SAT0559 High Expression of Cyclooxygenase-2, Prostaglandin E2 and Prostaglandin E2 Receptor Ep4 in Zygapophyseal Joints of Patients with Ankylosing Spondylitis: Table 1
Authors: J. Bleil, H. Appel, R. Maier, J. Sieper, U. Syrbe
Journal: Annals of the Rheumatic Diseases (2014)

<h3>Background</h3> Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first-line treatment for patients with ankylosing spondylitis (AS). They are effective in reducing signs and symptoms, and increasing evidence suggests that their sustained use may also retard radiographic progression [1, 2]. The equal efficacy of cyclooxygenase (COX)-2 selective inhibitors in AS suggests that COX-2-dependent PGE<sub>2</sub> synthesis is involved in the pathogenesis of AS. <h3>Objectives</h3> We studied here the expression of COX-2 and PGE<sub>2</sub> and of the PGE<sub>2</sub> receptors EP<sub>2</sub> and EP<sub>4</sub> in zygapophyseal joints of AS patients. <h3>Methods</h3> COX-2, PGE<sub>2</sub>, EP<sub>2</sub> and EP<sub>4</sub> were determined by immunohistochemistry in zygapophyseal joints from 19 AS, 11 osteoarthritis patients (OA) and 12 autopsy controls (CO). COX-2<sup>+</sup>, PGE<sub>+</sub>, EP<sub>+</sub> and EP<sub>+</sub> cells were detected at four different sites: within hyaline cartilage, subchondral bone plate, fibrous tissue and subchondral bone marrow. <h3>Results</h3> Within the subchondral bone marrow, numbers of COX-2<sup>+</sup> and PGE<sub>+</sub> cells were higher in joints of AS patients compared to controls (p=0.0394, p=0.0138). The number of cells expressing EP<sub>2</sub> and EP<sub>4</sub> were also but non-significantly elevated in the bone marrow of AS patients (p=0.0630; p=0.0786). In contrast, we found in preliminary analysis very low expression of COX-2 within the cartilage, the subchondral bone and the subchondral fibrous tissue. Within the subchondral bone plate, numbers of PGE<sub>+</sub> and EP<sub>+</sub> cells were higher in AS (and OA) patients compared to controls (p&lt;0.05 for all), while no significant differences were seen within the cartilage comparing AS patients and controls. Comparably very high numbers of PGE<sub>+</sub> and EP<sub>+</sub> cells were detected within the fibrous tissue of AS and OA patients (p=0.1902, p=0.3726). <h3>Conclusions</h3> According to these data, COX-2 dependent PGE<sub>2</sub> synthesis is primarily seen in the subchondral bone marrow and elevated in AS patients, and might be the target site for drugs inhibiting COX-2. <h3>References</h3> Poddubnyy D, Rudwaleit M, Haibel H, Listing J, Marker-Hermann E, Zeidler H, et al. Effect of non-steroidal anti-inflammatory drugs on radiographic spinal progression in patients with axial spondyloarthritis: results from the German Spondyloarthritis Inception Cohort. Annals of the rheumatic diseases. 2012 Oct; 71(10):1616-1622. Wanders A, Heijde D, Landewe R, Behier JM, Calin A, Olivieri I, et al. Nonsteroidal antiinflammatory drugs reduce radiographic progression in patients with ankylosing spondylitis: a randomized clinical trial. Arthritis and rheumatism. 2005 Jun; 52(6):1756-1765. <h3>Disclosure of Interest</h3> None declared <h3>DOI</h3> 10.1136/annrheumdis-2014-eular.3576