Background: The pathogenesis of primary sjögren’s syndrome (pSS) is multifactorial. Self-antigen-driven responses perform a vital function in the development of autoimmune diseases [1]. B cells, only 20-25% of total infiltrating cells in labial glands, are the cellular basis for spontaneous antibody production [2].Genome-wide association studies (GWAS) have identified Blimp-1 as a susceptibility gene for autoimmune diseases and played an important role in the pathogenesis of autoimmune diseases [3].

Objectives: To investigate the expression and effect of B lymphocyte induced maturation protein 1 (Blimp-1) in pSS and the correlation of Blimp-1 with B cell subsets and clinical features.

Methods: The PRDM1 mRNA expression in B lymphocyte and labial gland were examined by RT-PCR. The levels of B cell subsets were examined by flow cytometry. Hematoxylin-eosin (HE) staining and immunohistochemistry (IHC) were used to examine the invasion degree of lymph cell and Blimp-1 distribution, respectively. The correlation of PRDM1 mRNA with B cell subsets and clinical indicators were also analyzed.

Results: The levels of PRDM1 mRNA expression of B cells were significantly higher in SS than in healthy controls (HC) and which were also significantly higher in the high immunoglobulin (Ig) group than that in normal Ig group ( P <0.02, Fig. 1a -b). The number of CD19+B cells and CD138+ plasma cells(PC) have increased while the CD27+ cells decreased in SS( P <0.05). The percentage of PC and PC/B is positively correlated with PRDM1 mRNA( r =0.380, P =0.002; r =0.317, P =0.009, Fig. 1c -d). Blimp-1 expression level showed a positive correlation with invasion degree of lymph cell in histology ( Fig. 2a -c), Ig levels and ESSDAI score and an inverse correlation with the glucocorticoids usage ( Fig. 3c ).

Fig. 1

(a-b) RT-PCR showed that PRDM1 mRNA expression in SS patients and HC. (c-d) Correlation between PRDM1 mRNA expression and PC and PC/B.

Fig. 2

(a) Expression of Blimp-1 in labial glands of sjögren’s syndrome. (b) PRDM1 mRNA levels in different invasion degree of lymph cell group. (c) Correlation between PRDM1 mRNA expression and invasion degree of lymph cell. *p<0.05, ***p<0.001.

Fig. 3

(a-b) RT-PCR showed that PRDM1 mRNA expression in different usage of glucocorticoids. (c) Correlation between PRDM1 mRNA expression and different glucocorticoid usage. **p<0.01, ***p<0.001.

Conclusion: Blimp-1 displayed high expression in SS, which could affect pSS disease activity. SS activity is suppressed by glucocorticoid which might be through inhibition of Blimp-1.

REFERENCES:

[1]Kapsogeorgou EK, Abu-Helu RF, Moutsopoulos HM, Manoussakis MN (2005) Salivary gland epithelial cell exosomes: A source of autoantigenic ribonucleoproteins. Arthritis Rheum 52(5):1517-21. https://doi.org/10.1002/art.21005

[2]Arneth BM (2019) Impact of B cells to the pathophysiology of multiple sclerosis. J Neuroinflammation 16(1):128. https://doi.org/10.1186/s12974-019-1517-1

[3]Bönelt P, Wöhner M, Minnich M et al (2019) Precocious expression of Blimp-1 in B cells causes autoimmune disease with increased self-reactive plasma cells. EMBO J 38(2). pii:e100010. https://doi.org/10.15252/embj.2018100010

Acknowledgments : This study was supported by the grants from the National Natural Science Foundation of China (81871271).

Disclosure of Interests : None declared