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Meeting report : DC2018

Meeting report from Ophélie Vermeulen, recipient of a CFCD travel award.

The 15th International Symposium on Dendritic Cells, jointly organized by dutch and german
scientists took place in Aachen (Germany) from the 10th to the 14th of June, this year. Invited
and selected speakers gave great talks about DC in cancer and cancer immunotherapy, DC in
allergy and autoimmunity, DC development and ontogeny and several other domains.
Workshop sessions and around 300 posters completed the rich program of this symposium.

Yasmine Belkaid (National Institute of Allergy and Infectious Diseases, Bethesda, MD/US) gave
a presentation about the role of skin microbiota on the activation of immune cells and
inflammation. By applying microbes on the mouse skin her team could distinguish an immune
signature within the skin depending on the microbe. For instance, Corynebacterium was
shown to activate gamma-delta T cells in the skin without any detectable inflammation.
However, a simple change in diet can impact the microbiota influence and induce
inflammation. She gave the proof that the ability of a microbe to cause a disease is contextual.

Burkhard Becher (Institute of Experimental Immunology, Zurich, Swiss) presented
unpublished results about the role of GM-CSF in Experimental Autoimmune Encephalomyelitis
(EAE). By using genetically engineered mouse models such as the Fate Map and Reporter of
GM-CSF mouse (FROG), he showed that CD8 and CD4 T lymphocytes, Innate Lymphoid Cells
and Natural Killer Cells are the main cell types producing GM-CSF in the central nervous
system. He also demonstrated that the EAE score was inferior when the GM-CSF producing
cells were removed (FROG DTA mice) but the CD4 T Cell infiltration was still the same. Finally,
he demonstrated that GM-CSF producing cells were sensible to IL-23 and in a lesser extent to
IL-1 but not IL-6 (cytokine-blind FROG mice).

Damya Laoui (Vrije Universiteit Brussel, Brussels, Belgium) showed published results about
tumor-associated dendritic cells (TADC) and cDC vaccination. Briefly, she demonstrated that
several tumor-types are infiltrated by TADC recapitulating the myeloid infiltration in human
tumors. Then she went through the antigen uptake capacities and antigen presentation
capacities of the distinct subsets of DC in LLC-ova-associated DC. She demonstrated that cDC1
had better capacities to present antigens to OT-I CD8 T cells than cDC2 while cDC2 had greater
capacities to present antigens to OT-II CD4 T cells than cDC1. She finally demonstrated that
cDC1 vaccination is more beneficial than cDC2 vaccination in B16-melanoma model while
cDC2 vaccination is more beneficial than cDC1 vaccination in LLC-ova tumor bearing mice, thus
highlighting the important impact of the tumor micro-environment on DC functions and
effects on tumor immunity.

Dimitry Gabrilovich (The Wistar Insitute, Philadelphia, PA/US) gave a presentation about
cross-presenting capacities of tumor-associated dendritic cells. First, he demonstrated that DC
in cancer are defective in cross-presentation. By using Flow Cytometry analysis and confocal
microscopy he demonstrated that in Tumor Explant Supernatant (TES)-treated DC, pMHC
complex were largely intracellular and the presence of pMHC complex within the cell surface
was consistently decreased compared to untreated DC. The mechanism involved is based on
oxidized lipids binding to Hsp70 inhibiting its function and impacting DC cross-presentation.

Bart Lambrecht (VIB-UGent Center for Inflammation Research, Belgium) presented
unpublished data about the impact of Galectin 10 polymerization in DC during allergy. He
demonstrated that Charcot-Leyden (CL) crystals present in the mucus of patients were
composed by Galectin 10 polymerized protein produced by eosinophils. He got protein
crystals from patients and demonstrated that Galectin 10 can form crystals in vitro like in vivo.
In vivo, he demonstrated that polymerized-Galectin 10 injection induced a high increase in
neutrophils within the lungs 6h hours after injection and that the polymerized-protein
boosted the T cell presentation by antigen presenting cells, recapitulating the pathological
situation in human beings. He highlighted a non-polymerized form of Galectin 10 that
presented a Tyr69Glu mutation and generated an antibody in lama that could completely
dissolve crystals within minutes in vitro. This antibody was also shown to have dissolving
properties on human mucus and mice, giving new therapeutic strategies for asthma and

Allan Mowat (University of Glasgow, UK) gave a presentation about the development of the
CD103+ CD11b+ DC sub-population in the intestine. He demonstrated that the absence of
TGFßR1-mediated signaling in CD11c expressing cells was associated with an important
decrease in the number of CD103+ CD11b+ DC and a reciprocal increase in the CD103- CD11b+
DC subset in the intestinal mucosa. Reduced numbers of endogenous Th17 cells and inducible
FoxP3+ CD4 T cells were associated with the defect in CD103+ CD11b+ DC.

I would like to thank the CFCD for giving me the opportunity to participate to the 15th
International Symposium on Dendritic Cells to learn major scientific breakthrough and to
present my data during the poster session.