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Lipopolysaccharide activates the muscularis macrophage network and suppresses circular smooth muscle activity

M K Eskandari1, J C Kalff, T R Billiar

  • 1Department of Surgery, University of Pittsburgh Medical School, Pennsylvania 15261, USA.

The American Journal of Physiology
|October 8, 1997
PubMed

Insights

Bacterial lipopolysaccharide (LPS) causes sepsis-induced ileus by activating macrophages and leading to inflammation. This study reveals LPS impairs intestinal muscle function and increases leukocyte infiltration in rats.

Area of Science:

  • Gastroenterology
  • Immunology
  • Cellular Biology

Background:

  • Bacterial lipopolysaccharide (LPS) triggers inflammation and is linked to sepsis-induced ileus.
  • The impact of LPS on intestinal muscularis macrophages and inflammation remains under-investigated.

Purpose of the Study:

  • To investigate cellular and functional changes in rat intestinal muscularis following LPS administration.
  • To understand the role of the macrophage network in LPS-induced intestinal dysfunction.

Main Methods:

  • Histology and immunohistochemistry to identify leukocyte populations.
  • Organ bath studies to assess intestinal muscle contractility.
  • Intraperitoneal LPS injection in a rat model.

Main Results:

  • LPS significantly increased lymphocyte activation marker-1 (LFA-1) on macrophages within 1 hour.
  • Neutrophil, mast cell, and monocyte infiltration into the muscularis was observed.
  • A 62% reduction in spontaneous and 91% suppression of stimulated circular muscle activity occurred 12 hours post-LPS.

Conclusions:

  • Endotoxemia acutely activates the intestinal muscularis macrophage network.
  • LPS induces leukocyte extravasation into the muscularis.
  • LPS exposure leads to significant impairment of intestinal circular muscle function.

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