Syndecans in heart fibrosis

Characterization of wooden breast myopathy: a focus on syndecans and ECM remodeling

Introduction: The skeletal muscle deformity of commercial chickens (Gallus gallus), known as the wooden breast (WB), is associated with fibrotic myopathy of unknown etiology. For future breeding strategies and genetic improvements, it is essential to identify the molecular mechanisms underlying the phenotype. The pathophysiological hallmarks of WB include severe skeletal muscle fibrosis, inflammation, myofiber necrosis, and multifocal degeneration of muscle tissue. The transmembrane proteoglycans syndecans have a wide spectrum of biological functions and are master regulators of tissue homeostasis. They are upregulated and shed (cleaved) as a regulatory mechanism during tissue repair and regeneration. During the last decades, it has become clear that the syndecan family also has critical functions in skeletal muscle growth, however, their potential involvement in WB pathogenesis is unknown. Methods: In this study, we have categorized four groups of WB myopathy in broiler chickens and performed a comprehensive characterization of the molecular and histological profiles of two of them, with a special focus on the role of the syndecans and remodeling of the extracellular matrix (ECM). Results and discussion: Our findings reveal differential expression and shedding of the four syndecan family members and increased matrix metalloproteinase activity. Additionally, we identified alterations in key signaling pathways such as MAPK, AKT, and Wnt. Our work provides novel insights into a deeper understanding of WB pathogenesis and suggests potential therapeutic targets for this condition.

The role of glycosaminoglycans in blood pressure regulation

Essential hypertension (HT) is the global health problem and is a major risk factor for the development of cardiovascular and kidney disease. High salt intake has been associated with HT and impaired kidney sodium excretion is considered to be a major mechanism for the development of HT. Although kidney has a very important role in regulation of BP, this traditional view of BP regulation was challenged by recent findings suggesting that nonosmotic tissue sodium deposition is very important for BP regulation. This new paradigm indicates that sodium can be stored and deposited nonosmotically in the interstitium without water retention and without increased BP. One of the major determinants of this deposition is glycosaminoglycans (GAGs). By binding to GAGs found in the endothelial surface layer (ESL) which contains glycocalyx, sodium is osmotically inactivated and not induce concurrent water retention. Thus, GAGs has important function for homeostatic BP and sodium regulation. In the current review, we summarized the role of GAGs in ESL and BP regulation.

Syndecan-4 as a genetic determinant of the metabolic syndrome

BACKGROUND

Syndecan-4 (SDC4) is a member of the heparan sulfate proteoglycan family of cell-surface receptors. We and others previously reported that variation in the SDC4 gene was associated with several components of the metabolic syndrome, including intra-abdominal fat, fasting glucose and triglyceride levels, and hypertension, in human cohorts. Additionally, we demonstrated that high fat diet (HFD)-induced obese female mice with a Sdc4 genetic deletion had higher visceral adiposity and a worse metabolic profile than control mice. Here, we aimed to first investigate whether the mouse Sdc4 null mutation impacts metabolic phenotypes in a sex- and diet-dependent manner. We then tested whether SDC4 polymorphisms are related to the metabolic syndrome (MetS) in humans.

METHODS

For the mouse experiment, Sdc4-deficient (Sdc4-/-) and wild-type (WT) mice were treated with 14-weeks of low-fat diet (LFD). Body composition, energy balance, and selected metabolic phenotypes were assessed. For the human genetic study, we used logistic regression models to test 11 SDC4 SNPs for association with the MetS and its components in a cohort of 274 (113 with MetS) elderly subjects from southern Italy.

RESULTS

Following the dietary intervention in mice, we observed that the effects of the Sdc4 null mutation on several phenotypes were different from those previously reported in the mice kept on an HFD. Nonetheless, LFD-fed female Sdc4-/- mice, but not males, displayed higher levels of triglycerides and lower insulin sensitivity at fasting than WT mice, as seen earlier in the HFD conditions. In the parallel human study, we found that carriers of SDC4 rs2228384 allele C and rs2072785 allele T had reduced risk of MetS. The opposite was true for carriers of the SDC4 rs1981429 allele G. Additionally, the SNPs were found related to fasting triglyceride levels and triglyceride glucose (TyG) index, a reliable indicator of insulin resistance, with sex-stratified analysis detecting the association of rs1981429 with these phenotypes only in females.

CONCLUSIONS

Altogether, our results suggest that SDC4 is an evolutionary conserved genetic determinant of MetS and that its genetic variation is associated with fasting triglyceride levels in a female-specific manner.

Glycocalyx-Sodium Interaction in Vascular Endothelium

The glycocalyx generally covers almost all cellular surfaces, where it participates in mediating cell-surface interactions with the extracellular matrix as well as with intracellular signaling molecules. The endothelial glycocalyx that covers the luminal surface mediates the interactions of endothelial cells with materials flowing in the circulating blood, including blood cells. Cardiovascular diseases (CVD) remain a major cause of morbidity and mortality around the world. The cardiovascular risk factors start by causing endothelial cell dysfunction associated with destruction or irregular maintenance of the glycocalyx, which may culminate into a full-blown cardiovascular disease. The endothelial glycocalyx plays a crucial role in shielding the cell from excessive exposure and absorption of excessive salt, which can potentially cause damage to the endothelial cells and underlying tissues of the blood vessels. So, in this mini review/commentary, we delineate and provide a concise summary of the various components of the glycocalyx, their interaction with salt, and subsequent involvement in the cardiovascular disease process. We also highlight the major components of the glycocalyx that could be used as disease biomarkers or as drug targets in the management of cardiovascular diseases.

Conformations, interactions and functions of intrinsically disordered syndecans

Syndecans are transmembrane heparan sulfate proteoglycans present on most mammalian cell surfaces. They have a long evolutionary history, a single syndecan gene being expressed in bilaterian invertebrates. Syndecans have attracted interest because of their potential roles in development and disease, including vascular diseases, inflammation and various cancers. Recent structural data is providing important insights into their functions, which are complex, involving both intrinsic signaling through cytoplasmic binding partners and co-operative mechanisms where syndecans form a signaling nexus with other receptors such as integrins and tyrosine kinase growth factor receptors. While the cytoplasmic domain of syndecan-4 has a well-defined dimeric structure, the syndecan ectodomains are intrinsically disordered, which is linked to a capacity to interact with multiple partners. However, it remains to fully establish the impact of glycanation and partner proteins on syndecan core protein conformations. Genetic models indicate that a conserved property of syndecans links the cytoskeleton to calcium channels of the transient receptor potential class, compatible with roles as mechanosensors. In turn, syndecans influence actin cytoskeleton organization to impact motility, adhesion and the extracellular matrix environment. Syndecan clustering with other cell surface receptors into signaling microdomains has relevance to tissue differentiation in development, for example in stem cells, but also in disease where syndecan expression can be markedly up-regulated. Since syndecans have potential as diagnostic and prognostic markers as well as possible targets in some forms of cancer, it remains important to unravel structure/function relationships in the four mammalian syndecans.

Cardiomyocyte-specific overexpression of syndecan-4 in mice results in activation of calcineurin-NFAT signalling and exacerbated cardiac hypertrophy

BACKGROUND

Cardiomyocyte hypertrophy is a hallmark of cardiac dysfunction in patients with aortic stenosis (AS), and can be triggered by left ventricular (LV) pressure overload in mice by aortic banding (AB). Syndecan-4 is a transmembrane heparan sulphate proteoglycan which is found increased in the myocardium of AS patients and AB mice. The role of syndecan-4 in cardiomyocyte hypertrophy is not well understood.

PURPOSE OF THE STUDY

We developed mice with cardiomyocyte-specific overexpression of syndecan-4 (Sdc4-Tg) and subjected these to AB to examine the role of syndecan-4 in hypertrophy and activation of the pro-hypertrophic calcineurin-NFAT signalling pathway.

METHODS AND RESULTS

Sdc4-Tg mice showed exacerbated cardiac remodelling upon AB compared to wild type (WT). At 2-6 weeks post-AB, Sdc4-Tg and WT mice showed similar hypertrophic growth, while at 20 weeks post-AB, exacerbated hypertrophy and dysfunction were evident in Sdc4-Tg mice. After cross-breeding of Sdc4-Tg mice with NFAT-luciferase reporter mice, we found increased NFAT activation in Sdc4-Tg hearts after AB. Immunoprecipitation showed that calcineurin bound to syndecan-4 in Sdc4-Tg hearts. Isolated cardiomyocytes from Sdc4-Tg mice showed alterations in Ca2+ fluxes, suggesting that syndecan-4 regulated Ca2+ levels, and thereby, activating the syndecan-4-calcineurin complex resulting in NFAT activation and hypertrophic growth. Similarly, primary cardiomyocyte cultures from neonatal rats showed increased calcineurin-NFAT-dependent hypertrophic growth upon viral Sdc4 overexpression.

CONCLUSION

Our study of mice with cardiomyocyte-specific overexpression of Sdc4 have revealed that syndecan-4 is important for activation of the Ca2+-dependent calcineurin-NFAT signalling pathway, hypertrophic remodelling and dysfunction in cardiomyocytes in response to pressure overload.

Current Perspectives on Nucleus Pulposus Fibrosis in Disc Degeneration and Repair

A growing body of evidence in humans and animal models indicates an association between intervertebral disc degeneration (IDD) and increased fibrotic elements in the nucleus pulposus (NP). These include enhanced matrix turnover along with the abnormal deposition of collagens and other fibrous matrices, the emergence of fibrosis effector cells, such as macrophages and active fibroblasts, and the upregulation of the fibroinflammatory factors TGF-β1 and IL-1/-13. Studies have suggested a role for NP cells in fibroblastic differentiation through the TGF-βR1-Smad2/3 pathway, inflammatory activation and mechanosensing machineries. Moreover, NP fibrosis is linked to abnormal MMP activity, consistent with the role of matrix proteases in regulating tissue fibrosis. MMP-2 and MMP-12 are the two main profibrogenic markers of myofibroblastic NP cells. This review revisits studies in the literature relevant to NP fibrosis in an attempt to stratify its biochemical features and the molecular identity of fibroblastic cells in the context of IDD. Given the role of fibrosis in tissue healing and diseases, the perspective may provide new insights into the pathomechanism of IDD and its management.

Targeting Syndecan-1: New Opportunities in Cancer Therapy

Syndecan-1 (SDC1, CD138) is one of the heparan sulfate proteoglycans and is essential for maintaining normal cell morphology, interacting with extracellular and intracellular protein repertoire as well as mediating signaling transduction upon environmental stimuli. The critical role of SDC1 in promoting tumorigenesis and metastasis has been increasingly recognized in various cancer types, implying a promising potential of utilizing SDC1 as a novel target for cancer therapy. This review summarizes the current knowledge on SDC1 structure and functions, including its role in tumor biology. We also discuss the highlights and limitations of current SDC1-targeted therapies as well as the obstacles in developing new therapeutic methods, offering our perspective on the future directions to target SDC1 for cancer treatment.

Stiffness of tongue squamous cell carcinoma measured using strain elastography correlates with the amount of collagen fibers in the tumor

OBJECTIVES

To evaluate the stiffness of tongue squamous cell carcinoma (TSCC) using ultrasound strain elastography, a relatively new sonographic imaging technique, and to identify the factors that affect this stiffness.

METHODS

We treated 62 patients diagnosed with muscle invasive TSCC, who were treated at the department of oral surgery of our institution. Each patient's tumor stiffness was semi-quantified according to the ratio of cancer to tongue muscle strain measured using ultrasound strain elastography (the strain ratio). Histopathological diagnosis was made on the same section as the ultrasound strain elastography. We set the following histopathological parameters: cancer cell content in the tumor area (%CCC), collagen fiber content in the tumor area (%CFC), and tumor-infiltrating inflammatory cell content in the stromal compartment (%TIIC). Spearman's rank correlation (rs) was used to assess correlations, and P values < 0.05 were considered significant.

RESULTS

The mean strain ratio was 9.7 ± 9.8. The mean %CCC was 38.4 ± 11.3%, and % CFC was 31.1 ± 7.8%, % TIICs was 19.9 ± 8.9%. Log (strain ratio) by ultrasound strain elastography was positively correlated with %CFC (r_s = 0.379, P = 0.024). %CFC was negatively correlated with %TIICs (r_s =  - 0.318, P = 0.012). No correlations were observed between other clinico-histopathological factors and either strain ratio, or %CFC.

CONCLUSION

The strain ratio of the cancer to the strain of the tongue muscle measured through ultrasound strain elastography positively correlates with the collagen fiber content of the tumor area.

Using Network Pharmacology to Explore the Mechanism of Panax notoginseng in the Treatment of Myocardial Fibrosis

OBJECTIVE

The mechanism of Panax notoginseng in treating myocardial fibrosis (MF) was investigated using network pharmacology.

METHODS

Effective ingredients and potential targets of Panax notoginseng were screened in relevant databases to construct a compound-target network. Targets of MF were then screened to select common targets and construct a protein-protein interaction network. This was followed by Gene Ontology and pathway enrichment analyses. Molecular docking then verified the results of network analysis.

RESULTS

A total of 14 effective ingredients and 119 potential targets for MF were predicted. Quercetin, beta-sitosterol, and gossypetin were speculated to be the main active ingredients. The mechanism of action may be related to AGE-RAGE, proteoglycans, and IL-17 signaling pathways. Five key targets (IL6, ALB, AKT1, TNF, and VEGFA) may be involved in the treatment of MF using Panax notoginseng.

CONCLUSIONS

This study embodies the complex network relationship of multicomponents, multitargets, and multipathways of Panax notoginseng in treating MF and provides a novel method for further research on this herb's mechanism.

The Value of Fetuin-A as a Predictor to Identify Takotsubo Patients at Risk of Cardiovascular Events

INTRODUCTION

Takotsubo cardiomyopathy (TTC) remains a life-threatening disease with the risk of decompensated heart failure and arrhythmias. Valid markers for the prediction of outcome are unavailable. The novel biomarkers fetuin-A, matrix metalloproteinases-2 (MMP-2), myeloperoxidase (MPO), Syndecan-1 and CD40-L show promising results for risk stratification of cardiovascular patients. Nevertheless, clinical implementation has not been investigated in TTC patients.

METHODS

To investigate this issue, we evaluated clinical complications in 51 patients hospitalized for TTC and measured the serum levels of fetuin-A, MPO, MMP-2, Syndecan-1 and CD40-L within 24 h after admission.

RESULTS

Serum levels of Fetuin-A correlated inversely with the risk of cardiac decompensation and all cause complications within the acute phase of TTC. Fetuin-A levels over 190.1 µg/mL (AUC: 0.738, sensitivity 87.5%, specificity: 52.6%) indicate an acute phase of TTC without cardiac decompensation. Despite lower fetuin-A levels in patients with all cause complications, the combined endpoint remained slightly unmet (p = 0.058, AUC: 0.655). Patients with fetuin-A levels over 213.3 µg/mL are at risk of experiencing hemodynamic relevant rhythm disorders (AUC: 0.794; sensitivity: 75.0%, specificity: 79.1%). Other biomarkers failed to reveal a prognostic impact. Pro-BNP and hs troponin levels at admission did not predict adverse cardiac events.

CONCLUSION

Fetuin-A is a promising marker in our study and could be of benefit for the prediction of short-term adverse cardiac events in TTC patients. Therefore, fetuin-A might be of value to evaluate an individual's risk for complications within the acute phase of TTC and to individually choose the time of intensive care and hospitalization.

Understanding the molecular role of syndecan-1 in the regulation of caspase-6 during the progression of cardiac arrhythmia

The role of caspase-6 in heart disease is not well understood, particularly with respect to cardiac arrhythmia. Also, the function of syndecan-1 in the stimulation of inflammation or a regenerative response after cardiac injury is unclear. Leptin receptor-deficient (C57BL/KS-lepr^db/lepr^db) mice were used in the present study. In addition to developing type 2 diabetes, they also develop initial- and end-stage cardiac arrhythmia after 5 and 8 months, respectively. The initial and end-stage arrhythmias were confirmed through progressive variations in the PP intervals observable in electrocardiograms. Histopathological images of the cardiac tissue exhibited scattered and loosened cardiac cells at the initial stage of cardiac arrhythmia, whereas tissue hardness and extensive structural changes in cardiomyocytes were evident at the end stage. At the molecular level, the progressive upregulation of caspase-6 was observed as the cardiac arrhythmia progressed. In the initial stage of arrhythmia, immunohistochemistry revealed that caspase-6 was expressed at the surface of cardiac cells, suggesting that caspase-6 targeted the extracellular matrix, leading to a loosening of the cardiac tissue structure. In the end stage of cardiac arrhythmia, caspase-6 expression was abundant in the cytoplasm, as well as at the cell surface, suggesting that caspase-6 may have cleaved intermediate filaments, paving the way for cellular morphological changes and apoptosis. Notably, syndecan-1 was upregulated 5.8-fold in the initial stage of cardiac arrhythmia, but downregulated at the end stage. Syndecan-1 may restrict the expression of caspase-6 in the initial stage of cardiac arrhythmia, while its downregulation at the end stage may allow destructive changes via caspase-6 overexpression. Furthermore, the knockdown of syndecan-1 using small interfering RNA enhanced the expression of caspase-6 in the cardiac tissue by factors of 1.8 and 1.2 at the initial and end stages of cardiac arrhythmia, respectively, compared with that in non-silenced cardiac tissue. Therefore, it may be concluded that syndecan-1 plays a major role in the regulation of caspase-6 during the pathological stages of cardiac arrhythmia.

Expression of Syndecan-1 in Chronic Liver Diseases: Correlation With Hepatic Fibrosis

BACKGROUND/AIM

The mechanisms underlying the contribution of the heparan sulfate proteoglycan syndecan-1 to liver tissue injury and to crucial biological processes, such as fibrogenesis, remain to be elucidated. Therefore, we investigated the immunohistochemical expression of syndecan-1 in chronic liver diseases (CLDs) and its probable role in hepatic fibrosis.

MATERIALS AND METHODS

Immunohistochemistry was performed on formalin-fixed, paraffin-embedded tissue sections of biopsy material obtained from 128 patients diagnosed with CLDs. The correlation between syndecan-1 expression and the stage of fibrosis was investigated.

RESULTS

According to the severity of fibrosis, cases were categorized into three groups: early fibrosis; intermediate fibrosis; advanced fibrosis. Syndecan-1 expression was significantly enhanced in advanced fibrosis compared to early (p<0.012) and intermediate (p<0.003) fibrosis.

CONCLUSION

In CLDs, syndecan-1 immunohisto-chemical overexpression was found to be positively correlated with the severity of fibrosis, suggesting its probable role in hepatic fibrogenesis.

Multipotential and systemic effects of traumatic brain injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality of people at all ages. Biochemical, cellular and physiological events that occur during primary injury lead to a delayed and long-term secondary damage that can last from hours to years. Secondary brain injury causes tissue damage in the central nervous system and a subsequent strong and rapid inflammatory response that may lead to persistent inflammation. However, this inflammatory response is not limited to the brain. Inflammatory mediators are transferred from damaged brain tissue to the bloodstream and produce a systemic inflammatory response in peripheral organs, including the cardiovascular, pulmonary, gastrointestinal, renal and endocrine systems. Complications of TBI are associated with its multiple and systemic effects that should be considered in the treatment of TBI patients. Therefore, in this review, an attempt was made to examine the systemic effects of TBI in detail. It is hoped that this review will identify the mechanisms of injury and complications of TBI, and open a window for promising treatment in TBI complications.

[Change of serum levels of pentraxin-3 and syndecan-4 in children with chronic heart failure]

OBJECTIVE

To study the change and significance of serum pentraxin-3 (PTX-3) and syndecan-4 in children with chronic heart failure (CHF).

METHODS

A total of 40 children with CHF who were admitted to the Department of Pediatrics of the First Affiliated Hospital of Zhengzhou University were enrolled as the heart failure group, and 30 children who underwent physical examination in the outpatient service during the same period of time were enrolled as the control group. The serum levels of PTX-3, syndecan-4, and N-terminal pro-brain natriuretic peptide (NT-proBNP) were compared between the two groups.

RESULTS

The children with CHF had significant reductions in the serum levels of PTX-3, syndecan-4, and NT-proBNP after treatment. The levels of these markers in children with CHF were significantly higher than the control group before and after treatment (P < 0.05). The CHF children with grade II/III/IV cardiac function had significantly higher serum levels of PTX-3 and syndecan-4 than the control group (P < 0.05). The levels of PTX-3 and syndecan-4 were related to the severity of cardiac function. Compared with the grade II cardiac function group, the grade IV cardiac function group had significant increases in the serum levels of PTX-3 and syndecan-4 (P < 0.05). The serum level of PTX-3 was positively correlated with that of syndecan-4 in children with CHF (r_s=0.999, P < 0.05); the serum level of PTX-3 was positively correlated with NT-proBNP, left ventricular mass index (LVMI), and cardiac function grade (r_s=0.726, 0.736, and 0.934 respectively, P < 0.05) and was negatively correlated with left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) (r_s=-0.852 and -0.767 respectively, P < 0.05); the serum level of syndecan-4 was positively correlated with NT-proBNP, LVMI, and cardiac function grade (r_s=0.733, 0.743, and 0.934 respectively, P < 0.05) and was negatively correlated with LVEF and LVFS (r_s=-0.856 and -0.771 respectively, P < 0.05).

CONCLUSIONS

Serum PTX-3 and syndecan-4 may be involved in the development and progression of ventricular remodeling in children with CHF and may be used as markers for the diagnosis, cardiac function grading, and treatment outcome evaluation of children with heart failure.

Channelling the Force to Reprogram the Matrix: Mechanosensitive Ion Channels in Cardiac Fibroblasts

Cardiac fibroblasts (CF) play a pivotal role in preserving myocardial function and integrity of the heart tissue after injury, but also contribute to future susceptibility to heart failure. CF sense changes to the cardiac environment through chemical and mechanical cues that trigger changes in cellular function. In recent years, mechanosensitive ion channels have been implicated as key modulators of a range of CF functions that are important to fibrotic cardiac remodelling, including cell proliferation, myofibroblast differentiation, extracellular matrix turnover and paracrine signalling. To date, seven mechanosensitive ion channels are known to be functional in CF: the cation non-selective channels TRPC6, TRPM7, TRPV1, TRPV4 and Piezo1, and the potassium-selective channels TREK-1 and KATP. This review will outline current knowledge of these mechanosensitive ion channels in CF, discuss evidence of the mechanosensitivity of each channel, and detail the role that each channel plays in cardiac remodelling. By better understanding the role of mechanosensitive ion channels in CF, it is hoped that therapies may be developed for reducing pathological cardiac remodelling.

Liposomal doxorubicin attenuates cardiotoxicity via induction of interferon-related DNA damage resistance

AIMS

The clinical application of doxorubicin (DOX) is severely compromised by its cardiotoxic effects, which limit the therapeutic index and the cumulative dose. Liposomal encapsulation of DOX (Myocet®) provides a certain protective effect against cardiotoxicity by reducing myocardial drug accumulation. We aimed to evaluate transcriptomic responses to anthracyclines with different cardiotoxicity profiles in a translational large animal model for identifying potential alleviation strategies.

METHODS AND RESULTS

We treated domestic pigs with either DOX, epirubicin (EPI), or liposomal DOX and compared the cardiac, laboratory, and haemodynamic effects with saline-treated animals. Cardiotoxicity was encountered in all groups, reflected by an increase of plasma markers N-terminal pro-brain-natriuretic peptide and Troponin I and an impact on body weight. High morbidity of EPI-treated animals impeded further evaluation. Cardiac magnetic resonance imaging with gadolinium late enhancement and transthoracic echocardiography showed stronger reduction of the left and right ventricular systolic function and stronger myocardial fibrosis in DOX-treated animals than in those treated with the liposomal formulation. Gene expression profiles of the left and right ventricles were analysed by RNA-sequencing and validated by qPCR. Interferon-stimulated genes (ISGs), linked to DNA damage repair and cell survival, were downregulated by DOX, but upregulated by liposomal DOX in both the left and right ventricle. The expression of cardioprotective translocator protein (TSPO) was inhibited by DOX, but not its liposomal formulation. Cardiac fibrosis with activation of collagen was found in all treatment groups.

CONCLUSIONS

All anthracycline-derivatives resulted in transcriptional activation of collagen synthesis and processing. Liposomal packaging of DOX-induced ISGs in association with lower cardiotoxicity, which is of high clinical importance in anticancer treatment. Our study identified potential mechanisms for rational development of strategies to mitigate anthracycline-induced cardiomyopathy.

Syndecan-4 as a Marker of Endothelial Dysfunction in Patients with Resistant Hypertension

(1) Background: Arterial hypertension (HTN) is one of the most relevant cardiovascular risk factors. Nowadays multiple pharmaceutical treatment options exist with novel interventional methods (e.g., baroreflex activation therapy (BAT)) as a last resort to treat patients with resistant HTN. Although pathophysiology behind resistant HTN is still not fully understood. There is evidence that selected biomarkers may be involved in the pathophysiology of HTN. (2) Methods: We investigated serum SDC4-levels in patients suffering from resistant HTN before and 6 months after BAT implantation. We collected 19 blood samples from patients with resistant HTN and blood pressure above target and measured serum SDC4-levels. (3) Results: Our results showed high serum SDC4-levels in patients with resistant HTN as compared to a healthy population. Patients with both, resistant HTN and diabetes mellitus type II, demonstrated higher serum SDC4-levels. β-blockers had lowering effects on serum SDC4-levels, whereas calcium channel blockers were associated with higher levels of serum SDC4. BAT implantation did not lead to a significant difference in serum SDC4-levels after 6 months of therapy. (4) Conclusion: Based on our results we propose SDC4 is elevated in patients suffering from resistant HTN. Thus, SDC4 might be a potential marker for endothelial dysfunction in patients with resistant hypertension.

Sirtuin 1 and endothelial glycocalyx

Sirtuin1 deficiency or reduced activity comprises one of the hallmarks of diseases as diverse as chronic cardiovascular, renal, and metabolic, some malignancies, and infections, as well as aging-associated diseases. In a mouse model of endothelium-limited defect in sirtuin 1 deacetylase activity, we found a dramatic reduction in the volume of endothelial glycocalyx. This was associated with the surge in the levels of one of key scaffolding heparan sulfate proteoglycans of endothelial glycocalyx, syndecan-4, and specifically, its extracellular domain (ectodomain). We found that the defect in endothelial sirtuin 1 deacetylase activity is associated with (a) elevated basal and stimulated levels of superoxide generation (via the FoxO1 over-acetylation mechanism) and (b) increased nuclear translocation of NF-kB (via p65 over-acetylation mechanism). These findings laid the foundation for the proposed novel function of sirtuin 1, namely, the maintenance of endothelial glycocalyx, particularly manifest in conditions associated with sirtuin 1 depletion. In the forthcoming review, we summarize the emerging conceptual framework of the enhanced glycocalyx degradation in the states of defective endothelial sirtuin 1 function, thus explaining a broad footprint of the syndrome of endothelial dysfunction, from impaired flow-induced nitric oxide production, deterrent leukocytes infiltration, increased endothelial permeability, coagulation, and pro-inflammatory changes to development of microvascular rarefaction and progression of an underlying disease.

Assessment of early damage of endometrium after artificial abortion by shear wave elastography

Objectives

This study aimed to investigate the application of shear wave elastography (SWE) in the early damage detection through assessing the endometrial elasticity after artificial abortion.

Methods

A total of nulliparous women (20–30 years) who received ultrasonography in our hospital were recruited between January 2017 and December 2017. These women were divided into normal control group (NC; n = 65), after once artificial abortion group (AOAA; n = 68), after twice artificial abortion group (ATAA; n = 61), and after three times or more (range, 3–6) artificial abortion group (ATTMAA; n = 60). SWE was performed to evaluate the endometrium; Young’s modulus of the endometrium was determined and then the endometrial thickness was measured.

Results

Young’s modulus of the endometrium increased in the order of NC group, AOAA group, ATAA group, and ATTMAA group, and Young’s modulus increased with the increase in the number of artificial abortions (p < 0.05). The endometrial thickness in the ATTMAA group was significantly lower than in the NC group, AOAA group, and ATAA group (p < 0.05), but there was no marked difference among the NC group, AOAA group, and ATAA group (p > 0.05).

Conclusions

SWE increases with increasing number of abortions, which may indicate the damage that is done to the endometrium earlier than measurement of the endometrial thickness do.

Syndecans in Inflammation at a Glance

Syndecans are transmembrane proteoglycans with heparan and chondroitin sulfate chains attached to their extracellular domain. Like many proteoglycans, they interact with a large number of ligands, such as growth factors, adhesion receptors, soluble small molecules, proteinases, and other extracellular matrix proteins to initiate downstream signaling pathways. Syndecans play a major role in inflammation, mainly by regulating leukocyte extravasation and cytokine function. At the same time, syndecans can undergo cytokine mediated changes in their expression levels during inflammation. The function of syndecans during inflammation appears to depend on the stage of inflammation, sulfation of heparan/chondroitin sulfate chains, the rate of ectodomain shedding and the solubility of the ectodomains. From the current literature, it is clear that syndecans are not only involved in the initial recruitment of pro-inflammatory molecules but also in establishing a balanced progression of inflammation. This review will summarize how cell surface and soluble syndecans regulate multiple aspects of inflammation.

Syndecan-4 Protects the Heart From the Profibrotic Effects of Thrombin-Cleaved Osteopontin

Background Pressure overload of the heart occurs in patients with hypertension or valvular stenosis and induces cardiac fibrosis because of excessive production of extracellular matrix by activated cardiac fibroblasts. This initially provides essential mechanical support to the heart, but eventually compromises function. Osteopontin is associated with fibrosis; however, the underlying signaling mechanisms are not well understood. Herein, we examine the effect of thrombin-cleaved osteopontin on fibrosis in the heart and explore the role of syndecan-4 in regulating cleavage of osteopontin. Methods and Results Osteopontin was upregulated and cleaved by thrombin in the pressure-overloaded heart of mice subjected to aortic banding. Cleaved osteopontin was higher in plasma from patients with aortic stenosis receiving crystalloid compared with blood cardioplegia, likely because of less heparin-induced inhibition of thrombin. Cleaved osteopontin and the specific osteopontin peptide sequence RGDSLAYGLR that is exposed after thrombin cleavage both induced collagen production in cardiac fibroblasts. Like osteopontin, the heparan sulfate proteoglycan syndecan-4 was upregulated after aortic banding. Consistent with a heparan sulfate binding domain in the osteopontin cleavage site, syndecan-4 was found to bind to osteopontin in left ventricles and cardiac fibroblasts and protected osteopontin from cleavage by thrombin. Shedding of the extracellular part of syndecan-4 was more prominent at later remodeling phases, at which time levels of cleaved osteopontin were increased. Conclusions Thrombin-cleaved osteopontin induces collagen production by cardiac fibroblasts. Syndecan-4 protects osteopontin from cleavage by thrombin, but this protection is lost when syndecan-4 is shed in later phases of remodeling, contributing to progression of cardiac fibrosis.

Syndecan-1 regulates extracellular matrix expression in keloid fibroblasts via TGF-β1/Smad and MAPK signaling pathways

AIMS

The present study aimed to explore the effect of syndecan-1 on keloid fibroblasts.

MAIN METHODS

Immunohistochemistry and Western blot were employed to assess the expression of syndecan-1. Primary cultured keloid fibroblasts were transfected with syndecan-1 siRNA. The function of syndecan-1 on the proliferation of keloid fibroblasts was investigated through Cell Counting Kit-8 (CCK-8) and flow cytometry. Extracellular matrix, TGF-β1/Smad, and MAPK related proteins were evaluated by Western blot.

KEY FINDINGS

Syndecan-1 was significantly overexpressed in both keloid tissues and fibroblasts. Moreover, the knockdown of syndecan-1 remarkably attenuated the proliferation of keloid fibroblasts and reduced the content of the extracellular matrix. Importantly, syndecan-1 regulates the expression of the extracellular matrix in keloid fibroblasts via TGF-β1/Smad and mitogen-activated protein kinase (MAPK) signaling pathways.

SIGNIFICANCE

The current results revealed a crucial function for syndecan-1 in regulating the expression of extracellular matrix and cell proliferation, thereby designating syndecan-1 as a novel target for keloid.

Calcium in Cell-Extracellular Matrix Interactions

In multicellular organisms, the cells are surrounded by persistent, dynamic extracellular matrix (ECM), the largest calcium reservoir in animals. ECM regulates several aspects of cell behavior including cell migration and adhesion, survival, gene expression and differentiation, thus playing a significant role in health and disease. Calcium is reported to be important in the assembly of ECM, where it binds to many ECM proteins. While serving as a calcium reservoir, ECM macromolecules can directly interact with cell surface receptors resulting in calcium transport across the membrane. This chapter mainly focusses on the role of cell-ECM interactions in cellular calcium regulation and how calcium itself mediates these interactions.

Genetic Deletion of Syndecan-4 Alters Body Composition, Metabolic Phenotypes, and the Function of Metabolic Tissues in Female Mice Fed A High-Fat Diet

Syndecans are transmembrane proteoglycans that, like integrins, bind to components of the extracellular matrix. Previously, we showed significant associations of genetic variants in the Syndecan-4 (SDC4) gene with intra-abdominal fat, fasting plasma glucose levels, and insulin sensitivity index in children, and with fasting serum triglyceride levels in healthy elderly subjects. An independent study also reported a correlation between SDC4 and the risk of coronary artery disease in middle-aged patients. Here, we investigated whether deletion of Sdc4 promotes metabolic derangements associated with diet-induced obesity by feeding homozygous male and female Sdc4-deficient (Sdc4^-/-) mice and their age-matched wild-type (WT) mice a high-fat diet (HFD). We found that WT and Sdc4^-/- mice gained similar weight. However, while no differences were observed in males, HFD-fed female Sdc4^-/- mice exhibited a higher percentage of body fat mass than controls and displayed increased levels of plasma total cholesterol, triglyceride, and glucose, as well as reduced whole-body insulin sensitivity. Additionally, they had an increased adipocyte size and macrophage infiltration in the visceral adipose tissue, and higher triglyceride and fatty acid synthase levels in the liver. Together with our previous human genetic findings, these results provide evidence of an evolutionarily conserved role of SDC4 in adiposity and its complications.

Syndecan-1: A Review on Its Role in Heart Failure and Chronic Liver Disease Patients' Assessment

The close connection and interaction between the cardiac and the liver functions are well-known, as cirrhotic cardiomyopathy is an important clinical entity which best describes the mutual pathogenical influence between these two organs. Due to the fact that cardiac dysfunction in patients with chronic hepatic disorders is oligosymptomatic or even asymptomatic, an early diagnosis represents a challenge for every physician. Syndecan-1—a transmembrane proteoglycan that exerts its functions mainly via its heparane sulfate chains—is a very promising biomarker, correlated not only with the degree of cardiac fibrosis but also with the severity of liver fibrosis. Many studies highlighted its role in the development of cardiac fibrosis or atherogenesis, being significantly correlated with the activity of angiotensin II. Multiple evidence revealed that syndecan-1 is also associated with tissue injury and may regulate inflammatory and regenerative responses, being considered a protective molecule that limits the inflammation and reduces cardiac remodelling and dysfunction after a myocardial infarction. Syndecan-1 may also be used as a reliable biomarker for the noninvasive assessment of liver fibrosis. Under various fibrogenetic conditions, shedding of syndecan's extracellular domain took place, becoming a soluble form that binds different growth factors and inhibits further fibrosis. This complex molecule is also involved in the lipid metabolism, by altering the clearance of cholesterol particles, and in chronic hepatitis, by enhancing the viral invasion of hepatocytes. Due to the growing interest in this biomarker, multiple studies aimed at revealing syndecan-1's potential benefits in the diagnosis and prognosis assessment in patients with heart failure or chronic liver disorders. In this review, we review the mechanisms by which syndecan-1 exerts its effects and the possible perspectives opened by its use as a dual cardio-hepatic biomarker.

Platelet-Rich Plasma and Bone Marrow-Derived Mesenchymal Stromal Cells Prevent TGF-β1-Induced Myofibroblast Generation but Are Not Synergistic when Combined: Morphological in vitro Analysis

The persistence of activated myofibroblasts is a hallmark of fibrosis of many organs. Thus, the modulation of the generation/functionality of these cells may represent a strategical anti-fibrotic therapeutic option. Bone marrow-derived mesenchymal stromal cell (MSC)-based therapy has shown promising clues, but some criticisms still limit the clinical use of these cells, including the need to avoid xenogeneic compound contamination for ex vivo cell amplification and the identification of appropriate growth factors acting as a pre-conditioning agent and/or cell delivery vehicle during transplantation, thus enabling the improvement of cell survival in the host tissue microenvironment. Many studies have demonstrated the ability of platelet-rich plasma (PRP), a source of many biologically active molecules, to positively influence MSC proliferation, survival, and functionality, as well as its anti-fibrotic potential. Here we investigated the effects of PRP, murine and human bone marrow-derived MSCs, and of the combined treatment PRP/MSCs on in vitro differentiation of murine NIH/3T3 and human HDFα fibroblasts to myofibroblasts induced by transforming growth factor (TGF)-β1, a well-known pro-fibrotic agent. The myofibroblastic phenotype was evaluated morphologically (cell shape and actin cytoskeleton assembly) and immunocytochemically (vinculin-rich focal adhesion clustering, α-smooth muscle actin and type-1 collagen expression). We found that PRP and MSCs, both as single treatments and in combination, were able to prevent the TGF-β1-induced fibroblast-myofibroblast transition. Unexpectedly, the combination PRP/MSCs had no synergistic effects. In conclusion, within the limitations related to an in vitro experimentation, our study may contribute to providing an experimental background for supporting the anti-fibrotic potential of the combination PRP/MSCs which, once translated "from bench to bedside," could potentially offer advantages over the single treatments.

The extracellular matrix proteoglycan lumican improves survival and counteracts cardiac dilatation and failure in mice subjected to pressure overload

Left ventricular (LV) dilatation is a key step in transition to heart failure (HF) in response to pressure overload. Cardiac extracellular matrix (ECM) contains fibrillar collagens and proteoglycans, important for maintaining tissue integrity. Alterations in collagen production and cross-linking are associated with cardiac LV dilatation and HF. Lumican (LUM) is a collagen binding proteoglycan with increased expression in hearts of patients and mice with HF, however, its role in cardiac function remains poorly understood. To examine the role of LUM in pressure overload induced cardiac remodeling, we subjected LUM knock-out (LUMKO) mice to aortic banding (AB) and treated cultured cardiac fibroblasts (CFB) with LUM. LUMKO mice exhibited increased mortality 1-14 days post-AB. Echocardiography revealed increased LV dilatation, altered hypertrophic remodeling and exacerbated contractile dysfunction in surviving LUMKO 1-10w post-AB. LUMKO hearts showed reduced collagen expression and cross-linking post-AB. Transcriptional profiling of LUMKO hearts by RNA sequencing revealed 714 differentially expressed transcripts, with enrichment of cardiotoxicity, ECM and inflammatory pathways. CFB treated with LUM showed increased mRNAs for markers of myofibroblast differentiation, proliferation and expression of ECM molecules important for fibrosis, including collagens and collagen cross-linking enzyme lysyl oxidase. In conclusion, we report the novel finding that lack of LUM attenuates collagen cross-linking in the pressure-overloaded heart, leading to increased mortality, dilatation and contractile dysfunction in mice.

The extracellular matrix as a multitasking player in disease

Extracellular matrices (ECMs) are highly specialized and dynamic three-dimensional (3D) scaffolds into which cells reside in tissues. ECM is composed of a variety of fibrillar components, such as collagens, fibronectin, and elastin, and non-fibrillar molecules as proteoglycans, hyaluronan, and glycoproteins including matricellular proteins. These macromolecular components are interconnected forming complex networks that actively communicate with cells through binding to cell surface receptors and/or matrix effectors. ECMs exert diverse roles, either providing tissues with structural integrity and mechanical properties essential for tissue functions or regulating cell phenotype and functions to maintain tissue homeostasis. ECM molecular composition and structure vary among tissues, and is markedly modified during normal tissue repair as well as during the progression of various diseases. Actually, abnormal ECM remodeling occurring in pathologic circumstances drives disease progression by regulating cell-matrix interactions. The importance of matrix molecules to normal tissue functions is also highlighted by mutations in matrix genes that give rise to genetic disorders with diverse clinical phenotypes. In this review, we present critical and emerging issues related to matrix assembly in tissues and the multitasking roles for ECM in diseases such as osteoarthritis, fibrosis, cancer, and genetic diseases. The mechanisms underlying the various matrix-based diseases are also discussed. Research focused on the highly dynamic 3D ECM networks will help to discover matrix-related causative abnormalities of diseases as well as novel diagnostic tools and therapeutic targets.

Syndecan-1 as an independent risk factor for the incidence of adverse cardiovascular events in patients having stage C and D heart failure with non-ischemic dilated cardiomyopathy

BACKGROUND

Patients with heart failure (HF) having non-ischemic dilated cardiomyopathy (DCM) have high mortality rates. Syndecan-1 is reportedly associated with cardiac fibrosis and inflammation. This study explored the role of syndecan-1 in patients with non-ischemic DCM.

METHODS

Patients with HF were prospectively enrolled. Comprehensive clinical and biochemical analysis were performed. All patients were followed up for composite of major adverse cardiac events of cardiovascular death and cardiac transplantation.

RESULTS

We measured syndecan-1 levels in 96 patients with HF and non-ischemic DCM. The primary outcome was the 3-year major adverse cardiac events. Approximately, 71% of patients were men with mean age and LVEF of 51.08 ± 13.28 years and 31.90 ± 8.85%, respectively. Median syndecan-1 levels were 456.57 pg/ml (interquartile range, 244.93-1181.26 pg/ml). Multivariate Cox regression analysis for Model I (adjusted for age, sex) and II (adjusted for traditional confounding factors) revealed that baseline syndecan-1 remained an independent predictor of composite endpoint events (Model I HR, 1.10/100 pg/ml increase in syndecan-1 level, 95% CI, 1.04-1.16, P = 0.0006; Model II HR, 1.10/100 pg/ml increase in syndecan-1 level, 95% CI, 1.03-1.18, P = 0.0029). Kaplan Meier analysis based on syndecan-1 tertiles revealed that the top tertile was associated with reduced survival compare to that in middle and bottom tertiles (P < 0.0001). Multivariate logistic regression analyses showed a positive correlation between syndecan-1 level and fibrosis and inflammatory markers.

CONCLUSION

In patients with HF and non-ischemic DCM, the syndecan-1 level is important in the assessment of risk of adverse clinical outcome, and syndecan-1 level is correlated with fibrosis and inflammatory biomarkers.

Spotlight on the Transglutaminase 2-Heparan Sulfate Interaction

Heparan sulfate proteoglycans (HSPGs), syndecan-4 (Sdc4) especially, have been suggested as potential partners of transglutaminase-2 (TG2) in kidney and cardiac fibrosis, metastatic cancer, neurodegeneration and coeliac disease. The proposed role for HSPGs in the trafficking of TG2 at the cell surface and in the extracellular matrix (ECM) has been linked to the fibrogenic action of TG2 in experimental models of kidney fibrosis. As the TG2-HSPG interaction is largely mediated by the heparan sulfate (HS) chains of proteoglycans, in the past few years a number of studies have investigated the affinity of TG2 for HS, and the TG2 heparin binding site has been mapped with alternative outlooks. In this review, we aim to provide a compendium of the main literature available on the interaction of TG2 with HS, with reference to the pathological processes in which extracellular TG2 plays a role.

Immune Response Mediates Cardiac Dysfunction after Traumatic Brain Injury

Cardiovascular complications are common after traumatic brain injury (TBI) and are associated with increased morbidity and mortality. In this study, we investigated the possible role of the immune system in mediating cardiac dysfunction post-TBI in mice. Adult male C57BL/6J mice were subjected to a TBI model of controlled cortical impact (CCI) with or without splenectomy (n = 20/group). Splenectomy was performed immediately prior to induction of TBI. Cardiac function was measured using echocardiography prior to and after TBI. Neurological and cognitive functional tests and flow cytometry and immunostaining were performed. TBI mice exhibited significant cardiac dysfunction identified by decreased left ventricular ejection fraction and fractional shortening at 3 and 30 days post-TBI. In addition, these mice exhibited significantly increased cardiomyocyte apoptosis, inflammation, and oxidative stress at 3 and 30 days post-TBI, as well as cardiac hypertrophy and fibrosis and ventricular dilatation at 30 days after TBI. TBI mice subjected to splenectomy showed significantly improved cardiac function, and decreased cardiac fibrosis, oxidative stress, cardiomyocyte apoptosis, and infiltration of immune cells and inflammatory factor expression in the heart compared with TBI control mice. TBI mice exhibited severe neurological and cognitive function deficits. However, splenectomy did not improve neurological and cognitive functional outcome after TBI compared with the TBI control group. TBI induces immune cell infiltration and inflammatory factor expression in the heart as well as cardiac dysfunction. Splenectomy decreases heart inflammation and improves cardiac function after TBI. Immune response may contribute to TBI-induced cardiac dysfunction.

The extracellular matrix proteoglycan fibromodulin is upregulated in clinical and experimental heart failure and affects cardiac remodeling

Pressure overload of the heart leads to cardiac remodeling that may progress into heart failure, a common, morbid and mortal condition. Increased mechanistic insight into remodeling is instrumental for development of novel heart failure treatment. Cardiac remodeling comprises cardiomyocyte hypertrophic growth, extracellular matrix alterations including fibrosis, and inflammation. Fibromodulin is a small leucine-rich proteoglycan that regulates collagen fibrillogenesis. Fibromodulin is expressed in the cardiac extracellular matrix, however its role in the heart remains largely unknown. We investigated fibromodulin levels in myocardial biopsies from heart failure patients and mice, subjected fibromodulin knock-out (FMOD-KO) mice to pressure overload by aortic banding, and overexpressed fibromodulin in cultured cardiomyocytes and cardiac fibroblasts using adenovirus. Fibromodulin was 3-10-fold upregulated in hearts of heart failure patients and mice. Both cardiomyocytes and cardiac fibroblasts expressed fibromodulin, and its expression was increased by pro-inflammatory stimuli. Without stress, FMOD-KO mice showed no cardiac phenotype. Upon aortic banding, left ventricles of FMOD-KO mice developed mildly exacerbated hypertrophic remodeling compared to wild-type mice, with increased cardiomyocyte size and altered infiltration of leukocytes. There were no differences in mortality, left ventricle dilatation, dysfunction or expression of heart failure markers. Although collagen amount and cross-linking were comparable in FMOD-KO and wild-type, overexpression of fibromodulin in cardiac fibroblasts in vitro decreased their migratory capacity and expression of fibrosis-associated molecules, i.e. the collagen-cross linking enzyme lysyl oxidase, transglutaminase 2 and periostin. In conclusion, despite a robust fibromodulin upregulation in clinical and experimental heart failure, FMOD-KO mice showed a relatively mild hypertrophic phenotype. In cultured cardiac fibroblasts, fibromodulin has anti-fibrotic effects.

Proteoglycan Isolation and Analysis

Proteoglycans can be difficult molecules to isolate and analyze due to large mass, charge, and tendency to aggregate or form macromolecular complexes. This unit describes detailed methods for purification of matrix, cell surface, and cytoskeleton-linked proteoglycans. Methods for analysis of glycoaminoglycan size and type and of core protein species are described. © 2018 by John Wiley & Sons, Inc.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

Galectin-3 Activation and Inhibition in Heart Failure and Cardiovascular Disease: An Update

Galectin-3 is a versatile protein orchestrating several physiological and pathophysiological processes in the human body. In the last decade, considerable interest in galectin-3 has emerged because of its potential role as a biotarget. Galectin-3 is differentially expressed depending on the tissue type, however its expression can be induced under conditions of tissue injury or stress. Galectin-3 overexpression and secretion is associated with several diseases and is extensively studied in the context of fibrosis, heart failure, atherosclerosis and diabetes mellitus. Monomeric (extracellular) galectin-3 usually undergoes further "activation" which significantly broadens the spectrum of biological activity mainly by modifying its carbohydrate-binding properties. Self-interactions of this protein appear to play a crucial role in regulating the extracellular activities of this protein, however there is limited and controversial data on the mechanisms involved. We therefore summarize (recent) literature in this area and describe galectin-3 from a binding perspective providing novel insights into mechanisms by which galectin-3 is known to be "activated" and how such activation may be regulated in pathophysiological scenarios.

Symptom Onset in Aortic Stenosis: Relation to Sex Differences in Left Ventricular Remodeling

OBJECTIVES

The aim of this study was to establish sex differences in remodeling and outcome in aortic stenosis (AS) and their associations with biomarkers of myocardial fibrosis.

BACKGROUND

The remodeling response and timing of symptoms is highly variable in AS, and sex plays an important role.

METHODS

A total of 174 patients (133 men, mean age 66.2 ± 13.3 years) with asymptomatic moderate to severe AS underwent comprehensive stress cardiac magnetic resonance imaging, transthoracic echocardiography, and biomarker analysis (matrix metalloproteinase [MMP]-2, -3, -7, -8, and -9; tissue inhibitor matrix metalloproteinases-1 and -4; syndecan-1 and -4; and N-terminal pro-B-type natriuretic peptide), and were followed up at 6-month intervals. A primary endpoint was a composite of typical AS symptoms necessitating referral for aortic valve replacement, cardiovascular death, or major adverse cardiovascular events.

RESULTS

For a similar severity of AS, male patients demonstrated higher indexed left ventricular (LV) volumes and mass, more concentric remodeling (higher LV mass/volume), a trend to more late gadolinium enhancement (present in 51.1% men vs. 34.1% women; p = 0.057), and higher extracellular volume index than female patients (13.27 [interquartile range (IQR): 11.5 to 17.0] vs. 11.53 [IQR: 10.5 to 13.5] ml/m², p = 0.017), with worse systolic and diastolic function and higher MMP-3 and syndecan-4 levels, whereas female patients had higher septal E/e'. Male sex was independently associated with indexed LV mass (β = 13.32 [IQR: 9.59 to 17.05]; p < 0.001). During median follow-up of 374 (IQR: 351 to 498) days, a primary outcome, driven by spontaneous symptom onset, occurred in 21.8% of male and 43.9% of female patients (relative risk: 0.50 [95% confidence interval: 0.31 to 0.80]; p = 0.004). Measures of AS severity were associated with the primary outcome in both sexes, whereas N-terminal pro-B-type natriuretic peptide, MMP-3, and mass/volume were only associated in men.

CONCLUSIONS

In AS, women tolerate pressure overload with less concentric remodeling and myocardial fibrosis but are more likely to develop symptoms. This may be related to higher wall stress and filling pressures in women.

Endothelial dysfunction is a superinducer of syndecan-4: fibrogenic role of its ectodomain

Syndecan-4 (Synd4) is a member of the membrane-spanning, glycocalyx-forming proteoglycan family. It has been suggested that Synd4 participates in renal fibrosis. We compared wild-type and fibrosis-prone endothelial sirtuin 1-deficient (Sirt1^endo-/-) mice, the latter being a model of global endothelial dysfunction. We performed mass spectrometry analysis, which revealed that Synd4 was highly enriched in the secretome of renal microvascular endothelial cells obtained from Sirt1^endo-/- mice upon stimulation with transforming growth factor-β₁; notably, all detectable peptides were confined to the ectodomain of Synd4. Elevated Synd4 was due to enhanced NF-κB signaling in Sirt1^endo-/- mice, while its shedding occurred as a result of oxidative stress in Sirt1 deficiency. Synd4 expression was significantly enhanced after unilateral ureteral obstruction compared with contralateral kidneys. Furthermore, hyperplasia of renal myofibroblasts accompanied by microvascular rarefaction and overexpression of Synd4 were detected in Sirt1^endo-/- mice. The ectodomain of Synd4 acted as a chemoattractant for monocytes with higher levels of macrophages and higher expression levels of Synd4 in the extracellular matrix of Sirt1^endo-/- mice. In vitro, ectodomain application resulted in generation of myofibroblasts from cultured renal fibroblasts, while in vivo, subcapsular injection of ectodomain increased interstitial fibrosis. Moreover, the endothelial glycocalyx was reduced in Sirt1^endo-/- mice, highlighting the induction of Synd4 occurring in parallel with the depletion of its intact form and accumulation of its ectodomain in Sirt1^endo-/- mice. On the basis of our experimental results, we propose that it is the Synd4 ectodomain per se that is partially responsible for fibrosis in unilateral ureteral obstruction, especially when it is combined with endothelial dysfunction. NEW & NOTEWORTHY Our findings suggest that endothelial dysfunction induces the expression of syndecan-4 via activation of the NF-κB pathway. Furthermore, we show that syndecan-4 is shed to a greater amount because of increased oxidative stress in dysfunctional endothelial cells and that the release of the syndecan-4 ectodomain leads to tubulointerstitial fibrosis.

From Inflammation to Fibrosis-Molecular and Cellular Mechanisms of Myocardial Tissue Remodelling and Perspectives on Differential Treatment Opportunities

PURPOSE OF REVIEW

In this review, we highlight the most important cellular and molecular mechanisms that contribute to cardiac inflammation and fibrosis. We also discuss the interplay between inflammation and fibrosis in various precursors of heart failure (HF) and how such mechanisms can contribute to myocardial tissue remodelling and development of HF.

RECENT FINDINGS

Recently, many research articles attempt to elucidate different aspects of the interplay between inflammation and fibrosis. Cardiac inflammation and fibrosis are major pathophysiological mechanisms operating in the failing heart, regardless of HF aetiology. Currently, novel therapeutic options are available or are being developed to treat HF and these are discussed in this review. A progressive disease needs an aggressive management; however, existing therapies against HF are insufficient. There is a dynamic interplay between inflammation and fibrosis in various precursors of HF such as myocardial infarction (MI), myocarditis and hypertension, and also in HF itself. There is an urgent need to identify novel therapeutic targets and develop advanced therapeutic strategies to combat the syndrome of HF. Understanding and describing the elements of the inflammatory and fibrotic pathways are essential, and specific drugs that target these pathways need to be evaluated.

The Soft- and Hard-Heartedness of Cardiac Fibroblasts: Mechanotransduction Signaling Pathways in Fibrosis of the Heart

Cardiac fibrosis, the excessive accumulation of extracellular matrix (ECM), remains an unresolved problem in most forms of heart disease. In order to be successful in preventing, attenuating or reversing cardiac fibrosis, it is essential to understand the processes leading to ECM production and accumulation. Cardiac fibroblasts are the main producers of cardiac ECM, and harbor great phenotypic plasticity. They are activated by the disease-associated changes in mechanical properties of the heart, including stretch and increased tissue stiffness. Despite much remaining unknown, an interesting body of evidence exists on how mechanical forces are translated into transcriptional responses important for determination of fibroblast phenotype and production of ECM constituents. Such mechanotransduction can occur at multiple cellular locations including the plasma membrane, cytoskeleton and nucleus. Moreover, the ECM functions as a reservoir of pro-fibrotic signaling molecules that can be released upon mechanical stress. We here review the current status of knowledge of mechanotransduction signaling pathways in cardiac fibroblasts that culminate in pro-fibrotic gene expression.

Mechanical regulation of cardiac fibroblast profibrotic phenotypes

Cardiac fibroblasts are essential for beneficial myocardial healing but also cause detrimental adverse remodeling following myocardial infarction. The mechanical properties of the infarcted myocardium and border regions display temporal and spatial characteristics that regulate different aspects of the profibrotic cardiac fibroblast phenotypes.

Cardiac fibrosis is a serious condition currently lacking effective treatments. It occurs as a result of cardiac fibroblast (CFB) activation and differentiation into myofibroblasts, characterized by proliferation, extracellular matrix (ECM) production and stiffening, and contraction due to the expression of smooth muscle α-actin. The mechanical properties of myocardium change regionally and over time after myocardial infarction (MI). Although mechanical cues are known to activate CFBs, it is unclear which specific mechanical stimuli regulate which specific phenotypic trait; thus we investigated these relationships using three in vitro models of CFB mechanical activation and found that 1) paracrine signaling from stretched cardiomyocytes induces CFB proliferation under mechanical conditions similar to those of the infarct border region; 2) direct stretch of CFBs mimicking the mechanical environment of the infarct region induces a synthetic phenotype with elevated ECM production; and 3) progressive matrix stiffening, modeling the mechanical effects of infarct scar maturation, causes smooth muscle α-actin fiber formation, up-regulation of collagen I, and down-regulation of collagen III. These findings suggest that myocyte stretch, fibroblast stretch, and matrix stiffening following MI may separately regulate different profibrotic traits of activated CFBs.

Dissecting the Role of the Extracellular Matrix in Heart Disease: Lessons from the Drosophila Genetic Model

The extracellular matrix (ECM) is a dynamic scaffold within organs and tissues that enables cell morphogenesis and provides structural support. Changes in the composition and organisation of the cardiac ECM are required for normal development. Congenital and age-related cardiac diseases can arise from mis-regulation of structural ECM proteins (Collagen, Laminin) or their receptors (Integrin). Key regulators of ECM turnover include matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of matrix metalloproteinases (TIMPs). MMP expression is increased in mice, pigs, and dogs with cardiomyopathy. The complexity and longevity of vertebrate animals makes a short-lived, genetically tractable model organism, such as Drosophila melanogaster, an attractive candidate for study. We survey ECM macromolecules and their role in heart development and growth, which are conserved between Drosophila and vertebrates, with focus upon the consequences of altered expression or distribution. The Drosophila heart resembles that of vertebrates during early development, and is amenable to in vivo analysis. Experimental manipulation of gene function in a tissue- or temporally-regulated manner can reveal the function of adhesion or ECM genes in the heart. Perturbation of the function of ECM proteins, or of the MMPs that facilitate ECM remodelling, induces cardiomyopathies in Drosophila, including cardiodilation, arrhythmia, and cardia bifida, that provide mechanistic insight into cardiac disease in mammals.

Effect of QSKL on MAPK and RhoA Pathways in a Rat Model of Heart Failure

Qishenkeli (QSKL) is one of the Chinese medicine formulae for treating heart failure and has been shown to have an antifibrotic effect. However, the mechanism of its therapeutic effects remains unclear. In this study, we aimed to explore whether QSKL could exert an antifibrotic effect by attenuating ras homolog family member A (RhoA) and mitogen activated protein kinase (MAPK) pathways. Rats were randomly divided into sham group, model group, QSKL group, and positive control group. Heart failure was induced by ligation of the left ventricle anterior descending artery. Cardiac functions were measured by echocardiography and collagen deposition was assessed by Masson staining. Expressions of the key molecules involved in the RhoA and MAPK pathways were also measured. Twenty-one days after surgery, cardiac functions were severely impaired and collagen deposition was remarkable, while QSKL treatment could improve heart functions and alleviate collagen deposition. Further results demonstrated that the effects may be mediated by suppressing expressions of extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK). Moreover, expressions of RhoA, Rho-associated protein kinase 1/2 (ROCK1/2), and phosphorylated myosin light chain (p-MLC) were also downregulated by QSKL compared with the model group. The cardioprotective mechanism of QSKL on heart failure is probably mediated by regulating both the MAPK and RhoA signaling pathways.

Conformational and thermal characterization of left ventricle remodeling post-myocardial infarction

Adverse cardiac remodeling after myocardial infarction (MI) causes impaired ventricular function and heart failure. Histopathological characterization is commonly used to detect the location, size and shape of MI sites. However, the information about chemical composition, physical structure and molecular mobility of peri- and infarct zones post-MI is rather limited. The main objective of this work was to explore the spatiotemporal biochemical and biophysical alterations of key cardiac components post-MI. The FTIR spectra of healthy and remote myocardial tissue shows amides A, I, II and III associated with proteins in freeze-died tissue as major absorptions bands. In infarcted myocardium, the spectrum of these main absorptions was deeply altered. FITR evidenced an increase of the amide A band and the distinct feature of the collagen specific absorption band at 1338cm^-1 in the infarct area at 21days post-MI. At 21days post-MI, it also appears an important shift of amide I from 1646cm^-1 to 1637cm^-1 that suggests the predominance of the triple helical conformation in the proteins. The new spectra bands also indicate an increase in proteoglycans, residues of carbohydrates in proteins and polysaccharides in ischemic areas. Thermal analysis indicates a deep increase of unfreezable water/freezable water in peri- and infarcted tissues. In infarcted tissue is evidenced the impairment of myofibrillar proteins thermal profile and the emergence of a new structure. In conclusion, our results indicate a profound evolution of protein secondary structures in association with collagen deposition and reorganization of water involved in the scar maturation of peri- and infarct zones post-MI.