Distinct Th17 inductions contribute to the gender bias in CVB3-induced myocarditis

Cardiovascular Involvement in Tuberculosis Patients Treated in Southern Africa

Background

Tuberculosis (TB) is the leading cause of death among people with HIV and a major global health challenge. Subclinical cardiovascular manifestations of TB are poorly documented in high TB and HIV burden countries.

Objectives

The purpose of this study was to quantify the prevalence of cardiovascular involvement in TB patients and investigate changes after completion of anti-TB treatment.

Methods

HIV-positive and HIV-negative patients diagnosed with pulmonary TB between October 2022 and November 2023 were enrolled from 2 tertiary care hospitals in Zambia and South Africa. Standardized transthoracic echocardiography (TTE) was conducted at TB diagnosis and after 6 months of anti-TB treatment. Cross-sectional and longitudinal analyses assessed pericardial effusion, thickening, or calcification, with and without signs of pericardial constriction.

Results

A total of 286 TB patients (218 [76%] men, 109 [38%] people with HIV, median age 35 years) underwent TTE at TB diagnosis, of whom 105 participants had a second TTE after completion of treatment. At TB diagnosis, 134 (47%) had pericardial effusions, 86 (30%) thickening, 7 (2%) calcifications, 103 (42%) signs of constriction, and 13 (12%) had definite diagnosis of constriction. After TB treatment, pericardial effusions (47% vs 16%, P < 0.001) and pericardial thickenings (30% vs 15%, P = 0.002) became less prevalent. Pericardial calcifications (2% vs 1%, P = 0.4), signs of constrictions (42% vs 38%, P = 0.4), and definite diagnosis of constriction (12% vs 14%, P = 0.8) were similar.

Conclusions

Cardiac involvement is frequent in newly diagnosed TB patients. Early pericardial changes may be reversed with anti-TB treatment. Echocardiographic screening facilitates early detection and timely management of cardiovascular involvement in TB patients.

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.

Cardiovascular disease in transgender individuals

The population of people identifying as transgender has grown rapidly in recent years, resulting in a substantive increase in individuals obtaining gender-affirming medical care to align their secondary sex characteristics with their gender identity. This has established benefits for patients including improvements in gender dysphoria and psychosocial functioning, while reducing adverse mental health outcomes. Despite these potential advantages, recent evidence has suggested that gender-affirming hormone therapy (GAHT) may increase the risk of cardiovascular disease. However, owing to a paucity of research, the mechanisms underpinning these increased risks are poorly understood. Moreover, previous research has been limited by heterogenous methodologies, being underpowered, and lacking appropriate control populations. Consequently, the need for evidence regarding cardiovascular health in LGBTQ + individuals has been recognised as a critical area for future research to facilitate better healthcare and guidance. Recent research investigating the effect of transmasculine (testosterone) GAHT on cardiovascular disease risk points to testosterone effecting the nitric oxide pathway, triggering inflammation, and promoting endothelial dysfunction. Equivalent studies focussing on transfeminine (oestrogen) GAHT are required, representing a crucial area of future research. Furthermore, when examining the effects of GAHT on the vasculature, it cannot be ignored that there are multiple factors that may increase the burden of cardiovascular disease in the transgender population. Such stressors include major psychological stress; increased adverse health behaviours, such as smoking; discrimination; and lowered socioeconomic status; all of which undoubtedly impact upon cardiovascular disease risk and offers the opportunity for intervention.

The X-linked histone demethylases KDM5C and KDM6A as regulators of T cell-driven autoimmunity in the central nervous system

T cell-driven autoimmune responses are subject to striking sex-dependent effects. While the contributions of sex hormones are well-understood, those of sex chromosomes are meeting with increased appreciation. Here, we outline what is known about the contribution of sex chromosome-linked factors to experimental autoimmune encephalomyelitis (EAE), a mouse model that recapitulates many of the T cell-driven mechanisms of multiple sclerosis (MS) pathology. Particular attention is paid to the KDM family of histone demethylases, several of which - KDM5C, KDM5D and KDM6A - are sex chromosome encoded. Finally, we provide evidence that functional inhibition of KDM5 molecules can suppress interferon (IFN)γ production from murine male effector T cells, and that an increased ratio of inflammatory Kdm6a to immunomodulatory Kdm5c transcript is observed in T helper 17 (Th17) cells from women with the autoimmune disorder ankylosing spondylitis (AS). Histone lysine demethlyases thus represent intriguing targets for the treatment of T cell-driven autoimmune disorders.

Appendectomy Mitigates Coxsackievirus B3-Induced Viral Myocarditis

Appendix has a distinct abundance of lymphatic cells and serves as a reservoir of microbiota which helps to replenish the large intestine with healthy flora. And it is the primary site of IgA induction, which shapes the composition of the intestinal microbiota. Recent population-based cohort studies report that appendectomy is associated with an increased risk of acute myocardial infarction and ischemic heart disease. Here, whether appendectomy has an effect on the occurrence and development of coxsackievirus B3 (CVB3)-induced viral myocarditis is studied. 103 TCID50 CVB3 was inoculated i.p. into appendectomized and sham-operated mice. RNA levels of viral load and pro-inflammatory cytokines in the hearts and the intestine were detected by RT-PCR. Compared to sham-operated mice, appendectomized mice exhibited attenuated cardiac inflammation and improved cardiac function, which is associated with a systemic reduced viral load. Appendectomized mice also displayed a reduction in cardiac neutrophil and macrophage infiltration and pro-inflammatory cytokine production. Mechanistically, we found that CVB3 induced an early and potent IL-10 production in the cecal patch at 2 days post infection. Appendectomy significantly decreased intestinal IL-10 and IL-10+ CD4+ Treg frequency which led to a marked increase in intestinal (primary entry site for CVB3) anti-viral IFN-γ+ CD4+ T and IFN-γ+ CD8+ T response and viral restriction, eventually resulting in improved myocarditis. Our results suggest that appendix modulates cardiac infection and inflammation through regulating intestinal IL-10+ Treg response.

Vaccination-Associated Myocarditis and Myocardial Injury

SARS-CoV-2 vaccine-associated myocarditis/myocardial injury should be evaluated in the contexts of COVID-19 infection, other types of viral myocarditis, and other vaccine-associated cardiac disorders. COVID-19 vaccine-associated myocardial injury can be caused by an inflammatory immune cell infiltrate, but other etiologies such as microvascular thrombosis are also possible. The clinical diagnosis is typically based on symptoms and cardiac magnetic resonance imaging. Endomyocardial biopsy is confirmatory for myocarditis, but may not show an inflammatory infiltrate because of rapid resolution or a non-inflammatory etiology. Myocarditis associated with SARS-COVID-19 vaccines occurs primarily with mRNA platform vaccines, which are also the most effective. In persons aged >16 or >12 years the myocarditis estimated crude incidences after the first 2 doses of BNT162b2 and mRNA-1273 are approximately 1.9 and 3.5 per 100 000 individuals, respectively. These rates equate to excess incidences above control populations of approximately 1.2 (BNT162b2) and 1.9 (mRNA-1273) per 100 000 persons, which are lower than the myocarditis rate for smallpox but higher than that for influenza vaccines. In the studies that have included mRNA vaccine and SARS-COVID-19 myocarditis measured by the same methodology, the incidence rate was increased by 3.5-fold over control in COVID-19 compared with 1.5-fold for BNT162b2 and 6.2-fold for mRNA-1273. However, mortality and major morbidity are less and recovery is faster with mRNA vaccine-associated myocarditis compared to COVID-19 infection. The reasons for this include vaccine-associated myocarditis having a higher incidence in young adults and adolescents, typically no involvement of other organs in vaccine-associated myocarditis, and based on comparisons to non-COVID viral myocarditis an inherently more benign clinical course.

Biological Sex As a Critical Variable in CD4+ Effector T Cell Function in Preclinical Models of Multiple Sclerosis

Significance: T cells play a pivotal role in maintaining adaptive immune responses against pathogens. However, misdirected T cell responses against self-tissues may lead to autoimmune disease. Biological sex has profound effects on T cell function and is an important determinant of disease incidence and severity in autoimmune diseases such as multiple sclerosis (MS). Recent Advances: Many autoimmune diseases skew toward higher female incidence, including MS; however, it is has become increasingly more accepted that men living with MS are more prone to developing a progressive disease course and to having worsened disease outcomes. Critical Issues: In this review, we discuss what is known about the role of biological sex on T cell development and differentiation, examining evidence that male sex can augment T helper 17 (Th17) responses. Next, we outline what is known about sex differences in animal models of MS, and about the distinct roles played by sex hormones versus sex chromosomes in pathogenesis in these models. Finally, we discuss recent advances that examine the molecular basis for worsened disease outcomes in males, with a particular focus on the role played by Th17 cells in these models. Future Directions: Better understanding the role of biological sex in T cell function may pave the way to effective personalized treatment strategies in MS and other autoimmune diseases. Antioxid. Redox Signal. 37, 135-149.

Th17 cells-linked mechanisms mediate vascular dysfunction induced by testosterone in a mouse model of gender-affirming hormone therapy

Clinical data point to adverse cardiovascular events elicited by testosterone replacement therapy. Testosterone is the main hormone used in gender-affirming hormone therapy (GAHT) by transmasculine people. However, the cardiovascular impact of testosterone in experimental models of GAHT remains unknown. Sex hormones modulate T cells activation, and immune mechanisms contribute to cardiovascular risk. The present study evaluated whether testosterone negatively impacts female cardiovascular function by enhancing Th17 cells-linked effector mechanisms. Female (8 weeks-old) C57BL/6J mice received testosterone (48 mg.Kg^-1.week^-1) for 8 weeks. Male mice were used for phenotypical comparisons. The hormone-treatment in female mice increased circulating testosterone to levels observed in male mice. Testosterone increased lean body mass and body mass index, and decreased perigonadal fat mass, mimicking clinical findings. After 8 weeks, testosterone decreased endothelium-dependent vasodilation and increased circulating Th17 cells. After 24 weeks, testosterone increased blood pressure in female mice. Ovariectomy did not intensify phenotypical or cardiovascular effects by testosterone. Female mice lacking T and B cells [Rag1 knockout (^-/-)], as well as female mice lacking IL-17 receptor (IL-17Ra^-/-), did not exhibit vascular dysfunction induced by testosterone. Testosterone impaired endothelium-dependent vasodilation in female mice lacking γδ T cells, similarly to the observed in wild type female mice. Adoptive transfer of CD4⁺ T cells restored testosterone-induced vascular dysfunction in Rag1^-/- female mice. Together, these data suggest that CD4⁺ T cells, most likely Th17 cells, are central to vascular dysfunction induced by testosterone in female mice, indicating that changes in immune cells balance are important in the GAHT in transmasculine people.

Role of Toll-Like Receptors and Th Responses in Viral Myocarditis

Myocarditis is the common cause of sudden cardiac death, dilated cardiomyopathy (DCM) and heart failure (HF) in young adults. The most common type of myocarditis is viral myocarditis (VMC). Toll-like receptors (TLRs) are vital to identify pathogens in vivo. TLRs promote the differentiation of naive CD4⁺T cells to T helper (Th) cells, activate the immune response, and participate in the pathogenesis of autoimmune and allergic diseases. Although the pathogenesis of VMC is unclear, autoimmune responses have been confirmed to play a significant role; hence, it could be inferred that VMC is closely related to TLRs and Th responses. Some drugs have been found to improve the prognosis of VMC by regulating the immune response through activated TLRs. In this review, we discuss the role of TLRs and Th responses in VMC.

Arrhythmia spectrum and outcome in children with myocarditis

Introduction

Myocarditis remains an under-diagnosed entity among children. We evaluated the spectrum of electrocardiogram (ECG) changes and arrhythmias in children with myocarditis.

Methods

A single-center prospective observational study was conducted over a period of 18 months at a public university hospital, which included all cases with myocarditis from the ages of 1 month to 12 years. Myocarditis was diagnosed according to standard criteria. Arrhythmias were detected by 12-lead ECG or by multiparameter monitors.

Results

There were 63 children with myocarditis. Sinus tachycardia remained the most important ECG finding (61, 96.8%) followed by ST-T changes (30, 47.6%), low voltage QRS complexes (23, 36.5%), and premature complexes (11, 17.4%). Sustained arrhythmias were seen in 14/63 (22.2%) of the children (Group A), while the remaining 49 patients were designated as Group B. There were 11 (17.5%) cases with sustained tachyarrhythmias, comprising 5 with supraventricular tachycardia, 4 with ventricular tachycardia, and 2 with atrial flutter/fibrillation. Bradyarrhythmias were seen in 3 patients, including 2 children with atrioventricular block and 1 with severe sinus bradycardia. A longer hospital stay of 18.5 (4.75) days vs. 13 (4) days, P = 0.001), and more ST-T changes [12 (85.7%) vs. 18 (36.73%), P = 0.003] were seen in Group A. Multivariate regression analysis found only the presence of ST-T changes as predictors for arrhythmia.

Conclusions

A variety of arrhythmias and other ECG changes were commonly seen in children with myocarditis. Sustained arrhythmias were seen in one-fifth of the patients, being associated with ST-T changes and a longer hospital stay.

Cardiovascular magnetic resonance findings in young adult patients with acute myocarditis following mRNA COVID-19 vaccination: a case series

BACKGROUND

Messenger RNA (mRNA) coronavirus disease of 2019 (COVID-19) vaccine are known to cause minor side effects at the injection site and mild global systemic symptoms in first 24-48 h. Recently published case series have reported a possible association between acute myocarditis and COVID-19 vaccination, predominantly in young males.

METHODS

We report a case series of 5 young male patients with cardiovascular magnetic resonance (CMR)-confirmed acute myocarditis within 72 h after receiving a dose of an mRNA-based COVID-19 vaccine.

RESULTS

Our case series suggests that myocarditis in this setting is characterized by myocardial edema and late gadolinium enhancement in the lateral wall of the left ventricular (LV) myocardium, reduced global LV longitudinal strain, and preserved LV ejection fraction. All patients in our series remained clinically stable during a relatively short inpatient hospital stay.

CONCLUSIONS

In conjunction with other recently published case series and national vaccine safety surveillance data, this case series suggests a possible association between acute myocarditis and COVID-19 vaccination in young males and highlights a potential pattern in accompanying CMR abnormalities.

Male sex chromosomal complement exacerbates the pathogenicity of Th17 cells in a chronic model of central nervous system autoimmunity

Sex differences in multiple sclerosis (MS) incidence and severity have long been recognized. However, the underlying cellular and molecular mechanisms for why male sex is associated with more aggressive disease remain poorly defined. Using a T cell adoptive transfer model of chronic experimental autoimmune encephalomyelitis (EAE), we find that male Th17 cells induce disease of increased severity relative to female Th17 cells, irrespective of whether transferred to male or female recipients. Throughout the disease course, a greater frequency of male Th17 cells produce IFNγ, a hallmark of pathogenic Th17 responses. Intriguingly, XY chromosomal complement increases the pathogenicity of male Th17 cells. An X-linked immune regulator, Jarid1c, is downregulated in pathogenic male murine Th17 cells, and functional experiments reveal that it represses the severity of Th17-mediated EAE. Furthermore, Jarid1c expression is downregulated in CD4⁺ T cells from MS-affected individuals. Our data indicate that male sex chromosomal complement critically regulates Th17 cell pathogenicity.

Predictors and risk factors of short-term readmission of acute pericarditis

Background: The 30-day readmission risk factors for acute pericarditis are not well known. We investigated the risk factors and predictors of pericarditis from a national cohort.Methods: Readmission data from the National Readmission Database (NRD) from the year 2016 were used to analyze the prevalence of risk factors and predictors of pericarditis 30-day readmission.Results: From the year 2016, 16,475 acute pericarditis hospitalizations were recorded. The rate of readmission from the year 2016 is similar to 2012 reported data (18%). A total of 13,844 patients (mean age 55.2 years, 40% of women) were found for acute pericarditis readmissions. The incidence rate of 30-day readmission of acute pericarditis patients in our study was 17.8% with the major cause of readmission was related to cardiovascular (pericarditis, endocarditis, and myocarditis) during 30-day follow-up. The median cost of the index and 30 days pericarditis admission $10,048 and $9,932, respectively.Conclusion: Chronic comorbidities, prolonged hospitalization, and admission to a short-term hospital/left against medical advice admission to metropolitan teaching hospital were associated with a higher risk of 30-day readmission.

Myocarditis and inflammatory cardiomyopathy: current evidence and future directions

Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.

A Case for Targeting Th17 Cells and IL-17A in SARS-CoV-2 Infections

SARS-CoV-2, the virus causing COVID-19, has infected millions and has caused hundreds of thousands of fatalities. Risk factors for critical illness from SARS-CoV-2 infection include male gender, obesity, diabetes, and age >65. The mechanisms underlying the susceptibility to critical illness are poorly understood. Of interest, these comorbidities have previously been associated with increased signaling of Th17 cells. Th17 cells secrete IL-17A and are important for clearing extracellular pathogens, but inappropriate signaling has been linked to acute respiratory distress syndrome. Currently there are few treatment options for SARS-CoV-2 infections. This review describes evidence linking risk factors for critical illness in COVID-19 with increased Th17 cell activation and IL-17 signaling that may lead to increased likelihood for lung injury and respiratory failure. These findings provide a basis for testing the potential use of therapies directed at modulation of Th17 cells and IL-17A signaling in the treatment of COVID-19.

Interleukin-17: Potential Target for Chronic Wounds

Chronic wounds exhibit persistent inflammation with markedly delayed healing. The significant burden of chronic wounds, which are often resistant to standard therapy, prompts further research on novel therapies. Since the interleukin-17 family has been implicated as a group of proinflammatory cytokines in immune-mediated diseases in the gut and connective tissue, as well as inflammatory skin conditions, we consider here if it may contribute to the pathogenesis of chronic wounds. In this review, we discuss the interleukin-17 family's signaling pathways and role in tissue repair. A PubMed review of the English literature on interleukin-17, wound healing, chronic wounds, and inflammatory skin conditions was conducted. Interleukin-17 family signaling is reviewed in the context of tissue repair, and preclinical and clinical studies examining its role in the skin and other organ systems are critically reviewed. The published work supports a pathologic role for interleukin-17 family members in chronic wounds, though this needs to be more conclusively proven. Clinical studies using monoclonal interleukin-17 antibodies to improve healing of chronic skin wounds have not yet been performed, and only a few studies have examined interleukin-17 family expression in chronic skin wounds. Furthermore, different interleukin-17 family members could be playing selective roles in the repair process. These studies suggest a therapeutic role for targeting interleukin-17A to promote wound healing; therefore, interleukin-17A may be a target worthy of pursuing in the near future.

Vitamin D receptor restricts T helper 2-biased inflammation in the heart

Background and aims

The aberrant immune responses play a critical role in the pathogenesis of myocarditis. Vitamin D receptor (VDR) has immune regulatory functions. This study aims to investigate the role of VDR in restricting the immune inflammation in the heart.

Methods and results

The human heart samples were obtained from the heart transplantation. T helper (Th)2 and Th1 responses in the heart tissue were characterized by histology and immune assay. VDR-/- mice and recombination activating gene 2-/- mice were used in the experiments to test the role of VDR in maintaining the homeostasis in the heart. The results showed that, besides tissue damage, lower expression of VDR, high frequency of Th2 cells and increase in Th2 cytokines in the hearts of patients with myocarditis at the end stage of heart failure. The spontaneous Th2-biased inflammation was observed in the hearts of VDR-/- mice. CD4+ T cells from the VDR-/- mouse hearts were at highly activating status. The naïve VDR-/- CD4+ T cells and naïve CD4+ T cells from human hearts with myocarditis were prone to differentiate into Th2 cells. VDR formed complexes with GATA3, the interleukin (IL)-4 transcription factor, to prevent the Il4 gene transcription. Transplantation with VDR-/-CD4+ T cells induced the Th2-biased inflammation in the hearts of Rag2-/- mice. Reconstitution of VDR in CD4+ T cells inhibited the Th2-biased inflammation in the heart.

Conclusions

VDR-deficiency contributes to the pathogenesis of myocarditis. To enhance the VDR expression in CD4+, T cells haves the therapeutic potential for the treatment of myocarditis.

Altered immune parameters associated with Koala Retrovirus (KoRV) and Chlamydial infection in free ranging Victorian koalas (Phascolarctos cinereus)

Koala Retrovirus (KoRV) has been widely speculated to cause immune suppression in koalas (Phascolarctos cinereus) and to underlie the koala's susceptibility to infectious disease, however evidence for immunomodulation is limited. The aim of this study is to determine whether immunophenotypic changes are associated with KoRV infection in free ranging Victorian koalas. qPCR was used to examine mRNA expression for Th1 (IFNγ), Th2-promoting (IL6, IL10) and Th17 (IL17A) cytokines, along with CD4 and CD8 in whole blood of koalas (n = 74) from Mt Eccles and Raymond Island in Victoria, Australia, with and without natural chlamydial infection. KoRV positive koalas had significantly lower levels of IL17A (p`0.023) and IFNγ (p = 0.044) gene expression along with a decreased CD4:CD8 gene expression ratio (p = 0.025) compared to negative koalas. No effect of chlamydial infection or combined effect of KoRV and chlamydial infection was detected in these populations. The decreased expression of IFNγ could make KoRV infected koalas more susceptible to persistent chlamydial infection, and a decrease in IL17A could make them more susceptible to gram negative bacterial, fungal and mycobacterial infection; but more tolerant of chlamydial infection.

Calpain regulates CVB3 induced viral myocarditis by promoting autophagic flux upon infection

Calpains are calcium-activated neutral cysteine proteases. The dysregulation of calpain activity has been found to be related to cardiovascular diseases, for which calpain inhibition is used as a treatment. Viral myocarditis (VMC) is primarily caused by Coxsackievirus group B3 virus infection (CVB3). CVB3 virus infection induces autophagy and hijacks this process to facilitate its replication. In this study, we found that calpain was significantly activated in hearts affected by VMC. However, pharmacologically inhibiting calpain aggravated VMC symptoms in mice due to myocardial inflammation and cardiac dysfunction. The inhibition of calpain activity in vitro led to the accumulation of LC3-II and increased levels of p62/SQSTM1 protein expression, suggesting that autophagic flux was impaired by calpain inhibition. These effects of calpain inhibition were also observed in capn4-specific myocardial knockout mice in vivo. Furthermore, our results provided evidence that calpain inhibition in VMC, unlike other cardiovascular diseases, exacerbated the disease symptom by impairing CVB3-induced autophagic flux, which may subsequently reduce virus autolysosome degradation. Our findings indicated that calpain inhibition may not be a good treatment for VMC disease in a clinical setting.

Occurrence and Features of Childhood Myocarditis: A Nationwide Study in Finland

Background

Epidemiology of myocarditis in childhood is largely unknown. Men are known to have a higher incidence of myocarditis than women in adults aged <50 years, but whether this is true by sex in pediatric age groups is unknown. We set out to study the occurrence and potential sex differences of myocarditis in a general pediatric population.

Methods and Results

Data of all hospital admissions with myocarditis in Finland occurring in patients aged ≤15 years from 2004 to 2014 were collected from a mandatory nationwide registry. All patients with myocarditis as a primary, secondary, or tertiary cause of admission were included. Total and age‐ and sex‐specific incidence rates were calculated using corresponding population data. There were 213 admissions with myocarditis in pediatric patients. Myocarditis was the primary cause of admission in 86%. The overall incidence rate of myocarditis was 1.95/100 000 person‐years. Of all patients, 77% were boys, but sex differences in incidence rates were age‐dependent. In children aged 0 to 5 years, there was no sex difference in the occurrence of myocarditis. Boys aged 6 to 10 years had a higher incidence rate compared with girls (72% boys; incidence rate ratio: 2.46; 95% confidence interval, 1.03–5.89; P=0.04). Sex difference further increased in children aged 11 to 15 years (80% boys; incidence rate ratio: 3.5; 95% confidence interval, 2.68–5.67; P<0.0001).

Conclusions

Myocarditis leading to hospital admission is relatively uncommon in children, but occurrence of myocarditis increases with age. There is no sex difference in the risk of myocarditis during the first 6 years of life, but boys have a significantly higher risk at ages 6 to 15 years.

Age-Associated Changes in Estrogen Receptor Ratios Correlate with Increased Female Susceptibility to Coxsackievirus B3-Induced Myocarditis

Sexual bias is a hallmark in various diseases. This review evaluates sexual dimorphism in clinical and experimental coxsackievirus B3 (CVB3) myocarditis, and how sex bias in the experimental disease changes with increased age. Coxsackieviruses are major causes of viral myocarditis, an inflammation of the heart muscle, which is more frequent and severe in men than women. Young male mice infected with CVB3 develop heart-specific autoimmunity and severe myocarditis. Females infected during estrus (high estradiol) develop T-regulatory cells and when infected during diestrus (low estradiol) develop autoimmunity similar to males. During estrus, protection depends on estrogen receptor alpha (ERα), which promotes type I interferon, activation of natural killer/natural killer T cells and suppressor cell responses. Estrogen receptor beta has opposing effects to ERα and supports pro-inflammatory immunity. However, the sexual dimorphism of the disease is significantly ameliorated in aged animals when old females become as susceptible as males. This correlates to a selective loss of the ERα that is required for immunosuppression. Therefore, sex-associated hormones control susceptibility in the virus-mediated disease, but their impact can alter with the age and physiological stage of the individual.

Sex Drives Dimorphic Immune Responses to Viral Infections

New attention to sexual dimorphism in normal mammalian physiology and disease has uncovered a previously unappreciated breadth of mechanisms by which females and males differentially exhibit quantitative phenotypes. Thus, in addition to the established modifying effects of hormones, which prenatally and postpubertally pattern cells and tissues in a sexually dimorphic fashion, sex differences are caused by extragonadal and dosage effects of genes encoded on sex chromosomes. Sex differences in immune responses, especially during autoimmunity, have been studied predominantly within the context of sex hormone effects. More recently, immune response genes have been localized to sex chromosomes themselves or found to be regulated by sex chromosome genes. Thus, understanding how sex impacts immunity requires the elucidation of complex interactions among sex hormones, sex chromosomes, and immune response genes. In this Brief Review, we discuss current knowledge and new insights into these intricate relationships in the context of viral infections.

Sex-Dependent Intestinal Replication of an Enteric Virus

Coxsackievirus is an enteric virus that initiates infection in the gastrointestinal tract before disseminating to peripheral tissues to cause disease, but intestinal factors that influence viral replication are understudied. Furthermore, a sex bias for severe sequelae from coxsackievirus infections has been observed in humans. While mouse models mimicking human pathogenesis have been well characterized, many of these experiments use intraperitoneal injection of coxsackievirus to infect mice, bypassing the intestine. In light of recent studies identifying intestinal factors, such as the microbiota, that alter enteric viral replication, we sought to investigate coxsackievirus replication within the intestine. Here, we orally infected mice with coxsackievirus B3 (CVB3) and found that CVB3 replication in the intestine is sex dependent. CVB3 replicated efficiently in the intestine of male mice but not female mice. Additionally, we found that the type I interferon response and sex hormones can alter both viral replication and lethality. Overall, these data suggest that sex and the immune response play a vital role in CVB3 replication in the intestine and should be considered in light of the sex bias observed in human disease.IMPORTANCE Sex bias in severe sequelae from enteric viral infections has been observed. Since viruses have evolved to achieve optimal levels of fitness in their environmental niches, it is imperative to study viruses at the site of initial replication. Here, we used an oral inoculation system for CVB3, which follows the natural route of infection in the gastrointestinal tract. We found that sex can influence the replication of CVB3 in the intestine. Additionally, the type I interferon response and sex hormones alter both CVB3 intestinal replication and lethality. Overall this work highlights the fact that sex should be considered in investigations of enteric viral replication and pathogenesis.

Expansion of CD11b+Ly-6C+ myeloid-derived suppressor cells (MDSCs) driven by galectin-9 attenuates CVB3-induced myocarditis

Galectin-9 is known to play a role in the modulation of innate and adaptive immunity to ameliorate CVB3-induced myocarditis. In the present study, we found that galectin-9 induced the expansion of CD11b⁺Ly-6C⁺ myeloid-derived suppressor cells (MDSCs) in the heart from CVB3-infected mice. Adoptive transfer of CD11b⁺Ly-6C⁺ MDSCs significantly alleviated myocarditis accompanied by increased Th2 and Treg frequency and anti-inflammatory cytokines expression in the heart tissue. Moreover, Ly6C⁺ MDSCs, but not Ly6G⁺ cells, expressed Arg-1 and NOS2, and suppressed CD4⁺ T cell proliferation in vitro in an Arg-1-dependent mechanism; an event that was reversed with treatment of either an Arg-1 inhibitor or addition of excess l-arginine. Furthermore, Ly6C⁺ MDSCs co-expressed higher levels of F4/80, Tim-3, and IL-4Rα, and had the plasticity to up-regulate NOS2 or Arg-1 in response to IFN-γ or IL-4 treatment. The present results indicate that galectin-9 expands CD11b⁺Ly-6C⁺ MDSCs to ameliorate CVB3-induced myocarditis.

Sex-based differences in prevalence and clinical presentation among pericarditis and myopericarditis patients

BACKGROUND

Sex differences in heart diseases, including acute coronary syndrome, congestive heart failure, and atrial fibrillation, have been studied extensively. However, data are lacking regarding sex differences in pericarditis and myopericarditis patients.

OBJECTIVES

The purpose of the study was to evaluate whether there are sex differences in pericarditis and myopericarditis patients as well.

METHODS

We performed a retrospective, single-center observational study that included 200 consecutive patients hospitalized with idiopathic pericarditis or myopericarditis from January 2012 to April 2014. Patients were evaluated for sex differences in prevalence, clinical presentation, laboratory variables, and outcome. We excluded patients with a known cause for pericarditis.

RESULTS

Among 200 consecutive patients, 55 (27%) were female. Compared with men, women were significantly older (60±19 years vs 46±19 years, P<.001) and had a higher rate of chronic medical conditions. Myopericarditis was significantly more common among men (51% vs 25%, P=.001). Accordingly, men had significantly higher levels of peak troponin (6.8±17 ng/mL vs 0.9±2.6 ng/mL, P<.001), whereas women presented more frequently with pericardial effusion (68% vs 45%, P=.006). Interestingly, women had a significantly lower rate of hospitalization in the cardiology department (42% vs 63%, P=.015). Overall, there were no significant differences in ejection fraction, type of treatment, complications, or in-hospital mortality.

CONCLUSIONS

Most patients admitted with acute idiopathic pericarditis are male. In addition, men have a higher prevalence of myocardial involvement. Significant sex differences exist in laboratory variables and in hospital management; however, the outcome is similar and favorable in both sexes.

Monocytic myeloid-derived suppressor cells from females, but not males, alleviate CVB3-induced myocarditis by increasing regulatory and CD4(+)IL-10(+) T cells

Coxsackievirus group B type 3 (CVB3) is a common etiologic agent of viral myocarditis and often causes sexually dimorphic myocarditis with increased incidence and mortality in male. So far, the underlying mechanism for the high male prevalence is not well elucidated. In this study, we deciphered the role of myeloid-derived suppressor cells (MDSCs) in the gender bias in murine CVB3-induced myocarditis by comparing their frequencies, subsets as well as immune suppressive functions. We found that much more myocardial MDSCs were enriched in infected females than males, with dramatically higher percentage ratio of CD11b⁺Ly6G-Ly6C^high monocytic subset (M-MDSCs) to CD11b⁺Ly6G⁺Ly6C^low granulocytic subset (G-MDSCs). Interestingly, more potent suppression on T cell proliferation was also evidenced in female-derived M-MDSCs. Consistently, adoptive transfer of female- but not male-derived M-MDSCs efficiently alleviated CVB3-induced myocarditis in male recipient mice, and this protection could be ascribed to the increased induction of regulatory and CD4⁺IL-10⁺ T cells. Our study suggested that myocardial MDSCs were distinctively induced not only in quantities but also in phenotypes and immune suppressive functions in CVB3-infected males and females; and female-derived more suppressive M-MDSCs contributed to their insensitivity to CVB3-induced myocarditis.

Interleukin-27 ameliorates coxsackievirus-B3-induced viral myocarditis by inhibiting Th17 cells

Background

Interleukin (IL)-27, which has both pro and anti- inflammatory properties, is a new discovered heterodimeric cytokine that belongs to IL-12 family. However, the expression pattern and functional role of IL-27 in viral myocarditis (VMC) has not been investigated.

Methods

BALB/c mice were intraperitoneally (i.p) infected with Coxsackie virus B3 (CVB3) for establishing VMC models. Mice were then injected i.p. with Anti-Mouse IL-27 p28Ab or recombinant IL-27 for neutralization and overexpression of IL-27. The survival rates of mice were recorded and the kinetics of IL-27 expression, the frequencies of Th17 cells and the expression of inflammatory cytokine in CVB3-infected mice were determined by ELISA, real-time PCR and flow cytometry.

Results

The IL-27 expression in heart tissues and serum in coxsackievirus B3 (CVB3)-induced myocarditis mice peaked on day 4 but then rapidly decreased during the late infectious stage of CVB3, high IL-27 levels were negatively correlated with bodyweight loss (r = −0.71, P = 0.021) and myocardial pathological score (r = −0.85, P = 0.0018). Additionally, neutralization of IL-27 with Anti-IL-27 Ab accelerated, whereas systemic administration of recombinant mouse IL-27 ameliorated CVB3-induced myocarditis. The protective role of IL-27 in VMC was reflected by an improved survival rate, increased bodyweights, and reduced pathological scores in Anti-IL-27 group compared with IgG control group. Mechanistic investigations showed that IL-27 inhibited Th17 cells frequencies and IL-17 production, as well as the Th17-related proinflammatory cytokines in heart tissues.

Conclusions

Our results demonstrate that that IL-27 effectively protects the myocardium from the pathogenesis of CVB3 induced myocarditis, which may be attributable to reduced Th17 production. IL-27 might serve as a novel therapeutic treatment for VMC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-015-0418-x) contains supplementary material, which is available to authorized users.

Prognosis of myopericarditis as determined from previously published reports

BACKGROUND

The prognosis of pericarditis with concomitant myocarditis, especially in the setting of troponin elevation, is a reason for concern because it could imply an adverse outcome.

METHODS

We performed a comprehensive Medline search of all publications from 2000 to 2013 with the MeSH terms 'pericarditis', 'myocarditis' and 'prognosis'. Additional publications were sought using the reference lists of identified papers, the published reviews on this topic, and a search of abstracts from the American Heart Association, American College of Cardiology, and European Society of Cardiology scientific sessions.

RESULTS

We identified eight major clinical series evaluating the prognosis of myopericarditis. Studies included a total of 389 patients with myopericarditis (mean age 31.7 years, men-to-women ratio 4.0). After a mean follow-up of 31 months, residual left-ventricular dysfunction was reported in 3.5% without cases of heart failure. Recurrences occurred in 13.0% of cases mainly as recurrent pericarditis (>90%), cardiac tamponade and constrictive pericarditis in less than 1% of cases. The overall prognosis seems good (no mortality), with only one single discordant study reporting three deaths: one related to cardiac tamponade and two sudden cardiac deaths during hospitalization, but no out-of-hospital deaths during follow-up.

CONCLUSION

Myopericarditis has a good overall prognosis. Troponin elevation in this setting does not predict an adverse outcome in most cases. Thus it is important to reassure the patients on their prognosis, explaining the nature of the disease and the likely course. Diagnostic and therapeutic choices should take into account the overall good outcome of these patients, including less invasive diagnostic tools and toxic drugs.

AIM2 co-immunization favors specific multifunctional CD8(+) T cell induction and ameliorates coxsackievirus B3-induced chronic myocarditis

Coxsackievirus B3 (CVB3) infection can cause acute myocarditis and chronic myocarditis, leading to dilated cardiomyopathy (DCM) with no effective therapeutic strategy. Therefore, we investigated the potential of absent in melanoma 2 (AIM2) to enhance the therapeutic efficacy of DNA vaccine against CVB3-induced chronic myocarditis. Mice were infected with CVB3 and then intranasally immunized with chitosan-pcDNA3.1 (mock), chitosan-pAIM2 (CS-pAIM2), chitosan-pVP1 (CS-pVP1), or chitosan-pAIM2 plus chitosan-pVP1 (CS-pAIM2/CS-pVP1) at 7, 21, and 35d. Therapeutic efficacies of various vaccines were evaluated at day 56d. Compared with CS-pVP1 immunization, CS-pAIM2/CS-pVP1 co-immunization significantly increased survival rate, improved cardiac function, as well as decreased myocardial injury and fibrosis, this result indicated that CVB3-induced chronic myocarditis was alleviated. CVB3-specific T lymphocyte proliferation and cytotoxic T lymphocyte responses of the CS-pAIM2/CS-pVP1 co-immunization group were also increased. More interestingly, CS-pAIM2/CS-pVP1 co-immunization could facilitate CVB3-specific multifunctional CD8(+) T cell induction in the intestinal mucosa, and this induction was closely correlated with myocardial scores, this result indicated that CS-pAIM2/CS-pVP1 vaccine exhibits therapeutic efficacy by enhancing multifunctional CD8(+) T cells. This study may represent a novel therapy for CVB3-induced chronic myocarditis.

Endoplasmic Reticulum Stress Aggravates Viral Myocarditis by Raising Inflammation Through the IRE1-Associated NF-κB Pathway

BACKGROUND

Viral myocarditis, which is mostly caused by coxsackievirus infection, is characterized by myocardial inflammation. Abnormal endoplasmic reticulum (ER) stress participates in many heart diseases, but its role in viral myocarditis remains unsolved.

METHODS

We investigated the influence of ER stress in coxsackievirus B3 (CVB3)-induced viral myocarditis by dynamically detecting its activation in CVB3-infected hearts, analyzing its association with myocarditis severity, and exploring its impact on disease development by modulating the strength of ER stress with the chemical activator tunicamycin (Tm) or the inhibitor tauroursodeoxycholic acid (TUDCA). The underlying signal pathway of ER stress in CVB3-induced myocarditis was also deciphered.

RESULTS

We found that myocardial expression of Grp78 and Grp94, 2 ER stress markers, was significantly increased after CVB3 infection and positively correlated with myocarditis severity. Consistently, Tm-augmented ER stress obviously aggravated myocarditis, as shown by more severe myocardial inflammation, reduced cardiac function, and a lower survival rate, whereas TUDCA decreased ER stress and obviously alleviated myocarditis. This pathologic effect of ER stress could be attributed to increased levels of proinflammatory cytokine (interleukin [IL]-6, IL-12, tumor necrosis factor-alpha, and monocyte chemoattractant protein-1) production through the IRE1-associated nuclear factor-κB (NF-kB) pathway.

CONCLUSIONS

ER stress accentuated CVB3-induced myocardial inflammation through the IRE1-associated NF-κB pathway. This study may help us understand the role of ER stress in viral myocarditis and promote the development of corresponding therapeutic strategies based on manipulating ER stress.

Clinical profile and influences on outcomes in patients hospitalized for acute pericarditis

BACKGROUND

The clinical profile with regard to sex and the influences on outcomes in patients who have been hospitalized for acute pericarditis is largely uncharacterized.

METHODS AND RESULTS

We studied all patients aged ≥16 years admitted to the hospital because of acute pericarditis (postpericardiotomy and myocardial infarction associated pericarditis were excluded). Data were collected from a Finnish national registry that included data on all cardiovascular admissions (670 409) during 9.5 years in 29 hospitals nationwide. During the study period, there were 1361 admissions for acute pericarditis. Pericarditis patients were more likely to be male (64.9% of patients) than female (35.1%), with an age-adjusted likelihood ratio of 1.85 (95% confidence interval [CI], 1.65-2.06; P<0.0001) for male sex. The standardized incidence rate of hospitalizations for acute pericarditis was 3.32 per 100 000 person-years. Men 16 to 65 years of age were at higher risk for pericarditis (relative risk, 2.02; 95% CI, 1.81-2.26; P<0.0001) than women in the general admitted population, with the highest risk difference among young adults. Acute pericarditis caused 0.20% (95% CI, 0.19%-0.22%) of all cardiovascular admissions. The proportion of pericarditis-caused admissions declined by an estimated 51% per 10-year increase in age. The in-hospital mortality rate for acute pericarditis was 1.1% (95% CI, 0.6%-1.8%). Mortality increased with age (hazard ratio, 3.26; 95% CI, 1.78-5.95 per 10-year increase in age; P=0.0001) and severe coinfection (pneumonia or septicemia; hazard ratio, 13.46; 95% CI, 2.26-80.01; P<0.005) but was not associated with sex in multivariate analysis.

CONCLUSIONS

Patients hospitalized for acute pericarditis are more commonly male. Increasing age and severe coinfection are associated with greater in-hospital mortality in hospitalized acute pericarditis patients.

NK-derived IFN-γ/IL-4 triggers the sexually disparate polarization of macrophages in CVB3-induced myocarditis

Coxsackievirus B3 (CVB3) is a common etiology of myocarditis with an increased morbidity and mortality in males. We previously reported that differential polarization of macrophages contributed to sexually dimorphic susceptibility of mice to CVB3-induced myocarditis. However, the underlying kinetics, impetus as well as the molecular mechanism remain unclear. Here, we demonstrated that myocardial macrophages started to polarize at as early as day 5 post CVB3 infection in both genders of BALB/c mice, with M1 phenotype detected in males and M2a phenotype in females, and this trend was further amplified at day 7 when myocarditis reached peak. In addition, we identified that prevailed IFN-γ in males and dominant IL-4 in females were critical myocardial cytokines for the disparate macrophage polarization, which respectively activated JAK1-STAT1 and JAK3-STAT6 pathways. Strikingly, we found that the main source of IFN-γ and IL-4 cytokines in both genders were myocardial infiltrating NK cells, which differentially secreted cytokines in various microenvironments manifested synergistically by sex hormones and CVB3 infection. Consistently, depletion of NK cells significantly impeded the myocardial macrophage polarization in both genders of CVB3-infected mice. Collectively, these data indicated that myocardial NK-derived IFN-γ/IL-4 was critical for the differential polarization of macrophages in CVB3-induced myocarditis via activating JAK1-STAT1 and JAK3-STAT6 pathways respectively. Our study may help understand the mechanism of sexually differential polarization of macrophages and provide clues for the gender bias in CVB3-induced myocarditis.

In vivo delivery of interleukin-35 relieves coxsackievirus-B3-induced viral myocarditis by inhibiting Th17 cells

Interleukin (IL)-35 is a new member of the IL-12 cytokine family. The suppressive role of IL-35 in the immune response to parasitic and bacterial infections and in autoimmunity has been demonstrated in terms of its anti-inflammatory properties. However, the functional role of IL-35 in viral myocarditis has not been investigated. In this study, IL-35 expression was measured in heart tissues with coxsackievirus B3 (CVB3)-induced myocarditis. It was significantly reduced in the late stage of viral infection and correlated negatively with disease severity. To examine the therapeutic role of IL-35 in viral myocarditis, an IL-35-expressing plasmid (pIL-35-FC) was packaged with polyethyleneimine and delivered intraperitoneally to BALB/c male mice before and after CVB3 infection. The severity of myocarditis was assessed 7 days after infection. The in vivo delivery of IL-35 significantly ameliorated the severity of viral myocarditis, reflected in an increased survival rate and increased bodyweights, and reduced serum creatine kinase (CK) and CK-MB activities, cardiac pathological scores, and viral replication. We also show that the overexpression of IL-35 reduced splenic Th17 cells and Th17-related proinflammatory cytokines in heart tissues. In conclusion, our data indicate that IL-35 effectively protects the myocardium from the pathogenesis of CVB3-induced viral myocarditis, which may be attributable to reduced Th17 production. This suggests that supplementation with IL-35 could be a novel therapeutic treatment for viral myocarditis.

The effects of gender and age on occurrence of clinically suspected myocarditis in adulthood

OBJECTIVE

To study the effects of gender and age on occurrence of myocarditis.

DESIGN

Nationwide, multicentre registry study in Finland.

SETTING

All medical hospital admissions (n=1 698 397) of patients aged ≥ 16 years during 9.5 years in 29 hospitals.

PATIENTS

3198 myocarditis patients.

RESULTS

Myocarditis was more common in men (76.61%; 95% CI 75.11% to 78.05%) than in women (23.39%; 95% CI 21.95% to 24.89%, p<0.0001). Median age of patients was 33 years (IQR 23-50 years). Male patients were significantly younger than females (mean age 34.1 ± SD 15.1 vs 49.0 ± 18.7 years, p<0.0001). In men, occurrence was highest at 16-20 yrs of age, with a linear decline to elderliness (r=-0.95, p<0.0001). By contrast, myocarditis affected women more evenly at all ages with highest occurrence at the age of 56-60 years. Myocarditis caused 0.19% (95% CI 0.18% to 0.19%) of all medical admissions, and 0.48% (95% CI 0.46% to 0.49%) of admissions due to cardiovascular reasons with an inverse logarithmic association with age (r=-0.97, p<0.0001). Admissions were more commonly caused by myocarditis in men (risk ratio 3.11; 95% CI 2.87 to 3.38, p<0.0001).

CONCLUSIONS

Men are significantly more susceptible to myocarditis than women. Young men are especially at risk for acquiring myocarditis, while women are affected most commonly at the postmenopausal age. The proportion of hospital admissions caused by myocarditis has an inverse, logarithmic association with age.