Evaluation of the Serum Soluble Fractalkine as a Biomarker of Pulmonary Fibrosis in Systemic Sclerosis

Systemic Scleroderma (SCS) is an autoimmune disease characterized by vascular involvement, a dysimmune condition, cutaneous and visceral fibrosis. Interstitial lung disease (ILD) affects 75% of SSc patients and is the leading cause of death in SSc. No diagnostic or prognostic biomarkers of SSc-associated ILD have been validated to date. The search for such a serum biomarker is essential to assess the severity of these patients and to help the therapeutic management. We have shown that soluble fractalkine is elevated in SSc patients, especially in SSc patients with ILD. The fractalkine is both an endothelial adhesion molecule and a chemokine that binds to the CX3CR1 receptor expressed by immune populations. It would thus reflect the vasculopathy and inflammation that lead to the fibrosing pulmonary involvement of this disease. Objectives and means: We aim to perform a low-risk interventional biomedical research which main objective is the quantitative evaluation of soluble fractalkine in SSc patients with ILD in comparison with SSc patients without ILD. This epidemiological, explanatory, analytical, single-center study will comprise three groups: 1 / SSc without ILD (control group in the context of SSc), 2/ SSc with ILD and 3/ patients with idiopathic pulmonary fibrosis (IPF) (control group of the ILD). Secondary objectives are evaluation of: 1 / fractalkine levels in the IPF, 2 / correlations between fractalkine levels and severity of ILD and of SSc disease over time, 3 / correlations between fractalkine and 2 other biomarkers: KL-6 (marker of pulmonary fibrosis) and soluble CD146 (sCD146, marker of vasculopathy), 4 / predictive values of the decline in lung function of these 3 markers.