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Updated: May 20, 2026
Quantification of Intracellular Growth Inside Macrophages is a Fast and Reliable Method for Assessing the Virulence of Leishmania Parasites
Published on: March 16, 2018
Leishmania amazonensis fails to induce the release of reactive oxygen intermediates by CBA macrophages
T F Almeida1, L C Palma, L C Mendez
1Laboratório de Patologia e Biointervenção do CPqGM-FIOCRUZ, Bahia, Brazil.
Abstract:
CBA mouse macrophages effectively control Leishmania major infection, yet are permissive to Leishmania amazonensis. It has been established that some Leishmania species are destroyed by reactive oxygen species (ROS). However, other species of Leishmania exhibit resistance to ROS or even down-modulate ROS production. We hypothesized that L. amazonensis-infected macrophages reduce ROS production soon after parasite-cell interaction. Employing a highly sensitive analysis technique based on chemiluminescence, the production of superoxide (O(·-)(2)) and hydrogen peroxide (H(2)O(2)) by L. major- or L. amazonensis-infected CBA macrophages were measured. L. major induces macrophages to release levels of (O(·-)(2)) 3·5 times higher than in uninfected cells. This (O(·-)(2)) production is partially dependent on NADPH oxidase (NOX) type 2. The level of accumulated H(2)O(2) is 20 times higher in L. major-than in L. amazonensis-infected cells. Furthermore, macrophages stimulated with L. amazonensis release amounts of ROS similar to uninfected cells. These findings support previous studies showing that CBA macrophages are effective in controlling L. major infection by a mechanism dependent on both (O(·-)(2)) production and H(2)O(2) generation. Furthermore, these data reinforce the notion that L. amazonensis survive inside CBA macrophages by reducing ROS production during the phagocytic process.
Insights
Leishmania amazonensis evades immune cells by reducing reactive oxygen species (ROS) production, unlike Leishmania major which triggers a robust ROS response. This explains why macrophages control major but not amazonensis infections.
Area of Science:
- Immunology
- Parasitology
- Cell Biology
Background:
- CBA mouse macrophages effectively control Leishmania major infections.
- Macrophages are known to utilize reactive oxygen species (ROS) to eliminate certain Leishmania species.
- Leishmania amazonensis survival within macrophages suggests evasion mechanisms, potentially involving ROS modulation.
Purpose of the Study:
- To investigate the hypothesis that L. amazonensis-infected macrophages reduce ROS production shortly after interaction.
- To compare ROS (superoxide and hydrogen peroxide) production in CBA macrophages infected with L. major versus L. amazonensis.
Main Methods:
- Utilized a sensitive chemiluminescence-based assay to measure superoxide (O(·-)(2)) and hydrogen peroxide (H(2)O(2)) production.
- Infected CBA mouse macrophages with L. major or L. amazonensis.
- Quantified ROS levels in infected and uninfected macrophages.
Main Results:
- L. major infection induced a 3.5-fold increase in macrophage superoxide (O(·-)(2)) production, partially dependent on NADPH oxidase type 2.
- Hydrogen peroxide (H(2)O(2)) levels were 20 times higher in L. major-infected cells compared to L. amazonensis-infected cells.
- Macrophages infected with L. amazonensis exhibited ROS production levels similar to uninfected cells.
Conclusions:
- CBA macrophages control L. major infection via ROS production, including superoxide and hydrogen peroxide.
- L. amazonensis evades macrophage killing mechanisms by actively reducing ROS production during the phagocytic process.
- This differential ROS response explains the distinct outcomes of L. major and L. amazonensis infections in CBA macrophages.
