Showing papers by "Arthur A. Vandenbark published in 2005"

Decreased FOXP3 levels in multiple sclerosis patients.

Abstract: Autoimmune diseases such as multiple sclerosis (MS) may result from the failure of tolerance mechanisms to prevent expansion of pathogenic T cells. Our study is the first to establish that MS patients have abnormalities in FOXP3 message and protein expression levels in peripheral CD4+CD25+ T cells (Tregs) that are quantitatively related to a reduction in functional suppression induced during suboptimal T-cell receptor (TCR) ligation. Of importance, this observation links a defect in functional peripheral immunoregulation to an established genetic marker that has been unequivocally shown to be involved in maintaining immune tolerance and preventing autoimmune diseases. Diminished FOXP3 levels thus indicate impaired immunoregulation by Tregs that may contribute to MS. Future studies will evaluate the effects of therapies known to influence Treg cell function and FOXP3 expression, including TCR peptide vaccination and supplemental estrogen. © 2005 Wiley-Liss, Inc.

Middle-Age Male Mice Have Increased Severity of Experimental Autoimmune Encephalomyelitis and Are Unresponsive to Testosterone Therapy

Abstract: Treatment with sex hormones is known to protect against experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. However, little is known about how age affects the course of EAE or response to hormone treatment. This study demonstrates striking differences between middle-age vs young C57BL/6 male mice in the clinical course of EAE and response to both testosterone (T4) and estrogen (E2) hormone therapy. Unlike young males that developed an acute phase of EAE followed by a partial remission, middle-age males suffered severe chronic and unremitting EAE that was likely influenced by alterations in the distribution and function of splenic immunocytes and a significant reduction in suppressive activity of CD4+CD25+ regulatory T cells in the spleen and spinal cord. Middle-age males had reduced numbers of splenic CD4+ T cells that were generally hypoproliferative, but enhanced numbers of splenic macrophages and MHC class II-expressing cells, and increased secretion of the proinflammatory factors IFN-γ and MCP-1. Surprisingly, middle-age males were unresponsive to the EAE-protective effects of T4 and had only a transient benefit from E2 treatment; young males were almost completely protected by both hormone treatments. T4 treatment of young males inhibited proliferation of myelin oligodendrocyte glycoprotein 35–55-specific T cells and secretion of TNF-α and IFN-γ. The effects of T4 in vivo and in vitro were reversed by the androgen receptor antagonist, flutamide, indicating that the regulatory effects of T4 were mediated through the androgen receptor. These data are the first to define age-dependent differences in EAE expression and response to hormone therapy.

Treatment of passive experimental autoimmune encephalomyelitis in SJL mice with a recombinant TCR ligand induces IL-13 and prevents axonal injury.

Abstract: The major goal of this study was to evaluate the efficacy and mechanism of a rTCR ligand (RTL) construct (I-A(s)/proteolipid protein (PLP)-139-151 peptide = RTL401) for treatment of SJL/J mice developing passive experimental autoimmune encephalomyelitis (EAE) that did not involve coimmunization with the highly inflammatory CFA. Our results demonstrated clearly that RTL401 was highly effective in treating passive EAE, with kinetics of recovery from disease very similar to treatment of actively induced EAE. The potent RTL401 treatment effect was reflected by a partial reduction of infiltrating mononuclear cells into CNS, minimal inflammatory lesions in spinal cord, and preservation of axons injured in vehicle-treated mice during the progression of EAE. Interestingly, in the absence of CFA, RTL401 treatment strongly enhanced production of the Th2 cytokine, IL-13, in spleen, blood, and spinal cord tissue, with variable effects on other Th1 and Th2 cytokines, and no significant effect on the Th3 cytokine, TGF-beta1, or on FoxP3 that is expressed by regulatory T cells. Moreover, pretreatment of PLP-139-151-specific T cells with RTL401 in vitro induced high levels of secreted IL-13, with lesser induction of other pro- and anti-inflammatory cytokines. Given the importance of IL-13 for protection against EAE, these data strongly implicate IL-13 as a dominant regulatory cytokine induced by RTL therapy. Pronounced IL-13 levels coupled with marked reduction in IL-6 levels secreted by PLP-specific T cells from blood after treatment of mice with RTL401 indicate that IL-13 and IL-6 may be useful markers for following effects of RTL therapy in future clinical trials in multiple sclerosis.

Rationally designed mutations convert complexes of human recombinant T cell receptor ligands into monomers that retain biological activity.

Abstract: Single-chain human recombinant T cell receptor ligands derived from the peptide binding/TCR recognition domain of human HLA-DR2b (DRA*0101/DRB1*1501) produced in Escherichia coli with and without amino-terminal extensions containing antigenic peptides have been described previously. While molecules with the native sequence retained biological activity, they formed higher order aggregates in solution. In this study, we used site-directed mutagenesis to modify the β-sheet platform of the DR2-derived RTLs, obtaining two variants that were monomeric in solution by replacing hydrophobic residues with polar (serine) or charged (aspartic acid) residues. Size exclusion chromatography and dynamic light scattering demonstrated that the modified RTLs were monomeric in solution, and structural characterization using circular dichroism demonstrated the highly ordered secondary structure of the RTLs. Peptide binding to the `empty' RTLs was quantified using biotinylated peptides, and functional studies showed that the modified RTLs containing covalently tethered peptides were able to inhibit antigen-specific T cell proliferation in vitro, as well as suppress experimental autoimmune encephalomyelitis in vivo. These studies demonstrated that RTLs encoding the Ag-binding/TCR recognition domain of MHC class II molecules are innately very robust structures, capable of retaining potent biological activity separate from the Ig-fold domains of the progenitor class II structure, with prevention of aggregation accomplished by modification of an exposed surface that was buried in the progenitor structure.

Activation Pathways Implicate Anti-HLA-DP and Anti-LFA-1 Antibodies as Lead Candidates for Intervention in Chronic Berylliosis

Abstract: CD4(+) T cells play a key role in granulomatous inflammation in the lung of patients with chronic beryllium disease. The goal of this study was to characterize activation pathways of beryllium-responsive bronchoalveolar lavage (BAL) CD4(+) T cells from chronic beryllium disease patients to identify possible therapeutic interventional strategies. Our results demonstrate that in the presence of APCs, beryllium induced strong proliferation responses of BAL CD4(+) T cells, production of superoptimal concentrations of secreted proinflammatory cytokines, IFN-gamma, TNF-alpha,and IL-2, and up-regulation of numerous T cell surface markers that would promote T-T Ag presentation. Ab blocking experiments revealed that anti-HLA-DP or anti-LFA-1 Ab strongly reduced proliferation responses and cytokine secretion by BAL CD4(+) T cells. In contrast, anti-HLA-DR or anti-OX40 ligand Ab mainly affected beryllium-induced proliferation responses with little impact on cytokines other than IL-2, thus implying that nonproliferating BAL CD4(+) T cells may still contribute to inflammation. Blockade with CTLA4-Ig had a minimal effect on proliferation and cytokine responses, confirming that activation was independent of B7/CD28 costimulation. These results indicate a prominent role for HLA-DP and LFA-1 in BAL CD4(+) T cell activation and further suggest that specific Abs to these molecules could serve as a possible therapy for chronic beryllium disease.

T Cell Hybridomas And Related Compositions And Methods For Assaying And Modulating T Cell Receptor-Mediated Immune Responses

Abstract: The present invention provides T cell hybridomas and related compositions and assay systems for investigative, diagnostic, and therapeutic use in modulating T cell receptor (TCR)-mediated immune response. The T cell hybridomas of the invention are typically constructed by fusing a naive or early central memory T cell isolated from a mammalian subject with an immortalizing fusion partner (e.g. mammalian lymphoid tumor cell) to yield clonal T cell hybrids. The resulting T cell hybridomas exhibit antigen (Ag)-specific proliferation responsiveness over a background level of proliferation of the hybridomas. These hybridomas are useful for screening, identifying, and characterizing T cell immune modulatory agents, for example recombinant T cell receptor ligands (RTLs) and other agents that can modulate TCR-mediated T cell immune responses. Ag-specific proliferative response profiles exhibited by the T cell hybridomas of the invention show sufficient amplitude, sensitivity and fidelity to distinguish and/or quantify the presence and/or activity of a test RTL or other test modulatory agent in screening and sensitivity assays employing the hybridomas. These and other aspects of the invention yield powerful tools and methods for developing and characterizing novel RTLs and other immune modulatory agents for use in treating immune disorders, including a wide range of autoimmune diseases, in mammals.

T cell hybridomas

Abstract: The present invention provides T cell hybridomas and related compositions and assay systems for investigative, diagnostic, and therapeutic use in modulating T cell receptor (TCR)-mediated immune response. The T cell hybridomas of the invention are typically constructed by fusing a naive or early central memory T cell isolated from a mammalian subject with an immortalizing fusion partner (e.g. mammalian lymphoid tumor cell) to yield clonal T cell hybrids. The resulting T cell hybridomas exhibit antigen (Ag)-specific proliferation responsiveness over a background level of proliferation of the hybridomas. These hybridomas are useful for screening, identifying, and characterizing T cell immune modulatory agents, for example recombinant T cell receptor ligands (RTLs) and other agents that can modulate TCR-mediated T cell immune responses. Ag-specific proliferative response profiles exhibited by the T cell hybridomas of the invention show sufficient amplitude, sensitivity and fidelity to distinguish and/or quantify the presence and/or activity of a test RTL or other test modulatory agent in screening and sensitivity assays employing the hybridomas. These and other aspects of the invention yield powerful tools and methods for developing and characterizing novel RTLs and other immune modulatory agents for use in treating immune disorders, including a wide range of autoimmune diseases, in mammals.

Peptides restreints par mhc classe ii derives d'antigenes specifiques a la prostate et leur utilisation dans des vaccins destines a traiter ou a prevenir le cancer de la prostate

Abstract: La presente invention concerne des peptides immunogeniques derives de l'antigene humain du cancer de la prostate (peptides derives de PSA) et leur utilisation en tant que vaccins dans le traitement ou la prevention du cancer de la prostate L'invention concerne aussi des cellules dendritiques provenant d'un patient souffrant du cancer de la prostate, lesdites cellules dendritiques ayant ete exposees a un ou plusieurs peptides derives de PSA ainsi que leur utilisation pour traiter ou prevenir le cancer de la prostate chez le patient L'invention concerne aussi des lymphocytes T provenant d'un patient les cellules duquel sont specifiques a un ou plusieurs peptides actives par PSA et leur utilisation pour traiter ou prevenir le cancer de la prostate