Extracellular Matrix Protein Ratios in the Human Heart and Vessels: How to Distinguish Pathological From Physiological Changes?

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

3D Printing of Polysaccharide-Based Hydrogel Scaffolds for Tissue Engineering Applications: A Review

In tissue engineering, 3D printing represents a versatile technology employing inks to construct three-dimensional living structures, mimicking natural biological systems. This technology efficiently translates digital blueprints into highly reproducible 3D objects. Recent advances have expanded 3D printing applications, allowing for the fabrication of diverse anatomical components, including engineered functional tissues and organs. The development of printable inks, which incorporate macromolecules, enzymes, cells, and growth factors, is advancing with the aim of restoring damaged tissues and organs. Polysaccharides, recognized for their intrinsic resemblance to components of the extracellular matrix have garnered significant attention in the field of tissue engineering. This review explores diverse 3D printing techniques, outlining distinctive features that should characterize scaffolds used as ideal matrices in tissue engineering. A detailed investigation into the properties and roles of polysaccharides in tissue engineering is highlighted. The review also culminates in a profound exploration of 3D polysaccharide-based hydrogel applications, focusing on recent breakthroughs in regenerating different tissues such as skin, bone, cartilage, heart, nerve, vasculature, and skeletal muscle. It further addresses challenges and prospective directions in 3D printing hydrogels based on polysaccharides, paving the way for innovative research to fabricate functional tissues, enhancing patient care, and improving quality of life.

Extra-Skeletal Manifestations in Osteogenesis Imperfecta Mouse Models

Osteogenesis imperfecta (OI) is a rare heritable connective tissue disorder of skeletal fragility with an incidence of roughly 1:15,000. Approximately 85% of the pathogenic variants responsible for OI are in the type I collagen genes, COL1A1 and COL1A2, with the remaining pathogenic OI variants spanning at least 20 additional genetic loci that often involve type I collagen post-translational modification, folding, and intracellular transport as well as matrix incorporation and mineralization. In addition to being the most abundant collagen in the body, type I collagen is an important structural and extracellular matrix signaling molecule in multiple organ systems and tissues. Thus, OI disease-causing variants result not only in skeletal fragility, decreased bone mineral density (BMD), kyphoscoliosis, and short stature, but can also result in hearing loss, dentinogenesis imperfecta, blue gray sclera, cardiopulmonary abnormalities, and muscle weakness. The extensive genetic and clinical heterogeneity in OI has necessitated the generation of multiple mouse models, the growing awareness of non-skeletal organ and tissue involvement, and OI being more broadly recognized as a type I collagenopathy.This has driven the investigation of mutation-specific skeletal and extra-skeletal manifestations and broadened the search of potential mechanistic therapeutic strategies. The purpose of this review is to outline several of the extra-skeletal manifestations that have recently been characterized through the use of genetically and phenotypically heterogeneous mouse models of osteogenesis imperfecta, demonstrating the significant potential impact of OI disease-causing variants as a collagenopathy (affecting multiple organ systems and tissues), and its implications to overall health.

Cellular, Molecular and Clinical Aspects of Aortic Aneurysm-Vascular Physiology and Pathophysiology

A disturbance of the structure of the aortic wall results in the formation of aortic aneurysm, which is characterized by a significant bulge on the vessel surface that may have consequences, such as distention and finally rupture. Abdominal aortic aneurysm (AAA) is a major pathological condition because it affects approximately 8% of elderly men and 1.5% of elderly women. The pathogenesis of AAA involves multiple interlocking mechanisms, including inflammation, immune cell activation, protein degradation and cellular malalignments. The expression of inflammatory factors, such as cytokines and chemokines, induce the infiltration of inflammatory cells into the wall of the aorta, including macrophages, natural killer cells (NK cells) and T and B lymphocytes. Protein degradation occurs with a high expression not only of matrix metalloproteinases (MMPs) but also of neutrophil gelatinase-associated lipocalin (NGAL), interferon gamma (IFN-γ) and chymases. The loss of extracellular matrix (ECM) due to cell apoptosis and phenotype switching reduces tissue density and may contribute to AAA. It is important to consider the key mechanisms of initiating and promoting AAA to achieve better preventative and therapeutic outcomes.

Human Coronary Artery Endothelial Cell Response to Porphyromonas gingivalis W83 in a Collagen Three-Dimensional Culture Model

P. gingivalis has been reported to be an endothelial cell inflammatory response inducer that can lead to endothelial dysfunction processes related to atherosclerosis; however, these studies have been carried out in vitro in cell culture models on two-dimensional (2D) plastic surfaces that do not simulate the natural environment where pathology develops. This work aimed to evaluate the pro-inflammatory response of human coronary artery endothelial cells (HCAECs) to P. gingivalis in a 3D cell culture model compared with a 2D cell culture. HCAECs were cultured for 7 days on type I collagen matrices in both cultures and were stimulated at an MOI of 1 or 100 with live P. gingivalis W83 for 24 h. The expression of the genes COX-2, eNOS, and vWF and the levels of the pro-inflammatory cytokines thromboxane A2 (TXA-2) and prostaglandin I2 (PGI2) were evaluated. P. gingivalis W83 in the 2D cell culture increased IL-8 levels at MOI 100 and decreased MCP-1 levels at both MOI 100 and MOI 1. In contrast, the 3D cell culture induced an increased gene expression of COX-2 at both MOIs and reduced MCP-1 levels at MOI 100, whereas the gene expression of eNOS, vWF, and IL-8 and the levels of TXA2 and PGI2 showed no significant changes. These data suggest that in the collagen 3D culture model, P. gingivalis W83 induces a weak endothelial inflammatory response.

Empagliflozin protects against isoprenaline-induced fibrosis in rat heart through modulation of TGF-β/SMAD pathway

AIM

Cardiac fibrosis is characterized by excessive accumulation of fibrous tissue, particularly collagens, in the myocardium. Accumulated fibrous tissue renders myocardium stiffer and reduces its contractility. Empagliflozin is an oral hypoglycemic agent with extra-diabetic functional profile toward maintaining cardiac functions. The present study aimed to examine protective effect of empagliflozin against an in-vivo model of cardiac fibrosis induced by isoprenaline and targeting TGF-β/SMAD signaling as a possible pathway responsible for such effect.

MAIN METHODS

Sixty animals were divided into six groups; the first was normal, and the second was treated with isoprenaline only (5 mg/kg/day I.P.) as a control. The third received pirfenidone (500 mg/kg/day P.O.), and the remaining groups received graded doses (5, 10, 20 mg/kg respectively) of empagliflozin for 14 days before fibrosis induction by isoprenaline (5 mg/kg/day) for 30 days.

KEY FINDINGS

Isoprenaline increased cardiac enzymes, and cardiac tissues revealed elevated concentrations of transforming growth factor β (TGF-β1), monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor α (TNF-α), and c-jun N-terminal kinase (JNK) proteins. Expression of nuclear factor kappa B (NF-κB), alpha smooth muscle actin (α-SMA), collagens, suppressor of mothers against decapentaplegic (SMADs), connective tissue growth factor (CTGF), and fibronectin was upregulated. Empagliflozin improved the histological picture of heart tissue in comparison to fibrosis developed in controls, and protected against fibrosis through significant modulation of all mentioned parameters' concentrations and expressions.

SIGNIFICANCE

Empagliflozin demonstrated a promising protective approach against biological model of cardiac fibrosis through an anti-fibrotic effect through targeting TGF-β signaling pathways.

Inflammation and Fibrosis in Sleep-Disordered Breathing after Acute Myocardial Infarction

BACKGROUND

After acute myocardial infarction (AMI), inflammatory processes promote tissue remodeling at the infarct site. Procollagen III amino-terminal propeptide (PIIINP) is a circulating biomarker of type III collagen synthesis that has been shown to be associated with changes in left ventricular ejection fraction (LVEF) and predicts the occurrence of heart failure after AMI. We hypothesize that sleep-disordered breathing (SDB) promotes inflammation and myocardial fibrosis, leading to reduced myocardial salvage. Therefore, in patients with first-time AMI successfully treated with percutaneous coronary intervention (PCI), we aimed to investigate whether circulating levels of high-sensitivity C-reactive protein (hs-CRP) and PIIINP are elevated in patients with SDB compared to patients without SDB.

METHODS AND RESULTS

This cross-sectional analysis included a total of 88 eligible patients with first AMI and PCI pooled from two prospective studies and stratified according to the apnea-hypopnea index (AHI, with SDB: AHI ≥ 15 h-1). We analyzed circulating levels of hs-CRP and PIIINP 3-5 days after PCI. Patients with SDB had significantly higher levels of hs-CRP (18.3 mg/L [95% CI, 8.0-42.6] vs. 5.8 mg/L [95% CI, 4.2-19.8], p = 0.002) and PIIINP (0.49 U/mL [95% CI, 0.40-0.60] vs. 0.33 U/mL [95% CI, 0.28-0.43], p < 0.001). In a multivariable linear regression model accounting for important clinical confounders, SDB significantly predicted circulating levels of hs-CRP (p = 0.028). Similarly, only SDB was independently associated with PIIINP (p < 0.001). Only obstructive but not central AHI correlated with circulating levels of hs-CRP (p = 0.012) and PIIINP (p = 0.006) levels.

CONCLUSIONS

The presence of obstructive SDB after AMI was independently associated with increased circulating levels of hs-CRP and PIIINP. Our results emphasize the important role of SDB as a common comorbidity and indicate increased inflammation and myocardial fibrosis in these patients.

Increased Collagen I/Collagen III Ratio Is Associated with Hemorrhage in Brain Arteriovenous Malformations in Human and Mouse

Background: The increase in the collagen I (COL I)/COL III ratio enhances vessel wall stiffness and renders vessels less resistant to blood flow and pressure changes. Activated microglia enhance inflammation-induced fibrosis. Hypotheses: The COL I/COL III ratio in human and mouse brain arteriovenous malformations (bAVMs) is associated with bAVM hemorrhage, and the depletion of microglia decreases the COL I/COL III ratio and hemorrhage. Method: COL I, COL III, and hemorrhages were analyzed in 12 human bAVMs and 6 control brains, and mouse bAVMs induced in three mouse lines with activin receptor-like kinase 1 (n = 7) or endoglin (n = 7) deleted in the endothelial cells or brain focally (n = 5). The controls for the mouse study were no-gene-deleted litter mates. Mouse bAVMs were used to test the relationships between the Col I/Col III ratio and hemorrhage and whether the transient depletion of microglia reduces the Col I/Col III ratio and hemorrhage. Results: The COL I/COL III ratio was higher in the human and mouse bAVMs than in controls. The microhemorrhage in mouse bAVMs was positively correlated with the Col I/Col III ratio. Transient depletion of microglia reduced the Col I/Col III ratio and microhemorrhage. Conclusions: The COL I/COL III ratio in the bAVMs was associated with bAVM hemorrhage. The depletion of microglia reduced the bAVM Col I/Col III ratio and hemorrhage.

The Role of Arterial Elasticity in Determining the Degree of Chronic Heart Failure in Myocardial Infarction

Aim      To study the left ventricular (LV) contractile and pumping function during the recovery phase following ligation of the anterior descending coronary artery (CA).Material and methods  Cardiodynamic parameters were studied in Wistar rats 2-4 weeks after experimental myocardial infarction (MI). MI was induced by ligation of the anterior descending CA under zoletil anesthesia. LV catheterization was performed with a standard FTH-1912B-8018 PV catheter inserted into the LV through the right carotid artery.Results After the induction of MI, the mortality rate of animals was 50%. Survived animals developed significant LV dilatation and a decrease in ejection fraction (EF) by an average of 31%. However, major indexes of the pumping function, including minute volume, heart work, and maximum ejection velocity, were within a normal range whereas the maximum filling velocity was almost doubled. Approximately 50% of hearts with dilated LV had normal EF, delayed relaxation, and increased LV diastolic pressure, which qualified this group as a diastolic dysfunction group. The systolic dysfunction group with EF less than 50% of normal had similar values of myocardial contractility and relaxation but differed from the diastolic dysfunction group in more than 50% reduced maximum LV ejection velocity and 1.7 times increased elasticity of the arterial wall. A close inverse correlation was found between these values (r= -0.91).Conclusion      The study results showed that, with a similar myocardial contractile function, the cardiac pumping function is determined by the elasticity of the aortic wall. Therefore, restriction of reactive fibrosis during MI is an important task of modern cardiology.

Detergent-Based Decellularization for Anisotropic Cardiac-Specific Extracellular Matrix Scaffold Generation

Cell-derived extracellular matrix (ECM) has become increasingly popular in tissue engineering applications due to its ability to provide tailored signals for desirable cellular responses. Anisotropic cardiac-specific ECM scaffold decellularized from human induced pluripotent stem cell (hiPSC)-derived cardiac fibroblasts (hiPSC-CFs) mimics the native cardiac microenvironment and provides essential biochemical and signaling cues to hiPSC-derived cardiomyocytes (hiPSC-CMs). The objective of this study was to assess the efficacy of two detergent-based decellularization methods: (1) a combination of ethylenediaminetetraacetic acid and sodium dodecyl sulfate (EDTA + SDS) and (2) a combination of sodium deoxycholate and deoxyribonuclease (SD + DNase), in preserving the composition and bioactive substances within the aligned ECM scaffold while maximumly removing cellular components. The decellularization effects were evaluated by characterizing the ECM morphology, quantifying key structural biomacromolecules, and measuring preserved growth factors. Results showed that both treatments met the standard of cell removal (less than 50 ng/mg ECM dry weight) and substantially preserved major ECM biomacromolecules and growth factors. The EDTA + SDS treatment was more time-efficient and has been determined to be a more efficient method for generating an anisotropic ECM scaffold from aligned hiPSC-CFs. Moreover, this cardiac-specific ECM has demonstrated effectiveness in supporting the alignment of hiPSC-CMs and their expression of mature structural and functional proteins in in vitro cultures, which is crucial for cardiac tissue engineering.

Development of Self-Assembled Biomimetic Nanoscale Collagen-like Peptide-Based Scaffolds for Tissue Engineering: An In Silico and Laboratory Study

Development of biocomposite scaffolds has gained tremendous attention due to their potential for tissue regeneration. However, most scaffolds often contain animal-derived collagen that may elicit an immunological response, necessitating the development of new biomaterials. Herein, we developed a new collagen-like peptide,(Pro-Ala-His)10 (PAH)10, and explored its ability to be utilized as a functional biomaterial by incorporating it with a newly synthesized peptide-based self-assembled gel. The gel was prepared by conjugating a pectin derivative, galataric acid, with a pro-angiogenic peptide (LHYQDLLQLQY) and further functionalized with a cortistatin-derived peptide, (Phe-Trp-Lys-Thr)4 (FWKT)4, and the bio-ionic liquid choline acetate. The self-assembly of (PAH)10 and its interactions with the galactarate-peptide conjugates were examined using replica exchange molecular dynamics (REMD) simulations. Results revealed the formation of a multi-layered scaffold, with enhanced stability at higher temperatures. We then synthesized the scaffold and examined its physicochemical properties and its ability to integrate with aortic smooth muscle cells. The scaffold was further utilized as a bioink for bioprinting to form three-dimensional cell-scaffold matrices. Furthermore, the formation of actin filaments and elongated cell morphology was observed. These results indicate that the (PAH)10 hybrid scaffold provides a suitable environment for cell adhesion, proliferation and growth, making it a potentially valuable biomaterial for tissue engineering.

Doxorubicin-induced modulation of TGF-β signaling cascade in mouse fibroblasts: insights into cardiotoxicity mechanisms

Doxorubicin (DOX)-induced cardiotoxicity has been widely observed, yet the specific impact on cardiac fibroblasts is not fully understood. Additionally, the modulation of the transforming growth factor beta (TGF-β) signaling pathway by DOX remains to be fully elucidated. This study investigated DOX's ability to modulate the expression of genes and proteins involved in the TGF-β signaling cascade in mouse fibroblasts from two sources by assessing the impact of DOX treatment on TGF-β inducible expression of pivotal genes and proteins within fibroblasts. Mouse embryonic fibroblasts (NIH3T3) and mouse primary cardiac fibroblasts (CFs) were treated with DOX in the presence of TGF-β1 to assess changes in protein levels by western blot and changes in mRNA levels by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Our results revealed a dose-dependent reduction in cellular communication network factor 2 (CCN2) protein levels upon DOX treatment in both NIH3T3 and CFs, suggesting an antifibrotic activity by DOX in these fibroblasts. However, DOX only inhibited the TGF-β1 induced expression of COL1 in NIH3T3 cells but not in CFs. In addition, we observed that DOX treatment reduced the expression of BMP1 in NIH3T3 but not primary cardiac fibroblasts. No significant changes in SMAD2 protein expression and phosphorylation in either cells were observed after DOX treatment. Finally, DOX inhibited the expression of Atf4 gene and increased the expression of Cdkn1a, Id1, Id2, Runx1, Tgfb1, Inhba, Thbs1, Bmp1, and Stat1 genes in NIH3T3 cells but not CFs, indicating the potential for cell-specific responses to DOX and its modulation of the TGF-β signaling pathway.

Adult human cardiomyocyte mechanics in osteogenesis imperfecta

Osteogenesis imperfecta (OI) is an extracellular matrix disorder characterized by defects in collagen-1 transport or synthesis, resulting in bone abnormalities. Although reduced collagen in OI hearts has been associated with reduced myocardial stiffness and left ventricular remodeling, its impact on cardiomyocyte (CM) function has not been studied. Here, we explore the tissue-level and CM-level properties of a heart from a deceased organ donor with OI type I. Proteomics and histology confirmed strikingly low expression of collagen 1. Trabecular stretch confirmed low stiffness on the tissue level. However, CMs retained normal viscoelastic properties as revealed by nanoindentation. Interestingly, OI CMs were hypercontractile relative to nonfailing controls after 24 h of culture. In response to 48 h of culture on surfaces with physiological (10 kPa) and pathological (50 kPa) stiffness, OI CMs demonstrated a greater reduction in contractility than nonfailing CMs, suggesting that OI CMs may have an impaired stress response. Levels of detyrosinated α-tubulin, known to be responsive to extracellular stiffness, were reduced in OI CMs. Together these data confirm multiple CM-level adaptations to low stiffness that extend our understanding of OI in the heart and how CMs respond to extracellular stiffness.NEW & NOTEWORTHY In a rare donation of a heart from an individual with osteogenesis imperfecta (OI), we explored cardiomyocyte (CM) adaptations to low stiffness. This represents the first assessment of cardiomyocyte mechanics in OI. The data reveal the hypercontractility of OI CMs with rapid rundown when exposed to acute stiffness challenges, extending our understanding of OI. These data demonstrate that the impact of OI on myocardial mechanics includes cardiomyocyte adaptations beyond known direct effects on the extracellular matrix.

α1-Antitrypsin deficiency associated with increased risk of heart failure

Background

Individuals with α1-antitrypsin deficiency have increased elastase activity resulting in continuous degradation of elastin and early onset of COPD. Increased elastase activity may also affect elastic properties of the heart, which may impact risk of heart failure. We tested the hypothesis that α1-antitrypsin deficiency is associated with increased risk of heart failure in two large populations.

Methods

In a nationwide nested study of 2209 patients with α1-antitrypsin deficiency and 21 869 controls without α1-antitrypsin deficiency matched on age, sex and municipality, we recorded admissions and deaths due to heart failure during a median follow-up of 62 years. We also studied a population-based cohort of another 102 481 individuals from the Copenhagen General Population Study including 187 patients from the Danish α1-Antitrypsin Deficiency Registry, all with genetically confirmed α1-antitrypsin deficiency.

Results

Individuals with versus without α1-antitrypsin deficiency had increased risk of heart failure hospitalisation in the nationwide cohort (adjusted hazard ratio 2.64, 95% CI 2.25-3.10) and in the population-based cohort (1.77, 95% CI 1.14-2.74). Nationwide, these hazard ratios were highest in those without myocardial infarction (3.24, 95% CI 2.70-3.90), without aortic valve stenosis (2.80, 95% CI 2.38-3.29), without hypertension (3.44, 95% CI 2.81-4.22), without atrial fibrillation (3.33, 95% CI 2.75-4.04) and without any of these four diseases (6.00, 95% CI 4.60-7.82). Hazard ratios for heart failure-specific mortality in individuals with versus without α1-antitrypsin deficiency were 2.28 (95% CI 1.57-3.32) in the nationwide cohort and 3.35 (95% CI 1.04-10.74) in the population-based cohort.

Conclusion

Individuals with α1-antitrypsin deficiency have increased risk of heart failure hospitalisation and heart failure-specific mortality in the Danish population.

Investigating possible dilated cardiomyopathy targets via bioinformatic analysis

Dilated cardiomyopathy (DCM) is the most common cardiomyopathy associated with heart failure; however, the underlying mechanism remains unclear. Initially, gene expression data of patients with DCM from the GSE4172 and GSE21610 datasets were obtained from the Gene Expression Omnibus website. Differentially expressed genes (DEGs) were analyzed with a false discovery rate < 0.05 and log2 fold change > 1.2. Furthermore, both the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Set Enrichment Analysis (GSEA) were used to investigate the functional annotations. STRING and Cytoscape tools were used to form the protein-protein interaction (PPI) network and authenticate hub genes. Thereafter, the signature of immune-related genes (IRGs) was selected from the DEGs and data via the IMMPORT website. Hub genes were selected from the differentially expressed IRGs that formed the PPI network. Finally, the receiver-operating characteristic curves of the key genes were measured as biomarkers of DCM. A total of 173 independent DEGs (103 upregulated and 70 downregulated genes) were found in the microarray datasets GSE4172 and GSE21610. KEGG analysis and GSEA indicated that the BMP signaling pathway and apoptosis-related signals have a key effect on DCM development. The 10 hub genes also indicated the key effect of the BMP signaling pathway on DCM. A total of 224 differentially expressed IRGs and 20 featured IRGs were identified. Finally, BMP6, CD69, RUNX2, and SPP1 were identified as possible targets for DCM. Our data suggest a possible molecular regulatory mechanism for DCM therapy. Moreover, BMP6, CD69, RUNX2, and SPP1 may have key effects on the development of DCM.

Physical Training vs. Perindopril Treatment on Arterial Stiffening of Spontaneously Hypertensive Rats: A Proteomic Analysis and Possible Mechanisms

(1) Background: Arterial stiffness is an important predictor of cardiovascular events. Perindopril and physical exercise are important in controlling hypertension and arterial stiffness, but the mechanisms are unclear. (2) Methods: Thirty-two spontaneously hypertensive rats (SHR) were evaluated for eight weeks: SHR_C (sedentary); SHR_P (sedentary treated with perindopril-3 mg/kg) and SHR_T (trained). Pulse wave velocity (PWV) analysis was performed, and the aorta was collected for proteomic analysis. (3) Results: Both treatments determined a similar reduction in PWV (-33% for SHR_P and -23% for SHR_T) vs. SHR_C, as well as in BP. Among the altered proteins, the proteomic analysis identified an upregulation of the EH domain-containing 2 (EHD2) protein in the SHR_P group, required for nitric oxide-dependent vessel relaxation. The SHR_T group showed downregulation of collagen-1 (COL1). Accordingly, SHR_P showed an increase (+69%) in the e-NOS protein level and SHR_T showed a lower COL1 protein level (-46%) compared with SHR_C. (4) Conclusions: Both perindopril and aerobic training reduced arterial stiffness in SHR; however, the results suggest that the mechanisms can be distinct. While treatment with perindopril increased EHD2, a protein involved in vessel relaxation, aerobic training decreased COL1 protein level, an important protein of the extracellular matrix (ECM) that normally enhances vessel rigidity.

Dexamethasone-Induced Arterial Stiffening Is Attenuated by Training due to a Better Balance Between Aortic Collagen and Elastin Levels

PURPOSE

Although the cardioprotective benefits of exercise training are well known, the effects of training on dexamethasone (DEX)-induced arterial stiffness are still unclear. This study was aimed at investigating the mechanisms induced by training to prevent DEX-induced arterial stiffness.

METHODS

Wistar rats were allocated into 4 groups and submitted to combined training (aerobic and resistance exercises, on alternate days, 60% of maximal capacity, for 74 d) or were kept sedentary: sedentary control rats (SC), DEX-treated sedentary rats (DS), combined training control (CT), and DEX-treated trained rats (DT). During the last 14 d, rats were treated with DEX (50 μg/kg per body weight, per day, s.c.) or saline.

RESULTS

DEX increased PWV (+44% vs +5% m/s, for DS vs SC, p<0.001) and increased aortic COL 3 protein level (+75%) in DS. In addition, PWV was correlated with COL3 levels (r=0.682, p<0.0001). Aortic elastin and COL1 protein levels remained unchanged. On the other hand, the trained and treated groups showed lower PWV values (-27% m/s, p<0.001) vs DS and lower values of aortic and femoral COL3 compared with DS.

CONCLUSION

As DEX is widely used in several situations, the clinical relevance of this study is that the maintenance of good physical capacity throughout life can be crucial to alleviate some of its side effects, such as arterial stiffness.

Arterial dissections: Common features and new perspectives

Arterial dissections, which involve an abrupt tear in the wall of a major artery resulting in the intramural accumulation of blood, are a family of catastrophic disorders causing major, potentially fatal sequelae. Involving diverse vascular beds, including the aorta or coronary, cervical, pulmonary, and visceral arteries, each type of dissection is devastating in its own way. Traditionally they have been studied in isolation, rather than collectively, owing largely to the distinct clinical consequences of dissections in different anatomical locations - such as stroke, myocardial infarction, and renal failure. Here, we review the shared and unique features of these arteriopathies to provide a better understanding of this family of disorders. Arterial dissections occur commonly in the young to middle-aged, and often in conjunction with hypertension and/or migraine; the latter suggesting they are part of a generalized vasculopathy. Genetic studies as well as cellular and molecular investigations of arterial dissections reveal striking similarities between dissection types, particularly their pathophysiology, which includes the presence or absence of an intimal tear and vasa vasorum dysfunction as a cause of intramural hemorrhage. Pathway perturbations common to all types of dissections include disruption of TGF-β signaling, the extracellular matrix, the cytoskeleton or metabolism, as evidenced by the finding of mutations in critical genes regulating these processes, including LRP1, collagen genes, fibrillin and TGF-β receptors, or their coupled pathways. Perturbances in these connected signaling pathways contribute to phenotype switching in endothelial and vascular smooth muscle cells of the affected artery, in which their physiological quiescent state is lost and replaced by a proliferative activated phenotype. Of interest, dissections in various anatomical locations are associated with distinct sex and age predilections, suggesting involvement of gene and environment interactions in disease pathogenesis. Importantly, these cellular mechanisms are potentially therapeutically targetable. Consideration of arterial dissections as a collective pathology allows insight from the better characterized dissection types, such as that involving the thoracic aorta, to be leveraged to inform the less common forms of dissections, including the potential to apply known therapeutic interventions already clinically available for the former.

Is a Bioengineered Heart From Recipient Tissues the Answer to the Shortage of Donors in Heart Transplantation?

With the increase in life expectancy worldwide, end-organ failure is becoming more prevalent. In addition, improving post-transplant outcomes has contributed to soaring demand for organs. Unfortunately, thousands have died waiting on the transplant list due to the critical shortage of organs. The success of bioengineered hearts may eventually lead to the production of limitless organs using the patient’s own cells that can be transplanted into them without the need for immunosuppressive medications. Despite being in its infancy, scientists are making tremendous strides in “growing” an artificial heart in the lab. We discuss these processes involved in bioengineering a human-compatible heart in this review. The components of a functional heart must be replicated in a bioengineered heart to make it viable. This review aims to discuss the advances that have already been made and the future challenges of bioengineering a human heart suitable for transplantation.

Angiotensin II Induces Aortic Rupture and Dissection in Osteoprotegerin-Deficient Mice

Background

The biological mechanism of action for osteoprotegerin, a soluble decoy receptor for the receptor activator of nuclear factor‐kappa B ligand in the vascular structure, has not been elucidated. The study aim was to determine if osteoprotegerin affects aortic structural integrity in angiotensin II (Ang II)‐induced hypertension.

Methods and Results

Mortality was higher (P<0.0001 by log‐rank test) in 8‐week‐old male homozygotes of osteoprotegerin gene‐knockout mice given subcutaneous administration of Ang II for 28 days, with an incidence of 21% fatal aortic rupture and 23% aortic dissection, than in age‐matched wild‐type mice. Ang II‐infused aorta of wild‐type mice showed that osteoprotegerin immunoreactivity was present with proteoglycan. The absence of osteoprotegerin was associated with decreased medial and adventitial thickness and increased numbers of elastin breaks as well as with increased periostin expression and soluble receptor activator of nuclear factor‐kappa B ligand concentrations. PEGylated human recombinant osteoprotegerin administration decreased all‐cause mortality (P<0.001 by log‐rank test), the incidence of fatal aortic rupture (P=0.08), and aortic dissection (P<0.001) with decreasing numbers of elastin breaks, periostin expressions, and soluble receptor activator of nuclear factor‐kappa B ligand concentrations in Ang II‐infused osteoprotegerin gene‐knockout mice.

Conclusions

These data suggest that osteoprotegerin protects against aortic rupture and dissection in Ang II‐induced hypertension by inhibiting receptor activator of nuclear factor‐kappa B ligand activity and periostin expression.

Integrative bioinformatics analysis of potential therapeutic targets and immune infiltration characteristics in dilated cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is currently the major cause of systolic heart failure. This study explored potential therapeutic targets and investigated the role of immune cell infiltration in DCM.

Methods

Three DCM datasets (GSE3585, GSE9800, and GSE84796) from the Gene Expression Omnibus (GEO) database were merged into an integrated dataset, and batch effects were removed. Differentially expressed genes (DEGs) were screened and the associations between gene co-expression modules and clinical traits were assessed by weighted gene co-expression network analysis (WGCNA) in R software. Any DEGs from the integrated dataset overlapped with the significant module genes were defined as common genes (CGs). Enrichment analysis of the CGs was performed. The protein-protein interaction (PPI) network of the CGs was visualized and the hub gene was identified by using Cytoscape 3.8.2 software. The miRNA-transcription factor-mRNA (miRNA-TF-mRNA) network was constructed using Cytoscape to unveil the regulatory relationships in DCM. Finally, the CIBERSORT method (https://cibersort.stanford.edu/) was used to investigate immune cell infiltration in DCM.

Results

A total of 53 DEGs were identified, and 5 gene co-expression modules were detected by WGCNA of the DCM and control group samples of cardiac tissue. Genes such as FRZB, ASPN, and PHLDA1 were significantly upregulated, whereas IDH2 and ENDOG were significantly downregulated. Functional enrichment analysis showed that CGs were mainly enriched in the extracellular matrix (ECM) signaling pathway. ASPN was the hub gene in the PPI network. The miRNA-TF-mRNA network revealed that FRZB and ASPN were targeted by paired related homeobox 2 (Prrx2). We also found that miR-129-5p could regulate ASPN, PHLDA1, and IDH2 simultaneously. The immune infiltration analysis revealed higher levels of M1 macrophages in DCM samples than in the control samples.

Conclusions

In conclusion, we speculate that miR-129-5p might target ASPN in regulating DCM via the ECM signaling pathway. Macrophage infiltration may be involved in ECM remodeling and eventually lead to DCM.

Leptin: an entry point for the treatment of peripheral tissue fibrosis and related diseases

Leptin is a small peptide mainly secreted by adipocyte, which acts on the central nervous system of the hypothalamus to regulate the body's energy balance by inhibiting food intake, it also can directly act on specific cells through leptin receptors (for example, ObRa, which exists in the blood-brain barrier or kidneys), thereby affect cell metabolism. Excessive deposition of extracellular matrix (ECM) causes damage to normal tissues or destruction of organ structure, which will eventually lead to tissue or organ fibrosis. The sustainable development of fibrosis can lead to structural damage and functional decline of organs, and even exhaustion, which seriously threatens human health and life. In recent years, studies have found that leptin directly alleviates the fibrosis process of various tissues and organs in mammals. Therefore, we speculate that leptin may become a significant treatment for fibrosis of various tissues and organs in the future. So, the main purpose of this review is to explore the specific mechanism of leptin in the process of fibrosis in multiple tissues and organs, and to provide a theoretical basis for the treatment of various tissues and organs fibrosis and related diseases caused by it, which is of great significance in the future.

The Role of Oxidative Stress in the Aging Heart

Medical advances and the availability of diagnostic tools have considerably increased life expectancy and, consequently, the elderly segment of the world population. As age is a major risk factor in cardiovascular disease (CVD), it is critical to understand the changes in cardiac structure and function during the aging process. The phenotypes and molecular mechanisms of cardiac aging include several factors. An increase in oxidative stress is a major player in cardiac aging. Reactive oxygen species (ROS) production is an important mechanism for maintaining physiological processes; its generation is regulated by a system of antioxidant enzymes. Oxidative stress occurs from an imbalance between ROS production and antioxidant defenses resulting in the accumulation of free radicals. In the heart, ROS activate signaling pathways involved in myocyte hypertrophy, interstitial fibrosis, contractile dysfunction, and inflammation thereby affecting cell structure and function, and contributing to cardiac damage and remodeling. In this manuscript, we review recent published research on cardiac aging. We summarize the aging heart biology, highlighting key molecular pathways and cellular processes that underlie the redox signaling changes during aging. Main ROS sources, antioxidant defenses, and the role of dysfunctional mitochondria in the aging heart are addressed. As metabolism changes contribute to cardiac aging, we also comment on the most prevalent metabolic alterations. This review will help us to understand the mechanisms involved in the heart aging process and will provide a background for attractive molecular targets to prevent age-driven pathology of the heart. A greater understanding of the processes involved in cardiac aging may facilitate our ability to mitigate the escalating burden of CVD in older individuals and promote healthy cardiac aging.

Effects of chronic intermittent hypoxia on left cardiac function in young and aged mice

Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular disease that is characterized by chronic intermittent hypoxia (CIH), and its impact is related to age. This study aims to assess the age-related impact of CIH on cardiac function and to further explore the mechanism. After 8 weeks of severe CIH exposure, the hearts of young mice showed slight physiological hypertrophy, decreased diastolic function, and collagen I accumulation but no obvious change in contractile function. However, the contractile function of the hearts of aged mice was severely decreased. CIH exposure promoted the fragmentation of mitochondria in the hearts of aged mice and decreased the mitochondrial membrane potential of cardiomyocytes, but these effects were not observed in young mice exposed to the same conditions. CIH induced significant decreases in basal respiration, maximum respiration and ATP production in cardiac mitochondria of aged mice compared to those of young mice. The assessment of mitochondrial-related proteins showed that young mouse hearts had upregulated adaptive nuclear respiratory factors (Nrf)1/2 sirtuin (SIRT)1/3 and transcription factor A (TFAM) expression that stabilized mitochondrial function in response to CIH exposure. Aged mouse hearts exhibited maladaptation to CIH exposure, and downregulation of SIRT1 and TFAM expression resulted in mitochondrial dysfunction.

Apelin expression deficiency in mice contributes to vascular stiffening by extracellular matrix remodeling of the aortic wall

Numerous recent studies have shown that in the continuum of cardiovascular diseases, the measurement of arterial stiffness has powerful predictive value in cardiovascular risk and mortality and that this value is independent of other conventional risk factors, such as age, cholesterol levels, diabetes, smoking, or average blood pressure. Vascular stiffening is often the main cause of arterial hypertension (AHT), which is common in the presence of obesity. However, the mechanisms leading to vascular stiffening, as well as preventive factors, remain unclear. The aim of the present study was to investigate the consequences of apelin deficiency on the vascular stiffening and wall remodeling of aorta in mice. This factor freed by visceral adipose tissue, is known for its homeostasic role in lipid and vascular metabolisms, or again in inflammation. We compared the level of metabolic markers, inflammation of white adipose tissue (WAT), and aortic wall remodeling from functional and structural approaches in apelin-deficient and wild-type (WT) mice. Apelin-deficient mice were generated by knockout of the apelin gene (APL-KO). From 8 mice by groups, aortic stiffness was analyzed by pulse wave velocity measurements and by characterizations of collagen and elastic fibers. Mann-Whitney statistical test determined the significant data (p < 5%) between groups. The APL-KO mice developed inflammation, which was associated with significant remodeling of visceral WAT, such as neutrophil elastase and cathepsin S expressions. In vitro, cathepsin S activity was detected in conditioned medium prepared from adipose tissue of the APL-KO mice, and cathepsin S activity induced high fragmentations of elastic fiber of wild-type aorta, suggesting that the WAT secretome could play a major role in vascular stiffening. In vivo, remodeling of the extracellular matrix (ECM), such as collagen accumulation and elastolysis, was observed in the aortic walls of the APL-KO mice, with the latter associated with high cathepsin S activity. In addition, pulse wave velocity (PWV) and AHT were increased in the APL-KO mice. The latter could explain aortic wall remodeling in the APL-KO mice. The absence of apelin expression, particularly in WAT, modified the adipocyte secretome and facilitated remodeling of the ECM of the aortic wall. Thus, elastolysis of elastic fibers and collagen accumulation contributed to vascular stiffening and AHT. Therefore, apelin expression could be a major element to preserve vascular homeostasis.