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Background: Behçet's disease (BD) is an auto-inflammatory vasculitis characterized by aphthous oro-genital ulcers, inflammatory skin changes and uveitis. Treatment is mainly immunosuppressive. Interestingly, elevated endotheline-1 (ET-1) levels suggest a possible beneficial effect of treatment with an ET-1 receptor antagonist., Objective: The aim of our study was to investigate the possible beneficial effect of the ET-1 inhibitor bosentan., Methods: We performed a prospective double-blind placebo controlled pilot study into the effect and safety of bosentan in BD patients. Disease activity was measured using the Behçet Disease Current Activity Form. The primary objective of the study was to determine whether bosentan is therapeutically effective in patients with BD. Secondary endpoints were safety, tapering of medication and the effect of bosentan on possible disease activity markers such as ET-1, circulating endothelial cells (CECs), soluble interleukin-2 receptor (sIL2R) and cytokine levels., Results: Ten patients were randomized to either bosentan or placebo. Overall, no effect on disease activity was observed, although one patient responded clinically and continued treatment after the study period. Despite one SAE, bosentan seems safe to use. No effect on tapering of medication, CECs, sIL2R and cytokine levels was found. In the bosentan group, ET-1 levels were elevated during the treatment period, with no correlation with disease activity., Conclusions: Although this is a small pilot study, bosentan appears to be safe in BD patients. One patient had a durable and significant clinical response. Our observations should be confirmed and extended in a larger patient cohort to be of significant impact in the treatment options for BD.

Objectives: The aim of this study is to investigate the cumulative incidence and the severity of COVID-19 infections in patients with Behçet's disease., Methods: A retrospective cohort study of patients with Behçet's disease was conducted. We obtained the data systematically from electronic patient files and through telephone interviews between February 2020 and May 1, 2021. Main outcomes were COVID-19 infection, disease duration, hospitalisation, intensive care admission and mortality. Secondary outcome was adherence to quarantine measures as recommended by the government., Results: 185 Behçet's disease patients were included (mean age 42.2 years, 54% female); 58% of the patients were receiving colchicine, 30% anti-TNFα, 16% azathioprine and 8% systemic steroids. 30 patients (16.2%) were positive for COVID-19. Within our cohort, the cumulative incidence of COVID-19 was therefore 16.2% (95% CI 11.2-22.3%), which is significantly increased when compared to the general Dutch population (8.7% (95% CI 8.72-8.73%)) (p < 0.001). Four out of 30 (13%) patients were admitted to the hospital. There was no COVID-19 related mortality observed. Patients adhered to government measures; except in the period between the 1st of June and the 28th of September, this cohort received more visitors than in period 1 and 3., Conclusions: In this cohort, Behçet's disease patients have a higher risk for COVID-19 infection, without an increase of virus-related mortality. The course of COVID-19 disease in this cohort is relatively mild, with a lower admission rate than expected of patients using immunosuppressive medication.

Purpose: To compare quantitative optical coherence tomography angiography (OCT-A) measurements of the parafoveal microvasculature in retinal capillary plexuses among Behҫet uveitis (BU) patients, non-ocular Behҫet's disease (NOBD) patients, and healthy volunteers (HVs)., Methods: Sixty-eight subjects were enrolled in this prospective observational cross-sectional study. OCT-A imaging was performed using the Heidelberg Engineering Spectralis OCT. A custom algorithm was developed to calculate the vessel density (VD) in three retinal vascular layers: deep capillary plexus, intermediate capillary plexus, and superficial vascular plexus. The foveal avascular zone (FAZ) and acircularity index were calculated for the whole retinal vascular complex., Results: We analyzed one eye from 21 BU patients (age, 51 ± 10 years), 23 NOBD patients (age, 48 ± 14 years), and 22 HVs (age, 44 ± 13 years). One-way multivariate analysis of covariance showed a statistically significant difference in VD among the three groups when combining the layers after controlling for scan quality (P < 0.001). The VD was lowest in the BU group and highest in the HV group in all layers. The FAZ area was also statistically significant different among the groups (P < 0.005), with the largest FAZ areas in BU patients and smallest FAZ areas in the HV group. However, no statistically significant difference was found for the acircularity index., Conclusions: The parafoveal microvasculature is affected not only in BU patients but also in NOBD patients. Most deviations in the retinal microcirculation in Behҫet patients were found in the deeper layers of the retina by using the quantitative VD measurement.

Objectives: To investigate whether the auto-inflammatory nature and the pathergic reaction in Behçet's disease (BD) are driven by a disturbed toll-like receptor (TLR) response., Methods: We compared both TLR expression by flow-cytometry and TLR response by stimulation assay in 18 BD patients (both pathergy positive and pathergy negative) with 15 healthy controls., Results: Expression of TLR1 and 2 was significantly elevated in B-lymphocytes of BD patients compared with healthy controls. TLR1, 2 and 4 were significantly more highly expressed in both CD4+ and CD8+ T-lymphocytes of BD patients. Granulocytes of BD patients displayed significantly higher expression of TLR1, 2, 4 and 6. TLR2, 4 and 5 expression was significantly increased on classical monocytes of BD patients. Intermediate monocytes of BD patients showed an increase in expression of TLR2. Furthermore, TLR2 and 5 were significantly more highly expressed in non-classical monocytes of BD patients. In pathergy positive patients, TLR5 was even more highly expressed compared with pathergy negative patients on B- and T-lymphocytes and granulocytes. Furthermore, TLR2 and 5 showed an elevated TNF-α response to stimulation with their cognate ligands., Conclusion: Immune cells of BD patients overexpress TLR1, 2, 4, 5 and 6. Furthermore, after stimulation of TLR2 and 5, BD patients demonstrate a more potent TNF-α response. Although this is a small cohort, in the pathergy positive patients, TLR5 expression is even further augmented, suggesting that a microbial (flagellin) or damage (HMGB1) associated signal may trigger the exaggerated immune response that is characteristic for the pathergy phenomenon in BD. In conclusion, these results point to an exaggerated TLR response in the auto-inflammatory nature of BD., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Background: In Behçet's disease (BD), an auto-inflammatory vasculitis, an unbalanced gut microbiota can contribute to pro-inflammatory reactions. In separate studies, distinct pro- and anti-inflammatory bacteria associated with BD have been identified. Methods: To establish disease-associated determinants, we performed gut microbiome profiling in BD patients from the Netherlands ( n = 19) and Italy ( n = 13), matched healthy controls (HC) from the Netherlands ( n = 17) and Italy ( n = 15) and oral microbiome profiling in Dutch BD patients ( n = 18) and HC ( n = 15) by 16S rRNA gene sequencing. In addition, we used fecal IgA-SEQ analysis to identify specific IgA coated bacterial taxa in Dutch BD patients ( n = 13) and HC ( n = 8). Results: In BD stool samples alpha-diversity was conserved, whereas beta-diversity analysis showed no clustering based on disease, but a significant segregation by country of origin. Yet, a significant decrease of unclassified Barnesiellaceae and Lachnospira genera was associated with BD patients compared to HC. Subdivided by country, the Italian cohort displays a significant decrease of unclassified Barnesiellaceae and Lachnospira genera, in the Dutch cohort this decrease is only a trend. Increased IgA-coating of Bifidobacterium spp., Dorea spp. and Ruminococcus bromii species was found in stool from BD patients. Moreover, oral Dutch BD microbiome displayed increased abundance of Spirochaetaceae and Dethiosulfovibrionaceae families. Conclusions: BD patients show decreased fecal abundance of Barnesiellaceae and Lachnospira and increased oral abundance of Spirochaetaceae and Dethiosulfovibrionaceae . In addition, increased fecal IgA coating of Bifidobacterium, Ruminococcus bromii and Dorea may reflect retention of anti-inflammatory species and neutralization of pathosymbionts in BD, respectively. Additional studies are warranted to relate intestinal microbes with the significance of ethnicity, diet, medication and response with distinct pro- and inflammatory pathways in BD patients., (Copyright © 2020 van der Houwen, van Laar, Kappen, van Hagen, de Zoete, van Muijlwijk, Berbers, Fluit, Rogers, Groot, Hazelbag, Consolandi, Severgnini, Peano, D'Elios, Emmi and Leavis.)

Objectives: The TNF-blocker adalimumab can be effective in Behçet's disease (BD), a multisystem auto-inflammatory disorder. Unfortunately, the therapeutic efficacy of TNF-blockers can be hampered by the formation of anti-drug antibodies. We present an observational study of adalimumab in refractory BD with measurement of anti-drug antibodies., Methods: The effect of fortnightly 40mg adalimumab in nine patients with therapy refractory mucocutaneous, non-ocular or organ threatening BD was studied up to 60 months. Primary endpoint was a decrease in disease activity, measured by the BD Current Activity Form (BDCAF) within 6 months. Secondary endpoints included serum cytokines and the long-term formation of anti-adalimumab antibodies., Results: BDCAF improved significantly in all nine patients from 5.4 (SD=1.4) to 2.4 (SD=1.4) (p=0.007) within one month up to 6 months and after prolonged follow up of 5 years. All patients could either taper or stop concomitant therapy. Symptoms of mucocutaneous lesions, erythema nodosum and joint involvement decreased or disappeared. Serum TNF-alpha levels were elevates in five patients and decreased upon treatment (p=0.017). Adalimumab was save and none of the patients experienced therapy failure or antibodies against adalimumab., Conclusions: We present an observational study on patients with BD treated with adalimumab and provide a basis for long-term use in refractory mucocutaneous BD. These findings show that adalimumab can safely be administered yielding sustainable clinical effects in refractory BD patients with mucocutaneous disease without formation of anti-adalimumab antibodies, even after long follow up.

Objectives: Behçet's disease (BD), an auto-inflammatory vasculitis with oro-genital ulcerations, skin lesions and uveitis, is regarded as T cell mediated. A successful trial with rituximab suggests an additive role for B cells in the pathogenesis. Therefore, we studied B cell abnormalities in BD patients and the effect of TNF-blocking therapy., Methods: B cells in blood (n = 36) and tissue (n = 6) of BD patients were analysed with flow cytometry and/or immunohistochemistry and compared with healthy controls (n = 22). BD current activity form (BDCAF) in relation to B cell somatic hypermutations (SHMs) and immunoglobulin class-switching were studied., Results: Thirty-six patients (17 males) were included, mean age 44 years, average disease duration 10 years and mean BDCAF 2.7. Blood B cell numbers were significantly lower in patients than in controls (P = 0.0061), mostly due to decreased CD27 + memory B cells expressing IgM (P = 0.0001), IgG (P = 0.0002) and IgA (P = 0.0038) B cell subsets. CD27 + IgA + B cells showed the highest magnitude of decrease in active disease, measured with BDCAF (P = 0.02). CD27 + IgM + IgD + B cells were impaired in replication history (P = 0.0133) and selection of SHM, whereas IgA + B cells carried elevated SHM levels (P = 0.04) and lower IgA2 subclass usage (P = 0.0004) than controls. Immunohistochemistry revealed B cells in tissue of active mucosal ulcers. In adalimumab-treated patients, blood B cells were similar to controls., Conclusion: We show significant deviations in the memory B cell compartment, related to disease activity and therapeutic efficacy. Pronounced molecular impairments were seen in the fast-responding IgM + -memory and the mucosal IgA + -memory B cells. Because of the demonstrated abundance of B cells in affected tissue, we hypothesize relocation of memory B cells to the site of inflammation could account for the deviations found in blood of BD patients. These peripheral B cells are easily accessible as a marker to monitor therapeutic efficacy., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Introduction: The etiology of Behçet's disease (BD) is unknown, but widely considered an excessive T-cell mediated inflammatory response in a genetically susceptible host. Recent genome-wide association studies (GWAS) have shown limited number of novel loci-associations. The rarity and unequal distribution of the disease prevalence amongst different ethnic backgrounds have hampered the use of GWAS in cohorts of mixed ethnicity and sufficient sample size. However, novel statistical approaches have now enabled GWAS in admixed cohorts., Methods: We ran a GWAS on 336 BD cases and 5,843 controls. The cases consisted of Western Europeans, Middle Eastern and Turkish individuals. Participants from the Generation R study, a multiethnic birth cohort in Rotterdam, The Netherlands were used as controls. All samples were genotyped and data was combined. Linear regression models were corrected for population stratification using Genomic Principal Components and Linear Mixed Modelling. Meta-analysis was performed on selected results previously published., Results: We identified SNPs associated at genome-wide significant level mapping to the 6p21.33 (HLA) region. In addition to this known signal two potential novel associations on chromosomes 6 and 18 were identified, yet with low minor allele frequencies. Extended meta-analysis reveal a GWS association with the IL12A variant rs17810546 on chromosome 3., Discussion: We demonstrate that new statistical techniques enable GWAS analyses in a limited sized cohort of mixed ethnicity. After implementation, we confirmed the central role of the HLA region in the disease and identified new regions of interest. Moreover, we validated the association of a variant in the IL2A gene by meta-analysis with previous work. These findings enhance our knowledge of genetic associations and BD, and provide further justification for pursuing collective initiatives in genetic studies given the low prevalence of this and other rare diseases.

Objective: It has been shown previously that three nucleotide-binding oligomerization domain containing 2 (NOD2) variants (Arg702Trp, Gly908Arg and Lue1007fs) are associated with Crohn's disease (CD), a disorder clinically resembling Behçet's disease (BD). We studied the frequency of these variants in BD patients., Methods: DNA samples of 200 BD patients [59 Caucasians, 139 Middle Easterns (MEs) of Arab descent and 2 Asians] and 520 healthy controls (444 Caucasians and 76 MEs) were genotyped using a Taqman assay., Results: Both the Arg702Trp and Leu1007fs (frameshift) variants were significantly less frequently present among BD patients compared with healthy controls (0.5 vs 5.8%; P < 1.10(-5) and 0.0 vs 1.8%; P < 0.007, respectively). In the Caucasian subpopulation, Arg702Trp was significantly less frequent in the BD group as compared with the controls (P = 0.04); whereas in the ME subpopulation, a trend was observed (P < 0.06)., Conclusions: Of the three CD-associated single nucleotide polymorphisms, one of the variant NOD2 alleles, was found to be present significantly less in Caucasian BD patients.