Nanomaterial Exposure Induced Neutrophil Extracellular Traps: A New Target in Inflammation and Innate Immunity

Application of Nanomaterials Targeting Immune Cells in the Treatment of Chronic Inflammation

Chronic inflammation is a common characteristic of all kinds of diseases, including autoimmune diseases, metabolic diseases, and tumors. It is distinguished by the presence of low concentrations of inflammatory factors stimulating the body for an extended period, resulting in a persistent state of infection. This condition is manifested by the aggregation and infiltration of mononuclear cells, lymphocytes, and other immune cells, leading to tissue hyperplasia and lesions. Although various anti-inflammatory medications, including glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs), have shown strong therapeutic effects, they lack specificity and targeting ability, and require high dosages, which can lead to severe adverse reactions. Nanoparticle drug delivery mechanisms possess the capacity to minimize the effect on healthy cells or tissues due to their targeting capabilities and sustained drug release properties. However, most nanosystems can only target the inflammatory sites rather than specific types of immune cells, leaving room for further improvement in the therapeutic effects of nanomaterials. This article reviews the current research progress on the role of diverse immune cells in inflammation, focusing on the functions of neutrophils and macrophages during inflammation. It provides an overview of the domestic and international applications of nanomaterials in targeted therapy for inflammation, aiming to establish a conceptual foundation for the utilization of nanomaterials targeting immune cells in the treatment of chronic inflammation and offer new perspectives for the avoidance and management of inflammation.

The Potential of Human Pulmonary Mesenchymal Stem Cells as Vectors for Radiosensitizing Metallic Nanoparticles: An In Vitro Study

BACKGROUND/OBJECTIVES

Metallic nanoparticles (NPs) exhibit interesting radiosensitizing effects, and finding a way to accurately deliver them appears to be crucial. Due to their tumor tropism, mesenchymal stem cells (MSCs) represent a strategic approach. Therefore, we aimed to evaluate the impact of core-shell Fe3O4@Au NPs on the functionality of human pulmonary MSCs (HPMSCs).

METHODS/RESULTS

The results showed that 100 µg/mL Fe3O4@Au NPs, accumulated in HPMSCs (revealed by Prussian blue staining), did not alter cell viability as assessed by cell counting, MTT, and LDH assays. However, caspase 9 and Bcl2 gene expression, evaluated by RT-qPCR, was regulated 72 h after exposure to the NPs. Moreover, the NPs also decreased proinflammatory cytokine/chemokine secretions, except for CXCL8 (ELISA). These modulations were associated with the downregulation of AMPK gene expression at 24 h. In contrast, the NPs did not modulate VEGF, PI3K, or PDGF gene expression. Nevertheless, a decrease in VEGF secretion was observed after 24 h of exposure to the NPs. Interestingly, the Fe3O4@Au NPs did not modulate Nrf2 gene expression, but they did regulate the expression of the genes encoding Nox4 and HMOX-1. Additionally, the NPs increased ROS production, suggesting a redox imbalance.

CONCLUSIONS

Finally, the Fe3O4@Au NPs did not affect the HPMSCs' viability or proangiogenic/tumorigenic markers. These findings are encouraging for investigating the effects of Fe3O4@Au NPs delivered by HPMSCs to tumor sites in combination with radiation.

Neutrophils and extracellular traps in crystal-associated diseases

Crystalline material can cause a multitude of acute and chronic inflammatory diseases, such as gouty arthritis, silicosis, kidney disease, and atherosclerosis. Crystals of various types are thought to cause similar inflammatory responses, including the release of proinflammatory mediators and formation of neutrophil extracellular traps (NETs), processes that further promote necroinflammation and tissue damage. It has become apparent that the intensity of inflammation and the related mechanisms of NET formation and neutrophil death in crystal-associated diseases can vary depending on the crystal type, amount, and site of deposition. This review details new mechanistic insights into crystal biology, highlights the differential effects of various crystals on neutrophils and extracellular trap (ET) formation, and discusses treatment strategies and potential future approaches for crystal-associated disorders.

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.

Neutrophil as a Carrier for Cancer Nanotherapeutics: A Comparative Study of Liposome, PLGA, and Magnetic Nanoparticles Delivery to Tumors

Insufficient drug accumulation in tumors is still a major concern for using cancer nanotherapeutics. Here, the neutrophil-based delivery of three nanoparticle types-liposomes, PLGA, and magnetite nanoparticles-was assessed both in vitro and in vivo. Confocal microscopy and a flow cytometry analysis demonstrated that all the studied nanoparticles interacted with neutrophils from the peripheral blood of mice with 4T1 mammary adenocarcinoma without a significant impact on neutrophil viability or activation state. Intravital microscopy of the tumor microenvironment showed that the neutrophils did not engulf the liposomes after intravenous administration, but facilitated nanoparticle extravasation in tumors through micro- and macroleakages. PLGA accumulated along the vessel walls in the form of local clusters. Later, PLGA nanoparticle-loaded neutrophils were found to cross the vascular barrier and migrate towards the tumor core. The magnetite nanoparticles extravasated in tumors both via spontaneous macroleakages and on neutrophils. Overall, the specific type of nanoparticles largely determined their behavior in blood vessels and their neutrophil-mediated delivery to the tumor. Since neutrophils are the first to migrate to the site of inflammation, they can increase nanodrug delivery effectiveness for nanomedicine application.

Inflammatory Mechanisms in a Neurovascular Disease: Cerebral Cavernous Malformation

Cerebral cavernous malformation (CCM) is a common cerebrovascular malformation causing intracranial hemorrhage, seizures, and focal neurologic deficits. A unique CCM lesional inflammatory microenvironment has been shown to influence the clinical course of the disease. This review addresses the inflammatory cell infiltrate in the CCM lesion and the role of a defined antigen-driven immune response in pathogenicity. We summarize immune mechanisms associated with the loss of the CCM gene and disease progression, including the potential role of immunothrombosis. We also review evidence of circulating inflammatory biomarkers associated with CCM disease and its clinical activity. We articulate future directions for this research, including the role of individual cell type contributions to the immune response in CCM, single cell transcriptomics of inflammatory cells, biomarker development, and therapeutic implications. The concepts are applicable for developing diagnostic and treatment strategies for CCM and for studying other neurovascular diseases.

The role of thyroid hormone in the renal immune microenvironment

Thyroid hormones are essential for proper kidney growth and development. The kidney is not only the organ of thyroid hormone metabolism but also the target organ of thyroid hormone. Kidney disease is a common type of kidney damage, mainly including different types of acute kidney injury, chronic kidney disease, diabetic nephropathy, lupus nephritis, and renal cell carcinoma. The kidney is often damaged by an immune response directed against its antigens or a systemic immune response. A variety of immune cells in the innate and adaptive immune systems, including neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes, is essential for maintaining immune homeostasis and preventing autoimmune kidney disease. Recent studies have found that thyroid hormone plays an indispensable role in the immune microenvironment of various kidney diseases. Thyroid hormones regulate the activity of neutrophils, and dendritic cells express triiodothyronine receptors. Compared to hypothyroidism, hyperthyroidism has a greater effect on neutrophils. Furthermore, in adaptive immune systems, thyroid hormone may activate T lymphocytes through several underlying mechanisms, such as mediating NF-κB, protein kinase C signalling pathways, and β-adrenergic receptors, leading to increased T lymphocyte activation. The present review discusses the effects of thyroid hormone metabolism regulation in the immune microenvironment on the function of various immune cells, especially neutrophils, macrophages, dendritic cells, T lymphocytes, and B lymphocytes. Although there are not enough data at this stage to conclude the clinical relevance of these findings, thyroid hormone metabolism may influence autoimmune kidney disease by regulating the renal immune microenvironment.

The potential impact of nanomedicine on COVID-19-induced thrombosis

Extensive reports of pulmonary embolisms, ischaemic stroke and myocardial infarctions caused by coronavirus disease 2019 (COVID-19), as well as a significantly increased long-term risk of cardiovascular diseases in COVID-19 survivors, have highlighted severe deficiencies in our understanding of thromboinflammation and the need for new therapeutic options. Due to the complexity of the immunothrombosis pathophysiology, the efficacy of treatment with conventional anti-thrombotic medication is questioned. Thrombolytics do appear efficacious, but are hindered by severe bleeding risks, limiting their use. Nanomedicine can have profound impact in this context, protecting delicate (bio)pharmaceuticals from degradation en route and enabling delivery in a targeted and on demand manner. We provide an overview of the most promising nanocarrier systems and design strategies that may be adapted to develop nanomedicine for COVID-19-induced thromboinflammation, including dual-therapeutic approaches with antiviral and immunosuppressants. Resultant targeted and side-effect-free treatment may aid greatly in the fight against the ongoing COVID-19 pandemic.

Emerging applications of nanotechnology in context to immunology: A comprehensive review

Numerous benefits of nanotechnology are available in many scientific domains. In this sense, nanoparticles serve as the fundamental foundation of nanotechnology. Recent developments in nanotechnology have demonstrated that nanoparticles have enormous promise for use in almost every field of life sciences. Nanoscience and nanotechnology use the distinctive characteristics of tiny nanoparticles (NPs) for various purposes in electronics, fabrics, cosmetics, biopharmaceutical industries, and medicines. The exclusive physical, chemical, and biological characteristics of nanoparticles prompt different immune responses in the body. Nanoparticles are believed to have strong potential for the development of advanced adjuvants, cytokines, vaccines, drugs, immunotherapies, and theranostic applications for the treatment of targeted bacterial, fungal, viral, and allergic diseases and removal of the tumor with minimal toxicity as compared to macro and microstructures. This review highlights the medical and non-medical applications with a detailed discussion on enhanced and targeted natural and acquired immunity against pathogens provoked by nanoparticles. The immunological aspects of the nanotechnology field are beyond the scope of this Review. However, we provide updated data that will explore novel theragnostic immunological applications of nanotechnology for better and immediate treatment.

PEGylation of Metal Oxide Nanoparticles Modulates Neutrophil Extracellular Trap Formation

Novel metal oxide nanoparticle (NP) contrast agents may offer safety and functionality advantages over conventional gadolinium-based contrast agents (GBCAs) for cancer diagnosis by magnetic resonance imaging. However, little is known about the behavior of metal oxide NPs, or of their effect, upon coming into contact with the innate immune system. As neutrophils are the body's first line of defense, we sought to understand how manganese oxide and iron oxide NPs impact leukocyte functionality. Specifically, we evaluated whether contrast agents caused neutrophils to release web-like fibers of DNA known as neutrophil extracellular traps (NETs), which are known to enhance metastasis and thrombosis in cancer patients. Murine neutrophils were treated with GBCA, bare manganese oxide or iron oxide NPs, or poly(lactic-co-glycolic acid) (PLGA)-coated metal oxide NPs with different incorporated levels of poly(ethylene glycol) (PEG). Manganese oxide NPs elicited the highest NETosis rates and had enhanced neutrophil uptake properties compared to iron oxide NPs. Interestingly, NPs with low levels of PEGylation produced more NETs than those with higher PEGylation. Despite generating a low rate of NETosis, GBCA altered neutrophil cytokine expression more than NP treatments. This study is the first to investigate whether manganese oxide NPs and GBCAs modulate NETosis and reveals that contrast agents may have unintended off-target effects which warrant further investigation.

Size-dependent impact of polystyrene microplastics on the toxicity of cadmium through altering neutrophil expression and metabolic regulation in zebrafish larvae

Insufficient evidence exists regarding the visible physiological toxic endpoints of MPs exposures on zebrafish larvae due to their small sizes. Herein, the impacts of micro-polystyrene particles (μ-PS) and 100 nm polystyrene particles (n-PS) on the toxicity of cadmium (Cd) through altering neutrophil expressions were identified and quantified in the transgenic zebrafish (Danio rerio) larvae Tg(lyz:DsRed2), and the effects were size-dependent. When exposed together with μ-PS, the amount of neutrophils in Cd treated zebrafish larvae decreased by 25.56% through reducing Cd content in the larvae. By contrast, although n-PS exposure caused lower Cd content in the larvae, the expression of neutrophils under their combined exposure remained high. The mechanism of immune toxicity was analyzed based on the results of metabonomics. n-PS induced high oxidative stress in the larvae, which promoted taurine metabolism and unsaturated fatty biosynthesis in n-PS + Cd treatment. This observation was accordance with the significant inhibition of the activities of superoxide dismutase and catalase enzymes detected in their combined treatment. Moreover, n-PS promoted the metabolic pathways of catabolic processes, amino acid metabolism, purine metabolism, and steroid hormone biosynthesis in Cd treated zebrafish larvae. Nanoplasctis widely coexist with other pollutants in the environment at relatively low concentrations. We conclude that more bio-markers of immune impact should be explored to identify their toxicological mechanisms and mitigate the effects on the environment.

Targeting and exploitation of tumor-associated neutrophils to enhance immunotherapy and drug delivery for cancer treatment

Neutrophils, the most abundant leukocytes in human blood, are essential fighter immune cells against microbial infection. Based on the finding that neutrophils can either restrict or promote cancer progression, tumor-associated neutrophils (TAN) are classified into anti-tumor N1 and pro-tumor N2 subsets. One of the major mechanisms underlying the tumor-promoting function of N2-TANs is suppression of adaptive immune cells, in particular, cytotoxic T lymphocytes. Currently, no established methodologies are available that can unequivocally distinguish immunosuppressive TANs and granulocytic/polymorphonuclear myeloid-derived suppressor cells (G/PMN-MDSC). In view of the critical role of PMN-MDSCs in immune evasion and resistance to cancer immunotherapy, as established from data obtained with diverse cancer models, therapeutic strategies targeting these cells have been actively developed to enhance the efficacy of immunotherapy. Here, we have reviewed the available literature on strategies targeting PMN-MDSCs and summarized the findings into four categories: (1) depletion of existing PMN-MDSCs, (2) blockade of the development of PMN-MDSCs, (3) blockade of PMN-MDSC recruitment, (4) inhibition of immunosuppressive function. Owing to their high mobility to inflamed organs and ability to trespass the blood-brain barrier, neutrophils are outstanding candidate carriers in nanoparticle-based therapies. Another attractive application of neutrophils in cancer therapy is the use of neutrophil membrane-derived nanovesicles as a surrogate of extracellular vesicles for more efficient and scalable drug delivery. In the second part of the review, we have highlighted recent advances in the field of neutrophil-based cancer drug delivery. Overall, we believe that neutrophil-based therapeutics are a rapidly growing area of cancer therapy with significant potential benefits.

Immunologically Inert Nanostructures as Selective Therapeutic Tools in Inflammatory Diseases

The current therapies based on immunosuppressant or new biologic drugs often show some limitations in term of efficacy and applicability, mainly because of their inadequate targeting and of unwanted adverse reactions they generate. To overcome these inherent problems, in the last decades, innovative nanocarriers have been developed to encapsulate active molecules and offer novel promising strategies to efficiently modulate the immune system. This review provides an overview of how it is possible, exploiting the favorable features of nanocarriers, especially with regard to their immunogenicity, to improve the bioavailability of novel drugs that selectively target immune cells in the context of autoimmune disorders and inflammatory diseases. A focus is made on nanoparticles that selectively target neutrophils in inflammatory pathologies.

Biocompatibility of nanomaterials and their immunological properties

Nanomaterials (NMs) have revolutionized multiple aspects of medicine by enabling novel sensing, diagnostic, and therapeutic approaches. Advancements in processing and fabrication have also allowed significant expansion in the applications of the major classes of NMs based on polymer, metal/metal oxide, carbon, liposome, or multi-scale macro-nano bulk materials. Concomitantly, concerns regarding the nanotoxicity and overall biocompatibility of NMs have been raised. These involve putative negative effects on both patients and those subjected to occupational exposure during manufacturing. In this review, we describe the current state of testing of NMs including those that are in clinical use, in clinical trials, or under development. We also discuss the cellular and molecular interactions that dictate their toxicity and biocompatibility. Specifically, we focus on the reciprocal interactions between NMs and host proteins, lipids, and sugars and how these induce responses in immune and other cell types leading to topical and/or systemic effects.

Multiple Origins of Extracellular DNA Traps

Extracellular DNA traps (ETs) are evolutionarily conserved antimicrobial mechanisms present in protozoa, plants, and animals. In this review, we compare their similarities in species of different taxa, and put forward the hypothesis that ETs have multiple origins. Our results are consistent with a process of evolutionary convergence in multicellular organisms through the application of a congruency test. Furthermore, we discuss why multicellularity is related to the presence of a mechanism initiating the formation of ETs.

Perspective: The Lung, Particles, Fibers, Nanomaterials, and Autoimmunity

Studies have shown that a wide range of factors including drugs, chemicals, microbes, and other environmental agents can induce pre-clinical autoimmunity. However, only a few have been confidently linked to autoimmune diseases. Among these are exposures to inhaled particulates that are known to be associated with autoimmune diseases such as lupus and rheumatoid arthritis. In this article, the potential of particle, fiber, and nanomaterial exposures to induce autoimmunity is discussed. It is hypothesized that inhalation of particulate material known to be associated with human autoimmune diseases, such as cigarette smoke and crystalline silica, results in a complex interplay of a number of pathological processes, including, toxicity, oxidative stress, cell and tissue damage, chronic inflammation, post-translational modification of self-antigens, and the formation of lymphoid follicles that provide a milieu for the accumulation of autoreactive B and T cells necessary for the development and persistence of autoimmune responses, leading to disease. Although experimental studies show nanomaterials are capable of inducing several of the above features, there is no evidence that this matures to autoimmune disease. The procession of events hypothesized here provides a foundation from which to pursue experimental studies to determine the potential of other environmental exposures to induce autoimmunity and autoimmune disease.

Neutrophil activation by nanomaterials in vitro: comparing strengths and limitations of primary human cells with those of an immortalized (HL-60) cell line

Assessment of nanomaterial (NM) induced inflammatory responses has largely relied on rodent testing via measurement of leukocyte accumulation in target organs. Despite observations that NMs activate neutrophil driven inflammatory responses in vivo, a limited number of studies have investigated neutrophil responses to NMs in vitro. We compared responses between the human neutrophil-like HL-60 cell line and human primary neutrophils following exposure to silver (Ag), zinc oxide (ZnO), copper oxide (CuO) and titanium dioxide (TiO₂) NMs. NM cytotoxicity and neutrophil activation were assessed by measuring cellular metabolic activity, cytokine production, respiratory burst, and release of neutrophil extracellular traps. We observed a similar pattern of response between HL-60 cells and primary neutrophils, however we report that some neutrophil functions are compromised in the cell line. Ag NMs were consistently observed to stimulate neutrophil activation, with CuO NMs inducing similar though weaker responses. TiO₂ NMs did not induce a neutrophil response in either cell type. Interestingly, ZnO NMs readily induced activation of HL-60 cells but did not appear to activate primary cells. Our findings are relevant to the development of a tiered testing strategy for NM hazard assessment which promotes the use of non-rodent models. Whilst we acknowledge that HL-60 cells may not be a perfect substitute for primary cells and require further investigation regarding their ability to predict neutrophil activation, we recommend their use for initial screening of NM-induced inflammation. Primary human neutrophils can then be used for more focused assessments of neutrophil activation before progressing to in vivo models where necessary.

Fast and Robust Proteome Screening Platform Identifies Neutrophil Extracellular Trap Formation in the Lung in Response to Cobalt Ferrite Nanoparticles

Despite broad application of magnetic nanoparticles in biomedicine and electronics, only a few in vivo studies on biocompatibility are available. In this study, toxicity of magnetic metal oxide nanoparticles on the respiratory system was examined in vivo by single intratracheal instillation in mice. Bronchoalveolar lavage fluid (BALF) samples were collected for proteome analyses by LC-MS/MS, testing Fe₃O₄ nanoparticles doped with increasing amounts of cobalt (Fe₃O₄, CoFe₂O₄ with an iron to cobalt ratio 5:1, 3:1, 1:3, Co₃O₄) at two doses (54 μg, 162 μg per animal) and two time points (day 1 and 3 days postinstillation). In discovery phase, in-depth proteome profiling of a few representative samples allowed for comprehensive pathway analyses. Clustering of the 681 differentially expressed proteins (FDR < 0.05) revealed general as well as metal oxide specific responses with an overall strong induction of innate immunity and activation of the complement system. The highest expression increase could be found for a cluster of 39 proteins, which displayed strong dose-dependency to iron oxide and can be attributed to neutrophil extracellular trap (NET) formation. In-depth proteome analysis expanded the knowledge of in vivo NET formation. During screening, all BALF samples of the study (n = 166) were measured label-free as single-injections after a short gradient (21 min) LC separation using the Evosep One system, validating the findings from the discovery and defining protein signatures which enable discrimination of lung inflammation. We demonstrate a proteomics-based toxicity screening with high sample throughput easily transferrable to other nanoparticle types. Data are available via ProteomeXchange with identifier PXD016148.

Nanoparticles for hematologic diseases detection and treatment

Nanotechnology, as an interdisciplinary science, combines engineering, physics, material sciences, and chemistry with the biomedicine knowhow, trying the management of a wide range of diseases. Nanoparticle-based devices holding tumor imaging, targeting and therapy capabilities are formerly under study. Since conventional hematological therapies are sometimes defined by reduced selectivity, low therapeutic efficacy and many side effects, in this review we discuss the potential advantages of the NPs' use in alternative/combined strategies. In the introduction the basic notion of nanomedicine and nanoparticles' classification are described, while in the main text nanodiagnostics, nanotherapeutics and theranostics solutions coming out from the use of a wide-ranging NPs availability are listed and discussed.