Mitoxantrone elicits ROS-dependent elimination of dysfunctional mitochondria through mitophagy to control viability of intracellular mycobacteria in human macrophages.

Autophagy plays a critical role in clearance of Mycobacterium tuberculosis. It has emerged as a promising target for host-directed therapies against drug-resistant tuberculosis (TB). This insight opens up promising therapeutic avenues, suggesting that pharmacological activation of autophagy could effectively combat this highly persistent and harmful bacterium. The current study investigates the anti-mycobacterial properties of the anthracene-dione compound Mitoxantrone (MTX) through the activation of autophagy in differentiated THP-1 cells. The non-cytotoxic dose of MTX reduced the intracellular viability of mycobacteria compared to the control cells, and inhibition of autophagy reversed the effect of MTX on intracellular bacterial burden. Through multiparametric approaches, our investigation established the effect of MTX on mitochondria, the principal source of endogenous reactive oxygen species (ROS), acting as essential signal transducers that promote autophagy. Further, we have demonstrated that MTX decreased ATP production, which caused disruption of mitochondrial membrane proteins and increased mitochondrial ROS generation, resulting in mitochondrial fission and accelerating the initiation of mitophagy, leading to the elimination of intracellular mycobacteria. Our findings collectively demonstrated that MTX-induced mitochondrial dysfunction triggered interplay between two selective autophagic responses, diminishing mycobacterial infection and promoting its clearance. This study highlights MTX as a potential host-directed therapeutic candidate against TB through modulation of mitochondrial signaling pathways and autophagic responses.