Promoting effects of nanoparticles/materials on sensitive lung inflammatory diseases

Current Considerations and Practical Solutions for Overcoming Nanoparticle Interference with LAL Assays and Minimizing Endotoxin Contamination

Monitoring endotoxin contamination in drugs and medical devices is required to avoid pyrogenic responses and septic shock in patients receiving these products. Endotoxin contamination of engineered nanomaterials and nanotechnology-based medical products represents a significant translational hurdle. Nanoparticles often interfere with an in vitro limulus amebocyte lysate (LAL) assay commonly used in the pharmaceutical industry for the detection and quantification of endotoxin. Such interference challenges the preclinical development of nanotechnology-formulated drugs and medical devices containing engineered nanomaterials. Protocols for the analysis of nanoparticles using LAL assays have been reported before. Here, we discuss considerations for selecting an LAL format and describe a few experimental approaches for overcoming nanoparticle interference with the LAL assays to obtain more accurate estimations of endotoxin contamination in nanotechnology-based products. The discussed approaches do not solve all types of nanoparticle interference with the LAL assays but could be used as a starting point to address the problem. This chapter also describes approaches to prevent endotoxin contamination in nanotechnology-formulated products.

Vaping and Lung Inflammation and Injury

The use of electronic (e)-cigarettes was initially considered a beneficial solution to conventional cigarette smoking cessation. However, paradoxically, e-cigarette use is rapidly growing among nonsmokers, including youth and young adults. In 2019, this rapid growth resulted in an epidemic of hospitalizations and deaths of e-cigarette users (vapers) due to acute lung injury; this novel disease was termed e-cigarette or vaping use-associated lung injury (EVALI). Pathophysiologic mechanisms of EVALI likely involve cytotoxicity and neutrophilic inflammation caused by inhaled chemicals, but further details remain unknown. The undiscovered mechanisms of EVALI are a barrier to identifying biomarkers and developing therapeutics. Furthermore, adverse effects of e-cigarette use have been linked to chronic lung diseases and systemic effects on multiple organs. In this comprehensive review, we discuss the diverse spectrum of vaping exposures, epidemiological and clinical reports, and experimental findings to provide a better understanding of EVALI and the adverse health effects of chronic e-cigarette exposure.

Subchronic and chronic toxicity evaluation of inorganic nanoparticles for delivery applications

Inorganic nanoparticles provide the opportunity to localize bioactive agents to the target sites and protect them from degradation. In many cases, acute toxicities of inorganic nanoparticles used for delivery applications have been investigated. However, little information is available regarding the long-term toxicity of such materials. This review focuses on the importance of subchronic and chronic toxicity assessment of inorganic nanoparticles investigated for delivery applications. We have attempted to provide a comprehensive review of the available literature for chronic toxicity assessment of inorganic nanoparticles. Where possible correlations are made between particle composition, physiochemical properties, duration, frequency and route of administration, as well as the sex of animals, with tissue and blood toxicity, immunotoxicity and genotoxicity. A critical gap analysis is provided and important factors that need to be considered for long-term toxicology of inorganic nanoparticles are discussed.

RNA-DNA fibers and polygons with controlled immunorecognition activate RNAi, FRET and transcriptional regulation of NF-κB in human cells

Nucleic acid-based assemblies that interact with each other and further communicate with the cellular machinery in a controlled manner represent a new class of reconfigurable materials that can overcome limitations of traditional biochemical approaches and improve the potential therapeutic utility of nucleic acids. This notion enables the development of novel biocompatible 'smart' devices and biosensors with precisely controlled physicochemical and biological properties. We extend this novel concept by designing RNA-DNA fibers and polygons that are able to cooperate in different human cell lines and that have defined immunostimulatory properties confirmed by ex vivo experiments. The mutual intracellular interaction of constructs results in the release of a large number of different siRNAs while giving a fluorescent response and activating NF-κB decoy DNA oligonucleotides. This work expands the possibilities of nucleic acid technologies by (i) introducing very simple design principles and assembly protocols; (ii) potentially allowing for a simultaneous release of various siRNAs together with functional DNA sequences and (iii) providing controlled rates of reassociation, stabilities in human blood serum, and immunorecognition.

Low Dose Carbon Black Nanoparticle Exposure Does Not Aggravate Allergic Airway Inflammation in Mice Irrespective of the Presence of Surface Polycyclic Aromatic Hydrocarbons

Exposure to exogenous noxae, such as particulate matter, can trigger acute aggravations of allergic asthma—a chronic inflammatory airway disease. We tested whether Carbon Black nanoparticles (CBNP) with or without surface polycyclic aromatic hydrocarbons (PAH) aggravate an established allergic airway inflammation in mice. In an ovalbumin mouse model, Printex^®90 (P90), P90 coated with benzo[a]pyrene (P90-BaP) or 9-nitroanthracene (P90-9NA), or acetylene soot exhibiting a mixture of surface PAH (AS-PAH) was administered twice (70 µL, 100 µg/mL) during an established allergic airway inflammation. We analyzed the immune cell numbers and chemokine/cytokine profiles in bronchoalveolar lavages, the mRNA expressions of markers for PAH metabolism (Cyp1a1, 1b1), oxidative stress (HO-1, Gr, Gpx-3), inflammation (KC, Mcp-1, IL-6, IL-13, IL-17a), mucin synthesis (Muc5ac, Muc5b), the histology of mucus-producing goblet cells, ciliary beat frequency (CBF), and the particle transport speed. CBNP had a comparable primary particle size, hydrodynamic diameter, and ζ-potential, but differed in the specific surface area (P90 > P90-BaP = P90-9NA = AS-PAH) and surface chemistry. None of the CBNP tested increased any parameter related to inflammation. The unmodified P90, however, decreased the tracheal CBF, decreased the Muc5b in intrapulmonary airways, but increased the tracheal Muc5ac. Our results demonstrated that irrespective of the surface PAH, a low dose of CBNP does not acutely aggravate an established allergic airway inflammation in mice.

Considerations and Some Practical Solutions to Overcome Nanoparticle Interference with LAL Assays and to Avoid Endotoxin Contamination in Nanoformulations

Monitoring endotoxin contamination in drugs and medical devices is required to avoid pyrogenic response and septic shock in patients receiving these products. Endotoxin contamination of engineered nanomaterials and nanotechnology-based medical products represents a significant translational hurdle. Nanoparticles often interfere with an in vitro Limulus Amebocyte Lysate (LAL) assay commonly used in the pharmaceutical industry for the detection and quantification of endotoxin. Such interference challenges the preclinical development of nanotechnology-formulated drugs and medical devices containing engineered nanomaterials. Protocols for analysis of nanoparticles using LAL assays have been reported before. Here, we discuss considerations for selecting an LAL format and describe a few experimental approaches for overcoming nanoparticle interference with the LAL assays to obtain more accurate estimation of endotoxin contamination in nanotechnology-based products. The discussed approaches do not solve all types of nanoparticle interference with the LAL assays but could be used as a starting point to address the problem. This chapter also describes approaches to prevent endotoxin contamination in nanotechnology-formulated products.

Ins and Outs in Environmental and Occupational Safety Studies of Asthma and Engineered Nanomaterials

According to the Centers for Disease Control and Prevention, approximately 25 million Americans suffer from asthma. The disease total annual cost is about $56 billion and includes both the direct and indirect costs of medications, hospital stays, missed work, and decreased productivity. Air pollution with xenobiotics, bacterial agents, and industrial nanomaterials, such as carbon nanotubes, contribute to the exacerbation of this condition and are a point of particular attention in environmental toxicology as well as in occupational health and safety research. Mast cell degranulation and activation of Th2 cells triggered either by allergen-specific immunoglobulin E (IgE) or by alternative mechanisms, such as locally produced neurotransmitters, underlie the pathophysiological process of airway constriction during an asthma attack. Other immune and non-immune cell types, including basophils, eosinophils, Th1, Th17, Th9, macrophages, dendritic cells, and smooth muscle cells, are involved in the inflammatory and allergic responses during asthma, which, under chronic conditions, may progress without mast cells, the key trigger of the acute asthma attack. To decipher complex molecular, cellular, and genetic mechanisms, many researchers have attempted to develop in vitro and in vivo models to study asthma. Herein, we summarize the advantages and disadvantages of various models and their applicability to nanoparticle evaluation in asthma research. We further suggest that a framework for both in vitro and in vivo methods should be used to study the impact of engineered nanomaterials on asthma etiology, pathophysiology, and treatment.

Current understanding of interactions between nanoparticles and the immune system

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure-activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle-immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15years of research on the immunotoxicity of engineered nanomaterials.

Pre-clinical immunotoxicity studies of nanotechnology-formulated drugs: Challenges, considerations and strategy

Assorted challenges in physicochemical characterization, sterilization, depyrogenation, and in the assessment of pharmacology, safety, and efficacy profiles accompany pre-clinical development of nanotechnology-formulated drugs. Some of these challenges are not unique to nanotechnology and are common in the development of other pharmaceutical products. However, nanoparticle-formulated drugs are biochemically sophisticated, which causes their translation into the clinic to be particularly complex. An understanding of both the immune compatibility of nanoformulations and their effects on hematological parameters is now recognized as an important step in the (pre)clinical development of nanomedicines. An evaluation of nanoparticle immunotoxicity is usually performed as a part of a traditional toxicological assessment; however, it often requires additional in vitro and in vivo specialized immuno- and hematotoxicity tests. Herein, I review literature examples and share the experience with the NCI Nanotechnology Characterization Laboratory assay cascade used in the early (discovery-level) phase of pre-clinical development to summarize common challenges in the immunotoxicological assessment of nanomaterials, highlight considerations and discuss solutions to overcome problems that commonly slow or halt the translation of nanoparticle-formulated drugs toward clinical trials. Special attention will be paid to the grand-challenge related to detection, quantification and removal of endotoxin from nanoformulations, and practical considerations related to this challenge.

Biomarkers of susceptibility: State of the art and implications for occupational exposure to engineered nanomaterials

Rapid advances and applications in nanotechnology are expected to result in increasing occupational exposure to nano-sized materials whose health impacts are still not completely understood. Scientific efforts are required to identify hazards from nanomaterials and define risks and precautionary management strategies for exposed workers. In this scenario, the definition of susceptible populations, which may be at increased risk of adverse effects may be important for risk assessment and management. The aim of this review is to critically examine available literature to provide a comprehensive overview on susceptibility aspects potentially affecting heterogeneous responses to nanomaterials workplace exposure. Genetic, genotoxic and epigenetic alterations induced by nanomaterials in experimental studies were assessed with respect to their possible function as determinants of susceptibility. Additionally, the role of host factors, i.e. age, gender, and pathological conditions, potentially affecting nanomaterial toxicokinetic and health impacts, were also analysed. Overall, this review provides useful information to obtain insights into the nanomaterial mode of action in order to identify potentially sensitive, specific susceptibility biomarkers to be validated in occupational settings and addressed in risk assessment processes. The findings of this review are also important to guide future research into a deeper characterization of nanomaterial susceptibility in order to define adequate risk communication strategies. Ultimately, identification and use of susceptibility factors in workplace settings has both scientific and ethical issues that need addressing.

Titanium dioxide nanoparticles enhance macrophage activation by LPS through a TLR4-dependent intracellular pathway

TiO₂nanoparticles enhance LPS-dependent NO production and cytokine secretion through a mechanism that involves TLR4-mediated p38-signalling and requires phagocytosis.

Inhibition of phosphoinositol 3 kinase contributes to nanoparticle-mediated exaggeration of endotoxin-induced leukocyte procoagulant activity

AIM

Disseminated intravascular coagulation is an increasing concern for certain types of engineered nanomaterials. Recent studies have shed some light on the nanoparticle physicochemical properties contributing to this toxicity; however, the mechanisms are poorly understood. Leukocyte procoagulant activity (PCA) is a key factor contributing to the initiation of this toxicity. We have previously reported on the exaggeration of endotoxin-induced PCA by cationic dendrimers. Herein, we report an effort to discern the mechanism.

MATERIALS & METHODS

Poly(amidoamine) dendrimers with various sizes and surface functionalities were studied in vitro by the recalcification test, flow cytometry and other relevant assays.

RESULTS & CONCLUSION

Cationic dendrimers exaggerated endotoxin-induced PCA, but their anionic or neutral counterparts did not; the cationic charge prompts this phenomenon, but different cationic surface chemistries do not influence it. Cationic dendrimers and endotoxin differentially affect the PCA complex. The inhibition of phosphoinositol 3 kinase by dendrimers contributes to the exaggeration of the endotoxin-induced PCA.

Dose ranging, expanded acute toxicity and safety pharmacology studies for intravenously administered functionalized graphene nanoparticle formulations

Graphene nanoparticle dispersions show immense potential as multifunctional agents for in vivo biomedical applications. Herein, we follow regulatory guidelines for pharmaceuticals that recommend safety pharmacology assessment at least 10-100 times higher than the projected therapeutic dose, and present comprehensive single dose response, expanded acute toxicology, toxicokinetics, and respiratory/cardiovascular safety pharmacology results for intravenously administered dextran-coated graphene oxide nanoplatelet (GNP-Dex) formulations to rats at doses between 1 and 500 mg/kg. Our results indicate that the maximum tolerable dose (MTD) of GNP-Dex is between 50 mg/kg ≤ MTD < 125 mg/kg, blood half-life < 30 min, and majority of nanoparticles excreted within 24 h through feces. Histopathology changes were noted at ≥250 mg/kg in the heart, liver, lung, spleen, and kidney; we found no changes in the brain and no GNP-Dex related effects in the cardiovascular parameters or hematological factors (blood, lipid, and metabolic panels) at doses < 125 mg/kg. The results open avenues for pivotal preclinical single and repeat dose safety studies following good laboratory practices (GLP) as required by regulatory agencies for investigational new drug (IND) application.

Identification and avoidance of potential artifacts and misinterpretations in nanomaterial ecotoxicity measurements

Novel physicochemistries of engineered nanomaterials (ENMs) offer considerable commercial potential for new products and processes, but also the possibility of unforeseen and negative consequences upon ENM release into the environment. Investigations of ENM ecotoxicity have revealed that the unique properties of ENMs and a lack of appropriate test methods can lead to results that are inaccurate or not reproducible. The occurrence of spurious results or misinterpretations of results from ENM toxicity tests that are unique to investigations of ENMs (as opposed to traditional toxicants) have been reported, but have not yet been systemically reviewed. Our objective in this manuscript is to highlight artifacts and misinterpretations that can occur at each step of ecotoxicity testing: procurement or synthesis of the ENMs and assessment of potential toxic impurities such as metals or endotoxins, ENM storage, dispersion of the ENMs in the test medium, direct interference with assay reagents and unacknowledged indirect effects such as nutrient depletion during the assay, and assessment of the ENM biodistribution in organisms. We recommend thorough characterization of initial ENMs including measurement of impurities, implementation of steps to minimize changes to the ENMs during storage, inclusion of a set of experimental controls (e.g., to assess impacts of nutrient depletion, ENM specific effects, impurities in ENM formulation, desorbed surface coatings, the dispersion process, and direct interference of ENM with toxicity assays), and use of orthogonal measurement methods when available to assess ENMs fate and distribution in organisms.

Immunotoxicity of nanoparticles: a computational study suggests that CNTs and C60 fullerenes might be recognized as pathogens by Toll-like receptors

Over the last decade, a great deal of attention has been devoted to study the inflammatory response upon exposure to multi/single-walled carbon nanotubes (CNTs) and different fullerene derivatives. In particular, carbon nanoparticles are reported to provoke substantial inflammation in alveolar and bronchial epithelial cells, epidermal keratinocytes, cultured monocyte-macrophage cells, etc. We suggest a hypothetical model providing the potential mechanistic explanation for immune and inflammatory responses observed upon exposure to carbon nanoparticles. Specifically, we performed a theoretical study to analyze CNT and C60 fullerene interactions with the available X-ray structures of Toll-like receptors (TLRs) homo- and hetero-dimer extracellular domains. This assumption was based on the fact that similar to the known TLR ligands both CNTs and fullerenes induce, in cells, the secretion of certain inflammatory protein mediators, such as interleukins and chemokines. These proteins are observed within inflammation downstream processes resulted from the ligand molecule dependent inhibition or activation of TLR-induced signal transduction. Our computational studies have shown that the internal hydrophobic pockets of some TLRs might be capable of binding small-sized carbon nanostructures (5,5 armchair SWCNTs containing 11 carbon atom layers and C60 fullerene). High binding scores and minor structural alterations induced in TLR ectodomains upon binding C60 and CNTs further supported our hypothesis. Additionally, the proposed hypothesis is strengthened by the indirect experimental findings indicating that CNTs and fullerenes induce an excessive expression of specific cytokines and chemokines (i.e. IL-8 and MCP1).

Sneezing and allergic dermatitis were increased in engineered nanomaterial handling workers

The aim of this study was to survey the work-relatedness of symptoms and diseases among engineered nanomaterials handling workers by questionnaire. A total of 258 exposed workers and 200 comparison workers were recruited from 14 nanomaterials handling factories in Taiwan. In addition to current disease status (prevalence), we classified the diseases worsened by employment (worsened by work). The control banding nanotool risk level matrix was adopted to categorize the severity and probability of nanomaterial exposure. The work-relatedness of symptoms was also self-reported in the questionnaire. The only symptom identified as significantly work-related was sneezing (5.88% in risk level 2 and 7.91% in risk level 1 vs. 2.00% in controls, p=0.04). The prevalences of work-related dry cough (p=0.06) and productive cough (p=0.09) in nanomaterials handling workers were also higher than those in controls. The only disease significantly worsened by work was allergic dermatitis (4.20% in risk level 2, 0% in risk level 1 vs. 0.50% in control, p=0.01). The incidence of angina in nanoworkers was also higher than in controls (p=0.06). In addition to allergic diseases, cardiopulmonary symptoms such as cough and angina may be used as screening tools for medical surveillance of people handling engineered nanomaterials.

Nanoparticles and the blood coagulation system. Part II: safety concerns

Nanoparticle interactions with the blood coagulation system can be beneficial or adverse depending on the intended use of a nanomaterial. Nanoparticles can be engineered to be procoagulant or to carry coagulation-initiating factors to treat certain disorders. Likewise, they can be designed to be anticoagulant or to carry anticoagulant drugs to intervene in other pathological conditions in which coagulation is a concern. An overview of the coagulation system was given and a discussion of a desirable interface between this system and engineered nanomaterials was assessed in part I, which was published in the May 2013 issue of Nanomedicine. Unwanted pro- and anti-coagulant properties of nanoparticles represent significant concerns in the field of nanomedicine, and often hamper the development and transition into the clinic of many promising engineered nanocarriers. This part will focus on the undesirable effects of engineered nanomaterials on the blood coagulation system. We will discuss the relationship between the physicochemical properties of nanoparticles (e.g., size, charge and hydrophobicity) that determine their negative effects on the blood coagulation system in order to understand how manipulation of these properties can help to overcome unwanted side effects.

Distribution and systemic effects of intranasally administered 25 nm silver nanoparticles in adult mice

Previous work indicates that silver nanoparticles (AgNPs) given IP to mice alter the regulation of inflammation- and oxidative stress-related genes in brain. Here we assessed the distribution and toxic potential of AgNP following intranasal (IN) exposure. Adult male C57BL/6J mice received 25-nm AgNP (100 or 500 mg/kg) once IN. After 1 or 7 days, histopathology of selected organs was performed, and tissue reduced glutathione (GSH) levels were measured as an indicator of oxidative stress. Aggregated AgNP were found in spleen, lung, kidney, and nasal airway by routine light microscopy. Splenic AgNP accumulation was greatest in red pulp and occurred with modestly reduced cellularity and elevated hemosiderin deposition. Aggregated AgNP were not associated with microscopic changes in other tissues except for nasal mucosal erosions. Autometallography revealed AgNP in olfactory bulb and the lateral brain ventricles. Neither inflammatory cell infiltrates nor activated microglia were detected in brains of AgNP-treated mice. Elevated tissue GSH levels was observed in nasal epithelia (both doses at 1 day, 500 mg/kg at 7 days) and blood (500 mg/kg at 7 days). Therefore, IN administration of AgNP permits systemic distribution, produces reversible oxidative stress in the nose and in blood, and mildly enhances macrophage-mediated erythrocyte destruction in the spleen.

Dendrimer-induced leukocyte procoagulant activity depends on particle size and surface charge

Aims: Thrombogenicity associated with the induction of leukocyte procoagulant activity (PCA) is a common complication in sepsis and cancer. Since nanoparticles are increasingly used for drug delivery, their interaction with coagulation systems is an important part of the safety assessment. The purpose of this study was to investigate the effects of nanoparticle physicochemical properties on leukocyte PCA, and to get insight into the mechanism of PCA induction. Materials & Methods: A total of 12 formulations of polyamidoamine (PAMAM) dendrimers, varying in size and surface charge, were studied in vitro using recalcification time assay. Results: Irrespective of their size, anionic and neutral dendrimers did not induce leukocyte PCA in vitro. Cationic particles induced PCA in a size- and charge-dependent manner. The mechanism of PCA induction was similar to that of doxorubicin. Cationic dendrimers were also found to exacerbate endotoxin-induced PCA. Conclusion: PAMAM dendrimer-induced leukocyte PCA depends on particle size, charge and density of surface groups.

Direct effects of carbon nanotubes on dendritic cells induce immune suppression upon pulmonary exposure

Pharyngeal aspiration of single-walled carbon nanotubes (SWCNTs) caused inflammation, pulmonary damage, and an altered cytokine network in the lung. Local inflammatory response in vivo was accompanied by modified systemic immunity as documented by decreased proliferation of splenic T cells. Preincubation of naïve T cells in vitro with SWCNT-treated dendritic cells reduced proliferation of T cells. Our data suggest that in vivo exposure to SWCNT modifies systemic immunity by modulating dendritic cell function.