Thrombospondin-4, tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14: novel extracellular matrix modulating factors in cardiac remodelling

Extracellular Matrix Interactome in Modulating Vascular Homeostasis and Remodeling

The ECM (extracellular matrix) is a major component of the vascular microenvironment that modulates vascular homeostasis. ECM proteins include collagens, elastin, noncollagen glycoproteins, and proteoglycans/glycosaminoglycans. ECM proteins form complex matrix structures, such as the basal lamina and collagen and elastin fibers, through direct interactions or lysyl oxidase-mediated cross-linking. Moreover, ECM proteins directly interact with cell surface receptors or extracellular secreted molecules, exerting matricellular and matricrine modulation, respectively. In addition, extracellular proteases degrade or cleave matrix proteins, thereby contributing to ECM turnover. These interactions constitute the ECM interactome network, which is essential for maintaining vascular homeostasis and preventing pathological vascular remodeling. The current review mainly focuses on endogenous matrix proteins in blood vessels and discusses the interaction of these matrix proteins with other ECM proteins, cell surface receptors, cytokines, complement and coagulation factors, and their potential roles in maintaining vascular homeostasis and preventing pathological remodeling.

The Roles of Type 2 Cytotoxic T Cells in Inflammation, Tissue Remodeling, and Prostaglandin (PG) D2 Production Are Attenuated by PGD2 Receptor 2 Antagonism

Multiple proinflammatory effects of Tc2 cells are inhibited by DP2 antagonism.

Tissue-remodeling functions of Tc2 cells are attenuated by DP2 antagonism.

Autocrine/paracrine PGD₂ production in Tc2 cells is reduced by DP2 antagonism.

Human type 2 cytotoxic T (Tc2) cells are enriched in severe eosinophilic asthma and can contribute to airway eosinophilia. PGD₂ and its receptor PGD₂ receptor 2 (DP2) play important roles in Tc2 cell activation, including migration, cytokine production, and survival. In this study, we revealed novel, to our knowledge, functions of the PGD₂/DP2 axis in Tc2 cells to induce tissue-remodeling effects and IgE-independent PGD₂ autocrine production. PGD₂ upregulated the expression of tissue-remodeling genes in Tc2 cells that enhanced the fibroblast proliferation and protein production required for tissue repair and myofibroblast differentiation. PGD₂ stimulated Tc2 cells to produce PGD₂ using the routine PGD₂ synthesis pathway, which also contributed to TCR-dependent PGD₂ production in Tc2 cells. Using fevipiprant, a specific DP2 antagonist, we demonstrated that competitive inhibition of DP2 not only completely blocked the cell migration, adhesion, proinflammatory cytokine production, and survival of Tc2 cells triggered by PGD₂ but also attenuated the tissue-remodeling effects and autocrine/paracrine PGD₂ production in Tc2 induced by PGD₂ and other stimulators. These findings further confirmed the anti-inflammatory effect of fevipiprant and provided a better understanding of the role of Tc2 cells in the pathogenesis of asthma.

Serum soluble TWEAK levels in severe traumatic brain injury and its prognostic significance

BACKGROUND

Severe traumatic brain injury (sTBI) is characterized by a high mortality. Tumor necrosis factor-like weak inducer of apoptosis (TWEAK) participates in inflammation. We determined serum soluble TWEAK (sTWEAK) levels with respect to its prognostic ability.

METHODS

This was a single-center prospective, observational study that was performed from December 2014 to December 2017. A total of 114 sTBI patients who met the inclusion criteria and 114 randomly selected healthy controls were included in the study. Serum sTWEAK levels were gauged. Patients were followed-up until death or completion of 6 months. Poor outcome was referred to as Glasgow outcome scale score of 1-3.

RESULTS

In comparison with controls, patients displayed predominantly higher serum sTWEAK levels. Serum sTWEAK levels were strongly correlated with Glasgow coma scale scores and serum C-reactive protein levels. 32 patients (28.1%) died and 60 patients (52.6%) suffered from a poor outcome. Receiver operating characteristic curve analysis clearly showed that serum sTWEAK levels had substantially high predictive performance for 6-month mortality and poor outcome. Serum sTWEAK emerged as an independent predictor for 6-month mortality, overall survival and poor outcome.

CONCLUSIONS

Raised serum sTWEAK levels are closely related to increasing inflammatory response, elevated trauma severity and worse clinical outcome after sTBI.

Thrombospondin-4 mediates TGF-β-induced angiogenesis

TGF-β is a multifunctional cytokine affecting many cell types and implicated in tissue remodeling processes. Due to its many functions and cell-specific effects, the consequences of TGF-β signaling are process-and stage-dependent, and it is not uncommon that TGF-β exerts distinct and sometimes opposing effects on a disease progression depending on the stage and on the pathological changes associated with the stage. The mechanisms underlying cell- and process-specific effects of TGF-β are poorly understood.

We are describing a novel pathway that mediates induction of angiogenesis in response to TGF-β1. We found that in endothelial cells (EC) TSP-4, a secreted extracellular matrix (ECM) protein is upregulated in response to TGF-β1 and mediates the effects of TGF-β1 on angiogenesis.

Upregulation of TSP-4 does not require the synthesis of new protein, is not caused by decreased secretion of TSP-4, and is mediated by activation of SMAD3. Using Thbs4^−/− mice and TSP-4 shRNA, we found that TSP-4 mediated pro-angiogenic functions on cultured EC and angiogenesis in vivo in response to TGF-β1. We observed ~ 3-fold increases in tumor mass and levels of angiogenesis markers in animals injected with TGF-β1, and these effects did not occur in Thbs4^−/− animals. Injections of an inhibitor of TGF-β1 signaling SB431542 also decreased the weights of tumors and cancer angiogenesis.

Our results from in vivo angiogenesis models and cultured EC document that TSP-4 mediates upregulation of angiogenesis by TGF-β1. Upregulation of pro-angiogenic TSP-4 and selective effects of TSP-4 on EC may contribute to stimulation of tumor growth by TGF-β despite the inhibition of cancer cell proliferation.

Perindopril Induces TSP-1 Expression in Hypertensive Patients with Endothelial Dysfunction in Chronic Treatment

Thrombospondin-1 (TSP-1) is a potent endogenous inhibitor of both physiological and pathological angiogenesis, widely studied as a target in drug development for treating cancer. Several studies performed in the cardiovascular field on TSP-1 are contradictory, the role of TSP-1 in the physiopathology of cardiovascular disorders (CVDs) being, for the moment, incompletely understood and may be due to the presence of several domains in its structure which can stimulate many cellular receptors. It has been reported to inhibit NO-mediated signaling and to act on the angiogenesis, tissue perfusion, endothelial cell proliferation, and homeostasis, so we aimed to quantify the effect Perindopril has on TSP-1 plasma levels in hypertensive patients with endothelial dysfunction in comparison with other antihypertensive drugs, such as beta blockers, calcium channel blockers, and diuretics, in a chronic treatment. As a conclusion, patients under treatment with Perindopril had increased plasma levels of TSP-1 compared with other hypertensive patients and with the control group. The results of this study confirms the pleiotropic properties of Perindopril: anti-proliferative, anti-inflammatory, with effects showed by quantifying a single biomarker: TSP-1.

MicroRNA and receptor mediated signaling pathways as potential therapeutic targets in heart failure

INTRODUCTION

Cardiac remodelling is a complex pathogenetic pathway involving genome expression, molecular, cellular, and interstitial changes that cause changes in size, shape and function of the heart after cardiac injury. Areas covered: We will review recent advances in understanding the role of several receptor-mediated signaling pathways and micro-RNAs, in addition to their potential as candidate target pathways in the pathogenesis of heart failure. The myocyte is the main target cell involved in the remodelling process via ischemia, cell necrosis and apoptosis (by means of various receptor pathways), and other mechanisms mediated by micro-RNAs. We will analyze the role of some receptor mediated signaling pathways such as natriuretic peptides, mediators of glycogen synthase kinase 3 and ERK1/2 pathways, beta-adrenergic receptor subtypes and relaxin receptor signaling mechanisms, TNF/TNF receptor family and TWEAK/Fn14 axis, and some micro-RNAs as candidate target pathways in pathogenesis of heart failure. These mediators of receptor-mediated pathways and micro-RNA are the most addressed targets of emerging therapies in modern heart failure treatment strategies. Expert opinion: Future treatment strategies should address mediators involved in multiple steps within heart failure pathogenetic pathways.

Cardiac fibrosis in myocardial infarction-from repair and remodeling to regeneration

Ischemic cell death during a myocardial infarction leads to a multiphase reparative response in which the damaged tissue is replaced with a fibrotic scar produced by fibroblasts and myofibroblasts. This also induces geometrical, biomechanical, and biochemical changes in the uninjured ventricular wall eliciting a reactive remodeling process that includes interstitial and perivascular fibrosis. Although the initial reparative fibrosis is crucial for preventing rupture of the ventricular wall, an exaggerated fibrotic response and reactive fibrosis outside the injured area are detrimental as they lead to progressive impairment of cardiac function and eventually to heart failure. In this review, we summarize current knowledge of the mechanisms of both reparative and reactive cardiac fibrosis in response to myocardial infarction, discuss the potential of inducing cardiac regeneration through direct reprogramming of fibroblasts and myofibroblasts into cardiomyocytes, and review the currently available and potential future therapeutic strategies to inhibit cardiac fibrosis. Graphical abstract Reparative response following a myocardial infarction. Hypoxia-induced cardiomyocyte death leads to the activation of myofibroblasts and a reparative fibrotic response in the injured area. Right top In adult mammals, the fibrotic scar formed at the infarcted area is permanent and promotes reactive fibrosis in the uninjured myocardium. Right bottom In teleost fish and newts and in embryonic and neonatal mammals, the initial formation of a fibrotic scar is followed by regeneration of the cardiac muscle tissue. Induction of post-infarction cardiac regeneration in adult mammals is currently the target of intensive research and drug discovery attempts.

Tendon development and musculoskeletal assembly: emerging roles for the extracellular matrix

Tendons and ligaments are extracellular matrix (ECM)-rich structures that interconnect muscles and bones. Recent work has shown how tendon fibroblasts (tenocytes) interact with muscles via the ECM to establish connectivity and strengthen attachments under tension. Similarly, ECM-dependent interactions between tenocytes and cartilage/bone ensure that tendon-bone attachments form with the appropriate strength for the force required. Recent studies have also established a close lineal relationship between tenocytes and skeletal progenitors, highlighting the fact that defects in signals modulated by the ECM can alter the balance between these fates, as occurs in calcifying tendinopathies associated with aging. The dynamic fine-tuning of tendon ECM composition and assembly thus gives rise to the remarkable characteristics of this unique tissue type. Here, we provide an overview of the functions of the ECM in tendon formation and maturation that attempts to integrate findings from developmental genetics with those of matrix biology.

Thrombospondin-4 knockout in hypertension protects small-artery endothelial function but induces aortic aneurysms

Thrombospondin-4 (TSP-4) is a multidomain calcium-binding protein that has both intracellular and extracellular functions. As an extracellular matrix protein, it is involved in remodeling processes. Previous work showed that, in the cardiovascular system, TSP-4 expression is induced in the heart in response to experimental pressure overload and infarction injury. Intracellularly, it mediates the endoplasmic reticulum stress response in the heart. In this study, we explored the role of TSP-4 in hypertension. For this purpose, wild-type and TSP-4 knockout (Thbs4(-/-)) mice were treated with angiotensin II (ANG II). Hearts from ANG II-treated Thbs4(-/-) mice showed an exaggerated hypertrophic response. Interestingly, aortas from Thbs4(-/-) mice treated with ANG II showed a high incidence of aneurysms. In resistance arteries, ANG II-treated wild-type mice showed impaired endothelial-dependent relaxation. This was not observed in ANG II-treated Thbs4(-/-) mice or in untreated controls. No differences were found in the passive pressure-diameter curves or stress-strain relationships, although ANG II-treated Thbs4(-/-) mice showed a tendency to be less stiff, associated with thicker diameters of the collagen fibers as revealed by electron microscopy. We conclude that TSP-4 plays a role in hypertension, affecting cardiac hypertrophy, aortic aneurysm formation, as well as endothelial-dependent relaxation in resistance arteries.

Thrombospondins in the transition from myocardial infarction to heart failure

The heart's reaction to ischemic injury from a myocardial infarction involves complex cross-talk between the extra-cellular matrix (ECM) and different cell types within the myocardium. The ECM functions not only as a scaffold where myocytes beat synchronously, but an active signaling environment that regulates the important post-MI responses. The thrombospondins are matricellular proteins that modulate cell--ECM interactions, functioning as "sensors" that mediate outside-in and inside-out signaling. Thrombospondins are highly expressed during embryonic stages, and although their levels decrease during adult life, can be re-expressed in high quantities in response to cardiac stress including myocardial infarction and heart failure. Like a Swiss-army knife, the thrombospondins possess many tools: numerous binding domains that allow them to interact with other elements of the ECM, cell surface receptors, and signaling molecules. It is through these that the thrombospondins function. In the present review, we provide basic as well as clinical evidence linking the thrombospondin proteins with the post myocardial infarction response, including inflammation, fibrotic matrix remodeling, angiogenesis, as well as myocyte hypertrophy, apoptosis, and contractile dysfunction in heart failure. We will describe what is known regarding the intracellular signaling pathways that are involved with these responses, paving the road for future studies identifying these proteins as therapeutic targets for cardiac disease.

Proangiogenic Properties of Thrombospondin-4

OBJECTIVE

Thrombospondin-4 (TSP-4) is 1 of the 5 members of the thrombospondin protein family. TSP-1 and TSP-2 are potent antiangiogenic proteins. However, angiogenic properties of the 3 other TSPs, which do not contain the domains associated with the antiangiogeneic activity of TSP-1 and TSP-2, have not been explored. In our previous studies, we found that TSP-4 is expressed in the vascular matrix of blood vessels of various sizes and is especially abundant in capillaries. We sought to identify the function of TSP-4 in the regulation of angiogenesis.

APPROACH AND RESULTS

The effect of TSP-4 in in vivo angiogenesis models and its effect on angiogenesis-related properties in cultured cells were assessed using Thbs4(-/-) mice, endothelial cells (EC) derived from these mice, and recombinant TSP-4. Angiogenesis was decreased in Thbs4(-/-) mice compared with wild-type mice. TSP-4 was detected in the lumen of the growing blood vessels. Mice expressing the P387 TSP-4 variant, which was previously associated with coronary artery disease and found to be more active in its cellular interactions, displayed greater angiogenesis compared with A387 form. Lung EC from Thbs4(-/-) mice exhibited decreased adhesion, migration, and proliferation capacities compared with EC from wild-type mice. Recombinant TSP-4 promoted proliferation and the migration of EC. Integrin α2 and gabapentin receptor α2δ-1 were identified as receptors involved in regulation of EC adhesion, migration, and proliferation by TSP-4.

CONCLUSION

TSP-4, an extracellular matrix protein previously associated with tissue remodeling, is now demonstrated to possess proangiogenic activity.

Expression of the tissue inhibitor of metalloproteinase-3 by transplanted VSMCs modifies heart structure and function after myocardial infarction

OBJECTIVES

Extracellular matrix (ECM) remodelling is a critical aspect of cardiac remodelling following myocardial infarction. Tissue inhibitors of metalloproteinases (TIMPs) are physiological inhibitors of matrix metalloproteinases (MMPs) that degrade the ECM proteins. TIMP-3 is highly expressed in the heart and is markedly downregulated in patients with ischaemic cardiomyopathy. Cell-based gene therapy can enhance the effects of cell transplantation by temporally and spatially regulating the release of the gene product. The purpose of this study was to investigate the role of TIMP-3 gene-transfected vascular smooth muscle cells (VSMCs) in modifying heart structure and function in rats when transplanted 3days after myocardial infarction (MI).

METHODS

Anesthetised rats were subjected to coronary artery ligation followed 3days later by thoracotomy and transplantation of TIMP-3 gene-transfected VSMCs, untransfected VSMCs or medium injected directly into the ischaemic myocardium. We assessed left ventricular structure and function by echocardiography and morphometry, and measured the levels of myocardial matrix metalloproteinase-2 and -9 (MMP-2, MMP-9), TIMP-3 and tumour necrosis factor-α (TNF-α) at 4weeks post-myocardial infarction.

RESULTS

Transplantation of TIMP-3 gene-transfected VSMCs and untransfected VSMCs significantly decreased scar expansion and ventricular dilatation 25days post-transplantation (4weeks after MI). MMPs and TNF-α levels were reduced in the transplantation groups when compared to the group that was given an injection of medium only. Transplantation of TIMP-3 gene-transfected VSMCs was more effective in preventing progressive cardiac dysfunction, ventricular dilatation and in reducing MMP-2, MMP-9 and TNF-α levels when compared to the transplantation of untransfected VSMCs.

CONCLUSIONS

TIMP-3 gene transfection was associated with attenuated left ventricular dilation and recovery of systolic function after MI compared with the control. TIMP-3 transfection enhanced the effects of transplanted VSMCs in rats by inhibiting matrix degradation and inflammatory cytokine expression, leading to improved myocardial remodelling.

Invoking the power of thrombospondins: regulation of thrombospondins expression

Increasing evidence suggests critical functions of thrombospondins (TSPs) in a variety of physiological and pathological processes. With the growing understanding of the importance of these matricellular proteins, the need to understand the mechanisms of regulation of their expression and potential approaches to modulate their levels is also increasing. The regulation of TSP expression is multi-leveled, cell- and tissue-specific, and very precise. However, the knowledge of mechanisms modulating the levels of TSPs is fragmented and incomplete. This review discusses the known mechanisms of regulation of TSP levels and the gaps in our knowledge that prevent us from developing strategies to modulate the expression of these physiologically important proteins.

Elucidating novel serum biomarkers associated with pulmonary tuberculosis treatment

In an unbiased approach to biomarker discovery, we applied a highly multiplexed proteomic technology (SOMAscan, SomaLogic, Inc, Boulder, CO) to understand changes in proteins from paired serum samples at enrollment and after 8 weeks of TB treatment from 39 patients with pulmonary TB from Kampala, Uganda enrolled in the Center for Disease Control and Prevention's Tuberculosis Trials Consortium (TBTC) Study 29. This work represents the first large-scale proteomic analysis employing modified DNA aptamers in a study of active tuberculosis (TB). We identified multiple proteins that exhibit significant expression differences during the intensive phase of TB therapy. There was enrichment for proteins in conserved networks of biological processes and function including antimicrobial defense, tissue healing and remodeling, acute phase response, pattern recognition, protease/anti-proteases, complement and coagulation cascade, apoptosis, immunity and inflammation pathways. Members of cytokine pathways such as interferon-gamma, while present, were not as highly represented as might have been predicted. The top proteins that changed between baseline and 8 weeks of therapy were TSP4, TIMP-2, SEPR, MRC-2, Antithrombin III, SAA, CRP, NPS-PLA2, LEAP-1, and LBP. The novel proteins elucidated in this work may provide new insights for understanding TB disease, its treatment and subsequent healing processes that occur in response to effective therapy.