Endothelial Dysfunction in Systemic Sclerosis

Systemic sclerosis, commonly known as scleroderma, is an autoimmune disorder characterized by vascular abnormalities, autoimmunity, and multiorgan fibrosis. The exact etiology is not known but believed to be triggered by environmental agents in a genetically susceptible host. Vascular symptoms such as the Raynaud phenomenon often precede other fibrotic manifestations such as skin thickening indicating that vascular dysfunction is the primary event. Endothelial damage and activation occur early, possibly triggered by various infectious agents and autoantibodies. Endothelial dysfunction, along with defects in endothelial progenitor cells, leads to defective angiogenesis and vasculogenesis. Endothelial to mesenchymal cell transformation is another seminal event during pathogenesis that progresses to tissue fibrosis. The goal of the review is to discuss the molecular aspect of the endothelial dysfunction that leads to the development of systemic sclerosis.

Endothelial Dysfunction in Systemic Lupus Erythematosus and Systemic Sclerosis: A Common Trigger for Different Microvascular Diseases

This review describes the complex interplay between inflammation, vasculopathy and fibrosis that involve the heart and peripheral small vessels, leading to endothelial stiffness, vascular damage, and early aging in patients with systemic lupus erythematosus and systemic sclerosis, which represents two different models of vascular dysfunction among systemic autoimmune diseases. In fact, despite the fact that diagnostic methods and therapies have been significantly improved in the last years, affected patients show an excess of cardiovascular mortality if compared with the general population. In addition, we provide a complete overview on the new techniques which are used for the evaluation of endothelial dysfunction in a preclinical phase, which could represent a new approach in the assessment of cardiovascular risk in these patients.

Cellular and Molecular Diversity in Scleroderma

With the increasing armamentarium of high-throughput tools available at manageable cost, it is attractive and informative to determine the molecular underpinnings of patient heterogeneity in systemic sclerosis (SSc). Given the highly variable clinical outcomes of patients labelled with the same diagnosis, unravelling the cellular and molecular basis of disease heterogeneity will be crucial to predicting disease risk, stratifying management and ultimately informing a patient-centered precision medicine approach. Herein, we summarise the findings of the past several years in the fields of genomics, transcriptomics, and proteomics that contribute to unraveling the cellular and molecular heterogeneity of SSc. Expansion of these findings and their routine integration with quantitative analysis of histopathology and imaging studies into clinical care promise to inform a scientifically driven patient-centred personalized medicine approach to SSc in the near future.

Endothelial cells and endothelial progenitor cells in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive fibrosis, microvasculopathy, and autoimmunity. Endothelial cell (EC) injury and subsequent endothelial cell dysfunction is believed to be an initial event that eventually leads to a vicious pathogenic cycle. This process is further enhanced by defective angiogenesis and vasculogenesis, as the vascular repair machinery does not work properly. Endothelial progenitor cells (EPCs) are functionally and quantitatively insufficient to recover the endothelium in SSc patients. The dysfunctional ECs and EPCs not only trigger the formation of typical vascular lesions, such as progressive intimal fibrosis in small arteries and the loss of capillaries, but also promote a series of inflammatory and profibrotic processes, such as endothelial-mesenchymal transition and recruitment and accumulation of monocytic EPCs with profibrotic properties. These processes together contribute to the accumulation of extracellular matrix in the affected tissue. This review features current insights into the roles of ECs and EPCs in the pathogenesis of SSc.

Sustained benefit from combined plasmapheresis and allogeneic mesenchymal stem cells transplantation therapy in systemic sclerosis

Background

Systemic sclerosis (SSc) is an autoimmune disease involving the skin and several internal organs. Most therapies available for this disease are symptomatic. Given the difficulty in treating SSc, we conducted this study to investigate the effect of combined plasmapheresis (PE) and allogeneic mesenchymal stem cells transplantation (MSCT) therapy on SSc.

Methods

Fourteen patients underwent three repeated PE treatments with subsequent pulse cyclophosphamide on days 1, 3 and 5. Patients received a single MSCT (1 × 10⁶ cells/kg of body weight) on day 8. During follow up, evaluations performed included complete physical examination, serologic testing, and organ function.

Results

The mean modified Rodnan skin score (MRSS) improved from 20.1 ± 3.1 to 13.8 ± 10.2 (P < 0.001) at 12 months of follow up. Three patients had interstitial lung disease, all had improvement of lung function and improved computed tomography (CT) images after 12 months of combined therapy. This combined treatment also significantly decreased the anti-Scl70 autoantibody titer and serum transforming growth factor-β and vascular endothelial growth factor levels during follow up.

Conclusion

The results indicate that PE combined with MSCT is a feasible treatment associated with possible clinical benefit for SSc patients.

Trial registration

ClinicalTrials.gov, NCT00962923. Registered on 19 August 2009.

The role of endothelial cells in the vasculopathy of systemic sclerosis: A systematic review

INTRODUCTION

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by fibroproliferative vasculopathy, immunological abnormalities and progressive fibrosis of multiple organs including the skin. In this study, all English speaking articles concerning the role of endothelial cells (ECs) in SSc vasculopathy and representing biomarkers are systematically reviewed and categorized according to endothelial cell (EC) (dys)function in SSc.

METHODS

A sensitive search on behalf of the EULAR study group on microcirculation in Rheumatic Diseases was developed in Pubmed, The Cochrane Library and Web of Science to identify articles on SSc vasculopathy and the role of ECs using the following Mesh terms: (systemic sclerosis OR scleroderma) AND pathogenesis AND (endothelial cells OR marker). All selected papers were read and discussed by two independent reviewers. The selection process was based on title, abstract and full text level. Additionally, both reviewers further searched the reference lists of the articles selected for reading on full text level for supplementary papers. These additional articles went through the same selection process.

RESULTS

In total 193 resulting articles were selected and the identified biomarkers were categorized according to description of EC (dys)function in SSc. The most representing and reliable biomarkers described by the selected articles were adhesion molecules for EC activation, anti-endothelial cell antibodies for EC apoptosis, vascular endothelial growth factor (VEGF), its receptor VEGFR-2 and endostatin for disturbed angiogenesis, endothelial progenitors cells for defective vasculogenesis, endothelin-1 for disturbed vascular tone control, Von Willebrand factor for coagulopathy and interleukin (IL)-33 for EC-immune system communication. Emerging, relatively new discovered biomarkers described in the selected articles, are VEGF₁₆₅b, IL-17A and the adipocytokines. Finally, myofibroblasts involved in tissue fibrosis in SSc can derive from ECs or epithelial cells through a process known as endothelial-to-mesenchymal transition.

CONCLUSION

This systematic review emphasizes the growing evidence that SSc is primarily a vascular disease where EC dysfunction is present and prominent in different aspects of cell survival (activation and apoptosis), angiogenesis and vasculogenesis and where disturbed interactions between ECs and various other cells contribute to SSc vasculopathy.

Collapsed Reticular Network and its Possible Mechanism during the Initiation and/or Progression of Hepatic Fibrosis

Among the researches on hepatic fibrosis, great attention was paid to both hepatocytes and extracellular matrix (ECM). However, little focus was drawn on reticular fibrous network, which is important for demarcation and support of hepatocytes. The aim of this study was to investigate the change pattern of reticular fibers in hepatic fibrosis/cirrhosis and its underlying mechanism. In this study, thioacetamide (TAA) and bile duct ligation (BDL) were utilized to induce rat hepatic fibrosis respectively, and Human liver cirrhotic microassay was analyzed with IHC to confirm the results in animal experiment and to detect the metalloproteinases (MMPs) expressions. As a result, the reticular fibers decreased markedly after 1 week in TAA and 1 day in BDL treated rats. Multiple representative regulators of MMPs and MMPs increased significantly in their expressions and activities. Further more, in human liver cirrhotic microassay, MMPs expressions also showed similar patterns as that of animal experiment. In Conclusions: Degradation or collapse of reticular fibers in hepatic sinusoid can be considered as a pathological feature during the initiation and/or progression of hepatic fibrosis. Moreover, such degradation is associated with and probably caused by the over/dysregulated expression of MMPs.

Low-dose cyclophosphamide effectively mobilizes peripheral blood stem cells in patients with autoimmune disease

For patients with severe and refractory autoimmune diseases, high-dose chemotherapy and autologous hematopoietic stem cell transplantation has been established as a considerable therapeutic option in recent years. In this retrospective single-center analysis, we assessed the feasibility and efficacy of peripheral blood stem cells (PBSC) mobilization and collection in 35 patients with refractory autoimmune disease (AID). The mobilization data of 15 patients with systemic sclerosis (SSc), 11 patients with multiple sclerosis (MS), and 9 patients with other AID were analyzed. Stem cell mobilization with cyclophosphamide chemotherapy 2 × 2 g/m(2) (n = 16) or 1 × 2 g/m(2) (n = 17) and G-CSF followed by PBSC collection was performed between 1999 and 2015. Leukapheresis was performed in 16 inpatients and 19 outpatients. All patients reached their collection goal and no collection failures were observed. The median PBSC collection result was 12.2 (SSc), 8.0 (MS), and 8.2 (other AID) × 10(6) CD34+ cells/kg, respectively. Twenty-five of 35 (71%) patients achieved a sufficient collection with one leukapheresis session, while 6 patients (17%) required two and 4 patients (11%) required three or more leukapheresis sessions. No correlation of the collected PBSC number was observed regarding age, body weight, diagnosis, disease duration, skin sclerosis, or previous cyclophosphamide. Mobilization chemotherapy with cyclophosphamide 2 × 2 g/m(2) and 1 × 2 g/m(2) delivered comparable mobilization results with leukapheresis on day 13 or 14. In summary, we demonstrate that PBSC collection is safe and feasible in patients with AID. Mobilization chemotherapy with cyclophosphamide 1 × 2 g/m(2) and 2 × 2 g/m(2) is equally effective in those patients.

Efficient therapy of ischaemic lesions with VEGF121-fibrin in an animal model of systemic sclerosis

Background

In systemic sclerosis (SSc), chronic and uncontrolled overexpression of vascular endothelial growth factor (VEGF) results in chaotic vessels, and intractable fingertip ulcers. Vice versa, VEGF is a potent mediator of angiogenesis if temporally and spatially controlled. We have addressed this therapeutic dilemma in SSc by a novel approach using a VEGF₁₂₁ variant that covalently binds to fibrin and gets released on demand by cellular enzymatic activity. Using University of California at Davis (UCD)-206 chickens, we tested the hypothesis that cell-demanded release of fibrin-bound VEGF₁₂₁ leads to the formation of stable blood vessels, and clinical improvement of ischaemic lesions.

Methods

Ninety-one early and late ischaemic comb and neck skin lesions of UCD-206 chickens were treated locally with VEGF₁₂₁-fibrin, fibrin alone, or left untreated. After 1 week of treatment the clinical outcome was assessed. Angiogenesis was studied by immunofluorescence staining of vascular markers quantitatively analysed using TissueQuest.

Results

Overall, 79.3% of the lesions treated with VEGF₁₂₁-fibrin showed clinical improvement, whereas 71.0% of fibrin treated controls, and 93.1% of untreated lesions deteriorated. This was accompanied by significantly increased growth of stable microvessels, upregulation of the proangiogenic VEGFR-2 and its regulator TAL-1, and increase of endogenous endothelial VEGF expression.

Conclusions

Our findings in the avian model of SSc suggest that cell-demanded release of VEGF₁₂₁ from fibrin matrix induces controlled angiogenesis by differential regulation of VEGFR-1 and VEGFR-2 expression, shifting the balance towards the proangiogenic VEGFR-2. The study shows the potential of covalently conjugated VEGF-fibrin matrices for the therapy of ischaemic lesions such as fingertip ulcers.

Brief report: impaired in vivo neovascularization capacity of endothelial progenitor cells in patients with systemic sclerosis

OBJECTIVE

Defective vasculogenesis is thought to play a role in the pathogenesis of systemic sclerosis (SSc). We undertook this study to explore the in vivo functional capacity of CD34+CD133+CD309+ endothelial progenitor cells (EPCs) in SSc patients.

METHODS

CD133+ cells and EPCs were enumerated by flow cytometry. Immunomagnetically sorted circulating CD133+ cells from 16 patients with SSc and 12 healthy subjects, as well as murine colon carcinoma CT-26 cells, were transplanted beneath the skin of SCID mice. Tumor volume and blood vessel density were measured 10 days later. Human EPC incorporation into the vascular wall was evaluated using tumor sections double stained for mouse CD31 and human CD31.

RESULTS

The number of CD133+ cells and EPCs was significantly decreased in SSc patients as compared to healthy controls (P = 0.001 and P = 0.02, respectively), while the proportion of EPCs in CD133+ cells was similar between the 2 groups. CT-26 cells produced markedly stronger tumor growth and neovessel formation when transplanted with CD133+ cells from healthy subjects than when transplanted with CD133+ cells from SSc patients (P = 0.001 and P = 0.008, respectively). Tumors from mice that received transplants of CT-26 cells and SSc-derived CD133+ cells formed fewer vessels incorporating human EPC-derived mature endothelial cells than did tumors from mice that received transplants of CT-26 cells and CD133+ cells from healthy control subjects (P = 0.0002).

CONCLUSION

We established a system that can be used to evaluate the in vivo neovascularization capacity of freshly isolated EPCs. EPCs contribute to vascularization by incorporating into vessel walls and by differentiating into endothelial cells. These EPC functions are impaired in SSc.

Updates on morphea: role of vascular injury and advances in treatment

Morphea and systemic sclerosis are fibrosing disorders of the skin that share common inflammatory and immunologic pathways that are responsible for the vascular changes, increased collagen production, and extracellular matrix proliferation seen in both conditions. Recent advances in molecular biology techniques have furthered our knowledge of the potential underlying pathogenic mechanisms and offer new and provocative areas of research for novel diagnostic and therapeutic interventions. This review focuses on the role of vascular injury in the development of morphea, the use of ultrasonography as a diagnostic modality, and well-established and newly proposed treatments.

Dysregulation of angiogenic homeostasis in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissue disorder characterized by tissue hypoxia and excessive fibrosis of skin and internal organs.

OBJECTIVE

To evaluate the possible role of angiogenesis imbalance in the pathogenesis of SSc.

SUBJECTS AND METHODS

Twenty-five SSc patients and 20 age- and sex-matched healthy controls were included. Assay of serum vascular endothelial growth factor (VEGF) and endostatin was done for all patients and controls using enzyme-linked immunosorbent assay. Patients were subjected to modified Rodnan skin score (mRss), pulmonary function tests (PFTS) and skin biopsies for histopathological skin thickness score assessment.

RESULTS

There was significant increase in the mean levels of serum VEGF and endostatin in SSc patients compared to controls (t = 4.07, P < 0.001). Mean values of serum endostatin was significantly increased in late compared to early stages of disease (t = 6.65, P < 0.01). A significant positive correlation was found between serum levels of endostatin, mRss and histopathological skin thickness score (r = 0.99, 0.94, respectively, P < 0.01). SSc patients with ischemic manifestations had significantly higher levels of serum endostatin compared to those without ischemic manifestations (t = 6.27, P < 0.001). SSc patients with restricted PFTS had significantly higher levels of serum endostatin compared to those without pulmonary manifestations (t = 4.3, P < 0.001).

CONCLUSION

Angiogenic inhibitor (endostatin) is induced and outweighs angiogenic inducer (VEGF) in late stages of SSc. Increased serum endostatin is associated with skin sclerosis severity and pulmonary fibrosis and favors SSc disease progression.