| Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by polyclonal B-cell activation, autoantibody production and immune complex-mediated glomerulonephritis (GN). NZB/W F1 mice spontaneously develop SLE-like symptoms and have been widely used as an animal model for SLE. Even though the etiologic cause of autoimmunity in both human and murine lupus is not clearly understood, mounting evidence indicates the involvement of autoreactive B cells and T cells. Blockade of costimulatory pathways using CTLA4Ig fusion protein and anti-CD40 ligand monoclonal antibody (mAb) has been able to suppress autoantibody production and inhibit lupus nephritis in NZB/W F1 mice. In spite of these successes, protein- or mAb-based therapies are expensive, deliveries are problematic, and bolus injections result in transient and toxic levels of these reagents. In comparison, gene therapy offers an advantageous solution by achieving long-term, stable transgene expression and convenient gene delivery. Among the vectors used in gene therapy, recombinant adeno-associated virus (rAAV) has been proven to be a promising one because of its non-pathogenicity and non-immunogenicity.;In this project, the hypothesis that rAAV serotype 8 (rAAV8)-mediated immunomodulator gene transfer was able to prevent and suppress lupus development in NZB/W F1 mice was tested. First, the transgene expression pattern following systemic delivery was studied. rAAV8-mediated gene delivery was able to achieve long-lasting and high-level transgene expression following a single intraperitoneal or intrasplenic injection. Second, rAAV8-mediated costimulatory blockade gene transfer prevented autoantibody production, delayed proteinuria onset, prolonged survival and protected kidneys from immune-complex induced tissue damage. Moreover, it successfully suppressed CD4+ T cell activation and also the transition from naive to memory T cells. Among all early prevention strategies tested in newborn mice, the combination of murine CTLA4Ig (mCTLA4Ig) and murine CD40Ig (mCD40Ig) was more efficient than both single vectors, suggesting a synergistic effect between these two costimulatory blockades. Surprisingly, the late prevention in young lupus-prone mice achieved results similar to those observed in the early prevention. Furthermore, rAAV-mediated costimulatory blockade gene transfer did not suppress host humoral response to foreign antigens. Finally, in the treatment of lupus mice with high autoantibody titers, mCTLA4Ig alone, or in combination with mCD40Ig, was able to decrease autoantibody titers, delay proteinuria onset, and prolong survival. The therapeutic effects were evidenced to be dose-dependent. In general, this study indicates that rAAV8-mediated costimulatory blockade gene transfer is capable of preventing and suppressing lupus development, thereby suggesting the successful application of this autoimmune disease gene therapy both in research and in clinical settings to promote public health. |
