Iatrogenic extracellular matrix disruption as a local trigger for postoperative ileus.
BACKGROUND
Active matrix metallopeptidase 9 (MMP-9) disruption of the extracellular matrix (ECM) plays an important role in inflammatory disorders. In this study, we investigated the inflammatory role of MMP-9 and the ECM breakdown product hyaluronan as a trigger for the postoperative intestinal inflammatory response of postoperative ileus.


METHODS
We performed a standardized intestinal surgical manipulation on rats to produce ileus assessed by the oral non-digestible fluorescein isothiocyanate-dextran transit assay. We studied isolated intestinal muscularis extracts for mRNA expressions of interleukin 6 (IL-6), MMP-9 and CD44. We quantified peritoneal MMP-9 activity using zymography, and quantified peritoneal fluid and serum for hyaluronan and tissue inhibitor of metalloproteinase 1 levels by enzyme-linked immunosorbent assay (ELISA). We cultured peritoneal macrophages and exposed them to peritoneal fluid or synthetic hyaluronan for ELISA analysis of IL-6 and macrophage inflammatory protein-1α.


RESULTS
Transit was significantly delayed after surgical manipulation, and extracts of the isolated jejunal and colonic muscularis demonstrated a significant induction of IL-6, MMP-9, and CD44 mRNAs compared with controls. Zymography confirmed significant MMP-9 activity in peritoneal fluid compared with controls. Enzyme-linked immunosorbent assay measurements showed a significant up-regulation in hyaluronan and tissue inhibitor of metalloproteinase 1 in the peritoneal fluid and serum. In addition, ELISA and reverse transcriptase-polymerase chain reaction measurements of peritoneal macrophages stimulated with postsurgical peritoneal fluid and synthetic hyaluronan resulted in higher expressions of IL-6 and macrophage inflammatory protein-1α in the macrophage supernatant.


CONCLUSIONS
Our results confirm that MMP-9 disruption in the ECM with hyaluronan release and muscularis CD44 receptor induction has the potential to trigger muscularis proinflammatory cascades that cause postoperative ileus. Matrix metallopeptidase 9 inhibition may be a novel therapeutic approach to limit postoperative ileus.
Department of General, Visceral, Thoracic, and Vascular Surgery, University of Bonn, Bonn, Germany.
Johannes
J
Chang
Sven
S
Wehner
Nico
N
Schäfer
Maria
M
Sioutis
Stephan
S
Bortscher
Andreas
A
Hirner
Jörg C
JC
Kalff
Anthony J
AJ
Bauer
Marcus
M
Overhaus
D000818:Animals; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000502:physiology*; D005772:Gastrointestinal Transit; D018960:Hyaluronan Receptors / Q000502:physiology; D006820:Hyaluronic Acid / Q000502:physiology; D045823:Ileus / Q000209:etiology*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000502:physiology; D011183:Postoperative Complications / Q000209:etiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000502:physiology
D018960:Hyaluronan Receptors; D019715:Tissue Inhibitor of Metalloproteinase-1; D006820:Hyaluronic Acid; D020780:Matrix Metalloproteinase 9