http://hdl.handle.net/10033/56896 Publications of the Twincore Experimentelle Infektionsforschung Sat, 18 May 2013 12:12:25 GMT 2013-05-18T12:12:25Z http://hdl.handle.net/10033/271705 Title: Tumor-specific CD4(+) T cells develop cytotoxic activity and eliminate virus-induced tumor cells in the absence of regulatory T cells. Authors: Akhmetzyanova, Ilseyar; Zelinskyy, Gennadiy; Schimmer, Simone; Brandau, Sven; Altenhoff, Petra; Sparwasser, Tim; Dittmer, Ulf Abstract: The important role of tumor-specific cytotoxic CD8(+) T cells is well defined in the immune control of the tumors, but the role of effector CD4(+) T cells is poorly understood. In the current research, we have used a murine retrovirus-induced tumor cell line of C57BL/6 mouse origin, namely FBL-3 cells, as a model to study basic mechanisms of immunological control and escape during tumor formation. This study shows that tumor-specific CD4(+) T cells are able to protect against virus-induced tumor cells. We show here that there is an expansion of tumor-specific CD4(+) T cells producing cytokines and cytotoxic molecule granzyme B (GzmB) in the early phase of tumor growth. Importantly, we demonstrate that in vivo depletion of regulatory T cells (Tregs) and CD8(+) T cells in FBL-3-bearing DEREG transgenic mice augments IL-2 and GzmB production by CD4(+) T cells and increases FV-specific CD4(+) T-cell effector and cytotoxic responses leading to the complete tumor regression. Therefore, the capacity to reject tumor acquired by tumor-reactive CD4(+) T cells largely depends on the direct suppressive activity of Tregs. We suggest that a cytotoxic CD4(+) T-cell immune response may be induced to enhance resistance against oncovirus-associated tumors. Fri, 01 Feb 2013 00:00:00 GMT http://hdl.handle.net/10033/271705 2013-02-01T00:00:00Z http://hdl.handle.net/10033/271194 Title: A novel bacterial artificial chromosome-transgenic podoplanin-cre mouse targets lymphoid organ stromal cells in vivo. Authors: Onder, Lucas; Scandella, Elke; Chai, Qian; Firner, Sonja; Mayer, Christian T; Sparwasser, Tim; Thiel, Volker; Rülicke, Thomas; Ludewig, Burkhard Abstract: Stromal cells provide the structural foundation of secondary lymphoid organs (SLOs), and regulate leukocyte access and cell migration within the different compartments of spleen and lymph nodes (LNs). Furthermore, several stromal cell subsets have been implied in shaping of T cell responses through direct presentation of antigen. Despite significant gain of knowledge on the biology of different SLO-resident stromal cell subsets, their molecular and functional characterization has remained incomplete. To address this need, we have generated a bacterial artificial chromosome-transgenic mouse model that utilizes the podoplanin (pdpn) promoter to express the Cre-recombinase exclusively in stromal cells of SLOs. The characterization of the Pdpn-Cre mouse revealed transgene expression in subsets of fibroblastic reticular cells and lymphatic endothelial cells in LNs. Furthermore, the transgene facilitated the identification of a novel splenic perivascular stromal cell subpopulation that forms web-like structures around central arterioles. Assessment of the in vivo antigen expression in the genetically tagged stromal cells in Pdpn-Cre mice revealed activation of both MHC I and II-restricted TCR transgenic T cells. Taken together, stromal pdpn-Cre expression is well-suited to characterize the phenotype and to dissect the function of lymphoid organ stromal cells. Sat, 01 Jan 2011 00:00:00 GMT http://hdl.handle.net/10033/271194 2011-01-01T00:00:00Z http://hdl.handle.net/10033/269936 Title: Neuropilin 1 deficiency on CD4+Foxp3+ regulatory T cells impairs mouse melanoma growth. Authors: Hansen, Wiebke; Hutzler, Marina; Abel, Simone; Alter, Christina; Stockmann, Christian; Kliche, Stefanie; Albert, Juliane; Sparwasser, Tim; Sakaguchi, Shimon; Westendorf, Astrid M; Schadendorf, Dirk; Buer, Jan; Helfrich, Iris Abstract: Infiltration of Foxp3(+) regulatory T (T reg) cells is considered to be a critical step during tumor development and progression. T reg cells supposedly suppress locally an effective anti-tumor immune response within tumor tissues, although the precise mechanism by which T reg cells infiltrate the tumor is still unclear. We provide evidence that Neuropilin 1 (Nrp-1), highly expressed by Foxp3(+) T reg cells, regulates the immunological anti-tumor control by guiding T reg cells into the tumor in response to tumor-derived vascular endothelial growth factor (VEGF). We demonstrate for the first time that T cell-specific ablation of Nrp-1 expression results in a significant breakdown in tumor immune escape in various transplantation models and in a spontaneous, endogenously driven melanoma model associated with strongly reduced tumor growth and prolonged tumor-free survival. Strikingly, numbers of tumor-infiltrating Foxp3(+) T reg cells were significantly reduced accompanied by enhanced activation of CD8(+) T cells within tumors of T cell-specific Nrp-1-deficient mice. This phenotype can be reversed by adoptive transfer of Nrp-1(+) T reg cells from wild-type mice. Thus, our data strongly suggest that Nrp-1 acts as a key mediator of Foxp3(+) T reg cell infiltration into the tumor site resulting in a dampened anti-tumor immune response and enhanced tumor progression. Mon, 22 Oct 2012 00:00:00 GMT http://hdl.handle.net/10033/269936 2012-10-22T00:00:00Z http://hdl.handle.net/10033/268892 Title: T cell receptor stimulation-induced epigenetic changes and Foxp3 expression are independent and complementary events required for Treg cell development. Authors: Ohkura, Naganari; Hamaguchi, Masahide; Morikawa, Hiromasa; Sugimura, Kyoko; Tanaka, Atsushi; Ito, Yoshinaga; Osaki, Motonao; Tanaka, Yoshiaki; Yamashita, Riu; Nakano, Naoko; Huehn, Jochen; Fehling, Hans Joerg; Sparwasser, Tim; Nakai, Kenta; Sakaguchi, Shimon Abstract: The transcription factor Foxp3 is essential for the development of regulatory T (Treg) cells, yet its expression is insufficient for establishing the Treg cell lineage. Here we showed that Treg cell development was achieved by the combination of two independent processes, i.e., the expression of Foxp3 and the establishment of Treg cell-specific CpG hypomethylation pattern. Both events were induced by T cell receptor stimulation. The Treg cell-type CpG hypomethylation began in the thymus and continued to proceed in the periphery and could be fully established without Foxp3. The hypomethylation was required for Foxp3(+) T cells to acquire Treg cell-type gene expression, lineage stability, and full suppressive activity. Thus, those T cells in which the two events have concurrently occurred are developmentally set into the Treg cell lineage. This model explains how Treg cell fate and plasticity is controlled and can be exploited to generate functionally stable Treg cells. Fri, 16 Nov 2012 00:00:00 GMT http://hdl.handle.net/10033/268892 2012-11-16T00:00:00Z