Critical role of neutrophil extracellular traps (NETs) in patients with Behcet's disease

T-2 toxin triggers immunotoxic effects in goats by inducing ferroptosis and neutrophil extracellular traps

T-2 toxin, a prevalent mycotoxin, represents a notable global public health risk. Neutrophil extracellular traps (NETs) and ferroptosis are involved in a variety of pathophysiological processes and are implicated in goat immunity. However, the impact of T-2 toxin on NETs release, ferroptosis, and their interplay have not been previously documented. In this study, neutrophils were stimulated with T-2 toxin for 4 h. The structure and mechanism of NETs were analyzed using immunofluorescence and Pico Green staining. The expressions of glutathione peroxidase 4 (GPX4) and ferritin (FT) was quantified by qRT-PCR and western blotting. The levels of ROS and lipid ROS were assessed using DCFH-DA and C11 BODIPY 581/591 probes, and cellular mitochondria Fe2+ were detected by using Mito-FerroGreen probe. Inhibitors were utilized to explore the interaction between these two processes. The results confirmed that the T-2 toxin stimulated the NETs production, characterized by a structure co-modified by citrullinated histones (citH3), neutrophil elastase (NE) and DNA. Notably, significant inhibition of NETs production by T-2 toxin was observed with the NOX inhibitor DPI (P < 0.001), the ERK inhibitor U0126 (P < 0.001), the TLR2 inhibitor C29 (P < 0.001), and the TLR4 inhibitor TLR4-IN-C34 (P < 0.001). T-2 toxin triggered ferroptosis in neutrophils by suppressing GPX4 and FT expression, elevating ROS and lipid ROS, and augmenting the concentration of mitochondrial Fe2+. The ferroptosis inhibitor Fer-1 could rescue this induction; however, Fer-1 was unable to inhibit NETs which is induced by T-2 toxin. Conversely, T-2 toxin effectively triggered the downregulation of GPX4, which was counteracted by DPI, U0126, C29, and C34. This research elucidates the immunotoxic mechanisms of T-2 toxin in goat neutrophils and offers a novel perspective on preventing and treating T-2 toxin.

Evaluation of inflammatory-thrombosis panel as a diagnostic tool for vascular Behçet's disease

OBJECTIVES

Vascular Behçet's disease (VBD) is prevalent in 40% of BD, but lacks laboratory biomarker for timely diagnosis. We aimed to establish a diagnostic panel for discerning VBD and non-VBD patients and identify hemostatic-thrombotic markers most related to VBD pathogenesis using machine learning algorithm.

OBJECTIVES

A total of 338 BD patients comprising 123 VBD and 215 non-VBD were enrolled. Twenty-six clinical and laboratory features selected from LassoCV were included in multiple classifier to choose the optimal model for VBD differentiation. The Shapley Additive exPlanations (SHAP) was employed to interpret the contribution of model features for VBD prediction. Logistic regression analysis and nomogram were conducted to screen risk factors of VBD.

RESULTS

Inflammatory (neutrophils%, NK cells, IL-6), hematological (hemoglobin, hemoglobin distribution width (HDW)) and thrombosis (activated partial thromboplastin clotting time (APTT), D-dimer) parameters were elevated in VBD. Then we chose top contributors from XGBoost model and performed ten-fold cross validation, the diagnostic accuracy of which exceeded 0.90. Utilizing SHAP method, we identified higher incidence of arterial thrombosis or aneurysm and deep vein thrombosis, upregulated NK cell count, HDW, APTT and D-dimer, downregulated reticulocyte%, B cell count, red blood cell distribution width, cellular hemoglobin (CH) and TNF-α would ultimately generate the phenotype of VBD. Severity, hemoglobin, mean corpuscular hemoglobin, CH, HDW, APTT and D-dimer were found as potential risk factors for vascular outcomes among BD.

RESULTS

Our study developed a well-performed model leveraging clinical and laboratory parameters for differentiating VBD. Inflammatory and thrombotic risk factors are potential contributors to VBD. Key Points • Inflammatory (neutrophils%, NK cells, IL-6), hematological (HGB, HDW) and thrombosis (APTT, D-dimer) parameters were elevated in VBD. • We firstly developed an inflammatory-thrombosis model as a diagnostic tool for VBD. • HGB, MCH, CH, HDW, APTT and D-dimer are potential risk factors for VBD.

Neutrophil extracellular traps potentiate effector T cells via endothelial senescence in uveitis

Autoimmune uveitis (AU) is a sight-threatening ocular autoimmune disorder that often manifests as retinal vasculitis. Increased neutrophil infiltration around retinal vessels has been reported during the progression of AU, while how they function is not fully recognized. Neutrophil extracellular traps (NETs), produced by activated neutrophils, have been suggested to be detrimental in autoimmune diseases. Here, we found that NETs were elevated in patients with active AU, and this was verified in an experimental AU (EAU) mouse model. Depletion of neutrophils or degradation of NETs with deoxyribonuclease-I (DNase I) could decrease CD4+ effector T cell (Teff) infiltration in retina and spleen to alleviate EAU. Moreover, we found that the expression of adhesion molecules, selectin, and antigen-presenting molecules was elevated in EAU retina and in retinal microvascular endothelial cells (RMECs) cocultured with NETs. The stimulated RMECs further facilitated CD4+ T cell adhesion, activation, and differentiation into Teffs. Mechanistically, NETs trigger RMEC activation by hastening cell senescence through the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway. Slowing down senescence or inhibiting the cGAS/STING pathway in RMECs reduces the activation and differentiation of CD4+ T cells. These results suggest a deleterious role of NETs in AU. Targeting NETs would offer an effective therapeutic method.

Neutrophil extracellular DNA traps activate the TLR9 signaling pathway of pancreatic ductal epithelial cells in patients with type 2 autoimmune pancreatitis

The presence of neutrophil infiltration around the pancreatic ducts has been found to be associated with type 2 autoimmune pancreatitis (AIP). However, the functional role and clinical significance of neutrophil migration in the progression of pancreatitis is not fully understood. Here, we found that neutrophil extracellular traps (NETs) are abundant around the pancreatic duct in patients with type 2 AIP. We also observed an increased expression of toll-like receptor 9 (TLR9) in pancreatic ductal epithelial cells (HPDEC) in type 2 AIP patients compared to other pancreatic diseases. TLR9 acts as the DNA component of NETs (NET-DNA) receptor in HPDEC, which senses extracellular DNA and subsequently activates the NF-κB pathway to promote neutrophil recruitment and induce NET formation. In addition, our results indicated that the hydroxychloroquine (HCQ), acting as a TLR9 antagonist, could effectively inhibit the activation of inflammatory pathways, reduce neutrophil migration and block the positive feedback loop. The intervention positions HCQ acts as a potential target drug for the clinical treatment of type 2 AIP.

Juvenile Behçet syndrome: a contemporary view and differential diagnosis in pediatric practice

PURPOSE OF REVIEW

This review aims to provide a comprehensive and contemporary overview of juvenile Behçet syndrome (jBS), highlighting its clinical manifestations, diagnostic challenges, and treatment strategies.

RECENT FINDINGS

Behçet syndrome, with its intricate etiopathogenesis and diverse clinical phenotypes, is more aptly classified as a syndrome than a single disease. Its heterogeneous nature requires a broad diagnostic approach and sophisticated differential diagnosis capabilities. The relatively rare occurrence of Behçet syndrome, combined with incomplete clinical presentations and overlapping differential diagnoses, presents significant diagnostic challenges, particularly in pediatric cases. Nevertheless, substantial progress has been made in treatment, especially in managing inflammatory components and preventing complications. Juvenile patients, given their developmental stage, require distinct therapeutic strategies compared to adults, with careful consideration of treatment side effects on growth and psychosocial development.

SUMMARY

To ensure early identification of jBS, it is imperative to refine and develop diagnostic criteria specifically tailored to pediatric populations. With a deeper understanding of the disease mechanisms, treatment protocols should be designed to address the developmental, psychosocial, and individual needs of patients, aiming to minimize long-term side effects. Additionally, comprehensive studies considering age, sex, and ethnic differences are necessary to fill gaps in the literature and resolve existing inconsistencies.

The role of neutrophil extracellular traps in inflammatory rheumatic diseases

PURPOSE OF REVIEW

Dysregulation in neutrophil extracellular trap (NET) formation and degradation has been reported in several inflammatory rheumatic diseases. This review summarizes the recent advances in the understanding the role of NETs in the context of inflammatory rheumatic diseases.

RECENT FINDINGS

NET formation is enhanced in peripheral blood of patients with large vessel vasculitis and polymyalgia rheumatica. NETs are detected in affected organs in autoimmune conditions, and they might play pathological roles in tissues. Several understudied medications and supplements suppress NET formation and ameliorate animal models of inflammatory rheumatic diseases. NETs and anti-NET antibodies have potential utility as disease biomarkers.

SUMMARY

Growing evidence has suggested the contribution of NET dysregulation to the pathogenesis of several inflammatory rheumatic diseases. Further research is warranted in regard to clinical impact of modulating aberrant NET formation and clearance in inflammatory rheumatic diseases.

Prognostic factors associated with acute retinal necrosis treated non-surgically

OBJECTIVES

To analyse the prognostic factors for visual acuity in acute retinal necrosis (ARN) patients treated non-surgically.

METHODS

The clinical data of ARN patients who visited our hospital from January 2010 to January 2023 were retrospectively analysed.

RESULTS

Twenty-four patients (29 eyes) were included. Aqueous humour samples were collected from 20 out of 29 eyes, and PCR confirmed that 85% (17/20) of the eyes had VZV infection, 10% (2/20) had CMV infection, and 5% (1/20) had HSV infection. All patients were treated with intravenous antiviral agents. Intravitreal ganciclovir and oral corticosteroids were given according to the patients' wishes. A comparison of visual acuity at the time of first identification of inactive ARN with that at the first visit revealed that 16 (55.2%) eyes improved and 13 (44.8%) did not improve. Logistic regression analysis revealed that risk factors for failure to improve vision after treatment included retinal detachment (odds ratio [OR],33.75; 95% CI, 3.245-351.067; P = 0.003), necrotising retinitis involving the posterior pole (odds ratio [OR],8.167; 95% CI, 1.297-51.403, P = 0.025), and arteritis involving the large retinal arteries (odds ratio [OR],9.167; 95% CI, 1.493-56.297; P = 0.017). The VZV viral load in the aqueous humour at initial presentation was significantly associated with visual prognosis (r = 0.688, P = 0.013), retinal detachment (τ = 0.597, P = 0.021) and the extent of retinal necrosis (τ = 0.57, P = 0.027). The neutrophil to lymphocyte ratio (NLR) of VZV-infected patients at first presentation was significantly correlated with the prognosis of visual acuity (r = 0.616, P = 0.033) and retinal detachment (τ = 0.728, P = 0.004).

CONCLUSIONS

High NLR and viral DNA copy number in the aqueous humour at the initial presentation, as well as subsequent retinal detachment, necrotising retinitis involving the posterior pole, and arteritis involving the large retinal arteries were risk factors for poor visual prognosis in VZV-infected ARN patients.

TNF inhibitors target a mevalonate metabolite/TRPM2/calcium signaling axis in neutrophils to dampen vasculitis in Behçet's disease

TNF inhibitors have been used to treat autoimmune and autoinflammatory diseases. Here we report an unexpected mechanism underlying the therapeutic effects of TNF inhibitors in Behçet's disease (BD), an autoimmune inflammatory disorder. Using serum metabolomics and peripheral immunocyte transcriptomics, we find that polymorphonuclear neutrophil (PMN) from patients with BD (BD-PMN) has dysregulated mevalonate pathway and subsequently increased farnesyl pyrophosphate (FPP) levels. Mechanistically, FPP induces TRPM2-calcium signaling for neutrophil extracellular trap (NET) and proinflammatory cytokine productions, leading to vascular endothelial inflammation and damage. TNF, but not IL-1β, IL-6, IL-18, or IFN-γ, upregulates TRPM2 expression on BD-PMN, while TNF inhibitors have opposite effects. Results from mice with PMN-specific FPP synthetase or TRPM2 deficiency show reduced experimental vasculitis. Meanwhile, analyses of public datasets correlate increased TRPM2 expressions with the clinical benefits of TNF inhibitors. Our results thus implicate FPP-TRPM2-TNF/NETs feedback loops for inflammation aggravation, and novel insights for TNF inhibitor therapies on BD.

Dietary Antioxidants and Natural Compounds in Preventing Thrombosis and Cardiovascular Disease

Reactive oxygen species (ROS) contribute to endothelial dysfunction, platelet activation, and coagulation abnormalities, promoting thrombus formation. Given the growing interest in non-pharmacological approaches to modulate oxidative stress, we examine the potential of various dietary interventions and antioxidant supplementation in reducing oxidative damage and preventing thrombotic events. Key dietary patterns, such as the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and ketogenic diets, as well as antioxidant-rich supplements like curcumin, selenium, and polyphenols, demonstrate promising effects in improving oxidative stress markers, lipid profiles, and inflammatory responses. This review highlights recent advances in the field, drawing from in vitro, ex vivo, and clinical studies, and underscores the importance of integrating dietary strategies into preventive and therapeutic approaches for managing thrombosis and cardiovascular health. Further research is needed to better understand long-term effects and personalize these interventions for optimizing patient outcomes.

The Impact of Disease Severity on the Serum Levels of Significant Neutrophil Extracellular Trap (NET) Proteins in Patients with Psoriasis

Psoriasis is an inflammatory skin disease with various symptoms of differing severities and with the reported prominent involvement of neutrophil extracellular traps (NETs). The excitation of neutrophils, e.g., by interleukin 8 (IL-8) or lipopolysaccharide (LPS), leads to the citrullination of histones and the release of protein-DNA complexes into the extracellular space, where they are digested by DNases. Our aim was to explore data on the levels of protein-complexed DNAs neutrophil elastase-DNA (NE-DNA) and myeloperoxidase-DNA (MPO-DNA), citrullinated histones (citH2, citH3, citH4), and NET-degrading enzyme DNase I in the serum of psoriatic patients with varying severities of clinical symptoms assessed with the Psoriasis Area Severity Index (PASI), Body Surface Area (BSA), and Dermatology Life Quality Index (DLQI) scores. The levels of factors were detected in 52 patients with psoriasis and 22 healthy volunteers by the enzyme-linked immunosorbent assay (ELISA). The results showed the elevated levels of NE-DNA, MPO-DNA, citH3, and DNase I in the patients with psoriasis compared to healthy volunteers (p < 0.05). Additionally, changes were noticed in the levels of NE-DNA, citH3, and DNase I, depending on the severity of symptoms (p < 0.05). In mild psoriasis (PASI < 10, BSA < 10, DLQI < 10), the suppressing activity of the enzyme caused the impaired ability to remove the physiological level of NETs, whereas in moderate to severe psoriasis (PASI ≥ 10, BSA ≥ 10, DLQI ≥ 10), the enhanced activity of DNase I failed to remove NETs due to the observed overexpression. It may, thus, be concluded that the mechanism of action of NETs, which play an undeniable role in psoriatic diseases, seem to follow two different paths depending on the severity of disease, which may be crucial in selecting potential anti-NET treatment methods.

Genetic and epigenetic dysregulation of innate immune mechanisms in autoinflammatory diseases

Dysregulation and hyperactivation of innate immune responses can lead to the onset of systemic autoinflammatory diseases. Monogenic autoinflammatory diseases are caused by inborn genetic errors and based on molecular mechanisms at play, can be divided into inflammasomopathies, interferonopathies, relopathies, protein misfolding, and endogenous antagonist deficiencies. On the other hand, more common autoinflammatory diseases are multifactorial, with both genetic and non-genetic factors playing an important role. During the last decade, long-term memory characteristics of innate immune responses have been described (also called trained immunity) that in physiological conditions provide enhanced host protection from pathogenic re-infection. However, if dysregulated, induction of trained immunity can become maladaptive, perpetuating chronic inflammatory activation. Here, we describe the mechanisms of genetic and epigenetic dysregulation of the innate immune system and maladaptive trained immunity that leads to the onset and perpetuation of the most common and recently described systemic autoinflammatory diseases.

The role of neutrophils in autoimmune diseases

Historically, neutrophils have been primarily regarded as short-lived immune cells that act as initial responders to antibacterial immunity by swiftly neutralizing pathogens and facilitating the activation of adaptive immunity. However, recent evidence indicates that their roles are considerably more complex than previously recognized. Neutrophils comprise distinct subpopulations and can interact with various immune cells, release granular proteins, and form neutrophil extracellular traps. These functions are increasingly recognized as contributing factors to tissue damage in autoimmune diseases. This review comprehensively examines the physiological functions and heterogeneity of neutrophils, their interactions with other immune cells, and their significance in autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, antiphospholipid syndrome, antineutrophil cytoplasmic antibody-associated vasculitis, multiple sclerosis, and others. This review aims to provide a deeper understanding of the function of neutrophils in the development and progression of autoimmune disorders.

Profile of immunological biomarkers in Behcet's syndrome: a large-scale single-center real-world study

Behcet's syndrome (BS) is a vasculitis characterized by immune dysregulation. Biomarkers are valuable for assessing clinically atypical pathogenesis. We aimed to investigate the distribution of different biomarkers and their effects on the clinical features of patients with BS in a large-scale, real-world study. This is a retrospective, single-center study. In total, 502 patients diagnosed with BS were enrolled in this study. We analyzed the clinical features of this cohort and divided patients' symptoms into six categories, including mucocutaneous, articular, neurological, gastrointestinal, vascular, and ocular involvements. HLA-B51 cells, autoantibodies, and subsets of immune cells from the patients were tested. Pearson's correlation, Wilcoxon rank sum test and multivariate logistic regression were used for data analysis. Various autoantibodies were detected in the serum of 40.8% of patients with BS. The positivity rate of anti-endothelial cell antibodies (AECA) was the highest among autoantibodies and was found in 23.5% (118/502) of patients with BS. The positivity rate of HLA-B51 in patients with BS was 27.1%. Tumor necrosis factor (TNF)-α, IL-2, and IL-4 producing CD4+ T cells were positively correlated with the gastrointestinal BS. Increased IL-4+CD4+ T cell was a risk factor for gastrointestinal BS (P = 0.006, Overall rate [OR] = 2.491, 95% Confidence interval [CI]: [1.317, 5.100]). Various autoantibodies can be detected in patients with BS. HLA-B51 and AECA are the most common biomarkers. Increased IL-4+ CD4+ T cell was a risk factor for gastrointestinal involvement in BS.

Interferon Gamma Induces Higher Neutrophil Extracellular Traps Leading to Tumor-Killing Activity in Microsatellite Stable Colorectal Cancer

Many patients with colorectal cancer do not respond to immune checkpoint blockade (ICB) therapy, highlighting the urgent need to understand tumor resistance mechanisms. Recently, the link between the IFNγ signaling pathway integrity and ICB resistance in the colorectal cancer tumor microenvironment has been revealed. The immunosuppressive microenvironment poses a significant challenge to antitumor immunity in colorectal cancer development. Tumor-associated neutrophils found in tumor tissues exhibit an immunosuppressive phenotype and are associated with colorectal cancer patient prognosis. Neutrophil extracellular traps (NET), DNA meshes containing cytotoxic enzymes released into the extracellular space, may be promising therapeutic targets in cancer. This study showed increased NETs in tumor tissues and peripheral neutrophils of high levels of microsatellite instability (MSI-H) patients with colorectal cancer compared with microsatellite stable (MSS) patients with colorectal cancer. IFNγ response genes were enriched in MSI-H patients with colorectal cancer compared with patients with MSS colorectal cancer. Co-culturing neutrophils with MSI-H colorectal cancer cell lines induced more NET formation and higher cellular apoptosis than MSS colorectal cancer cell lines. IFNγ treatment induced more NET formation and apoptosis in MSS colorectal cancer cell lines. Using subcutaneous or orthotopic CT-26 (MSS) tumor-bearing mice models, IFNγ reduced tumor size and enhanced PD-1 antibody-induced tumor-killing activity, accompanied by upregulated NETs and cellular apoptosis. These findings suggest that IFNγ could be a therapeutic strategy for MSS colorectal cancer.

Gasdermin D deficiency aborts myeloid calcium influx to drive granulopoiesis in lupus nephritis

Gasdermin D (GSDMD) is emerging as an important player in autoimmune diseases, but its exact role in lupus nephritis (LN) remains controversial. Here, we identified markedly elevated GSDMD in human and mouse LN kidneys, predominantly in CD11b+ myeloid cells. Global or myeloid-conditional deletion of GSDMD was shown to exacerbate systemic autoimmunity and renal injury in lupus mice with both chronic graft-versus-host (cGVH) disease and nephrotoxic serum (NTS) nephritis. Interestingly, RNA sequencing and flow cytometry revealed that myeloid GSDMD deficiency enhanced granulopoiesis at the hematopoietic sites in LN mice, exhibiting remarkable enrichment of neutrophil-related genes, significant increases in total and immature neutrophils as well as granulocyte/macrophage progenitors (GMPs). GSDMD-deficient GMPs and all-trans-retinoic acid (ATRA)-stimulated human promyelocytes NB4 were further demonstrated to possess enhanced clonogenic and differentiation abilities compared with controls. Mechanistically, GSDMD knockdown promoted self-renewal and granulocyte differentiation by restricting calcium influx, contributing to granulopoiesis. Functionally, GSDMD deficiency led to increased pathogenic neutrophil extracellular traps (NETs) in lupus peripheral blood and bone marrow-derived neutrophils. Taken together, our data establish that GSDMD deletion accelerates LN development by promoting granulopoiesis in a calcium influx-regulated manner, unraveling its unrecognized critical role in LN pathogenesis.

Decoding Behcet's Uveitis: an In-depth review of pathogenesis and therapeutic advances

Behcet's disease (BD) is a rare but globally distributed vasculitis that primarily affects populations in the Mediterranean and Asian regions. Behcet's uveitis (BU) is a common manifestation of BD, occurring in over two-thirds of the patients. BU is characterized by bilateral, chronic, recurrent, non-granulomatous uveitis in association with complications such as retinal ischemia and atrophy, optic atrophy, macular ischemia, macular edema, and further neovascular complications (vitreous hemorrhage, neovascular glaucoma). Although the etiology and pathogenesis of BU remain unclear, numerous studies reveal that genetic factors (such as HLA-B51), dysregulated immune responses of both the innate and adaptive immune systems, infections (such as streptococcus), and environmental factors (such as GDP) are all involved in its development. Innate immunity, including hyperactivity of neutrophils and γδT cells and elevated NK1/NK2 ratios, has been shown to play an essential role in this disease. Adaptive immune system disturbance, including homeostatic perturbations, Th1, Th17 overaction, and Treg cell dysfunction, is thought to be involved in BU pathogenesis. Treatment of BU requires a tailored approach based on the location, severity of inflammation, and systemic manifestations. The therapy aims to achieve rapid inflammation suppression, preservation of vision, and prevention of recurrence. Systemic corticosteroids combined with other immunosuppressive agents have been widely used to treat BU, and beneficial effects are observed in most patients. Recently, biologics have been shown to be effective in treating refractory BU cases. Novel therapeutic targets for treating BU include the LCK gene, Th17/Treg balance, JAK pathway inhibition, and cytokines such as IL-17 and RORγt. This article summarizes the recent studies on BU, especially in terms of pathogenesis, diagnostic criteria and classification, auxiliary examination, and treatment options. A better understanding of the significance of microbiome composition, genetic basis, and persistent immune mechanisms, as well as advancements in identifying new biomarkers and implementing objective quantitative detection of BU, may greatly contribute to improving the adequate management of BU patients.

Sex-specific circulating unconventional neutrophils determine immunological outcome of auto-inflammatory Behçet's uveitis

Neutrophils are the most abundant immune cells that first respond to insults in circulation. Although associative evidence suggests that differences in neutrophils may be linked to the sex-specific vulnerability of inflammatory diseases, mechanistic links remain elusive. Here, we identified extensive sex-specific heterogeneity in neutrophil composition under normal and auto-inflammatory conditions at single-cell resolution. Using a combination of single-cell RNA sequencing analysis, neutrophil-specific genetic knockouts and transfer experiments, we discovered dysregulation of two unconventional (interferon-α responsive and T cell regulatory) neutrophil subsets leading to male-biased incidence, severity and poor prognosis of auto-inflammatory Behçet's uveitis. Genome-wide association study (GWAS) and exosome study revealed that male-specific negative effects of both genetic factors and circulating exosomes on unconventional neutrophil subsets contributed to male-specific vulnerability to disease. Collectively, our findings identify sex-specifically distinct neutrophil subsets and highlight unconventional neutrophil subsets as sex-specific therapeutic targets to limit inflammatory diseases.

[An update on Behçet's syndrome]

Behçet's syndrome (BS, synonym: Behçet's disease, or Adamantiades-Behçet's disease, ABD) is classified as a vasculitis of variable vessel size and can manifest itself in both arterial and venous vessels. Its extensive and at the same time interindividually very different clinical picture is not uncommon a challenge, both with regard to the diagnosis of this rheumatic systemic disease, which is rather rare in our latitudes, and its therapeutic options. In addition to the four cardinal symptoms of recurrent oral aphthae, genital aphthae, skin and eye lesions, the clinical picture offers numerous other manifestations which often require interdisciplinary cooperation. In addition to the above mentioned ocular involvement, which can still lead to blindness if inadequately treated, this is especially true for intestinal and cerebral manifestations as well as for large vessel vasculitis.A final revision of the European League Against Rheumatism recommendations for the management of Behcet's syndrome (EULAR) was made in 2018, and the recommendations are now established internationally as an important treatment guide. Therapy is based on the leading organ involvement. After adalimumab received approval for the treatment of posterior ocular involvement in 2016, another agent, apremilast, became available in 2020. The drug is recommended for the treatment of recurrent oral aphthae in adult Behçet's patients requiring systemic therapy. Nevertheless, there is a further need for new drugs.This article aims to highlight recent findings in the areas of epidemiology, immunopathogenesis & genetics, clinical findings, and therapy, with an emphasis on clinical relevance.

Behçet's syndrome

Behçet's syndrome is a rare, chronic multisystemic inflammatory disorder also known as the Silk Route disease due to its geographical distribution. Behçet's syndrome is a multifactorial disease and infectious, genetic, epigenetic, and immunological factors contribute to its pathogenesis. Its heterogeneous spectrum of clinical features include mucocutaneous, articular, ocular, vascular, neurological, and gastrointestinal manifestations that can present with a relapsing and remitting course. Differential diagnosis is often hampered by the non-specific clinical presentation and the absence of laboratory biomarkers or pathognomonic histological features. The therapeutic approach is tailored on the basis of patient-specific manifestations and relies on glucocorticoids, colchicine, and traditional and biological immunosuppressants. Despite progress in the knowledge and management of the disease, unmet needs in diagnostics, monitoring, prediction, and treatment personalisation challenge clinical practice, making Behçet's syndrome a complex disorder associated with an increased risk of morbidity.

Immunomodulatory effect of vitamin D supplementation on Behçet's disease patients: effect on nitric oxide and Th17/Treg cytokines production

INTRODUCTION

In the last decade, an immuno-modulatory effect of vitamin D supplementation have emerged as a potential therapeutic approach for some inflammatory and autoimmune diseases. As previously reported, vitamin D deficiency was strongly linked to several diseases as Behçet's disease (BD). BD is a chronic systemic inflammatory disorder with autoimmunity, genetic and environmental factors involvement. The aim of our current study is to set up a new therapeutic strategy in BD, combining conventional therapy and vitamin D supplementation.

MATERIALS AND METHODS

Blood samples were collected from active and inactive BD patients and healthy controls (HC) to evaluate 25(OH) vitamin D levels using an electrochemiluminescence method. All deficient and insufficient vitamin D BD patients' were supplemented with vitamin D3 (CHOLECALCIFEROL, 200 000 UI/1 ml). In this context, NO, IL-17A and IL-10 levels were evaluated in patients and HC in vivo and ex vivo using Griess and ELISA methods respectively.

RESULTS

Before supplementation, we noted with interest that BD patients had vitamin D deficiency, associated with elevated in vivo and ex vivo NO and IL-17A levels compared to HC. Conversely, low IL-10 levels were observed in the same BD patients in comparison to HC. Interestingly, restored vitamin D status in supplemented BD patients was related to the decreased NO levels. In the same way, the IL-10/IL-17A ratio was improved.

CONCLUSIONS

Collectively, our data suggest that vitamin D supplementation in combination with conventional treatments has a beneficial effect and could constitute a good therapeutic candidate for alleviating inflammatory responses during Behçet disease.

Plasma-derived exosomal protein SHP2 deficiency induces neutrophil hyperactivation in Behcet's uveitis

To investigate the effect of plasma-derived exosomal proteins on neutrophil hyperactivation in Behcet's uveitis (BU), we treated neutrophils from healthy controls with plasma-derived exosomes from active BU patients, and determined the level of neutrophil activation by real-time quantitative PCR (RT-qPCR) and cytokine detection assay. The results revealed that exosomes from active BU patients could activate neutrophils as shown by increasing the expression levels of pro-inflammatory cytokines (IL-17 and IL-6), chemokines (IL-8 and MCP-1), and NETs (MPO and ELANE). Label-free quantitative proteomic analysis of plasma-derived exosomes from patients and healthy controls found a remarkably distinct protein profile and identified differentially expressed proteins (DEPs) between the two groups. The results of GO, KEGG, and GSEA enrichment analysis showed that DEPs were enriched in innate immune-mediated and neutrophil hyperactivation-related signaling pathways. The protein-protein interaction (PPI) analysis determined that SHP2 was a downregulated key hub protein in the exosomes of active BU patients. Knockdown of SHP2 in human neutrophil cell lines (NB4 cells) was shown to promote the secretion of pro-inflammatory cytokines, chemokines, and NETs. The converse effects were observed following SHP2 overexpression. In conclusion, we highlighted a pathogenic role of plasma-derived exosomal SHP2 deficiency in facilitating neutrophil activation and suggested that SHP2 might be an immunoprotective factor in BU pathologic process.

Unveiling the Web: Exploring the Multifaceted Role of Neutrophil Extracellular Traps in Ocular Health and Disease

Neutrophil extracellular traps (NETs) play an essential role in antimicrobial defense. However, NETs have also been shown to promote and mediate a wide spectrum of diseases, including cancer, diabetes mellitus, cardiovascular diseases, and ocular diseases. Data regarding NETs in ocular diseases remain limited. In physiological conditions, NETs protect the eye from debris and cleave proinflammatory cytokines, including several interleukins. On the other hand, NETs play a role in corneal diseases, such as dry eye disease and ocular graft-versus-host disease, where they promote acinar atrophy and delayed wound healing. Additionally, NET levels positively correlate with increased severity of uveitis. NETs have also been described in the context of diabetic retinopathy. Although increased NET biomarkers are associated with an increased risk of the disease, NETs also assist in the elimination of pathological blood vessels and the regeneration of normal vessels. Targeting NET pathways for the treatment of ocular diseases has shown promising outcomes; however, more studies are still needed in this regard. In this article, we summarize the literature on the protective roles of NETs in the eye. Then, we describe their pathogenetic effects in ocular diseases, including those of the cornea, uvea, and retinal blood vessels. Finally, we describe the therapeutic implications of targeting NETs in such conditions.

Neutrophil extracellular traps and neutrophilic dermatosis: an update review

Neutrophils have both antimicrobial ability and pathogenic effect in the immune system, neutrophil extracellular traps (NETs) formation is one of the representative behaviors of their dual role. NETs formation was triggered by pathogen-related components and pathogen non-related proteins as cytokines to exert its effector functions. Recent studies indicate that the pathogenicity of NETs contributed to several skin diseases such as psoriasis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and neutrophilic dermatosis. Especially in neutrophilic dermatosis, a heterogeneous group of inflammatory skin disorders characterized with sterile neutrophilic infiltrate on dermis, NETs formation was reported as the way of participation of neutrophils in the pathogenesis of these diseases. In this review, we describe the different processes of NETs formation, then summarized the most recent updates about the pathogenesis of neutrophilic dermatosis and the participation of NETs, including pyoderma gangrenosum and PAPA syndrome, Behçet syndrome, hidradenitis suppurativa, Sweet Syndrome, pustular dermatosis and other neutrophilic dermatosis. Furthermore, we discuss the link between NETs formation and the development of neutrophilic dermatosis.

Rare presentation of thrombosis with bleeding in Behcet's disease

Behcet's disease (BD) is a rare autoimmune and autoinflammatory disease characterised by recurrent oral and genital aphthous ulcers as well as gastrointestinal, ocular, neurological, articular and vascular inflammation. Patients are at risk for both thrombotic events and bleeding, so providers are often challenged in deciding whether to start patients on anticoagulation. We report a rare, complex case of a patient with BD who presented with massive gastrointestinal bleeding. This case report highlights the management of recurrent thrombosis due to protein C and S deficiency in a patient with BD who also presents with acute gastrointestinal bleeding.

Enoxaparin improves COVID-19 by reducing Neutrophils Extracellular Traps (NETs) production

BACKGROUND

COVID-19 causes consequences such as imbalance of the immune system and thrombotic events. During the infection process, NETs in excess induce a pro-inflammatory response and disseminated intravascular coagulation. We evaluated the role of enoxaparin as a potential inhibitor of NETs.

METHODS

K18-hACE2 animals infected with the SARS-CoV-2 virus and a group of 23 individuals admitted to the hospital with COVID-19 treated with enoxaparin or without treatment and controls without the disease were included.

RESULTS

Enoxaparin decreased the levels of NETs, reduced the signs of the disease and mitigated lung damage in the animals infected with SARS-CoV-2. These effects were partially associated with prevention of SARS-CoV-2 entry and NETs synthesis. Clinical data revealed that treatment with enoxaparin decreased the levels of inflammatory markers, the levels of NETs in isolated neutrophils and the organ dysfunction.

CONCLUSION

This study provides evidence for the beneficial effects of enoxaparin in COVID-19 in addition to its anticoagulant role.

Behçet's Disease: A Comprehensive Review on the Role of HLA-B*51, Antigen Presentation, and Inflammatory Cascade

Behçet's disease (BD) is a complex, recurring inflammatory disorder with autoinflammatory and autoimmune components. This comprehensive review aims to explore BD's pathogenesis, focusing on established genetic factors. Studies reveal that HLA-B*51 is the primary genetic risk factor, but non-HLA genes (ERAP1, IL-10, IL23R/IL-12RB2), as well as innate immunity genes (FUT2, MICA, TLRs), also contribute. Genome-wide studies emphasize the significance of ERAP1 and HLA-I epistasis. These variants influence antigen presentation, enzymatic activity, and HLA-I peptidomes, potentially leading to distinct autoimmune responses. We conducted a systematic review of the literature to identify studies exploring the association between HLA-B*51 and BD and further highlighted the roles of innate and adaptive immunity in BD. Dysregulations in Th1/Th2 and Th17/Th1 ratios, heightened clonal cytotoxic (CD8+) T cells, and reduced T regulatory cells characterize BD's complex immune responses. Various immune cell types (neutrophils, γδ T cells, natural killer cells) further contribute by releasing cytokines (IL-17, IL-8, GM-CSF) that enhance neutrophil activation and mediate interactions between innate and adaptive immunity. In summary, this review advances our understanding of BD pathogenesis while acknowledging the research limitations. Further exploration of genetic interactions, immune dysregulation, and immune cell roles is crucial. Future studies may unveil novel diagnostic and therapeutic strategies, offering improved management for this complex disease.

Neutrophils in Inflammatory Diseases: Unraveling the Impact of Their Derived Molecules and Heterogeneity

Inflammatory diseases involve numerous disorders and medical conditions defined by an insufficient level of self-tolerance. These diseases evolve over the course of a multi-step process through which environmental variables play a crucial role in the emergence of aberrant innate and adaptive immunological responses. According to experimental data accumulated over the past decade, neutrophils play a significant role as effector cells in innate immunity. However, neutrophils are also involved in the progression of numerous diseases through participation in the onset and maintenance of immune-mediated dysregulation by releasing neutrophil-derived molecules and forming neutrophil extracellular traps, ultimately causing destruction of tissues. Additionally, neutrophils have a wide variety of functional heterogeneity with adverse effects on inflammatory diseases. However, the complicated role of neutrophil biology and its heterogeneity in inflammatory diseases remains unclear. Moreover, neutrophils are considered an intriguing target of interventional therapies due to their multifaceted role in a number of diseases. Several approaches have been developed to therapeutically target neutrophils, involving strategies to improve neutrophil function, with various compounds and inhibitors currently undergoing clinical trials, although challenges and contradictions in the field persist. This review outlines the current literature on roles of neutrophils, neutrophil-derived molecules, and neutrophil heterogeneity in the pathogenesis of autoimmune and inflammatory diseases with potential future therapeutic strategies.

Ileocecal involvement in intestinal Behçet's disease and Crohn's disease: comparison of clinicopathological and immunophenotypic features

OBJECTIVES

Intestinal Behçet's disease (BD) predominantly affects the ileocecal region and is currently diagnosed based on endoscopic features and clinical manifestations. It is difficult to distinguish between intestinal BD and Crohn's disease (CD) due to similar patient populations, gastrointestinal involvement, extraintestinal manifestations, and long-term recurrent course. In this study we aimed to compare the clinicopathological and immunophenotypic features of intestinal BD to CD.

METHODS

The medical and pathological records of 29 cases of intestinal BD and 120 cases of CD diagnosed at Sir Run Run Shaw Hospital were retrospectively analyzed. Immunohistochemistry for CD3, CD20, FOXP3, myeloperoxidase, and quantitative analysis of the infiltrating inflammatory cells was conducted.

RESULTS

Intestinal BD with ileocecal ulcer had a higher incidence of abdominal pain and a higher erythrocyte sedimentation rate than CD, while chronic diarrhea was more common in CD. Excessive neutrophils in the mucosal lamina propria, neutrophilic exudate on the ulcer surface, and prominent lymphocytic infiltration in ulcer tissues were statistically more frequent in intestinal BD than in CD. The numbers of FOXP3+ T cells, CD3+ T cells, and CD20+ B cells in biopsy tissue from intestinal BD were significantly higher than CD, but the ratio of FOXP3+ T cells to CD3+ T cells was not statistically different.

CONCLUSION

Besides the typical clinical and endoscopic findings, diagnostic biopsies from the ileocecal region in intestinal BD show some histological and immunophenotypic features that are different from CD, which may be useful in distinguishing these two entities.

Risk factors, clinical features and treatment of Behçet's disease uveitis

Behçet's disease is a systemic vasculitis frequently associated with intraocular inflammation. Recent findings identified independent clinical clusters in Behçet's disease, each involving distinct combinations of affected organs. Ocular Behçet's disease, mainly manifested as uveitis, is characterized as an independent cluster with a low likelihood of association with other system involvements, such as intestinal, cardiovascular, or central nervous system. A prevailing theory suggests that the pathogenesis of the disease is multifactorial, where a variety of genetic and infectious agents may interact with each other to cause the disease. Among sporadic cases, the human leukocyte antigen (HLA) genes, including HLA-B51, HLA-A26, HLA-B15, and HLA-B5701, have been found to be a key component conferring genetic susceptibility. Outside the HLA region, a set of susceptibility variants are identified, closely related to interleukin (IL)-23/IL-17 pathway, tumor necrosis factor (TNF) signaling, and pattern recognition receptor systems. Microbial infections, such as Streptococcus sanguinis, Mycobacterium tuberculosis, and Herpes simplex virus (HSV), are linked to play the triggering of disease in immunogenetically predisposed individuals. Clinically, due to the notable relapsing-remitting course of ocular Behçet's disease, the prevention of recurrent attack would be the primary treatment goal. Combination of corticosteroids and immunomodulatory drugs, such as anti-TNF agents, interferon, and conventional immunosuppressants (e.g. cyclosporine, azathioprine), have been the mainstream regimen for the disease. Future research may focus on comparing the effectiveness of immunomodulatory drugs and identifying the most suitable subgroups for a specific drug on the basis of the knowledge of the molecular heterogeneity of the disease.

Secretion of mitochondrial DNA via exosomes promotes inflammation in Behçet's syndrome

Mitochondrial DNA (mtDNA) leakage into the cytoplasm can occur when cells are exposed to noxious stimuli. Specific sensors recognize cytoplasmic mtDNA to promote cytokine production. Cytoplasmic mtDNA can also be secreted extracellularly, leading to sterile inflammation. However, the mode of secretion of mtDNA out of cells upon noxious stimuli and its relevance to human disease remain unclear. Here, we show that pyroptotic cells secrete mtDNA encapsulated within exosomes. Activation of caspase-1 leads to mtDNA leakage from the mitochondria into the cytoplasm via gasdermin-D. Caspase-1 also induces intraluminal membrane vesicle formation, allowing for cellular mtDNA to be taken up and secreted as exosomes. Encapsulation of mtDNA within exosomes promotes a strong inflammatory response that is ameliorated upon exosome biosynthesis inhibition in vivo. We further show that monocytes derived from patients with Behçet's syndrome (BS), a chronic systemic inflammatory disorder, show enhanced caspase-1 activation, leading to exosome-mediated mtDNA secretion and similar inflammation pathology as seen in BS patients. Collectively, our findings support that mtDNA-containing exosomes promote inflammation, providing new insights into the propagation and exacerbation of inflammation in human inflammatory diseases.

IL-8 Triggers Neutrophil Extracellular Trap Formation Through an Nicotinamide Adenine Dinucleotide Phosphate Oxidase- and Mitogen-Activated Protein Kinase Pathway-Dependent Mechanism in Uveitis

Purpose

To explore the mechanism underlying IL-8-induced neutrophil extracellular trap (NET) formation in patients with ocular-active Behçet's disease (BD) and the effect of inhibiting NET formation on the severity of inflammation in experimental autoimmune uveitis (EAU) mice.

Methods

The serum extracellular DNA and neutrophil elastase (NE) and IL-8 levels in patients with ocular-active BD, the expression of myeloperoxidase, NE, and histone H3Cit in IL-8-induced neutrophils isolated from healthy controls, and the effects of NETs on HMC3 cells were detected. Female C57BL/6J mice were immunized with IRBP651-670 to induce EAU and EAU mice received intravitreal injection of the CXCR2 (IL-8 receptor) antagonist SB225002 or PBS. The serum levels of extracellular DNA, NE, and keratinocyte-derived chemokine (the mouse ortholog of human IL-8) and expression of myeloperoxidase, NE, and histone H3Cit in mouse retinas were detected. Disease severity was evaluated by clinical and histopathological scores.

Results

Serum keratinocyte-derived chemokine expression levels in EAU mice and IL-8 expression levels in patients with ocular-active BD increased. IL-8 notably increased NET formation in a dose-dependent manner through an nicotinamide adenine dinucleotide phosphate oxidase and mitogen-activated protein kinase pathway dependent mechanism. IL-8-induced NET formation damaged HMC3 cells in vitro. Pretreatment with SB225002 notably ameliorated the production of NETs in EAU mice.

Conclusions

Our data confirm that NET formation is induced by IL-8. IL-8-induced NET formation was found to be related to mitogen-activated protein kinase and nicotinamide adenine dinucleotide phosphate pathways. Pretreatment with the CXCR2 antagonist SB225002 alleviated neutrophil infiltration and suppressed NET formation in EAU mice.

Cerebrovascular involvement in systemic childhood vasculitides

Pediatric vasculitides sometimes involve central nervous system (CNS). The manifestations are diverse, ranging from headache, seizures, vertigo, ataxia, behavioral changes, neuropsychiatric symptoms, consciousness disorders, and even cerebrovascular (CV) accidents that may lead to irreversible impairment and even death. Stroke, on the other hand despite the great progress in prevention and treatment, is still one of the leading causes of morbidity and mortality in the general population. The aim of this article was to summarize CNS manifestations and CV issues observed in primary pediatric vasculitides and the current knowledge of etiology and CV risk factors, preventive strategies, and therapeutic options in this target patient population. Pathophysiological links reveal similar immunological mechanisms involved in both pediatric vasculitides and CV events with endothelial injury and damage being the central point. From the clinical point of view, CV events in pediatric vasculitides were associated with increased morbidity and poor prognosis. If damage has already occurred, the therapeutic approach consists of good management of the vasculitis itself, antiplatelet and anticoagulation therapy, and early rehabilitation. Risk factors for acquiring cerebrovascular disease (CVD) and stroke, particularly hypertension and early atherosclerotic changes, already begin in childhood, with vessel wall inflammation contributing itself, once more emphasizing that appropriate preventive measures are certainly necessary in pediatric vasculitis population to improve their long-term outcome.

Reduction of Neutrophil Activation by Phosphodiesterase 4 Blockade in Behçet's Disease

OBJECTIVE

Behçet's disease (BD) is a systemic vasculitis with inflammatory lesions mediated by cytotoxic T cells and neutrophils. Apremilast, an orally available small-molecule drug that selectively inhibits phosphodiesterase 4 (PDE4), has been recently approved for the treatment of BD. We aimed to investigate the effect of PDE4 inhibition on neutrophil activation in BD.

METHODS

We studied surface markers and reactive oxygen species (ROS) production by flow cytometry, and neutrophil extracellular traps (NETs) production and molecular signature of neutrophils by transcriptome analysis before and after PDE4 inhibition.

RESULTS

Activation surface markers (CD64, CD66b, CD11b, and CD11c), ROS production, and NETosis were up-regulated in BD patient neutrophils compared to healthy donor neutrophils. Transcriptome analysis revealed 1,021 significantly dysregulated neutrophil genes between BD patients and healthy donors. Among dysregulated genes, we found a substantial enrichment for pathways linked to innate immunity, intracellular signaling, and chemotaxis in BD. Skin lesions of BD patients showed increased infiltration of neutrophils that colocalized with PDE4. Inhibition of PDE4 by apremilast strongly inhibited neutrophil surface activation markers as well as ROS production, NETosis, and genes and pathways related to innate immunity, intracellular signaling, and chemotaxis.

CONCLUSION

We highlight key biologic effects of apremilast on neutrophils in BD.

[An update on Behçet's syndrome]

Behçet's syndrome (BS, synonym: Behçet's disease, or Adamantiades-Behçet's disease, ABD) is classified as a vasculitis of variable vessel size and can manifest itself in both arterial and venous vessels. Its extensive and at the same time interindividually very different clinical picture is not uncommon a challenge, both with regard to the diagnosis of this rheumatic systemic disease, which is rather rare in our latitudes, and its therapeutic options. In addition to the four cardinal symptoms of recurrent oral aphthae, genital aphthae, skin and eye lesions, the clinical picture offers numerous other manifestations which often require interdisciplinary cooperation. In addition to the above mentioned ocular involvement, which can still lead to blindness if inadequately treated, this is especially true for intestinal and cerebral manifestations as well as for large vessel vasculitis.A final revision of the European League Against Rheumatism recommendations for the management of Behcet's syndrome (EULAR) was made in 2018, and the recommendations are now established internationally as an important treatment guide. Therapy is based on the leading organ involvement. After adalimumab received approval for the treatment of posterior ocular involvement in 2016, another agent, apremilast, became available in 2020. The drug is recommended for the treatment of recurrent oral aphthae in adult Behçet's patients requiring systemic therapy. Nevertheless, there is a further need for new drugs.This article aims to highlight recent findings in the areas of epidemiology, immunopathogenesis & genetics, clinical findings, and therapy, with an emphasis on clinical relevance.

Immunopathogenesis of Behçet's disease

Behçet's disease (BD) is a multi-system inflammatory disorder with vasculitic features. It does not suit any of the current pathogenesis-driven disease classifications well, a unifying concept of its pathogenesis is not unanimously conceivable at present, and its etiology is obscure. Still, evidence from immunogenetic and other studies supports the notion of a complex-polygenic disease with robust innate effector responses, reconstitution of regulatory T cells upon successful treatment, and first clues to the role of an, as of yet, underexplored adaptive immune system and its antigen recognition receptors. Without an attempt to be comprehensive, this review aims to collect and organize impactful parts of this evidence in a way that allows the reader to appreciate the work done and define the efforts needed now. The focus is on literature and notions that drove the field into new directions, whether recent or more remote.

Neutrophilic dermatosis and hidradenitis suppurativa in patients with Behçet's disease: A neutrophilic disease in the spectrum of autoinflammatory syndromes

BACKGROUND

Association of neutrophilic dermatosis (ND), hidradenitis suppurativa (HS) and Behçet's disease (BD) and shared efficacy of TNFα axis blockade suggests common physiopathology.

OBJECTIVES

To investigate the clinical features and therapeutic response of ND and HS associated with BD.

METHODS

We identified 20 patients with ND or HS associated with BD among 1462 patients with BD.

RESULTS

We analysed 20 (1.4%) patients diagnosed with ND or HS associated with BD: 13 HS, 6 pyoderma gangrenosum (PG), and 1 SAPHO. Our 6 PG cases over 1462 BD patients accounts for 400/100 000 prevalence. Thirteen had bipolar aphthosis, 6 vascular, 5 neurologic, and 4 ocular involvements. All PG occurred on limbs and had typical histology with constant dermal neutrophilic infiltrate. All HS had the classical axillary-mammary phenotype. Sixty-nine percent (69%) of HS were Hurley 1 stage. Treatment consisted mainly in colchicine (n = 20), glucocorticoids (n = 12), and anti-TNFα (n = 9). Interesting results with complete or partial responses were obtained with anti-TNFα (9 cases), ustekinumab (3 cases) and tocilizumab (1 case) to treat refractory ND or HS associated with BD.

CONCLUSION

PG seems overrepresented in patients with BD. Biotherapies such as anti-TNFα, ustekinumab and tocilizumab appear to be promising to treat refractory ND or HS associated with BD.

Behçet Syndrome

Behçet's syndrome is a systemic vasculitis affecting arteries and veins of all sizes as well as recurrent oral, genital, and intestinal ulcers, skin lesions, predominantly posterior uveitis, and parenchymal brain lesions. These can be present in various combinations and sequences over time and diagnosis is made by recognizing the manifestations, as there are no diagnostic biomarkers or genetic tests. Treatment modalities include immunomodulatory agents, immunosuppressives and biologics, tailored according to prognostic factors, disease activity, severity, and patients' preferences.

Tocilizumab suppresses NF-kappa B activation via toll-like receptor 9 signaling by reducing cell-free DNA in rheumatoid arthritis

Endogenous DNA is released into the bloodstream as cell-free DNA (cfDNA) following cell death and is associated with various pathological conditions. However, their association with therapeutic drugs against rheumatoid arthritis (RA) remains unknown. Therefore, we investigated the significance of cfDNA in RA treated with tocilizumab and tumour necrosis factor inhibitor (TNF-I). Biological DMARDs (bDMARDs), including tocilizumab and TNF-I, were administered to 77 and 59 RA patients, respectively. Plasma cfDNA levels were measured at weeks 0, 4, and 12 by quantitative polymerase chain reaction. Disease activity was evaluated at the same time point using DAS28ESR. cfDNA levels from RA synovial cells treated with tocilizumab or etanercept for 24 h were measured. Human toll-like receptor 9 (hTLR9)-expressing HEK293 cells, which release secreted embryonic alkaline phosphatase (SEAP) upon NF-κB activation, were stimulated by cfDNA from RA patients, and subsequently, SEAP levels were determined. NF-κB translocation was evaluated by immunofluorescence staining with or without tocilizumab. The DAS28ESR significantly improved in both bDMARD groups at week 12. However, plasma cfDNA levels significantly decreased in the tocilizumab group at week 12 compared to that in week 0. cfDNA levels correlated with DAS28ESR in biological treatment-naïve patients administered tocilizumab. cfDNA levels in synovial cells were significantly suppressed by tocilizumab treatment and unaltered with etanercept. HEK293 cells released SEAP upon cfDNA stimulation, and the observed NF-κB nuclear translocation was suppressed by tocilizumab. Tocilizumab suppressed inflammation via the TLR9 pathway by decreasing cfDNA levels. Regulation of cfDNA may be a therapeutic target for RA.

Innate immune responses in Behçet disease and relapsing polychondritis

Behçet disease (BD) and relapsing polychondritis (RP) are chronic multisystem disorders characterized by recurrent flare-ups of tissue inflammation. Major clinical manifestations of BD are oral aphthae, genital aphthous ulcers, skin lesions, arthritis, and uveitis. Patients with BD may develop rare but serious neural, intestinal, and vascular complications, with high relapse rates. Meanwhile, RP is characterized by the inflammation of the cartilaginous tissues of the ears, nose, peripheral joints, and tracheobronchial tree. Additionally, it affects the proteoglycan-rich structures in the eyes, inner ear, heart, blood vessels, and kidneys. The mouth and genital ulcers with inflamed cartilage (MAGIC) syndrome is a common characteristic of BD and RP. The immunopathology of these two diseases may be closely related. It is established that the genetic predisposition to BD is related to the human leukocyte antigen (HLA)-B51 gene. Skin histopathology demonstrates the overactivation of innate immunity, such as neutrophilic dermatitis/panniculitis, in patients with BD. Monocytes and neutrophils frequently infiltrate cartilaginous tissues of patients with RP. Somatic mutations in UBA1, which encodes a ubiquitylation-related enzyme, cause vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome (VEXAS) with severe systemic inflammation and activation of myeloid cells. VEXAS prompts auricular and/or nasal chondritis, with neutrophilic infiltration around the cartilage in 52-60% of patients. Thus, innate immune cells may play an important role in the initiation of inflammatory processes underlying both diseases. This review summarizes the recent advances in our understanding of the innate cell-mediated immunopathology of BD and RP, with a focus on the common and distinct features of these mechanisms.

Behçet syndrome: The disturbed balance between anti- (CLEC12A, CLC) and proinflammatory (IFI27) gene expressions

INTRODUCTION

Behçet syndrome (BS) is a chronic, multisystemic inflammatory condition with unanswered questions regarding its pathogenesis and rational therapeutics. A microarray-based comparative transcriptomic analysis was performed to elucidate the molecular mechanisms of BS and identify any potential therapeutic targets.

METHODS

Twenty-nine BS patients (B) and 15 age and sex-matched control subjects (C) were recruited. Patients were grouped as mucocutaneous (M), ocular (O), and vascular (V) according to their clinical phenotypes. GeneChip Human Genome U133 Plus 2.0 arrays were used for expression profiling on peripheral blood samples of the patients and the control subjects. Following documentation of the differentially expressed gene (DEG) sets, the data were further evaluated with bioinformatics analysis, visualization, and enrichment tools. Validation of the microarray data was performed using quantitative reverse transcriptase polymerase chain reaction.

RESULTS

When p ≤ 0.05 and fold change ≥2.0 were chosen, the following numbers of DEGs were obtained; B versus C: 28, M versus C: 20, O versus C: 8, V versus C: 555, M versus O: 6, M versus V: 324, O versus V: 142. Venn diagram analysis indicated only two genes, CLEC12A and IFI27, in the intersection of M versus C ∩ O versus C ∩ V versus C. Another noteworthy gene appeared as CLC in the DEG sets. Cluster analyses successfully clustered distinct clinical phenotypes of BS. While innate immunity-related processes were enriched in the M group, adaptive immunity-specific processes were significantly enriched in the O and V groups.

CONCLUSIONS

Distinct clinical phenotypes of BS patients displayed distinct expression profiles. In Turkish BS patients, expression differences regarding the genes CLEC12A, IFI27, and CLC seemed to be operative in the disease pathogenesis. Based on these findings, future research should consider the immunogenetic heterogeneity of BS clinical phenotypes. Two anti-inflammatory genes, namely CLEC12A and CLC, may be valuable as therapeutic targets and may also help design an experimental model in BS.

Neutrophil, NETs and Behçet's disease: A review

Behçet's disease (BD) is a chronic systemic vasculitis characterized by recurrent oral and genital ulcers, skin lesions, articular, neurological, vascular and sight-threatening ocular inflammation. BD is thought to share both autoimmune and autoinflammatory disease features. BD is triggered by environmental factors such as infectious agents in genetically predisposed subjects. Neutrophils seem to play an instrumental role in BD and recent works regarding the role of neutrophils extracellular traps (NETs) provides new insight in the pathophysiology of BD and the mechanisms involved in immune thrombosis. This review provides a recent overview on the role of neutrophils and NETs in the pathogenesis of BD.

Proteomics Landscape Mapping of Organ-Resolved Behçet's Disease Using In-Depth Plasma Proteomics for Identifying Hyaluronic Binding Protein 2 Expression Associated With Vascular Involvement

OBJECTIVE

This study was undertaken to elucidate the pathogenesis and heterogeneity of Behçet's disease (BD) involving different organs using in-depth proteomics to identify the biomarkers for clinical assessment and treatment of patients with BD.

METHODS

We measured the expression levels of proteins in plasma samples from 98 patients with BD and from 31 healthy controls using our in-depth proteomics platform with a data-independent acquisition mass spectrometer and antibody microarray. We performed bioinformatics analyses of the biologic processes and signaling pathways that were changed in the BD group and constructed a proteomics landscape of organ-resolved BD pathogenesis. We then validated the biomarkers of disease severity and the vascular subset in an independent cohort of 108 BD patients and 29 healthy controls using an enzyme-linked immunosorbent assay.

RESULTS

The BD group had 220 differentially expressed proteins, which discriminated between BD patients (88.6%) and healthy controls (95.5%). The bioinformatics analyses revealed different biologic processes associated with BD pathogeneses, including complement activation, wound healing, angiogenesis, and leukocyte-mediated immunity. Furthermore, the constructed proteomics landscape of organ-resolved BD identified proteomics features of BD associated with different organs and protein targets that could be used for the development of therapeutic treatment. Hyaluronic binding protein 2, tenascin, and serpin A3 were validated as potential biomarkers for the clinical assessment of vascular BD and treatment targets.

CONCLUSION

Our results provide valuable insight into the pathogenesis of organ-resolved BD in terms of proteomics characteristics and potential biomarkers for clinical assessment and potential therapies for vascular BD.

Highlights from the International Chronic Thromboembolic Pulmonary Hypertension Congress 2021

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism. It is caused by persistent obstruction of pulmonary arteries by chronic organised fibrotic clots, despite adequate anticoagulation. The pulmonary hypertension is also caused by concomitant microvasculopathy which may progress without timely treatment. Timely and accurate diagnosis requires the combination of imaging and haemodynamic assessment. Optimal therapy should be individualised to each case and determined by an experienced multidisciplinary CTEPH team with the ability to offer all current treatment modalities. This report summarises current knowledge and presents key messages from the International CTEPH Conference, Bad Nauheim, Germany, 2021. Sessions were dedicated to 1) disease definition; 2) pathophysiology, including the impact of the hypertrophied bronchial circulation, right ventricle (dys)function, genetics and inflammation; 3) diagnosis, early after acute pulmonary embolism, using computed tomography and perfusion techniques, and supporting the selection of appropriate therapies; 4) surgical treatment, pulmonary endarterectomy for proximal and distal disease, and peri-operative management; 5) percutaneous approach or balloon pulmonary angioplasty, techniques and complications; and 6) medical treatment, including anticoagulation and pulmonary hypertension drugs, and in combination with interventional treatments. Chronic thromboembolic pulmonary disease without pulmonary hypertension is also discussed in terms of its diagnostic and therapeutic aspects.

Vascular Behçet syndrome: from pathogenesis to treatment

Behçet syndrome is a rare, chronic inflammatory disease of unknown aetiopathogenesis, most commonly presenting with mucocutaneous and ocular manifestations. Vascular involvement, most frequently superficial vein and deep vein thrombosis, can occur in up to 50% of patients with Behçet syndrome. Venous thrombosis at atypical sites (inferior and superior vena cava, suprahepatic veins with Budd-Chiari syndrome, portal vein, cerebral sinuses and right atrium and/or ventricle) and arterial involvement (mostly in situ thrombosis and aneurysms of the pulmonary arteries, as well as aneurysms of the abdominal aorta, and peripheral and visceral arteries) are also unique features of Behçet syndrome. Behçet syndrome is considered a natural model of inflammation-induced thrombosis in humans, with an impaired immune-inflammatory response rather than traditional cardiovascular risk factors contributing to thrombogenesis. Specifically, neutrophil hyperactivation and neutrophil-mediated mechanisms of damage directly promote endothelial dysfunction, platelet activation and thrombogenesis in Behçet syndrome. This unusual pathogenesis directly determines the treatment approach, which relies mostly on immunosuppressants rather than anticoagulants for treatment of thrombosis and for secondary prevention. This Review discusses the main histopathological, pathogenetic and clinical aspects of vascular Behçet syndrome, addressing their implications for therapeutic management. Future perspectives in terms of pathogenetic studies, disease monitoring and treatment strategies are also discussed.

An update on VEXAS syndrome

INTRODUCTION

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a recently described, late-onset, acquired autoinflammatory disorder caused by mutations in the UBA1 gene. The various clinical manifestations of VEXAS broadly divided into inflammatory or haematological. VEXAS defines a new disease category - the hematoinflammatory disorders triggered by somatic mutations restricted to blood but causing systemic inflammation with multi-organ involvement and associated with aberrant bone marrow status. VEXAS causes significant morbidity and reduced life expectancy, but the optimum standard of care remains undefined.

AREAS COVERED

This review describes the discovery of VEXAS, relevant genetic causes and immunopathology of the disease. A detailed account of its various clinical manifestations and disease mimics is provided. Current treatment and management options are discussed.

EXPERT OPINION

New rare variants in UBA1 and VEXAS-like UBA1 negative cases are reported. Consensus diagnostic criteria might be required to define VEXAS and its related disorders. Investigation of sporadic, VEXAS-like cases will require the application of deep sequencing using DNA obtained from various cellular or tissue locations. Prospective studies are needed to define the optimal supportive and treatment options for patients with varying disease severity and prognosis. VEXAS-specific hematopoietic stem cell transplant selection criteria also require development.

[Vascular manifestations of Behcet's disease]

Behçet disease is a multi-systemic complex vasculitis with unknown etiology characterized by different clinical involvements, including mucocutaneous, ocular, vascular, articular, neurological and gastrointestinal manifestations. Growing evidence supports that different phenotypes, characterized by clusters of co-existing involvements, can be distinguished. Namely, the vascular phenotype identifies a specific group of patients who suffer from recurrent inflammatory thrombosis and arterial involvement. Vascular disease develops in up to 40% with a definite male preponderance and is usually an early manifestation. It is one of the main causes of death in Behçet's disease. Venous involvement is significantly more common than arterial disease and lower extremity deep vein thrombosis is its most frequent manifestation. Arterial disease involves mostly pulmonary arteries and aorta and manifests mainly in the form of aneurysms. Glucocorticoids and immunosuppressant's are the recommended first-line treatments in vasculo-Behçet. Furthermore, randomized controlled trials are still needed to assess the role of adding anticoagulation to current standard therapy in venous thrombosis in Behçet's disease and to assess the role of anti-TNF alpha therapy in vasculo-Behçet.

Chemokines and chemokine receptors in Behçet's disease

Behçet's disease (BD), a chronic vascular inflammatory disease, is characterized by the symptoms of ocular lesions, recurrent genital and oral ulcers, skin symptoms and arthritis in addition to neurological, intestinal and vascular involvement. The pathogenesis of BD is poorly understood, and there are no effective laboratory markers for the diagnosis of BD. In addition, BD is presently incurable. Chemokines, a family of small secreted chemotactic cytokines, interact with chemokine receptors and mediate the migration, localization and cellular interactions of inflammatory cells. Several studies have suggested that chemokines and their receptors play an important role in the occurrence and development of BD and that these chemokines along with their receptors can be utilized as biomarkers and therapeutic targets. In the present review, chemokines and chemokine receptors involved in BD and their potential application in diagnosis and therapy have been discussed.