Treatment of Mycobacterium tuberculosis infected macrophages with Rifabutin loaded β-glucan microparticles induces...

Tuberculosis (TB), attributable to Mycobacterium tuberculosis (M.tb.), constitutes a formidable global health challenge, particularly with the proliferation of multidrug-resistant (MDR-TB) strains. The efficacious clearance of M.tb. from host cells is imperative for mitigating infection and averting disease progression. Autophagy, an intricate cellular mechanism for degrading and recycling biomolecules, plays a pivotal role in the immune response to M.tb. by facilitating the degradation of intracellular pathogen through the formation of autophagosomes and their subsequent fusion with lysosomes. The present study elucidates the therapeutic efficacy of Rifabutin loaded YDGP (DYDGP) microparticles within M.tb.infected macrophage. Our results show that the administration of DYDGP improve the membrane integrity of macrophage infected with H37Rv as well as MDR strains, as compared to that of untreated controls at 30 min, 6 h and 24 h post-exposure time points. DCFHDA staining elucidated that DYDGP treatment significantly enhances intracellular reactive oxygen species (ROS) production compared to blank YDGP, even in the presence of NOX-2 inhibitors. Furthermore, DYDGP promotes the biogenesis of acidic vesicular organelles and phago-lysosomal maturation, as corroborated by acridine orange and Lysotracker Red staining. Immunofluorescence and dansylcadaverine dual staining data evidenced that DYDGP treatment enhances autophagosome formation, autophagy induction and LC3 puncta formation within M.tb. infected macrophage at both 30 min and 24 h post-exposure time points. Further, protein expression analyses demonstrated that DYDGP treatment enhances the expression levels of NOX-2 and LC3, thereby confirming autophagy induction within M.tb. infected macrophage. Antimycobacterial efficacy assessments revealed that DYDGP treatment engendered significant reductions in colony-forming units (CFUs) of H37Rv (64, 40, 19), MDR32420 (44, 35, 18), MDR32422 (44, 39, 21), and MDR32521 (38, 22, 18) after 30 min, 24 h, and 48 h, exposure respectively. These findings accentuate DYDGP's potential to substantially attenuate M.tb. burden, including the addressal of MDR strains, thereby positioning it as a promising adjunctive therapy for augmenting TB treatment.