Programmed Cell Death-1: Programmed Cell Death-Ligand 1 Interaction Protects Human Cardiomyocytes Against T-Cell Mediated Inflammation and Apoptosis Response In Vitro

Molecular fingerprints of cardiovascular toxicities of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy by unleashing the power of the immune system against malignant cells. However, their use is associated with a spectrum of adverse effects, including cardiovascular complications, which can pose significant clinical challenges. Several mechanisms contribute to cardiovascular toxicity associated with ICIs. First, the dysregulation of immune checkpoints, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) and its ligand (PD-L1), and molecular mimicry with cardiac autoantigens, leads to immune-related adverse events, including myocarditis and vasculitis. These events result from the aberrant activation of T cells against self-antigens within the myocardium or vascular endothelium. Second, the disruption of immune homeostasis by ICIs can lead to autoimmune-mediated inflammation of cardiac tissues, manifesting as cardiac dysfunction and heart failure, arrhythmias, or pericarditis. Furthermore, the upregulation of inflammatory cytokines, particularly tumor necrosis factor-alpha, interferon-γ, interleukin-1β, interleukin-6, and interleukin-17 contributes to cardiac and endothelial dysfunction, plaque destabilization, and thrombosis, exacerbating cardiovascular risk on the long term. Understanding the intricate mechanisms of cardiovascular side effects induced by ICIs is crucial for optimizing patient care and to ensure the safe and effective integration of immunotherapy into a broader range of cancer treatment protocols. The clinical implications of these mechanisms underscore the importance of vigilant monitoring and early detection of cardiovascular toxicity in patients receiving ICIs. Future use of these key pathological mediators as biomarkers may aid in prompt diagnosis of cardiotoxicity and will allow timely interventions.

Immune checkpoints in cardiac physiology and pathology: therapeutic targets for heart failure

Immune checkpoint molecules are physiological regulators of the adaptive immune response. Immune checkpoint inhibitors (ICIs), such as monoclonal antibodies targeting programmed cell death protein 1 or cytotoxic T lymphocyte-associated protein 4, have revolutionized cancer treatment and their clinical use is increasing. However, ICIs can cause various immune-related adverse events, including acute and chronic cardiotoxicity. Of these cardiovascular complications, ICI-induced acute fulminant myocarditis is the most studied, although emerging clinical and preclinical data are uncovering the importance of other ICI-related chronic cardiovascular complications, such as accelerated atherosclerosis and non-myocarditis-related heart failure. These complications could be more difficult to diagnose, given that they might only be present alongside other comorbidities. The occurrence of these complications suggests a potential role of immune checkpoint molecules in maintaining cardiovascular homeostasis, and disruption of physiological immune checkpoint signalling might thus lead to cardiac pathologies, including heart failure. Although inflammation is a long-known contributor to the development of heart failure, the therapeutic targeting of pro-inflammatory pathways has not been successful thus far. The increasingly recognized role of immune checkpoint molecules in the failing heart highlights their potential use as immunotherapeutic targets for heart failure. In this Review, we summarize the available data on ICI-induced cardiac dysfunction and heart failure, and discuss how immune checkpoint signalling is altered in the failing heart. Furthermore, we describe how pharmacological targeting of immune checkpoints could be used to treat heart failure.

PD-1: A critical player and target for immune normalization

Immune system imbalances contribute to the pathogenesis of several different diseases, and immunotherapy shows great therapeutic efficacy against tumours and infectious diseases with immune-mediated derivations. In recent years, molecules targeting the programmed cell death protein 1 (PD-1) immune checkpoint have attracted much attention, and related signalling pathways have been studied clearly. At present, several inhibitors and antibodies targeting PD-1 have been utilized as anti-tumour therapies. However, increasing evidence indicates that PD-1 blockade also has different degrees of adverse side effects, and these new explorations into the therapeutic safety of PD-1 inhibitors contribute to the emerging concept that immune normalization, rather than immune enhancement, is the ultimate goal of disease treatment. In this review, we summarize recent advancements in PD-1 research with regard to immune normalization and targeted therapy.

IFN-γ activates an immune-like regulatory network in the cardiac vascular endothelium

The regulatory mechanisms underlying the response to pro-inflammatory cytokines during myocarditis are poorly understood. Here, we use iPSC-derived cardiovascular progenitor cells (CVPCs) to model the response to interferon gamma (IFN-γ) during myocarditis. We generate RNA-seq and ATAC-seq for four CVPCs that were treated with IFN-γ and compare them with paired untreated controls. Transcriptional differences after treatment show that IFN-γ initiates an innate immune cell-like response in the vascular cardiac endothelium. IFN-γ treatment also shifts the CVPC transcriptome towards the adult coronary artery and aorta profiles and expands the relative endothelial cell population in all four CVPC lines. Analysis of the accessible chromatin shows that IFN-γ is a potent chromatin remodeler and establishes an IRF-STAT immune-cell like regulatory network. Our findings reveal insights into the endothelial-specific protective mechanisms during myocarditis.

Previous cardiovascular injury is a prerequisite for immune checkpoint inhibitor-associated lethal myocarditis in mice

AIMS

Immune checkpoint inhibitors (ICIs) are antineoplastic drugs designed to activate the immune system's response against cancer cells. Evidence suggests that they may lead to immune-related adverse events, particularly when combined (e.g., anti-CTLA-4 plus anti-PD-1), sometimes resulting in severe conditions such as myocarditis. We aimed to investigate whether a previously sustained cardiac injury, such as pathological remodelling due to hypertension, is a prerequisite for ICI therapy-induced myocarditis.

METHODS

We evaluated the cardiotoxicity of ICIs in a hypertension (HTN) mouse model (C57BL/6). Weekly doses were administered up to day 21 after the first administration. Our analysis encompassed the following parameters: (i) survival and cardiac pathological remodelling, (ii) cardiac function assessed using pressure-volume (PV)-loops, with brain natriuretic peptide (BNP) serving as a marker of haemodynamic dysfunction and (iii) cardiac inflammation (cytokine levels, infiltration, and cardiac antigen autoantibodies).

RESULTS

After the first administration of ICI combined therapy, the treated HTN group showed a 30% increased mortality (P = 0.0002) and earlier signs of hypertrophy and pathological remodelling compared with the untreated HTN group. BNP (P = 0.01) and TNF-α (<0.0001) increased 2.5- and 1.7-fold, respectively, in the treated group, while IL-6 (P = 0.8336) remained unchanged. Myocarditis only developed in the HTN group treated with ICIs on day 21 (score >3), characterised by T cell infiltration and increased cardiac antigen antibodies (86% showed a titre of 1:160). The control group treated with ICI was unaffected in any evaluated feature.

CONCLUSIONS

Our findings indicate that pre-existing sustained cardiac damage is a necessary condition for ICI-induced myocarditis.

The Balance of CD8-Positive T Cells and PD-L1 Expression in the Myocardium Predicts Prognosis in Lymphocytic Fulminant Myocarditis

INTRODUCTION

The clinical significance and prognostic value of T cell involvement and programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) have not been established in lymphocytic fulminant myocarditis (FM). We investigated the prognostic impact of the number of CD4+, CD8+, FoxP3+, and PD-1+ T cells, as well as PD-L1 expression, in cardiomyocytes in lymphocytic FM.

METHODS

This is a single-center observational cohort study. Myocardial tissue was obtained from 16 consecutive patients at lymphocytic FM onset. The median follow-up was 140 days. Cardiac events were defined as a composite of cardiac death and left ventricular-assist device implantation. CD4, CD8, FoxP3, PD-1, and PD-L1 immunostaining were performed on myocardial specimens.

RESULTS

The median age of the patients was 52 years (seven men and nine women). There was no significant difference in the number of CD4+ cells. The number of CD8+ cells and the CD8+/CD4+ T cell ratio were higher in the cardiac event group (Event+) than in the group without cardiac events (Event-) (p = 0.048 and p = 0.022, respectively). The number of FoxP3+ T cells was higher in the Event+ group (p = 0.049). Although there was no difference in the number of PD-1+ cells, cardiomyocyte PD-L1 expression was higher in the Event+ group (p = 0.112). Event-free survival was worse in the group with a high CD8+ cell count (p = 0.012) and high PD-L1 expression (p = 0.049). When divided into three groups based on the number of CD8+ cells and PD-L1 expression (CD8highPD-L1high [n = 8], CD8lowPD-L1high [n = 1], and CD8lowPD-L1low [n = 7]), the CD8highPD-L1high group demonstrated the worst event-free survival, while the CD8lowPD-L1high group had a favorable prognosis without cardiac events (p = 0.041).

CONCLUSION

High myocardial expression of CD8+ T cells and PD-L1 may predict a poor prognosis in lymphocytic FM.

Immune interactions in pembrolizumab (PD-1 inhibitor) cancer therapy and cardiovascular complications

The use of immunotherapies like pembrolizumab (PEM) is increasingly common for the management of numerous cancer types. The use of PEM to bolster T-cell response against tumor growth is well documented. However, the interactions PEM has on other immune cells to facilitate tumor regression and clearance is unknown and warrants further investigation. In this review, we present literature findings that have reported the interactions of PEM in stimulating innate and adaptive immune cells, which enhance cytotoxic phenotypes. This triggers secretion of cytokines and chemokines, which have both beneficial and detrimental effects. We also describe how this leads to the development of rare but underreported occurrence of PEM-induced immune-related cardiovascular complications that arise suddenly and progress rapidly to debilitating and fatal consequences. This review encourages further research and investigation of PEM-induced cardiovascular complications and other immune cell interactions in patients with cancer. As PEM therapy in treating cancer types is expanding, we expect that this review will inform health care professionals of diverse specializations of medicine like dermatology (melanoma skin cancers), ophthalmology (eye cancers), and pathology (hematological malignancies) about PEM-induced cardiac complications.

Identification of Novel Targets for Treatment of Dilated Cardiomyopathy Based on the Ferroptosis and Immune Heterogeneity

Purpose

This study aimed to investigate the role of ferroptosis in dilated cardiomyopathy (DCM) and to identify new targets for treatment and diagnosis of DCM.

Methods

GSE116250 and GSE145154 were downloaded from the Gene Expression Omnibus database. Unsupervised consensus clustering of DCM patients was used to confirm the impact of ferroptosis. Ferroptosis-related hub genes were identified by WGCNA and single cell sequencing analyses. Finally, we established a DCM mouse model via injection of Doxorubicin to verify the expression level of OTUD1 and colocalization between cell markers and OTUD1 in DCM mouse heart.

Results

A total of 13 ferroptosis-related differentially expressed genes (DEGs) were identified. The DCM patients were divided into two clusters according to the expression of 13 DEGs. The DCM patients in different clusters showed discrepancies in immune infiltration. Four hub genes were further identified by WGCNA analysis. Single cell data analysis revealed that OTUD1 may regulate B cells and DC cells and then participate in immune infiltration discrepancy. The upregulation of OTUD1 and the colocalization of OTUD1 with CD19 (B cell maker) and CD11c (DCs markers) markers were confirmed in DCM mouse hearts.

Conclusion

Ferroptosis and the immune microenvironment are closely associated with DCM, and OTUD1 may play an important role through B cells and DCs.

Drug therapy for myocarditis induced by immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs), including cytotoxic T-lymphocyte antigen 4 (CTLA-4), programmed cell death 1 (PD-1), and its ligand 1 (PD-L1), have improved the survival in multiple types of cancers; however, ICIs may cause cardiovascular toxicity. Although rare, ICI-mediated cardiotoxicity is an extremely serious complication with a relatively high mortality. In this review, we discuss the underlying mechanism and clinical manifestations of cardiovascular toxicity induced by ICIs. According to previous studies, multiple signaling pathways are involved in myocarditis induced by ICIs. Further, we summarize the clinical trials of drugs for the treatment of ICI-associated myocarditis. Although these drugs have shown the beneficial effects of alleviating cardiac function and reducing mortality rates, their efficacy is not optimal. Finally, we discuss the therapeutic potential of some novel compounds as well as the underlying mechanisms of their action.

Clinical characteristics and management of immune checkpoint inhibitor-related cardiotoxicity: A single-center experience

Background

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy in the past decade and amplify T-cell-mediated immune responses by disrupting immunoinhibitory signals. The augmented T-cell immune response has led to a range of immune-related adverse effects (irAEs). Immune-related cardiotoxicity has been reported in case series but has been underappreciated due to difficulties in diagnosis. This article describes epidemiological, clinical presentation, subtype, and treatment data and a new systematic framework for the clinical management of cardiotoxicity.

Methods

Data were extracted for cancer patients who received ICIs in a single center between January 1, 2020, and February 28, 2022. ICI-associated cardiotoxicity was clinically diagnosed based on clinical presentations, biochemical biomarkers, and imaging features.

Results

We identified a total of 12 (2.46%) cases of ICI-related cardiotoxicity from 487 patients who received PD-1 or PD-L1 inhibitors. All patients were diagnosed with advanced or metastatic solid tumors. The severity of ICI-related cardiotoxicity ranged from subclinical cardiac abnormalities (subclinical type) with only asymptomatic troponin-I (TnI) elevations (25.0%) to symptomatic cardiac abnormalities (clinical type) (75.0%). Patients with symptomatic cardiac abnormalities had several manifestations, including tachyarrhythmia (16.7%), bradyarrhythmia (41.7%), or cardiac failure (8.3%). The median immunotherapy exposure time was 1.5 doses (range: 1 to 5), and the median time from the initial immunotherapy to the onset of ICI-related cardiotoxicity was 33.5 days (IQR: 20.3 to 46.8). Most patients, including those with subclinical cardiac abnormalities, were administered systemic corticosteroids (58.3%). One (8.3%) patient was put on mechanical ventilation, one (8.3%) received plasma exchange therapy, one (8.3%) was implanted with a pacemaker, and one (8.3%) was admitted to the ICU. Three patients with symptomatic cardiac abnormalities (25.0%) died, and other patients presented with significant clinical improvement with good outcomes.

Conclusion

ICI-related cardiotoxicity is uncommon but critical with a high mortality rate and poor prognosis, especially for a small group of patients with symptomatic cardiac abnormalities. More attention should be given to cardiotoxicity associated with ICIs, and these patients should be given baseline examinations and biochemical analyses before and after the initiation of immunotherapy, intensive cardiac assessments, an accurate and rapid diagnosis, and timely multidisciplinary management with immunosuppressive agents and other necessary clinical interventions.

Immune Checkpoint Inhibitor Associated Myocarditis and Cardiomyopathy: A Translational Review

Immune checkpoint inhibitors (ICIs) have revolutionized oncology and transformed the treatment of various malignancies. By unleashing the natural immunological brake of the immune system, ICIs were initially considered an effective, gentle therapy with few side effects. However, accumulated clinical knowledge reveals that ICIs are associated with inflammation and tissue damage in multiple organs, leading to immune-related adverse effects (irAEs). Most irAEs involve the skin and gastrointestinal tract; however, cardiovascular involvement is associated with very high mortality rates, and its underlying pathomechanisms are poorly understood. Ranging from acute myocarditis to chronic cardiomyopathies, ICI-induced cardiotoxicity can present in various forms and entities. Revealing the inciting factors, understanding the pathogenesis, and identifying effective treatment strategies are needed to improve the care of tumor patients and our understanding of the immune and cardiovascular systems.

Characterization of immune checkpoint inhibitor-induced cardiotoxicity reveals interleukin-17A as a driver of cardiac dysfunction after anti-PD-1 treatment

BACKGROUND AND PURPOSE

Immune checkpoint inhibitors (ICI), such as anti-PD-1 monoclonal antibodies, have revolutionized cancer therapy by enhancing the cytotoxic effects of T-cells against tumours. However, enhanced T-cell activity also may cause myocarditis and cardiotoxicity. Our understanding of the mechanisms of ICI-induced cardiotoxicity is limited. Here, we aimed to investigate the effect of PD-1 inhibition on cardiac function and explore the molecular mechanisms of ICI-induced cardiotoxicity.

EXPERIMENTAL APPROACH

C57BL6/J and BALB/c mice were treated with isotype control or anti-PD-1 antibody. Echocardiography was used to assess cardiac function. Cardiac transcriptomic changes were investigated by bulk RNA sequencing. Inflammatory changes were assessed by qRT-PCR and immunohistochemistry in heart, thymus, and spleen of the animals. In follow-up experiments, anti-CD4 and anti-IL-17A antibodies were used along with PD-1 blockade in C57BL/6J mice.

KEY RESULTS

Anti-PD-1 treatment led to cardiac dysfunction and left ventricular dilation in C57BL/6J mice, with increased nitrosative stress. Only mild inflammation was observed in the heart. However, PD-1 inhibition resulted in enhanced thymic inflammatory signalling, where Il17a increased most prominently. In BALB/c mice, cardiac dysfunction was not evident, and thymic inflammatory activation was more balanced. Inhibition of IL-17A prevented anti-PD-1-induced cardiac dysfunction in C57BL6/J mice. Comparing myocardial transcriptomic changes in C57BL/6J and BALB/c mice, differentially regulated genes (Dmd, Ass1, Chrm2, Nfkbia, Stat3, Gsk3b, Cxcl9, Fxyd2, and Ldb3) were revealed, related to cardiac structure, signalling, and inflammation.

CONCLUSIONS

PD-1 blockade induces cardiac dysfunction in mice with increased IL-17 signalling in the thymus. Pharmacological inhibition of IL-17A treatment prevents ICI-induced cardiac dysfunction.

Immunopathogenesis of Immune Checkpoint Inhibitor Induced Myocarditis: Insights from Experimental Models and Treatment Implications

Despite the extraordinary success of immune checkpoint inhibitors (ICIs) in cancer treatment, their use is associated with a high incidence of immune-related adverse events (IRAEs), resulting from therapy-related autoimmunity against various target organs. ICI-induced myocarditis is one of the most severe forms of IRAE, which is associated with risk of hemodynamic compromise and mortality. Despite increasing recognition and prompt treatment by clinicians, there remain significant gaps in knowledge regarding the pathophysiology, diagnosis and treatment of ICI-induced myocarditis. As the newly emerged disease entity is relatively rare, it is challenging for researchers to perform studies involving patients at scale. Alternatively, mouse models have been developed to facilitate research understanding of the pathogenesis of ICI-induced myocarditis and drug discovery. Transgenic mice with immune checkpoint genes knocked out allow induction of myocarditis in a highly reproducible manner. On the other hand, it has not been possible to induce ICI-induced myocarditis in wild type mice by injecting ICIs monotherapy alone. Additional interventions such as combinational ICI, tumor inoculation, cardiac sarcomere immunization, or cardiac irradiation are necessary to mimic the underlying pathophysiology in human cancer patients and to induce ICI-induced myocarditis successfully. This review focuses on the immunopathogenesis of ICI-induced myocarditis, drawing insights from human studies and animal models, and discusses the potential implications for treatment.

Role of non-cardiomyocytes in anticancer drug-induced cardiotoxicity: A systematic review

Cardiotoxicity induced by anticancer drugs interferes with the continuation of optimal treatment, inducing life-threatening risks or leading to long-term morbidity. The heart is a complex pluricellular organ comprised of cardiomyocytes and non-cardiomyocytes. Although the study of these cell populations has been often focusing on cardiomyocytes, the contributions of non-cardiomyocytes to development and disease are increasingly being appreciated as both dynamic and essential. This review summarized the role of non-cardiomyocytes in anticancer drug-induced cardiotoxicity, including the mechanism of direct damage to resident non-cardiomyocytes, cardiomyocytes injury caused by paracrine modality, myocardial inflammation induced by transient cell populations and the protective agents that focused on non-cardiomyocytes.

The role of immune checkpoints in cardiovascular disease

Immune checkpoint inhibitors (ICI) are monoclonal antibodies which bind to immune checkpoints (IC) and their ligands to prevent inhibition of T-cell activation by tumor cells. Currently, multiple ICI are approved targeting Cytotoxic T-lymphocyte antigen 4 (CTLA-4), Programmed Death Protein 1 (PD-1) and its ligand PD-L1, and Lymphocyte-activation gene 3 (LAG-3). This therapy has provided potent anti-tumor effects and improved prognosis for many cancer patients. However, due to systemic effects, patients can develop immune related adverse events (irAE), including possible life threatening cardiovascular irAE, like atherosclerosis, myocarditis and cardiomyopathy. Inhibition of vascular IC is associated with increased atherosclerotic burden and plaque instability. IC protect against atherosclerosis by inhibiting T-cell activity and cytokine production, promoting regulatory T-cell differentiation and inducing T-cell exhaustion. In addition, PD-L1 on endothelial cells might promote plaque stability by reducing apoptosis and increasing expression of tight junction molecules. In the heart, IC downregulate the immune response to protect against cardiac injury by reducing T-cell activity and migration. Here, inhibition of IC could induce life-threatening T-cell-mediated-myocarditis. One proposed purpose behind lymphocyte infiltration is reaction to cardiac antigens, caused by decreased self-tolerance, and thereby increased autoimmunity because of IC inhibition. In addition, there are several reports of ICI-mediated cardiomyopathy with immunoglobulin G expression on cardiomyocytes, indicating an autoimmune response. IC are mostly known due to their cardiotoxicity. However, t his review compiles current knowledge on mechanisms behind IC function in cardiovascular disease with the aim of providing an overview of possible therapeutic targets in prevention or treatment of cardiovascular irAEs.

Pathophysiology of Immune Checkpoint Inhibitor-Induced Myocarditis

Immune checkpoint inhibitors (ICIs) have recently emerged as strong therapies for a broad spectrum of cancers being the first-line treatment for many of them, even improving the prognosis of malignancies that were considered untreatable. This therapy is based on the administration of monoclonal antibodies targeting inhibitory T-cell receptors, which boost the immune system and prevent immune evasion. However, non-specific T-cell de-repression can result in a wide variety of immune-related adverse events (irAEs), including gastrointestinal, endocrine, and dermatologic, with a smaller proportion of these having the potential for fatal outcomes such as neurotoxicity, pulmonary toxicity, and cardiotoxicity. In recent years, alarm has been raised about cardiotoxicity as it has the highest mortality rate when myocarditis develops. However, due to the difficulty in diagnosing this cardiac condition and the lack of clinical guidelines for the management of cardiovascular disease in patients on therapy with ICIs, early detection of myocarditis has become a challenge in these patients. In this review we outline the mechanisms of tolerance by which this fatal cardiomyopathy may develop in selected cancer patients treated with ICIs, summarize preclinical models of the disease that will allow the development of more accurate strategies for its detection and treatment, and discuss the challenges in the future to decrease the risks of its development with better decision making in susceptible patients.

Myocarditis Induced by Immunotherapy in Metastatic Melanoma—Review of Literature and Current Guidelines

Immunotherapy is a widely used treatment modality in oncology. Immune checkpoint inhibitors, as a part of immunotherapy, caused a revolution in oncology, especially in melanoma therapy, due to the significant prolongation of patients’ overall survival. These drugs act by activation of inhibited immune responses of T lymphocytes against cancer cells. The mechanism responsible for the therapy’s high efficacy is also involved in immune tolerance of the patient’s own tissues. The administration of ICI therapy to a patient can cause severe immune reactions against non-neoplastic cells. Among them, cardiotoxicity seems most important due to the high mortality rate. In this article, we present the history of a 79 year-old patient diagnosed with melanoma who died due to myocarditis induced by ICI therapy, despite the fast administration of recommended immunosuppressive therapy, as an illustration of possible adverse events of ICI. Additionally, we summarize the mechanism, risk factors, biomarkers, and clinical data from currently published guidelines and studies about ICI-related myocarditis. The fast recognition of this fatal adverse effect of therapy may accelerate the rapid introduction of treatment and improve patients’ outcomes.

Revisiting PD-1/PD-L pathway in T and B cell response: Beyond immunosuppression

The regulation of T cell response depends on co-inhibitory pathways that serve to control immune-mediated tissue damage and resolve inflammation by modulating the magnitude and duration of immune response. In this process, the axis of T-cell-expressed programmed death-1 (PD-1) and its ligands (PD-L1 and PD-L2) play a key role. While the PD-1/PD-L pathway has received considerable attention for its role in the maintenance of T cell exhaustion in cancer and chronic infection, the PD-1/PD-L pathway also plays diverse roles in regulating host immunity beyond T cell exhaustion. In this review, we will discuss emerging concepts in co-stimulatory functions of PD-1/PD-L pathway on T cell- and B cell response and explore the potential underlying mechanisms. In addition, based on the elevated expression of PD-1 and its ligands in local inflamed tissues, we further discussed the role of PD-1/PD-L pathway in autoimmune diseases.

Novel immunosuppressive effect of FK506 by upregulation of PD-L1 via FKBP51 in heart transplantation

The calcineurin inhibitor-FK506-is a first-line immunosuppressant that regulates T-cell secretion of IL-2 and other cytokines. However, the mechanism of its protective effect on target cells and its role on tumor recurrence and interaction with anti-tumor immune checkpoint inhibitors, such as PD-L1 blocking, are still unclear. Here, in a murine heart transplantation model, we observed the upregulation of programmed death-ligand 1 (PD-L1) expression by FK506 in both dendritic cells (DCs) and allografts. Blocking PD-L1 during FK506 treatment increased IFN-γ and TNF-α expression, enhanced CD4⁺ and CD8⁺ T-cell proliferation, and suppressed Treg differentiation. Moreover, PD-L1 decreased T-cell infiltration and induced T cell apoptosis in both the spleen and graft. PD-L1 was not only required in FK506-mediated immunosuppression but also upregulated by FK506. Treatment with SAFit2, a FKBP51 selective inhibitor, reduced the expression of PD-L1 on DCs and the grafts and interfered with the immunosuppressive effect of FK506, suggesting that the mechanism depends on FK506-binding protein (FKBP) 51 expression. Overall, our results add new insights into the role of FK506, not only on T-cell cytokine secretion but also on co-inhibitory molecular regulation and target cell immune privilege.

PD-1/L1 inhibitors may increase the risk of pericardial disease in non-small-cell lung cancer patients: a meta-analysis and systematic review

Background: The advent of PD-1/L1 inhibitors has changed the landscape for patients with non-small-cell lung cancer (NSCLC). Meanwhile, the adverse events of PD-1/L1 inhibitors have been focused. Methods: The Cochrane Central Register of Controlled Trials, PubMed and Embase databases and ClinicalTrials.gov were searched from inception to February 2021. Results: 18 studies involving 11,394 patients with NSCLC were included. PD-1/L1 inhibitor monotherapy was associated (relative risk, 95% confidence interval) with an increased risk of pericardial effusion (2.72 [1.45-5.12]; p = 0.002) and cardiac tamponade (2.76 [1.15-6.62]; p = 0.023), whereas PD-1/L1 inhibitors combined with chemotherapy did not increase the risk of pericardial effusion and cardiac tamponade (3.08 [0.93-10.21]; p = 0.066 and 3.27 [0.37-28.94]; p = 0.288, respectively). Conclusion: For patients with NSCLC, treatment with PD-1/L1 inhibitor monotherapy increases the risk of pericardial effusion and cardiac tamponade, but PD-1/L1 inhibitors combined with chemotherapy do not.

The Interplay of Hypoxia Signaling on Mitochondrial Dysfunction and Inflammation in Cardiovascular Diseases and Cancer: From Molecular Mechanisms to Therapeutic Approaches

Simple Summary

The regulation of hypoxia has recently emerged as having a central impact in mitochondrial function and dysfunction in various diseases, including the major disorders threatening worldwide: cardiovascular diseases and cancer. Despite the studies in this matter, its effective role in protection and disease progression even though its direct molecular mechanism in both disorders is still to be elucidated. This review aims to cover the current knowledge about the effect of hypoxia on mitochondrial function and dysfunction, and inflammation, in cardiovascular diseases and cancer, and reports further therapeutic strategies based on the modulation of hypoxic pathways.

Abstract

Cardiovascular diseases (CVDs) and cancer continue to be the primary cause of mortality worldwide and their pathomechanisms are a complex and multifactorial process. Insufficient oxygen availability (hypoxia) plays critical roles in the pathogenesis of both CVDs and cancer diseases, and hypoxia-inducible factor 1 (HIF-1), the main sensor of hypoxia, acts as a central regulator of multiple target genes in the human body. Accumulating evidence demonstrates that mitochondria are the major target of hypoxic injury, the most common source of reactive oxygen species during hypoxia and key elements for inflammation regulation during the development of both CVDs and cancer. Taken together, observations propose that hypoxia, mitochondrial abnormality, oxidative stress, inflammation in CVDs, and cancer are closely linked. Based upon these facts, this review aims to deeply discuss these intimate relationships and to summarize current significant findings corroborating the molecular mechanisms and potential therapies involved in hypoxia and mitochondrial dysfunction in CVDs and cancer.

Prevotellaceae produces butyrate to alleviate PD-1/PD-L1 inhibitor-related cardiotoxicity via PPARα-CYP4X1 axis in colonic macrophages

BACKGROUND

Immune checkpoint inhibitor-related cardiotoxicity is one of the most lethal adverse effects, and thus, the identification of underlying mechanisms for developing strategies to overcome it has clinical importance. This study aimed to investigate whether microbiota-host interactions contribute to PD-1/PD-L1 inhibitor-related cardiotoxicity.

METHODS

A mouse model of immune checkpoint inhibitor-related cardiotoxicity was constructed by PD-1/PD-L1 inhibitor BMS-1 (5 and 10 mg/kg), and cardiomyocyte apoptosis and cardiotoxicity were determined by hematoxylin and eosin, Masson's trichome and TUNEL assays. 16S rRNA sequencing was used to define the gut microbiota composition. Gut microbiota metabolites short-chain fatty acids (SCFAs) were determined by HPLC. The serum levels of myocardial enzymes (creatine kinase, aspartate transaminase, creatine kinase-MB and lactate dehydrogenase) and the production of M1 factors (TNF-α and IL-1β) were measured by ELISA. The colonic macrophage phenotype was measured by mmunofluorescence and qPCR. The expression of Claudin-1, Occludin, ZO-1 and p-p65 was measured by western blot. The gene expression of peroxisome proliferator-activated receptor α (PPARα) and cytochrome P450 (CYP) 4X1 was determined using qPCR. Statistical analyses were performed using Student's t-test for two-group comparisons, and one-way ANOVA followed by Student-Newman-Keul test for multiple-group comparisons.

RESULTS

We observed intestinal barrier injury and gut microbiota dysbiosis characterized by Prevotellaceae and Rikenellaceae genus depletion and Escherichia-Shigella and Ruminococcaceae genus enrichment, accompanied by low butyrate production and M1-like polarization of colonic macrophages in BMS-1 (5 and 10 mg/kg)-induced cardiotoxicity. Fecal microbiota transplantation mirrored the effect of BMS-1 on cardiomyocyte apoptosis and cardiotoxicity, while macrophage depletion and neutralization of TNF-α and IL-1β greatly attenuated BMS-1-induced cardiotoxicity. Importantly, Prevotella loescheii recolonization and butyrate supplementation alleviated PD-1/PD-L1 inhibitor-related cardiotoxicity. Mechanistically, gut microbiota dysbiosis promoted M1-like polarization of colonic macrophages and the production of proinflammatory factors TNF-α and IL-1β through downregulation of PPARα-CYP4X1 axis.

CONCLUSIONS

Intestinal barrier dysfunction amplifies PD-1/PD-L1 inhibitor-related cardiotoxicity by upregulating proinflammatory factors TNF-α and IL-1β in colonic macrophages via downregulation of butyrate-PPARα-CYP4X1 axis. Thus, targeting gut microbiota to polarize colonic macrophages away from the M1-like phenotype could provide a potential therapeutic strategy for PD-1/PD-L1 inhibitor-related cardiotoxicity.

Clinical Features and Outcomes of Immune Checkpoint Inhibitor-Associated Cardiovascular Toxicities

BACKGROUND

Despite the increasing prevalence of therapies utilizing immune checkpoint inhibitors (ICIs), the associated cardiovascular complications have been poorly reported. Given the fatality of ICI-related complications, especially myocarditis, optimal risk stratification to predict major adverse cardio- and cerebrovascular events (MACCEs) in patients receiving ICIs is mandatory.

METHODS

We collected clinical data from patients receiving ICIs, and the primary outcomes were MACCEs, including myocarditis, heart failure, and ischemic stroke. Other systemic immune responses relating to ICIs were also recorded. The median follow-up duration was 3 years.

RESULTS

Among 580 patients, the incidence of MACCEs was 3.9%. Older patients, male patients, and patients with lung cancer, liver cirrhosis, or diabetes had higher risks of MACCEs. There was no significant difference between the use of PD-1/PD-L1 inhibitors or CTLA inhibitors in terms of developing cardiovascular toxicities. The development of ICI-related MACCEs was associated with worse survival. Notably, after re-review by specialists, three patients eventually diagnosed with ICI-related myocarditis had not previously been identified. Only one was treated with pulse steroids, and none survived. The most common concomitant extracardiac immune-related adverse events were myositis/dermatitis, endocrine toxicity and hepatitis.

CONCLUSIONS

Collectively, ICIs may lead to severe cardiovascular toxicities and require more attention. Early identification, proper diagnosis, and prompt treatment are pivotal for improving survival.

A Novel Kinase Inhibitor AX-0085 Inhibits Interferon-γ-Mediated Induction of PD-L1 Expression and Promotes Immune Reaction to Lung Adenocarcinoma Cells

In this study, we describe a novel kinase inhibitor AX-0085 which can suppress the induction of PD-L1 expression by Interferon-γ (IFN-γ) in lung adenocarcinoma (LUAD) cells. AX-0085 effectively blocks JAK2/STAT1 signaling initiated by IFN-γ treatment and prevents nuclear localization of STAT1. Importantly, we demonstrate that AX-0085 reverses the IFN-γ-mediated repression of T cell activation in vitro and enhances the anti-tumor activity of anti-PD-1 antibody in vivo when used in combination. Finally, transcriptomic analyses indicated that AX-0085 is highly specific in targeting the IFN-γ-pathway, thereby raising the possibility of applying this reagent in combination therapy with checkpoint inhibitor antibodies. It may be particularly relevant in cases in which PD-L1-mediated T cell exhaustion leads to immunoevasive phenotypes.

The S Protein of SARS-CoV-2 Injures Cardiomyocytes Indirectly through the Release of Cytokines Instead of Direct Action

BACKGROUND

Emerging evidence has shown that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with cardiac injury, but it remains unclear whether cardiac injury is mainly caused by direct viral infection or is secondary to SARS-CoV-2-induced cytokine storm.

METHODS

Through directly treating cardiomyocytes with S protein, a crucial surface protein of SARS-CoV-2, and indirectly treating cardiomyocytes with S protein-derived human T lymphocyte conditioned medium, we compared the intensities of cardiomyocyte injuries caused by either S protein of the virus or S protein of virus-triggered cytokines.

RESULTS

The directly treated cardiomyocytes did not show increasing cell apoptosis. In contrast, cardiomyocytes treated with the supernatant medium of S protein pre-conditioned peripheral blood mononuclear cells showed significantly suppressed viability. In addition, using a cardiovascular disease-specific PCR array, genes associated with hypertrophy, apoptosis, inflammation and angiogenesis were observed to be affected by cytokine stress.

CONCLUSIONS

Collectively, we found that SARS-CoV-2-induced heart injury may be mainly through the S protein of the virus enhancing host immune responses instead of the S protein of the virus per se. With regards to clinical application, the strategy for treating COVID-19 should not only focus on anti-viral therapy but also on suppressing over-activated immunity.

Cardiac Toxicity Associated with Immune Checkpoint Inhibitors: A Systematic Review

Immune checkpoint inhibitors are immune stimulatory drugs used to treat many types of cancer. These drugs are antibodies against inhibitory proteins, such as CTLA-4 and PD-1/PD-L1, that are expressed on immune cells. When bound, they allow for increased stimulation of T cells to fight tumor cells. However, immune checkpoint inhibitors have several immune-related adverse effects. Many cases have come to light recently of cardiotoxicity as a result of treatment with these drugs. Cardiotoxicity from immune checkpoint inhibitors is unique due to its rarity and high mortality rate. Patients with this toxicity may present with myocarditis, pericarditis, Takotsubo cardiomyopathy, conduction disorders, and others within just a few weeks of starting immune checkpoint inhibitors. We present here a review of the current research on immune checkpoint inhibitors, their associated cardiotoxicities, the timing of presentation of these conditions, lab tests and histology for each condition, and finally the treatment of patients with cardiotoxicity. We observe a positive skew in the onset of presentation, which is significant for the treating physician.

Clinical implications of isolated troponinemia following immune checkpoint inhibitor therapy

Cardiovascular adverse events induced by immune checkpoint inhibitors (ICIs) have gained significant interest over the past decade due to their impact on short- and long-term outcomes. They were initially thought to be rare, but the increasing use of ICIs in the treatment of both advanced and early stages of various malignancies has resulted in a substantial increase in their incidence. Different guidelines have proposed screening measures for ICI-induced myocarditis by incorporating troponin measurements at baseline and during the first few weeks of treatment. However, no specific guidelines have been developed yet regarding the interpretation of an asymptomatic rise in troponins. This state-of-the art review aims to provide an overview of the clinical relevance of elevated troponins during checkpoint inhibition and recommendations on how to manage elevated troponin levels during ICI therapy.