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Colon
Bacteroides fragilis toxin 2 damages human colonic mucosa in vitro
  1. M Rieglerd,
  2. M Lotzd,
  3. C Searse,
  4. C Pothoulakisd,
  5. I Castagliuolod,
  6. C C Wangd,
  7. R Sedivyb,
  8. T Sogukoglua,
  9. E Cosentinia,
  10. G Bischofa,
  11. W Feilc,
  12. B Telekya,
  13. G Hamiltona,
  14. J T LaMontd,
  15. E Wenzla
  1. aUniversity Clinic of Surgery, University of Vienna, Austria, bInstitute of Clinical Pathology, University of Vienna, Austria, cDepartment of Surgery, Danube Hospital, Vienna, Austria, dDivision of Gastroenterology, Beth Israel Deaconess Medical Centre, Boston, Harvard Medical School, Massachusetts, USA, eDivisions of Infectious Diseases and Gastroenterology, John Hopkins University, Baltimore, Maryland, USA
  1. Dr C Pothoulakis, Division of Gastroenterology, Beth Israel Deaconess Medical Centre, 330 Brookline Ave, Boston, MA 02215, USA.

Abstract

BACKGROUND Strains ofBacteroides fragilis producing a 20 kDa protein toxin (B fragilis toxin (BFT) or fragilysin) are associated with diarrhoea in animals and humans. Although in vitro results indicate that BFT damages intestinal epithelial cells in culture, the effects of BFT on native human colon are not known.

AIMS To examine the electrophysiological and morphological effects of purified BFT-2 on human colonic mucosa in vitro.

METHODS For resistance (R) measurements, colonic mucosa mounted in Ussing chambers was exposed to luminal or serosal BFT-2 (1.25–10 nM) and after four hours morphological damage was measured on haematoxylin and eosin stained sections using morphometry. F actin distribution was assessed using confocal microscopy.

RESULTS Serosal BFT-2 for four hours was four-, two-, seven-, and threefold more potent than luminal BFT-2 in decreasing resistance, increasing epithelial3H-mannitol permeability, and damaging crypt and surface colonocytes, respectively (p<0.05). Confocal microscopy showed reduced colonocyte F actin staining intensity after exposure to BFT-2.

CONCLUSIONS BFT-2 increases human colonic permeability and damages human colonic epithelial cells in vitro. These effects may be important in the development of diarrhoea and intestinal inflammation caused by B fragilis in vivo.

  • B fragilis toxin
  • toxin mediated colonocyte damage
  • actin filaments
  • transepithelial resistance
  • morphometry

  • Abbreviations

    BFT
    Bacteroides fragilis toxin
    ETBF
    enterotoxigenicBacteroides fragilis
    Isc
    short circuit current
    PD
    potential difference
    R
    resistance

    • https://doi.org/10.1136/gut.44.4.504

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    • Abbreviations

      BFT
      Bacteroides fragilis toxin
      ETBF
      enterotoxigenicBacteroides fragilis
      Isc
      short circuit current
      PD
      potential difference
      R
      resistance
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