The chemokine CCL22 is abundantly expressed in many types of cancer and is instrumental for intra... more The chemokine CCL22 is abundantly expressed in many types of cancer and is instrumental for intratumoral recruitment of regulatory T cells (Treg), an important subset of immunosuppressive and tumor-promoting lymphocytes. In this study, we offer evidence for a generalized strategy to blunt Treg activity that can limit immune escape and promote tumor rejection. Activation of innate immunity with Toll-like receptor (TLR) or RIG-I-like receptor (RLR) ligands prevented accumulation of Treg in tumors by blocking their immigration. Mechanistic investigations indicated Treg blockade was a consequence of reduced intratumoral CCL22 levels caused by type I interferon. Notably, stable expression of CCL22 abrogated the antitumor effects of treatment with RLR or TLR ligands. Taken together, our findings argue that type I interferon blocks the Treg-attracting chemokine CCL22 and thus helps limit the recruitment of Treg to tumors, a finding with implications for cancer immunotherapy.
Regulatory T cells (Treg) are a T-cell subpopulation with suppressive capacities, specifically at... more Regulatory T cells (Treg) are a T-cell subpopulation with suppressive capacities, specifically attracted by CCL22. We aimed to investigate whether CCL22 is expressed in human placentas and whether its presence, together with Treg infiltration, is associated with miscarriage conditions. Paraffin samples were stained for CCL22 and for the Treg-specific transcription factor FoxP3. Expression levels were evaluated in a semi-quantitative manner. Double immunofluorescence was used for the identification of CCL22-producing cells. In all placentas, trophoblasts expressed CCL22. Interestingly, expression in the decidua was only observed in miscarriage conditions. Maternal stromal cells expressed CCL22. Correlation with a higher presence of Treg in the decidua of abortive tissues was observed. Our results demonstrate that CCL22 is expressed in human placenta. Decidual expression was only observed in miscarriage conditions and correlates with Treg infiltration. Thus, CCL22 plays a role in human pregnancy and may occur as a negative feedback response to pro-inflammatory events during miscarriage conditions.
Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic c... more Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic cancer. Recent evidence suggests that the coinhibitory PD-1-PD-L1 axis plays a major role in ACT failure. We hypothesized that a new fusion receptor reverting PD-1-mediated inhibition into CD28 costimulation may break peripheral tolerance. Different PD-1-CD28 fusion receptor constructs were created and retrovirally transduced into primary T cell receptor transgenic murine CD8(+) T cells specific for ovalbumin (OT-1). Cytokine release, proliferation, cytotoxicity, and tumor recognition were analyzed in vitro. Antitumor efficacy and mode of action were investigated in mice bearing subcutaneous tumors induced with the pancreatic carcinoma cell line Panc02 expressing the model antigen ovalbumin (Panc-OVA). For antitumoral efficacy, six to eight mice per group were used. All statistical tests are two-sided. Transduction of the PD-1-CD28 receptor constructs mediated enhanced cytokine release, T...
Toll-like receptor (TLR) ligands hold promise for cancer immunotherapy. The isolation of intratum... more Toll-like receptor (TLR) ligands hold promise for cancer immunotherapy. The isolation of intratumoral leukocytes of tumor-bearing mice is a useful technique for analyzing the immunological effects of TLR ligands on the tumor microenvironment. These isolated immune cells can be directly used for analysis (e.g., by flow cytometry) or cultured for functional in vitro studies. Here, we describe the isolation of intratumoral leukocytes by density gradient centrifugation. This technique can be used to isolate leukocytes from freshly dissected murine tumors.
Regulatory T cells (Treg) mediate tolerance towards self-antigens by suppression of innate and ad... more Regulatory T cells (Treg) mediate tolerance towards self-antigens by suppression of innate and adaptive immunity. In cancer patients, tumor-infiltrating FoxP31 Treg suppress local anti-tumor immune responses and are often associated with poor prognosis. Markers that are selectively expressed on tumor-infiltrating Treg may serve as targets for immunotherapy of cancer. Here we show that CD103, an integrin mediating lymphocyte retention in epithelial tissues, is expressed at high levels on tumor-infiltrating FoxP31 Treg in several types of murine cancer. In the CT26 model of colon cancer up to 90% of the intratumoral FoxP31 cells expressed CD103 compared to less than 20% in lymphoid organs. CD1031 Treg suppressed T effector cell activation more strongly than CD103 neg Treg. Expression of CD103 on Treg closely correlated with intratumoral levels of transforming growth factor b (TGF-b) and could be induced in a TGF-b-dependent manner by tumor cell lines. In vivo, gene silencing of TGF-b reduced the frequency of CD1031 Treg, demonstrating that CD103 expression on tumor-infiltrating Treg is driven by intratumoral TGF-b. Functional blockade of CD103 using a monoclonal antibody did however not reduce the number of intratumoral Treg, indicating that CD103 is not involved in homing or retention of FoxP31 cells in the tumor tissue.
Inhibitors of dipeptidylpeptidase IV (DPP-IV) represent a novel class of frequently used anti-dia... more Inhibitors of dipeptidylpeptidase IV (DPP-IV) represent a novel class of frequently used anti-diabetic drugs. In addition to its function in metabolic regulation, DPP-IV also plays a role in the immune system. Whether the DPP-IV inhibitors sitagliptin, vildagliptin or saxagliptin impair immune responses is, however, currently unknown. Here, we investigated the effect of these agents on both innate and adaptive immunity. We found that the DPP-IV inhibitors did not affect the innate immune response induced by Toll-like receptor (TLR) ligands, as cytokine secretion and induction of co-stimulatory molecules by human blood mononuclear cells was not impaired. Furthermore, proliferation of T cells and suppressive function of regulatory T cells was preserved. Mice treated with vildagliptin showed normal cytokine production, immune cell activation and lymphocyte trafficking upon TLR activation. Thus, crucial immunological parameters remain unaffected upon treatment with DPP-IV inhibitors, a fact that is reassuring with respect to safety of these drugs.
The chemokine CCL22 is abundantly expressed in many types of cancer and is instrumental for intra... more The chemokine CCL22 is abundantly expressed in many types of cancer and is instrumental for intratumoral recruitment of regulatory T cells (Treg), an important subset of immunosuppressive and tumor-promoting lymphocytes. In this study, we offer evidence for a generalized strategy to blunt Treg activity that can limit immune escape and promote tumor rejection. Activation of innate immunity with Toll-like receptor (TLR) or RIG-I-like receptor (RLR) ligands prevented accumulation of Treg in tumors by blocking their immigration. Mechanistic investigations indicated Treg blockade was a consequence of reduced intratumoral CCL22 levels caused by type I interferon. Notably, stable expression of CCL22 abrogated the antitumor effects of treatment with RLR or TLR ligands. Taken together, our findings argue that type I interferon blocks the Treg-attracting chemokine CCL22 and thus helps limit the recruitment of Treg to tumors, a finding with implications for cancer immunotherapy.
Regulatory T cells (Treg) are a T-cell subpopulation with suppressive capacities, specifically at... more Regulatory T cells (Treg) are a T-cell subpopulation with suppressive capacities, specifically attracted by CCL22. We aimed to investigate whether CCL22 is expressed in human placentas and whether its presence, together with Treg infiltration, is associated with miscarriage conditions. Paraffin samples were stained for CCL22 and for the Treg-specific transcription factor FoxP3. Expression levels were evaluated in a semi-quantitative manner. Double immunofluorescence was used for the identification of CCL22-producing cells. In all placentas, trophoblasts expressed CCL22. Interestingly, expression in the decidua was only observed in miscarriage conditions. Maternal stromal cells expressed CCL22. Correlation with a higher presence of Treg in the decidua of abortive tissues was observed. Our results demonstrate that CCL22 is expressed in human placenta. Decidual expression was only observed in miscarriage conditions and correlates with Treg infiltration. Thus, CCL22 plays a role in human pregnancy and may occur as a negative feedback response to pro-inflammatory events during miscarriage conditions.
Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic c... more Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic cancer. Recent evidence suggests that the coinhibitory PD-1-PD-L1 axis plays a major role in ACT failure. We hypothesized that a new fusion receptor reverting PD-1-mediated inhibition into CD28 costimulation may break peripheral tolerance. Different PD-1-CD28 fusion receptor constructs were created and retrovirally transduced into primary T cell receptor transgenic murine CD8(+) T cells specific for ovalbumin (OT-1). Cytokine release, proliferation, cytotoxicity, and tumor recognition were analyzed in vitro. Antitumor efficacy and mode of action were investigated in mice bearing subcutaneous tumors induced with the pancreatic carcinoma cell line Panc02 expressing the model antigen ovalbumin (Panc-OVA). For antitumoral efficacy, six to eight mice per group were used. All statistical tests are two-sided. Transduction of the PD-1-CD28 receptor constructs mediated enhanced cytokine release, T...
Toll-like receptor (TLR) ligands hold promise for cancer immunotherapy. The isolation of intratum... more Toll-like receptor (TLR) ligands hold promise for cancer immunotherapy. The isolation of intratumoral leukocytes of tumor-bearing mice is a useful technique for analyzing the immunological effects of TLR ligands on the tumor microenvironment. These isolated immune cells can be directly used for analysis (e.g., by flow cytometry) or cultured for functional in vitro studies. Here, we describe the isolation of intratumoral leukocytes by density gradient centrifugation. This technique can be used to isolate leukocytes from freshly dissected murine tumors.
Regulatory T cells (Treg) mediate tolerance towards self-antigens by suppression of innate and ad... more Regulatory T cells (Treg) mediate tolerance towards self-antigens by suppression of innate and adaptive immunity. In cancer patients, tumor-infiltrating FoxP31 Treg suppress local anti-tumor immune responses and are often associated with poor prognosis. Markers that are selectively expressed on tumor-infiltrating Treg may serve as targets for immunotherapy of cancer. Here we show that CD103, an integrin mediating lymphocyte retention in epithelial tissues, is expressed at high levels on tumor-infiltrating FoxP31 Treg in several types of murine cancer. In the CT26 model of colon cancer up to 90% of the intratumoral FoxP31 cells expressed CD103 compared to less than 20% in lymphoid organs. CD1031 Treg suppressed T effector cell activation more strongly than CD103 neg Treg. Expression of CD103 on Treg closely correlated with intratumoral levels of transforming growth factor b (TGF-b) and could be induced in a TGF-b-dependent manner by tumor cell lines. In vivo, gene silencing of TGF-b reduced the frequency of CD1031 Treg, demonstrating that CD103 expression on tumor-infiltrating Treg is driven by intratumoral TGF-b. Functional blockade of CD103 using a monoclonal antibody did however not reduce the number of intratumoral Treg, indicating that CD103 is not involved in homing or retention of FoxP31 cells in the tumor tissue.
Inhibitors of dipeptidylpeptidase IV (DPP-IV) represent a novel class of frequently used anti-dia... more Inhibitors of dipeptidylpeptidase IV (DPP-IV) represent a novel class of frequently used anti-diabetic drugs. In addition to its function in metabolic regulation, DPP-IV also plays a role in the immune system. Whether the DPP-IV inhibitors sitagliptin, vildagliptin or saxagliptin impair immune responses is, however, currently unknown. Here, we investigated the effect of these agents on both innate and adaptive immunity. We found that the DPP-IV inhibitors did not affect the innate immune response induced by Toll-like receptor (TLR) ligands, as cytokine secretion and induction of co-stimulatory molecules by human blood mononuclear cells was not impaired. Furthermore, proliferation of T cells and suppressive function of regulatory T cells was preserved. Mice treated with vildagliptin showed normal cytokine production, immune cell activation and lymphocyte trafficking upon TLR activation. Thus, crucial immunological parameters remain unaffected upon treatment with DPP-IV inhibitors, a fact that is reassuring with respect to safety of these drugs.
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Papers by Moritz Rapp