Background/Purpose: Antibodies and up-regulated cytokines and chemokines predate the onset of symptoms of rheumatoid arthritis (RA). The aims with this study was to identify pathways related to the early processes leading to RA development, and potential novel biomarkers, using multiple proteins analysis.

Methods: A case-control study was conducted within the Biobank of northern Sweden. Plasma samples from 118 pre-symptomatic individuals (207 samples, median predating time 4.1 years), 79 early RA patients and 74 matched controls were analysed. The levels of 122 unique proteins with acknowledged relation to autoimmunity were analysed using 153 antibodies in a bead-based multiplex system (FlexMap3D, Luminex Corp.). Data was analyzed using ANOVA, Random Forest and Network Enrichment analysis (NEA), on the basis of the ten most significantly differentially expressed proteins for each two-by-two group comparison, using the MSigDB collection of Hallmarks.

Results: There was high agreement between the different statistical methods for identifying the most significant proteins. Levels of 22 proteins differed significantly between pre-symptomatic individuals and controls, 93 between RA-patients and controls and one between pre-symptomatic individuals and RA after adjustment for multiple testing. The area under curve for proteins discriminating pre-symptomatic individuals from controls was 0.75, between pre-symptomatic individuals and RA 0.80 and between RA and controls 0.93. Of the 30 proteins with the highest discriminatory capacity 27 differed between pre-symptomatic individuals vs. controls (p< 1.9e-7 to 0.05), 29 between RA-patients and controls (p< 5.5e-26 to 1.7e-4) and 29 between pre-symptomatic individuals and RA (p< 7.4e-4 to 0.05). The Adipogenesis and Interferon alpha response hallmarks, included proteins involved in innate immunity, differentiated pre-symptomatic individuals from controls. Between pre-symptomatic individuals and RA-patients three hallmarks were identified, involving Apical Junction, Epithelial Mesenchymal Transition and TGF-β signaling including proteins suggestive of cell interaction, re-modulation and fibrosis. The Adipogenesis and Heme metabolism hallmarks differentiated RA-patients from controls.

Conclusion: We confirm the importance of Interferon alpha signaling as well as of lipids in the early phases of RA development. Network Enrichment Analysis provides a tool for a deeper understanding of molecules involved at different phases of the disease progression.

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/protein-profiling-and-network-enrichment-analysis-in-individuals-before-and-after-the-onset-of-rheumatoid-arthritis/