Neutrophil extracellular traps: formation dynamics associated with the transition from remission to active rheumatoid arthritis

Abstract

Tne aim of the research. To evaluate the main parameters of neutrophil extracellular traps formation (NETosis) and their dynamics in rheumatoid arthritis (RA) patients associated with the transition from remission to active autoimmune infl ammation. Material and methods. A total of 37 patients (6 males and 31 females) with verifi ed RA according to the ACR/EULAR 2010 criteria were enrolled in the study and formed the main group. Th e comparison group was constituted by 30 healthy volunteers. Circulating neutrophils were isolated with one-step density gradient centrifugation using double layers of iohexol gradient in the original modifi cation. Th e quantitative composition of neutrophils was assessed through microscopy of smears stained according to May-Grunwald. Cell viability as well as non-specifi c activation were evaluated microscopically using trypan blue exclusion assay and nitroblue tetrazolium test, respectively. Neutrophil extracellular trap (NETs) formation was induced by 50 nM phorbol-12-myristate-13- acetate and assessed using fl uorescence microscopy. Results. Neutrophils isolated from RA patients in clinical remission have been revealed to have a higher ability for spontaneous and induced NETs formation than neutrophils from the comparison group. Th e transition from remission to active RA was characterised by a signifi cant increase in induced and, especially, spontaneous formation of NETs. Th e growth rate of spontaneous NET formation was 3.9-fold higher than the induced NETs formation. Spontaneous formation of NETs above 16.4 % may serve as a possible RA activation indicator. Neutrophils from ACPA-positive RA patients were found to have increased spontaneous and induced NETs formation compared to ACPA-negative RA patients. Conclusion. We have studied the main parameters of NETs formation and their dynamics associated with the transition from remission to active autoimmune infl ammation in RA patients. Th e activity of RA has a more pronounced eff ect on the intensity of NETs formation than the presence of ACPA. NETs may be considered a new potential diagnostic and prognostic biomarker