Characterization of synovial mast cells in knee osteoarthritis ...

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Nov 17, 2015 - 0e9), and numbers of mast cells (per 10 high-power fields) using double immunofluorescence for CD117 and tryptase. Average scores per ...
Osteoarthritis and Cartilage 24 (2016) 664e671

Characterization of synovial mast cells in knee osteoarthritis: association with clinical parameters e y, E. Yusuf y, B.J.E. de Lange-Brokaar y, M. Kloppenburg y z, S.N. Andersen y, A.L. Dorje L. Herb-van Toorn y, H.M. Kroon x, A.-M. Zuurmond k, V. Stojanovic-Susulic ¶, J.L. Bloem x, R.G.H.H. Nelissen #, R.E.M. Toes y, A. Ioan-Facsinay y * y Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands z Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands x Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands k TNO, Leiden, The Netherlands ¶ Janssen Research & Development, LLC, Spring House, PA, USA # Department Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands

a r t i c l e i n f o

s u m m a r y

Article history: Received 2 June 2015 Accepted 17 November 2015

Objective: To investigate the presence of mast cells in the osteoarthritic (OA) synovium and their association with clinical parameters in comparison with rheumatoid arthritis (RA) samples. Method: Synovial tissues of 56 symptomatic OA and 49 RA patients were obtained. Two to three paraffin slides were used to quantify inflammation using haematoxylin and eosin (H&E) staining (synovitis score 0e9), and numbers of mast cells (per 10 high-power fields) using double immunofluorescence for CD117 and tryptase. Average scores per patient were used for analysis. Knee radiographs of OA patients were scored according to the Kellgren and Lawrence (KL) system and pain was determined in OA patients at baseline by visual analogue scale (VAS). Results: Median (range) of mast cells was significantly higher in OA samples 45 (1e168) compared to RA samples 4 (1e47) (P-value < 0.001), despite a lower median (range) synovitis score in OA (2.5 (0e6.0)) compared to 4.6 (0e8.0) in RA samples. The synovitis score was significantly correlated with the number of mast cells (in OA Spearman's rho (P-value) 0.3 (0.023) and RA 0.5 (P-value < 0.001)). Interestingly, we observed a trend towards an association between the number of mast cells and an increased KL-grade (Pvalue 0.05) in OA patients, independently of synovitis. No associations were found with self-reported pain. Conclusion: Prevalence of mast cells in OA synovial tissue is relatively high and associates with structural damage in OA patients, suggesting a role of mast cells in this disease. © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Keywords: Osteoarthritis (OA) Mast cells Inflammation

Introduction

* Address correspondence and reprint requests to: A. Ioan-Facsinay, Department of Rheumatology, Leiden University Medical Centre, C1-38, Postbus 9600, 2300 RC Leiden, The Netherlands. Tel: 31-71-5262904; Fax: 31-71-5266752. E-mail addresses: [email protected] (B.J.E. de Lange-Brokaar), G. [email protected] (M. Kloppenburg), [email protected] e), [email protected] (S.N. Andersen), [email protected] (A.L. Dorje (E. Yusuf), [email protected] (L. Herb-van Toorn), [email protected] (H.M. Kroon), [email protected] (A.-M. Zuurmond), VStojano@its. jnj.com (V. Stojanovic-Susulic), [email protected] (J.L. Bloem), R.G.H.H.Nelissen@ lumc.nl (R.G.H.H. Nelissen), [email protected] (R.E.M. Toes), [email protected] (A. Ioan-Facsinay).

Osteoarthritis (OA) is a common rheumatic disorder that has been considered to be a non-inflammatory condition1. Synovitis, however, could play a role in the pathophysiology of OA1e6 as it is a predictor of cartilage destruction7,8 and a determinant of pain9,10. Although the biological processes underlying these associations are poorly understood, it has been suggested that immune cells infiltrating the synovial tissue could be important determinants of synovial inflammation6,11. Most frequent types of immune cells found in OA are macrophages, T cells and mast cells11. In contrast to macrophages and T cells, mast cells have been less frequently investigated in OA12e22. Interestingly however, it has been reported

http://dx.doi.org/10.1016/j.joca.2015.11.011 1063-4584/© 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

B.J.E. de Lange-Brokaar et al. / Osteoarthritis and Cartilage 24 (2016) 664e671

in the 1980s and 90s that mast cells were the only type of immune cells found in equal numbers14,15,17,23 or higher12,18 in OA compared to rheumatoid arthritis (RA) and healthy controls15e18,20,23. Moreover, a recent publication has shown an increased number of mast cells in femoroacetabular impingement (FAI), which is often the cause of OA in young individuals 24. These observations suggest a role for these cells in the pathophysiology of OA. However, no studies investigated the relationship between mast cells and clinical symptoms and signs of OA. Several mechanisms have been put forward through which mast cells could contribute to the disease process in RA and these could also apply in OA. For example, mast cells are thought to attract other immune cells through cytokine release, chemokine release or direct cell to cell contact, which leads to activation of the synovium and ultimately to inflammation and bone destruction25. Other possible mechanisms include the activation of fibroblasts and other synovial cells, stimulation of angiogenesis, upregulation of adhesion molecules on endothelium and others25. Furthermore, mast cells could contribute to pain in OA, as they have been implicated in pain perception in several disorders. How mast cells exert these effects is also poorly understood, but release of soluble mediators and enzymes have been suggested as possible mechanisms26. Whether mast cells could contribute to radiographic changes and pain is still unknown. To get initial insight into the potential role of mast cells in OA, we investigated the difference in mast cell number or degranulation status in OA compared to RA and at different stages of disease. Furthermore, we investigated the association of the number of mast cells with the grade of synovitis, structural damage and pain in OA, in a hypothesis generating setting. With this study, we intend to obtain a first insight into a possible contribution of mast cells to clinical parameters in OA. Methods OA patients The OA patients participated in the geMstoan study (GEneration of Models, Mechanism & Markers for Stratification of OsteoArthritis patieNts), an observational study in established and end-stage knee OA patients27. This study has been approved by the ethics committee of the Leiden University Medical Center (LUMC) and the Diaconessenhuis Leiden. All patients provided written informed consent. Inclusion and exclusion criteria are described elsewhere27. Two groups of patients with symptomatic radiographic primary knee OA, following the ACR criteria28, have been included in the geMstoan study: one group with end-stage disease that were planned to receive an arthroplasty (“late OA”) and another group with mild to established OA, as established by the rheumatologist, who had no indication for an arthroplasty (“early OA”). RA patients Tissue samples were obtained as leftover material from patients who underwent arthroplasty (“late RA”). Arthroscopy samples (“early RA”) were collected from RA patients who have been diagnosed with RA by a rheumatologist, but did not receive an indication for arthroplasty. These patients were part of a study described in29 excluded were RA patients on oral prednisolon >10 mg/day, recent (