Interferon-Dependent IL-10 Production by Tregs Limits Tumor Th17 Inflammation

“The capacity of IL-10 and Tregs in the inflammatory tumor microenvironment to impair anticancer Th1 immunity makes them attractive targets for cancer immunotherapy. IL-10 and Tregs also suppress Th17 activity, which is associated with poor prognosis in several cancers. However, previous studies have overlooked their potential contribution to the regulation of pathogenic cancer-associated inflammation. In this study, we investigated the origin and function of IL-10–producing cells in the tumor microenvironment using transplantable tumor models in mice. The majority of tumor-associated IL-10 was produced by an activated Treg population. IL-10 production by Tregs was required to restrain Th17-type inflammation. Accumulation of activated IL-10+ Tregs in the tumor required type I IFN signaling but not inflammatory signaling pathways that depend on TLR adapter protein MyD88 or IL-12 family cytokines. IL-10 production limited Th17 cell numbers in both spleen and tumor. However, type I IFN was required to limit Th17 cells specifically in the tumor microenvironment, reflecting selective control of tumor-associated Tregs by type I IFN. Thus, the interplay of type I IFN, Tregs, and IL-10 is required to negatively regulate Th17 inflammation in the tumor microenvironment. Therapeutic interference of this network could therefore have the undesirable consequence of promoting Th17 inflammation and cancer growth.”


Interferon-Dependent IL-10 Production by Tregs Limits Tumor Th17 Inflammation

“The capacity of IL-10 and Tregs in the inflammatory tumor microenvironment to impair anticancer Th1 immunity makes them attractive targets for cancer immunotherapy. IL-10 and Tregs also suppress Th17 activity, which is associated with poor prognosis in several cancers. However, previous studies have overlooked their potential contribution to the regulation of pathogenic cancer-associated inflammation. In this study, we investigated the origin and function of IL-10–producing cells in the tumor microenvironment using transplantable tumor models in mice. The majority of tumor-associated IL-10 was produced by an activated Treg population. IL-10 production by Tregs was required to restrain Th17-type inflammation. Accumulation of activated IL-10+ Tregs in the tumor required type I IFN signaling but not inflammatory signaling pathways that depend on TLR adapter protein MyD88 or IL-12 family cytokines. IL-10 production limited Th17 cell numbers in both spleen and tumor. However, type I IFN was required to limit Th17 cells specifically in the tumor microenvironment, reflecting selective control of tumor-associated Tregs by type I IFN. Thus, the interplay of type I IFN, Tregs, and IL-10 is required to negatively regulate Th17 inflammation in the tumor microenvironment. Therapeutic interference of this network could therefore have the undesirable consequence of promoting Th17 inflammation and cancer growth.”


An Interleukin-17-Mediated Paracrine Network Promotes Tumor Resistance to Anti-Angiogenic Therapy

“Although angiogenesis inhibitors have provided substantial clinical benefit as cancer therapeutics, their use is limited by resistance to their therapeutic effects. While ample evidence indicates that such resistance can be influenced by the tumor microenvironment, the underlying mechanisms remain incompletely understood. Here, we have uncovered a paracrine signaling network between the adaptive and innate immune systems that is associated with resistance in multiple tumor models: lymphoma, lung and colon. Tumor-infiltrating T helper type 17 (TH17) cells and interleukin-17 (IL-17) induced the expression of granulocyte colony-stimulating factor (G-CSF) through nuclear factor κB (NF-κB) and extracellular-related kinase (ERK) signaling, leading to immature myeloid-cell mobilization and recruitment into the tumor microenvironment. The occurrence of TH17 cells and Bv8-positive granulocytes was also observed in clinical tumor specimens. Tumors resistant to treatment with antibodies to VEGF were rendered sensitive in IL-17 receptor (IL-17R)-knockout hosts deficient in TH17 effector function. Furthermore, pharmacological blockade of TH17 cell function sensitized resistant tumors to therapy with antibodies to VEGF. These findings indicate that IL-17 promotes tumor resistance to VEGF inhibition, suggesting that immunomodulatory strategies could improve the efficacy of anti-angiogenic therapy.”


An Interleukin-17-Mediated Paracrine Network Promotes Tumor Resistance to Anti-Angiogenic Therapy

“Although angiogenesis inhibitors have provided substantial clinical benefit as cancer therapeutics, their use is limited by resistance to their therapeutic effects. While ample evidence indicates that such resistance can be influenced by the tumor microenvironment, the underlying mechanisms remain incompletely understood. Here, we have uncovered a paracrine signaling network between the adaptive and innate immune systems that is associated with resistance in multiple tumor models: lymphoma, lung and colon. Tumor-infiltrating T helper type 17 (TH17) cells and interleukin-17 (IL-17) induced the expression of granulocyte colony-stimulating factor (G-CSF) through nuclear factor κB (NF-κB) and extracellular-related kinase (ERK) signaling, leading to immature myeloid-cell mobilization and recruitment into the tumor microenvironment. The occurrence of TH17 cells and Bv8-positive granulocytes was also observed in clinical tumor specimens. Tumors resistant to treatment with antibodies to VEGF were rendered sensitive in IL-17 receptor (IL-17R)-knockout hosts deficient in TH17 effector function. Furthermore, pharmacological blockade of TH17 cell function sensitized resistant tumors to therapy with antibodies to VEGF. These findings indicate that IL-17 promotes tumor resistance to VEGF inhibition, suggesting that immunomodulatory strategies could improve the efficacy of anti-angiogenic therapy.”


An Interleukin-17-Mediated Paracrine Network Promotes Tumor Resistance to Anti-Angiogenic Therapy

“Although angiogenesis inhibitors have provided substantial clinical benefit as cancer therapeutics, their use is limited by resistance to their therapeutic effects. While ample evidence indicates that such resistance can be influenced by the tumor microenvironment, the underlying mechanisms remain incompletely understood. Here, we have uncovered a paracrine signaling network between the adaptive and innate immune systems that is associated with resistance in multiple tumor models: lymphoma, lung and colon. Tumor-infiltrating T helper type 17 (TH17) cells and interleukin-17 (IL-17) induced the expression of granulocyte colony-stimulating factor (G-CSF) through nuclear factor κB (NF-κB) and extracellular-related kinase (ERK) signaling, leading to immature myeloid-cell mobilization and recruitment into the tumor microenvironment. The occurrence of TH17 cells and Bv8-positive granulocytes was also observed in clinical tumor specimens. Tumors resistant to treatment with antibodies to VEGF were rendered sensitive in IL-17 receptor (IL-17R)-knockout hosts deficient in TH17 effector function. Furthermore, pharmacological blockade of TH17 cell function sensitized resistant tumors to therapy with antibodies to VEGF. These findings indicate that IL-17 promotes tumor resistance to VEGF inhibition, suggesting that immunomodulatory strategies could improve the efficacy of anti-angiogenic therapy.”