A chimeric anti-vascularization immunomodulator prevents high-risk corneal transplantation rejection via ex vivo gene
Brian C Gilger1, Tomoko Hasegawa2, R Bryan Sutton3
1Department of Clinical Sciences, North Carolina State University, Raleigh, NC 27607, USA; Bedrock Therapeutics, Raleigh, NC 27613, USA.
Abstract:
Corneal blindness affects more than 5 million individuals, with over 180,000 corneal transplantations (CTs) performed annually. In high-risk CTs, almost all grafts are rejected within 10 years. Here, we investigated adeno-associated virus (AAV) ex vivo gene therapy 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 called single-chain immunomodulator (scIM), 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-scIM 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 scIM-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 and vascularization, with minimal fibrosis at the host-graft interface. The data collectively demonstrate that scIM gene therapy prevents corneal neovascularization, reduces trauma-induced corneal fibrosis, and prevents allogeneic CT rejection in a high-risk large animal model.
Insights
Gene therapy using adeno-associated virus (AAV) carrying a single-chain immunomodulator (scIM) protein successfully prevented corneal allograft rejection in a high-risk rabbit model. This novel approach reduced immune rejection, vascularization, and fibrosis, offering hope for corneal transplantation.
Area of Science:
- Ophthalmology
- Immunology
- Gene Therapy
Background:
- Corneal blindness impacts millions globally, with high-risk corneal transplantations (CTs) frequently failing due to graft rejection.
- HLA-G is crucial for ocular immune privilege, but its function is limited by homodimerization.
- A novel chimeric protein, single-chain immunomodulator (scIM), was engineered to mimic HLA-G dimer activity without requiring homodimerization.
Purpose of the Study:
- To investigate adeno-associated virus (AAV) ex vivo gene therapy with scIM to establish immune tolerance in corneal allografts.
- To prevent high-risk corneal transplantation rejection.
Main Methods:
- Engineered a single-chain immunomodulator (scIM) protein to mimic secreted HLA-G dimer function.
- Utilized adeno-associated virus serotype 8 (AAV8) for ex vivo gene delivery of scIM.
- Evaluated AAV8-scIM efficacy in a murine corneal burn model and a high-risk rabbit corneal transplantation model.
Main Results:
- AAV8-scIM significantly reduced corneal vascularization and fibrosis in a murine model.
- In rabbits, 100% of scIM-treated corneas were well-tolerated and transparent after 42 days, compared to 83% rejection in vehicle-treated controls.
- Histological analysis showed minimal immune cell infiltration, vascularization, and fibrosis in scIM-treated corneas.
Conclusions:
- scIM gene therapy effectively prevents corneal neovascularization and reduces trauma-induced fibrosis.
- Ex vivo AAV-scIM gene delivery establishes immune tolerance and prevents allogeneic corneal graft rejection in a high-risk large animal model.
- This approach holds promise for improving outcomes in high-risk corneal transplantation.
