AGE-RELATED DIFFERENCES OF FORMING NEUTROPHIL EXTRACELLULAR TRAPS IN HEALTHY INDIVIDUALS AND IN TUBERCULOSIS PATIENTS

Abstract

Abstracts. Introduction. Forming a neutrophil extracellular trap (NET) from DNA (NETosis) is considered as a potentially significant marker in the diagnosis of tuberculosis. However, there is practically a lack of data regarding the age-related differences in forming extracellular traps in research publications. Aim. To determine the age-related differences of NETosis in healthy individuals and in tuberculosis (TB) patients. Materials and Methods. The ability of neutrophils to form extracellular traps was investigated in 4 groups: 1) 4-7-year-old children diagnosed with the primary tuberculosis complex, who fell ill within Omsk region; 2) healthy and uninfected children at the same age; 3) adults with tuberculosis, and 4) adults without tuberculosis. For this purpose, isolated fractions of neutrophils from peripheral blood of the groups under research were stimulated with a mixture of bacteria (probiotic) for 30 minutes. In the hanging-drop preparation, we analyzed the proportion of neutrophil extracellular traps and cells in the state of various motility degrees. Results and Discussion. Age-related differences in the ability of neutrophils to form extracellular traps were characterized by a more pronounced response of neutrophils to the NETosis stimulant in children in the control group in comparison with neutrophils isolated from blood in the group of healthy adult volunteers: Neutrophils of children (Me=16.1; Q1=12.8; Q3=18.3) were statistically significantly more intense (p=0.0002) than those of adults (Me=8.6; Q1=7.1; Q3=10.5) and formed filamentous NETs. In the groups of pediatric and adult pulmonary TB patients, the response of neutrophils to the NETosis stimulant was diametrically opposite. Neutrophils of children with primary tuberculosis complex, as of those in the control group, predominantly formed filamentous NETs, but in greater amounts, while neutrophils of adults with infiltrative or focal form and with at most 2 segments involved mainly formed cloudy NETs, whereas filamentous NETs prevailed for the adults in the control group after stimulation. At the same time, proportion of cloudy NETs did not exceed 5% in healthy children and healthy adults. Comparing the findings of our study with literature data, we hypothesized that, most likely, there is a greater increase in PAD4 expression and more pronounced histone H3 citrullination in children’s neutrophils than in those of adults. Conclusions. Our findings indicate more pronounced ex vivo processes induced by NETosis stimulator in both groups of children (healthy individuals and TB patients) as compared to adults in the respective groups, which should be considered by the researchers interpreting the findings of the ability of neutrophils to form extracellular traps in tuberculosis.