BREATHOMICS APPROACH TO INVESTIGATE SYSTEMIC SCLEROSIS USING THERMAL DESORPTION AND COMPREHENSIVE TWO-DIMENSIONAL GAS CHROMATOGRAPHY HIGH-RESOLUTION TIME-OF-FLIGHT MASS SPECTROMETRY

Abstract

Systemic sclerosis (SSc) is a chronic and heterogenous auto-immune disease of unknown origin characterized by fibrosis, inflammation, vascular damages, and involvement of internal organs. Organ involvement appears at the early stage of the disease[1,2]. Interstitial lung disease (ILD) is one of the most common types of pulmonary involvement, responsible for the disease severity, and leading to high morbidity and mortality. One of the challenges in SSc remains the early diagnosis of patients with a high risk of disease progression driving mortality[3]. There is an unmet need for biological markers enabling SSc early diagnosis, prognosis, disease progression monitoring, and improving patients’ classification for more targeted therapies. Ideally, new diagnostic methods for SSc should be simple, fast, accurate, and cost-effective. Comprehensive two-dimensional gas chromatography (GC×GC) has a great potential for exhaled breath analysis. The increased peak capacity and sensitivity of GC×GC, provided by the combination of two capillary columns of different stationary phases by means of a modulator, enable the chromatographic separation and detection of thousands of compounds from a complex matrix[4]. For this reason, we carried out an exploratory study on SSc[5]. Basically, breath samples were collected in 5L Tedlar® bags. Volatiles contained in the sampling bag were then transferred onto Tenax®GR/Carbopack™B thermal desorption tubes (Markes International Ltd., Llantrisant, UK) and finally released and separated into a Pegasus GC-HRT 4D (LECO Corporation, St Joseph, MI, USA) through a mid-polar Rxi-624SilMS (30 m × 0.25 mm × 1.4 μm) as first column (dimension) and a polar Stabilwax (2 m × 0.25 mm ×0.5μm) as second dimension. The exhaled breath of 32 patients and 30 healthy subjects was therefore analyzed. The high resolving power of this approach and the use of statistical models enabled the identification of 16 compounds discriminating SSC patients from healthy ones[5]. However, further investigations had to be held to reach a better disease classification. In fact, the biomarkers highlighted here could be related to the scarring (fibrosis) of the lungs making these non-specific to SSCs. The second phase of the study aims to go deeper in patient stratification. Three groups were investigated: 50 SSC patients, 50 SSC-fibrosis patients and 50 ILD ones. The samples were collected at Maastricht medical center and CHU of Liège. All samples were then analyzed in the OBiACHem lab. Currently, a classification model is under construction to stratify patients based on their fibrosis status. [1] E. Zanatta, V. Codullo, J. Avouac, Y.A.-J. bone spine, undefined 2020, Elsevier (2019). [2] O. Bonhomme, B. André, F. Gester, … D. de S.-, undefined 2019, Academic.Oup.Com (n.d.). [3] J. Guiot, M. Henket, B. Andre, M. Herzog, N. Hardat, M.S. Njock, C. Moermans, M. Malaise, R. Louis, Clin. Epigenetics 12 (2020). [4] D. Zanella, J. Focant, F.A. Franchina, Anal. Sci. Adv. 2 (2021) 213–224. [5] D. Zanella, J. Guiot, P.-H. Stefanuto, L. Giltay, M. Henket, F. Guissard, B. André, M. Malaise, J. Potjewijd, F. Schleich, R. Louis, J.-F. Focant, Anal. Bioanal. Chem. 2021 41314 413 (2021) 3813–3822