Basic Research in Cardiology最新文献

Ventricular fibrillation (VF)-induced cardiac arrest frequently complicates ST-segment elevation myocardial infarction (STEMI). Although larger infarct sizes (IS) correlate with a higher risk of VF, the influence of VF itself on IS has remained poorly investigated. To address this knowledge gap, we analyzed the effect of VF on IS in patients and two experimental models. From a prospective cohort, 30 STEMI patients with VF were matched 1:2 with STEMI patients without VF on the common determinants of IS. The primary endpoint was IS, assessed using the 48-h area under the curve (AUC) for troponin. We also compared IS in pigs with/without spontaneous VF during STEMI (n = 15/group), and in an isolated rat heart model of myocardial infarction with/without electrically induced VF (n = 7/group). After matching, the patient characteristics, including the area at risk (AR), were similar. IS was 33% lower in the VF group compared to the control group (troponin AUC 1.6 [0.5–3.3] 10⁶ arbitrary units vs. 2.4 [0.9–4.1] 10⁶ arbitrary units; p < 0.05), but infarct scar size (assessed using MRI and ECG) did not differ between the groups at 1 and 6 months. In both experimental models, IS, expressed as a percentage of AR, was lower (p < 0.05) in the VF group than in the control group. When common determinants of IS are comparable, VF occurring prior to myocardial infarction reperfusion appears to be associated with smaller IS. Nevertheless, this finding, observed under specific experimental conditions and in a highly selected group of patients, was not associated with reduced infarct scar size.

Registration (HIBISCUS-STEMI cohort): ClinicalTrials.gov NCT05794022.

Immune checkpoint inhibitor (ICI)-associated myocarditis is a rare but potentially fatal immune-related adverse event. Previously, we reported a case of ICI-associated myocarditis with elevated autoantibodies to 4E-binding protein 3 (4E-BP3). Recent studies have suggested that 4E-BP3 may play an important role in tumor development. However, its role in cardiac diseases including myocarditis is unknown. We investigated the role of 4E-BP3 in an autoimmune myocarditis mouse model. Myocarditis was induced in wild-type and 4E-BP3 knockout mice by immunization with murine α-myosin peptide. 4E-BP3 gene expression was upregulated in the heart of myocarditis mouse. We found that genetic deletion of 4E-BP3 attenuated myocardial inflammation, reduced fibrosis area, and improved cardiac function in myocarditis mice. Studies in bone marrow-chimeric mice demonstrated that immune cell-derived 4E-BP3 plays a pivotal role in the pathogenesis of myocarditis. Immune cell transfer experiments revealed that 4E-BP3 deficiency in dendritic cells and CD4⁺ T cells decreased disease severity in recipient mice. Furthermore, dendritic cells that were deficient in 4E-BP3 exhibited a diminished capacity to produce IL-6 and IL-1β. Naive CD4⁺ T cells lacking 4E-BP3 had a reduced ability to differentiate into T-helper (Th)1 and Th17 cells. These findings suggest that 4E-BP3 in dendritic cells and CD4⁺ T cells may be critically involved in the pathogenesis of α-myosin-specific T cell-mediated myocarditis. Thus, 4E-BP3 could be a possible therapeutic target for myocarditis.

Despite accumulating data on underlying mechanisms, the influence of sex and prevalent cardio-metabolic co-morbidities on the manifestation and severity of immune checkpoint inhibitor (ICI)-induced cardiotoxicity has not been well defined. To elucidate whether sex and prevalent cardio-metabolic co-morbidities affect ICI-induced cardiotoxicity, we randomized 17-month-old male and female mice to receive control diet (CON) or high-fat diet (HFD) + L-NAME—a well-established mouse model of cardio-metabolic co-morbidities—for 17 weeks (n = 5–7), and evaluated markers of T-cell function in the spleen. As expected, HFD + L-NAME significantly increased body- and heart weight, and serum cholesterol levels, and caused no systolic dysfunction, however, led to diastolic dysfunction, cardiomyocyte hypertrophy, and increased fibrosis only in males compared to corresponding CON. Western blot analyses of splenic immune checkpoint protein levels showed differential expression depending on sex and prevalent cardio-metabolic co-morbidities, suggesting T-cell exhaustion in both sexes on HFD + L-NAME, but more pronounced in males. In a sub-study with a similar setup, we tested cardiotoxic manifestations of ICI by treating mice with anti-PD-1 monoclonal antibody (ICI) for the last 2 weeks of diet administration (n = 5–7). After 2 weeks of ICI treatment, cardiac systolic functions significantly decreased in CON, but not in HFD + L-NAME groups of both sexes compared to baseline (before ICI administration). In conclusion, in this exploratory study using aged mice, we describe for the first time that ICI-related systolic dysfunction is diminished in both sexes when obesity and hypercholesterolemia are present, possibly due to obesity-related T-cell exhaustion.

The heterogeneity of endothelial cells (ECs) across human tissues remains incompletely inventoried. We constructed an atlas of > 210,000 ECs derived from 38 regions across 24 human tissues. Our analysis reveals significant differences in transcriptome, phenotype, metabolism and transcriptional regulation among ECs from various tissues. Notably, arterial, venous, and lymphatic ECs shared more common markers in multiple tissues than capillary ECs, which exhibited higher heterogeneity. This diversity in capillary ECs suggests their greater potential as targets for drug development. ECs from different tissues and vascular beds were found to be associated with specific diseases. Importantly, tissue specificity of EC senescence is more determined by somatic site than by tissue type (e.g. subcutaneus adipose tissue and visceral adipose tissue). Additionally, sex-specific differences in brain EC senescence were observed. Our EC atlas offers valuble resoursce for identifying EC subclusters in single-cell datasets from body tissues or organoids, facilitating the screen of tissue-specific targeted therapies, and serving as a powerful tool for future discoveries.

Myocardial ischemia–reperfusion (IR) injury is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD). The most frequently used and representative experimental model is the rat dietary adenine-induced CKD, which leads to CKD-associated CVD. However, the continued intake of adenine is a potential confounding factor. This study investigated cardiovascular dysfunction following brief adenine exposure, CKD development and return to a normal diet. Male Wistar rats received a 0.3% adenine diet for 10 weeks and normal chow for an additional 8 weeks. Kidney function was assessed by urinalysis and histology. Heart function was assessed by echocardiography. Sensitivity to myocardial IR injury was assessed using the isolated perfused rat heart (Langendorff) model. The inflammation profile of rats with CKD was assessed via cytokine ELISA, tissue histology and RNA sequencing. Induction of CKD was confirmed by a significant increase in plasma creatinine and albuminuria. Histology revealed extensive glomerular and tubular damage. Diastolic dysfunction, measured by the reduction of the E/A ratio, was apparent in rats with CKD even following a normal diet. Hearts from rats with CKD had significantly larger infarcts after IR injury. The CKD rats also had statistically higher levels of markers of inflammation including myeloperoxidase, KIM-1 and interleukin-33. RNA sequencing revealed several changes including an increase in inflammatory signaling pathways. In addition, we noted that CKD induced significant cardiac capillary rarefaction. We have established a modified model of adenine-induced CKD, which leads to cardiovascular dysfunction in the absence of adenine. Our observations of capillary rarefaction and inflammation suggest that these may contribute to detrimental cardiovascular outcomes.

Numerous cardioprotective interventions have been reported to reduce myocardial infarct size (IS) in pre-clinical studies. However, their translation for the benefit of patients with acute myocardial infarction (AMI) has been largely disappointing. One reason for the lack of translation is the lack of rigor and reproducibility in pre-clinical studies. To address this, we have established the European IMproving Preclinical Assessment of Cardioprotective Therapies (IMPACT) pig AMI network with centralized randomization and blinded core laboratory IS analysis and validated the network with ischemic preconditioning (IPC) as a positive control. Ten sites in the COST Innovators Grant (IG16225) network participated in the IMPACT network. Three sites were excluded from the final analysis through quality control of infarct images and use of pre-defined exclusion criteria. Using a centrally generated randomization list, pigs were allocated to myocardial ischemia/reperfusion (I/R, N = 5/site) or IPC + I/R (N = 5/site). The primary endpoint was IS [% area-at-risk (AAR)], as quantified by triphenyl-tetrazolium-chloride (TTC) staining in a centralized, blinded core laboratory (5 sites), or IS [% left-ventricular mass (LV)], as quantified by a centralized, blinded cardiac magnetic resonance (CMR) core laboratory (2 sites). In pooled analyses, IPC significantly reduced IS when compared to I/R (57 ± 14 versus 32 ± 19 [%AAR] N = 25 pigs/group; p < 0.001; 25 ± 13 versus 14 ± 8 [%LV]; N = 10 pigs/group; p = 0.021). In site-specific analyses, in 4 of the 5 sites, IS was significantly reduced by IPC when compared to I/R when quantified by TTC and in 1 of 2 sites when quantified by CMR. A pig AMI multicenter European network with centralized randomization and core blinded IS analysis was established and validated with the aim to improve the reproducibility of cardioprotective interventions in pre-clinical studies and the translation of cardioprotection for patient benefit.

Cardiac macrophages facilitate electrical conduction through the atrioventricular-node (AV) in mice. A possible role for cardiomyocyte-macrophage coupling on the effect of antiarrhythmic therapy has not been investigated yet. Holter monitoring was conducted in LysM^CrexCsf1r^LsL−DTR mice (MM^DTR) under baseline conditions and after an elctrophysiological stress test by flecainide. In vivo effects were recapitulated in vitro by patch-clamp experiments. The underlying mechanism was characterized by expression and localization analysis of connexin43 (Cx43) and voltage-gated-sodium-channel-5 (Na_v1.5). ECG monitoring in MM^DTR mice did not show any significant conduction abnormalities but a significantly attenuated flecainide-induced extension of RR- and PP-intervals. Patch-clamp analysis revealed that the application of flecainide to neonatal rat ventricular cardiomyocytes (CMs) changed their resting-membrane-potential (RMP) to more negative potentials and decreased action-potential-duration (APD50). Coupling of macrophages to CMs significantly enhances the effects of flecainide, with a further reduction of the RMP and APD50, mediated by an upregulation of Cx43 and Na_v1.5 surface expression. Macrophage depletion in mice does not correlate with cardiac electric conduction delay. Cardiac macrophages amplify the effects of flecainide on electrophysiological properties of cardiomyocytes in vivo and in vitro. Mechanistically, formation of macrophage-cardiomyocyte cell–cell-contacts via Cx43 facilitates the recruitment of Na_v1.5 to the cell membrane increasing flecainide effects.

The erythrocyte S1P transporter Mfsd2b is also expressed in the heart. We hypothesized that S1P transport by Mfsd2b is involved in cardiac function. Hypertension-induced cardiac remodeling was induced by 4-weeks Angiotensin II (AngII) administration and assessed by echocardiography. Ca²⁺ transients and sarcomere shortening were examined in adult cardiomyocytes (ACM) from Mfsd2b^+/+ and Mfsd2b^-/- mice. Tension and force development were measured in skinned cardiac fibers. Myocardial gene expression was determined by real-time PCR, Protein Phosphatase 2A (PP2A) by enzymatic assay, and S1P by LC/MS, respectively. Msfd2b was expressed in the murine and human heart, and its deficiency led to higher cardiac S1P. Mfsd2b^-/- mice had regular basal cardiac function but were protected against AngII-induced deterioration of left-ventricular function as evidenced by ~ 30% better stroke volume and cardiac index, and preserved ejection fraction despite similar increases in blood pressure. Mfsd2b^-/- ACM exhibited attenuated Ca²⁺ mobilization in response to isoprenaline whereas contractility was unchanged. Mfsd2b^-/- ACM showed no changes in proteins responsible for Ca²⁺ homeostasis, and skinned cardiac fibers exhibited reduced passive tension generation with preserved contractility. Verapamil abolished the differences in Ca²⁺ mobilization between Mfsd2b^+/+ and Mfsd2b^-/- ACM suggesting that S1P inhibits L-type-Ca²⁺ channels (LTCC). In agreement, intracellular S1P activated the inhibitory LTCC phosphatase PP2A in ACM and PP2A activity was increased in Mfsd2b^-/- hearts. We suggest that myocardial S1P protects from hypertension-induced left-ventricular remodeling by inhibiting LTCC through PP2A activation. Pharmacologic inhibition of Mfsd2b may thus offer a novel approach to heart failure.