Incident Heart Failure Risk Reclassification With Race-Independent Estimated Glomerular Filtration Rate: A National Heart, Lung, and Blood Institute Pooled Cohorts Analysis.

BACKGROUND: This study compared the predictive value of the race-independent creatinine- and cystatin C-based estimated glomerular filtration rate (eGFRcr-cys) and the race-dependent creatinine-based eGFR (eGFRcr) for incident heart failure (HF). METHODS: This study combined the participant-level data from ARIC (Atherosclerosis Risk in Communities) (visit 4) and MESA (Multi-Ethnic Study of Atherosclerosis) (visit 1) to calculate eGFRcr-cys and eGFRcr. The primary outcome of the study was adjudicated incident HF over a follow-up period of 10 years. Multivariable Cox models were used to assess the risk of incident HF with the quartiles of eGFRcr-cys and eGFRcr. RESULTS: Among 15,615 individuals (median age: 62 [57-68] years; 55.0% females; 23.9% Black), the median eGFRcr-cys and eGFRcr were 91.4 (79.4, 102.0) mL/min/1.73m2 and 84.7 (72.0, 94.7) mL/min/1.73m2, respectively. Compared with the fourth quartile of eGFRcr-cys, the hazard ratio for incident HF was 1.02 (95% CI:0.80-1.30) in the third quartile, 1.02 (95% CI:0.80-1.30) in the second quartile, and 1.47 (95% CI:1.16-1.86) in the first quartile. Compared with the 4th quartile of the eGFRcr, the risk of incident HF was similar in the 3rd (HRadj:0.90 [95% CI:0.73-1.12]), 2nd (HRadj: 0.96 [95% CI:0.77-1.20]), and 1st (HRadj:1.15 [95% CI:0.93-1.44]) quartiles. C-statistics were similar for the multivariable-adjusted Cox models for incident HF using eGFRcr (0.80 [0.79-0.81]) and eGFRcr-cys (0.80 [0.79-0.82]). CONCLUSION: The eGFRcr and eGFRcr-cys had comparable predictive values for incident HF.

Ponatinib Drives Cardiotoxicity by S100A8/A9-NLRP3-IL-1ß Mediated Inflammation.

BACKGROUND: The tyrosine kinase inhibitor ponatinib is the only treatment option for chronic myelogenous leukemia patients with T315I (gatekeeper) mutation. Pharmacovigilance analysis of Food and Drug Administration and World Health Organization datasets has revealed that ponatinib is the most cardiotoxic agent among all Food and Drug Administration-approved tyrosine kinase inhibitors in a real-world scenario. However, the mechanism of ponatinib-induced cardiotoxicity is unknown. METHODS: The lack of well-optimized mouse models has hampered the in vivo cardio-oncology studies. Here, we show that cardiovascular comorbidity mouse models evidence a robust cardiac pathological phenotype upon ponatinib treatment. A combination of multiple in vitro and in vivo models was employed to delineate the underlying molecular mechanisms. RESULTS: An unbiased RNA sequencing analysis identified the enrichment of dysregulated inflammatory genes, including a multifold upregulation of alarmins S100A8/A9, as a top hit in ponatinib-treated hearts. Mechanistically, we demonstrate that ponatinib activates the S100A8/A9-TLR4 (Toll-like receptor 4)-NLRP3 (NLR family pyrin domain-containing 3)-IL (interleukin)-1ß signaling pathway in cardiac and systemic myeloid cells, in vitro and in vivo, thereby leading to excessive myocardial and systemic inflammation. Excessive inflammation was central to the cardiac pathology because interventions with broad-spectrum immunosuppressive glucocorticoid dexamethasone or specific inhibitors of NLRP3 (CY-09) or S100A9 (paquinimod) nearly abolished the ponatinib-induced cardiac dysfunction. CONCLUSIONS: Taken together, these findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. From a translational perspective, our results provide critical preclinical data and rationale for a clinical investigation into immunosuppressive interventions for managing ponatinib-induced cardiotoxicity.

TNFR1 Contributes to Activation-Induced Cell Death of Pathological CD4+ T Lymphocytes During Ischemic Heart Failure.

CD4+ T cells turn pathological during heart failure (HF). We show that the expression of tumor necrosis factor (TNF)-α and tumor necrosis factor receptor (TNFR1) increases in HF-activated CD4+ T cells. However, the role of the TNF-α/TNFR1 axis in T-cell activation/proliferation is unknown. We show that TNFR1 neutralization during T-cell activation (ex vivo) or the loss of TNFR1 in adoptively transferred HF-activated CD4+ T cells (in vivo) augments their prosurvival and proliferative signaling. Importantly, TNFR1 neutralization does not affect CD69 expression or the pathological activity of HF-activated TNFR1-/- CD4+ T cells. These results show that during HF TNFR1 plays an important role in quelling prosurvival and proliferative signals in CD4+ T cells without altering their pathological activity.

Coronary flow abnormalities in chronic kidney disease: A systematic review and meta-analysis.

BACKGROUND: Coronary vasomotion abnormalities have been described in small studies but not studied systematically. We aimed to review the present literature and analyze it to improve our understanding of chronic kidney disease (CKD) related-coronary microvascular dysfunction. OBJECTIVE: Coronary flow reserve (CFR) is a well-known measure of coronary vasomotion. We aimed to assess the difference in CFR among participants with and without CKD. METHODS: PubMed, Embase, and Cochrane CENTRAL were systematically reviewed to identify studies that compared CFR in participants with and without CKD. We estimated standardized mean differences in mean CFR reported in these studies. We performed subgroup analyses according to imaging modality, and the presence of significant epicardial coronary artery disease. RESULTS: In 14 observational studies with 5966 and 1410 patients with and without CKD, the mean estimated glomerular filtration rate (eGFR) was 29 ± 04 and 87 ± 25 ml/min/1.73 m2 , respectively. Mean CFR was consistently lower in patients with CKD in all studies and the cumulative mean difference was statistically significant (2.1 ± .3 vs. 2.7 ± .5, standardized mean difference -.8, 95% CI -1.1, -.6, p < .05). The lower mean CFR was driven by both significantly higher mean resting flow velocity (.58 cm/s, 95% CI .17, .98) and lower mean stress flow velocity (-.94 cm/s, 95% CI -1.75, -.13) in studies with CKD. This difference remained significant across diagnostic modalities and even in absence of epicardial coronary artery disease. In meta-regression, there was a significant positive relationship between mean eGFR and mean CFR (p < .05). CONCLUSION: Patients with CKD have a significantly lower CFR versus those without CKD, even in absence of epicardial coronary artery disease. There is a linear association between eGFR and CFR. Future studies are required to understand the mechanisms and therapeutic implications of these findings. KEY POINTS: In this meta-analysis of observational studies, there was a significant reduction in coronary flow reserve in studies with chronic kidney disease versus those without. This difference was seen even in absence of epicardial coronary artery disease. In meta-regression, a lower estimate glomerular filtration rate was a significant predictor of lower coronary flow reserve. Coronary microvascular dysfunction, rather than atherosclerosis-related epicardial disease may underly increase cardiovascular risk in a patient with chronic kidney disease.

Activation of Autophagic Flux Maintains Mitochondrial Homeostasis during Cardiac Ischemia/Reperfusion Injury.

Reperfusion injury after extended ischemia accounts for approximately 50% of myocardial infarct size, and there is no standard therapy. HDAC inhibition reduces infarct size and enhances cardiomyocyte autophagy and PGC1α-mediated mitochondrial biogenesis when administered at the time of reperfusion. Furthermore, a specific autophagy-inducing peptide, Tat-Beclin 1 (TB), reduces infarct size when administered at the time of reperfusion. However, since SAHA affects multiple pathways in addition to inducing autophagy, whether autophagic flux induced by TB maintains mitochondrial homeostasis during ischemia/reperfusion (I/R) injury is unknown. We tested whether the augmentation of autophagic flux by TB has cardioprotection by preserving mitochondrial homeostasis both in vitro and in vivo. Wild-type mice were randomized into two groups: Tat-Scrambled (TS) peptide as the control and TB as the experimental group. Mice were subjected to I/R surgery (45 min coronary ligation, 24 h reperfusion). Autophagic flux, mitochondrial DNA (mtDNA), mitochondrial morphology, and mitochondrial dynamic genes were assayed. Cultured neonatal rat ventricular myocytes (NRVMs) were treated with a simulated I/R injury to verify cardiomyocyte specificity. The essential autophagy gene, ATG7, conditional cardiomyocyte-specific knockout (ATG7 cKO) mice, and isolated adult mouse ventricular myocytes (AMVMs) were used to evaluate the dependency of autophagy in adult cardiomyocytes. In NRVMs subjected to I/R, TB increased autophagic flux, mtDNA content, mitochondrial function, reduced reactive oxygen species (ROS), and mtDNA damage. Similarly, in the infarct border zone of the mouse heart, TB induced autophagy, increased mitochondrial size and mtDNA content, and promoted the expression of PGC1α and mitochondrial dynamic genes. Conversely, loss of ATG7 in AMVMs and in the myocardium of ATG7 cKO mice abolished the beneficial effects of TB on mitochondrial homeostasis. Thus, autophagic flux is a sufficient and essential process to mitigate myocardial reperfusion injury by maintaining mitochondrial homeostasis and partly by inducing PGC1α-mediated mitochondrial biogenesis.

Healing and repair after myocardial infarction: the forgotten but resurgent basophil.

The biphasic wound-healing response in the heart after myocardial infarction involves an initial inflammatory phase followed by a more prolonged period of inflammation resolution, tissue repair, and scar formation. Infiltrating proinflammatory Ly6Chi monocytes and monocyte-derived macrophages are key drivers of the inflammatory phase and are also the source of the locally generated reparative macrophages that promote inflammation resolution. In this issue of the JCI, Sicklinger et al. from the Leuschner laboratory uncover a salutary role for cardiac basophils in this process. The authors demonstrated that basophils promote healing and proper scar formation and also limit late cardiac remodeling by augmenting reparative macrophages in the infarcted heart, in part via basophil-derived enhancement of cardiac IL-4 and IL-13 levels. These findings underscore the potentially disproportionate (relative to cell numbers) yet essential biological effects of immune cells of low abundance on cardiac repair and remodeling, related in part to amplification of downstream macrophage responses via secreted cytokines.

The Apolipoprotein A-I Mimetic L-4F Attenuates Monocyte Activation and Adverse Cardiac Remodeling after Myocardial Infarction.

Excessive inflammation after myocardial infarction (MI) can promote infarct expansion and adverse left ventricular (LV) remodeling. L-4F, a mimetic peptide of apolipoprotein A-I (apoA-I), exhibits anti-inflammatory and anti-atherogenic properties; however, whether L-4F imparts beneficial effects after myocardial infarction (MI) is unknown. Here we demonstrate that L-4F suppresses the expansion of blood, splenic, and myocardial pro-inflammatory monocytes and macrophages in a mouse model of reperfused MI. Changes in immune cell profiles were accompanied by alleviation of post-MI LV remodeling and dysfunction. In vitro, L-4F also inhibited pro-inflammatory and glycolytic gene expression in macrophages. In summary, L-4F treatment prevents prolonged and excessive inflammation after MI, in part through modulation of pro-inflammatory monocytes and macrophages, and improves post-MI LV remodeling. These data suggest that L-4F could be a used as a therapeutic adjunct in humans with MI to limit inflammation and alleviate the progression to heart failure.

Clinical, Demographic, and Imaging Correlates of Anemia in Heart Failure With Preserved Ejection Fraction (from the RELAX Trial).

Anemia is a commonly occurring comorbidity among patients of heart failure with preserved ejection fraction (HFpEF) but limited data exists on the cardiovascular phenotype of anemia in HFpEF. We sought to characterize the clinical features, exercise capacity, and outcomes in patients with HFpEF to elucidate the phenotype and pathophysiology of anemia in HFpEF. Post hoc analyses of participants enrolled in the RELAX (Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure) trial was performed. Anemia was defined as hemoglobin <13 g/dL in men and <12 g/dL in women. Multivariate adjusted regression modeling was done to assess for differences in peak oxygen uptake. Adjusted hazard ratios were generated to assess difference in hospitalization events using a Cox proportional hazards model. Anemic HFpEF patients were more likely to be older, male, and have worse renal function (p <0.05 for all). N-terminal pro-B-type natriuretic peptide, troponin I, pro-collagen III N-terminal peptide, C-telopeptide for type I collagen, uric acid, cystatin-c, and galectin-3 (p <0.05 for all) levels were higher in anemic HFpEF patients. In adjusted models, anemic HFpEF patients had worse exercise capacity (peak oxygen uptake: 11.3 vs 12.1 mL/kg/min; p = 0.004). The hazard for cardiac or renal cause of hospitalization in those with anemia was 2.0 (95% confidence interval: 0.9 to 4.3). Anemic HFpEF patients have worse exercise capacity and are more likely to be hospitalized. A better understanding of the physiologic phenotypes of HFpEF patients may allow for greater personalization of treatment and prognostication in HFpEF patients.

Anemia, Mortality, and Hospitalizations in Heart Failure With a Preserved Ejection Fraction (from the TOPCAT Trial).

In this post-hoc analysis of the TOPCAT trial, we evaluated the prognostic role of anemia in adverse cardiovascular (CV) outcomes in heart failure with a preserved ejection fraction (HFpEF). Anemia was defined as hemoglobin of <12 g/dl in females and <13 g/dl in males. The primary outcome was a composite of CV mortality, aborted cardiac arrest (ACA), and heart failure (HF) hospitalization. Secondary outcomes were components of the primary outcome, all-cause, CV and non-CV mortality, cause-specific CV and non-CV mortality, all-cause and HF hospitalization, myocardial infarction, and stroke. Among 1,748 patients from TOPCAT-Americas, patients with anemia had a 52% higher risk of the primary outcome (hazard ratio [HR] 1.52, 95% confidence interval 1.27, 1.83, p<0.05) during a median follow up of 2.4 years. These patients were also at higher risk of all-cause and CV mortality with no difference in non-CV mortality. Among CV causes, patients with anemia had higher risk of sudden cardiac death (SCD)/ACA and presumed CV death with no difference in death due to pump failure. Among non-CV causes, patients with anemia had higher risk of death due to malignancy (HR 2.61, p<0.05). Patients with anemia had higher risk of all-cause and HF hospitalizations (HR 1.26 and 1.56, respectively, p<0.05 for both). There was no difference in the risk of myocardial infarction or stroke. In conclusion, patients with HFpEF and anemia are at higher risk of mortality and hospitalization. Anemia is a significant risk factor for SCD/ACA, death due to presumed CV causes and malignancy in HFpEF.

Risk of Major Adverse Cardiovascular Events and Major Hemorrhage Among White and Black Patients Undergoing Percutaneous Coronary Intervention.

Background Data on racial disparities in major adverse cardiovascular events (MACE) and major hemorrhage (HEM) after percutaneous coronary intervention are limited. Factors contributing to these disparities are unknown. Methods and Results PRiME-GGAT (Pharmacogenomic Resource to Improve Medication Effectiveness-Genotype-Guided Antiplatelet Therapy) is a prospective cohort. Patients aged ≥18 years undergoing percutaneous coronary intervention were enrolled and followed for up to 1 year. Racial disparities in risk of MACE and HEM were assessed using an incident rate ratio. Sequential cumulative adjustment analyses were performed to identify factors contributing to these disparities. Data from 919 patients were included in the analysis. Compared with white patients, black patients (n=203; 22.1% of the cohort) were younger and were more likely to be female, to be a smoker, and to have higher body mass index, lower socioeconomic status, higher prevalence of diabetes mellitus and moderate to severe chronic kidney disease, and presentation with acute coronary syndrome and to undergo urgent percutaneous coronary intervention. The incident rates of MACE (34.1% versus 18.2% per 100 person-years, P<0.001) and HEM (17.7% versus 10.3% per 100 person-years, P=0.02) were higher in black patients. The incident rate ratio was 1.9 (95% CI, 1.3-2.6; P<0.001) for MACE and 1.7 (95% CI, 1.1-2. 7; P=0.02) for HEM. After adjustment for nonclinical and clinical factors, black race was not significantly associated with outcomes. Rather, differences in socioeconomic status, comorbidities, and coronary heart disease severity were attributed to racial disparities in outcomes. Conclusions Despite receiving similar treatment, racial disparities in MACE and HEM still exist. Opportunities exist to narrow these disparities by mitigating the identified contributors.

Effects of Crushed Ticagrelor Versus Eptifibatide Bolus Plus Clopidogrel in Troponin-Negative Acute Coronary Syndrome Patients Undergoing Percutaneous Coronary Intervention: A Randomized Clinical Trial.

Background After a loading dose of ticagrelor, the rate of high on-treatment platelet reactivity remains elevated, which increases periprocedural myocardial infarction and injury. This indicates that faster platelet inhibition with crushed ticagrelor (CTIC) or eptifibatide is needed to reduce high on-treatment platelet reactivity. The efficacy of CTIC versus eptifibatide bolus plus clopidogrel is unknown. Methods and Results A total of 100 P2Y12 naïve, troponin-negative patients with acute coronary syndrome were randomized to CTIC (180 mg) versus eptifibatide bolus (180 µg/kg×2 intravenous boluses) plus clopidogrel (600 mg) at the time of percutaneous coronary intervention. High on-treatment platelet reactivity was markedly higher with CTIC versus eptifibatide bolus plus clopidogrel (42% versus 0%; P<0.001) at 30 minutes and persisted up to 2 hours (12% versus 0%; P=0.01, respectively). Platelet aggregation by adenosine diphosphate dropped faster from baseline with eptifibatide bolus plus clopidogrel versus CTIC (0.5 versus 2 hours, respectively) and was higher with CTIC versus eptifibatide bolus plus clopidogrel at 0.5, 2, and 4 hours after loading dose (53±12% versus 1.3±2%; 35±11% versus 0.34±1.0%; and 23±9% versus 3.5±2%, respectively; P<0.001). Eptifibatide bolus plus clopidogrel, but not CTIC, significantly inhibited platelet aggregation induced by thrombin-receptor activating peptide. Periprocedural myocardial infarction and injury was higher with CTIC versus eptifibatide bolus plus clopidogrel (48% versus 28%, respectively; P=0.035). Post-percutaneous coronary intervention hemoglobin levels were not different between groups. Conclusions Eptifibatide bolus plus clopidogrel led to faster and more potent platelet inhibition than CTIC and reduced periprocedural myocardial infarction and injury in troponin-negative acute coronary syndrome patients undergoing percutaneous coronary intervention, with no significant hemoglobin drop after percutaneous coronary intervention. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT02925923.

Circulating myocardial microRNAs from infarcted hearts are carried in exosomes and mobilise bone marrow progenitor cells.

Myocardial microRNAs (myo-miRs) are released into the circulation after acute myocardial infarction (AMI). How they impact remote organs is however largely unknown. Here we show that circulating myo-miRs are carried in exosomes and mediate functional crosstalk between the ischemic heart and the bone marrow (BM). In mice, we find that AMI is accompanied by an increase in circulating levels of myo-miRs, with miR-1, 208, and 499 predominantly in circulating exosomes and miR-133 in the non-exosomal component. Myo-miRs are imported selectively to peripheral organs and preferentially to the BM. Exosomes mediate the transfer of myo-miRs to BM mononuclear cells (MNCs), where myo-miRs downregulate CXCR4 expression. Injection of exosomes isolated from AMI mice into wild-type mice downregulates CXCR4 expression in BM-MNCs and increases the number of circulating progenitor cells. Thus, we propose that myo-miRs carried in circulating exosomes allow a systemic response to cardiac injury that may be leveraged for cardiac repair.

HDAC inhibition induces autophagy and mitochondrial biogenesis to maintain mitochondrial homeostasis during cardiac ischemia/reperfusion injury.

AIMS: The FDA-approved histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA, Vorinostat) has been shown to induce cardiomyocyte autophagy and blunt ischemia/reperfusion (I/R) injury when administered at the time of reperfusion. However, the precise mechanisms underlying the cardioprotective activity of SAHA are unknown. Mitochondrial dysfunction and oxidative damage are major contributors to myocardial apoptosis during I/R injury. We hypothesize that SAHA protects the myocardium by maintaining mitochondrial homeostasis and reducing reactive oxygen species (ROS) production during I/R injury. METHODS: Mouse and cultured cardiomyocytes (neonatal rat ventricular myocytes and human embryonic stem cell-derived cardiomyocytes) I/R models were used to investigate the effects of SAHA on mitochondria. ATG7 knockout mice, ATG7 knockdown by siRNA and PGC-1α knockdown by adenovirus in cardiomyocytes were used to test the dependency of autophagy and PGC-1α-mediated mitochondrial biogenesis respectively. RESULTS: Intact and total mitochondrial DNA (mtDNA) content and mitochondrial mass were significantly increased in cardiomyocytes by SAHA pretreatment before simulated I/R. In vivo, I/R induced >50% loss of mtDNA content in the border zones of mouse hearts, but SAHA pretreatment and reperfusion treatment alone reverted mtDNA content and mitochondrial mass to control levels. Moreover, pretreatment of cardiomyocytes with SAHA resulted in a 4-fold decrease in I/R-induced loss of mitochondrial membrane potential and a 25%-40% reduction in cytosolic ROS levels. However, loss-of-function of ATG7 in cardiomyocytes or mouse myocardium abolished the protective effects of SAHA on ROS levels, mitochondrial membrane potential, mtDNA levels, and mitochondrial mass. Lastly, PGC-1α gene expression was induced by SAHA in NRVMs and mouse heart subjected to I/R, and loss of PGC-1α abrogated SAHA's mitochondrial protective effects in cardiomyocytes. CONCLUSIONS: SAHA prevents I/R induced-mitochondrial dysfunction and loss, and reduces myocardial ROS production when given before or after the ischemia. The protective effects of SAHA on mitochondria are dependent on autophagy and PGC-1α-mediated mitochondrial biogenesis.

Dysfunctional and Proinflammatory Regulatory T-Lymphocytes Are Essential for Adverse Cardiac Remodeling in Ischemic Cardiomyopathy.

BACKGROUND: Heart failure (HF) is a state of inappropriately sustained inflammation, suggesting the loss of normal immunosuppressive mechanisms. Regulatory T-lymphocytes (Tregs) are considered key suppressors of immune responses; however, their role in HF is unknown. We hypothesized that Tregs are dysfunctional in ischemic cardiomyopathy and HF, and they promote immune activation and left ventricular (LV) remodeling. METHODS: Adult male wild-type C57BL/6 mice, Foxp3-diphtheria toxin receptor transgenic mice, and tumor necrosis factor (TNF) α receptor-1 (TNFR1)-/- mice underwent nonreperfused myocardial infarction to induce HF or sham operation. LV remodeling was assessed by echocardiography as well as histological and molecular phenotyping. Alterations in Treg profile and function were examined by flow cytometry, immunostaining, and in vitro cell assays. RESULTS: Compared with wild-type sham mice, CD4+Foxp3+ Tregs in wild-type HF mice robustly expanded in the heart, circulation, spleen, and lymph nodes in a phasic manner after myocardial infarction, beyond the early phase of wound healing, and exhibited proinflammatory T helper 1-type features with interferon-γ, TNFα, and TNFR1 expression, loss of immunomodulatory capacity, heightened proliferation, and potentiated antiangiogenic and profibrotic properties. Selective Treg ablation in Foxp3-diphtheria toxin receptor mice with ischemic cardiomyopathy reversed LV remodeling and dysfunction, alleviating hypertrophy and fibrosis, while suppressing circulating CD4+ T cells and systemic inflammation and enhancing tissue neovascularization. Tregs reconstituted after ablation exhibited restoration of immunosuppressive capacity and normalized TNFR1 expression. Treg dysfunction was also tightly coupled to Treg-endothelial cell contact- and TNFR1-dependent inhibition of angiogenesis and the mobilization and tissue infiltration of CD34+Flk1+ circulating angiogenic cells in a C-C chemokine ligand 5/C-C chemokine receptor 5-dependent manner. Anti-CD25-mediated Treg depletion in wild-type mice imparted similar benefits on LV remodeling, circulating angiogenic cells, and tissue neovascularization. CONCLUSIONS: Proinflammatory and antiangiogenic Tregs play an essential pathogenetic role in chronic ischemic HF to promote immune activation and pathological LV remodeling. The restoration of normal Treg function may be a viable approach to therapeutic immunomodulation in this disease.

THE CARDIOSPLENIC AXIS IS ESSENTIAL FOR THE PATHOGENESIS OF ISCHEMIC HEART FAILURE.

The role of innate and adaptive immunity in heart failure (HF) is poorly understood. We discovered that mice with ischemic HF exhibit robust expansion of proinflammatory monocytes/macrophages, classical and plasmacytoid dendritic cells, and CD4+ and CD8+ T cells. There was profound splenic remodeling indicative of heightened antigen processing, and expanded antigen-experienced effector and memory CD4+ T cell populations. A series of subsequent studies in HF mice that incorporated splenectomy, adoptive transfer of both unselected splenocytes and splenic CD4+ T-cells, and antibody-mediated CD4+ T-cell depletion indicated that intensely activated splenic immune cells: 1) underlie the chronic inflammatory response in HF, 2) traffic and home to the failing heart, and 3) exhibit immune memory and are primed to induce tissue injury that promotes pathological cardiac remodeling. Hence, we propose that ischemic cardiomyopathy is in part an immune-mediated disease, against as-of-yet unidentified cardiac antigens, with a central role for the spleen in this process.

CCR2+ Monocyte-Derived Infiltrating Macrophages Are Required for Adverse Cardiac Remodeling During Pressure Overload.

Although chronic inflammation is a central feature of heart failure (HF), the immune cell profiles differ with different underlying causes. This suggests that for immunomodulatory therapy in HF to be successful, it needs to be tailored to the specific etiology. Here, the authors demonstrate that monocyte-derived C-C chemokine receptor 2 (CCR2)+ macrophages infiltrate the heart early during pressure overload in mice, and that blocking this response either pharmacologically or with antibody-mediated CCR2+ monocyte depletion alleviates late pathological left ventricular remodeling and dysfunction, T-cell expansion, and cardiac fibrosis. Hence, suppression of CCR2+ monocytes/macrophages may be an important immunomodulatory therapeutic target to ameliorate pressure-overload HF.

Genetic deletion of 12/15 lipoxygenase promotes effective resolution of inflammation following myocardial infarction.

12/15 lipoxygenase (LOX) directs inflammation and lipid remodeling. However, the role of 12/15LOX in post-myocardial infarction (MI) left ventricular remodeling is unclear. To determine the role of 12/15LOX, 8-12 week-old C57BL/6 J wild-type (WT; n = 93) and 12/15LOX-/- (n = 97) mice were subjected to permanent coronary artery ligation and monitored at day (d)1 and d5 post-operatively. Post-MI d28 survival was measured in male and female mice. No-MI surgery mice were maintained as d0 naïve controls. 12/15LOX-/- mice exhibited higher survival rates with lower cardiac rupture and improved LV function as compared with WT post-MI. Compared to WT, neutrophils and macrophages in 12/15LOX-/- mice were polarized towards N2 and M2 phenotypes, respectively, with increased of expression mrc-1, ym-1, and arg-1 post-MI. 12/15LOX-/- mice exhibited lower levels of pro-inflammatory 12-(S)-hydroperoxyeicosatetraenoic acid (12(S)-HETE) and higher CYP2J-derived epoxyeicosatrienoic acids (EETs) levels. CYP2J-derived 5,6-, 8,9-, 11,12-, and 14,15-EETs activated macrophage-specific hemeoxygenase (HO)-1 marked with increases in F4/80+/Ly6Clow and F4/80+/CD206high cells at d5 post-MI in 12/15LOX-/- mice. In contrast, inhibition of HO-1 led to total mortality in 12/15LOX-/- mice by post-MI d5. 12/15LOX-/- mice exhibited reduced collagen density and lower α-smooth muscle actin (SMA) expression at d5 post-MI, indicating delayed or limited fibroblast-to-myofibroblast differentiation. In conclusion, genetic deletion of 12/15LOX reduces 12(S)-HETE and activates CYP2J-derived EETs to promote effective resolution of inflammation post-MI leading to reduced cardiac rupture, improved LV function, and better survival.

The stress kinase JNK regulates gap junction Cx43 gene expression and promotes atrial fibrillation in the aged heart.

BACKGROUND: The stress kinase c-jun N-terminal kinase (JNK) is critical in the pathogenesis of cardiac diseases associated with an increased incidence of atrial fibrillation (AF), the most common arrhythmia in the elderly. We recently discovered that JNK activation is linked to the loss of gap junction connexin43 (Cx43) and enhanced atrial arrhythmogenicity. However, direct evidence for JNK-mediated impairment of intercellular coupling (cell-cell communication) in the intact aged atrium is lacking, as is evidence for whether and how JNK suppresses Cx43 in the aged human atrium. METHODS AND RESULTS: JNK activity in human atrial samples is correlated with both reduced Cx43 expression and increasing age. Using a unique technique of optical mapping space constant measurement, we found that impaired intercellular coupling and reduced Cx43 were linked to enhanced activation of JNK in intact aged rabbit atria. These JNK-associated alterations were further confirmed in naturally JNK activated aged mice and in cardiac-specific inducible MKK7D (JNK upstream activator) young mice. Moreover, JNK inhibition, using either JNK specific inhibitors in aged wild-type (WT) mice and JNK activator anisomycin-treated young WT mice or JNK1/2 dominant-negative mice with genetically inhibited cardiac JNK activity, completely eliminated these functional abnormalities. Furthermore, we discovered for the first time that long-term JNK activation downregulates Cx43 expression via c-jun suppressed transcriptional activity of the Cx43 gene promoter. CONCLUSION: Our results demonstrate that JNK is a critical regulator of Cx43 expression, and that augmented JNK activation in aged atria downregulates Cx43 to impair cell-cell communication and promote the development of AF. JNK inhibition may represent a promising therapeutic approach to prevent or treat AF in the elderly.

Resolution Agonist 15-epi-Lipoxin A4 Programs Early Activation of Resolving Phase in Post-Myocardial Infarction Healing.

Following myocardial infarction (MI), overactive inflammation remodels the left ventricle (LV) leading to heart failure coinciding with reduced levels of 15-epi-Lipoxin A4 (15-epi LXA4). However, the role of 15-epi LXA4 in post-MI acute inflammatory response and resolving phase is unclear. We hypothesize that liposomal fusion of 15-epi-LXA4 (Lipo-15-epi-LXA4) or free 15-epi-LXA4 will expedite the resolving phase in post-MI inflammation. 8 to 12-week-old male C57BL/6 mice were subjected to permanent coronary artery ligation. Lipo-15-epi-LXA4 or 15-epi-LXA4 (1 µg/kg/day) was injected 3 hours post-MI for (d)1 or continued daily till d5. 15-epi-LXA4 activated formyl peptide receptor (FPR2) and GPR120 on alternative macrophages but inhibited GPR40 on classical macrophages in-vitro. The 15-epi-LXA4 injected mice displayed reduced LV and lung mass to body weight ratios and improved ejection fraction at d5 post-MI. In the acute phase of inflammation-(d1), 15-epi-LXA4 primes neutrophil infiltration with a robust increase of Ccl2 and FPR2 expression. During the resolving phase-(d5), 15-epi-LXA4 initiated rapid neutrophils clearance with persistent activation of FPR2 in LV. Compared to MI-control, 15-epi-LXA4 injected mice showed reduced renal inflammation along with decreased levels of ngal and plasma creatinine. In summary, 15-epi-LXA4 initiates the resolving phase early to discontinue inflammation post-MI, thereby reducing LV dysfunction.