Raised concentration of soluble form of vascular endothelial cadherin and IL-23 in sera of patients with Behçet’s disease

Plasma Proteomic Analysis Reveals the Potential Role of Lectin and Alternative Complement Pathways in IgA Vasculitis Pathogenesis

BACKGROUND

IgA vasculitis (IgAV) is the most common form of childhood vasculitis. A better understanding of its pathophysiology is required to identify new potential biomarkers and treatment targets.

OBJECTIVE

to assess the underlying molecular mechanisms in the pathogenesis of IgAV using an untargeted proteomics approach.

METHODS

Thirty-seven IgAV patients and five healthy controls were enrolled. Plasma samples were collected on the day of diagnosis before any treatment was initiated. We used nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS) to investigate the alterations in plasma proteomic profiles. For the bioinformatics analyses, databases including Uniprot, PANTHER, KEGG, Reactome, Cytoscape, and IntAct were used.

RESULTS

Among the 418 proteins identified in the nLC-MS/MS analysis, 20 had significantly different expressions in IgAV patients. Among them, 15 were upregulated and 5 were downregulated. According to the KEGG pathway and function classification analysis, complement and coagulation cascades were the most enriched pathways. GO analyses showed that the differentially expressed proteins were mainly involved in defense/immunity proteins and the metabolite interconversion enzyme family. We also investigated molecular interactions in the identified 20 proteins of IgAV patients. We extracted 493 interactions from the IntAct database for the 20 proteins and used Cytoscape for the network analyses.

CONCLUSION

Our results clearly suggest the role of the lectin and alternate complement pathways in IgAV. The proteins defined in the pathways of cell adhesion may serve as biomarkers. Further functional studies may lead the way to better understanding of the disease and new therapeutic options for IgAV treatment.

Finding the Needle in the Haystack: Serological and Urinary Biomarkers in Behçet's Disease: A Systematic Review

Urinary and serological markers play an essential role in the diagnostic process of autoimmune diseases. However, to date, specific and reliable biomarkers for diagnosing Behçet's disease (BD) are still lacking, negatively affecting the management of these patients. To analyze the currently available literature on serological and urinary BD biomarkers investigated in the last 25 years, we performed a systematic literature review using the Population, Intervention, Comparison, and Outcomes (PICO) strategy. One hundred eleven studies met the eligibility criteria (6301 BD patients, 5163 controls). Most of them were retrospective, while five (5%) were prospective. One hundred ten studies (99%) investigated serological biomarkers and only two (2%) focused on urinary biomarkers. One hundred three studies (93%) explored the diagnostic potential of the biomolecules, whereas sixty-two (56%) tested their effect on disease activity monitoring. Most articles reported an increase in inflammatory markers and pro-oxidant molecules, with a decrease in antioxidants. Promising results have been shown by the omics sciences, offering a more holistic approach. Despite the vast number of investigated markers, existing evidence indicates a persistent gap in BD diagnostic/prognostic indices. While new steps have been taken in the direction of pathogenesis and disease monitoring, international efforts for the search of a diagnostic marker for BD are still needed.

Long-Term Outcome of Ustekinumab Therapy for Behçet's Disease

OBJECTIVE

Oral ulcers, the hallmark lesion of Behçet's disease (BD), can be disabling and resistant to conventional treatment, and there is a need for safe and effective treatment. We undertook this study to investigate the long-term safety and efficacy of ustekinumab therapy for BD-related oral ulcers that are resistant to colchicine.

METHODS

This multicenter, prospective, open-label study included 30 patients who fulfilled the criteria of the International Study Group for BD and who were diagnosed as having active oral ulcers resistant to colchicine. Patients were treated subcutaneously with ustekinumab 90 mg at inclusion, at week 4, and then once every 12 weeks. Each patient was assessed longitudinally for the presence and number of oral ulcers, and median numbers of oral ulcers (with interquartile range [IQR]) were calculated. The primary efficacy end point was the proportion of patients at week 12 who experienced complete response, defined as having no oral ulcers.

RESULTS

The median number of oral ulcers per patient during ustekinumab therapy was significantly lower at week 12 compared to baseline (0 [IQR 0-1] versus 2 [IQR 2-3]; P < 0.0001). Complete response was achieved in 60.0% and 88.9% of patients at weeks 12 and 24, respectively. The median Behçet's Syndrome Activity Score (in which higher scores indicate more active disease) was significantly lower at weeks 12 and 24 (17.5 [IQR 10-42.5] and 10 [IQR 8-11], respectively) versus baseline (70 [IQR 50-70]; P < 0.0001). After a median follow-up of 12 months (IQR 6-16 months), 26 patients (86.7%) were still receiving ustekinumab treatment. Reasons for ustekinumab discontinuation included BD flare (n = 3) and side effects (n = 1). Seven patients (23.3%) experienced adverse events, including headaches (n = 4) and asthenia (n = 2), with no serious side effects.

CONCLUSION

Ustekinumab seems to be effective in treating BD-related oral ulcers that are resistant to treatment with colchicine.

Emerging Roles of Redox-Mediated Angiogenesis and Oxidative Stress in Dermatoses

Angiogenesis is the process of new vessel formation, which sprouts from preexisting vessels. This process is highly complex and primarily involves several key steps, including stimulation of endothelial cells by growth factors, degradation of the extracellular matrix by proteolytic enzymes, migration and proliferation of endothelial cells, and capillary tube formation. Currently, it is considered that multiple cytokines play a vital role in this process, which consist of proangiogenic factors (e.g., vascular endothelial growth factor, fibroblast growth factors, and angiopoietins) and antiangiogenic factors (e.g., endostatin, thrombospondin, and angiostatin). Angiogenesis is essential for most physiological events, such as body growth and development, tissue repair, and wound healing. However, uncontrolled neovascularization may contribute to angiogenic disorders. In physiological conditions, the above promoters and inhibitors function in a coordinated way to induce and sustain angiogenesis within a limited period of time. Conversely, the imbalance between proangiogenic and antiangiogenic factors could cause pathological angiogenesis and trigger several diseases. With insights into the molecular mechanisms of angiogenesis, increasing reports have shown that a close relationship exists between angiogenesis and oxidative stress (OS) in both physiological and pathological conditions. OS, an imbalance between prooxidant and antioxidant systems, is a cause and consequence of many vascular complains and serves as one of the biomarkers for these diseases. Furthermore, emerging evidence supports that OS and angiogenesis play vital roles in many dermatoses, such as psoriasis, atopic dermatitis, and skin tumor. This review summarizes recent findings on the role of OS as a trigger of angiogenesis in skin disorders, highlights newly identified mechanisms, and introduces the antiangiogenic and antioxidant therapeutic strategies.

Behçet's disease: An immunogenetic perspective

Behçet's disease (BD) is a chronic and rare multisystemic disorder defined by autoimmunity and inflammatory characteristics, manifested by ocular lesions, recurrent genital and oral ulcers, skin symptoms and arthritis as well as neurological, intestinal, and vascular involvement. Despite the unknown cause of BD, there is some strong documentation for immunological, genetic, environmental, and infectious factors playing a role in the pathogenesis of BD. While the nature of the genetic variants remains unidentified, many genetic risk factors are considered to contribute to BD susceptibility. Along with human leukocyte antigen gene encoding B*51 (HLA-B*51) and areas including the major histocompatibility complex class I, genome-wide association studies have recognized numerous other BD susceptibility genes including those encoding interleukin (IL)-10, IL-12 receptor β 2 (IL-12RB2), IL-23 receptor (IL-23R), C-C chemokine receptor 1 gene, signal transducer and activator of transcription 4 (STAT4), endoplasmic reticulum aminopeptidase (ERAP1), and genes encoding killer cell lectin-like receptor family members (KLRC4-KLRK1). It is believed that BD could be considered as a disorder lying in between autoimmune and autoinflammatory syndromes. The positive responses to classical immunosuppressive agents like azathioprine and cyclosporine and involvement of autoantigens in the initiation of the disorder are the main BD features that reflect the autoimmune nature of the disorder. In this review, we address recent findings on the role of common cytokines, antibodies and immunogenetic factors in BD.

Unmet Needs in the Pathogenesis and Treatment of Vasculitides

Despite the progress in the last years on the field of vasculitides, there are several unmet needs regarding classification, disease activity assessment, predictors of flares and complications, and type of treatment for the different forms. The 1990 American College of Rheumatology (ACR) classification criteria currently used to define giant cell arteritis and Takayasu arteritis were designed to discriminate between different types of vasculitides but not to differentiate vasculitis from other disorders. Recently, efforts have been made to overcome the shortcomings of the ACR criteria. The lack of an accepted definition of disease activity in large-vessel vasculitides presents a major challenge in creating useful and valid outcome tools for the assessment of disease course. Identification of predictors of flares can aid in optimizing therapeutic strategies, minimizing disease flares, and reducing treatment-related side effects. It is furthermore important to recognize and characterize the risk factor that might predict the manifestations associated with poor outcome and prognosis. Two RCTs have evidenced the efficacy of tocilizumab in addition to glucocorticoids (GCs) in the treatment of giant cell arteritis (GCA). However, the role of tocilizumab or other biological agents without GCs needs to be investigated. Recent observational studies have suggested that rituximab is also effective in patients with eosinophilic granulomatosis with polyangiitis and in antineutrophil cytoplasmic antibodies (ANCA)-negative patients with granulomatosis with polyangiitis and microscopic polyangiitis. Rituximab or anti-TNF alfa may represent a possible alternative therapy in case of refractory or difficult to treat polyarteritis nodosa (PAN) patients. The new International Criteria for Behçet's Disease have shown a better sensitivity and a better accuracy compared to the older International Study Group on Behçet's Disease criteria. The EULAR recommendations for the management of Behçet's disease (BD) have been recently updated. However, the treatment of refractory disease is still a real challenge.

Investigational drugs in systemic vasculitis

INTRODUCTION

Treatment of systemic vasculitis is based on glucocorticoids (GC) in association with immunosuppressive therapy. There are still unmet needs, including earlier onset of response, more targeted therapies, reduction of relapse-risk and decrease of long-term GC and classic immunosuppressants toxicities. Areas covered: In this review, we discuss investigational drugs in early phase clinical trials for induction of remission in vasculitis. We focus on ANCA-associated vasculitis, Behçet's disease, giant cell arteritis, Takayasu arteritis, and cryoglobulinemic vasculitis. We performed a comprehensive review of articles published on pubmed and a review of clinical trials registered online ( https://clinicaltrials.gov ) for each vasculitis. Expert opinion: Recent progress in the pathogenesis identifies new therapeutic targets. Some of these therapies are promising in GC sparing effects, in reducing relapse rate, and for their safety profile. These results need to be confirmed in large-scale phase III studies.

Increased serum soluble vascular endothelial cadherin levels in patients with chronic spontaneous urticaria

BACKGROUND

Chronic spontaneous urticaria (CSU) is a common skin disease characterized by recurrent itchy wheals with or without angioedema that lasts longer than 6 weeks. Vascular endothelial (VE)-cadherin is an endothelial cell-specific adhesion molecule that plays critical roles in angiogenesis and endothelial permeability.

OBJECTIVE

To investigate serum levels of soluble VE (sVE)-cadherin in patients with CSU.

METHODS

Serum levels of sVE-cadherin in patients with CSU, patients with atopic dermatitis, and healthy controls were determined by enzyme-linked immunosorbent assay. In addition, changes in sVE-cadherin serum levels were compared in patients with CSU before and after H₁ antihistamine treatment. Furthermore, the effects of histamine on sVE-cadherin release by HMEC-1 cells were determined by enzyme-linked immunosorbent assay. The inhibition effects of H₁ antihistamine and H₂ antihistamine on sVE-cadherin release, VE-cadherin phosphorylation, and VE-cadherin disruption were evaluated in histamine-treated HMEC-1 cells by western blot and immunofluorescence.

RESULTS

Serum levels of sVE-cadherin in patients with CSU were significantly higher than those in patients with atopic dermatitis and healthy controls. Serum sVE-cadherin levels in patients with CSU were correlated with the severity of CSU according to Urticaria Activity Scores. Furthermore, serum sVE-cadherin levels in patients with CSU at pretreatment decreased after H₁ antihistamine treatment. In addition, histamine markedly induced sVE-cadherin release in HMEC-1 cells. Moreover, H₁ antihistamine, but not H₂ antihistamine, significantly inhibited sVE-cadherin release in histamine-treated HMEC-1 cells. Western blot data showed that histamine induced phosphorylation of VE-cadherin in HMEC-1 cells, which was blocked by H₁ antihistamine.

CONCLUSION

The present data showed serum levels of sVE-cadherin are increased in patients with CSU. Histamine-induced sVE-cadherin release from endothelial cells could play a role in the pathogenesis of CSU.

Soluble Vascular Endothelial Cadherin as a New Biomarker of Irradiation in Highly Irradiated Baboons with Bone Marrow Protection

Vascular endothelial cadherin is the main component of adherens junctions enabling cohesion of the endothelial monolayer in vessels. The extracellular part of vascular endothelial cadherin (VE-cadherin) can be cleaved, releasing soluble fragments in blood (sVE-cadherin). In some diseases with endothelial dysfunction, a correlation between increased blood sVE-cadherin levels and disease state has been proposed. Irradiation is known to induce endothelial damage, but new serum biomarkers are needed to evaluate endothelial damage after irradiation. Here, the authors investigated whether sVE-cadherin may be an interesting biomarker of irradiation in highly irradiated baboons with bone marrow protection. sVE-cadherin was detected in the plasma of young as well as old baboons. Plasma sVE-cadherin levels significantly decrease a few days after irradiation but recover in the late time after irradiation. Kinetic analysis of plasma sVE-cadherin levels suggests a correlation with white blood cell counts in both the acute phase of irradiation and during hematopoietic recovery, suggesting that plasma sVE-cadherin levels may be partly linked to the disappearance and recovery of white blood cells. Interestingly, after hematopoietic recovery was completed, sVE-cadherin levels were found to exceed control values, suggesting that plasma sVE-cadherin may represent a new biomarker of endothelial damage or neovascularization in the late time after irradiation.

Soluble vascular endothelial-cadherin and auto-antibodies to human vascular endothelial-cadherin in human diseases: Two new biomarkers of endothelial dysfunction

Vascular endothelial-cadherin is the most important transmembrane component of endothelial adherens junctions, exclusively expressed by endothelial cells in all types of vessels. Targeting either the extracellular domain or the cytoplasmic tail deleteriously affects the junctional strength and leads to vascular permeability. Recently, cytokine-induced phosphorylation of the vascular endothelial-cadherin cytoplasmic domain was reported to trigger cleavage of its extracellular domain, producing the soluble form of the protein – soluble vascular endothelial-cadherin. Hence, the presence of soluble vascular endothelial-cadherin or auto-antibodies to human vascular endothelial-cadherin in human serum could signalize the presence of vascular abnormalities. This systematic review covers many human studies reporting increased levels of soluble vascular endothelial-cadherin, as well as auto-antibodies to human vascular endothelial-cadherin, which could be promising biomarkers of endothelial dysfunction in a large panel of diseases.

Soluble vascular endothelial-cadherin levels in patients with sepsis treated with direct hemoperfusion with a polymyxin B-immobilized fiber column

Capillary permeability is a tightly regulated feature of microcirculation in all organ beds; however, in sepsis this feature is fundamentally altered. Several molecules are investigated as associated factors with capillary permeability and vascular endothelial (VE)-cadherin internalization by vascular endothelial growth factor (VEGF)-induced signaling through VEGF receptors leads to increased vascular endothelial cell detachment and trans-endothelial permeability. We investigated serum soluble VE-cadherin levels in septic patients. An enzyme-linked immunoassay was used to measure serum soluble VE-cadherin levels in 47 septic patients treated by direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX). The serum soluble VE-cadherin level of septic patients before PMX-DHP was 3424.1 ± 2033.0 ng/mL, which was significantly lower than that of the controls (5862.0 ± 1521.2 ng/mL; P < 0.0001). The time course of serum soluble VE-cadherin levels remained unchanged during PMX-DHP therapy. There was no significant difference in serum soluble VE-cadherin levels before PMX-DHP therapy between survivors and non-survivors, and there was no significant difference in those levels between the groups at any time after the initiation of PMX-DHP therapy. There was no correlation between soluble VE-cadherin levels and clinical data, except white blood cell count (r = -0.277, P = 0.0009). There was no correlation between soluble VE-cadherin levels and the levels of angiopoietin 1 and 2. In summary, the relationship between VE-cadherin and capillary permeability in sepsis could not be demonstrated. Soluble VE-cadherins are not reflected in the balance between intercellular junction plasticity and integrity, but VE-cadherin stabilization by its phosphorylation or internalization may be associated with capillary permeability.

Serum angiostatin levels in patients with Behçet's disease: does angiogenesis play a role in the pathogenesis of Behçet's disease?

Angiogenesis plays an important role in the pathogenesis of inflammatory diseases, but the possible role of angiogenesis in Behçet's disease (BD) has not yet been studied. The aim of this study was to determine angiostatin levels in patients with BD and the role of angiogenesis in the pathogenesis of the disease. Thirty-seven patients with BD (mean age: 28·6±5·4 years, mean disease duration: 9·3±3·7 years) and 18 healthy controls were enrolled to the study. Twenty-four patients were in active and 13 patients were in inactive stage of the disease. The mean serum angiostatin level of patients with BD was 113·9±53·2 and 60·7±20·1 ng/ml in healthy controls. The mean serum angiostatin level was 142·7±43·1 ng/ml in active and 86·9±15·5 ng/ml in inactive patients with BD. Serum angiostatin levels were significantly high in patients with BD compared with healthy controls (P<0·001) and it was significantly high in active patients compared with inactive patients with BD (P<0·001). In inactive patients with BD, serum angiostatin concentrations were found to be higher compared with healthy controls (P<0·01). In active BD patients, the mean serum angiostatin level was correlated with the deep vein thrombosis (r = 0·482, P = 0·05), uveitis (r = 0·582, P = 0·01), and arthritis (r = 0·492, P = 0·05). According to these results; elevated serum angiostatin levels in patients with BD suggest the possible role of angiogenesis in the pathogenesis of the disease and its high levels in inactive Behçet's patients is related with the continuous activation of the disease even in the subclinical period.

ADAM12 is expressed in the tumour vasculature and mediates ectodomain shedding of several membrane-anchored endothelial proteins

ADAM (a disintegrin and metalloproteinase) 12 is a metalloprotease implicated in cancer progression. ADAM12 can activate membrane-anchored proteins, such as sonic hedgehog, Delta-like 1 and certain epidermal growth factor receptor ligands, through a process called ectodomain shedding. We screened several membrane-anchored proteins to further dissect the substrate profile of ADAM12-mediated ectodomain shedding, and found shedding of five previously unreported substrates [Kitl1, VE-cadherin (vascular endothelial cadherin), Flk-1 (fetal liver kinase 1), Tie-2, and VCAM-1 (vascular cell adhesion molecule 1)], of which the latter four are specifically expressed by endothelial cells. We also observed that ADAM12 expression was increased in the tumour vasculature of infiltrating ductal carcinoma of the human breast as compared with little to no expression in normal breast tissue vasculature, suggesting a role for ADAM12 in tumour vessels. These results prompted us to further evaluate ADAM12-mediated shedding of two endothelial cell proteins, VE-cadherin and Tie-2. Endogenous ADAM12 expression was very low in cultured endothelial cells, but was significantly increased by cytokine stimulation. In parallel, the shed form of VE-cadherin was elevated in such cytokine-stimulated endothelial cells, and ADAM12 siRNA (small interfering RNA) knockdown reduced cytokine-induced shedding of VE-cadherin. In conclusion, the results of the present study demonstrate a role for ADAM12 in ectodomain shedding of several membrane-anchored endothelial proteins. We speculate that this process may have importance in tumour neovascularization or/and tumour cell extravasation.

Therapeutic potency of Poly I:C in HSV-induced inflammation through up-regulation of IL-15 receptor alpha

Interleukin-15 receptor alpha (IL-15Rα) forms stable complex with IL-15 on the cell surface of activated monocytes and mediates the proliferation of memory CD8+ T cells. Recent studies informed that polyinosinic:polycytidylic acid (Poly I:C) is an immunostimulant which boosts the generation of memory T cells through induction of IL-15Rα. The aim of this study is to evaluate the relevance of IL-15Rα in Herpes simplex virus (HSV)-induced Behçet's disease (BD) mouse model and BD patients. The frequencies of IL-15Rα expression in PBMCs of BD patients and BD-like symptomatic mice were analyzed by flow cytometry. In addition, Poly I:C supplementation could reduce inflammation through the up-regulation of memory T cells and IL-15Rα+ cells accompany with down-regulation of pro-inflammatory cytokine, IL-17A in BD mice. In BD patients, the frequencies of IL-15Rα expression in PBMCs were also significantly different between the inactive and active disease states. These results suggest that IL-15Rα is a relevant factor in BD.