Data is available on human Hemato-Lymphoid System Rag2gc-/- mice infected with both CXCR4 as well as CCR5 tropic HIV-1 strains. HIV causes a disseminated infection and spreads in all newly generated lymphoid tissues, thus closely resembling HIV infection in humans. However, as in EBV infected animals, adaptive T and B cell responses were not consistently detected. Thus, although these “humanized” mice represent a major step forward in generating an in vivo preclinical testing system, they still harbor limitations as inconsistent/weak adaptive immune respons...

We further our understanding of different DC populations and their soluble products in adults but in particular in neonatal mice. We have concentrated on the evaluation of the interplay between the hematopoetic factor Flt3L and IFNalpha,beta and have data available from our studies. We found that the cooperation between IFNalpha,beta and Flt3L (FL) plays an important role in the defense against Herpes simplex virus type 1 (HSV-1) in neonates. Treatment of neonatal mice with recombinant IFNalpha has a short-term, FL-independent and a long-term, FL-dependent protect...

Our lab obtained data on maturation of DC by TLR agonists.

Studies have continued and data obtained on the effects of biolistic (Gene Gun) delivery of vectors engineered to express distinct chemokines at the local skin site of mice. In particular, attention has been focussed on the recruitment of distinct subsets of DC to skin. This work, which is being performed in collaboration with PowderMed, a former SME now owned by Pfizer, may lead to the development of more targeted strategies to induce distinct T cell responses using this technology. A publication has resulted from this work.

Data were obtained on the effect of enhanced CD83 expression on dendritic cells and T cells and its correlation with effective immune responses. Human CD83 is a marker molecule for mature dendritic cells (DC) and is also expressed on activated B and T cells. Although CD83 has been implicated in immune responses, its function on DC and T cells remains unclear. In this study, we wanted to assess the role of CD83 expressed on DC and T cells in the immune response. Down-regulation of CD83 expression on human DC through RNA interference (RNAi) results in a less potent...

Data was obtained of the capacity of splenic DC, pulsed in vitro with protein antigens or peptides, to induce immunity after transfer into syngeneic animals. To improve existing strategies, the amplitude and polarisation of T cell responses was monitored in the presence or absence of regulatory T cells. Natural regulatory T cells (CD4+ CD25+) were depleted by injection of anti-CD25 mAbs, whereas regulatory T cells were induced by injection of (presumably agonistic) anti-CTLA-4 mAbs. Our observations demonstrate that natural and CTLA-4 induced regulatory T cells a...

We obtained data from an in vitro system to study ex-vivo responses able to detect bona fide in vivo primed CD4+ T cells. We focused on the monitoring of tumour antigen specific CD4+ T cell responses. We select the following tumour associated antigens: i) the E6 and E7 proteins of human papilloma viruses, ii) the carcinoembryonic antigen (CEA) and iii) the tumour specific antigen MAGE-A3. We investigated spontaneous CD4+ T cell responses to these antigens in normal donors and in patients with high-grade cervical lesions, pancreas adenocarcinoma and advanced ...

Data has been generated by multiplex analysis on the response of human MoDC to yeast, spheroplasts, pseudohyphae and spores. Human blood contains myeloid (mDCs) and plasmacytoid (pDCs) dendritic cells that differ in cytokine secretion pattern and responsiveness to microbial stimuli. We found that LPS-stimulated mDCs are able to induce up-regulation of co-stimulatory molecules on co-cultured pDCs. Likewise, CpG-stimulated pDCs activate co-cultured mDCs. The cross talk between these two populations of DC is very efficient since it can be observed at mDC/pDC ratio ran...

Our lab has obtained data on maturation stimuli for GMP-grade DC.

Data has been obtained on the phenotype and function of myeloid derived suppressor cells in melanoma in patients. Accumulation of myeloid derived suppressor cells (MDSC) with the ability to suppress T cells has been observed in serveral types of cancer, including melanoma. Using blood from melanoma patients we are investigating phenotypic markers that can be used to further characterize MDSC, focusing on molecules that are related to their suppressive function. As it is believed that recruitment from the bone marrow by tumor derived factors leads to increased pre...

Currently there is no knowledge about the relevance of MDSC in ovarian cancer patients. However, it is known that both Tregs and suppressive macrophages are increased in this malignancy and have been suggested to correlate with worse prognosis. In order to obtain data, we are collecting blood and ascitic fluid of ovarian cancer patients to study the presence of immature myeloid populations as compared to healthy donor blood. We have identified two candidate populations that will be tested for the ability to suppress T cells. We also aim to characterize these cel...

Data has been generated in HHD2 transgenic mice on dendritic cell derived-exosomes (DEX), nanomeric vesicles harboring MHC/peptide complexes capable of promoting primary T cell responses and tumor rejection in the presence of adjuvants. We showed that, in the absence of adjuvants, DEX mediate potent antigen dependent-antitumor effects against preestablished tumors in mice pretreated with immunopotentiating dosing of cyclophosphamide (CTX). CTX could i) abolish the suppressive function of CD4+CD25+Foxp3+ regulatory T cells (Treg), ii) markedly enhance the mag...

Preclinical data is available on the power of preventing disease and invoking immune response of our lead product for the prevention of infectious disease, ImmunoVexHSV2, a vaccine for genital herpes. ImmunoVex HSV2 is a novel live-attenuated vaccine candidate that expresses approximately 80 HSV-2 proteins intended to stimulate a broad and powerful immune response. In preclinical studies, ImmunoVex HSV2 completely prevents disease and invokes a powerful immune response. We intend to initiate a Phase I clinical trial for this product early in 2008.

We have obtained valuable data on chemically well-defined TLR ligand conjugates and their effectiveness to induce a strong immune response via the cross-presentation pathway. We have studied long peptides which were covalently conjugated to either the TLR2 ligand or TLR9 ligand, Pam3CysSK4 or CpG, respectively have been used to study the uptake, antigen presentation, and induction of specific T-cells. A pronounced enhancement in antigen presentation by DC in vitro was facilitated by the conjugated peptides compared to peptide alone, or peptide mixed with the fre...

Data have been obtained on Mart-1 specific T cell priming and/or NK cell triggering in HHD2 mice. We have used DC exosomes along with various TLR ligands or cytokines such as IL-2 or alpha IFN to promote Mart-1 specific T cell priming and/or NK cell triggering in HHD2 mice. We demonstrated that only TLR3 and 9 ligation is able to induce CTL priming in vivo. However, exosomes in the absence of adjuvants can induce NK cell activation. DC exosome-mediated NK cell triggering depends upon NKG2D ligands presented on the exosome surface

Data has been obtained on DCs loaded with Ag-IgG immune complexes (ICs) as a means of prophylactic immunization in mice. Therapeutic vaccinations strongly delay tumor growth or even prevent tumors from growing out. By depleting CD4+ and CD8+ cell populations prior to tumor challenge, CD8+ cells were identified as the main effector cells involved. Importantly, DCs pre-loaded in vitro with ICs are at least 1000-fold more potent than ICs injected directly into mice or DCs loaded with the same amount of non-complexed protein. FcgammaRs on DCs were required for effici...

Our lab has generated data on receptors on dendritic cells necessary for capture of exosomes. In 2007, we have finalized analysis of the receptors on DCs responsible for capture of exosomes secreted by mature DCs. We have shown that expression of LFA-1, but not of Mac-1, integrin, on DCs is required for capture of ICAM-1-bearing exosomes. Furthermore, the CD8+ subpopulation of DCs in lymph nodes expresses LFA-1 at higher levels than the CD8- subpopulation, and is responsible for in vivo capture of injected exosomes. We have thus proposed a new role for LFA-1 on DCs...

Data has been obtained on MVA BN (a powerful poxvirus vaccine system) from a thorough analysis on the nucleotide level on safety in cell cultures in immune deficient mice as well as in healthy, HIV–infected and other immune deficient humans. We have furthered our interaction with Dr.Markus Manz, (Partner group 27) IBR, Bellinzona, Switzerland to strengthen vaccine developments with an improved humanized mouse model. We focus on recombinant vaccines against HIV driven by a powerful poxvirus vaccine system termed MVA BN. To improve our understanding MVA BN has b...

Our lab has obtained data on the mechanism of how IL-10 regulates the immune response to MTb infection in mice. Control and clearance of intracellular pathogens such as MTb is dependent on the production of TNF and the induction of the T-helper 1 (Th1) cytokine IFN-gamma by IL-12. Conversely, IL-10 is a suppressive cytokine essential for dampening the immune response to a number of intracellular pathogens to limit host immune pathology. IL-10 has been shown to exert its suppressive effect by directly acting on the antigen presenting cell (APC), therefore functi...

Our laboratory has obtained data on the role of DC-derived cytokines in NK cell production of IFN-gamma.