MHC Variant Peptide-Mediated Anergy of Encephalitogenic T Cells Requires SHP-1

Abstract

Our lab has demonstrated that encephalitogenic T cells can be effectively anergized by treatment with MHC variant peptides, which are analogues of immunogenic peptides containing an amino acid substitution at an MHC anchor residue. The MHC variant peptide of myelin oligodendrocyte glycoprotein (MOG)35–55 proves an effective treatment as it does not induce symptoms of experimental autoimmune encephalomyelitis and fails to recruit macrophages or MOG35–55-specific T cells to the CNS. In this study, we sought to characterize the signaling pathways required for the induction of anergy by building upon the observations identifying the tyrosine phosphatase SHP-1 as a critical regulator of T cell responsiveness. Motheaten viable heterozygous mice, which contain a mutation in the SHP-1 gene resulting in a reduction in functional SHP-1, were challenged with MOG35–55 or the MOG35–55 MHC variant 45D. These mice display symptoms of experimental autoimmune encephalomyelitis upon immunization with MHC variant peptide and have significant CNS infiltration of tetramer-positive CD4+ cells and macrophages, unlike B6 mice challenged with the variant peptide. The effects of SHP-1 are directly on the T cell as Motheaten viable heterozygous mice autoreactive T cells are not anergized in vitro. Lastly, we demonstrate no distinguishable difference in the initial interaction between the TCR and agonist or MHC variant. Rather, an unstable interaction between peptide and MHC attenuates the T cell response, seen in a decreased half-life relative to MOG35–55. These results identify SHP-1 as a mediator of T cell anergy induced by destabilized peptide:MHC complexes.

CD8+ T Cell Responses to a Viral Escape Mutant Epitope: Active Suppression via Altered SHP-1 Activity

“…Furthermore, results from our lab using the mouse model for multiple sclerosis, experimental autoimmune encephalomyelitis, have shown that CD4 ϩ T cells become anergized upon recognition of epitopes that have low affinity for MHC (17,18). We have also implicated SHP-1 as the mediator of the anergic phenotype upon weak ligand recognition in experimental autoimmune encephalomyelitis (46). Future studies are needed to determine whether the signaling that does occur in CD8 ϩ T cells responding to viral escape mutants imprints an irreversible unresponsive phenotype such as that seen in CD4 ϩ T cells.…”

Taming the TCR: Antigen-Specific Immunotherapeutic Agents for Autoimmune Diseases

“…In vitro analyses of APLs derived from this epitope showed that some could act as antagonists towards some T cell clones and as agonists or superagonists towards others, while other APLs were capable of antagonizing a broader range of T cell clones [113,114]. Person-to-person differences in APL responsiveness were also observed: T cell clones derived from different HLA-DRB1 * 15:01 + MS patients displayed bias towards particular TCR variable gene segments and different patterns of cross-reactivity to MBP [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97] and the APL A91 (numbered according to the human sequence) [115]. In one patient, MBP 83-97 and A91 selected cross-reactive T cell clones, demonstrating that both peptides agonized the same pool of T cells, while in another patient MBP [83][84][85][86][87][88][89][90][91][92][93][94][95][96][97] and A91 selected independent, non-cross-reactive T cell clones.…”

“…The means by which IFN-γ mediates the MVP-induced protection in this scenario is not completely understood, but a regulatory mechanism that may be involved is negative feedback to TCR signaling by SHP-1. In mice expressing low levels of SHP-1, the MVP failed to induce hyporesponsiveness in SHP-1 low , MOG 35-55 -specific T cells, and became encephalitogenic [94]. In CIA, an MVP peptide known as A12 has been described, which is derived from the CII 259-273 epitope.…”

Adhesion Frequency Assay for <em>In Situ</em> Kinetics Analysis of Cross-Junctional Molecular Interactions at the Cell-Cell Interface

“…The assay has been validated using interactions of Fcγ receptors with IgG Fc 1-6 , selectins with glycoconjugate ligands 6-9 , integrins with ligands 10-13 , homotypical cadherin binding 14 , T cell receptor and coreceptor with peptide-major histocompatibility complexes [15][16][17][18][19] .…”

“…Varying the contact time generates a binding curve. Fitting a probabilistic model for receptor-ligand reaction kinetics 1 to the binding curve returns the 2D affinity and off-rate.The assay has been validated using interactions of Fcγ receptors with IgG Fc 1-6 , selectins with glycoconjugate ligands 6-9 , integrins with ligands 10-13 , homotypical cadherin binding 14 , T cell receptor and coreceptor with peptide-major histocompatibility complexes [15][16][17][18][19] .The method has been used to quantify regulations of 2D kinetics by biophysical factors, such as the membrane microtopology 5 , membrane anchor 2 , molecular orientation and length 6 , carrier stiffness 9 , curvature 20 , and impingement force 20 , as well as biochemical factors, such as modulators of the cytoskeleton and membrane microenvironment where the interacting molecules reside and the surface organization of these molecules 15,17,19 .The method has also been used to study the concurrent binding of dual receptor-ligand species 3,4 , and trimolecular interactions 19 using a modified model 21 .The major advantage of the method is that it allows study of receptors in their native membrane environment. The results could be very different from those obtained using purified receptors 17 .…”