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Segment-selective absorption of lysozyme in the intestine

Mikihisa Takano1, Yuka Koyama, Hiromi Nishikawa

  • 1Department of Pharmaceutics and Therapeutics, Programs for Pharmaceutical Sciences, Graduate School of Biomedical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan. takanom@hiroshima-u.ac.jp

European Journal of Pharmacology
|October 7, 2004
PubMed

Insights

Lysozyme absorption in rats is higher in the upper small intestine than the lower. This uptake occurs via an endocytic pathway, suggesting cationic charge is important for lysozyme intestinal absorption.

Area of Science:

  • Gastroenterology
  • Molecular Biology
  • Pharmacology

Background:

  • Lysozyme, an antimicrobial enzyme, plays a role in innate immunity.
  • The small intestine's role in lysozyme absorption is not well understood.
  • Megalin is an endocytic receptor known to bind lysozyme in the kidney.

Purpose of the Study:

  • To investigate the segment-specific absorption of lysozyme in the rat small intestine.
  • To explore the potential role of megalin in intestinal lysozyme absorption.
  • To elucidate the mechanism of lysozyme uptake in the small intestine.

Main Methods:

  • In situ closed loop and recirculation methods were used to assess FITC-lysozyme absorption.
  • Messenger RNA expression of megalin was analyzed in different intestinal segments.
  • Inhibitory effects of unlabeled lysozyme, spermine, and phenylarsine oxide on FITC-lysozyme absorption were evaluated.

Main Results:

  • FITC-lysozyme absorption was significantly higher in the upper small intestine compared to the lower intestine.
  • Megalin mRNA was detected in the lower but not the upper small intestine.
  • Lysozyme absorption in the upper intestine was inhibited by unlabeled lysozyme, spermine, and phenylarsine oxide, but not FITC-dextran.

Conclusions:

  • Intestinal lysozyme absorption is segment-selective, favoring the upper small intestine.
  • Megalin does not appear to significantly contribute to lysozyme absorption in the lower intestine.
  • Lysozyme is absorbed in the upper intestine via an endocytic pathway, potentially involving cationic charge interactions.

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