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In vitro model of Treponema pallidum invasiveness
G R Riviere1, D D Thomas, C M Cobb
1Department of Oral Biology, School of Dentistry, University of Missouri-Kansas City 64108.
Abstract:
The purpose of this investigation was to develop an in vitro model with which invasion of tissues by pathogenic Treponema pallidum could be studied. Double-sided culture chambers were created by mounting abdominal walls excised from mice between two halves of small dialysis cells. The integrity of tissue barriers was confirmed by dye exclusion. T. pallidum subsp. pallidum, including intrinsically radiolabeled organisms, was introduced into one side of each chamber, and fractions from the other side were evaluated over time by dark-field microscopy and scintillation counting. Tissues were evaluated by scanning electron microscopy and immunologic staining. Motile T. pallidum, but not nonpathogenic, host-indigenous Treponema phagedenis biotype Reiter, was able to pass from one side of the chamber to the other side within 10 h. Up to 12% of the inoculum crossed the chamber within 24 h. Spirochetes were found within tissue in the greatest numbers between 6 and 8 h postinoculation. The murine abdominal wall has epithelium only on the peritoneum side, and results showed that T. pallidum required an epithelial surface on the entry side of the double-chambered cell in order to traverse the tissue barrier. This new in vitro technique may be of value in studying spirochete virulence and host resistance.
Insights
Pathogenic Treponema pallidum can invade tissues, but only when an epithelial surface is present. This study developed a novel in vitro model to investigate Treponema pallidum invasion of tissue barriers.
Area of Science:
- Microbiology
- Infectious Diseases
- Pathogenesis
Background:
- Treponema pallidum is a pathogenic bacterium responsible for syphilis.
- Understanding the mechanisms of tissue invasion by T. pallidum is crucial for developing effective treatments and prevention strategies.
- Existing models for studying T. pallidum invasion are limited.
Purpose of the Study:
- To develop a novel in vitro model for studying tissue invasion by pathogenic Treponema pallidum.
- To investigate the requirements for T. pallidum to traverse a tissue barrier.
- To assess the utility of this model for studying spirochete virulence and host resistance.
Main Methods:
- Development of a double-sided culture chamber using excised murine abdominal walls.
- Confirmation of tissue barrier integrity using dye exclusion.
- Introduction of radiolabeled T. pallidum subsp. pallidum and nonpathogenic Treponema phagedenis biotype Reiter into the chambers.
- Evaluation of spirochete translocation over time using dark-field microscopy and scintillation counting.
- Microscopic and immunologic analysis of invaded tissues.
Main Results:
- Motile T. pallidum, but not T. phagedenis biotype Reiter, successfully translocated across the tissue barrier within 10 hours.
- Up to 12% of the T. pallidum inoculum crossed the chamber within 24 hours.
- T. pallidum required an epithelial surface on the entry side of the chamber to invade the tissue.
- Spirochetes were most abundant within the tissue between 6 and 8 hours post-inoculation.
Conclusions:
- A new in vitro model using murine abdominal walls effectively simulates T. pallidum tissue invasion.
- Epithelial surface presence is a critical factor for T. pallidum tissue penetration.
- This model holds promise for future research into spirochete virulence factors and host immune responses.