Systemic lupus erythematosus (SLE) is characterized by abnormalities in T lymphocyte receptor–mediated signal transduction pathways. Our previous studies have established that lymphocyte-specific protein tyrosine kinase (LCK) is reduced in T lymphocytes from patients with SLE and that this reduction is associated with disease activity and parallels an increase in LCK ubiquitination independent of T cell activation. This study investigated the expression of molecules that regulate LCK homeostasis, such as CD45, C-terminal Src kinase (CSK), and c-Cbl, in lipid raft domains from SLE T cells and investigated the localization of these proteins during T cell receptor (TCR) triggering. Our results indicate that the expression of raft-associated ganglioside, GM1, is increased in T cells from SLE patients and LCK may be differentially regulated due to an alteration in the association of CD45 with lipid raft domains. CD45 tyrosine phosphatase, which regulates LCK activity, was differentially expressed and its localization into lipid rafts was increased in T cells from patients with SLE. Furthermore, T cells allowed to “rest” in vitro showed a reversal of the changes in LCK, CD45, and GM1 expression. The results also revealed that alterations in the level of GM1 expression and lipid raft occupancy cannot be induced by serum factors from patients with SLE but indicated that cell-cell contact, activating aberrant proximal signaling pathways, may be important in influencing abnormalities in T cell signaling and, therefore, function in patients with SLE.
Elizabeth C. Jury, Panagiotis S. Kabouridis, Fabian Flores-Borja, Rizgar A. Mageed, David A. Isenberg
Autoimmune sensorineural hearing loss (ASNHL) is characterized typically by bilateral, rapidly progressive hearing loss that responds therapeutically to corticosteroid treatment. Despite its name, data implicating autoimmunity in the etiopathogenesis of ASNHL have been limited, and targeted self-antigens have not been identified. In the current study we show that the inner ear–specific proteins cochlin and β-tectorin are capable of targeting experimental autoimmune hearing loss (EAHL) in mice. Five weeks after immunization of SWXJ mice with either Coch 131–150 or β-tectorin 71–90, auditory brainstem responses (ABR) showed significant hearing loss at all frequencies tested. Flow cytometry analysis showed that each peptide selectively activated CD4+ T cells with a proinflammatory Th1-like phenotype. T cell mediation of EAHL was determined by showing significantly increased ABR thresholds 6 weeks after adoptive transfer of peptide-activated CD4+ T cells into naive SWXJ recipients. Immunocytochemical analysis showed that leukocytic infiltration of inner ear tissues coincided with onset of hearing loss. Our study provides a contemporary mouse model for clarifying our understanding of ASNHL and facilitating the development of novel effective treatments for this clinical entity. Moreover, our data provide experimental confirmation that ASNHL may be a T cell–mediated organ-specific autoimmune disorder of the inner ear.
C. Arturo Solares, Andrea E. Edling, Justin M. Johnson, Moo-Jin Baek, Keiko Hirose, Gordon B. Hughes, Vincent K. Tuohy
We describe the generation of mice that express a transgenic T cell receptor (TCR) (5B6) specific for the encephalitogenic myelin proteolipid protein (PLP) peptide 139–151, on the experimental autoimmune encephalomyelitis–resistant (EAE-resistant) B10.S background. Despite harboring a high frequency of self-reactive T cells, 5B6 transgenic mice on the B10.S background rarely develop spontaneous EAE, which is in striking contrast to 5B6 transgenic mice on the EAE-susceptible SJL background. The relative resistance to spontaneous EAE in transgenic B10.S mice is not due to deletion or anergy of T cells, but appears to be controlled by APCs. Analysis of APCs revealed a lower activation state and a lower T cell–activating capacity for APCs from B10.S mice than for those from EAE-susceptible SJL mice. When APCs in 5B6 transgenic B10.S mice were activated, for example, via TLR9 or TLR4, T cell tolerance was broken, resulting in EAE. Our findings demonstrate that activation of APCs via innate immune receptors can break self tolerance and trigger the development of autoimmunity even in a genetically resistant strain. These findings suggest that the development of autoimmune diseases such as multiple sclerosis is determined at least partly by the endogenous activation state of APCs.
Hanspeter Waldner, Mary Collins, Vijay K. Kuchroo
Whether and how T cells contribute to the pathogenesis of immunoglobulin A nephropathy (IgAN) has not been well defined. Here, we explore a murine model that spontaneously develops T cell–mediated intestinal inflammation accompanied by pathological features similar to those of human IgAN. Intestinal inflammation mediated by LIGHT, a ligand for lymphotoxin β receptor (LTβR), not only stimulates IgA overproduction in the gut but also results in defective IgA transportation into the gut lumen, causing a dramatic increase in serum polymeric IgA. Engagement of LTβR by LIGHT is essential for both intestinal inflammation and hyperserum IgA syndrome in our LIGHT transgenic model. Impressively, the majority of patients with inflammatory bowel disease showed increased IgA-producing cells in the gut, elevated serum IgA levels, and severe hematuria, a hallmark of IgAN. These observations indicate the critical contributions of dysregulated LIGHT expression and intestinal inflammation to the pathogenesis of IgAN.
Jing Wang, Robert A. Anders, Qiang Wu, Dacheng Peng, Judy H. Cho, Yonglian Sun, Reda Karaliukas, Hyung-Sik Kang, Jerrold R. Turner, Yang-Xin Fu
Ab’s to the 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. 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/β or γ/δ T cell receptors. Antiergotypic α/β T cells were MHC restricted, while γ/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.
Avishai Mimran, Felix Mor, Pnina Carmi, Francisco J. Quintana, Varda Rotter, Irun R. Cohen
A number of studies have suggested B7-H1, a B7 family member, inhibits T cell responses. Therefore, its expression on nonlymphoid tissues has been proposed to prevent T cell–mediated tissue destruction. To test this hypothesis, we generated transgenic mice that expressed B7-H1 on pancreatic islet β cells. Surprisingly, we observed accelerated rejection of transplanted allogeneic B7-H1–expressing islet β cells. Furthermore, transgenic B7-H1 expression broke immune tolerance, as some of the mice spontaneously developed T cell–dependent autoimmune diabetes. In addition, B7-H1 expression increased CD8+ T cell proliferation and promoted autoimmunity induction in a T cell adoptive transfer model of diabetes. Consistent with these findings, B7-H1.Ig fusion protein augmented naive T cell priming both in vitro and in vivo. Our results demonstrate that B7-H1 can provide positive costimulation for naive T cells to promote allograft rejection and autoimmune disease pathogenesis.
Sumit K. Subudhi, Ping Zhou, Lisa M. Yerian, Robert K. Chin, James C. Lo, Robert A. Anders, Yonglian Sun, Lieping Chen, Yang Wang, Maria-Luisa Alegre, Yang-Xin Fu
The principal effect of TGF-β1 on mesenchymal cells is its stimulation of ECM synthesis. Previous reports indicated the significance of the autocrine TGF-β loop in the pathogenesis of scleroderma. In this study, we focused on Smad7 and Smurfs, principal molecules in the negative regulation of TGF-β signaling, to further understand the autocrine TGF-β loop in scleroderma. Scleroderma fibroblasts exhibited increased Smad7 levels compared with normal fibroblasts in vivo and in vitro. Smad7 constitutively formed a complex with the TGF-β receptors, and the inhibitory effect of Smad7 on the promoter activity of human α2(I) collagen and 3TP-lux was completely impaired in scleroderma fibroblasts. Furthermore, the protein stability of TGF-β receptor type I was significantly increased in scleroderma fibroblasts compared with normal fibroblasts. There was no significant difference in Smurf1 and Smurf2 levels between normal and scleroderma fibroblasts, and the transiently overexpressed Smurf1 and/or Smurf2 did not affect TGF-β receptor type I protein levels in scleroderma fibroblasts. These results indicate that the impaired Smad7-Smurf–mediated inhibitory effect on TGF-β signaling might contribute to maintaining the autocrine TGF-β loop in scleroderma fibroblasts. To our knowledge, this is the first report of a disturbed negative regulation of TGF-β signaling in fibrotic disorders.
Yoshihide Asano, Hironobu Ihn, Kenichi Yamane, Masahide Kubo, Kunihiko Tamaki
Relapsing polychondritis is a multisystem autoimmune disease involving cartilage destruction but no known causative antigen. HLA-DQ8 has been associated with various autoimmune diseases in humans. To study the role of DQ8 in autoimmune diseases, we have generated transgenic mice expressing DQ8 (DQA1*0301, DQB1*0302) in a NOD background lacking endogenous class II molecules (Aβo). Upon immunization with type II collagen (CII), 85% of NOD.DQ8 mice develop severe experimental polychondritis, auricular chondritis, and polyarthritis, with clinical and histological similarities to relapsing polychondritis (RP) in humans. CII-immunized mice mount a T cell response and produce Ab’s to type IX collagen (CIX) and self-CII. Transgene-negative littermates do not develop any serological and clinical manifestations following immunization. B10.DQ8 transgenic mice develop polyarthritis and Ab’s to CII only. The susceptibility to auricular chondritis in NOD.DQ8 mice can be attributed to response to CIX. A higher number of activated cells, CD4+CD44hiCD62Llo, and lower regulatory cells CD4+CD152+CD25+ were observed in NOD.DQ8 mice compared with B10.DQ8 mice. The NOD.DQ8 mice provide a model of RP with a high disease incidence and multiple organ involvement to investigate putative autoantigen and regulatory cells involved in disease pathogenesis. An experimental model restricted by the human class II molecule will be valuable when studying the role of various collagens in immunologic and pathologic responses in human RP.
Veena Taneja, Marie Griffiths, Marshall Behrens, Harvinder S. Luthra, Chella S. David
To determine the role of CD154-CD40 interactions in the B cell overactivity exhibited by patients with active systemic lupus erythematosus (SLE), CD19+ peripheral B cells were examined before and after treatment with humanized anti-CD154 mAb (BG9588, 5c8). Before treatment, SLE patients manifested activated B cells that expressed CD154, CD69, CD38, CD5, and CD27. Cells expressing CD38, CD5, or CD27 disappeared from the periphery during treatment with anti-CD154 mAb, and cells expressing CD69 and CD154 disappeared from the periphery during the post-treatment period. Before treatment, active-SLE patients had circulating CD38bright Ig-secreting cells that were not found in normal individuals. Disappearance of this plasma cell subset during treatment was associated with decreases in anti–double-stranded DNA (anti-dsDNA) Ab levels, proteinuria, and SLE disease activity index. Consistent with this finding, peripheral B cells cultured in vitro spontaneously proliferated and secreted Ig in a manner that was inhibited by anti-CD154 mAb. Finally, the CD38+/++IgD+, CD38+++, and CD38+IgD– B cell subsets present in the peripheral blood also disappeared following treatment with humanized anti-CD154. Together, these results indicate that patients with active lupus nephritis exhibit abnormalities in the peripheral B cell compartment that are consistent with intensive germinal center activity, are driven via CD154-CD40 interactions, and may reflect or contribute to the propensity of these patients to produce autoantibodies.
Amrie C. Grammer, Rebecca Slota, Randy Fischer, Hanan Gur, Hermann Girschick, Cheryl Yarboro, Gabor G. Illei, Peter E. Lipsky
Psoriasis is a chronic inflammatory disease of the skin characterized by epidermal hyperplasia, dermal angiogenesis, infiltration of activated T cells, and increased cytokine levels. One of these cytokines, IL-15, triggers inflammatory cell recruitment, angiogenesis, and production of other inflammatory cytokines, including IFN-γ, TNF-α, and IL-17, which are all upregulated in psoriatic lesions. To investigate the role of IL-15 in psoriasis, we generated mAb’s using human immunoglobulin-transgenic mice. One of the IL-15–specific antibodies we generated, 146B7, did not compete with IL-15 for binding to its receptor but potently interfered with the assembly of the IL-15 receptor α, β, γ complex. This antibody effectively blocked IL-15–induced T cell proliferation and monocyte TNF-α release in vitro. In a human psoriasis xenograft model, antibody 146B7 reduced the severity of psoriasis, as measured by epidermal thickness, grade of parakeratosis, and numbers of inflammatory cells and cycling keratinocytes. These results obtained with this IL-15–specific mAb support an important role for IL-15 in the pathogenesis of psoriasis.
Louise S. Villadsen, Janine Schuurman, Frank Beurskens, Tomas N. Dam, Frederik Dagnæs-Hansen, Lone Skov, Jørgen Rygaard, Marleen M. Voorhorst-Ogink, Arnout F. Gerritsen, Marc A. van Dijk, Paul W.H.I. Parren, Ole Baadsgaard, Jan G.J. van de Winkel
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