THU0236 EFFICACY AND SAFETY OF NON-MITOGENIC ANTICD3 ANTIBODY ADMINISTRATION IN THE TREATMENT OF LUPUS-PRONE MICE
Authors: M. Morita, S. Masuyama, M. Mizui, Y. Isaka
Journal: Annals of the Rheumatic Diseases (2020)

Background: Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease characterized by the production of autoantibody and systemic tissue damages including glomerulonephritis. Immune responses mediated by autoreactive T-cells, as well as by autoantibody, is involved in the development and progression of end-organ damages 1 . Biologic agents which manipulate T-cell function such as CTLA4-Ig and anti-CD40L have been revisited and tried to treat human SLE, however, both of them failed to demonstrate efficacy. A mouse specific anti-CD3ε mAb, clone 145-2C11 (2C11) is known to be immunosuppressive by down-modulation of TCR and depletion of T-cells 2 . Administration of Fc-deleted 145-2C11 F(ab’) 2 to lupus-prone mice was reported to reduce lymphadenopathy and prolong survival, but had no significant effect on anti-DNA antibody titer 3 . The mechanisms by which 2C11 ameliorates lupus are still unclear. In this study, we used non-mitogenic Fc-modified silent 145-2c11 (2C11S), which disables interaction between target cells and Fc receptor-bearing cells, abolishes antibody directed cytotoxicity, and has longer half-life than F(ab’) 2 . 2C11S is expected to exert its effect in safe and stable as compared with functional parent-2C11 (2C11P) antibody. Objectives: The purpose of our study is to clarify the difference between 2C11S and 2C11P and to examine their therapeutic effects against murine lupus-prone (NZB/W F1) mice. Methods: 20 μg of 2C11P (absolute antibody), 2C11S (absolute antibody), or isotype control immunoglobulin G1 κ (IC)(BioLegend) were administered intraperitoneally to C57BL6 mice. The difference of their action on T-cells were evaluated in a time series from peripheral blood. Plasma cytokine levels were measured within 24 hours after antibody administration. In NZB/W F1 mice from weeks 10 or 20, 2C11P, 2C11S, and IC were administered (100 μg / week, 4 times, intraperitoneally). Plasma anti-dsDNA antibody titer, spleen and kidney blood cell subpopulation, and histology of renal tissue were evaluated before and/or after treatment. Results: Duration of reduced TCR expression in 2C11S group was approximately twice as long as that in 2C11P group, and the levels of plasma TNF-α was not increased in 2C11S group while significant increase was observed in 2C11P group (IC; mean 48.3 ± SD 16.7 pg/ml, 2C11S; 57.9 ± 6.12, 2C11P; 168 ± 50.6, IC VS 2C11S; p&gt;0.99, IC VS 2C11P; p=0.03, ANOVA). In NZB/W F1 mice, the number of follicular helper T (Tfh) cells in spleen significantly decreased in 2C11S group (IC; median 9.0*10 4 [interquartile range 8.5*10 4 ], 2C11S; 1.8*10 4 [1.0*10 4 ], 2C11P; 1.0*10 5 [9.4*10 4 ], IC VS 2C11S; p=0.03, IC VS 2C11P; p&gt;0.99, Kruskal-Wallis). The number of germinal center B (GCB) cells in spleen also decreased in 2C11S group (IC; 1.2*10 5 [1.7*10 5 ], 2C11S; 9.0*10 3 [2.3*10 4 ], 2C11P; 8.0*10 4 [2.3*10 5 ], IC VS 2C11S; p=0.03, IC VS 2C11P; p&gt;0.99). The number of infiltrating CD4 + T-cells in kidney significantly reduced in 2C11S group (IC; 3.4*10 3 [1.0*10 4 ], 2C11S; 6.4*10 2 [8.8*10 2 ], 2C11P; 1.2*10 3 [4.4*10 3 ], IC VS 2C11S; p=0.048, IC VS 2C11P; p=0.23). In addition, the rate of increase in anti-dsDNA IgG titers significantly decreased in 2C11S group (IC; 2.3 [1.3], 2C11S; 0.9 [1.0], 2C11P; 1.3 [1.4], IC VS 2C11S; p=0.03, IC VS 2C11P; p=0.24). Finally, glomerular hypercellularity was markedly alleviated only in 2C11S group (IC; 4.4*10 [8.4], 2C11S; 3.8*10 [1.1], 2C11P; 3.9*10 [8.2], IC VS 2C11S; p=0.02, IC VS 2C11P; p=0.57). Conclusion: 2C11S did not induce cytokine release with maintaining longer effect on TCR down-modulation. 2C11S reduced autoantibody production by suppressing GCB differentiation, possibly through down-regulation of Tfh cell number. Consequently, 2C11S ameliorated lupus nephritis. On the other hand, 2C11P did not show therapeutic effect. References: [1]George C Tsokos. et al. Nat. Rev. Rheum (2016) 12: 716-730. [2]Kuhn C. et al. Immunotherapy (2016) 8: 889-906. [3]Henrickson M. et al. Arthritis Rheum (1994) 37: 587-589. Disclosure of Interests: : None declared