@article{LangenhorstTabaresGuldeetal.2018,
  author    = {Langenhorst, Daniela and Tabares, Paula and Gulde, Tobias and Becklund, Bryan R. and Berr, Susanne and Surh, Charles D. and Beyersdorf, Niklas and H{\"u}nig, Thomas},
  title     = {Self-recognition sensitizes mouse and human regulatory T cells to low-dose CD28 superagonist stimulation},
  series = {Frontiers in Immunology},
  volume    = {8},
  journal   = {Frontiers in Immunology},
  number    = {1985},
  doi       = {10.3389/fimmu.2017.01985},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159387},
  year      = {2018},
  abstract  = {In rodents, low doses of CD28-specific superagonistic monoclonal antibodies (CD28 superagonists, CD28SA) selectively activate regulatory T cells (Treg). This observation has recently been extended to humans, suggesting an option for the treatment of autoimmune and inflammatory diseases. However, a mechanistic explanation for this phenomenon is still lacking. Given that CD28SA amplify T cell receptor (TCR) signals, we tested the hypothesis that the weak tonic TCR signals received by conventional CD4\(^{+}\) T cells (Tconv) in the absence of cognate antigen require more CD28 signaling input for full activation than the stronger TCR signals received by self-reactive Treg. We report that in vitro, the response of mouse Treg and Tconv to CD28SA strongly depends on MHC class II expression by antigen-presenting cells. To separate the effect of tonic TCR signals from self-peptide recognition, we compared the response of wild-type Treg and Tconv to low and high CD28SA doses upon transfer into wild-type or H-2M knockout mice, which lack a self-peptide repertoire. We found that the superior response of Treg to low CD28SA doses was lost in the absence of self-peptide presentation. We also tested if potentially pathogenic autoreactive Tconv would benefit from self-recognition-induced sensitivity to CD28SA stimulation by transferring TCR transgenic OVA-specific Tconv into OVA-expressing mice and found that low-dose CD28SA application inhibited, rather than supported, their expansion, presumably due to the massive concomitant activation of Treg. Finally, we report that also in the in vitro response of human peripheral blood mononuclear cells to CD28SA, HLA II blockade interferes with the expansion of Treg by low-dose CD28SA stimulation. These results provide a rational basis for the further development of low-dose CD28SA therapy for the improvement of Treg activity.},
  language  = {en}
}
@article{ZadehKhorasaniNolteMuelleretal.2013,
  author    = {Zadeh-Khorasani, Maryam and Nolte, Thomas and Mueller, Thomas D. and Pechlivanis, Markos and Rueff, Franziska and Wollenberg, Andreas and Fricker, Gert and Wolf, Eckhard and Siebeck, Matthias and Gropp, Roswitha},
  title     = {NOD-scid IL2R \(\gamma^{null}\) mice engrafted with human peripheral blood mononuclear cells as a model to test therapeutics targeting human signaling pathways},
  series = {Journal of Translational Medicine},
  volume    = {11},
  journal   = {Journal of Translational Medicine},
  number    = {4},
  issn      = {1479-5876},
  doi       = {10.1186/1479-5876-11-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-122960},
  year      = {2013},
  abstract  = {Background: Animal models of human inflammatory diseases have limited predictive quality for human clinical trials for various reasons including species specific activation mechanisms and the immunological background of the animals which markedly differs from the genetically heterogeneous and often aged patient population. Objective: Development of an animal model allowing for testing therapeutics targeting pathways involved in the development of Atopic Dermatitis (AD) with better translatability to the patient. Methods: NOD-scid IL2R \(\gamma^{null}\) mice engrafted with human peripheral blood mononuclear cells (hPBMC) derived from patients suffering from AD and healthy volunteers were treated with IL-4 and the antagonistic IL-4 variant R121/Y124D (Pitrakinra). Levels of human (h) IgE, amount of B-, T- and plasma-cells and ratio of CD4 : CD8 positive cells served as read out for induction and inhibition of cell proliferation and hIgE secretion. Results were compared to in vitro analysis. Results: hIgE secretion was induced by IL-4 and inhibited by the IL-4 antagonist Pitrakinra in vivo when formulated with methylcellulose. B-cells proliferated in response to IL-4 in vivo; the effect was abrogated by Pitrakinra. IL-4 shifted CD4 : CD8 ratios in vitro and in vivo when hPBMC derived from healthy volunteers were used. Pitrakinra reversed the effect. Human PBMC derived from patients with AD remained inert and engrafted mice reflected the individual responses observed in vitro. Conclusion: NOD-scid IL2R \(\gamma^{null}\) mice engrafted with human PBMC reflect the immunological history of the donors and provide a complementary tool to in vitro studies. Thus, studies in this model might provide data with better translatability from bench to bedside.},
  language  = {en}
}
@phdthesis{RomerRoche2012,
  author    = {Romer Roche, Paula Sofia},
  title     = {Separation from self explains failure of circulating T-cells to respond to the CD28 superagonist TGN1412},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74933},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Stimulatory or superagonistic (SA) CD28-specific monoclonal antibodies (mAbs) are potent polyclonal activators of regulatory T cells and have proven highly effective as treatment in a wide range of rodent models for autoimmune and inflammatory diseases. In these models, a preferential activation of regulatory T cells was observed by in vivo administration of CD28SA. In stark contrast, human volunteers receiving TGN1412, a humanized CD28-specific mAb, experienced a life-threatening cytokine release syndrome during the first-in-man trial. Preclinical tests employing human peripheral blood mononuclear cells (PBMC) failed to announce the rapid cytokine release measured in the human volunteers in response to TGN1412. The aim of this thesis project was to find an explanation of why standard PBMC assays failed to predict the unexpected TGN1412-induced "cytokine storm" observed in human volunteers. CD28 superagonists can activate T cells without T cell receptor (TCR) ligation. They do depend, however, on "tonic" TCR signals received by MHC scanning, signals that they amplify. PBMC do not receive these signals in the circulation. Short-term in vitro preculture of human PBMC at a high cell density (HDC) resulted in massive cytokine release during subsequent TGN1412 stimulation. Restoration of reactivity was cell-contact dependent, associated with TCR polarization and tyrosine-phosphorylation, and blocked by HLA-specific mAb. In HDC, both CD4 T cells and monocytes functionally mature in a mutually dependent fashion. However, only CD4 memory T-cells proliferate upon TGN1412 stimulation, and were identified as the main source of pro-inflammatory cytokines. Importantly, responses to other T-cell activating agents were also enhanced if PBMC were first allowed to interact under tissue-like conditions. A new in vitro protocol is provided that returns circulating T-cells to a tissue-like status where they respond to TGN1412 stimulation, and it might represent a more reliable preclinical in vitro test for both activating and inhibitory immunomodulatory drugs. Finally, the surprising observation was made that the IgG1 "sibling" of TGN1412, which is of the poorly Fc receptor-binding IgG4 isotype, has a much lower stimulatory activity. We could exclude steric hindrance as an explanation and provide evidence for removal of TGN1112 from the T-cell surface by trans-endocytosis.},
  subject      = {T-Lymphozyten-Rezeptor},
  language  = {en}
}