AbstractsBiology & Animal Science

Introduction: The ability to ameliorate murine lupus renders regulatory T cells (Treg) a promising tool for the treatment of systemic lupus erythematosus (SLE). In consideration to the clinical translation of a Treg-based immunotherapy of SLE, we explored the potential of CD4+Foxp3+ Treg to maintain disease remission after induction of remission with an established cyclophosphamide (CTX) regimen in lupus-prone (NZBxNZW) F1 mice. As a prerequisite for this combined therapy, we also investigated the impact of CTX on the biology of endogenous Treg and conventional CD4+ T cells (Tcon). Methods: Remission of disease was induced in diseased (NZBxNZW) F1 mice with an established CTX regimen consisting of a single dose of glucocorticosteroids followed by five day course with daily injections of CTX. Five days after the last CTX injection, differing amounts of purified CD4+Foxp3+CD25+ Treg were adoptively transferred and clinical parameters, autoantibody titers, the survival and changes in peripheral blood lymphocyte subsets were determined at different time points during the study. The influence of CTX on the numbers, frequencies and proliferation of endogenous Treg and Tcon was analyzed in lymphoid organs by flow cytometry. Results: Apart from abrogating the proliferation of Tcon, we found that treatment with CTX induced also a significant inhibition of Treg proliferation and a decline in Treg numbers in lymphoid organs. Additional adoptive transfer of 1.5 × 106 purified Treg after the CTX regimen significantly increased the survival and prolonged the interval of remission by approximately five weeks compared to mice that received only the CTX regimen. The additional clinical amelioration was associated with an increase in the Treg frequency in the peripheral blood indicating a compensation of CTX-induced Treg deficiency by the Treg transfer. Conclusions: Treg were capable to prolong the interval of remission induced by conventional cytostatic drugs. This study provides valuable information and a first proof-of-concept for the feasibility of a Treg-based immunotherapy in the maintenance of disease remission in SLE. Einführung: Die Fähigkeit murinen Lupus zu beeinflußen, macht regulatorische T-Zellen (Treg) zu einem aussichtsreichen Instrument zur Therapie des Systemischen Lupus Erythematodes (SLE). In Anbetracht der zukünftigen klinischen Umsetzung einer Treg-basierten Immuntherapie des SLE, erforschten wir im (NZBxNZW) F1 Mausmodell des Lupus das Potential von CD4+Foxp3+Treg die durch ein etabliertes Cyclophosphamid (CTX) Regime induzierte Krankheitsremission aufrechtzuerhalten. Als Vorraussetzung für diese kombinierte Therapie untersuchten wir auch die Auswirkung von CTX auf die Biologie von endogenen Treg und konventionellen CD4+ T-Zellen (Tcon). Methoden: Zunächst induzierten wir die Remission bei bereits erkrankten (NZBxNZW) F1-Mäusen durch ein bewährtes CTX-Behandlungsschema bestehend aus einer einmaligen Glukokortikosteroid-Injektion gefolgt von täglichen CTX Injektionen über fünf Tage. Weitere fünf Tage…