Looking for markers circulating in the blood

Within the framework of a new study recently published in the Journal of Nuclear Medicine (1), Natzi Sakalihasan, Roland Hustinx and Alain Colige focused on the cells and molecules associated with areas of high metabolic activity in abdominal aortic aneurysms. The objective of this work was to identify circulating biomarkers that would convey the presence of an unstable aneurysm. “In the present study”, explains Alain Colige, “we had the opportunity to compare human samples from patients with a negative or positive result from the PET-CT. In these latter subjects, we analysed components of the aortic wall in both areas of high and low metabolic activity". Work on these different types of samples would allow researchers to pinpoint the cells and molecules that were likely to cause the rupture of the aneurysm.

At LBTC, Audrey Courtois, a doctoral student supervised by Betty Nusgens, analysed the variation in the abundance of RNA messengers in order to determine if there was a correlation between the results obtained by the imaging technique (PET-CT) and the presence of specific molecules in the samples of aortic wall taken from the areas of high metabolic activity in the aneurysm. “We wanted to see if some molecules were expressed more in these areas and if their presence could serve as a marker for the risk level of the aneurysm", Alain Colige continues.

The analysis of the samples thus enabled researchers to confirm the presence of large infiltrates of inflammatory cells in places where metabolic activity was particularly high. At the same time, it allowed them to also identify the enzymes produced by these cells, responsible for the deterioration of the aortic wall.  

Systematic screening in Liège soon

The analyses of Alain Colige’s team have also shown that the expression of certain genes linked to the remodelling and maintenance of the aortic wall is different in aneurysmal areas with significant metabolic activity. Furthermore, changes in the structure and composition of the blood vessel’s wall have been revealed. “For instance, in these areas, there is loss of smooth muscle cells, responsible for the blood vessel's mechanical activity.  Moreover, part of the collagen present in this area isn’t typical of vascular walls but rather of cartilage!", the researchers stress. While the exact meaning of these changes is still unknown today, the authors of this study strongly suspect that they contribute to the weakening of the aortic wall before rupture.

As regards the markers indicating the level of risk of abdominal aortic aneurysms, the scientists have pinpointed potential candidates. This work will be the subject of a future publication...

In parallel to this research work, Professor Natzi Sakalihasan will soon launch a systematic screening campaign for AAA among the population of Liège, with the collaboration of the Department of Cardiovascular Surgery at Liège’s CHU and the Aneurysmal Pathology Foundation (APF) which is funding this initiative. A mobile medical team will soon be visiting the communes of the Province of Liège to roll it out.

(1) Audrey Courtois, Betty V. Nusgens, Roland Hustinx, Gauthier Namur, Pierre Gomez, Joan Somja, Jean-Olivier Defraigne, Philippe Delvenne, Jean-Baptiste Michel, Alain C. Colige and Natzi Sakalihasan.18F-FDG Uptake Assessed by PET/CT in Abdominal Aortic Aneurysms Is Associated with Cellular and Molecular Alterations Prefacing Wall Deterioration and Rupture. J Nucl Med. 2013 Oct;54(10):1740-1747. Epub 2013 Sep 5.