202 S. Viglio et al. J. Sep. Sci. 2007, 30, 202 – 213

Simona Viglio1 Review Laura Annovazzi1 Maurizio Luisetti2 Jan Stolk3 Progress in the methodological strategies for the Begoa Casado4 Paolo Iadarola1 detection in real samples of and isodesmosine, two biological markers of elastin

1Dipartimento di Biochimica “A. degradation Castellani”, Universit di Pavia, Italy are crosslinking amino acids unique to mature elastin in humans. 2 Laboratorio di Biochimica e Owing to this unicity, they have been discussed as potentially attractive indicators Genetica, Clinica di Malattie of connective tissue disorders whose clinical manifestations are mostly the result of dell'Apparato Respiratorio, IRCCS Policlinico San Matteo, elastin degradation. This review covers advances in immunochemical, chromatogra- Pavia, Italy phic, and electrophoretic procedures applied in the last 25 years to detect and quan- 3Department of Pneumology, titate these crosslinks in a variety of biological samples. Recent applications of CE Leiden University Medical with LIF detection (CE-LIF) for investigating the content of desmosines in different Center, Leiden, The Netherlands fluids will also be discussed. 4Swiss Federal Institute of Technology ETH, Institute for Keywords: Biological fluids / Biomarkers / Desmosine / Isodesmosine / Molecular Systems Biology, Received: July 5, 2006; revised: August 28, 2006; accepted: August 30, 2006 Zrich, Switzerland DOI 10.1002/jssc.200600260

1 Introduction Owing to this unicity, desmosines have been discussed as potentially attractive indicators of connective tissue dis- Three scientists (J. Thomas, F. Eldsen, and M. Partridge) orders whose clinical manifestations are mostly the result from the University of Cambridge (UK) have pioneered of elastin degradation. In fact, given that peptides con- the research on crosslinkages in elastin. In fact, in 1963, taining the desmosines derived from the destruction of they published the first reports on the isolation of two elastic fibers are quantitatively excreted in the urine, new amino acids that were named desmosine and isodes- their determination may provide a measurement of body mosine [1, 2], obtained as the products of the acid hydroly- elastin destruction [9–12]. Obviously, the same determi- sis of purified elastin from bovine ligamentum nuchae. nation may help in the definitive evaluation of any thera- On the basis of physical and chemical procedures that peutic agent, by showing the effectiveness (or not) of included proton magnetic resonance studies, they were agents with potential in reducing the elastin breakdown also able to provide a structure, although partial, for both process [13–15]. The fact that detection of desmosines compounds [2, 3]. A few years later, Anwar and Oda [4] may represent an indirect measurement of extracellular studied the biosynthesis of these two amino acids by matrix degradation or of elastase activity in several dis- 14 incorporating uniformly labeled - C in cultures of eases with high morbidity and mortality provides the chicken embryo aortas. The results of their investigations rationale for understanding why so many efforts have provided evidence that four condense to form des- been devoted to achieve their determination in biological mosine or isodesmosine, strongly supporting the view fluids. Chronic obstructive pulmonary disease (COPD), a forwarded by other authors who had previously hypothe- class of disorders characterized by massive destruction of sized the same mechanism of formation [5, 6]. It is now the elastic fibers of the alveoli [16–19] and pseudox- well established that these compounds, whose structures anthoma elasticum (PXE), a rare heritable disorder of con- are shown in Fig. 1, are polyfunctional crosslinking nective tissue, whose clinical manifestations are the amino acids unique of mature elas