Characterization of a novel MR‐detectable nanoantioxidant that mitigates the recall immune response

Abstract

In many human diseases, the presence of inflammation is associated with an increase in the level of reactive oxygen species (ROS). The resulting state of oxidative stress is highly detrimental and can initiate a cascade of events that ultimately lead to cell death. Thus, many therapeutic attempts have been focused on either modulating the immune system to lower inflammation or reducing the damaging caused by ROS. Berlin et al. reported the development of a novel nanoantioxidant known as poly(ethylene glycol)‐functionalized‐hydrophilic carbon clusters (PEG‐HCCs). They showed that PEG‐HCCs could be targeted to cancer cells, utilized as a drug delivery vector, and can even be visualized ex vivo. Our work here furthers this work and characterizes Gd‐DTPA conjugated PEG‐HCCs and explores the potential for in vivo tracking of T cells in live mice. We utilized a mouse model of delayed‐type hypersensitivity (DTH) to assess the immunomodulatory effects of PEG‐HCCs. The T 1‐agent Gd‐DTPA was then conjugated to the PEG‐HCCs and T 1 measurements, and T 1‐weighted MRI of the modified PEG‐HCCs was done to assess their relaxivity. We then assessed if PEG‐HCCs could be visualized both ex vivo and in vivo within the mouse lymph node and spleen. Mice treated with PEG‐HCCs showed significant improvements in the DTH assay as compared to the vehicle (saline)‐treated control. Flow cytometry demonstrated that splenic T cells are capable of internalizing PEG‐HCCs whereas fluorescent immunohistochemistry showed that PEG‐HCCs are detectable within the cortex of lymph nodes. Finally, our nanoantioxidants can be visualized in vivo within the lymph nodes and spleen of a mouse after addition of the Gd‐DTPA. PEG‐HCCs are internalized by T cells in the spleen and can reduce inflammation by suppression of a recall immune response. PEG‐HCCs can be modified to allow for both in vitro and in vivo visualization using MRI. © 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

Antioxidant Carbon Nanoparticles Inhibit Fibroblast-Like Synoviocyte Invasiveness and Reduce Disease Severity in a Rat Model of Rheumatoid Arthritis

“…Activators of antioxidant pathways, such as dimethyl fumarate, induce lymphopenia by killing activated T lymphocytes [ 46 ]. As T cells can endocytose PEG-HCCs [ 16 , 17 ], we collected the inguinal lymph nodes of vehicle-treated and PEG-HCC-treated PIA rats to determine if they too induce lymphopenia. We found no differences in the percentage of total T lymphocytes, identified by the expression of CD3 ( Figure 7 A), in the percentage of activated T cells (CD3 + CD25 + ) ( Figure 7 B), or in naïve (CD3 + CD45RC + ) or memory (CD3 + CD45RC − ) T lymphocytes ( Figure 7 C) [ 47 ].…”

“…To quantify cellular uptake of PEG-HCCs [ 16 , 17 ], FLS were incubated in ultralow adhesion 24-well plates with PEG-HCCs for different durations at 37 °C, 5% CO 2 . Cells were fixed with PBS + 1% paraformaldehyde.…”

“…We have previously demonstrated that PEG-HCCs are preferentially endocytosed by highly metabolic cells, such as T lymphocytes, and inhibit their function via scavenging intracellular O 2 •− [ 16 , 17 ]. As FLS are highly metabolic and have elevated levels of O 2 •− during RA [ 10 , 18 ], we sought to define their sensitivity to PEG-HCCs and the ability of these nanoparticles to treat a rat model of RA.…”

Nanoparticles Targeting Lymph Nodes for Cancer Immunotherapy: Strategies and Influencing Factors

“…This creates electrostatic or steric repulsion force among NPs, mitigating cluster formation. [72] The protein corona, a layer of proteins adhering to NPs in biological fluids, can affect the NPs' properties and interactions, including size, charge, aggregation, and cellular uptake. [123,124] Coating NPs with PEG significantly reduces the formation of the protein corona by interfering with the protein adsorption process, thereby limiting the amount and variety of proteins that can attach to the NP surface.…”