IMMU-45. CUSTOMIZED LIPID NANOPARTICLES DELIVER NUCLEIC ACIDS TO IMMUNE CELLS IN BRAIN TUMORS

Abstract BACKGROUND Brain tumors are notoriously difficult to treat in part due to their isolation behind the blood brain barrier and their power to suppress antitumor immune responses. We have previously reported cationic liposome formulations capable of delivering immune modulatory nucleic acids to immune cells in various peripheral organs, but there is currently no reliable method to deliver nucleic acids into brain tumors without direct injection into the tumor site. OBJECTIVE Here, we report the development of a customized lipid nanoparticle to deliver immune modulatory nucleic acids to immune cells in brain tumors. APPROACH Cationic liposomes composed of varying lipid combinations were evaluated for their ability to deliver functional mRNA and siRNA to innate immune cells in vitro and in intracranial tumor models. Nucleic acids were labelled with Cy3 to monitor particle distribution in vivo. RESULTS Lipids composed of DOTAP and cholesterol selectively delivered mRNA and siRNA to intracranial GL261 and KR158b tumors. Interestingly, these particles selectively delivered these nucleic acids to CD45+ white blood cells with minimal delivery to CD45- tumor cells or normal brain tissue. Encapsulation of siRNA blocking programmed death ligand 1 (PDL1) significantly reduced PDL1 expression on innate immune cells in brain tumors, with the greatest effects on tumor-associated macrophages. Co-administration of systemic checkpoint blockade with intravenous administration of these lipid nanoparticles bearing PDL1 siRNA enabled systemic and intratumoral checkpoint blockade, leading to 37% long term survivorship in an otherwise fatal intracranial tumor model. CONCLUSIONS Our customized lipid nanoparticles enable potent intratumoral immune modulation via delivery of nucleic acids to immune cells in brain tumors.

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IMMU-39. RNA LOADED LIPID-NANOPARTICLES FUNCTION AS CUSTOMIZABLE IMMUNOTHERAPEUTIC VEHICLES AGAINST MALIGNANT GLIOMAS

Neuro-Oncology ◽

10.1093/neuonc/noz175.531 ◽

2019 ◽

Vol 21 (Supplement_6) ◽

pp. vi127-vi127

Author(s):

Adam Grippin ◽

Brandon Wummer ◽

Hector Mendez-Gomez ◽

Brian Stover ◽

Jianping Huang ◽

...

Keyword(s):

Brain Tumor ◽

Tumor Microenvironment ◽

Immune Cells ◽

Lipid Nanoparticles ◽

Lymphoid Organs ◽

Innate Immune ◽

T Cell Immunity ◽

Innate Immune Cells ◽

Cell Immunity ◽

The Brain

Abstract BACKGROUND While dendritic cell (DC) vaccine therapy has shown considerable promise for glioblastoma (GBM) patients (Mitchell et al. Nature, 2015), their advancement into human clinical trials has been fraught with challenges in the development, manufacturing, and marketing of successful cancer immunotherapies. To circumvent the challenges associated with cell therapy, we have developed a new platform technology consisting of tumor derived mRNA complexed into lipid-nanoparticles (RNA-NPs) for systemic delivery to DCs in vivo and induction of antigen specific T cell immunity against GBM. OBJECTIVES/ METHODS We sought to assess if surface and charge modifications to our custom lipid-NP could facilitate its localization to lymphoid organs and the brain tumor microenvironment. RESULTS We demonstrate that intravenous administration of our unmodified custom RNA-NPs mediate systemic activation of DCs; these include activation of CD11c+ cells in the brains of animals with intact blood brain-barriers (BBBs). RNA-NPs mediate antigen specific T cell immunity and anti-tumor efficacy with increased tumor infiltrating lymphocytes against a NF-1/p53 mutant glioma that recapitulates features of human GBM in immunocompetent mice. Modification of surface charge could direct these RNA-NPs to lymphoid organs (e.g. spleen, lymph nodes) while modification of the lipid backbone (with cholesterol) enhances localization to innate immune cells in NF-1/p53 mutant and GL261 gliomas. We therefore assessed if this customizable lipid-NP could be leveraged for delivery of immune checkpoint inhibitors (ICIs) (i.e. PD-L1 siRNA) to the brain tumor microenvironment. Compared with scrambled siRNA-NPs in combination with ICIs, surface modified siRNA-NPs (antagonizing PD-L1) in combination with ICIs mediated significant antitumor efficacy with 37% long term survivors in an otherwise fatal brain tumor model. CONCLUSION We designed multifunctional RNA-NPs with a simple, scalable synthesis method that enables delivery of nucleic acids to innate immune cells in lymphoid organs and brain tumors.

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The behavior and function of innate immune cells during sterile inflammation and normal brain development in embryonic zebrafish

10.14711/thesis-b1190212 ◽

2012 ◽

Author(s):

Bo Yan

Keyword(s):

Brain Development ◽

Immune Cells ◽

Innate Immune ◽

Sterile Inflammation ◽

Normal Brain ◽

Innate Immune Cells ◽

And Function ◽

Normal Brain Development

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Effects of the ecto-ATPase apyrase on microglial ramification and surveillance reflect cell depolarization, not ATP depletion

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1715354115 ◽

2018 ◽

Vol 115 (7) ◽

pp. E1608-E1617 ◽

Cited By ~ 24

Author(s):

Christian Madry ◽

I. Lorena Arancibia-Cárcamo ◽

Vasiliki Kyrargyri ◽

Victor T. T. Chan ◽

Nicola B. Hamilton ◽

...

Keyword(s):

Immune Cells ◽

Purinergic Signaling ◽

Innate Immune ◽

Atp Depletion ◽

Normal Brain ◽

Innate Immune Cells ◽

High K ◽

Cell Depolarization ◽

Dying Cells ◽

The Brain

Microglia, the brain’s innate immune cells, have highly motile processes which constantly survey the brain to detect infection, remove dying cells, and prune synapses during brain development. ATP released by tissue damage is known to attract microglial processes, but it is controversial whether an ambient level of ATP is needed to promote constant microglial surveillance in the normal brain. Applying the ATPase apyrase, an enzyme which hydrolyzes ATP and ADP, reduces microglial process ramification and surveillance, suggesting that ambient ATP/ADP maintains microglial surveillance. However, attempting to raise the level of ATP/ADP by blocking the endogenous ecto-ATPase (termed NTPDase1/CD39), which also hydrolyzes ATP/ADP, does not affect the cells’ ramification or surveillance, nor their membrane currents, which respond to even small rises of extracellular [ATP] or [ADP] with the activation of K+ channels. This indicates a lack of detectable ambient ATP/ADP and ecto-ATPase activity, contradicting the results with apyrase. We resolve this contradiction by demonstrating that contamination of commercially available apyrase by a high K+ concentration reduces ramification and surveillance by depolarizing microglia. Exposure to the same K+ concentration (without apyrase added) reduced ramification and surveillance as with apyrase. Dialysis of apyrase to remove K+ retained its ATP-hydrolyzing activity but abolished the microglial depolarization and decrease of ramification produced by the undialyzed enzyme. Thus, applying apyrase affects microglia by an action independent of ATP, and no ambient purinergic signaling is required to maintain microglial ramification and surveillance. These results also have implications for hundreds of prior studies that employed apyrase to hydrolyze ATP/ADP.

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