Synovial Fluid and Plasma Selenium, Copper, Zinc, and Iron Concentrations in Patients with Rheumatoid Arthritis and Osteoarthritis

Background:Rheumatoid arthritis (RA) is characterized by chronic, uncontrolled joint inflammation and tissue destruction. Macrophages are thought to be key mediators in both the initiation and perpetuation of this pathology.1,2The RA synovium contains a complex inflammatory milieu that can stimulate macrophage-dependent production of proinflammatory cytokines through multiple signaling pathways.1,2Existing evidence indicates that toll-like receptors (TLRs) and interleukin-1 receptors (IL-1R) along with their agonists, damage-associated molecular patterns (DAMPs) and IL-1β, are highly expressed in RA joints and are important mediators of synovial macrophage activation and proinflammatory cytokine production.1-9IRAK4 (interleukin-1 receptor-associated kinase 4) is a serine/threonine kinase that facilitates TLR and IL-1R signaling in many cell types, including macrophages.10IRAK4 inhibition represents an opportunity to reduce proinflammatory cytokine production in the joints of patients with RA.Objectives:To investigate the effect of a highly selective IRAK4 inhibitor on proinflammatory cytokine production from human macrophages stimulated with synovial fluid from patients with RA.Methods:Primary human monocytes from 2 independent donors were differentiated for 6 days with granulocyte-macrophage colony-stimulating factor (GM-CSF) to generate human monocyte-derived macrophages (hMDMs). hMDMs were then pretreated with an IRAK4 inhibitor for 1 hour and subsequently stimulated for 24 hours with RA synovial fluid from 5 patients. Culture supernatants were then assessed for secretion of proinflammatory cytokines by MesoScale Discovery.Results:RA synovial fluid stimulation of hMDMs resulted in the production of several proinflammatory cytokines, including IL-6, IL-8, and TNFα. Pretreatment of hMDMs with an IRAK4 inhibitor resulted in the dose-dependent inhibition of IL-6, IL-8, and TNFα production, with an average EC50± SD of 27 ± 31, 26 ± 41, and 28 ± 22 nM, respectively. Maximal percent suppression ± SD of IL-6, IL-8, and TNFα were 76 ± 8.8, 73 ± 15, and 77 ± 13, respectively. To evaluate the specific IRAK4-dependent signaling pathways mediating this response, hMDMs were pretreated with inhibitors of TLR4 (TAK242) and IL-1R (IL-1RA) prior to stimulation with RA synovial fluid. Both TAK242 and IL-1RA inhibited proinflammatory cytokine production. For TAK242, maximal percent suppression ± SD of IL-6, IL-8, and TNFα were 39 ± 25, 48 ± 24, and 50 ± 21, respectively. For IL-1RA maximal percent suppression ± SD of IL-6, IL-8, and TNFα were 18 ± 18, 20 ± 23, and 16 ± 18, respectively. The broad range of inhibition across each stimulation highlights the complexity and variability in the signaling pathways mediating proinflammatory cytokine production from hMDMs stimulated with RA synovial fluid, but demonstrates that RA synovial fluid can stimulate proinflammatory cytokine production in hMDMs, at least partly, through IRAK4-dependent pathways.Conclusion:This work demonstrates that IRAK4 inhibition can suppress proinflammatory cytokine production from macrophages stimulated with synovial fluid from patients with RA and supports a potential pathophysiological role for IRAK4 in perpetuating chronic inflammation in RA.References:[1]Smolen JS, et al.Nat Rev Dis Primers.2018;4:18001.[2]Udalova IA, et al.Nat Rev Rheumatol.2016;12(8):472-485.[3]Joosten LAB, et al.Nat Rev Rheumatol.2016;12(6):344-357.[4]Huang QQ, Pope RM.Curr Rheumatol Rep.2009;11(5):357-364.[5]Roh JS, Sohn DH.Immune Netw.2018;18(4):e27.[6]Sacre SM, et al.Am J Pathol.2007;170(2):518-525.[7]Ultaigh SNA, et al.Arthritis Res Ther.2011;13(1):R33.[8]Bottini N, Firestein GS.Nat Rev Rheumatol.2013;9(1):24-33.[9]Firestein GS, McInnes IB.Immunity.2017;46(2):183-196.[10]Janssens S, Beyaert R.Mol Cell.2003;11(2):293-302.Disclosure of Interests:Adam Yadon Employee of: Gilead, Debbie Ruelas Employee of: Gilead, Gundula Min-Oo Employee of: Gilead, James Taylor Employee of: Gilead, Matthew R. Warr Employee of: Gilead

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POS0399 TMT-BASED QUANTITATIVE PROTEOMICS ANALYSIS OF SYNOVIAL FLUID-DERIVED EXOSOMES IN RHEUMATOID ARTHRITIS, AXIAL SPONDYLOARTHRITIS, GOUT AND OSTEOARTHRITIS

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2021-eular.3607 ◽

2021 ◽

Vol 80 (Suppl 1) ◽

pp. 428.3-429

Author(s):

Y. Liu ◽

Y. Huang ◽

Q. Huang ◽

Z. Huang ◽

Z. Li ◽

...

Keyword(s):

Rheumatoid Arthritis ◽

Cluster Analysis ◽

Synovial Fluid ◽

Pathway Analysis ◽

Quantitative Proteomics ◽

Axial Spondyloarthritis ◽

Kegg Pathway ◽

Hierarchical Cluster ◽

Kegg Pathway Analysis ◽

Differential Proteins

Background:The pathogeneses of the joint diseases rheumatoid arthritis (RA), axial spondyloarthritis (axSpA), gout, and osteoarthritis (OA) are still not fully elucidated. Exosomes in synovial fluid (SF) has a critical role in the pathogenesis of arthritis. None of study has compared the proteomics of SF-derived exosomes in RA, axSpA, gout and OA.Objectives:To compare the proteomics of SF-derived exosomes in RA, axSpA, gout and OA based on tandem mass tags (TMT) labeled quantitative proteomics technique.Methods:SF-derived exosomes was isolated from RA, axSpA, gout and OA patients by the Exoquick kit combined ultracentrifugation method. TMT labeled quantitative proteomics technique was used to compare the proteomics of SF-derived exosomes. Volcano plot, hierarchical cluster, Gene Ontologies (GO), Encyclopedia of Genes and Genomes (KEGG) pathway analysis were conducted.Results:A total of 1678 credible proteins were detected. With the cut off criteria of |log2 (fold-change)| ≥1.2 and p-value <0.05, 267 (140 up-regulated and 127 down-regulated)differential proteins were found in OA vs gout, 291 (179 and 112) in axSpA vs OA, 515 (109 and 406) in RA vs axSpA, 298 (191 and 107) in axSpA vs gout, 462 (160 and 302) in RA vs gout, 536 (170 and 366) in RA vs OA. GO analysis showed that the biological progress of differential proteins were mainly enriched in the “immune response”. Regarding the molecular function, the differential proteins mainly mediated “antigen binding”. GO analysis of the cellular components indicated that most proteins were annotated as “extracellular exosomes”. KEGG pathway analysis demonstrated differential proteins were significantly enriched in “complement and coagulation cascades”. The hierarchical cluster analysis of the differential proteins in the four groups showed that Lysozyme C and Keratin were more abundant in gout, Hemoglobin and Actin-related protein 2/3 complex subunit 3 in OA, Sodium/potassium-transporting ATPase subunit alpha-1 and Immunoglobulin heavy constant delta in axSpA, Pregnancy zone protein and Stromelysin-1 in RA.Conclusion:The protein profiles of SF-derived exosomes in RA, axSpA, gout and OA patients were different. The differential proteins were the potential biomarkers of RA, axSpA, gout and OA.References:[1]Cretu D, Diamandis E P, Chandran V. Delineating the synovial fluid proteome: recent advancements and ongoing challenges in biomarker research.[J]. Critical reviews in clinical laboratory sciences, 2013,50(2):51-63.[2]McArdle A J, Menikou S. What is proteomics?[J]. Archives of disease in childhood. Education and practice edition, 2020.Figure 1.The hierarchical cluster analysis of differential proteins in axSpA, OA, Gout and RA.Disclosure of Interests:None declared

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