The mechanism of preventing EAE via gene therapy

Abstract

Abstract Similar to Multiple Sclerosis, EAE is a complex disease in which immune tolerance is lost and antigen specific (Ag-sp) Tregs are known to play a role. We have developed a gene immunotherapy that has been shown to induce MOG specific Tregs, restore tolerance, and effectively prevent, and/or reverse, significant disease. However, the spatiotemporal profile of the induced Tregs is unclear. To identify the tissue specific populations of AAV8.MOG-induced specific Tregs, we used a transgenic Foxp3 reporter mouse with a MOG35–55/I-Ab tetramer. Two weeks prior to EAE induction, mice were tolerized via a single injection of vector. At the peak of disease, tissues were harvested and fluorescently labeled for phenotypic identification. FACS analysis revealed a higher proportion of Ag-sp Tregs in the cervical and inguinal lymph nodes (LN) and spleen, as compared to controls. In contrast, a higher proportion of Ag-sp effector cells were seen in control mice as compared to treated. Furthermore, a significant number of infiltrating effector T cells were isolated from the spinal cords of control mice, while very few T cells were recovered from treated mice. This aligns with cytokine data that was collected showing there to be higher production of IFN-γ in the spinal cord and spleen of control mice. These results suggest that AAV.MOG induced Ag-sp Treg populations accumulate in the peripheral organs, and may prevent effector cells from migrating to the spinal cord. This work provides new insights on tolerance induction mechanisms. These insights will be useful for the development of effective cell based therapies capable of treating autoimmune diseases.