Cellular and molecular aspects of vascular dysfunction in systemic sclerosis

Impact of Human Cytomegalovirus and Human Herpesvirus 6 Infection on the Expression of Factors Associated with Cell Fibrosis and Apoptosis: Clues for Implication in Systemic Sclerosis Development

Systemic sclerosis (SSc) is a severe autoimmune disorder characterized by vasculopathy and multi-organ fibrosis; its etiology and pathogenesis are still largely unknown. Herpesvirus infections, particularly by human cytomegalovirus (HCMV) and human herpesvirus 6 (HHV-6), have been suggested among triggers of the disease based on virological and immunological observations. However, the direct impact of HCMV and/or HHV-6 infection on cell fibrosis and apoptosis at the cell microenvironment level has not yet been clarified. Thus, this study aimed to investigate the effects of HCMV and HHV-6 infection on the induction of pro-fibrosis or pro-apoptosis conditions in primary human dermal fibroblasts, one of the relevant SSc target cells. The analysis, performed by microarray in in vitro HCMV- or HHV-6-infected vs. uninfected cells, using specific panels for the detection of the main cellular factors associated with fibrosis or apoptosis, showed that both viruses significantly modified the expression of at least 30 pro-fibrotic and 20 pro-apoptotic factors. Notably, several recognized pro-fibrotic factors were highly induced, and most of them were reported to be involved in vivo in the multifactorial and multistep pathogenic process of SSc, thus suggesting a potential role of both HCMV and HHV-6.

Vascular dysfunction in aged mice contributes to persistent lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive disease thought to result from impaired lung repair following injury and is strongly associated with aging. While vascular alterations have been associated with IPF previously, the contribution of lung vasculature during injury resolution and fibrosis is not well understood. To compare the role of endothelial cells (ECs) in resolving and non-resolving models of lung fibrosis, we applied bleomycin intratracheally to young and aged mice. We found that injury in aged mice elicited capillary rarefaction, while injury in young mice resulted in increased capillary density. ECs from the lungs of injured aged mice relative to young mice demonstrated elevated pro-fibrotic and reduced vascular homeostasis gene expression. Among the latter, Nos3 (encoding the enzyme endothelial nitric oxide synthase, eNOS) was transiently upregulated in lung ECs from young but not aged mice following injury. Young mice deficient in eNOS recapitulated the non-resolving lung fibrosis observed in aged animals following injury, suggesting that eNOS directly participates in lung fibrosis resolution. Activation of the NO receptor soluble guanylate cyclase in human lung fibroblasts reduced TGFβ-induced pro-fibrotic gene and protein expression. Additionally, loss of eNOS in human lung ECs reduced the suppression of TGFβ-induced lung fibroblast activation in 2D and 3D co-cultures. Altogether, our results demonstrate that persistent lung fibrosis in aged mice is accompanied by capillary rarefaction, loss of EC identity, and impaired eNOS expression. Targeting vascular function may thus be critical to promote lung repair and fibrosis resolution in aging and IPF.

Vascular permeability in the fibrotic lung

Idiopathic pulmonary fibrosis (IPF) is thought to result from aberrant tissue repair processes in response to chronic or repetitive lung injury. The origin and nature of the injury, as well as its cellular and molecular targets, are likely heterogeneous, which complicates accurate pre-clinical modelling of the disease and makes therapeutic targeting a challenge. Efforts are underway to identify central pathways in fibrogenesis which may allow targeting of aberrant repair processes regardless of the initial injury stimulus. Dysregulated endothelial permeability and vascular leak have long been studied for their role in acute lung injury and repair. Evidence that these processes are of importance to the pathogenesis of fibrotic lung disease is growing. Endothelial permeability is increased in non-fibrosing lung diseases, but it resolves in a self-limited fashion in conditions such as bacterial pneumonia and acute respiratory distress syndrome. In progressive fibrosing diseases such as IPF, permeability appears to persist, however, and may also predict mortality. In this hypothesis-generating review, we summarise available data on the role of endothelial permeability in IPF and focus on the deleterious consequences of sustained endothelial hyperpermeability in response to and during pulmonary inflammation and fibrosis. We propose that persistent permeability and vascular leak in the lung have the potential to establish and amplify the pro-fibrotic environment. Therapeutic interventions aimed at recognising and "plugging" the leak may therefore be of significant benefit for preventing the transition from lung injury to fibrosis and should be areas for future research.

Antibody against Na/K-ATPase Inhibitor Lowers Blood Pressure and Increases Vascular Fli1 in Experimental Preeclampsia

BACKGROUND

Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). We demonstrated that MBG induces fibrosis via mechanism involving inhibition of Fli1, a nuclear transcription factor and a negative regulator of collagen-1 synthesis. We hypothesized that PE blockade of increased MBG with antibody would lessen the fibrosis of umbilical arteries and lower the blood pressure in rats with PE.

METHODS

We tested 36 pregnant Sprague-Dawley rats in which 12 were made hypertensive by 1.8% Na supplementation (days 6-19 of gestation), 12 pregnant rats served controls. At day 19, PE rats received one intraperitoneal injection of polyclonal anti-MBG-4 antibody (0.5 ug/ml) for 4 hours.

RESULTS

PE was associated with higher blood pressure (117 ± 2 vs. 107 ± 2 mm Hg; P < 0.01), plasma MBG levels (1.54 ± 0.34 vs. 0.49 ± 0.11 nmol/L; P < 0.01), protein excretion (26 vs. 12 mg/24 hours), sFlt-1 (3-fold), decrease in Fli1 (7-fold) and increase in collagen-1 in aorta (4-fold) vs. control rats (all P < 0.01). In 12 rats treated with polyclonal anti-MBG-4 antibody blood pressure dropped (93 ± 3 mm Hg) and Fli1 was decreased much less (2-fold; P < 0.01 vs. nontreated rats).

CONCLUSIONS

These results demonstrate that in experimental PE elevated MBG level is implicated in umbilical fibrosis via suppression of Fli1.

'Narrow-sense' and 'broad-sense' vascular abnormalities of systemic sclerosis

Systemic sclerosis (SSc) induces skin thickening and numerous symptoms involving the entire body. Collagen deposition, immune disorder, and vascular abnormalities is currently estimated to be three major causal factors involved in the respective conditions. Vascular abnormalities usually develop in the initial phase of this disease, and may exist in all phases; therefore, they markedly influence the patient's quality of life. This article reviews recent findings about 'narrow-sense' vascular lesions (including Raynaud's phenomenon, skin ulcers, nailfold bleedings, pitting scars, telangiectasia, and pulmonary hypertension) and 'broad-sense' vascular lesions (such as calcinosis or erectile dysfunction). Affected blood vessels can be classified into arteriole/small artery and capillary blood vessels. Furthermore, pathological changes include the proliferation of the vascular endothelial or smooth muscle cells, lumen stenosis by collagen accumulation of the vascular intima, vasodilation or fragility, and apoptosis. There may be interaction between vascular lesions, autoimmune disorder, and collagen deposition. Thus, various symptoms of this disease may be controlled through the treatment of vascular lesions.

Treprostinil Hydrogel Iontophoresis in Systemic Sclerosis-Related Digital Skin Ulcers: A Safety Study

Digital skin ulcers are a severe complication of systemic sclerosis. The first-line treatment is intravenous iloprost, but it induces dose-limiting adverse effects. Local administration of treprostinil through skin iontophoresis may be a safe alternative. We conducted a 2-stage, randomized, placebo-controlled single-ascending-dose study in healthy volunteers and patients with systemic sclerosis-related digital ulcer. We further explored the effect of the procedure on skin blood flux. In a first group of healthy subjects, treprostinil and placebo iontophoresis were performed at 3 locations (ie, 6 skin sites): the sole of the foot, the leg, and the fingers. We used a 1-mg/mL hydrogel of treprostinil. We then randomly treated systemic sclerosis-related digital ulcers in a 3:1 ratio of treprostinil or placebo. We used concentrations from 0.1 to 1 mg/mL. All adverse events were recorded and rated according to the Common Terminology Criteria for Adverse Events (CTCAE), whereas skin microvascular blood flux was recorded with laser speckle contrast imaging. Among the 12 healthy volunteers, we observed 60 local adverse effects: burns, skin pain, erythema, and pruritus, graded 1 or 2 on the 5-point CTCAE scale. Treprostinil iontophoresis significantly increased skin blood flux on the leg (AUC_0-4 h at 88 460% ± 6436% versus 12 730% ± 3397% baseline flux.min respectively; P < .001) and on the sole of the foot (AUC_{0-3 h} at 20 124% ± 6119% versus 3142% ± 3036% baseline flux.min, respectively; P = .018) with a trend on the finger. Among 5 patients with systemic sclerosis-related digital ulcer, 2 resolutive local adverse effects were reported. Iontophoresis of treprostinil hydrogel was safe in systemic sclerosis patients with digital ulcer.

Phase angle could be a marker of microvascular damage in systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is an autoimmune disease characterized by endothelial dysfunction with fibrosis of skin and internal organs. Integrity of the endothelial cell is important to its physiologic function such as production of angiogenetic factors. The aim of this study was to assess whether phase angle (PhA) is altered in patients with SSc and whether its values correlate with vascular endothelial growth factor (VEGF) and digital microvascular damage.

METHODS

Patients with SSc and matched healthy controls underwent VEGF determination and bioimpedentiometry (BIA) for PhA assessment. Clinical assessment, disease activity index (DAI), disease severity scale, and nailfold videocapillaroscopy (NCV) were performed in patients with SSc.

RESULTS

Fifty-five patients (46 women) with a mean age of 53.2 ± 13.7 y were studied. The mean value of VEGF was significantly higher in patients with SSc than in the healthy controls (240.3 ± 149.5 versus 139 ± 87.5; P = 0.035). The mean value of PhA was significantly lower in the patient grouop than in the healthy controls (4.51 ± 0.87 versus 5.22 ± 0.55; P < 0.0001). A significant positive correlation was found between VEGF and PhA (P = 0.009, beta coefficient = 1.48) in SSc patients. A negative correlation between VEGF and DAI (P = 0.048, β coefficient = 0.48) was found. PhA median value was significantly (P = 0.006) lower in patients with late pattern SSc (4.2 [2.5-5.3]). PhA median value was significantly (P < 0,0001) lower in patients with digital ulcers (DUs; 4.2 [2.5-5.3]) than in those without DUs (3.80 [2.50-5] versus 4.75 [2.80-7.3]). These data were confirmed in both female and male patients.

CONCLUSIONS

The evaluation of VEGF with PhA, NVC, and DUs could be useful to estimate cellular and microvascular damage in patients with SSc.

HHV-6A Infection and Systemic Sclerosis: Clues of a Possible Association

Systemic sclerosis (SSc) is an autoimmune disease characterized by vasculopathy, excessive extracellular matrix deposition, and fibrosis of the skin and internal organs. Several infectious agents, including human herpesvirus-6 (HHV-6), have been suggested as possible triggering factors, but a direct association is still missing. We characterized 26 SSc patients for the presence of HHV-6 in tissues and blood, the anti-HHV-6 response, HLA-G plasma levels, and KIR typing. Given the prominent role of endothelial cells (EC) in SSc pathogenesis, along with HHV-6 tropism for EC, we also investigated the expression of pro-fibrosis factors in HHV-6 infected EC. Results showed the presence of HHV-6A in skin biopsies, and an increased virus load was associated with disease severity and poor natural killer (NK) response against the virus, particularly in subjects exhibiting a KIR2 phenotype. HLA-G plasma levels were significantly higher in HHV-6A/B-KIR2 positive SSc patients and in vitro HHV-6A infection-induced pro-fibrosis factors expression in EC, supporting its role in the development of the fibrosing process. Our data suggest an association between virus infection/reactivation and disease, opening the way to future studies to understand the mechanisms by which HHV-6A might contribute to the multifactorial pathogenesis of SSc.

Existing and novel biomarkers for precision medicine in systemic sclerosis

The discovery and validation of biomarkers resulting from technological advances in the analysis of genomic, transcriptomic, lipidomic and metabolomic pathways involved in the pathogenesis of complex human diseases have led to the development of personalized and rationally designed approaches for the clinical management of such disorders. Although some of these approaches have been applied to systemic sclerosis (SSc), an unmet need remains for validated, non-invasive biomarkers to aid in the diagnosis of SSc, as well as in the assessment of disease progression and response to therapeutic interventions. Advances in global transcriptomic technology over the past 15 years have enabled the assessment of microRNAs that circulate in the blood of patients and the analysis of the macromolecular content of a diverse group of lipid bilayer membrane-enclosed extracellular vesicles, such as exosomes and other microvesicles, which are released by all cells into the extracellular space and circulation. Such advances have provided new opportunities for the discovery of biomarkers in SSc that could potentially be used to improve the design and evaluation of clinical trials and that will undoubtedly enable the development of personalized and individualized medicine for patients with SSc.

Bufei Qingyu Granules Inhibit the Development of Systemic Sclerosis via Notch-1/Jagged-2 Signaling Pathway

Systemic sclerosis (SSc) is a rare chronic autoimmune disorder, mainly characterized by skin sclerosis. In this study, Bufei Qingyu Granules (BQG), a Chinese herbal formula, was used to treat SSc. To better understand the effects and molecular mechanisms of BQG, we successfully established a Bleomycin- (BLM-) induced SSc mouse model, and the mice were treated by BQG. Meanwhile, transcriptomic and bioinformatics analyses were conducted on those samples. As a result, we visually showed that BQG ameliorated the overall health of mice, including body weight, spleen, and thymus index. Thus, it also significantly alleviated inflammation presented by Chemokine (C-X-C motif) ligand 2 (Cxcl2), vasculopathy characterized by α-smooth muscle actin (α-SMA), and fibrotic changes elaborated by not only pathological images, but also the hydroxyproline (HYP) content. After testing by transcriptomic analysis, Cxcl2, Synaptosomal-associated protein 25 (Snap25), and Eukaryotic translation initiation factor 3, and subunit J2 (Eif3j2) which were differentially expressed genes, were verified, so that the data were credible. We further found that BQG could regulate Notch signaling pathway by significantly decreasing both mRNA and protein expression levels of Notch-1 and Jagged-2. Hence, this study demonstrated that BQG could ameliorate the sclerotic skin in mice model involved in inflammation, vascular changes, and fibrosis effects, which was partly mediated by Notch signaling pathway.

Performance of a new quantitative computed tomography index for interstitial lung disease assessment in systemic sclerosis

Quantitative high resolution computed tomography (HRCT) may objectively assess systemic sclerosis (SSc)-interstitial lung disease (ILD) extent, using three basic densitometric measures: mean lung attenuation (MLA), skewness, and kurtosis. This prospective study aimed to develop a composite index - computerized integrated index (CII) – that accounted for MLA, skewness, and kurtosis by means of Principal Component Analysis over HRCTs of 83 consecutive SSc subjects, thus eliminating redundancies. Correlations among CII, cardiopulmonary function and immune-inflammatory biomarkers (e.g. sIL-2Rα and CCL18 serum levels) were explored. ILD was detected in 47% of patients at visual HRCT assessment. These patients had worse CII values than patients without ILD. The CII correlated with lung function at both baseline and follow-up, and with sIL-2Rα and CCL18 serum levels. The best discriminating CII value for ILD was 0.1966 (AUC = 0.77; sensitivity = 0.81 [95%CI:0.68–0.92]; specificity = 0.66 [95%CI:0.52–0.80]). Thirty-four percent of patients without visual trace of ILD had a CII lower than 0.1966, and 67% of them had a diffusing lung capacity for CO <80% of predicted. We showed that this new composite CT index for SSc-ILD assessment correlates with both lung function and immune-inflammatory parameters and could be sufficiently sensitive for capturing early lung density changes in visually ILD-free patients.

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.

OTUD6B-AS1 Might Be a Novel Regulator of Apoptosis in Systemic Sclerosis

Antisense long non-coding RNAs (AS lncRNAs) have increasingly been recognized as important regulators of gene expression and they have been found to play key roles in several diseases. However, very little is known about the role of AS lncRNAs in fibrotic diseases such as systemic sclerosis (SSc). Our recent screening experiments by RNA sequencing showed that ovarian tumor domain containing 6B antisense RNA1 (OTUD6B-AS1) and its sense gene OTUD6B were significantly downregulated in SSc skin biopsies. Therefore, we aimed to identify key regulators of OTUD6B-AS1 and to analyze the functional relevance of OTUD6B-AS1 in SSc. OTUD6B-AS1 and OTUD6B expression in SSc and healthy control (HC) dermal fibroblasts (Fb) after stimulation with transforming growth factor-β (TGFβ), Interleukin (IL)-4, IL-13, and platelet-derived growth factor (PDGF) was analyzed by qPCR. To identify the functional role of OTUD6B-AS1, dermal Fb or human pulmonary artery smooth muscle cells (HPASMC) were transfected with a locked nucleic acid antisense oligonucleotide (ASO) targeting OTUD6B-AS1. Proliferation was measured by BrdU and real-time proliferation assay. Apoptosis was measured by Caspase 3/7 assay and Western blot for cleaved caspase 3. While no difference was recorded at the basal level between HC and SSc dermal Fb, the expression of OTUD6B-AS1 and OTUD6B was significantly downregulated in both SSc and HC dermal Fb after PDGF stimulation in a time-dependent manner. Only mild and inconsistent effects were observed with TGFβ, IL-4, and IL-13. OTUD6B-AS1 knockdown in Fb and HPASMC did not affect extracellular matrix or pro-fibrotic/proinflammatory cytokine production. However, OTUD6B-AS1 knockdown significantly increased Cyclin D1 expression at the mRNA and protein level. Moreover, silencing of OTUD6B-AS1 significantly reduced proliferation and suppressed apoptosis in both dermal Fb and HPASMC. OTUD6B-AS1 knockdown did not affect OTUD6B expression at the mRNA level and protein level. Our data suggest that OTUD6B-AS1 regulates proliferation and apoptosis via cyclin D1 expression in a sense gene independent manner. This is the first report investigating the function of OTUD6B-AS1. Our data shed light on a novel apoptosis resistance mechanism in Fb and vascular smooth muscle cells that might be relevant for pathogenesis of SSc.

Targeting of dermal myofibroblasts through death receptor 5 arrests fibrosis in mouse models of scleroderma

Scleroderma is an autoimmune rheumatic disorder accompanied by severe fibrosis in skin and other internal organs. During scleroderma progression, resident fibroblasts undergo activation and convert to α-smooth muscle actin (α-SMA) expressing myofibroblasts (MFBs) with increased capacity to synthesize collagens and fibrogenic components. Accordingly, MFBs are a major therapeutic target for fibrosis in scleroderma and treatment with blocking MFBs could produce anti-fibrotic effects. TLY012 is an engineered human TNF-related apoptosis-inducing ligand (TRAIL) which induces selective apoptosis in transformed cells expressing its cognate death receptors (DRs). Here we report that TLY012 selectively blocks activation of dermal fibroblasts and induces DR-mediated apoptosis in α-SMA+ MFBs through upregulated DR5 during its activation. In vivo, TLY012 reverses established skin fibrosis to near-normal skin architecture in mouse models of scleroderma. Thus, the TRAIL pathway plays a critical role in tissue remodeling and targeting upregulated DR5 in α-SMA+ MFBs is a viable therapy for fibrosis in scleroderma.

Acute salt loading and cardiotonic steroids in resistant hypertension

The study addresses the association of marinobufagenin (MBG), a natriuretic and vasoconstrictor steroid, and Na/K-ATPase (NKA) activity with pressor response to salt-loading and arterial stiffness in resistant hypertension (RH). Thirty-four patients (18 males and 16 females; 56±8 years) with RH on a combined (lisnopril/amlodipine/hydrochlorothiazide) therapy and 11 healthy age-matched normotensive subjects (7 males and 4 females; 54±2 years) were enrolled in this study. Salt-loading was performed via intravenous infusion of 1000mL saline (0.9% NaCl) for 1h. Arterial stiffness was measured by Sphygmocor Px device with a calculation of pulse-wave velocity (PWV). Activity of NKA was measured in erythrocytes. We demonstrated that plasma levels of MBG and magnitude of NaCl-induced MBG-dependent NKA inhibition are associated with PWV, and that this association has gender- and age-specific fashion in RH patients.

The serum vitamin D metabolome: What we know and what is still to discover

Vitamin D, referring to the two forms, D2 from the diet and D3 primarily derived from phototransformation in the skin, is a prohormone important in human health. The most hormonally active form, 1α,25-dihydroxyvitamin D (1α,25(OH)₂D), formed from vitamin D via 25-hydroxyvitamin D (25(OH)D), is not only important for regulating calcium metabolism, but has many pleiotropic effects including regulation of the immune system and has anti-cancer properties. The major circulating form of vitamin D is 25(OH)D and both D2 and D3 forms are routinely measured by LC/MS/MS to assess vitamin D status, due to their relatively long half-lives and much higher concentrations compared to 1α,25(OH)₂D. Inactivation of both 25(OH)D and 1α,25(OH)₂D is catalyzed by CYP24A1 and 25-hydroxyvitamin D3 3-epimerase. Initial products from these enzymes acting on 25(OH)D3 are 24R,25(OH)₂D3 and 3-epi-25(OH)D3, respectively, and both of these can also be measured routinely in some clinical laboratories to further document vitamin D status. With advances in LC/MS/MS and its increased availability, and with the help of studies with recombinant vitamin D-metabolizing enzymes, many other vitamin D metabolites have now been detected and in some cases quantitated, in human serum. CYP11A1 which catalyzes the first step in steroidogenesis, has been found to also act on vitamins D3 and D2 hydroxylating both at C20, but with some secondary metabolites produced by subsequent hydroxylations at other positions on the side chain. The major vitamin D3 metabolite, 20S-hydroxyvitamin D3 (20S(OH)D3), shows biological activity, often similar to 1α,25(OH)₂D3 but without calcemic effects. Using standards produced enzymatically by purified CYP11A1 and characterized by NMR, many of these new metabolites have been detected in human serum, with semi-quantitative measurement of 20S(OH)D3 indicating it is present at comparable concentrations to 24R,25(OH)₂D3 and 3-epi-25(OH)D3. Recently, vitamin D-related hydroxylumisterols derived from lumisterol3, a previtamin D3 photoproduct, have also been measured in human serum and displayed biological activity in initial in vitro studies. With the current extensive knowledge on the reactions and pathways of metabolism of vitamin D, especially those catalyzed by CYP24A1, CYP27A1, CYP27B1, CYP3A4 and CYP11A1, it is likely that many other of the resulting hydroxyvitamin D metabolites will be measured in human serum in the future, some contributing to a more detailed understanding of vitamin D status in health and disease.

The Role of Fibrinolytic Regulators in Vascular Dysfunction of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by vascular dysfunction and extensive fibrosis of the skin and visceral organs. Vascular dysfunction is caused by endothelial cell (EC) apoptosis, defective angiogenesis, defective vasculogenesis, endothelial-to-mesenchymal transition (EndoMT), and coagulation abnormalities, and exacerbates the disease. Fibrinolytic regulators, such as plasminogen (Plg), plasmin, α2-antiplasmin (α2AP), tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plasminogen activator inhibitor 1 (PAI-1), and angiostatin, are considered to play an important role in the maintenance of endothelial homeostasis, and are associated with the endothelial dysfunction of SSc. This review considers the roles of fibrinolytic factors in vascular dysfunction of SSc.

Management of Raynaud’s phenomenon in systemic sclerosis—a practical approach

Raynaud’s phenomenon is nearly universal in systemic sclerosis. Vasculopathy is part of systemic sclerosis. Raynaud’s phenomenon can cause of complications and impairment, especially when tissue ischemia and digital ulcers develop. There are many treatment options for Raynaud’s phenomenon in systemic sclerosis often with sparse data and few robust studies comparing the different treatment options. Recommendations from guidelines usually include calcium channel blockers as first-line pharmacological treatment. In the clinical setting, multiple variables such as financial factors, geography where access to medications varies, and patient factors, baseline hypotension, can influence the treatment for Raynaud’s phenomenon and digital ulcers. Prostacyclins and PDE-5 inhibitors are reserved for more severe Raynaud’s phenomenon or healing of digital ulcers. Prevention of digital ulcers may also include endothelin receptor blocker (bosentan) in some countries. Other treatments had less consensus. Algorithms developed by systemic sclerosis experts might be helpful in deciding which treatment to choose for each setting, using a step-wise strategy, which intends to complement guidelines. This review focuses on a practical approach to the treatment of Raynaud’s phenomenon and digital ulcers in systemic sclerosis, based on algorithms designed by systemic sclerosis experts using consensus, and we review the evidence that supports treatment from initial to second and third-line options.

Oncostatin M and its role in fibrosis

Oncostain M, a member of the IL-6 family of cytokines, is produced by immune cells in response to infections and tissue injury. OSM has a broad, often context-dependent effect on various cellular processes including differentiation, hematopoiesis, cell proliferation, and cell survival. OSM signaling is initiated by binding to type I (LIFRβ/gp130) or type II (OSMRβ/gp130) receptor complexes and involves activation of Janus kinase/signal transducer and activator of transcription, mitogen-activated protein kinase, and phosphatidylinositol-3-kinase. High levels of OSM have been detected in many chronic inflammatory conditions characterized by fibrosis, giving a rationale to target OSM for the treatment of these diseases. Here we discuss the current knowledge on the role of OSM in various stages of the fibrotic process including inflammation, vascular dysfunction, and activation of fibroblasts.

The Regulation of Skin Fibrosis in Systemic Sclerosis by Extracellular ATP via P2Y2 Purinergic Receptor

Tissue injury/hypoxia and oxidative stress induced-extracellular adenosine triphosphate (ATP) can act as damage-associated molecular pattern molecules, which initiate inflammatory response. Our objective was to elucidate the role of extracellular ATP in skin fibrosis in systemic sclerosis (SSc). We identified that hypoxia enhanced ATP release and that extracellular ATP enhanced IL-6 production more significantly in SSc fibroblasts than in normal fibroblasts. There were no significant differences of P2X and P2Y receptor expression levels between normal and SSc fibroblasts. Nonselective P2 receptor antagonist and selective P2Y₂ receptor antagonists, kaempferol and AR-C118925XX, significantly inhibited ATP-induced IL-6 production and phosphorylation of p38 in SSc fibroblasts. ATP-induced IL-6 production was significantly inhibited by p38 inhibitors, SB203580, and doramapimod. Collagen type I production in SSc fibroblasts by ATP-induced IL-6/IL-6 receptor trans-signaling was inhibited by kaempferol and SB203580. The amount of ATP in bleomycin-treated skin was increased, and administration of AR-C118925XX significantly inhibited bleomycin-induced dermal fibrosis in mice. These results suggest that vasculopathy-induced hypoxia and oxidative stress might enhance ATP release in the dermis in SSc and that extracellular ATP-induced phosphorylation of p38 via P2Y₂ receptor might enhance IL-6 and collagen type I production in SSc fibroblasts. P2Y₂ receptor antagonist therapy could be a treatment for skin sclerosis in patients with SSc.

Qingchang Suppository Ameliorates Colonic Vascular Permeability in Dextran-Sulfate-Sodium-Induced Colitis

Ulcerative colitis (UC), with a long course and repeated attack, severely affects patient's life quality and increases economic burden all over the world. However, the concrete causes and mechanisms of UC are still unclear, but it is generally considered that many factors participate in this process. Qingchang Suppository (QCS) has been used in treating rectitis and colitis for about 30 years in Shanghai, China. Its satisfactory clinical effects have been proved. The aim of this study is to investigate the effect and mechanisms of QCS on colonic vascular endothelial barrier in dextran sulfate sodium (DSS)-induced colitis. The results indicated that increased vascular permeability (VP) appeared earlier than increased intestinal epithelial permeability (EP) in the process of DSS-induced colitis. QCS attenuated colonic tissue edema, vascular congestion and inflammatory cell infiltration. QCS inhibited the elevation of MPO, TNF-α, and IL-6 levels in colon tissues and alleviated the microvascular damage induced by DSS. QCS also improved colonic hypoxia and decreased the expression of VEGF, HIF-1α, and iNOS. These results revealed that QCS can reduce colonic VP and can improve vascular endothelial barrier function maybe by regulating the VEGF/HIF-1α signaling pathway.

A Potential Link Between Oxidative Stress and Endothelial-to-Mesenchymal Transition in Systemic Sclerosis

Systemic sclerosis (SSc), an autoimmune disease that is associated with a number of genetic and environmental risk factors, is characterized by progressive fibrosis and microvasculature damage in the skin, lungs, heart, digestive system, kidneys, muscles, joints, and nervous system. These abnormalities are associated with altered secretion of growth factor and profibrotic cytokines, such as transforming growth factor-beta (TGF-β), interleukin-4 (IL-4), platelet-derived growth factor (PDGF), and connective-tissue growth factor (CTGF). Among the cellular responses to this proinflammatory environment, the endothelial cells phenotypic conversion into activated myofibroblasts, a process known as endothelial to mesenchymal transition (EndMT), has been postulated. Reactive oxygen species (ROS) might play a key role in SSs-associated fibrosis and vascular damage by mediating and/or activating TGF-β-induced EndMT, a phenomenon that has been observed in other disease models. In this review, we identified and critically appraised published studies investigating associations ROS and EndMT and the presence of EndMT in SSc, highlighting a potential link between oxidative stress and EndMT in this condition.

Inhibitory Regulation of Skin Fibrosis in Systemic Sclerosis by Apelin/APJ Signaling

OBJECTIVE

Apelin/APJ signaling has been determined to regulate cardiac and arterial fibrosis and to be involved in the pathogenesis of pulmonary arterial hypertension. Our objective was to elucidate the role of apelin in skin fibrosis in systemic sclerosis (SSc).

METHODS

Expression of apelin/APJ in normal and SSc fibroblasts was compared. Effects of small interfering RNA depletion and the addition of apelin in fibroblasts were analyzed. The effect of apelin injections on bleomycin-induced dermal fibrosis in mice was investigated. We analyzed the effects of the biased agonist of APJ, MM07, on skin fibrosis in vitro and in vivo.

RESULTS

The expression of apelin in SSc fibroblasts was significantly lower than that in normal fibroblasts. Serum apelin levels were negatively correlated with the modified Rodnan skin thickness score in SSc patients. Stimulation with transforming growth factor β1 (TGFβ1) inhibited apelin expression in fibroblasts, suggesting that activation of TGFβ1 signaling in SSc might be responsible for reduced apelin expression in SSc fibroblasts. Small interfering RNA depletion of apelin from fibroblasts significantly enhanced fibrosis-related gene expression, and treatment with apelin protein significantly inhibited TGFβ1 signaling in fibroblasts. Administration of apelin significantly inhibited bleomycin-induced dermal fibrosis in mice. We demonstrated that MM07 had greater potential than apelin to inhibit fibrosis in vivo and in vitro.

CONCLUSION

Collectively, TGFβ1 signaling and apelin signaling may counteract each other in the fibrotic process of SSc. Inhibitory regulation of TGFβ1-induced skin fibrosis by apelin/APJ signaling may be involved in the pathogenesis of SSc and could be a therapeutic target for fibrosis in SSc patients.

Antibody to Marinobufagenin Reverses Placenta-Induced Fibrosis of Umbilical Arteries in Preeclampsia

Background: Previous studies implicated cardiotonic steroids, including Na/K-ATPase inhibitor marinobufagenin (MBG), in the pathogenesis of preeclampsia (PE). Immunoneutralization of heightened MBG by Digibind, a digoxin antibody, reduces blood pressure (BP) in patients with PE, and anti-MBG monoclonal antibody lessens BP in a rat model of PE. Recently, we demonstrated that MBG induces fibrosis in cardiovascular tissues via a mechanism involving inhibition of Fli-1, a nuclear transcription factor and a negative regulator of collagen-1 synthesis. Objectives and Methods: We hypothesized that in PE, elevated placental MBG levels are associated with development of fibrosis in umbilical arteries. Eleven patients with PE (mean BP 124 ± 4 mmHg; age 29 ± 2 years; 39 weeks gest. age) and 10 gestational age-matched normal pregnant subjects (mean BP 92 ± 2 mmHg; controls) were enrolled in the clinical study. Results: PE was associated with a higher placental (0.04 ± 0.01 vs. 0.49 ± 0.11 pmol/g; p < 0.01) and plasma MBG (0.5 ± 0.1 vs. 1.6 ± 0.5 nmol/L; p < 0.01), lower Na/K-ATPase activity in erythrocytes (2.7 ± 0.2 vs. 1.5 ± 0.2 µmol Pi/mL/hr; p < 0.01), 9-fold decrease of Fli-1 level and 2.5-fold increase of collagen-1 in placentae (p < 0.01) vs. control. Incubation of umbilical arteries from control patients with 1 nmol/L MBG was associated with four-fold decrease in Fli-1 level and two-fold increase in collagen-1 level vs. those incubated with placebo (p < 0.01), i.e., physiological concentration of MBG mimicked effect of PE in vitro. Collagen-1 abundance in umbilical arteries from PE patients was 4-fold higher than in control arteries, and this PE-associated fibrosis was reversed by monoclonal anti-MBG antibody ex vivo. Conclusion: These results demonstrate that elevated placental MBG level is implicated in the development of fibrosis of the placenta and umbilical arteries in PE.

The Role of Endothelial Progenitors in the Repair of Vascular Damage in Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by a complex pathological process where the main scenario is represented by progressive loss of microvascular bed, with the consequent progressive fibrotic changes in involved organ and tissues. Although most aspects of vascular injury in scleroderma are poorly understood, recent data suggest that the scleroderma impairment of neovascularization could be related to both angiogenesis and vasculogenesis failure. Particularly, compensatory angiogenesis does not occur normally in spite of an important increase in many angiogenic factors either in SSc skin or serum. Besides insufficient angiogenesis, the contribution of defective vasculogenesis to SSc vasculopathy has been extensively studied. Over the last decades, our understanding of the processes responsible for the formation of new vessels after tissue ischemia has increased. In the past, adult neovascularization was thought to depend mainly on angiogenesis (a process by which new vessels are formed by the proliferation and migration of mature endothelial cells). More recently, increased evidence suggests that stem cells mobilize from the bone marrow into the peripheral blood (PB), differentiate in circulating endothelial progenitors (EPCs), and home to site of ischemia to contribute to de novo vessel formation. Significant advances have been made in understanding the biology of EPCs, and molecular mechanisms regulating EPC function. Autologous EPCs now are becoming a novel treatment option for therapeutic vascularization and vascular repair, mainly in ischemic diseases. However, different diseases, such as cardiovascular diseases, diabetes, and peripheral artery ischemia are related to EPC dysfunction. Several studies have shown that EPCs can be detected in the PB of patients with SSc and are impaired in their function. Based on an online literature search (PubMed, EMBASE, and Web of Science, last updated December 2017) using keywords related to “endothelial progenitor cells” and “Systemic Sclerosis,” “scleroderma vasculopathy,” “angiogenesis,” “vasculogenesis,” this review gives an overview on the large body of data of current research in this issue, including controversies over the identity and functions of EPCs, their meaning as biomarker of SSc microangiopathy and their clinical potency.

Metabolomic profile of systemic sclerosis patients

Systemic sclerosis (SSc) is an autoimmune disease of unknown aetiology characterized by vascular lesions, immunological alterations and diffuse fibrosis of the skin and internal organs. Since recent evidence suggests that there is a link between metabolomics and immune mediated disease, serum metabolic profile of SSc patients and healthy controls was investigated by ¹H-NMR and GC-MS techniques. The results indicated a lower level of aspartate, alanine, choline, glutamate, and glutarate in SSc patients compared with healthy controls. Moreover, comparing patients affected by limited SSc (lcSSc) and diffuse SSc (dcSSc), 6 discriminant metabolites were identified. The multivariate analysis performed using all the metabolites significantly different revealed glycolysis, gluconeogenesis, energetic pathways, glutamate metabolism, degradation of ketone bodies and pyruvate metabolism as the most important networks. Aspartate, alanine and citrate yielded a high area under receiver-operating characteristic (ROC) curves (AUC of 0.81; CI 0.726–0.93) for discriminating SSc patients from controls, whereas ROC curve generated with acetate, fructose, glutamate, glutamine, glycerol and glutarate (AUC of 0.84; CI 0.7–0.98) discriminated between lcSSc and dcSSc. These results indicated that serum NMR-based metabolomics profiling method is sensitive and specific enough to distinguish SSc from healthy controls and provided a feasible diagnostic tool for the diagnosis and classification of the disease.

Esophageal high-resolution impedance manometry alterations in asymptomatic patients with systemic sclerosis: prevalence, associations with disease features, and prognostic value

This study aims to investigate pre-clinical esophageal involvement in systemic sclerosis (SSc) by high-resolution impedance manometry (HRiM), its associations with disease features including lung involvement, and its predictivity of esophageal symptoms overtime. Charts of 45 asymptomatic (no heartburn/regurgitation/dysphagia) SSc patients (96% females; mean age 46 years) with at least one follow-up (FU) visit and complete clinical, serological, functional, and radiological assessment, including high-resolution computed tomography (HRCT) of the chest and lung function tests, that had undergone esophageal HRiM were retrospectively evaluated. Esophagogastric junction-contractile integral (EGJ-CI) and esophageal body motility, as evaluated by mean distal contractile integral (DCI), were assessed. SSc patients had a normal esophageal motility in 7/45 cases, a defective EGJ-CI in 28, an ineffective esophageal motility (IEM) in 17, and aperistalsis in 12. Defective EGJ-CI was associated with IEM/aperistalsis in 20 cases, while 9 patients had isolated IEM. Defective EGJ-CI and/or IEM/aperistalsis were associated with a diffusing lung capacity for CO < 80% of predicted value (all p < 0.05), while defective EGJ-CI was also associated with interstitial lung disease on HRCT (p = 0.03). Prevalence of any HRiM abnormality was higher in anti-centromere antibody negative patients (all p < 0.05). IEM/aperistalsis independently increased the risk of esophageal symptoms by 2.3-fold (95% CI 1.1-5.7) and was associated with their higher cumulative incidence with respect to patients with other HRiM patterns at FU (χ² = 4.63; p = 0.03). SSc patients asymptomatic for esophageal involvement can have HRiM abnormalities in up to 84% of cases. A baseline-impaired motility is a risk factor for symptomatic esophageal disease.

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.

Pathogenesis of systemic sclerosis: recent insights of molecular and cellular mechanisms and therapeutic opportunities

Systemic sclerosis (SSc) is a complex disease characterized by early microvascular abnormalities, immune dysregulation and chronic inflammation, and subsequent fibrosis of the skin and internal organs. Excessive fibrosis, distinguishing hallmark of SSc, is the end result of a complex series of interlinked vascular injury and immune activation, and represents a maladaptive repair process. Activated vascular, epithelial, and immune cells generate pro-fibrotic cytokines, chemokines, growth factors, lipid mediators, autoantibodies, and reactive oxygen species. These paracrine and autocrine cues in turn induce activation, differentiation, and survival of mesenchymal cells, ensuing tissue fibrosis through increased collagen synthesis, matrix deposition, tissue rigidity and remodeling, and vascular rarefaction. This review features recent insights of the pathogenic process of SSc, highlighting three major characteristics of SSc, microvasculopathy, excessive fibrosis, and immune dysregulation, and sheds new light on the understanding of molecular and cellular mechanisms contributing to the pathogenesis of SSc and providing novel avenues for targeted therapies.

Endoglin-based biological therapy in the treatment of angiogenesis-dependent pathologies

INTRODUCTION

Alterations in the process of angiogenesis, either by excess or by defect, are present in different common pathologies. For this reason, great efforts are being made toward the development of pro- and anti-angiogenic therapies. Since endoglin levels are enhanced in tissues undergoing angiogenesis, and changes in its expression lead to alterations in vessel formation, endoglin has become an ideal target for these types of therapies. Areas covered: In this review, the role of endoglin in angiogenesis is summarized. In addition, the authors review pro- and anti-angiogenic therapies that are currently being used and new approaches that target endoglin. The article includes therapies that are both in preclinical and clinical development. Expert opinion: Endoglin is a very good target for anti-angiogenic therapy, as demonstrated by the positive results obtained with anti-endoglin antibodies. However, although endoglin in pro-angiogenic therapies has been successful in vitro, its use has not yet reached clinical settings. Moreover, the authors believe that establishing the exact role of endoglin in angiogenesis is essential and that this should be the next step in this field in the coming years.

The "myth" of loss of angiogenesis in systemic sclerosis: a pivotal early pathogenetic process or just a late unavoidable event?

Systemic sclerosis is considered a disease dominated by a "loss of angiogenesis", although in its early phases evidence indicates a disturbed angiogenic response only. In fact, microvascular changes are primarily due to endothelial cell injury, triggering downstream significant enlargement of the capillary in an inflammatory environment, followed by capillary rupture (microhemorrhages). Subsequent pro-angiogenic efforts lead to an aberrant angiogenesis and, eventually, to a total loss of vessel repair and regeneration (loss of angiogenesis). This clearly suggests that the pathogenetic process has a steady progression: from an early excessive pro-angiogenesis, to an aberrant microvascular regeneration, then ending with a late loss of angiogenesis. Herein, we suggest the loss of angiogenesis should not be considered as an overall "myth" characterizing systemic sclerosis but as a very late event of the vascular pathogenesis. Future research should be oriented essentially on the earlier phases dominated by excessive pro-angiogenesis and microvascular aberration.

Endothelial cell-specific activation of transforming growth factor-β signaling in mice induces cutaneous, visceral, and microvascular fibrosis

In this study, we tested the hypothesis that constitutive endothelial cell-specific activation of TGF-β signaling induces tissue fibrosis and vasculopathy resembling the characteristic fibrotic and vascular alterations of systemic sclerosis. Transgenic mice with inducible expression of a constitutively active TGF-β receptor I specifically in endothelial cells were generated by intercrossing mice harboring a constitutively active TGF-β receptor I with a mouse strain containing the endothelial cell-specific Cdh5 gene promoter directing the tamoxifen-inducible expression of the Cre-ER^T2 cassette. Administration of tamoxifen to these mice would result in constitutive TGF-β activation and signaling confined to endothelial lineage cells. The effects of constitutive TGF-β endothelial cell activation were assessed by histopathological examination of skin and various internal organs, tissue hydroxyproline analysis, and assessment of expression of myofibroblast differentiation and TGF-β signaling genes employing real-time PCR and immunohistochemical staining of lung vessels for endothelial- and myofibroblast-specific proteins. Constitutive TGFβ-1 signaling in endothelial cells resulted in cutaneous and visceral fibrosis with prominent fibrotic involvement of the lungs and severe perivascular and subendothelial fibrosis of small arterioles. A marked increase in the expression of fibrosis-associated genes and of genes indicative of myofibroblast activation was also found. Confocal microscopy of lung vessels showed evidence consistent with the induction of endothelial-to-mesenchymal transition (EndoMT). Taken together, our data indicate that transgenic mice with constitutive endothelial cell-specific activation of TGF-β signaling display severe cutaneous, pulmonary, and microvascular fibrosis resembling the fibrotic and microvascular alterations characteristic of systemic sclerosis.

Transforming growth factor-β signaling in systemic sclerosis

Systemic sclerosis (SSc) is a complex, multiorgan autoimmune disease of unknown etiology. Manifestation of the disease results from an interaction of three key pathologic features including irregularities of the antigen-specific immune system and the non-specific immune system, resulting in autoantibody production, vascular endothelial activation of small blood vessels, and tissue fibrosis as a result of fibroblast dysfunction. Given the heterogeneity of clinical presentation of the disease, a lack of universal models has impeded adequate testing of potential therapies for SSc. Regardless, recent research has elucidated the roles of various ubiquitous molecular mechanisms that contribute to the clinical manifestation of the disease. Transforming growth factor β (TGF-β) has been identified as a regulator of pathological fibrogenesis in SSc. Various processes, including cell growth, apoptosis, cell differentiation, and extracellular matrix synthesis are regulated by TGF-β, a type of cytokine secreted by macrophages and many other cell types. Understanding the essential role TGF-β pathways play in the pathology of systemic sclerosis could provide a potential outlet for treatment and a better understanding of this severe disease.

Review article: pathogenesis and clinical manifestations of gastrointestinal involvement in systemic sclerosis

BACKGROUND

Gastrointestinal tract (GIT) involvement is a common cause of debilitating symptoms in patients with systemic sclerosis (SSc). There are no disease modifying therapies for this condition and the treatment remains symptomatic, largely owing to the lack of a clear understanding of its pathogenesis.

AIMS

To investigate novel aspects of the pathogenesis of gastrointestinal involvement in SSc. To summarise existing knowledge regarding the cardinal clinical gastrointestinal manifestations of SSc and its pathogenesis, emphasising recent investigations that may be valuable in identifying potentially novel therapeutic targets.

METHODS

Electronic (PubMed/Medline) and manual Google search.

RESULTS

The GIT is the most common internal organ involved in SSc. Any part of the GIT from the mouth to the anus can be affected. There is substantial variability in clinical manifestations and disease course and symptoms are nonspecific and overlapping for a particular anatomical site. Gastrointestinal involvement can occur in the absence of cutaneous disease. Up to 8% of SSc patients develop severe GIT symptoms. This subset of patients display increased mortality with only 15% survival at 9 years. Dysmotiity of the GIT causes the majority of symptoms. Recent investigations have identified a novel mechanism in the pathogenesis of GIT dysmotility mediated by functional anti-muscarinic receptor autoantibodies.

CONCLUSIONS

Despite extensive investigation, the pathogenesis of gastrointestinal involvement in systemic sclerosis remains elusive. Although treatment currently remains symptomatic, an improved understanding of novel pathogenic mechanisms may allow the development of potentially highly effective approaches including intravenous immunoglobulin and microRNA based therapeutic interventions.

Geniposide inhibited endothelial-mesenchymal transition via the mTOR signaling pathway in a bleomycin-induced scleroderma mouse model

AIM

Geniposide is an iridoid glycoside isolated from the gardenia plant. It has multiple biological activities. The roles of geniposide in systemic sclerosis (SSc) and in endothelial-to-mesenchymal transition (EndMT) are unclear. We investigated the protective effects of geniposide in a bleomycin-induced SSc mouse model, and its potential mechanisms.

METHODS

The effects of geniposide were evaluated as follows: (1) histological and immunochemical changes in mouse skin tissue; (2) changes in cellular morphology of human umbilical vein endothelial cells (HUVECs); (3) expression of endothelial cell biomarkers (E-Cadherin, CD31, and CD34), mesenchymal cell markers (FSP1, Collagen, and α-SMA), and key factors of EndMT (Slug, Snail, and Twist) using real time PCR, Western blot, and immunofluorescence; (4) tube formation in HUVECs; (5) mTOR signaling pathway transcription factors using Western blot analysis.

RESULTS

Treatment with bleomycin induced up-regulation of mesenchymal cell biomarkers and down-regulation of endothelial cell biomarkers in in vivo and in vitro bleomycin-induced scleroderma models. Geniposide treatment suppressed these effects. Geniposide remedied bleomycin-induced dermal capillary loss and fibrosis in mice. The expression of key EndMT factors (Slug, Snail, and Twist) and the mTOR signaling pathway (mTOR and S6) were also attenuated by geniposide treatment.

CONCLUSION

Geniposide had protective effects on endothelial cells in the bleomycin-induced scleroderma mouse model. These effects may occur via inhibition of the mTOR signaling pathway activation. The results suggested that geniposide could be a potential candidate drug for treatment of vascular damage in SSc patients.

Agonistic Anti-PDGF Receptor Autoantibodies from Patients with Systemic Sclerosis Impact Human Pulmonary Artery Smooth Muscle Cells Function In Vitro

One of the earliest events in the pathogenesis of systemic sclerosis (SSc) is microvasculature damage with intimal hyperplasia and accumulation of cells expressing PDGF receptor. Stimulatory autoantibodies targeting PDGF receptor have been detected in SSc patients and demonstrated to induce fibrosis in vivo and convert in vitro normal fibroblasts into SSc-like cells. Since there is no evidence of the role of anti-PDGF receptor autoantibodies in the pathogenesis of SSc vascular lesions, we investigated the biologic effect of agonistic anti-PDGF receptor autoantibodies from SSc patients on human pulmonary artery smooth muscle cells and the signaling pathways involved. The synthetic (proliferation, migration, and type I collagen gene α1 chain expression) and contractile (smooth muscle-myosin heavy chain and smooth muscle-calponin expression) profiles of human pulmonary artery smooth muscle cells were assessed in vitro after incubation with SSc anti-PDGF receptors stimulatory autoantibodies. The role of reactive oxygen species, NOX isoforms, and mammalian target of rapamycin (mTOR) was investigated. Human pulmonary artery smooth muscle cells acquired a synthetic phenotype characterized by higher growth rate, migratory activity, gene expression of type I collagen α1 chain, and less expression of markers characteristic of the contractile phenotype such as smooth muscle-myosin heavy chain and smooth muscle-calponin when stimulated with PDGF and autoantibodies against PDGF receptor, but not with normal IgG. This phenotypic profile is mediated by increased generation of reactive oxygen species and expression of NOX4 and mTORC1. Our data indicate that agonistic anti-PDGF receptor autoantibodies may contribute to the pathogenesis of SSc intimal hyperplasia.

α2AP regulates vascular alteration by inhibiting VEGF signaling in systemic sclerosis: the roles of α2AP in vascular dysfunction in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a connective tissues disease of unknown origin characterized by vascular damage and extensive fibrosis. Recently, we demonstrated that α2-antiplasmin (α2AP) is associated with the development of fibrosis in SSc. We herein investigate the roles of α2AP in vascular dysfunction in SSc.

METHODS

Vascular damage in mice was determined by the levels of blood vessels and blood flow. Vascular functions in vascular endothelial cells (ECs) were determined by the levels of tube formation, cell proliferation, and endothelial junction-associated protein (VE-cadherin and PECAM1) production.

RESULTS

The administration of α2AP induced vascular damage in mice. Conversely, the α2AP neutralization improved vascular damage in a bleomycin-induced mouse model of SSc. Additionally, we showed that the SSc fibroblast-conditioned media induced the reduction of tube formation, cell proliferation, and endothelial junction-associated protein production in ECs, and that α2AP neutralization improved them. We also examined the mechanisms underlying the effects of α2AP on vascular alteration in SSc and found that α2AP attenuated vascular endothelial growth factor-induced tube formation, cell proliferation, and endothelial junction-associated protein production through the adipose triglyceride lipase/tyrosine phosphatase SHP2 axis in ECs.

CONCLUSION

Our findings demonstrate that α2AP is associated with vascular alteration, and that the blocking of α2AP improves vascular dysfunction in SSc.

Equol Attenuates Atherosclerosis in Apolipoprotein E-Deficient Mice by Inhibiting Endoplasmic Reticulum Stress via Activation of Nrf2 in Endothelial Cells

The development of atherosclerosis is closely related to excessive endoplasmic reticulum stress (ERs). Equol reportedly protects against cardiovascular disease; however, the underlying mechanism for this protection remains unknown. Herein, the mechanisms contributing to the atheroprotective effect of equol were addressed using apolipoprotein E knockout (apoE-/-) mice fed a high-fat diet (HFD) with or without equol. Equol intervention reduced atherosclerotic lesions in the aorta in HFD-fed apoE-/- mice. Plasma lipid analysis showed that equol intervention reduced triglycerides, total cholesterol and LDL-cholesterol and increased HDL-cholesterol. Additionally, equol administration decreased lipid accumulation in the liver. Simultaneously, equol treatment inhibited cell apoptosis induced by t-BHP and thapsigargin in human umbilical vein endothelial cells (HUVECs). Furthermore, equol treatment attenuated palmitate, t-BHP or thapsigargin-induced upregulation of ER stress markers, including p-PERK, p-eIF2α, GRP78, ATF6 and CHOP proteins expression. The same tendency was also observed in aortic lysates in apoE-/- mice fed with equol plus HFD compared with HFD alone. Moreover, equol treatment dose dependently activated the Nrf2 signaling pathway under oxidative stress. Additionally, elevation of Nrf2 induction was found in aortic lysates in apoE-/- mice fed with a HFD diet containing equol compared with a HFD diet without equol. Importantly, Nrf2 siRNA interference induced CHOP and attenuated the effect of equol to inhibit t-BHP mediated CHOP induction, furthermore, abrogated cell apoptosis induced by t-BHP, suggesting a role for Nrf2 in the protective effect of equol in HUVECs. Collectively, these findings implicate that the improvement of atherosclerosis by equol through attenuation of ER stress is mediated, at least in part, by activating the Nrf2 signaling pathway.

Association of a rare NOTCH4 coding variant with systemic sclerosis: a family-based whole exome sequencing study

BACKGROUND

Systemic sclerosis (SSc) is a rheumatologic disease with a multifactorial etiology. Genome-wide association studies imply a polygenic, complex mode of inheritance with contributions from variation at the human leukocyte antigen locus and non-coding variation at a locus on chromosome 6p21, among other modestly impactful loci. Here we describe an 8-year-old female proband presenting with diffuse cutaneous SSc/scleroderma and a family history of SSc in a grandfather and maternal aunt.

METHODS

We employed whole exome sequencing (WES) of three members of this family. We examined rare missense, nonsense, splice-altering, and coding indels matching an autosomal dominant inheritance model. We selected one missense variant for Sanger sequencing confirmation based on its predicted impact on gene function and location in a known SSc genetic locus.

RESULTS

Bioinformatic analysis found eight candidate variants meeting our criteria. We identified a very rare missense variant in the regulatory NODP domain of NOTCH4 located at the 6p21 locus, c.4245G > A:p.Met1415Ile, segregating with the phenotype. This allele has a frequency of 1.83 × 10^-5 by the data of the Exome Aggregation Consortium.

CONCLUSION

This family suggests a novel mechanism of SSc pathogenesis in which a rare and penetrant coding variation can substantially elevate disease risk in contrast to the more modest non-coding variation typically found at this locus. These results suggest that modulation of the NOTCH4 gene might be responsible for the association signal at chromosome 6p21 in SSc.

A multicenter, open-label, comparative study of B-cell depletion therapy with Rituximab for systemic sclerosis-associated interstitial lung disease

OBJECTIVES

Rituximab (RTX) may favorably affect lung function and skin fibrosis in patients with systemic sclerosis (SSc). We aimed to assess long-term efficacy and safety of RTX in SSc compared to standard treatment.

METHODS

A total of 51 patients with SSc-associated interstitial lung disease were recruited and treated with RTX (n = 33) or conventional treatment (n = 18). Median follow-up was 4 years (range: 1-7). Conventional treatment consisted of azathioprine (n = 2), methotrexate (n = 6), and mycophenolate mofetil (n = 10).

RESULTS

Patients in the RTX group showed an increase in FVC at 2 years (mean ± SD of FVC: 80.60 ± 21.21 vs 86.90 ± 20.56 at baseline vs 2 years, respectively, p = 0.041 compared to baseline). In sharp contrast, patients in the control group had no change in FVC during the first 2 years of follow-up. At the 7 year time point the remaining patients in the RTX group (n = 5) had higher FVC compared to baseline (mean ± SD of FVC: 91.60 ± 14.81, p = 0.158 compared to baseline) in contrast to patients in the control group (n = 9) where FVC deteriorated (p < 0.01, compared to baseline). Direct comparison between the 2 groups showed a significant benefit for the RTX group in FVC (p = 0.013). Improvement of skin thickening was found in both the RTX and the standard treatment group; however, direct comparison between groups strongly favored RTX at all-time points. Adverse events were comparable between groups.

CONCLUSIONS

Our data indicate that RTX has a beneficial effect on lung function and skin fibrosis in patients with SSc. Randomized controlled studies are highly needed.

Early Endothelial Progenitor Cells (eEPCs) in systemic sclerosis (SSc) - dynamics of cellular regeneration and mesenchymal transdifferentiation

BACKGROUND

Patients with systemic sclerosis (SSc) are endagered by tissue fibrosis and by microvasculopathy, with the latter caused by endothelial cell expansion/proliferation. SSc-associated fibrosis potentially results from mesenchymal transdifferentiation of endothelial cells. Early Endothelial Progenitor Cells (eEPCs) act proangiogenic under diverse conditions. Aim of the study was to analyze eEPC regeneration and mesenchymal transdifferentiation in patients with limited and diffuse SSs (lSSc and dSSc).

METHODS

Patients with both, lSSc and dSSc were included into the study. The following parameters were evaluated: eEPC numbers and regeneration, concentrations of vasomodulatory mediators, mesenchymal properties of blood-derived eEPC. Serum samples of healthy subjects and SS patients were used for stimulation of cultured human eEPC, subsequently followed by analysis of mesenchymal cell characteristics and mobility.

RESULTS

Twenty-nine patients were included into the study. Regenerative activity of blood-derived eEPCs did not differ between Controls and patients. Circulating eEPC were significantly lower in all patients with SSc, and in limited and diffuse SSc (lSSc/dSSc). Serum concentrations of promesenchymal TGF-b was elevated in all patients with SSc. Cultured mononuclear cells from SS patients displayed higher abundances of CD31 and of CD31 and aSMA combined. Finally, serum from SSc patients inhibited migration of cultured eEPCs and the cells showed lower sensitivity towards the endothelin antagonist Bosentan.

CONCLUSIONS

The eEPC system, which represents an essential element of the endogenous vascular repair machinery is affected in SSc. The increased appearance of mesenchymal properties in eEPC may indicate that alterations of the cells potentially contribute to the accumulation of connective tissue and to vascular malfunction.

Updates on animal models of systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of unknown etiology that is characterized by fibrosis of the skin and several internal organs, vasculopathy, inflammation and autoimmunity. Animal models have improved our understanding of the pathogenesis of SSc. Many inducible and genetic animal models of SSc have been developed and characterized in the last years. All of these models have different strengths and limitations and mimic different aspects of the pathogenesis of SSc. The purpose of this review is to summarize the characteristics of the various animal models of SSc and to provide an outline of how to use these models to study certain aspects in the pathogenesis of SSc and to test the effects of potential therapeutic approaches.

Emerging strategies for treatment of systemic sclerosis

Systemic sclerosis is a heterogeneous condition characterized by microvascular damage, dysregulation of the immune system, and progressive fibrosis affecting skin and internal organs. Currently, there are no approved disease-modifying therapies, and management mostly involves treatment of organ-specific complications. In recent years, major advances have greatly improved our understanding of the disease process, especially the molecular mechanisms by which fibrosis becomes self-sustaining. We discuss selected aspects of these mechanisms with a focus on those relevant to ongoing efforts to develop disease-modifying therapies. We also discuss advances in identification of patient subtypes, and selected examples of potential disease-modifying therapies in clinical development.

Type I IFNs Regulate Inflammation, Vasculopathy, and Fibrosis in Chronic Cutaneous Graft-versus-Host Disease

Type I IFNs play a critical role in the immune response to viral infection and may also drive autoimmunity through modulation of monocyte maturation and promotion of autoreactive lymphocyte survival. Recent demonstrations of type I IFN gene signatures in autoimmune diseases, including scleroderma, led us to investigate the pathological role of IFNs in a preclinical model of sclerodermatous graft-versus-host disease. Using a neutralizing Ab against the type I IFN receptor IFNAR1, we observed a marked reduction in dermal inflammation, vasculopathy, and fibrosis compared with that seen in the presence of intact IFNAR1 signaling. The ameliorative effects of IFNAR1 blockade were restricted to the skin and were highly associated with inhibition of chronic vascular injury responses and not due to the inhibition of the T or B cell alloresponse. Inhibition of IFNAR1 normalized the overexpression of IFN-inducible genes in graft-versus-host disease skin and markedly reduced dermal IFN-α levels. Depletion of plasmacytoid dendritic cells, a major cellular source of type I IFNs, did not reduce the severity of fibrosis or type I IFN gene signature in the skin. Taken together, these studies demonstrate an important role for type I IFN in skin fibrosis, and they provide a rationale for IFNAR1 inhibition in scleroderma.