Differential Regulation of Oxidative Burst by First Line Drugs Used Against Multi Drug-Resistant Tuberculosis in...

Background/Objectives: Reactive oxygen species (ROS) are key effectors of innate immunity but can also contribute to inflammation and tissue injury when their production is dysregulated. Although antibiotics are primarily selected for their antimicrobial activity, prolonged treatment may also influence host immune responses. However, the effects of anti-tuberculosis drugs on ROS production across innate immune cell subsets have not been assessed, especially not for novel drugs currently used against multi drug-resistant (MDR) tuberculosis (TB). Methods: Whole blood from healthy donors was incubated with seven antimycobacterial drugs used against MDR TB at sub-therapeutic, therapeutic, and supra-therapeutic concentrations. ROS production was quantified by flow cytometry using dihydrorhodamine 123 (DHR-123) in neutrophils, classical monocytes, and eosinophils under unstimulated conditions or following stimulation with Escherichia coli, fMLP, or PMA. Results: Bedaquiline and clofazimine decreased ROS production in neutrophils and classical monocytes across multiple stimuli (median values of Rh-123⁺ classical monocytes after E. coli stimulation without BDQ was 30.8% versus 24.9% with 1 µg/mL BDQ (p < 0.05, therapeutic concentration) and 31.3% without CFZ versus 19.2% with 1 µg/mL CFZ (p < 0.01, therapeutic concentration) in the same conditions). In contrast, levofloxacin and linezolid showed no detectable impact on ROS production in any cell population. Pretomanid uniquely induced a reduction in ROS generation in eosinophils and classical monocytes while sparing neutrophil oxidative burst activity, distinguishing it from other antibiotics tested (34.1% decrease in Rh-123 MFI of eosinophils between the control and PA 3 µg/mL after fMLP stimulation, p < 0.01, therapeutic concentration). Conclusions: These findings demonstrate that first line drugs against MDR TB display heterogeneous and cell type-specific effects on innate immune oxidative responses. Such differential effects on host immunity may have implications for both antimicrobial efficacy and inflammation control during tuberculosis treatment.