Research

Translocation of bacterial NOD2 agonist and its link with inflammation

Oh Yoen Kim¹ , Antoine Monsel² , Michèle Bertrand² , Jean-Marc Cavaillon¹ , Pierre Coriat² and Minou Adib-Conquy¹

¹  Cytokines & Inflammation Unit, Institut Pasteur, 28 rue Dr. Roux, 75015 Paris, France

²  Department of Anesthesiology and Critical Care, Université Pierre et Marie Curie – Paris 6, and Centre Hospitalier Universitaire Pitié-Salpêtrière, Assistance-Publique Hôpitaux de Paris, Paris, France

author email corresponding author email

Critical Care 2009, 13:R124doi:10.1186/cc7980

Published:	28 July 2009

Abstract

Introduction

The gut is often considered as the motor of critical illness through bacterial translocation, which amplifies the inflammatory response and alters the immune status. However, systemic bacterial translocation was rarely proven and endotoxin measurement only reflects translocation of Gram-negative-derived products. The process could be more frequently identified if peptidoglycan, derived from both Gram-negative and Gram-positive bacteria, was measured.

Methods

We developed a new tool to detect circulating peptidoglycan-like structure using a NOD2-transfected cell line. We also measured plasma and cell-associated endotoxin and different plasma markers of inflammation. We studied 21 patients undergoing abdominal aortic surgery (AAS), and 21 patients undergoing carotid artery surgery (CAS) were included as negative controls. Patients were sampled during surgery until two days post-surgery.

Results

In 90.5% of the AAS patients, a NOD2 agonist peak was detected in plasma before aortic clamping, but after gut manipulation by the surgeon, and persisted after blood reperfusion. As expected, no peak was detected in plasma from CAS patients (P = 0.003). Leukocyte-bound endotoxin appeared after blood reperfusion in 71% of the AAS patients, and circulating endotoxin was detected for 57% of them. The levels of interleukin (IL)-6, IL-10 and of inflammatory markers (C-reactive protein, procalcitonin) were maximal at postoperative day 1 or 2 in AAS patients. The levels of circulating NOD2 agonist positively correlated with those of cortisol and IL-10.

Conclusions

The measurement of circulating NOD2 agonist gives a higher informative tool than that of circulating endotoxin for early and sensitive detection of the translocation of bacterial products. The data suggest that circulating NOD2 agonist contributes to further enhance the stress response following surgery.