Nuclear factor-kappaB activation by edema inhibits intestinal contractile activity.

OBJECTIVE

To investigate the molecular mechanisms leading to edema-induced decreases in intestinal smooth muscle myosin light-chain phosphorylation. Intestinal interstitial edema often develops during abdominal surgery and after fluid resuscitation in trauma patients. Intestinal edema causes decreased intestinal contractile activity via decreased intestinal smooth muscle myosin light-chain phosphorylation, leading to slower intestinal transit. Interstitial edema development is a complex phenomenon, resulting in many changes to the interstitial environment surrounding intestinal smooth muscle cells. Thus, the mechanism(s) by which intestinal edema development causes intestinal dysfunction are likely to be multifactorial.

DESIGN

Randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats, weighing 250-350 g.

INTERVENTION

Studies were performed in a rat model in which a combination of mesenteric venous hypertension and administration of resuscitative fluids induces intestinal edema, mimicking the clinical setting of damage control resuscitation.

MEASUREMENTS AND MAIN RESULTS

Microarray analysis of edematous intestinal smooth muscle combined with an in silico search for overrepresented transcription factor binding sites revealed the involvement of nuclear factor-kappaB in edema-induced intestinal dysfunction. Nuclear factor-kappaB deoxyribonucleic acid binding activity was significantly increased in edematous intestinal smooth muscle compared with controls. Inhibition of nuclear factor-kappaB activation blocked edema-induced decreases in basal intestinal contractile activity. Inhibition of nuclear factor-kappaB activation also attenuated edema-induced decreases in myosin light-chain phosphorylation.

CONCLUSIONS

We conclude that intestinal edema activates nuclear factor-kappaB, which, in turn, triggers a gene regulation program that eventually leads to decreased myosin light-chain phosphorylation and, thus, decreased intestinal contractile activity.