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Secretion of microbicidal alpha-defensins by intestinal Paneth cells in response to bacteria

T Ayabe1, D P Satchell, C L Wilson

  • 1Department of Pathology, College of Medicine, University of California, Irvine, CA 92697, USA.

Nature Immunology
|March 15, 2001
PubMed

Insights

Paneth cells in the small intestine release antimicrobial peptides, such as alpha-defensins (cryptdins), within minutes of detecting bacteria or bacterial components, bolstering innate immunity.

Area of Science:

  • Immunology
  • Microbiology
  • Gastroenterology

Background:

  • Paneth cells are specialized epithelial cells in the small intestinal crypts.
  • They contain granules rich in antimicrobial peptides.
  • These peptides play a crucial role in intestinal innate immunity.

Purpose of the Study:

  • To investigate the secretory response of Paneth cells to various microbial stimuli.
  • To identify the specific microbial components that trigger Paneth cell degranulation.
  • To quantify the contribution of alpha-defensins to the antimicrobial activity of secreted granules.

Main Methods:

  • Exposure of mouse small intestinal crypts to different bacteria, bacterial antigens, fungi, and protozoa.
  • Measurement of Paneth cell granule secretion.
  • Assay of bactericidal peptide activity in the secreted granules.

Main Results:

  • Paneth cells rapidly secrete granules containing microbicidal peptides upon exposure to bacteria and bacterial antigens.
  • Alpha-defensins (cryptdins) constitute 70% of the bactericidal activity of the secreted peptides.
  • Specific bacterial components like LPS, lipoteichoic acid, lipid A, and muramyl dipeptide elicit secretion, while fungi and protozoa do not.

Conclusions:

  • Intestinal Paneth cells act as sentinels, sensing the presence of bacteria and bacterial antigens.
  • They rapidly discharge microbicidal peptides, including alpha-defensins, to combat bacterial threats.
  • This mechanism is a key component of the innate immune defense in the small intestine.

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