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Updated: May 27, 2026
Polarization of M1 and M2 Human Monocyte-Derived Cells and Analysis with Flow Cytometry upon Mycobacterium tuberculosis Infection
Published on: September 18, 2020
The human macrophage sodium channel NaV1.5 regulates mycobacteria processing through organelle polarization and
Lisette M Carrithers1, Paul Hulseberg, Matyas Sandor
1The Departments of Neurology, University of Wisconsin School of Medicine andPublic Health, Madison, USA. carrithers@neurology.wisc.edu
Abstract:
Phagocytosis and intracellular processing of mycobacteria by macrophages are complex cellular processes that require spatial and temporal coordination of particle uptake, organelle movement, activation of signaling pathways, and channel-mediated ionic flux. Recent work demonstrated that human macrophage NaV1.5, an intracellular voltage-gated sodium channel expressed on late endosomes, enhances endosomal acidification and phagocytosis. Here, using bacillus Camille-Guerin (BCG) as a model of mycobacterial infection, we examined how this channel regulates phagocytosis and phagosome maturation in human macrophages. Knockdown of NaV1.5 reduced high capacity uptake of labeled BCG. BCG-containing, NaV1.5-expressing cells demonstrated localization of NaV1.5 and Rab-7 positive endosomes and mitochondria to periphagosome regions that was not observed in NaV1.5-deficient cells. Knockdown of the channel reduced the initial calcium response following bacterial challenge and prevented the generation of prolonged and localized calcium oscillations during phagosome maturation. Inhibition of the mitochondrial Na(+) /Ca(2+) exchanger also prevented prolonged calcium oscillations during phagosome maturation. These results suggest that NaV1.5 and mitochondrial-dependent calcium signaling regulate mycobacteria phagocytosis and phagosome maturation in human macrophages through spatial-temporal coordination of calcium signaling within a unique subcellular region.
Insights
Human macrophage NaV1.5 channels enhance mycobacterial phagocytosis and phagosome maturation by regulating calcium signaling and organelle coordination. This finding reveals a novel role for intracellular sodium channels in host defense against mycobacteria.
Area of Science:
- Cellular Biology
- Immunology
- Ion Channel Physiology
Background:
- Phagocytosis of mycobacteria by macrophages is crucial for host defense but involves complex cellular processes.
- Intracellular voltage-gated sodium channels, like NaV1.5, are implicated in macrophage functions.
- NaV1.5 on late endosomes enhances endosomal acidification and phagocytosis.
Purpose of the Study:
- To investigate the role of human macrophage NaV1.5 in regulating phagocytosis and phagosome maturation during mycobacterial infection.
- To elucidate the mechanisms by which NaV1.5 influences calcium signaling and organelle dynamics during mycobacterial uptake.
Main Methods:
- Utilized bacillus Calmette-Guerin (BCG) as a model for mycobacterial infection in human macrophages.
- Employed knockdown of NaV1.5 to assess its impact on BCG uptake and phagosome maturation.
- Investigated the localization of NaV1.5, Rab-7, endosomes, and mitochondria relative to phagosomes.
- Measured calcium responses and oscillations using live-cell imaging.
- Examined the role of the mitochondrial Na+/Ca2+ exchanger.
Main Results:
- Knockdown of NaV1.5 significantly reduced the uptake of labeled BCG by macrophages.
- NaV1.5 expression correlated with the recruitment of Rab-7 positive endosomes and mitochondria to periphagosome regions.
- NaV1.5 deficiency impaired the initial calcium response and prevented prolonged calcium oscillations during phagosome maturation.
- Inhibition of the mitochondrial Na+/Ca2+ exchanger disrupted calcium oscillations during phagosome maturation.
Conclusions:
- NaV1.5 plays a critical role in enhancing mycobacterial phagocytosis and phagosome maturation in human macrophages.
- NaV1.5 regulates spatial-temporal calcium signaling, involving mitochondria, essential for efficient phagosome maturation.
- These findings highlight NaV1.5 as a potential target for modulating host immune responses against mycobacterial infections.
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