Macrophage Interactions with Mycobacterium Pathogens

Macrophages are frontline defenders against Mycobacterium pathogens, orchestrating both innate and adaptive immune responses. Following inhalation or entry at mucosal surfaces, mycobacteria are recognised and internalised by macrophages through phagocytosis. Instead of being destroyed, however, pathogenic species such as Mycobacterium tuberculosis and non-tuberculous mycobacteria employ a range of evasion tactics. They arrest phagosomal maturation, subvert autophagy pathways and manipulate host signalling to establish an intracellular niche. Polarisation of macrophages into pro-inflammatory (M1) or anti-inflammatory (M2) states is a critical determinant of infection outcome. M1 macrophages produce nitric oxide and inflammatory cytokines that restrict bacterial growth, whereas M2 macrophages foster tissue repair and may inadvertently permit persistence. Over time, infected macrophages aggregate to form granulomas, structured cellular assemblies that aim to contain but seldom eradicate mycobacteria. The global burden of tuberculosis and rising incidence of drug-resistant and atypical mycobacterial infections underline the urgent need for new vaccines and host-directed therapies. Advances in imaging, single-cell profiling and molecular biology are illuminating the delicate balance between protective immunity and pathological inflammation, offering fresh avenues for intervention.

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Macrophage Interactions with Mycobacterium Pathogens publication trend

The graph below shows the total number of articles in macrophage interactions with mycobacterium pathogens across all publications each year (not limited to Nature Index journals).

Technical terms

Macrophage: A phagocytic white blood cell that engulfs pathogens, processes antigens and orchestrates immune responses.

Phagocytosis: The cellular process by which macrophages ingest and attempt to destroy microbial invaders.

Granuloma: A structured aggregate of immune cells, primarily macrophages, that forms around persistent mycobacterial infection to contain the pathogen.

Polarisation: The differentiation of macrophages into distinct functional states (M1 pro-inflammatory or M2 anti-inflammatory) in response to environmental cues.

Interferon-γ (IFN-γ): A cytokine essential for activating macrophages and enhancing their antimicrobial mechanisms against intracellular pathogens.

Signal transducer and activator of transcription-3 (STAT3): A transcription factor that regulates macrophage activation, driving anti-inflammatory programmes exploited by intracellular bacteria.

References

1. Enhancement of mycobacterial pathogenesis by host interferon-γ. Cellular and Molecular Life Sciences (2024).
2. Ready, STAT3, Go! Bacteria in the race for M2 macrophage polarisation. Current Opinion in Microbiology (2023).
3. Induction of killing of Mycobacterium avium subsp. hominissuis in macrophages by cytokine stimulated innate-like lymphoid cells is negatively affected by the pathogen. International Microbiology (2023).