Autoimmunity Against the Heart and Cardiac Myosin in Children With Myocarditis

Safety of COVID-19 Vaccines in Patients with Autoimmune Diseases, in Patients with Cardiac Issues, and in the Healthy Population

The coronavirus disease 2019 (COVID-19) has been a challenge for the whole world since the beginning of 2020, and COVID-19 vaccines were considered crucial for disease eradication. Instead of producing classic vaccines, some companies pointed to develop products that mainly function by inducing, into the host, the production of the antigenic protein of SARS-CoV-2 called Spike, injecting an instruction based on RNA or a DNA sequence. Here, we aim to give an overview of the safety profile and the actual known adverse effects of these products in relationship with their mechanism of action. We discuss the use and safety of these products in at-risk people, especially those with autoimmune diseases or with previously reported myocarditis, but also in the general population. We debate the real necessity of administering these products with unclear long-term effects to at-risk people with autoimmune conditions, as well as to healthy people, at the time of omicron variants. This, considering the existence of therapeutic interventions, much more clearly assessed at present compared to the past, and the relatively lower aggressive nature of the new viral variants.

Compensatory Upregulation of Anti-Beta-Adrenergic Receptor Antibody Levels Might Prevent Heart Failure Presentation in Pediatric Myocarditis

BACKGROUND

Myocarditis can be associated with severe heart failure and is caused by different inflammatory and autoimmune responses. The aim of this study was to describe the immunological response in children with myocarditis by analyzing anti-beta-adrenergic receptor antibodies (anti-β-AR Abs).

METHODS

Sera of children who were hospitalized with biopsy-proven myocarditis were prospectively collected between April 2017 and March 2019. Anti-β1-AR Ab, anti-β2-AR Ab, and anti-β3-AR Ab were quantified by a CE-certified ELISA kit. According to normal values for immunoglobulin G (IgG), three age groups, <1, 1-5, and >5-17 years, were defined. Children without inflammatory cardiac pathology and no heart failure signs were served as a control group.

RESULTS

We compared 22 patients with biopsy-proven myocarditis and 28 controls. The median age (interquartile range) of the myocarditis group (MYC) was 12.1 (2.7-16.4) years, 13 men, left ventricular ejection fraction (LVEF) 51% and for control group, the median age was 5.0 (3.0-6.8) years, nine men, LVEF 64%. Myocarditis patients in the age group >5-17 years showed significantly higher anti-β3-AR Ab levels as compared to controls (p = 0.014). Lower anti-β2-AR Ab and anti-β3-AR Ab levels were significantly correlated with higher left ventricular diameters in myocarditis patients. The event-free survival using a combined endpoint (mechanical circulatory support [MCS], transplantation, and/or death) was significantly lower in myocarditis patients with antibody levels below the median as compared to myocarditis patients with antibody levels ≥ the median.

CONCLUSION

Anti-β-AR Ab levels are increased in children with myocarditis and >5 years of age. These antibodies might be upregulated compensatory to prevent further cardiac deterioration. A worse event-free survival in patients with lower anti-β-AR Ab levels might be a therapeutic target for immunoglobulin substitution.

Acute myocarditis with autoimmune features: one-year follow-up with CMR

In this prospective study on patients with acute myocarditis (AM), we aimed to describe the new concept of AMAF (AM with autoimmune features) similar to the previously described interstitial pneumonia with autoimmune features (IPAF). IPAF has recently emerged as a new entity, and IPAF patients appear to have fewer episodes of exacerbation and better survival than patients with idiopathic pulmonary fibrosis. Consecutive patients with infarct-like CMR-confirmed AM were classified AMAF if their serologic status measured from blood sampled at presentation was positive (antinuclear antibodies (ANA) ≥ 1:320), but without meeting established classification criteria for connective tissue disease (CTD). The myocardial tissue abnormalities and their progression were assessed on cardiac magnetic resonance (CMR) within 7 days following symptom onset and at 1 year according to their seropositivity. Among the 64 AM patients included, seven presented AMAF (11%). At baseline CMR, patients with AMAF had half as much late gadolinium enhancement (LGE) as seronegative AM patients (4.41% (1.47-4.41) of myocardial volume versus 8.82% (5.88-14.71), p = 0.01, respectively). At 1-year of follow-up, persistent myocardial scarring was less frequent in AMAF patients (n = 2 (28.6%) than seronegative AM patients (n = 38 (66.7%) (p = 0.021). AMAF, diagnosed as seropositive AM without a specific autoimmune disease, is not rare and is associated with less extensive LGE in the acute phase. In addition, AMAF patients had more favorable outcomes on 12-month CMR. Prospective studies are needed to address the clinical significance of this new concept and its long-term cardiovascular impact.

The role of B cells in heart failure and implications for future immunomodulatory treatment strategies

Despite numerous demonstrations that the immune system is activated in heart failure, negatively affecting patients' outcomes, no definitive treatment strategy exists directed to modulate the immune system. In this review, we present the evidence that B cells contribute to the development of hypertrophy, inflammation, and maladaptive tissue remodelling. B cells produce antibodies that interfere with cardiomyocyte function, which culminates as the result of recruitment and activation of a variety of innate and structural cell populations, including neutrophils, macrophages, fibroblasts, and T cells. As B cells appear as active players in heart failure, we propose here novel immunomodulatory therapeutic strategies that target B cells and their products.

Severe heart failure and the need for mechanical circulatory support and heart transplantation in pediatric patients with myocarditis: Results from the prospective multicenter registry "MYKKE"

Myocarditis represents an important cause for acute heart failure. MYKKE, a prospective multicenter registry of pediatric patients with myocarditis, aims to gain knowledge on courses, diagnostics, and therapy of pediatric myocarditis. The role of mechanical circulatory support (MCS) in children with severe heart failure and myocarditis is unclear. The aim of this study was to determine characteristics and outcome of patients with severe heart failure requiring MCS and/or heart transplantation. The MYKKE cohort between September 2013 and 2016 was analyzed. A total of 195 patients were prospectively enrolled by 17 German hospitals. Twenty-eight patients (14%) received MCS (median 1.5 years), more frequently in the youngest age group (0-2 years) than in the older groups (P < 0.001; 2-12 and 13-18 years). In the MCS group, 50% received a VAD, 36% ECMO, and 14% both, with a survival rate of 79%. The weaning rate was 43% (12/28). Nine (32%) patients were transplanted, one had ongoing support, and six (21%) died. Histology was positive for myocarditis in 63% of the MCS group. Patients within the whole cohort with age <2 years and/or ejection fraction <30% had a significantly worse survival with high risk for MCS, transplantation, and death (P < 0.001). Myocarditis represents a life-threatening disease with an overall mortality of 4.6% in this cohort. The fulminant form more often affected the youngest, leading to significantly higher rate of MCS, transplantation, and mortality. MCS represents an important and life-saving therapeutic option in children with myocarditis with a weaning rate of 43%.

Regulatory Role of CD4+ T Cells in Myocarditis

Myocarditis is an important cause of heart failure in young patients. Autoreactive, most often, infection-triggered CD4⁺ T cells were confirmed to be critical for myocarditis induction. Due to a defect in clonal deletion of heart-reactive CD4⁺ T cells in the thymus of mice and humans, significant numbers of heart-specific autoreactive CD4⁺ T cells circulate in the blood. Normally, regulatory T cells maintain peripheral tolerance and prevent spontaneous myocarditis development. In the presence of tissue damage and innate immune activation, however, activated self-antigen-loaded dendritic cells promote CD4⁺ effector T cell expansion and myocarditis. So far, a direct pathogenic role has been described for both activated Th17 and Th1 effector CD4⁺ T cell subsets, though Th1 effector T cell-derived interferon-gamma was shown to limit myocarditis severity and prevent transition to inflammatory dilated cardiomyopathy. Interestingly, recent observations point out that various CD4⁺ T cell subsets demonstrate high plasticity in maintaining immune homeostasis and modulating disease phenotypes in myocarditis. These subsets include Th1 and Th17 effector cells and regulatory T cells, despite the fact that there are still sparse and controversial data on the specific role of FOXP3-expressing Treg in myocarditis. Understanding the specific roles of these T cell populations at different stages of the disease progression might provide a key for the development of successful therapeutic strategies.

Roles of Host Immunity in Viral Myocarditis and Dilated Cardiomyopathy

The pathogenesis of viral myocarditis includes both the direct damage mediated by viral infection and the indirect lesion resulted from host immune responses. Myocarditis can progress into dilated cardiomyopathy that is also associated with immunopathogenesis. T cell-mediated autoimmunity, antibody-mediated autoimmunity (autoantibodies), and innate immunity, working together, contribute to the development of myocarditis and dilated cardiomyopathy.

Streptococcus mutans antigen I/II and autoimmunity in cardiovascular diseases

Infectious pathogens from the oral cavity cause oral diseases such as caries, gingivitis, periodontitis, endodontic infections, and alveolar osteitis, and often are also concomitant to systemic diseases, including cardiovascular disorders, stroke, preterm birth, diabetes, and pneumonia, among others. The relationship(s) between oral infections and systemic diseases are still unclear. Using the bacterial cell surface antigen I/II from S. mutans and cardiovascular diseases as a model, this study analyzes peptide commonalities that might underlie autoimmune crossreactions between the bacterial antigen and human proteins associated with cardiovascular disorders. The study outlines a vast peptide sharing that calls attention on autoimmune crossreactivity as a possible mechanism by which S. mutans infection might contribute to induce cardiovascular diseases, and, more in general, offers a new approach to investigate the still elusive molecular links between focal oral infections and human systemic diseases.