Sissela Broos

Immunomodulatory nanoparticles as adjuvants and allergen-delivery system to human dendritic cells: Implications for specific immunotherapy.

Novel adjuvants and antigen-delivery systems with immunomodulatory properties that shift the allergenic Th2 response towards a Th1 or regulatory T cell response are desired for allergen-specific immunotherapy. This study demonstrates that 200-nm sized biodegradable poly(gamma-glutamic acid) (gamma-PGA) nanoparticles (NPs) are activators of human monocyte-derived dendritic cells (MoDCs). Gamma-PGA NPs are efficiently internalized by immature MoDCs and strongly stimulate production of chemokines and inflammatory cytokines as well as up-regulation of co-stimulatory molecules and immunomodulatory mediators involved in efficient T cell priming. Furthermore, MoDCs from allergic subjects stimulated in vitro with a mixture of gamma-PGA NPs and extract of grass pollen allergen Phleum pratense (Phl p) augment allergen-specific IL-10 production and proliferation of autologous CD4(+) memory T cells. Thus, gamma-PGA NPs are promising as sophisticated adjuvants and allergen-delivery systems in allergen-specific immunotherapy.

The human agonistic CD40 antibody ADC-1013 eradicates bladder tumors and generates T cell dependent tumor immunity

Purpose: Local administration of immune-activating antibodies may increase the efficacy and reduce the immune-related adverse events associated with systemic immunotherapy of cancer. Here, we report the development and affinity maturation of a fully human agonistic CD40 antibody (IgG1), ADC-1013. Experimental Design: We have used molecular engineering to generate an agonistic antibody with high affinity for CD40. The functional activity of ADC-1013 was investigated in human and murine in vitro models. The in vivo effect was investigated in two separate bladder cancer models, both using human xenograft tumors in immune deficient NSG mice and using a syngeneic bladder cancer model in a novel human CD40 transgenic mouse. Results: Activation of dendritic cells (DC) by ADC-1013 results in upregulation of the costimulatory molecules CD80 and CD86, and secretion of IL12. ADC-1013 also activates DCs from human CD40 transgenic mice, and peptide-pulsed and ADC-1013–stimulated DCs induce antigen-specific T-cell proliferation in vitro. In vivo, treatment with ADC-1013 in a syngeneic bladder cancer model, negative for hCD40, induces significant antitumor effects and long-term tumor-specific immunity. Furthermore, ADC-1013 demonstrates significant antitumor effects in a human bladder cancer transplanted into immunodeficient NSG mice. Conclusions: Our data demonstrate that ADC-1013 induces long-lasting antitumor responses and immunologic memory mediated by CD40 stimulation. To the best of our knowledge, ADC-1013 represents the first immunomodulatory antibody developed for local immunotherapy of cancer. Clin Cancer Res; 21(5); 1115–26. ©2014 AACR. See related commentary by Dronca and Dong, p. 944

Synergistic augmentation of CD40-mediated activation of antigen-presenting cells by amphiphilic poly(γ-glutamic acid) nanoparticles.

Agonistic anti-CD40 monoclonal antibodies (mAbs) hold great potential for cancer immunotherapy. However, systemic administration of anti-CD40 mAbs can be associated with severe side effects, such as cytokine release syndrome and liver damage. With the aim to increase the immunostimulatory potency as well as to achieve a local drug retention of anti-CD40 mAbs, we linked an agonistic mAb to immune activating amphiphilic poly(γ-glutamic acid) nanoparticles (γ-PGA NPs). We demonstrate that adsorption of anti-CD40 mAb to γ-PGA NPs (anti-CD40-NPs) improved the stimulatory capacity of the CD40 agonist, resulting in upregulation of costimulatory CD80 and CD86 on antigen-presenting cells, as well as IL-12 secretion. Interestingly, anti-CD40-NPs induced strong synergistic proliferative effects in B cells, possibly resulting from a higher degree of CD40 multimerization, enabled by display of multiple anti-CD40 mAbs on the NPs. In addition, local treatment with anti-CD40-NPs, compared to only soluble CD40 agonist, resulted in a significant reduction in serum levels of IL-6, IL-10, IL-12 and TNF-α in a bladder cancer model. Taken together, our results suggest that anti-CD40-NPs are capable of synergistically enhancing the immunostimulatory effect induced by the CD40 agonist, as well as minimizing adverse side effects associated with systemic cytokine release. This concept of nanomedicine could play an important role in localized immunotherapy of cancer.

Allergen-Specific Immunotherapy Alters the Frequency, as well as the FcR and CLR Expression Profiles of Human Dendritic Cell Subsets.

Allergen-specific immunotherapy (AIT) induces tolerance and shifts the Th2 response towards a regulatory T-cell profile. The underlying mechanisms are not fully understood, but dendritic cells (DC) play a vital role as key regulators of T-cell responses. DCs interact with allergens via Fc receptors (FcRs) and via certain C-type lectin receptors (CLRs), including CD209/DC-SIGN, CD206/MR and Dectin-2/CLEC6A. In this study, the effect of AIT on the frequencies as well as the FcR and CLR expression profiles of human DC subsets was assessed. PBMC was isolated from peripheral blood from seven allergic donors before and after 8 weeks and 1 year of subcutaneous AIT, as well as from six non-allergic individuals. Cells were stained with antibodies against DC subset-specific markers and a panel of FcRs and CLRs and analyzed by flow cytometry. After 1 year of AIT, the frequency of CD123+ DCs was increased and a larger proportion expressed FcεRI. Furthermore, the expression of CD206 and Dectin-2 was reduced on CD141+ DCs after 1 year of treatment and CD206 as well as Dectin-1 was additionally down regulated in CD1c+ DCs. Interestingly, levels of DNGR1/CLEC9A on CD141+ DCs were increased by AIT, reaching levels similar to cells isolated from non-allergic controls. The modifications in phenotype and occurrence of specific DC subsets observed during AIT suggest an altered capacity of DC subsets to interact with allergens, which can be part of the mechanisms by which AIT induces allergen tolerance.

C-type Lectin Receptor Expression on Human Basophils and Effects of Allergen-Specific Immunotherapy

Basophils are emerging as immunoregulatory cells capable of interacting with their environment not only via their characteristic IgE‐mediated activation, but also in an IgE‐independent manner. Basophils are known to express and respond to stimulation via TLR2, TLR4, DC‐SIGN and DCIR, but whether basophils also express other C‐type lectin receptors (CLRs) is largely unknown. In this study, we investigate the CLR expression profile of human basophils using multicolour flow cytometry. As FcRs as well as some CLRs are associated with allergen recognition and shown to be involved in subsequent immune responses, the expression of CLRs and FcRs on peripheral blood basophils, as well as their frequency, was monitored for 1 year in subjects undergoing subcutaneous allergen‐specific immunotherapy (AIT). Here, we show that human basophils express CLECSF14, DEC205, Dectin‐1, Dectin‐2 and MRC2. Furthermore, we demonstrate that the frequencies of basophils expressing the allergy‐associated CLRs Dectin‐1 and Dectin‐2 were significantly reduced after 1 year and 8 weeks of AIT, respectively. In contrast, the frequency of basophils positive for FcγRII, as well as the fraction of total basophils, significantly increased after 1 year of AIT. The herein demonstrated expression of various CLRs on basophils, and their altered CLR and FcR expression profile upon AIT, suggest yet unexplored ways by which basophils can interact with antigens and may point to novel immunoregulatory functions targeted through AIT.

ADC-1013, an agonistic CD40 antibody optimized for local immunotherapy of cancer

Local administration of immune activating antibodies may increase the efficacy and reduce the immune-related adverse events associated with systemic immunotherapy of cancer. Here we report the development of a fully human agonistic CD40 antibody (IgG1), ADC-1013, which has been optimized for local immunotherapy by increasing potency and tumor retention. ADC-1013 activates CD40 receptors on antigen-presenting cells such as dendritic cells, resulting in up-regulation of the co-stimulatory molecules CD80 and CD86, and induction of IL-12. In addition, ADC-1013 induces direct tumor killing of CD40+ tumors, e.g. via antibody-dependent cellular cytotoxicity (ADCC). The anti-tumor effects of ADC-1013 were first assessed in a bladder cancer model (EJ) in immunodeficient NSG mice. Significant anti-tumor responses were demonstrated, and further augmented in mice repopulated with human moDCs/T cells. To study the anti-tumor effects related to the immune activating properties of ADC-1013 in more detail, a human CD40 positive transgenic mouse (hCD40tg) in C57/BL-6 background was used. This transgenic mouse strain has an intact immune system and fully functional dendritic cells that are activated upon ADC-1013 treatment. Furthermore, the dendritic cells obtained from this strain are able to induce antigen specific T cell activation in vitro upon stimulation with ADC-1013. Importantly, treatment with ADC-1013 in a syngeneic bladder cancer (MB49) model, which is hCD40 negative, demonstrated that ADC-1013 induce significant tumor protection and long term immunity independent of direct tumor targeting. In addition, the anti-tumor immunity was shown to be T-cell dependent. To our knowledge, ADC-1013 represents the first immunomodulatory antibody optimized for local immunotherapy of cancer. It is currently in late pre-clinical development and will enter clinical trials in 2014.

Synergistic effects of agonistic costimulatory antibodies adsorbed to amphiphilic poly(γ-glutamic acid) nanoparticles

Agonistic antibodies targeting costimulatory pathways for the immune system hold great potential for cancer immunotherapy. However, systemic administration of immunoactivating antibodies can be associated with side effects such as cytokine release syndrome and liver toxicity. Polymeric nanoparticles (NPs) represent an exciting approach to control the release of therapeutic antibodies and to optimize the desired immune response via selective targeting. With increased potency as objective, agonistic antibodies targeting TNF receptors were adsorbed to immune stimulating biodegradable and self-assembled polymeric nanoparticles composed of g-glutamic acid (g-PGA NPs). The effects of antibodies targeting CD40, CD137 and OX40 were evaluated based on T and B cell proliferation as well as on cytokine release and phenotypic maturation of antigen-presenting cells. Our results demonstrated a strong synergistic effect on human B cell proliferation of CD40 monoclonal antibodies (mAbs) carrying NPs in vitro. In addition adsorption of anti-CD40 mAb to g-PGA NPs significantly reduced the systemic release of TNF-a ,I L-6, IL-10 and IL-12, compared to treatment with the soluble mAb. Preliminary results indicate increased T cell proliferation and activation by CD137 and OX40 agonistic antibodies in combination with g-PGA NPs. Combining NPs with agonistic antibodies for cancer immunotherapy offers intriguing opportunities for increased therapeutic efficacy and safety.

Nanoparticle-Based Specific Targeting of Antigen-Presenting Cells for Immunotherapy

Immunotherapy, which involves strategies to activate, enhance or redirect immune responses to achieve long-lasting immunity, has the potential to play an important role in the treatment of a variety of diseases. This thesis, based on four original papers, highlights different approaches to modulate immune responses by specific targeting of antigen-presenting cells. The first two studies focuses on regulation of allergic responses. In Paper I, we showed that biodegradable poly(γ-glutamic acid) (γ-PGA) nanoparticles influence allergen-specific T cell activation, suggesting a beneficial role as adjuvants in allergen-specific immunotherapy. In Paper II, the histamine H4 receptor was shown to mediate histamine-induced activation of human dendritic cells and enhance their Th2 cell stimulating capacity in response to allergen. This suggests that blocking of the histamine H4 receptor may be a promising strategy to modulate allergic responses. The last two studies involve strategies to optimise CD40-targeted cancer immunotherapy. In Paper III, adsorption of agonistic anti-CD40 monoclonal antibodies to γ-PGA nanoparticles was shown to enhance their efficacy and reduce the systemic release of cytokines after local drug delivery. In Paper IV, we demonstrated that increasing the affinity and the isoelectric point of an anti-CD40 antibody resulted in enhanced potency and tumour retention of the locally applied drug. The above strategies may thus serve to improve the efficacy and safety of local CD40-targeted immunotherapy. In conclusion, this thesis underlines the promise of directing immunotherapies to antigen-presenting cells, and in particular dendritic cells, which are central decision makers of the immune system. (Less)

Amphiphilic γ-PGA nanoparticles administered on rat middle ear mucosa produce adjuvant-like immunostimulation in vivo.

Abstract Conclusion: Amphiphilic biodegradable nanoparticles (NPs) composed of poly(γ-glutamic acid) conjugated with L-phenylalanine ethylester (γ-PGA-Phe NPs) applied on the rat middle ear mucosa produce an inflammatory type 1 response. The observation is of relevance for the use of γ-PGA-Phe NPs as a concomitant antigen delivery system and adjuvant measure in the context of vaccinations. Objectives: To examine effects of topical mucosal administration of γ-PGA-Phe NPs as a potentially combined antigen delivery system and adjuvant. Methods: γ-PGA-Phe NPs were administered on rat middle ear mucosa in a sham-controlled design and the response was monitored, focusing on soluble markers in mucosal surface liquids and on overall histopathology. Results: γ-PGA-Phe NPs produced a dose- and time-dependent inflammatory response characterized by generation of proinflammatory cytokines (IL-1α, IL-1β, IL-6, MIP-1α, and TNF-α) and associated histopathological changes.