G. Trinchieri by Aikaterini Nasi
Cancer as a disease of the symbiont/metaorganism
In the lecture the importance of microbiota in cancer immune responses and success of anti cancer therapy was described.
Microorganisms and the host share many metabolic processes and the interplay between them affect inflammation and host immunity. The tumor microenvironment and the innate and adaptive immune responses are shaped both by genetic and environmental factors. Therefore the host-microbiome interactions can affect cancer development as it was suggested by Tlr5-/- and Il18-/- mice strains that develop bacterial dysbiosis and colon carcinogenesis.
The speaker asked the question whether cancer therapy is regulated by commensal microbiota. To answer this question they used normal mice or antibiotic treated mice with tumors, which they treated with different types of chemotherapeutic agents. Treatment of mice with antibiotics led to higher tumor volume after cisplatin treatment. In addition the induction of TNFa production by macrophages and DCs which leads to tumor necrosis was abolished when mice where treated with antibiotics. The bacterial strain that was associated with decreased TNFa production was Lactobacillus. Oxaliplatins induce NOX1, SOD1 and SOD2 that lead to ROS production and DNA damage responsible for cancer cell death. However treatment of mice with antibiotics led to prevention of ROS production by myeloid cells showing that myeloid cells are primed by microbiota. The major conclusions from the lecture were that the different commensal symbiotic microorganisms could have different effects on antitumor immunity and on the ability of the immune system to regulate pro- carcinogenic versus anti- carcinogenic responses.
I chose to summarize this lecture because even though the fact that microbiome can shape the immune responses is known, the association of microbiome with the responses during chemotherapy was an area new for me. This lecture also showed that alternative strategies for the treatment of cancer exploiting the microbiome and its interaction with the host could be possible in the future.

Wim Hof by Eliane Piket
Background: Wim Hof is convinced he can, by meditation, cold exposure and breathing exercises, affect his autonomic nervous system, and thereby his immune system. Both of these systems are however believed not to be able to voluntarily be influenced.
Study: In a study by dr. Matthijs Kox and colleagues, Wim Hof and healthy volunteers showed that after a training program influencing the autonomic nervous system they could reduce their immune system activation compared to volunteers that were not trained.  Volunteers were injected low dose LPS which usually results in symptoms such as nausea, headache, muscle ache, shivers and fever as well as increase of TNFa, IL-6, IL-8. Trained individuals experienced less of these symptoms and showed attenuated levels of pro-inflammatory cytokines TNFa, IL-6 and IL-8. Levels of anti-inflammatory cytokine IL-10, epinephrine and leukocyte count were higher compared to controls and suggest that voluntary activation of the sympathetic nervous system can suppress the immune system.
Why I liked it: It was refreshing to hear how this study was started, by actually following-up on a not so scientific hypothesis. Still they could show we can break scientific dogmas (systems we are not believed to affect voluntarily).

Jane Oliar0 by Joanna Kritikos
Loss of DNAM-1 ligand expression by acute myeloid leukemia cells renders
them resistant to NK cell killing (Jane Oliaro)
Dr. Oliaro presented results published in the Journal of Immunology on the receptor DNAM-
1 and how the loss of its ligands on tumor cells leads to the inability of T cells to form a
functional immune synapse with the target cells.
Introduction: DNAM-1 (DNAX Accessory Molecule 1) is an adhesion receptor on the surface
of CD8+ T cells and NK cells and facilitates the formation of the lytic immune synapse
between these cells and target cells. This synapse is very important in the killing of the
tumor cells as it has been shown that effector cells that are unable to form a synapse cannot
eliminate tumor cells. DNAM-1 associates with LFA-1 and its ligands are CD155 and CD112.
Results: During this presentation it was shown that loss of the ligand CD155 on the surface
of acute myeloid leukemia (AML) cells lead to the resistance of these cells towards NK cell
mediated killing. This was elegantly shown by time lapse confocal microscopy where
CD155+/+ or CD155-/- AML cells were put together with NK cells and killing was measured by
the appearance of a red dye in the target c ell. While CD155+/+ AML cells were readily
recognized and killed by NK cells, CD155-/- AML cells were mostly left alone. NK cells would
inspect them but then let them be and did not proceed to the formation of a synapse and
granule secretion as they did with the CD155+/+ AML cells.
Conclusions: The DNAM-1/CD155 interaction seems to be very important in the formation of
a synapse and target cell elimination. Both the loss of the ligand on the target cell and the
loss of the receptor on the effector cell (shown in another publication by the same group)
could eliminate synapse formation and target cell killing. Therefore, targeting this interaction
could perhaps be useful in finding new therapeutic approaches towards cancer.

Matthias Uhlén by Karl Carlström
Towards a knowledge-based Human protein atlas
Background: Despite we have known the human genome sequence for 10-15, our breakthroughs in terms of curing people based on this knowledge is limited. Back then, the hope was put into genome editing and artificial regulation of disease causing genes. However this turned out to be more complexed. The Human Protein Atlas project has faced the fact that’s it’s easier to target protein than genes for therapy, and they have thus created an enormous catalog for mRNA and protein expression in different human tissues and cell lines.
Summary: This project has generated an open access catalog containing mRNA and protein expression in several human tissues and cell lines. This has been done with various techniques such as histology and RNAseq. For some genes you can also assay their subcellular location.
Since they do whole body assessment of mRNA and protein expression they will also generate data on how these correlate to each other, this I found particular interesting because we often mRNA levels as an estimate for protein expression, without also checking the protein levels. He also raised the interesting fact that very few genes are organ specific.
Why did you liked the presentation?
I liked this presentation because the presenter in a very nice way described a problem which they are trying to overcome. I’m using their catalog a lot and it was nice to hear their vision and how they will develop it further.

Donna Davies by Kristina Johansson
Epithelium and Barrier
The airway epithelium serves important roles in protecting the host from pathogens and foreign particles found in the environment, and thereby prevents respiratory infections and tissue injury. Effective barrier function relies on physical barrier properties such as the ability of epithelial cells to make up cell-cell adhesion complexes as well as mucus production which contains a wide range of host defense molecules. Together, these functions make up the first line of defense which keeps the innate immune system from reacting to the constant stream of environmental stimuli. To date, a large body of evidence supports the view that dysregulation of innate immune functions contribute to the pathogenesis and exacerbation of respiratory diseases such as asthma. Thus, it is possible that restoration of barrier function may have therapeutic implications in respiratory diseases. 
Davies and coworkers utilize air liquid interface (ALI) cultures to study human epithelial functions. Epithelial cells are acquired from bronchial brushings from moderate to severe asthmatics and healthy controls that have undergone a bronchoscopy. The ALI technique allows for a complete rebuilding of the human epithelium including differentiation and maturation of ciliated cells and mucus producing goblet cells. Through the ALI cell culture system Davies has developed a method that allows the group to measure permeability of the epithelium to allergen as well as ways to monitor innate cell signaling. By investigating epithelial cells donated from healthy vs asthmatics Davies has found that asthmatic individuals demonstrate weakened epithelial barrier functions including increased allergen permeability as well as defect interferon signaling as compared to healthy epithelia. This may explain why common cold virus causes asthma exacerbations.  
I enjoyed the talk by Donna Davies a lot, mostly because she did not take for granted that everyone in the audience was in the asthma/allergy field. Instead she had a nice, long, introduction (made up like a lecture) where she explained the roles of the epithelium in broader terms. When she moved on to present experimental data she took her time and went through the experimental details (depicted in easy to understand illustrations/schemes) that were necessary to fully understand the data presented.

Emmanuel Wiertz by Liza Lind
Professor Emmanuel Wiertz studies viral strategies to elude the immune system of the host, with specific focus on large DNA viruses (like Herpes viruses). At his talk at WIRM he dedicated most of his time to the Herpes virus family, and what advances that has been made in the field of viral evasion for the ~20 past years.
Since I am a big fan of the Herpes viruses (and especially the Simplex sub family) I found this talk really interesting, and I don’t think I was the only one. Wiertz showed some of the concepts of viral evasion by using cartoon pictures that both caught the eye of the audience, but also showed quite complicated cellular pathways that otherwise can be hard to grasp. He seemed very keen that people actually understood what his research is all about (while some presenters are mostly showing off the cool techniques that they are using).
Wiertz showed how Herpes virus downregulate MHC class I, which makes infected cells unrecognizable by the cytotoxic cells that “see” viral peptides with the help of MHC I. This is achieved by inhibition of a protein called Transporter associated with antigen processing (TAP). This protein plays a big part in moving viral peptides from the cytosol into the endoplasmic reticulum, where they are loaded onto MHC I. The Herpes Simplex protein ICP47 inhibits TAP, and interestingly this takes part only in humans and not in mice.
Wiertz also talked about the inhibition of CD1d recycling by Herpes Simplex virus, a study originally by Yuan et al. (2006). CD1d presents lipids to NK T cells, making them produce both Th1 and Th2 cytokines. Yuan showed that Herpes Simplex virus type 1 (HSV-1) downregulates CD1d on antigen-presenting cells, by inhibiting recycling of CD1d after endocytosis. HSV-1 might also inhibit the transport of newly synthesized CD1d to the cell surface. This is of course not an unlikely scenario, since Herpes viruses really love to tamper with the normal functions of host proteins.
To summarize Wiertz showed how Herpes viruses stop both cytotoxic CD8+ T cells and NK T cells from recognizing virus infected cells.

Pleun Hombrink by Michael Hagemann-Jensen
 Human CD8+ lung resident memory T-cells.
In their study they went on to characterize different subsets of tissue/effector resident memory
CD8 T-cells in the lungs characterized by CD69+ and CD103+. Comparison was made to peripheral
blood as well. These different subsets and not at least the lung specific ones showed different
transcriptomic profiles, showing impact on the lung environment. Interestingly the CD8 CD103+
Tissue resident memory (TRM) cells lacked expression of T-bet and Eomes (usually needed for
cytotoxic function, as far as my knowledge extends, might be wrong), but instead expressed
Notch. They investigated the importance of notch signaling for the TRM cells with knock-out mice
and identified that Notch signaling is important for maintaining the pool of CD103+ TRM cells in
lungs and function.
He also mentioned Thy.1 (CD90) signaling as potentially being very interesting to further explore.
At least I have written in my notes Thy-1 signaling with a big circle around it, so it must have
seemed important at the time. I will do a search.
I liked this study primarily because I found it relevant to my own studies, both in regards to
similarities I have observed, but also as a source of explanation and further investigation. Plus, I
marked it with a star in my notes. Aside from the potential therapeutic implications of targeting
Notch signaling to sculpt function and amount of tissue resident memory cells, it would also be
interesting to look for similarities and further elucidate it in the so far less studied CD4 tissue
resident memory T-cells. They did indicate that it might, since they showed that inhibition of
Notch affected all CD69+ T-cells.

John J. O’Shea by Miranda Houtman
 Genomic switches and lymphoid specification
I am glad that I got the opportunity to attend the world immune regulation meeting in Davos. As my PhD projects are focusing on the genetics of autoimmune diseases (mainly rheumatoid arthritis), the scope of this meeting was different than that of my daily research. However, this meeting expanded my general knowledge in immune cells. Not surprisingly, I think that the talk by John J. O’Shea was interesting as it was most closely related to my field of research. He is one of the many persons that wants to gain insight into immune cell identity and specialized functions. They believe that super-enhancers (SEs), large clusters of transcriptional enhancers, drive expression of genes that define cell identity. He showed that in human CD4+ T cells from rheumatoid arthritis patients the highly associated SNPs fell within SEs. Thus, GWAS hits relevant to certain cell types are enriched for SEs. He also showed that cytokines and cytokine receptors were the main class of genes exhibiting SE architecture in these CD4+ T cells. They found that the locus encoding bach2, associated with many autoimmune diseases, is the most important SE in T cells. This locus is of importance, because BACH2 is a key negative regulator of effector differentiation. They deleted bach2 and investigated the expression of SE associated genes in T cells. They found that BACH2 negatively controlled the expression of 350 genes and concluded that BACH2 is the main transcription factor in CD4+ T cells. 
Another thing that his group is interested in is to understand the relationship between innate lymphoid cells (ILCs) and CD4+ T cells with regard to chromatin accessibility. To understand this relationship, they measured genome-wide chromatin accessibility. He showed that the chromatin state in ILCs was highly accessible and transcription could occur rapidly. And after activation, the chromatin state in these ILCs changed only a little. However, the chromatin state in CD4+ T cells is closed. Many factors are needed for transcription, which makes it a slow process. And after activation, chromatin remodeling occurred in naïve CD4+ T cells. He showed that this leads to the usage of similar regulatory elements that are used in ILCs. He concluded that although the cells are different before activation, they share regulatory elements after activation.
I think that his work really shows that there is much more than just genes. I think he clearly showed that SEs can be used to discover key players in newly identified cell types. This is of high importance because these key players can most likely be used as novel drug targets. And I think he also clearly showed that regulomes more precisely identify immune cell subsets than transcriptomes.

Nina Babel by Quan Tang 
Immune correlates of BK virus control post kidney transplantation-analysis of BKV specific conventional and regulatory T cells kinetics on a clonal level

Background: BK virus (BKV) is a member of the polyomavirus family. The BK virus rarely causes disease, but they stayed latently in the kidneys and urinary tract of most people for the whole life. They remain latent until the body undergoes some form of immunosuppression, such as the condition of kidney transplantation. The BK infection could lead to nephropathy and graft rejection. Some patients can control BKV but some patients can’t. The mechanism need further investigation.
Method: A next generation sequencing (NGS) methodology and a bioinformatics platform were used to analyze BKV specific cells from PBMC from 12 patients post kidney transplantation to see the BKV specific T cell receptor TCR repertoire.
Results: There are 2 waves of clonal proliferation and decline before BKV starts declining and before its clearance, in which CD4 conventional T cells pronounced. They also find BKV is associated with a higher fraction of BKV-specific regulatory T cells.
Conclusions: Frequency of BKV-spec. Treg and Teff/Treg ratio is associated with the duration of BKV reactivation and BKV clearance.
TCR-NGS allows for differential diagnosis BKV-nephropathy/acute rejection and individualized therapy in transplant patients.
Why I like it? The presentation use several questions as clues to lead us to understand the presentation, which makes it very easy to get and very logical.
And they also apply the molecular techniques to diagnose the clinical patients. I like the combination of lab work and clinical work.

 David Tarlinton by Rita Ivanchenko
 IL21 in the B cell response to antigen
This lecture immediately caught my attention as it started with the description of a cell cycle assay called fluorescent ubiquitination-based cell cycle indicator (FUCCI), developed by Miyawaki et al. in 2008.
This system utlyses two transgenic fused fluorescent proteins: red Cdt1 and green Geminin, both involved in the control of cell cycle. Cdt1 is accumulated in G1, and Geminin – in S/G2/M phases. Therefore, FUCCI enables elegant cell tracking through the cell cycle by flow cytometry and fluorescent microscopy.
David and his group used FUCCI mice to investigate how IL-21 influenced the germinal center (GC) cell composition in the context of cell cycle distribution. They immunized the mice with NP, and estimated the cell distribution in the dark zone (DZ) and light zone (LZ) of the GCs at different time points. They observed that IL-21R knock out mice had increased counts of centrocytes and centroblasts in G0/G1 and reduced counts of centrocytes in G2/S, although the total cell counts were not altered. T helpers had a low proliferation rate, independently of IL-21. The results were followed by a very nice cartoon and a comprehensive explanation of the processes taking place in the zones of the GC. David and colleagues conclude that proliferation mainly maps to the DZ, but is initiated in the LZ, and these outputs maintain the GC homeostasis. Some cells complete the cell cycle in LZ, an observation that needs to be further investigated. Finally, IL-21 signaling is critical for the DZ and LZ representation, and cell cycle dispersal seems to be the main reason.
David’s lecture was easy to comprehend, as if it was already a part of a textbook; I truly enjoyed it.

Sebastian Kreiter by Raya Saleh

 Eliciting Potent T-cells against Individual Mutant Neoantigens – The
Mutanome as Rich Target Source for Individualized Cancer Vaccination

If identified, Mutanome (Unique genomic alterations and epigenetic changes that
make specific molecular profile of every given tumor) are an ideal target for cancer
immunotherapy as healthy tissues lack expression of them and can potentially be
recognized as neo-antigens by the mature T-cell repertoire.
• Sebastian Kreiter et al., have shown in three independent murine tumor models
that a considerable fraction of non-synonymous cancer mutations are
immunogenic. Unexpectedly, the majority of the immunogenic mutanome is
recognized by CD4+ T cells and is MHC class-II restricted. Vaccination with such
CD4+ immunogenic mutations confers strong antitumor activity.
• Encouraged by these findings, they established a process by which mutations
identified by exome sequencing could be selected as vaccine targets solely
through bioinformatic prioritization on the basis of their expression levels and
major histocompatibility complex (MHC) class II-binding capacity for rapid
production as synthetic poly- epitope messenger RNA vaccines that is tailored to
activate and expand the individual patient’s neoantigen-specific T cells.
• They showed that vaccination with such polytope mRNA vaccines induces potent
tumor control and complete rejection of established aggressively growing tumors
in mice.
• Moreover, they demonstrated that CD4+ T cell neo-epitope vaccination reshapes
the tumor microenvironment and induces cytotoxic T lymphocyte responses
against an independent immunodominant antigen in mice, indicating orchestration
of antigen spread.
• Finally, they demonstrated an abundance of mutations predicted to bind to MHC
class II in human cancers as well by employing the same predictive algorithm on
corresponding human cancer types.
Why did I like it?
It was a clear and nice presentation with pedagogical figures of an interesting new
translational topic. It is really exciting that the personalized immunotherapy approach
introduced here may be regarded as a universally applicable blueprint for substantial
neo-epitope target repertoire of cancers, enabling the effective targeting of every
patient’s tumor with vaccines produced.

Wim Hof and Matthijs Kox by Daniëlle Vaartjes
The Iceman - a medical mystery unraveled
The talk that I liked most was the special lecture by Wim Hof and Matthijs Kox, especially because it was brought in a different way than all the other talks. Even though everyone in the scientific world was skeptical about “the iceman” Wim Hof claiming that he could control his autonomic nervous system, Radboud UMC Nijmegen in The Netherlands eventually took the chance to study him. They (Matthijs Kox and scientists) first looked at the effect of Wim Hof’s meditation technique on his autonomic nervous system and the innate immune response under extreme cold conditions and using the human endotoxemia model (i.v. injection of LPS, a model commonly used at Radboud UMC). The iceman showed to have a drastic change in pro- and anti-inflammatory cytokine response and high levels of cortisol by meditation during ice immersion. In the endotoxemia experiment, the plasma cortisol concentrations were higher and the cytokine response and clinical symptoms were lower compared with previously studied participants. However, since these are results from only one individual and Wim Hof claimed that he could teach anyone his techniques; they repeated the experiments with healthy volunteers. One group of healthy volunteers got trained the iceman’s meditation technique, breathing techniques and they got exposed to extreme cold in Poland before undergoing experimental endotoxemia whereas the other group did not. The trained volunteers showed increased levels of IL-10 and epinephrine, whereas the levels of pro-inflammatory cytokines TNF-a, IL-6 and IL-8 were decreased. They also showed less flu-like symptoms after LPS administration as compared to the control group. Matthijs Kox and colleagues claimed that based on these results one could indeed voluntarily activate the sympathetic nervous system, resulting in epinephrine release and suppression of the innate immune response. If they get the funding, they will try this in patients with Rheumatoid Arthritis.
As brought up during the questions after the lecture, I still think there are quite some loopholes in the experiments and claims made, however I quite liked the way the lecture was given. Very light and very clear. And scientists stay scientists so of course we all had to try the breathing technique (cyclic hyperventilation followed by breath retention), which was surprisingly refreshing.
One of the things that I found really fascinating was the endotoxemia model. Whenever I have to inject LPS into mice, I feel really bad because I know it gives a very strong immune response. When I realized that people would volunteer to get LPS injected I was shocked.
When I first heard about “the iceman” a few years ago I was also very skeptical, so when I found out that he was the special guest at WIRM, I had to see it. I still think he is a remarkable person, but he has achieved quite a lot and that I admire.

Vincenzo Bronte by Angnieszka Sowinska

Immune suppressive mechanisms in cancer microenvironment
Among diverse myeloid cell populations Bronte’s group identified and characterized myeloid-derived suppressor cells (MDSCs). Those immunoregulatory cells negatively influence antitumor immunity, for example by exerting an inhibitory activity on anti-tumor T cell responses. MDSCs act on the metabolism of L-arginine to suppress the proliferation and effector functions of antigen-stimulated T lymphocytes. Bronte showed that arginase1 (ARG1) and nitric oxide sinthase 2 (NOS2), which are enzymes involved in L-arginine metabolism, cause modifications directly on T cell signaling pathway, as well as indirectly in the tumor microenvironment, resulting in major changes to molecules involved in T cell recruitment and function. However, Bronte’s results also show that the negative regulation of tumor-specific T cells by L-arginine metabolism does not prevent those cells from signaling to a subset of monocytes to aid tumor rejection. As that signaling pathway depends on NOS2 induction, the role of NO in cancer seems to be plastic. Depending on various factors, NO can either kill or sustain proliferation of tumor cells.
The talk was extremely well delivered and easy to follow. I liked that Bronte made very clear points that tumor microenvironment converts myeloid cells into potent immunosuppressive cells and the role of NO in cancer is paradoxical.

Hermelijn Smits by Jorge Ramírez
“B cells capture helminth antigens, develop regulatory function and drive Treg cell development”
When one is immersed in trying to understand the pathogenesis of autoimmune diseases, one tends to overlook the somewhat obscure world of parasites. This isn’t perhaps due to lack of interest but rather because of the known clear-cut and nasty consequences these organisms can have in a host. Hermelijn Smits et al have showed us a more gracious angle of helminthes: they can participate in immune regulation and promote immune tolerance.
The lecture offered us an interesting insight into the generation of Bregs upon infection with Schistosoma haematobium. The talk took us on a journey from the endemic S. haematobium endemic region in Gabon where they collected blood from infected and uninfected individuals all the way back to the lab in the Netherlands where the samples were assessed for Breg markers and subsequent in vitro co-stimulation with T cells. The conclusions from these experiments revealed that the parasites are able to promote generation of IL-10 producing Bregs which, in turn, can enhance the conversion of CD4+ T cells to Tregs. The group even went further into proposing the clinical applicability of these generated Bregs and Tregs to treatment of other diseases where these cell subtypes are affected in numbers or function.
The talk was structured in a sequential manner and was easy to follow, even for someone with little contact with Parasitology. The novelty of the study lies in the translation from an observation in a particular endemic group to potential therapeutic applications of Bregs. This is a good example of how studies in infectious diseases can bridge the gap and contribute to the understanding of the immune response and its regulation.