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Interaction of mycoplasmas and phagocytes
Abstract:
Aspects of the interaction of certain mycoplasmas with macrophages and neutrophils in vivo and in vitro have been studied using two systems, one involving M. pulmonis in mice and the other involving M. bovis with bovine leucocytes. Studies with M. pulmonis indicated that the disappearance of viable organisms from the peritoneal cavity was not enhanced in SPF mice in which a peritoneal exudate rich in neutrophils had been induced. However, viable M. pulmonis organisms disappeared more rapidly from the peritoneal cavities with exudates containing increased numbers of macrophages. Experiments in vitro studied the opsonic effect of bovine IgG isotypes for bovine neutrophils and alveolar macrophages. Both IgG1 and IgG2 promoted killing of M. bovis by alveolar macrophages but IgG2 was more effective than IgG1 at promoting mycoplasma killing by neutrophils. Further studies in vitro indicated that certain bovine mycoplasma could inhibit killing of Escherichia coli by bovine neutrophils.
Insights
This study shows that macrophages enhance mycoplasma clearance more effectively than neutrophils. Bovine IgG isotypes aid mycoplasma killing by macrophages, but some mycoplasmas can hinder neutrophil bacterial killing.
Area of Science:
- Immunology
- Microbiology
- Veterinary Science
Background:
- Mycoplasma species are significant pathogens in both human and animal health.
- Understanding host-pathogen interactions, particularly with innate immune cells like macrophages and neutrophils, is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the role of macrophages and neutrophils in clearing Mycoplasma species in vivo and in vitro.
- To evaluate the opsonic activity of bovine IgG isotypes on Mycoplasma bovis clearance by bovine leukocytes.
- To determine if Mycoplasma species can interfere with neutrophil function against other bacteria.
Main Methods:
- In vivo studies using Mycoplasma pulmonis in mice with induced peritoneal exudates (neutrophil-rich vs. macrophage-rich).
- In vitro experiments assessing the opsonic effect of bovine IgG1 and IgG2 on Mycoplasma bovis killing by bovine neutrophils and alveolar macrophages.
- In vitro assessment of Mycoplasma's impact on neutrophil-mediated killing of Escherichia coli.
Main Results:
- Mycoplasma pulmonis clearance was not enhanced by neutrophil-rich exudates but was accelerated in macrophage-rich exudates.
- Both bovine IgG1 and IgG2 enhanced Mycoplasma bovis killing by alveolar macrophages, with IgG2 being more effective.
- Bovine IgG2 was more effective than IgG1 in promoting mycoplasma killing by neutrophils.
- Certain bovine Mycoplasma species inhibited the killing of Escherichia coli by bovine neutrophils.
Conclusions:
- Macrophages play a more significant role in the clearance of Mycoplasma species than neutrophils in vivo.
- Bovine IgG isotypes differentially modulate the phagocytic and killing capacity of macrophages and neutrophils against Mycoplasma.
- Mycoplasma species possess mechanisms to evade or interfere with innate immune responses, potentially impairing neutrophil bactericidal activity against other pathogens.