Carbon nanotubes as delivery systems for respiratory disease: do the dangers outweigh the potential benefits?

Carbon Nanotube Immunotoxicity in Alveolar Epithelial Type II Cells Is Mediated by Physical Contact-Independent Cell-Cell Interaction with Macrophages as Demonstrated in an Optimized Air-Liquid Interface (ALI) Coculture Model

There is a need for the assessment of respiratory hazard potential and mode of action of carbon nanotubes (CNTs) before their approval for technological or medical applications. In CNT-exposed lungs, both alveolar macrophages (MФs), which phagocytose CNTs, and alveolar epithelial type II cells (AECII cells), which show tissue injury, are impacted but cell-cell interactions between them and the impacted mechanisms are unclear. To investigate this, we first optimized an air-liquid interface (ALI) transwell coculture of human AECII cell line A549 (upper chamber) and human monocyte cell line THP-1 derived macrophages (lower chamber) in a 12-well culture by exposing macrophages to CNTs at varying doses (5-60 ng/well) for 12-48 h and measuring the epithelial response markers for cell differentiation/maturation (proSP-C), proliferation (Ki-67), and inflammation (IL-1β). In optimal ALI epithelial-macrophage coculture (3:1 ratio), expression of Ki-67 in AECII cells showed dose dependence, peaking at 15 ng/well CNT dose; the Ki-67 and IL-1β responses were detectable within 12 h, peaking at 24-36 h in a time-course. Using the optimized ALI transwell coculture set up with and without macrophages, we demonstrated that direct interaction between CNTs and MФs, but not a physical cell-cell contact between MФ and AECII cells, was essential for inducing immunotoxicity (proliferative and inflammatory responses) in the AECII cells.

Engineering nano-drug biointerface to overcome biological barriers toward precision drug delivery

The rapid advancement of nanomedicine and nanoparticle (NP) materials presents novel solutions potentially capable of revolutionizing health care by improving efficacy, bioavailability, drug targeting, and safety. NPs are intriguing when considering medical applications because of their essential and unique qualities, including a significantly higher surface to mass ratio, quantum properties, and the potential to adsorb and transport drugs and other compounds. However, NPs must overcome or navigate several biological barriers of the human body to successfully deliver drugs at precise locations. Engineering the drug carrier biointerface can help overcome the main biological barriers and optimize the drug delivery in a more personalized manner. This review discusses the significant heterogeneous biological delivery barriers and how biointerface engineering can promote drug carriers to prevail over hurdles and navigate in a more personalized manner, thus ushering in the era of Precision Medicine. We also summarize the nanomedicines' current advantages and disadvantages in drug administration, from natural/synthetic sources to clinical applications. Additionally, we explore the innovative NP designs used in both non-personalized and customized applications as well as how they can attain a precise therapeutic strategy.

Innate but Not Adaptive Immunity Regulates Lung Recovery from Chronic Exposure to Graphene Oxide Nanosheets

Graphene has drawn a lot of interest in the material community due to unique physicochemical properties. Owing to a high surface area to volume ratio and free oxygen groups, the oxidized derivative, graphene oxide (GO) has promising potential as a drug delivery system. Here, the lung tolerability of two distinct GO varying in lateral dimensions is investigated, to reveal the most suitable candidate platform for pulmonary drug delivery. Following repeated chronic pulmonary exposure of mice to GO sheet suspensions, the innate and adaptive immune responses are studied. An acute and transient influx of neutrophils and eosinophils in the alveolar space, together with the replacement of alveolar macrophages by interstitial ones and a significant activation toward anti-inflammatory subsets, are found for both GO materials. Micrometric GO give rise to persistent multinucleated macrophages and granulomas. However, neither adaptive immune response nor lung tissue remodeling are induced after exposure to micrometric GO. Concurrently, milder effects and faster tissue recovery, both associated to a faster clearance from the respiratory tract, are found for nanometric GO, suggesting a greater lung tolerability. Taken together, these results highlight the importance of dimensions in the design of biocompatible 2D materials for pulmonary drug delivery system.

Concepts of advanced therapeutic delivery systems for the management of remodeling and inflammation in airway diseases

Chronic respiratory disorders affect millions of people worldwide. Pathophysiological changes to the normal airway wall structure, including changes in the composition and organization of its cellular and molecular constituents, are referred to as airway remodeling. The inadequacy of effective treatment strategies and scarcity of novel therapies available for the treatment and management of chronic respiratory diseases have given rise to a serious impediment in the clinical management of such diseases. The progress made in advanced drug delivery, has offered additional advantages to fight against the emerging complications of airway remodeling. This review aims to address the gaps in current knowledge about airway remodeling, the relationships between remodeling, inflammation, clinical phenotypes and the significance of using novel drug delivery methods.

Advances in endocrine toxicity of nanomaterials and mechanism in hormone secretion disorders

The size of nanoparticles is about 1-100 nm. People are exposed to nanoparticles in environmental pollutants from ancient times to the present. With the maturity of nanotechnology in the past two decades, the production of manufactured nanomaterials is rapidly increasing and they are used in a wide range of aerospace, medicine, food, and industrial applications. However, both natural and manufactured nanomaterials have been proved to pose a threat to diverse organs and systems. The endocrine system is critical to maintaining homeostasis. Endocrine disorders are associated with many diseases, including cancer, reduced fertility, and metabolic diseases. Therefore, we review the literatures dealing with the endocrine toxicity of nanomaterial. This review provides an exhaustive description of toxic effects of several common nanomaterials in the endocrine system; more involved are reproductive endocrinology. Then physicochemical factors that determine the endocrine toxicity of nanomaterials are discussed. Furthermore, oxidative stress, changes in steroid production and metabolic enzymes, organelle disruption, and alterations in signal pathways are introduced as potential mechanisms that may cause changes in hormone levels. Finally, we suggest that a risk assessment of endocrine toxicity based on standard procedures and consideration of endocrine disrupting effects of nanomaterials in the field and its environmental and population effects could be future research directions for endocrine toxicity of nanomaterials.

Cellular senescence as a response to multiwalled carbon nanotube (MWCNT) exposure in human mesothelial cells

Cellular senescence is a stable cell cycle arrest induced by diverse triggers, including replicative exhaustion, DNA damaging agents, oncogene activation, oxidative stress, and chromatin disruption. With important roles in aging and tumor suppression, cellular senescence has been implicated also in tumor promotion. Here we show that certain multiwalled carbon nanotubes (MWCNTs), as fiber-like nanomaterials, can trigger cellular senescence in primary human mesothelial cells. Using in vitro approaches, we found manifestation of several markers of cellular senescence, especially after exposure to a long and straight MWCNT. These included inhibition of cell division, senescence-associated heterochromatin foci, senescence-associated distension of satellites, LMNB1 depletion, γH2A.X nuclear panstaining, and enlarged cells exhibiting senescence-associated β-galactosidase activity. Furthermore, genome-wide transcriptome analysis revealed many differentially expressed genes, among which were genes encoding for a senescence-associated secretory phenotype. Our results clearly demonstrate the potential of long and straight MWCNTs to induce premature cellular senescence. This finding may find relevance in risk assessment of workplace safety, and in evaluating MWCNT's use in medicine such as drug carrier, due to exposure effects that might prompt onset of age-related diseases, or even carcinogenesis.

Susceptibility Factors in Chronic Lung Inflammatory Responses to Engineered Nanomaterials

Engineered nanomaterials (ENMs) are products of the emerging nanotechnology industry and many different types of ENMs have been shown to cause chronic inflammation in the lungs of rodents after inhalation exposure, suggesting a risk to human health. Due to the increasing demand and use of ENMs in a variety of products, a careful evaluation of the risks to human health is urgently needed. An assessment of the immunotoxicity of ENMs should consider susceptibility factors including sex, pre-existing diseases, deficiency of specific genes encoding proteins involved in the innate or adaptive immune response, and co-exposures to other chemicals. This review will address evidence from experimental animal models that highlights some important issues of susceptibility to chronic lung inflammation and systemic immune dysfunction after pulmonary exposure to ENMs.

The Applications of Carbon Nanotubes in the Diagnosis and Treatment of Lung Cancer: A Critical Review

The importance of timely diagnosis and the complete treatment of lung cancer for many people with this deadly disease daily increases due to its high mortality. Diagnosis and treatment with helping the nanoparticles are useful, although they have reasonable harms. This article points out that the side effects of using carbon nanotube (CNT) in this disease treatment process such as inflammation, fibrosis, and carcinogenesis are very problematic. Toxicity can reduce to some extent using the techniques such as functionalizing to proper dimensions as a longer length, more width, and greater curvature. The targeted CNT sensors can be connected to various modified vapors. In this regard, with helping this method, screening makes non-invasive diagnosis possible. Researchers have also found that nanoparticles such as CNTs could be used as carriers to direct drug delivery, especially with chemotherapy drugs. Most of these carriers were multi-wall carbon nanotubes (MWCNT) used for cancerous cell targeting. The results of laboratory and animal researches in the field of diagnosis and treatment became very desirable and hopeful. The collection of researches summarized has highlighted the requirement for a detailed assessment which includes CNT dose, duration, method of induction, etc., to achieve the most controlled conditions for animal and human studies. In the discussion section, 4 contradictory issues are discussed which are invited researchers to do more research to get clearer results.

A Weigh-in-Motion Characterization Algorithm for Smart Pavements Based on Conductive Cementitious Materials

Smart materials are promising technologies for reducing the instrumentation cost required to continuously monitor road infrastructures, by transforming roadways into multifunctional elements capable of self-sensing. This study investigates a novel algorithm empowering smart pavements with weigh-in-motion (WIM) characterization capabilities. The application domain of interest is a cementitious-based smart pavement installed on a bridge over separate sections. Each section transduces axial strain provoked by the passage of a vehicle into a measurable change in electrical resistance arising from the piezoresistive effect of the smart material. The WIM characterization algorithm is as follows. First, basis signals from axles are generated from a finite element model of the structure equipped with the smart pavement and subjected to given vehicle loads. Second, the measured signal is matched by finding the number and weights of appropriate basis signals that would minimize the error between the numerical and measured signals, yielding information on the vehicle’s number of axles and weight per axle, therefore enabling vehicle classification capabilities. Third, the temporal correlation of the measured signals are compared across smart pavement sections to determine the vehicle weight. The proposed algorithm is validated numerically using three types of trucks defined by the Eurocodes. Results demonstrate the capability of the algorithm at conducting WIM characterization, even when two different trucks are driving in different directions across the same pavement sections. Then, a noise study is conducted, and the results conclude that a given smart pavement section operating with less than 5% noise on measurements could yield good WIM characterization results.

Carbon nanotubes: Evaluation of toxicity at biointerfaces

Carbon nanotubes (CNTs) are a class of carbon allotropes with interesting properties that make them productive materials for usage in various disciplines of nanotechnology such as in electronics equipments, optics and therapeutics. They exhibit distinguished properties viz., strength, and high electrical and heat conductivity. Their uniqueness can be attributed due to the bonding pattern present between the atoms which are very strong and also exhibit high extreme aspect ratios. CNTs are classified as single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) on the basis of number of sidewalls present and the way they are arranged spatially. Application of CNTs to improve the performance of many products, especially in healthcare, has led to an occupational and public exposure to these nanomaterials. Hence, it becomes a major concern to analyze the issues pertaining to the toxicity of CNTs and find the best suitable ways to counter those challenges. This review summarizes the toxicity issues of CNTs in vitro and in vivo in different organ systems (bio interphases) of the body that result in cellular toxicity.

Low doses of multi-walled carbon nanotubes elicit hepatotoxicity in rats with markers of oxidative stress and induction of pro-inflammatory cytokines

The investigation into the potential health risks associated with the use of engineered nanoparticles is a major scientific interest in recent years. The present study elucidated the involvement of pro-inflammatory cytokines, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in carboxylated multi-walled carbon nanotubes (MWCNTs)-induced hepatotoxicity. Pubertal rats were exposed to purified MWCNTs at 0, 0.25, 0.50, 0.75 and 1.0 mg/kg for 5 consecutive days. Results indicated that exposure to MWCNTs caused liver damage evidenced by significant elevation in serum activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and gamma glutamyl transferase (GGT) when compared with control. Moreover, MWCNTs significantly decreased superoxide dismutase (SOD) and glutathione S-transferase (GST) activities as well as glutathione level whereas it significantly increased catalase (CAT) and glutathione peroxidase (GPx) activities in liver of the treated rats. Moreover, the dose-dependent increase in hepatic hydrogen peroxide (H₂O₂) and lipid peroxidation levels were accompanied by marked increase in micronucleated polychromatic erythrocytes (MNPCE) in the MWCNTs-treated rats. Administration of MWCNTs significantly increased serum concentrations of pro-inflammatory cytokines namely interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in the treated rats. Immunohistochemical analysis showed significantly increased COX-2 and iNOS protein expressions in the liver of MWCNTs-treated rats. In conclusion, carboxylated MWCNTs induces hepatic damage via disruption of antioxidant defense systems, promotion of pro-inflammatory cytokines generation and expression of COX-2 and i-NOS in rats.

Pulmonary surfactant protein SP-D opsonises carbon nanotubes and augments their phagocytosis and subsequent pro-inflammatory immune response

Carbon nanotubes (CNTs) are increasingly being developed for use in biomedical applications, including drug delivery. One of the most promising applications under evaluation is in treating pulmonary diseases such as tuberculosis. Once inhaled or administered, the nanoparticles are likely to be recognised by innate immune molecules in the lungs such as hydrophilic pulmonary surfactant proteins. Here, we set out to examine the interaction between surfactant protein D (SP-D), a key lung pattern recognition molecule and CNTs, and possible downstream effects on the immune response via macrophages. We show here that a recombinant form of human SP-D (rhSP-D) bound to oxidised and carboxymethyl cellulose (CMC) coated CNTs via its C-type lectin domain and enhanced phagocytosis by U937 and THP-1 macrophages/monocytic cell lines, together with an increased pro-inflammatory response, suggesting that sequestration of SP-D by CNTs in the lungs can trigger an unwanted and damaging immune response. We also observed that functionalised CNTs, opsonised with rhSP-D, continued to activate complement via the classical pathway, suggesting that C1q, which is the recognition sub-component of the classical pathway, and SP-D have distinct pattern recognition sites on the CNTs. Consistent with our earlier reports, complement deposition on the rhSP-D opsonised CNTs led to dampening of the pro-inflammatory immune response by THP-1 macrophages, as evident from qPCR, cytokine array and NF-κB nuclear translocation analyses. This study highlights the importance of understanding the interplay between innate immune humoral factors including complement in devising nanoparticle based drug delivery strategies.

Toxicological Effects of Carbon Nanotubes

The rapidly evolving field of nanotechnology offers many potential societal and economic benefits. Carbon Nanotubes (CNTs) are one of the most widely produced engineered nanomaterials and have diverse applications in engineering, electronics, and medicine. They have also been extensively investigated for their toxicological properties. Studies with rodents indicate that CNTs can cause lung fibrosis or granuloma formation, exacerbate pre-existing respiratory disease, cause injury to the sensitive pleural lining of the lungs, and have systemic immunosuppressive effects. CNTs have also been reported to cause genotoxic effects on cultured cells. The fiber-like structure of CNTs has led to comparisons with asbestos fibers; yet the debate over whether CNTs cause mesothelioma remains highly controversial, and evidence thus far is lacking. The aim of this chapter is to overview the evidence in rodent models that CNTs cause lung disease and to discuss the potential of CNTs to cause adverse immune, fibrogenic, or carcinogenic effects in humans as a result of occupational, consumer, or environmental exposure.

Responses of testis, epididymis, and sperm of pubertal rats exposed to functionalized multiwalled carbon nanotubes

The present study investigated the response of testes, epididymides and sperm in pubertal Wistar rats following exposure to 0, 0.25, 0.5, 0.75, and 1.0 mg kg(-1) functionalized multi-walled carbon nanotubes (f-MWCNTs) for 5 days. The results showed that administration of (f-MWCNTs) significantly increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in a dose-dependent manner in both testes and sperm compared with control group. Moreover, the significant decrease in the activity of glutathione-S-transferase and glutathione level was accompanied with significant elevation in the levels of hydrogen peroxide and malondialdehyde in both testes and sperm of (f-MWCNTs)-treated rats. The spermiogram of (f-MWCNTs)-treated rats indicated significant decrease in epididymal sperm number, sperm progressive motility, testicular sperm number and daily sperm production with elevated sperm abnormalities when compared with the control. Exposure to (f-MWCNTs) decreased plasma testosterone level and produced marked morphological changes including decreased geminal epithelium, edema, congestion, reduced spermatogenic cells and focal areas of tubular degeneration in the testes. The lumen of the epididymides contained reduced sperm cells and there was mild to severe hyperplasia epithelial cells lining the duct of the epididymis. Collectively, pubertal exposure of male rats to (f-MWCNTs) elicited oxidative stress response resulting in marked testicular and epididymides dysfunction.

Lipid micelles packaged with semiconducting polymer dots as simultaneous MRI/photoacoustic imaging and photodynamic/photothermal dual-modal therapeutic agents for liver cancer

Semiconducting polymer dot micelles for MRI/photoacoustic imaging and single-laser-induced PDT/PTT therapy.

Dual-function theranostic nanoparticles for drug delivery and medical imaging contrast: perspectives and challenges for use in lung diseases

Theranostic nanoparticles with both therapeutic and imaging abilities have the promise to revolutionize diagnosis, therapy, and prognosis. Early and accurate detection along with swift treatment are the most important steps in the successful treatment of any disease. Over the last decade, a variety of nanotechnology-based platforms have been created in the hope of improving the treatment and diagnosis of a wide variety of diseases. However, significant hurdles still remain before theranostic nanoparticles can bring clinical solutions to the fight against chronic respiratory diseases. Some fundamental issues such as long-term toxicity, a precise understanding of the accumulation, degradation and clearance of these particles, and the correlation between basic physicochemical properties of these nanoparticles and their in vivo behavior have to be fully understood before they can be used clinically. To date, very little theranostic nanoparticle research has focused on the treatment and diagnosis of chronic respiratory illnesses. Nanomedicine approaches incorporating these theranostic nanoparticles could potentially be translated into clinical advances to improve diagnosis and treatment of these chronic respiratory diseases and enhance quality of life for the patients.

Toxicoproteomic analysis of pulmonary carbon nanotube exposure using LC-MS/MS

Toxicoproteomics is a developing field that utilizes global proteomic methodologies to investigate the physiological response as a result of adverse toxicant exposure. The aim of this study was to compare the protein secretion profile in lung bronchoalveolar lavage fluid (BALF) from mice exposed to non-functionalized multi-walled carbon nanotubes (U-MWCNTs) or MWCNTs functionalized by nanoscale Al2O3 coatings (A-MWCNT) formed using atomic layer deposition (ALD). Proteins were identified using liquid chromatography tandem mass spectrometry (LC-MS/MS), and quantified using a combination of two label-free proteomic methods: spectral counting and MS1 peak area analysis. On average 465 protein groups were identified per sample and proteins were first screened using spectral counting and the Fisher's exact test to determine differentially regulated species. Significant proteins by Fisher's exact test (p<0.05) were then verified by integrating the intensity under the extracted ion chromatogram from a single unique peptide for each protein across all runs. A two sample t-test based on integrated peak intensities discovered differences in 27 proteins for control versus U-MWCNT, 13 proteins for control versus A-MWCNT, and 2 proteins for U-MWCNT versus A-MWCNT. Finally, an in-vitro binding experiment was performed yielding 4 common proteins statistically different (p<0.05) for both the in-vitro and in-vivo study. Several of the proteins found to be significantly different between exposed and control groups are known to play a key role in inflammatory and immune response. A comparison between the in-vitro and in-vivo CNT exposure emphasized a true biological response to CNT exposure.

Toxicity of quantum dots on respiratory system

Quantum dots (QDs), as advanced nanotechnology products, are widely used in the bio-medical field for diagnostic and therapeutic purposes due to their unique properties. Therefore, it becomes important for researchers to elucidate the adverse effects of QDs on human beings. This essay provides an overview of the toxic effects of QDs on respiratory system, which are summarized into two main parts: in vitro toxicity, including reduction of cell viability, genetic material damage and disordered immune cell reactions; as well as in vivo toxicity, involving accumulation of QDs, lung injury and inflammation, and potential long-term adverse effects. As the toxic severity of a QD type depends on its composition, dose, size, surface chemistry and structure, it is a big challenge to determine a benchmark of QDs. Thus, we have to remember that each QD type is a unique nanocrystal, which needs to be assessed individually. However, there are still some feasible recommendations for minimizing the toxicity provided in this review. Overall, more and more large-scale well-organized toxicity studies of different QD types on different species need to be conducted in order to provide guidelines of QDs' safety application.

Carbon Nanotubes and Chronic Granulomatous Disease

Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT) or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

Flow cytometric analysis of the basophil cell activating impact of potential drug delivery nanoparticle-candidate

INTRODUCTION

Carbon nanotubes – as artificial nano-size ranged materials –have increasing role in the modern biomedical, diagnostic and therapeutic applications.There is a promising option for their use as more potential drug carriers. Despite the favourable properties, their impact (accumulation, elimination, etc.) on biological systems is largely unknown. The main limiting factor of medical use of nanomaterials in most cases is the potential hypersensitive side effect. It can develop in different route, but the activation of basophil granulocytes may play a central role in this process.

OBJECTIVE

Our aim was to test the direct activation ability of different, surface modified nanotubes on basophil granulocytes in vitro. In parallel we tested the effectiveness of BasoTest planned to use for this study.

MATERIALS AND METHODS

Using the blood samples of allergic and healthy volunteers we examined the basophil degranulation in the presence of nanotubes and the expression level changes of cell-surface CD63 on FACS Calibur instrument. Our results were compared to positive(fMLP, Mite, Grass) and negative control samples.

RESULTS

The test we have chosen proved to be sufficiently sensitive and specific for further study. Significant basophil activation was observed in the presence of carbon nanotubes in healthy persons and allergic patients, as well. The activating effect of nanotubes was more prevailed in allergic population.

CONCLUSION

Our experiments have proven the fact that nanotubes may play a role in the development of hypersensitive allergic reactions through their basophil granulocyte activator effect.

Innate Immune Responses to Nanoparticle Exposure in the Lung

The nanotechnology revolution offers enormous societal and economic benefits for innovation in the fields of engineering, electronics, and medicine. Nevertheless, evidence from rodent studies show that biopersistent engineered nanomaterials (ENMs) stimulate immune, inflammatory, and fibroproliferative responses in the lung, suggesting possible risks for lung diseases or systemic immune disorders as a consequence of occupational, environmental, or consumer exposure. Due to their nanoscale dimensions and increased surface area per unit mass, ENMs have a much greater potential to reach the distal regions of the lung and generate ROS. High aspect ratio ENMs (e.g., nanotubes, nanofibers) activate inflammasomes in macrophages, triggering IL-1β release and neutrophilic infiltration into the lungs. Moreover, some ENMs alter allergen-induced eosinophilic inflammation by immunostimulation, immunosuppression, or modulating the balance between Th1, Th2, and Th17 cells, thereby influencing the nature of the inflammatory response. ENMs also migrate from the lungs across epithelial, endothelial, or mesothelial barriers to stimulate or suppress systemic immune responses.

Carbon nanotube-induced pulmonary granulomatous disease: Twist1 and alveolar macrophage M1 activation

Sarcoidosis, a chronic granulomatous disease of unknown cause, has been linked to several environmental risk factors, among which are some that may favor carbon nanotube formation. Using gene array data, we initially observed that bronchoalveolar lavage (BAL) cells from sarcoidosis patients displayed elevated mRNA of the transcription factor, Twist1, among many M1-associated genes compared to healthy controls. Based on this observation we hypothesized that Twist1 mRNA and protein expression might become elevated in alveolar macrophages from animals bearing granulomas induced by carbon nanotube instillation. To address this hypothesis, wild-type and macrophage-specific peroxisome proliferator-activated receptor gamma (PPARγ) knock out mice were given oropharyngeal instillation of multiwall carbon nanotubes (MWCNT). BAL cells obtained 60 days later exhibited significantly elevated Twist1 mRNA expression in granuloma-bearing wild-type or PPARγ knock out alveolar macrophages compared to sham controls. Overall, Twist1 expression levels in PPARγ knock out mice were higher than those of wild-type. Concurrently, BAL cells obtained from sarcoidosis patients and healthy controls validated gene array data: qPCR and protein analysis showed significantly elevated Twist1 in sarcoidosis compared to healthy controls. In vitro studies of alveolar macrophages from healthy controls indicated that Twist1 was inducible by classical (M1) macrophage activation stimuli (LPS, TNFα) but not by IL-4, an inducer of alternative (M2) macrophage activation. Findings suggest that Twist1 represents a PPARγ-sensitive alveolar macrophage M1 biomarker which is induced by inflammatory granulomatous disease in the MWCNT model and in human sarcoidosis.

Potential toxicity and safety evaluation of nanomaterials for the respiratory system and lung cancer

Engineered nanomaterials (ENMs) are a diverse group of materials finding increasing use in manufacturing, computing, food, pharmaceuticals, and biomedicine due to their very small size and exceptional properties. Health and safety concerns for ENMs have forced regulatory agencies to consider preventive measures and regulations for workers’ health and safety protection. Respiratory system toxicity from inhalable ENMs is the most important concern to health specialists. In this review, we focus on similarities and differences between conventional microparticles (diameters in mm and μm), which have been previously studied, and nanoparticles (sizes between 1 and 100 nm) in terms of size, composition, and mechanisms of action in biological systems. In past decades, respirable particulate matter (PM), asbestos fibers, crystalline silicate, and various amorphous dusts have been studied, and epidemiological evidence has shown how dangerous they are to human health, especially from exposure in working environments. Scientific evidence has shown that there is a close connection between respirable PM and pulmonary oxidative stress through the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). There is a close connection between oxidative stress in the cell and the elicitation of an inflammatory response via pro-inflammatory gene transcription. Inflammatory processes increase the risk for lung cancer. Studies in vitro and in vivo in the last decade have shown that engineered nanoparticles (ENPs) at various doses can cause ROS generation, oxidative stress, and pro-inflammatory gene expression in the cell. It is assumed that ENPs have the potential to cause acute respiratory diseases and probably lung cancer in humans. The situation regarding chronic exposure at low doses is more complicated. The long-term accumulation of ENPs in the respiratory system cannot be excluded. However, at present, exposure data for the general public regarding ENPs are not available.

PEGylated single-walled carbon nanotubes as nanocarriers for cyclosporin A delivery

Single-walled carbon nanotubes (SWCNTs) have attracted the attention of many researchers due to their remarkable physicochemical features and have been found to be a new family of nanovectors for the delivery of therapeutic molecules. The ability of these nanostructures to load large amounts of drug molecules on their outer surface has been considered as the main advantage by many investigators. Here, we report the development of a PEGylated SWCNT-mediated delivery system for cyclosporin A (CsA) as a potent immunosuppressive agent. The available OH group in the CsA structure was first linked to a bi-functional linker (i.e., succinic anhydride) in order to provide a COOH terminal group. CsA succinylation process was optimized by using the modified simplex method. The resulting compound, CsA-CO-(CH(2))(2)-COOH, was then grafted onto the exterior surface of SWCNTs, previously PEGylated with phospholipid-PEG(5000)-NH(2) conjugates, through the formation of an amide bond with the free amine group of PEGylated SWCNTs. Drug loading, stability of the PEGylated SWCNT-CsA complex, and in vitro release of the drug were evaluated. Loading efficiencies of almost 72% and 68% were achieved by UV spectrophotometry and elemental analysis methods, respectively. It was observed that 57.3% of cyclosporine was released from CsA-Pl-PEG(5000)-SWCNTs after 3 days. In this investigation, we conjugated CsA to an amine-terminated phospholipid-polyethylene glycol chain attached on SWCNTs via a cleavable ester bond and demonstrated the possible potential of PEGylated SWCNT-based systems for CsA delivery.

Citrullination as early-stage indicator of cell response to single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) have been widely explored as potential technologies for information systems and medical applications. The impact of SWCNTs on human health is of prime concern, if SWCNTs have a future in the manufacturing industry. This study proposes a novel, inflammation-independent paradigm of toxicity for SWCNTs, identifying the protein citrullination process as early-stage indicator of inflammatory responses of macrophages (THP-1) and of subtle phenotypic damages of lung epithelial (A549) cells following exposure to chemically-treated SWCNTs. Our results showed that, while most of the cellular responses of A549 cells exposed to SWCNTs are different to those of similarly treated THP-1 cells, the protein citrullination process is triggered in a dose- and time-dependent manner in both cell lines, with thresholds comparable between inflammatory (THP-1) and non-inflammatory (A549) cell types. The cellular mechanism proposed herein could have a high impact in predicting the current risk associated with environmental exposure to SWCNTs.