Biomarkers of skin and lung fibrosis in systemic sclerosis

Introduction: Excessive fibrosis is the hallmark of systemic sclerosis (SSc) and numerous experts are investing efforts into identifying parameters that could predict disease course and prognosis. Here, we review the available and potential biomarkers of lung and skin fibrosis in SSc. Areas covered: Specific autoantibodies are important for the determination of clinical subsets of SSc, making them routine in clinical practice. Physical parameters, such as modified Rodnan skin score (mRSS) and pulmonary function tests are standardized in evaluating the skin and lung involvement. High resolution computed tomography is the gold standard for SSc-related interstitial lung disease (ILD) diagnostics, as well as progress evaluation. Nowadays, the main focus is on specific autoantibodies, various genetic pathways, and different cytokines. In addition to the profibrotic role of interleukin 6 and transforming growth factor-beta, newer studies stress on glycoprotein Krebs von den Lungen-6 (KL-6), surfactant protein-D (SP-D) and chemokine (C-C motif) ligand 18 (CCL18) as potential biomarkers of skin and lung fibrosis in SSc. Expert opinion: Skin and lung biomarkers in SSc frequently mirror the typical signs of fibrosis, overlapping sporadically. There is an urgent need for better diagnostic distinction and evaluation; therefore, further investigations are critical to establish more suitable biomarkers of SSc.