17th International Mass Spectrometry Conference :: Prague, 2006
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|Presentation date:||Thu, Aug 31, 2006|
|Presentation time:||13:30 – 15:00|
David Touboul1, Sandrine Roy2, Dominique P. Germain3, Pierre Chaminade2, Alain Brunelle1, Olivier Laprevote11 ICSN-CNRS, Gif-sur-Yvette, France
Correspondence address: David Touboul, ICSN-CNRS, Mass Spectrometry Laboratory, Avenue de la Terrasse, Gif-sur-Yvette, 91198 France.
Keywords: Imaging; Lipid; MALDI; Secondary Ion Imaging.
Novel aspect: Complementarity of MALDI-TOF and cluster TOF-SIMS biological imaging techniques coupled with structural analysis (MALDI MS/MS and PSD-TOF-SIMS).
Fabry disease is a X-linked disorder of the glycosphingolipid metabolism, in which a partial or total deficiency of a lysosomal enzyme, the α-galactosidase A, results in the progressive accumulation of neutral glycosphingolipids (globotriaosylceramide (Gb3) and digalactosylceramide (Ga2)) in most tissues, such as skin or kidneys. MALDI 1 and cluster-SIMS 2 offer the unique possibility to access simultaneously to the distribution of numerous compounds on a thin tissue section. The present work describes the application of these both innovative approaches for the characterization of the accumulated lipids on cutaneous and renal tissue sections from different Fabry patients, using a MALDI-TOF and a TOF-SIMS fitted with a bismuth cluster ion source.3 PSD-TOF-SIMS4 and MALDI MS/MS experiments were also performed for structural identification.
MALDI images of cutaneous sections showed the possibility to obtain spatial distribution of each glycosphingolipid molecular species. At a lateral resolution of 50 µm, all the maps display exactly the same accumulation areas in the derma and hypodermis. The structures of the glycosphingolipids were assessed by MS/MS. A control experiment confirmed the absence of Ga2 or Gb3 signals on the cutaneous biopsies from healthy volunteers. TOF-SIMS signals were very weak but confirmed the Ga2 or Gb3 distribution at a micrometer scale.
Renal biopsies were too small (200 µm), regarding to the laser spot size (50 µm), to acquire MALDI-TOF images. In that case, TOF-SIMS proved to be an excellent alternative due to the 1 Ám focus of the bismuth cluster ion beam. Intense signals of glycosphingolipids, correlated with an end-stage renal disease, were recorded in structures having a diameter of a few tens of micrometers, in the cortical and medullar parts of the kidney. Moreover, TOF-SIMS images revealed a colocalization of the intact Ga2 and Gb3 with vitamin E and cholesterol derivative compounds. The chemical structures were confirmed by PSD-TOF-SIMS experiments carried out directly on the tissue sections. Vitamin E is well-known for its antioxidant activity, preventing oxidative events, which are known to occur in the Fabry disease. In fibroblasts isolated from Fabry patients, Ga2 accumulation has been linked to high cholesterol levels. TOF-SIMS imaging confirmed these prior results directly on tissue sections and cholesterol sulfate is known to be involved in the formation of the epidermal barrier and in the keratinocyte differentiation.
1. M. Stoeckli, P. Chaurand, D. E. Hallahan and R. M. Caprioli, Nat. Med. 7, 493 (2001).
2. A. Brunelle, D. Touboul and O. Laprevote, J. Mass Spectrom. 40, 985 (2005).
3. D. Touboul, F. Kollmer, E. Niehuis, A. Brunelle and O. Laprevote, J. Am. Soc. Mass Spectrom. 16, 1608 (2005).
4. D. Touboul, A. Brunelle and O. Laprevote, Rapid Commun. Mass Spectrom. 20, 703 (2006).