A humanized HLA-DR4 mouse model for autoimmune myocarditis

WOS: 000403386800003PubMed ID: 28431892Myocarditis, the principal cause of dilated cardiomyopathy and heart failure in young adults, is associated with autoimmunity to human cardiac alpha-myosin (hCAM) and the DR4 allele of human major histocompatibility II (MHCII). We developed an hCAM-induced myocarditis model in human HLA-DR4 transgenic mice that lack all mouse MHCII genes, demonstrating that immunization for 3 weeks significantly increased splenic T-cell proliferative responses and titres of IgG1 and IgG2c antibodies, abolished weight gain, provoked cardiac inflammation and significantly impaired cardiac output and fractional shortening, by echocardiography, compared to adjuvant -injected mice. Neither cardiac dilatation nor fibrosis occurred at this time point but prolonging the experiment was associated with mortality. Treatment with mixtures of hCAM derived peptides predicted to have high affinity for DR4 significantly preserved ejection fraction and fractional shortening. Our new humanized mouse model of autoimmune cardiomyopathy should be useful to refine hCAM-derived peptide treatment. (C) 2017 The Authors. Published by Elsevier Ltd.Turkish Ministry of EducationTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); British Heart FoundationBritish Heart Foundation [CH95/001]; Apitope International NVMES was supported by a Postgraduate Scholarship from the Turkish Ministry of Education. ACN was supported by a British Heart Foundation Chair CH95/001. Apitope International NV, supported the research, in part, through a grant in aid

Early growth response gene 2 (Egr-2) controls the self-tolerance of T cells and prevents the development of lupuslike autoimmune disease

© 2008 Zhu et al. This article is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).Maintaining tolerance of T cells to self-antigens is essential to avoid autoimmune disease. How self-reactive T cells are kept functionally inactive is, however, unknown. In this study, we show that early growth response gene 2 (Egr-2), a zinc-finger transcription factor, is expressed in CD44(high) T cells and controls their proliferation and activation. In the absence of Egr-2, CD44(high), but not CD44(low) T cells, are hyperreactive and hyperproliferative in vivo. The accumulation of activated CD4(+)CD44(high) T cells leads to the development of a late onset lupuslike autoimmune disease characterized by the accumulation of interferon (IFN)-gamma and interleukin (IL)-17-producing CD4(+) T cells, loss of tolerance to nuclear antigens, massive infiltration of T cells into multiple organs and glomerulonephritis. We found that the expression of cyclin-dependent kinase inhibitor p21cip1 was impaired in Egr-2-deficient T cells, whereas the expression of IFN-gamma and IL-17 in response to T cell receptor ligation was significantly increased, suggesting that Egr-2 activates the expression of genes involved in the negative regulation of T cell proliferation and inflammation. These results demonstrate that Egr-2 is an intrinsic regulator of effector T cells and controls the expansion of self-reactive T cells and development of autoimmune disease.The Biotechnology and Biological Sciences Research Council, the Medical Research Council and the Wellcome Trust

Protein kinase C theta is required for efficient induction of IL-10-secreting T cells

<div><p>Secretion of interleukin-10 (IL-10) by CD4⁺ T cells is an essential immunoregulatory mechanism. The work presented here assesses the role of the signaling molecule protein kinase C theta (PKCθ) in the induction of IL-10 expression in CD4⁺ T cells. Using wildtype and PKCθ-deficient Tg4 T cell receptor transgenic mice, we implemented a well-described protocol of repeated doses of myelin basic protein (MBP)Ac1-9[4Y] antigen to induce Tr1-like IL-10⁺ T cells. We find that PKCθ is required for the efficient induction of IL-10 following antigen administration. Both serum concentrations of IL-10 and the proportion of IL-10⁺ T cells were reduced in PKCθ-deficient mice relative to wildtype mice following [4Y] treatment. We further characterized the T cells of [4Y] treated PKCθ-deficient Tg4 mice and found reduced expression of the transcription factors cMaf, Nfil3 and FoxP3 and the surface receptors PD-1 and Tim3, all of which have been associated with the differentiation or function of IL-10⁺ T cells. Finally, we demonstrated that, unlike [4Y] treated wildtype Tg4 T cells, cells from PKCθ-deficient mice were unable to suppress the priming of naïve T cells <i>in vitro</i> and <i>in vivo</i>. In summary, we present data demonstrating a role for PKCθ in the induction of suppressive, IL-10-secreting T cells induced in TCR-transgenic mice following chronic antigen administration. This should be considered when contemplating PKCθ as a suitable drug target for inducing immune suppression and graft tolerance.</p></div

Negative Selection during the Peripheral Immune Response to Antigen

Thymic selection depends on positive and negative selective mechanisms based on the avidity of T cell interaction with antigen–major histocompatibility complex complexes. However, peripheral mechanisms for the recruitment and clonal expansion of the responding T cell repertoire remain obscure. Here we provide evidence for an avidity-based model of peripheral T cell clonal expansion in response to antigenic challenge. We have used the encephalitogenic, H-2 Au-restricted, acetylated NH2-terminal nonameric peptide (Ac1-9) epitope from myelin basic protein as our model antigen. Peptide analogues were generated that varied in antigenic strength (as assessed by in vitro assay) based on differences in their binding affinity for Au. In vivo, these analogues elicited distinct repertoires of T cells that displayed marked differences in antigen sensitivity. Immunization with the weakest (wild-type) antigen expanded the high affinity T cells required to induce encephalomyelitis. In contrast, immunization with strongly antigenic analogues led to the elimination of T cells bearing high affinity T cell receptors by apoptosis, thereby preventing disease development. Moreover, the T cell repertoire was consistently tuned to respond to the immunizing antigen with the same activation threshold. This tuning mechanism provides a peripheral control against the expansion of autoreactive T cells and has implications for immunotherapy and vaccine design

Epigenetic modification of the PD-1 (Pdcd1) promoter in effector CD4(+) T cells tolerized by peptide immunotherapy

Clinically effective antigen-based immunotherapy must silence antigen-experienced effector T cells (Teff) driving ongoing immune pathology. Using CD4+ autoimmune Teff cells, we demonstrate that peptide immunotherapy (PIT) is strictly dependent upon sustained T cell expression of the co-inhibitory molecule PD-1. We found high levels of 5-hydroxymethylcytosine (5hmC) at the PD-1 (Pdcd1) promoter of non-tolerant T cells. 5hmC was lost in response to PIT, with DNA hypomethylation of the promoter. We identified dynamic changes in expression of the genes encoding the Ten-Eleven-Translocation (TET) proteins that are associated with the oxidative conversion 5-methylcytosine and 5hmC, during cytosine demethylation. We describe a model whereby promoter demethylation requires the co-incident expression of permissive histone modifications at the Pdcd1 promoter together with TET availability. This combination was only seen in tolerant Teff cells following PIT, but not in Teff that transiently express PD-1. Epigenetic changes at the Pdcd1 locus therefore determine the tolerizing potential of TCR-ligation. - See more at: http://elifesciences.org/content/3/e03416#sthash.n6isQlkn.dpu

Glycogen synthase kinase-3 controls IL-10 expression in CD4⁺effector T-cell subsets through epigenetic modification of the IL-10 promoter

The serine/threonine kinase glycogen synthase kinase-3 (GSK3) plays an important role in balancing pro- and anti-inflammatory cytokines. We have examined the role of GSK3 in production of IL-10 by subsets of CD4(+) T helper cells. Treatment of naive murine CD4(+) T cells with GSK3 inhibitors did not affect their production of IL-10. However, treatment of Th1 and Th2 cells with GSK3 inhibitors dramatically increased production of IL-10. GSK3 inhibition also led to upregulation of IL-10 among Th1, Th2, and Th17 subsets isolated from human blood. The encephalitogenic potential of GSK3 inhibitor treated murine Th1 cells was significantly reduced in adoptive transfer experiments by an IL-10-dependent mechanism. Analysis of the murine IL-10 promoter in response to inhibition of GSK3 in Th1 cells showed modification to a transcriptionally active state indicated by changes in histone H3 acetylation and methylation. Additionally, GSK3 inhibition increased expression of the transcription factors c-Maf, Nfil3, and GATA3, correlating with the increase in IL-10. These findings are important in the context of autoimmune disease since they show that it is possible to reprogram disease-causing cells through GSK3 inhibition

Regulatory T Cell Migration Is Dependent on Glucokinase-Mediated Glycolysis.

Migration of activated regulatory T (Treg) cells to inflamed tissue is crucial for their immune-modulatory function. While metabolic reprogramming during Treg cell differentiation has been extensively studied, the bioenergetics of Treg cell trafficking remains undefined. We have investigated the metabolic demands of migrating Treg cells in vitro and in vivo. We show that glycolysis was instrumental for their migration and was initiated by pro-migratory stimuli via a PI3K-mTORC2-mediated pathway culminating in induction of the enzyme glucokinase (GCK). Subsequently, GCK promoted cytoskeletal rearrangements by associating with actin. Treg cells lacking this pathway were functionally suppressive but failed to migrate to skin allografts and inhibit rejection. Similarly, human carriers of a loss-of-function GCK regulatory protein gene-leading to increased GCK activity-had reduced numbers of circulating Treg cells. These cells displayed enhanced migratory activity but similar suppressive function, while conventional T cells were unaffected. Thus, GCK-dependent glycolysis regulates Treg cell migration