Differences in impact on disease or lung injury depending on the physicochemical characteristics of harmful chemicals in the PAH model.

The number of individuals with underlying medical conditions has been increasing steadily. These individuals are relatively vulnerable to harmful external factors. But it has not been proven that the effects of hazardous chemicals may differ depending on their physicochemical properties. This study determines the toxic effects of two chemicals with high indoor exposure risk and different physicochemical properties on an underlying disease model. A pulmonary arterial hypertension (PAH) model was constructed by a single subcutaneous injection of monocrotaline (MCT; 60 mg/kg) into Sprague-Dawley rats. After three weeks, formaldehyde (FA; 2.5 mg/kg) and polyhexamethylene guanidine (PHMG; 0.05 mg/kg) were administered once via intratracheal instillation, and rats were necropsied one week later. Exposure to FA and PHMG affected organ weight and the Fulton and toxicity indices in rats induced with PAH. FA promoted bronchial injury and aggravated PAH, while PHMG only induced alveolar injury. Additionally, the differentially expressed genes were altered following exposure to FA and PHMG, as were the associated diseases (cardiovascular disease and pulmonary fibrosis, respectively). In conclusion, inhaled chemicals with different physicochemical properties can cause damage to organs, such as the lungs and heart, and can aggravate underlying diseases. This study elucidates indoor inhaled exposure-induced toxicities and alerts patients with pre-existing diseases to the harmful chemicals.

Repeated intratracheal instillation of whole-cigarette smoke condensate to assess lung damage in a rat model.

Cigarette smoke induces an inflammatory response in the lungs by recruiting inflammatory cells, leading to lung diseases such as lung cancer, chronic obstructive pulmonary disease, and pulmonary fibrosis. Existing inhalation exposure methods for assessing the adverse effects of cigarette smoke require expensive equipment and are labor-intensive. Therefore, we attempted to develop a novel method to assess these adverse effects using intratracheal instillation (ITI) of whole cigarette smoke condensate (WCSC). The WCSC (0, 5, 10, or 20 mg/mL) was administered by ITI once daily for 6 or 12 days using an automatic video instillator. Repeated WCSC ITI increased the lung weight, and monocyte chemoattractant protein-1 (MCP-1), neutrophil, and lymphocyte levels within bronchoalveolar lavage fluid compared to the control. In the histopathological analysis of the lung tissue, a mild inflammatory response was observed in the 6 and 12 days 20 mg/mL WCSC exposure groups. The genome-wide RNA-seq expression patterns revealed that inflammatory and immune response-related genes, such as the chemokine signaling pathway, Th1/Th2 cell differentiation, and cytokine-cytokine receptor interaction, were employed following WCSC exposure. In addition, MCP-1 was time-dependent and increased in the 10 mg/mL exposure group compared to the control group. These results suggested that the WCSC might induce the potential pulmonary inflammatory response. Furthermore, we proposed that ITI may be a rapid and effective method of evaluating the adverse effects of WCSC within a short exposure period (less than 2 weeks), and it can be used to evaluate cigarette inhalation toxicity studies as an alternative method.

Pulmonary inflammation and cellular responses following exposure to benzalkonium chloride: Potential impact of disrupted pulmonary surfactant homeostasis.

Benzalkonium chloride (BKC) is a prototypical quaternary ammonium disinfectant. Previously, we suggested a no lethal dose level (0.005%) and an LD50 range (0.5-0.05%) of BKC following a single pharyngeal aspiration. Herein, we exposed BKC repeatedly by pharyngeal aspiration for 14 days (0.005 and 0.01%, female mice, total five times with interval of two days, 5 mice/group) and 28 days (0, 0.001, 0.005, and 0.01%, male and female mice, weekly, 16 mice/sex/group). Death following 14 days-repeated exposure did not occur. Meanwhile, chronic pathological lesions were observed in the lung tissues of mice exposed to BKC for 28 days. The total number of bronchial alveolar lavage cells increased, and pulmonary homeostasis of immunologic messenger molecules was disturbed. Following, we investigated BKC-induced cellular responses using human bronchial epithelial cells. The cytotoxicity increased rapidly with concentration. Lysosomal volume, NO production, and lipid peroxidation increased in BKC-treated cells, whereas intracellular ROS level decreased accompanying structural and functional damage of mitochondria. We also found that BKC affected the expression level of immune response, DNA damage, and amino acid biosynthesis-related molecules. More interestingly, lamellar body- and autophagosome-like structures were notably observed in cells exposed to BKC, and necrotic and apoptotic cell death were identified accompanying cell accumulation in the G2/M phase. Therefore, we suggest that repeated respiratory exposure of BKC causes pulmonary inflammation and lung tissue damage and that dead and damaged cells may contribute to the inflammatory response. In addition, the formation process of lamellar body-like structures may function as a key toxicity mechanism.

Disruption of Membrane Integrity as a Molecular Initiating Event Determines the Toxicity of Polyhexamethylene Guanidine Phosphate Depending on the Routes of Exposure.

Polyhexamethylene guanidine phosphate (PHMG-P), a cationic biocide, is widely used in household products due to its strong bactericidal activity and low toxicity. However, it causes fatal lung damage when inhaled. In this study, we investigated why PHMG-P causes fatal lung injury when inhaled, and demonstrated that the disruption of membrane integrity through ionic interaction-a molecular initiating event of PHMG-P-determines toxicity. Mice were injected intravenously with 0.9 or 7.2 mg/kg PHMG-P (IV group), or instilled intratracheally with 0.9 mg/kg PHMG-P (ITI group); they were euthanatized at 4 h and on days 1 and 7 after treatment. Increased total BAL cell count and proinflammatory cytokine production, along with fibrotic changes in the lungs, were detected in the ITI group only. Levels of hepatic enzymes and hepatic serum amyloid A mRNA expression were markedly upregulated in the 7.2 mg/kg IV and ITI groups at 4 h or day 1 after treatment, but returned to baseline. No pathological findings were detected in the heart, liver, or kidneys. To simulate the IV injection, A549, THP-1, and HepG2 cells were treated with PHMG-P in cell culture media supplemented with different serum concentrations. Increased serum concentration was associated with an increase in cell viability. These results support the idea that direct contact between PHMG-P and cell membranes is necessary for PHMG-induced toxicity.

Reference value of hematologic, urologic, and organ weights of 2- to 4-year-old long-tailed macaques (Macaca fascicularis fascicularis) in the context of toxicological studies.

BACKGROUND: The long-tailed macaque (Macaca fascicularis fascicularis) is an Old World species, which is one among the most commonly used monkeys for pharmaceutical research. However, most of the available background data are not suitable for good laboratory practice (GLP)-regulated drug safety tests because the current reverence value covers fewer indices than necessary. Therefore, in this study, historical data for preclinical safety test were collected and managed. METHODS: Twenty-five hematology, 20 clinical chemistry, 19 urine analysis, and 16 organ weights were evaluated in a drug safety test of 228 male and 140 female 2- to 4-year-old long-tailed macaques at the Korea Institute of Toxicology under GLP regulations. RESULTS: The absolute and relative count of lymphocyte, basophil, and large unstained cell were higher, whereas neutrophil was lower in male than in female monkeys. In serum biochemistry, IP, GGT, ALP, and TCHO of male were higher than female. CONCLUSION: Historical data suitable for preclinical safety analysis were determined.

Toxicity of orally administered food-grade titanium dioxide nanoparticles.

This year, France banned the application of titanium dioxide nanoparticles as a food additive (hereafter, E171) based on the insufficient oral toxicity data. Here, we investigated the subchronic toxic responses of E171 (0, 10, 100, and 1,000 mg/kg) and tried to elucidate the possible toxic mechanism using AGS cells, a human stomach epithelial cell line. There were no dose-related changes in the Organisation for Economic Cooperation and Development test guideline-related endpoints. Meanwhile, E171 deeply penetrated cells lining the stomach tissues of rats, and the IgM and granulocyte-macrophage colony-stimulating factor levels were significantly lower in the blood from rats exposed to E171 compared with the control. The colonic antioxidant protein level decreased with increasing Ti accumulation. Additionally, after 24-h exposure, E171 located in the perinuclear region of AGS cells and affected expression of endoplasmic reticulum stress-related proteins. However, cell death was not observed up to the used maximum concentration. A gene profile analysis also showed that immune response-related microRNAs were most strongly affected by E171 exposure. Collectively, we concluded that the NOAEL of E171 for 90 days repeated oral administration is between 100 and 1,000 mg/kg for both male and female rats. Additionally, further study is needed to clarify the possible carcinogenesis following the chronic accumulation in the colon.

Four-week repeated dose oral toxicity study of KDS2010, a novel selective monoamine oxidase B inhibitor, in Sprague Dawley rats.

Repeated dose oral toxicity and toxicokinetic of KDS2010, a new drug for Parkinson's disease, was investigated after 4-week repeated oral administration at 30, 50, 75, or 100 mg/kg/day in rats. Body weight and body weight gain decreased in rats of both sexes in the 75 and 100 mg/kg groups, and food consumption was reduced in male rats of the 75 and 100 mg/kg male groups. Histological alterations were observed in the kidney (urothelial hyperplasia, inflammatory cell infiltration in the renal pelvis, tubular vacuolation/degeneration, basophilic tubules, and hyaline droplets in the proximal tubules) of the 75 and 100 mg/kg male groups and the 50 and 100 mg/kg female groups. The 75 and 100 mg/kg male groups showed adverse effect in the testes (degeneration/exfoliation of germ cells, seminiferous tubules atrophy) and epididymis (cellular debris, oligospermia). These changes were partially recovered after a 2-week recovery period. However, basophilic tubules and hyaline droplets in the proximal tubules in the kidney and germ cell degeneration/exfoliation in the testis were not recovered. In toxicokinetics study, systemic exposure to KDS2010 increased proportionally in both sexes by in a dose -dependent manner. In addition, repeated administration for 4 weeks led to increased tendency of systemic exposure in both sexes compared with that in Day 1. In conclusion, KDS2010 was shown to target the kidney and testis with a no-observed-adverse-effect level of 50 and 30 mg/kg/day for males and females, respectively.

Thirteen-week oral toxicity study of fermented ginseng, GBCK25, in Sprague-Dawley rats.

Ginseng (Panax ginseng) is commonly used in Asia as a medicinal herb. In particular, fermented ginseng, GBCK25, has been recently developed to increase ginsenoside absorption. It also has other beneficial biological effects such as hemodynamic and anti-inflammation functions. Here, we investigated the potential toxicity of GBCK25 in Sprague-Dawley rats following 13 weeks of GBCK25 treatment by oral gavage at doses of 250, 500, or 1000 mg/kg/day and reversible toxic effects over a 4-week recovery phase. Ten male and female rats per group were randomly allocated to the main toxicology groups and five male and female rats per group were allocated to the 0 and 1000 mg/kg/day recovery groups, respectively. There was no mortality; significant clinical toxicity or microscopic findings; and changes in body weight, food consumption, hematological parameters, serum biochemistry, or absolute and relative organ weights in any of the groups. In conclusion, there were no toxicological changes upon repeated oral gavage of GBCK25 at doses of 250, 500, or 1000 mg/kg/day in Sprague-Dawley rats over 13 weeks. The no-observed-adverse-effect level of GBCK25 was 1000 mg/kg/day in both sexes of Sprague-Dawley rat.

The formation of lamellar body-like structures may be a trigger of cetylpyridinium chloride-induced cell death and inflammatory response.

Cetylpyridinium chloride (CPC) is a quaternary ammonium compound used widely in health and personal care products. Meanwhile, due to its increasing use, its potential adverse health effects are emerging as a topic of public concern. In this study, we first administered CPC by pharyngeal aspiration to determine the survival level (the maximum concentration at which no death is observed) and then administered CPC to mice repeatedly for 28 days using the survival level as the highest concentration. CPC increased the total number of pulmonary cells secreting pro- and anti-inflammatory cytokines and chemokines. Infiltration of inflammatory cells, production of foamy alveolar macrophages, and chronic inflammatory lesions were found in the lung tissue of male and female mice exposed to the highest dose of CPC. We also investigated the toxicity mechanism using BEAS-2B cells isolated from normal human bronchial epithelium. At 6 h after exposure to CPC, the cells underwent non-apoptotic cell death, especially at concentrations greater than 2 µg/mL. The expression of the transferrin receptor was remarkably enhanced, and the expression of proteins that contribute to intracellular iron storage was inhibited. The expression of both mitochondrial SOD and catalase increased with CPC concentration, and PARP protein was cleaved, suggesting possible DNA damage. In addition, the internal structure of mitochondria was disrupted, and fusion between damaged organelles was observed in the cytoplasm. Most importantly, lamellar body-like structures and autophagosome-like vacuoles were found in CPC-treated cells, with enhanced expression of ABCA3 protein, a marker for lamellar body, and a docking score between ABCA3 protein and CPC was considered to be approximately -6.8969 kcal/mol. From these results, we propose that mitochondrial damage and iron depletion may contribute to CPC-induced non-apoptotic cell death and that pulmonary accumulation of cell debris may be closely associated with the inflammatory response. Furthermore, we hypothesize that the formation of lamellar body-like structures may be a trigger for CPC-induced cell death.

Exposure to polyhexamethyleneguanidine phosphate in early life dampens pulmonary damage compared to adult mice.

Polyhexamethyleneguanidine phosphate (PHMG-P) is a biocide of guanidine family that can cause a fatal lung damage if exposed directly to the lungs. No reports exist regarding the toxicity of PHMG-P in neonatal animals. Therefore, this study aimed to determine PHMG-P toxicity in neonatal and 8-week-old mice after they were intranasally instilled with 1.5 mg/kg, 3 mg/kg, and 4.5 mg/kg PHMG-P. PHMG-P lung exposure resulted in more severe pulmonary toxicity in adult mice than in newborn mice. In the high-dose group of newborn mice, a minimal degree of inflammatory cell infiltration and fibrosis in the lung were detected, whereas more severe pathological lesions including granulomatous inflammation, fibrosis, and degeneration of the bronchiolar epithelium were observed in adult mice. At day 4, C-C motif chemokine ligand 2 (CCL2), a potent chemokine for monocytes, was upregulated but recovered to normal levels at day 15 in newborn mice. However, increased CCL2 and IL-6 levels were sustained at day 15 in adult mice. When comparing the differentially expressed genes of newborn and adult mice through RNA-seq analysis, there were expression changes in several genes associated with inflammation in neonates that were similar or different from those in adults. Although no significant lung damage occurred in newborns, growth inhibition was observed which was not reversed until the end of the experiment. Further research is needed to determine how growth inhibition from neonatal exposure to PHMG-P affects adolescent and young adult health.

Comparison of repeated toxicity of polyhexamethyleneguanidine phosphate, a causative agent of humidifier disinfectant tragedy, in young and adult mice.

Some drugs or chemicals exhibit different safety profiles in newborns/young children compared to adults. Polyhexamethyleneguanidine phosphate (PHMG-P) has been implicated in the humidifier disinfectant tragedy in 2011. There are limited reports on the toxicity of PHMG-P in neonatal animals. This study aimed to assess the toxicity of PHMG-P in neonates and to compare toxicity between young and adult mice. Mice aged 7-10 days and 8 weeks were anesthetized with isoflurane and then intranasally instilled with 0.9 mg/kg and 1.5 mg/kg PHMG-P once weekly for 4 weeks. The control group was given a corresponding volume of saline intranasally. Approximately 20 h after the 4th instillation, all mice (juveniles aged 28‒31 days and adults aged 11 weeks) were euthanized. Assessments included body weights, organ weights, cytokine production, and histopathological examinations. Both juvenile and adult mice exhibited significant pulmonary toxicity. There were no significant changes in body weight in either male or female juveniles, whereas adult mice experienced 5.0‒22.2% weight loss. However, lung weights increased in both age groups, accompanied by rises in cytokines and chemokines. Histopathological analyses revealed significant lung changes in both juvenile and adult mice, including immune cell infiltration, foamy macrophage, and granulomatous inflammation. PHMG-P is known to cause inflammation and fibrotic changes in rodents and humans that persist even during long recovery periods. Further research is required to explore the long-term health effects of PHMG-P following repeated early-life exposure.

Nicotinamide adenine dinucleotide phosphate oxidase 2 deletion attenuates polyhexamethylene guanidine-induced lung injury in mice.

Inhalation of polyhexamethylene guanidine phosphate (PHMG) can cause pulmonary fibrosis. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox) are enzymes that produce reactive oxygen species, which may be involved in tissue damage in various lung diseases. To investigate whether the Nox2 isoform of Nox is involved in the progression of PHMG-induced lung damage, we studied the contribution of Nox2 in PHMG-induced lung injury in Nox2-deficient mice. We treated wild-type (WT) and Nox2 knockout mice with a single intratracheal instillation of 1.1 mg/kg PHMG and sacrificed them after 14 days. We analyzed lung histopathology and the number of total and differential cells in the bronchoalveolar lavage fluid. In addition, the expressions of cytokines, chemokines, and profibrogenic genes were analyzed in the lung tissues. Based on our results, Nox2-deficient mice showed less PHMG-induced pulmonary damage than WT mice, as indicated by parameters such as body weight, lung weight, total cell count, cytokine and chemokine levels, fibrogenic mediator expression, and histopathological findings. These findings suggest that Nox2 may have the potential to contribute to PHMG-induced lung injury and serves as an essential signaling molecule in the development of PHMG-induced pulmonary fibrosis by regulating the expression of profibrogenic genes.

Toxicity of a novel antifungal agent (ATB1651 gel) in Yucatan minipigs (Sus scrofa) following 4 weeks of daily dermal administration.

ATB1651 gel is an antifungal drug candidate that enhances antifungal activity through substitution of several aryl rings, alkyl chains, and methyl groups. To ensure safety of use of ATB1651 gel, assessment of its potentially toxic side effects is necessary. In this study, we examined the repeated-dose toxicity of ATB1651 gel to Yucatan minipigs (Sus scrofa) in accordance with the Good Laboratory Practice guidelines. Five doses of ATB1651 gel (0%, 0.2%, 0.5%, 1.0%, 3.0%) were administered dermally to the left and right flanks of 38 minipigs daily for 4 weeks. Mortality, clinical symptoms, dermal scores, body weights, and physiological, biochemical, pathological, and toxicokinetic analyses were performed after the treatment period. No systemic toxicological damage was observed in either male or female minipigs regardless of dose; however, dermal application of ATB1651 gel caused some skin alterations at the application sites. Specifically, erythema and eschar formation, edema, and scabs or raise spots were observed at the application site(s) in males in the 3.0% ATB1651 gel treatment group and in females at ATB1651 gel concentrations ≥ 1.0%, with dermal scores ranging from grade 1 to 2. Additionally, histopathological assay indicated infiltration of different types of inflammatory cells and the presence of pustule/crust at the application site(s) in both males and females at ATB1651 gel concentrations ≥ 0.5%. However, these changes were reversible after a 2-week recovery period and were considered a local irritation effect of ATB1651 gel. The no-observed-adverse-effect level of ATB1651 gel was 3.0% with regard to topical and systemic toxicity in both male and female minipigs. Collectively, our results imply that ATB1651 gel is a safe candidate for clinical development as an antifungal drug with a wide therapeutic window.

General toxicity and screening of reproductive and developmental toxicity following bioaccumulation of oral-dosed perfluorooctanoic acid: Loss of the Golgi apparatus.

Despite its widespread use as a stabilizer across various industries over the past several decades, the health effects of chronic exposure to PFOA are still unclear. We administered PFOA by oral gavage (0, 12.5, 50, and 200 µg/day/mouse, eight groups) to male and female mice for six months. Body weight gain decreased with dose accompanied by increased liver weight, and PFOA altered liver damage-related-blood biochemical indicators and induced pathological lesions, including hepatocellular hypertrophy, cholangiofibrosis, and centrilobular hepatocellular vacuolation. Loss of the Golgi apparatus, formation of lamellar body-like structures, and lipid accumulation were observed in the liver of PFOA-treated mice. We also cohabited five pairs of male and female mice for the last ten days of administration, dosed PFOA to dam up to 28 days after birth, and investigated effects on reproduction and development. The survival rate of pups and the sex ratio of surviving mice decreased significantly at the highest dose. PFOA tissue concentration increased with the dose in the parent mice's liver and the pups' blood and brain. Taken together, we suggest that PFOA primarily affects the liver and reproduction system and that disturbance in lipid metabolism and Golgi's structural stability may be involved in PFOA-induced toxicity.

Dietary Intervention with Quercetin Attenuates Diesel Exhaust Particle-Instilled Pulmonary Inflammation and Behavioral Abnormalities in Mice.

Exposure to diesel exhaust particles (DEPs) is inevitable and closely linked with increased health hazards, causing pulmonary abnormalities by increasing inflammation, hypoxia, and so on. Moreover, long-term exposure to DEPs may trigger whole-body toxicity with behavioral alterations. Therefore, nutritional intervention with natural components may be desirable to prevent and/or ameliorate DEP-inducible pathophysiology in mammals. Quercetin has been demonstrated to reduce metabolic complications by possessing antioxidative, anti-inflammatory, and antimutagenic effects. In this study, we investigated the effects of quercetin on pulmonary inflammation and behavioral alteration in male C57BL/6 mice against DEP instillation. The experimental mice were separated into four treatment groups (n = 8 per group), which include: vehicle control, DEP instillation, dietary intervention with a low dose of quercetin (20 mg/kg) for 14 days with DEP instillation for 7 days, or dietary intervention with a high dose of quercetin (100 mg/kg) for 14 days with DEP instillation for 7 days. Compared with the DEP-instilled group, dietary intervention with quercetin significantly attenuated eosinophils in the bronchoalveolar lavage fluid analysis, pulmonary cytokine, and hypoxic mRNA expressions regardless of quercetin concentrations. DEP instillation triggered hyperactivities in the experimental mice, while quercetin pretreatment successfully normalized DEP-inducible abnormalities regardless of the dosage. Therefore, dietary intervention with quercetin may be an applicable means to prevent DEP-triggered pulmonary and behavioral abnormalities.

Assessment of acute inhalation toxicity of citric acid and sodium hypochlorite in rats.

BACKGROUND: Citric acid (CA) and sodium hypochlorite (NaOCl) have been used to disinfect animals to protect them against avian influenza and foot-and-mouth disease. OBJECTIVES: We performed a good laboratory practice (GLP)-compliant animal toxicity study to assess the acute toxic effects of CA and NaOCl aerosol exposure in Sprague-Dawley rats. METHODS: Groups of five rats per sex were exposed for 4 h to four concentrations of the two chemicals, i.e., 0.00, 0.22, 0.67, and 2.00 mg/L, using a nose-only exposure. After a single exposure to the chemicals, clinical signs, body weight, and mortality was observed during the observation period. On day 15, an autopsy, and then gross findings, and histopathological analysis were performed. RESULTS: After exposure to CA and NaOCl, body weight loss was observed but recovered. Two males died in the CA 2.00 mg/L group and, two males and one female died in the 2.00 mg/L NaOCl group. In the gross findings and histopathological analysis, discoloration of the lungs was observed in the CA exposed group and inflammatory lesions with discoloration of the lungs were observed in the NaOCl exposed group. These results suggest that the lethal concentration 50 (LC50) of CA is 1.73390 mg/L for males and > 1.70 mg/L for females. For NaOCl, the LC50 was 2.22222 mg/L for males and 2.39456 mg/L for females. CONCLUSIONS: The Globally Harmonized System is category 4 for both CA and NaOCl. In this study, the LC50 results were obtained through a GLP-based acute inhalation toxicity assessment. These results provide useful data to reset safety standards for CA and NaOCl use.

Uptake and toxicity of cerium dioxide nanoparticles with different aspect ratio.

Cerium dioxide nanoparticles (CeONPs) have been extensively applied in research for future energy development due to two common oxidation states on their surface. Considering that shape (aspect ratio) is a key determinant of NPs-induced toxicity, we compared the toxicity of hexagonal (H)- and rod-shaped (R)-CeONPs in mice. At 24 h after pharyngeal aspiration, both types of CeONPs recruited surrounding immune cells (monocytes and neutrophils) into the lung, and R-CeONPs induced a more severe pulmonary inflammatory response compared with H-CeONPs. To identify an indicator to predict pulmonary inflammatory responses at the cellular level, we also investigated their responses in alveolar macrophage cells. At 24 h after treatment, both types of CeONPs were mainly located within the vacuoles (partially, in the lysosome) in the cytoplasm. Mitochondrial damage, intracellular calcium accumulation, and increased NO production were observed in cells exposed to both types of CeONPs, ultimately resulting in a decrease in cell viability. More interestingly, both types of CeONPs formed multinucleated giant cells. Meanwhile, contrary to when suspended in deionized water, R-CeONPs were strongly aggregated with a negative charge in cell culture media, whereas H-CeONPs were relatively well-dispersed with a positive charge. R-CeONPs-induced lysosomal extension was also recovered by premix with negatively charged DNA, and even NPs suspended in cell culture media without cells were detected under the FACS system, suggesting interference by protein corona. Therefore, we suggest that shape (aspect ratio) is an important factor determining inhaled NPs-induced pathology and that the effect of the surface charge and protein corona should be carefully considered in interpreting results derived from in vitro tests. Furthermore, we propose that the relationship between the formation of multinucleated giant cells and the inflammatory response of inhaled CeONPs should be further studied.

Subchronic pulmonary toxicity of ambient particles containing cement production-related elements.

Chronic respiratory disease is among the most common non-communicable diseases, and particulate materials (PM) are a major risk factor. Meanwhile, evidence of the relationship between the physicochemical characteristics of PM and pulmonary toxicity mechanism is still limited. Here, we collected particles (CPM) from the air of a port city adjacent to a cement factory, and we found that the CPM contained various elements, including heavy metals (such as arsenic, thallium, barium, and zirconium) which are predicted to have originated from a cement plant adjacent to the sampling site. We also delivered the CPM intratracheally to mice for 13 weeks to investigate the pulmonary toxicity of inhaled CPM. CPM-induced chronic inflammatory lesions with an increased total number of cells in the lung of mice. Meanwhile, among inflammatory mediators measured in this study, levels of IL-1ß, TNF-α, CXCL-1, and IFN-γ were elevated in the treated group compared with the controls. Considering that the alveolar macrophage (known as dust cell) is a professional phagocyte that is responsible for the clearance of PM from the respiratory surfaces, we also investigated cellular responses following exposure to CPM in MH-S cells, a mouse alveolar macrophage cell line. CPM inhibited cell proliferation and formed autophagosome-like vacuoles. Intracellular calcium accumulation and oxidative stress, and altered expression of pyrimidine metabolism- and olfactory transduction-related genes were observed in CPM-treated cells. More interestingly, type I-LC3B and full-length PARP proteins were not replenished in CPM-treated cells, and cell cycle changes, apoptotic and necrotic cell death, and caspase-3 cleavage were not significantly detected in cells exposed to CPM. Taken together, we conclude that dysfunction of alveolar macrophages may contribute to CPM-induced pulmonary inflammation. In addition, given the possible transformation of heart tissue observed in CPM-treated mice, we suggest that further study is needed to clarify the systemic pathological changes and the molecular mechanisms following chronic exposure to CPM.

Subway station dust-induced pulmonary inflammation may be due to the dysfunction of alveolar macrophages: Possible contribution of bound elements.

With its increasing value as a means of public transportation, the health effects of the air in subway stations have attracted public concern. In the current study, we investigated the pulmonary toxicity of dust collected from an air purifier installed on the platform of the busiest subway station in Seoul. We found that the dust contained various elements which are attributable to the facilities and equipment used to operate the subway system. Particularly, iron (Fe), chromium (Cr), zirconium (Zr), barium (Ba), and molybdenum (Mo) levels were more notable in comparison with those in dust collected from the ventilation chamber of a subway station. To explore the health effects of inhaled dust, we first instilled via the trachea in ICR mice for 13 weeks. The total number of pulmonary macrophages increased significantly with the dose, accompanying hematological changes. Dust-laden alveolar macrophages and inflammatory cells accumulated in the perivascular regions in the lungs of the treated mice, and pulmonary levels of CXCL-1, TNF-α, and TGF-ß increased clearly compared with the control. The CCR5 and CD54 level expressed on BAL cell membranes was also enhanced following exposure to dust, whereas the CXCR2 level tended to decrease in the same samples. In addition, we treated the dust to alveolar macrophages (known as dust cells), lysosomal and mitochondrial function decreased, accompanied by cell death, and NO production was rapidly elevated with concentration. Moreover, the expression of autophagy- (p62) and anti-oxidant (SOD-2)-related proteins increased, and the expression of inflammation-related genes was dramatically up-regulated in the dust-treated cells. Therefore, we suggest that dysfunction of alveolar macrophages may importantly contribute to dust-induced inflammatory responses and that the exposure concentrations of Cr, Fe, Mo, Zr, and Ba should be considered carefully when assessing the health risks associated with subway dust. We also hypothesize that the bound elements may contribute to dust-induced macrophage dysfunction by inhibiting viability.

Inflammatory response in rat lungs with recurrent exposure to welding fumes: a transcriptomic approach.

As chronic exposure to welding fumes causes pulmonary diseases, such as pneumoconiosis, public concern has increased regarding continued exposure to these hazardous gases in the workplace. In a previous study, the inflammatory response to welding fume exposure was analysed in rat lungs in the case of recurrent exposure and recovery periods. Thus using lung samples, well-annotated by histological observation and biochemical analysis, this study examines the gene expression profiles to identify phenotype-anchored genes corresponding to lung inflammation and the repair phenomenon after recurrent welding fume exposure. Seven genes (Mmp12, Cd5l, LOC50101, LOC69183, Spp1, and Slc26a4) were found to be significantly up-regulated according to the severity of the lung injury. In addition, the transcription and translation of Trem2, which was up-regulated in response to the repair process, were validated using a real-time polymerase chain reaction, Western blotting, and immunohistochemistry. The differentially expressed genes in the exposure and recovery groups were also classified using k-means and hierarchical clustering, plus their toxicological function and canonical pathways were further analysed using Ingenuity Pathways Analysis Software. As a result, this comprehensive and integrative analysis of the transcriptional changes that occur during repeated exposure provides important information on the inflammation and repair processes after welding-fume-induced lung injury.