ABSTRACT
Background: To search for molecular biomarkers of pulmonary pathologies using non-invasive samples, such as urine, is of high clinical relevance. However, there are almost no proteomic studies using urine applied to respiratory diseases. Aim(s): To develop a biomarker discovery strategy using non-targeted proteomics in urine with applicability to different pulmonary diseases. Method(s): Urine samples were centrifuged and DTT treated to decrease uromodulin (THP). Low-THP samples were concentrated (ultrafiltration), ultracentrifugated, and exosome free urine was analysed using LC-MS/MS. GO terms/Pathway analyses were performed using STRING database. Result(s): Urine proteome (765 proteins) was enriched (FDR < 0.05) in proteins from different tissues, including respiratory system (N = 124), lung (N = 107), and immune system (N = 88). We detected an enrichment of relevant pathways for respiratory diseases, including several innate (e.g., TLR and NFkB pathways, complement system), and adaptive (e.g., interleukin signalling) immune system pathways. Some of these proteins have been previously studied in respiratory system disease (e.g., MPO, NAPSA, CHL1, FREM2, PLG), lower respiratory tract disease (e.g., NCAM1, MTOR, SERPINA1), viral infectious disease (e.g., ITIH4, CD209, CLEC4M, CD55), or specific pathologies such as coronavirus infection (e.g., ACE2, TMPRSS2), bronchiectasis (e.g., SAA1, SAA2, ELANE) or asthma (e.g., IGFALS, IGFBP7, HSPG2, DPP4, CD44, IL6R, MASP1). Conclusion(s): We have developed a protocol for the detection of proteomic biomarkers in urine. This proteome is enriched in proteins from the immune and respiratory systems, with a potential clinical and translational relevance.