Vascular involvement in systemic sclerosis (scleroderma)

Single-cell transcriptomes and chromatin accessibility of endothelial cells unravel transcription factors associated with dysregulated angiogenesis in systemic sclerosis

OBJECTIVES

Vasculopathy emerges early in systemic sclerosis (SSc) and links to endothelial cell (EC) injury and angiogenesis. Understanding EC transcriptomes and epigenomes is crucial for unravelling the mechanisms involved.

METHODS

Transcriptomes and chromatin accessibility were assessed by single-cell RNA sequencing and single-nucleus transposase-accessible chromatin sequencing. Immunofluorescent staining of skin and proteomics assay were employed to confirm the altered SSc EC phenotypes. Gain-of-function assay was used to evaluate the effects of ETS transcription factors on human dermal ECs (hDECs).

RESULTS

Both control and SSc ECs shared transcriptomic signatures of vascular linages (arterial, capillary and venous ECs) and lymphatic ECs. Arterial ECs in SSc showed reduced number and increased expression of genes associated with apoptosis. Two distinct EC subpopulations, tip and proliferating ECs, were markedly upregulated in SSc, indicating enhanced proangiogenic and proliferative activities. Molecular features of aberrant SSc-ECs were associated with disease pathogenesis and clinical traits of SSc, such as skin fibrosis and digital ulcers. Ligand-receptor analysis demonstrated altered intercellular networks of SSc EC subpopulations with perivascular and immune cells. Furthermore, the integration of open chromatin profiles with transcriptomic analysis suggested an increased accessibility of regulatory elements for ETS family transcription factors in SSc ECs. Overexpression of ETS genes in hDECs suggested ELK4, ERF and ETS1 may orchestrate arterial apoptosis and dysregulated angiogenesis in SSc.

CONCLUSIONS

This study unveils transcriptional and chromatin alterations in driving endovascular dysregulation in SSc, proposing ELK4, ERF and ETS1 as novel targets in ECs for addressing vascular complications in the condition.

A genome-wide association study suggests new susceptibility loci for primary antiphospholipid syndrome

Objectives

Primary antiphospholipid syndrome (PAPS) is a rare autoimmune disease characterized by the presence of antiphospholipid antibodies and the occurrence of thrombotic events and pregnancy complications. Our study aimed to identify novel genetic susceptibility loci associated with PAPS.

Methods

We performed a genome-wide association study comprising 5,485 individuals (482 affected individuals) of European ancestry. Significant and suggestive independent variants from a meta-analysis of approximately 7 million variants were evaluated for functional and biological process enrichment. The genetic risk variability for PAPS in different populations was also assessed. Hierarchical clustering, Mahalanobis distance, and Dirichlet Process Mixtures with uncertainty clustering methods were used to assess genetic similarities between PAPS and other immune-mediated diseases.

Results

We revealed genetic associations with PAPS in a regulatory locus within the HLA class II region near HLA-DRA and in STAT4 with a genome-wide level of significance. 34 additional suggestive genetic susceptibility loci for PAPS were also identified. The disease risk allele in the HLA class II locus is associated with overexpression of HLA-DRB6 , HLA-DRB9 , HLA-DPB2 , HLA-DQA2 and HLA-DQB2 , and is independent of the association between PAPS and HLA-DRB1*1302 . Functional analyses highlighted immune and nervous system related pathways in PAPS-associated loci. The comparison with other immune-mediated diseases revealed a close genetic relatedness to neuromyelitis optica, systemic sclerosis, and Sjögren's syndrome, suggesting colocalized causal variations close to STAT4 , TNPO3 , and BLK .

Conclusions

This study represents a comprehensive large-scale genetic analysis for PAPS and provides new insights into the genetic basis and pathophysiology of this rare disease.

S1P/S1PR signaling pathway advancements in autoimmune diseases

Sphingosine-1-phosphate (S1P) is a versatile sphingolipid that is generated through the phosphorylation of sphingosine by sphingosine kinase (SPHK). S1P exerts its functional effects by binding to the G protein-coupled S1P receptor (S1PR). This lipid mediator plays a pivotal role in various cellular activities. The S1P/S1PR signaling pathway is implicated in the pathogenesis of immune-mediated diseases, significantly contributing to the functioning of the immune system. It plays a crucial role in diverse physiological and pathophysiological processes, including cell survival, proliferation, migration, immune cell recruitment, synthesis of inflammatory mediators, and the formation of lymphatic and blood vessels. However, the full extent of the involvement of this signaling pathway in the development of autoimmune diseases remains to be fully elucidated. Therefore, this study aims to comprehensively review recent research on the S1P/S1PR axis in diseases related to autoimmunity.

Biomarkers in the Pathogenesis, Diagnosis, and Treatment of Systemic Sclerosis

Systemic sclerosis (SSc) is a complex autoimmune disease characterized by vascular damage, vasoinstability, and decreased perfusion with ischemia, inflammation, and exuberant fibrosis of the skin and internal organs. Biomarkers are analytic indicators of the biological and disease processes within an individual that can be accurately and reproducibly measured. The field of biomarkers in SSc is complex as recent studies have implicated at least 240 pathways and dysregulated proteins in SSc pathogenesis. Anti-nuclear antibodies (ANA) are classical biomarkers with well-described clinical classifications and are present in more than 90% of SSc patients and include anti-centromere, anti-Th/To, anti-RNA polymerase III, and anti-topoisomerase I antibodies. Transforming growth factor-β (TGF-β) is central to the fibrotic process of SSc and is intimately intertwined with other biomarkers. Tyrosine kinases, interferon-1 signaling, IL-6 signaling, endogenous thrombin, peroxisome proliferator-activated receptors (PPARs), lysophosphatidic acid receptors, and amino acid metabolites are new biomarkers with the potential for developing new therapeutic agents. Other biomarkers implicated in SSc-ILD include signal transducer and activator of transcription 4 (STAT4), CD226 (DNAX accessory molecule 1), interferon regulatory factor 5 (IRF5), interleukin-1 receptor-associated kinase-1 (IRAK1), connective tissue growth factor (CTGF), pyrin domain containing 1 (NLRP1), T-cell surface glycoprotein zeta chain (CD3ζ) or CD247, the NLR family, SP-D (surfactant protein), KL-6, leucine-rich α2-glycoprotein-1 (LRG1), CCL19, genetic factors including DRB1 alleles, the interleukins (IL-1, IL-4, IL-6, IL-8, IL-10 IL-13, IL-16, IL-17, IL-18, IL-22, IL-32, and IL-35), the chemokines CCL (2,3,5,13,20,21,23), CXC (8,9,10,11,16), CX3CL1 (fractalkine), and GDF15. Adiponectin (an indicator of PPAR activation) and maresin 1 are reduced in SSc patients. A new trend has been the use of biomarker panels with combined complex multifactor analysis, machine learning, and artificial intelligence to determine disease activity and response to therapy. The present review is an update of the various biomarker molecules, pathways, and receptors involved in the pathology of SSc.

Spectrum of Cerebrovascular Disease in Scleroderma: A Case Series and Systematic Review

INTRODUCTION

Central nervous system involvement in scleroderma has traditionally been considered uncommon. Recent studies suggest that scleroderma might be associated with an increased risk of cerebrovascular disease (CBVD), independent of conventional cardiovascular risk factors. We present a case series and a systematic review to capture the spectrum of CBVD in scleroderma, through a detailed description of clinical, demographic, laboratory, and radiographical findings.

METHODS

In our case series, we included consecutive patients with scleroderma and CBVD seen over 35 years by our group in different hospitals in the USA. We also performed a systematic review from inception to July 2022. MEDLINE/Embase/WoS were searched for "scleroderma", "systemic scleroderma", "systemic sclerosis", "cerebrovascular", "stroke", "cerebrovascular disorders", "cerebrovascular disease".

RESULTS

Fourteen patients with scleroderma and CBVD were included in our case series (mean age 48 years, 85% female). CBVDs were ischemic stroke (64%), hemorrhagic stroke (7%), venous thrombosis (7%), ischemic optic neuropathy (7%), probable ischemic stroke (14%). Of the 110 studies identified in our systematic review (45,484 patients), 82 reports with patient-level data were included for quantitative analysis (93 patients, mean age 48 years, 79% female). Despite 16 different CBVD types identified, ischemic stroke was the most common CBVD (29%), followed by vasculopathy (20%), hemorrhage (12%), vasculitis (11%), and intracranial aneurysm (11%).

CONCLUSION

Our relatively large case series combined with a systematic review of CBVD in SCL patients shows a heterogeneous spectrum of CBVD etiology, with acute ischemic stroke being the most common in our cases and in our literature review. A complex interaction between chronic inflammation, autoimmune mechanisms, and endothelial dysfunction seems to underlie the CBVD heterogeneity in scleroderma patients. This review informs clinicians about the spectrum of CBVD related to scleroderma and raise awareness about scleroderma being a possible risk factor for early-onset CBVD.

The Prostacyclin Analogue Iloprost Modulates CXCL10 in Systemic Sclerosis

The prostacyclin analogue iloprost is used to treat vascular alterations and digital ulcers, the early derangements manifesting in systemic sclerosis (SSc), an autoimmune disease leading to skin and organ fibrosis. Bioindicator(s) of SSc onset and progress are still lacking and the therapeutic approach remains a challenge. The T helper 1 (Th1) chemokine interferon (IFN)γ-induced protein 10 (IP-10/CXCL10) associates with disease progression and worse prognosis. Endothelial cells and fibroblasts, under Th1-dominance, release CXCL10, further enhancing SSc’s detrimental status. We analyzed the effect of iloprost on CXCL10 in endothelial cells, dermal fibroblasts, and in the serum of SSc patients. Human endothelial cells and dermal fibroblasts activated with IFNγ/Tumor Necrosis Factor (TNF)α, with/without iloprost, were investigated for CXCL10 secretion/expression and for intracellular signaling cascade underlying chemokine release (Signal Transducer and Activator of Transcription 1, STAT1; Nuclear Factor kappa-light-chain-enhancer of activated B cells, NF-kB; c-Jun NH₂-terminal kinase, JNK: Phosphatidyl-Inositol 3-kinase (PI3K)/protein kinase B, AKT; Extracellular signal-Regulated Kinase 1/2, ERK1/2). CXCL10 was quantified in sera from 25 patients taking iloprost, satisfying the American College of Rheumatology (ACR)/European Alliance of Associations for Rheumatology (EULAR) 2013 classification criteria for SSc, and in sera from 20 SSc sex/age-matched subjects without therapy, previously collected. In human endothelial cells and fibroblasts, iloprost targeted CXCL10, almost preventing IFNγ/TNFα-dependent cascade activation in endothelial cells. In SSc subjects taking iloprost, serum CXCL10 was lower. These in vitro and in vivo data suggest a potential role of iloprost to limit CXCL10 at local vascular/dermal and systemic levels in SSc and warrant further translational research aimed to ameliorate SSc understanding/management.

Spontaneous innominate artery rupture in a patient with systemic sclerosis

We present the case of a 57-year-old female with systemic sclerosis who presented in extremis to our hospital with an acute onset of right upper chest and neck pain with swelling. She deteriorated rapidly due to haemodynamic compromise from suspected bleeding and suffered a cardiac arrest with prolonged resuscitation. Emergency thoracotomy demonstrated an acute longitudinal tear of the innominate artery/brachiocephalic trunk at the junction of the subclavian and common carotid arteries. This is the first reported case of spontaneous arterial rupture in a patient with systemic sclerosis, and while direct causation is difficult to prove, her history of previous vascular complications with potential ongoing microvascular damage makes a contributory role likely.

Effect of vasodilator and immunosuppressive therapy on the endothelial dysfunction in patients with systemic sclerosis

A comparative analysis of flow-mediated vasodilation (FMD), vasoactive angiogenic, and fibrogenic mediators between treatment-naive and treated systemic sclerosis (SSc) patients is an unmet need. (1)To assess the FMD and different pathogenic mediators in SSc patients about endothelial dysfunction. (2) To assess the proportion of circulating endothelial cells (CECs) in treatment-naïve patients. SSc patients were grouped into treatment-naïve (Group-I, n = 24) on vasodilator (Group-II, n = 10), on vasodilator + immunosuppressive (Group-III, n = 22)]. Age-sex matched healthy controls (n = 20) were included. Endothelial dysfunction (ED) was measured radiologically using FMD. Serum levels of NO, ET1, NO/ET1, sVCAM, sICAM, TGF, IL-6, and VEGF, as well as gene expressions of eNOS, iNOS, ET-1, and TGF, were measured to assess the status of ED in various study groups. CEC was measured in Group-I and HC. CEC was used as a marker to identify a key regulator of ED in SSc. FMD was significantly decreased in all SSc patients through receiving treatment. Upregulation of serum NO and ET concentrations was noted post-treatment with an unaltered NO/ET1 ratio. NO was positively correlated with FMD (r = 0.6) and negatively with TGFβ (r =  - 0.5). ET-1 showed a negative correlation with TGFβ (r =  - 0.5) but no significant correlation with FMD. Circulating endothelial cell (CEC) was significantly higher in Group-I (3.2%) than HC (0.8%) (p = 0.002), and it showed a good correlation with NO (r =  - 0.7, p = 0.0001) and NO/ET1 (r =  - 0.6, p = 0.007). Persistent ED was observed in all SSc patients irrespective of treatment. Dysbalance in NO/ET1 ratio might be the considering factor for the underlying progression of ED. Based on our findings, it may be hypothesized that reduced NO may be a contributing factor in the pathogenesis of endothelial dysfunction in SSc.

Pathogenetic Aspects of Systemic Sclerosis: A View Through the Prism of B Cells

Systemic sclerosis (SSc) is a rare fibrotic rheumatic disease, associated with psychological distress and increased morbidity and mortality due to skin involvement and internal organ damage. The current understanding of the complex pathogenesis is yet incomplete and disease therapeutic algorithms are far from optimal. Immunologic aberrations are considered key factors for the disease, along with vascular involvement and excess fibrosis. Adaptive immunity and its specialized responses are an attractive research target and both T and B cells have been extensively studied in recent years. In the present review, the focus is placed on B cells in SSc. B cell homeostasis is deranged and B cell subsets exhibit an activated phenotype and abnormal receptor signaling. Autoantibodies are a hallmark of the disease and the current perception of their diagnostic and pathogenetic role is analyzed. In addition, B cell cytokine release and its effect on immunity and fibrosis are examined, together with B cell tissue infiltration of the skin and lung. These data support the concept of targeting B cells as part of the therapeutic plan for SSc through well designed clinical trials.

The role of endothelin and RAS/ERK signaling in immunopathogenesis-related fibrosis in patients with systemic sclerosis: an updated review with therapeutic implications

Systemic sclerosis (SSc) is a disease of connective tissue with high rate of morbidity and mortality highlighted by extreme fibrosis affecting various organs such as the dermis, lungs, and heart. Until now, there is no specific cure for the fibrosis occurred in SSc disease. The SSc pathogenesis is yet unknown, but transforming growth factor beta (TGF-β), endothelin-1 (ET-1), and Ras-ERK1/2 cascade are the main factors contributing to the tissue fibrosis through extracellular matrix (ECM) accumulation. Several studies have hallmarked the association of ET-1 with or without TGF-β and Ras-ERK1/2 signaling in the development of SSc disease, vasculopathy, and fibrosis of the dermis, lungs, and several organs. Accordingly, different clinical and experimental studies have indicated the potential therapeutic role of ET-1 and Ras antagonists in these situations in SSc. In addition, ET-1 and connective tissue growth factor (CTGF) as a cofactor of the TGF-β cascade play a substantial initiative role in inducing fibrosis. Once initiated, TGF-β alone or in combination with ET-1 and CTGF can activate several kinase proteins such as the Ras-ERK1/2 pathway that serve as the fundamental factor for developing fibrosis. Furthermore, Salirasib is a synthetic small molecule that is able to inhibit all Ras forms. Therefore, it can be used as a potent therapeutic factor for fibrotic disorders. So, this review discusses the role of TGF-β/ET-1/Ras signaling and their involvement in SSc pathogenesis, particularly in its fibrotic situation.

Microangiopathy in Inflammatory Diseases-Strategies in Surgery of the Lower Extremity

BACKGROUND

Patients with an inflammatory disease frequently develop chronic angiopathy of the capillaries. Due to this pathology, there is an increased rate of complications in lower extremity surgical procedures. It is not uncommon for microangiopathic wound healing disorders to cause deep infections and fistulas, which lead to prolonged courses and hospitalizations. In addition, adhesions and ossifications of the contractile elements occur regularly. This sometimes results in serious limitations of the mobility of the patients. The study aims to present the results of a combination of vacuum and physical therapy.

PATIENT AND METHODS

A retrospective study of six patients with systemic sclerosis undergoing joint-related procedures of the lower extremity between 2015 and 2020 was performed. In addition to characterization of the patients and therapy, special attention was paid to cutaneous wound healing, affection of the fascia and displacement layers, and sclerosis of the muscle and tendon insertion.

RESULTS

The characterized structures (skin, tendon, fascia) show pathological changes at the microangiopathic level, which are associated with delayed healing and less physical capacity. Early suture removal regularly results in secondary scar dehiscence. With a stage-adapted vacuum therapy with sanitation of the deep structures and later on a dermal vacuum system, healing with simultaneous mobilization of the patients could be achieved in our patient cohort.

CONCLUSION

In the case of necessary interventions on the lower extremity, such as trauma surgery, additional decongestive measures in the sense of regular and sustained lymphatic therapy and adapted physiotherapy are indispensable.

Predicting clinical events using Bayesian multivariate linear mixed models with application to scleroderma

BACKGROUND

Scleroderma is a serious chronic autoimmune disease in which a patient's disease state manifests in several irregularly spaced longitudinal measures of lung, heart, skin, and other organ systems. Threshold crossings of pulmonary and cardiac measures indicate potentially life-threatening key clinical events including interstitial lung disease (ILD), cardiomyopathy, and pulmonary hypertension (PH). The statistical challenge is to accurately and precisely predict these events by using all of the clinical history for the patient at hand and for a reference population of patients.

METHODS

We use a Bayesian mixed model approach to simultaneously characterize each individual's future trajectories for several biomarkers. We estimate this model using a large population of patients from the Johns Hopkins Scleroderma Center Research Registry. The joint probabilities of critical lung and heart events are then calculated as a byproduct of the mixed model.

RESULTS

The performance of this approach is substantially better than standard, more common alternatives. In order to predict an individual's risks in a clinical setting, we also develop a cross-validated, sequential prediction (CVSP) algorithm. As additional data are observed during a patient's visit, the algorithm sequentially produces updated predictions for the future longitudinal trajectories and for ILD, cardiomyopathy, and PH. The updated prediction distributions with little additional computing, for example within an electronic health record (EHR).

CONCLUSIONS

This method that generates real-time personalized risk estimates has been implemented within the electronic health record system for clinical testing. To our knowledge, this work represents the first approach to compute personalized risk estimates for multiple scleroderma complications.

Role of Alarmins in the Pathogenesis of Systemic Sclerosis

Systemic sclerosis (SSc) is a rare chronic autoimmune disease associated with significant morbidity and mortality. Two main subsets of SSc are recognized: (i) diffuse cutaneous SSc with rapidly progressive fibrosis of the skin, lungs, and other internal organs; and (ii) limited cutaneous SSc, which is dominated by vascular manifestations, with skin and organ fibrosis generally limited and slowly progressing. In spite of intense investigation, both etiology and pathogenesis of SSc are still unknown. Genetic and environmental factors, as well as abnormalities of immune functions, are strongly suggested for etiology, while microvascular abnormalities, immune system activation, and oxidative stress are suggested for the pathogenesis. Recently, it has been found that a multitude of mediators and cytokines are implicated in the fibrotic processes observed in SSc. Among these, a central role could be exerted by “alarmins”, endogenous and constitutively expressed proteins/peptides that function as an intercellular signal defense. This review describes, in a detailed manner, the role of alarmins in the pathogenesis of scleroderma.

Exosomes in Systemic Sclerosis: Messengers Between Immune, Vascular and Fibrotic Components?

Systemic sclerosis (SSc) is a rare autoimmune disease, characterized by vasculopathy and fibrosis of the skin and internal organs. This disease is still considered incurable and is associated with a high risk of mortality, which is related to fibrotic events. An early diagnosis is useful for preventing complications, and targeted therapies reduce disease progression and ameliorate patients’ quality of life. Nevertheless, there are no validated biomarkers for early diagnosis with predictive prognostic value. Exosomes are membrane vesicles, transporting proteins and nucleic acids that may be delivered to target cells, which influences cellular behavior. They play important roles in cell–cell communication, both in physiological and pathological conditions, and may be useful as circulating biomarkers. Recent evidences suggest a role for these microvesicles in the three main aspects related to the pathogenesis of SSc (immunity, vascular damage, and fibrosis). Moreover, exosomes are of particular interest in the field of nano-delivery and are used as biological carriers. In this review, we report the latest information concerning SSc pathogenesis, clinical aspects of SSc, and current approaches to the treatment of SSc. Furthermore, we indicate a possible role of exosomes in SSc pathogenesis and suggest their potential use as diagnostic and prognostic biomarkers, as well as therapeutic tools.

Platelets in Skin Autoimmune Diseases

Systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and small vessel vasculitis are three autoimmune diseases frequently manifested in the skin. They share common pathogenic features, including production of autoantibodies, loss of tolerance to self-antigens, tissue necrosis and fibrosis, vasculopathy and activation of the coagulation system. Platelets occupy a central part within the coagulation cascade and are well-recognized for their hemostatic role. However, recent cumulative evidence implicates their additional and multifaceted immunoregulatory functions. Platelets express immune receptors and they store growth factors, cytokines, and chemokines in their granules enabling a significant contribution to inflammation. A plethora of activating triggers such as damage associated molecular patterns (DAMPs) released from damaged endothelial cells, immune complexes, or complement effector molecules can mediate platelet activation. Activated platelets further foster an inflammatory environment and the crosstalk with the endothelium and leukocytes by the release of immunoactive molecules and microparticles. Further insight into the pathogenic implications of platelet activation will pave the way for new therapeutic strategies targeting autoimmune diseases. In this review, we discuss the inflammatory functions of platelets and their mechanistic contribution to the pathophysiology of SSc, ANCA associated small vessel vasculitis and other autoimmune diseases affecting the skin.

Corneal Perforation after Nd: YAG Capsulotomy: A Case Report and Literature Review

Background

Nd: YAG capsulotomy is the treatment of choice for posterior capsular opacification after cataract surgery. We report a case of corneal perforation following Nd:YAG capsulotomy in a patient with systemic scleroderma.

Case Presentation

A 69-year-old woman presented with acute onset of blurred vision 2 weeks following Nd:YAG laser capsulotomy for posterior subcapsular opacification. On examination, her best-corrected visual acuity was 1/120, and bio-microscopy revealed a central full-thickness corneal laceration. Conservative treatment consisted of topical ocular antibiotics, cycloplegics, hypotensive drops and a soft therapeutic contact lens. Her final visual acuity improved to 6/18 with resolution of the corneal laceration.

Conclusion

The possibility of corneal perforation after Nd-YAG capsulotomy in patients with systemic scleroderma and connective tissue disease should be borne in mind when treating such patients.

The clinical effects of l-arginine and asymmetric dimethylarginine: implications for treatment in secondary Raynaud's phenomenon

Secondary Raynaud's phenomenon (RP) is often the sentinel clinical finding in systemic sclerosis and may precede systemic disease by several years. Altered nitric oxide metabolism plays a critical role in both fibrosis and severe secondary RP phenotypes in these patients. Increased flux through inducible nitric oxide synthase (iNOS) drives cutaneous fibrosis. Failure of flux through endothelial nitric oxide synthase (eNOS) contributes to increased vasoconstriction and decreased vasorelaxation. The underproduction of nitric oxide by eNOS is in part due to increased levels of asymmetric dimethylarginine (ADMA), an endogenous competitive inhibitor of nitric oxide synthase. The inhibitory effects of increased ADMA levels may be counteracted increasing serum l‐arginine, which is often an effective treatment strategy in these patients. As such, l‐arginine‐based therapies should be considered in managing secondary RP, particularly given their favourable safety and tolerability profile. While there is no established dosing regimen, studies of oral l‐arginine in secondary RP suggest that divided dosing may begin at 1–2 g/day and may be titrated up to 10 g/day. Conversely, primary RP is not associated with increased ADMA production which likely accounts for the failure of l‐arginine trials to show benefit in primary RP.

Cutaneous Manifestations of Scleroderma and Scleroderma-Like Disorders: a Comprehensive Review

Scleroderma refers to an autoimmune connective tissue fibrosing disease, including three different subsets: localized scleroderma, limited cutaneous systemic sclerosis, and diffuse cutaneous systemic sclerosis with divergent patterns of organ involvement, autoantibody profiles, management, and prognostic implications. Although systemic sclerosis is considered the disease prototype that causes cutaneous sclerosis, there are many other conditions that can mimic and be confused with SSc. They can be classified into immune-mediated/inflammatory, immune-mediated/inflammatory with abnormal deposit (mucinoses), genetic, drug-induced and toxic, metabolic, panniculitis/vascular, and (para)neoplastic disorders according to clinico-pathological and pathogenetic correlations. This article reviews the clinical presentation with emphasis on cutaneous disease, etiopathogenesis, diagnosis, and treatment options available for the different forms of scleroderma firstly and for scleroderma-like disorders, including scleromyxedema, scleredema, nephrogenic systemic fibrosis, eosinophilic fasciitis, chronic graft-versus-host disease, porphyria cutanea tarda, diabetic stiff-hand syndrome (diabetic cheiroartropathy), and other minor forms. This latter group of conditions, termed also scleroderma mimics, sclerodermiform diseases, or pseudosclerodermas, shares the common thread of skin thickening but presents with distinct cutaneous manifestations, skin histology, and systemic implications or disease associations, differentiating each entity from the others and from scleroderma. The lack of Raynaud's phenomenon, capillaroscopic abnormalities, or scleroderma-specific autoantibodies is also important diagnostic clues. As cutaneous involvement is the earliest, most frequent and characteristic manifestation of scleroderma and sclerodermoid disorders, dermatologists are often the first-line doctors who must be able to promptly recognize skin symptoms to provide the affected patient a correct diagnosis and appropriate management.

Effects of arterial blood on the venous blood vessel wall and differences in percentages of lymphocytes and neutrophils between arterial and venous blood

Vascular sclerosis mostly occurs in arteries and is mainly related to anatomic structure and hemodynamics of artery. This study aimed to investigate effects of arterial blood on vein wall and explore differences of composition between arterial and venous blood.Ultrasound was used to examine the distal venous structure of arteriovenous fistula in uremia patients. Immunohistochemistry was used to study the pathology of the distal vein. Twelve patients were divided into control group and trial group. Patients received an arteriovenous fistula within 1 month in control group. Patients had undergone this surgery ≥2 years before in the trial group. Blood samples were collected from the aortic, arterial, and venous vessels of 51 patients who had taken coronary angiography and analyzed with blood routine rest, biochemical, and immunological measures to compare the differences of blood composition between artery and vein. This study was registered with the China Clinical Trial Center website under registration number ChiCTR-OOC-16008085.In the trial group, the vascular wall of distal veins of fistula were thickened and hardened. No significant differences of blood composition were found between the aortic and radial arterial blood. However, the differences in the percentages of lymphocytes and neutrophils between arterial and venous blood were significant (Pa = .0095, Pb = .01).Under smooth hemodynamic conditions, arterial blood caused hardening of the venous wall. Arterial and venous blood differed in the percentage of lymphocyte and neutrophils. This may contribute to the vascular sclerosis that is observed in arteries more often than veins.

Selective deletion of PPARβ/δ in fibroblasts causes dermal fibrosis by attenuated LRG1 expression

Connective tissue diseases of the skin are characterized by excessive collagen deposition in the skin and internal organs. Fibroblasts play a pivotal role in the clinical presentation of these conditions. Nuclear receptor peroxisome-proliferator activated receptors (PPARs) are therapeutic targets for dermal fibrosis, but the contribution of the different PPAR subtypes are poorly understood. Particularly, the role of fibroblast PPARβ/δ in dermal fibrosis has not been elucidated. Thus, we generated a mouse strain with selective deletion of PPARβ/δ in the fibroblast (FSPCre-Pparb/d-/-) and interrogated its epidermal and dermal transcriptome profiles. We uncovered a downregulated gene, leucine-rich alpha-2-glycoprotein-1 (Lrg1), of previously unknown function in skin development and architecture. Our findings suggest that the regulation of Lrg1 by PPARβ/δ in fibroblasts is an important signaling conduit integrating PPARβ/δ and TGFβ1-signaling networks in skin health and disease. Thus, the FSPCre-Pparb/d-/- mouse model could serve as a novel tool in the current gunnery of animal models to better understand dermal fibrosis.

Optical coherence tomography angiography of normal skin and inflammatory dermatologic conditions

BACKGROUND

In clinical dermatology, the identification of subsurface vascular and structural features known to be associated with numerous cutaneous pathologies remains challenging without the use of invasive diagnostic tools.

OBJECTIVE

To present an advanced optical coherence tomography angiography (OCTA) method to directly visualize capillary-level vascular and structural features within skin in vivo.

METHODS

An advanced OCTA system with a 1310 nm wavelength was used to image the microvascular and structural features of various skin conditions. Subjects were enrolled and OCTA imaging was performed with a field of view of approximately 10 × 10 mm. Skin blood flow was identified using an optical microangiography (OMAG) algorithm. Depth-resolved microvascular networks and structural features were derived from segmented volume scans, representing tissue slabs of 0-132, 132-330, and 330-924 μm, measured from the surface of the skin.

RESULTS

Subjects with both healthy and pathological conditions, such as benign skin lesions, psoriasis, chronic graft-versus-host-disease (cGvHD), and scleroderma, were OCTA scanned. Our OCTA results detailed variations in vascularization and local anatomical characteristics, for example, depth-dependent vascular, and structural alterations in psoriatic skin, alongside their resolve over time; vascular density changes and distribution irregularities, together with corresponding structural depositions in the skin of cGvHD patients; and vascular abnormalities in the nail folds of a patient with scleroderma.

CONCLUSION

OCTA can image capillary blood flow and structural features within skin in vivo, which has the potential to provide new insights into the pathophysiology, as well as dynamic changes of skin diseases, valuable for diagnoses, and non-invasive monitoring of disease progression and treatment. Lasers Surg. Med. 50:183-193, 2018. © 2018 Wiley Periodicals, Inc.

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.

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.

T and NK Cell Phenotypic Abnormalities in Systemic Sclerosis: a Cohort Study and a Comprehensive Literature Review

Scleroderma (SSc) is a rare and heterogeneous immune-mediated disease involving the connective tissue and microvasculature whose pathogenesis remains unclear. Data concerning T and natural killer (NK) cell abnormalities and cytokine levels in the peripheral blood (PB) from patients with SSc are scarce, and the results are contradictory. The present study aimed to analyze the changes of T lymphocytes, NK cells, and T helper (Th)-related cytokines in the PB of patients with SSc in comparison to healthy individuals and its relation to disease subtype and stage, organ involvement, and nailfold capillaroscopic changes. A non-random convenience sample of 57 scleroderma patients was utilized. Fifty-five out of the 57 patients studied were women (97 %); 10 patients presented pre-scleroderma (pre-SSc) and 47 SSc: 34 limited cutaneous SSc (lcSSc) and 13 diffuse cutaneous SSc (dcSSc). Patients with SSc were classified in early (n = 7), intermediate (n = 10), and late (n = 30) disease. Blood samples were analyzed by flow cytometry for total T cells, CD4+ and CD8+ T cell subsets, total NK cells, and CD56+low and CD56+high NK cell subsets. T cells were further analyzed for the expression of the CD56 adhesion molecule and activation-related markers (HLA-DR, CD45RO). In addition, the serum levels of Th1-, Th2-, and Th17-related cytokines were measured by flow cytometry. Twenty-five healthy individuals recruited from the blood bank were used as controls. Patients had lower numbers of total lymphocytes and T cells comparing to healthy controls. Both CD4+ and CD8+ T cells were decreased, but differences were statistically significant only for CD8+ and CD8+ CD45RO+ T cells. These alterations were seen in patients with SSc but not in patients with pre-SSc, and, in general, they were more pronounced in patients with dcSSc than in patients with lcSSc, in patients with vascular involvement than in those without, as well as in patients having active and late nailfold capillaroscopic patterns. CD56+ T cells were also decreased in SSc patients, especially in those with active/late capillaroscopic patterns or with severe lung disease. Diminished numbers of circulating NK cells were also observed in patients with lcSSc and in those with early disease. No statistically significant changes were found in serum cytokine levels, as compared with controls. Patients with SSc had major alterations in circulating CD8+ and CD56+ T cells, as well as in NK cells, suggesting that these cells may play a relevant role in SSc pathogenesis, probably operating at different phases and/or at different organs. In addition, the serum levels of Th1, Th2, and Th17 cytokines did not provide useful information for evaluating T cell polarization in SSc.

Intrinsic Deregulation of Vascular Smooth Muscle and Myofibroblast Differentiation in Mesenchymal Stromal Cells from Patients with Systemic Sclerosis

Introduction

Obliterative vasculopathy and fibrosis are hallmarks of systemic sclerosis (SSc), a severe systemic autoimmune disease. Bone marrow-derived mesenchymal stromal cells (MSCs) from SSc patients may harbor disease-specific abnormalities. We hypothesized disturbed vascular smooth muscle cell (VSMC) differentiation with increased propensity towards myofibroblast differentiation in response to SSc-microenvironment defining growth factors and determined responsible mechanisms.

Methods

We studied responses of multipotent MSCs from SSc-patients (SSc-MSCs) and healthy controls (H-MSCs) to long-term exposure to CTGF, b-FGF, PDGF-BB or TGF-β1. Differentiation towards VSMC and myofibroblast lineages was analyzed on phenotypic, biochemical, and functional levels. Intracellular signaling studies included analysis of TGF-β receptor regulation, SMAD, AKT, ERK1/2 and autocrine loops.

Results

VSMC differentiation towards both, contractile and synthetic VSMC phenotypes in response to CTGF and b-FGF was disturbed in SSc-MSCs. H-MSCs and SSc-MSCs responded equally to PDGF-BB with prototypic fibroblastic differentiation. TGF-β1 initiated myofibroblast differentiation in both cell types, yet with striking phenotypic and functional differences: In relation to H-MSC-derived myofibroblasts induced by TGF-β1, those obtained from SSc-MSCs expressed more contractile proteins, migrated towards TGF-β1, had low proliferative capacity, and secreted higher amounts of collagen paralleled by reduced MMP expression. Higher levels of TGF-β receptor 1 and enhanced canonical and noncanonical TGF-β signaling in SSc-MSCs accompanied aberrant differentiation response of SSc-MSCs in comparison to H-MSCs.

Conclusions

Deregulated VSMC differentiation with a shift towards myofibroblast differentiation expands the concept of disturbed endogenous regenerative capacity of MSCs from SSc patients. Disease related intrinsic hyperresponsiveness to TGF-β1 with increased collagen production may represent one responsible mechanism. Better understanding of repair barriers and harnessing beneficial differentiation processes in MSCs could widen options of autologous MSC application in SSc patients.

Clinical Phenotype of Endothelial Dysfunction in Romanian Scleroderma Patients

OBJECTIVE

To identify the particularities of the clinical phenotype of endothelial dysfunction in a lot of Romanian patients from a reference center and compare it to data reported by international registries.

MATERIAL AND METHODS

51 patients were included in a cross-sectional study. The patients were evaluated for the pattern of disease, main visceral involvement, serum markers of disease.

RESULTS

41.2% patients had history of digital ulcers, 27.45% had pulmonary arterial hypertension; cardiovascular involvement also included: diastolic dysfunction in 31.1% of the patients, global systolic dysfunction in 9.8%, rhythm and conduction disturbances in 19.6%, peripheral vascular disease in 19.6%. Scleroderma renal crisis was identified in 2 patients.

CONCLUSION

Vascular complications are a major cause of morbidity and mortality in systemic sclerosis. Earlier therapeutic intervention demands improved screening and diagnosis in all cases.

Clinical Phenotype of Endothelial Dysfunction in a Lot of Romanian Scleroderma Patients

OBJECTIVES

to identify the particularities of the clinical phenotype of endothelial dysfunction in a lot of Romanian patients from a reference center and compare it to data reported by international registries.

MATERIALS AND METHODS

51 patients were included in a cross sectional study. The patients were evaluated for the pattern of disease, main visceral involvement, serum markers of disease.

RESULTS

41.2% patients had history of digital ulcers, 27.45% had pulmonary arterial hypertension; cardiovascular involvement also included: diastolic dysfunction in 31.1% of the patients, global systolic dysfunction in 9.8%, rhythm and conduction disturbances in 19.6%, peripheral vascular disease in 19.6%. Scleroderma renal crisis was identified in 2 patients.

CONCLUSION

Vascular complications are a major cause of morbidity and mortality in systemic sclerosis. Earlier therapeutic intervention demands improved screening and diagnosis in all cases.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

Regulatory mechanisms of anthrax toxin receptor 1-dependent vascular and connective tissue homeostasis

It is well known that angiogenesis is linked to fibrotic processes in fibroproliferative diseases, but insights into pathophysiological processes are limited, due to lack of understanding of molecular mechanisms controlling endothelial and fibroblastic homeostasis. We demonstrate here that the matrix receptor anthrax toxin receptor 1 (ANTXR1), also known as tumor endothelial marker 8 (TEM8), is an essential component of these mechanisms. Loss of TEM8 function in mice causes reduced synthesis of endothelial basement membrane components and hyperproliferative and leaky blood vessels in skin. In addition, endothelial cell alterations in mutants are almost identical to those of endothelial cells in infantile hemangioma lesions, including activated VEGF receptor signaling in endothelial cells, increased expression of the downstream targets VEGF and CXCL12, and increased numbers of macrophages and mast cells. In contrast, loss of TEM8 in fibroblasts leads to increased rates of synthesis of fiber-forming collagens, resulting in progressive fibrosis in skin and other organs. Compromised interactions between TEM8-deficient endothelial and fibroblastic cells cause dramatic reduction in the activity of the matrix-degrading enzyme MMP2. In addition to insights into mechanisms of connective tissue homeostasis, our data provide molecular explanations for vascular and connective tissue abnormalities in GAPO syndrome, caused by loss-of-function mutations in ANTXR1. Furthermore, the loss of MMP2 activity suggests that fibrotic skin abnormalities in GAPO syndrome are, in part, the consequence of pathophysiological mechanisms underlying syndromes (NAO, Torg and Winchester) with multicentric skin nodulosis and osteolysis caused by homozygous loss-of-function mutations in MMP2.

Association of immunological cell profiles with specific clinical phenotypes of scleroderma disease

This study aimed to search the correlation among immunological profiles and clinical phenotypes of scleroderma in well-characterized groups of scleroderma patients, comparing forty-nine scleroderma patients stratified according to specific clinical phenotypes with forty-nine healthy controls. Five immunological cell subpopulations (B, CD4(+) and CD8(+) T-cells, NK, and monocytes) and their respective stages of apoptosis and activation were analyzed by flow cytometry, in samples of peripheral blood mononuclear cells (PBMCs). Analyses of results were stratified according to disease stage, time since the diagnosis, and visceral damage (pulmonary fibrosis, pulmonary hypertension, and cardiac affliction) and by time of treatment with corticosteroids. An increase in the percentages of monocytes and a decrease in the B cells were mainly related to the disease progression. A general apoptosis decrease was found in all phenotypes studied, except in localized scleroderma. An increase of B and NK cells activation was found in patients diagnosed more than 10 years ago. Specific cell populations like monocytes, NK, and B cells were associated with the type of affected organ. This study shows how, in a heterogeneous disease, proper patient's stratification according to clinical phenotypes allows finding specific cellular profiles. Our data may lead to improvements in the knowledge of prognosis factors and to aid in the analysis of future specific therapies.

Endothelial cells recruit macrophages and contribute to a fibrotic milieu in bleomycin lung injury

Systemic sclerosis (SSc) is a systemic autoimmune disease that causes inflammation, vasculopathy, and fibrosis of the skin and internal organs. One of the most severe complications of SSc involves the development of pulmonary fibrosis. Endothelial cell injury precedes the development of fibrosis, and is believed to be an initiating event. Therefore, we aimed to characterize the role of endothelial cells in the progression of pulmonary fibrosis, using a well-established bleomycin (BLM) model of pulmonary fibrosis. Endothelial cells were isolated by cell sorting, and the analysis of gene expression was performed with quantitative RT-PCR. Endothelial injury was induced between the first and second week, as shown by the elevated expression of the vascular injury markers matrix metallopeptidase-12 and von Willebrand factor. After injury, endothelial activation was indicated by the up-regulation of selectins, CCL chemokines, and inflammatory mediators, including complement anaphylatoxin receptors (C3aR and C5aR), oncostatin M, and leukemia inhibitory factor. The endothelial cell overexpression of fibrotic mediators, including connective tissue growth factor, plasminogen activator inhibitor-1, osteopontin, fibronectin, and fibroblast specific protein-1, was observed in the second and fourth weeks. This study suggests that endothelial cells actively contribute to the disease process via multiple mechanisms, including the recruitment of inflammatory cells and the establishment of a profibrotic environment during the development of BLM-induced pulmonary fibrosis.

Steroidogenesis in the skin: implications for local immune functions

The skin has developed a hierarchy of systems that encompasses the skin immune and local steroidogenic activities in order to protect the body against the external environment and biological factors and to maintain local homeostasis. Most recently it has been established that skin cells contain the entire biochemical apparatus necessary for production of glucocorticoids, androgens and estrogens either from precursors of systemic origin or, alternatively, through the conversion of cholesterol to pregnenolone and its subsequent transformation to biologically active steroids. Examples of these products are corticosterone, cortisol, testosterone, dihydrotesterone and estradiol. Their local production can be regulated by locally produced corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) or cytokines. Furthermore the production of glucocorticoids is affected by ultraviolet B radiation. The level of production and nature of the final steroid products are dependent on the cell type or cutaneous compartment, e.g., epidermis, dermis, adnexal structures or adipose tissue. Locally produced glucocorticoids, androgens and estrogens affect functions of the epidermis and adnexal structures as well as local immune activity. Malfunction of these steroidogenic activities can lead to inflammatory disorders or autoimmune diseases. The cutaneous steroidogenic system can also have systemic effects, which are emphasized by significant skin contribution to circulating androgens and/or estrogens. Furthermore, local activity of CYP11A1 can produce novel 7Δ-steroids and secosteroids that are biologically active. Therefore, modulation of local steroidogenic activity may serve as a new therapeutic approach for treatment of inflammatory disorders, autoimmune processes or other skin disorders. In conclusion, the skin can be defined as an independent steroidogenic organ, whose activity can affect its functions and the development of local or systemic inflammatory or autoimmune diseases. This article is part of a Special Issue entitled 'CSR 2013'.

Interferon-γ promotes vascular remodeling in human microvascular endothelial cells by upregulating endothelin (ET)-1 and transforming growth factor (TGF) β2

Systemic sclerosis (SSc) is a complex disease characterized by vascular alterations, activation of the immune system and tissue fibrosis. Previous studies have implicated activation of the interferon pathways in the pathogenesis of SSc. The goal of this study was to determine whether interferon type I and/or type II could play a pathogenic role in SSc vasculopathy. Human dermal microvascular endothelial cells (HDMVECs) and fibroblasts were obtained from foreskins of healthy newborns. The RT Profiler PCR Array System was utilized to screen for EndoMT genes. Treatment with IFN-α or IFN-γ downregulated Fli1 and VE-cadherin. In contrast, IFN-α and IFN-γ exerted opposite effects on the expression of α-SMA, CTGF, ET-1, and TGFβ2, with IFN-α downregulating and IFN-γ upregulating this set of genes. Blockade of TGFβ signaling normalized IFN-γ-mediated changes in Fli1, VE-cadherin, CTGF, and ET-1 levels, whereas upregulation of α-SMA and TGFβ2 was not affected. Bosentan treatment was more effective than TGFβ blockade in reversing the actions of IFN-γ, including downregulation of α-SMA and TGFβ2, suggesting that activation of the ET-1 pathway plays a main role in the IFN-γ responses in HDMECs. IFN-γ induced expression of selected genes related to endothelial-to-mesenchymal transition (EndoMT), including Snail1, FN1, PAI1, TWIST1, STAT3, RGS2, and components of the WNT pathway. The effect of IFN-γ on EndoMT was mediated via TGFβ2 and ET-1 signaling pathways. This study demonstrates distinct effects of IFN-α and IFN-γ on the biology of vascular endothelial cells. IFN-γ may contribute to abnormal vascular remodeling and fibrogenesis in SSc, partially via induction of EndoMT.

The role of platelets in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is an inflammatory disease of unknown etiology characterized by widespread organ dysfunction due to fibrosis and ischemia. Its nebulous pathogenic background and the consequent absence of an etiological therapy prevent the adoption of satisfying treatment strategies, able to improve patients’ quality of life and survival and stimulate researchers to identify a unifying pathogenic target. Platelets show a unique biological behavior, lying at the crossroads between vascular function, innate and adaptive immunity, and regulation of cell proliferation. Consequently they are also emerging players in the pathogenesis of many inflammatory diseases, including SSc. In the setting of SSc platelets are detectable in a persistent activated state, which is intimately linked to the concomitant presence of an injured endothelium and to the widespread activation of the innate and adaptive immune system. As a consistent circulating source of bioactive compounds platelets contribute to the development of many characteristic phenomena of SSc, such as fibrosis and impaired vascular tone.