Understanding the role of the extracellular matrix in cardiovascular development and disease: where do we go from here?

Effects and mechanisms of Porphyromonas gingivalis outer membrane vesicles induced cardiovascular injury

BACKGROUND

The outer membrane vesicles (OMVs) derived from Porphyromonas gingivalis (P. gingivalis) have long been acknowledged for their crucial role in the initiation of periodontitis. However, the implications of P. gingivalis OMVs in the context of cardiovascular disease (CVD) remain incompletely understood. This study aimed to clarify both the impact and the underlying mechanisms through which P. gingivalis OMVs contribute to the propagation of distal cardiovascular inflammation and trauma.

METHODS

In this study, various concentrations (0, 1.25, 2.5, and 4.5 µg/µL) of P. gingivalis OMVs were microinjected into the common cardinal vein of zebrafish larvae at 48 h post-fertilization (hpf) to assess changes in cardiovascular injury and inflammatory response. Zebrafish larvae from both the PBS and the 2.5 µg/µL injection cohorts were harvested at 30 h post-injection (hpi) for transcriptional analysis. Real-time quantitative PCR (RT-qPCR) was employed to evaluate relative gene expression.

RESULTS

These findings demonstrated that P. gingivalis OMVs induced pericardial enlargement in zebrafish larvae, caused vascular damage, increased neutrophil counts, and activated inflammatory pathways. Transcriptomic analysis further revealed the involvement of the immune response and the extracellular matrix (ECM)-receptor interaction signaling pathway in this process.

CONCLUSION

This study illuminated potential mechanisms through which P. gingivalis OMVs contribute to CVD. It accentuated their involvement in distal cardiovascular inflammation and emphasizes the need for further research to comprehensively grasp the connection between periodontitis and CVD.

Anti-inflammatory Effects of S. cumini Seed Extract on Gelatinase-B (MMP-9) Regulation against Hyperglycemic Cardiomyocyte Stress

Black berry (Syzygium cumini) fruit is useful in curing diabetic complications; however, its role in diabetes-induced cardiomyopathy is not yet known. In this study, we investigated the regulation of gelatinase-B (MMP-9) by S. cumini methanol seed extract (MSE) in diabetic cardiomyopathy using real-time PCR, RT-PCR, immunocytochemistry, gel diffusion assay, and substrate zymography. The regulatory effects of MSE on NF-κB, TNF-α, and IL-6 were also examined. Identification and estimation of polyphenol constituents present in S. cumini extract were carried out using reverse-phase HPLC. Further, in silico docking studies of identified polyphenols with gelatinase-B were performed to elucidate molecular level interaction in the active site of gelatinase-B. Docking studies showed strong interaction of S. cumini polyphenols with gelatinase-B. Our findings indicate that MSE significantly suppresses gelatinase-B expression and activity in high-glucose- (HG-) stimulated cardiomyopathy. Further, HG-induced activation of NF-κB, TNF-α, and IL-6 was also remarkably reduced by MSE. Our results suggest that S. cumini MSE may be useful as an effective functional food and dietary supplement to regulate HG-induced cardiac stress through gelatinase.

Multiscale Analysis of Extracellular Matrix Remodeling in the Failing Heart

RATIONALE

Cardiac ECM (extracellular matrix) comprises a dynamic molecular network providing structural support to heart tissue function. Understanding the impact of ECM remodeling on cardiac cells during heart failure (HF) is essential to prevent adverse ventricular remodeling and restore organ functionality in affected patients.

OBJECTIVES

We aimed to (1) identify consistent modifications to cardiac ECM structure and mechanics that contribute to HF and (2) determine the underlying molecular mechanisms.

METHODS AND RESULTS

We first performed decellularization of human and murine ECM (decellularized ECM) and then analyzed the pathological changes occurring in decellularized ECM during HF by atomic force microscopy, 2-photon microscopy, high-resolution 3-dimensional image analysis, and computational fluid dynamics simulation. We then performed molecular and functional assays in patient-derived cardiac fibroblasts based on YAP (yes-associated protein)-transcriptional enhanced associate domain (TEAD) mechanosensing activity and collagen contraction assays. The analysis of HF decellularized ECM resulting from ischemic or dilated cardiomyopathy, as well as from mouse infarcted tissue, identified a common pattern of modifications in their 3-dimensional topography. As compared with healthy heart, HF ECM exhibited aligned, flat, and compact fiber bundles, with reduced elasticity and organizational complexity. At the molecular level, RNA sequencing of HF cardiac fibroblasts highlighted the overrepresentation of dysregulated genes involved in ECM organization, or being connected to TGFβ1 (transforming growth factor β1), interleukin-1, TNF-α, and BDNF signaling pathways. Functional tests performed on HF cardiac fibroblasts pointed at mechanosensor YAP as a key player in ECM remodeling in the diseased heart via transcriptional activation of focal adhesion assembly. Finally, in vitro experiments clarified pathological cardiac ECM prevents cell homing, thus providing further hints to identify a possible window of action for cell therapy in cardiac diseases.

CONCLUSIONS

Our multiparametric approach has highlighted repercussions of ECM remodeling on cell homing, cardiac fibroblast activation, and focal adhesion protein expression via hyperactivated YAP signaling during HF.

Cartilage oligomeric matrix protein fine-tunes disturbed flow-induced endothelial activation and atherogenesis

Disturbed flow leads to increased inflammatory responses of endothelial cells (ECs) prone to atherogenic state. Currently, little is known about the physiological mechanisms protecting vasculature against disturbed flow-activated ECs leading to atherosclerosis. Understanding the protective mediators involved in EC activation could provide novel therapeutic strategies for atherosclerosis. The extracellular matrix microenvironment profoundly regulates cellular homeostasis. A non-EC resident ECM protein, cartilage oligomeric matrix protein (COMP), has diverse protective roles in the cardiovascular system. To determine whether COMP could protect against disturbed flow-activated EC and atherosclerosis, we compared oscillatory shear stress (OSS) induced EC activation coated with various ECM proteins. Purified COMP inhibited EC activation caused by OSS. EC activation was upregulated in the aortic arch where the flow is disturbed in COMP^-/- mice as compared with wild-type mice under physiological conditions or pathologically in partially ligated mouse carotid arteries. Mechanistically, co-immunoprecipitation, mammalian two-hybrid and FRET assay results suggest that COMP bound directly to integrin α5 via its C-terminus. We next synthesized a COMP-derived peptidomimetics (CCPep24) mimicking a specific COMP-integrin α5 interaction and found that CCPep24 protected against EC activation and atherogenesis in vivo. This study extends our current understanding of how ECM and flow coordinately fine-tune EC homeostasis and reveals the potential therapeutic effect of COMP or COMP-derived peptidomimetics on blocking aberrant integrin α5 activation, inflammatory EC activation and atherosclerosis pathogenesis.

Curcumin suppresses gelatinase B mediated norepinephrine induced stress in H9c2 cardiomyocytes

Background

Extracellular matrix (ECM) remodeling facilitates biomechanical signals in response to abnormal physiological conditions. This process is witnessed as one of the major effects of the stress imposed by catecholamines, such as epinephrine and norepinephrine (NE), on cardiac muscle cells. Matrix metalloproteinases (MMPs) are the key proteases involved in degradation of the ECM in heart.

Objectives

The present study focuses on studying the effect of curcumin on Gelatinase B (MMP-9), an ECM remodeling regulatory enzyme, in NE-induced cardiac stress. Curcumin, a bioactive polyphenol found in the spice turmeric, has been studied for its multi-fold beneficial properties. This study focuses on investigating the role of curcumin as a cardio-protectant.

Methods

H9c2 cardiomyocytes were subjected to NE and curcumin treatments to study the response in stress conditions. Effect on total collagen content was studied using Picrosirus red staining. Gelatinase B activity was assessed through Gel-Diffusion Assay and Zymographic techniques. RT-PCR, Western Blotting and Immunocytochemistry were performed to study effect on expression of gelatinase B. Further, the effect of curcumin on the localization of NF-κB, known to regulate gelatinase B, was also examined.

Results

Curcumin suppressed the increase in the total collagen content under hypertrophic stress and was found to inhibit the in-gel and in-situ gelatinolytic activity of gelatinase B. Moreover, it was found to suppress the mRNA and protein expression of gelatinase B.

Conclusions

The study provides an evidence for an overall inhibitory effect of curcumin on Gelatinase B in NE-induced hypertrophic stress in H9c2 cardiomyocytes which may contribute in the prevention of ECM remodeling.

Using proteomics to uncover extracellular matrix interactions during cardiac remodeling

The left ventricle (LV) responds to a myocardial infarction with an orchestrated sequence of events that result in fundamental changes to both the structure and function of the myocardium. This collection of responses is termed as LV remodeling. Myocardial ischemia resulting in necrosis is the initiating event that culminates in the formation of an extracellular matrix (ECM) rich infarct scar that replaces necrotic myocytes. While the cardiomyocyte is the major cell type that responds to ischemia, infiltrating leukocytes and cardiac fibroblasts coordinate the subsequent wound healing response. The matrix metalloproteinase family of enzymes regulates the inflammatory and ECM responses that modulate scar formation. Matridomics is the proteomic evaluation focused on ECM, while degradomics is the proteomic evaluation of proteases as well as their inhibitors and substrates. This review will summarize the use of proteomics to better understand matrix metalloproteinase roles in post myocardial infarction LV remodeling.

Matrix metalloproteinases: drug targets for myocardial infarction

Myocardial infarction (MI) remains a major cause of morbidity and mortality worldwide. Rapid advances in the treatment of acute MI have significantly improved short-term outcomes in patients, due in large part to successes in preventing myocardial cell death and limiting infarct area during the time of ischemia and subsequent reperfusion. Matrix metalloproteases (MMPs) play key roles in post-MI cardiac remodeling and in the development of adverse outcomes. This review highlights the importance of MMPs in the injury and remodeling response of the left ventricle and also discusses their potential as therapeutic targets Additional pre-clinical and clinical research is needed to further investigate and understand the cardioprotective effects of MMPs inhibitors.

A mean-field model of ventricular muscle tissue

A theoretical model of the cross-linking topology of ventricular muscle tissue is developed. Using parameter estimation the terms of the theoretical model are estimated for normal and pathological conditions. The model represents the anisotropic structure of the tissue, reproduces published experimental data and characterizes the role of different tissue components in the observed macroscopic behavior. Changes in the material parameters are consistent with expected structural changes and the model is extended to reproduce force-Calcium relationships. Model results are invoked to argue that semisoft behavior and the material axis anisotropy arise from the constraints on the extracellular matrix cross-linking topology.

A proteomic analysis of the functional effects of fatty acids in NIH 3T3 fibroblasts

Previous studies have demonstrated that long chain fatty acids influence fibroblast function at sub-lethal concentrations. This study is the first to assess the effects of oleic, linoleic or palmitic acids on protein expression of fibroblasts, as determined by standard proteomic techniques. The fatty acids were not cytotoxic at the concentration used in this work as assessed by membrane integrity, DNA fragmentation and the MTT assay but significantly increased cell proliferation. Subsequently, a proteomic analysis was performed using two dimensional difference gel electrophoresis (2D-DIGE) and MS based identification. Cells treated with 50 μM oleic, linoleic or palmitic acid for 24 h were associated with 24, 22, 16 spots differentially expressed, respectively. Among the identified proteins, α-enolase and far upstream element binding protein 1 (FBP-1) are of importance due to their function in fibroblast-associated diseases. However, modulation of α-enolase and FBP-1 expression by fatty acids was not validated by the Western blot technique.

Adenylyl cyclase 6 improves calcium uptake and left ventricular function in aged hearts

OBJECTIVES

This study tested the hypothesis that activation of adenylyl cyclase 6 (AC6) expression in cardiac myocytes improves calcium uptake and left ventricular (LV) function in aging mice.

BACKGROUND

Aging hearts exhibit impaired β-adrenergic receptor signaling and LV dysfunction.

METHODS

Twenty-month-old mice with cardiac-directed and regulated AC6 expression were randomized into 2 groups, and AC6 expression was activated in 1 group (AC6-On) but not the other (AC6-Off). One month later, LV function and sarcoplasmic reticulum calcium uptake were assessed.

RESULTS

AC6 expression was associated with increased LV contractility, as reflected by ejection fraction (p = 0.02), rate of pressure development (p = 0.002), and slope of the LV end-systolic pressure-volume relationship (p = 0.04). No changes in LV weight to tibial length ratio, LV fibrosis, and expression of fetal genes (atrial natriuretic factor, α-skeletal muscle actin, and β-myosin heavy chain) and collagens were observed between AC6-On and AC6-Off groups. However, LV samples from AC6-On mice showed increases in: isoproterenol-stimulated cAMP production (p = 0.04), cAMP-dependent protein kinase activity (p < 0.0004), phosphorylation of phospholamban (at Ser16 site; p = 0.04) and cardiac troponin I (at Ser23/24 sites; p = 0.01), velocity of sarcoplasmic reticulum calcium uptake (p < 0.0001), and sarcoplasmic reticulum calcium-ATPase2a (SERCA2a) affinity for calcium (p < 0.0001). Finally, we found that AC6 expression increased sarcoplasmic reticulum calcium storage in cardiac myocytes isolated from 23-month-old rats. In contrast, AC6 expression in 7-month-old mice did not change LV function and calcium uptake.

CONCLUSIONS

These results indicate that activation of cardiac AC6 expression improves impaired function of aged hearts through improved calcium uptake.

Dynamic interactions between the cellular components of the heart and the extracellular matrix

The heart is composed of both cellular and acellular components that act in a dynamic fashion from birth to death. The cellular components consist of myocytes, fibroblasts, and vascular cells, including endothelium and smooth muscle. Changes in these components are intimately associated with function by altering the mechanical, chemical, and electrical properties of the heart. In future investigations, it will be important to examine these interactions as dynamic changes in response to physiological signals.

Transcapillary exchange: role and importance of the interstitial fluid pressure and the extracellular matrix

This review will summarize current knowledge on the role of the extracellular matrix (ECM) in general and on the interstitial fluid pressure (P(if)) in particular with regard to their importance in transcapillary exchange. The fluid volume in the interstitial space is normally regulated within narrow limits by automatic re-adjustment of the interstitial hydrostatic and colloid osmotic pressures in response to perturbations in capillary filtration and by the lymphatics. Contrary to this commonly accepted view, P(if) can become an active force and create a fluid flux across the capillaries in several inflammatory reactions and trauma situations rather than limit the changes occurring. The molecular mechanisms involved in the lowering of P(if) include the release of cellular tension exerted on the collagen and microfibril networks in the connective tissue via the collagen-binding beta(1)-integrins, thereby allowing the glycosaminoglycan ground substance, which is normally underhydrated, to expand and take up fluid. Several growth factors and cytokines, including the platelet-derived growth factor BB, are able to reverse a lowering of P(if) and restore the normal compaction of the ECM. The magnitude of the lowering of P(if) varies with the inflammatory response. In several inflammatory reactions, a lowering of P(if) to -5 to -10 mmHg is seen, which will increase capillary filtration by 10-20 times since the normal capillary filtration pressure is usually 0.5-1 mmHg (skin and skeletal muscle). Unless this lowering of P(if) is taken into account, the enhanced solute flux resulting from an inflammatory response will be ascribed to an increased capillary permeability.