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Quantification of the Respiratory Burst Response as an Indicator of Innate Immune Health in Zebrafish
Published on: September 12, 2013
Respiratory burst responses of rat macrophages to microsporidian spores
J Leiro1, R Iglesias, A Paramá
1Departamento de Microbiología y Parasitología, Laboratorio de Parasitología, Facultad de Farmacia, Universidad de Santiago de Compostela, Spain. mpleiro@usc.es
Abstract:
This study investigated the respiratory burst responses of rat resident peritoneal macrophages and of peritoneal macrophages stimulated 5 days previously with viable spores of the fish infecting microsporidian Microgemma caulleryi. Nitric oxide production by resident macrophages and prestimulated macrophages in response to viable microsporidian spores was significantly lower than in response to Escherichia coli lipopolysaccharide (LPS) (nitrite concentration in medium 57 +/- 1 microM for resident macrophages stimulated with LPS versus 31 +/- 1 microM for resident macrophages stimulated with microsporidian spores and 36 +/- 4 microM for M. caulleryi prestimulated macrophages; P < 0.05). Extracellular release of reactive oxygen species (ROS) by resident macrophages in response to microsporidian spores was similar to that in response to Kluyveromyces lactis yeast cells and to that in response to phorbol myristate (a stimulator of protein C kinase). Intracellular ROS production by resident macrophages in response to microsporidian spores was similar to that produced in response to yeast cells. Both extracellular ROS production and intracellular ROS production (in response to all stimuli) were significantly lower after in vivo prestimulation of macrophages with microsporidian spores. These results demonstrate that microsporidian spores of species other than those that habitually infect mammals are capable of modulating the respiratory burst of rat peritoneal macrophages. Such modulation may contribute to avoidance by the microsporidian of cytotoxic responses associated with the respiratory burst.
Insights
Microsporidian spores from fish can alter rat macrophage responses, reducing nitric oxide and reactive oxygen species (ROS) production. This modulation may help microsporidians evade host immune defenses.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Macrophages are crucial immune cells involved in pathogen defense.
- The respiratory burst, producing nitric oxide and reactive oxygen species, is a key microbicidal mechanism.
- Microsporidia are intracellular parasites with varying host specificities.
Purpose of the Study:
- To investigate the impact of Microgemma caulleryi spores on rat peritoneal macrophage respiratory burst responses.
- To compare the responses to microsporidian spores with those induced by Escherichia coli lipopolysaccharide (LPS) and other stimuli.
- To determine if prior in vivo exposure to microsporidian spores modulates macrophage activity.
Main Methods:
- Culturing rat resident peritoneal macrophages.
- Stimulating macrophages with viable Microgemma caulleryi spores, E. coli LPS, Kluyveromyces lactis yeast, and phorbol myristate.
- Measuring nitric oxide production via nitrite concentration.
- Assessing extracellular and intracellular reactive oxygen species (ROS) release.
Main Results:
- Nitric oxide production was significantly lower in response to microsporidian spores compared to LPS.
- Extracellular and intracellular ROS production by resident macrophages was similar to yeast cell stimulation.
- In vivo prestimulation with microsporidian spores significantly reduced both extracellular and intracellular ROS production.
Conclusions:
- Microsporidian spores, even non-mammalian specific ones, can modulate the respiratory burst of rat macrophages.
- This modulation of immune responses may be a strategy for microsporidian immune evasion.
- Further research is needed to understand the mechanisms of this immune modulation.
