Cardiac remodeling secondary to chronic volume overload is attenuated by a novel MMP9/2 blocking antibody

A Need to Preserve Ejection Fraction during Heart Failure

Heart failure (HF) is a significant global healthcare burden with increasing prevalence and high morbidity and mortality rates. The diagnosis and management of HF are closely tied to ejection fraction (EF), a crucial parameter for evaluating disease severity and determining treatment plans. This paper emphasizes the urgent need to maintain EF during heart failure, highlighting the distinct phenotypes of HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). It discusses the complexities of HFrEF pathophysiology and its negative impact on patient outcomes, stressing the importance of ongoing research and the development of effective therapeutic interventions to slow down the progression from preserved to reduced ejection fraction. Additionally, it explores the potential role of renal denervation in preserving ejection fraction and its implications for HFrEF management. This comprehensive review aims to offer valuable insights into the critical role of EF preservation in enhancing outcomes for patients with heart failure.

Cardioprotective effects of the aqueous extract of Echinops cephalotes on myocardial ischemia-reperfusion in rats by modulation of MMP-2, MMP-9, TIMP, and oxidative stress

Echinops plants have received great attention for the treatment of many diseases due to pharmacological properties such as their antidiabetic, antioxidant, and anti-inflammatory characteristics. The major purpose of the present study was to investigate the cardioprotective benefits of Echinops cephalotes (Ech) against myocardial ischemia-reperfusion (MI/R) injury. Male Wistar rats were randomly allocated to three groups: sham, MI, and MI + Ech. The left coronary artery (LAD) was blocked for 30 minutes to induce MI. In the treatment group, rats were given 150 mg/kg/day of Ech extract for 28 days. Aqueous extracts were made from Echinops plants. To study heart function, fibrosis, cardiac damage indicators, and oxidative stress factors, echocardiography, Masson's trichrome staining, and biochemical tests were used. The expression of matrix metalloproteinase 2 and 9 (MMP2 and MMP-9) and tissue inhibitor of metalloproteinase (TIMP) was determined using Western blotting. Tissue damage was assessed using hematoxylin and eosin staining. MI group exhibited significantly reduced ejection fraction (EF) and fractional shortening (FS), enhanced levels of lactate dehydrogenase (LDH), creatine kinase MB (CK-MB), cardiac Troponin I (cTnI), and malondialdehyde (MDA), as well as a decrease in the Glutathione (GSH) tissue content, reduced activity of superoxide dismutase (SOD), increasing fibrosis, upregulations of MMP-2 and MMP-9, and reduction of TIMP compared to the sham group. The findings suggest that Ech in particular, could be a promising therapeutic agent to reduce the damage in MI by targeting oxidative stress and modulating the activities of matrix metalloproteinases and their tissue inhibitors.

Microvascular function and inflammatory activation in Takotsubo cardiomyopathy

AIMS

The aim of this study was to determine microvascular function in the acute phase of Takotsubo syndrome (TTS) and to identify inflammatory mediators that could reflect TTS-induced pathology.

METHODS AND RESULTS

The study included 20 females [median age 65 years; interquarile range (IQR) = 58-70 years] with TTS according to the Mayo diagnostic criteria. During heart catheterization, we determined the index of microvascular resistance (IMR) and drew blood samples almost simultaneously from the aorta and coronary sinus. Cardiac magnetic resonance imaging (MRI) was done in the acute phase. We present descriptive coronary physiology and cardiac MRI data and compare inflammatory biomarkers between samples from the aorta, coronary sinus, and venous samples after 3 months using the Wilcoxon signed-rank test. For comparison, we also analysed the actual biomarkers in venous blood from 15 healthy female controls. A supplementary analysis explored Spearman's rank correlation between the inflammatory biomarkers, IMR, MRI data, and cardiac biomarkers. The median IMR was 16.5 mmHg·s (IQR = 10.5-28.2 mmHg·s), which was only slightly higher than that in the reference populations. Seven (35%) of the study subjects had IMR > 25 mmHg·s, suggesting a microvascular dysfunction. IMR was not affected by time from symptom onset. According to MRI, the apical region of the left ventricle was affected in 65% of the subjects. The median ejection fraction was 41% (IQR = 31-48%). Biomarker analyses revealed elevation of markers for extracellular matrix remodelling and fibrosis, inflammation, immune activation, and upstream inflammation as compared with healthy controls. Only the levels of interleukin (IL)-1 receptor antagonist and soluble T-cell immunoglobulin mucin domain-3 (sTIM-3) were higher in the coronary sinus than in the aorta. No variable was significantly correlated with IMR. The IL-6 level in the aorta was inversely correlated with the left ventricular ejection fraction. Growth differentiation factor-15, osteoprotegerin, and von Willebrand factor levels in both aorta and coronary sinus were positively correlated with N-terminal-pro-brain-natriuretic peptide, while the correlations of IL-6 and sTIM-3 with N-terminal-pro-brain-natriuretic peptide were restricted to the aorta and coronary sinus, respectively. While most of the markers were within normal limits after 3 months, matrix metalloproteinase-9 increased during follow-up to reach levels higher than those in the healthy controls.

CONCLUSION

The median IMR was only slightly elevated in this study, but about one-third of the patients had values indicating microvascular dysfunction. The present study supports the involvement of several inflammatory pathways in TTS, including monocyte/macrophage activation, with sTIM-3 as a potential novel marker.

Molecular Changes in Prepubertal Left Ventricular Development Under Experimental Volume Overload

Background

Left ventricular (LV) volume overload (VO), commonly found in patients with chronic aortic regurgitation (AR), leads to a series of left ventricular (LV) pathological responses and eventually irreversible LV dysfunction. Recently, questions about the applicability of the guideline for the optimal timing of valvular surgery to correct chronic AR have been raised in regard to both adult and pediatric patients. Understanding how VO regulates postnatal LV development may shed light on the best timing of surgical or drug intervention.

Methods and Results

Prepubertal LV VO was induced by aortocaval fistula (ACF) on postnatal day 7 (P7) in mice. LV free walls were analyzed on P14 and P21. RNA-sequencing analysis demonstrated that normal (P21_Sham vs.P14_Sham) and VO-influenced (P21_VO vs. P14_VO) LV development shared common terms of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) in the downregulation of cell cycle activities and the upregulation of metabolic and sarcomere maturation. The enriched GO terms associated with cardiac condition were only observed in normal LV development, while the enriched GO terms associated with immune responses were only observed in VO-influenced LV development. These results were further validated by the examination of the markers of cell cycle, maturation, and immune responses. When normal and VO-influenced LVs of P21 were compared, they were different in terms of immune responses, angiogenesis, percentage of Ki67-positive cardiomyocytes, mitochondria number, T-tubule regularity, and sarcomere regularity and length.

Conclusions

A prepubertal LV VO mouse model was first established. VO has an important influence on LV maturation and development, especially in cardiac conduction, suggesting the requirement of an early correction of AR in pediatric patients. The underlying mechanism may be associated with the activation of immune responses.

Mechanism of Blood-Heart-Barrier Leakage: Implications for COVID-19 Induced Cardiovascular Injury

Although blood–heart-barrier (BHB) leakage is the hallmark of congestive (cardio-pulmonary) heart failure (CHF), the primary cause of death in elderly, and during viral myocarditis resulting from the novel coronavirus variants such as the severe acute respiratory syndrome novel corona virus 2 (SARS-CoV-2) known as COVID-19, the mechanism is unclear. The goal of this project is to determine the mechanism of the BHB in CHF. Endocardial endothelium (EE) is the BHB against leakage of blood from endocardium to the interstitium; however, this BHB is broken during CHF. Previous studies from our laboratory, and others have shown a robust activation of matrix metalloproteinase-9 (MMP-9) during CHF. MMP-9 degrades the connexins leading to EE dysfunction. We demonstrated juxtacrine coupling of EE with myocyte and mitochondria (Mito) but how it works still remains at large. To test whether activation of MMP-9 causes EE barrier dysfunction, we hypothesized that if that were the case then treatment with hydroxychloroquine (HCQ) could, in fact, inhibit MMP-9, and thus preserve the EE barrier/juxtacrine signaling, and synchronous endothelial-myocyte coupling. To determine this, CHF was created by aorta-vena cava fistula (AVF) employing the mouse as a model system. The sham, and AVF mice were treated with HCQ. Cardiac hypertrophy, tissue remodeling-induced mitochondrial-myocyte, and endothelial-myocyte contractions were measured. Microvascular leakage was measured using FITC-albumin conjugate. The cardiac function was measured by echocardiography (Echo). Results suggest that MMP-9 activation, endocardial endothelial leakage, endothelial-myocyte (E-M) uncoupling, dyssynchronous mitochondrial fusion-fission (Mfn2/Drp1 ratio), and mito-myocyte uncoupling in the AVF heart failure were found to be rampant; however, treatment with HCQ successfully mitigated some of the deleterious cardiac alterations during CHF. The findings have direct relevance to the gamut of cardiac manifestations, and the resultant phenotypes arising from the ongoing complications of COVID-19 in human subjects.

Prostaglandin-E2 receptor-4 stimulant rescues cardiac malfunction during myocarditis and protects the heart from adverse ventricular remodeling after myocarditis

Cardioprotective effect of prostaglandin-E2 receptor-4 (EP4) stimulation on the ischemic heart has been demonstrated. Its effect on the heart affected by myocarditis, however, remains uncertain. In this study, we investigated therapeutic effect of EP4 stimulant using a mouse model of autoimmune myocarditis (EAM) that progresses to dilated cardiomyopathy (DCM). EP4 was present in the hearts of EAM mice. Treatment with EP4 agonist (ONO-0260164: 20 mg/kg/day) improved an impaired left ventricular (LV) contractility and reduction of blood pressure on day 21, a peak myocardial inflammation. Alternatively, DCM phenotype, characterized by LV dilation, LV systolic dysfunction, and collagen deposition, was observed on day 56, along with activation of matrix metalloproteinase (MMP)-2 critical for myocardial extracellular matrix disruption, indicating an important molecular mechanism underlying adverse ventricular remodeling after myocarditis. Continued treatment with ONO-0260164 alleviated the DCM phenotype, but this effect was counteracted by its combination with a EP4 antagonist. Moreover, ONO-0260164 inhibited in vivo proteolytic activity of MMP-2 in association with up-regulation of tissue inhibitor of metalloproteinase (TIMP)-3. EP4 stimulant may be a promising and novel therapeutic agent that rescues cardiac malfunction during myocarditis and prevents adverse ventricular remodeling after myocarditis by promoting the TIMP-3/MMP-2 axis.