Pathogenesis of Cutaneous Mycobacterial Infections-M. marinum and M. leprae.

Mycobacterium marinum and Mycobacterium leprae are zoonotic mycobacteria causing chronic cutaneous infections that challenge host immunity and tissue integrity. Reactive oxygen species (ROS) play a complex role in the host defense system. While essential for pathogen elimination and intracellular signaling, excessive ROS can lead to immune dysregulation and impaired tissue healing. This review explores M. marinum and M. leprae pathogenesis through the role of ROS in redox imbalances, immunity, and cutaneous wound healing. Physiological ROS levels are vital for T-cell activation and differentiation. However, excessive ROS production, particularly in innate immune cells, can lead to T-cell suppression. M. leprae infection is associated with a significant reduction in key antioxidants such as glutathione (GSH), GSH peroxidase (GSH-Px), and GSH reductase (GR), a reduction that correlates with disease severity. For M. marinum, disrupting the pathogen's redox balance through thioredoxin reductase (TrxR) inhibition sensitizes bacteria to ROS damage, reducing bacterial load. Overall, redox imbalance is central to the pathogenesis and persistence of cutaneous mycobacterial infections, compromising host defense and impairing tissue repair. Restoring and maintaining proper redox homeostasis, potentially by exploring the role of GSH as an antioxidant, represents a promising adjunct treatment to improve host outcomes in these challenging dermatological conditions.