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Identification of epithelial gaps in human small and large intestine by confocal endomicroscopy
Ralf Kiesslich1, Martin Goetz, Elizabeth M Angus
1I Medical Clinic, University of Mainz, Mainz, Germany.
Insights
Confocal endomicroscopy can identify gaps in human intestinal epithelium. Proinflammatory cytokines like tumor necrosis factor alpha increase cell shedding, impacting intestinal barrier function.
Area of Science:
- Gastroenterology
- Microscopy
- Cell Biology
Background:
- Confocal endomicroscopy presents challenges in identifying human intestinal epithelial structures.
- Previous research indicated murine intestinal epithelium has gaps from cell shedding.
Purpose of the Study:
- To determine if confocal endomicroscopy can resolve human epithelial gaps.
- To investigate if a proinflammatory cytokine increases cell shedding.
Main Methods:
- Intestinal mucosa was stained with acriflavine and imaged using confocal endomicroscopy in 17 patients.
- Results were validated in mice using rigid confocal probe microscopy, 2-photon/confocal microscopy, and scanning electron microscopy.
Main Results:
- Human intestinal epithelium showed unstained areas resembling individual epithelial cells.
- Mouse studies identified these as goblet cells or gaps in Math1(DeltaIntestine) mice.
- Tumor necrosis factor alpha increased mouse cell shedding 27-fold, compromising barrier function.
Conclusions:
- Confocal endomicroscopy can differentiate epithelial gaps from goblet cells in the human intestine.
- Epithelial gap sealing is crucial for intestinal barrier integrity.
- Findings have implications for understanding intestinal barrier dysfunction in diseases.
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 Math1(DeltaIntestine)) 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 Math1(DeltaIntestine) mice, which lack goblet cells. In the mouse, tumor necrosis factor alpha (0.33 microg/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.
