FP190
MODIFIED IMMUNE CELL THERAPY AMELIORATES MURINE LUPUS NEPHRITIS AND INDUCES REGULATORY CELL SUBSETS

INTRODUCTION: Modified immune cells (MICs) are mononuclear cells that gain immunosuppressive properties after incubation with the proliferation inhibitor mitomycin C. We recently showed that syngeneic MIC therapy controlled experimental autoimmune encephalitis (EAE). In addition, allogeneic MIC therapy prevented rejection in rat heart and hindlimb as well as pig kidney transplantation. We now wanted to translate these encouraging findings to the prevention and treatment of lupus nephritis.

METHODS: Splenocytes of syngeneic NZB/W F1 (BWF1) donor mice were incubated with mitomycin C and injected into recipient’s tail vein after matching for age and disease activity. Group 1 received no MIC therapy, group 2 standard-dose MIC therapy with 1.5x10⁸/kg BW once and group 3 repeated MIC therapy with 1.5x10⁸/kg BW at weeks 1, 2 and 3. Group 4 received MIC infusions before disease onset as preemptive treatment approach. Disease activity was monitored by loss of body weight, protein excretion and serum creatinine. Combined primary endpoint was day 40 post-treatment, protein excretion ≥3g/l for 2 consecutive weeks and >30% loss of original body weight. Histopathology with PAS and HE staining was performed to assess degree of lupus nephritis. Regulatory cell subsets were measured in peripheral blood.

RESULTS: MIC therapy prevented the progression of fatal lupus nephritis in BWF1 mice. Protein excretion, serum creatinine and dsDNA antibodies were lower in standard-dose (group 2) and preemptive (group 4) groups compared to control group (group 1) whereas repeated MIC therapy after disease onset had no effect. The primary endpoint was reached significantly more often in control group (group 1, 67%) compared to treatment groups 2 (14%), 3 (14%) and 4 (0%). Renal architecture was preserved in different MIC treatment groups (groups 2-4) with decreased glomerular and tubular damage scores. Most importantly, frequencies of CD8+CD25+FoxP3+regulatory T cells and CD19+CD5+CD1dhighregulatory B cells were significantly higher in MIC-treated (groups 2-4) compared to control animals of group 1, whereas double negative T cells were markedly reduced.

CONCLUSIONS: MIC therapy inhibits progression of active lupus nephritis. Interestingly, preemptive MIC therapy was even able to prevent onset of disease with no significant disease activity at completion of the study. In accordance with our previous pre-clinical EAE experiments and a first in-human clinical trial in living-donor kidney transplantation (TOL-1 study), MIC therapy was able to induce an in-vivo induction of regulatory cell subsets. This clinically applicable cell therapeutic approach may control lupus nephritis by specifically silencing deleterious autoimmune responses.