Preliminary data of an extended open label phase I study of T cell vaccination in multiple sclerosis

Beyond the Magic Bullet: Current Progress of Therapeutic Vaccination in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system (CNS) characterized by neuroinflammation, neurodegeneration and impaired repair mechanisms that lead to neurological disability. The crux of MS is the patient's own immune cells attacking self-antigens in the CNS, namely the myelin sheath that protects nerve cells of the brain and spinal cord. Restoring antigen-specific tolerance via therapeutic vaccination is an innovative and exciting approach in MS therapy. Indeed, leveraging the body's attempt to prevent autoimmunity, i.e., tolerization, focuses on the underlying cause of the disease and could be the key to solving neuroinflammation. In this perspective, antigen-specific vaccination targets only the detrimental and aberrant immune response against the specific disease-associated antigen(s) involved while retaining the capacity of the immune system to respond to unrelated antigens. We review the experimental approaches of tolerance-inducing vaccination in relapsing and progressive forms of MS that have reached the clinical development phase, including vaccination with autologous T cells, autologous tolerogenic dendritic cells, T cell receptor peptide vaccination, altered peptide ligand, ATX-MS-1467, cluster of differentiation (CD)-206-targeted liposomal myelin basic protein peptides and DNA vaccination. Failures, successes and future directions are discussed.

Cellular and humoral immune responses against autoreactive T cells in multiple sclerosis patients after T cell vaccination

Myelin basic protein (MBP)-reactive T cells may play an important role in the autoimmune pathogenesis of multiple sclerosis (MS). MBP-reactive T cells can be specifically targeted by T cell vaccination, a procedure whereby MS patients are immunized with attenuated autologous MBP reactive T cells. T cell vaccination induces immune responses to the vaccine cells together with a depletion of MBP reactive T cells. Forty-nine MS patients were treated with T cell vaccination in an extended phase I trial to study the safety, immune responses and clinical effects of T cell vaccination. In the present paper the immune responses towards the vaccine cells were characterized. Substantial long-term in vitro proliferative responses were observed in all treated patients. Some patients, immunized with different clones, displayed distinct proliferative reactivity against the various vaccine clones, suggesting unequal immunogenic properties of these clones. Reactive TCRalphabeta(+), CD8(+)and CD4(+)T cells, and to a lesser extent, gammadelta T cells and NK cells were observed to in vitro stimulation with the vaccine cells. A small fraction only of CD8(+)T cells expressed cytolytic and inhibitory anti-clonotypic reactivity against the vaccine cells. Stimulation with the vaccine clones predominantly induced expression of pro-inflammatory cytokines in these mixed cultures, although one vaccine clone consistently induced production of IL-4. CD4(+)T cells are the major cytokine-producing cells in these anti-vaccine lines. We could not detect upregulated antibody responses to the vaccine cells in most patients, although a temporary antibody response was observed in one patient. In conclusion, immunization with attenuated autoreactive T cells induces a complex cellular response specifically targeted at the vaccine cells, but no antibody responses. These data provide further insights into the mechanisms of T cell vaccination and improve our understanding of the complex regulatory networks of autoreactive T cells.