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Bacterial transcytosis across conjunctival M cells
Carisa K Petris1, Miriam Golomb, Thomas E Phillips
1Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211-7400, USA.
Investigative Ophthalmology & Visual Science
|April 27, 2007
Summary
Conjunctival M cells actively transport bacteria into the eye, acting as a pathway for microbes. This process is partly mediated by alpha(2-3) sialic acid, influencing immune responses.
Area of Science:
- Ocular immunology
- Microbiology
- Epithelial cell biology
Background:
- Antigen-sampling M cells are present in conjunctival tissue overlying lymphoid follicles in rabbits and guinea pigs.
- Conjunctival M cells in guinea pigs exhibit alpha(2-3) sialic acid on their surfaces, identified by Maackia amurensis leukoagglutinin (MAL)-I binding.
Purpose of the Study:
- To investigate the role of conjunctival M cells in translocating large microbes, specifically bacteria.
- To test the hypothesis that conjunctival M cells serve as a portal for microbial entry into ocular tissues.
Main Methods:
- Instillation of fluorescein-labeled bacteria (Haemophilus influenzae strains OM12 and Rd KW20) into the conjunctival sac of guinea pigs.
- Visualization of bacterial distribution using confocal laser scanning microscopy and electron microscopy.
- Assessment of bacterial translocation using MAL-I co-administration to block alpha(2-3) sialic acid binding.
Main Results:
- Conjunctival M cells, not other epithelial cells, selectively bound and translocated bacteria into the follicle-associated epithelium (FAE).
- Bacteria were observed translocated deep into the follicle over time, with increased numbers and depth.
- Blocking alpha(2-3) sialic acid with MAL-I significantly reduced the transport of both OM12 and Rd KW20 strains, indicating its role in bacterial uptake.
Conclusions:
- Conjunctival M cells function as a significant entry point for large microbes into the eye.
- These M cells may initiate mucosal immune responses against common or transient ocular bacteria.
- Conjunctival M cells can facilitate the entry of pathogenic bacteria into ocular tissues.
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