The use of light in cancer immunotherapy

The breakthrough of immunotherapy for cancer has introduced promising new options, but nonetheless only a minority of cancer patients show significant clinical benefit. This situation has inspired two avenues of research to find solutions to this problem: mechanistic studies to decipher the working mechanisms of immunotherapies and to investigate why many patients do not respond, and studies developing combination treatments to achieve clinical benefit in situations where immunotherapy alone is not sufficient. This thesis explores both these avenues by investigating applications of visible light in immunotherapy of cancer in pre-clinical models. We developed optical imaging platforms for visualization of immune cells and immunotherapies, which can shed light on the immunological events after administration of immunotherapy. In addition, we investigated novel therapies based on the combination of tumor ablation by Photodynamic Therapy and different types of immunotherapy. Our findings may prove useful in understanding success and failure of immunotherapy, and provide new combination treatment options when the efficacy of monotherapy is insufficient.LUMC / Geneeskunde Repositoriu

PD-L1 immune suppression in cancer: Tumor cells or host cells?

Experimental cancer immunology and therap

PD-L1 expression on malignant cells is no prerequisite for checkpoint therapy

Experimental cancer immunology and therap

IL-6 signaling in macrophages is required for immunotherapy-driven regression of tumors

Background High serum interleukin (IL-6) levels may cause resistance to immunotherapy by modulation of myeloid cells in the tumor microenvironment. IL-6 signaling blockade is tested in cancer, but as this inflammatory cytokine has pleiotropic effects, this treatment is not always effective. Methods IL-6 and IL-6R blockade was applied in an IL-6-mediated immunotherapy-resistant TC-1 tumor model (TC-1.IL-6) and immunotherapy-sensitive TC-1.control. Effects on therapeutic vaccination-induced tumor regression, recurrence and survival as well on T cells and myeloid cells in the tumor microenvironment were studied. The effects of IL-6 signaling in macrophages under therapy conditions were studied in Il6ra(fl/fl)xLysM(cre+) mice. Results Our therapeutic vaccination protocol elicits a strong tumor-specific CD8(+) T-cell response, leading to enhanced intratumoral T-cell infiltration and recruitment of tumoricidal macrophages. Blockade of IL-6 signaling exacerbated tumor outgrowth, reflected by fewer complete regressions and more recurrences after therapeutic vaccination, especially in TC-1.IL-6 tumor-bearing mice. Early IL-6 signaling blockade partly inhibited the development of the vaccine-induced CD8(+) T-cell response. However, the main mechanism was the malfunction of macrophages during therapy-induced tumor regression. Therapy efficacy was impaired in Il6ra(fl/fl)xLysM(cre+) but not cre-negative control mice, while no differences in the vaccine-induced CD8(+) T-cell response were found between these mice. IL-6 signaling blockade resulted in decreased expression of suppressor of cytokine signaling 3, essential for effective M1-type function in macrophages, and increased expression of the phagocytic checkpoint molecule signal-regulatory protein alpha by macrophages. Conclusion IL-6 signaling is critical for macrophage function under circumstances of immunotherapy-induced tumor tissue destruction, in line with the acute inflammatory functions of IL-6 signaling described in infections.Experimental cancer immunology and therap

A Restricted Role for FcγR in the Regulation of Adaptive Immunity.

By their interaction with IgG immune complexes, FcγR and complement link innate and adaptive immunity, showing functional redundancy. In complement-deficient mice, IgG downstream effector functions are often impaired, as well as adaptive immunity. Based on a variety of model systems using FcγR-knockout mice, it has been concluded that FcγRs are also key regulators of innate and adaptive immunity; however, several of the model systems underpinning these conclusions suffer from flawed experimental design. To address this issue, we generated a novel mouse model deficient for all FcγRs (FcγRI/II/III/IV-/- mice). These mice displayed normal development and lymphoid and myeloid ontogeny. Although IgG effector pathways were impaired, adaptive immune responses to a variety of challenges, including bacterial infection and IgG immune complexes, were not. Like FcγRIIb-deficient mice, FcγRI/II/III/IV-/- mice developed higher Ab titers but no autoantibodies. These observations indicate a redundant role for activating FcγRs in the modulation of the adaptive immune response in vivo. We conclude that FcγRs are downstream IgG effector molecules with a restricted role in the ontogeny and maintenance of the immune system, as well as the regulation of adaptive immunity

A Dual-Color Bioluminescence Reporter Mouse for Simultaneous in vivo Imaging of T Cell Localization and Function

Non-invasive imaging technologies to visualize the location and functionality of T cells are of great value in immunology. Here, we describe the design and generation of a transgenic mouse in which all T cells constitutively express green-emitting click-beetle luciferase (CBG99) while expression of the red-emitting firefly luciferase (PpyRE9) is induced by Nuclear Factor of Activated T cells (NFAT) such as during T cell activation, which allows multicolor bioluminescence imaging of T cell location and function. This dual-luciferase mouse, which we named TbiLuc, showed high constitutive luciferase expression in lymphoid organs such as lymph nodes and the spleen. Ex vivo purified CD8+ and CD4+ T cells both constitutively expressed luciferase, whereas B cells showed no detectable signal. We cross-bred TbiLuc mice to T cell receptor-transgenic OT-I mice to obtain luciferase-expressing naïve CD8+ T cells with defined antigen-specificity. TbiLuc*OT-I T cells showed a fully antigen-specific induction of the T cell activation-dependent luciferase. In vaccinated mice, we visualized T cell localization and activation in vaccine-draining lymph nodes with high sensitivity using two distinct luciferase substrates, D-luciferin and CycLuc1, of which the latter specifically reacts with the PpyRE9 enzyme. This dual-luciferase T cell reporter mouse can be applied in many experimental models studying the location and functional state of T cells

The use of light in cancer immunotherapy

The breakthrough of immunotherapy for cancer has introduced promising new options, but nonetheless only a minority of cancer patients show significant clinical benefit. This situation has inspired two avenues of research to find solutions to this problem: mechanistic studies to decipher the working mechanisms of immunotherapies and to investigate why many patients do not respond, and studies developing combination treatments to achieve clinical benefit in situations where immunotherapy alone is not sufficient. This thesis explores both these avenues by investigating applications of visible light in immunotherapy of cancer in pre-clinical models. We developed optical imaging platforms for visualization of immune cells and immunotherapies, which can shed light on the immunological events after administration of immunotherapy. In addition, we investigated novel therapies based on the combination of tumor ablation by Photodynamic Therapy and different types of immunotherapy. Our findings may prove useful in understanding success and failure of immunotherapy, and provide new combination treatment options when the efficacy of monotherapy is insufficient.</p

Photodynamic-Immune Checkpoint Therapy Eradicates Local and Distant Tumors by CD8(+) T Cells

Tumorimmunolog

Photodynamic cancer therapy enhances accumulation of nanoparticles in tumor-associated myeloid cells

In cancer treatment, nanomedicines may be employed in an attempt to improve the tumor localization of antineoplastic drugs e.g. immunotherapeutic agents either through passive or active targeting, thereby potentially enhancing therapeutic effect and reducing undesired off-target effects. However, a large number of administrated nanocarriers often fail to reach the tumor area. In the present study, we show that photodynamic therapy (PDT) enhances the tumor accumulation of systemically administered lipid-PEG layer coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NP). Intravital microscopy and histological analysis of the tumor area reveal that the tumor vasculature was disrupted after PDT, disturbing blood flow and coinciding with entrapment of nanocarriers in the tumor area. We observed that the nanoparticles accumulating after treatment do not confine to specific locations within the tumor, but rather localize to various cells present throughout the tumor area. Finally, we show by flow cytometry that NP accumulation occurred mostly in immune cells of the myeloid lineage present in the tumor microenvironment (TME) as well as in tumor cells, albeit to a lower extent. These data expose opportunities for combination treatments of clinical PDT with NP-based immunotherapy to modulate the TME and improve antitumor immune responses.Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas