In Vivo AAV Delivery of Anti-CD19 CAR in Murine and Humanized SLE Models

Systemic lupus erythematosus (SLE) is a chronic, life-threatening autoimmune disease characterized by activation of the adaptive immune system, production of anti-dsDNA autoantibodies, and multi-organ inflammation. Although recent therapies have improved disease control, no curative approach currently exists. Many patients remain refractory to treatment and at risk for irreversible organ damage.

Autoreactive B cells play a central role in SLE pathogenesis by driving autoantibody production and inflammation. CD19 is broadly expressed across pathogenic B cell subsets, making it a strong candidate for therapeutic targeting. Depletion of CD19⁺ B cells may reduce active inflammation and promote immune reset, offering the potential for durable remission.

CD19-directed CAR T cells have shown promise in hematologic malignancies and autoimmune diseases, but their ex vivo production is labor-intensive, costly, and technically complex. To address this, we use an in vivo gene therapy approach with recombinant adeno-associated virus (rAAV) to deliver a CD19 CAR to T cells. In lupus-prone mice, a single intravenous dose of rAAV8 led to potent B cell depletion, reduced autoantibodies, improved kidney pathology, and prolonged survival.

While immunocompetent mouse models have advanced understanding of SLE, only humanized models enable the evaluation of clinically relevant vectors. We establish humanized model by injecting pristane, a lupus-like inducing hydrocarbon, into immunodeficient mice engrafted with human CD34⁺ hematopoietic stem cells. We also engineer the viral capsid to incorporate DARPin targeting human CD8, enabling preferential transduction of cytotoxic T cells.

This approach offers a promising strategy for targeted and potentially curative immunotherapy for SLE and other autoimmune diseases.