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Pure endotoxin does not pass across the intestinal epithelium in vitro
R Benoit1, S Rowe, S C Watkins
1Department of Surgery, University of Pittsburgh School of Medicine and The Children's Hospital of Pittsburgh, Pennsylvania 15213, USA.
Shock (Augusta, Ga.)
|August 4, 1998
Summary
Pure lipopolysaccharide (LPS) does not cross the injured intestinal barrier in vitro. Bacterial translocation in vivo may involve LPS released from dead bacteria, not direct LPS passage.
Area of Science:
- Gastroenterology
- Immunology
- Critical Care Medicine
Background:
- Endotoxin (lipopolysaccharide, LPS) is implicated in triggering systemic inflammatory response syndrome.
- Mechanisms of LPS translocation across the intestinal barrier remain unclear.
- Bacterial translocation is observed following conditions like hemorrhagic shock.
Purpose of the Study:
- To investigate whether pure endotoxin (LPS) can permeate injured rat ileal mucosa in an in vitro Ussing chamber model.
- To compare the transmucosal passage of LPS with that of whole bacteria (E. coli).
Main Methods:
- Rats underwent mild or severe hemorrhagic shock, or sham-shock, followed by resuscitation.
- Bacterial translocation was assessed in mesenteric lymph nodes, liver, and spleen.
- Transmucosal passage of FITC-labeled E. coli and FITC-conjugated LPS was measured using Ussing chambers and microscopy.
Main Results:
- Severe hemorrhagic shock led to high mortality and bacterial translocation.
- While FITC-labeled E. coli crossed the ileal mucosa, FITC-LPS passage was never detected, even with mucosal injury.
- Disruption of the intestinal epithelium did not increase FITC-LPS transmucosal passage.
Conclusions:
- Pure LPS does not appear to cross the intestinal mucosa in vitro.
- Translocation of LPS in vivo may result from LPS released from bacteria that have already translocated and subsequently died.