The relationship between NETosis findings and disease activity in Behçet's disease: an exploratory study.

Objectives: This study aimed to investigate the relationship between the neutrophil extracellular traps (NET) and NETosis findings and disease activity in Behçet disease (BD).

Methods: The study group consisted of 30 active BD patients and 10 healthy individuals as controls. Serum and saliva samples were collected from the patients during their active and remission periods. A subset of them were followed longitudinally. Serum and saliva cf-DNA, NE, MPO, and cit-H3 levels were measured as indirect NETosis findings, subsequently the results were adjusted based on the peripheral blood neutrophil counts. Unadjusted and adjusted levels of the NETosis findings were evaluated.

Results: In active BD, unadjusted serum cf-DNA and NE levels were significantly higher than in controls, whereas adjusted serum MPO and cit-H3 levels were found to be lower. In inactive BD, unadjusted serum NE levels remained elevated compared to controls, while unadjusted serum MPO, adjusted serum MPO, and adjusted serum cit-H3 levels were lower. No significant differences were observed in salivary NETosis findings between the patients and controls. Longitudinal follow-up revealed a decrease in both unadjusted serum cf-DNA and saliva cf-DNA levels in parallel with reduced clinical activity. Saliva and unadjusted serum cf-DNA showed a positive correlation with inflammatory markers, whereas adjusted serum MPO and cit-H3 correlated negatively.

Conclusions: Indirect NETosis findings varied in relation to the systemic and/or local activity of BD patients. The changes after adjustment suggest that serum NETosis markers can be influenced by increased neutrophil turnover during the active phase of the disease.