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Coiling phagocytosis is the preferential phagocytic mechanism for Borrelia burgdorferi
M G Rittig1, A Krause, T Häupl
1Department of Anatomy, University of Erlangen-Nürnberg, Germany.
Abstract:
The uptake mechanism for the spirochete Borrelia burgdorferi, the causative agent of Lyme disease, was investigated by electron microscopy for human and murine phagocytes. Spirochetes of both a low- and a high-passage strain were preferentially internalized by coiling rather than by conventional phagocytosis. The spirochetes engulfed by coiling phagocytosis were found to disintegrate in an organelle exclusion zone without evident participation of lysosomes. Preincubation of B. burgdorferi with monoclonal antibody to the spirochetal OspA enhanced phagocytosis in general but did not consistently influence the uptake mechanism. Quantitative and kinetic differences concerning the phagocytic rate and mechanism were evident between cells from different lineages, different human individuals, and mice and humans. In general, when few phagocytes participated in spirochete uptake, the active cells displayed a high ratio of coiling versus conventional phagocytosis. These results suggest that coiling phagocytosis of B. burgdorferi plays a critical role in the control of spirochetal infection. More detailed studies on the molecular basis of this phagocytic mechanism may lead to new insights into the pathogenesis of Lyme borreliosis, a disease which is frequently characterized by the host's inability to eliminate the pathogenic spirochete.
Insights
Borrelia burgdorferi, the Lyme disease spirochete, is primarily internalized by coiling phagocytosis, not conventional methods. This mechanism, crucial for controlling infection, involves spirochete disintegration without lysosome involvement.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Borrelia burgdorferi is the bacterium causing Lyme disease.
- Understanding pathogen uptake by host cells is key to controlling infection.
Purpose of the Study:
- To investigate the uptake mechanism of Borrelia burgdorferi by human and murine phagocytes.
- To elucidate the role of coiling phagocytosis in controlling spirochetal infection.
Main Methods:
- Electron microscopy was used to visualize the interaction between Borrelia burgdorferi and phagocytes.
- Phagocytosis was assessed using both low- and high-passage strains of the spirochete.
- The effect of monoclonal antibody to OspA on phagocytosis was evaluated.
Main Results:
- Borrelia burgdorferi was preferentially internalized via coiling phagocytosis, not conventional phagocytosis.
- Engulfed spirochetes disintegrated in an organelle exclusion zone, independent of lysosomes.
- Phagocytic rates and mechanisms varied between different cell types and individuals.
- Antibody treatment enhanced overall phagocytosis but did not alter the uptake mechanism.
Conclusions:
- Coiling phagocytosis is a critical mechanism for controlling Borrelia burgdorferi infection.
- Further research into the molecular basis of coiling phagocytosis could offer insights into Lyme borreliosis pathogenesis.
- The host's difficulty in eliminating Borrelia burgdorferi may be linked to this uptake mechanism.