RT Journal Article SR Electronic T1 22 Baricitinib inhibits B cell activation and ameliorates murine lupus JF Lupus Science & Medicine JO Lupus Sci & Med FD Lupus Foundation of America SP A17 OP A17 DO 10.1136/lupus-2019-lsm.22 VO 6 IS Suppl 1 A1 Lee, Jaeseon A1 Jang, SeGwang A1 Hong, Seung-Min A1 Baek, SeungYe A1 Park, Sung-Hwan A1 Kwok, Seung-Ki YR 2019 UL http://lupus.bmj.com/content/6/Suppl_1/A17.1.abstract AB Background B cells carry out central roles in the pathogenesis of SLE by triggering tissue inflammation through autoreactive antibody-dependent responses. Baricitinib is a JAK1/2 inhibitor that blocks the downstream of multiple cytokine receptor signaling implicated in lupus pathogenesis.Methods We investigated the effect of Baricitinib to the differentiation of B cells in vitro. And female MRL/lpr mice were administered baricitinib (10 mg/kg) or vehicle (0.5% methyl cellulose) by gavage twice daily for 8 weeks, when determined serum levels of anti-ds DNA antibodies and pro-inflammatory cytokines (BAFF, IL-6 and IL-17), proteinuria, renal inflammation and IgG-C3 deposit. In vitro, Baricitinib suppressed the mRNA expression of AID, Bcl6, XBP-1, IRF4 and the production of IgG in B cells.Results In MRL/lpr model, Baricitinib-treated mice showed reduced levels of anti-dsDNA antibodies, proteinuria, and cytokines as compared with those of control mice. In addition, Baricitinib prevented renal pathology, as judged by changes in the histopathological scores of glomeruli with PAS stain and IgG-C3 deposition by confocal microscope. Finally, Baricitinib treatment significantly inhibited downstream of Jak/STAT signals in CD19 +B cells from spleen. In conclusion, this study revealed the regulatory effects of baricitinib on B cells and ameliorates murine lupus.Conclusions These results indicate that Jak inhibitors have the potential therapeutic approach for SLE.Funding Source(s): None