POS0996 MASS CYTOMETRICAL APPROACH TO REVEAL IMMUNE CELL PROFILES ASSOCIATED WITH PRIMARY SJÖGREN’S SYNDROME
Authors: H. Fukui, M. Takeshita, K. Suzuki, T. Takeuchi, Y. Kaneko
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Sjögren's syndrome (SjS) is a systemic autoimmune disease characterized by the secretory gland dysfunction and the presence of autoantibodies. Extra-glandular symptoms occur in about 30-40% of patients, with various manifestations including musculoskeletal, pulmonary, renal, dermal, central and peripheral nervous systems. Although B-cell hyperactivation is the key feature of SjS, its pathogenesis still remains unclear and immunosuppressive therapies including glucocorticoids or B-cell targeted agents have not shown convincing effect in previous clinical trials. Currently, there are no specific treatments available for SjS, and unmet medical needs still exist in this systemic autoimmune disease. <h3>Objectives:</h3> To identify the unique cell populations related to the pathophysiology of primary SjS immunopathogenesis using mass cytometry (CyTOF). <h3>Methods:</h3> Patients fulfilling the 2016 ACR-EULAR classification criteria for primary SjS were selected in our hospital for the analysis. Age and sex matched healthy volunteers were selected as the control. Peripheral blood mononuclear cell (PBMC) from primary SjS patients and healthy individuals were measured by CyTOF with 37-marker panel. CyTOF data were analyzed by machine-learning algorithms including dimensional reduction with tSNE (t-Distributed Stochastic Neighbor Embedding) and unsupervised clustering with CITRUS (Cluster identification, characterization, and regression). Conventional biaxial manual gating methods were conducted to verify the results. <h3>Results:</h3> Twenty-seven primary SjS patients and twenty-three healthy controls (HC) were included in the analysis. Age, sex, and body mass index were comparable between the two groups. The mean ESSDAI was 3.73 ± 6.19, and anti SS-A/Ro60 antibody positivity was 81.4% (22/27) in SjS patients. Increased frequency of monocytes (SjS vs HC, p&lt;0.01) and CXCR5-PD-1<sup>high</sup> T peripheral helper cells (p=0.02) were detected in SjS patients compared to HC. Proportion of memory B cells (p&lt;0.01), CD4+CD45RA+CCR7+CD25-CD38+T cells (p=0.04) and CD3<sup>high</sup>CD4-CD8-CD45RA- T cells (p=0.03) were decreased in SjS patients. In SjS patients, increased PD-L1 expression was observed in B cells (p&lt;0.01), CD4+CD25-CD45RA-T cells (p&lt;0.01), and CD8+CD45RA-CCR7+ T cells (p&lt;0.01). Increased CD38 expression was observed in CD16+NK cells (p&lt;0.01), CD8+CD45RA+CCR7- T cells (p&lt;0.01), CD4-CD8- T cells (p&lt;0.01), and naïve B cells (p=0.01). Decreased CXCR3 expression was observed in CD16+NK cells (p&lt;0.01), CD8+CD45RA- T cells (p&lt;0.01) and CD4-CD8- T cells (p&lt;0.01). CD4-CD8- T cell clusters, which is partly represented by γδT cell subset, imply the importance of this unique T cell subset in the pathogenesis of SjS. <h3>Conclusion:</h3> Mass cytometry analysis identified distinct cell subsets in primary SjS patients which are significantly different from healthy individuals. Further research is needed to determine the function and pathogenicity of these cell populations in primary SjS. <h3>REFERENCES:</h3> [1] Nocturne G, Mariette X. B cells in the pathogenesis of primary Sjögren syndrome. <i>Nat Rev Rheumatol</i>. 2018;14(3):133-145. [2] Shiboski CH, Shiboski SC, Seror R, et al. 2016 American College of Rheumatology/European League Against Rheumatism classification criteria for primary Sjögren's syndrome: A consensus and data-driven methodology involving three international patient cohorts. <i>Ann Rheum Dis</i>. 2017;76(1):9-16. [3] Bruggner RV, Bodenmiller B, Dill DL, Tibshirani RJ, Nolan GP. Automated identification of stratifying signatures in cellular subpopulations. <i>Proc Natl Acad Sci U S A</i>. 2014;111(26):E2770-E2777. <h3>Acknowledgements:</h3> This work is supported by "Immune-mediated Inflammatory Disease Consortium", which is funded by Daiichi-Sankyo Co., Ltd., Mitsubishi Tanabe Pharma, and Ono Pharmaceutical Co., Ltd. <h3>Disclosure of Interests:</h3> Hiroyuki Fukui Grant/research support from:Daiichi-Sankyo, Mitsubishi-Tanabe, Ono, Masaru Takeshita Grant/research support from: Daiichi-Sankyo, Mitsubishi-Tanabe, Ono, Katsuya Suzuki Speakers bureau from: AbbVie, AsahiKasei, Astellas, Ayumi, Bristol-Myers Squibb, Chugai, Eisai, Eli Lilly, Gilead, Janssen, Mitsubishi-Tanabe, Pfizer, Sanofi, Viatris, Consultant from: AbbVie, Asahi Kasei, Janssen, Pfizer, Grant/research support from: Chugai, Daiichi-Sankyo, Eli Lilly, Mitsubishi-Tanabe, Ono, Takeda, Tsutomu Takeuchi Speakers bureau from: AbbVie, Asahi Kasei, Astellas, Bristol-Myers Squibb, Chugai, Daiichi-Sankyo, Eisai, Eli Lilly, Gilead, Janssen, Mitsubishi-Tanabe, Pfizer, Consultant from: AbbVie, Chugai, Eli Lilly, Gilead, Mitsubishi-Tanabe, Grant/research support from: AbbVie, Asahi Kasei, Ayumi, Chugai, Eisai, Eli Lilly, Mitsubishi-Tanabe, Ono, Yuko Kaneko Speakers bureau from: AbbVie, Asahi Kasei, Astellas, Boehringer Ingelheim, Bristol Myers Squibb, Chugai, Daiichi Sankyo, Eisai, Eli Lilly, Gilead, Janssen, Mitsubishi-Tanabe, Novartis, Pfizer, Grant/research support from: AbbVie, Asahi Kasei, Ayumi, Boehringer Ingelheim, Chugai, Eisai, Mitsubishi-Tanabe.