POS0270 OVERLAPPING MACROPHAGE PROFILES IN PMR BURSA AND GCA TEMPORAL ARTERY BIOPSIES
Authors: A. Zhang, W. F. Jiemy, Y. Van Sleen, S. Xu, M. Sandovici, E. Brouwer, K. Van der Geest
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Polymyalgia rheumatica (PMR), an inflammatory disease affecting the shoulder and hip girdles, co-occurs in 50% of giant cell arteritis (GCA) patients [1]. Glucocorticoids have remained the cornerstone treatment for GCA, although targeted therapies have emerged [2,3]. Nevertheless, relapses are still common, and half of the relapsing patients have PMR symptoms[4]. Ideally, novel therapies should treat both GCA and PMR. IL-6 targeted treatments for example, have been shown to be effective for both diseases [2,3]. Macrophages are major players in the immunopathology of GCA, whereas the immune pathology of PMR remains obscure. <h3>Objectives:</h3> We sought to compare macrophage-related immune profiles in PMR- and GCA-affected tissues to identify shared therapeutic targets. <h3>Methods:</h3> Subacromial bursa biopsies (SABB) from 12 patients with isolated PMR and temporal artery biopsies (TAB) from 10 patients with isolated GCA were included. To study macrophage phenotypes and functions, immunohistochemistry of SABB and TAB was focused on macrophage markers (CD68, CD86, CD64, CD206, folate receptor β) and cytokines (IL-1β, IL-6, IL-12, IL-23, TNF-α, GM-CSF, M-CSF), which were scored semi-quantitatively on a five-point scale (0–4) by two independent researchers: 0 = no positive cells, 1 = 0–1% estimated positive cells, 2 = &gt; 1–20% positive cells, 3 = &gt; 20–50% positive cells, 4 = &gt; 50% positive cells. An average score was calculated. Statistical analysis was performed by the Mann Whitney U test. P values &lt;0.05 were considered statistically significant. <h3>Results:</h3> The number of CD68+ macrophages was comparable in TAB and PMR-affected bursa tissues. The distribution of M1/M2 markers and co-stimulatory molecules was similar in both types of tissue. Expression of GM-CSF, IL-1β, IL-23, M-CSF and TNF-α was comparable in GCA TAB and PMR SABB. Prominent expression of IL-6 and IL-12A was observed in GCA TAB, but these pro-inflammatory cytokines were even more intensely expressed in the PMR SABB (Figure 1). <h3>Conclusion:</h3> Macrophage immune profiles show substantial overlap in GCA and PMR tissue. Macrophage-related markers and cytokines may constitute therapeutic targets for both GCA and PMR. <h3>REFERENCES:</h3> [1] Awisat A, et al. Giant Cell Arteritis: State of the Art in Diagnosis, Monitoring, and Treatment. Rambam Maimonides Med J. 2023 Apr 30;14(2): e0009. [2] Sandovici M, et al. Need and value of targeted immunosuppressive therapy in giant cell arteritis. RMD Open. 2022 Feb;8(1): e001652. [3] Wendling D. Biological therapy in polymyalgia rheumatica. Expert Opin Biol Ther. 2023 Nov 21:1-9. [4] Alba MA, et al. Relapses in patients with giant cell arteritis: prevalence, characteristics, and associated clinical findings in a longitudinally followed cohort of 106 patients. Medicine (Baltimore). 2014 Jul;93(5):194-201. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Anqi Zhang: None declared, William Febry Jiemy: None declared, Yannick van Sleen: None declared, Shuang Xu: None declared, Maria Sandovici: None declared, Elisabeth Brouwer: None declared, Kornelis van der Geest K. van der Geest received research support from AbbVie.