Plasma levels of heart failure biomarkers are primarily a reflection of extracardiac production

Plasma heart failure (HF) biomarkers, like natriuretic peptides, are important in diagnosis, prognosis and HF treatment. Several novel HF biomarkers have been identified, including Gal-3, GDF-15 and TIMP-1, but their clinical potential remains vague. Here we investigated plasma biomarker levels in relation to tissue expression and structural and functional cardiac changes. Methods: Cardiac remodeling, cardiac function, and plasma and tissue biomarker levels were investigated in mice after myocardial infarction induced by temporal and permanent LAD ligation (tLAD and pLAD). In addition, a pressure overload model induced by transverse aortic constriction (TAC) and an obese/hypertensive HFpEF-like mouse model were investigated. Results: Plasma levels of ANP and its cardiac expression were strictly associated with cardiac remodeling and function. Gal-3, GDF-15 and TIMP-1 cardiac expressions were also related to cardiac remodeling and function, but not their plasma levels. Only directly after myocardial infarction could elevated plasma levels of Gal-3 and TIMP-1 be detected. Eight weeks after infarction, plasma levels were not elevated despite enhanced cardiac expression and low EF (18.3±3.3%, pLAD). Plasma levels of TIMP-1 and GDF-15 were elevated after TAC, but this also correlated with increased lung expression and congestion. In obese-hypertensive mice, elevated plasma levels of Gal-3, GDF-15 and TIMP1 were associated with increased adipose tissue expression and not with cardiac function. Conclusions: The Gal-3, GDF-15 and TIMP-1 plasma pool levels are hardly influenced by dynamic changes in cardiac expression. These biomarkers are not specific for indices of cardiac remodeling, but predominantly reflect stress in other affected tissues and hence provide health information beyond the heart

The phospholamban p.(Arg14del) pathogenic variant leads to cardiomyopathy with heart failure and is unreponsive to standard heart failure therapy

Phospholamban (PLN) plays a role in cardiomyocyte calcium handling as primary inhibitor of sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). The p.(Arg14del) pathogenic variant in the PLN gene results in a high risk of developing dilated or arrhythmogenic cardiomyopathy with heart failure. There is no established treatment other than standard heart failure therapy or heart transplantation. In this study, we generated a novel mouse model with the PLN-R14del pathogenic variant, performed detailed phenotyping, and tested the efficacy of established heart failure therapies eplerenone or metoprolol. Heterozygous PLN-R14del mice demonstrated increased susceptibility to ex vivo induced arrhythmias, and cardiomyopathy at 18 months of age, which was not accelerated by isoproterenol infusion. Homozygous PLN-R14del mice exhibited an accelerated phenotype including cardiac dilatation, contractile dysfunction, decreased ECG potentials, high susceptibility to ex vivo induced arrhythmias, myocardial fibrosis, PLN protein aggregation, and early mortality. Neither eplerenone nor metoprolol administration improved cardiac function or survival. In conclusion, our novel PLN-R14del mouse model exhibits most features of human disease. Administration of standard heart failure therapy did not rescue the phenotype, underscoring the need for better understanding of the pathophysiology of PLN-R14del-associated cardiomyopathy. This model provides a great opportunity to study the pathophysiology, and to screen for potential therapeutic treatments

Author Correction:The phospholamban p.(Arg14del) pathogenic variant leads to cardiomyopathy with heart failure and is unresponsive to standard heart failure therapy (Scientific Reports, (2020), 10, 1, (9819), 10.1038/s41598-020-66656-9)

The title in the original version of this Article contained a typographical error of ‘unresponsive’. The error has now been corrected in the PDF and HTML versions of the Article

23Na chemical shift imaging and Gd enhancement of myocardial edema

Myocardial edema can arise in several disease states. MRI contrast agent can accumulate in edematous tissue, which complicates differential diagnosis with contrast-enhanced (CE)-MRI and might lead to overestimation of infarct size. Sodium Chemical Shift Imaging ((23)Na-CSI) may provide an alternative for edema imaging. We have developed a non-infarct, isolated rat heart model with two levels of edema, which was studied with (23)Na-CSI and CE-MRI. In edematous, but viable tissue the extracellular sodium (Na (e) (+)) signal is hypothesized to increase, but not the intracellular sodium (Na (i) (+)) signal. Isolated hearts were perfused at 60 (n = 6) and 140 mmHg (n = 5). Dimethyl methylphosphonate (DMMP) and phenylphosphonate (PPA) were used to follow edema formation by (31)P-MR Spectroscopy. In separate groups, Thulium(III)1,4,7,10 tetraazacyclododecane-N,N',N″,N'''-tetra(methylenephosphonate) (TmDOTP(5-)) and Gadovist were used for (23)Na-CSI (n = 8) and CE-MRI (n = 6), respectively. PPA normalized signal intensity (SI) was higher at 140 versus 60 mmHg, with a ratio of 1.27 ± 0.12 (p <0.05). The (DMMP-PPA)/dry weight ratio, as a marker of intracellular volume, remained unchanged. The mid-heart cross sectional area (CSA) of the left ventricle (LV) was significantly increased at 140 mmHg. In addition, at 140 mmHg, the LV Na (e) (+) SI increased with a 140 mmHg/60 mmHg ratio of 1.24 ± 0.18 (p <0.05). Na (i) (+) SI remained essentially unchanged. With CE-MRI, a subendocardially enhanced CSA was identified, increasing from 0.20 ± 0.02 cm(2) at 60 mmHg to 0.31 ± 0.02 cm(2) at 140 mmHg (p <0.05). Edema shows up in both CE-MRI and Na (e) (+) . High perfusion pressure causes more edema subendocardially than subepicardially. (23)Na-CSI is an attractive alternative for imaging of edema and is a promising tool to discriminate between edema, acute and chronic M

Overexpression of A kinase interacting protein 1 attenuates myocardial ischemia / reperfusion injury, but does not influence heart failure development

A kinase interacting protein 1 (AKIP1) stimulates physiological growth in cultured cardiomyocytes and attenuates ischaemia/reperfusion (I/R) injury in ex vivo perfused hearts. We aimed to determine whether AKIP1 modulates the cardiac response to acute and chronic cardiac stresses in vivo. Transgenic mice with cardiac-specific overexpression of AKIP1 (AKIP1-TG) were created. AKIP1-TG mice and their wild-type (WT) littermates displayed similar cardiac structure and function. Likewise, cardiac remodelling in response to transverse aortic constriction or permanent coronary artery ligation was identical in AKIP1-TG and WT littermates, as evidenced by serial cardiac magnetic resonance imaging and pressure-volume loop analysis. Histological indices of remodelling, including cardiomyocyte cross-sectional diameter, capillary density, and left ventricular fibrosis were also similar in AKIP1-TG mice and WT littermates. When subjected to 45 min of ischaemia followed by 24 h of reperfusion, AKIP1-TG mice displayed a significant two-fold reduction in myocardial infarct size and reductions in cardiac apoptosis. In contrast to previous reports, AKIP1 did not co-immunoprecipitate with or regulate the activity of the signalling molecules NF-kappa B, protein kinase A, or AKT. AKIP1 was, however, enriched in cardiac mitochondria and co-immunoprecipitated with a key component of the mitochondrial permeability transition (MPT) pore, ATP synthase. Finally, mitochondria isolated from AKIP1-TG hearts displayed markedly reduced calcium-induced swelling, indicative of reduced MPT pore formation. In contrast to in vitro studies, AKIP1 overexpression does not influence cardiac remodelling in response to chronic cardiac stress. AKIP1 does, however, reduce myocardial I/R injury through stabilization of the MPT pore. These findings suggest that AKIP1 deserves further investigation as a putative treatment target for cardioprotection from I/R injury during acute myocardial infarction

Molecular MRI of murine atherosclerotic plaque targeting NGAL: a protein associated with unstable human plaque characteristics

Aims Neutrophil gelatinase-associated lipocalin (NGAL) is an effector molecule of the innate immune system. One of its actions is the prolongation of matrix metalloproteinase-9 (MMP-9) activity by the formation of a degradation-resistant NGAL/MMP-9 complex. We studied NGAL in human atherosclerotic lesions and we examined whether NGAL could act as a target for molecular imaging of atherosclerotic plaques. Methods and results Increased levels of NGAL and the NGAL/MMP-9 complex were associated with high lipid content, high number of macrophages, high interleukin-6 (IL-6) and IL-8 levels, and low smooth muscle cell content in human atherosclerotic lesions obtained during carotid endarterectomy (n = 122). Moreover, plaque levels of NGAL tended to be higher when intra-plaque haemorrhage (IPH) or luminal thrombus was present (n 77) than without the presence of IPH or thrombus (n 30). MMP-9 and -8 activities were strongly related to NGAL levels. The enhancement on magnetic resonance (MR) images of the abdominal aorta of ApoE(-/-)/eNOS(-/-) mice was observed at 72 h after injection of NGAL/24p3-targeted micelles. The specificity of these results was validated by histology, and co-localization of micelles, macrophages, and NGAL/24p3 was observed. Conclusion NGAL is highly expressed in atheromatous human plaques and associated with increased MMP-9 activity. NGAL can be detected in murine atherosclerotic arteries using targeted high-resolution MR imaging. Therefore, we conclude that NGAL might serve as a novel imaging target for the detection of high-risk plaques

Molecular MRI of murine atherosclerotic plaque targeting NGAL: a protein associated with unstable human plaque characteristics

Aims Neutrophil gelatinase-associated lipocalin (NGAL) is an effector molecule of the innate immune system. One of its actions is the prolongation of matrix metalloproteinase-9 (MMP-9) activity by the formation of a degradation-resistant NGAL/MMP-9 complex. We studied NGAL in human atherosclerotic lesions and we examined whether NGAL could act as a target for molecular imaging of atherosclerotic plaques. Methods and results Increased levels of NGAL and the NGAL/MMP-9 complex were associated with high lipid content, high number of macrophages, high interleukin-6 (IL-6) and IL-8 levels, and low smooth muscle cell content in human atherosclerotic lesions obtained during carotid endarterectomy (n = 122). Moreover, plaque levels of NGAL tended to be higher when intra-plaque haemorrhage (IPH) or luminal thrombus was present (n 77) than without the presence of IPH or thrombus (n 30). MMP-9 and -8 activities were strongly related to NGAL levels. The enhancement on magnetic resonance (MR) images of the abdominal aorta of ApoE(-/-)/eNOS(-/-) mice was observed at 72 h after injection of NGAL/24p3-targeted micelles. The specificity of these results was validated by histology, and co-localization of micelles, macrophages, and NGAL/24p3 was observed. Conclusion NGAL is highly expressed in atheromatous human plaques and associated with increased MMP-9 activity. NGAL can be detected in murine atherosclerotic arteries using targeted high-resolution MR imaging. Therefore, we conclude that NGAL might serve as a novel imaging target for the detection of high-risk plaques