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Retour sur le "XLII CONGRESS OF THE BRAZILIAN SOCIETY OF IMMUNOLOGY - Mucosal Immuno 2017" October 2 to 6, 2017, Salvador - BA - Brazil par CLARISSA RODRIGUES NASCIMENTO, sponsorisée par le CFCD

The ‘Brazilian Society of Immunology (SBI)’ was founded in 1973, with the aim of better integrating scientists working in different arms of immunology. The SBI annual congress has been going since then, and this year, despite big problems Brazil is facing, of note lack of incentives for science, the members of the society put efforts for organizing the thematic meeting ‘Mucosal Immuno’. The scientific program was wide and extensive from microbiota to neuro-immuno regulation, HIV vaccination, inflammasome, and infectious disease.
Here I describe some of the inspiring presentations of the meeting.

One talk which arrested much attention was given by Thomaz Brunner (University of Konstanz, Denmark). He presented evidence for an extra-adrenal glucocorticoid (GC) synthesis. Endogenous GCs are known to be produced by the adrenal glands and to serve important functions, among them the regulation of the immune system. The group has been demonstrating the production of considerable amounts of GC in the intestinal mucosa and in the skin, with implications for local homeostasis and regulation of immune responses. While the basal synthesis of intestinal GC is relatively low, the initiation of inflammation can strongly increase it. For instance, local GCs regulate the expression of tight junction proteins, thus having a role in the stabilization of the intestinal epithelial barrier. Regarding immune responses, the group observed that intestinal GCs exhibit an inhibitory effect on the activation of different populations of T cells, in the context of LCMV infection.

Again concerning the intestine, Daniel Mucida (Rockefeller University, NY, USA) is interested in understanding how different microenvironments in the tissue regulate resident macrophages. Mucida explained with enthusiasm that when using imaging approaches and transcriptional profiling tools his group observed that lamina propria macrophages (LpMs) preferentially express a pro-inflammatory phenotype when compared to muscularis macrophages (MMs), which displays a tissue-protective phenotype. Upon bacterial infection in the lumem, the phenotype of MMs is boosted via crosstalk with neurons innervating the region. Of interest is the fact that the MMs are present underneath the submucosal region, thus distant from the lumen evidencing a role for the neuro-immune communication between enteric neurons and macrophages in sensing disequilibrium originated in more distant location.

Another researcher from Rockefeller, Gabriel Victora, presented an elegant method for monitoring cell-cell interactions in vivo, based on a strategy for placing a label (site-specific), biotin in that case, during the contact between two cells, which the group aim to apply for studying the crosstalk between DC/T cell, and T cell/B cell within lymph nodes. Gabriel Victora combines intravital microscopy with other techniques for studying the antibody affinity maturation in B cells which, takes place in germinal centers. The migratory behavior of B cells during this process has being dissected as the technics of imaging evolve. It is not much to add that basic research on this topic is extremely relevant for the studies on vaccination, since it tells about the production of broadly neutralizing antibodies, which are rarely produced in infected individuals and intend to be recapitulated through vaccination.
Michel Nussenzweig (Rockfeller University, NY, USA) presented the progress of his group and others toward active or passive HIV-1 vaccination. Briefly, regarding passive vaccination he demonstrated that macaques are protected from HIV after having received a single injection of a specific combination of broad neutralizing antibodies.

The section ‘awards’ was, in my view, particularly interesting, because it recognizes the efforts of young scientists as well as long-term contribution of senior scientists.
The group of Dario Zamboni uncovered a mechanism through which some Leishmania species (L. guyanensis and one L. braziliensis), which carries the Leishmania RNA virus type 1 escapes from the microbicidal activity of macrophages. It is known that inflammasome is triggered in macrophages during infection with Leishmania, and that IL-1β production has an important role restricting parasite replication. Interestingly, parasites carrying the endosymbiont virus present increased infectivity. The mechanism behind, as demonstrated in Dario Zamboni’s work, relies on the activation of TLR3 followed by induction of autophagy and finally autophagy-dependent downregulation of inflammasome. In this scenario, cells produce less IL-1β. The student presenting the work was granted with one of the SBI awards.
Importantly, the SBI is committed to provide emphasis on the achievements of women in science, and in this sense, has created the ‘Women in Science award’ for being part of the annual meetings. The award was given to Antoniana Krettli for her studies concerning Chagas disease, the heart pathology caused by chronic Trypanosoma cruzi infection. Antoniana Krettli contributed enormously for the description of mechanisms accounting for the parasite survival and infectivity in susceptible hosts. It turns out that the parasite is resistant to lysis by the complement system. However, during chronic infection, the vertebrate hosts produce antibodies that render the infective form of the parasite sensitive to lysis. The respective targets of the lytic antibodies on the parasite surface were then explored. Later on, she realized that the binding of antibodies in the infective form of the parasite could serve as an assay for the control of cure in patients undergoing therapy.

Besides, I had the opportunity to present our results and discuss our ideas on MHCI antigen cross presentation. We presented evidence for the interaction between UNC93B1 and the calcium sensor STIM1, and the relevance of this interaction for the process of antigen cross presentation.

Finally, I would like to thank the CFCD for the travel support. I believe the attendance at the SBI meeting was a great opportunity for me to integrate the different aspects of the fascinating field of immunology, and to solidify the idea that the immune system is constantly in contact with other systems, while influencing and being influenced by the microbiota.