The “History” of Desmosines: Forty Years of Debate on the Hypothesis That These Two Unnatural Amino Acids May Be Potential Biomarkers of Chronic Obstructive Pulmonary Disease

Abstract

Desmosine and isodesmosine (collectively known as desmosines), two unnatural amino acids unique to mature elastin in humans, have been widely discussed as being potential biomarkers of disorders, which involve connective tissue and whose clinical manifestations result in elastin degradation. In particular, experimental data accumulated over the last 40 years have demonstrated that patients with chronic obstructive pulmonary disease (COPD) excrete higher amounts of urinary desmosines than healthy controls. Based on this evidence, it has been speculated by several authors that these cross-links may be potential biomarkers of COPD with clinical significance. Nevertheless, a strict correlation between the amount of these amino acids and the severity of the disease still has to be demonstrated. For this reason, the debate on the opportunity to consider desmosines as biomarkers of COPD is still open, and the development of sophisticated methods aimed at obtaining very precise measurement of their concentration is still considered technically challenging. The aim of this chapter is to trace the history of this debate through the presentation and discussion of a large number of articles dealing with the detection and quantification of desmosines in different biological fluids, from early years until the present.