Bronchoalveolar lavage proteomic analysis in pulmonary fibrosis associated with systemic sclerosis: S100A6 and 14-3-3ε as potential biomarkers

Objective: SSc is a rare severe connective tissue disorder. Its prognosis is mainly related to the development of pulmonary fibrosis (PF)-SSc and pulmonary arterial hypertension. No known therapy for PF-SSc modifies progressive lung fibrotic involvement. Research is therefore aimed at a deeper understanding of complex pathogenetic mechanisms and the possibility of new prognostic biomarkers and therapeutic targets. Methods: Towards the first of these aims, we conducted functional proteomic analysis of bronchoalveolar lavage samples from PF-SSc patients and smoker and non-smoker controls. Results: The differential expression pattern revealed by principal component analysis highlighted a specific protein profile of PF-SSc with respect to control samples, and enrichment analysis shed light on process networks involved in pathogenesis. The proteins identified are known to be involved in lung inflammation of PF-SSc-induced IL6 signalling, the complement system, innate immunity, Jak-STAT, the kallikrein-kinin system, blood coagulation, the immune response mediated by phagocytosis and phagosomes in antigen presentation. In particular, our MetaCore network suggested C3a, APOAI, 14-3-3e, SPFA2 and S100A6 as potential biomarkers; these are upstream molecules involved in lung fibrosis, innate immunity and vascular damage occurring in PF-SSc. Conclusion: This report provides a molecular overview of pathological processes in PF-SSc, pinpointing possible new disease biomarkers and therapeutic targets.