BackgroundStudies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.MethodsNeutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H2O2/O2 − production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.ResultssCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H2O2/O2 − were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4+ T cells from patients with BD showed higher CD40L expression.ConclusionsPlasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.

Background: Complement component 4 (C4) gene copy number (GCN) affects the susceptibility to systemic lupus erythematosus (SLE) in different populations, however the possible phenotype significance remains to be determined. This study aimed to associate C4A, C4B and total C4 GCN and SLE, focusing on the clinical phenotype and disease progression. Methods: C4, C4A and C4B GCN were determined by real-time PCR in 427 SLE patients and 301 healthy controls, which underwent a detailed clinical evaluation according to a pre-established protocol. Results: The risk of developing SLE was 2.62 times higher in subjects with low total C4 GCN (< 4 copies, OR = 2.62, CI = 1.77 to 3.87, p < 0.001) and 3.59 times higher in subjects with low C4A GCN (< 2 copies; OR = 3.59, CI = 2.15 to 5.99, p < 0.001) compared to those subjects with normal or high GCN of total C4 (≥4) and C4A (≥2), respectively. An increased risk was also observed regarding low C4B GCN, albeit to a lesser degree (OR = 1.46, CI = 1.03 to 2.08, p = 0.03). Furthermore, subjects with low C4A GCN had higher permanent disease damage as assessed by the Systemic Lupus International Collaborating Clinics-Damage Index (SLICC-DI; median = 1.5, 95% CI = 1.2-1.9) than patients with normal or high copy number of C4A (median = 1.0, 95% CI = 0.8-1.1; p = 0.004). There was a negative association between low C4A GCN and serositis (p = 0.02) as well as between low C4B GCN and arthritis (p = 0.02). Conclusions: This study confirms the association between low C4 GCN and SLE susceptibility, and originally demonstrates an association between low C4A GCN and disease severity.

We evaluated the possible association between FCGR3A V/F (158) polymorphism and SLE susceptibility and clinical phenotype in 305 sequentially retrieved SLE patients and 300 healthy controls from the southeastern part of Brazil by allele-specific polymerase chain reaction. Our results showed no association between FCGR3A 158V/F alleles and susceptibility to SLE in this series of patients albeit the heterozygous genotype was strongly associated with the disease.

Susceptibility to systemic lupus erythematosus was associated with the FCGR3B*01 allele, as well as with the FCGR3B*01/*01 and FCGR3B*01/*02 genotypes. No association was found between FCGR3B genotypes and clinical manifestations, disease severity or the presence of autoantibodies.

Background FCGR3B gene encoding the receptor FcγRIIIb has three polymorphic forms (FCGR3B*01, FCGR3B*02 and FCGR3B*03) which represent the human neutrophil antigens HNA-1a, -1b and -1c, respectively. It has been postulated that variants of these alleles might represent new FCGR3B alleles, however there are few studies assessing the frequency of such variants in different populations. In this study we performed an analysis of the frequency of the FCGR3B alleles and its variant forms examining the polymorphic region of the FCGR3B gene in a large Brazilian population sample including healthy blood donors and patients with systemic lupus erythematosus (SLE). Study Design and Methods A segment containing the polymorphic nucleotide positions 141, 147, 227, 266 and 277 in exon 3 was sequenced from genomic DNA of 615 individuals including 310 blood donors and 305 patients with SLE. Additionally, nucleotide databases were screened for variant FCGR3B sequences. Results The allele frequencies for FCGR3B*01, FCGR3B*02 and FCGR3B*03 were 0.37, 0.59 and 0.04, respectively. In two patients with SLE (0.3%) there was no gene amplification characterizing the FCGR3B-null phenotype. Considering the 5 FCGR3B polymorphic sites, 4 variant forms were observed. One variant was linked to the FCGR3B*01 allele with SNPs occurring simultaneously in two positions: A227G and G277A (n=2; 0.3%). The other three variants, linked to the FCGR3B*02 allele were: A277G (n=8; 1.3%); C141G (n=3; 0.5%); and T147C (n=1; 0.2%). All mutations observed were missenses. The results are summarized in the Table. In 103/613 (16.8%) sequenced individuals we found 19 SNPs on 14 polymorphic sites distinct from those which characterize the FCGR3B alleles. Among the most frequent, T230A was observed in 36 cases (5.9%), T230G in 20 cases (3.3%), G249A in 6 cases (1%) and C337A in 6 cases (1%), all shown as heterozygous. The comparative analysis between the two groups of individuals revealed an association between the presence of the allele FCGR3B*01 and the HNA-1a/a and HNA-1a/b genotypes with increased susceptibility to SLE (p <0.001; p = 0.028; and p = 0.012, respectively), however there was no significant correlation between these genotypes and disease severity. Discussion The observed frequencies of the FCGR3B*01, FCGR3B*02, and FCGR3B*03 alleles were similar to those reported by genotyping studies which included Europeans or North Americans individuals. The frequency of the null phenotype (0.3%) was similar to that reported by Europeans (0.2-0.8%). The variant FCGR3B*02A277G showed a frequency (1.3%) sufficiently high to be considered a new allele as proposed by the last Granulocyte Working Party/ISBT 2013. Interestingly, this variant was significantly more prevalent in patients with SLE than in blood donors (p=0.03). All the variants described in this study have been observed in different populations however we emphasize the presence of SNPs (T230A, T230G, G249A and C337A) in polymorphic sites different from those that characterize the FCGR3B gene alleles. We conclude that the FCGR3B gene is highly polymorphic and that the occurrence of new alleles must be considered, however the functional consequences of such changes has not yet been elucidated. Disclosures: No relevant conflicts of interest to declare.