Das Melanom gehört zu den am stärksten immunogenen Tumoren. Dennoch ist es in der Lage, sich eine... more Das Melanom gehört zu den am stärksten immunogenen Tumoren. Dennoch ist es in der Lage, sich einer antitumoralen Immunantwort zu entziehen, indem es Toleranzmechanismen, einschließlich negativer Immuncheckpoint-Moleküle, nutzt. Die am umfassendsten untersuchten Immuncheckpoints sind CTLA-4 (cytotoxic T lymphocyte-associated protein-4) und PD-1 (programmed cell death protein 1). Immuncheckpoint-Inhibitoren (ICI), die in den vergangenen 10 Jahren häufig zur Behandlung von Melanomen eingesetzt wurden, können antitumorale Immunreaktionen auslösen und eine Rückbildung des Melanoms bewirken. Patienten, die auf die ICI-Behandlung ansprachen, erreichten eine langanhaltende Remission oder einen Zustand der Krankheitskontrolle. Eine große Gruppe von Patienten sprach dagegen nicht auf diese Therapie an, was darauf hindeutet, dass es zu einer Entwicklung von Resistenzmechanismen kommt, darunter intrinsische Eigenschaften des Tumors, Funktionsstörungen der Effektorzellen und die Entstehung eines immunsuppressiven Tumormikromilieus (tumor microenvironment, TME). In der vorliegenden Übersichtsarbeit werden die Erfolge der ICI-Therapie bei Melanom, die Gründe für ein Therapieversagen und vielversprechende Ansätze zur Überwindung der Resistenz erörtert. Letztere umfassen die Kombination verschiedener ICI, Strategien zur Neutralisierung des immunsuppressiven Tumormikromilieus und die Kombination von ICI mit anderen antitumoralen Therapien wie Bestrahlung, onkolytische Viren oder zielgerichtete Therapien. Darüber hinaus werden neue therapeutische Ansätze, die gegen andere Immuncheckpoint-Moleküle gerichtet sind, ebenfalls besprochen.
There is evidence that cancer-derived extracellular vesicles (EVs) have nearby and distant effect... more There is evidence that cancer-derived extracellular vesicles (EVs) have nearby and distant effects in the body. In order to reach distant sites, EVs need to travel through the blood stream and organs where they encounter a hostile environment in the form or phagocytic cells. However, the stability and homeostasis in the blood circulation and in the tumor microenvironment are not well understood. Phagocytosis is an important mechanism for the clearance of apoptotic and necrotic cells. As exosomes (small EV) express “eat-me” signals such as phosphatidyl-serine, it is likely that they are cleared similar to dead cells. Here we discuss measures that cancer cells have developed to protect their EVs from rapid depletion. The expression of “don’t eat me” signals such as CD47 and CD24 on the tumor cell surface and in released exosomes is of vital importance. We will focus on the role of the CD24-Siglec-10 binding axis as a stop signal at the interface between tumor cells and phagocytic cells. Extending the lifetime of EVs is essential for the cancer to achieve systemic immune suppression and to prepare metastatic niches for spreading. Keywords: CD24, CD47, Extracellular vesicles, Siglecs, carbohydrates, phagocytosis
Myeloid‐derived suppressor cells (MDSC) represent a highly immunosuppressive population that expa... more Myeloid‐derived suppressor cells (MDSC) represent a highly immunosuppressive population that expands in tumor bearing hosts and inhibits both T and NK cell antitumor effector functions. Among MDSC subpopulations, the polymorphonuclear (PMN) one is gaining increasing interest since it is a predominant MDSC subset in most cancer entities and inherits unique properties to facilitate metastatic spread. In addition, further improvement in distinguishing PMN‐MDSC from neutrophils has contributed to the design of novel therapeutic approaches. In this review, we summarize the current view on the origin of PMN‐MDSC and their relation to classical neutrophils. Furthermore, we outline the metastasis promoting features of these cells and promising strategies of their targeting to improve the efficacy of cancer immunotherapy.
Fig.S1:CCR5 ligands are enriched in mouse melanoma lesions and induce the migration of CD11b Gr1 ... more Fig.S1:CCR5 ligands are enriched in mouse melanoma lesions and induce the migration of CD11b Gr1 cells. Fig.S2:Immunosuppressivephenotype of CCR5 MDSC in tumor bearing mice. Fig.S3:Induction of CCR5 expression and immunosuppressive molecules by inflammatory factors. Fig.S4:Immunosuppressivepattern of CCR5 MDSC from melanoma patients. Fig.S5:Increased production of immunosuppressive molecules by CCR5 MDSC in melanoma patients.
Tumor cell–derived extracellular vesicles (EV) convert normal myeloid cells into myeloid-derived ... more Tumor cell–derived extracellular vesicles (EV) convert normal myeloid cells into myeloid-derived suppressor cells (MDSC), inhibiting antitumor immune responses. Here, we show that EV from Ret mouse melanoma cells upregulate the expression of programmed cell death ligand 1 (PD-L1) on mouse immature myeloid cells (IMC), leading to suppression of T-cell activation. PD-L1 expression and the immunosuppressive potential of EV-generated MDSC were dependent on the expression of Toll-like receptors (TLR). IMC from Tlr4−/− mice failed to increase T-cell PD-L1 expression and immunosuppression with Ret-EV treatment, and this effect was dependent on heat-shock protein 86 (HSP86) as HSP86-deficient Ret cells could not stimulate PD-L1 expression on normal IMC; IMC from Tlr2−/− and Tlr7−/− mice demonstrated similar results, although to a lesser extent. HSP86-deficient Ret cells slowed tumor progression in vivo associated with decreased frequency of tumor-infiltrating PD-L1+CD11b+Gr1+ MDSC. EV from human melanoma cells upregulated PD-L1 and immunosuppression of normal monocytes dependent on HSP86. These findings highlight a novel EV-mediated mechanism of MDSC generation from normal myeloid cells, suggesting the importance of EV targeting for tumor therapy.Significance:These findings validate the importance of TLR4 signaling in reprogramming normal myeloid cells into functional myeloid-derived suppressor cells.
Malignant melanoma is the deadliest of skin cancers. Melanoma frequently metastasizes to the brai... more Malignant melanoma is the deadliest of skin cancers. Melanoma frequently metastasizes to the brain, resulting in dismal survival. Nevertheless, mechanisms that govern early metastatic growth and the interactions of disseminated metastatic cells with the brain microenvironment are largely unknown. To study the hallmarks of brain metastatic niche formation, we established a transplantable model of spontaneous melanoma brain metastasis in immunocompetent mice and developed molecular tools for quantitative detection of brain micrometastases. Here we demonstrate that micrometastases are associated with instigation of astrogliosis, neuroinflammation, and hyperpermeability of the blood–brain barrier. Furthermore, we show a functional role for astrocytes in facilitating initial growth of melanoma cells. Our findings suggest that astrogliosis, physiologically instigated as a brain tissue damage response, is hijacked by tumor cells to support metastatic growth. Studying spontaneous melanoma b...
Myeloid-derived suppressor cells (MDSC) are known to inhibit functions of T and NK cells. MDSC ha... more Myeloid-derived suppressor cells (MDSC) are known to inhibit functions of T and NK cells. MDSC have been shown to be generated and to accumulate under chronic inflammatory conditions that are typical for cancer. Therefore, it would be highly beneficial to find ways to diminish the number and immunosuppressive functions of these cells in tumor-bearing hosts. Here we describe current protocols to deplete MDSC or induce their maturation in preclinical tumor models that could lead to the attenuation of their immunosuppressive functions.
Hepatocellular carcinoma (HCC) can have viral or non-viral causes1–5. Non-alcoholic steatohepatit... more Hepatocellular carcinoma (HCC) can have viral or non-viral causes1–5. Non-alcoholic steatohepatitis (NASH) is an important driver of HCC. Immunotherapy has been approved for treating HCC, but biomarker-based stratification of patients for optimal response to therapy is an unmet need6,7. Here we report the progressive accumulation of exhausted, unconventionally activated CD8+PD1+T cells in NASH-affected livers. In preclinical models of NASH-induced HCC, therapeutic immunotherapy targeted at programmed death-1 (PD1) expanded activated CD8+PD1+T cells within tumours but did not lead to tumour regression, which indicates that tumour immune surveillance was impaired. When given prophylactically, anti-PD1 treatment led to an increase in the incidence of NASH–HCC and in the number and size of tumour nodules, which correlated with increased hepatic CD8+PD1+CXCR6+, TOX+, and TNF+T cells. The increase in HCC triggered by anti-PD1 treatment was prevented by depletion of CD8+T cells or TNF neut...
BackgroundMyeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that inclu... more BackgroundMyeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells.MethodsWe developed, tested, executed and o...
Das Melanom gehört zu den am stärksten immunogenen Tumoren. Dennoch ist es in der Lage, sich eine... more Das Melanom gehört zu den am stärksten immunogenen Tumoren. Dennoch ist es in der Lage, sich einer antitumoralen Immunantwort zu entziehen, indem es Toleranzmechanismen, einschließlich negativer Immuncheckpoint-Moleküle, nutzt. Die am umfassendsten untersuchten Immuncheckpoints sind CTLA-4 (cytotoxic T lymphocyte-associated protein-4) und PD-1 (programmed cell death protein 1). Immuncheckpoint-Inhibitoren (ICI), die in den vergangenen 10 Jahren häufig zur Behandlung von Melanomen eingesetzt wurden, können antitumorale Immunreaktionen auslösen und eine Rückbildung des Melanoms bewirken. Patienten, die auf die ICI-Behandlung ansprachen, erreichten eine langanhaltende Remission oder einen Zustand der Krankheitskontrolle. Eine große Gruppe von Patienten sprach dagegen nicht auf diese Therapie an, was darauf hindeutet, dass es zu einer Entwicklung von Resistenzmechanismen kommt, darunter intrinsische Eigenschaften des Tumors, Funktionsstörungen der Effektorzellen und die Entstehung eines immunsuppressiven Tumormikromilieus (tumor microenvironment, TME). In der vorliegenden Übersichtsarbeit werden die Erfolge der ICI-Therapie bei Melanom, die Gründe für ein Therapieversagen und vielversprechende Ansätze zur Überwindung der Resistenz erörtert. Letztere umfassen die Kombination verschiedener ICI, Strategien zur Neutralisierung des immunsuppressiven Tumormikromilieus und die Kombination von ICI mit anderen antitumoralen Therapien wie Bestrahlung, onkolytische Viren oder zielgerichtete Therapien. Darüber hinaus werden neue therapeutische Ansätze, die gegen andere Immuncheckpoint-Moleküle gerichtet sind, ebenfalls besprochen.
There is evidence that cancer-derived extracellular vesicles (EVs) have nearby and distant effect... more There is evidence that cancer-derived extracellular vesicles (EVs) have nearby and distant effects in the body. In order to reach distant sites, EVs need to travel through the blood stream and organs where they encounter a hostile environment in the form or phagocytic cells. However, the stability and homeostasis in the blood circulation and in the tumor microenvironment are not well understood. Phagocytosis is an important mechanism for the clearance of apoptotic and necrotic cells. As exosomes (small EV) express “eat-me” signals such as phosphatidyl-serine, it is likely that they are cleared similar to dead cells. Here we discuss measures that cancer cells have developed to protect their EVs from rapid depletion. The expression of “don’t eat me” signals such as CD47 and CD24 on the tumor cell surface and in released exosomes is of vital importance. We will focus on the role of the CD24-Siglec-10 binding axis as a stop signal at the interface between tumor cells and phagocytic cells. Extending the lifetime of EVs is essential for the cancer to achieve systemic immune suppression and to prepare metastatic niches for spreading. Keywords: CD24, CD47, Extracellular vesicles, Siglecs, carbohydrates, phagocytosis
Myeloid‐derived suppressor cells (MDSC) represent a highly immunosuppressive population that expa... more Myeloid‐derived suppressor cells (MDSC) represent a highly immunosuppressive population that expands in tumor bearing hosts and inhibits both T and NK cell antitumor effector functions. Among MDSC subpopulations, the polymorphonuclear (PMN) one is gaining increasing interest since it is a predominant MDSC subset in most cancer entities and inherits unique properties to facilitate metastatic spread. In addition, further improvement in distinguishing PMN‐MDSC from neutrophils has contributed to the design of novel therapeutic approaches. In this review, we summarize the current view on the origin of PMN‐MDSC and their relation to classical neutrophils. Furthermore, we outline the metastasis promoting features of these cells and promising strategies of their targeting to improve the efficacy of cancer immunotherapy.
Fig.S1:CCR5 ligands are enriched in mouse melanoma lesions and induce the migration of CD11b Gr1 ... more Fig.S1:CCR5 ligands are enriched in mouse melanoma lesions and induce the migration of CD11b Gr1 cells. Fig.S2:Immunosuppressivephenotype of CCR5 MDSC in tumor bearing mice. Fig.S3:Induction of CCR5 expression and immunosuppressive molecules by inflammatory factors. Fig.S4:Immunosuppressivepattern of CCR5 MDSC from melanoma patients. Fig.S5:Increased production of immunosuppressive molecules by CCR5 MDSC in melanoma patients.
Tumor cell–derived extracellular vesicles (EV) convert normal myeloid cells into myeloid-derived ... more Tumor cell–derived extracellular vesicles (EV) convert normal myeloid cells into myeloid-derived suppressor cells (MDSC), inhibiting antitumor immune responses. Here, we show that EV from Ret mouse melanoma cells upregulate the expression of programmed cell death ligand 1 (PD-L1) on mouse immature myeloid cells (IMC), leading to suppression of T-cell activation. PD-L1 expression and the immunosuppressive potential of EV-generated MDSC were dependent on the expression of Toll-like receptors (TLR). IMC from Tlr4−/− mice failed to increase T-cell PD-L1 expression and immunosuppression with Ret-EV treatment, and this effect was dependent on heat-shock protein 86 (HSP86) as HSP86-deficient Ret cells could not stimulate PD-L1 expression on normal IMC; IMC from Tlr2−/− and Tlr7−/− mice demonstrated similar results, although to a lesser extent. HSP86-deficient Ret cells slowed tumor progression in vivo associated with decreased frequency of tumor-infiltrating PD-L1+CD11b+Gr1+ MDSC. EV from human melanoma cells upregulated PD-L1 and immunosuppression of normal monocytes dependent on HSP86. These findings highlight a novel EV-mediated mechanism of MDSC generation from normal myeloid cells, suggesting the importance of EV targeting for tumor therapy.Significance:These findings validate the importance of TLR4 signaling in reprogramming normal myeloid cells into functional myeloid-derived suppressor cells.
Malignant melanoma is the deadliest of skin cancers. Melanoma frequently metastasizes to the brai... more Malignant melanoma is the deadliest of skin cancers. Melanoma frequently metastasizes to the brain, resulting in dismal survival. Nevertheless, mechanisms that govern early metastatic growth and the interactions of disseminated metastatic cells with the brain microenvironment are largely unknown. To study the hallmarks of brain metastatic niche formation, we established a transplantable model of spontaneous melanoma brain metastasis in immunocompetent mice and developed molecular tools for quantitative detection of brain micrometastases. Here we demonstrate that micrometastases are associated with instigation of astrogliosis, neuroinflammation, and hyperpermeability of the blood–brain barrier. Furthermore, we show a functional role for astrocytes in facilitating initial growth of melanoma cells. Our findings suggest that astrogliosis, physiologically instigated as a brain tissue damage response, is hijacked by tumor cells to support metastatic growth. Studying spontaneous melanoma b...
Myeloid-derived suppressor cells (MDSC) are known to inhibit functions of T and NK cells. MDSC ha... more Myeloid-derived suppressor cells (MDSC) are known to inhibit functions of T and NK cells. MDSC have been shown to be generated and to accumulate under chronic inflammatory conditions that are typical for cancer. Therefore, it would be highly beneficial to find ways to diminish the number and immunosuppressive functions of these cells in tumor-bearing hosts. Here we describe current protocols to deplete MDSC or induce their maturation in preclinical tumor models that could lead to the attenuation of their immunosuppressive functions.
Hepatocellular carcinoma (HCC) can have viral or non-viral causes1–5. Non-alcoholic steatohepatit... more Hepatocellular carcinoma (HCC) can have viral or non-viral causes1–5. Non-alcoholic steatohepatitis (NASH) is an important driver of HCC. Immunotherapy has been approved for treating HCC, but biomarker-based stratification of patients for optimal response to therapy is an unmet need6,7. Here we report the progressive accumulation of exhausted, unconventionally activated CD8+PD1+T cells in NASH-affected livers. In preclinical models of NASH-induced HCC, therapeutic immunotherapy targeted at programmed death-1 (PD1) expanded activated CD8+PD1+T cells within tumours but did not lead to tumour regression, which indicates that tumour immune surveillance was impaired. When given prophylactically, anti-PD1 treatment led to an increase in the incidence of NASH–HCC and in the number and size of tumour nodules, which correlated with increased hepatic CD8+PD1+CXCR6+, TOX+, and TNF+T cells. The increase in HCC triggered by anti-PD1 treatment was prevented by depletion of CD8+T cells or TNF neut...
BackgroundMyeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that inclu... more BackgroundMyeloid-derived suppressor cells (MDSC) are a functional myeloid cell subset that includes myeloid cells with immune suppressive properties. The presence of MDSC has been reported in the peripheral blood of patients with several malignant and non-malignant diseases. So far, direct comparison of MDSC across different diseases and Centers is hindered by technical pitfalls and a lack of standardized methodology. To overcome this issue, we formed a network through the COST Action Mye-EUNITER (www.mye-euniter.eu) with the goal to standardize and facilitate the comparative analysis of human circulating MDSC in cancer, inflammation and infection. In this manuscript, we present the results of the multicenter study Mye-EUNITER MDSC Monitoring Initiative, that involved 13 laboratories and compared circulating MDSC subsets across multiple diseases, using a common protocol for the isolation, identification and characterization of these cells.MethodsWe developed, tested, executed and o...
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Papers by Viktor Umansky