Reactive oxygen species (ROS) and reactive nitrogen species (RNS) generation by silica in inflammation and fibrosis

Metabolomics Study of Immune Responses of New Zealand Greenshell™ Mussels (Perna canaliculus) Infected with Pathogenic Vibrio sp

Vibrio coralliilyticus is a bacterial pathogen which can affect a range of marine organisms, such as corals, fish and shellfish, with sometimes devastating consequences. However, little is known about the mechanisms involved in the host-pathogen interaction, especially within molluscan models. We applied gas chromatography-mass spectrometry (GC-MS)-based metabolomics to characterize the physiological responses in haemolymph of New Zealand Greenshell™ mussels (Perna canaliculus) injected with Vibrio sp. DO1 (V. coralliilyticus/neptunius-like isolate). Univariate data analyses of metabolite profiles in Vibrio-exposed mussels revealed significant changes in 22 metabolites at 6 h post-infection, compared to non-exposed mussels. Among them, 10 metabolites were up-regulated, while 12 metabolites were down-regulated in infected mussels. Multivariate analyses showed a clear distinction between infected and non-infected mussels. In addition, secondary pathway analyses indicated perturbations of the host innate immune system following infection, including oxidative stress, inflammation and disruption of the TCA cycle, change in amino acid metabolism and protein synthesis. These findings provide new insights into the pathogenic mechanisms of Vibrio infection of mussels and demonstrate our ability to detect detailed and rapid host responses from haemolymph samples using a metabolomics approach.

Inflammatory and oxidative stress parameters as potential early biomarkers for silicosis

Workers involved in mining activities are exposed to crystalline silica, which leads to constant pulmonary inflammatory reactions and severe oxidative damage, resulting in silicosis. In this work, we aimed to evaluate inflammatory and oxidative stress parameters as potential early biomarkers of effect to assess crystalline silica toxicity in workers who had occupational exposure during mining. We enrolled 38 workers exposed to crystalline silica (WECS), 24 individuals with silicosis (IWS), and 30 occupationally unexposed workers (OUW), a total of 92 participants. The WECS were divided into 2 groups, according to the time of exposure: 19 workers with 1-15 years of occupational exposure (WECS I) and 19 workers with >16 years of occupational exposure (WECS II). The inflammatory parameters assessed were L-selectin, β-2 integrin, and intercellular adhesion molecule-1 (ICAM-1) surface protein expression in lymphocytes and monocytes, complement C3 and C4, high sensitivity C-reactive protein (hsCRP), and adenosine deaminase (ADA) in serum. Plasma levels of malondialdehyde (MDA) and serum levels of vitamin C were determined as biomarkers of oxidative stress. Biochemical and hematological parameters were also investigated. L-selectin surface protein expression was significantly decreased in the WECS II group (p < 0.05), indicating the importance of this immune system component as a potential marker of crystalline-silica-induced toxicity. The MDA levels were significantly increased in the WECS I, WECS II, and IWS groups compared to the OUW group (p < 0.05). Vitamin C levels were decreased, while C3, hsCRP, ADA, and aspartate aminotransferase (AST) levels were increased in the IWS group compared to the OUW group (p < 0.05). Glucose and urea levels were significantly higher in the WECS I, II, and IWS groups compared to the OUW group (p < 0.05). Negative partial association was found between L-selectin and time of exposure (p < 0.001), supporting the relevance of this biomarker evaluation in long-term exposure to crystalline silica. Significant associations were also observed among inflammatory and oxidative stress biomarkers. Therefore, our results demonstrated the relevance of L-selectin as a potential peripheral biomarker for monitoring crystalline silica-induced toxicity in miners after chronic exposure, before silicosis has developed. However, more studies are necessary for better understanding of the use L-selectin as an early biomarker in exposed workers.

Intratracheal instillation of coal and coal fly ash particles in mice induces DNA damage and translocation of metals to extrapulmonary tissues

Continuous exposure to coal mining particles can cause a variety of lung diseases. We aimed to evaluate the outcomes of exposure to detailed characterized coal and coal fly ash (CFA) particles on DNA, lung and extrapulmonary tissues. Coal samples (COAL11 and COAL16) and CFA samples (CFA11 and CFA16) were included in this study. Intending to enhance the combustion process COAL16 was co-fired with a mixture of fuel oil and diesel oil, producing CFA16. Male BALB/c mice were intratracheally instilled with coal and CFA particles. Measurements were done 24h later. Results showed significant rigidity and obstruction of the central airways only for animals acutely exposed to coal particles. The COAL16 group also showed obstruction of the peripheral airways. Mononuclear cells were recruited in all treatment groups and expression of cytokines, particularly TNF-α and IL-1β, was observed. Only animals exposed to COAL16 showed a significant expression of IL-6 and recruitment of polymorphonuclear cells. DNA damage was demonstrated by Comet assay for all groups. Cr, Fe and Ni were detected in liver, spleen and brain, showing the efficient translocation of metals from the bloodstream to extrapulmonary organs. These effects were associated with particle composition (oxides, hydroxides, phosphates, sulfides, sulphates, silciates, organic-metalic compounds, and polycyclic aromatic hidrocarbons) rather than their size. This work provides state of knowledge on the effects of acute exposure to coal and CFA particles on respiratory mechanics, DNA damage, translocation of metals to other organs and related inflammatory processes.

Modulation of reactive oxygen species production, apoptosis and cell cycle in pleural exudate cells of carrageenan-induced acute inflammation in rats by rutin

The present study seeks to investigate the effect of rutin, a flavonoid compound in rat models of acute inflammation induced by carrageenan (CAR). Twenty-four female Wistar rats weighing 222-247 g received saline or 2% λ-carrageenan in the pleural cavity and treatment with rutin (80 mg kg^-1) or saline by oral gavage for 21 days prior to the intrapleural induction of CAR. After 4 h of induction, the rats were euthanized, the plasma was prepared from the blood for the analysis of haematological parameters and the pleural exudate was obtained for the analysis of the total cell count, cell viability, reactive oxygen species (ROS) production, apoptosis and cell cycle. The result revealed that rutin exhibited anti-inflammatory effects by modulating the ROS level, apoptosis and cell cycle. This study indicates that rutin may exert a protective effect against ROS-mediated oxidative damage associated with an anti-inflammatory activity in rat models of acute inflammation.

Crystalline silica alters Sulfatase-1 expression in rat lungs which influences hyper-proliferative and fibrogenic effects in human lung epithelial cells

Lung epithelial cells are the first cell-type to come in contact with hazardous dust materials. Upon deposition, they invoke complex reactions in attempt to eradicate particles from the airways, and repair damage. The cell surface is composed of a heterogeneous network of matrix proteins and proteoglycans, which act as scaffold and control cell-signaling networks. These functions are controlled, in part, by the sulfation patterns of heparin-sulfate proteoglycans (HSPGs), which are enzymatically regulated. Although there is evidence of altered HSPG-sulfation in idiopathic pulmonary fibrosis (IPF), this is not investigated in silicosis. Our previous studies revealed down-regulation of Sulfatase-1 (SULF1) in human bronchial epithelial cells (BECs) by crystalline silica (CS). In this study, CS-induced down-regulation of SULF1, and increases in Sulfated-HSPGs, were determined in human BECs, and in rat lungs. By siRNA and plasmid transfection techniques the effects of SULF1 expression on silica-induced fibrogenic and proliferative gene expression were determined. These studies confirmed down-regulation of SULF1 and subsequent increases in sulfated-HSPGs in vitro. Moreover, short-term exposure of rats to CS resulted in similar changes in vivo. Conversely, effects were reversed after long term CS exposure of rats. SULF1 knockdown, and overexpression alleviated and exacerbated silica-induced decrease in cell viability, respectively. Furthermore, overexpression of SULF1 promoted silica-induced proliferative and fibrogenic gene expression, and collagen production. These findings demonstrate that the HSPG modification enzyme SULF1 and HSPG sulfation are altered by CS in vitro and in vivo. Furthermore, these changes may contribute to CS-induced lung pathogenicity by affecting injury tolerance, hyperproliferation, and fibrotic effects.

Inflammasome-Independent Leukotriene B4 Production Drives Crystalline Silica-Induced Sterile Inflammation

Silicosis is a lung inflammatory disease caused by chronic exposure to crystalline silica (CS). Leukotriene B₄ (LTB₄) plays an important role in neutrophilic inflammation, which drives silicosis and promotes lung cancer. In this study, we examined the mechanisms involved in CS-induced inflammatory pathways. Phagocytosis of CS particles is essential for the production of LTB₄ and IL-1β in mouse macrophages, mast cells, and neutrophils. Phagosomes enclosing CS particles trigger the assembly of lipidosome in the cytoplasm, which is likely the primary source of CS-induced LTB₄ production. Activation of the JNK pathway is essential for both CS-induced LTB₄ and IL-1β production. Studies with bafilomycin-A1- and NLRP3-deficient mice revealed that LTB₄ synthesis in the lipidosome is independent of inflammasome activation. Small interfering RNA knockdown and confocal microscopy studies showed that GTPases Rab5c, Rab40c along with JNK1 are essential for lipidosome formation and LTB₄ production. BI-78D3, a JNK inhibitor, abrogated CS-induced neutrophilic inflammation in vivo in an air pouch model. These results highlight an inflammasome-independent and JNK activation-dependent lipidosome pathway as a regulator of LTB₄ synthesis and CS-induced sterile inflammation.

Upregulation of SIRT1 inhibits H2O2‑induced osteoblast apoptosis via FoxO1/β‑catenin pathway

Osteoporosis is a disease that significantly influences life expectancy and quality in humans. Oxidative stress may stimulate bone marrow osteoclast differentiation and inhibit osteoblast (OB) differentiation. OB proliferation and differentiation are affected by the forkhead box O (FoxO)1/β‑catenin signaling pathway. The osteogenic differentiation of mesenchymal stem cells (MSCs) may be promoted by silent information regulator type‑1 [sirtuin (SIRT)1]. However, the molecular mechanism of SIRT1 regulation of osteogenic differentiation of MSCs remains unclear, and further elucidation is needed. The present study investigated the role of SIRT1 in the FoxO1/β‑catenin signaling pathway in oxidative stress and its mechanism in the osteoblastic progenitor cell line (MC3T3‑E1). The results demonstrated that OB apoptosis and elevated oxidative stress in cells were simulated by H2O2, which was inhibited by moderate SIRT1 overexpression through reducing the oxidative stress. Further studies revealed that FOXO1 and β‑catenin pathway activity was downregulated by SIRT1 and eventually resulted in inhibition of target genes, including the proapoptotic gene B cell lymphoma‑2 interacting mediator of cell death, DNA repair gene growth arrest and DNA damage inducible protein 45 and the OB differentiation suppressor gene peroxisome proliferator activated receptor (PPAR)‑γ. Furthermore, β‑catenin and PPAR‑γ were inhibited by SIRT1. Overall, the results of the present study suggest that moderate overexpression of SIRT1 (~3‑fold of normal level) may directly or indirectly inhibit apoptosis of OBs via the FOXO1 and β‑catenin signaling pathway.

Deposition and cellular interaction of cancer-inducing particles in the human respiratory tract: Theoretical approaches and experimental data

Inhaled particles that are deposited on the epithelial surface of the human respiratory tract (HRT) may act as serious health hazards, in the worst case inducing the development of various types of lung cancer. In the past, several particle types, such as asbestos fibers, hard wood dust and cigarette smoke were identified and classified as human carcinogens. Due to their different physical and chemical properties these particles are characterized by remarkable discrepancies concerning their transport, deposition, and epithelial interaction in the HRT. In order to continuously increase the knowledge on carcinogenic particle behavior in the HRT, theoretical models describing single stages of particulate action in the lung airways were developed over the last few decades. With the help of these mathematical approaches physical characteristics of aerosolized drugs as well as protocols of inhalative therapies for the treatment of lung diseases could be significantly optimized. In addition, new experimental setups for the enlightenment of possible mechanisms underlying particle-lung interaction were, among other things, founded upon the results of theoretical computations. This review summarizes the efforts and advances of theoretical lung modeling from the early 1970s till today, thereby mainly directing the attention to the simulation of carcinogenic particle behavior in the HRT.

A Short Review of Experimental Peritoneal Sclerosis: From Mice to Men

Peritoneal sclerosis has been induced in rodents in vivo by exposing the membrane to a variety of experimental interventions: asbestos, 0.1% chlorexidine, iron dextran, glucose degradation products, AGE deposits derived from uremia per se, sodium hypochlorite, lypopolysaccharide, low pH, pure water, silica or zymosan. With a few exceptions (pure water, chlorhexidine and low pH), the other substances mentioned operate setting out different degrees of oxidative stress. This short review describes several experimental interventions in rodents, aimed at acute exfoliation or long-term, sustained injury of the mesothelial monolayer performed by means of intraperitoneal injections of different oxidant agents.

Acute exfoliation induced by deoxycholate resulted in a depopulated monolayer coincident with immediate alteration of the peritoneal permeability, evidenced by increased urea D/P ratio, higher glucose absorption rate, elevated albumin losses in the effluent and significant reduction of the ultrafiltration rate.

In the long term (30 days), these manifestations of membrane failure persisted and coincided with substantial peritoneal sclerosis.

Peritoneal sclerosis was also induced by IP injections of 0.125% trypsin and 6.6 mM/L solution of formaldehyde. Using the doughnut rat model of mesothelial regeneration, exposure to 4.25% glucose or 7.5% icodextrin solutions severely hampered repopulation of the monolayer, which was replaced by a thick sheet of fibrous tissue.

It is concluded that peritoneal sclerosis derives mostly from sustained oxidative injury to the peritoneal membrane. Loss of the mesothelial monolayer is the first step in the chain of events leading to this complication.

Regulation of TLR4 in silica-induced inflammation: An underlying mechanism of silicosis

Silicosis is an incurable lung disease affecting millions of workers in hazardous occupations. It is caused by chronic exposure to the dust that contains free crystalline silica. Silica-induced lung damage occurs by several main mechanisms including cell death by apoptosis, fibrosis and production of cytokines. However, the signal pathways involved in these mechanisms are not fully characterized. In this study, the toll-like receptor 4 (TLR4)-related signal pathway was examined in silica-treated U937-differentiated macrophages. The expression level of TLR4 was measured by both quantitative PCR and Western blot. Confirmation of the involvement of MyD88/TIRAP and NFκB p65 cascade was performed by Western blot. The secretion of cytokines IL-1β, IL-6, IL-10 and TNFα was measured by enzyme-linked immunosorbent assay. Our results showed that TLR4 and related MyD88/TIRAP pathway was associated with silica-exposure in U937-differentiated macrophages. Protein expression of TLR4, MyD88 and TIRAP was upregulated when the U937-differentiated macrophages were exposed to silica. However, the upregulation was attenuated when TLR4 inhibitor, TAK-242 was present. At different incubation times of silica exposure, it was found that NFκB p65 cascade was activated at 10-60 minutes. Release of cytokines IL-1β, IL-6, IL-10 and TNFα was induced by silica exposure and the induction of IL-1β, IL-6 and TNFα was suppressed by the addition of TAK-242. In conclusion, our study demonstrated that TLR4 and related MyD88/TIRAP pathway was involved in silica-induced inflammation in U937-differentiated macrophages. Downstream NFκB p65 cascade was activated within 1 hour when the U937-differentiated macrophages were exposed to silica. The better understanding of early stage of silica-induced inflammatory process may help to develop earlier diagnosis of silicosis.

Toxicity Assessment in the Nanoparticle Era

The wide use of engineered nanomaterials in many fields, ranging from biomedical, agriculture, environment, cosmetic, urged the scientific community to understand the processes behind their potential toxicity, in order to develop new strategies for human safety. As a matter of fact, there is a big discrepancy between the increased classes of nanoparticles and the consequent applications versus their toxicity assessment. Nanotoxicology is defined as the science that studies the effects of engineered nanodevices and nanostructures in living organisms. This chapter analyzes the physico-chemical properties of the most used nanoparticles, the way they enter the living organism and their cytoxicity mechanisms at cellular exposure level. Moreover, the current state of nanoparticles risk assessment is reported and analyzed.

Protective Effect of Yang Mi Ryung® Extract on Noise-Induced Hearing Loss in Mice

Noise-induced hearing loss (NIHL) results from the damage of the delicate hair cells inside the ear after excessive stimulation of noise. Unlike certain lower animals such as amphibians, fishes, and birds, in humans, hair cells cannot be regenerated once they are killed or damaged; thus, there are no therapeutic options to cure NIHL. Therefore, it is more important to protect hair cells from the noise before the damage occurs. In this study, we report the protective effect of Yang Mi Ryung extract (YMRE) against NIHL; this novel therapeutic property of YMRE has not been reported previously. Our data demonstrates that the hearing ability damaged by noise is markedly restored in mice preadministrated with YMRE before noise exposure, to the level of normal control group. Our study also provides the molecular mechanism underlying the protective effect of YMRE against NIHL by showing that YMRE significantly blocks noise-induced apoptotic cell death and reduces reactive oxygen species (ROS) production in cochleae. Moreover, quantitative polymerase chain reaction (qPCR) analysis demonstrates that YMRE has anti-inflammatory properties, suppressing the mRNA levels of TNFα and IL-1β induced by noise exposure. In conclusion, YMRE could be a useful preventive intervention to prevent hearing impairment induced by the exposure to excessive noise.

Roles of Heat Shock Proteins in Apoptosis, Oxidative Stress, Human Inflammatory Diseases, and Cancer

Heat shock proteins (HSPs) play cytoprotective activities under pathological conditions through the initiation of protein folding, repair, refolding of misfolded peptides, and possible degradation of irreparable proteins. Excessive apoptosis, resulting from increased reactive oxygen species (ROS) cellular levels and subsequent amplified inflammatory reactions, is well known in the pathogenesis and progression of several human inflammatory diseases (HIDs) and cancer. Under normal physiological conditions, ROS levels and inflammatory reactions are kept in check for the cellular benefits of fighting off infectious agents through antioxidant mechanisms; however, this balance can be disrupted under pathological conditions, thus leading to oxidative stress and massive cellular destruction. Therefore, it becomes apparent that the interplay between oxidant-apoptosis-inflammation is critical in the dysfunction of the antioxidant system and, most importantly, in the progression of HIDs. Hence, there is a need to maintain careful balance between the oxidant-antioxidant inflammatory status in the human body. HSPs are known to modulate the effects of inflammation cascades leading to the endogenous generation of ROS and intrinsic apoptosis through inhibition of pro-inflammatory factors, thereby playing crucial roles in the pathogenesis of HIDs and cancer. We propose that careful induction of HSPs in HIDs and cancer, especially prior to inflammation, will provide good therapeutics in the management and treatment of HIDs and cancer.

Silica inhalation altered telomere length and gene expression of telomere regulatory proteins in lung tissue of rats

Exposure to silica can cause lung fibrosis and cancer. Identification of molecular targets is important for the intervention and/or prevention of silica-induced lung diseases. Telomeres consist of tandem repeats of DNA sequences at the end of chromosomes, preventing chromosomal fusion and degradation. Regulator of telomere length-1 (RTEL1) and telomerase reverse transcriptase (TERT), genes involved in telomere regulation and function, play important roles in maintaining telomere integrity and length. The goal of this study was to assess the effect of silica inhalation on telomere length and the regulation of RTEL1 and TERT. Lung tissues and blood samples were collected from rats at 4, 32, and 44 wk after exposure to 15 mg/m3 of silica × 6 h/d × 5 d. Controls were exposed to air. At all-time points, RTEL1 expression was significantly decreased in lung tissue of the silica-exposed animals compared to controls. Also, significant increases in telomere length and TERT were observed in the silica group at 4 and 32 wk. Telomere length, RTEL1 and TERT expression may serve as potential biomarkers related to silica exposure and may offer insight into the molecular mechanism of silica-induced lung disease and tumorigeneses.

Apoptotic Cells Induced Signaling for Immune Homeostasis in Macrophages and Dendritic Cells

Inefficient and abnormal clearance of apoptotic cells (efferocytosis) contributes to systemic autoimmune disease in humans and mice, and inefficient chromosomal DNA degradation by DNAse II leads to systemic polyarthritis and a cytokine storm. By contrast, efficient clearance allows immune homeostasis, generally leads to a non-inflammatory state for both macrophages and dendritic cells (DCs), and contributes to maintenance of peripheral tolerance. As many as 3 × 10⁸ cells undergo apoptosis every hour in our bodies, and one of the primary “eat me” signals expressed by apoptotic cells is phosphatidylserine (PtdSer). Apoptotic cells themselves are major contributors to the “anti-inflammatory” nature of the engulfment process, some by secreting thrombospondin-1 (TSP-1) or adenosine monophosphate and possibly other immune modulating “calm-down” signals that interact with macrophages and DCs. Apoptotic cells also produce “find me” and “tolerate me” signals to attract and immune modulate macrophages and DCs that express specific receptors for some of these signals. Neither macrophages nor DCs are uniform, and each cell type may variably express membrane proteins that function as receptors for PtdSer or for opsonins like complement or opsonins that bind to PtdSer, such as protein S and growth arrest-specific 6. Macrophages and DCs also express scavenger receptors, CD36, and integrins that function via bridging molecules such as TSP-1 or milk fat globule-EGF factor 8 protein and that differentially engage in various multi-ligand interactions between apoptotic cells and phagocytes. In this review, we describe the anti-inflammatory and pro-homeostatic nature of apoptotic cell interaction with the immune system. We do not review some forms of immunogenic cell death. We summarize the known apoptotic cell signaling events in macrophages and DCs that are related to toll-like receptors, nuclear factor kappa B, inflammasome, the lipid-activated nuclear receptors, Tyro3, Axl, and Mertk receptors, as well as induction of signal transducer and activator of transcription 1 and suppressor of cytokine signaling that lead to immune system silencing and DC tolerance. These properties of apoptotic cells are the mechanisms that enable their successful use as therapeutic modalities in mice and humans in various autoimmune diseases, organ transplantation, graft-versus-host disease, and sepsis.

Development of breath test for pneumoconiosis: a case-control study

Background

Lipid peroxidation plays an important role in the pathogenesis of pneumoconiosis. Volatile organic compounds (VOCs) generated from lipid peroxidation might be used to detect pneumoconiosis. The objective of this study was to develop a breath test for pneumoconiosis.

Methods

A case-control study was designed. Breath and ambient air were analysed by gas chromatography/mass spectrometry. After blank correction to prevent contamination from ambient air, we used canonical discriminant analysis (CDA) to assess the discrimination accuracy and principal component analysis (PCA) to generate a prediction score. The prediction accuracy was calculated and validated using the International Classification of Radiographs of the Pneumoconiosis criteria combined with an abnormal pulmonary function test as a reference standard. We generated a receiver operator characteristic (ROC) curve and calculated the area under the ROC curve (AUC) to estimate the screening accuracy of the breath test.

Results

We enrolled 200 stone workers. After excluding 5 subjects with asthma and 16 subjects who took steroids or nonsteroidal anti-inflammatory drugs, a total of 179 subjects were used in the final analyses, which included 25 cases and 154 controls. By CDA, 88.8% of subjects were correctly discriminated by their exposure status and the presence of pneumoconiosis. After excluding the VOCs of automobile exhaust and cigarette smoking, pentane and C5-C7 methylated alkanes constituted the major VOCs in the breath of persons with pneumoconiosis. Using the prediction score generated from PCA, the ROC-AUC was 0.88 (95% CI = 0.80—0.95), and the mean ROC-AUC of 5-fold cross-validation was 0.90. The breath test had good accuracy for pneumoconiosis diagnosis.

Conclusion

The analysis of breath VOCs has potential in the screening of pneumoconiosis for its non-invasiveness and high accuracy. We suggest that a multi-centre study is warranted and that all procedures must be standardized before clinical application.

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria-A Challenge for Life on Mars

The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

The Effects of Silica Nanoparticles on Apoptosis and Autophagy of Glioblastoma Cell Lines

Silica nanoparticles (SiNPs) are one of the most commonly used nanomaterials in various medical applications. However, possible mechanisms of the toxicity caused by SiNPs remain unclear. The study presented here provides novel information on molecular and cellular effects of SiNPs in glioblastoma LBC3 and LN-18 cells. It has been demonstrated that SiNPs of 7 nm, 5–15 nm and 10–20 nm induce time- and dose-dependent cytotoxicity in LBC3 and LN-18 cell lines. In contrast to glioblastoma cells, we observed only weak reduction in viability of normal skin fibroblasts treated with SiNPs. Furthermore, in LBC3 cells treated with 5–15 nm SiNPs we noticed induction of apoptosis and necrosis, while in LN-18 cells only necrosis. The 5–15 nm SiNPs were also found to cause oxidative stress, a loss in mitochondrial membrane potential, and changes in the ultrastructure of the mitochondria in LBC3 cells. Quantitative real-time PCR results showed that in LBC3 cells the mRNA levels of pro-apoptotic genes Bim, Bax, Puma, and Noxa were significantly upregulated. An increase in activity of caspase-9 in these cells was also observed. Moreover, the activation of SiNP-induced autophagy was demonstrated in LBC3 cells as shown by an increase in LC3-II/LC3-I ratio, the upregulation of Atg5 gene and an increase in AVOs-positive cells. In conclusion, this research provides novel information concerning molecular mechanisms of apoptosis and autophagy in LBC3 cells.

Transcriptomics in toxicology

Xenobiotics, of which many are toxic, may enter the human body through multiple routes. Excessive human exposure to xenobiotics may exceed the body's capacity to defend against the xenobiotic-induced toxicity and result in potentially fatal adverse health effects. Prevention of the adverse health effects, potentially associated with human exposure to the xenobiotics, may be achieved by detecting the toxic effects at an early, reversible and, therefore, preventable stage. Additionally, an understanding of the molecular mechanisms underlying the toxicity may be helpful in preventing and/or managing the ensuing adverse health effects. Human exposures to a large number of xenobiotics are associated with hepatotoxicity or pulmonary toxicity. Global gene expression changes taking place in biological systems, in response to exposure to xenobiotics, may represent the early and mechanistically relevant cellular events contributing to the onset and progression of xenobiotic-induced adverse health outcomes. Hepatotoxicity and pulmonary toxicity resulting from exposure to xenobiotics are discussed as specific examples to demonstrate the potential application of transcriptomics or global gene expression analysis in the prevention of adverse health effects associated with exposure to xenobiotics.

Delayed Nrf2-regulated antioxidant gene induction in response to silica nanoparticles

Silica nanoparticles with iron on their surface cause the production of oxidants and stimulate an inflammatory response in macrophages. Nuclear factor erythroid-derived 2 - like factor 2 (Nrf2) signaling and its regulated antioxidant genes play critical roles in maintaining redox homeostasis. In this study we investigated the regulation of four representative Nrf2-regulated antioxidant genes; i.e., glutamate cysteine ligase (GCL) catalytic subunit (GCLC), GCL modifier subunit (GCLM), heme oxygenase 1 (HO-1), and NAD(P)H:quinone oxidoreductase-1 (NQO-1), by iron-coated silica nanoparticles (SiO2-Fe) in human THP-1 macrophages. We found that the expression of these four antioxidant genes was modified by SiO2-Fe in a time-dependent manner. At 6h, their expression was unchanged except for GCLC, which was reduced compared with controls. At 18h, the expression of these antioxidant genes was significantly increased compared with controls. In contrast, the Nrf2 activator sulforaphane induced all antioxidant genes at as early as 3h. The nuclear translocation of Nrf2 occurred later than that for NF-κB p65 protein and the induction of proinflammatory cytokines (TNFα and IL-1β). NF-κB inhibitor SN50 prevented the reduction of GCLC at 6h and abolished the induction of antioxidant genes at 18h by SiO2-Fe, but did not affect the basal and sulforaphane-induced expression of antioxidant genes, suggesting that NF-κB signaling plays a key role in the induction of Nrf2-mediated genes in response to SiO2-Fe. Consistently, SN50 inhibited the nuclear translocation of Nrf2 caused by SiO2-Fe. In addition, Nrf2 silencing decreased the basal and SiO2-induced expression of the four reprehensive antioxidant genes. Taken together, these data indicated that SiO2-Fe induced a delayed response of Nrf2-regulated antioxidant genes, likely through NF-κB-Nrf2 interactions.

DNA Oncogenic Virus-Induced Oxidative Stress, Genomic Damage, and Aberrant Epigenetic Alterations

Approximately 20% of human cancers is attributable to DNA oncogenic viruses such as human papillomavirus (HPV), hepatitis B virus (HBV), and Epstein-Barr virus (EBV). Unrepaired DNA damage is the most common and overlapping feature of these DNA oncogenic viruses and a source of genomic instability and tumour development. Sustained DNA damage results from unceasing production of reactive oxygen species and activation of inflammasome cascades that trigger genomic changes and increased propensity of epigenetic alterations. Accumulation of epigenetic alterations may interfere with genome-wide cellular signalling machineries and promote malignant transformation leading to cancer development. Untangling and understanding the underlying mechanisms that promote these detrimental effects remain the major objectives for ongoing research and hope for effective virus-induced cancer therapy. Here, we review current literature with an emphasis on how DNA damage influences HPV, HVB, and EBV replication and epigenetic alterations that are associated with carcinogenesis.

Surface modification minimizes the toxicity of silver nanoparticles: an in vitro and in vivo study

Currently toxicological research in Silver nanoparticle is a leading issue in medical science. The surface chemistry and physical dimensions of silver nanoparticles (Ag-NPs) play an important role in toxicity. The aim of this present study was to evaluate the in vitro and in vivo toxicity of Ag-NPs as well as the alteration of toxicity profile due to surface functionalization (PEG and BSA) and the intracellular signaling pathways involved in nanoparticles mediated oxidative stress and apoptosis in vitro and in vivo system. Ag-NPs released excess Ag⁺ ions leads to activation of NADPH oxidase and helps in generating the reactive oxygen species (ROS). Silver nanoparticles elicit the production of excess amount of ROS results activation of TNF-α. Ag-NPs activates caspase-3 and 9 which are the signature of mitochondrial pathway. Ag-NPs are responsible to decrease the antioxidant enzymes and imbalance the oxidative status into the cells but functionalization with BSA and PEG helps to protect the adverse effect of Ag-NPs on the cells. This study suggested that Ag-NPs are toxic to normal cells which directly lead with human health. Surface functionalization may open the gateway for further use of Ag-NPs in different area such as antimicrobial and anticancer therapy, industrial use or in biomedical sciences.

Protective effect of crocin and voluntary exercise against oxidative stress in the heart of high-fat diet-induced type 2 diabetic rats

Background Oxidative stress plays a critical role in the pathogenesis and progression of type 2 diabetes and diabetic-associated cardiovascular complications. This study investigated the impact of crocin combined with voluntary exercise on heart oxidative stress indicator in high-fat diet-induced type 2 diabetic rats. Materials and methods Rats were divided into four groups: diabetes, diabetic-crocin, diabetic-voluntary exercise, diabetic-crocin-voluntary exercise. Type 2 diabetes was induced by high-fat diet (4 weeks) and injection of streptozotocin (intraperitoneally, 35 mg/kg). Animals received crocin orally (50 mg/kg); voluntary exercise was performed alone or combined with crocin treatment for 8 weeks. Finally, malondialdehyde (MDA), activity of antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were measured spectrophotometrically. Results Treatment of diabetic rats with crocin and exercise significantly decreased the levels of MDA (p < 0.001) and increased the activity of SOD, GPx, and CAT compared with the untreated diabetic group. In addition, combination of exercise and crocin amplified their effect on antioxidant levels in the heart tissue of type 2 diabetic rats. Conclusion We suggest that a combination of crocin with voluntary exercise treatment may cause more beneficial effects in antioxidant defense system of heart tissues than the use of crocin or voluntary exercise alone.

CTRP3 attenuates cardiac dysfunction, inflammation, oxidative stress and cell death in diabetic cardiomyopathy in rats

AIMS/HYPOTHESIS

Oxidative stress, inflammation and cell death are closely involved in the development of diabetic cardiomyopathy (DCM). C1q/tumour necrosis factor-related protein-3 (CTRP3) has anti-inflammatory properties but its role in DCM remains largely unknown. The aims of this study were to determine whether CTRP3 could attenuate DCM and to clarify the underlying mechanisms.

METHODS

Streptozotocin (STZ) was injected intraperitoneally to induce diabetes in Sprague-Dawley rats. Cardiomyocyte-specific CTRP3 overexpression was achieved using an adeno-associated virus system 12 weeks after STZ injection.

RESULTS

CTRP3 expression was significantly decreased in diabetic rat hearts. Knockdown of CTRP3 in cardiomyocytes at baseline resulted in increased oxidative injury, inflammation and apoptosis in vitro. Cardiomyocyte-specific overexpression of CTRP3 decreased oxidative stress and inflammation, attenuated myocyte death and improved cardiac function in rats treated with STZ. CTRP3 significantly activated AMP-activated protein kinase α (AMPKα) and Akt (protein kinase B) in H9c2 cells. CTRP3 protected against high-glucose-induced oxidative stress, inflammation and apoptosis in vitro. AMPKα deficiency abolished the protective effects of CTRP3 in vitro and in vivo. Furthermore, we found that CTRP3 activated AMPKα via the cAMP-exchange protein directly activated by cAMP (EPAC)-mitogen-activated protein kinase kinase (MEK) pathway.

CONCLUSIONS/INTERPRETATION

CTRP3 protected against DCM via activation of the AMPKα pathway. CTRP3 has therapeutic potential for the treatment of DCM.

Pulmonary toxicity following acute coexposures to diesel particulate matter and α-quartz crystalline silica in the Sprague-Dawley rat

The effects of acute pulmonary coexposures to silica and diesel particulate matter (DPM), which may occur in various mining operations, were investigated in vivo. Rats were exposed by intratracheal instillation (IT) to silica (50 or 233 µg), DPM (7.89 or 50 µg) or silica and DPM combined in phosphate-buffered saline (PBS) or to PBS alone (control). At one day, one week, one month, two months and three months postexposure bronchoalveolar lavage and histopathology were performed to assess lung injury, inflammation and immune response. While higher doses of silica caused inflammation and injury at all time points, DPM exposure alone did not. DPM (50 µg) combined with silica (233 µg) increased inflammation at one week and one-month postexposure and caused an increase in the incidence of fibrosis at one month compared with exposure to silica alone. To assess susceptibility to lung infection following coexposure, rats were exposed by IT to 233 µg silica, 50 µg DPM, a combination of the two or PBS control one week before intratracheal inoculation with 5 × 105 Listeria monocytogenes. At 1, 3, 5, 7 and 14 days following infection, pulmonary immune response and bacterial clearance from the lung were evaluated. Coexposure to DPM and silica did not alter bacterial clearance from the lung compared to control. Although DPM and silica coexposure did not alter pulmonary susceptibility to infection in this model, the study showed that noninflammatory doses of DPM had the capacity to increase silica-induced lung injury, inflammation and onset/incidence of fibrosis.

Nanotoxicity in Systemic Circulation and Wound Healing

Nanotoxicity of nanomaterials is an important issue in view of their potential applications in systemic circulation and wound healing dressing. This account specifically deals with several characteristic features of different nanomaterials which induce hemolysis and how to make them hemocompatible. The shape, size, and surface functionalities of naked metallic as well as nonmetallic nanoparticles surfaces are responsible for the hemolysis. An appropriate coating of biocompatible molecules dramatically reduces hemolysis and promotes their ability as safe drug delivery vehicles. The use of coated nanomaterials in wound healing dressing opens several new strategies for rapid wound healing processes. Properly designed nanomaterials should be selected to minimize the nanotoxicity in the wound healing process. Future directions need new synthetic methods for engineered nanomaterials for their best use in nanomedicine and nanobiotechnology.

Effects of Occupational Silica Exposure on OXIDATIVE Stress and Immune System Parameters in Ceramic Workers in TURKEY

Silica is the second most common element after oxygen, and therefore, exposures to crystalline silica dust occur in a large variety of occupations such as metal foundries, constructions, and ceramic, quarry, and pottery industries. Since crystalline silica exposure has been linked with silicosis, lung cancer, and other pulmonary diseases, adverse effect attributed to this element has be a cause for concern worldwide. Silica dust exposure in workers is still considered to be important health problem especially in developing countries. The aim of the study was to investigate the effects of occupational silica exposure on oxidative stress parameters including the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and levels of total glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) as well as immune system parameters such as interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, and IL-10 and tumor necrosis factor (TNF)-α in Turkish ceramic workers. In this study, nearly 50% of Turkish ceramic workers were diagnosed with silicosis. Eighty-four percent of these silicotic workers were found to present with profusion category 1 silicosis, whereas controls (n = 81) all displayed normal chest radiographs. Data demonstrated a significant decrease in levels of GSH and activities of CAT, SOD, and GPx, but a significant increase in MDA levels and activity of GR in all workers. Further, workers possessed significantly higher levels of IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, and TNF-α. These observations suggest that ceramic workers may have impaired antioxidant/oxidant status and activated immune system indicative of inflammatory responses.

Extra-Large Pore Mesoporous Silica Nanoparticles for Directing in Vivo M2 Macrophage Polarization by Delivering IL-4

Over the past decade, mesoporous silica nanoparticles (MSNs) smaller than 200 nm with a high colloidal stability have been extensively studied for systemic drug delivery. Although small molecule delivery via MSNs has been successful, the encapsulation of large therapeutic biomolecules, such as proteins or DNA, is limited due to small pore size of the conventional MSNs obtained by soft-templating. Here, we report the synthesis of mesoporous silica nanoparticles with extra-large pores (XL-MSNs) and their application to in vivo cytokine delivery for macrophage polarization. Uniform, size-controllable XL-MSNs with 30 nm extra-large pores were synthesized using organic additives and inorganic seed nanoparticles. XL-MSNs showed significantly higher loadings for the model proteins with different molecular weights compared to conventional small pore MSNs. XL-MSNs were used to deliver IL-4, which is an M2-polarizing cytokine and very quickly degraded in vivo, to macrophages and polarize them to anti-inflammatory M2 macrophages in vivo. XL-MSNs induced a low level of reactive oxygen species (ROS) production and no pro-inflammatory cytokines in bone marrow-derived macrophages (BMDMs) and in mice injected intravenously with XL-MSNs. We found that the injected XL-MSNs were targeted to phagocytic myeloid cells, such as neutrophils, monocytes, macrophages, and dendritic cells. Finally, we demonstrated that the injection of IL-4-loaded XL-MSNs successfully triggered M2 macrophage polarization in vivo, suggesting the clinical potential of XL-MSNs for modulating immune systems via targeted delivery of various cytokines.

Association between SNPs at IL-17A and IL-17F and susceptibility to accelerated silicosis

The association between single nucleotide polymorphisms (SNPs) in the interleukin (IL)-17 gene and silicosis has been evaluated in different populations. The aim of the present study was to analyze the association between SNPs at IL-17A (−832A/G) and IL-17F (+7488A/G) and susceptibility to accelerated silicosis in the Iranian Kurdish population. We studied 48 patients with accelerated silicosis and 62 controls. Genomic DNA was isolated using the “salting out” method. PCR-RFLP was performed for all SNPs typing. The frequencies of A/A, A/G, and G/G genotypes at IL-17A (−832A/G) were 4 (8.33%), 23 (47.92%), and 21 (43.75%) in patients and 5 (8.06%), 35 (56.45%), and 22 (35.48%) in controls, respectively. The frequencies of A and G alleles at IL-17 (−832A/G) were 31 (32.29%) and 65 (67.71%) in patients, and 45 (36.29%) and 79 (63.71%) in the controls, respectively. The frequencies of A/A, A/G, and G/G genotypes at IL-17F (+7488A/G) were 1 (2.08%), 47 (97.92%), and 0 (0%) in patients, and 11 (17.74%), 51 (82.26%), and 0 (0%) in the controls, respectively. The frequencies of A and G alleles at IL-17F (+7488A/G) were 49 (51.04%) and 47 (48.96%) in patients, and 73 (58.87%) and 51 (41.13%) in the controls, respectively. IL-17F (+7488A/G) genotype was more frequent among the cases compared with controls (97.92% vs. 82.26%). The frequency of the IL-17F (+7488A/G) genotype was significantly greater in patients with accelerated silicosis (odds ratio = 10.13 95%; confidence interval = 1.2–81.5; p = 0.008). The IL-17F (+7488A/G) genotype revealed a significantly increased risk of accelerated silicosis ( p < 0.05). The IL-17F (+7488 G) allele was associated with an increased risk of accelerated silicosis, but in the case of the IL-17A (−832A/G) polymorphism, a significant association was not observed.

Evaluation of Dynamic Disulphide/Thiol Homeostasis in Silica Exposed Workers

BACKGROUND

Oxidative stress is implicated as one of the main molecular mechanism underlying silicosis.

AIMS

In this study, our aim was to asses the redox status in occupationally silica-exposed workers, by evaluating the dynamic thiol-disulphide homeostasis.

STUDY DESIGN

Case-control study.

METHODS

Thirty-six male workers occupationally exposed to silica particles and 30 healthy volunteers, working as office workers were included to the study. Posteroanterior chest radiographs and pulmonary function tests of both groups were evaluated. Also serum thiol disulphide levels were measured using the spectrophotometric method described by Erel and Neşelioğlu.

RESULTS

Among the 36 workers that underwent pulmonary function tests 6 (17%) had obstructive, 7 (19%) had restrictive, 6 (17%) had obstructive and restrictive signs whereas 17 (47%) had no signs. The mean PFTs results of silica-exposed workers were significantly lower than control subjects. The serum disulphide levels of silica-exposed workers were significantly higher than control subjects (23.84±5.89 μmol/L and 21.18±3.44 μmol/L, respectively p=0.02).

CONCLUSION

The serum disulphide levels, a biomarker of oxidative stress, are found to be higher in silica-exposed workers.

Cytotoxic, genotoxic and mutagenic evaluation of surface waters from a coal exploration region

Coal mining generates a considerable amount of waste, which is disposed of in piles or dams near mining sites. As a result, leachates may reach rivers and streams, promoting the wide dispersion of contaminants in solution and as particulate matter. The present study evaluated the cytotoxic, genotoxic, and mutagenic action of surface waters collected around a thermoelectric power plant and the largest mining area in Brazil (Candiota). Four sites in Candiota stream were selected, and samples were collected in winter and summer. Water samples were analyzed using the comet and CBMN assays in V79 and HepG2 cells. Furthermore, genotoxicity of water samples was evaluated in vivo using the SMART in Drosophila melanogaster. In addition, polycyclic aromatic hydrocarbons and inorganic elements were quantified. The results indicate that water samples exhibited no genotoxic and mutagenic activities, whether in vitro or in vivo. On the other hand, surface water samples collected in sites near the power plant in both summer and winter inhibited cell proliferation and induced increased frequencies of V79 cell death, apoptosis, and necrosis. The cytotoxicity observed may be associated with the presence of higher concentration of inorganic elements, especially aluminum, silicon, sulfur, titanium and zinc at sites 1 and 2 in the stream, as well as with the complex mixture present in the coal, in both seasons. Therefore, the results obtained point to the toxicity potential of water samples with the influence of coal mining and combustion processes and the possible adverse effects on the health of exposed organisms.

Ameliorative Effects of Dietary Selenium Against Cadmium Toxicity Is Related to Changes in Trace Elements in Chicken Kidneys

The ameliorative effects of selenium (Se) against cadmium (Cd)-induced toxicity have been reported extensively. However, few studies have assessed the effects of multiple ions simultaneously on the variations of elements. In this study, the changes in Se, Cd, and 26 other element concentrations were investigated in chicken kidneys. One hundred and twenty-eight 31-week-old laying hens were fed a diet supplemented with either Se, Cd, or both Se and Cd for 90 days. The ion content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). We found that the Se, Cd, and combined Se and Cd treatments significantly affected the trace elements in the chicken kidneys. The Cd supplement caused ion profile disorders, including reduced concentrations of V, Cr, Mn, Mo, As, Ba, Hg, Ti, and Pb and increased Si, Cu, Li, Cd, and Sb. The Se supplement reduced the contents of Co, Mo, and Pb and increased the contents of Cr, Fe, and Se. Moreover, Se also increased the concentrations of Cr, Mn, Zn, and Se and decreased those of Li and Pb, which in contrast were induced by Cd. Complex interactions between elements were analyzed, and both positive and negative correlations among these elements are presented. The present study indicated that Se can help against the negative effects of Cd and may be related to the homeostasis of the trace elements in chicken kidneys.

Bosutinib Therapy Ameliorates Lung Inflammation and Fibrosis in Experimental Silicosis

Silicosis is an occupational lung disease for which no effective therapy exists. We hypothesized that bosutinib, a tyrosine kinase inhibitor, might ameliorate inflammatory responses, attenuate pulmonary fibrosis, and thus improve lung function in experimental silicosis. For this purpose, we investigated the potential efficacy of bosutinib in the treatment of experimental silicosis induced in C57BL/6 mice by intratracheal administration of silica particles. After 15 days, once disease was established, animals were randomly assigned to receive DMSO or bosutinib (1 mg/kg/dose in 0.1 mL 1% DMSO) by oral gavage, twice daily for 14 days. On day 30, lung mechanics and morphometry, total and differential cell count in alveolar septa and granuloma, levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-4, transforming growth factor (TGF)-β, and vascular endothelial growth factor in lung homogenate, M1 and M2 macrophages, total leukocytes, and T cells in BALF, lymph nodes, and thymus, and collagen fiber content in alveolar septa and granuloma were analyzed. In a separate in vitro experiment, RAW264.7 macrophages were exposed to silica particles in the presence or absence of bosutinib. After 24 h, gene expressions of arginase-1, IL-10, IL-12, inducible nitric oxide synthase (iNOS), metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1, and caspase-3 were evaluated. In vivo, in silicotic animals, bosutinib, compared to DMSO, decreased: (1) fraction area of collapsed alveoli, (2) size and number of granulomas, and mononuclear cell granuloma infiltration; (3) IL-1β, TNF-α, IFN-γ, and TGF-β levels in lung homogenates, (4) collagen fiber content in lung parenchyma, and (5) viscoelastic pressure and static lung elastance. Bosutinib also reduced M1 cell counts while increasing M2 macrophage population in both lung parenchyma and granulomas. Total leukocyte, regulatory T, CD4⁺, and CD8⁺ cell counts in the lung-draining lymph nodes also decreased with bosutinib therapy without affecting thymus cellularity. In vitro, bosutinib led to a decrease in IL-12 and iNOS and increase in IL-10, arginase-1, MMP-9, and TIMP-1. In conclusion, in the current model of silicosis, bosutinib therapy yielded beneficial effects on lung inflammation and remodeling, therefore resulting in lung mechanics improvement. Bosutinib may hold promise for silicosis; however, further studies are required.

Enhanced cellular uptake of size-separated lipophilic silicon nanoparticles

Specific size, shape and surface chemistry influence the biological activity of nanoparticles. In the case of lipophilic nanoparticles, which are widely used in consumer products, there is evidence that particle size and formulation influences skin permeability and that lipophilic particles smaller than 6 nm can embed in lipid bilayers. Since most nanoparticle synthetic procedures result in mixtures of different particles, post-synthetic purification promises to provide insights into nanostructure-function relationships. Here we used size-selective precipitation to separate lipophilic allyl-benzyl-capped silicon nanoparticles into monodisperse fractions within the range of 1 nm to 5 nm. We measured liposomal encapsulation and cellular uptake of the monodisperse particles and found them to have generally low cytotoxicities in Hela cells. However, specific fractions showed reproducibly higher cytotoxicity than other fractions as well as the unseparated ensemble. Measurements indicate that the cytotoxicity mechanism involves oxidative stress and the differential cytotoxicity is due to enhanced cellular uptake by specific fractions. The results indicate that specific particles, with enhanced suitability for incorporation into lipophilic regions of liposomes and subsequent in vitro delivery to cells, are enriched in certain fractions.

The Role of Reactive Oxygen Species (ROS) in the Biological Activities of Metallic Nanoparticles

Nanoparticles (NPs) possess unique physical and chemical properties that make them appropriate for various applications. The structural alteration of metallic NPs leads to different biological functions, specifically resulting in different potentials for the generation of reactive oxygen species (ROS). The amount of ROS produced by metallic NPs correlates with particle size, shape, surface area, and chemistry. ROS possess multiple functions in cellular biology, with ROS generation a key factor in metallic NP-induced toxicity, as well as modulation of cellular signaling involved in cell death, proliferation, and differentiation. In this review, we briefly explained NP classes and their biomedical applications and describe the sources and roles of ROS in NP-related biological functions in vitro and in vivo. Furthermore, we also described the roles of metal NP-induced ROS generation in stem cell biology. Although the roles of ROS in metallic NP-related biological functions requires further investigation, modulation and characterization of metallic NP-induced ROS production are promising in the application of metallic NPs in the areas of regenerative medicine and medical devices.

A ROS-responsive polymeric micelle with a π-conjugated thioketal moiety for enhanced drug loading and efficient drug delivery

As the implications of reactive oxygen species (ROS) are elucidated in many diseases, ROS-responsive nanoparticles are attracting great interest from researchers.

Single Cell Analysis of Phagocytosis, Phagosome Maturation, Phagolysosomal Leakage, and Cell Death Following Exposure of Macrophages to Silica Particles

Chronic inhalation of silica in various occupational settings results in the development of silicosis, a disease characterized by lung fibrosis. Uptake of silica particles by alveolar macrophages results in cell death and this is one of the contributing factors to the development of silicosis. We have characterized the uncoated or protein-coated (non-opsonized) and Fc receptor-mediated (antibody-opsonized) routes of silica phagocytosis and toxicity. Numerous microscopy techniques and fluorescent probes are outlined in this chapter to carefully measure particle uptake, by macrophages, phagosome maturation, phagosomal reactive oxygen species generation, phagolysosomal leakage, and cell death.

Understanding Toxicity of Nanomaterials in Biological Systems

Nanotechnology is a growing applied science having considerable global socioeconomic value. Nanoscale materials are casting their impact on almost all industries and all areas of society. A wide range of engineered nanoscale products has emerged with widespread applications in fields such as energy, medicine, electronics, plastics, energy and aerospace etc. While the market for nanotechnology products will have grown over one trillion US dollars by 2015, the presence of these material is likely to increase leading to increasing likelihood of exposure. The direct use of nanomaterials in humans for medical and cosmetic purposes dictates vigorous safety assessment of toxicity. Therefore this book chapter provides the detailed toxicity assessment of various types of nanomaterials.