84. Alpha 1 Antitrypsin Protein & Gene Therapies for the Treatment of Lupus in Animal Models

Systemic lupus erythematosus (SLE) is an autoimmune rheumatic disorder. Although the pathogenesis of SLE remains elusive, over-reactive dendritic cells (DCs), which promote B cell activation and autoantibodies secretion, play critical roles in the disease development. Alpha-1 antitrypsin (AAT) is a multifunctional protein with anti-inflammatory, cytoprotective and immunoregulatory properties. We has shown that AAT has protective effect in autoimmune disease models including type 1 diabetes and rheumatoid arthritis. In this study, we tested therapeutic potentials of AAT in controlling DC and B cells function and the development of SLE in a spontaneous lupus mouse model. Using bone marrow cells from normal (C57BL/6) and lupus prone (B6. TC, MRL/lpr) mice, we showed that AAT treatment significantly inhibited lipopolysaccharide (LPS) (TLR4 agonist) or CpG (TLR9 agonist) induced DC (cDC and pDC) maturation. In this in vitro system, AAT significantly inhibited the production of IFN-I, IL-1β, IL-6 and TNF-α from DCs. AAT treated DC also have significantly lower potential in stimulating B cell proliferation and functions. Based on these results, performed following experiments using spontaneous lupus mouse models. In order to test this therapeutic potential, we treated female MRL/lpr mice (at 7-weeks of age, n=10) with clinical grade of AAT (2 mg/mouse, every 3 days) or PBS for 11 weeks. Consistent with our in vitro observations, results from this experiment showed that AAT treatment significantly inhibited DC maturation and reduced DC susceptibility to LPS stimulation. Importantly, AAT treatment significantly lowered serum antibody (anti-dsDNA IgG and anti-nuclear antibodies, ANAs) levels and urine albumin levels. Detailed pathological examinations showed that AAT treatment prevented kidney disease development. To confirm this observations and test the long-term effect of AAT treatment, we performed second experiment using both AAT protein and gene therapies. In this experiment, we treated adult female NZM2410 (another commonly used spontaneous lupus model) mice with AAT protein and rAAV8-CB-AAT vector (1×1011 vg/mouse, single IP injection). While 100% mice in control group develop lupus and died at 46 week of age, 50% mice in AAT protein treatment group remain lupus free at 55 weeks of age. Intriguingly, AAT gene therapy (rAAV8-CB-AAT) significantly prevent lupus development (70% mice remain lupus free at 63 weeks of age, P=0.0059). These results clearly demonstrated the therapeutic effect of AAT protein and gene therapy in lupus mouse model. Our results also indicated the advantage of rAAV8 mediated gene therapy for the chronic autoimmune diseases. In summary, we showed AAT inhibited the activation and function of DCs and B cells in vitro and in vivo. We also showed AAT treatment (protein therapy and gene therapy) prevent lupus development in spontaneous lupus mouse models. Considering the safety profile of AAT and rAAV, our results may be translated into clinical application and lead to a novel (safe and effective) therapy for SLE in humans. This work was supported by grants from University of Florida and Grifols, Inc.