Iron oxide nanoparticles induce cytokine secretion in a complement-dependent manner in a human whole blood model

An insight into impact of nanomaterials toxicity on human health

In recent years, advances in nanotechnology have significantly influenced electronics manufacturing, industrial processes, and medical research. Various industries have seen a surge in the use of nanomaterials. However, several researchers have raised the alarm about the toxicological nature of nanomaterials, which appear to be quite different from their crude forms. This altered nature can be attributed to their unique physicochemical profile. They can adversely affect human health and the environment. Nanomaterials that have been released into the environment tend to accumulate over time and can cause a significant impact on the ecosystem and organisms with adverse health effects. Increased use of nanoparticles has led to increased human exposure in their daily lives, making them more vulnerable to nanoparticle toxicity. Because of their small size, nanomaterials can readily cross biological membranes and enter cells, tissues, and organs. Therefore, the effect of nanomaterials on the human environment is of particular concern. The toxicological effects of nanomaterials and their mechanisms of action are being researched worldwide. Technological advances also support monitoring new nanomaterials marketed for industrial and household purposes. It is a challenging area because of the exceptional physicochemical properties of nanomaterials. This updated review focuses on the diverse toxicological perspective of nanomaterials. We have discussed the use of different types of nanoparticles and their physiochemical properties responsible for toxicity, routes of exposure, bio-distribution, and mechanism of toxicity. The review also includes various in vivo and in vitro methods of assessing the toxicity of nanomaterials. Finally, this review will provide a detailed insight into nano material-induced toxicological response, which can be beneficial in designing safe and effective nanoparticles.

Engineered Nanomaterials for Immunomodulation: A Review

The immune system usually provides a defense against invading pathogenic microorganisms and any other particulate contaminants. Nonetheless, it has been recently reported that nanomaterials can evade the immune system and modulate immunological responses due to their unique physicochemical characteristics. Consequently, nanomaterial-based activation of immune components, i.e., neutrophils, macrophages, and other effector cells, may induce inflammation and alter the immune response. Here, it is essential to distinguish the acute and chronic modulations triggered by nanomaterials to determine the possible risks to human health. Nanomaterials size, shape, composition, surface charge, and deformability are factors controlling their uptake by immune cells and the resulting immune responses. The exterior corona of molecules adsorbed over nanomaterials surfaces also influences their immunological effects. Here, we review current nanoengineering trends for targeted immunomodulation with an emphasis on the design, safety, and potential toxicity of nanomaterials. First, we describe the characteristics of engineered nanomaterials that trigger immune responses. Then, the biocompatibility and immunotoxicity of nanoengineered particles are debated, because these factors influence applications. Finally, future nanomaterial developments in terms of surface modifications, synergistic approaches, and biomimetics are discussed.

Complement-dependent uptake of nanoparticles by blood phagocytes: brief overview and perspective

Immune recognition and uptake of nanoparticles remain the hot topic in nanomedicine research. Complement is the central player in the immune recognition of engineered nanoparticles. Here, we summarize the accumulated knowledge on the role of complement in the interactions of nanomaterials with blood phagocytes. We describe the interplay between surface properties, complement opsonization, and immune uptake, primarily of iron oxide nanoparticles. We discuss the rigor of the published research and further identify the following knowledge gaps: 1) the role of complement in the variability of uptake of nanomaterials in healthy and diseased subjects, and 2) modulation of complement interactions to improve the performance of nanomaterials. Addressing these gaps is critical to improving translational chances of nanomaterials for drug delivery and imaging applications.

Liposomes - Human phagocytes interplay in whole blood: effect of liposome design

Nanomedicine holds immense potential for therapeutic manipulation of phagocytic immune cells. However, in vitro studies often fail to accurately translate to the complex in vivo environment. To address this gap, we employed an ex vivo human whole-blood assay to evaluate liposome interactions with immune cells. We systematically varied liposome size, PEG-surface densities and sphingomyelin and ganglioside content. We observed differential uptake patterns of the assessed liposomes by neutrophils and monocytes, emphasizing the importance of liposome design. Interestingly, our results aligned closely with published in vivo observations in mice and patients. Moreover, liposome exposure induced changes in cytokine release and cellular responses, highlighting the potential modulation of immune system. Our study highlights the utility of human whole-blood models in assessing nanoparticle-immune cell interactions and provides insights into liposome design for modulating immune responses.

Application of magnetic iron oxide nanoparticles: Thrombotic activity, imaging and cytocompatibility of silica-coated and carboxymethyl dextrane-coated particles

Coated iron oxide nanoparticles (IONs) are promising candidates for various applications in nanomedicine, including imaging, magnetic hyperthermia, and drug delivery. The application of IONs in nanomedicine is influenced by factors such as biocompatibility, surface properties, agglomeration, degradation behavior, and thrombogenicity. Therefore, it is essential to investigate the effects of coating material and thickness on the behavior and performance of IONs in the human body. In this study, IONs with a carboxymethyl dextran (CMD) coating and two thicknesses of silica coating (TEOS0.98, and TEOS3.91) were screened and compared to bare iron oxide nanoparticles (BIONs). All three coated particles showed good cytocompatibility (>70%) when tested with smooth muscle cells over three days. To investigate their potential long term behavior inside the human body, the Fe²⁺ release and hydrodynamic diameters of silica-coated and CMD (carboxymethyl dextrane)-coated IONs were analyzed in simulated body fluids for 72 h at 37 °C. The ION@CMD showed moderate agglomeration of around 100 nm in all four simulated fluids and dissolved faster than the silica-coated particles in artificial exosomal fluid and artificial lysosomal fluid. The particles with silica coating agglomerated in all tested simulated media above 1000 nm. Increased thickness of the silica coating led to decreased degradation of particles. Additionally, CMD coating resulted in nanoparticles with the least prothrombotic activity, and the thick silica coating apparently decreased the prothrombotic properties of nanoparticles compared to BIONs and ION@TEOS0.98. For magnetic resonance applications, ION@CMD and ION@TEOS3.91 showed comparatively high relaxation rates R₂ values. In magnetic particle imaging experiments ION@TEOS3.91 yielded the highest normalized signal to noise ratio values and in magnetic hyperthermia studies, ION@CMD and ION@TEOS0.98 showed similar specific loss power. These findings demonstrate the potential of coated IONs in nanomedicine and emphasize the importance of understanding the effect of coating material and thickness on their behavior and performance in the human body.

In vitro evaluation of iron oxide nanoparticle-induced thromboinflammatory response using a combined human whole blood and endothelial cell model

Iron oxide nanoparticles (IONPs) are widely used in diagnostic and therapeutic settings. Upon systemic administration, however, they are rapidly recognized by components of innate immunity, which limit their therapeutic capacity and can potentially lead to adverse side effects. IONPs were previously found to induce the inflammatory response in human whole blood, including activation of the complement system and increased secretion of cytokines. Here, we investigated the thromboinflammatory response of 10-30 nm IONPs in lepirudin anticoagulated whole blood in interplay with endothelial cells and evaluated the therapeutic effect of applying complement inhibitors to limit adverse effects related to thromboinflammation. We found that IONPs induced complement activation, primarily at the C3-level, in whole blood incubated for up to four hours at 37°C with and without human microvascular endothelial cells. Furthermore, IONPs mediated a strong thromboinflammatory response, as seen by the significantly increased release of 21 of the 27 analyzed cytokines (p<0.05). IONPs also significantly increased cell-activation markers of endothelial cells [ICAM-1 (p<0.0001), P/E-selectin (p<0.05)], monocytes, and granulocytes [CD11b (p<0.001)], and platelets [CD62P (p<0.05), CD63 (p<0.05), NAP-2 (p<0.01), PF4 (p<0.05)], and showed cytotoxic effects, as seen by increased LDH (p<0.001) and heme (p<0.0001) levels. We found that inflammation and endothelial cell activation were partly complement-dependent and inhibition of complement at the level of C3 by compstatin Cp40 significantly attenuated expression of ICAM-1 (p<0.01) and selectins (p<0.05). We show that complement activation plays an important role in the IONPs-induced thromboinflammatory response and that complement inhibition is promising in improving IONPs biocompatibility.

Thrombin Differentially Modulates the Acute Inflammatory Response to Escherichia coli and Staphylococcus aureus in Human Whole Blood

Thrombin plays a central role in thromboinflammatory responses, but its activity is blocked in the common ex vivo human whole blood models, making an ex vivo study of thrombin effects on thromboinflammatory responses unfeasible. In this study, we exploited the anticoagulant peptide Gly-Pro-Arg-Pro (GPRP) that blocks fibrin polymerization to study the effects of thrombin on acute inflammation in response to Escherichia coli and Staphylococcus aureus Human blood was anticoagulated with either GPRP or the thrombin inhibitor lepirudin and incubated with either E. coli or S. aureus for up to 4 h at 37°C. In GPRP-anticoagulated blood, there were spontaneous elevations in thrombin levels and platelet activation, which further increased in the presence of bacteria. Complement activation and the expression of activation markers on monocytes and granulocytes increased to the same extent in both blood models in response to bacteria. Most cytokines were not elevated in response to thrombin alone, but thrombin presence substantially and heterogeneously modulated several cytokines that increased in response to bacterial incubations. Bacterial-induced releases of IL-8, MIP-1α, and MIP-1β were potentiated in the thrombin-active GPRP model, whereas the levels of IP-10, TNF, IL-6, and IL-1β were elevated in the thrombin-inactive lepirudin model. Complement C5-blockade, combined with CD14 inhibition, reduced the overall cytokine release significantly, both in thrombin-active and thrombin-inactive models. Our data support that thrombin itself marginally induces leukocyte-dependent cytokine release in this isolated human whole blood but is a significant modulator of bacteria-induced inflammation by a differential effect on cytokine patterns.

The Relevance of Physico-Chemical Properties and Protein Corona for Evaluation of Nanoparticles Immunotoxicity-In Vitro Correlation Analysis on THP-1 Macrophages

Alongside physiochemical properties (PCP), it has been suggested that the protein corona of nanoparticles (NPs) plays a crucial role in the response of immune cells to NPs. However, due to the great variety of NPs, target cells, and exposure protocols, there is still no clear relationship between PCP, protein corona composition, and the immunotoxicity of NPs. In this study, we correlated PCP and the protein corona composition of NPs to the THP-1 macrophage response, focusing on selected toxicological endpoints: cell viability, reactive oxygen species (ROS), and cytokine secretion. We analyzed seven commonly used engineered NPs (SiO2, silver, and TiO2) and magnetic NPs. We show that with the exception of silver NPs, all of the tested TiO2 types and SiO2 exhibited moderate toxicities and a transient inflammatory response that was observed as an increase in ROS, IL-8, and/or IL-1β cytokine secretion. We observed a strong correlation between the size of the NPs in media and IL-1β secretion. The induction of IL-1β secretion was completely blunted in NLR family pyrin domain containing 3 (NLRP3) knockout THP-1 cells, indicating activation of the inflammasome. The correlations analysis also implicated the association of specific NP corona proteins with the induction of cytokine secretion. This study provides new insights toward a better understanding of the relationships between PCP, protein corona, and the inflammatory response of macrophages for different engineered NPs, to which we are exposed on a daily basis.

Combination of ovalbumin-coated iron oxide nanoparticles and poly(amidoamine) dendrimer-cisplatin nanocomplex for enhanced anticancer efficacy

Enhancement of drug efficacy is essential in cancer treatment. The immune stimulator ovalbumin (Ova)-coated citric acid (AC-)-stabilized iron oxide nanoparticles (AC-IO-Ova NPs) and enhanced permeability and retention (EPR)-based tumor targeted 4.5 generation poly(amidoamine) dendrimer(4.5GDP)-cisplatin (Cis-pt) nanocomplex (NC) (4.5GDP-Cis-pt NC) were used for enhanced anticancer efficiency. The formations of 4.5GDP-Cis-pt NC, AC-IO, and AC-IO-Ova NPs were examined via FTIR spectroscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The conjugation of Cis-pt with 4.5GDP was confirmed using carbon NMR spectroscopy. The tumor-specific 4.5GDP-Cis-pt NC provided 45%and 28% cumulative cisplatin release in 72 h at pH 6.5 and 7.4, respectively. A significant immune response with high TNF-α and IL-6 cytokine secretion was confirmed for the co-incubation of AC-IO-Ova with RAW 264.7 or HaCaT cells. AC-IO-Ova NPs were biocompatible with different cell lines, even at a high concentration (200 µg mL^-1). However, AC-IO-Ova NPs mixed with 4.5GDP-Cis-pt NC (Cis-pt at 15 µg mL^-1) significantly increased the cytotoxicity against the cancer cells in a dose-dependent manner with the increasing AC-IO-Ova NPs concentrations. The increased anticancer effects may be attributed to the generation of reactive oxygen species (ROS). Moreover, AC-IO-Ova NPs might assist the efficiency of anticancer cells, inducing an innate immune response via M1 macrophage polarization. We provide a novel synergistic chemoimmunotherapeutic strategy to enhance the anticancer efficacy of cisplatin via a chemotherapeutic agent 4.5GDP-Cis-pt NC and induce proinflammatory cytokines stimulating innate immunity through AC-IO-Ova NPs against tumors.

Application of the C3 inhibitor compstatin in a human whole blood model designed for complement research - 20 years of experience and future perspectives

The complex molecular and cellular biological systems that maintain host homeostasis undergo continuous crosstalk. Complement, a component of innate immunity, is one such system. Initially regarded as a system to protect the host from infection, complement has more recently been shown to have numerous other functions, including involvement in embryonic development, tissue modeling, and repair. Furthermore, the complement system plays a major role in the pathophysiology of many diseases. Through interactions with other plasma cascades, including hemostasis, complement activation leads to the broad host-protective response known as thromboinflammation. Most complement research has been limited to reductionistic models of purified components and cells and their interactions in vitro. However, to study the pathophysiology of complement-driven diseases, including the interaction between the complement system and other inflammatory systems, holistic models demonstrating only minimal interference with complement activity are needed. Here we describe two such models; whole blood anticoagulated with either the thrombin inhibitor lepirudin or the fibrin polymerization peptide blocker GPRP, both of which retain complement activity and preserve the ability of complement to be mutually reactive with other inflammatory systems. For instance, to examine the relative roles of C3 and C5 in complement activation, it is possible to compare the effects of the C3 inhibitor compstatin effects to those of inhibitors of C5 and C5aR1. We also discuss how complement is activated by both pathogen-associated molecular patterns, inducing infectious inflammation caused by organisms such as Gram-negative and Gram-positive bacteria, and by sterile damage-associated molecular patterns, including cholesterol crystals and artificial materials used in clinical medicine. When C3 is inhibited, it is important to determine the mechanism by which inflammation is attenuated, i.e., whether the attenuation derives directly from C3 activation products or via downstream activation of C5, since the mechanism involved may determine the appropriate choice of inhibitor under various conditions. With some exceptions, most inflammatory responses are dependent on C5 and C5aR1; one exception is venous air embolism, in which air bubbles enter the blood circulation and trigger a mainly C3-dependent thromboembolism, with the formation of an active C3 convertase, without a corresponding C5 activation. Under such conditions, an inhibitor of C3 is needed to attenuate the inflammation. Our holistic blood models will be useful for further studies of the inhibition of any complement target, not just C3 or C5. The focus here will be on targeting the critical complement component, activation product, or receptor that is important for the pathophysiology in a variety of disease conditions.

Albumin covering maintains endothelial function upon magnetic iron oxide nanoparticles intravenous injection in rats

Magnetic iron oxide nanoparticles (IONP) present the promising instrument for broad-spectrum of clinical applications, for example, targeted drug delivery. Reactivity of nanoparticles depends on their surface area and material. In the blood plasma IONP are getting covered with an albumin crown, so it was decided to test this shell for biocompatibility. Male Wistar rats were anesthetized and underwent laparotomy. Abdominal aorta was connected to external hemodynamic loop with regulated blood flow. Hind body quarter got step-like blood flow changing from 30 to 150 mmHg and back. This was followed with i.v. injection of IONP, albumin solution or albumin-covered IONP and consequent similar flow changes. Central hemodynamics-heart rate and mean arterial pressure were registered throughout the experiment and no significant changes in these parameters were observed. Hind paw microcirculation level had the same dynamic in all groups under changing blood flow conditions. At the end, venous blood was collected for endothelin-1 and NO evaluation that showed similar changes and no endothelial damage. Mesenteric arteries and femoral artery reactivity were evaluated with wire myography. Mesenteric arteries had the most relaxing function preservation after albumin-covered IONP injection. Given data reveal advantage of albumin-coated IONP so this can be used for further investigations as a vascular-safe vehicle.

In vivo Cell Tracking Using Non-invasive Imaging of Iron Oxide-Based Particles with Particular Relevance for Stem Cell-Based Treatments of Neurological and Cardiac Disease

Stem cell-based therapeutics is a rapidly developing field associated with a number of clinical challenges. One such challenge lies in the implementation of methods to track stem cells and stem cell-derived cells in experimental animal models and in the living patient. Here, we provide an overview of cell tracking in the context of cardiac and neurological disease, focusing on the use of iron oxide-based particles (IOPs) visualized in vivo using magnetic resonance imaging (MRI). We discuss the types of IOPs available for such tracking, their advantages and limitations, approaches for labeling cells with IOPs, biological interactions and effects of IOPs at the molecular and cellular levels, and MRI-based and associated approaches for in vivo and histological visualization. We conclude with reviews of the literature on IOP-based cell tracking in cardiac and neurological disease, covering both preclinical and clinical studies.

Complement Inhibitors Block Complement C3 Opsonization and Improve Targeting Selectivity of Nanoparticles in Blood

Complement is one of the critical branches of innate immunity that determines the recognition of engineered nanoparticles by immune cells. Antibody-targeted iron oxide nanoparticles are a popular platform for magnetic separations, in vitro diagnostics, and molecular imaging. We used 60 nm cross-linked iron oxide nanoworms (CLIO NWs) modified with antibodies against Her2/neu and EpCAM, which are common markers of blood-borne cancer cells, to understand the role of complement in the selectivity of targeting of tumor cells in whole blood. CLIO NWs showed highly efficient targeting and magnetic isolation of tumor cells spiked in lepirudin-anticoagulated blood, but specificity was low due to high uptake by neutrophils, monocytes, and lymphocytes. Complement C3 opsonization in plasma was predominantly via the alternative pathway regardless of the presence of antibody, PEG, or fluorescent tag, but was higher for antibody-conjugated CLIO NWs. Addition of various soluble inhibitors of complement convertase (compstatin, soluble CD35, and soluble CD55) to whole human blood blocked up to 99% of the uptake of targeted CLIO NWs by leukocytes, which resulted in a more selective magnetic isolation of tumor cells. Using well-characterized nanomaterials, we demonstrate here that complement therapeutics can be used to improve targeting selectivity.

A novel Approach for Non-Invasive Lung Imaging and Targeting Lung Immune Cells

Despite developments in pulmonary radiotherapy, radiation-induced lung toxicity remains a problem. More sensitive lung imaging able to increase the accuracy of diagnosis and radiotherapy may help reduce this problem. Super-paramagnetic iron oxide nanoparticles are used in imaging, but without further modification can cause unwanted toxicity and inflammation. Complex carbohydrate and polymer-based coatings have been used, but simpler compounds may provide additional benefits. Herein, we designed and generated super-paramagnetic iron oxide nanoparticles coated with the neutral natural dietary amino acid glycine (GSPIONs), to support non-invasive lung imaging and determined particle biodistribution, as well as understanding the impact of the interaction of these nanoparticles with lung immune cells. These GSPIONs were characterized to be crystalline, colloidally stable, with a size of 12 ± 5 nm and a hydrodynamic diameter of 84.19 ± 18 nm. Carbon, Hydrogen, Nitrogen (CHN) elemental analysis estimated approximately 20.2 × 10³ glycine molecules present per nanoparticle. We demonstrated that it is possible to determine the biodistribution of the GSPIONs in the lung using three-dimensional (3D) ultra-short echo time magnetic resonance imaging. The GSPIONs were found to be taken up selectively by alveolar macrophages and neutrophils in the lung. In addition, the GSPIONs did not cause changes to airway resistance or induce inflammatory cytokines. Alveolar macrophages and neutrophils are critical regulators of pulmonary inflammatory diseases, including allergies, infections, asthma and chronic obstructive pulmonary disease (COPD). Therefore, pulmonary Magnetic Resonance (MR) imaging and preferential targeting of these lung resident cells by our nanoparticles offer precise imaging tools, which can be utilized to develop precision targeted radiotherapy as well as diagnostic tools for lung cancer, thereby having the potential to reduce the pulmonary complications of radiation.

Effects of Iron Oxide Nanoparticles (γ-Fe2O3) on Liver, Lung and Brain Proteomes following Sub-Acute Intranasal Exposure: A New Toxicological Assessment in Rat Model Using iTRAQ-Based Quantitative Proteomics

Iron Oxide Nanoparticles (IONPs) present unique properties making them one of the most used NPs in the biomedical field. Nevertheless, for many years, growing production and use of IONPs are associated with risks that can affect human and the environment. Thus, it is essential to study the effects of these nanoparticles to better understand their mechanism of action and the molecular perturbations induced in the organism. In the present study, we investigated the toxicological effects of IONPs (γ-Fe2O3) on liver, lung and brain proteomes in Wistar rats. Exposed rats received IONP solution during 7 consecutive days by intranasal instillation at a dose of 10 mg/kg body weight. An iTRAQ-based quantitative proteomics was used to study proteomic variations at the level of the three organs. Using this proteomic approach, we identified 1565; 1135 and 1161 proteins respectively in the brain, liver and lung. Amon them, we quantified 1541; 1125 and 1128 proteins respectively in the brain, liver and lung. Several proteins were dysregulated comparing treated samples to controls, particularly, proteins involved in cytoskeleton remodeling, cellular metabolism, immune system stimulation, inflammation process, response to oxidative stress, angiogenesis, and neurodegenerative diseases.

Towards a nanoparticle-based prophylactic for maternal autoantibody-related autism

Recently, the causative agents of Maternal Autoantibody-Related (MAR) autism, pathological autoantibodies and their epitopic targets (e.g. lactate dehydrogenase B [LDH B] peptide), have been identified. Herein, we report on the development of Systems for Nanoparticle-based Autoantibody Reception and Entrapment (SNAREs), which we hypothesized could scavenge disease-propagating MAR autoantibodies from the maternal blood. To demonstrate this functionality, we synthesized 15 nm dextran iron oxide nanoparticles surface-modified with citric acid, methoxy PEG(10 kDa) amine, and LDH B peptide (33.8 μg peptide/cm2). In vitro, we demonstrated significantly lower macrophage uptake for SNAREs compared to control NPs. The hallmark result of this study was the efficacy of the SNAREs to remove 90% of LDH B autoantibody from patient-derived serum. Further, in vitro cytotoxicity testing and a maximal tolerated dose study in mice demonstrated the safety of the SNARE formulation. This work establishes the feasibility of SNAREs as the first-ever prophylactic against MAR autism.

Submicron-Sized Nanocomposite Magnetic-Sensitive Carriers: Controllable Organ Distribution and Biological Effects

Although new drug delivery systems have been intensely developed in the past decade, no significant increase in the efficiency of drug delivery by nanostructure carriers has been achieved. The reasons are the lack of information about acute toxicity, the influence of the submicron size of the carrier and difficulties with the study of biodistribution in vivo. Here we propose, for the first time in vivo, new nanocomposite submicron carriers made of bovine serum albumin (BSA) and tannic acid (TA) and containing magnetite nanoparticles with sufficient content for navigation in a magnetic field gradient on mice. We examined the efficacy of these submicron carriers as a delivery vehicle in combination with magnetite nanoparticles which were systemically administered intravenously. In addition, the systemic toxicity of this carrier for intravenous administration was explicitly studied. The results showed that (BSA/TA) carriers in the given doses were hemocompatible and didn’t cause any adverse effect on the respiratory system, kidney or liver functions. A combination of gradient-magnetic-field controllable biodistribution of submicron carriers with fluorescence tomography/MRI imaging in vivo provides a new opportunity to improve drug delivery efficiency.

Plasma protein adsorption on Fe3O4-PEG nanoparticles activates the complement system and induces an inflammatory response

BACKGROUND

Understanding of iron oxide nanoparticles (IONP) interaction with the body milieu is crucial to guarantee their efficiency and biocompatibility in nanomedicine. Polymer coating to IONP, with polyethyleneglycol (PEG) and polyvinylpyrrolidone (PVP), is an accepted strategy to prevent toxicity and excessive protein binding.

AIM

The aim of this study was to investigate the feature of IONP adsorption of complement proteins, their activation and consequent inflammatory response as a strategy to further elucidate their biocompatibility.

METHODS

Three types of IONP with different surface characteristics were used: bare (IONP-bare), coated with PVP (IONP-PVP) and PEG-coated (IONP-PEG). IONPs were incubated with human plasma and adsorbed proteins were identified. BALB/c mice were intravenously exposed to IONP to evaluate complement activation and proinflammatory response.

RESULTS

Protein corona fingerprinting showed that PEG surface around IONP promoted a selective adsorption of complement recognition molecules which would be responsible for the complement system activation. Furthermore, IONP-PEG activated in vitro, the complement system and induced a substantial increment of C3a and C4a anaphylatoxins while IONP-bare and IONP-PVP did not. In vivo IONP-PEG induced an increment in complement activation markers (C5a and C5b-9), and proinflammatory cytokines (IL-1β, IL-6, TNF-α).

CONCLUSION

The engineering of nanoparticles must incorporate the association between complement proteins and nanomedicines, which will regulate the immunostimulatory effects through a selective adsorption of plasma proteins and will enable a safer application of IONP in human therapy.

Impact of Morphology on Iron Oxide Nanoparticles-Induced Inflammasome Activation in Macrophages

Inflammasomes, a critical component of the innate immune system, mediate much of the inflammatory response manifested by engineered nanomaterials. Iron oxide nanoparticles (IONPs), a type of nanoparticles that have gained widespread acceptance in preclinical and clinical settings, are known to induce inflammasome activation, but how morphology affects the inflammasome-activating property of IONPs has not been addressed. In this report, we have synthesized four morphologically distinct IONPs having the same aspect ratio and similar surface charge, thus offering an ideal system to assess the impact of morphology on nanoparticle-elicited biological effect. We show that morphology was a critical determinant for IONP-induced IL-1β release and pyroptosis, with the octapod and plate IONPs exhibiting significantly higher activity than the cube and sphere IONPs. The inflammasome-activating capacity of different IONPs correlated with their respective ability to elicit intracellular reactive oxygen species generation, lysosomal damage, and potassium efflux, three well-known mechanisms for nanoparticle-facilitated inflammasome activation. Furthermore, we demonstrate that the release of IL-1β induced by IONPs was only partly mediated by NLRP3, suggesting that inflammasomes other than NLRP3 are also involved in IONP-induced inflammasome activation. Our results may have implications for designing safer nanoparticles for in vivo applications.

Iron oxide nanoparticles enhance Toll-like receptor-induced cytokines in a particle size- and actin-dependent manner in human blood

Aim: To assess the effects of different-sized iron oxide nanoparticles (IONPs) on inflammatory responses in human whole blood. Materials & methods: Human whole blood with and without 10 and 30 nm IONPs was incubated with Toll-like receptor (TLR) ligands. Cytokine levels, complement activation, reactive oxygen species and viability were determined. Results: The 10 nm IONPs enhanced the TLR2/6, TLR4 and partly TLR8-mediated cytokine production, whereas the 30 nm IONPs partly enhanced TLR2/6 and decreased TLR8-mediated cytokine production. Particle-mediated enhancement of TLR4-induced cytokines could not be explained by complement activation, but was dependent on TLR4/MD2 and CD14, as well as actin polymerization. Conclusion: The IONPs differentially affected the TLR ligand-induced cytokines, which has important implications for biomedical applications of IONPs.

Nanoparticle effect on neutrophil produced myeloperoxidase

Nanoparticles affect the immune system as they may interact directly with immune cells and activate them. However, it is possible that nanoparticles also interact with released cytokines and immunologically active enzymes. To test this hypothesis, the activity of myeloperoxidase released from activated neutrophils was measured in the presence of nanoparticles with different chemistry and size. In high concentrations of nanoparticles, myeloperoxidase activity is decreased whereas in low concentrations of nanoparticles the activity is increased. The effect of the nanoparticles on myeloperoxidase is dependent on the total protein concentration as low concentrations of bovine serum albumin together with nanoparticles further increase the myeloperoxidase activity. The results herein show that nanoparticles affect the immune response not only at the cellular level but also on released immune effectors. In particular, they show that the nanoparticle effect on myeloperoxidase activity in the neutrophil degranulation environment is the result of an intricate interplay between the enzyme and protein concentrations in the environment and the available surface area on the nanoparticle.