IDENTIFICATION OF NOVEL BIOMARKERS OF DISEASE ACTIVITY IN SYSTEMIC AUTOIMMUNE DISEASES THROUGH NEXT GENERATION PROTEOMICS

BackgroundSystemic autoimmune diseases such as Rheumatoid Arthritis (RA) and Systemic Lupus Erythematosus (SLE) are characterised by aberrant autoimmune and inflammatory processes, which are directly associated with the development and progression of these disorders. Novel biomarkers associated with the severity of these diseases are needed to better characterise and monitor their progression as well as to develop new and more effective therapeutic strategies.ObjectivesTo identify common and distinctive novel biomarkers of disease activity in SLE and RA using high-throughput proteomics.MethodsSerum samples from 170 patients, including 100 RA and 70 SLE, were profiled with the disruptive technology “proximity extension assay” from Olink, which analysed the levels of a panel of 92 inflammatory proteins. The methodology involves protein-specific antibodies linked to DNA-encoded tags which are amplified by RT-PCR.Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and Disease activity score in 28 joints (DAS28) were assessed in SLE and RA patients respectively to characterise the disease status of all patients.Pearson´s correlation studies were performed using molecular information and clinical data to identify biomarkers of disease activity in each disease (FDR<0.05). Gene ontology enrichment analysis were performed to gain insight about the biological meaning of the biomarker signatures.ResultsSLE patients were characterised by an average SLEDAI of 5.2 (min-max, 0-29) while RA patients exhibited an average DAS28 of 4.6 (min-max, 1.5-7.8).Correlation studies revealed 14 proteins directly associated with SLEDAI in SLE patients, including ADA, CCL25, CD40, CDCP1, CSF1, FGF21, FLT3L, IL10RB, LAP-TGFB1, MMP20, OPG, SLAMF1, TNFRSF9 and uPA. The subsequent enrichment analysis revealed that those molecules were associated with pathways such as cytokine-cytokine receptor interaction and MAPK signalling.In RA patients 26 proteins were directly correlated with DAS28 including AXIN1, BNGF, CASP8, CCL23, CD40, CSF1, CXCL9, CXCL10, CXCL11, EN-RAGE, FGF23, GDNF, HGF, IL10RB, IL15RA, IL6, IL7, IL19, IL20, IL33, LAP-TGFB, MCP3, OPG, SLAMF1, TNFRSF9 and TWEAK which were enriched in biological pathways such as chemokine-chemokine receptor interaction and JAK-STAT signalling.The levels of five pro-inflammatory mediators were commonly associated with the disease activity status of both diseases such as IL10RB (receptor for IL10, IFNL2 and IFNL3), CSF1 (macrophage colony-stimulating factor 1 receptor), SLAMF1 (Signaling lymphocytic activation molecule), TNFRSF9 and OPG (both, tumor receptor factor ligand superfamily members), suggesting a key common role of these molecules in the underlying molecular mechanisms associated with both diseases.ConclusionThe analysis of the inflammatory profile of systemic autoimmune diseases with novel high-throughput proteomic technologies in non-invasive samples allow the identification of relevant biomarkers associated with the disease activity, which can improve the monitoring of the disease and the development of new targeted therapies.AcknowledgementsSupported by ISCIII (PI21/005991 and RICOR-RD21/0002/0033) co-financed by FEDER, Fundacion Andaluza de Reumatología (FAR) and Consejería de Conocimiento, Investigación y Universidad de la Junta de Andalucía (P20_01367).Disclosure of InterestsNone declared