Evaluation of a RAGE ELISA in septic dogs

Matthew Lim

Sepsis describes life-threatening organ dysfunction caused by a dysregulated host response to infection. Unfortunately, improvements in our understanding of the immunopathogenesis of sepsis has not yet translated into a significant change in the diagnostic approach or therapeutic protocols in dogs or humans, as reflected by the substantial morbidity and mortality in both species. Recently, blocking the signal transduction pathway of the inflammation-perpetuating receptor of advanced glycation end-products (RAGE), has been identified as a promising therapeutic target in sepsis, with improved outcomes associated with decreasing the inflammatory surface membrane-bound form of RAGE (mRAGE) and increasing the protective soluble isoform of the protein (sRAGE) in mouse models. Based on these promising data, therapeutics to shift human and dog pro-inflammatory RAGE expression towards anti-inflammatory isoforms have been developed. However, prior to future clinical trials in septic dogs involving RAGE, the measurement of RAGE in dogs with sepsis must first be optimised, which was investigated in two studies comprising this thesis. Firstly, analytical validation of a canine RAGE ELISA was performed, which demonstrated sufficient intra-assay precision (CV <15%) and accuracy at all RAGE concentrations, and sufficient inter-assay precision (CV 7.8%) for high RAGE concentrations. However, the ELISA showed poor inter-assay precision at low and medium RAGE concentrations (CV 31.9% and 88.0% respectively). Secondly, a clinical validation study was performed, comparing RAGE concentrations among 5 groups of dogs: 45 healthy dogs, 14 with non-infectious systemic inflammatory response syndrome (nSIRS), 17 septic dogs, 9 dogs with infection but not meeting SIRS criteria, and 23 dogs that were sick but without SIRS or infection. Group median (Min-Max) RAGE concentrations in the five groups were as follows: (i) Healthy (42.1 pg/mL [0- 641.8]; (ii) nSIRS (176.8 pg/mL [5.2-4707.7]; (iii) Septic (238 pg/mL [0-910]; (iv) Infection (95.5 pg/mL [0-545.8]); and (v) Sick (47 pg/mL [0-1912.2]), with significant between-group differences in both median and distribution of RAGE concentrations between the healthy and sepsis groups (both P < 0.001). The distribution of RAGE concentrations was also significantly different between survivors and non-survivors (P = 0.042), demonstrating promise of RAGE as a negative prognostic indicator. Further studies investigating RAGE in septic dogs will provide greater clarity as to both its potential diagnostic biomarker, prognostic indicator, and therapeutic target.

Evaluation of a RAGE ELISA in septic dogs

Files and links (1)

Abstract

Details

Metrics