Immune responses against self-TCR peptides

Antigenized antibodies expressing Vbeta8.2 TCR peptides immunize against rat experimental allergic encephalomyelitis

Background

Immunity against the T cell receptor (TCR) is considered to play a central role in the regulation of experimental allergic encephalomyelitis (EAE), a model system of autoimmune disease characterized by a restricted usage of TCR genes. Methods of specific vaccination against the TCR of pathogenetic T cells have included attenuated T cells and synthetic peptides from the sequence of the TCR. These approaches have led to the concept that anti-idiotypic immunity against antigenic sites of the TCR, which are a key regulatory element in this disease.

Methods

The present study in the Lewis rat used a conventional idiotypic immunization based on antigenized antibodies expressing selected peptide sequences of the Vβ8.2 TCR (⁹³ASSDSSNTE¹⁰¹ and ³⁹DMGHGLRLIHYSYDVNSTEKG⁵⁹).

Results

The study demonstrates that vaccination with antigenized antibodies markedly attenuates, and in some instances, prevents clinical EAE induced with the encephalitogenic peptide ⁶⁸GSLPQKSQRSQDENPVVHF⁸⁸ in complete Freunds' adjuvant (CFA). Antigenized antibodies induced an anti-idiotypic response against the Vβ8.2 TCR, which was detected by ELISA and flowcytometry. No evidence was obtained of a T cell response against the corresponding Vβ8.2 TCR peptides.

Conclusions

The results indicate that antigenized antibodies expressing conformationally-constrained TCR peptides are a simple means to induce humoral anti-idiotypic immunity against the TCR and to vaccinate against EAE. The study also suggests the possibility to target idiotypic determinants of TCR borne on pathogenetic T cells to vaccinate against disease.

A novel inflammatory eye disease induced by lymphocytes from knockout mice sensitized against the deleted ocular antigen

Lens-associated uveitis (LAU), a severe inflammatory eye disease, is thought to be mediated by autoimmunity against lens crystallins. Previously described animal models for this disease are antibody-mediated, since no cellular response to self crystallins could be induced in experimental animals. Here, we describe a new model for LAU, in which lymphocytes from knockout mice deficient in alphaB-crystallin are sensitized against the deleted protein and induce severe ocular inflammation when adoptively transferred into wild type recipients. Similar to LAU, the experimental disease developed only following rupture of the lens capsule, produced in this study by capsulotomy; no disease was detected in recipient eyes with no capsulotomy, or in those treated with cautery, or in eyes affected by systemic treatment with sodium iodate, lipopolysaccharide or X-irradiation. The ocular changes in affected eyes included heavy cellular infiltration and proteinaceous exudate in both the anterior and posterior segments of the eye, that reached their peak on day 4 following cell transfer and subsided quite rapidly thereafter.

Acquired resistance to experimental autoimmune encephalomyelitis is independent of V beta usage

In Lewis rats, activated encephalitogenic T-helper cells elicit a single bout of experimental autoimmune encephalomyelitis (EAE). Recovery from EAE is marked by reduced susceptibility to disease reinduction. The purpose of this study was to determine whether a dominant expression of V beta gene segments by encephalitogenic T cells was required for development of recovery-associated resistance. Several polyclonal and monoclonal T cell lines were derived from Lewis rats sensitized with R72-86, a synthetic peptide representing the 72- to 86-amino-acid sequence of rat myelin basic protein (RMBP). The results revealed broad heterogeneity among encephalitogenic T cells specific for R72-86 in regard to V beta expression and CDR3 sequence. Encephalitogenic clones exclusively bearing either V beta 4 or V beta 10 TCR or polyclonal T cells bearing heterogeneous TCR transferred EAE to recipient rats and elicited resistance to EAE as revealed by subsequent challenge with guinea pig (GP)MBP in complete Freund's adjuvant (CFA). Nonpathogenic V beta 3+ and V beta 8.6+ clones specific for the 68-86 and 55-66 regions of MBP, respectively, did not elicit effective protection from EAE. These data indicate that induction of postrecovery resistance to EAE does not depend upon a particular V beta usage.

Immunotolerance and prevention of ocular autoimmune disease

Immunotherapeutic approaches to autoimmune disease have a common goal of inducing antigen-specific, long-lasting tolerance to autoantigens, without otherwise compromising the immune response. Here we review some of the most interesting experimental advances in this area. We discuss the use of T cell targeting drugs that have been reported to induce long lasting tolerance to ocular antigens. Strategies involving the targeting of idiotypic and clonotypic determinants associated with ocular autoimmunity, such as idiotypic network manipulation and T cell vaccination, are reviewed. The use of cytokines to promote perturbation of the Th1/Th2 balance with its possible implications for treatment of uveitis, is analysed. Finally, we review tolerogenic strategies based on acquisition of tolerance following presentation of antigen through alternative routes, such as injection of antigen into the anterior chamber, intravenous infusion of antigen, and oral administration of retinal antigens. Special emphasis is placed on the last strategy, since there are ongoing clinical trials using oral tolerance as an immunotherapeutic approach to treat autoimmune diseases, among them uveitis.