Interaction of Iron Oxide Nanoparticles with Macrophages Is Influenced Distinctly by "Self" and "Non-Self" Biological Identities

Nano-modified viruses prime the tumor microenvironment and promote the photodynamic virotherapy in liver cancer

BACKGROUND

As of 2020, hepatocellular carcinoma (HCC), a form of liver cancer, stood as the third most prominent contributor to global cancer-related mortality. Combining immune checkpoint inhibitors (ICI) with other therapies has shown promising results for treating unresectable HCC, offering new opportunities. Recombinant adeno-associated viral type 2 (AAV2) virotherapy has been approved for clinical use but it efficacy is stifled through systemic administration. On the other hand, iron oxide nanoparticles (ION) can be cleared via the liver and enhance macrophage polarization, promoting infiltration of CD8+ T cells and creating a more favorable tumor microenvironment for immunotherapy.

METHODS

To enhance the efficacy of virotherapy and promote macrophage polarization towards the M1-type in the liver, ION-AAV2 were prepared through the coupling of ION-carboxyl and AAV2-amine using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC)/N-hydroxysulfosuccinimide (Sulfo-NHS). Efficacy after systemic delivery of ION-AAV2 in an orthotopic HCC model was evaluated.

RESULTS

After 28 days, the tumor weight in mice treated with ION-AAV2 was significantly reduced by 0.56-fold compared to the control group. The ION-AAV2 treatment led to an approximate 1.80-fold increase in the level of tumor associated M1-type macrophages, while the number of M2-type macrophages was reduced by 0.88-fold. Moreover, a proinflammatory response increased the population of tumor-infiltrating CD8+ T cells in the ION-AAV2 group. This transformation converted cold tumors into hot tumors.

CONCLUSIONS

Our findings suggest that the conjugation of ION with AAV2 could be utilized in virotherapy while simultaneously exploiting macrophage-modulating cancer immunotherapies to effectively suppress HCC growth.

Intravenous Injection of PEI-Decorated Iron Oxide Nanoparticles Impacts NF-kappaB Protein Expression in Immunologically Stressed Mice

Nanoparticle-based formulations are considered valuable tools for diagnostic and treatment purposes. The surface decoration of nanoparticles with polyethyleneimine (PEI) is often used to enhance their targeting and functional properties. Here, we aimed at addressing the long-term fate in vivo and the potential "off-target" effects of PEI decorated iron oxide nanoparticles (PEI-MNPs) in individuals with low-grade and persistent systemic inflammation. For this purpose, we synthesized PEI-MNPs (core-shell method, PEI coating under high pressure homogenization). Further on, we induced a low-grade and persistent inflammation in mice through regular subcutaneous injection of pathogen-associated molecular patterns (PAMPs, from zymosan). PEI-MNPs were injected intravenously. Up to 7 weeks thereafter, the blood parameters were determined via automated fluorescence flow cytometry, animals were euthanized, and the organs analyzed for iron contents (atomic absorption spectrometry) and for expression of NF-κB associated proteins (p65, IκBα, p105/50, p100/52, COX-2, Bcl-2, SDS-PAGE and Western blotting). We observed that the PEI-MNPs had a diameter of 136 nm and a zeta-potential 56.9 mV. After injection in mice, the blood parameters were modified and the iron levels were increased in different organs. Moreover, the liver of animals showed an increased protein expression of canonical NF-κB signaling pathway members early after PEI-MNP application, whereas at the later post-observation time, members of the non-canonical signaling pathway were prominent. We conclude that the synergistic effect between PEI-MNPs and the low-grade and persistent inflammatory state is mainly due to the hepatocytes sensing infection (PAMPs), to immune responses resulting from the intracellular metabolism of the uptaken PEI-MNPs, or to hepatocyte and immune cell communications. Therefore, we suggest a careful assessment of the safety and toxicity of PEI-MNP-based carriers for gene therapy, chemotherapy, and other medical applications not only in healthy individuals but also in those suffering from chronic inflammation.

Evaluation of Dimercaptosuccinic Acid-Coated Iron Nanoparticles Immunotargeted to Amyloid Beta as MRI Contrast Agents for the Diagnosis of Alzheimer's Disease

Nanoparticle-based magnetic contrast agents have opened the potential for magnetic resonance imaging (MRI) to be used for early non-invasive diagnosis of Alzheimer's disease (AD). Accumulation of amyloid pathology in the brain has shown association with cognitive decline and tauopathy; hence, it is an effective biomarker for the early detection of AD. The aim of this study was to develop a biocompatible magnetic nanoparticle targeted to amyloid beta (Aβ) plaques to increase the sensitivity of T2-weighted MRI for imaging of amyloid pathology in AD. We presented novel iron core-iron oxide nanoparticles stabilized with a dimercaptosuccinic acid coating and functionalized with an anti-Aβ antibody. Nanoparticle biocompatibility and cellular internalization were evaluated in vitro in U-251 glioblastoma cells using cellular assays, proteomics, and transmission electron microscopy. Iron nanoparticles demonstrated no significant in vitro cytotoxicity, and electron microscopy results showed their movement through the endocytic cycle within the cell over a 24 h period. In addition, immunostaining and bio-layer interferometry confirmed the targeted nanoparticle's binding affinity to amyloid species. The iron nanoparticles demonstrated favourable MRI contrast enhancement; however, the addition of the antibody resulted in a reduction in the relaxivity of the particles. The present work shows promising preliminary results in the development of a targeted non-invasive method of early AD diagnosis using contrast-enhanced MRI.