Soluble CD40L is associated with increased oxidative burst and neutrophil extracellular trap release in Behçet’s disease

Abstract

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.

Neutrophils contribute to vasculitis by increased release of neutrophil extracellular traps in Behçet's disease

“…Few studies have addressed the role of NETosis in BD. In line with our results, a recent study by Perazzio et al showed that circulating neutrophils from active BD release more NETs than those from inactive BD and healthy controls [11]. In that study, the authors performed a multiplex screening of cytokines and soluble receptors and found a number of soluble factors increased in the serum of active BD patients compared to healthy controls.…”

“…Interestingly, IL8 a known chemo-attractant of neutrophils, was not significantly increased in the serum of active BD [11]. This points towards distinct cytokines acting in attracting neutrophils and inducing NETosis.…”

“…In that study, the authors performed a multiplex screening of cytokines and soluble receptors and found a number of soluble factors increased in the serum of active BD patients compared to healthy controls. The most elevated factor in their screening was CD40 L. A number of other soluble factors were also reported, namely TNFα and Interferon g, which are both potential NETs inducers in BD [11].…”

“…The implication of NETs in the pathophysiology of BD is still poorly investigated. Recently, circulating neutrophils from BD patients having an active disease were shown to release more NETs in response to circulating factors, namely CD40 L, compared to neutrophils from inactive disease [11].…”

Persistently higher serum sCD40L levels are associated with mortality in septic patients

“…In sepsis, EC activation induced adhesion receptors, released in ammatory mediators such as interleukin(IL)-1, IL-6 and tumor necrosis factor (13,14). sCD40L also effect on neutrophil oxidative burst and neutrophil extracellular trap (5,15). Previous studies and our studies suggested that sCD40L has no correlation with other coagulation factors except tissue factor(TF) (8).…”