Possible mechanisms of neutrophil activation in Behçet's disease

Quantitative urinary proteome analysis reveals potential biomarkers for disease activity of Behcet's disease uveitis

PURPOSE

Behçet's disease-associated uveitis (BDU) is a severe, recurrent inflammatory condition affecting the eye and is part of a systemic vasculitis with unknown etiology, making biomarker discovery essential for disease management. In this study, we intend to investigate potential urinary biomarkers to monitor the disease activity of BDU.

METHODS

Firstly, label-free data-dependent acquisition (DDA) and tandem mass tag (TMT)-labeled quantitative proteomics methods were used to profile the proteomes of urine from active and quiescent BDU patients, respectively. For further exploration, the remaining fifty urine samples were analyzed by a data-independent acquisition (DIA) quantitative proteomics method.

RESULTS

Twenty-nine and 21 differential proteins were identified in the same urine from BDU patients by label-free DDA and TMT-labeled analyses, respectively. Seventy-nine differentially expressed proteins (DEPs) were significantly changed in other active BDU urine samples compared to those in quiescent BDU urine samples by IDA analysis. Gene Ontology (GO) and protein-protein interaction (PPI) analyses revealed that the DEPs were associated with multiple functions, including the immune and neutrophil activation responses. Finally, seven proteins were identified as candidate biomarkers for BDU monitoring and recurrence prediction, namely, CD38, KCRB, DPP4, FUCA2, MTPN, S100A8 and S100A9.

CONCLUSIONS

Our results showed that urine can be a good source of biomarkers for BDU. These dysregulated proteins provide potential urinary biomarkers for BDU activity monitoring and provide valuable clues for the analysis of the pathogenic mechanisms of BDU.

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.

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.

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.

Intestinal Behcet's Disease: A Review of the Immune Mechanism and Present and Potential Biological Agents

Behcet's disease (BD) is a chronic and recurrent systemic vasculitis involving almost all organs and tissues. Intestinal BD is defined as BD with predominant gastrointestinal involvement, presenting severe complications such as massive gastrointestinal hemorrhage, perforation, and obstruction in some cases. To some extent, intestinal BD is classified as a member of inflammatory bowel disease (IBD), as it has a lot in common with classical IBD including Crohn's disease (CD) and ulcerative colitis (UC). Certainly, the underlying pathogenesis is not the same and dysregulation of immune function is believed to be one of the main pathogeneses in intestinal BD, although the etiology has not been clear up to now. Biological agents are an emerging category of pharmaceuticals for various diseases, including inflammatory diseases and cancers, in recent decades. Based on the deep understanding of the immune mechanism of intestinal BD, biological agents targeting potential pathogenic cells, cytokines and pathways are optimized options. Recently, the adoption of biological agents such as anti-tumor necrosis factor agents has allowed for the effective treatment of patients with refractory intestinal BD who show poor response to conventional medications and are faced with the risk of surgical treatment. In this review, we have tried to summarize the immune mechanism and present potential biological agents of intestinal BD.

Baricitinib for the treatment of refractory vascular Behçet's disease

OBJECTIVE

The pilot study aims to evaluate the effectiveness and safety of baricitinib in Behcet's Disease (BD) patients with refractory vascular involvement.

METHODS

We consecutively enrolled vascular/cardiac BD patients who received baricitinib (2 mg/day) along with glucocorticoids (GCs) and immunosuppressants in our center. Efficacy assessment mainly depends on the proportion of clinical remission and side effects were recorded.

RESULTS

17 patients (12 males) were included with a mean follow-up of 10.7 ± 5.3 months. At 3 months of follow-up, 76.5% of patients achieved a complete response and the proportion increased to 88.2% at the last visit. During follow-up, ESR (p < 0.01) and hsCRP (p < 0.0001) decreased significantly, as well as Behçet's Disease Current Activity Form score (p < 0.01). In addition, baricitinib showed a GCs-sparing effect. No serious adverse events were noted.

CONCLUSIONS

Our study suggests that baricitinib is well-tolerated and effective in treating refractory vascular/cardiac BD patients.

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.

Platelet lymphocyte ratio, lymphocyte monocyte ratio, mean platelet volume, and neutrophil lymphocyte ratio in Behcet’s disease and their relation to disease activity

Background

Behcet’s disease (BD) does not have specific laboratory finding or pathological physical examination sign, and only few studies have investigated Neutrophil to lymphocyte ratio (NLR), platelets to lymphocytes ratio (PLR), lymphocytes to monocytes ratio (LMR), or mean platelet volume (MPV) values in patients with BD. We conducted this study to investigate the relationship between these indices and Behcet’s disease (BD) and to determine their relation to BD disease activity.

Results

This study is a case-control study that included 36 Behcet’s disease patients and 36 healthy controls. BD patients showed significant increase in the mean of NLR and PLR in comparison to control (P = 0.008 and 0.011) respectively, and highly significant decrease in LMR and MPV levels in BD patients in comparison to control (P < 0.001 and < 0.001) respectively. Also, we found that NLR, PLR, and LMR were significantly related to BD activity, and there were significant associations between the studied hematological parameters with some of muco-cutaneous, articular, gastrointestinal, eye, and nervous system manifestations in BD patients.

Conclusion

The blood indices NLR, PLR, LMR, and MPV are potential inflammatory markers that can be used to evaluate inflammatory status and disease activity in patients with BD. NLR and PLR showed positive relation being higher in active disease and also higher in highly active disease than in low disease activity. Also, LMR was significantly decreased in Behcet’s disease patients in relation to disease activity. Furthermore, NLR and PLR levels were significantly more associated with muco-cutaneous and nervous system involvement while, LMR levels were significantly associated with muco-cutaneous, articular, gastrointestinal and eye manifestations and MPV levels were associated with articular manifestations being significantly related to disease activity. These easily evaluated markers could help in the management of this disease with multisystem affection that are sometimes serious and potentially life threatening.

Anti-tumour necrosis factor-alpha agent therapy, compared with conventional therapy, reduces the relapse of uveitis in patients with behçet’s disease: A systematic review of controlled trials

Purpose: Anti-tumour necrosis factor-alpha (TNF-α) agents are often used for Behçet’s disease (BD) in clinical practice, but they have not been validated by a high level of evidence. We systematically reviewed published controlled trials to investigate the efficacy and safety of anti-TNF-α therapy and summarize the efficacy of anti-TNF-α therapy relative to the available therapeutic options.

Methods: A systematic database search was conducted (PubMed, Embase and Cochrane) using specific search terms. All controlled studies of anti-TNF-α treatment of BD patients prior to December 2021 were included. Single-arm studies were excluded. The decision of whether to incorporate data into the meta-analysis or summarize the data by qualitative synthesis was based on the results of the literature screening.

Results: Of 4389 screened studies, 13 (total 778 patients) were included in accordance with our retrieval strategy, comprising 1 randomized controlled trial, 1 prospective study, 10 retrospective studies, and 1 multicentre open-label study. Ten studies (76.9%) involved Behçet’s uveitis (BU), 1 involved intestinal BD, and the other studies had undefined subtypes. Subgroup reviews were conducted according to the control drug. Four studies involving 167 participants reported relapse rates. Meta-analysis of three of these studies demonstrated that, compared with traditional immunosuppressant (TIS) therapy, anti-TNF-α therapy reduced the relapse rates in patients with BU. In targeted drug comparison studies, the efficacy appeared to be similar between the anti-TNF-α agent and interferon in BU patients. The rates of adverse events were comparable between a variety of different therapeutic controls. Serious adverse events were not observed in 53.8% (7/13) of the studies.

Conclusions: Compared with TIS therapy, anti-TNF-a therapy reduces the relapse of uveitis in patients with BD. However, the evidence regarding anti-TNF-α therapy is very limited for the full spectrum of BD subtypes, which calls for caution.

Characterization of autologous platelet rich plasma (PRP) and its biological effects in patients with Behçet's Disease

INTRODUCTION

Behçet's disease (BD) is an immune-mediated chronic systemic vasculitis, characterized by clinical manifestations that include: mucocutaneous ulcers, ocular involvement, immunological alterations, vascular and neurological implications. The available treatments present limitations such as high cost and side effects, and the search for a low-cost biological treatment with immunomodulatory potential becomes of great value. Platelet rich plasma (PRP) has some characteristics that indicate a possible use as an immunomodulator due to the wide range of secreted cytokines, especially through the participation of TGF-β1 in the differentiation of T regulatory cells (Treg). This study aimed to characterize the PRP poor in leukocytes (P-PRP) of patients with BD and active ulcers and to evaluate its effects as an immunomodulator through a subcutaneous application.

METHODS

We selected patients with a diagnosis of BD, with a low dose of prednisone and with no central nervous system or ocular involvement. Platelet and leukocyte count and quantification of 17 cytokines were evaluated in P-PRP. The effects of P-PRP were evaluated by cell frequency of TCD4 +, TCD8 +, Treg, natural killer (NK), and activated NK, as well as by the cytokine profile in patient's plasma, and the clinical manifestations through score and questionnaire. Also, it was evaluated the number and timing of oral ulcer closure. PRP was used as an adjuvant, with 9 applications of 3 mL, over 6 months, with a follow-up of one year.

RESULTS

The results using PRP showed adequate values and no significant inter-and intra-individual variations. The systemic evaluations during the use of PRP showed significant alterations, characterized by the increase in Treg cell frequency (p = 0.0416) and a decrease in activated NK cells (p = 0.0010). However, no clinical correlation was observed through score analysis. The most relevant clinical data was the decrease in the closing time of ulcers throughout the application period.

CONCLUSION

In a pilot study with BD patients, P-PRP promoted an anti-inflammatory profile characterized by increased Treg cells and decreased activated NK cells and alterations in cytokines. A clinical improvement was observed with a decrease in the number and time of closure of oral ulcers.

Genetics of Behçet's Disease: Functional Genetic Analysis and Estimating Disease Heritability

Behçet's disease is a chronic multisystemic inflammatory disorder characterized by recurrent oral and genital ulcers. Although its etiology remains unclear, it is thought that both genetic and environmental factors contribute to the onset and progression of Behçet's disease. Here, we provide an updated view of the genetic landscape and architecture of Behçet's disease. Large-scale genetic studies performed to date revealed 21 genetic susceptibility loci associated with the disease at a GWAS level of significance (p-value = 5 × 10⁻⁸). We performed epigenetic pattern enrichment analysis in Behçet's disease associated loci, providing new insights into the molecular mechanisms underlying its pathophysiology. Our data suggest the crucial involvement of several immune cell types, including natural killer cells, monocytes, and B cells in the pathogenesis of the disease. Pathway enrichment analysis identified important biological processes involved. Using large-scale genetic data available from ~200 immune-related loci (Immunochip), we estimate Behçet's disease heritability to be at least 16%. We further used the same approach to estimate the heritability explained by the known Behçet's disease-associated loci, suggesting that they explain ~ 60% of the genetic component underlying Behçet's disease. These results indicate a significant role of non-genetic factors in causing Behçet's disease and that additional genetic variation influencing the risk of Behçet's disease remains to be identified. Finally, we calculated a cumulative genetic risk score across populations reinforcing the link between geographic variations in disease prevalence with its genetic component.

Neutrophil Extracellular Traps Promote Aberrant Macrophages Activation in Behçet's Disease

Neutrophil extracellular traps (NETs) are upregulated and promote thrombosis in Behçet's disease (BD). However, whether NETs promote autoinflammation in BD remains unclear. This study aimed to investigate the potential role of NETs in promoting macrophage activation in BD. Firstly, we quantified NETs by measuring double-stranded DNA (dsDNA) using PicoGreen and calculating the proportion of NETosis. Then macrophages were stimulated with BD- or healthy controls (HC)-derived NETs, and IL-8 and TNF-α production and IFN-γ⁺ CD4⁺ T cells differentiation were measured using ELISA and flow cytometry, respectively. The protein components in NETs were analyzed by western blot. Macrophages were stimulated with Histone H4 neutralized NETs, and IL-8 and TNF-α production were measured using ELISA. The level of 8-hydroxydeoxyguanosine (8-OHdG) DNA in NETs was measured using ELISA. The levels of reactive oxygen species (ROS) in serum and neutrophils were measured using ROS probes by a microplate reader and flow cytometry. We found that circulating NETs and neutrophil-derived NETs were significantly higher in BD than HC. BD NETs stimulated macrophages produced higher levels of IL-8 and TNF-α, and promoted IFN-γ⁺ CD4⁺ T cells differentiation. BD NETs were enriched in Histone H4, and neutralizing Histone H4 abrogated the BD NETs-mediated IL-8 production by macrophages, but not TNF-α. Also, BD neutrophils produced more 8-OHdG DNA than HC neutrophils, and the percentage of 8-OHdG DNA in dsDNA from BD neutrophils was also higher than that of HC neutrophils. The ROS levels in serum and neutrophils were both higher in BD than HC. Our findings suggested that excessive BD NETs promoted macrophages activation and facilitated IFN-γ⁺ CD4⁺ T cells differentiation. Higher levels of Histone H4 and oxidized DNA in BD NETs might mediate macrophages hyperactivation.

Dysregulation of glycerophospholipid metabolism during Behçet's disease contributes to a pro-inflammatory phenotype of circulating monocytes

Behçet's disease (BD) is a relapsing, multisystem and inflammatory condition characterized by systemic vasculitis of small and large vessels. Although the etiopathogenesis of BD remains unknown, immune-mediated mechanisms play a major role in the development of the disease. BD patients present leukocyte infiltration in the mucocutaneous lesions as well as neutrophil hyperactivation. In contrast to neutrophils, whose involvement in the pathogenesis of BD has been extensively studied, the biology of monocytes during BD is less well known. In this study, we analyzed the phenotype and function of circulating monocytes of 38 BD patients from Hospital of Braga. In addition, we evaluated the impact of inflammatory and metabolomic plasma environment on monocyte biology. We observed a worsening of mitochondrial function, with lower mitochondrial mass and increased ROS production, on circulating monocytes of BD patients. Incubation of monocytes from healthy donors with the plasma of BD patients mimicked the observed phenotype, strongly suggesting the involvement of serum mediators. BD patients, regardless of their symptoms, had higher serum pro-inflammatory TNF-α and IP-10 levels and IL-1β/IL-1RA ratio. Untargeted metabolomic analysis identified a dysregulation of glycerophospholipid metabolism on BD patients, where a significant reduction of phospholipids was observed concomitantly with an increase of lysophospholipids and fatty acids. These observations converged to an enhanced phospholipase A2 (PLA2) activation. Indeed, inhibition of PLA2 with dexamethasone or the downstream cyclooxygenase (COX) enzyme with ibuprofen was able to significantly revert the mitochondrial dysfunction observed on monocytes of BD patients. Our results show that the plasma inflammatory environment coupled with a dysregulation of glycerophospholipid metabolism in BD patients contribute to a dysfunction of circulating monocytes.

Effect of combined colchicine-corticosteroid treatment on neutrophil/lymphocyte ratio: a predictive marker in Behçet disease activity

BACKGROUND AND AIMS

Behçet's disease (BD) is an auto-immune vasculitis, characterized by episodic inflammation of multiple organs. The neutrophil to lymphocyte ratio (NLR) is used as a marker of inflammation in several diseases nowadays. While nitric oxide (NO) seem to be involved in BD pathogenicity. Our study aims to investigate the NLR as an inflammatory marker of BD activity as well as to evaluate the relationship between the NO production and NLR in Algerian BD patients with different clinical manifestations before and under colchicine + corticosteroid treatment.

METHODS

For this purpose, we evaluated the NLR as the ratio of neutrophil count to lymphocyte count in naïve and treated active BD patients with different clinical manifestations and in inactive ones. Furthermore, we assessed NO production by the Griess' method in the same patients. Additionally, we evaluated in vivo interferon-γ (IFN-γ) and interleukin-4 (IL-4) levels using ELISA.

RESULTS AND DISCUSSION

Our results indicate that the NLR and nitrite levels were higher in naïve active BD patients. Interestingly, this high ratio and NO production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Importantly, in treated BD patients NLR was higher in active patients especially in those with mucocutaneous involvement while increased nitrites levels were regardless of the clinical manifestations studied. Both NLR and NO production decreased in these treated active patients. In addition, IL-4 production differed according to the clinical manifestations studied contrary to the IFN-γ production.

CONCLUSION

Collectively our results suggest that the NLR is a potential marker of BD activity in Algerian patients, predicting the disease severity. Moreover, the positive relationship between the NLR and NO production is related to an increased risk of mucocutaneous lesions and vascular involvement. Thus, the application of these two accessible tools could be benefit for the clinical prognosis and treatment of BD.

Enhanced NLRP3 and DEFA1B Expression During the Active Stage of Parenchymal Neuro-Behçet's Disease

BACKGROUND/AIM

Neurological symptoms (neuro-Behçet's disease; NBD) occur in a fraction of Behçet's disease (BD) patients and often present with parenchymal brain lesions and clinical exacerbations. Our aim was to identify genes associated with attack and remission periods of NBD.

MATERIALS AND METHODS

Microarray analysis was performed using peripheral blood mononuclear cell (PBMC) samples obtained during attack and remission periods of five NBD patients. Expression levels of the most significantly up-regulated genes were measured with real-time PCR using PBMC samples of 15 NBD patients and 20 healthy controls.

RESULTS

During NBD attacks, the most remarkably up-regulated genes were defensin alpha 1B (DEFA1B) and NLR family, pyrin domain containing 3 (NLRP3). Real time PCR studies showed significantly increased DEFA1B and NLRP3 expression levels during attacks.

CONCLUSION

Immunological factors showing the most significant increase in expression during NBD attacks were primarily associated with innate immunity functions. DEFA1B and NLRP3 can be used as biomarkers for estimation of disease activity in NBD.

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

OBJECTIVES

Behçet's disease (BD) is a chronic systemic vasculitis. Thrombosis is a frequent and life-threatening complication. The pathogenesis of BD is poorly understood and evidence supporting a role for primed neutrophils in BD-associated thrombotic risk is scant. To respond to inflammatory insults, neutrophils release web-like structures, known as neutrophil extracellular traps (NETs), which are prothrombotic. We evaluated the role of NETs and markers of NETs in BD.

METHODS

Blood samples were collected from patients with BD, according to the International Study Group Criteria for Behçet's disease, and healthy donors (HD). NET components, including cell-free DNA (CfDNA) and neutrophil enzymes myeloperoxidase (MPO), were assessed in serum or in purified neutrophils from patients with BD and HD.

RESULTS

Patients with active BD had elevated serum cfDNA levels and MPO-DNA complexes compared with patients with inactive BD and to HD. In addition, levels of cfDNA and MPO-DNA complexes were significantly higher in patients with BD with vascular involvement compared with those without vascular symptoms. Purified neutrophils from patients with BD exhibited spontaneous NETosis compared with HD. Thrombin generation in BD plasma was significantly increased and positively correlated with the levels of MPO-DNA complexes and cfDNA. Importantly, DNAse treatment significantly decreased thrombin generation in BD plasma but not in HD plasma. In addition, biopsy materials obtained from patients with BD showed NETs production in areas of vasculitic inflammation and thrombosis.

CONCLUSIONS

Our data show that NETs and markers of NETS levels are elevated in patients with BD and contribute to the procoagulant state. Targeting NETs may represent a potential therapeutic target for the reduction or prevention of BD-associated thrombotic risk.

Immunopathogenesis of Behcet's Disease

Behcet's disease (BD) is a chronic systemic inflammatory vasculitis of unknown etiology characterized by recurrent episodes of oral aphthous ulcers, genital ulcers, skin lesions, ocular lesions, and other manifestations. Although the pathogenesis of BD is unclear, some studies have shown that immunological aberrations play an important role in the development and progression of BD. Infection-related trigger factors, including antigens and autoantigens, are believed to mediate the development of BD in patients with a genetic predisposition and subsequently activate the innate and adaptive immune systems, resulting in the production of numerous cytokines and chemokines to combat the infection-related factors. The study of the immunological mechanism of BD paves the way for the development of innovative therapies. Recently, novel biotherapy approaches, including interferon-α (IFN-α), tumor necrosis factor-α (TNF-α) antagonists, and other agents that target interleukins and their receptors, have shown promising results in the treatment of patients with refractory BD and have improved the prognosis of BD. In this review, we provide the current concepts of BD immunopathogenesis.

Gene Expression Profiling in Behcet's Disease Indicates an Autoimmune Component in the Pathogenesis of the Disease and Opens New Avenues for Targeted Therapy

Behçet disease (BD) is a chronic inflammatory multisystem disease characterized by oral and genital ulcers, uveitis, and skin lesions. Disease etiopathogenesis is still unclear. We aim to elucidate some aspects of BD pathogenesis and to identify specific gene signatures in peripheral blood cells (PBCs) of patients with active disease using novel gene expression and network analysis. 179 genes were modulated in 10 PBCs of BD patients when compared to 10 healthy donors. Among differentially expressed genes the top enriched gene function was immune response, characterized by upregulation of Th17-related genes and type I interferon- (IFN-) inducible genes. Th17 polarization was confirmed by FACS analysis. The transcriptome identified gene classes (vascular damage, blood coagulation, and inflammation) involved in the pathogenesis of the typical features of BD. Following network analysis, the resulting interactome showed 5 highly connected regions (clusters) enriched in T and B cell activation pathways and 2 clusters enriched in type I IFN, JAK/STAT, and TLR signaling pathways, all implicated in autoimmune diseases. We report here the first combined analysis of the transcriptome and interactome in PBCs of BD patients in the active stage of disease. This approach generates useful insights in disease pathogenesis and suggests an autoimmune component in the origin of BD.

Influence of corticosteroid therapy on IL-18 and nitric oxide production during Behçet's disease

BACKGROUND AND AIMS

Behçet's disease (BD) is a chronic multisystemic inflammatory disease with complex etiopathogenesis. Th1-proinflammatory cytokines seem to be involved in its pathogenesis. Our current study aims to evaluate interleukin-18 (IL-18) and nitric oxide (NO) involvement in the development of different clinical manifestations of BD as well as to investigate the corticosteroid therapy effect on this production in Algerian patients.

METHODS

For this purpose, we evaluated in vivo and ex vivo IL-18, interferon-γ (IFN-γ) levels using ELISA and NO production by the Griess' method in naïve-active and corticosteroid-treated BD patients with different clinical manifestations. Additionally, we assessed CD40/CD40L expression by flow cytometrics assay in these groups of patients.

RESULTS AND DISCUSSION

Our results indicate that IL-18 and nitrite levels were higher in naïve-active BD patients. Interestingly, this high production differed according to the clinical manifestations and was associated with an increased risk of mucocutaneous and vascular involvement. Concerning corticosteroid treated-active BD patients, no difference was observed in this production between each clinical subgroup. However, IFN-γ levels increased in all categories of active patients. Interestingly, corticosteroid therapy reduced significantly these inflammatory mediators regardless of the clinical manifestations studied. In addition, the CD40/CD40L expression differed according to the clinical presentations.

CONCLUSION

Collectively, our results suggest that concomitant high production of IL-18 and NO in naïve-active BD patients is related to an increased risk of mucocutaneous lesions and vascular involvement. Moreover, the relationship between these two inflammatory markers could constitute a predictable tool of BD clinical presentations and an early factor of therapy efficiency.

Serum PLR and LMR in Behçet's disease: Can they show the disease activity?

The aim of this study is to determine platelet to lymphocyte ratio (PLR) and lymphocytes to monocytes ratio (LMR) levels in Behçet's disease (BD) and to investigate their relationships with disease activity.Hematological and inflammatory parameters including high-sensitivity C-reactive proteins (hs-CRP), erythrocyte sedimentation rate (ESR), PLR, and LMR were examined in BD and healthy controls.Data from 140 patients with BD (108 with active and 32 with inactive disease) and 107 controls were enrolled. PLR (153.21 ± 65.44, 106.20 ± 28.91, P <.001, respectively) was remarkably higher, whereas LMR (5.37 ± 5.47, 8.95 ± 5.84, P <.001, respectively) was significantly lower in BD than in controls. Active BD patients had significantly higher PLR (159.20 vs 131.14, P = .037), ESR (38.30 vs 24.55, P = .017), and hs-CRP (30.20 vs 17.21, P = .027) than those with inactive BD. However, no significant difference in LMR was found between the groups. Moreover, PLR was positively correlated with BDCAF (r = 0.193, P <.05), hs-CRP (r = 0.402, P <.01), and ESR (r = 0.284, P <.01), whereas LMR was negatively correlated with BDCAF (r = -0.175, P <.05), hs-CPR (r = -0.263, P <.01), and ESR (r = -0.175, P <.05). Additionally, both PLR and LMR were shown to be independent factors for BD by multivariate logistic regression analysis. Furthermore, a PLR level of 124.63 was determined as the best cut-off value by ROC analysis (sensitivity 64.3%, specificity 78.0%, and the area under the ROC curve 0. 753).PLR was elevated in active BD as compared to inactive BD. PLR may be a reliable, cost-effective, and novel potential parameter to help evaluate disease activity in BD.

Natural Killer Cell Subsets and Their Functional Activity in Behçet's Disease

BACKGROUND

Behçet's disease (BD) is a rare, chronic autoinflammatory disorder of unknown origin. Natural killer (NK) cells are one of the major immunoregulatory cell groups of the innate immune system, but their role in BD pathogenesis is not well documented.

OBJECTIVES

We aimed to investigate the role of NK cell subsets and their cytokine secretion and cytotoxic activity in patients with BD.

PATIENTS AND METHODS

The study group consisted of BD patients who had only mucocutaneous involvement, and they were compared with healthy subjects. BD patients were divided into two groups according to their frequencies of oral ulcerations. NK cell cytotoxicity was determined using CD107a expression and a CFSE-based cytotoxicity test. Expression of NK cell receptors and surface markers and the intracellular IL-5, IL-10, IL-17, and IFN-γ levels in CD16⁺ NK cells were assessed by flow cytometry.

RESULTS

Although the cytokine secretion pattern was different, no difference was obtained in cytotoxic activity, expression of activatory receptors, or degranulation of NK cells.

CONCLUSION

Increases in NK1/NK2 ratio and CD16⁺IFN-γ⁺ NK1 cells might support the idea of a biased IFN-γ dominant immune response in the mucocutaneous involvement of BD pathogenesis. Although the cytokine secretion pattern was different, no difference was obtained in cytotoxic activity, expression of activatory receptors, or degranulation of NK cells.

The Role of IFN-alpha in Experimental and Clinical Uveitis

PURPOSE

IFN-α is the only treatment capable of inducing long-term remission in some patients with ocular Behçet's disease. In this review, we focus on immune mechanisms of IFN-α in animal models and patients and compare the outcome of different clinical studies.

METHODS

Review of literature using PubMed and Google and original data from rat models with monophasic/chronic or relapsing experimental autoimmune uveitis treated with IFN-α.

RESULTS

The role of IFN-α and its effect on various cell types were investigated, in some cases with contradictory results. Some patients respond very well to IFN-α treatment, while others are non-responders, which was reflected in the uveitis rat models: relapsing uveitis was ameliorated, the monophasic/chronic disease even aggravated.

CONCLUSIONS

Despite intensive investigations in patients and animal models, the immune mechanisms explaining the therapeutic effect of IFN-α in ocular Behçet's disease are not yet fully understood and need further investigation.

The IL-8 Gene Polymorphisms in Behçet's Disease Observed in Denizli Province of Turkey

Behçet's disease is a multisystemic inflammatory disorder as a triad of symptoms including recurrent oral and genital aphthous ulceration and uveitis with unknown pathogenesis. IL-8, a proinflammatory cytokine, has been found increased in the active stage of BD. DNA samples were obtained from 88 patients with BD and 112 healthy control subjects in Denizli province of Turkey. All genotyping experiments of SNPs in IL-8 gene were performed using polymerase chain reaction-restriction fragment polymorphism. We found that IL-8 -845 T > C and -738 T > A sites are non-polymorphic. There were no differences in the polymorphisms of IL-8 +396 G/T, +781 C/T, and +1633 C/T sites except IL-8 -251 T > A in between patients and healthy controls. Analysis of IL-8 polymorphisms indicates that the distribution of frequencies seems to be associated with -251 T > A and gender, -251 T > A and erythema nodosum, -251 T > A and ocular involvement, +781 C > T and erythema nodosum, +396 G > T and pathergy positivity, and +1633 C > T and papulopustular lesion. We demonstrated that the frequencies of IL-8 haplotypes were significantly different with BD patients than control group. We found that the distribution of IL-8 haplotypes was significantly different with genital ulcers, ocular involvement, positive pathergy test, erythema nodosum, papulopustular lesions, and arthritis with BD patients than healthy control individuals. Our study suggests that IL-8 gene polymorphisms may affect susceptibility to BD and increase the risk of developing disease. In order to confirm and assess the association of IL-8 and other cytokine gene polymorphisms in the pathophysiology of BD, large cohort studies are needed.

Modulation of endothelial function by Toll like receptors

Endothelial cells (EC) are able to actively control vascular permeability, coagulation, blood pressure and angiogenesis. Most recently, a role for endothelial cells in the immune response has been described. Therefore, the endothelium has a dual role controlling homeostasis but also being the first line for host defence and tissue damage repair thanks to its ability to mount an inflammatory response. Endothelial cells have been shown to express pattern-recognition receptors (PRR) including Toll-like receptors (TLR) that are activated in response to stimuli within the bloodstream including pathogens and damage signals. TLRs are strategic mediators of the immune response in endothelial cells but they also regulate the angiogenic process critical for tissue repair. Nevertheless, endothelial activation and angiogenesis can contribute to some pathologies. Thus, inappropriate endothelial activation, also known as endothelial dysfunction, through TLRs contributes to tissue damage during autoimmune and inflammatory diseases such as atherosclerosis, hypertension, ischemia and diabetes associated cardiovascular diseases. Also TLR induced angiogenesis is required for the growth of some tumors, atherosclerosis and rheumatoid arthritis, among others. In this review we discuss the importance of various TLRs in modulating the activation of endothelial cells and their importance in immunity to infection and vascular disease as well as their potential as therapeutic targets.

Comparison between Outcomes of Vitrectomy in Granulomatous and Nongranulomatous Uveitis

Purpose: The aim of this study was to compare the outcomes of vitrectomy in granulomatous uveitis and nongranulomatous uveitis insufficiently managed by immunosuppressive therapy. Methods: Thirty-eight eyes with granulomatous uveitis and 17 eyes with nongranulomatous uveitis that underwent vitrectomy for ocular complications between July 2006 and August 2012 were reviewed retrospectively. Visual acuity and ocular inflammation scores before and 6 months after surgery were compared. Patients treated with vitrectomy alone and those in whom vitrectomy was combined with phacoemulsification were analyzed separately. Results: The mean visual acuity improved significantly both in granulomatous and nongranulomatous uveitis. In granulomatous uveitis, the mean inflammation scores decreased significantly both in the anterior segment and in the posterior segment. In nongranulomatous uveitis, the mean inflammation score in the posterior segment decreased significantly, although it did not change in the anterior segment. Conclusion: Vitrectomy was effective for treating ocular complications both in granulomatous uveitis and nongranulomatous uveitis, with favorable outcomes of improved visual acuity and decreased uveitis activity.

Gamma Delta (γδ) T Cells and Their Involvement in Behçet's Disease

Behçet's disease (BD) is a multisystem inflammatory disorder characterized by orogenital ulcerations, ocular manifestations, arthritis, and vasculitis. The disease follows a relapsing-remitting course and its pathogenesis is unknown. Genetic predisposition and immune-dysregulation involving gamma delta (γδ) T cells are reported to have a role. γδ T cells are atypical T cells, which represent a small proportion of total lymphocytes. They have features of both innate and adaptive immunity and express characteristics of conventional T cells, natural killer cells, and myeloid antigen presenting cells. These unconventional T cells are found in the inflammatory BD lesions and have been suggested to be responsible for inducing and/or maintaining the proinflammatory environment characteristic of the disease. Over the last 20 years there has been much interest in the role of γδ T cells in BD. We review the literature and discuss the roles that γδ T cells may play in BD pathogenesis.

Pegylated interferon-α-2b reduces corticosteroid requirement in patients with Behçet's disease with upregulation of circulating regulatory T cells and reduction of Th17

OBJECTIVE

To determine whether the addition of 26 weeks of subcutaneous peginterferon-α-2b could reduce the requirement for systemic corticosteroids and conventional immunosuppressive medication in patients with Behçet's disease (BD).

METHODS

We conducted a multicentre randomised trial in patients with BD requiring systemic therapy. Patients were randomised to 26 weeks of peginterferon-α-2b in addition to their standard care or to standard care only and followed 6-monthly for 3 years with BD activity scores and quality of life questionnaires. Patients at one centre had blood taken to measure regulatory T cells (Tregs) and Th17 cells.

RESULTS

72 patients were included. At months 10-12, while among the entire patient population there was no difference in the corticosteroid dose or immunosuppression use between the treatment groups (adjusted OR 1.04, 95% CI 0.34 to 3.19), post hoc analysis revealed that in patients who were on corticosteroids at baseline the corticosteroid requirement was significantly lower in the peginterferon-α-2b (6.5 (5-15) mg/day) compared with the non-interferon group (10 (8.25-16.5) mg/day, p=0.039). Furthermore, there was a trend towards an improved quality of life that became significant by 36 months (p=0.008). This was associated with a significant rise in Tregs and a decrease in Th17 cells which was still present at 1 year and 6 months after the interferon was stopped. The safety profile was similar with adverse events in 10% in both groups.

CONCLUSIONS

The addition of peginterferon-α-2b to the drug regime of BD patients did not significantly reduce their corticosteroid dose required at 1 year. However, in those on corticosteroids at baseline post hoc analysis demonstrated that the addition of peginterferon-α-2b did result in a significant reduction in corticosteroid dose with a significantly improved quality of life and trend to reduce other required immunosuppressive agents. This effect was seen at 1 year and associated with a rise in Tregs suggesting a possible mode for interferon action.

TRIAL REGISTRATION NUMBER

ISRCTN 36354474; EudraCT 2004-004301-18.

Cytokines Modulate the "Immune-Metabolism" Interactions during Behçet Disease: Effect on Arginine Metabolism

Aim and Methods. In this study, we evaluated NOS and arginase activities and their regulation during Behçet disease, a systemic chronic inflammatory disorder with uncertain etiology. The peripheral blood mononuclear cells of 36 patients and 15 control samples (PBMC) were cultured in either RPMI 1640, MEM, or DMEM complemented with 10% of FBS and antibiotics. Cultures were performed with or without the control or patients plasma. Subsequent treatment contained anticytokines (IL-6, TGF-β), a mitogenic effector (PHA), or NOS modulators (L-NMMA, BH4). Culture supernatants were harvested after 24 h of incubation. NO and urea measurements were, respectively, performed by modified Griess and Berthelot methods. Results. Higher urea levels were found in patients' plasma compared to the control's (P < 0.05). NOS modulators induced inverted production profiles for NO and urea (P < 0.05). Their results differed depending on the clinical findings (P < 0.05). It was also found that cytokine neutralization induced different response profiles in patients as opposed to control cultures (P < 0.05). Conclusion. Our results suggest that arginases can compete with NOS2 for L-arginine during Behçet disease. Both enzymes are regulated by environmental cytokines and substrate availability. Furthermore, it seems that NOS/arginase balance is dependent on clinical expression.