Interferon-α Up-Regulates the Expression of PD-L1 Molecules on Immune Cells Through STAT3 and p38 Signaling

Interferon-α (IFNα) has one of the longest histories of use amongst cytokines in clinical oncology and has been applied for the treatment of many types of cancers. Due to its immune-activating properties, IFNα is also an attractive candidate for combinatory anti-cancer therapies. Despite its extensive use in animal tumor models as well as in several clinical trials, the different mechanisms underlying patient responses and affecting desirable clinical benefits are still under investigation. Here we show that in addition to its immune-activating properties, IFNα induces the expression of a key negative regulator, immunosuppressive PD-L1 molecule, in the majority of the specific immune cell populations, particularly in the dendritic cells (DC). DC can modulate immune responses by a variety of mechanisms, including expression of T-cell regulatory molecules and cytokines. Our results showed that treatment of DC with IFNα-2b led to pronounced up-regulation of surface expression of PD-L1 molecules, increased IL-6 and decreased IL-12 production. Moreover, we present evidence that IFNα-treated DC exhibited a reduced capacity to stimulate interferon-γ production in T cells compared to control DC. This T-cell response after treatment of DC with IFNα was recovered by a pre-treatment with an anti-PD-L1 blocking antibody. Further analyses revealed that IFNα regulated PD-L1 expression through the STAT3 and p38 signaling pathways, since blocking of STAT3 and p38 activation with specific inhibitors prevented PD-L1 up-regulation. Our findings underline the important roles of p38 and STAT3 in the regulation of PD-L1 expression and prove that IFNα induces STAT3/p38-mediated expression of PD-L1 and thereby a reduced stimulatory ability of DC. The augmentation of PD-L1 expression in immune cells through IFNα treatment should be considered by use of IFNα in an anti-cancer therapy

Interferon-alpha Up-Regulates the Expression of PD-L1 Molecules on Immune Cells Through STAT3 and p38 Signaling

Interferon-alpha (IFN alpha) has one of the longest histories of use amongst cytokines in clinical oncology and has been applied for the treatment of many types of cancers. Due to its immune-activating properties, IFN alpha is also an attractive candidate for combinatory anti-cancer therapies. Despite its extensive use in animal tumor models as well as in several clinical trials, the different mechanisms underlying patient responses and affecting desirable clinical benefits are still under investigation. Here we show that in addition to its immune-activating properties, IFN alpha induces the expression of a key negative regulator, immunosuppressive PD-L1 molecule, in the majority of the specific immune cell populations, particularly in the dendritic cells (DC). DC can modulate immune responses by a variety of mechanisms, including expression of T-cell regulatory molecules and cytokines. Our results showed that treatment of DC with IFN alpha-2b led to pronounced up-regulation of surface expression of PD-L1 molecules, increased IL-6 and decreased IL-12 production. Moreover, we present evidence that IFN alpha-treated DC exhibited a reduced capacity to stimulate interferon-gamma production in T cells compared to control DC. This T-cell response after treatment of DC with IFN alpha was recovered by a pre-treatment with an anti-PD-L1 blocking antibody. Further analyses revealed that IFN a regulated PD-L1 expression through the STAT3 and p38 signaling pathways, since blocking of STAT3 and p38 activation with specific inhibitors prevented PD-L1 up-regulation. Our findings underline the important roles of p38 and STAT3 in the regulation of PD-L1 expression and prove that IFN alpha induces STAT3/p38-mediated expression of PD-L1 and thereby a reduced stimulatory ability of DC. The augmentation of PD-L1 expression in immune cells through IFN alpha treatment should be considered by use of IFN alpha in an anti-cancer therapy

Influence of Interferon-Alpha Combined with Chemo (Radio) Therapy on Immunological Parameters in Pancreatic Adenocarcinoma

Prognosis of patients with carcinoma of the exocrine pancreas is particularly poor. A combination of chemotherapy with immunotherapy could be an option for treatment of pancreatic cancer. The aim of this study was to perform an immunomonitoring of 17 patients with pancreatic cancer from the CapRI-2 study, and tumor-bearing mice treated with combination of chemo (radio) therapies with interferon-2. Low doses of interferon-2 led to a decrease in total leukocyte and an increase in monocyte counts. Furthermore, we observed a positive effect of interferon-2 therapy on the dendritic cells and NK (natural killer) cell activation immediately after the first injection. In addition, we recorded an increased amount of interferon- and IL-10 in the serum following the interferon-2 therapy. These data clearly demonstrate that pancreatic carcinoma patients also show an immunomodulatory response to interferon-2 therapy. Analysis of immunosuppressive cells in the Panc02 orthotopic mouse model of pancreatic cancer revealed an accumulation of the myeloid-derived suppressor cells in spleens and tumors of the mice treated with interferon-2 and 5-fluorouracil. The direct effect of the drugs on myeloid-derived suppressor cells was also registered in vitro. These data expose the importance of immunosuppressive mechanisms induced by combined chemo-immunotherapy

Influence of Interferon-Alpha Combined with Chemo (Radio) Therapy on Immunological Parameters in Pancreatic Adenocarcinoma

Prognosis of patients with carcinoma of the exocrine pancreas is particularly poor. A combination of chemotherapy with immunotherapy could be an option for treatment of pancreatic cancer. The aim of this study was to perform an immunomonitoring of 17 patients with pancreatic cancer from the CapRI-2 study, and tumor-bearing mice treated with combination of chemo (radio) therapies with interferon-2. Low doses of interferon-2 led to a decrease in total leukocyte and an increase in monocyte counts. Furthermore, we observed a positive effect of interferon-2 therapy on the dendritic cells and NK (natural killer) cell activation immediately after the first injection. In addition, we recorded an increased amount of interferon- and IL-10 in the serum following the interferon-2 therapy. These data clearly demonstrate that pancreatic carcinoma patients also show an immunomodulatory response to interferon-2 therapy. Analysis of immunosuppressive cells in the Panc02 orthotopic mouse model of pancreatic cancer revealed an accumulation of the myeloid-derived suppressor cells in spleens and tumors of the mice treated with interferon-2 and 5-fluorouracil. The direct effect of the drugs on myeloid-derived suppressor cells was also registered in vitro. These data expose the importance of immunosuppressive mechanisms induced by combined chemo-immunotherapy

Immune Checkpoint Molecules and Cancer Immunotherapy

For the faultless function of the immune system, tight regulation of immune cell activation, immuno-suppression and the strength and efficiency of the immune response is essential. Immune checkpoint (ICP) molecules can amplify or dampen signals that lead to the modulation of specific immune activities. Under physiological conditions, immune checkpoints are essential to prevent autoimmune manifestations and to preserve self-tolerance. They help modulate immune responses by either promoting or inhibiting T-cell activation. However, in the context of cancer, malignant cells can dysregulate the expression of immune checkpoint proteins on immune cells in order to suppress anti-tumor immune responses and to gain immune resistance. Moreover, tumor cells themselves can also express some checkpoints proteins, thereby enabling these cells to externally orchestrate immune regulatory mechanisms. Several recent studies have confirmed that the expression of immune checkpoints could be an important prognostic parameter for cancer development and for patient outcome. Therefore, cancer immunotherapy based on the modulation of immune checkpoint molecules alone, or in combination with conventional tumor therapy (chemo- or/and radiotherapy), is now in focus as a means of developing new therapeutic strategies for different types of cancer. The two well-known molecules – CTLA4 and PD-1 - serve as important examples of such checkpoint proteins of important therapeutic potential. Thus far, inhibitors of CTLA4 and PD-1 have been approved to treat only a limited number of malignancies (e.g. malignant Melanoma, Non-Small Cell Lung Cancer). Many others are currently under investigation and the list of immune checkpoint molecules for potential therapeutic targeting is still growing. However, the clinical response to inhibitors of checkpoint molecules is not sufficient in all cases. Therefore, further studies are needed to improve our knowledge of such immunomodulatory proteins and their associated signaling pathways. Several key signaling pathways which are involved in the regulation of expression of checkpoint molecules in immune cells and in cancer cells have already been identified including MAPK, PI3K, NF-kB, JAKs and STATs. These (and future discovered) signaling pathways could give rise to the development of new strategies for modulating the expression of ICPs and thereby, improving anti-cancer immune responses. The main aim of the Research Topic is to collect novel findings from scientists involved in basic research on immune checkpoints as well as in translational studies investigating the use of checkpoint inhibtors in immunotherapy in experimental settings. We welcome the submission of Review, Mini-Review and Original Research articles that cover the following topics: 1. Molecular mechanisms underlying regulation of ICP expression in immune and/or cancer cells. 2. Characterization of signaling pathways downstream ICP molecules. 3. Cellular responses to ICP blockade. 4. Identification of new compounds interfering with ICP expression and/or signaling. 5. ICP-mediated interactions between cancer cells and immune cells. 6. Functional links between ICP and cytokines/chemokines. 7. Molecular mechanisms of ICP inhibition in the context of experimental cancer immunotherapy

Overcoming immunosuppression as a new immunotherapeutic approach against pancreatic cancer

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