An update on the pathophysiology of acute and recurrent pericarditis

Pathogenic pathways and therapeutic targets of inflammation in heart diseases: A focus on Interleukin-1

BACKGROUND

An exuberant and dysregulated inflammatory response contributes to the development and progression of cardiovascular diseases (CVDs).

METHODS

This narrative review includes original articles and reviews published over the past 20 years and found through PubMed. The following search terms (or combination of terms) were considered: "acute pericarditis," "recurrent pericarditis," "myocarditis," "cardiac sarcoidosis," "atherosclerosis," "acute myocardial infarction," "inflammation," "NLRP3 inflammasome," "Interleukin-1" and "treatment."

RESULTS

Recent evidence supports the role of inflammation across a wide spectrum of CVDs including myocarditis, pericarditis, inflammatory cardiomyopathies (i.e. cardiac sarcoidosis) as well as atherosclerotic CVD and heart failure. Interleukins (ILs) are the signalling mediators of the inflammatory response. The NACHT, leucine-rich repeat and pyrin-domain containing protein 3 (NLRP3) inflammasome play a key role in producing IL-1β, the prototypical pro-inflammatory cytokine involved in CVDs. Other pro-inflammatory cytokines (e.g. tumour necrosis factor) have been implicated in cardiac sarcoidosis. As a proof of this, IL-1 blockade has been proven efficacious in pericarditis and chronic coronary syndrome.

CONCLUSION

Tailored strategies aiming at quenching the inflammatory response have emerged as promising to treat CVDs. In this review article, we summarize recent evidence regarding the role of inflammation across a broad spectrum of CVDs. We also review novel evidence regarding targeted therapeutic strategies.

The Evolving Etiologic and Epidemiologic Portrait of Pericardial Disease

Pericardial disease includes a variety of conditions, including inflammatory pericarditis, pericardial effusions, constrictive pericarditis, pericardial cysts, and primary and secondary pericardial neoplasms. The true incidence of this varied condition is not well established, and the causes vary greatly across the world. This review aims to describe the changing pattern of epidemiology of pericardial disease and to provide an overview of causative etiologies. Idiopathic pericarditis (assumed most often to be viral) remains the most common etiology for pericardial disease globally, with tuberculous pericarditis being most common in developing countries. Other important etiologies include fungal, autoimmune, autoinflammatory, neoplastic (both benign and malignant), immunotherapy-related, radiation therapy-induced, metabolic, postcardiac injury, postoperative, and postprocedural causes. Improved understanding of the immune pathophysiological pathways has led to identification and reclassification of some idiopathic pericarditis cases into autoinflammatory etiologies, including immunoglobulin G (IgG)4-related pericarditis, tumour necrosis factor receptor-associated periodic syndrome (TRAPS), and familial Mediterranean fever in the current era. Contemporary advances in percutaneous cardiac interventions and the recent COVID-19 pandemic have also resulted in changes in the epidemiology of pericardial diseases. Further research is needed to improve our understanding of the etiologies of pericarditis, using the assistance of contemporary advanced imaging techniques and laboratory testing. Careful consideration of the range of potential causes and local epidemiologic patterns of causality are important for the optimization of diagnostic and therapeutic approaches.

NLRP3-mediated inflammation in cardio-oncology: sterile yet harmful

Despite significant advances and the continuous development of novel, effective therapies to treat a variety of malignancies, cancer therapy-induced cardiotoxicity has been identified as a prominent cause of morbidity and mortality, closely competing with secondary malignancies. This unfortunate limitation has prompted the inception of the field of cardio-oncology with its purpose to provide the necessary knowledge and key information on mechanisms that support the use of the most efficacious cancer therapy with minimal or no interruption while paying close attention to preventing cardiovascular related morbidity and mortality. Several mechanisms that contribute to cancer therapy-induced cardiotoxicity have been proposed and studied. These mainly involve mitochondrial dysfunction and reactive oxygen species-induced oxidative stress, lysosomal damage, impaired autophagy, cell senescence, DNA damage, and sterile inflammation with the formation and activation of the NLRP3 inflammasome. In this review, we focus on describing the principal mechanisms for different classes of cancer therapies that lead to cardiotoxicity involving the NLRP3 inflammasome. We also summarize current evidence of cardio-protection with inflammasome inhibitors in the context of heart disease in general, and further highlight the potential application of this evidence for clinical translation in at risk patients for the purpose of preventing cancer therapy associated cardiovascular morbidity and mortality.

Deciphering the Basis of Molecular Biology of Selected Cardiovascular Diseases: A View on Network Medicine

Cardiovascular diseases are the leading cause of death across the world. For decades, researchers have been studying the causes of cardiovascular disease, yet many of them remain undiscovered or poorly understood. Network medicine is a recently expanding, integrative field that attempts to elucidate this issue by conceiving of disease as the result of disruptive links between multiple interconnected biological components. Still in its nascent stages, this revolutionary application of network science facilitated a number of important discoveries in complex disease mechanisms. As methodologies become more advanced, network medicine harbors the potential to expound on the molecular and genetic complexities of disease to differentiate how these intricacies govern disease manifestations, prognosis, and therapy. This is of paramount importance for confronting the incredible challenges of current and future cardiovascular disease research. In this review, we summarize the principal molecular and genetic mechanisms of common cardiac pathophysiologies as well as discuss the existing knowledge on therapeutic strategies to prevent, halt, or reverse these pathologies.

Advances in Imaging and Targeted Therapies for Recurrent Pericarditis: A Review

Importance

Pericarditis is the most common form of pericardial disease. Recurrence of pericarditis affects 15% to 30% of patients after the initial episode of pericarditis. Up to 50% of patients with the first recurrence have additional recurrences. These patients often progress to have colchicine-resistant and corticosteroid-dependent disease. Rapidly evolving cardiac magnetic resonance imaging techniques and novel targeted therapies have paved the way for imaging-guided therapy for recurrent pericarditis. However, the optimal application of these recent advances remains unclear.

Observations

A search was conducted using the PubMed and Cochrane databases for English-language studies, management guidelines, meta-analyses, and review articles published until April 2022 on recurrent pericarditis. Following the 2015 European Society of Cardiology guidelines for the diagnosis and management of pericardial diseases, new clinical trials and registry data have emerged that demonstrate the efficacy of interleukin-1 blockers in recurrent pericarditis. In addition, new observational data have come to light supporting the use of cardiac magnetic resonance imaging in the diagnosis, risk stratification, and management of such patients.

Conclusions and Relevance

Advances in imaging and targeted therapies have led to a paradigm shift in the management of recurrent pericarditis. This narrative review summarizes the established and emerging data on the diagnosis and treatment of recurrent pericarditis with special emphasis on the role of cardiac magnetic resonance imaging and interleukin-1 blockers in the current era of tailored therapy for recurrent pericarditis.

The inflammasome as a therapeutic target for myopericardial diseases

Myopericardial diseases are relatively common in clinical practice although often neglected due to the limited availability of treatments and evidence to support management strategies. However in the past ten years, growing evidence has improved our knowledge of the pathophysiology of myopericardial diseases and first clinical trials have highlighted the importance of inflammation as therapeutic target developing first steps toward a personalized approach also in this field. The NLRP3 (NACHT, leucine-rich repeat, and pyrin domain-containing protein 3) inflammasome is a protein complex that functions as a platform for rapid induction of the inflammatory response to infection or sterile injury through pro-inflammatory cytokines, now recognized as a new important therapeutic target for myopericardial diseases. Colchicine is an old drug that acts as non-specific inhibitor of the inflammasome and could be a useful and inexpensive option in clinical practice and it is currently registered for pericarditis in some European countries (e.g., Italy, Austria). Anti-interleukin-1 (IL-1) agents (anakinra and rilonacept) appear to be a major advance in medical therapy of recurrent pericarditis and could be a therapeutic option also for myocarditis if confirmed in additional studies. In this review, we provide an update on the inflammasome as therapeutic target for myopericardial diseases, a significant advance in medical therapy for these diseases in the last five years.

Colchicine for COVID-19: targeting NLRP3 inflammasome to blunt hyperinflammation

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is capable of inducing the activation of NACHT, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome, a macromolecular structure sensing the danger and amplifying the inflammatory response. The main product processed by NLRP3 inflammasome is interleukin (IL)-1β, responsible for the downstream production of IL-6, which has been recognized as an important mediator in coronavirus disease 2019 (COVID-19). Since colchicine is an anti-inflammatory drug with the ability to block NLRP3 inflammasome oligomerization, this may prevent the release of active IL-1β and block the detrimental effects of downstream cytokines, i.e. IL-6. To date, few randomized clinical trials and many observational studies with colchicine have been conducted, showing interesting signals. As colchicine is a nonspecific inhibitor of the NLRP3 inflammasome, compounds specifically blocking this molecule might provide increased advantages in reducing the inflammatory burden and its related clinical manifestations. This may occur through a selective blockade of different steps preceding NLRP3 inflammasome oligomerization as well as through a reduced release of the main cytokines (IL-1β and IL-18). Since most evidence is based on observational studies, definitive conclusion cannot be drawn and additional studies are needed to confirm preliminary results and further dissect how colchicine and other NLRP3 inhibitors reduce the inflammatory burden and evaluate the timing and duration of treatment.

Post-cardiac injury syndrome triggered by radiofrequency ablation for AVNRT

Background

Post-cardiac injury syndrome (PCIS) is an inflammatory condition following myocardial or pericardial damage. In response to catheter ablation, PCIS most frequently occurs after extensive radiofrequency (RF) ablation of large areas of atrial myocardium. Minor myocardial injury from right septal slow pathway ablation for atrioventricular nodal reentrant tachycardia (AVNRT) is not an established cause of the syndrome.

Case presentation

A 62-year-old women with a 6-year history of symptomatic narrow-complex tachycardia was referred to perform an electrophysiological study. During the procedure AVNRT was recorded and a total of two RF burns were applied to the region between the coronary sinus and the tricuspid annulus. Pericardial effusion was routinely ruled out by focused cardiac ultrasound. In the following days, the patient developed fever, elevated inflammatory and cardiac markers, new-onset pericardial effusion, characteristic ECG changes, and complained of pleuritic chest pain. An extensive workup for infectious, metabolic, rheumatologic, neoplastic, and toxic causes of pericarditis and myocarditis was unremarkable. Cardiac magnetic resonance imaging showed no signs of ischemia, infiltrative disease or structural abnormalities. The patient was diagnosed with PCIS and initiated on aspirin and low-dose colchicine. At a 1-month follow-up visit the patient was free of symptoms but still had a small pericardial effusion. After three  months of treatment the pericardial effusion had resolved completely.

Conclusions

Inflammatory pericardial reactions can occur after minor myocardial damage from RF ablation without involvement of structures in close proximity to the pericardium.

Clinical Trials in Pericardial Disease: New Paradigm Shift

PURPOSE OF REVIEW

Aim of the review is to discuss the results of major clinical trials and how they can have impact on clinical practice.

RECENT FINDINGS

Pericardial diseases have been the Cinderella of cardiovascular diseases for many years, but improvements in the knowledge of etiology and the pathophysiology especially of recurrent pericarditis have led to first clinical trials that have demonstrated the efficacy and safety of colchicine on top of standard anti-inflammatory therapies and of anti-IL-1 agents (anakinra and rilonacept) in corticosteroid-dependent and colchicine-resistant pericarditis. Current pooled data suggest that anti-IL-1 agents should be a first option for corticosteroid-dependent and colchicine-resistant recurrent pericarditis with evidence of systemic inflammation by means of elevated C-reactive protein. This could translate into an upgraded recommendation for these agents in future guidelines. Treatment of pericardial diseases is improving moving towards a more personalized therapy according to the presentation and etiology, and new or old drugs could be important to expand the therapeutic spectrum.

Interleukin-1 and the NLRP3 Inflammasome in Pericardial Disease

Purpose of Review

Pericarditis is a generally benign disease, although complications and/or recurrences may occur in up to 30% of cases. New evidence on the pathophysiology of the disease has accumulated in recent years.

Recent Findings

Recently, it has been shown that the activation of the NLRP3 (NACHT, leucine-rich repeat, and pyrin domain-containing protein 3) inflammasome is central in the pathophysiology of pericarditis. These findings derive from clinical data, an experimental animal model of acute pericarditis supporting a role for the NLRP3 inflammasome in pericarditis, and from indirect evidence of inhibitors of NLRP3 inflammasome in clinical trials.

Summary

Pericarditis is regarded as a stereotypical response to an acute damage of the mesothelial cells of the pericardial layers. NLRP3 inflammasome, a macromolecular structure sensing damage and releasing pro-inflammatory cytokines, is centrally involved as it releases interleukin (IL)-1β, whose auto-induction feeds an autoinflammatory disease, mostly responsible for recurrences. Colchicine, an inhibitor of NLRP3 inflammasome formation, and IL-1-targeted therapies, such as anakinra and rilonacept, were found to effectively blunt the acute inflammation and reduce the risk for recurrences.

Anti-interleukin-1 agents for pericarditis: a primer for cardiologists

Anti-interleukin (IL)-1 agents have been developed for the treatment of autoinflammatory and rheumatic conditions, where overproduction of IL-1 is an important pathophysiologic process. IL-1α and IL-1β are the most studied members of the IL-1 family of cytokines and have the strongest proinflammatory effects. A naturally occurring antagonist (IL-1Ra) mitigates their proinflammatory effects. Overproduction of both IL-1α (released by inflamed/damaged pericardial cells) and IL-1β (released by inflammatory cells) is now a well-recognized therapeutic target in patients with recurrent idiopathic pericarditis. Currently, there are three available anti-IL-1 agents: anakinra (recombinant human IL-1Ra), rilonacept (a soluble decoy receptor ‘trap’, binding both IL-1α and IL-1β), and canakinumab (human monoclonal anti-IL-1β antibody). For patients with corticosteroid-dependent and colchicine-resistant recurrent pericarditis with evidence of systemic inflammation, as evidenced by elevated C-reactive protein, the efficacy and safety of anakinra (2 mg/kg/day up to 100 mg/day subcutaneously usually for at least 6 months, then tapered) and rilonacept (320 mg subcutaneously for the first day followed by 160 mg subcutaneously weekly) have been clearly demonstrated in observational studies and randomized controlled clinical trials. Severe side effects are rare and discontinuation rates are very low (<4%). The most common reported side effect is injection site reactions (>50% of patients). In this article, we describe the historical and pathophysiological background and provide a comprehensive review of these agents, which appear to be the most significant advance in medical therapy of recurrent pericarditis in the last 5 years.

Current treatment of recurrent pericarditis: safety considerations and future directions

INTRODUCTION

Recurrent pericarditis is one of the most troublesome complications of pericarditis affecting a substantial amount of patients and often severely impairing the quality of life. Current medical treatments range from non-steroidal anti-inflammatory drugs (NSAIDs), colchicine and corticosteroids to biological agents (anti IL-1 agents, especially anakinra and rilonacept), intravenous immunoglobulins and immunosuppressive treatments. Safety is a major issue to deal with since the disease often affects relatively young or middle-aged patients.

AREAS COVERED

The review is aimed at providing an update on the efficacy and safety of current medical therapies for recurrent pericarditis including most recent advances represented by anti IL-1 agents.

EXPERT OPINION

Therapy of recurrent pericarditis has evolved over years leading to a more evidence-based and personalized treatment based on clinical presentation and pathophysiology. The main distinction is between patients with an inflammatory phenotype (e.g. fever, elevation of markers of inflammation, pericardial and/or pleural effusion) vs. those without an inflammatory phenotype. Colchicine and anti IL-1 agents are especially efficacious and indicated for those with an inflammatory phenotype, while corticosteroids, azathioprine and immunoglobulins seem more indicated for those without evidence of systemic inflammation.

Autoimmune and Autoinflammatory Pericarditis: Definitions and New Treatments

PURPOSE OF THE REVIEW

The purpose of the review is to analyze the pathogenetic mechanisms that underlie acute pericarditis, with attention to autoimmune and autoinflammatory pericarditis, and, in addition, to review the available therapeutic armamentarium.

RECENT FINDINGS

Several studies have been published on the use of anti-IL-1 drugs in recurrent pericarditis, including anakinra and rilonacept. The latest, the RHAPSODY study, based on the use of rilonacept in recurrent pericarditis, has recently reached phase 3 with promising results in terms of efficacy and safety. Alterations in the function of the inflammasome and the consequent overproduction of IL-1 play a pivotal role in the genesis of autoinflammatory pericarditis. Recent studies added evidence to the importance of anti-IL-1 drugs in the treatment of recurrent pericarditis with raised C-reactive protein. In the era of tailored medicine, anti-IL-1 agents may be very useful in the subset of patients with recurrent pericarditis and a clear inflammatory phenotype.