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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
PubMed
Abstract

Insights

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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