes in MMVD stage B1. Our research findings, which include identified variations in clinical markers and gene expression, enhance our understanding of MMVD. Furthermore, they underscore the need for further research into early diagnosis and treatment strategies, as, to the best of our knowledge, no prior studies have explored the precise molecular mechanisms of stage B1 in MMVD through total RNA sequencing.

Viral DNAemia and DNA Virus Seropositivity and Mortality in Pediatric Sepsis

Importance

Sepsis is a leading cause of pediatric mortality. Little attention has been paid to the association between viral DNA and mortality in children and adolescents with sepsis.

Objective

To assess the association of the presence of viral DNA with sepsis-related mortality in a large multicenter study.

Design, Setting, and Participants

This cohort study compares pediatric patients with and without plasma cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus 1 (HSV-1), human herpesvirus 6 (HHV-6), parvovirus B19 (B19V), BK polyomavirus (BKPyV), human adenovirus (HAdV), and torque teno virus (TTV) DNAemia detected by quantitative real-time polymerase chain reaction or plasma IgG antibodies to CMV, EBV, HSV-1, or HHV-6. A total of 401 patients younger than 18 years with severe sepsis were enrolled from 9 pediatric intensive care units (PICUs) in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Collaborative Pediatric Critical Care Research Network. Data were collected from 2015 to 2018. Samples were assayed from 2019 to 2022. Data were analyzed from 2022 to 2023.

Main Outcomes and Measures

Death while in the PICU.

Results

Among the 401 patients included in the analysis, the median age was 6 (IQR, 1-12) years, and 222 (55.4%) were male. One hundred fifty-four patients (38.4%) were previously healthy, 108 (26.9%) were immunocompromised, and 225 (56.1%) had documented infection(s) at enrollment. Forty-four patients (11.0%) died in the PICU. Viral DNAemia with at least 1 virus (excluding TTV) was detected in 191 patients (47.6%) overall, 63 of 108 patients (58.3%) who were immunocompromised, and 128 of 293 (43.7%) who were not immunocompromised at sepsis onset. After adjustment for age, Pediatric Risk of Mortality score, previously healthy status, and immunocompromised status at sepsis onset, CMV (adjusted odds ratio [AOR], 3.01 [95% CI, 1.36-6.45]; P = .007), HAdV (AOR, 3.50 [95% CI, 1.46-8.09]; P = .006), BKPyV (AOR. 3.02 [95% CI, 1.17-7.34]; P = .02), and HHV-6 (AOR, 2.62 [95% CI, 1.31-5.20]; P = .007) DNAemia were each associated with increased mortality. Two or more viruses were detected in 78 patients (19.5%), with mortality among 12 of 32 (37.5%) who were immunocompromised and 9 of 46 (19.6%) who were not immunocompromised at sepsis onset. Herpesvirus seropositivity was common (HSV-1, 82 of 246 [33.3%]; CMV, 107 of 254 [42.1%]; EBV, 152 of 251 [60.6%]; HHV-6, 253 if 257 [98.4%]). After additional adjustment for receipt of blood products in the PICU, EBV seropositivity was associated with increased mortality (AOR, 6.10 [95% CI, 1.00-118.61]; P = .049).

Conclusions and Relevance

The findings of this cohort study suggest that DNAemia for CMV, HAdV, BKPyV, and HHV-6 and EBV seropositivity were independently associated with increased sepsis mortality. Further investigation of the underlying biology of these viral DNA infections in children with sepsis is warranted to determine whether they only reflect mortality risk or contribute to mortality.

A viral-specific CD4+ T cell response protects female mice from Coxsackievirus B3 infection

Background

Biological sex plays an integral role in the immune response to various pathogens. The underlying basis for these sex differences is still not well defined. Here, we show that Coxsackievirus B3 (CVB3) induces a viral-specific CD4+ T cell response that can protect female mice from mortality.

Methods

We inoculated C57BL/6 Ifnar-/- mice with CVB3. We investigated the T cell response in the spleen and mesenteric lymph nodes in male and female mice following infection.

Results

We found that CVB3 can induce expansion of CD62Llo CD4+ T cells in the mesenteric lymph node and spleen of female but not male mice as early as 5 days post-inoculation, indicative of activation. Using a recombinant CVB3 virus expressing a model CD4+ T cell epitope, we found that this response is due to viral antigen and not bystander activation. Finally, the depletion of CD4+ T cells before infection increased mortality in female mice, indicating that CD4+ T cells play a protective role against CVB3 in our model.

Conclusions

Overall, these data demonstrated that CVB3 can induce an early CD4 response in female but not male mice and further emphasize how sex differences in immune responses to pathogens affect disease.

Role of CCRL2 in the Pathogenesis of Experimental Autoimmune Myocarditis via P21-Activated Kinase 1/NOD-Like Receptor Protein 3 Pathway

Myocarditis, a severe inflammatory disease, is becoming a worldwide public health concern. This study aims to elucidate the effect of Chemokine (C C motif) receptor-like 2 (CCRL2) in experimental autoimmune myocarditis (EAM) occurrence and its potential regulatory mechanisms.EAM was simulated in a mouse model injected with α-myosin-heavy chain. The changes on EAM were assessed through histological staining of heart tissues, including measuring cardiac troponin I (cTnI), proinflammatory cytokines, transferase-mediated dUTP nick end labeling (TUNEL) assay, and cardiac function. Then, the heart tissues from the EAM mouse model and control groups were analyzed through transcriptome sequencing to identify the differential expressed genes (DEGs) and hub genes related to pyroptosis. Downregulation of CCRL2 further verified the function of CCRL2 on EAM and p21-activated kinase 1/NOD-like receptor protein 3 (PAK/NLRP3) signaling pathways in vivo.The EAM model was constructed successfully, with the heart weight/body weight ratio, serum level of cTnI, and concentrations of proinflammatory cytokines elevation. Moreover, cell apoptosis was also significantly increased. Transcriptome sequencing revealed 696 and 120 upregulated and downregulated DEGs, respectively. After functional enrichment, CCRL2 was selected as a potential target. Then, we verified that CCRL2 knockdown improved cardiac function, alleviated EAM occurrence, and reduced PAK/NLRP3 protein expression.CCRL2 may act as a novel potential treatment target in EAM by regulating the PAK1/NLRP3 pathway.

A viral-specific CD4 + T cell response protects female mice from Coxsackievirus B3 infection

Biological sex plays an integral role in the immune response to various pathogens. The underlying basis for these sex differences is still not well defined. Here, we show that Coxsackievirus B3 (CVB3) induces a viral-specific CD4 + T cell response that can protect female mice from mortality. We found that CVB3 can induce expansion of CD62L lo CD4 + T cells in the mesenteric lymph node and spleen of female but not male mice as early as 5 days post-inoculation, indicative of activation. Using a recombinant CVB3 virus expressing a model CD4 + T cell epitope, we found that this response is due to viral antigen and not bystander activation. Finally, the depletion of CD4 + T cells before infection increased mortality in female mice, indicating that CD4 + T cells play a protective role against CVB3 in our model. Overall, these data demonstrated that CVB3 can induce an early CD4 response in female but not male mice and further emphasize how sex differences in immune responses to pathogens affect disease outcomes.

Detection of Parvovirus B19 genome in human heart tissue samples

OBJECTIVE

Identifying viral genomes in human heart tissues is critical for disease diagnosis and assessment of cardiovascular damage. Human heart tissue samples obtained during a biopsy procedure are routinely used to test for the presence of viruses, as guided by clinical manifestations and prognosis. Furthermore, heart tissue samples obtained post-mortem or during a cardiac transplant procedure serve as a valuable research tool, as they allow for an in-depth assessment of cardiac pathology that can aid in our understanding of molecular pathways associated with disease. Because viral nucleic acid constitutes only a small portion of each sample's genetic material, appropriate methods are necessary for positive viral genome identification.

RESULTS

Snap-frozen heart tissue samples obtained either post-mortem or during a cardiac transplant procedure were used to develop conditions for detection of Parvovirus B19. Briefly, total DNA was isolated from the heart tissue under varying conditions. A PCR-based assay with Parvovirus B19 specific primers was implemented to detect the presence of the viral genome, followed by Sanger Sequencing. The mechanical disruption of the heart tissue, as well as the cardiac tissue processing methods, had a significant effect on the DNA quality and the ability to detect the Parvovirus B19 genome.

Update on Myocarditis: From Etiology and Clinical Picture to Modern Diagnostics and Methods of Treatment

Although the frequency of myocarditis in the general population is very difficult to accurately determine due to the large number of asymptomatic cases, the incidence of this disease is increasing significantly due to better defined criteria for diagnosis and the development of modern diagnostic methods. The multitude of different etiological factors, the diversity of the clinical picture, and the variability of the diagnostic findings make this disease often demanding both for the selection of the diagnostic modality and for the proper therapeutic approach. The previously known most common viral etiology of this disease is today overshadowed by new findings based on immune-mediated processes, associated with diseases that in their natural course can lead to myocardial involvement, as well as the iatrogenic cause of myocarditis, which is due to use of immune checkpoint inhibitors in the treatment of cancer patients. Suspecting that a patient with polymorphic and non-specific clinical signs and symptoms, such as changes in ECG and echocardiography readings, has myocarditis is the starting point in the diagnostic algorithm. Cardio magnetic resonance imaging is non-invasive and is the gold standard for diagnosis and clinical follow-up of these patients. Endomyocardial biopsy as an invasive method is the diagnostic choice in life-threatening cases with suspicion of fulminant myocarditis where the diagnosis has not yet established or there is no adequate response to the applied therapeutic regimen. The treatment of myocarditis is increasingly demanding and includes conservative methods of treating heart failure, immunomodulatory and immunospressive therapy, methods of mechanical circulatory support, and heart transplantation. The goal of developing new diagnostic and therapeutic methods is to reduce mortality from this complex disease, which is still high.

Intra-host variation in the spike S1/S2 region of a feline coronavirus type-1 in a cat with persistent infection

Feline coronavirus type 1 (FCoV-1) is widely known for causing feline infectious peritonitis (FIP), a systemic infection that is often fatal, with the virus known as the FIPV biotype. However, subclinical disease also occurs, in which cats may not show signs and intermittently shed the virus, including in feces, possibly for long periods of time. This virus is known as the FECV biotype. Progression of FECV to FIPV has been linked to several genomic changes, however a specific region of the viral spike protein at the interface of the spike S1 and S2 domains has been especially implicated. In this study, we followed a cat (#576) for six years from 2017, at which time FCoV-1 was detected in feces and conjunctival swabs, until 2022, when the animal was euthanized based on a diagnosis of alimentary small cell lymphoma. Over this time period, the cat was clinically diagnosed with inflammatory bowel disease and chronic rhinitis, and cardiac problems were also suspected. Using hybridization capture targeting the spike (S) gene of FCoV followed by next-generation sequencing, we screened 27 clinical samples. We detected FCoV-1 in 4 samples taken in 2017 (intestine and nasal tissue, feces, and conjunctiva), and 3 samples taken in 2022 (feces, and intestinal and heart tissue), but not in fecal samples taken in 2019 and 2020. Next, we focused on the S1/S2 region within S, which contains the furin cleavage site (FCS), a key regulator of viral transmission and pathogenesis. We show that the FCoV-1 variants obtained from feces in 2017 and 2022 were identical, while the ones from conjunctiva (2017), heart (2022), and intestine (2017 and 2022) were distinct. Sequence comparison of all the variants obtained showed that most of the non-synonymous changes in the S1/S2 region occur within the FCS. In the heart, we found two variants that differed by a single nucleotide, resulting in distinct FCS motifs that differ in one amino acid. It is predicted that one of these FCS motifs will down-regulate spike cleavability. The variant from the conjunctiva (2017) had a 6-nucleotide in-frame insertion that resulted in a longer and more exposed S1/S2 loop, which is predicted to be more accessible to the furin protease. Our studies indicate that FCoV-1 can independently persist in the gastrointestinal tract and heart of a cat over a long period of time without evidence of typical FIP signs, with intermittent viral shedding from the gastrointestinal and respiratory tracts.

Autoimmune Heart Disease: A Comprehensive Summary for Forensic Practice

Autoimmune heart disease is a non-random condition characterised by immune system-mediated aggression against cardiac tissue. Cardiac changes often exhibit nonspecific features and, if unrecognised, can result in fatal outcomes even among seemingly healthy young individuals. In the absence of reliable medical history, the primary challenge lies in differentiating between the various cardiopathies. Numerous immunohistochemical and genetic studies have endeavoured to characterise distinct types of cardiopathies, facilitating their differentiation during autopsy examinations. However, the presence of a standardised protocol that forensic pathologists can employ to guide their investigations would be beneficial. Hence, this summary aims to present the spectrum of autoimmune cardiopathies, including emerging insights such as SARS-CoV-2-induced cardiopathies, and proposes the utilisation of practical tools, such as blood markers, to aid forensic pathologists in their routine practice.

A Kaposi's sarcoma-associated herpes virus-encoded microRNA contributes to dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is the leading cause of heart transplantation. By microRNA (miRNA) array, a Kaposi's sarcoma-associated herpes virus (KSHV)-encoded miRNA, kshv-miR-K12-1-5p, was detected in patients with DCM. The KSHV DNA load and kshv-miR-K12-1-5p level in plasma from 696 patients with DCM were measured and these patients were followed-up. Increased KSHV seropositivity and quantitative titers were found in the patients with DCM compared with the non-DCM group (22.0% versus 9.1%, p < 0.05; 168 versus 14 copies/mL plasma, p < 0.05). The risk of the individual end point of death from cardiovascular causes or heart transplantation was increased among DCM patients with the KSHV DNA seropositivity during follow-up (adjusted hazard ratio 1.38, 95% confidence interval 1.01-1.90; p < 0.05). In heart tissues, the KSHV DNA load was also increased in the heart from patients with DCM in comparison with healthy donors (1016 versus 29 copies/105 cells, p < 0.05). The KSHV and kshv-miR-K12-1-5p in DCM hearts were detected using immunofluorescence and fluorescence staining in situ hybridization. KSHV itself was exclusively detectable in CD31-positive endothelium, while kshv-miR-K12-1-5p could be detected in both endothelium and cardiomyocytes. Moreover, kshv-miR-K12-1-5p released by KSHV-infected cardiac endothelium could disrupt the type I interferon signaling pathway in cardiomyocytes. Two models of kshv-miR-K12-1-5p overexpression (agomiR and recombinant adeno-associated virus) were used to explore the roles of KSHV-encoded miRNA in vivo. The kshv-miR-K12-1-5p aggravated known cardiotropic viruses-induced cardiac dysfunction and inflammatory infiltration. In conclusion, KSHV infection was a risk factor for DCM, providing developmental insights of DCM involving virus and its miRNA ( https://clinicaltrials.gov . Unique identifier: NCT03461107).