Systemic Sclerosis Sera Impair Angiogenic Performance of Dermal Microvascular Endothelial Cells: Therapeutic Implications of Cyclophosphamide

The pentraxin family in autoimmune disease

The pentraxins represent a family of multifunctional proteins composed of long and short pentamers. The latter includes serum amyloid P component (SAP) and C-reactive protein (CRP) whereas the former includes neuronal PTX1 and PTX2 (NPTX1 and NPTX2, respectively), PTX3 and PTX4. These serve as a bridge between adaptive immunity and innate immunity and a link between inflammation and immunity. Similarities and differences between long and short pentamers are examined and their roles in autoimmune disease are discussed. Increased CRP and PTX3 could indicate the activity of rheumatoid arthritis, systemic lupus erythematosus or other autoimmune diseases. Mechanistically, CRP and PTX3 may predict target organ injury, regulate bone metabolic immunity and maintain homeostasis as well as participate in vascular endothelial remodeling. Interestingly, PTX3 is pleiotropic, being involved in inflammation and tissue repair. Given the therapeutic potential of PTX3 and CRP, targeting these factors to exert a beneficial effect is the focus of research efforts. Unfortunately, studies on NPTX1, NPTX2, PTX4 and SAP are scarce and more research is clearly needed to elaborate their potential roles in autoimmune disease.

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.

Current Trends in Vascular Biomarkers for Systemic Sclerosis: A Narrative Review

Systemic sclerosis (SSc, scleroderma) is a multifaceted rare connective tissue disease whose pathogenesis is dominated by immune dysregulation, small vessel vasculopathy, impaired angiogenesis, and both cutaneous and visceral fibrosis. Microvascular impairment represents the initial event of the disease, preceding fibrosis by months or years and accounting for the main disabling and/or life-threatening clinical manifestations, including telangiectasias, pitting scars, periungual microvascular abnormalities (e.g., giant capillaries, hemorrhages, avascular areas, ramified/bushy capillaries) clinically detectable by nailfold videocapillaroscopy, ischemic digital ulcers, pulmonary arterial hypertension, and scleroderma renal crisis. Despite a variety of available treatment options, treatment of SSc-related vascular disease remains problematic, even considering SSc etherogenity and the quite narrow therapeutic window. In this context, plenty of studies have highlighted the great usefulness in clinical practice of vascular biomarkers allowing clinicians to assess the evolution of the pathological process affecting the vessels, as well as to predict the prognosis and the response to therapy. The current narrative review provides an up-to-date overview of the main candidate vascular biomarkers that have been proposed for SSc, focusing on their main reported associations with characteristic clinical vascular features of the disease.

Screening and identification of potential biomarkers and therapeutic targets for systemic sclerosis-associated interstitial lung disease

Objectives

This study aims to analyze gene expression in lung tissue and lung fibroblasts of patients with systemic sclerosis-associated interstitial lung disease (SSc-ILD) to identify potential biomarkers and therapeutic targets and to examine its possible role in the pathogenesis of SSc-ILD.

Patients and methods

We obtained datasets from Gene Expression Omnibus (GEO) database, and used Robust Rank Aggregation to calculate the co-expressed differentially-expressed-genes (DEGs) in three chips, then analyzed the function, signaling pathways and the protein-protein interaction network of the DEGs. Finally, we verified the DEGs related to SSc-ILD by three databases of Comparative Toxicogenomics Database (CTD), GENE, and DisGeNET, respectively.

Results

There were 16 co-expressed DEGs related to SSc-ILD in three GEO series, of which six genes were upregulated, and 10 genes were downregulated. The CTD included 29,936 genes related to SSc, and the GENE and DisGeNET databases had 429 genes related to SSc.

Conclusion

The results of gene differential expression analysis suggest that interleukin-6, chemokine ligand 2, intercellular adhesion molecule 1, tumor necrosis factor alpha-induced protein 3, pentraxin 3, and cartilage oligomeric matrix protein may be implicated in the pathogenesis of SSc-ILD and are expected to be potential biomarkers and therapeutic targets for SSc-ILD.

Genome-wide DNA methylation pattern in systemic sclerosis microvascular endothelial cells: Identification of epigenetically affected key genes and pathways

Background

The etiology of systemic sclerosis is not clear, but there is evidence suggesting a critical role for epigenetic alterations in disease pathogenesis and clinical expression. We sought, in this study, to characterize the genome-wide DNA methylation signature in systemic sclerosis microvascular endothelial cells.

Methods

We performed a genome-wide DNA methylation study in microvascular endothelial cells derived from seven diffuse cutaneous systemic sclerosis patients compared to seven age-, sex-, and ethnicity-matched healthy controls. We paired matched samples on Illumina HumanMethylation450 (three diffuse cutaneous systemic sclerosis microvascular endothelial cells and three controls), and reproduced the results in an independent set of matched patient and controls using Illumina Infinium MethylationEPIC (four diffuse cutaneous systemic sclerosis patients and four controls) to identify differentially methylated genes.

Results

We identified 71,353 differentially methylated CpG sites in systemic sclerosis microvascular endothelial cells using Infinium MethylationEPIC microarray in the first group (0.081% of representative probes) and 33,170 CpG sites in the second group using HumanMethylation450 microarray (0.073% of representative probes) in diffuse cutaneous systemic sclerosis microvascular endothelial cells. Among the two groups of subjects, we identified differential methylation of 2455 CpG sites, representing 1301 genes. Most of the differentially methylated CpG sites were hypermethylated (1625 CpG), corresponding to 910 genes. Common hypermethylated genes in systemic sclerosis microvascular endothelial cells include NOS1, DNMT3A, DNMT3B, HDAC4, and ANGPT2. We also identified hypomethylation of IL17RA, CTNNA3, ICAM2, and SDK1 in systemic sclerosis microvascular endothelial cells. Furthermore, we demonstrate significant inverse correlation between DNA methylation status and gene expression in the majority of genes evaluated. Gene ontology analysis of hypermethylated genes demonstrated enrichment of genes involved in angiogenesis (p = 0.0006). Pathway analysis of hypomethylated genes includes genes involved in vascular smooth muscle contraction (p = 0.014) and adherens junctions (p = 0.013).

Conclusion

Our data suggest the presence of significant genome-wide DNA methylation aberrancies in systemic sclerosis microvascular endothelial cells, and identify novel affected genes and pathways in systemic sclerosis microvascular endothelial cells.

Management of Endothelial Dysfunction in Systemic Sclerosis: Current and Developing Strategies

Systemic Sclerosis (SSc) is an autoimmune disease marked by dysregulation of the immune system, tissue fibrosis and dysfunction of the vasculature. Vascular damage, remodeling and inadequate endothelial repair are hallmarks of the disease. Since early stages of SSc, damage and apoptosis of endothelial cells (ECs) can lead to perivascular inflammation, oxidative stress and tissue hypoxia, resulting in multiple clinical manifestations. Raynaud's phenomenon, edematous puffy hands, digital ulcers, pulmonary artery hypertension, erectile dysfunction, scleroderma renal crisis and heart involvement severely affect quality of life and survival. Understanding pathogenic aspects and biomarkers that reflect endothelial damage in SSc is essential to guide therapeutic interventions. Treatment approaches described for SSc-associated vasculopathy include pharmacological options to improve blood flow and tissue perfusion and, more recently, cellular therapy to enhance endothelial repair, promote angiogenesis and heal injuries. This mini-review examines the current knowledge on cellular and molecular aspects of SSc vasculopathy, as well as established and developing therapeutic approaches for improving the vascular compartment.

Biomarker profiles of endothelial activation and dysfunction in rare systemic autoimmune diseases: implications for cardiovascular risk

OBJECTIVES

Vasculopathy is an important hallmark of systemic chronic inflammatory connective tissue diseases (CICTD) and is associated with increased cardiovascular risk. We investigated disease-specific biomarker profiles associated with endothelial dysfunction, angiogenic homeostasis and (tissue) inflammation, and their relation to disease activity in rare CICTD.

METHODS

A total of 38 serum proteins associated with endothelial (dys)function and inflammation were measured by multiplex-immunoassay in treatment-naive patients with localized scleroderma (LoS, 30), eosinophilic fasciitis (EF, 8) or (juvenile) dermatomyositis (34), 119 (follow-up) samples during treatment, and 65 controls. Data were analysed by unsupervised clustering, Spearman correlations, non-parametric t test and ANOVA.

RESULTS

The systemic CICTD, EF and dermatomyositis, had distinct biomarker profiles, with 'signature' markers galectin-9 (dermatomyositis) and CCL4, CCL18, CXCL9, fetuin, fibronectin, galectin-1 and TSP-1 (EF). In LoS, CCL18, CXCL9 and CXCL10 were subtly increased. Furthermore, dermatomyositis and EF shared upregulation of markers related to interferon (CCL2, CXCL10), endothelial activation (VCAM-1), inhibition of angiogenesis (angiopoietin-2, sVEGFR-1) and inflammation/leucocyte chemo-attraction (CCL19, CXCL13, IL-18, YKL-40), as well as disturbance of the Angiopoietin-Tie receptor system and VEGF-VEGFR system. These profiles were related to disease activity, and largely normalized during treatment. However, a subgroup of CICTD patients showed continued elevation of CXCL10, CXCL13, galectin-9, IL-18, TNFR2, VCAM-1, and/or YKL-40 during clinically inactive disease, possibly indicating subclinical interferon-driven inflammation and/or endothelial dysfunction.

CONCLUSION

CICTD-specific biomarker profiles revealed an anti-angiogenic, interferon-driven environment during active disease, with incomplete normalization under treatment. This warrants further investigation into monitoring of vascular biomarkers during clinical follow-up, or targeted interventions to minimize cardiovascular risk in the long term.

Altered Properties of Endothelial Cells and Mesenchymal Stem Cells Underlying the Development of Scleroderma-like Vasculopathy in KLF5+/- ;Fli-1+/- Mice

OBJECTIVE

In prevous studies, we established a new animal model, KLF5^+/- ;Fli-1^+/- mice, in which fundamental pathologic features of systemic sclerosis (SSc) are broadly recapitulated. SSc vasculopathy is believed to occur as a result of impaired vascular remodeling, but its detailed mechanism of action remains unknown. To address this, the present study investigated the properties of dermal microvascular endothelial cells (DMECs), bone marrow-derived endothelial progenitor cells (BM-EPCs), and bone marrow-derived mesenchymal stem cells (BM-MSCs), a precursor of pericytes, in KLF5^+/- ;Fli-1^+/- mice.

METHODS

Neovascularization and angiogenesis were assessed in KLF5^+/- ;Fli-1^+/- mice by in vivo Matrigel plug assay and in vitro tube formation assay, respectively. The properties of mouse BM-EPCs and BM-MSCs were assessed with in vitro studies. Dermal vasculature was visualized in vivo by injecting the mice with fluorescein isothiocyanate-conjugated dextran.

RESULTS

Neovascularization was diminished in skin-embedded Matrigel plugs from KLF5^+/- ;Fli-1^+/- mice. DMECs from KLF5^+/- ;Fli-1^+/- mice showed defective tubulogenic activity, decreased expression of VE-cadherin and CD31, and an imbalance in the expression of Notch1/Dll4, suggesting that angiogenesis and anastomosis are disturbed. KLF5^+/- ;Fli-1^+/- mouse BM-MSCs exhibited enhanced proliferation and migration and increased collagen production following stimulation with transforming growth factor β1, indicating that these cells differentiate preferentially into myofibroblasts rather than pericytes. KLF5^+/- ;Fli-1^+/- mouse BM-EPCs displayed a transition toward mesenchymal cells, suggesting that vasculogenesis is impaired. Wound healing was delayed in KLF5^+/- ;Fli-1^+/- mice (mean ± SD healing time 15.67 ± 0.82 days versus 13.50 ± 0.84 days; P = 0.0017), and the vascular network was poorly developed in wound scar tissue.

CONCLUSION

The characteristics observed in the KLF5^+/- ;Fli-1^+/- mouse model - specifically, impaired neovascularization and vascular maturation - are similar to those observed in human SSc, and could be at least partially attributable to the induction of SSc-like properties in DMECs, BM-EPCs, and BM-MSCs. These findings indicate the critical contribution of Klf5 and Fli1 deficiency in vascular cells and related cell precursors to the development of SSc vasculopathy.

Pentraxin 3: A promising therapeutic target for autoimmune diseases

Pentraxin 3 (PTX3) is a prototypic humoral soluble pattern recognition molecule that exerts a pivotal role in innate immune response and inflammation, as well as in tissue damage and remodeling. Recently, emerging evidence has revealed that PTX3 is involved in the occurrence and development of various autoimmune diseases, such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), ankylosing spondylitis (AS), systemic sclerosis (SSc), inflammatory bowel disease (IBD), multiple sclerosis (MS) and psoriasis, etc. In this review, we have succinctly summarized the complex immunological functions of PTX3 and mostly focused on recent findings of the pleiotropic activities played by PTX3 in the pathogenesis of autoimmune diseases, aiming at hopefully offering possible future therapeutic alternatives.

Role of increased vascular permeability in chemotherapy-induced alopecia: In vivo imaging of the hair follicular microenvironment in mice

Chemotherapy-induced alopecia is one of the most difficult adverse events of cancer treatment for patients. However, it is still unknown why anticancer drugs cause hair loss. We aimed to clarify the mechanism of chemotherapy-induced alopecia in mice using an in vivo imaging technique with a two-photon microscope, which enables observation of the deep reaction in the living body in real time. In this study, ICR mice were injected intraperitoneally with cyclophosphamide (120 µg/g). Changes in the hair bulb morphology, subcutaneous vessel permeability, and vessel density were evaluated by two-photon microscopy and conventional methods. In order to determine whether there is a causal relationship between vascular permeability and hair loss, we combined cyclophosphamide (50 µg/g) with subcutaneous histamine. Using two‐photon microscopy and conventional examination, we confirmed that the hair bulbs became smaller, blood vessels around the hair follicle decreased, and vascular permeability increased at 24 hours after cyclophosphamide injection [corrected]. Apoptosis occurred in vascular endothelial cells around the hair follicle. Additionally, hair loss was exacerbated by temporarily enhancing vascular permeability with histamine. In conclusion, cyclophosphamide caused a decrease in vascular density and an increase in vascular permeability, therefore increased vascular permeability might be one of the causes of chemotherapy-induced alopecia.

Systemic Sclerosis Serum Significantly Impairs the Multi-Step Lymphangiogenic Process: in Vitro Evidence

In systemic sclerosis (SSc), the possible involvement of lymphatic microcirculation and lymphangiogenesis has traditionally been overshadowed by the greater emphasis placed on dysfunctional blood vascular system and angiogenesis. In the present in vitro study, we explore for the first time whether the SSc microenvironment may interfere with lymphangiogenesis, a complex, multi-step process in which lymphatic microvascular endothelial cells (LMVECs) sprout, migrate, and proliferate to generate new lymphatic capillaries. Normal human adult dermal LMVECs from three donors were treated with serum from SSc patients (n = 8), serum from healthy individuals (n = 8), or recombinant human vascular endothelial growth factor (VEGF)-C as a positive control for lymphangiogenesis. Cell proliferation, Boyden chamber Matrigel chemoinvasion, wound healing capacity, and lymphatic capillary morphogenesis on Geltrex were assayed. VEGF-C serum levels were measured by enzyme-linked immunosorbent assay. Gene and protein expression levels of the lymphangiogenic orchestrators VEGF receptor-3 (VEGFR-3)/Flt-4 and neuropilin-2 (NRP-2) were determined by real-time PCR and Western blotting, respectively. Conditioning with SSc serum significantly inhibited LMVEC proliferation, Matrigel invasion, and wound healing capacity with respect to healthy serum. The ability of LMVECs to form lymphatic tubes on Geltrex was also severely compromised in the presence of SSc serum. VEGF-C levels were comparable in SSc and healthy sera. Treatment with SSc serum resulted in a significant downregulation of both VEGFR-3/Flt-4 and NRP-2 mRNA and protein levels. In SSc, the pathologic environment severely hampers every lymphangiogenesis step, likely through the reduction of pro-lymphangiogenic VEGFR-3/NRP-2 co-receptor signaling. The impairment of the lymphangiogenic process opens a new scenario underlying SSc vascular pathophysiology, which is worth investigating further.

Macrophages Guard Endothelial Lineage by Hindering Endothelial-to-Mesenchymal Transition: Implications for the Pathogenesis of Systemic Sclerosis

The signals that control endothelial plasticity in inflamed tissues have only been partially characterized. For example, it has been shown that inadequate vasculogenesis in systemic sclerosis (SSc) has been associated with an endothelial defect. We used a genetic lineage tracing model to investigate whether endothelial cells die or change phenotypically after fibrosis induction and whether signals released by cells of the innate immune system and in the blood of patients influence their commitment. We observed that in the lineage-tracing transgenic mice Cdh5-CreER^T2::R26R-EYFP, endothelial-derived cells (EdCs) underwent fibrosis after treatment with bleomycin, and EdCs retrieved from the lung showed expression of endothelial-to-mesenchymal transition (EndoMT) markers. Liposome-encapsulated clodronate was used to assess macrophage impact on EdCs. Clodronate treatment affected the number of alternatively activated macrophages in the lung, with upregulated expression of EndoMT markers in lung EdCs. Endothelial fate and function were investigated in vitro upon challenge with serum signals from SSc patients or released by activated macrophages. Sera of SSc patients with anti-Scl70 Abs, at higher risk of visceral organ fibrosis, induced EndoMT and jeopardized endothelial function. In conclusion, EdCs in SSc might be defective because of commitment to a mesenchymal fate, which is sustained by soluble signals in the patient's blood. Macrophages contribute to preserve the endothelial identity of precursor cells. Altered macrophage-dependent plasticity of EdCs could contribute to link vasculopathy with fibrosis.

Cyclophosphamide Pulse Therapy Normalizes Vascular Abnormalities in a Mouse Model of Systemic Sclerosis Vasculopathy

Intravenous cyclophosphamide pulse, a standard treatment for systemic sclerosis (SSc)-related interstitial lung disease, elicits a disease-modifying effect on SSc vasculopathy, such as fostering microvascular de-remodeling. To investigate the molecular mechanism by which cyclophosphamide mitigates SSc vasculopathy, we employed endothelial cell-specific Fli1 knockout mice that mimic the functional and structural vascular abnormalities characteristic of SSc. Biweekly cyclophosphamide injection improved vascular permeability and structural abnormalities of endothelial cell-specific Fli1 knockout mice in 2 weeks and in 3 months, respectively. In endothelial cell-specific Fli1 knockout mice, a single dose of cyclophosphamide was sufficient to normalize the decreased expression of α-smooth muscle actin in dermal blood vessels and improve the impaired neovascularization in skin-embedded Matrigel plug. Under the same condition, the decreased expression of vascular endothelial cadherin, platelet-derived growth factor B, S1P₁, and CCN1 (molecules associated with angiogenesis and/or vasculogenesis) was reversed along with the reversal of endothelial Fli1 expression. In SSc patients, serum CCN1 levels were significantly increased after intravenous cyclophosphamide pulse. Taken together, these results indicate that cyclophosphamide improves Fli1 deficiency-dependent vascular changes by normalizing the expression of angiogenesis- and vasculogenesis-related molecules and endothelial Fli1, which may help to explain the beneficial effect of cyclophosphamide on SSc vasculopathy.

Slit2/Robo4 axis may contribute to endothelial cell dysfunction and angiogenesis disturbance in systemic sclerosis

OBJECTIVE

In systemic sclerosis (SSc), early microvascular injury is followed by impaired angiogenesis and peripheral capillary loss. Here, we investigated the possible contribution of the neurovascular guidance molecule Slit2 and its Roundabout (Robo) receptors to SSc-related endothelial cell dysfunction.

METHODS

Circulating Slit2 levels were measured in patients with SSc and healthy controls. Slit2, Robo1 and Robo4 expression was investigated in SSc and healthy skin biopsies and explanted dermal microvascular endothelial cells (MVECs). Slit2/Robo4 function in MVEC angiogenesis was studied by cell viability, wound healing and capillary-like tube formation assays.

RESULTS

Circulating Slit2 was significantly increased in either SSc or patients with a very early diagnosis of SSc (VEDOSS) compared with controls. Interestingly, serum Slit2 levels were raised in patients with VEDOSS with nailfold videocapillaroscopy (NVC) abnormalities, while they were similar in VEDOSS with normal NVC and controls. In SSc, Slit2 and Robo4 expression was upregulated in clinically affected skin and explanted MVECs in respect to controls. The angiogenic performance of healthy MVECs was significantly reduced after challenge with recombinant human Slit2 or SSc sera. These inhibitory effects were significantly attenuated when SSc sera were preincubated with an anti-Slit2 blocking antibody. In vitro angiogenesis was severely compromised in SSc-MVECs and could be significantly ameliorated by Slit2 neutralisation or ROBO4 gene silencing. Slit2/Robo4 axis interfered with angiogenesis through the inhibition of Src kinase phosphorylation.

CONCLUSIONS

In SSc, increased circulating levels of Slit2 and activation of the Slit2/Robo4 antiangiogenic axis may contribute to peripheral microangiopathy since the very early phase of the disease.

Increased serum levels of adhesion molecules ICAM-1 and VCAM-1 in systemic sclerosis are not specific for pulmonary manifestations

Studies suggest elevated serum intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels may be markers of pulmonary arterial hypertension in systemic sclerosis (SSc-PAH). We sought to evaluate whether ICAM-1 and VCAM-1 levels are useful screening biomarkers for incident SSc-PAH. In this cross-sectional study, four groups were selected from the Australian Scleroderma Cohort Study: group 1 (n = 15) had definite PAH; group 2 (n = 19) had interstitial lung disease (ILD); group 3 (n = 30) were SSc-controls; and group 4 (n = 34) were healthy controls. Serum ICAM-1 and VCAM-1 levels were measured using the Millipore Milliplex MAP Human 2-Plex Panel. There were no differences in ICAM-1 levels in the PAH versus ILD group (263.0 ± 85.4 vs 380.4 ± 168.3 ng/mL, p = 0.136), SSc-controls (263.0 ± 85.4 vs 253.1 ± 98.0 ng/mL, p = 1.00), or healthy controls (263.0 ± 85.4 vs 201.8 ± 57.2 ng/mL, p = 0.093). Similarly, there were no differences in VCAM-1 level in PAH versus ILD groups (1476.2 ± 434.9 vs 1424.8 ± 527.6 ng/mL, p = 1.00) and SSc-controls (1476.2 ± 434.9 vs 1409.5 ± 341.1 ng/mL, p = 1.00). SSc subjects had significantly higher levels of ICAM-1 (297.4 ± 134.0 vs 201.8 ± 57.2 ng/mL, p < 0.0001) and VCAM-1 compared to healthy controls (1432.7 ± 427.4 vs 1125.6 ± 273.4 ng/mL, p < 0.0001). Neither ICAM-1 nor VCAM-1 is a specific screening biomarker of SSc-PAH. Instead, increased levels of these adhesion molecules in SSc, irrespective of pulmonary complications, suggest that they may play a role in SSc pathogenesis.

Circulating angiostatin serum level in patients with systemic sclerosis

Introduction

Systemic sclerosis (SSc) is achronic connective tissue disease characterized by microangiopathy with inadequate angiogenesis. Angiostatin (AS) is a potent antiangiogenic factor specifically inhibiting proliferation and inducing apoptosis of vascular endothelial cells.

Aim

To evaluate the level of angiostatin in the serum of patients with SSc.

Material and methods

Serum levels of AS were measured in 20 SSc patients and 12 healthy controls.

Results

A statistically significant difference in the serum levels of AS in SSc patients was observed compared to the control group (636.51 vs. 869.20 ng/ml; p = 0.012). Significant correlations between limited and disseminated SSc (lSSc/dSSc) were not found, however, a difference between lSSc and the control group was demonstrated (620.00 vs. 869.20 ng/ml; p = 0.011). The serum level of AS was not associated positively with organ changes caused by SSc. However, a statistically significant lower serum level of AS was observed in patients with SSc and no esophageal (p = 0.008) or pulmonary changes (p = 0.007) compared to the control group.

Conclusions

Our results reveal significant differences in AS level in SSc patients compared to the healthy controls, and suggest that a low level of AS may occur as a result of impaired angiogenesis.

Angiogenic T cell expansion correlates with severity of peripheral vascular damage in systemic sclerosis

The mechanisms underlying endothelial cell injury and defective vascular repair in systemic sclerosis (SSc) remain unclear. Since the recently discovered angiogenic T cells (Tang) may have an important role in the repair of damaged endothelium, this study aimed to analyze the Tang population in relation to disease-related peripheral vascular features in SSc patients. Tang (CD3⁺CD31⁺CXCR4⁺) were quantified by flow cytometry in peripheral blood samples from 39 SSc patients and 18 healthy controls (HC). Circulating levels of the CXCR4 ligand stromal cell-derived factor (SDF)-1α and proangiogenic factors were assessed in paired serum samples by immunoassay. Serial skin sections from SSc patients and HC were subjected to CD3/CD31 and CD3/CXCR4 double immunofluorescence. Circulating Tang were significantly increased in SSc patients with digital ulcers (DU) compared either with SSc patients without DU or with HC. Tang levels were significantly higher in SSc patients with late nailfold videocapillaroscopy (NVC) pattern than in those with early/active NVC patterns and in HC. No difference in circulating Tang was found when comparing either SSc patients without DU or patients with early/active NVC patterns and HC. In SSc peripheral blood, Tang percentage was inversely correlated to levels of SDF-1α and CD34⁺CD133⁺VEGFR-2⁺ endothelial progenitor cells (EPC), and positively correlated to levels of vascular endothelial growth factor and matrix metalloproteinase-9. Tang were frequently detected in SSc dermal perivascular inflammatory infiltrates. In summary, our findings demonstrate for the first time that Tang cells are selectively expanded in the circulation of SSc patients displaying severe peripheral vascular complications like DU. In SSc, Tang may represent a potentially useful biomarker reflecting peripheral vascular damage severity. Tang expansion may be an ineffective attempt to compensate the need for increased angiogenesis and EPC function. Further studies are required to clarify the function of Tang cells and investigate the mechanisms responsible for their change in SSc.

Endothelial-to-mesenchymal transition contributes to endothelial dysfunction and dermal fibrosis in systemic sclerosis

Objective

Systemic sclerosis (SSc) features multiorgan fibrosis orchestrated predominantly by activated myofibroblasts. Endothelial-to-mesenchymal transition (EndoMT) is a transdifferentiation by which endothelial cells (ECs) lose their specific morphology/markers and acquire myofibroblast-like features. Here, we determined the possible contribution of EndoMT to the pathogenesis of dermal fibrosis in SSc and two mouse models.

Methods

Skin sections were immunostained for endothelial CD31 or vascular endothelial (VE)-cadherin in combination with α-smooth muscle actin (α-SMA) myofibroblast marker. Dermal microvascular ECs (dMVECs) were prepared from SSc and healthy skin (SSc-dMVECs and H-dMVECs). H-dMVECs were treated with transforming growth factor-β1 (TGFβ1) or SSc and healthy sera. Endothelial/mesenchymal markers were assessed by real-time PCR, immunoblotting and immunofluorescence. Cell contractile phenotype was assayed by collagen gel contraction.

Results

Cells in intermediate stages of EndoMT were identified in dermal vessels of either patients with SSc or bleomycin-induced and urokinase-type plasminogen activator receptor (uPAR)-deficient mouse models. At variance with H-dMVECs, SSc-dMVECs exhibited a spindle-shaped appearance, co-expression of lower levels of CD31 and VE-cadherin with myofibroblast markers (α-SMA+ stress fibres, S100A4 and type I collagen), constitutive nuclear localisation of the EndoMT driver Snail1 and an ability to effectively contract collagen gels. Treatment of H-dMVECs either with SSc sera or TGFβ1 resulted in the acquisition of a myofibroblast-like morphology and contractile phenotype and downregulation of endothelial markers in parallel with the induction of mesenchymal markers. Matrix metalloproteinase-12-dependent uPAR cleavage was implicated in the induction of EndoMT by SSc sera.

Conclusions

In SSc, EndoMT may be a crucial event linking endothelial dysfunction and development of dermal fibrosis.

Plasma plasmin-α2-plasmin inhibitor complex levels may predict the effect of cyclophosphamide for systemic sclerosis-related interstitial lung disease

OBJECTIVES

Intravenous pulse cyclophosphamide (IVCY) is the first-line treatment for systemic sclerosis-associated interstitial lung disease (SSc-ILD). So far, there is no useful predictive marker for IVCY efficacy against SSc-ILD, although potential candidates are parameters reflecting vascular activation. Since plasma levels of plasmin-α2-plasmin inhibitor complex (PIC) serve as a potential biomarker of SSc vasculopathy, we evaluated the usefulness of plasma PIC levels as an indicator for IVCY efficacy against SSc-ILD.

METHODS

We measured plasma PIC levels in 23 patients with active SSc-ILD and 20 patients with stabilized SSc-ILD, and also retrospectively studied traceable data of patients with active SSc-ILD during IVCY therapy.

RESULTS

Plasma PIC levels were significantly elevated in patients with active SSc-ILD as compared to patients with stabilized SSc-ILD. Among patients with active SSc-ILD, baseline plasma PIC concentrations were significantly higher in patients responsive to IVCY than in those refractory to IVCY. After the entire six infusions, plasma PIC levels were significantly decreased compared with baseline in the responders, while not in the nonresponders. In the responders, plasma PIC levels were remarkably decreased after a couple of infusions. Regarding the changes of parameters by the entire infusions, Δ plasma PIC levels correlated positively with Δ serum KL-6 levels and inversely with Δ the percentage of predicted vital capacity.

CONCLUSIONS

The elevation of baseline plasma PIC levels and the rapid decrease in plasma PIC levels during a couple of infusions may predict the efficacy of the entire IVCY therapy against SSc-ILD.

Decreased expression of neuropilin-1 as a novel key factor contributing to peripheral microvasculopathy and defective angiogenesis in systemic sclerosis

OBJECTIVES

In systemic sclerosis (SSc), vascular involvement is characterised by vascular endothelial growth factor (VEGF)-A/VEGF receptor (VEGFR) system disturbances. Neuropilin-1 (NRP1), a receptor for both class-3 semaphorins (Sema3s) and VEGF-A, is required for optimal VEGF-A/VEGFR-2 signalling. Here, we investigated the possible involvement of Sema3A/NRP1 axis in SSc.

METHODS

Circulating Sema3A and soluble NRP1 (sNRP1) were measured in patients with SSc and controls. NRP1 and Sema3A expression in skin biopsies was evaluated by immunofluorescence and western blotting. NRP1 expression was assessed in SSc and healthy dermal microvascular endothelial cells (SSc-MVECs and H-MVECs), and in SSc and control endothelial progenitor cell (EPC)-derived endothelial cells (ECs). The possible impact of transcription factor Friend leukaemia integration 1 (Fli1) deficiency on endothelial NRP1 expression was investigated by gene silencing. The binding of Fli1 to NRP1 gene promoter was evaluated using chromatin immunoprecipitation. Capillary morphogenesis was performed on Matrigel.

RESULTS

Decreased sNRP1 levels in SSc were associated with active and late nailfold videocapillaroscopy patterns and digital ulcers. No difference in Sema3A was found between patients and controls. NRP1 was significantly decreased in SSc-MVECs both ex vivo and in vitro. NRP1 and Fli1 significantly decreased in H-MVECs challenged with SSc sera, while they were not different in SSc and control EPC-derived ECs. Fli1 occupied the NRP1 gene promoter and Fli1 gene silencing reduced NRP1 expression in H-MVECs. NRP1 gene silencing in H-MVECs resulted in a significantly impaired angiogenic capacity comparable to that of cells treated with SSc sera.

CONCLUSION

In SSc, NRP1 deficiency may be an additional factor in the perturbed VEGF-A/VEGFR-2 system contributing to peripheral microvasculopathy and defective angiogenesis.