Targeting anti-beta-1-adrenergic receptor antibodies for dilated cardiomyopathy

Cardiological Challenges Related to Long-Term Mechanical Circulatory Support for Advanced Heart Failure in Patients with Chronic Non-Ischemic Cardiomyopathy

Long-term mechanical circulatory support by a left ventricular assist device (LVAD), with or without an additional temporary or long-term right ventricular (RV) support, is a life-saving therapy for advanced heart failure (HF) refractory to pharmacological treatment, as well as for both device and surgical optimization therapies. In patients with chronic non-ischemic cardiomyopathy (NICM), timely prediction of HF's transition into its end stage, necessitating life-saving heart transplantation or long-term VAD support (as a bridge-to-transplantation or destination therapy), remains particularly challenging, given the wide range of possible etiologies, pathophysiological features, and clinical presentations of NICM. Decision-making between the necessity of an LVAD or a biventricular assist device (BVAD) is crucial because both unnecessary use of a BVAD and irreversible right ventricular (RV) failure after LVAD implantation can seriously impair patient outcomes. The pre-operative or, at the latest, intraoperative prediction of RV function after LVAD implantation is reliably possible, but necessitates integrative evaluations of many different echocardiographic, hemodynamic, clinical, and laboratory parameters. VADs create favorable conditions for the reversal of structural and functional cardiac alterations not only in acute forms of HF, but also in chronic HF. Although full cardiac recovery is rather unusual in VAD recipients with pre-implant chronic HF, the search for myocardial reverse remodelling and functional improvement is worthwhile because, for sufficiently recovered patients, weaning from VADs has proved to be feasible and capable of providing survival benefits and better quality of life even if recovery remains incomplete. This review article aimed to provide an updated theoretical and practical background for those engaged in this highly demanding and still current topic due to the continuous technical progress in the optimization of long-term VADs, as well as due to the new challenges which have emerged in conjunction with the proof of a possible myocardial recovery during long-term ventricular support up to levels which allow successful device explantation.

Synergistic action of organophosphates and COVID-19 on inflammation, oxidative stress, and renin-angiotensin system can amplify the risk of cardiovascular maladies

Organophosphates (OPs) are ubiquitous environmental contaminants, widely used as pesticides in agricultural fields. In addition, they serve as flame-retardants, plasticizers, antifoaming or antiwear agents in lacquers, hydraulic fluids, and floor polishing agents. Therefore, world-wide and massive application of these compounds have increased the risk of unintentional exposure to non-targets including the human beings. OPs are neurotoxic agents as they inhibit the activity of acetylcholinesterase at synaptic cleft. Moreover, they can fuel cardiovascular issues in the form of myocardities, cardiac oedema, arrhythmia, systolic malfunction, infarction, and altered electrophysiology. Such pathological outcomes might increase the severity of cardiovascular diseases which are the leading cause of mortality in the developing world. Coronavirus disease-19 (COVID-19) is the ongoing global health emergency caused by SARS-CoV-2 infection. Similar to OPs, SARS-CoV-2 disrupts cytokine homeostasis, redox-balance, and angiotensin-II/AT₁R axis to promote cardiovascular injuries. Therefore, during the current pandemic milieu, unintentional exposure to OPs through several environmental sources could escalate cardiac maladies in patients with COVID-19.

Long COVID and the Neuroendocrinology of Microbial Translocation Outside the GI Tract: Some Treatment Strategies

Similar to previous pandemics, COVID-19 has been succeeded by well-documented post-infectious sequelae, including chronic fatigue, cough, shortness of breath, myalgia, and concentration difficulties, which may last 5 to 12 weeks or longer after the acute phase of illness. Both the psychological stress of SARS-CoV-2 infection and being diagnosed with COVID-19 can upregulate cortisol, a stress hormone that disrupts the efferocytosis effectors, macrophages, and natural killer cells, leading to the excessive accumulation of senescent cells and disruption of biological barriers. This has been well-established in cancer patients who often experience unrelenting fatigue as well as gut and blood–brain barrier dysfunction upon treatment with senescence-inducing radiation or chemotherapy. In our previous research from 2020 and 2021, we linked COVID-19 to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) via angiotensin II upregulation, premature endothelial senescence, intestinal barrier dysfunction, and microbial translocation from the gastrointestinal tract into the systemic circulation. In 2021 and 2022, these hypotheses were validated and SARS-CoV-2-induced cellular senescence as well as microbial translocation were documented in both acute SARS-CoV-2 infection, long COVID, and ME/CFS, connecting intestinal barrier dysfunction to disabling fatigue and specific infectious events. The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID. To accomplish this goal, we examine the role of intestinal and blood–brain barriers in long COVID and other illnesses typified by chronic fatigue, with a special emphasis on commensal microbes functioning as viral reservoirs. Furthermore, we discuss the role of SARS-CoV-2/Mycoplasma coinfection in dysfunctional efferocytosis, emphasizing some potential novel treatment strategies, including the use of senotherapeutic drugs, HMGB1 inhibitors, Toll-like receptor 4 (TLR4) blockers, and membrane lipid replacement.

Continuous improvement of both hepatic and cardiac dysfunction by sequential plasma exchange in a patient with thyrotoxicosis and cardiogenic shock: a case report indicating the potential role of cardiohepatic interactions during thyroid storm

Background

Thyroid storm (TS) complicated by cardiogenic shock is associated with high mortality due to the high incidence of multiple organ failure. It is recommended that TS patients with hepatic failure undergo plasma exchange (PE) and receive optimal anti-hyperthyroid medications. However, the effect of PE on cardiac dysfunction in TS patients has been unclear.

Case summary

A 46-year-old woman was admitted to our hospital for dyspnoea and tachycardia. She was diagnosed with TS pursuant to Graves' disease complicated by acute decompensated heart failure (ADHF). Cardiac function was remarkably impaired [left ventricular ejection fraction (LVEF) = 15-20%], with rapid atrial fibrillation. Despite the management of both ADHF and hyperthyroidism, cardiogenic shock developed; therefore, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and intra-aortic balloon pumping (IABP) were initiated. Plasma exchange was performed after severe hepatic failure manifested on Day 2. After the first three PE treatments, cardiac and hepatic function improved immediately but deteriorated the next day. The improvement persisted after the fourth PE, and the patient was weaned from VA-ECMO and IABP on Days 10 and 11, respectively. She was discharged on Day 37, and her cardiac function was still normal 1.5 years later.

Discussion

In hyperthyroidism, severe hepatic dysfunction is more likely to occur in patients with acute ADHF than in those without it. Plasma exchange has the potential to improve not only hepatic but also cardiac dysfunction under optimal antithyroid treatment, especially in patients with TS complicated by severe hepatic dysfunction.

The Relationship Between Peripartum Cardiomyopathy and Preeclampsia – Pathogenesis, Diagnosis and Management

Peripartum cardiomyopathy (PPCM) is a condition with an incompletely understood etiology, although many risk factors for this disorder have been mentioned. Preeclampsia (PE) is a rare but undoubtedly very important cause of PPCM. Early recognition and prompt treatment of preeclampsia and peripartum cardiomyopathy are essential to optimize pregnancy outcomes. An extensive manual search of major electronic databases was conducted in November 2021. The following literature review provides a comprehensive discussion of peripartum cardiomyopathy and preeclampsia and quantifies the prevalence of PE in women with PPCM. The authors highlighted aspects such as epidemiology, risk factors, cardiovascular changes, diagnosis and clinical presentation, and management and complications. Accumulating data indicate that both conditions have a similar pathogenesis characterized by vascular abnormalities. In both conditions we can observe an increase in interleukin-6 and gamma interferon, CCL2/MCP1, and decreased SOD activity. sFLT1 (a soluble form of fms-like tyrosine kinase 1), a substance with antiangiogenic and probably cardiotoxic effects, may be important. Preeclampsia and peripartum cardiomyopathy are characterized by recurrence rates that follow a similar pattern in subsequent pregnancies, and mortality remains a concern. Our analysis highlights the need to better understand the co-morbidity of PE and PPCM, and the need to qualify patients for the same clinical trials because of the common origin of these conditions.

Pathogenic Mechanisms Underlying Cirrhotic Cardiomyopathy

Cardiac dysfunction associated with cirrhosis in the absence of preexisting heart disease is a condition known as cirrhotic cardiomyopathy (CCM). Cardiac abnormalities consist of enlargement of cardiac chambers, attenuated systolic and diastolic contractile responses to stress stimuli, and repolarization changes. CCM may contribute to cardiovascular morbidity and mortality after liver transplantation and other major surgeries, and also to the pathogenesis of hepatorenal syndrome. The underlying mechanisms of CCM are poorly understood and as such medical therapy is an area of unmet medical need. The present review focuses on the pathogenic mechanisms responsible for development of CCM. The two major concurrent mechanistic pathways are the inflammatory phenotype due to portal hypertension, and protein/lipid synthetic/metabolic defects due to cirrhosis and liver insufficiency. The inflammatory phenotype arises from intestinal congestion due to portal hypertension, resulting in bacteria/endotoxin translocation into the systemic circulation. The cytokine storm associated with inflammation, particularly TNFα acting via NFκB depresses cardiac function. They also stimulate two evanescent gases, nitric oxide and carbon monoxide which produce cardiodepression by cGMP. Inflammation also stimulates the endocannabinoid CB-1 pathway. These systems inhibit the stimulatory beta-adrenergic contractile pathway. The liver insufficiency of cirrhosis is associated with defective synthesis or metabolism of several substances including proteins and lipids/lipoproteins. The protein defects including titin and collagen contribute to diastolic dysfunction. Other protein abnormalities such as a switch of myosin heavy chain isoforms result in systolic dysfunction. Lipid biochemical changes at the cardiac sarcolemmal plasma membrane result in increased cholesterol:phospholipid ratio and decreased membrane fluidity. Final common pathway changes involve abnormal cardiomyocyte intracellular ion kinetics, particularly calcium. In conclusion, cirrhotic cardiomyopathy is caused by two pathways of cellular and molecular dysfunction/damage due to hepatic insufficiency and portal hypertension.

Sympatho-adrenergic mechanisms in heart failure: new insights into pathophysiology

The sympathetic nervous system is activated in the setting of heart failure (HF) to compensate for hemodynamic instability. However, acute sympathetic surge or sustained high neuronal firing rates activates β-adrenergic receptor (βAR) signaling contributing to myocardial remodeling, dysfunction and electrical instability. Thus, sympatho-βAR activation is regarded as a hallmark of HF and forms pathophysiological basis for β-blocking therapy. Building upon earlier research findings, studies conducted in the recent decades have significantly advanced our understanding on the sympatho-adrenergic mechanism in HF, which forms the focus of this article. This review notes recent research progress regarding the roles of cardiac β2AR or α1AR in the failing heart, significance of β1AR-autoantibodies, and βAR signaling through G-protein independent signaling pathways. Sympatho-βAR regulation of immune cells or fibroblasts is specifically discussed. On the neuronal aspects, knowledge is assembled on the remodeling of sympathetic nerves of the failing heart, regulation by presynaptic α2AR of NE release, and findings on device-based neuromodulation of the sympathetic nervous system. The review ends with highlighting areas where significant knowledge gaps exist but hold promise for new breakthroughs.

Role of Anti-Beta-1-Adrenergic Receptor Antibodies in Cardiac Dysfunction in Patients with Cirrhotic Cardiomyopathy

Cirrhotic cardiomyopathy (CCM) is a recognized complication of cirrhosis and is associated with poor outcomes, especially under challenges such as surgery/liver transplantation. However, the mechanism is not clear, and the treatment is not specific. The present study aimed to evaluate the role of anti-β₁-adrenergic receptor antibodies (anti-β1-AR) in CCM. We enrolled 3 groups: healthy controls, cirrhotic patients without CCM, and patients with CCM. We found that the anti-β1-AR levels in the CCM group were significantly higher than that in the non-CCM group; anti-β1-AR was positively correlated to NT-proBNP, negatively correlated to left ventricular ejection fraction, fractional shortening ((r =  - 0.466, P < 0.05), and the ratio of peak early (E wave) and atrial (A wave) flow velocities (E/A (r =  - 0.475, P < 0.05) in CCM patients. Anti-β1-AR is a useful predictive biomarker for the presence of CCM and eventually may also have therapeutic implications. Clinical Trials Registration: Chinese Clinical Trials No. ChiCTR 2,000,037,730.

Clinical value of detecting autoantibodies against β1-, β2,- and α1-adrenergic receptors in carvedilol treatment of patients with heart failure

Objective

To determine the possible association of anti-β₁-adrenergic receptors (anti-β₁-AR), anti-β₂-AR and anti-α₁-AR with carvedilol treatment in patients with heart failure (HF).

Methods

A total of 267 HF patients were prospectively enrolled. Blood samples were measured by an enzyme-linked immunosorbent assay. All of the patients received carvedilol for their HF. Each patient was followed up for six months and their cardiac function was measured.

Results

The final analysis encompassed 137 patients comprising 65 patients with three autoantibodies (positive group) and 72 patients without all three autoantibodies but with one or two autoantibodies (negative group). The frequency and geometric mean titer of anti-β₁-AR, anti-β₂-AR, and anti-α₁-AR were significantly lower in the group without all three autoantibodies after six months of carvedilol treatment (all P < 0.01; from 100% to 57%, 50%, and 49%, respectively; and from 1: 118, 1: 138, and 1: 130 to 1: 72, 1: 61, and 1: 67, respectively). Furthermore, 28 patients in the positive group demonstrated complete ablation of autoantibodies. In addition, left ventricular remodelling and function was significantly improved by the use of carvedilol combined with the standard treatment regime for six months in the positive group (P < 0.01) when compared to the negative group (P < 0.05).

Conclusions

Carvedilol treatment significantly decreases frequency and geometric mean titer in patients with all three autoantibodies, even up to complete ablation, and significantly improved cardiac function and remodelling. The effect of carvedilol is probably correlated to the presence of all three autoantibodies.

Interactions of antithrombotic herbal medicines with Western cardiovascular drugs

Thrombotic events act as a critical factor that interferes with Cardiovascular Diseases (CVDs), and antithrombotic herbal medicine is a long-standing controversial issue. Although a dispute is involved in their clinical application, all parties unanimously agree that herbal products have been widely used in folk medicine, and their interactions with conventional drugs are of high concern. This study aims to investigate how antithrombotic herbal medicines interact with Western cardiovascular drugs on the molecular level by taking an example of the most frequently used herbal pair, Danshen-Chuanxiong (DS-CX), and to discover more scientific evidence on their potential herb-drug interactions. Network pharmacology (NP), as an analytical approach of a complex system, is used to visualize and compare target profiles of DS-CX and Western cardiovascular drugs, which can be applied to predict common herb-drug targets and to construct a solid context for discussing herb-drug interactions. These interactions are further validated by in vitro assays, while in vivo zebrafish model employed for evaluating an overall pharmacological efficacy of herbal pairs in specific combination ratios. The study finds that DS could react directly to the Western cardiovascular drug targets relevant to antithrombotic pathways (i.e., thrombin, coagulation factor Xa and cyclooxygenase-1), whereas CX could not react directly and can synergistically affect antithrombotic effects with DS in specific combination ratios. Moreover, it is indicated that DS-CX may generate wide biological functions by a complicated mechanism of "neuro-immune-metabolism/endocrine" (NIM), which can further cause multiple direct and indirect interactions with Western cardiovascular drugs. From the clinical perspective, herb-drug interactions should be given high attention, especially when multiple herbs are used simultaneously.

Unmasking features of the auto-epitope essential for β1 -adrenoceptor activation by autoantibodies in chronic heart failure

Aims

Chronic heart failure (CHF) can be caused by autoantibodies stimulating the heart via binding to first and/or second extracellular loops of cardiac β₁‐adrenoceptors. Allosteric receptor activation depends on conformational features of the autoantibody binding site. Elucidating these features will pave the way for the development of specific diagnostics and therapeutics. Our aim was (i) to fine‐map the conformational epitope within the second extracellular loop of the human β₁‐adrenoceptor (β₁EC_II) that is targeted by stimulating β₁‐receptor (auto)antibodies and (ii) to generate competitive cyclopeptide inhibitors of allosteric receptor activation, which faithfully conserve the conformational auto‐epitope.

Methods and results

Non‐conserved amino acids within the β₁EC_II loop (compared with the amino acids constituting the EC_II loop of the β₂‐adrenoceptor) were one by one replaced with alanine; potential intra‐loop disulfide bridges were probed by cysteine–serine exchanges. Effects on antibody binding and allosteric receptor activation were assessed (i) by (auto)antibody neutralization using cyclopeptides mimicking β₁EC_II ± the above replacements, and (ii) by (auto)antibody stimulation of human β₁‐adrenoceptors bearing corresponding point mutations. With the use of stimulating β₁‐receptor (auto)antibodies raised in mice, rats, or rabbits and isolated from exemplary dilated cardiomyopathy patients, our series of experiments unmasked two features of the β₁EC_II loop essential for (auto)antibody binding and allosteric receptor activation: (i) the NDPK^211–214 motif and (ii) the intra‐loop disulfide bond C²⁰⁹↔C²¹⁵. Of note, aberrant intra‐loop disulfide bond C²⁰⁹↔C²¹⁶ almost fully disrupted the functional auto‐epitope in cyclopeptides.

Conclusions

The conformational auto‐epitope targeted by cardio‐pathogenic β₁‐receptor autoantibodies is faithfully conserved in cyclopeptide homologues of the β₁EC_II loop bearing the NDPK^211–214 motif and the C²⁰⁹↔C²¹⁵ bridge while lacking cysteine C²¹⁶. Such molecules provide promising tools for novel diagnostic and therapeutic approaches in β₁‐autoantibody‐positive CHF.

Autoantibodies Against β1-Adrenoceptor Exaggerated Ventricular Remodeling by Inhibiting CTRP9 Expression

Background

Autoantibodies against the second extracellular loop of the β₁‐adrenoceptor (β₁‐AA) act similarly to agonist of β₁‐adrenergic receptor, which plays an important role in the pathophysiological characteristics of ventricular remodeling. Recently, considerable lines of evidence have suggested that CTRP9 (C1q tumor necrosis factor–related protein 9) is a potent cardioprotective cardiokine and protects the heart from ventricular remodeling. The aim of this study was to determine the role of CTRP9 in ventricular remodeling induced by β₁‐AA.

Methods and Results

Blood samples were collected from 131 patients with coronary heart disease and 131 healthy subjects. The serum levels of β₁‐AA and CTRP9 were detected using ELISA. The results revealed that CTRP9 levels in β₁‐AA–positive patients were lower than those in β₁‐AA–negative patients, and serum CTRP9 concentrations were inversely correlated with β₁‐AA. β₁‐AA monoclonal antibodies (β₁‐AAmAbs) were administered in mice with and without rAAV9‐cTnT‐Full Ctrp9‐FLAG virus for 8 weeks. Reverse transcription–polymerase chain reaction/Western analysis showed that cardiomyocyte CTRP9 expression was significantly reduced in β₁‐AAmAb–treated mice. Moreover, compared with the β₁‐AAmAb alone group, cardiac‐specific CTRP9 overexpression improved cardiac function, attenuated adverse remodeling, and ameliorated cardiomyocyte apoptosis and fibrosis. Mechanistic studies demonstrated that CTRP9 overexpression decreased the levels of G‐protein–coupled receptor kinase 2 and promoted the activation of AMP‐dependent kinase pathway. However, cardiac‐specific overexpression of CTRP9 had no effect on the levels of cAMP and protein kinase A activity elevated by β₁‐AAmAb.

Conclusions

This study provides the first evidence that the long‐term existence of β₁‐AAmAb suppresses cardiac CTRP9 expression and exaggerates cardiac remodeling, suggesting that CTRP9 may be a novel therapeutic target against pathologic remodeling in β₁‐AA–positive patients with coronary heart disease.

Diagnostic and prognostic value of autoantibodies against β1-adrenoreceptors in patients with heart failure following acute myocardial infarction: A 5-year prospective study

A number of studies have suggested that autoantibodies against β₁-adrenoreceptors (β₁R-AAbs) have an important role in pathophysiological processes of heart failure. The aim of the present study was to determine whether β₁R-AAbs are implicated in cardiac dysfunction following acute myocardial infarction (AMI) and their association with prognosis. A total of 33 cases with systolic heart failure (SHF), 49 with diastolic heart failure (DHF) and 44 with normal heart function following AMI were recruited. β₁R-AAbs were detected by ELISA and major adverse cardiac events (MACEs) were recorded during the 5-year follow-up. The positive rate of β₁R-AAbs in the SHF group (45.5%) was significantly higher compared with that in the DHF (22.4%; P<0.05) and normal (15.9%; P<0.05) groups. The area under the receiver operating characteristics curve for the diagnosis of SHF was 0.630 (95% CI: 0.514–0.747, P=0.026). During a median follow-up period of 51.0±15.4 months, the positive rate of β₁R-AAbs in the MACEs group was significantly higher compared with that in the non-MACEs group (P<0.05). Multivariate logistic regression analysis indicated that the left ventricular ejection fraction and diabetes were independent predictors of 5-year MACEs following AMI, whereas β₁R-AAbs were not. Kaplan-Meier analysis revealed that the cumulative MACEs-free survival rate was the lowest in the SHF group, followed by the DHF and normal groups (P<0.05). Therefore, β₁R-AAbs were indicated to be of value for early diagnosis of SHF after AMI but not as independent predictors for the prognosis of patients with AMI.

The relationship between β1 -adrenergic and M2 -muscarinic receptor autoantibodies and hypertrophic cardiomyopathy

NEW FINDINGS

What is the central question of this study? The concentrations of β₁ -adrenergic receptor and M₂ -muscarinic receptor autoantibodies in hypertrophic cardiomyopathy (HCM) patients and the relationship between the cardiac autoantibodies and clinical manifestations of HCM have rarely been reported. What is the main finding and its importance? We found that the concentrations of the two autoantibodies in HCM patients were significantly higher than those in control subjects. Furthermore, we found that the concentrations of the two autoantibodies could reflect myocardial injury and diastolic dysfunction in HCM patients to some extent and might be involved in the occurrence of arrhythmia. These findings might be valuable in exploration of the mechanisms of occurrence and progression of HCM.

ABSTRACT

Increasing attention is being given to the role of immunological mechanisms in the development of heart failure. The purpose of this study was to investigate the concentration of serum β₁ -adrenergic receptor autoantibody (β₁ -AAb) and M₂ -muscarinic receptor autoantibody (M₂ -AAb) in patients with hypertrophic cardiomyopathy (HCM), and the relationship between β₁ -AAb, M₂ -AAb and clinical indices. One hundred and thirty-four patients with HCM were recruited consecutively into the HCM group. Forty healthy subjects were assigned as the normal controls (NCs). Serum samples were collected to measure the concentrations of β₁ -AAb and M₂ -AAb by enzyme-linked immunosorbent assay. The clinical data of HCM patients were collected. The serum concentrations of β₁ -AAb and M₂ -AAb of HCM patients were significantly higher than those of NCs. In HCM patients, those with a left atrial diameter ≥50 mm or moderate-to-severe mitral regurgitation had significantly higher concentrations of the two autoantibodies. Patients with a history of syncope had higher concentrations of β₁ -AAb. Female patients and patients with a family history of sudden cardiac death or atrial fibrillation had higher concentrations of M₂ -AAb. Maximal wall thickness, interventricular septum thickness and resting left ventricular outflow tract gradient were positively correlated with log β₁ -AAb or log M₂ -AAb in HCM patients. In conclusion, the serum concentrations of β₁ -AAb and M₂ -AAb of HCM patients were significantly higher than those of NCs. Being female, syncope, a family history of sudden death, atrial fibrillation, left atrial diameter ≥50 mm, moderate-to-severe mitral regurgitation, maximal wall thickness, interventricular septum thickness and resting left ventricular outflow tract gradient may affect the concentrations of the two autoantibodies.

β1-Adrenoreceptor Autoantibodies in Heart Failure: Physiology and Therapeutic Implications

Antibodies that activate the β₁-AR (β₁-adrenoreceptor) can induce heart failure in animal models. These antibodies are often found in patients with heart failure secondary to varying etiologies. Their binding to the β₁ receptor leads to prolonged receptor activation with subsequent induction of cellular dysfunction, apoptosis, and arrhythmias. β-blocker therapy while highly effective for heart failure, may not be sufficient treatment for patients who have β₁ receptor autoantibodies. Removal of these autoantibodies by immunoadsorption has been shown to improve heart failure in small studies. However, immunoadsorption is costly, time consuming, and carries potential risks. An alternative to immunoadsorption is neutralization of autoantibodies through the intravenous application of small soluble molecules, such as peptides or aptamers, which specifically target and neutralize β₁-AR autoantibodies. Peptides may induce immunogenicity. Animal as well as early phase human studies with aptamers have not shown safety concerns to date and have demonstrated effectiveness in reducing autoantibody levels. Novel aptamers have the potential advantage of having a wide spectrum of action, neutralizing a variety of known circulating G-protein coupled receptor autoantibodies. These aptamers, therefore, have the potential to be novel therapeutic option for patients with heart failure who have positive for β₁-AR autoantibodies. However, clinical outcomes trials are needed to assess the clinical utility of this novel approach to treat heart failure.

Small RNA-sequencing identified the potential roles of neuron differentiation and MAPK signaling pathway in dilated cardiomyopathy

Dilated cardiomyopathy is a severe disease characterized by ventricular enlargement and subsequent cardiac dysfunction. MiRNAs plays multiple roles in cardiovascular disease. However, diagnosis values and therapeutic effects of miRNAs in dilated cardiomyopathy are yet poorly understood. In the present study, small RNA-sequencing was employed to identify dysregulated circulating miRNAs in DCM patients compared with healthy controls. A total of 48 dysregulated miRNAs were detected, and 7198 mRNAs, the intersection of predicted mRNAs from both Miranda database and RNAhybrid database, were identified as the target mRNAs of these dysregulated miRNAs. Bioinformatics analysis was performed to identify the potential effects of these dysregulated miRNAs in dilated cardiomyopathy. GO analysis and GO-Tree analysis disclosed that neuron differentiation was potentially the core biological process associated with dilated cardiomyopathy. KEGG analysis and Pathway-Act network showed that mitogen-activated protein kinase (MAPK) signaling pathway was the hub pathway in dilated cardiomyopathy. The dysregulated miRNAs and related target mRNAs in neuron differentiation process and MAPK signaling pathway were also presented in the study. In conclusion, forty-eight dysregulated miRNAs were identified by small RNA-sequencing. Bioinformatics analysis suggested these miRNAs might be involved in the pathogenesis of dilated cardiomyopathy via regulating neuron differentiation process and MAPK signaling pathway.

Autoantibodies for Cardiac Channels and Sudden Cardiac Death and its Relationship to Autoimmune Disorders

Background:

Sudden Cardiac Death (SCD) is an unexpected death caused by heart dys-function. Autoantibodies against cardiac proteins may be potentially involved in the occurrence and progression of cardiac disease and SCD. The first report on the role of autoantibodies in idiopathic dilated cardiomyopathy appeared in the 1980s. In recent years new studies on the effects of the pres-ence of specific autoantibodies and their relationship to ventricular arrhythmias and SCD were pub-lished. The purpose of the current mini-review is to analyze the results of the research studies focused on the relationship between anti-cardiomyocyte autoantibodies and SCD with respect to autoimmune disorders.

Conclusion:

According to our analysis, more research is needed to understand the role of these auto-antibodies against cardiac proteins in the SCD pathogenesis, and potentially employ this knowledge for improving prognosis of SCD.

Cyclic peptide RD808 reduces myocardial injury induced by β1-adrenoreceptor autoantibodies

Autoantibodies against the second extracellular loop of β₁-adrenergic receptor (β₁-AA) have been shown to be involved in the development of cardiovascular diseases. Recently, there has been considerable interest in strategies to remove these autoantibodies, particularly therapeutic peptides to neutralize β₁-AA. Researchers are investigating the roles of cyclic peptides that mimic the structure of relevant epitopes on the β₁-AR-EC_II in a number of immune-mediated diseases. Here, we used a cyclic peptide, namely, RD808, to neutralize β₁-AA, consequently alleviating β₁-AA-induced myocardial injury. We investigated the protective effects of RD808 on the myocardium both in vitro and in vivo. RD808 was found to increase the survival rate of cardiomyocytes; furthermore, it decreased myocardial necrosis and apoptosis and improved the cardiac function of BalB/c mice in a β₁-AA transfer model. In vitro and in vivo experiments showed that myocardial autophagy was increased in the presence of RD808, which might contribute to its cardioprotective effects. Our findings indicate that RD808 reduced myocardial injury induced by β₁-AA.

Stress and Inflammation in Coronary Artery Disease: A Review Psychoneuroendocrineimmunology-Based

Recent findings have deeply changed the current view of coronary heart disease, going beyond the simplistic model of atherosclerosis as a passive process involving cholesterol build-up in the subintimal space of the arteries until their final occlusion and/or thrombosis and instead focusing on the key roles of inflammation and the immune system in plaque formation and destabilization. Chronic inflammation is a typical hallmark of cardiac disease, worsening outcomes irrespective of serum cholesterol levels. Low-grade chronic inflammation correlates with higher incidence of several non-cardiac diseases, including depression, and chronic depression is now listed among the most important cardiovascular risk factors for poor prognosis among patients with myocardial infarction. In this review, we include recent evidence describing the immune and endocrine properties of the heart and their critical roles in acute ischaemic damage and in post-infarct myocardial remodeling. The importance of the central and autonomic regulation of cardiac functions, namely, the neuro-cardiac axis, is extensively explained, highlighting the roles of acute and chronic stress, circadian rhythms, emotions and the social environment in triggering acute cardiac events and worsening heart function and metabolism in chronic cardiovascular diseases. We have also included specific sections related to stress-induced myocardial ischaemia measurements and stress cardiomyopathy. The complex network of reciprocal interconnections between the heart and the main biological systems we have presented in this paper provides a new vision of cardiovascular science based on psychoneuroendocrineimmunology.

Difference between beta1-adrenoceptor autoantibodies of human and animal origin-Limitations detecting beta1-adrenoceptor autoantibodies using peptide based ELISA technology

Cell-based analytics for the detection of the beta1-adrenoceptor autoantibody (beta1-AAB) are functional, yet difficult to handle, and should be replaced by easily applicable, routine lab methods. Endeavors to develop solid-phase-based assays such as ELISA to exploit epitope moieties for trapping autoantibodies are ongoing. These solid-phase-based assays, however, are often unreliable when used with human patient material, in contrast to animal derived autoantibodies. We therefore tested an immunogen peptide-based ELISA for the detection of beta1-AAB, and compared commercially available goat antibodies against the 2^nd extracellular loop of human beta1-adrenoceptor (ADRB1-AB) to autoantibodies enriched from patient material. The functionality of these autoantibodies was tested in a cell based assay for comparison and their structural appearance was investigated using 2D gel electrophoresis. The ELISA showed a limit of detection for ADRB1-AB of about 1.5 nmol antibody/L when spiked in human control serum and only about 25 nmol/L when spiked in species identical (goat) matrix material. When applied to samples of human origin, the ELISA failed to identify the specific beta1-AABs. A low concentration of beta1-AAB, together with structural inconsistency of the patient originated samples as seen from the 2D Gel appearance, might contribute to the failure of the peptide based ELISA technology to detect human beta1-AABs.

Role of Adaptive Immunity in the Development and Progression of Heart Failure: New Evidence

Heart failure (HF) is considered the endpoint of a variety of cardiac diseases, which are the leading cause of death in adults and considered a growing pandemic worldwide. Independent of the initial form of cardiac injury, there is evidence linking the involvement of the immune system. In HF there is evidence of the participation of T_H1, and T_H17 cells, which account for sustained pathological chronic inflammation, cell migration, and the induction of specific pathological phenotypes of mononuclear cells. Of equal or even higher relevance are the B lymphocyte activation mechanisms that include production of pro-inflammatory cytokines, chemokines, and cardiac autoantibodies with or without activation of the complement proteins. Both of these unbalanced T- and B-cell pathways of the adaptive immune system are associated with cardiomyocyte death and tissue remodeling by fibrosis leading to a dysfunctional heart. At this time, therapy with neutralizing antibodies and the use of anti-cytokine immunomodulators to counteract the immune system effects have reached a plateau of mixed results in clinical trials. Nevertheless, recent evidence showed promising results in animal models that suggest that modulation of the adaptive immune system cells more than some of their effector molecules could have benefits in HF patients. This review summarizes the role of the adaptive immunity cells in HF, considering the sustained activation of adaptive immune system as a potential contributor to disease progression in humans and experimental models where its regulation provides a new therapeutic target.

Performance and in-house validation of a bioassay for the determination of beta1-autoantibodies found in patients with cardiomyopathy

Background

Autoantibodies specific for the adrenergic beta1-receptor were identified to be an essential factor for the pathogenesis of dilated cardiomyopathy. For the detection of these autoantibodies, a bioassay was developed and has been used, measuring the positive chronotropic effect on spontaneously beating neonatal rat cardiomyocytes. In order to use this bioassay as an analytical tool to monitor the effectiveness of autoantibody neutralizing therapy in a regulated field, there is a need to assess its analytical performance and validate it according to current guidelines.

Methods

Using standard autoantibody samples, the increased beat rate compared to the basal rate [delta beats/min] was recorded when investigating guideline required assay performance parameters.

Results

The analytical specificity and sensitivity of the bioassay was demonstrated. The limit of detection and positivity cut-off level were determined to be 3.56 and 7.97 delta beats/min, respectively. The coefficient of variation (CV) of all tested single values (four technical replicates each) was ≤15.2%. The CV of precision within each measuring series did not exceed 20%. Furthermore, the sample stability under a variety of different storage conditions was assessed, as well as the robustness of the cardiomyocyte preparations, which were both given.

Conclusion

This bioassay fulfilled guideline determined quality requirements and proved to be appropriate for its application in clinical trials.

Autoantibodies against β1-adrenergic receptor: response to induction therapy with bortezomib-containing regimens for multiple myeloma patients

This study aims to investigate the predictive value of pre-chemotherapy β1R-AABs by evaluating the response of newly diagnosed symptomatic multiple myeloma (MM) patients to their treatment with a bortezomib-containing regimen. Forty-five de novo MM patients and 50 normal controls (NCs) were prospectively enrolled in this study. Serum titers of β1R-AABs were detected by ELISA. These 45 MM patients were divided into two groups (positive and negative groups) according to their β1R-AABs. Follow-up examinations were performed on these patients during chemotherapy induction. The final analysis covered all 45 MM patients, including 19 patients who were positive for MM and 26 patients who were negative for MM. Multivariate analysis revealed that pre-chemotherapy β1R-AABs are possibly independent predictors for less than very good partial response (VGPR) after the bortezomib-containing regimen treatment (odds ratio: 5.967, 95% confidence interval: 1.513-23.531; p = .011). This study demonstrates for the first time that the presence of β1R-AABs is associated with MM. Pre-chemotherapy β1R-AABs are independent predictors for less than VGPR in de novo MM patients after the bortezomib-containing regimen was administrated. Bortezomib might not significantly give rise to cardiac impairment in MM patients.

Molecular mechanisms in cardiomyopathy

Cardiomyopathies represent a heterogeneous group of diseases that negatively affect heart function. Primary cardiomyopathies specifically target the myocardium, and may arise from genetic [hypertrophic cardiomyopathy (HCM), arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D), mitochondrial cardiomyopathy] or genetic and acquired [dilated cardiomyopathy (DCM), restrictive cardiomyopathy (RCM)] etiology. Modern genomics has identified mutations that are common in these populations, while in vitro and in vivo experimentation with these mutations have provided invaluable insight into the molecular mechanisms native to these diseases. For example, increased myosin heavy chain (MHC) binding and ATP utilization lead to the hypercontractile sarcomere in HCM, while abnormal protein–protein interaction and impaired Ca2+ flux underlie the relaxed sarcomere of DCM. Furthermore, expanded access to genetic testing has facilitated identification of potential risk factors that appear through inheritance and manifest sometimes only in the advanced stages of the disease. In this review, we discuss the genetic and molecular abnormalities unique to and shared between these primary cardiomyopathies and discuss some of the important advances made using more traditional basic science experimentation.

Autoantibody profiling on a plasmonic nano-gold chip for the early detection of hypertensive heart disease

The role of autoimmunity in cardiovascular (CV) diseases has been increasingly recognized. Autoimmunity is most commonly examined by the levels of circulating autoantibodies in clinical practices. Measurement of autoantibodies remains, however, challenging because of the deficiency of reproducible, sensitive, and standardized assays. The lack of multiplexed assays also limits the potential to identify a CV-specific autoantibody profile. To overcome these challenges, we developed a nanotechnology-based plasmonic gold chip for autoantibody profiling. This approach allowed simultaneous detection of 10 CV autoantibodies targeting the structural myocardial proteins, the neurohormonal regulatory proteins, the vascular proteins, and the proteins associated with apoptosis and coagulation. Autoantibodies were measured in four groups of participants across the continuum of hypertensive heart diseases. We observed higher levels of all 10 CV autoantibodies in hypertensive subjects (n = 77) compared with healthy participants (n = 30), and the autoantibodies investigated were related to each other, forming a highly linked network. In addition, we established that autoantibodies to troponin I, annexin-A5, and beta 1-adrenegic receptor best discriminated hypertensive subjects with adverse left ventricular (LV) remodeling or dysfunction (n = 49) from hypertensive subjects with normal LV structure and function (n = 28). By further linking these three significant CV autoantibodies to the innate and growth factors, we revealed a positive but weak association between autoantibodies to troponin I and proinflammatory cytokine IL-18. Overall, we demonstrated that this platform can be used to evaluate autoantibody profiles in hypertensive subjects at risk for heart failure.

A standardised FACS assay based on native, receptor transfected cells for the clinical diagnosis and monitoring of β1-adrenergic receptor autoantibodies in human heart disease

BACKGROUND

Autoantibodies against β1-adrenergic receptors (β1AR) that stimulate cardiac cAMP-production play a causal role in the pathogenesis of human heart failure. Patients can be subjected to specific therapies, if the presence of potentially cardio-noxious β1AR-autoantibodies is reliably diagnosed. This requires assessment of IgG-interactions with the native β1AR because β1AR-autoantibodies target a conformational epitope inadequately presented by denatured receptors or linear peptides. Here, we report on a standardised diagnostic procedure for the assessment of β1AR-autoantibodies in heart failure patients, which is based on IgG-binding to native human β1AR.

METHODS

Good laboratory practice (GLP)-conform measurement of β1AR-autoantibodies was based on flow-cytometric quantification of differential IgG-binding to native HT1080 cells overexpressing biofluorescent human β1AR or not. Receptor-specific IgG-binding was derived from IgG-related median fluorescence of β1AR-positive cells corrected for background staining of β1AR-negative cells admixed to each measurement. The slope of IgG binding at two different concentrations was used as measure for the titre/avidity of β1AR-autoantibodies.

RESULTS

Sensitivity and specificity of the novel procedure for high β1AR-autoantibody levels in dilated cardiomyopathy patients (n=40, NYHA class III-IV) relative to n=40 matched healthy subjects was >90%. It was similar to functional assays considered the gold standard and vastly superior to existing screening-procedures employing fixed cells or linear receptor-peptides as auto-antigenic targets. Inter-assay scatter was 7%-15% and linear dilution recovery was within ±10% of expected values throughout.

CONCLUSIONS

The novel assay possibly provides a tool to determine true prevalence and clinical impact of β1AR-autoantibodies. Furthermore, it may serve as companion diagnostic for therapies specifically directed at β1AR-autoantibodies.

High throughput bioassay for beta1-adrenoceptor autoantibody detection

BACKGROUND

While the involvement of adrenergic beta1-autoantibodies (beta1-AABs) in pathogenesis of cardiomyopathies is well established as are the benefits associated with autoantibody removal by immunoapheresis, the development of drugs neutralizing beta1-AABs in-vivo has been slowed due to a lack of high throughput autoantibody analytics. Highly scalable routine diagnostics involving immobilized binding partners have mostly failed in comparison to the laborious bioassays, which are difficult to scale up, but present the most reliable and sensitive tools for detecting the beta1-autoantibodies.

METHODS

A high throughput, image-based assay to measure cardiomyocyte beat rate and contractility was developed and tested for its applicability for detecting adrenergic beta1-autoantibodies. The classical bioassay of spontaneously beating neonatal rat cardiomyocytes was used for comparison.

RESULTS

The high throughout assay using human iPSC-derived cardiomyocytes was able to detect beta1-AAB activity of biological sample material. The results from the high throughput assay were very similar to the data obtained from the original bioassay of spontaneously beating neonatal cardiomyocytes, with one exception, where a control antibody targeting the N-terminal end of the human beta1-receptor induced a response when tested with the high throughput imager, while none was observed by the classical bioassay. This discrepancy may be explained by the differences in host species of cardiomyocytes tested by the two methods.

CONCLUSION

The high throughput system using iPSC-derived cardiomyocytes for the detection of beta1-AAB provides a realistic option to overcome the sample-size limitations of the bioassay-based diagnostics.

Generation of Antigen Microarrays to Screen for Autoantibodies in Heart Failure and Heart Transplantation

Autoantibodies directed against endogenous proteins including contractile proteins and endothelial antigens are frequently detected in patients with heart failure and after heart transplantation. There is evidence that these autoantibodies contribute to cardiac dysfunction and correlate with clinical outcomes. Currently, autoantibodies are detected in patient sera using individual ELISA assays (one for each antigen). Thus, screening for many individual autoantibodies is laborious and consumes a large amount of patient sample. To better capture the broad-scale antibody reactivities that occur in heart failure and post-transplant, we developed a custom antigen microarray technique that can simultaneously measure IgM and IgG reactivities against 64 unique antigens using just five microliters of patient serum. We first demonstrated that our antigen microarray technique displayed enhanced sensitivity to detect autoantibodies compared to the traditional ELISA method. We then piloted this technique using two sets of samples that were obtained at our institution. In the first retrospective study, we profiled pre-transplant sera from 24 heart failure patients who subsequently received heart transplants. We identified 8 antibody reactivities that were higher in patients who developed cellular rejection (2 or more episodes of grade 2R rejection in first year after transplant as defined by revised criteria from the International Society for Heart and Lung Transplantation) compared with those who did have not have rejection episodes. In a second retrospective study with 31 patients, we identified 7 IgM reactivities that were higher in heart transplant recipients who developed antibody-mediated rejection (AMR) compared with control recipients, and in time course studies, these reactivities appeared prior to overt graft dysfunction. In conclusion, we demonstrated that the autoantibody microarray technique outperforms traditional ELISAs as it uses less patient sample, has increased sensitivity, and can detect autoantibodies in a multiplex fashion. Furthermore, our results suggest that this autoantibody array technology may help to identify patients at risk of rejection following heart transplantation and identify heart transplant recipients with AMR.

Discoveries in peripartum cardiomyopathy

The past decade has seen remarkable gains for outcomes in peripartum cardiomyopathy (PPCM), one of the leading causes of maternal mortality and morbidity in the USA and many other countries, including the high-incidence areas of Haiti and South Africa. This review article emphasizes the importance of continuing the process of increasing awareness of PPCM and presents details of this evolving picture, including important discoveries that point the way to full recovery for almost all PPCM subjects. In addition, new interventions will be highlighted, which may facilitate recovery. Numerous studies have demonstrated that when the diagnosis of PPCM is made with LVEF > 0.30, the probability is that recovery to LVEF ≥ 0.50 will occur in the overwhelming majority of subjects. PPCM patients diagnosed with severely depressed systolic function (LVEF < 0.30) and a remodeled left ventricle with greater dilatation (LVEDd ≥ 60mm) are least likely to reach the outcome recovery goals. These are the patients with the greatest need for newer interventional strategies.

Agonistic autoantibodies directed against G-protein-coupled receptors and their relationship to cardiovascular diseases

Agonistic autoantibodies (AABs) against G-protein-coupled receptor (GPCR) are present mainly in diseases of the cardiovascular system or in diseases associated with cardiovascular disturbances. The increasing knowledge about the role of autoantibodies against G-protein-coupled receptor (GPCR-AABs) as pathogenic drivers, the resulting development of strategies aimed at their removal or neutralization, and the evidenced patient benefit associated with such therapies have created the need for a summary of GPCR-AAB-associated diseases. Here, we summarize the present knowledge about GPCR-AABs in cardiovascular diseases. The identity of the GPCR-AABs and their prevalence in each of several specific cardiovascular diseases are documented. The structure of GPCR is also briefly discussed. Using this information, differences between classic agonists and GPCR-AABs in their GPCR binding and activation are presented and the resulting pathogenic consequences are discussed. Furthermore, treatment strategies that are currently under study, most of which are aimed at the removal and in vivo neutralization of GPCR-AABs, are indicated and their patient benefits discussed. In this context, immunoadsorption using peptides/proteins or aptamers as binders are introduced. The use of peptides or aptamers for in vivo neutralization of GPCR-AABs is also described. Particular attention is given to the GPCR-AABs directed against the adrenergic beta1-, beta2-, and α1-receptor as well as the muscarinic receptor M2, angiotensin II-angiotensin receptor type I, endothelin1 receptor type A, angiotensin (1-7) Mas-receptor, and 5-hydroxytryptamine receptor 4. Among the diseases associated with GPCR-AABs, special focus is given to idiopathic dilated cardiomyopathy, Chagas' cardiomyopathy, malignant and pulmonary hypertension, and kidney diseases. Relationships of GPCR-AABs are indicated to glaucoma, peripartum cardiomyopathy, myocarditis, pericarditis, preeclampsia, Alzheimer's disease, Sjörgren's syndrome, and metabolic syndrome after cancer chemotherapy.

Neutralization of pathogenic beta1-receptor autoantibodies by aptamers in vivo: the first successful proof of principle in spontaneously hypertensive rats

Autoantibodies (AABs) against the second extracellular loop of the beta1-receptor (beta1(II)-AABs) are found as a pathogenic driver in patients with idiopathic dilated cardiomyopathy, Chagas cardiomyopathy, peripartum cardiomyopathy, and myocarditis, and have been increasingly seen as a treatment target. We recently identified an aptamer (single short DNA strand) that specifically binds and neutralizes beta1(II)-AABs. Via application of this aptamer, a new treatment strategy for diseases associated with the cardio-pathogenic beta1(II)-AABs could be developed. Spontaneously hypertensive rats (SHR) positive for beta1(II)-AABs were treated five times at weekly intervals (bolus application of 2 mg/kg body weight followed by an infusion of the same amount over 20 min). SHR responded to aptamer treatment with a strong reduction in the cardio-pathogenic beta1(II)-AABs. The AABs did not substantially return within the study period. No signs for aptamer toxicity were observed by visual examination of the heart, liver, and kidney, or by measurement of plasma CK, ALT, and creatinine. The aptamer's potential for beta1(II)-AAB neutralization and consequently for cardiomyopathy treatment has been shown for the first time in vivo.

Peripartum cardiomyopathy: A puzzle closer to solution

Peripartum cardiomyopathy (PPCM) represents new heart failure in a previously heart-healthy peripartum patient. It is necessary to rule out all other known causes of heart failure before accepting a diagnosis of PPCM. The modern era for PPCM in the United States and beyond began with the report of the National Institutes of Health PPCM Workshop in 2000, clarifying all then-currently known aspects of the disease. Since then, hundreds of publications have appeared, an indication of how devastating this disease can be to young mothers and their families and the urgent desire to find solutions for its cause and better treatment. The purpose of this review is to highlight the important advances that have brought us nearer to the solution of this puzzle, focusing on what we have learned about PPCM since 2000; and what still remains unanswered. Despite many improvements in outcome, we still do not know the actual triggers that initiate the pathological process; but realize that cardiac angiogenic imbalances resulting from complex pregnancy-related immune system and hormonal changes play a key role.