A chimeric anti-inflammatory and anti-vascularization immunomodulator prevents high-risk corneal transplantation rejection via ex vivo gene therapy

Abstract

Corneal blindness affects greater than 5 million individuals, with over 180,000 corneal transplantations (CTs) performed annually. Inhigh-risk CTs, almost all grafts are rejected within 10 years. Herein, adeno-associated virus (AAV) ex vivo gene therapy was investigated to establish immune tolerance in the corneal allograft to prevent high-risk CT rejection. Our previous work has demonstrated that HLA-G contributes to ocular immune privilege by inhibiting both immune cells and neovascularization; however, homodimerization is a rate-limiting step for optimal HLA-G function. Therefore, a chimeric protein termed single chain immunomodulator (sclM), was engineered to mimic the native activity of the secreted HLA-G dimer complex and eliminate the need for homodimerization. In a murine corneal burn model, AAV8-sclM significantly reduced corneal vascularization and fibrosis. Next, ex vivo AAV8-scIM gene delivery to corneal allografts was evaluated in a high-risk CT rejection rabbit model. All sclM treated corneas were well tolerated and transparent after 42 days while 83% of vehicle treated corneas were rejected. Histologically, AAV-scIM treated corneas were devoid of immune cell infiltration, vascularization, with minimal fibrosis at the host-graft interface. The data collectively demonstrate that sclM gene therapy prevents corneal neovascularization, reduces trauma-induced corneal fibrosis, and prevents allogeneic CT rejection in a high-risk large animal model.