Gastroenterology

Gastroenterology

Volume 133, Issue 6, December 2007, Pages 1769-1778
Gastroenterology

Clinical–Alimentary Tract
Identification of Epithelial Gaps in Human Small and Large Intestine by Confocal Endomicroscopy

https://doi.org/10.1053/j.gastro.2007.09.011Get rights and content

Background & Aims: Confocal endomicroscopy is an emerging technology that poses the endoscopist with challenges for identifying epithelial structures in the human intestine. We have shown previously that the murine intestinal epithelium is punctuated by gaps caused by cell shedding. The goals of this study were to determine if confocal endomicroscopy could resolve the presence of human epithelial gaps and whether a proinflammatory cytokine could increase cell shedding. Methods: Intestinal mucosa was imaged after staining with acriflavine. Confocal endomicroscopy of 17 patients yielded 6277 images from the human terminal ileum and rectum. Results were validated by parallel studies of anesthetized mice (wild-type and Math1ΔIntestine) using rigid confocal probe microscopy, 2-photon/confocal microscopy, and scanning electron microscopy. Results: Human terminal ileal and rectal epithelium revealed unstained areas with the diameter of an individual epithelial cell, with 2 distinct morphologies. One had a “target” appearance, shown by mouse studies to be goblet cells. The other morphology had no nucleus and was observed by rigid confocal probe microscopy and scanning electron microscopy in the villi of Math1ΔIntestine mice, which lack goblet cells. In the mouse, tumor necrosis factor α (0.33 μg/g intraperitoneally) increases cell shedding by 27-fold and caused loss of barrier function across 20% of resultant gaps. Conclusions: Confocal endomicroscopy can distinguish between epithelial discontinuities (gaps) and goblet cells in human intestine. Results suggest that the sealing of epithelial gaps must be considered as a component of the intestinal barrier and has potential implications for intestinal barrier dysfunction in human disease.

Section snippets

Patients

Patients undergoing colonoscopy for cancer screening or investigation of abdominal pain were recruited. Patients with known active inflammatory bowel diseases, acute gastrointestinal bleeding, coagulopathy (prothrombin time <50% of control; partial thromboplastin time >50 seconds), impaired renal function (creatinine level >1.2 mg/dL), pregnancy or breast-feeding, inability to give informed consent, and known allergy to fluorescein or acriflavine were excluded. Patients with inadequate bowel

Results

We have previously used the nuclear stain Hoechst 33258 to find discontinuities in the murine epithelial layer, identified by the absence of a nucleus. Acriflavine has been reported as a dye for confocal microendoscopy that stains nuclei and, unlike Hoechst 33258, is approved for use in human endoscopy.10

Discussion

Confocal endomicroscopy is an emerging technology that presents an unfamiliar view of intestinal morphology. We have taken a translational approach to help identify and interpret one of the more unexpected features observed using this imaging modality. In brief summary, we provide evidence that inhomogeneities in acriflavine staining of the intestinal epithelium are explained by 2 features: lack of goblet cell staining and occasional epithelial discontinuities (gaps). As confocal endomicroscopy

References (29)

  • K.D. Katz et al.

    Intestinal permeability in patients with Crohn’s disease and their healthy relatives

    Gastroenterology

    (1989)
  • B.R. Yacyshyn et al.

    CD45RO expression on circulating CD19+ B cells in Crohn’s disease correlates with intestinal permeability

    Gastroenterology

    (1995)
  • E.J. Irvine et al.

    Increased intestinal permeability precedes the onset of Crohn’s disease in a subject with familial risk

    Gastroenterology

    (2000)
  • C.S. Potten et al.

    Stem cells: attributes, cycles, spirals, pitfalls and uncertaintiesLessons for and from the crypt

    Development

    (1990)
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    Supported by the HVC Foundation (grant 10). R.K. holds an unrestricted grant from Pentax Europe.

    The authors report that no conflicts of interest exist.

    1

    R.K. and M.G. share first authorship.

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