THU0325 REDUCED OF TREG CELLS ASSOCIATED WITH THE DISEASE ACTIVITY OF ANCA-ASSOCIATED VASCULITIS
Authors: R. Wu, R. Su, T. Ding, H. Xue, J. An, X. F. LI, C. Wang
Journal: Annals of the Rheumatic Diseases (2020)

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a group of autoimmune disease that can cause systemic organ damage, characterized with the presence of abnormal antibodies (ANCAs) in the circulation and the small- and medium-vessel vasculitis[1].However,the etiology of AAV remained unclear. Several observations have showed that the breakdown of immune tolerance caused by many complex interactions was involved in the pathogenesis of AAV[2].It has been confirmed that the disorder of the CD4+T cell,especially the imbalance of Th17 and Treg cells can destroy the immune tolerance and cause many autoimmune disease[3]. But the relationship between the Th17/Treg and AAV is unknown. Objectives: We investigated the absolute numbers of CD4+T subsets cells in peripheral blood of patients with AAV and healthy adults,and then compared them in different disease activity of AAV to explore the role of CD4+T subsets cells in the pathogenesis and development of AAV. Methods: 49 patients with AAV,hospitalized at the Second Hospital of Shanxi Medical University from the May 2016 to the November 2019 were enrolled, and 31 age and gender-matched healthy adults were anticipated as controls.According to BVAS, the patients were divided into disease-activity group (BVAS≥15, n=27) and non-disease-activity group (BVAS&lt;15, n=22). The absolute numbers of CD4+T subsets cells including Th17 and Tregs in peripheral blood of these individuals were detected by flow cytometry.We analyzed whether there was difference of CD4+T subsets between the patients and healthy controls,and between disease-activity group and non-disease-activity group. Results: There was significant decreased level of Treg cells in the patients with AAV compared with healthy controls,especially in the disease-activity group. The absolute numbers of Treg cells was decreased in the patients with AAV compared with healthy controls (P&lt;0.001) leading to a higher Th17/Treg ratio in the patients (P&lt;0.01).Similarly,the absolute number of Treg cells was decreased in the disease- activity group (P&lt;0.01) compared with the non-disease-activity group, and the absolute number of Treg cells was significant negative correlation with the disease activity indexes such as BVAS (r=-0.342,P=0.016), erythrocyte sedimentation rate(ESR) (r=-0.315,P=0.027) and C-reactive protein(CRP) (r=-0.305,P=0.033). But there was no statistically significant in the absolute number of Th17 cells between the patients and healthy controls, and between disease-activity group and non-disease-activity group. Conclusion: The results we investigated here suggested that the decreased number of Treg cells failed to control autoimmune inflammatory response and maintain immune tolerance, and the disease activity of AAV was associated with the reduced number of Treg cells. Figure 1. (A-C) Characteristics of the absolute number of Th17 cells and Treg cells in peripheral blood of healthy controls (n=31) and the patients with AAV (n=49). There was significant decreased level of Treg cells in the patients with AAV compared with healthy controls leading to a higher Th17/Treg ratio in the patients with AAV. (D-F) The absolute number of Treg cells was decreased in the disease- activity group (n=27) compared with the non-disease-activity group (n=21). The absolute number of Th17 cells and Treg cells was detected by flow cytometry. Statistical analyses were performed by the Mann-Whitney U test. *p&lt;0.05,**p&lt;0.01, ***p&lt;0.001. References: [1]Cosmi, L., Th17 and Treg lymphocytes as cellular biomarkers of disease activity in Granulomatosis with Polyangiitis. Eur J Immunol, 2017. 47 (4): p. 633-636. [2]Pagnoux, C., Updates in ANCA-associated vasculitis. Eur J Rheumatol, 2016. 3 : p. 122-133. [3]Diller, M.L., et al., Balancing Inflammation: The Link between Th17 and Regulatory T Cells. Mediators Inflamm, 2016. 2016 : p. 6309219. Disclosure of Interests: None declared