POS1257 COMPARISON OF REGULATORY B CELLS IN PERIPHERAL BLOOD AND CLINICAL CHARACTERISTICS BETWEEN IGURATIMOD AND HYDROXYCHLOROQUINE IN THE TREATMENT OF PRIMARY SJÖGREN’S SYNDROME
Authors: J. Zou, L. Yang, J. Yang, J. Luo, S. LI, Y. Zhang, J. Dong, D. Deng, Y. Ni, M. LI, X. Yin
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> The pathogenesis of Primary Sjögren's syndrome (pSS) is complex and the treatment is difficult, the enhanced activation of polyclonal B lymphocytes is the characteristic of the disease<sup>[1, 2]</sup>. Regulatory B cells (Bregs) are a class of B cell subsets with immunosuppressive effect. Several studies have shown that Iguratimod (IGU) has achieved certain efficacy in the treatment of Sjögren's syndrome<sup>[3-5]</sup>. However, there is no study on whether IGU has an effect on Bregs. <h3>Objectives:</h3> To analyze the regulatory Bregs in the peripheral blood and clinical data before and after treantment with IGU vesus hydroxychloroquine(HCQ) in pSS patients. <h3>Methods:</h3> The study was a prospective, single-center, randomized controlled study. 60 pSS patients in Mianyang Central Hospital from December 2020 to December 2022 were recruited. All the patients met the inclusion and excluded criteria of this study, they were randomly divided into two groups: IGU group and HCQ group. The treatment of IGU group was: prednisone ≤ 10mg/d, IGU 25mg bid; HCQ group was: prednisone ≤ 10mg/d, hydroxychloroquine 0.2g bid. The clinical and laboratory data of all patients at baseline and 24 weeks after treatment were collected. The SS disease activity index (ESSDAI) and the European League against desiccation Sjögren's syndrome patient reported index (ESSPRI) were used to assess the disease activity. The functional assessment of chronic illness therapy (FANCIT) was used to assess the fatigue degree of patients. B lymphocytes and Bregs (CD 19<sup>+</sup> CD 24 hi CD38 hi, CD 19<sup>+</sup> CD 24<sup>+</sup> CD 27<sup>+</sup> and CD 19<sup>+</sup> CD 1d<sup>+</sup> CD 5<sup>+</sup>B cells) in the peripheral blood were detected by flow cytometry. The protocol has been approved by the Ethic Committee of the MianYang Central Hospital, Written informed consents were obtained from all patients before they participate in this study. <h3>Results:</h3> Compared with the baseline, after 24 weeks of treatment, the levels of IgG and ESSPRI in the IGU group were significantly lower than those in the HCQ group, and the levels of CD19<sup>+</sup>CD5<sup>+</sup>CD1d<sup>+</sup>B cells were significantly higher than those in the HCQ group. There was no significant difference in other indicators between the two groups. In IGU group: The serum IgG level, erythrocyte sedimentation rate (ESR), B lymphocytes, ESSDAI, ESSPRI, FANCIT in the IGU group were significantly decreased, while the CD19<sup>+</sup>CD5<sup>+</sup>CD1d<sup>+</sup>B cells were significantly increased (Figure 1). In hydroxychloroquine group: CRP, ESR, ESSDAI, ESSPRI, FANCIT were significantly decreased, while there was no significant difference in Bregs before and after treatment (Figure 2).The main adverse reactions of the two groups were abnormal liver function, gastrointestinal symptoms, rash, leukopenia, skin itching, headache, and there was no significant difference between the two groups. <h3>Conclusion:</h3> Both IGU and HCQ can reduce the disease activity and fatigue score of patients with Sjögren's syndrome, However, IGU was superior to HCQ in reducing immunoglobulin IgG levels. IGU can also affect the levels of peripheral blood B lymphocytes and CD19<sup>+</sup>CD5<sup>+</sup>CD1d<sup>+</sup>B cells. <h3>REFERENCES:</h3> [1] Sandhya P, Kurien BT, Danda D, Scofield RH. Update on Pathogenesis of Sjogren's Syndrome. Curr Rheumatol Rev. 2017. 13(1): 5-22. [2] Zhan Q, Zhang J, Lin Y, Chen W, Fan X, Zhang D. Pathogenesis and treatment of Sjogren's syndrome: Review and update. Front Immunol. 2023. 14: 1127417. [3] Ye Z, Jiang Y, Sun D, Zhong W, Zhao L, Jiang Z. The Plasma Interleukin (IL)-35 Level and Frequency of Circulating IL-35(+) Regulatory B Cells are Decreased in a Cohort of Chinese Patients with New-onset Systemic Lupus Erythematosus. Sci Rep. 2019. 9(1): 13210. [4] Cui D, Zhang L, Chen J, et al. Changes in regulatory B cells and their relationship with rheumatoid arthritis disease activity. Clin Exp Med. 2015. 15(3): 285-92. [5] Lin X, Wang X, Xiao F, et al. IL-10-producing regulatory B cells restrain the T follicular helper cell response in primary Sjögren's syndrome. Cell Mol Immunol. 2019. 16(12): 921-931. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>