Adult neural stem cells (aNSCs) derived from the subventricular zone of the brain show therapeutic effects in EAE, an animal model of the chronic inflammatory neurodegenerative disease MS; however, the beneficial effects are modest. One critical weakness of aNSC therapy may be an insufficient antiinflammatory effect. Here, we demonstrate that i.v. or i.c.v. injection of aNSCs engineered to secrete IL-10 (IL-10–aNSCs), a potent immunoregulatory cytokine, induced more profound functional and pathological recovery from ongoing EAE than that with control aNSCs. IL-10–aNSCs exhibited enhanced antiinflammatory effects in the periphery and inflammatory foci in the CNS compared with control aNSCs, more effectively reducing myelin damage, a hallmark of MS. When compared with mice treated with control aNSCs, those treated with IL-10–aNSCs demonstrated differentiation of transplanted cells into greater numbers of oligodendrocytes and neurons but fewer astrocytes, thus enhancing exogenous remyelination and neuron/axonal growth. Finally, IL-10–aNSCs converted a hostile environment to one supportive of neurons/oligodendrocytes, thereby promoting endogenous remyelination. Thus, aNSCs engineered to express IL-10 show enhanced ability to induce immune suppression, remyelination, and neuronal repair and may represent a novel approach that can substantially improve the efficacy of neural stem cell–based therapy in EAE/MS.
Jingxian Yang, Zhilong Jiang, Denise C. Fitzgerald, Cungen Ma, Shuo Yu, Hongmei Li, Zhao Zhao, Yonghai Li, Bogoljub Ciric, Mark Curtis, Abdolmohamad Rostami, Guang-Xian Zhang
Ania Skowera, Richard J. Ellis, Ruben Varela-Calviño, Sefina Arif, Guo Cai Huang, Cassie Van-Krinks, Anna Zaremba, Chloe Rackham, Jennifer S. Allen, Timothy I.M. Tree, Min Zhao, Colin M. Dayan, Andrew K. Sewell, Wendy W. Unger, Jan W. Drijfhout, Ferry Ossendorp, Bart O. Roep, Mark Peakman
Bim, the B cell lymphoma 2–interacting (Bcl2-interacting) mediator, maintains immunological tolerance by deleting autoreactive lymphocytes through apoptosis. We report here that Bim is also, paradoxically, required for the activation of autoreactive T cells. Deletion of Bim in hematopoietic cells rendered mice resistant to autoimmune encephalomyelitis and diabetes, and Bim-deficient T cells had diminished cytokine production. Upon T cell receptor activation, Bim-deficient T cells exhibited severe defects in both calcium release and dephosphorylation of nuclear factor of activated T cells (NFAT) but maintained normal levels of activation of NF-κB and MAPKs. The defective calcium signaling in Bim-deficient T cells was associated with a significant increase in the formation of an inhibitory complex containing Bcl2 and the inositol triphosphate receptor (IP3R). Thus, in addition to mediating the death of autoreactive T cells, Bim also controlled T cell activation through the IP3R/calcium/NFAT pathway. These results indicate that a single protein is used to control both the activation and apoptosis of autoreactive T cells and may explain why Bim-deficient mice do not reject their own organs despite lacking thymic negative selection.
Maciej W. Ludwinski, Jing Sun, Brendan Hilliard, Shunyou Gong, Fan Xue, Ruaidhri J. Carmody, Jennifer DeVirgiliis, Youhai H. Chen
The clear association of Th17 cells with autoimmune pathogenicity implicates Th17 cytokines as critical mediators of chronic autoimmune diseases such as EAE. To study the impact of IL-17A on CNS inflammation, we generated transgenic mice in which high levels of expression of IL-17A could be initiated after Cre-mediated recombination. Although ubiquitous overexpression of IL-17A led to skin inflammation and granulocytosis, T cell–specific IL-17A overexpression did not have a perceptible impact on the development and health of the mice. In the context of EAE, neither the T cell–driven overexpression of IL-17A nor its complete loss had a major impact on the development of clinical disease. Since IL-17F may be able to compensate for the loss of IL-17A, we also generated IL-17F–deficient mice. This strain was fully susceptible to EAE and displayed unaltered emergence and expansion of autoreactive T cells during disease. To eliminate potential compensatory effects of either cytokine, we treated IL-17F–deficient mice with antagonistic monoclonal antibodies specific for IL-17A and found again only a minimal beneficial impact on disease development. We conclude therefore that both IL-17A and IL-17F, while prominently expressed by an encephalitogenic T cell population, may only marginally contribute to the development of autoimmune CNS disease.
Stefan Haak, Andrew L. Croxford, Katharina Kreymborg, Frank L. Heppner, Sandrine Pouly, Burkhard Becher, Ari Waisman
Multiple sclerosis (MS) is a chronic inflammatory disease that results in demyelination in the central nervous system, and a defect in the regulatory function of CD4+CD25high T cells has been implicated in the pathogenesis of the disease. Here, we reanalyzed the function of this T cell subset in patients with MS, but we depleted cells expressing IL-7 receptor α-chain (CD127), a marker recently described as present on activated T cells but not Tregs. Similar to other studies, we observed a marked defect in the suppressive function of unseparated CD4+CD25high T cells isolated from MS patients. However, when CD127high cells were removed from the CD4+CD25high population, patient and control cells inhibited T cell proliferation and cytokine production equally. Likewise, when the CD25 gate used to sort the cells was stringent enough to eliminate CD127high cells, CD4+CD25high T cells from patients with MS and healthy individuals had similar regulatory function. Additional analysis indicated that the CD127high cells within the CD4+CD25high T cell population from patients with MS appeared more proliferative and secreted more IFN-γ and IL-2 than the same cells from healthy individuals. Taken together, we conclude that CD4+CD25highCD127low Tregs from MS patients and healthy individuals exhibit similar suppressive functions. The decreased inhibitory function of unfractioned CD4+CD25high cells previously observed might be due to abnormal activation of CD127high T cells in patients with MS.
Laure Michel, Laureline Berthelot, Ségolène Pettré, Sandrine Wiertlewski, Fabienne Lefrère, Cécile Braudeau, Sophie Brouard, Jean-Paul Soulillou, David-Axel Laplaud
Homozygous loss-of-function mutations in AIRE cause autoimmune polyglandular syndrome type 1 (APS 1), which manifests in a classic triad of hypoparathyroidism, adrenal insufficiency, and candidiasis. Interestingly, a kindred with a specific G228W AIRE variant presented with an autosomal dominant autoimmune phenotype distinct from APS 1. We utilized a novel G228W-knockin mouse model to show that this variant acted in a dominant-negative manner to cause a unique autoimmunity syndrome. In addition, the expression of a large number of Aire-regulated thymic antigens was partially inhibited in these animals, demonstrating the importance of quantitative changes in thymic antigen expression in determining organ-specific autoimmunity. Furthermore, the dominant-negative effect of the G228W variant was exerted through recruitment of WT Aire away from active sites of transcription in the nucleus of medullary thymic epithelial cells in vivo. Together, these results may demonstrate a mechanism by which autoimmune predisposition to phenotypes distinct from APS 1 can be mediated in a dominant-negative fashion by Aire.
Maureen A. Su, Karen Giang, Kristina Žumer, Huimin Jiang, Irena Oven, John L. Rinn, Jason J. DeVoss, Kellsey P.A. Johannes, Wen Lu, James Gardner, Angela Chang, Paula Bubulya, Howard Y. Chang, B. Matija Peterlin, Mark S. Anderson
IFN-β, a type I IFN, is widely used for the treatment of MS. However, the mechanisms behind its therapeutic efficacy are not well understood. Using a murine model of MS, EAE, we demonstrate that the Th17-mediated development of autoimmune disease is constrained by Toll–IL-1 receptor domain–containing adaptor inducing IFN-β–dependent (TRIF-dependent) type I IFN production and its downstream signaling pathway. Mice with defects in TRIF or type I IFN receptor (IFNAR) developed more severe EAE. Notably, these mice exhibited marked CNS inflammation, as manifested by increased IL-17 production. In addition, IFNAR-dependent signaling events were essential for negatively regulating Th17 development. Finally, IFN-β–mediated IL-27 production by innate immune cells was critical for the immunoregulatory role of IFN-β in the CNS autoimmune disease. Together, our findings not only may provide a molecular mechanism for the clinical benefits of IFN-β in MS but also demonstrate a regulatory role for type I IFN induction and its downstream signaling pathways in limiting Th17 development and autoimmune inflammation.
Beichu Guo, Elmer Y. Chang, Genhong Cheng
A hallmark of SLE is the production of high-titer, high-affinity, isotype-switched IgG autoantibodies directed against nucleic acid–associated antigens. Several studies have established a role for both type I IFN (IFN-I) and the activation of TLRs by nucleic acid–associated autoantigens in the pathogenesis of this disease. Here, we demonstrate that 2 IFN-I signaling molecules, IFN regulatory factor 9 (IRF9) and STAT1, were required for the production of IgG autoantibodies in the pristane-induced mouse model of SLE. In addition, levels of IgM autoantibodies were increased in pristane-treated Irf9–/– mice, suggesting that IRF9 plays a role in isotype switching in response to self antigens. Upregulation of TLR7 by IFN-α was greatly reduced in Irf9–/– and Stat1–/– B cells. Irf9–/– B cells were incapable of being activated through TLR7, and Stat1–/– B cells were impaired in activation through both TLR7 and TLR9. These data may reveal a novel role for IFN-I signaling molecules in both TLR-specific B cell responses and production of IgG autoantibodies directed against nucleic acid–associated autoantigens. Our results suggest that IFN-I is upstream of TLR signaling in the activation of autoreactive B cells in SLE.
Donna L. Thibault, Alvina D. Chu, Kareem L. Graham, Imelda Balboni, Lowen Y. Lee, Cassidy Kohlmoos, Angela Landrigan, John P. Higgins, Robert Tibshirani, Paul J. Utz
TLRs may contribute to the progression of rheumatoid arthritis through recognition of microbial or host-derived ligands found in arthritic joints. Here, we show that TLR2 and TLR4, but not TLR9, are involved in the pathogenesis of autoimmune arthritis and play distinct roles in the regulation of T cells and cytokines. We investigated the involvement of TLR2, TLR4, and TLR9 in the progression of arthritis using IL-1 receptor antagonist–knockout (IL1rn–/–) mice, which spontaneously develop an autoimmune T cell–mediated arthritis. Spontaneous onset of arthritis was dependent on TLR activation by microbial flora, as germ-free mice did not develop arthritis. Clinical and histopathological evaluation of IL1rn–/–Tlr2–/– mice revealed more severe arthritis, characterized by reduced suppressive function of Tregs and substantially increased IFN-γ production by T cells. IL1rn–/–Tlr4–/– mice were, in contrast, protected against severe arthritis and had markedly lower numbers of Th17 cells and a reduced capacity to produce IL-17. A lack of Tlr9 did not affect the progression of arthritis. While any therapeutic intervention targeting TLR2 still seems complicated, the strict position of TLR4 upstream of a number of pathogenic cytokines including IL-17 provides an interesting potential therapeutic target for rheumatoid arthritis.
Shahla Abdollahi-Roodsaz, Leo A.B. Joosten, Marije I. Koenders, Isabel Devesa, Mieke F. Roelofs, Timothy R.D.J. Radstake, Marleen Heuvelmans-Jacobs, Shizuo Akira, Martin J.H. Nicklin, Fátima Ribeiro-Dias, Wim B. van den Berg
Autoimmune encephalomyelitis, a mouse model for multiple sclerosis, is characterized by the activation of immune cells, demyelination of axons in the CNS, and paralysis. We found that TGF-β1 synthesis in glial cells and TGF-β–induced signaling in the CNS were activated several days before the onset of paralysis in mice with autoimmune encephalomyelitis. While early production of TGF-β1 was observed in glial cells TGF-β signaling was activated in neurons and later in infiltrating T cells in inflammatory lesions. Systemic treatment with a pharmacological inhibitor of TGF-β signaling ameliorated the paralytic disease and reduced the accumulation of pathogenic T cells and expression of IL-6 in the CNS. Priming of peripheral T cells was not altered, nor was the generation of TH17 cells, indicating that this effect was directed within the brain, yet affected the immune system. These results suggest that early production of TGF-β1 in the CNS creates a permissive and dangerous environment for the initiation of autoimmune inflammation, providing a rare example of the brain modulating the immune system. Importantly, inhibition of TGF-β signaling may have benefits in the treatment of the acute phase of autoimmune CNS inflammation.
Jian Luo, Peggy P. Ho, Marion S. Buckwalter, Tiffany Hsu, Lowen Y. Lee, Hui Zhang, Dae-Kee Kim, Seong-Jin Kim, Sanjiv S. Gambhir, Lawrence Steinman, Tony Wyss-Coray
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