AB0083 ADIPONECTIN STIMULATES PRO-INFLAMMATORY CYTOKINE PRODUCTION BY PERIPHERAL BLOOD MONONUCLEAR CELLS FROM PATIENTS WITH EARLY UNTREATED RHEUMATOID ARTHRITIS
Authors: Yuan Zhang, Jonathan Aldridge, Anna-Carin Lundell, Anna Rudin, Cristina Maglio
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> The pathogenesis of rheumatoid arthritis (RA) involves the action of immune cells and fibroblast-like synoviocytes (FLS). Adiponectin, an adipokine produced mainly by adipocytes, is elevated in serum of RA patients compared to healthy controls; moreover, synovial fluid from RA subjects has higher levels of adiponectin compared to controls with osteoarthritis<sup>1,2</sup>. Adiponectin induces the production of pro-inflammatory cytokines, such as interleukin 6 (IL-6) and IL-8, by FLS from RA patients <sup>3,4</sup>. However, it remains unclear whether the response to adiponectin in terms of cytokine production is different in immune blood cells from healthy donors compared to RA patients; moreover, it is not known if FLS from healthy subjects can also produce pro-inflammatory cytokines upon adiponectin stimulation. <h3>Objectives:</h3> The study aims to analyse if adiponectin induces pro-inflammatory cytokine production by peripheral blood mononuclear cells (PBMCs) from both early RA patients and healthy controls. We also aim to study whether adiponectin induces pro-inflammatory cytokine production by FLS from healthy subjects. <h3>Methods:</h3> PBMCs were isolated from whole blood obtained from 5 healthy donors and 3 early untreated newly diagnosed RA patients using Ficoll-Paque PLUS. FLS were isolated from synovial tissue obtained from 3 healthy donors after knee surgery due to injury. Healthy FLS were cultured in Dulbecco's Modified Eagle Medium (DMEM GlutaMAX) supplemented with 10% FBS, 1% Penicillin-streptomycin and 0.5% Gentamycin. Harvested PBMCs and FLS were resuspended in X-VIVO 15 serum-free hematopoietic cell medium and stimulated with different doses of human recombinant adiponectin (1, 5 and 10 μg/ml), and the culture media were collected at different time points. Concentrations of IL-6, IL-8 and TNF-α were measured with ELISA. <h3>Results:</h3> Unstimulated PBMCs from early RA patients produced higher levels of IL-6 compared to healthy subjects (P&lt;0.001). In healthy controls, both the production of IL-6 and TNF-α was higher in PBMCs stimulated with adiponectin compared to unstimulated PBMCs (n=5, P&lt;0.01 for IL-6 and P&lt;0.01 for TNF-α). Likewise, the production of both IL-6 and TNF-α was higher in PBMCs from early-RA patients after stimulation with adiponectin compared with unstimulated PBMCs (n=3, P&lt;0.01 for IL-6 and P=0.03 for TNF-α) in a dose- and time-dependent manner. After stimulation with adiponectin, levels of IL-6, but not TNF-α, were higher in PMBCs from subjects with early RA compared to healthy controls (P&lt;0.01). Adiponectin stimulation did not induce IL-8 production from PBMCs from either healthy donors or RA patients. Adiponectin was able to induce the production of IL-6 and IL-8 by FLS isolated from heathy donors (n=3, P=0.03 for IL-6 and P=0.02 for IL-8), but not TNF-α. <h3>Conclusion:</h3> Our results show that adiponectin induces the production of IL-6 and TNF-α from PBMCs from both healthy subjects and patients with RA and that adiponectin is able to stimulate the production of IL-6 and IL-8 by FLS isolated from healthy subjects. Those results suggest that adiponectin may play a role in the pathogenesis of RA. <h3>References</h3> [1] Laurberg TB, et al. Plasma adiponectin in patients with active, early, and chronic rheumatoid arthritis who are steroid- and disease-modifying antirheumatic drug-naive compared with patients with osteoarthritis and controls. J Rheumatol2009 [2] Tan W, et al. High adiponectin and adiponectin receptor 1 expression in synovial fluids and synovial tissues of patients with rheumatoid arthritis. Semin Arthritis Rheum2009 [3] Tang CH, et al. Adiponectin enhances IL-6 production in human synovial fibroblast via an AdipoR1 receptor, AMPK, p38, and NF-kappa B pathway. J Immunol2007 [4] Kitahara K, et al. Adiponectin stimulates IL-8 production by rheumatoid synovial fibroblasts. Biochem Biophys Res Commun2009 <h3>Disclosure of Interests:</h3> Yuan Zhang: None declared, Jonathan Aldridge: None declared, Anna-Carin Lundell: None declared, Anna Rudin Grant/research support from: I have received research grants från AstraZeneca (2017-2018), Consultant for: I was paid consultant för AstraZeneca (2015-2018), Cristina Maglio: None declared