Roles of Host Immunity in Viral Myocarditis and Dilated Cardiomyopathy

Viral myocarditis: From molecular mechanisms to therapeutic prospects

Myocarditis is characterized as local or diffuse inflammatory lesions in the myocardium, primarily caused by viruses and other infections. It is a common cause of sudden cardiac death and dilated cardiomyopathy. In recent years, the global prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the widespread vaccination have coincided with a notable increase in the number of reported cases of myocarditis. In light of the potential threat that myocarditis poses to global public health, numerous studies have sought to elucidate the pathogenesis of this condition. However, despite these efforts, effective treatment strategies remain elusive. To collate the current research advances in myocarditis, and thereby provide possible directions for further research, this review summarizes the mechanisms involved in viral invasion of the organism and primarily focuses on how viruses trigger excessive inflammatory responses and in result in different types of cell death. Furthermore, this article outlines existing therapeutic approaches and potential therapeutic targets for the acute phase of myocarditis. In particular, immunomodulatory treatments are emphasized and suggested as the most extensively studied and clinically promising therapeutic options.

Effect of Yangxin Huoxue Jiedu recipe on inflammatory factors and oxidative stress on viral myocarditis in children

OBJECTIVE

This observation purposed to investigate the effect of the Yangxin Huoxue Jiedu formula on children with viral myocarditis and its effect on inflammatory factors and oxidative response.

MATERIALS AND METHODS

A total of 121 children with viral myocarditis were randomly divided into two groups, namely the control group (N = 60) and the traditional Chinese medicine group (N = 61). The control group was mainly treated with routine therapy, while the traditional Chinese medicine group was treated with Yangxin Huoxue Jiedu recipes based on the control group. The creatine kinase, creatine kinase myocardial isoenzyme, aspartate aminotransferase, lactic dehydrogenase, hydroxybutyrate dehydrogenase, cardiac troponin I, brain natriuretic peptide, interleukin-6, interleukin-8, and tumour necrosis factor-alpha, superoxide dismutase and malondialdehyde in viral myocarditis patients were tested to estimate the myocardial function, inflammation, and oxidative situation.

RESULTS

After Yangxin Huoxue Jiedu treatment, 15 cases were recovered, 20 were excellent, and 21 were effective, which had a significant difference from the control group. The concentration of creatine kinase, creatine kinase myocardial isoenzyme, aspartate aminotransferase, lactic dehydrogenase, hydroxybutyrate dehydrogenase, cardiac troponin I and brain natriuretic peptide was decreased in the traditional Chinese medicine group. The levels of interleukin-6, interleukin-8, and tumour necrosis factor-alpha in the traditional Chinese medicine group were significantly lower than those in the control group. Superoxide dismutase was higher and malondialdehyde was lower than those in the control group.

CONCLUSION

The use of Yangxin Huoxue Jiedu in the treatment of viral myocarditis has a definite clinical effect, which could improve myocardial function, reduce body inflammation, and promote oxidative recovery.

Advances in the mechanism of inflammasomes activation in herpes virus infection

Herpesviruses, prevalent DNA viruses with a double-stranded structure, establish enduring infections and play a part in various diseases. Despite their deployment of multiple tactics to evade the immune system, both localized and systemic inflammatory responses are triggered by the innate immune system's recognition of them. Recent progress has offered more profound understandings of the mechanisms behind the activation of the innate immune system by herpesviruses, specifically through inflammatory signaling. This process encompasses the initiation of an intracellular nucleoprotein complex, the inflammasome associated with inflammation.Following activation, proinflammatory cytokines such as IL-1β and IL-18 are released by the inflammasome, concurrently instigating a programmed pathway for cell death. Despite the structural resemblances between herpesviruses, the distinctive methods of inflammatory activation and the ensuing outcomes in diseases linked to the virus exhibit variations.The objective of this review is to emphasize both the similarities and differences in the mechanisms of inflammatory activation among herpesviruses, elucidating their significance in diseases resulting from these viral infections.Additionally, it identifies areas requiring further research to comprehensively grasp the impact of this crucial innate immune signaling pathway on the pathogenesis of these prevalent viruses.

Repurposing of rituximab biosimilars to treat B cell mediated autoimmune diseases

Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off-label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off-label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune-related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.

Construction and evaluation of immune-related diagnostic model in patients with heart failure caused by idiopathic dilated cardiomyopathy

OBJECTIVE

The purpose of the study was to construct the potential diagnostic model of immune-related genes during the development of heart failure caused by idiopathic dilated cardiomyopathy.

METHOD

GSE5406 and GSE57338 were downloaded from the GEO website ( https://www.ncbi.nlm.nih.gov/geo/ ). CIBERSORT was used for the evaluation of immune infiltration in idiopathic dilated cardiomyopathy (DCM) of GSE5406. Differently expressed genes were calculated by the limma R package and visualized by the volcano plot. The immune-related genes were downloaded from Immport, TISIDB, and InnateDB. Then the immune-related differential genes (IRDGs) were acquired from the intersection. Protein-protein interaction network (PPI) and Cytoscape were used to visualize the hub genes. Three machine learning methods such as random forest, logical regression, and elastic network regression model were adopted to construct the prediction model. The diagnostic value was also validated in GSE57338.

RESULTS

Our study demonstrated the obvious different ratio of T cell CD4 memory activated, T cell regulatory Tregs, and neutrophils between DCM and control donors. As many as 2139 differential genes and 274 immune-related different genes were identified. These genes were mainly enriched in lipid and atherosclerosis, human cytomegalovirus infection, and cytokine-cytokine receptor interaction. At the same time, as many as fifteen hub genes were identified as the IRDGs (IFITM3, IFITM2, IFITM1, IFIT3, IFIT1, HLA-A, HLA-B, HLA-C, ADAR, STAT1, SAMHD1, RSAD2, MX1, ISG20, IRF2). Moreover, we also discovered that the elastic network and logistic regression models had a higher diagnostic value than that of random forest models based on these hub genes.

CONCLUSION

Our study demonstrated the pivotal role of immune function during the development of heart failure caused by DCM. This study may offer new opportunities for the detection and intervention of immune-related DCM.

Integrating scRNA-seq to explore novel macrophage infiltration-associated biomarkers for diagnosis of heart failure

OBJECTIVE

Inflammation and immune cells are closely intertwined mechanisms that contribute to the progression of heart failure (HF). Nonetheless, there is a paucity of information regarding the distinct features of dysregulated immune cells and efficient diagnostic biomarkers linked with HF. This study aims to explore diagnostic biomarkers related to immune cells in HF to gain new insights into the underlying molecular mechanisms of HF and to provide novel perspectives for the detection and treatment of HF.

METHOD

The CIBERSORT method was employed to quantify 22 types of immune cells in HF and normal subjects from publicly available GEO databases (GSE3586, GSE42955, GSE57338, and GSE79962). Machine learning methods were utilized to screen for important cell types. Single-cell RNA sequencing (GSE145154) was further utilized to identify important cell types and hub genes. WGCNA was employed to screen for immune cell-related genes and ultimately diagnostic models were constructed and evaluated. To validate these predictive results, blood samples were collected from 40 normal controls and 40 HF patients for RT-qPCR analysis. Lastly, key cell clusters were divided into high and low biomarker expression groups to identify transcription factors that may affect biomarkers.

RESULTS

The study found a noticeable difference in immune environment between HF and normal subjects. Macrophages were identified as key immune cells by machine learning. Single-cell analysis further showed that macrophages differed dramatically between HF and normal subjects. This study revealed the existence of five subsets of macrophages that have different differentiation states. Based on module genes most relevant to macrophages, macrophage differentiation-related genes (MDRGs), and DEGs in HF and normal subjects from GEO datasets, four genes (CD163, RNASE2, LYVE1, and VSIG4) were identified as valid diagnostic markers for HF. Ultimately, a diagnostic model containing two hub genes was constructed and then validated with a validation dataset and clinical samples. In addition, key transcription factors driving or maintaining the biomarkers expression programs were identified.

CONCLUSION

The analytical results and diagnostic model of this study can assist clinicians in identifying high-risk individuals, thereby aiding in guiding treatment decisions for patients with HF.

ET-1 receptor type B (ETBR) overexpression associated with ICAM-1 downregulation leads to inflammatory attenuation in experimental autoimmune myocarditis

Background

An experimental autoimmune myocarditis rat model was established by subcutaneous injection of porcine myocardial myosin (PCM). The effect of ET-1 receptor type B (ETBR) overexpression on autoimmune myocarditis was observed via tail vein injection of ETBR overexpression lentivirus in rats. We further investigated the mechanisms involved in the regulation of autoimmune myocarditis by ETBR overexpression.

Methods

Six rats were randomly selected from 24 male Lewis rats as the NC group, and the remaining 18 rats were injected with PCM on Day 0 and Day 7, to establish the experimental autoimmune myocarditis (EAM) rat model. The 18 rats initially immunized were randomly divided into three groups: the EAM group, ETBR-oe group, and GFP group. On Day 21 after the initial immunization of rats, cardiac echocardiography and serum brain natriuretic peptide (BNP) analysis were performed to evaluate cardiac function, myocardial tissue HE staining was performed to assess myocardial tissue inflammatory infiltration and the myocarditis score, and mRNA expression of IFN-γ, IL-12, and IL-17 was detected by qRT-PCR. Subsequently, immunohistochemical analysis was performed to detect the localization and expression of the ETBR and ICAM-1 proteins, and the expression of ETBR and ICAM-1 was verified by qRT-PCR and western blotting methods.

Results

On Day 21 after initial immunization, left ventricular end-diastolic diameter (LVEDd), left ventricular end-systolic diameter (LVEDs), and serum BNP concentrations increased in the hearts of rats in the EAM group compared with the NC group (P < 0.01), and ejection fraction (EF) and fractional shortening (FS) decreased compared with those of the normal control (NC) group (P < 0.01). LVEDd, LVEDs, and serum BNP concentrations decreased in the ETBR-oe group compared with the EAM group, while EF and FS increased significantly (P < 0.01). HE staining showed that a large number of inflammatory cell infiltrates, mainly lymphocytes, were observed in the EAM group, and the myocarditis score was significantly higher than that of the NC group (P < 0.01). Compared with that of the EAM group, myocardial tissue inflammatory cell infiltration was significantly reduced in the ETBR-oe group, and the myocarditis scores were significantly lower (P < 0.01). The mRNAs of the inflammatory factors IFN-γ, IL-12 and IL-17 in myocardial tissue of rats in the EAM group exhibited elevated levels compared with those of the NC group (P < 0.01) while the mRNAs of IFN-γ, IL-12 and IL-17 were significantly decreased in the ETBR-oe group compared with the EAM group (P < 0.01). Immunohistochemistry showed that the staining depth of ETBR protein in myocardial tissue was greater in the EAM group than in the NC group, and significantly greater in the ETBR-oe group than in the EAM group, while the staining depth of ICAM-1 was significantly greater in the EAM group than in the NC group, and significantly lower in the ETBR-oe group than in the EAM group. The ICAM-1 expression level was significantly higher in the EAM group than in the NC group (P < 0.01), and was significantly lower in the ETBR-oe groupthan in the EAM group (P < 0.01).

m6A regulator-mediated RNA methylation modification remodels immune microenvironment in dilated cardiomyopathy

The latest evidence suggested that the onset of dilated cardiomyopathy (DCM) is closely associated with immune microenvironment disturbance. Since N6 -methyladenosine (m6A) RNA methylation impacts on immunocyte function and antitumor immunity, it is predictable that m6A RNA methylation may result in immune microenvironment disorder. Here, we attempted to verify this hypothesis. We used single-sample gene set enrichment analysis (ssGSEA) to investigate the infiltration abundance of immunocytes, single-cell RNA-Seq to identify key m6A regulator, and a doxorubicin (Dox)-induced DCM mouse model to confirm our findings. ssGSEA revealed a higher infiltration abundance of CD8+ T lymphocytes, NK cells, monocytes, and B+ lymphocytes in DCM myocardium tissue. Single-cell RNA-Seq indicated a critical role of IGFBP2 in DCM. Cross-checking analysis hinted an interaction between IGFBP2 and NSUN5, ALYREF, RRP8, and ALKBH3. Mechanically, IGFBP2-mediated RNA methylation deteriorated the immune microenvironment and thus increased the risk of DCM by enhancing CD8+ T lymphocyte, NK cell, monocyte, B+ lymphocyte infiltration and activating check-point, MHC-I, and T cell co-stimulation signaling pathways. In the DCM mouse model, echocardiography indicated a significant reduction in ejection fraction (EF) and fractional shortening (FS) and an increase in left ventricular internal dimensions at systole (LVIDs) and diastole (LVIDd). MASSON staining indicated an increased fibrosis in myocardium tissue. qPCR and immunofluorescence staining indicated a significant increase in mRNA and protein levels of IGFBP2. The present study indicated that IGFBP2-mediated RNA methylation remodeled the immune microenvironment and increased the risk of DCM. IGFBP2 may serve as potential therapeutic target for DCM.

Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice

Myocarditis is an inflammatory disease of the myocardium caused by infectious or non-infectious agents. It can lead to serious short-term and long-term sequalae, such as sudden cardiac death or dilated cardiomyopathy. Due to its heterogenous clinical presentation and disease course, challenging diagnosis and limited evidence for prognostic stratification, myocarditis poses a great challenge to clinicians. As it stands, the pathogenesis and etiology of myocarditis is only partially understood. Moreover, the impact of certain clinical features on risk assessment, patient outcomes and treatment options is not entirely clear. Such data, however, are essential in order to personalize patient care and implement novel therapeutic strategies. In this review, we discuss the possible etiologies of myocarditis, outline the key processes governing its pathogenesis and summarize best available evidence regarding patient outcomes and state-of-the-art therapeutic approaches.

Viral Heart Disease: Diagnosis, Management, and Mechanisms

"Viral heart disease" is a term encompassing numerous virus-triggered heart conditions, wherein cardiac myocytes are injured, causing contractile dysfunction, cell death, or both. Cardiotropic viruses may also damage interstitial cells and vascular cells. Clinical presentation of the disorder varies widely. In most cases, patients are asymptomatic. Presentation includes-but is not limited to-flu-like symptoms, chest pain, cardiac arrhythmias, heart failure, cardiogenic shock, and sudden cardiac death. Laboratory studies, including blood-based heart injury indicators and cardiac imaging, may be needed. Management of viral heart disease requires a graded approach. Watchful observation at home may be the first step. Closer observation, with additional testing such as echocardiography in the clinic or hospital is less common yet may inform the use of cardiac magnetic resonance imaging. Intensive care may be indicated in severe acute illness. Viral heart disease mechanisms are complex. Initially, damage is predominantly virus mediated, whereas, in the second week, immune responses bring unintended obverse consequences for the myocardium. Innate immunity is largely beneficial in initial attempts to quell viral replication, whereas adaptive immunity brings helpful and antigen-specific mechanisms to fight the pathogen but also introduces the capability of autoimmunity. Each cardiotropic virus family has its own pathogenesis signature, including attack on myocytes, vascular cells, and other constitutive cells of myocardial interstitium. The stage of disease and preponderant viral pathways lend opportunities for potential intervention but also the likelihood of uncertainty about management. Overall, this review provides a novel glimpse into the depth of and need for solutions in viral heart disease.

Reappraising the role of chronic inflammatory burden in heart failure

BACKGROUND

Heart failure (HF) is a clinical syndrome associated with poor quality of life, substantial utilization of health care resources, and premature mortality. It is now considered to be the most urgent unmet medical need in the field of cardiovascular disease. Accumulated evidence suggested that comorbidity-driven inflammation has emerged as a critical component of HF pathogenesis. Although anti-inflammatory therapies have increased in popularity, very few effective treatments are still available. A comprehensive understanding of the interplay between chronic inflammation and its impact on HF will facilitate the identification of future therapeutic targets.

METHODS

A two-sample Mendelian randomization study was conducted to assess the association between genetic liability for chronic inflammation and HF. By analyzing functional annotations and enrichment data, we were able to identify common pathophysiological mechanisms.

RESULTS

The present study did not provide evidence for chronic inflammation as the cause of HF and the reliability of the results was enhanced by the other three Mendelian randomization analysis methods. Functional annotations of genes and pathway enrichment analyses have indicated that chronic inflammation and HF share a common pathophysiology.

CONCLUSIONS

The associations between chronic inflammation and cardiovascular disease from observational studies may be explained by shared risk factors and comorbidities rather than direct effects.

Inhibitor of CD147 Suppresses T Cell Activation and Recruitment in CVB3-Induced Acute Viral Myocarditis

Viral myocarditis (VMC) is a common disease characterized by cardiac inflammation. AC-73, an inhibitor of CD147, disrupts the dimerization of CD147, which participates in the regulation of inflammation. To explore whether AC-73 could alleviate cardiac inflammation induced by CVB3, mice were injected intraperitoneally with AC-73 on the fourth day post-infection (dpi) and sacrificed on the seventh dpi. Pathological changes in the myocardium, T cell activation or differentiation, and expression of cytokines were analyzed using H&E staining, flow cytometry, fluorescence staining and multiplex immunoassay. The results showed that AC-73 alleviated cardiac pathological injury and downregulated the percentage of CD45⁺CD3⁺ T cells in the CVB3-infected mice. The administration of AC-73 reduced the percentage of activated CD4⁺ and CD8⁺ T cells (CD69⁺ and/or CD38⁺) in the spleen, while the percentage of CD4⁺ T cell subsets in the spleen was not changed in the CVB3-infected mice. In addition, the infiltration of activated T cells (CD69⁺) and macrophages (F4/80⁺) in the myocardium also decreased after the AC-73 treatment. The results also showed that AC-73 inhibited the release of many cytokines and chemokines in the plasma of the CVB3-infected mice. In conclusion, AC-73 mitigated CVB3-induced myocarditis by inhibiting the activation of T cells and the recruitment of immune cells to the heart. Thus, CD147 may be a therapeutic target for virus-induced cardiac inflammation.

Myocarditis: causes, mechanisms, and evolving therapies

INTRODUCTION

Myocarditis is a severe lymphocyte-mediated inflammatory disorder of the heart, mostly caused by viruses and immune checkpoint inhibitors (ICIs). Recently, myocarditis as a rare adverse event of mRNA vaccines for SARS-CoV-2 has caused global attention. The clinical consequences of myocarditis can be very severe, but specific treatment options are lacking or not yet clinically proven.

AREAS COVERED

This paper offers a brief overview of the biology of viruses that frequently cause myocarditis, focusing on mechanisms important for viral entry and replication following host infection. Current and new potential therapeutic targets/strategies especially for viral myocarditis are reviewed systematically. In particular, the immune system in myocarditis is dissected with respect to infective viral and non-infective, ICI-induced myocarditis.

EXPERT OPINION

Vaccination is an excellent emerging preventative strategy for viral myocarditis, but most vaccines still require further development. Anti-viral treatments that inhibit viral replication need to be considered following viral infection in host myocardium, as lower viral load reduces inflammation severity. Understanding how the immune system continues to damage the heart even after viral clearance will define novel therapeutic targets/strategies. We propose that viral myocarditis can be best treated using a combination of antiviral agents and immunotherapies that control cytotoxic T cell activity.

COVID-19 Heart Lesions in Children: Clinical, Diagnostic and Immunological Changes

In the beginning of COVID-19, the proportion of confirmed cases in the pediatric population was relatively small and there was an opinion that children often had a mild or asymptomatic course of infection. Our understanding of the immune response, diagnosis and treatment of COVID-19 is highly oriented towards the adult population. At the same time, despite the fact that COVID-19 in children usually occurs in a mild form, there is an incomplete understanding of the course as an acute infection and its subsequent manifestations such as Long-COVID-19 or Post-COVID-19, PASC in the pediatric population, correlations with comorbidities and immunological changes. In mild COVID-19 in childhood, some authors explain the absence of population decreasing T and B lymphocytes. Regardless of the patient's condition, they can have the second phase, related to the exacerbation of inflammation in the heart tissue even if the viral infection was completely eliminated-post infectious myocarditis. Mechanism of myocardial dysfunction development in MIS-C are not fully understood. It is known that various immunocompetent cells, including both resident inflammatory cells of peripheral tissues (for example macrophages, dendritic cells, resident memory T-lymphocytes and so on) and also circulating in the peripheral blood immune cells play an important role in the immunopathogenesis of myocarditis. It is expected that hyperproduction of interferons and the enhanced cytokine response of T cells 1 and 2 types contribute to dysfunction of the myocardium. However, the role of Th1 in the pathogenesis of myocarditis remains highly controversial. At the same time, the clinical manifestations and mechanisms of damage, including the heart, both against the background and after COVID-19, in children differ from adults. Further studies are needed to evaluate whether transient or persistent cardiac complications are associated with long-term adverse cardiac events.

QiShenYiQi pill for myocardial collagen metabolism and apoptosis in rats of autoimmune cardiomyopathy

CONTEXT

QiShenYiQi pill (QSYQ) is a traditional Chinese medicine with a myocardial protective effect.

OBJECTIVE

To explore the effect of QSYQ on myocardial collagen metabolism in rats with autoimmune cardiomyopathy and explore the underlying mechanism from the aspect of apoptosis.

MATERIALS AND METHODS

We established an autoimmune cardiomyopathy model using Lewis rats. The rats were then randomly divided into six groups (n = 8): control, model, 3-methyladenine (15 mg/kg, intraperitoneal injection), QSYQ low-dose (135 mg/kg, gavage), QSYQ medium dose (270 mg/kg, gavage), and QSYQ high-dose (540 mg/kg, gavage) for four weeks. Van Gieson staining was applied for myocardial pathological characteristics, TUNEL fluorescence for myocardial cell apoptosis, enzyme-linked immunosorbent assay (ELISA) for serum PICP, PIIINP, and CTX-I levels, and western blot analysis for type I/III myocardial collagen, Bcl-2, Bax, and caspase-3 proteins.

RESULTS

Results showed that QSYQ (135, 270, or 540 mg/kg) significantly reduced the expression of myocardial type I/III collagen, and concentrations of serum PICP, PIIINP, and CTX-I in rats. Moreover, QSYQ could alleviate myocardial fibrosis more effectively at a higher dose. QSYQ could also inhibit myocardial apoptosis via downregulating Bcl-2 expression, and upregulating Bax and caspase-3 expression levels.

DISCUSSION AND CONCLUSIONS

The QSYQ can improve myocardial collagen metabolism by inhibiting apoptosis, which provides a potential therapeutic approach for autoimmune cardiomyopathy.

The abnormal distribution of peripheral B1 cells and transition B cells in patients with idiopathic dilated cardiomyopathy: a pilot study

Background

The aberrant distribution of peripheral B cell subsets is associated with the pathogenesis of a variety of inflammatory and autoimmune diseases. However, the distribution of peripheral B cell subsets in patients with idiopathic dilated cardiomyopathy (DCM) remains to be elucidated.

Methods

Twenty-seven patients with idiopathic DCM (DCM group), 18 control patients with heart failure (HF group) and 21 healthy individuals (HC group) were included in this study. Peripheral B cell subsets were analysed using multicolour flow cytometry. The plasma β1 adrenergic receptor (β1-AR) autoantibody titre was determined using ELISA. Additionally, clinical features were also collected.

Results

Compared with the HF and HC groups, the percentage of B1 cells was significantly decreased, whereas the percentage of transitional B cells (Tr) was significantly increased in the DCM group. Notably, the percentage of B1 cells was significantly lower in patients with β1-AR autoantibody-positive DCM than in β1-AR autoantibody-negative patients. The correlation analysis showed that the percentage of B1 cells was negatively correlated with N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and positively correlated with the left ventricular ejection fraction in patients with DCM.

Conclusion

As shown in the present study, the percentage of B1 cells in the peripheral blood of patients with idiopathic DCM is abnormally decreased, especially in β1-AR autoantibody-positive patients, while the percentage of Tr cells is significantly increased, indicating that B1 cells and Tr cells may be implicated in the pathogenesis of idiopathic DCM. The decrease in the percentage of B1 cells is directly related to the severity of DCM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02461-8.

Altered Phenotype of Circulating Dendritic Cells and Regulatory T Cells from Patients with Acute Myocarditis

Dendritic cells (DCs) and regulatory T cells (Tregs) play an essential role in myocarditis. However, a particular DC phenotype in this disease has not been assessed. Herein, we aim to evaluate myeloid (mDCs) and plasmacytoid DC (pDC) phenotype, as well as Treg levels from myocarditis patients and healthy controls. Using multiparametric flow cytometry, we evaluated the levels of myeloid DCs (mDCs), plasmacytoid DCs (pDCs), and Tregs in peripheral blood from myocarditis patients (n = 16) and healthy volunteers (n = 16) and performed correlation analysis with clinical parameters through Sperman test. DCs from myocarditis patients showed a higher expression of costimulatory molecules while a diminished expression of the inhibitory receptors, ILT2 and ILT4. Even more, Treg cells from myocarditis patients displayed higher levels of FOXP3 compared to controls. Clinically, the increased levels of mDCs and their higher expression of costimulatory molecules correlate with a worse myocardial function, higher levels of acute phase reactants, and higher cardiac enzymes. This study shows an activating phenotype of circulating DCs from myocarditis patients. This proinflammatory status may contribute to the pathogenesis and immune deregulation in acute myocarditis.

A20 (TNFAIP3) alleviates viral myocarditis through ADAR1/miR-1a-3p-dependent regulation

Objective

To investigate the effect of A20 and how A20 is regulated in viral myocarditis (VMC).

Methods

BABL/C mice, primary neonatal rat cardiomyocytes and H9c2 cells were infected with Coxsackie virus B3 (CVB3) to establish animal and cellular models of VMC. H&E staining revealed the pathologic condition of myocardium. ELISA measured the serum levels of creatine kinase, creatine kinase isoenzyme and cardiac troponin I. The effects of A20, miR-1a-3p and ADAR1 were investigated using gain and loss of function approaches. ELISA measured the levels of IL-6, IL-18 and TNF-α in serum or cell culture supernatant. TUNEL staining and flow cytometry assessed the apoptosis of myocardium and cardiomyocytes, respectively. RNA-binding protein immunoprecipitation and dual-luciferase reporter assays verified the binding between A20 and miR-1a-3p. Co-immunoprecipitation assay verified the binding between ADAR1 and Dicer.

Results

A20 was underexpressed and miR-1a-3p was overexpressed in the myocardium of VMC mice as well as in CVB3-infected cardiomyocytes. Overexpression of A20 suppressed cardiomyocyte inflammation and apoptosis in vivo and in vitro. miR-1a-3p promoted CVB3-induced inflammation and apoptosis in cardiomyocytes by binding to A20. The expression of miR-1a-3p was regulated by ADAR1. ADAR1 promoted the slicing of miR-1a-3p precursor by binding to Dicer.

Conclusion

A20, regulated by ADAR1/miR-1a-3p, suppresses inflammation and cardiomyocyte apoptosis in VMC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02438-z.

Effect of gamma globulin combined with creatine phosphate on viral myocarditis

OBJECTIVE

This study aimed to investigate the effect of gamma globulin (IVIG) and creatine phosphate (CP) on viral myocarditis (VMC).

METHODS

We enrolled 121 young patients with VMC who were admitted in our hospital from February 2017 to September 2018, and divided them into two groups as follows: study group (62 patients, IVIG + CP + routine treatment), and control group (59 patients, conventional treatment). Patient's baseline data, including gender, age, disease course, etiology, cardiac function classification, and severity, were collected. Ejection fraction (EF), fractional shortening (FS), and mitral ratio of peak early to late diastolic filling velocity (E/A ratio) before and after treatment were recorded. These changes include the lactate dehydrogenase, creatine kinase (CK), aspartate aminotransferase, creatine kinase isoenzyme (CK-MB), and cardiac troponin I (CTnI). Furthermore, the changes in immune factors such as CD3⁺, CD4⁺, and CD8⁺ before and after the treatment were determined.

RESULTS

The study group had a significantly higher response rate than the control group (P < 0.05). After treatment, the ejection fraction, fractional shortening, and mitral ratio of peak early-to-late diastolic filling velocity were more significantly improved in the study group than in the control group (P < 0.05). The electrocardiogram (ECG) results of the study group were also significantly better than those of the control group (P < 0.05). The levels of lactate dehydrogenase (LDH), creatine kinase (CK), aspartate aminotransferase (AST), creatine kinase isoenzyme (CK-MB), and cardiac troponin I (CTnI) in the study group were all significantly better than those in the control group (P < 0.05). Symptom recuperation, cardiac function recovery, and ECG and myocardial enzyme normalization were significantly faster in the study group than those in the control group (P < 0.05). The immune factor levels in the study group also significantly improved compared with those before the treatment (P < 0.05). Meanwhile, the adverse reactions in both groups showed no differences (P < 0.05).

CONCLUSION

IVIG combined with CP exhibited better clinical effects and effectively boosted the immune system of patients with VMC.

Vagus nerve plays a pivotal role in CD4+ T cell differentiation during CVB3-induced murine acute myocarditis

Abnormalities in CD4⁺ T cell (Th cell) differentiation play an important role in the pathogenesis of viral myocarditis (VMC). Our previous studies demonstrated that activation of the cholinergic anti-inflammatory pathway (CAP) alleviated the inflammatory response. In addition, we observed that right cervical vagotomy aggravates VMC by inhibiting CAP. However, the vagus nerve’s effect on differentiation of CD4⁺ T cells has not been studied in VMC mice to date. In this study, we investigated the effects of cervical vagotomy and the α7nAChR agonist pnu282987 on CD4⁺ T cell differentiation in a murine myocarditis model (BALB/c) infected with coxsackievirus B3 (CVB3). Splenic CD4⁺ T cells from CVB3-induced mice obtained and cultured to investigate the potential mechanism of CD4⁺ T cell differentiation. Each Th cell subset was analyzed by flow cytometry. Our results showed that right cervical vagotomy increased proportions of Th1 and Th17 cells and decreased proportions of Th2 and Treg cells in the spleen. Vagotomy-induced upregulation of T-bet, Ror-γ, IFN-γ, and IL-17 expression while downregulating the expression of Gata3, Foxp3, and IL-4 in the heart. In addition, we observed upregulated levels of proinflammatory cytokines, aggravated myocardial lesions and cellular infiltration, and worsened cardiac function in VMC mice. Pnu282987 administration reversed these outcomes. Furthermore, vagotomy inhibited JAK2-STAT3 activation and enhanced NF-κB activation in splenic CD4⁺ T cells. The CD4⁺ T cell differentiation was related to JAK2-STAT3 and NF-κB signal pathways. In conclusion, vagus nerve modulates the inflammatory response by regulating CD4⁺ T cell differentiation in response to VMC.

Adaptive immune disorders in hypertension and heart failure: focusing on T-cell subset activation and clinical implications

: Hypertension is a growing health concern worldwide. Established hypertension is a causative factor of heart failure, which is characterized by increased vascular resistance and intractable uncontrolled blood pressure. Hypertension and heart failure have multiple causes and complex pathophysiology but cellular immunity is thought to contribute to the development of both. Recent studies showed that T cells play critical roles in hypertension and heart failure in humans and animals, with various stimuli leading to the formation of effector T cells that infiltrate the cardiovascular wall. Monocytes/macrophages also accumulate in the cardiovascular wall. Various cytokines (e.g. interleukin-6, interleukin-17, interleukin-10, tumor necrosis factor-α, and interferon-γ) released from immune cells of various subtypes promote vascular senescence and elastic laminal degradation as well as cardiac fibrosis and/or hypertrophy, leading to cardiovascular structural alterations and dysfunction. Recent laboratory evidence has defined a link between inflammation and the immune system in initiation and progression of hypertension and heart failure. Moreover, cross-talk among natural killer cells, adaptive immune cells (T cells and B cells), and innate immune cells (i.e. monocytes, macrophages, neutrophils, and dendritic cells) contributes to end-cardiovasculature damage and dysfunction in hypertension and heart failure. Clinical and experimental studies on the diagnostic potential of T-cell subsets revealed that blood regulatory T cells, CD4 cells, CD8 T cells, and the ratio of CD4 to CD8 T cells show promise as biomarkers of hypertension and heart failure. Therapeutic interventions to suppress activation of these cells may prove beneficial in reducing end-organ damage and preventing consequences of cardiovascular failure, including hypertension of heart failure.

COVID-19: Infection or Autoimmunity

The clinical and laboratory features of COVID-19 are reviewed with attention to the immunologic manifestations of the disease. Recent COVID-19 publications describe a variety of clinical presentations including an asymptomatic state, pneumonia, a hemophagocytic lymphohistiocytosis like syndrome, Multisystem Inflammatory Syndrome in Children (MIS-C) but, also called Pediatric Inflammatory Multisystem Syndrome-Toxic Shock (PIMS-TS), Kawasaki Disease, and myocarditis. A common theme amongst multiple reports suggests an overexuberant autoimmune component of the disease but a common pathophysiology to explain the variations in clinical presentation has been elusive. Review of the basic science of other viral induced autoimmune disorders may give clues as to why immunosuppressive and immunomodulating regimens now appear to have some efficacy in COVID-19. Review of the immunopathology also reveals other therapies that have yet to be explored. There is potential use of T cell depleting therapies and possibly anti-CD20 therapy for COVID-19 and clinical research using these medications is warranted.

Inflammatory Cytokines and Chemokines as Therapeutic Targets in Heart Failure

Heart failure exhibits remarkable pathophysiologic heterogeneity. A large body of evidence suggests that regardless of the underlying etiology, heart failure is associated with induction of cytokines and chemokines that may contribute to the pathogenesis of adverse remodeling, and systolic and diastolic dysfunction. The pro-inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 have been extensively implicated in the pathogenesis of heart failure. Inflammatory cytokines modulate phenotype and function of all myocardial cells, suppressing contractile function in cardiomyocytes, inducing inflammatory activation in macrophages, stimulating microvascular inflammation and dysfunction, and promoting a matrix-degrading phenotype in fibroblasts. Moreover, cytokine-induced growth factor synthesis may exert chronic fibrogenic actions contributing to the pathogenesis of heart failure with preserved ejection fraction (HFpEF). In addition to their role in adverse cardiac remodeling, some inflammatory cytokines may also exert protective actions on cardiomyocytes under conditions of stress. Chemokines, such as CCL2, are also upregulated in failing hearts and may stimulate recruitment of pro-inflammatory leukocytes, promoting myocardial injury, fibrotic remodeling, and dysfunction. Although experimental evidence suggests that cytokine and chemokine targeting may hold therapeutic promise in heart failure, clinical translation remains challenging. This review manuscript summarizes our knowledge on the role of TNF-α, IL-1, IL-6, and CCL2 in the pathogenesis of heart failure, and discusses the promises and challenges of targeted anti-cytokine therapy. Dissection of protective and maladaptive cellular actions of cytokines in the failing heart, and identification of patient subsets with overactive or dysregulated myocardial inflammatory responses are required for design of successful therapeutic approaches.

Dysregulated CD4+ T Cells and microRNAs in Myocarditis

Myocarditis is a polymorphic disease complicated with indeterminate etiology and pathogenesis, and represents one of the most challenging clinical problems lacking specific diagnosis and effective therapy. It is caused by a complex interplay of environmental and genetic factors, and causal links between dysregulated microribonucleic acids (miRNAs) and myocarditis have also been supported by recent epigenetic researches. Both dysregulated CD4+ T cells and miRNAs play critical roles in the pathogenesis of myocarditis, and the classic triphasic model of its pathogenesis consists of the acute infectious, subacute immune, and recovery/chronic myopathic phase. CD4+ T cells are key pathogenic factors underlying the development and progression of myocarditis, and the effector and regulatory subsets, respectively, promote and inhibit autoimmune responses. Furthermore, the reciprocal interplay of these subsets influences the pathogenesis as well. Dysregulated miRNAs along with their mRNA and protein targets have been identified in heart biopsies (intracellular miRNAs) and body fluids (circulating miRNAs) during myocarditis. These miRNAs show phase-dependent changes, and correlate with viral infection, immune status, fibrosis, destruction of cardiomyocytes, arrhythmias, cardiac functions, and outcomes. Thus, miRNAs are promising diagnostic markers and therapeutic targets in myocarditis. In this review, we review myocarditis with an emphasis on its pathogenesis, and present a summary of current knowledge of dysregulated CD4+ T cells and miRNAs in myocarditis.

The potential role of interleukin-37 in infectious diseases

Interleukin-37 (IL-37) is a newly introduced cytokine to interleukin-1 family. Many studies have demonstrated that IL-37 owns immunosuppressive effects against both innate and acquired immune responses via inhibition of several inflammatory mediators. Thence, IL-37 has anti-inflammatory action in some diseases including cancer, autoimmune diseases, cardiovascular diseases and infectious diseases. Recent investigations have reported the important role of IL-37 in immunity against viral, bacterial and fungal infections as they prevent inappropriate immune activation and suppress the inflammation induced by these infectious agents. Thus, IL-37 could play a crucial role in protecting host tissues from injury during infections by damping excessive inflammatory reactions. However, the precise roles of IL-37 in infectious diseases remain largely unknown. The current review shed light on the pivotal role of IL-37 in infectious diseases such as the human immunodeficiency virus-1 (HIV-1), viral myocarditis, hepatitis C virus (HCV), hepatitis B virus (HBV), tuberculosis, leprosy, pneumococcal pneumonia, listeria infection, aspergillosis, candidiasis and eumycetoma. In conclusion, this review reported that IL-37 has a crucial role in reducing infection-associated inflammation and has a good impact on inflammation-induced pathology. However, tight regulation that achieved balance between effector immune responses that required for pathogen elimination and limited tissue damage that resulted from excessive inflammation should be existed in the potential IL-37 therapy to prevent clinical complications of a disease.