Endothelial to Mesenchymal Transition in Pulmonary Vascular Diseases

Endothelial-to-Mesenchymal Transition in Cardiovascular Pathophysiology

Under different pathophysiological conditions, endothelial cells lose endothelial phenotype and gain mesenchymal cell-like phenotype via a process known as endothelial-to-mesenchymal transition (EndMT). At the molecular level, endothelial cells lose the expression of endothelial cell-specific markers such as CD31/platelet-endothelial cell adhesion molecule, von Willebrand factor, and vascular-endothelial cadherin and gain the expression of mesenchymal cell markers such as α-smooth muscle actin, N-cadherin, vimentin, fibroblast specific protein-1, and collagens. EndMT is induced by numerous different pathways triggered and modulated by multiple different and often redundant mechanisms in a context-dependent manner depending on the pathophysiological status of the cell. EndMT plays an essential role in embryonic development, particularly in atrioventricular valve development; however, EndMT is also implicated in the pathogenesis of several genetically determined and acquired diseases, including malignant, cardiovascular, inflammatory, and fibrotic disorders. Among cardiovascular diseases, aberrant EndMT is reported in atherosclerosis, pulmonary hypertension, valvular disease, fibroelastosis, and cardiac fibrosis. Accordingly, understanding the mechanisms behind the cause and/or effect of EndMT to eventually target EndMT appears to be a promising strategy for treating aberrant EndMT-associated diseases. However, this approach is limited by a lack of precise functional and molecular pathways, causes and/or effects, and a lack of robust animal models and human data about EndMT in different diseases. Here, we review different mechanisms in EndMT and the role of EndMT in various cardiovascular diseases.

Molecular Mechanisms Responsible for the Therapeutic Potential of Mesenchymal Stem Cell-Derived Exosomes in the Treatment of Lung Fibrosis

Mesenchymal stem cell-derived exosomes (MSC-Exos) are nano-sized extracellular vesicles which contain various MSC-sourced anti-fibrotic, immunoregulatory and angio-modulatory proteins (growth factors, immunoregulatory cytokines, chemokines), lipids, and nucleic acids (messenger RNA and microRNAs). Due to their lipid envelope, MSC-Exos easily by-pass all barriers in the body and deliver their cargo directly in target cells, modulating their viability, proliferation, phenotype and function. The results obtained in recently published experimental studies demonstrated beneficial effects of MSC-Exos in the treatment of lung fibrosis. MSC-Exos reduced activation of fibroblasts and prevented their differentiation in myofibroblasts. By delivering MSC-sourced immunoregulatory factors in lung-infiltrated monocytes and T cells, MSC-Exos modulate their function, alleviating on-going inflammation and fibrosis. MSC-Exos may also serve as vehicles for the target delivery of anti-fibrotic and immunomodulatory agents, enabling enhanced attenuation of lung fibrosis. Although numerous pre-clinical studies have demonstrated the therapeutic potential of MSC-Exos in the treatment of pulmonary fibrosis, there are several challenges that currently hinder their clinical implementation. Therefore, in this review article, we summarized current knowledge and we discussed future perspectives regarding molecular and cellular mechanisms which were responsible for the anti-fibrotic, anti-inflammatory and immunoregulatory properties of MSC-Exos, paving the way for their clinical use in the treatment of lung fibrosis.

Cutaneous vasculitis: insights into pathogenesis and histopathological features

The mechanisms underlying the onset and progression of vasculitis remain poorly understood. This condition is characterized by damage to the vascular wall, recruitment of inflammatory cells, and subsequent structural remodeling, which are hallmarks of vasculitis. The histopathological classification of vasculitis relies on the size of the affected vessel and the predominant type of inflammatory cell involved - neutrophils in acute cases, lymphocytes in chronic conditions, and histiocytes in granulomatous forms. Pathological changes progress in every context, and a single vasculitic pattern can be associated with various systemic conditions. Conversely, a single causative agent may lead to multiple distinct clinical and pathological manifestations of vasculitis. Moreover, many cases of vasculitis have no identifiable cause. A foundational understanding of the normal structure of the cutaneous vascular network is crucial. Similarly, identifying the cellular and molecular participants and their roles in forming the "dermal microvascular unit" is propedeutical.

This review aims to elucidate the complex mechanisms involved in the initiation and progression of vasculitis, offering a comprehensive overview of its histopathological classification, underlying causes, and the significant role of the cutaneous vascular network and cellular dynamics. By integrating the latest insights from studies on NETosis and the implications of lymphocytic infiltration in autoimmune diseases, we seek to bridge gaps in current knowledge and highlight areas for future research. Our discussion extends to the clinical implications of vasculitis, emphasizing the importance of identifying etiological agents and understanding the diverse histopathological manifestations to improve diagnostic accuracy and treatment outcomes.

Overexpressed pigment epithelium-derived factor alleviates pulmonary hypertension in two rat models induced by monocrotaline and SU5416/hypoxia

BACKGROUND

Pulmonary hypertension (PH) is a progressive and fatal cardiopulmonary disease characterized by vascular remodeling and is associated with endothelial-to-mesenchymal transition (EndoMT). The pigment epithelium-derived factor (PEDF), a secretory protein widely distributed in multiple organs, has been shown to demonstrate anti-EndoMT activity in cardiovascular diseases. In the present study, the role of PEDF in PH was investigated.

METHODS

For PEDF overexpression, Sprague Dawley rats were infected with an adeno-associated virus through injection via the internal jugular vein. To establish PH models, the animals were subjected to monocrotaline or Sugen/hypoxia. Four weeks later, pulmonary artery angiography was performed, and hemodynamic parameters, right ventricular function, and vascular remodeling were evaluated. EndoMT and cell proliferation in the pulmonary arteries were assessed via immunofluorescence staining. Moreover, pulmonary artery endothelial cells (PAECs) isolated from experimental PH rats were cultured to investigate the underlying molecular mechanisms involved.

RESULTS

PEDF expression was significantly downregulated in PAECs from PH patients and PH model rats. Overexpressed PEDF alleviated the development of PH by improving pulmonary artery morphology and perfusion, reducing pulmonary artery pressure, improving right ventricular function, and alleviating vascular remodeling. PEDF inhibits EndoMT and reduces excessive PAEC proliferation. Moreover, PEDF overexpression reduced EndoMT in cultured PAECs by competitively inhibiting the binding of wnt to LRP6 and downregulating phosphorylation at the 1490 site of LRP6.

CONCLUSIONS

Our findings suggest that PEDF may be a potential therapeutic target for PH. We also found that PEDF can inhibit EndoMT in PAECs and may exert these effects by inhibiting the Wnt/LRP6/β-catenin pathway.

Human iPSCs as Model Systems for BMP-Related Rare Diseases

Disturbances in bone morphogenetic protein (BMP) signalling contribute to onset and development of a number of rare genetic diseases, including Fibrodysplasia ossificans progressiva (FOP), Pulmonary arterial hypertension (PAH), and Hereditary haemorrhagic telangiectasia (HHT). After decades of animal research to build a solid foundation in understanding the underlying molecular mechanisms, the progressive implementation of iPSC-based patient-derived models will improve drug development by addressing drug efficacy, specificity, and toxicity in a complex humanized environment. We will review the current state of literature on iPSC-derived model systems in this field, with special emphasis on the access to patient source material and the complications that may come with it. Given the essential role of BMPs during embryonic development and stem cell differentiation, gain- or loss-of-function mutations in the BMP signalling pathway may compromise iPSC generation, maintenance, and differentiation procedures. This review highlights the need for careful optimization of the protocols used. Finally, we will discuss recent developments towards complex in vitro culture models aiming to resemble specific tissue microenvironments with multi-faceted cellular inputs, such as cell mechanics and ECM together with organoids, organ-on-chip, and microfluidic technologies.

Pathophysiology and pathogenic mechanisms of pulmonary hypertension: role of membrane receptors, ion channels, and Ca2+ signaling

The pulmonary circulation is a low-resistance, low-pressure, and high-compliance system that allows the lungs to receive the entire cardiac output. Pulmonary arterial pressure is a function of cardiac output and pulmonary vascular resistance, and pulmonary vascular resistance is inversely proportional to the fourth power of the intraluminal radius of the pulmonary artery. Therefore, a very small decrease of the pulmonary vascular lumen diameter results in a significant increase in pulmonary vascular resistance and pulmonary arterial pressure. Pulmonary arterial hypertension is a fatal and progressive disease with poor prognosis. Regardless of the initial pathogenic triggers, sustained pulmonary vasoconstriction, concentric vascular remodeling, occlusive intimal lesions, in situ thrombosis, and vascular wall stiffening are the major and direct causes for elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension and other forms of precapillary pulmonary hypertension. In this review, we aim to discuss the basic principles and physiological mechanisms involved in the regulation of lung vascular hemodynamics and pulmonary vascular function, the changes in the pulmonary vasculature that contribute to the increased vascular resistance and arterial pressure, and the pathogenic mechanisms involved in the development and progression of pulmonary hypertension. We focus on reviewing the pathogenic roles of membrane receptors, ion channels, and intracellular Ca2+ signaling in pulmonary vascular smooth muscle cells in the development and progression of pulmonary hypertension.

Mesenchymal stem cell-derived exosomes in cardiovascular and cerebrovascular diseases: From mechanisms to therapy

Cardiovascular and cerebrovascular diseases (CVDs) remain an intractable problem and have high morbidity and mortality worldwide, as well as substantial health and economic burdens, representing an urgent clinical need. In recent years, the focus of research has shifted from the use of mesenchymal stem cells (MSCs) for transplantation to the use of their secretory exosomes (MSC-exosomes) for the treatment of numerous CVDs, including atherosclerosis, myocardial infarction (MI), heart failure (HF), ischemia/reperfusion (I/R), aneurysm, and stroke. MSCs are pluripotent stem cells with multiple differentiation pathways that exert pleiotropic effects by producing soluble factors, the most effective components of which are exosomes. MSC-exosomes are considered to be an excellent and promising cell-free therapy for CVDs due to their higher circulating stability, improved biocompatibility, reduced toxicity, and immunogenicity. In addition, exosomes play critical roles in repairing CVDs by inhibiting apoptosis, regulating inflammation, ameliorating cardiac remodeling, and promoting angiogenesis. Herein, we describe knowledge about the biological characteristics of MSC-exosomes, investigate the mechanism by which MSC-exosomes mediate therapeutic repair, and summarize recent advances in the efficacy of MSC-exosomes in CVDs, with a view toward future clinical applications.

APELIN-13 AMELIORATES LPS-INDUCED ENDOTHELIAL-TO-MESENCHYMAL TRANSITION AND POST-ACUTE LUNG INJURY PULMONARY FIBROSIS BY SUPPRESSING TRANSFORMING GROWTH FACTOR-Β1 SIGNALING

ABSTRACT

The pathophysiology of acute respiratory distress syndrome (ARDS) involves cytokine storms, alveolar-capillary barrier destruction, and fibrotic progression. Pulmonary interstitial fibrosis is an important factor affecting the prognosis of ARDS patients. Endothelial-to-mesenchymal transition (EndMT) plays an important role in the development of fibrotic diseases, and the occurrence of EndMT has been observed in experimental models of LPS-induced acute lung injury (ALI). Apelin is an endogenous active polypeptide that plays an important role in maintaining endothelial cell homeostasis and inhibiting fibrotic progression in various diseases. However, whether apelin attenuates EndMT in ALI and post-ALI pulmonary fibrosis remains unclear. We analyzed the serum levels of apelin-13 in patients with sepsis-associated ARDS to examine its possible clinical value. A murine model of LPS-induced pulmonary fibrosis and an LPS-challenged endothelial cell injury model were used to analyze the protective effect and underlying mechanism of apelin-13. Mice were treated with apelin-13 by i.p. injection, and human pulmonary microvascular endothelial cells were incubated with apelin-13 in vitro . We found that the circulating apelin-13 levels were significantly elevated in sepsis-associated ARDS patients compared with healthy controls. Our study also confirmed that LPS induced EndMT progression and pulmonary fibrosis, which were characterized by decreased CD31 expression and increased α-smooth muscle actin expression and collagen deposition. LPS also stimulated the production of transforming growth factor β1 and activated the Smad signaling pathway. However, apelin-13 treatment significantly attenuated these changes. Our findings suggest that apelin-13 may be a novel biomarker in patients with sepsis-associated ARDS. These results demonstrate that apelin-13 ameliorates LPS-induced EndMT and post-ALI pulmonary fibrosis by suppressing transforming growth factor β1 signaling.

Nanoparticle endothelial delivery of PGC-1α attenuates hypoxia-induced pulmonary hypertension by attenuating EndoMT-caused vascular wall remodeling

Pulmonary hypertension (PH) induced by chronic hypoxia is characterized by thickening of pulmonary artery walls, elevated pulmonary vascular resistance, and right-heart failure. Dysfunction of endothelial cells is the hallmark event in the progression of PH. Among various mechanisms, endothelial to mesenchymal transition (EndoMT) has emerged as an important source of endothelial cell dysfunction in PH. However, the mechanisms underlying the EndoMT in PH remain largely unknown. Our results showed that peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) expression was decreased in pulmonary arterial endothelial cells (PAECs) in PH patients and hypoxia-induced PH mouse model compared to the normal controls. Endothelial-specific overexpression of PGC-1α using nanoparticle delivery significantly attenuated the progression of PH, as shown by the significantly decreased right ventricular systolic pressure and diminished artery thickness as well as reduced vascular muscularization. Moreover, Endothelial-specific overexpression of PGC-1α blocked the EndoMT of PAECs during PH, indicating that loss of PGC-1α promotes PH development by mediating EndoMT, which damages the integrity of endothelium. Intriguingly, we found that PGC-1α overexpression rescued the expression of endothelial nitric oxide synthase in mouse lung tissues that was deceased by hypoxia treatment in vivo and in endothelial cells treated with TGF-β in vitro. Consistently, PAECs and vascular smooth muscle co-culture showed that overexpression of PGC-1α in PAECs increases nitric oxide release, which would likely diffuse to smooth muscle cells, where it activates specific protein kinases, and initiates SMC relaxation by diminishing the calcium flux. Endothelial-specific overexpression of PGC-1α also attenuated hypoxia-induced pulmonary artery stiffness which appeared to be caused by both the decreased endothelial nitric oxide production and increased vascular remodeling. Taken together, these results demonstrated that endothelial-specific delivery of PGC-1α prevents PH development by inhibiting EndoMT of PAECs and thus restoring endothelial function and reducing vascular remodeling.

Mechanistic and therapeutic perspectives of baicalin and baicalein on pulmonary hypertension: A comprehensive review

Pulmonary hypertension (PH) is a chronic and fatal disease, for which new therapeutic drugs and approaches are needed urgently. Baicalein and baicalin, the active compounds of the traditional Chinese medicine, Scutellaria baicalensis Georgi, exhibit a wide range of pharmacological activities. Numerous studies involving in vitro and in vivo models of PH have revealed that the treatment with baicalin and baicalein may be effective. This review summarizes the potential mechanisms driving the beneficial effects of baicalin and baicalein treatment on PH, including anti-inflammatory response, inhibition of pulmonary smooth muscle cell proliferation and endothelial-to-mesenchymal transformation, stabilization of the extracellular matrix, and mitigation of oxidative stress. The pharmacokinetics of these compounds have also been reviewed. The therapeutic potential of baicalin and baicalein warrants their continued study as natural treatments for PH.

Palmitic acid promotes endothelial-to-mesenchymal transition via activation of the cytosolic DNA-sensing cGAS-STING pathway

Elevated levels of plasma free fatty acids (FFAs) lead to endothelial dysfunction, a process that is involved in the pathogenesis of atherosclerosis. Endothelial-to-mesenchymal transformation (EndMT) has been reported to accelerate endothelial dysfunction during the process of atherosclerosis. However, the underlying mechanisms of EndMT remain poorly understood. The present study aimed to investigate the role of the cytosolic DNA-sensing cyclic GMP-AMP synthase-stimulator interferon gene (cGAS-STING) pathway in palmitic acid (PA)-induced EndMT. Human aortic endothelial cells (HAECs) were exposed to different concentrations of PA, and subsequently its effects on EndMT and the cGAS-STING pathway were assessed. To investigate the role of cGAS-STING pathway on PA-induced EndMT, RNA interference was used to knockdown the expression of cGAS in HAECs prior to their exposure to PA. First, it was observed that PA reduced cell viability and intracellular nitric oxide production, and increased migratory capacity of the HAECs as well as the cellular oxidative stress response, leading to EndMT. Moreover, it was observed that the cGAS-STING pathway was activated in PA-exposed primary HAECs. Activating cGAS-STING pathway via mtDNA directing lead to EndMT in HAECs. Interestingly, cGAS knockdown by RNA interference attenuated PA-induced inflammation, oxidative stress and EndMT in HAECs. Taken together, the results of the present study suggested that the cytosolic DNA-sensing cGAS-STING pathway may have important roles in PA-induced EndMT in endothelial cells.

The Role of Endothelial-to-Mesenchymal Transition in Cardiovascular Disease

Endothelial-to-mesenchymal transition (EndoMT) is the process of endothelial cells progressively losing endothelial-specific markers and gaining mesenchymal phenotypes. In the normal physiological condition, EndoMT plays a fundamental role in forming the cardiac valves of the developing heart. However, EndoMT contributes to the development of various cardiovascular diseases (CVD), such as atherosclerosis, valve diseases, fibrosis, and pulmonary arterial hypertension (PAH). Therefore, a deeper understanding of the cellular and molecular mechanisms underlying EndoMT in CVD should provide urgently needed insights into reversing this condition. This review summarizes a 30-year span of relevant literature, delineating the EndoMT process in particular, key signaling pathways, and the underlying regulatory networks involved in CVD.

Endothelial Cell Phenotype, a Major Determinant of Venous Thrombo-Inflammation

Reduced blood flow velocity in the vein triggers inflammation and is associated with the release into the extracellular space of alarmins or damage-associated molecular patterns (DAMPs). These molecules include extracellular nucleic acids, extracellular purinergic nucleotides (ATP, ADP), cytokines and extracellular HMGB1. They are recognized as a danger signal by immune cells, platelets and endothelial cells. Hence, endothelial cells are capable of sensing environmental cues through a wide variety of receptors expressed at the plasma membrane. The endothelium is then responding by expressing pro-coagulant proteins, including tissue factor, and inflammatory molecules such as cytokines and chemokines involved in the recruitment and activation of platelets and leukocytes. This ultimately leads to thrombosis, which is an active pro-inflammatory process, tightly regulated, that needs to be properly resolved to avoid further vascular damages. These mechanisms are often dysregulated, which promote fibrinolysis defects, activation of the immune system and irreversible vascular damages further contributing to thrombotic and inflammatory processes. The concept of thrombo-inflammation is now widely used to describe the complex interactions between the coagulation and inflammation in various cardiovascular diseases. In endothelial cells, activating signals converge to multiple intracellular pathways leading to phenotypical changes turning them into inflammatory-like cells. Accumulating evidence suggest that endothelial to mesenchymal transition (EndMT) may be a major mechanism of endothelial dysfunction induced during inflammation and thrombosis. EndMT is a biological process where endothelial cells lose their endothelial characteristics and acquire mesenchymal markers and functions. Endothelial dysfunction might play a central role in orchestrating and amplifying thrombo-inflammation thought induction of EndMT processes. Mechanisms regulating endothelial dysfunction have been only partially uncovered in the context of thrombotic diseases. In the present review, we focus on the importance of the endothelial phenotype and discuss how endothelial plasticity may regulate the interplay between thrombosis and inflammation. We discuss how the endothelial cells are sensing and responding to environmental cues and contribute to thrombo-inflammation with a particular focus on venous thromboembolism (VTE). A better understanding of the precise mechanisms involved and the specific role of endothelial cells is needed to characterize VTE incidence and address the risk of recurrent VTE and its sequelae.

The “Third Violin” in the Cytoskeleton Orchestra—The Role of Intermediate Filaments in the Endothelial Cell’s Life

The endothelium plays an important role in the transcytosis of lipoproteins. According to one of the theories, endothelial injury is a triggering factor for the development of atherosclerosis, and intracellular structures, including components of the endotheliocyte cytoskeleton (microtubules, actin, and intermediate filaments), are involved in its development. In contrast to the proteins of tubulin-based microtubules and actin microfilaments, intermediate filaments are comprised of various tissue-specific protein members. Vimentin, the main protein of endothelial intermediate filaments, is one of the most well-studied of these and belongs to type-III intermediate filaments, commonly found in cells of mesenchymal origin. Vimentin filaments are linked mechanically or by signaling molecules to microfilaments and microtubules by which coordinated cell polarisation and migration are carried out, as well as control over several endotheliocyte functions. Moreover, the soluble vimentin acts as an indicator of the state of the cardiovascular system, and the involvement of vimentin in the development and course of atherosclerosis has been demonstrated. Here we discuss current concepts of the participation of vimentin filaments in the vital activity and functioning of endothelial cells, as well as the role of vimentin in the development of inflammatory processes and atherosclerosis.

Endothelial upregulation of mechanosensitive channel Piezo1 in pulmonary hypertension

Piezo is a mechanosensitive cation channel responsible for stretch-mediated Ca2+ and Na+ influx in multiple types of cells. Little is known about the functional role of Piezo1 in the lung vasculature and its potential pathogenic role in pulmonary arterial hypertension (PAH). Pulmonary arterial endothelial cells (PAECs) are constantly under mechanic stretch and shear stress that are sufficient to activate Piezo channels. Here, we report that Piezo1 is significantly upregulated in PAECs from patients with idiopathic PAH and animals with experimental pulmonary hypertension (PH) compared with normal controls. Membrane stretch by decreasing extracellular osmotic pressure or by cyclic stretch (18% CS) increases Ca2+-dependent phosphorylation (p) of AKT and ERK, and subsequently upregulates expression of Notch ligands, Jagged1/2 (Jag-1 and Jag-2), and Delta like-4 (DLL4) in PAECs. siRNA-mediated downregulation of Piezo1 significantly inhibited the stretch-mediated pAKT increase and Jag-1 upregulation, whereas downregulation of AKT by siRNA markedly attenuated the stretch-mediated Jag-1 upregulation in human PAECs. Furthermore, the mRNA and protein expression level of Piezo1 in the isolated pulmonary artery, which mainly contains pulmonary arterial smooth muscle cells (PASMCs), from animals with severe PH was also significantly higher than that from control animals. Intraperitoneal injection of a Piezo1 channel blocker, GsMTx4, ameliorated experimental PH in mice. Taken together, our study suggests that membrane stretch-mediated Ca2+ influx through Piezo1 is an important trigger for pAKT-mediated upregulation of Jag-1 in PAECs. Upregulation of the mechanosensitive channel Piezo1 and the resultant increase in the Notch ligands (Jag-1/2 and DLL4) in PAECs may play a critical pathogenic role in the development of pulmonary vascular remodeling in PAH and PH.

Endocardial Endothelial Dysfunction and Unknown Polymorphic Composite Accumulation in Heart Failure

The accumulation of unknown polymorphic composites in the endocardium damages the endocardial endothelium (EE). However, the composition and role of unknown polymorphic composites in heart failure (HF) progression remain unclear. Here, we aimed to explore composite deposition during endocardium damage and HF progression. Adult male Sprague–Dawley rats were divided into two HF groups—angiotensin II-induced HF and left anterior descending artery ligation-induced HF. Heart tissues from patients who had undergone coronary artery bypass graft surgery (non-HF) and those with dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (ICM) were collected. EE damage, polymorphic unknown composite accumulation, and elements in deposits were examined. HF progression reduced the expression of CD31 in the endocardium, impaired endocardial integrity, and exposed the myofibrils and mitochondria. The damaged endocardial surface showed the accumulation of unknown polymorphic composites. In the animal HF model, especially HF caused by myocardial infarction, the weight and atomic percentages of O, Na, and N in the deposited composites were significantly higher than those of the other groups. The deposited composites in the human HF heart section (DCM) had a significantly higher percentage of Na and S than the other groups, whereas the percentage of C and Na in the DCM and ICM groups was significantly higher than those of the control group. HF causes widespread EE dysfunction, and EndMT was accompanied by polymorphic composites of different shapes and elemental compositions, which further damage and deteriorate heart function.

Endothelial-to-mesenchymal transition in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by significant vascular alterations and multi-organ fibrosis. Microvascular alterations are the first event of SSc and injured endothelial cells (ECs) may transdifferentiate towards myofibroblasts, the cells responsible for fibrosis and collagen deposition. This process is identified as endothelial-to-mesenchymal transition (EndMT), and understanding of its development is pivotal to identify early pathogenetic events and new therapeutic targets for SSc. In this review, we have highlighted the molecular mechanisms of EndMT and summarize the evidence of the role played by EndMT during the development of progressive fibrosis in SSc, also exploring the possible therapeutic role of its inhibition.