THU0044 Impaired autophagy induces defective function of regulatory b cells in ankylosing spondylitis
Authors: C. Shuizhong, X. zhongyu, Z. guan, S. huiyong, W. yanfeng
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Ankylosing spondylitis (AS) is an autoimmune disease characterised by pathological osteogenesis and chronic inflammation. Large number studies shown that Regulatory B cells (Bregs) has immunosuppressive function, which could be involved in many rheumatic disease, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA). But the Bregs in AS are poorly understood. <h3>Objectives</h3> To investigate the ratio and function of Bregs in AS, and illuminate the under lying mechanism, which might help to further understand the pathology of AS. <h3>Methods</h3> (1) Peripheral blood mononuclear cells (PBMCs) were collected from 9 AS patients and 9 healthy controls, then the Bregs were detected by using flow cytometry with the following antibodies: CD19-PE, CD24-FITC and CD38-APC.<sup>2</sup> B cells were purified with a CD19 magnetic bead, the Bregs were sorted by using the flow cytometry. Bregs were added to the upper chamber with 1.5 ml medium, while CD4 +T cells were added to the lower chamber with 2.6 ml medium at a ratio of 1:1 Bregs(1 × 106 cells): CD4 +T cells(1 × 106 cells). CD4 +T cells were incubated with 5 µM CFDA-SE. The CD4 +T cell proliferation was analyse in the fifth day.<sup>3</sup>The cytokines of Bregs were detected with a proteome profiler kit, and confirmed by using Elias and Western Blot.<sup>4</sup> We detected the Bregs autophagy between AS and HD. And we regulate the autophagy with rapamycin and 3-methyladenine (3-MA), then detected the IL-10 secretion of Bregs and the CD4 +T cell proliferation among groups. <h3>Results</h3> (1) The ratio of Bregs in AS was higher that in healthy group.<sup>2</sup> Bregs from AS shown a impaired function in suppressed the CD4 +T cell proliferation compared with HD.<sup>3</sup> Bregs of AS expressed and secreted less IL-10 than healthy control, and might explain the impaired function of Bregs of AS.<sup>4</sup> Exogenous IL-10 recovered the immunosuppressive capacity of AS Bregs, whereas exogenous anti-IL-10 antibody reduced the immunosuppressive capacity of HD Bregs.<sup>5</sup> Autophagy impaired in AS Bregs compared with HD Bregs. Induce autophagy in AS Bregs could increase the IL-10 secretion and strengthened its immunosuppressive capacity, while 3-MA shown the opposite results. <h3>Conclusions</h3> Even increasing ratio of Bregs in AS, but they had a impaired function in suppressed CD4 +T cell proliferation compared with the HD. We further found that impaired autophagy could induces less IL-10 secretion, which further affected the immunosuppressive capacity of Bregs of AS. <h3>Acknowledgements</h3> This study was supported by the National Natural Science Foundation of China (81271951, 81401850), the Science and Technology Project of Guangdong Province (2015 B020228001) and by the Engineering Technology Research Centre for Comprehensive Diagnosis and Treatment of Ankylosing Spondylitis of Guangdong Higher Education Institutes (GCZX-A1301). <h3>Disclosure of Interest</h3> None declared