Lack of over-expression of T cell receptor Vbeta5.2 in myelin basic protein-specific T cell lines derived from HLA-DR2 positive multiple sclerosis patients and controls

Immunology of multiple sclerosis

Multiple sclerosis (MS) develops in young adults with a complex predisposing genetic trait and probably requires an inciting environmental insult such as a viral infection to trigger the disease. The activation of CD4+ autoreactive T cells and their differentiation into a Th1 phenotype are a crucial events in the initial steps, and these cells are probably also important players in the long-term evolution of the disease. Damage of the target tissue, the central nervous system, is, however, most likely mediated by other components of the immune system, such as antibodies, complement, CD8+ T cells, and factors produced by innate immune cells. Perturbations in immunomodulatory networks that include Th2 cells, regulatory CD4+ T cells, NK cells, and others may in part be responsible for the relapsing-remitting or chronic progressive nature of the disease. However, an important paradigmatic shift in the study of MS has occurred in the past decade. It is now clear that MS is not just a disease of the immune system, but that factors contributed by the central nervous system are equally important and must be considered in the future.

Complementarity-determining region 3 spectratyping analysis of the TCR repertoire in multiple sclerosis

Multiple sclerosis (MS) is considered to be an autoimmune disease mediated by T cells reactive with Ags in the CNS. Therefore, it has been postulated that neuroantigen-reactive T cells bearing particular types of TCRs are expanded clonally during the course of the disease. However, there is a controversy with regard to the TCR usage by T cells associated with the development of MS. By the use of complementarity-determining region 3 spectratyping analysis that is shown to be a useful tool for identification of pathogenic TCR in autoimmune disease models, we tried to demonstrate that spectratype was T cells bearing particular types of TCR are activated in MS patients. Consequently, it was found that Vbeta5.2 were often oligoclonally expanded in peripheral blood of MS patients, but not of healthy subjects. Sequence analysis of the complementarity-determining region 3 region of spectratype-derived TCR clones revealed that the predominant TCR clone was different from patient to patient, but that similar results were obtained in a patient examined at different time points. More importantly, examination of cerebrospinal fluid T cells and longitudinal studies of PBLs from selected patients revealed that Vbeta5.2 expansion was detectable in the majority of patients examined. These findings suggest that Vbeta5.2 spectratype expansion is associated with the development of MS and that TCR-based immunotherapy can be applicable to MS patients if the TCR activation pattern of each patient is determined at different stages of the disease.

Short-term dynamics of circulating T cell receptor V beta repertoire in relapsing-remitting MS

To understand the short-term dynamics of the circulating T cell receptor V beta (TCRBV) repertoire in relapsing-remitting multiple sclerosis (MS), we monitored the TCRBV profiles of untreated MS patients and healthy controls. Expansions of TCRBV genes in MS patients were significantly more frequent than in controls (P<0.001), were predominantly oligoclonal (80%) and were significantly correlated with immune responses to myelin basic protein (MBP) (P<0.02) and with inflammatory disease activity detected by magnetic resonance imaging (MRI) (P<0.05). Autoreactive T cell responses against myelin antigens may be implicated in perturbations of TCR repertoire in untreated MS patients, detectable even in the absence of clinically evident manifestations.

TCR peptide therapy in human autoimmune diseases

Inflammatory Th1 cells reacting to tissue/myelin derived antigens likely contribute to the pathogenesis of diseases such as multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. One regulatory mechanism that may be useful for treating autoimmune diseases involves an innate second set of Th2 cells specific for portions of the T cell receptor of clonally expanded pathogenic Th1 cells. These Th2 cells are programmed to respond to internally modified V region peptides from the T cell receptor (TCR) that are expressed on the Th1 cell surface in association with major histocompatibility molecules. Once the regulatory Th2 cells are specifically activated, they may inhibit inflammatory Th1 cells through a non-specific bystander mechanism. A variety of strategies have been used by us to identify candidate disease-associated TCR V genes present on pathogenic Th1 cells, including BV5S2, BV6S5, and BV13SI in MS, BV3, BV14, and BV17 in RA, and BV3 and BV13S1 in psoriasis. TCR peptides corresponding to the mid region of these BV genes were found to be consistently immunogenic in vivo when administered either i.d. in saline or i.m. in incomplete Freund's adjuvant (IFA). In MS patients, repeated injection of low doses of peptides (100-300 microg) significantly boosted the number of TCR-reactive Th2 cells. These activated cells secreted cytokines, including IL-10, that are known to inhibit inflammatory Th1 cells. Cytokine release could also be induced in TCR-reactive Th2 cells by direct cell-cell contact with Th1 cells expressing the target V gene. These findings indicate the potential of regulatory Th2 cells to inhibit not only the target Th1 cells, but also bystander Th1 cells expressing different V genes specific for other autoantigens. TCR peptide vaccines have been used in our studies to treat a total of 171 MS patients (6 trials), 484 RA patients (7 trials), and 177 psoriasis patients (2 trials). Based on this experience in 824 patients with autoimmune diseases, TCR peptide vaccination is safe and well tolerated, and can produce significant clinical improvement in a subset of patients that respond to immunization. TCR peptide vaccination represents a promising approach that is well-suited for treating complex autoimmune diseases.

Characterization of T cell receptor (TCR) of organ-specific autoimmune disease-inducing T cells and TCR-based immunotherapy with DNA vaccines

Organ-specific autoimmune diseases and their animal models are characterized by the finding that the development of the diseases is closely associated with, or induced by, T cells reactive to organ-specific antigens. Therefore, the identification of T cell receptors (TCR) used by disease-inducing T cells within a short period of time is a key factor for designing TCR-based immunotherapy. The findings introduced in this article show that TCR associated with the development of multiple sclerosis and experimental autoimmune diseases including encephalomyelitis (EAE), neuritis (EAN) and carditis (EAC) are identifiable by complementarity-determining region 3 (CDR3) spectratyping analysis and subsequent sequencing of the CDR3 region of spectratype-derived TCR clones. It is also demonstrated that immunotherapy targeting disease-associated TCR using monoclonal antibodies and DNA vaccines significantly reduced the histological severity, and completely suppressed the inflammation in some animals. Since depletion or suppression of one of several types of effector cells does not significantly improve the severity of the disease, combined TCR-based immunotherapy should be considered as a primary therapy for T cell-mediated autoimmune diseases. TCR-based immunotherapy after rapid identification of autoimmune disease-associated TCR by CDR3 spectratyping can be applicable, not only to animal, but also to human autoimmune diseases whose pathomechanism is poorly understood.