THU0348 Localisation of IL-20 in Synovium From Patients with Psoriatic Arthritis
Authors: M. Jackerott, J. Mandelbaum, L.-L. Kruse, N. Vendel, E. M. Bartels, M. Andersen, C. H. Jensen, N. H. Søe, H. Bliddahl, J. Rømer
Journal: Annals of the Rheumatic Diseases (2013)

<h3>Background</h3> Interleukin-20 (IL-20) is a pro-inflammatory cytokine that belongs to the IL-10 family of cytokines. Increased expression of IL-20 is found in autoimmune diseased tissue, such as lesional psoriatic skin and synovium from patients with rheumatoid arthritis (RA). A neutralising anti-IL-20 monoclonal antibody (NNC0109-0012) has shown efficacy in phase 2A clinical testing in patients with RA. <h3>Objectives</h3> The aim of the present study is to investigate the expression of IL-20 in synovial samples from patients with psoriatic arthritis (PsA). <h3>Methods</h3> Three synovial biopsies were obtained during synovectomy from the joints of the hands from patients with PsA. Five 'normal' synovial biopsies were obtained during surgical treatment of patients with non-inflamed shoulder disorders, such as subacromial impingement. Samples from eight synovial biopsies from patients with PsA and seven 'normal' synovial biopsies were obtained during joint surgery and represented as 2-mm spots on tissue micro array sections. All synovial samples were formalin-fixed and paraffin-embedded. The localisation of IL-20 was analysed in synovial sections by immunohistochemistry using a rabbit polyclonal anti-IL-20 antibody (2313b), and immunoreactivity was visualised with tyramide signal amplification and immunoperoxidase. The specificity of the antibody was verified with IL-20-transfected cells and using antigen pre-absorption and pre-immune IgG control. <h3>Results</h3> IL-20 was detected in 6 out of 11 synovial samples from patients with PsA. In 4 of these samples, IL-20 was present in both synovial lining and sublining. In 2 samples, IL-20 was present in the synovial lining, but not in the sublining. The three synovial samples obtained by synovectomy were all positive for IL-20, while IL-20 positive cells were observed in only 3 out of the 8 synovial samples obtained during joint replacement surgery. A few IL-20 positive cells were detected in the lining in one 'normal' synovial sample, while 11 out of the 12 'normal' samples were negative for IL-20. The localisation pattern of IL-20 in synovial tissue from patients with PsA was similar to what we have previously observed in synovium from patients with RA. The IL-20 immunoreactivity was completely eliminated following antigen pre-absorption of the antibody. <h3>Conclusions</h3> The results demonstrate that IL-20 is differentially expressed in synovial samples from patients with PsA compared with 'normal' synovial tissue, and that the distribution of IL-20 in synovium from patients with PsA and RA appears to be similar. <h3>Disclosure of Interest</h3> M. Jackerott Shareholder of: Novo Nordisk A/S, Employee of: Novo Nordisk A/S, J. Mandelbaum Shareholder of: Novo Nordisk A/S, Employee of: Novo Nordisk A/S, L.-L. Kruse Shareholder of: Novo Nordisk A/S, Employee of: Novo Nordisk A/S, N. Vendel: None Declared, E. Bartels: None Declared, M. Andersen Employee of: Novo Nordisk A/S, C. Jensen: None Declared, N. Søe: None Declared, H. Bliddahl: None Declared, J. Rømer Shareholder of: Novo Nordisk A/S, Employee of: Novo Nordisk A/S