Evidence for CTLA4 as a susceptibility gene for dilated cardiomyopathy

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.

Cellular Alterations in Immune Checkpoint Inhibitor Therapy-Related Cardiac Dysfunction

PURPOSE OF REVIEW

Immune checkpoint inhibitor (ICI) therapy has emerged as a pivotal advancement in cancer treatment, but the widespread adoption has given rise to a growing number of reports detailing significant cardiovascular toxicity. This review concentrates on elucidating the mechanisms behind ICI-related cardiovascular complications, emphasizing preclinical and mechanistic data.

RECENT FINDINGS

Accumulating evidence indicates a more significant role of immune checkpoints in maintaining cardiac integrity than previously understood, and new key scientific data are available to improve our understanding of ICI-related cardiovascular toxicity, including hidden cardiotoxicity. New avenues for innovative concepts are hypothesized, and opportunities to leverage the knowledge from ICI-therapy for pioneering approaches in related scientific domains can be derived from the latest scientific projects. Cardiotoxicity from ICI therapy is a paramount challenge for cardio-oncology. Understanding the underlying effects builds the foundation for tailored cardioprotective approaches in the growing collective at risk for severe cardiovascular complications.

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.

Association of CTLA4 and NFKB1 polymorphisms with chronic heart failure: a case-control study in the Chinese population

Previous works have demonstrated the involvement of cytotoxic T-lymphocyte antigen 4 (CTLA-4) and nuclear factor kappa B (NF-κB) in maintaining the normal physiology of the heart. Polymorphisms in genes encoding these proteins may affect their normal functions, which could subsequently lead to chronic heart failure (CHF). In this work, we examined the association of CTLA4 and NFKB1 polymorphisms with CHF in a Chinese population. The −318C>T and +49A>G polymorphisms of CTLA4 and −94 insertion/deletion ATTG polymorphism of NFKB1 were genotyped on 538 patients with CHF and 1076 healthy controls. Our data indicate that the CTLA4 +49A>G and NFKB1 polymorphisms could confer susceptibility to CHF among Chinese. A significantly increased CHF risk was observed for the mutant CTLA4 +49GG genotype ( P = 0.0093), and both heterozygous ATTG1/ATTG2 ( P = 0.0142) and mutant ATTG2/ATTG2 ( P = 0.0018) genotypes of NFKB1. Our data suggest that there is a potential use of these polymorphisms for early genetic screening for CHF.

Heart failure in cancer: role of checkpoint inhibitors

The introduction of immune checkpoint inhibitors have greatly improved clinical outcomes in several cancer types, revolutionizing the management of a wide variety of tumors endowed with poor prognosis. Despite its success, high grade immune related adverse events were observed in patients treated with checkpoint inhibitors. While cardiotoxicity was largely underestimated in initial studies, numerous reports of fulminant myocarditis and fatal heart failure (HF) have been recently described. In this review we discuss possible mechanisms involved in cardiac toxicity triggered by inhibition of cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1) pathway, the most prominent checkpoint inhibitors available in the clinic. Major cardiovascular events associated with checkpoint inhibitors adds another layer of complexity in cancer therapy and urges for an interdisciplinary approach between oncologists, cardiologists, and immunologist.

Potential cardiac risk of immune-checkpoint blockade as anticancer treatment: What we know, what we do not know, and what we can do to prevent adverse effects

Cancer immunotherapy has become a well-established treatment option for some cancers after the development of a family of drugs targeting the so-called immune checkpoints, such as CTLA4 and PD-1 with PD-L1. These co-receptors/ligands inhibit the activation of T-cell, thus preventing an excessive inflammatory response. Tumors exploit these pathways to induce immune tolerance to themselves. Thus, the main effect of checkpoint-blocking drugs is to awake an immune response primarily directed against cancer cells. Nonetheless, as the immune response elicited by these drugs is not completely tumor-specific, their use may actually cause several adverse effects, including adverse cardiovascular effects. In this review, we will discuss the principles and potentiality of immunotherapy for cancer treatment, the experimental and clinical data on the role of CTLA4 and PD-1 with PD-L1 as immune-checkpoints in the cancer environment and in the cardiovascular system, and strategies aimed at preventing possible cardiovascular adverse effects of immune-checkpoint blockers.

Common variants in IL-17A/IL-17RA axis contribute to predisposition to and progression of congestive heart failure

Heart failure is characterized by immune activation leading to production and release of proinflammatory cytokines. Interleukin 17A (IL-17A) is a proinflammatory cytokine and multiple lines of evidence from animal and human studies suggest crucial roles of IL-17A in heart failure. Therefore, we investigated whether common polymorphisms of genes IL17A and IL17RA (coding interleukin 17 receptor A) contribute to genetic predisposition to heart failure and adverse clinical outcomes associated with it.A total of 1713 adult patients with congestive heart failure and 1713 age- and sex-matched controls were genotyped for promoter single nucleotide polymorphisms (SNPs), rs2275913 and rs8193037 in IL17A and rs4819554 in IL17RA, to assess the relationship between individual SNPs and the risk of congestive heart failure. Results showed that rs8193037 in IL17A was associated with the risk of congestive heart failure (odds ratio [OR] = 0.76; 95% confidence interval [CI] 0.63-0.90, adjusted P = 0.002) after adjustment for multiple cardiovascular risk factors including age, sex, smoking status, diabetes, hypertension, and dyslipidemia. This association was evident in both ischemic and nonischemic heart failure (P = 0.005 and P = 0.05, respectively). Furthermore, prospective follow-up of 12.7 months for the occurrence of adverse clinical outcomes showed that rs4819554 in IL17RA was significantly associated with cardiovascular mortality (hazard ratio [HR] = 1.28; 95% CI = 1.02-1.59, adjusted P = 0.03) after adjustments for multiple cardiovascular risk factors and New York Heart Association functional class.This study demonstrated associations of rs8193037 in the promoter of IL17A with the risk of congestive heart failure, and of rs4819554 in the promoter of IL17RA with the risk of cardiovascular mortality in patients with congestive heart failure. These data lend further support to the notion that immune activation and genetic polymorphisms contribute to heart failure pathogenesis and progression.

Genetic polymorphisms associated with heart failure: A literature review

Objective

To review possible associations reported between genetic variants and the risk, therapeutic response and prognosis of heart failure.

Methods

Electronic databases (PubMed, Web of Science and CNKI) were systematically searched for relevant papers, published between January 1995 and February 2015.

Results

Eighty-two articles covering 29 genes and 39 polymorphisms were identified.

Conclusion

Genetic association studies of heart failure have been highly controversial. There may be interaction or synergism of several genetic variants that together result in the ultimate pathological phenotype for heart failure.

Association of Nicotinamide Phosphoribosyltransferase (NAMPT) Gene Polymorphisms and of Serum NAMPT Levels with Dilated Cardiomyopathy in a Chinese Population

Nicotinamide phosphoribosyltransferase (NAMPT) has crucial roles for myocardial development, cardiomyocyte energy metabolism and cell death/survival by regulating NAD⁺-dependent sirtuin-1 (SIRT1) deacetylase. This study aimed to determine if the single nucleotide polymorphisms (SNPs) of the NAMPT gene may affect the susceptibility and prognosis for patients with dilated cardiomyopathy (DCM) and to describe the association of serum NAMPT levels with clinical features of DCM. Three SNPs (rs61330082, rs2505568, and rs9034) were analyzed by the polymerase chain reaction-restriction fragment length polymorphism method in a case-control study of 394 DCM patients and 395 controls from China. Serum NAMPT levels were measured by enzyme-linked immunosorbent assay kits. The homozygote for the minor allele at rs2505568 and rs9034 could not be detected in this study. Rs9034 T allele and CT genotype were associated with increased DCM risk (OR: 1.63, 95% CI = 1.16–2.27, p = 0.005 and OR: 1.72, 95% CI = 1.20–2.50, p = 0.0027, respectively). Nominally significant decreased DCM risk was found to be associated with the A allele and AT genotype of rs2505568 (OR: 0.48, 95% CI = 0.35–0.67, p < 0.0001 and OR: 0.44, 95% CI = 0.31–0.62, p < 0.0001, respectively), but it should be interpreted with caution because of Hardy-Weinberg disequilibrium in the control group. Of five haplotypes constructed, TAC (rs61330082-rs2505568-rs9034) was a protective haplotype to DCM (OR: 0.22, 95% CI = 0.13–0.39, p = 1.84 × 10⁻⁸). The Cox multivariate survival analysis indicated that the rs9034 CT genotype (hazard ratio (HR): 0.59, 95% CI = 0.37–0.96, p = 0.03) was an independently multivariate predictor for longer overall survival in DCM patients. Serum NAMPT levels were significantly higher in the DCM group than controls (p < 0.0001) and gradually increased with the increase of New York Heart Association grade in DCM patients. However, there was a lack of association of the three SNPs with serum NAMPT levels. Spearman correlation test revealed that the NAMPT level was positively associated with brain natriuretic peptide (r = 0.56, p = 0.001), left ventricular end-diastolic diameter (r = 0.293, p = 0.011) and left ventricular end-diastolic volume (r = 0.294, p = 0.011). Our study suggested that NAMPT may play an important role in the development of DCM.

Association of genetic polymorphisms on BTNL2 with susceptibility to and prognosis of dilated cardiomyopathy in a Chinese population

BACKGROUND

Dilated cardiomyopathy (DCM) is one type of primary myocardial disease, partly caused by immunity dysfunctions. BTNL2 (butyrophilin-like 2) has already been confirmed to be involved in the etiology of autoimmune disorders and GWAS (genome wide association study) has also identified mutants of a SNP (single nucleotide polymorphism) near BTNL2 could modulate risk of coronary heart disease (also cardiomyopathy). The current study, therefore, was aimed to investigate whether polymorphisms within or around BTNL2 would be correlated with susceptibility to and prognosis of DCM.

MATERIAL AND METHODS

Peripheral blood samples were gathered from 82 DCM patients and 75 healthy controls. Nine tag-SNPs within or near BTNL2 were obtained from HapMap Database and previously published studies. Eligible haplotypes were gained on the basis of SHesis software. Genotyping of SNPs was implemented with aid of Sequenom MassArray iPLEX platform and subsequently analyzed via MALDI-TOF mass spectrometry. The odd ratios and their 95% confidence interval (95% CI) were utilized to evaluate the correlations between SNPs/haplotypes and DCM risks. Finally, Cox proportional hazard models and Kaplan-Meier curves were performed to assess association of SNPs/haplotypes with prognosis of DCM patients. The statistical analyses were conducted with SPSS 19.0 software.

RESULTS

Under the allelic model, rs3763313 (A > C), rs9268494 (C > A), rs9268492 (C > G) and rs9268402 (A > G) were remarkably associated with susceptibility to grade IV of DCM classified by NYHA (New York heart association) (OR = 0.43, 95% CI: 0.22-0.84; P = 0.018; OR = 0.49, 95% CI: 0.27-0.91; P = 0.024; OR = 0.50, 95% CI: 0.27-0.94; P = 0.035; OR = 0.53, 95% CI: 0.28-0.97; P = 0.048). Haplotype C-C-A-T (rs9268492, rs9268494, rs3763313 and rs3763317 synthesized) was also regarded as a protective factor for DCM patients compared with carriers of other haplotypes (OR = 0.50, 95% CI: 0.26-0.97, P = 0.038). Moreover, the univariate survival analysis and multivariate Cox regression analysis both indicated noticeable correlations between rs9268402 and haplotype C-C-A-T and prognosis of DCM patients (NYHA IV), respectively (Long-Rank P = 0.029, HR: 0.241, 95% CI: 0.089-0.650, P = 0.005; Long-Rank P = 0.036; HR = 0.126, 95% CI: 0.035-0.457, P = 0.002). Nonetheless, rs3763313 was found only associated with prognosis of DCM patients (NYHA IV) expressed in the Kaplan-Meier curve (P = 0.009).

CONCLUSION

The genetic mutations within or around BTNL2 (rs3763313, rs9268494, rs9268492 and rs9268402) could alter susceptibility to grade IV of DCM in a Chinese population, and the 2 SNPs (rs3763313 and rs9268402) therein added with haplotype C-C-A-T might separately predict the prognosis of DCM patients. However, additional studies regarding diverse ethnicities need to be furthered to validate our results.

Reverse epidemiology in different stages of heart failure

BACKGROUND

In heart failure (HF), traditional cardiovascular risk factors (RF) as body mass index (BMI), total cholesterol (TC) and systolic blood pressure (SBP) are associated with better survival. It is unknown at which time point along the disease continuum the adverse impact of these RF ceases and may 'start to reverse'. We analyzed the distribution of RF and their association with survival across HF stages.

METHODS

We pooled data from four cohort studies from the German Competence Network HF. Employing ACC/AHA-criteria, patients were allocated to stage A (n=218), B (n=1324), C1 (i.e., New York Heart Association [NYHA] classes I & II; n=1134), and C2+D (NYHA III & IV; n=639).

RESULTS

With increasing HF severity median age increased (63/67/67/70 years), whereas the proportion of females (56/52/37/35%), median BMI (26.1/28.8/27.7/26.6 kg/m(2)), TC (212/204/191/172 mg/dl), and SBP (140/148/130/120 mmHg) decreased (P<0.001 for trend for all). In the total cohort, higher levels of all RF were associated with better survival, even after extensive adjustment for multiple confounders. If analyses were stratified, however, a higher RF burden predicted better survival only in clinically symptomatic patients: hazard ratio (HR) per +2 kg/m(2) BMI 0.91 (95% confidence interval 0.88; 0.95); per +10 mg/dl TC 0.93 (0.92; 0.95); per +5 mmHg SBP 0.94 (0.92; 0.95).

CONCLUSION

In this well-characterized sample of patients representing the entire HF continuum, reverse associations were only consistently observed in symptomatic HF stages. Our data indicate that the phenomenon of a "reverse epidemiology" in HF is subject to significant selection bias in less advanced disease.

Association of innate immune IFIH1 gene polymorphisms with dilated cardiomyopathy in a Chinese population

The interferon-induced helicase C domain-containing protein 1 (IFIH1) is a cytosolic RNA sensor belonging to the pattern-recognition receptor (PPR) family. Activation of PPRs on innate immune cells is widely believed to control the development of virus-induced autoimmunity in myocarditis and subsequent dilated cardiomyopathy (DCM). We conducted a pilot study to test whether single nucleotide polymorphisms (SNPs) in IFIH1 were associated with the risk and prognosis of DCM. The TaqMan SNP Genotyping Assay was used to genotype rs1990760 and rs3747517 in 351 DCM patients and 359 controls. The frequency of T allele and CT/TT genotypes at rs1990760 were significantly increased in DCM patients compared to control subjects (p = 0.046 and p = 0.027, respectively). The CC homozygosity was associated with worse prognosis expressed by the endpoint of cardiac death compared with allele T carriers of rs3747517 in both univariable (p = 0.04) and multivariable survival analysis after adjusting for age, sex, left ventricular end-diastolic diameter and ejection fraction (p = 0.01). The results revealed that rs1990760 was associated with susceptibility to DCM and rs3747517 played a role in the prognostic assessment of DCM, reflecting the distinct genetic contributions of innate IFIH1 polymorphisms in controlling the onset and outcome of DCM.