Angiotensin II in the lesional skin of systemic sclerosis patients contributes to tissue fibrosis via angiotensin II type 1 receptors

Part I: Epidemiology, pathophysiology, and clinical considerations of primary and secondary Raynaud's phenomenon

Raynaud's phenomenon (RP) is a relatively common disease with both primary and secondary forms. It is well understood as a vasospastic condition affecting the acral and digital arteries, resulting in characteristic, well-demarcated color changes typically in the hands and feet in response to cold or stress. Secondary RP (SRP) has been described in association with a variety of rheumatologic and nonrheumatologic diseases, environmental exposures, and/or medications. While both primary RP and SRP may impact the quality of life, SRP may lead to permanent and potentially devastating tissue destruction when undiagnosed and untreated. It is therefore crucial for dermatologists to distinguish between primary and secondary disease forms early in clinical evaluation, investigate potential underlying causes, and risk stratify SRP patients for the development of associated autoimmune connective tissue disease. The epidemiology, pathogenesis, and clinical presentation and diagnosis of both forms of RP are described in detail in this review article.

Role of SARS-COV-2 and ACE2 in the pathophysiology of peripheral vascular diseases

The occurrence of a novel coronavirus known as severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), created a serious challenge worldwide. SARS-CoV-2 has high infectivity, the ability to be transmitted even during the asymptomatic phase, and relatively low virulence, which has resulted in rapid transmission. SARS-CoV-2 can invade epithelial cells, hence, many patients infected with SARS-CoV-2 have suffered from vascular diseases (VDs) in addition to pulmonary manifestations. Accordingly, SARS-CoV-2 may can worsen the clinical condition of the patients with pre-existing VDs. Endothelial cells express angiotensin-converting enzyme 2 (ACE2). ACE2 is a biological enzyme that converts angiotensin (Ang)- 2 to Ang-(1-7). SARS-CoV-2 uses ACE2 as a cell receptor for viral entry. Thus, the SARS-CoV-2 virus promotes downregulation of ACE2, Ang-(1-7), and anti-inflammatory cytokines, as well as, an increase in Ang-2, resulting in pro-inflammatory cytokines. SARS-CoV-2 infection can cause hypertension, and endothelial damage, which can lead to intravascular thrombosis. In this review, we have concentrated on the effect of SARS-CoV-2 in peripheral vascular diseases (PVDs) and ACE2 as an enzyme in Renin-angiotensin aldosterone system (RAAS). A comprehensive search was performed on PubMed, Google Scholar, Scopus, using related keywords. Articles focusing on ("SARS-CoV-2", OR "COVID-19"), AND ("Vascular disease", OR "Peripheral vascular disease", OR interested disease name) with regard to MeSH terms, were selected. According to the studies, it is supposed that vascular diseases may increase susceptibility to severe SARS-CoV-2 infection due to increased thrombotic burden and endothelial dysfunction. Understanding SARS-CoV-2 infection mechanism and vascular system pathogenesis is crucial for effective management and treatment in pre-existing vascular diseases.

Topical captopril: a promising treatment for secondary lymphedema

Transforming growth factor-beta 1 (TGF-β1)-mediated tissue fibrosis is an important regulator of lymphatic dysfunction in secondary lymphedema. However, TGF-β1 targeting can cause toxicity and autoimmune complications, limiting clinical utility. Angiotensin II (Ang II) modulates intracellular TGF-β1 signaling, and inhibition of Ang II production using angiotensin-converting enzyme (ACE) inhibitors, such as captopril, has antifibrotic efficacy in some pathological settings. Therefore, we analyzed the expression of ACE and Ang II in clinical lymphedema biopsy specimens from patients with unilateral breast cancer-related lymphedema (BCRL) and mouse models, and found that cutaneous ACE expression is increased in lymphedematous tissues. Furthermore, topical captopril decreases fibrosis, activation of intracellular TGF-β1 signaling pathways, inflammation, and swelling in mouse models of lymphedema. Captopril treatment also improves lymphatic function and immune cell trafficking by increasing collecting lymphatic pumping. Our results show that the renin-angiotensin system in the skin plays an important role in the regulation of fibrosis in lymphedema, and inhibition of this signaling pathway may hold merit for treating lymphedema.

When natural antibodies become pathogenic: autoantibodies targeted against G protein-coupled receptors in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a chronic, multisystem connective tissue, and autoimmune disease with the highest case-specific mortality and complications among rheumatic diseases. It is characterized by complex and variable features such as autoimmunity and inflammation, vasculopathy, and fibrosis, which pose challenges in understanding the pathogenesis of the disease. Among the large variety of autoantibodies (Abs) present in the sera of patients suffering from SSc, functionally active Abs against G protein-coupled receptors (GPCRs), the most abundant integral membrane proteins, have drawn much attention over the last decades. These Abs play an essential role in regulating the immune system, and their functions are dysregulated in diverse pathological conditions. Emerging evidence indicates that functional Abs targeting GPCRs, such as angiotensin II type 1 receptor (AT1R) and the endothelin-1 type A receptor (ETAR), are altered in SSc. These Abs are part of a network with several GPCR Abs, such as those directed to the chemokine receptors or coagulative thrombin receptors. In this review, we summarize the effects of Abs against GPCRs in SSc pathologies. Extending the knowledge on pathophysiological roles of Abs against GPCRs could provide insights into a better understanding of GPCR contribution to SSc pathogenesis and therefore help in developing potential therapeutic strategies that intervene with pathological functions of these receptors.

Autoimmune pre-disease

Approximately 5% of the world-wide population is affected by autoimmune diseases. Overall, autoimmune diseases are still difficult to treat, impose a high burden on patients, and have a significant economic impact. Like other complex diseases, e.g., cancer, autoimmune diseases develop over several years. Decisive steps in the development of autoimmune diseases are (i) the development of autoantigen-specific lymphocytes and (often) autoantibodies and (ii) potentially clinical disease manifestation at a later stage. However, not all healthy individuals with autoantibodies develop disease manifestations. Identifying autoantibody-positive healthy individuals and monitoring and inhibiting their switch to inflammatory autoimmune disease conditions are currently in their infancy. The switch from harmless to inflammatory autoantigen-specific T and B-cell and autoantibody responses seems to be the hallmark for the decisive factor in inflammatory autoimmune disease conditions. Accordingly, biomarkers allowing us to predict this progression would have a significant impact. Several factors, such as genetics and the environment, especially diet, smoking, exposure to pollutants, infections, stress, and shift work, might influence the progression from harmless to inflammatory autoimmune conditions. To inspire research directed at defining and ultimately targeting autoimmune predisease, here, we review published evidence underlying the progression from health to autoimmune predisease and ultimately to clinically manifest inflammatory autoimmune disease, addressing the following 3 questions: (i) what is the current status, (ii) what is missing, (iii) and what are the future perspectives for defining and modulating autoimmune predisease.

A phase 2 trial investigating the effects of the angiotensin II type 2 receptor agonist C21 in systemic sclerosis-related Raynaud's

OBJECTIVE

Our main aim was to investigate the effect of a single oral dose of C21, a selective angiotensin II type 2 receptor agonist, on cold-induced vasoconstriction in SSc-related RP.

METHODS

This was a phase IIa, randomized, double-blind, cross-over, single-dose, placebo-controlled, single-centre study. Twelve female patients with SSc (median age 58.5 years, median duration of RP 19.0 years) attended on four occasions: screening, treatment visits 1 and 2 (separated by 3-7 days) and follow-up. At the first treatment visit, patients were randomized to receive either a single oral dose of C21 (200 mg) or placebo, then the opposite treatment on the second visit. Forty min after each treatment, each patient underwent a standard hand cold challenge. The primary end point was the area under the curve (AUC) for rewarming for each finger (eight fingers) over 15 min. Secondary end points included the maximum finger temperature after rewarming (MAX). Statistical analyses were performed by multiplicative ANCOVA models.

RESULTS

For all eight fingers combined, mean AUC for rewarming was higher after treatment with C21 than after placebo (geometric mean 20 046°C*s vs 19 558°C*s), but not significantly (P = 0.380) and MAX (at 15 min) was also higher (geometric mean 23.5°C vs 22.5°C; P = 0.036). C21 was well tolerated.

CONCLUSION

Despite the small trial size, a signal emerged suggesting that even in patients with established SSc, C21 may confer benefit for RP and deserves further investigation.

TRIAL REGISTRATION

ClinicalTrials.gov, https://clinicaltrials.gov, NCT04388176.

Autoantibodies as Biomarker and Therapeutic Target in Systemic Sclerosis

Systemic sclerosis (SSc) is a rare connective tissue disorder characterized by immune dysregulation evoking the pathophysiological triad of inflammation, fibrosis and vasculopathy. In SSc, several alterations in the B-cell compartment have been described, leading to polyclonal B-cell hyperreactivity, hypergammaglobulinemia and autoantibody production. Autoreactive B cells and autoantibodies promote and maintain pathologic mechanisms. In addition, autoantibodies in SSc are important biomarkers for predicting clinical phenotype and disease progression. Autoreactive B cells and autoantibodies represent potentially promising targets for therapeutic approaches including B-cell-targeting therapies, as well as strategies for unselective and selective removal of autoantibodies. In this review, we present mechanisms of the innate immune system leading to the generation of autoantibodies, alterations of the B-cell compartment in SSc, autoantibodies as biomarkers and autoantibody-mediated pathologies in SSc as well as potential therapeutic approaches to target these.

A broad look into the future of systemic sclerosis

Systemic sclerosis (SSc) is a systemic autoimmune disease with the key features of inflammation, vasculopathy and fibrosis. This article focussed on emerging fields based on the authors' current work and expertise. The authors provide a hierarchical structure into the studies of the pathogenesis of SSc starting with the contribution of environmental factors. Regulatory autoantibodies (abs) are discussed, which are parts of the human physiology and are specifically dysregulated in SSc. Abs against the angiotensin II receptor subtype 1 (AT1R) and the endothelin receptor type A (ETAR) are discussed in more detail. Extracellular vesicles are another novel player to possess disease processes. Fibroblasts are a key effector cell in SSc. Therefore, the current review will provide an overview about their plasticity in the phenotype and function. Promising nuclear receptors as key regulators of transcriptional programmes will be introduced as well as epigenetic modifications, which are pivotal to maintain the profibrotic fibroblast phenotype independent of external stimuli. Fibroblasts from SSc patients exhibit a specific signalling and reactivate developmental pathways and stem cell maintenance such as by employing hedgehog and WNT, which promote fibroblast-to-myofibroblast transition and extracellular matrix generation. Pharmacological interventions, although for other indications, are already in clinical use to address pathologic signalling.

Fibrotic Scar in CNS Injuries: From the Cellular Origins of Fibroblasts to the Molecular Processes of Fibrotic Scar Formation

Central nervous system (CNS) trauma activates a persistent repair response that leads to fibrotic scar formation within the lesion. This scarring is similar to other organ fibrosis in many ways; however, the unique features of the CNS differentiate it from other organs. In this review, we discuss fibrotic scar formation in CNS trauma, including the cellular origins of fibroblasts, the mechanism of fibrotic scar formation following an injury, as well as the implication of the fibrotic scar in CNS tissue remodeling and regeneration. While discussing the shared features of CNS fibrotic scar and fibrosis outside the CNS, we highlight their differences and discuss therapeutic targets that may enhance regeneration in the CNS.

Animal Models of Systemic Sclerosis: Using Nailfold Capillaroscopy as a Potential Tool to Evaluate Microcirculation and Microangiopathy: A Narrative Review

Systemic sclerosis (SSc) is an autoimmune disease with three pathogenic hallmarks, i.e., inflammation, vasculopathy, and fibrosis. A wide plethora of animal models have been developed to address the complex pathophysiology and for the development of possible anti-fibrotic treatments. However, no current model comprises all three pathological mechanisms of the disease. To highlight the lack of a complete model, a review of some of the most widely used animal models for SSc was performed. In addition, to date, no model has accomplished the recreation of primary or secondary Raynaud’s phenomenon, a key feature in SSc. In humans, nailfold capillaroscopy (NFC) has been used to evaluate secondary Raynaud’s phenomenon and microvasculature changes in SSc. Being a non-invasive technique, it is widely used both in clinical studies and as a tool for clinical evaluation. Because of this, its potential use in animal models has been neglected. We evaluated NFC in guinea pigs to investigate the possibility of applying this technique to study microcirculation in the nailfold of animal models and in the future, development of an animal model for Raynaud’s phenomenon. The applications are not only to elucidate the pathophysiological mechanisms of vasculopathy but can also be used in the development of novel treatment options.

Poor Performance of Angiotensin II Enzyme-Linked Immuno-Sorbent Assays in Mostly Hypertensive Cohort Routinely Screened for Primary Aldosteronism

Primary aldosteronism (PA) is the most common, but broadly underdiagnosed, form of hormonal hypertension. To improve screening procedures, current biochemical approaches aim to determine newly appreciated angiotensin II (Ang II) and calculate the aldosterone-to-angiotensin II ratio (AA2R). Thus, the aim of this study was to assess the diagnostic performance of these screening tests in comparison to the aldosterone-to-direct renin ratio (ADRR), which is routinely used. Cheap and available ELISA was used for Ang II measurement. To our knowledge, this is the first study of this laboratory method’s usage in PA. The study cohort included 20 PA patients and 80 controls. Ang II concentrations were comparable between PA and non-PA patients (773.5 vs. 873.2 pg/mL, p = 0.23, respectively). The AA2R was statistically significantly higher in PA group when compared with non-PA (0.024 vs. 0.012 ng/dL/pg/mL, p < 0.001). However, the diagnostic performance of the AA2R was significantly worse than that of the ADRR (AUROC 0.754 vs. 0.939, p < 0.01). The sensitivity and specificity of the AA2R were 70% and 76.2%, respectively. Thus, the AA2R was not effective as a screening tool for PA. Our data provide important arguments in the discussion on the unsatisfactory accuracy of renin−angiotensin system evaluation by recently repeatedly used ELISA tests.

α2-Antiplasmin as a Potential Therapeutic Target for Systemic Sclerosis

Systemic sclerosis is a connective tissue disease of unknown origin that is characterized by immune system abnormalities, vascular damage, and extensive fibrosis of the skin and visceral organs. α2-antiplasmin is known to be the main plasmin inhibitor and has various functions such as cell differentiation and cytokine production, as well as the regulation of the maintenance of the immune system, endothelial homeostasis, and extracellular matrix metabolism. The expression of α2-antiplasmin is elevated in dermal fibroblasts from systemic sclerosis patients, and the blockade of α2-antiplasmin suppresses fibrosis progression and vascular dysfunction in systemic sclerosis model mice. α2-antiplasmin may have promise as a potential therapeutic target for systemic sclerosis. This review considers the role of α2-antiplasmin in the progression of systemic sclerosis.

Neuropeptide Cortistatin Regulates Dermal and Pulmonary Fibrosis in an Experimental Model of Systemic Sclerosis

INTRODUCTION

Scleroderma, or systemic sclerosis, is a complex connective tissue disorder characterized by autoimmunity, vasculopathy, and progressive fibrosis of the skin and internal organs. Because its aetiology is unknown, the identification of genes/factors involved in disease severity, differential clinical forms, and associated complications is critical for understanding its pathogenesis and designing novel treatments. Neuroendocrine mediators in the skin emerge as potential candidates. We investigated the role played by the neuropeptide cortistatin in a preclinical model of scleroderma.

METHODS

Dermal fibrosis was induced by repetitive intradermal injections of bleomycin in wild-type and cortistatin-deficient mice. The histopathological signs and expression of fibrotic markers were evaluated in the skin and lungs.

RESULTS

An inverse correlation between cortistatin levels and fibrogenic activation exists in the damaged skin and dermal fibroblasts. Bleomycin-challenged skin lesions of mice that are partially and totally deficient in cortistatin showed exacerbated histopathological signs of scleroderma, characterized by thicker and more fibrotic dermal layer, enlarged epidermis, and increased inflammatory infiltration in comparison to those of wild-type mice. Cortistatin deficiency enhanced dermal collagen deposits, connective tissue growth factor expression, loss of microvessels, and predisposition to suffer severe complications that co-occur with dermal exposition to bleomycin, including pulmonary fibrotic disease and increased mortality. Treatment with cortistatin mitigated these pathological processes.

DISCUSSION/CONCLUSION

We identify cortistatin as an endogenous break of skin inflammation and fibrosis. Deficiency in cortistatin could be a marker of poor prognosis of scleroderma and associated complications. Cortistatin-based therapies emerge as attractive candidates to treat severe forms of systemic sclerosis and to manage fibrosis-related side effects of bleomycin chemotherapy in oncologic patients.

Raynaud's Phenomenon: Reviewing the Pathophysiology and Management Strategies

Raynaud's phenomenon (RP) is a multifactorial vasospastic disorder characterized by a transient, recurrent, and reversible constriction of peripheral blood vessels. RP is documented to affect up to 5% of the general population, but variation in its prevalence is commonly recognized owing to many factors, including varied definitions, gender, genetics, hormones, and region. Furthermore, RP may be idiopathic or be a clinical manifestation of an underlying illness. Patients with RP classically describe a triphasic discoloration of the affected area, beginning with pallor, followed by cyanosis, and finally ending with erythema. This change in color spares the thumb and is often associated with pain. Each attack may persist from several minutes to hours. Moreover, the transient cessation of blood flow in RP is postulated to be mediated by neural and vascular mechanisms. Both structural and functional alterations observed in the blood vessels contribute to the vascular abnormalities documented in RP. However, functional impairment serves as a primary contributor to the pathophysiology of primary Raynaud's. Substances like endothelin-1, angiotensin, and angiopoietin-2 play a significant role in the vessel-mediated pathophysiology of RP. The role of nitric oxide in the development of this phenomenon is still complex. Neural abnormalities resulting in RP are recognized as either being concerned with central mechanisms or peripheral mechanisms. CNS involvement in RP may be suggested by the fact that emotional distress and low temperature serve as major triggers for an attack, but recent observations have highlighted the importance of locally produced factors in this regard as well. Impaired vasodilation, increased vasoconstriction, and several intravascular abnormalities have been documented as potential contributors to the development of this disorder. RP has also been observed to occur as a side effect of various drugs. Recent advances in understanding the mechanism of RP have yielded better pharmacological therapies. However, general lifestyle modifications along with other nonpharmacological interventions remain first-line in the management of these patients. Calcium channel blockers, alpha-1 adrenoreceptor antagonists, angiotensin-converting enzyme inhibitors, nitric oxide, prostaglandin analogs, and phosphodiesterase inhibitors are some of the common classes of drugs that have been found to be therapeutically significant in the management of RP. Additionally, anxiety management, measures to avoid colder temperatures, and smoking cessation, along with other simple modifications, have proven to be effective non-drug strategies in patients experiencing milder symptoms.

Cellular and Molecular Diversity in Scleroderma

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

The prevalence and role of functional autoantibodies to angiotensin-converting-enzyme-2 in patients with systemic sclerosis

INTRODUCTION

Systemic sclerosis (SSc) is an autoimmune disease caused by the imbalance between the activity of angiotensin II and angiotensin-(1-7). Their balance should be controlled by angiotensin-converting enzyme 2 (ACE2), which degrades angiotensin II into angiotensin-(1-7). Previously, autoantibodies to ACE2 (anti-ACE2) were identified in patients with vasculopathy due to different connective tissue diseases, including SSc, but their frequency in SSc was not further analyzed. The aim of the research was to investigate the prevalence and potential role of those anti-ACE2 antibodies in SSc patients.

MATERIALS AND METHODS

There were enrolled 27 patients with SSc and 23 healthy donors. ELISA assay determined the presence of anti-ACE2 autoantibodies in serum samples. The results were compared to plasma measurements of angiotensin-(1-7) level via commercial ELISA.

RESULTS

The presence of anti-ACE2 autoantibodies was confirmed in five patients with SSc and two healthy controls. Two of those SSc subjects were anti-Scl70+, another two were double anti-Scl70+ and anti-Ro/SSA+, and anti-PM/Scl antibodies were detected in one patient. Median plasma level of Ang-(1-7) in anti-ACE2 negative patients was 47.4 pg/ml and stayed below the detection level in anti-ACE2 positive subjects. The plasma level of Ang-(1-7) was undetectable in four SSc patients, and three of them were anti-ACE2 positive.

CONCLUSIONS

Anti-ACE2 antibodies appear to be other functional autoantibodies with the potential to dysregulate the balance between Ang II and Ang-(1-7). They are non-specific for SSc and probably result from polyautoimmunity which affect some of SSc patients. Their occurrence in SSc settings may be associated with a severe depletion of plasma Ang-(1-7).

The Potential Association between the Risk of Post-Surgical Adhesion and the Activated Local Angiotensin II Type 1 Receptors: Need for Novel Treatment Strategies

Background

Post-surgical adhesion bands (PSABs) are a common complication after abdominal or pelvic surgeries for different reasons like cancer treatment. Despite improvements in surgical techniques and the administration of drugs or the use of physical barriers, there has only been limited improvement in the frequency of postoperative adhesions. Complications of PSAB are pain, infertility, intestinal obstruction, and increased mortality. The most important molecular mechanisms for the development of PSAB are inflammatory response, oxidative stress, and overexpression of pro-fibrotic molecules such as transforming growth factor β. However, questions remain about the pathogenesis of this problem, for example, the causes for individual differences or why certain tissue sites are more prone to post-surgical adhesions.

Summary

Addressing the pathological causes of PSAB, the potential role of local angiotensin II/angiotensin II type 1 receptors (AngII/AT1R), may help to prevent this problem.

Key Message

The objective of this article was to explore the role of the AngII/AT1R axis potential to induce PSAB and the therapeutic potential of angiotensin receptor blockers in the prevention and treatment of PSAB.

Angiotensin-Converting Enzyme Inhibitor, Captopril, Improves Scar Healing in Hypertensive Rats

Pathological cutaneous scars, with aberrant extracellular matrix accumulation, have multiple origins. Antihypertensive medications, such as calcium channel blockers, have been used to treat pathological scars. However, a relationship between angiotensin-converting enzyme (ACE) inhibitors, pathological scars, and blood pressure (BP) has never been reported. Here, we aimed to compare the differences in scar development and the effects of the administration of systemic ACE inhibitor on scar tissue in a normotensive rat, the Wistar Kyoto rat (WKY), a hypertensive rat, and the spontaneously hypertensive rat (SHR). Using an 8-mm punch, we created two full-thickness skin defects in a total of 32 rats (16 WKY and 16 SHR) to obtain a total of 64 wounds. We established control WKY (n = 16), captopril-treated WKY (n = 16), control SHR (n = 16), and captopril-treated SHR (n = 16) groups and started captopril (100 mg/g per day) treatment on day 21 in the appropriate groups. The BP of all groups was measured at 0, 3, and 5 weeks. The scar area was measured by histopathological examination, and scarring was expressed in terms of scar area and fibroblast and capillary counts. The expression of heat shock protein (HSP) 47, type I and III collagens, alpha-smooth muscle actin (α-SMA), Ki67, and vascular endothelial growth factor (VEGF) was investigated using immunohistochemistry. The scar area and fibroblast count were significantly higher in control SHR than in control WKY. The scar area, fibroblast count, and capillary count were significantly smaller in captopril-treated SHR than in control SHR. Immunostaining for α-SMA, Ki67, and VEGF also showed a noticeable decrease in scarring in the treated SHR compared with that in control SHR. Thus, BP affects scar development in a rat model, and an ACE inhibitor is more effective at reducing scars in hypertensive rats than in normotensive rats.

What Makes Antibodies Against G Protein-Coupled Receptors so Special? A Novel Concept to Understand Chronic Diseases

Expressions of G protein-coupled receptors (GPCR) on immune and tissue resident cells are the consequence of the cellular environment, which is highly variable. As discussed here, antibodies directed to GPCR (GPCR abs), their levels and correlations to other abs, serve as biomarkers for various diseases. They also could reflect the individual interplay between the environment and the immune system. Thus, GPCR abs could display pathogenic chronic conditions and could help to identify disease-related pathways. Moreover, by acting as ligands to their corresponding receptors, GPCR abs modulate autoimmune as well as non-autoimmune diseases. This article introduces GPCR abs as drivers for diseases by their capability to induce a specific signaling and by determining immune cell homeostasis. The identification of the individual GPCR ab function is challenging but might be pivotal in the comprehension of the aetiology of diseases. This, hopefully, will lead to the identification of novel therapeutic strategies. This article provides an overview about concepts and recent developments in research. Accordingly, GPCR abs could represent ideal candidates for precision medicine. Here, we introduce the term antibodiom to cover the network of abs with GPCR abs as prominent players.

Pathogenic roles of autoantibodies in systemic sclerosis: Current understandings in pathogenesis

The potential pathogenic role for autoantibodies in systemic sclerosis has captivated researchers for the past 40 years. This review answers the question whether there is yet sufficient knowledge to conclude that certain serum autoantibodies associated with systemic sclerosis contribute to its pathogenesis. Definitions for pathogenic, pathogenetic and functional autoantibodies are formulated, and the need to differentiate these autoantibodies from natural autoantibodies is emphasized. In addition, seven criteria for the identification of pathogenic autoantibodies are proposed. Experimental evidence is reviewed relevant to the classic systemic sclerosis antinuclear autoantibodies, anti-topoisomerase I and anticentromere, and to functional autoantibodies to endothelin 1 type A receptor, angiotensin II type 1 receptor, muscarinic receptor 3, platelet-derived growth factor receptor, chemokine receptors CXCR3 and CXCR4, estrogen receptor α, and CD22. Pathogenic evidence is also reviewed for anti-matrix metalloproteinases 1 and 3, anti-fibrillin 1, anti-IFI16, anti-eIF2B, anti-ICAM-1, and anti-RuvBL1/RuvBL2 autoantibodies. For each autoantibody, objective evidence for a pathogenic role is scored qualitatively according to the seven pathogenicity criteria. It is concluded that anti-topoisomerase I is the single autoantibody specificity with the most evidence in favor of a pathogenic role in systemic sclerosis, followed by anticentromere. However, these autoantibodies have not been demonstrated yet to fulfill completely the seven proposed criteria for pathogenicity. Their contributory roles to the pathogenesis of systemic sclerosis remain possible but not yet conclusively demonstrated. With respect to functional autoantibodies and other autoantibodies, only a few criteria for pathogenicity are fulfilled. Their common presence in healthy and disease controls suggests that major subsets of these immunoglobulins are natural autoantibodies. While some of these autoantibodies may be pathogenetic in systemic sclerosis, establishing that they are truly pathogenic is a work in progress. Experimental data are difficult to interpret because high serum autoantibody levels may be due to polyclonal B-cell activation. Other limitations in experimental design are the use of total serum immunoglobulin G rather than affinity-purified autoantibodies, the confounding effect of other systemic sclerosis autoantibodies present in total immunoglobulin G and the lack of longitudinal studies to determine if autoantibody titers fluctuate with systemic sclerosis activity and severity. These intriguing new specificities expand the spectrum of autoantibodies observed in systemic sclerosis. Continuing elucidation of their potential mechanistic roles raises hope of a better understanding of systemic sclerosis pathogenesis leading to improved therapies.

Significance of the angiotensin I/angiotensin II/angiotensin-(1-7) axis in the pathogenesis of systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a multisystemic disease with an extensive microvasculopathy. Previously, disturbances in plasma levels of angiotensin II (Ang II) and its antagonistic angiotensin-(1-7) (Ang-(1-7)) were found in patients with SSc. Their significance in a pathogenesis of SSc stays unclear due to discrepancies of earlier studies.

OBJECTIVES

To evaluate a significance of disturbances in production pathway of angiotensins in a development of SSc.

METHODS

There were enrolled 27 patients with established SSc, 23 subjects with very early SSc and 23 healthy controls. The diagnosis of SSc was established in patients who met EULAR/ACR 2013 classification criteria. Very early SSc described patients with Raynaud's phenomenon having SSc-specific antinuclear antibodies and SSc-like abnormalities in nailfold videocapillaroscopy. Patients were submitted to evaluation of internal organ involvement and blood sampling to assay plasma levels of angiotensin I, angiotensin II and angiotensin-(1-7) with ELISA technique.

RESULTS

Plasma level of angiotensin-(1-7) was significantly reduced in both SSc group (median = 47.2 pg/mL; P < 0.001) and ones with very early SSc (median = 102.7 pg/mL; P = 0.002) when compared to healthy controls (median = 176.1 pg/mL). A tendency to higher than in control group (median = 214 pg/mL) plasma level of angiotensin I was seen in SSc group (median = 392 pg/mL; P = 0.059). Differences in plasma level of angiotensin II were insignificant between all study groups. Those disturbances produced unfavourable angiotensin-(1-7)/angiotensin II (%) ratio in both groups of patients, which achieved statistical significance in subjects with established SSc (P < 0.001). Production pathway of angiotensins showed a dependence on a subtype of SSc, immune profile and a presence of interstitial lung disease.

CONCLUSIONS

Production of angiotensin-(1-7) was significantly reduced in both SSc patients and those ones with very early SSc, although a significant imbalance between angiotensin II and angiotensin-(1-7) occurred only in subjects with established disease.

Dermal Interstitial Alterations in Patients With Heart Failure and Reduced Ejection Fraction: A Potential Contributor to Fluid Accumulation?

BACKGROUND

Large networks of interstitial glycosaminoglycans help to regulate water and electrolyte homeostasis. The relation between dermal interstitial alterations and occurrence of edema in heart failure patients with reduced ejection fraction (HFrEF) is unknown. We hypothesize that in HFrEF patients (1) interstitial glycosaminoglycan density is increased, (2) changes in the interstitial glycosaminoglycan network are associated with interstitial fluid accumulation, and (3) there is a link between the interstitial glycosaminoglycan network and the renin-angiotensin-aldosterone system.

METHODS AND RESULTS

Two punch biopsies of the skin were obtained in healthy subjects (n=18) and HFrEF patients (n=29). Alcian blue staining and immunostaining for the angiotensin II type 1 receptor was performed. After obtaining tissue water content, total interstitial glycosaminoglycan (uronic acid) and sulfated glycosaminoglycan were quantified. A venous blood sample, clinical examination, and echocardiography were obtained. A significantly higher interstitial glycosaminoglycan content was observed in HFrEF patients compared with healthy subjects (uronic acid: 13.0±4.2 versus 9.6±1.6 μg/mg; P=0.002; sulfated glycosaminoglycan: 14.1 [11.7; 18.1] versus 10.0 [9.1; 10.8] μg/mg; P<0.001). Uronic acid and sulfated glycosaminoglycan density were strongly associated with tissue water content and peripheral edema (uronic acid: ρ=0.66; P<0.0001 and sulfated glycosaminoglycan: τ=0.58; P<0.0001). Expression of the angiotensin II type 1 receptor was found on dermal cells, although use of angiotensin-converting enzyme inhibitors/angiotensin receptor blocker was associated with significantly lower levels of interstitial glycosaminoglycans in HFrEF patients.

CONCLUSIONS

Interstitial glycosaminoglycan concentration is significantly increased in HFrEF patients compared with healthy subjects and correlated with tissue water content and clinical signs of volume overload. A better appreciation of the interstitial compartment might improve management of volume overload in HF.

Cardiac phenotype in mouse models of systemic autoimmunity

Patients suffering from systemic autoimmune diseases are at significant risk of cardiovascular complications. This can be due to systemically increased levels of inflammation leading to accelerated atherosclerosis, or due to direct damage to the tissues and cells of the heart. Cardiac complications include an increased risk of myocardial infarction, myocarditis and dilated cardiomyopathy, valve disease, endothelial dysfunction, excessive fibrosis, and bona fide autoimmune-mediated tissue damage by autoantibodies or auto-reactive cells. There is, however, still a considerable need to better understand how to diagnose and treat cardiac complications in autoimmune patients. A range of inducible and spontaneous mouse models of systemic autoimmune diseases is available for mechanistic and therapeutic studies. For this Review, we systematically collated information on the cardiac phenotype in the most common inducible, spontaneous and engineered mouse models of systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis. We also highlight selected lesser-known models of interest to provide researchers with a decision framework to choose the most suitable model for their study of heart involvement in systemic autoimmunity.

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.

Oxidative/nitrative stress in the pathogenesis of systemic sclerosis: are antioxidants beneficial?

Systemic sclerosis (SSc) is a multisystem autoimmune disease: characterised from the clinical side by progressive vasculopathy and fibrosis of the skin and different organs and from the biochemical side by fibroblast deregulation with excessive production of collagen and increased expression of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4). The latter contributes to an overproduction of reactive oxygen species that through an autocrine loop maintains NOX4 in a state of activation. Reactive oxygen and nitrogen species are implicated in the origin and perpetuation of several clinical manifestations of SSc having vascular damage in common; attempts to dampen oxidative and nitrative stress through different agents with antioxidant properties have not translated into a sustained clinical benefit. Objective of this narrative review is to describe the origin and clinical implications of oxidative and nitrative stress in SSc, with particular focus on the central role of NOX4 and its interactions, to re-evaluate the antioxidant approaches so far used to limit disease progression, to appraise the complexity of antioxidant treatment and to touch on novel pathways elements of which may represent specific treatment targets in the not so distant future.

Therapeutic interleukin-6 blockade reverses transforming growth factor-beta pathway activation in dermal fibroblasts: insights from the faSScinate clinical trial in systemic sclerosis

Objectives

Skin fibrosis mediated by activated dermal fibroblasts is a hallmark of systemic sclerosis (SSc), especially in the subset of patients with diffuse disease. Transforming growth factor-beta (TGFβ) and interleukin-6 (IL-6) are key candidate mediators in SSc. Our aim was to elucidate the specific effect of IL-6 pathway blockade on the biology of SSc fibroblasts in vivo by using samples from a unique clinical experiment—the faSScinate study—in which patients with SSc were treated for 24 weeks with tocilizumab (TCZ), an IL-6 receptor-α inhibitor.

Methods

We analysed the molecular, functional and genomic characteristics of explant fibroblasts cultured from matched skin biopsy samples collected at baseline and at week 24 from 12 patients receiving placebo (n=6) or TCZ (n=6) and compared these with matched healthy control fibroblast strains.

Results

The hallmark functional and molecular-activated phenotype was defined in SSc samples and was stable over 24 weeks in placebo-treated cases. RNA sequencing analysis robustly defined key dysregulated pathways likely to drive SSc fibroblast activation in vivo. Treatment with TCZ for 24 weeks profoundly altered the biological characteristics of explant dermal fibroblasts by normalising functional properties and reversing gene expression profiles dominated by TGFβ-regulated genes and molecular pathways.

Conclusions

We demonstrated the exceptional value of using explant dermal fibroblast cultures from a well-designed trial in SSc to provide a molecular framework linking IL-6 to key profibrotic pathways. The profound impact of IL-6R blockade on the activated fibroblast phenotype highlights the potential of IL-6 as a therapeutic target in SSc and other fibrotic diseases.

Trial registration number

NCT01532869; Post-results.

Pathogenesis of systemic sclerosis-current concept and emerging treatments

Systemic sclerosis (SSc) is an intractable multifaceted disease with high mortality. Although its pathogenesis is not fully understood, recent studies have advanced our knowledge on SSc. The cardinal pathological features of SSc are autoimmunity, vasculopathy, and fibrosis. The B cells in SSc are constitutively activated and lead to the production of a plethora of autoantibodies, such as anti-topoisomerase I and anti-centromere antibodies. In addition to these autoantibodies, which are valuable for diagnostic criteria or biomarkers, many other autoantibodies targeting endothelial cells, including endothelin type A receptor and angiotensin II type I receptor, are known to be functional and induce activation or apoptosis of endothelial cells. The autoantibody-mediated endothelial cell perturbation facilitates inflammatory cell infiltration, cytokine production, and myofibroblastic transformation of fibroblasts and endothelial cells. Profibrotic cytokines, such as transforming growth factor β, connective tissue growth factor, interleukin 4/interleukin 13, and interleukin 6, play a pivotal role in collagen production from myofibroblasts. Specific treatments targeting these causative molecules may improve the clinical outcomes of patients with SSc. In this review, we summarize recent topics on the pathogenesis (autoantibodies, vasculopathy, and fibrosis), animal models, and emerging treatments for SSc.

Inhibitory Effects of Angiotensin II Receptor Blockade on Human Tenon Fibroblast Migration and Reactive Oxygen Species Production in Cell Culture

Purpose

We investigate the effect of angiotensin receptor blockade on the migration of human Tenon fibroblasts (HTF), using irbesartan, an angiotensin II receptor type 1 (AT1R) blocker (ARB) as a potential antifibrotic agent in glaucoma filtration surgery.

Methods

Confluent HTF cultures were scratched with a 1 mL pipette tip and treated with either irbesartan (10, 50, and 100 μg/mL) or angiotensin II (2 μg/mL). The extent of HTF migration up to 30 hours, and cell number and morphology at 72 hours was evaluated. To assess the effect on reactive oxygen species (ROS) level, HTF were treated with either irbesartan (10 μg/mL) or angiotensin II (2 μg/mL) for 24 hours after scratching, and then stained with dihydroethidium (DHE) before evaluation by confocal microscopy.

Results

Irbesartan inhibited HTF migration by 50% to 70% compared to controls (P < 0.05). Levels of ROS were almost completely attenuated by irbesartan (DHE fluorescence intensity of 5.68E-09) (P < 0.05). Irbesartan reduced cell numbers by 50% and induced morphologic changes with loss of pseudopods (P < 0.05). Conversely, angiotensin II increased cell numbers up to 4-fold while retaining cell viability.

Conclusions

Irbesartan inhibited HTF migration and ROS production. It also reduced cell numbers and altered HTF morphology. Angiotensin II increased cell number without altering morphology. This initial study warrants future investigations for further potential antifibrotic effects of this drug.

Translational Relevance

This in vitro study focused on investigations of irbesartan's effects on HTF migration, ROS production, as well as HTF cell numbers and morphology. It suggests a potential therapeutic strategy worth further exploration with a view towards postoperative wound healing modulation in glaucoma filtration surgery.

Comparison of Enalapril, Candesartan and Intralesional Triamcinolone in Reducing Hypertrophic Scar Development: An Experimental Study

BACKGROUND

The purpose of this study was to compare the effects of oral enalapril, an angiotensin-converting enzyme inhibitor (ACE-I), oral candesartan, an angiotensin receptor blocker (ARB), and intralesional corticosteroid treatments in reducing scar formation.

METHODS

Twenty male rabbits were divided into five study groups: A (sham), B (control), C (ACE-I), D (ARB) and E (intralesional corticosteroid). The rabbit ear hypertrophic scar model was used. The hypertrophic scars were photographed and analyzed with the program ImageJ quantitatively to determine the degree of collagen fibers. The scar elevation index (SEI) was calculated at the end of the 40th day. Tissue samples were stained with hematoxylin and eosin and Masson's trichrome and examined under light microscopy for the determination of fibroblast number, epithelization, vascularization, inflammation and fibrosis.

RESULTS

The SEI was the highest in the control group with the highest number of fibroblasts under the epithelium. In the steroid group, the SEI was significantly lower than both the ACE-I (p: 0.02) and ARB (p: 0.001) groups. The density of type 1 collagen fibers was the lowest in the control group, whereas type 3 collagen fibers were highest in that group. The ACE-I and ARB groups were similar regarding densities of type 1 and type 3 collagen fibers. The density of type 1 collagen fibers was the highest in the steroid group, whereas the density of type 3 collagen fibers was the lowest in that group.

CONCLUSIONS

Enalapril, candesartan and intralesional steroid therapies were all effective in reducing scar tissue development; however, enalapril and steroid groups revealed better results.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Functional autoantibodies targeting G protein-coupled receptors in rheumatic diseases

G protein-coupled receptors (GPCRs) comprise the largest and most diverse family of integral membrane proteins that participate in different physiological processes such as the regulation of the nervous and immune systems. Besides the endogenous ligands of GPCRs, functional autoantibodies are also able to bind GPCRs to trigger or block intracellular signalling pathways, resulting in agonistic or antagonistic effects, respectively. In this Review, the effects of functional GPCR-targeting autoantibodies on the pathogenesis of autoimmune diseases, including rheumatic diseases, are discussed. Autoantibodies targeting β1 and β2 adrenergic receptors, which are expressed by cardiac and airway smooth muscle cells, respectively, have an important role in the development of asthma and cardiovascular diseases. In addition, high levels of autoantibodies against the muscarinic acetylcholine receptor M3 as well as those targeting endothelin receptor type A and type 1 angiotensin II receptor have several implications in the pathogenesis of rheumatic diseases such as Sjögren syndrome and systemic sclerosis. Expanding the knowledge of the pathophysiological roles of autoantibodies against GPCRs will shed light on the biology of these receptors and open avenues for new therapeutic approaches.

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.

Functional autoantibodies directed against cell surface receptors in systemic sclerosis

Systemic sclerosis (SSc) is a complex and heterogeneous systemic autoimmune disease characterized by the presence of high serum levels of antibodies targeting a variety of self-antigens. In addition to autoantibodies directed against nuclear antigens, patients with SSc also develop high serum levels of functional autoantibodies that target cell surface receptors when compared to healthy subjects. Following binding to extracellular receptors, these functional autoantibodies trigger the activation of signal transducing pathways, resulting in a stimulatory or suppressive effect. For example, stimulatory autoantibodies toward platelet-derived growth factor receptor (PDGFR) or antibodies targeting G protein–coupled receptors (e.g., angiotensin II receptor type 1 and endothelin receptor type A) have pleiotropic roles in the pathogenesis of SSc. High levels of these functional autoantibodies dysregulate the response of non-immune cells (e.g., fibroblasts and endothelial cells) as well as innate and adaptive immune cells, including myeloid cells and lymphocytes, respectively. Thus, the immunobiology of such autoantibodies clarifies why patients with SSc develop clinical features such as extensive fibrosis, vasculopathies and abnormal immune responses. Future interventions that modulate the natural production of functional autoantibodies that target cell surface receptors or neutralize such autoantibodies would be essential in reducing morbidity and mortality rates presented by SSc patients.

Blockade of PDGF Receptors by Crenolanib Has Therapeutic Effect in Patient Fibroblasts and in Preclinical Models of Systemic Sclerosis

Systemic sclerosis (SSc) is a multi-organ fibrotic disease with few treatment options. Activated fibroblasts are the key effector cells in SSc responsible for the excessive production of collagen and the development of fibrosis. Platelet-derived growth factor (PDGF), a potent mitogen for cells of mesenchymal origin, has been implicated in the activation of SSc fibroblasts. Our aim was to examine the therapeutic potential of crenolanib, an inhibitor of PDGF receptor signaling, in cultured fibroblasts and in angiotensin II-induced skin and heart fibrosis. Crenolanib effectively inhibited proliferation and migration of SSc and healthy control fibroblasts and attenuated basal and transforming growth factor-β-induced expression of CCN2/CTGF and periostin. In contrast to healthy control fibroblasts, SSc fibroblasts proliferated in response to PDGFAA, whereas a combination of PDGFAA and CCN2 was required to elicit a similar response in healthy control fibroblasts. PDGF receptor α mRNA correlated with CCN2 and other fibrotic markers in the skin of SSc patients. In mice challenged with angiotensin II, PDGF receptor α-positive cells were increased in the skin and heart. These PDGF receptor α-positive cells co-localized with PDGF receptor β, procollagen, and periostin. Treatment with crenolanib attenuated the skin and heart fibrosis. Our data indicate that inhibition of PDGF signaling presents an attractive therapeutic approach for SSc.

Monocytic Angiotensin and Endothelin Receptor Imbalance Modulate Secretion of the Profibrotic Chemokine Ligand 18

Objective.

To assess monocytic expression and ratio of angiotensin and endothelin receptors in systemic sclerosis (SSc) and their functional relevance.

Methods.

Receptor expression was measured by flow cytometry. Chemokine ligand 18 (CCL18) concentration in supernatants of peripheral blood mononuclear cells stimulated with immunoglobulin G was measured by ELISA.

Results.

Monocytes of patients with SSc presented an increased angiotensin II Type 1 receptor (AT1R)/AT2R ratio compared with those of healthy donors. Patients with lung fibrosis and patients with high modified Rodnan skin score showed a reduced endothelin 1 Type A receptor (ETAR)/ETBR ratio. High AT1R/AT2R, but low ETAR/ETBR ratios corresponded to higher CCL18 secretion.

Conclusion.

Altered angiotensin and endothelin receptor ratios observed in SSc influence autoantibody-mediated effects such as secretion of profibrotic CCL18.

The role of endothelial microparticles in autoimmune disease patients with Raynaud's phenomenon

BACKGROUND AND AIM

Raynaud's phenomenon (RP) is a microvascular disorder characterized by episodic peripheral vasospasm and ischemia and is commonly found in patients with autoimmune diseases (AID). The vasomotor homoeostasis and endothelial cells damage are involved in RP. Endothelial microparticles (EMPs) may act as a biomarker for endothelial damage. The aim of this study is to investigate the correlation between the levels of microparticles (MPs) and microvasculopathy in AID with RP.

METHODS

Thirty-seven patients with AID and RP (RP group) and 27 patients with AID but without RP (non-RP group) were enrolled. The microvasculopathy score of RP was graded by nailfold capillary microscopy. The plasma levels of MPs were measured by flow cytometry utilizing specific labels for endothelial MPs (CD105 and CD144) and annexin V staining for phosphatidylserine bearing-MPs (annexin V+MPs).

RESULTS

The levels of circulating EMPs (CD105+ p = 0.005, CD144+ p = 0.004), and the annexin V+ MPs (p < 0.001) were significantly elevated in the RP group compared with the non-RP group. Moreover, the high microvasculopathy scores were closely related with annexinV+ MPs levels in the RP group (p = 0.041).

CONCLUSIONS

Levels of circulating EMPs and annexin V+ MPs are elevated in AID patients with RP indicate the endothelial damage and endothelial dysfunctions. In addition, levels of annexin V+ MPs can predict the severity of microvasculopathy in AID with RP.

Systemic sclerosis: New evidence re-enforces the role of B cells

Systemic sclerosis (SSc) is characterized by widespread fibrosis, microangiopathy (vasospasms and stenosis), and formation of autoantibodies. T cell activation has been shown to contribute to fibrosis and microvasculopathy in SSc. However, recent evidence suggests that B cells are also likely to contribute in the pathogenesis of the disease. B cells are hyperactivated in SSc, as indicated by the overexpression of the stimulatory CD19 receptor and impairment of the inhibitory CD22 receptor. They lead to the production of many autoantibodies, some of which induce collagen production and vasoconstriction. They promote fibroblast collagen production through cell contact. Furthermore, B cells can function as antigen-presenting cells to T cells and induce dendritic cell maturation that promotes profibrotic Th2 response. Lately, interleukin (IL)-10-producing B regulatory cells, which induce generation of T regulatory cells and can ameliorate autoimmune diseases, were found to be reduced in SSc, favoring autoaggression of B cells in this disease. Finally, B cell depletion with rituximab improves or stabilizes skin fibrosis and lung function. These finding suggest that new therapeutic strategies targeting B cell function(s) can be developed for SSc.

Role of chymase in the local renin-angiotensin system in keloids: inhibition of chymase may be an effective therapeutic approach to treat keloids

Background

Histologically, keloids contain excess fibroblasts and an overabundance of dermal collagen. Recently, it was reported that chymase induced a profibrotic response via transforming growth factor-β1 (TGF-β1)/Smad activation in keloid fibroblasts (KFs). However, the role of chymase in the local renin-angiotensin system (RAS) in keloids has not been elucidated. This study aims to determine whether chymase plays an important role in the local RAS in keloids.

Methods

We compared the expression and activity of chymase in keloids and normal skin tissues using Western blotting and radioimmunoassay, and studied the expression of TGF-β1, interleukin-1β, collagen I, hydroxyproline, and angiotensin II in KFs after chymase and inhibitors’ treatment.

Results

The results revealed an increased activity of chymase in keloid tissues, and that chymase enhanced the expression of angiotensin II, collagen I, TGF-β1, and interleukin-1β in KFs. Blockade of the chymase pathway involved in the local RAS lowered the expression of these signaling factors.

Conclusion

This research suggests that inhibition of chymase might be an effective therapeutic approach to improve the clinical treatment of keloids.

Autoantibodies against Endothelin 1 Type A Receptor Are Strong Predictors of Digital Ulcers in Systemic Sclerosis

OBJECTIVE

To determine the predictive value of functional autoantibodies against vascular receptors for the development of ischemic digital ulcers (DU) in patients with systemic sclerosis (SSc).

METHODS

Angiotensin II Type 1 receptor (AT1R) and endothelin 1 Type A receptor (ETAR) autoantibodies were measured at baseline in a prospective cohort of 90 patients with SSc together with 5 validated angiogenic markers. The primary outcome was the occurrence of at least 1 new ischemic DU during the 5-year followup.

RESULTS

Twenty-four patients developed at least 1 new DU during the followup period. Univariate Cox analysis revealed that concentrations above the median value of anti-AT1R and anti-ETAR antibodies were predictive of the occurrence of ischemic DU (HR 2.85, 95% CI 1.19-6.84 and HR 3.39, 95% CI 1.35-8.50, respectively). A first multivariate Cox analysis including functional autoantibodies and clinical predictors of new DU confirmed anti-ETAR autoantibodies as independent predictors of the occurrence of new ischemic DU (HR 3.15, 95% CI 1.22-8.13) together with a history of DU at baseline. In a second model implemented with angiogenic markers, anti-ETAR autoantibodies remained an independent predictor of the occurrence of new ischemic DU (HR 9.59, 95% CI 1.75-52.64) together with the presence at baseline of active DU or history of DU.

CONCLUSION

Anti-ETAR autoantibodies can be used together with the presence of current or past DU to identify patients with SSc who are at risk for the development of subsequent DU. These autoantibodies may allow for earlier management and therapeutic intervention.

Angiotensin II inhibitor facilitates epidermal wound regeneration in diabetic mice

Tissue regeneration and wound healing are severely impaired in diabetes and are associated with poor circulation and dysfunctional blood vessels. Angiotensin II inhibitors are anti-hypertensive drugs used in clinical practice to regulate blood pressure and could affect tissue remodeling. We hypothesize that blocking angiotensin II, using Losartan, could facilitate tissue regeneration in diabetic mice. To this end, we established an experimental model of wound healing in streptozotocin-induced diabetic mice. Our data demonstrated that Losartan accelerates wound repair and normalizes wound stromal responses, having a beneficial role in wounds of diabetic individuals. Our findings highlight a potential therapeutic use of Losartan in improving wound repair in diabetic conditions.

Angiotensin receptor I stimulates osteoprogenitor proliferation through TGFβ-mediated signaling

Clinical studies of large human populations and pharmacological interventions in rodent models have recently suggested that anti-hypertensive drugs that target angiotensin II (Ang II) activity may also reduce loss of bone mineral density. Here, we identified in a genetic screening the Ang II type I receptor (AT1R) as a potential determinant of osteogenic differentiation and, implicitly, bone formation. Silencing of AT1R expression by RNA interference severely impaired the maturation of a multipotent mesenchymal cell line (W20-17) along the osteoblastic lineage. The same effect was also observed after the addition of the AT1R antagonist losartan but not the AT2R inhibitor PD123,319. Additional cell culture assays traced the time of greatest losartan action to the early stages of W20-17 differentiation, namely during cell proliferation. Indeed, addition of Ang II increased proliferation of differentiating W20-17 and primary mesenchymal stem cells and this stimulation was reversed by losartan treatment. Cells treated with losartan also displayed an appreciable decrease of activated (phosphorylated)-Smad2/3 proteins. Moreover, Ang II treatment elevated endogenous transforming growth factor β (TGFβ) expression considerably and in an AT1R-dependent manner. Finally, exogenous TGFβ was able to restore high proliferative activity to W20-17 cells that were treated with both Ang II and losartan. Collectively, these results suggest a novel mechanism of Ang II action in bone metabolism that is mediated by TGFβ and targets proliferation of osteoblast progenitors.

Raynaud's phenomenon: new aspects of pathogenesis and the role of nailfold videocapillaroscopy

Raynaud's phenomenon (RP) refers to paroxysmal pallor or cyanosis of the digits of the hands or feet and, infrequently, the tips of the nose or ears (acral parts) owing to cold-induced vasoconstriction of the digital arteries, precapillary arterioles, and cutaneous arteriovenous shunts.

Raynaud's phenomenon reflects an exaggeration of normal central and local vasomotor responses to cold or emotion. Raynaud's phenomenon has been classified as primary or secondary, depending on whether it occurs as an isolated condition or is associated mainly with a connective tissue disease.

Dysregulation of autonomic and sensitive nerve fibers, functional and structural vessel changes, and intravascular alterations can be observed in the pathogenesis of RP.

Nailfold videocapillaroscopy (NVC) is the best non-invasive and repetitive diagnostic technique for detecting morpho-functional changes in the microcirculation. Nailfold videocapillaroscopy is accepted in early diagnosis and monitoring of primary and secondary RP.

Modulation of angiotensin II signaling in the prevention of fibrosis

Over the last decade, it has become clear that the role of angiotensin II extends far beyond recognized renal and cardiovascular effects. The presence of an autologous renin-angiotensin system has been demonstrated in almost all tissues of the body. It is now known that angiotensin II acts both independently and in synergy with TGF-beta to induce fibrosis via the angiotensin type 1 receptor (AT1) in a multitude of tissues outside of the cardiovascular and renal systems, including pulmonary fibrosis, intra-abdominal fibrosis, and systemic sclerosis. Interestingly, recent studies have described a paradoxically regenerative effect of the angiotensin system via stimulation of the angiotensin type 2 receptor (AT2). Activation of AT2 has been shown to ameliorate fibrosis in animal models of skeletal muscle, gastrointestinal, and neurologic diseases. Clinical reports suggest a beneficial role for modulation of angiotensin II signaling in cutaneous scarring. This article reviews current knowledge on the role that angiotensin II plays in tissue fibrosis, as well as current and potential therapies targeting this system.

The role of botulinum toxin in vasospastic disorders of the hand

Raynaud phenomenon may be a primary disorder or associated with a variety of other autoimmune processes. Raynaud phenomenon produces digital vasospasm, which can lead to ischemia and ulceration. The treatment of Raynaud phenomenon has been difficult because multiple medical treatments have not provided uniform resolution of symptoms. Many patients have turned to surgery and sympathectomies for the treatment of unrelenting vasospasm. Botulinum toxin has been shown to be an effective alternative to surgery, with a single treatment being capable of resolving pain and healing ulcer. This article reviews the use of botulinum toxin for the treatment of Raynaud phenomenon.

MMP-12 deficiency attenuates angiotensin II-induced vascular injury, M2 macrophage accumulation, and skin and heart fibrosis

MMP-12, a macrophage-secreted elastase, is elevated in fibrotic diseases, including systemic sclerosis (SSc) and correlates with vasculopathy and fibrosis. The goal of this study was to investigate the role of MMP-12 in cardiac and cutaneous fibrosis induced by angiotensin II infusion. Ang II-induced heart and skin fibrosis was accompanied by a marked increase of vascular injury markers, including vWF, Thrombospondin-1 (TSP-1) and MMP-12, as well as increased number of PDGFRβ⁺ cells. Furthermore Ang II infusion led to an accumulation of macrophages (Mac3⁺) in the skin and in the perivascular and interstitial fibrotic regions of the heart. However, alternatively activated (Arg 1⁺) macrophages were mainly present in the Ang II infused mice and were localized to the perivascular heart regions and to the skin, but were not detected in the interstitial heart regions. Elevated expression of MMP-12 was primarily found in macrophages and endothelial cells (CD31⁺) cells, but MMP-12 was not expressed in the collagen producing cells. MMP-12 deficient mice (MMP12KO) showed markedly reduced expression of vWF, TSP1, and PDGFRβ around vessels and attenuation of dermal fibrosis, as well as the perivascular fibrosis in the heart. However, MMP-12 deficiency did not affect interstitial heart fibrosis, suggesting a heterogeneous nature of the fibrotic response in the heart. Furthermore, MMP-12 deficiency almost completely prevented accumulation of Arg 1⁺ cells, whereas the number of Mac3⁺ cells was partially reduced. Moreover production of profibrotic mediators such as PDGFBB, TGFβ1 and pSMAD2 in the skin and perivascular regions of the heart was also inhibited. Together, the results of this study show a close correlation between vascular injury markers, Arg 1⁺ macrophage accumulation and fibrosis and suggest an important role of MMP-12 in regulating these processes.

The association between vibration and vascular injury in rheumatic diseases: a review of the literature

Vascular manifestations can be seen early in the pathogenesis of inflammatory rheumatic diseases. Animal experiments, laboratory and clinical findings indicated that acute or long-term vibration exposure can induce vascular abnormalities. Recent years, in addition to Raynaud's phenomenon (RP), vibration as a risk factor for other rheumatic diseases has also received corresponding considered. This review is concentrated upon the role of vibration in the disease of systemic sclerosis (SSc). In this review, we are going to discuss the main mechanisms which are thought to be important in pathophysiology of vascular injury under the three broad headings of "vascular", "neural" and "intravascular". Aspects on the vibration and vascular inflammation are briefly discussed. And the epidemiological studies related to vibration studies in SSc and other rheumatic diseases are taken into account.

Animal models of systemic sclerosis: their utility and limitations

Without doubt, animal models have provided significant insights into our understanding of the rheumatological diseases; however, no model has accurately replicated all aspects of any autoimmune disease. Recent years have seen a plethora of knockouts and transgenics that have contributed to our knowledge of the initiating events of systemic sclerosis, an autoimmune disease. In this review, the focus is on models of systemic sclerosis and how they have progressed our understanding of fibrosis and vasculopathy, and whether they are relevant to the pathogenesis of systemic sclerosis.

Effect of captopril on collagen metabolisms in keloid fibroblast cells

BACKGROUND

Keloid is a proliferative disease of fibrous tissues. The mechanism and consistently effective treatments of keloid remained unknown. Although there was a report about treating keloid with topical captopril, the further investigation about captopril affecting keloid has not been performed so far.

OBJECTIVES

The aim of this study was to analyse the effect of captopril on collagen metabolisms in keloid fibroblast cells, and to provide information for the mechanism and therapy of keloid.

METHODS

To investigate the effects and relative mechanism of captopril on keloid fibroblast cells, we examined the changes of collagen metabolism, expression of angiotensin, transforming growth factor (TGF)-β1, platelet-derived growth factor (PDGF)-BB and heat shock protein 47 (HSP47), and cellular proliferation in keloid fibroblast cells.

RESULTS

We found that all collagen metabolisms, expression of TGF-β1, PDGF-BB and HSP47, and cellular proliferation decreased significantly with effective captopril concentrations in keloid fibroblast cells.

CONCLUSIONS

With a comprehensive analysis of test results, we proposed that captopril may decrease the expression of angiotensin, PDGF-BB, TGF-β1 and HSP47, and further inhibit proliferation and collagen synthesis of keloid fibroblast cells, which were the key in keloid formation.

Systemic sclerosis biomarkers discovered using mass-spectrometry-based proteomics: a systematic review

CONTEXT

Systemic sclerosis (SSc) is an autoimmune disease with incompletely known physiopathology. There is a great challenge to predict its course and therapeutic response using biomarkers.

OBJECTIVE

To critically review proteomic biomarkers discovered from biological specimens from systemic sclerosis patients using mass spectrometry technologies.

METHODS

Medline and Embase databases were searched in February 2014.

RESULTS

Out of the 199 records retrieved, a total of 20 records were included, identifying 116 candidate proteomic biomarkers.

CONCLUSION

Research in SSc proteomic biomarkers should focus on biomarker validation, as there are valuable mass-spectrometry proteomics studies in the literature.