Urinary desmosine as a biomarker in acute lung injury

Abstract

Acute lung injury (ALI) is a complex disorder associated with an acute inflammatory response thought to contribute to tissue injury. Desmosine, a cross-linking amino acid present in elastin, is released during matrix degradation and cleared by the kidney. Results from animal models and human disease studies have suggested that ALI is associated with the release of desmosine, resulting in increased urinary desmosine. A radioimmunoassay was used to monitor urinary desmosine levels over 10 days in ten patients with ALI. The concentration of desmosine was measured with and without acid hydrolysis. Baseline urinary desmosine was increased in two of ten patients. The concentration of desmosine at baseline did not appear to be related to age, gender, neutrophil elastase (NE)/α₁-antiprotease complex concentration or P_aO₂/F_iO₂ ratio. No meaningful changes in desmosine levels were noted after removal from mechanical ventilation. Baseline desmosine concentrations did not appear to correlate with the risk of death. The limited sensitivity, predictive correlations and dynamic modulation would suggest that urine desmosine has a limited role as a biomarker for ALI. Hydrolysis of urine samples appears necessary for optimal measurement of urine desmosine.

Keywords: :

• Desmosine
• acute lung injury
• acute respiratory distress syndrome
• neutrophil elastase

Acknowledgements

The study was funded by Eli Lilly and Co., Indianapolis, IN, USA. The authors acknowledge the essential contributions of Dr Robert Konrad, for advice, Mark Willey and Daphne Farrington, for assistance validating the assay, Ed Legan, for assistance developing the tracer, and Julie Kaster, for help setting up the study.