CNS-Targeted Cell Therapy for Multiple Sclerosis

Abstract: Multiple sclerosis (MS) is an autoimmune disorder of the central nervous system (CNS). In the current thesis, we have preformed an immunological investigation of patients with MS and developed an immunosuppressive cell therapy that could be beneficial for these patients.MS has been considered to be driven by T helper type1 (Th1) lymphocytes but new data indicate the involvement of Th17 responses. T cells from patients with MS that were evaluated for immunological status secreted both interferon-? and interleukin-17 upon stimulation. However, T cells from patients with MS in remission, in contrast to relapse, had poor proliferative capacity suggesting that they are controlled and kept in anergy.T regulatory cells (Tregs) are important to maintain self-tolerance and the role of CD4+CD25+FoxP3+ Tregs in autoimmunity has been extensively investigated. We analyzed Tregs from patients with MS in relapse and remission by multicolor flow cytometry for the expression of CD3, CD4, IL2R (CD25), FoxP3 and the IL7R (CD127). Patients in relapse exhibited higher levels of FoxP3-positive Tregs lacking CD25 compared to healthy controls, indicating that Tregs might attempt to restrain immune activity during relapse.In the murine experimental autoimmune encephalomyelitis (EAE) model of MS, therapy with suppressive cells such as Tregs or mesenchymal stromal cells (MSCs) has proven beneficial. However, systemic administration of such cells may immunologically compromise the recipient and promote infections due to general immunosuppression. We hypothesized that suppressive cells can be equipped with a CNS-targeting receptor and be delivered intra-nasally to avoid systemic exposure. CD4+ T cells were modified with a lentiviral vector system to express a myelin oligodendrocyte (MOG)-targeting receptor in trans with the FoxP3 gene that drives Treg differentiation. Genetically engineered Tregs demonstrated suppressive capacity in vitro and localized to the brain and suppressed ongoing encephalomyelitis in vivo. Cured mice were rechallenged with an EAE-inducing inoculum but remained healthy.MSCs are a heterogeneous population of stromal cells residing in most connective tissues and have the capacity to suppress effector cells of the immune system. MSCs were engineered to express MOG-targeting receptors using lentiviral vectors. Genetically engineered MSCs retained their suppressive capacity in vitro and successfully targeted the brain upon intranasal delivery. Engineered MSCs cured mice from disease symptoms and these mice were resistant to further EAE challenge. Encephalitic T cells isolated from cured mice displayed an anergic profile while peripheral T cells were still responsive to stimuli.In conclusion, MS patients have peripheral CNS-reactive T cells of both Th1 and Th17 type that, while in remission, are kept in anergy. Also, MS patients in relapse exhibit increased levels of CD25 negative Tregs indicating an attempt to restrain immune activity. Finally, immunosuppressive cells can be genetically engineered to target CNS and efficiently suppress encephalomyelitis in an active EAE model upon intranasal delivery.