Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment

Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don't respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/β2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development

Access to a Cu^II–O–Cu^II Motif: Spectroscopic Properties, Solution Structure, and Reactivity

We report a complex with a rare Cu^II–O–Cu^II structural motif that is stable at room temperature, which allows its in-depth characterization by a variety of spectroscopic methods. Interest in such compounds is fueled by the recent discovery that a Cu^II–O–Cu^II species on the surface of Cu-ZSM-5 is capable of oxidizing methane to methanol, and this in turn ties into mechanistic discussions on the methane oxidation at the dicopper site within the particulate methane monooxygenase. For the synthesis of our <b>Cu</b>_<b>2</b><b>O</b> complex we have developed a novel, neutral ligand system, <b>FurNeu</b>, exhibiting two <i>N</i>-(<i>N</i>′,<i>N</i>′-dimethylaminoethyl)­(2-pyridylmethyl)­amino binding pockets connected by a dibenzofuran spacer. The reaction of <b>FurNeu</b> with CuCl yielded [<b>FurNeu</b>]­(Cu₂(μ-Cl))­(CuCl₂), <b>1</b>, demonstrating the geometric potential of the ligand to stabilize Cu–X–Cu moieties. A Cu^I precursor with weakly coordinating anions was chosen in the next step, namely [Cu­(NCCH₃)₄]­OTf, which led to the formation of [<b>FurNeu</b>]­(Cu­(NCCH₃))₂(OTf)₂, <b>3</b>. Treatment of <b>3</b> with O₂ or PhIO led to identical green solutions, whose UV–vis spectra were markedly different from the one displayed by [<b>FurNeu</b>]­(Cu)₂(OTf)₄, <b>4</b>, prepared independently from <b>FurNeu</b> and Cu­(OTf)₂. Further investigations including PhIO consumption experiments, NMR and UV–vis spectroscopy, HR-ESI mass spectrometry, and protonation studies led to the identification of the green product as [<b>FurNeu</b>]­(Cu₂(μ-O))­(OTf)₂, <b>5</b>. DOSY NMR spectroscopy confirmed its monomeric character. Over longer periods of time <b>5</b> decomposes to give [Cu­(picoloyl)₂], formed through an oxidative N-dealkylation reaction followed by further oxidation of the ligand. Due to its slow decomposition reaction, all attempts to crystallize <b>5</b> failed. However, its structure in solution could be determined by EXAFS analysis in combination with DFT calculations, which revealed a Cu–O–Cu angle that amounts to 105.17°. Moreover, TDDFT calculations helped to rationalize the UV–vis absorptions of <b>5</b>. The reactivity of complex <b>5</b> with 2,4-di-<i>tert</i>-butylphenol, DTBP, was also investigated; the initially formed biphenol product, TBBP, was found to further react in the presence of excessive O₂ to yield 2,4,7,9-tetra-<i>tert</i>-butyloxepino­[2,3-b]­benzofuran, TBOBF, via an intermediate diphenoquinone. It turned out that <b>5</b>, or its precursor <b>3</b>, can even be employed as a catalyst for the oxidation of DTBP to TBBP or for the oxidation of TBBP to TBOBF

Neurodegeneration by α-synuclein-specific T cells in AAV-A53T-α-synuclein Parkinson’s disease mice

Background Antigen-specific neuroinflammation and neurodegeneration are characteristic for neuroimmunological diseases. In Parkinson’s disease (PD) pathogenesis, α-synuclein is a known culprit. Evidence for α-synuclein-specific T cell responses was recently obtained in PD. Still, a causative link between these α-synuclein responses and dopaminergic neurodegeneration had been lacking. We thus addressed the functional relevance of α-synuclein-specific immune responses in PD in a mouse model. Methods We utilized a mouse model of PD in which an Adeno-associated Vector 1/2 serotype (AAV1/2) expressing human mutated A53T-α-Synuclein was stereotactically injected into the substantia nigra (SN) of either wildtype C57BL/6 or Recombination-activating gene 1 (RAG1)$^{-/-}$ mice. Brain, spleen, and lymph node tissues from different time points following injection were then analyzed via FACS, cytokine bead assay, immunohistochemistry and RNA-sequencing to determine the role of T cells and inflammation in this model. Bone marrow transfer from either CD4$^{+}$/CD8$^{-}$, CD4$^{-}$/CD8$^{+}$, or CD4$^{+}$/CD8$^{+}$ (JHD$^{-/-}$) mice into the RAG-1$^{-/-}$ mice was also employed. In addition to the in vivo studies, a newly developed A53T-α-synuclein-expressing neuronal cell culture/immune cell assay was utilized. Results AAV-based overexpression of pathogenic human A53T-α-synuclein in dopaminergic neurons of the SN stimulated T cell infiltration. RNA-sequencing of immune cells from PD mouse brains confirmed a pro-inflammatory gene profile. T cell responses were directed against A53T-α-synuclein-peptides in the vicinity of position 53 (68–78) and surrounding the pathogenically relevant S129 (120–134). T cells were required for α-synuclein-induced neurodegeneration in vivo and in vitro, while B cell deficiency did not protect from dopaminergic neurodegeneration. Conclusions Using T cell and/or B cell deficient mice and a newly developed A53T-α-synuclein-expressing neuronal cell culture/immune cell assay, we confirmed in vivo and in vitro that pathogenic α-synuclein peptide-specific T cell responses can cause dopaminergic neurodegeneration and thereby contribute to PD-like pathology

Tumor-derived GDF-15 blocks LFA-1 dependent T cell recruitment and suppresses responses to anti-PD-1 treatment

Abstract Immune checkpoint blockade therapy is beneficial and even curative for some cancer patients. However, the majority don’t respond to immune therapy. Across different tumor types, pre-existing T cell infiltrates predict response to checkpoint-based immunotherapy. Based on in vitro pharmacological studies, mouse models and analyses of human melanoma patients, we show that the cytokine GDF-15 impairs LFA-1/β2-integrin-mediated adhesion of T cells to activated endothelial cells, which is a pre-requisite of T cell extravasation. In melanoma patients, GDF-15 serum levels strongly correlate with failure of PD-1-based immune checkpoint blockade therapy. Neutralization of GDF-15 improves both T cell trafficking and therapy efficiency in murine tumor models. Thus GDF-15, beside its known role in cancer-related anorexia and cachexia, emerges as a regulator of T cell extravasation into the tumor microenvironment, which provides an even stronger rationale for therapeutic anti-GDF-15 antibody development