Upregulation of Programmed Death-1 and Its Ligand in Cardiac Injury Models: Interaction with GADD153

Cardiovascular toxicities associated with immune checkpoint inhibitors

Cardiovascular toxicities associated with immune checkpoint inhibitors (ICIs) have been reported in case series but have been underappreciated due to their recent emergence, difficulties in diagnosis and non-specific clinical manifestations. ICIs are antibodies that block negative regulators of the T cell immune response, including cytotoxic T lymphocyte-associated protein-4 (CTLA-4), programmed cell death protein-1 (PD-1), and PD-1 ligand (PD-L1). While ICIs have introduced a significant mortality benefit in several cancer types, the augmented immune response has led to a range of immune-related toxicities, including cardiovascular toxicity. ICI-associated myocarditis often presents with arrhythmias, may co-exist with myositis and myasthenia gravis, can be severe, and portends a poor prognosis. In addition, pericardial disease, vasculitis, including temporal arteritis, and non-inflammatory heart failure, have been recently described as immune-related toxicities from ICI. This narrative review describes the epidemiology, diagnosis, pathophysiology, and treatment of cardiovascular toxicities of ICI therapy, highlighting recent developments in the field in the past year.

Cardiotoxicity danger in immunotherapy

Immunotherapy based on immune checkpoint inhibitors (ICIs) is currently broadly used in the treatment of different types of cancer. The treatment targeting programmed cell death protein 1/programmed death-ligand 1 axis is already approved by Food and Drug Administration for numerous cancers. These kinds of therapy brought spectacular results in the treatment of non-small cell lung cancer where systemic therapy was ineffective. However, a wide range of applied therapies based on ICIs in the clinic have led to unexpected side effects, such as severe cardiotoxicity. It needs to be underlined that the molecular mechanism of myocarditis in response to ICIs is still not fully understood. Lack of sufficient knowledge, especially concerning the kind of risk factors increasing probability of myocarditis, poses currently a large clinical problem. Continuous cardiac monitoring of patients who undergo ICI treatment presents another problem as it is cost-ineffective for the healthcare system. Herein, we highlight the risks of use of anticancer therapy based on ICIs. We also stress that detailed monitoring of any event of cardiotoxicity following ICIs treatment should be carefully investigated and registered to give a global overview of the frequency of myocarditis occurrence. Moreover, we propose that the extension of molecular and systemic knowledge of etiology of myocarditis as a side effect, including the role of protein kinases, will be highly beneficial for the medical field. Last but not least, better understanding of mechanisms of cardiotoxicity induction will improve the safety of cancer patients and will help clinicians in prediction of unexpected side effect occurrence.

Cardiotoxicity with immune system targeting drugs: a meta-analysis of anti-PD/PD-L1 immunotherapy randomized clinical trials

Background: With antiprogrammed death receptor-1 (anti-PD-L1) therapy, a recent meta-analysis reported higher incidence of cutaneous, endocrine and gastrointestinal complications especially with dual anti-PD-L1 immunotherapy (IMM). Methods: Our primary outcome was assessment of all cardiotoxicity grades in IMM compared with different treatments, thus a systemic review and a meta-analysis on randomized clinical trials (RCTs) were done. Results: We included 11 RCTs with 6574 patients (3234 patients in IMM arm vs 3340 patients in the other arm). Three non-small-cell lung cancer RCTs, seven melanoma RCTs and only one prostatic cancer RCT met the inclusion criteria. There were five RCTs that compared monoimmunotherapy to chemotherapy "(n = 2631 patients)". No difference exists in all cardiotoxicity grades or high-grade cardiotoxicity (p > 0.05). Lung cancer exhibited a higher response rate and lower mortality in IMM. Conclusion: There was no reported statistically significant cardiotoxicity associated with anti-PD/PD-L1 use. Lung cancer subgroups showed better response and survival rates.

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

Aim: Immunological checkpoint therapy is considered a powerful method for cancer therapy and acts by re-activating autologous T cells to kill the cancer cell. Myocarditis cases have been reported in cancer patients after immunological therapy; for example, nivolumab treatment is a monoclonal antibody that blocks programmed cell death-1/programmed cell death ligand-1 ligand interaction. This project provided insight into the inflammatory response as a benchmark to investigate the potential cardiotoxic effect of T cell response to the programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) axis in regulating cardiomyocyte injury in vitro. Methods and Results: We investigated cardiomyopathy resulted from the PD-1/PD-L1 axis blockade using the anti-PD-1 antibody in Rockefeller University embryonic stem cells-derived cardiomyocytes (RUES2-CMs) and a melanoma tumor-bearing murine model. We found that nivolumab alone did not induce inflammatory-related proteins, including PD-L1 expression, and did not induce apoptosis, which was contrary to doxorubicin, a cardiotoxic chemotherapy drug. However, nivolumab was able to exacerbate the immune response by increasing cytokine and inflammatory gene expression in RUES2-CMs when co-cultured with CD4⁺ T lymphocytes and induced apoptosis. This effect was not observed when RUES2-CMs were co-cultured with CD8⁺ T lymphocytes. The in vivo model showed that the heart function of tumor-bearing mice was decreased after treatment with anti-PD-1 antibody and demonstrated a dilated left ventricle histological examination. The dilated left ventricle was associated with an infiltration of CD4⁺ and CD8⁺ T lymphocytes into the myocardium. PD-L1 and inflammatory-associated gene expression were significantly increased in anti-PD-1-treated tumor-bearing mice. Cleaved caspase-3 and mouse plasma cardiac troponin I expressions were increased significantly. Conclusion: PD-L1 expression on cardiomyocytes suppressed T-cell function. Blockade of PD-1 by nivolumab enhanced cardiomyocyte inflammation and apoptosis through the enhancement of T-cell response towards cardiomyocytes.

MicroRNAs in Cancer Treatment-Induced Cardiotoxicity

Cancer treatment has made significant progress in the cure of different types of tumors. Nevertheless, its clinical use is limited by unwanted cardiotoxicity. Aside from the conventional chemotherapy approaches, even the most newly developed, i.e., molecularly targeted therapy and immunotherapy, exhibit a similar frequency and severity of toxicities that range from subclinical ventricular dysfunction to severe cardiomyopathy and, ultimately, congestive heart failure. Specific mechanisms leading to cardiotoxicity still remain to be elucidated. For instance, oxidative stress and DNA damage are considered key players in mediating cardiotoxicity in different treatments. microRNAs (miRNAs) act as key regulators in cell proliferation, cell death, apoptosis, and cell differentiation. Their dysregulation has been associated with adverse cardiac remodeling and toxicity. This review provides an overview of the cardiotoxicity induced by different oncologic treatments and potential miRNAs involved in this effect that could be used as possible therapeutic targets.

Clinical Characteristics and Treatment of Immune-Related Adverse Events of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have been changing the paradigm of cancer treatment. However, immune-related adverse effects (irAEs) have also increased with the exponential increase in the use of ICIs. ICIs can break up the immunologic homeostasis and reduce T-cell tolerance. Therefore, inhibition of immune checkpoint can lead to the activation of autoreactive T-cells, resulting in various irAEs similar to autoimmune diseases. Gastrointestinal toxicity, endocrine toxicity, and dermatologic toxicity are common side effects. Neurotoxicity, cardiotoxicity, and pulmonary toxicity are relatively rare but can be fatal. ICI-related gastrointestinal toxicity, dermatologic toxicity, and hypophysitis are more common with anti- CTLA-4 agents. ICI-related pulmonary toxicity, thyroid dysfunction, and myasthenia gravis are more common with PD-1/PD-L1 inhibitors. Treatment with systemic steroids is the principal strategy against irAEs. The use of immune-modulatory agents should be considered in case of no response to the steroid therapy. Treatment under the supervision of multidisciplinary specialists is also essential, because the symptoms and treatments of irAEs could involve many organs. Thus, this review focuses on the mechanism, clinical presentation, incidence, and treatment of various irAEs.

Clinical Characteristics and Treatment of Immune-Related Adverse Events of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICIs) have been changing the paradigm of cancer treatment. However, immune-related adverse effects (irAEs) have also increased with the exponential increase in the use of ICIs. ICIs can break up the immunologic homeostasis and reduce T-cell tolerance. Therefore, inhibition of immune checkpoint can lead to the activation of autoreactive T-cells, resulting in various irAEs similar to autoimmune diseases. Gastrointestinal toxicity, endocrine toxicity, and dermatologic toxicity are common side effects. Neurotoxicity, cardiotoxicity, and pulmonary toxicity are relatively rare but can be fatal. ICI-related gastrointestinal toxicity, dermatologic toxicity, and hypophysitis are more common with anti- CTLA-4 agents. ICI-related pulmonary toxicity, thyroid dysfunction, and myasthenia gravis are more common with PD-1/PD-L1 inhibitors. Treatment with systemic steroids is the principal strategy against irAEs. The use of immune-modulatory agents should be considered in case of no response to the steroid therapy. Treatment under the supervision of multidisciplinary specialists is also essential, because the symptoms and treatments of irAEs could involve many organs. Thus, this review focuses on the mechanism, clinical presentation, incidence, and treatment of various irAEs.

T cell co-stimulation and co-inhibition in cardiovascular disease: a double-edged sword

The role of inflammation in cardiovascular disease (CVD) is now widely accepted. Immune cells, including T cells, are influenced by inflammatory signals and contribute to the onset and progression of CVD. T cell activation is modulated by T cell co-stimulation and co-inhibition pathways. Immune checkpoint inhibitors (ICIs) targeting T cell inhibition pathways have revolutionized cancer treatment and improved survival in patients with cancer. However, ICIs might induce cardiovascular toxicity via T cell re-invigoration. With the rising use of ICIs for cancer treatment, a timely overview of the role of T cell co-stimulation and inhibition molecules in CVD is desirable. In this Review, the importance of these molecules in the pathogenesis of CVD is highlighted in preclinical studies on models of CVD such as vein graft disease, myocarditis, graft arterial disease, post-ischaemic neovascularization and atherosclerosis. This Review also discusses the therapeutic potential of targeting T cell co-stimulation and inhibition pathways to treat CVD, as well as the possible cardiovascular benefits and adverse events after treatment. Finally, the Review emphasizes that patients with cancer who are treated with ICIs should be monitored for CVD given the reported association between the use of ICIs and the risk of cardiovascular toxicity.

Cardiotoxicity of Immune Checkpoint Inhibitors

PURPOSE OF REVIEW

Immunotherapies, particularly immune checkpoint inhibitors (ICI), are revolutionary cancer therapies being increasingly applied to a broader range of cancers. Our understanding of the mechanism, epidemiology, diagnosis, and treatment of cardiotoxicity related to immunotherapies remains limited. We aim to synthesize the limited current literature on cardiotoxicity of ICIs and to share our opinions on the diagnosis and treatment of this condition.

RECENT FINDINGS

The incidence of ICI-associated myocarditis ranges from 0.1 to 1%. Patients with ICI-associated myocarditis often have a fulminant course with a case fatality rate of 25-50%. The diagnosis of this condition poses many challenges because independently a normal electrocardiogram, biomarkers, or a preserved left ventricular function do not rule out ICI-associated myocarditis. Endomyocardial biopsy should be pursued when clinical suspicion remains despite normal non-invasive tests. Data on optimal screening and surveillance tools are lacking. Cessation of ICIs, combined with high dose corticosteroids and other immunosuppressant approaches are the cornerstones of the treatment of ICI-associated myocarditis. This condition may recur when patients are re-challenged with these agents and the decision to resume ICIs should be made through a multidisciplinary discussion. Immunotherapies have changed the landscape of cancer treatment. Recognizing and managing cardiotoxicity related to ICIs is of critical importance. Our understanding of ICI-cardiotoxicity has improved, but large information gaps remain for further research. Due to the high case fatality rate, any type of cardiac symptoms or signs in a patient who has recently started an ICI should prompt consideration of ICI-cardiotoxicity.

Cardiac toxicity of immune-checkpoint inhibitors: a clinical case of nivolumab-induced myocarditis and review of the evidence and new challenges

Immune checkpoint inhibitors have revolutionized cancer treatment due to their undeniable efficacy, but a range of new adverse events (AE) has emerged. In particular, cardiac toxicity is a potentially fatal AE, and introduces new challenges regarding its underlying molecular mechanisms of occurrence, optimal treatment and follow up, and prevention. We present a clinical case of a patient with advanced kidney cancer treated with nivolumab as a third line treatment. After four cycles, the patient developed nonspecific symptoms and was hospitalized, identifying a set of clinical, analytical and electrocardiographic alterations compatible with myocarditis. Despite the intensive support, the patient died and a necropsy study was performed. We present a detailed description of the clinical case including the pathological and molecular findings, and we conduct a review of the available evidence related to immune-mediated cardiac toxicity to offer some new highlights in the management of this AE.

Immune checkpoint inhibitors and cardiovascular toxicity

Immune checkpoint inhibitors are a new class of anticancer therapies that amplify T-cell-mediated immune responses against cancer cells. Immune checkpoint inhibitors have shown important benefits in phase 3 trials, and several agents have been approved for specific malignancies. Although adverse events from immune checkpoint inhibitors are a common occurrence, cardiotoxic effects are uncommon, but are often serious complications with a relatively high mortality. Most cardiotoxic effects appear to be inflammatory in nature. Clinical assessment of a combination of biomarkers, electrocardiography, cardiac imaging, and endomyocardial biopsy can be used to confirm a possible diagnosis. In this Review, we discuss the epidemiology of immune checkpoint inhibitor-mediated cardiotoxic effects, as well as their clinical presentation, subtypes, risk factors, pathophysiology, and clinical management, including the introduction of a new surveillance strategy.

Cardiac Immune-Related Adverse Events in Immune Checkpoint Inhibition Therapy

Immune checkpoint inhibitors present clinicians with both an exciting step forward in cancer treatment and the unknown possibilities of an unshackled immune system. The latter phenomena, known as immune-related adverse events (irAEs), are of particular interest because they may affect any organ system with autoimmune-like pathologies, such as hepatitis and colitis. Within the cardiovascular system, irAEs associated with immune checkpoint blockade exist as a broad clinical spectrum, with autoimmune myocarditis being the best-characterized entity at this time. In general, irAEs are often reversible with immunosuppression. However, irAEs that affect the cardiovascular system pose the possibility of a rapid and fatal clinical deterioration. The mortality attributed to immune checkpoint blockade-associated autoimmune myocarditis, as reported in the WHO database, exists from 36% to 67%, dependent on the therapeutic regimen. Yet, despite the potential severity such events pose, guidelines dictating the identification of immune checkpoint inhibition irAEs do not exist, providing a stark contrast with other anticancer medications with known cardiovascular effects. The lack of guidelines may be related to the perceived rarity of these events, yet a recent study of immune checkpoint inhibition-associated autoimmune myocarditis suggests that this clinical entity may be more prevalent than initially believed. Until more standardized information regarding these potentially serious events is available, the study of documented cases is instructive to improve identification of such phenomena, as well as the outcomes for patients who develop them.

Sequential Blockade of PD-1 and PD-L1 Causes Fulminant Cardiotoxicity-From Case Report to Mouse Model Validation

The combined administration of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) inhibitors might be considered as a treatment for poorly responsive cancer. We report a patient with brain metastatic lung adenocarcinoma in whom fatal myocarditis developed after sequential use of PD-1 and PD-L1 inhibitors. This finding was validated in syngeneic tumor-bearing mice. The mice bearing lung metastases of CT26 colon cancer cells treated with PD-1 and/or PD-L1 inhibitors showed that the combination of anti-PD-1 and anti-PD-L1, either sequentially or simultaneously administered, caused myocarditis lesions with myocyte injury and patchy mononuclear infiltrates in the myocardium. A significant increase of infiltrating neutrophils in myocytes was noted only in mice with sequential blockade, implying a role for the pathogenesis of myocarditis. Among circulating leukocytes, concurrent and subsequent treatment of PD-1 and PD-L1 inhibitors led to sustained suppression of neutrophils. Among tumor-infiltrating leukocytes, combinatorial blockade increased CD8⁺ T cells and NKG2D⁺ T cells, and reduced tumor-associated macrophages, neutrophils, and natural killer (NK) cells in the lung metastatic microenvironment. The combinatorial treatments exhibited better control and anti-PD-L1 followed by anti-PD-1 was the most effective. In conclusion, the combinatory use of PD-1 and PD-L1 blockade, either sequentially or concurrently, may cause fulminant cardiotoxicity, although it gives better tumor control, and such usage should be cautionary.

Immune Checkpoint Inhibitor-Associated Pericarditis

Side effects of immune checkpoint inhibitors, termed immune-related adverse events, are relatively common, but immune checkpoint inhibitor-mediated cardiotoxicities are rare; however, they can be serious and potentially fatal. Pericarditis is an infrequent cardiac toxicity of immunotherapy and predisposing factors remain unknown. Here we report three patients with NSCLC who developed pericarditis during therapy with programmed death 1/programmed death ligand 1+/- CTLA-4 inhibitors. We review the clinical presentation of these three cases and histopathologic findings from autopsies from the first two patients and a pericardial sampling that has been obtained from a pericardial window procedure in the third patient who recovered from the pericarditis episode. We also discuss the potential mechanisms, as well as what is known about pericarditis secondary to immune-related adverse events.

Cardio-toxicity of checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have started revolutionizing the treatment of numerous advanced oncological diseases by restoring immune resistance against cancer cells. ICI-associated cardiac adverse effects are rare, but severe. About 50% of cardiac complications comprise myocarditis with variable clinical presentation and a high rate of fatality. The pathomechanism is incompletely understood and may involve preexisting autoimmunity such as autoantibodies or common epitopes shared by cardiomyocytes and tumor cells. Especially patients at risk might be followed up by serial troponin measurements in order to allow an early identification of ICI-associated myocarditis. Therapeutic options are limited and consist of early discontinuation of ICI treatment and initiation of an immunosuppression. Further studies are necessary to elucidate the mechanism, define diagnostic criteria, improve surveillance of patients at risk, and finally refine therapy.

Cardiac morbidity in HIV infection is associated with checkpoint inhibitor LAG-3 on CD4 T cells

Recent findings point to a role of Checkpoint Inhibitor (CPI) receptors at the tissue level in immune homeostasis. Here we investigated the role of CPI molecules on immune cells in relation to cardiac function. Participants recruited in Chennai, India consisted of HIV+ ART naive viremic (Gp1 n = 102), HIV+ on ART, virologically suppressed (Gp2, n = 172) and HIV negative healthy controls (Gp3, n = 64). A cross-sectional analysis of cardiac function, arterial resistance and immunologic assessment of CPI expressing T cells was performed. Data indicate that ART naive exhibited cardiac function impairment and greater arterial stiffness than the other groups. Frequencies of CD4+ T cells expressing LAG-3 and PD1 were higher in ART naïve while TIGIT and TIM3 were similar among the patient groups. LAG-3+, PD1+ and dual LAG-3+PD1+ CD4 T cells were inversely correlated with cardiac function and arterial elasticity and directly with arterial stiffness in ART naïve participants and with arterial elasticity in virally suppressed group on ART. We conclude that HIV induced upregulation of LAG-3 singly or in combination with PD1 in immune cells may regulate cardiac health and warrant mechanistic investigations. The implications of these findings have bearing for the potential utility of anti-LAG-3 immunotherapy for cardiac dysfunction in chronic HIV infection.

Impact of cannabidiol treatment on regulatory T-17 cells and neutrophil polarization in acute kidney injury

Hallmark features of acute kidney injury (AKI) include mobilization of immune and inflammatory mechanisms culminating in tissue injury. Emerging information indicates heterogeneity of neutrophils with pro- and anti-inflammatory functions (N1 and N2, respectively). Also, regulatory T-17 (Treg17) cells curtail T helper 17 (Th-17)-mediated proinflammatory responses. However, the status of Treg17 cells and neutrophil phenotypes in AKI are not established. Furthermore, cannabidiol exerts immunoregulatory effects, but its impact on Treg17 cells and neutrophil subtypes is not established. Thus, we examined the status of Treg17 cells and neutrophil subtypes in AKI and determined whether cannabidiol favors regulatory neutrophils and T cells accompanied with renoprotection. Accordingly, mice were subjected to bilateral renal ischemia-reperfusion injury (IRI), without or with cannabidiol treatment; thereafter, kidneys were processed for flow cytometry analyses. Renal IRI increased N1 and Th-17 but reduced N2 and Treg17 cells accompanied with disruption of mitochondrial membrane potential (ψ_m) and increased apoptosis/necrosis and kidney injury molecule-1 (KIM-1) immunostaining compared with their sham controls. Importantly, cannabidiol treatment preserved ψ_m and reduced cell death and KIM-1 accompanied by restoration of N1 and N2 imbalance and preservation of Treg17 cells while decreasing Th-17 cells. The ability of cannabidiol to favor development of Treg17 cells was further established using functional mixed lymphocytic reaction. Subsequent studies showed higher renal blood flow and reduced serum creatinine in cannabidiol-treated IRI animals. Collectively, our novel observations establish that renal IRI causes neutrophil polarization in favor of N1 and also reduces Treg17 cells in favor of Th-17, effects that are reversed by cannabidiol treatment accompanied with significant renoprotection.

Oral NaHCO3 Activates a Splenic Anti-Inflammatory Pathway: Evidence That Cholinergic Signals Are Transmitted via Mesothelial Cells

We tested the hypothesis that oral NaHCO₃ intake stimulates splenic anti-inflammatory pathways. Following oral NaHCO₃ loading, macrophage polarization was shifted from predominantly M1 (inflammatory) to M2 (regulatory) phenotypes, and FOXP3⁺CD4⁺ T-lymphocytes increased in the spleen, blood, and kidneys of rats. Similar anti-inflammatory changes in macrophage polarization were observed in the blood of human subjects following NaHCO₃ ingestion. Surprisingly, we found that gentle manipulation to visualize the spleen at midline during surgical laparotomy (sham splenectomy) was sufficient to abolish the response in rats and resulted in hypertrophy/hyperplasia of the capsular mesothelial cells. Thin collagenous connections lined by mesothelial cells were found to connect to the capsular mesothelium. Mesothelial cells in these connections stained positive for the pan-neuronal marker PGP9.5 and acetylcholine esterase and contained many ultrastructural elements, which visually resembled neuronal structures. Both disruption of the fragile mesothelial connections or transection of the vagal nerves resulted in the loss of capsular mesothelial acetylcholine esterase staining and reduced splenic mass. Our data indicate that oral NaHCO₃ activates a splenic anti-inflammatory pathway and provides evidence that the signals that mediate this response are transmitted to the spleen via a novel neuronal-like function of mesothelial cells.

Cardiotoxicity of immune checkpoint inhibitors

Cardiac toxicity after conventional antineoplastic drugs (eg, anthracyclines) has historically been a relevant issue. In addition, targeted therapies and biological molecules can also induce cardiotoxicity. Immune checkpoint inhibitors are a novel class of anticancer drugs, distinct from targeted or tumour type-specific therapies. Cancer immunotherapy with immune checkpoint blockers (ie, monoclonal antibodies targeting cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), programmed cell death 1 (PD-1) and its ligand (PD-L1)) has revolutionised the management of a wide variety of malignancies endowed with poor prognosis. These inhibitors unleash antitumour immunity, mediate cancer regression and improve the survival in a percentage of patients with different types of malignancies, but can also produce a wide spectrum of immune-related adverse events. Interestingly, PD-1 and PD-L1 are expressed in rodent and human cardiomyocytes, and early animal studies have demonstrated that CTLA-4 and PD-1 deletion can cause autoimmune myocarditis. Cardiac toxicity has largely been underestimated in recent reviews of toxicity of checkpoint inhibitors, but during the last years several cases of myocarditis and fatal heart failure have been reported in patients treated with checkpoint inhibitors alone and in combination. Here we describe the mechanisms of the most prominent checkpoint inhibitors, specifically ipilimumab (anti-CTLA-4, the godfather of checkpoint inhibitors) patient and monoclonal antibodies targeting PD-1 (eg, nivolumab, pembrolizumab) and PD-L1 (eg, atezolizumab). We also discuss what is known and what needs to be done about cardiotoxicity of checkpoint inhibitors in patients with cancer. Severe cardiovascular effects associated with checkpoint blockade introduce important issues for oncologists, cardiologists and immunologists.

Fibrinogen-like protein-2 causes deterioration in cardiac function in experimental autoimmune myocarditis rats through regulation of programmed death-1 and inflammatory cytokines

Programmed death-1 (PD-1) plays an important role in protecting against inflammation and myocyte damage in T-cell-mediated myocarditis. To understand whether fibrinogen-like protein-2 (FGL2) can affect the role of the PD-1/PD-L1 pathway in experimental autoimmune myocarditis (EAM), we investigated cardiac function in EAM rats over-expressing FGL2. Over-expression of FGL2 significantly decreased PD-1 and deteriorated cardiac function in rats with autoimmune myocarditis. Histopathology revealed increased inflammatory cell infiltrate in EAM-FGL2 rats compared with the control groups (EAM, EAM-GFP and NC). Notably, transcription factor forkhead box P3 (Foxp3) and retinoic acid-related orphan receptor γt (RORγt) protein and mRNA levels were statistically (P < 0·05) increased in EAM rats. We also found that interferon-γ, interleukin-6, interleukin-17 and brain natriuretic peptide levels were profoundly increased in serum of FGL2 over-expressing EAM rats. Hence, FGL2 plays an important role in the pathogenesis of autoimmune myocarditis that also involves the PD-1/PD-L1 pathway. Our findings may provide novel therapeutic targets for the treatment of immune-induced heart injury.

Immunological Properties of Murine Parthenogenetic Stem Cell-Derived Cardiomyocytes and Engineered Heart Muscle

Pluripotent parthenogenetic stem cells (pSCs) can be derived by pharmacological activation of unfertilized oocytes. Homozygosity of the major histocompatibility complex (MHC) in pSCs makes them an attractive cell source for applications in allogeneic tissue repair. This was recently demonstrated for pSC-based tissue-engineered heart repair. A detailed analysis of immunological properties of pSC-derived cardiomyocytes and engineered heart muscle (EHM) thereof is, however, lacking. The aim of this study was to determine baseline and cytokine-inducible MHC class I and MHC class II as well as programmed death ligand-1 (PDL-1) and co-stimulatory protein (CD40, CD80, CD86) expression in pSC-derived cardiomyocytes and pSC-EHM in vitro and in vivo. Cardiomyocytes from an MHC-homologous (H2^d/d) pSC-line were enriched to ~90% by making use of a recently developed cardiomyocyte-specific genetic selection protocol. MHC class I and MHC class II expression in cardiomyocytes could only be observed after stimulation with interferon gamma (IFN-γ). PDL-1 was markedly upregulated under IFN-γ. CD40, CD80, and CD86 were expressed at low levels and not upregulated by IFN-γ. EHM constructed from H2^d/d cardiomyocytes expressed similarly low levels of MHC class I, MHC class II, and costimulatory molecules under basal conditions. However, in EHM only MHC class I, but not MHC class II, molecules were upregulated after IFN-γ-stimulation. We next employed a cocultivation system with MHC-matched and MHC-mismatched splenocytes and T-cells to analyze the immune stimulatory properties of EHMs. Despite MHC-mismatched conditions, EHM did not induce splenocyte or T-cell proliferation in vitro. To evaluate the immunogenicity of pSC-derived cardiomyocytes in vivo, we implanted pSC-derived embryoid bodies after elimination of non-cardiomyocytes (cardiac bodies) under the kidney capsules of MHC-matched and -mismatched mice. Spontaneous beating of cardiac bodies could be observed for 28 days in the matched and for 7 days in the mismatched conditions. Teratomas formed after 28 days only in the MHC-matched conditions. Immunohistochemistry revealed single clusters of CD3-positive cells in the border zone of the implant in the mismatched conditions with few CD3-positive cells infiltrating the implant. Taken together, MHC-matched pSC-cardiomyocyte allografts show little immune cell activation, offering an explanation for the observed long-term retention of pSC-EHM allografts in the absence of immunosuppression.

Mitochondrial N-formyl peptides cause airway contraction and lung neutrophil infiltration via formyl peptide receptor activation

Respiratory failure is a common characteristic of systemic inflammatory response syndrome (SIRS) and sepsis. Trauma and severe blood loss cause the release of endogenous molecules known as damage-associated molecular patterns (DAMPs). Mitochondrial N-formyl peptides (F-MITs) are DAMPs that share similarities with bacterial N-formylated peptides, and are potent immune system activators. Recently, we observed that hemorrhagic shock-induced increases in plasma levels of F-MITs associated with lung damage, and that antagonism of formyl peptide receptors (FPR) ameliorated hemorrhagic shock-induced lung injury in rats. Corroborating these data, in the present study, it was observed that F-MITs expression is higher in plasma samples from trauma patients with SIRS or sepsis when compared to control trauma group. Therefore, to better understand the role of F-MITs in the regulation of lung and airway function, we studied the hypothesis that F-MITs lead to airway contraction and lung inflammation. We observed that F-MITs induced concentration-dependent contraction in trachea, bronchi and bronchioles. However, pre-treatment with mast cells degranulator or FPR antagonist decreased this response. Finally, intratracheal challenge with F-MITs increased neutrophil elastase expression in lung and inducible nitric oxide synthase and cell division control protein 42 expression in all airway segments. These data suggest that F-MITs could be a putative target to treat respiratory failure in trauma patients.

Altered Maturation Status and Possible Immune Exhaustion of CD8 T Lymphocytes in the Peripheral Blood of Patients Presenting With Acute Coronary Syndromes

OBJECTIVE

Inflammation in response to oxidized lipoproteins is thought to play a key role in acute coronary syndromes (ACS), but the pattern of immune activation has not been fully characterized. We sought to perform detailed phenotypic and functional analysis of CD8 T lymphocytes from patients presenting with ACS to determine activation patterns and potential immunologic correlates of ACS.

APPROACH AND RESULTS

We used polychromatic flow cytometry to analyze the cytokine production profiles of naïve, effector, and memory CD8 T cells in patients with ACS compared with control subjects with stable coronary artery disease. ACS was associated with an altered distribution of circulating CD8(+) T-cell maturation subsets with reduced proportions of naïve cells and expansion of effector memory cells. ACS was also accompanied by impaired interleukin-2 production by phenotypically naïve CD8 T cells. These results were validated in a second replication cohort. Naïve CD8 cells from patients with ACS also had increased expression of programmed cell death-1, which correlated with interleukin-2 hypoproduction. In vitro, stimulation of CD8 T cells with oxidized low-density lipoprotein was sufficient to cause programmed cell death-1 upregulation and diminished interleukin-2 production by naïve CD8 T cells.

CONCLUSIONS

In this exploratory analysis, naïve CD8(+) T cells from patients with ACS show phenotypic and functional characteristics of immune exhaustion: impaired interleukin-2 production and programmed cell death-1 upregulation. Exposure to oxidized low-density lipoprotein recapitulates these features in vitro. These data provide evidence that oxidized low-density lipoprotein could play a role in immune exhaustion, and this immunophenotype may be a biomarker for ACS.

RhNRG-1β Protects the Myocardium against Irradiation-Induced Damage via the ErbB2-ERK-SIRT1 Signaling Pathway

Radiation-induced heart disease (RIHD), which is a serious side effect of the radiotherapy applied for various tumors due to the inevitable irradiation of the heart, cannot be treated effectively using current clinical therapies. Here, we demonstrated that rhNRG-1β, an epidermal growth factor (EGF)-like protein, protects myocardium tissue against irradiation-induced damage and preserves cardiac function. rhNRG-1β effectively ameliorated irradiation-induced myocardial nuclear damage in both cultured adult rat-derived cardiomyocytes and rat myocardium tissue via NRG/ErbB2 signaling. By activating ErbB2, rhNRG-1β maintained mitochondrial integrity, ATP production, respiratory chain function and the Krebs cycle status in irradiated cardiomyocytes. Moreover, the protection of irradiated cardiomyocytes and myocardium tissue by rhNRG-1β was at least partly mediated by the activation of the ErbB2-ERK-SIRT1 signaling pathway. Long-term observations further showed that rhNRG-1β administered in the peri-irradiation period exerts continuous protective effects on cardiac pump function, the myocardial energy metabolism, cardiomyocyte volume and interstitial fibrosis in the rats receiving radiation via NRG/ErbB2 signaling. Our findings indicate that rhNRG-1β can protect the myocardium against irradiation-induced damage and preserve cardiac function via the ErbB2-ERK-SIRT1 signaling pathway.