Micellar Electrokinetic Chromatography with Laser Induced Detection and liquid chromatography tandem mass-spectrometry-based desmosine assays in urine of patients with Chronic Obstructive Pulmonary Disease: A comparative analysis

Free Urinary Desmosine and Isodesmosine as COPD Biomarkers: The Relevance of Confounding Factors

Background: Desmosine (DES) and isodesmosine (IDES) have been widely discussed as potential biomarkers of COPD. However, their clinical utility and validity remains unproven. Aim: This study aims to progress DES/IDES evaluation as a chronic obstructive pulmonary disease (COPD) biomarker by investigating its urinary excretion in a large sample cohort with respect to a) which factors influence DES/IDES levels in a population of healthy control individuals and COPD individuals; b) whether DES/IDES levels enable the differentiation between COPD individuals and healthy control individuals; c) whether DES/IDES can be used to differentiate between fast and slow decliners in lung function. Methods: Urinary DES and IDES were quantified in 365 individuals (147 healthy control individuals and 218 COPD individuals) from the Evaluation of COPD Longitudinally to Indentify Predictive Surrogate Endpoints (ECLIPSE) study (NCT00292552) by employing a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Results: Age, gender, body mass index (BMI) and smoking have a significant (p<0.05) influence on DES/IDES urinary excretion and need to be corrected for when investigating DES/IDES as a disease biomarker. Urinary DES/IDES allowed a statistically relevant differentiation (p<0.05) between stable COPD individuals and healthy control individuals, however, assay sensitivity and specificity were low (62% and 73%, respectively). Furthermore, urinary DES/IDES does not allow the differentiation of fast and slow decliners in lung function. Conclusions: The present results suggest that while urinary DES/IDES excretion is related to COPD, it is not a sensitive or specific biomarker for COPD diagnosis or prognosis.

Elastin degradation product isodesmosine is a chemoattractant for Pseudomonas aeruginosa

Previous studies have demonstrated that Pseudomonas aeruginosa PAO1 is chemotactic towards proteinogenic amino acids, however, the chemotaxis response of this strain towards non-proteinogenic amino acids and the specific chemoreceptors involved in this response are essentially unknown. In this study, we analysed the chemotactic response of PAO1 towards two degradation products of elastin, the lysine-rich, non-proteinogenic amino acids, desmosine and isodesmosine. We observed that isodesmosine, a potential biomarker for different diseases, served as a chemoattractant for PAO1. A screen of 251methyl-accepting chemotaxis proteins mutants of PAO1 identified PctA as the chemoreceptor for isodesmosine. We also showed that the positive chemotactic response to isodesmosine is potentially common by demonstrating chemoattraction in 12 of 15 diverse (in terms of source of isolation) clinical isolates, suggesting that the chemotactic response to this non-proteinogenic amino acid might be a conserved feature of acute infection isolates and thus could influence the colonization of potential infection sites.

The role of desmosines as biomarkers for chronic obstructive pulmonary disease

Since chronic obstructive pulmonary disease (COPD) has a progressive and major impact on health management, many aspects of this disorder, including development of effective and reliable biomarkers to monitor disease progression, are under intensive investigation. A huge amount of data, accumulated over the years, have provided solid evidence that two pyridinium-ring-containing amino acid isoforms, desmosine and isodesmosine (usually referred to as desmosines), unique to mature elastin in humans, are representative of the elastin breakdown occurring in chronic destructive disorders, such as COPD. This paper is aimed at providing a critical review of the methodological steps that have marked the progress in the detection of desmosines in biological fluids in health and disease, as well as the progress in the authors knowledge of desmosines' role in the pathophysiology of COPD. The authors have tried to emphasize that the suitability of desmosine as a biomarker for COPD increased over the years, as the techniques developed for its detection became progressively more sophisticated and precise. The authors conclude that desmosines, although not yet definitely proven, have nevertheless all the requisites to become a critical COPD biomarker.