Changes in neutrophil extracellular trap formation ability and citrullinated histone H3 concentration as a criterion for antituberculosis therapy efficacy in children

Introduction. Neutrophil extracellular traps (NETs) play a dual role in host defense and immunopathology. However, the impact of anti-tuberculosis (TB) and preventive chemotherapy on NET formation remains insufficiently studied, particularly in pediatric populations.

Objective. To evaluate changes in the ability of peripheral blood neutrophils to form extracellular traps and in serum citrullinated histone H3 (citH3) levels in children with respiratory tuberculosis and latent tuberculosis infection (LTBI) before and after chemotherapy.

Methods. The study included children with active respiratory TB (n=21) examined at diagnosis and after 6 months of anti-TB therapy, children with LTBI (n=27) examined before and after 6 months of preventive chemotherapy, and healthy controls (n=30). Neutrophils were isolated on a double Ficoll-Verografin density gradient and stimulated with a nonspecific bacterial antigen (probiotic mixture). NET types (cloud-shaped, filamentous) and activation stages were assessed by fluorescence microscopy. Serum citH3, PAD4, DRP-1, IL-1β was measured by ELISA.

Results. At baseline, children with active TB showed significantly higher percentages of early NETosis cells, cloud-shaped, and filamentous NETs compared to controls (p<0.05). After 6 months of anti-TB chemotherapy, cloud-shaped NETs nearly disappeared, while filamentous NETs remained unchanged. In LTBI patients, initial filamentous NET levels were significantly elevated versus controls (p=0.0419). After preventive chemotherapy, the proportion of filamentous NETs decreased significantly (p=0.0357) to control levels. Serum citH3 was markedly elevated in LTBI at baseline (median 5.60 ng/mL vs. 1.41 ng/mL in controls, p=0.0002) and normalized after preventive therapy (1.20 ng/mL). No significant changes were observed in PAD4, DRP-1, IL-1β serum levels.

Conclusion. Both anti-TB and preventive chemotherapy reduce NET formation capacity, predominantly affecting filamentous NETs and citH3 levels. These parameters may serve as promising biomarkers for monitoring treatment efficacy in tuberculosis and latent infection.

The study was carried out using funds from the State Assignment of the Ministry of Health of Russia (Registration No. 124021500060-1 dated February 15, 2024).