Influence of Acute Respiratory Distress Syndrome (ARDS) and Severe Sepsis on sRAGE Levels in ICU Patients

Overview

sRAGE, the soluble form of the receptor for advanced glycation end products, is a novel marker of alveolar epithelial type I cell injury, but is also involved in acute systemic inflammation. The purpose of this observational prospective study is to determine whether sRAGE could be used in an ICU setting as a potential diagnostic and prognostic marker during ALI/ARDS, regardless of associated severe sepsis or septic shock.

BACKGROUND: The receptor for advanced glycation end products (RAGE was recently identified as a promising new marker of alveolar type I cell injury. RAGE is a member of the immunoglobulin superfamily that acts as a multiligand receptor and is involved in propagating inflammatory responses. While the precise function of RAGE remains unclear, the elevated levels of RAGE, and its soluble isoform sRAGE, correlate with severity of ALI/ARDS in human and animal studies, and RAGE levels could reflect impaired alveolar fluid clearance. Thus, it is possible that elevated levels of RAGE in ALI/ARDS derive in part from RAGE's role in systemic inflammatory cascades rather than purely from its release from alveolar type I cells. DESIGN NARRATIVE: This observational prospective clinical study will describe and compare sRAGE levels in the alveolar edema fluid and in the plasma from ICU patients enrolled within the first 24 hours after onset of ALI/ARDS and/or severe sepsis/septic shock, and from patients under mechanical ventilation (control group). Edema fluid and plasma samples will be collected simultaneously on day 1, day 3, day 6, and day 28 (or at ICU discharge), in order to describe kinetics of evolution of sRAGE levels. Undiluted pulmonary edema fluid samples will be collected in intubated patients only, and blood samples will be gathered from an indwelling arterial catheter. The concentrations of sRAGE will be measured in duplicate by ELISA.

Conditions