DNA vaccination with CD25 protects rats from adjuvant arthritis and induces an antiergotypic response

Abstract

MethodsRats. Female Lewis rats were raised and maintained under pathogen-free conditions in the Animal Breeding Center of the Weizmann Institute. Experiments were carried out under the supervision and guidelines of the Animal Welfare Committee. The rats were 4-6 weeks old at the beginning of the experiments.Plasmids and DNA vaccination. The coding sequence for the α-chain of the rat IL-2 receptor (IL-2Ra; CD25) was cloned into the pcDNA3 expression vector (Invitrogen Corp., San Diego, California, USA) in the BamHI-XbaI sites. The γ-chain of the IL-2 receptor (IL-2Rg) CD132, which is constitutively expressed on T cells (8-10), was cloned in the BamHI-XhoI sites. The empty pcDNA3 vector was used as a control. Plasmid DNA was prepared in large scale using the Qiagen Plasmid Maxi Kit (QIAGEN GmbH, Hilden, Germany). DNA was eluted to a final concentration of 1 mg/ml. In each experiment, groups of eight rats were injected intramuscular-DNA vaccination with CD25 protects rats from adjuvant arthritis and induces an antiergotypic response Ab's to the α α-chain of the IL-2 receptor (anti-CD25) are used clinically to achieve immunosuppression. Here we investigated the effects of DNA vaccination with the whole CD25 gene on the induction of rat adjuvant arthritis. The DNA vaccine protected the rats and led to a shift in the cytokine profile of T cells responding to disease target antigens from Th1 to Th2. The mechanism of protection was found to involve the induction of an antiergotypic response, rather than the induction of anti-CD25 Ab's. Antiergotypic T cells respond to activation molecules, ergotopes, expressed on syngeneic activated, but not resting, T cells. CD25-derived peptides function as ergotopes that can be recognized by the antiergotypic T cells. Antiergotypic T cells taken from control sick rats did not proliferate against activated T cells and secreted mainly IFN-γ γ. In contrast, antiergotypic cells from CD25-DNA-protected rats proliferated against activated T cells and secreted mainly IL-10. Protective antiergotypic T cells were found in both the CD4 + and CD8 + populations and expressed α α/ /β β or γ γ/ /δ δ T cell receptors. Antiergotypic α α/ /β β T cells were MHC restricted, while γ γ/ /δ δ T cells were MHC independent. Thus, CD25 DNA vaccination may induce protection from autoimmunity by inducing a cytokine shift in both the antiergotypic response and the response to the antigens targeted in the disease.

CD4+regulatory T cell responses induced by T cell vaccination in patients with multiple sclerosis

“…It should be noted that the same patterns of In this study, we present important evidence indicating that CD4 ϩ regulatory T cells, mainly the CD4 ϩ CD25 ϩ Foxp3 ϩ population, induced by T cell vaccination preferentially recognize an epitope corresponding to residues 61-73 of the IL-2 receptor ␣ chain. The result is consistent with the observed reactivity of antiergotypic T cells with IL-2 receptor ␣ chain in rodents (11). Furthermore, this unique property of peptide 61-73 becomes more evident as it is able to elicit CD4 ϩ regulatory T cell responses in postimmunization specimens.…”

“…It was also evident in a number of studies that in addition to CD8 ϩ antiidiotypic T cells, T cell vaccination induces CD4 ϩ regulatory T cell responses in both experimental autoimmune encephalomyelitis and human MS (7,10). CD4 ϩ regulatory T cell responses may represent an important immune regulatory component relevant to clinical effects of T cell vaccination (7,9,11). However, the nature and functional properties of these CD4 ϩ regulatory T cells are poorly understood.…”

“…However, the nature and functional properties of these CD4 ϩ regulatory T cells are poorly understood. It has been suggested that CD4 ϩ regulatory T cell responses may be induced through interaction with certain T cell markers loosely and collectively called ''ergotopes'' (7,11,12). There have been some indications that T cell activation molecules such as IL-2 receptor and heat-shock protein 60 may be among candidate ergotopes (11)(12)(13)(14).…”

“…It has been suggested that CD4 ϩ regulatory T cell responses may be induced through interaction with certain T cell markers loosely and collectively called ''ergotopes'' (7,11,12). There have been some indications that T cell activation molecules such as IL-2 receptor and heat-shock protein 60 may be among candidate ergotopes (11)(12)(13)(14). It has been a topic of great interest to characterize the nature and functional properties of human CD4 ϩ regulatory T cell responses induced by T cell vaccination in clinical trials because the findings would have direct implication in the understanding of the potential therapeutic role of T cell vaccination in human autoimmune conditions.…”

“…However, the functional properties and regulatory mechanism of CD4 ϩ regulatory T cells, especially in humans, are poorly understood. In experimental animal models, there is some evidence suggesting that at least a portion of CD4 ϩ T cells induced by T cell vaccination represent antiergotypic T cells and recognize candidate ergotopes, such as IL-2 receptor ␣ chain and heat-shock protein 60 (11)(12)(13). In this study, we demonstrated that CD4 ϩ regulatory T cells induced in MS patients by T cell vaccination are largely composed of T cell populations of two distinct patterns distinguishable by the expression of Foxp3 and cytokine profile.…”