Background/Purpose
Plasma factors seem to play a role in Behçet’s disease (BD) pathogenesis, especially by increasing phagocyte oxidative profile. No data exists regarding neutrophil extracellular trap (NET) formation. We investigate the effect of plasma from patients with active BD (aBD) and inactive BD (iBD) on NET formation and oxidative burst, and searched for candidate soluble factors.
Methods
Neutrophils, peripheral blood mononuclear cells (PBMC) and plasma were obtained from patients with aBD (n=30), iBD (n=31), and healthy controls (HC; n=30). H2O2 and O2– production was determined by luminol/lucigenin luminescence with or without stimulation with phorbol myristate acetate (PMA), Streptococcus pneumoniae, Streptococcus sanguinis, Candida albicans or human plasma (from HC, iBD or aBD). Gene expression for the five NADPH-oxidase subunits was determined by qRT-PCR in resting cells, and protein expression by flow cytometry before and after stimulation with PMA or human plasma. NET formation was quantified after stimulus with PMA or human plasma, followed by labeling with anti-histones antibody, anti-neutrophil elastase antibody and Sytox Orange.
Results
Neutrophil production of O2–/H2O2 (Table 1) and NADPH-oxidase expression (Table 2) was higher after stimulus with aBD or iBD plasma than with HC plasma. PBMC displayed equivalent results. Resting and pathogen-stimulated phagocytes presented equivalent O2–/H2O2 production and NADPH-oxidase expression. NET formation was constitutively increased in aBD and iBD, compared to HC neutrophils (Table 3). Similarly, neutrophils from aBD and iBD produced more extensive NET than neutrophils from HC when stimulated with iBD plasma. In neutrophils from each group, aBD plasma induced greater NET formation than iBD or HC plasma. Eighteen soluble factors had increased concentration in aBD or BD plasma, and six were increased in both (Table 3). There was no significant difference in medication use between aBD and iBD patients.
Conclusion
Plasma from patients with aBD exerts a strong stimulus on NET formation and phagocyte oxidative burst. Increased concentration of MIP-1β, TNFα and other soluble plasma factors might be associated with neutrophil hyperactivity in BD. These findings warrant further studies in order to identify possible metabolic pathways involved in neutrophil activation in BD.
Disclosure:
S. F. Perazzio,
None;
P. V. S. Pereira,
None;
A. W. S. de Souza,
None;
A. Condino-Neto,
None;
L. E. C. Andrade,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/plasma-of-patients-with-active-behcets-disease-bd-increases-neutrophil-extracellular-trap-formation-oxidative-metabolism-and-nadph-oxidase-expression-in-normal-and-bd-neutrophils-and-carries/