Our lab has obtained data on the role of IL-10 and IDO in relation to Th1 and inflammatory responses in a colitis model tested on mice. IDO appears critical for the regulation of TNBS colitis upon CTLA-4 engagement, as the beneficial effect of anti-CTLA-4 treatment was lost in IDO-deficient mice. By contrast, the absence of IDO did not alter the course of inflammation in mice injected with TNBS only, an unexpected finding which suggests that IDO-dependent counter-regulation requires other factors/cells in addition to IDO production and T cell activation by TNBS. Ou...

Our lab has obtained data on the role of p50 NF-kB in differentiation, survival and APC function in mice. Tumor growth is supported by tumor stroma, which is made by matrix and infiltrating cells, such as tumor associated macrophages (TAM) and tumor associated dendritic cells (TADC). We have recently reported that TAM display massive nuclear localization of the p50 NF-kB inhibitory homodimer, which correlates with impaired inflammatory functions (Saccani et al., 2006).The functional significance of this observation was demonstrated in p50 NF-kB deficient mice, whi...

We are continuing our studies of the roles of DC in scrapie uptake and dissemination and have obtained data on intestinal DC subsets all of which can acquire scrapie ME7 form the intestinal lumen and transport it via lymph. In current studies we are examining the effects of indomethacin-induced small intestinal inflammation on both intestinal DC biology and on scrapie uptake, transport and delivery. We are characterising (in collaboration with Sebastian Amigorena) rat lymph exosomes and will determine if they transport intestinally-delivered scrapie ME7. We are ...

We obtained data on the influence of bLf, whose immunomodulant properties are now recognized, on MDDC differentiation/activation. We found that bLF interferes with the activation of MD-DC induced by different TLR agonists, but not by T cell mediated signals. Although bLF did not significantly influence monocyte differentiation in DCs, we found that it markedly reduced the up-modulation of CD83, co-stimulatory and MHC molecules (i.e. CD80, CD86, MHC class I and II), and cytokine secretion (IL-12, TNF-? and IL-23) induced by LPS or polyI-C. Consistently with an impa...

Data have been obtained defining the differential roles of intestinal lymph DC subsets in activation of naïve and memory T cells in rats. We have shown that two of the three DC subsets are highly potent activators of naïve CD4+ T cells, and do not appear to be constitutively suppressed in any way. We are currently examining the phenotype of the activated cells and determining if Tregs are induced. We have initiated (in collaboration with Pfizer) a study of nano-particles as potential deliverers of intestinal vaccines.

We have data available on some functional immune responses in a small animal model to study the development and function of the human hematopoietic and immune system as well as human specific infections in vivo. We established “human hemato-lymphoid-system mice” by transplanting human CD34+ cord blood cells into irradiated newborn Rag2-/-gc-/- mice, leading to de novo development of human B, T, and dendritic cells; formation of structured primary and secondary lymphoid organs; and production of some limited functional immune responses.

We obtained data from an evaluation whether antigens could be rerouted from the endosomal into the cytosolic compartment by combining antigen with cell penetrating peptides to further enhance cross-presentation. We made significant progress using biodegradable polymers to enhance cross-presentation of loaded antigens, and the best results were obtained by maturing DCs with a combination of the TLR ligands R848 and polyI:C. Furthermore, we have shown that DC electroporated with melanoma antigen RNA express the proteins ex vivo and in vivo.

Our laboratory obtained data from studies of DC phagosomes and cross-presentation using K/O and mutant mouse strains. Cross presentation is the process by which Dendritic cells (DC) phagocytose pathogens or dying cell fragments, and present proteolytic peptides derived from these antigens in association with MHC class I molecules. The reasons why DCs are the only antigen presenting cells that efficiently cross present antigens are not well understood. We have demonstrated that the NADPH oxidase NOX2 is recruited to DC early phagosomes mediating a sustained produc...

We obtained data on immune tolerance in mice breast-fed by antigen-exposed lactating mothers. We have previously generated a monoclonal antibody, 2C44, that reacted to a peptide derived from the Leishmania LACK protein bound to I-Ad MHC class II molecules. We have successfully used the 2C44 mAb to visualize LACK-presenting DCs in mice infected with the L. major. In 2007, we have attempted to identify the APCs that are responsible for the development of immune tolerance in mice that have been breast-fed by antigen-exposed lactating mothers. Recent experiments perf...

We have obtained data on the immuno-physiology of rat and mouse intestinal dendritic cells. We have used a known adjuvant, E. coli heat-labile toxin (Etx) and a potential adjuvant R-848, a small TLR7/8 ligand. We have shown that R-848 causes massive changes in DC migration and leads to their activation in lymph nodes but not lymph. These changes are due to TNF-alpha (migration) and Type 1 interferons (activation), but are not accompanied by obvious oral adjuvant effects. In contrast Etx causes only minor changes in migration and activation but is a potent oral adju...

Our lab gathered data on the responses to EBV and HIV in hu-SCID mice.

Data were obtained on responses to viral infections in TLR9 -/- mice, C57Bl/6 mice and IFNalpha receptor -/- mice. Toll receptor 9 (TLR9) is an important pattern recognition receptor. It is stimulated by foreign DNA or CpG motivs. We found that TLR9 -/- mice were very susceptible to infection with the mouse pox virus Ectromelia. In contrast to DC from C57Bl/6 mice, DC from TLR9 -/- produced little if any interferon alpha. However, MVA-BN induced IFNalpha in presence or absence of TLR9 -/-. Moreover, coinfection with MVA-BN and Ectromilia protected TLR9 -/- mice ...

We obtained data from a study of the correlation between CD8 multiple cell surface markers and functional profiles studied at single cell level. For that purpose, we subdivided peripheral CD8 T cells into eleven different cell subtypes based on the association of multiple cell surface markers. In each subtype, we isolated single-cells. In each single cell, we quantified the expression of multiple genes. Moreover, we isolated and studied cells from different normal donors. These results were published in Blood. We showed that - this strategy allowed the identifi...

We obtained data on the effect of pro-inflammatory stroma-derived cytokines on DC in vivo. Our investigation has shown that, in the absence of additional stimuli, such inflammatory signals are ineffectual in promoting DC activation and cannot substitute for engagement of innate receptors directly on DC.

We have obtained data from our work on biodegradable poly (D, L-lactide-co-glycolide) (PLGS) micropsheres (MS) coencapsulating ligands for endosomally expressed TLRs plus exogeneous Antigen (Ag) to deliver its cargo to endosomes of murine Dendritic cells (DCs), thus initiating TLR mediated DC maturation as well as processing of MHC class I and class II restricted epitopes. In these studies we used as Ag either Ovalbumin, or rec. Prion-protein. In the latter system, a CD4 T cell response could be initiated. We also found that the DNA sugar backbone determines TLR9...

We explored for the first time transfection of CD4(+) and CD8(+) T cells with mRNA encoding recombinant immunoreceptors for use in the adoptive immunotherapy of cancer and obtained data from this study. CD4(+) and CD8(+) T cells were efficiently transfected with immunoreceptors specific for ErbB2 and CEA. The immunoreceptor expression was transient with half-maximal expression at day 2 and no detectable immunoreceptor expression at day 9 after electroporation. Immunoreceptor-transfected T cells were specifically activated upon coincubation with ErbB2(+) and CEA(+...

We have used agonists of the dectin-1/Syk pathway as adjuvants in vivo to induce CD8+ T cell responses and have data available on this. In summary, we have shown that this can result in CTL capable of destroying tumours.

Data have been obtained on the use of nano-particles for intestinal vaccine delivery from our continued investigation of the use of nano-particles as oral vaccine vehicles (Cerovic). We have identified an important role for complement C1q in the uptake of scrapie agent by dendritic cells (Flores-Langarica).We have shown that a protein from Schistosomes has dramatic effects on intestinal physiology, including dendritic cells (Nassar). We have shown that steady-state intestinal denritic cells are not constitutively biased towards stimluating Th2 responses (Milling). ...

Data characterizing the antigen-presenting DC in immunized mice is available. Our goal was to generate a probe that could allow the visualization of specific activated DCs following either the immunization of mice with an antigen in adjuvant or an infection with leishmania major parasites. We thus tried to prepare a mAb reacting to the immunodominant LACK156-173 peptide of leishmania bound to I-Ad MHC class II molecules. To this aim, we injected I-Ad/LACK recombinant dimers to TCR transgenic mice which exhibited an increased frequency of LACK-specific T cells. ...