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.

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.

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.

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.

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.

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.

Inhalation toxicity of polyhexamethylene guanidine-phosphate in rats: A 4-week inhalation exposure and 24-week recovery period study.

Humidifier disinfectant (HD) is a causative agent of atypical lung injury reported in 2011 in South Korea, and various diseases caused by HD after exposure cessation have been reported to date. However, there is limited research on most of the reported diseases in terms of their association with HD exposure, and information on the progression of diseases caused by HD exposure is also limited. Therefore, we investigated the effects of HD inhalation on the body in rats. Rats were exposed to 0.15, 0.50, and 1.60 mg/m3 polyhexamethylene guanidine-phosphate (PHMG-p), which is the major component of HDs and most closely related to HD-associated lung injury. We conducted necropsy four times during the recovery period (0, 4, 12, and 24 weeks) and evaluated general systemic toxicities. There were significant changes in the mortality rate, body weight, and food consumption in the PHMG-p-exposed groups. Hematology revealed changes in hemoglobin level, hematocrit, red blood cell, reticulocyte, and white blood cell counts until 12 weeks of the recovery period. PHMG-p induced a delay in prothrombin time until 12 weeks of the recovery period. The aspartate aminotransferase, alanine aminotransferase, total bilirubin, and triglyceride levels were higher in the PHMG-p-exposed groups than in the control group at week 4 of the recovery period, and these parameters normalized after 12 weeks of the recovery period. Histopathological examination in PHMG-p exposed groups revealed several changes in the lungs, including the presence of alveolar macrophages, chronic inflammation, squamous metaplasia, alveolar emphysema, and pulmonary fibrosis. The severity of these symptoms was maintained or exacerbated till 24 weeks. Overall, PHMG-p inhalation can induce irreversible histological changes in the lungs and cause various types of damage throughout the body, even after exposure ends.

Polyhexamethylene guanidine phosphate-induced necrosis may be linked to pulmonary fibrosis.

Following the humidifier disinfectant incident in Korea, polyhexamethylene guanidine phosphate (PHMG-P) has been used to establish lung fibrosis model animals. Herein, we investigated time-dependent changes after a single PHMG-P instillation (22 µg/lung) to identify the underlying pathogenesis and immune response involved in PHMG-P-induced lung fibrosis. Compared to control mice, body weight loss and blood biochemical and hematological changes were more remarkable in PHMG-P-instilled mice, an increase of total cell counts, infiltration of macrophages and neutrophils and necrotic cell death were also more notable in the lungs of PHMG-P-instilled mice. Pathological lesions were detected from Day 1 after exposure, deteriorating with time. In addition, secretion of anti-inflammatory mediators was rapidly inhibited from 6 h after exposure, and level of IL-24, a tissue repair-related cytokine, was up-regulated in the lungs of PHMG-P-instilled mice until Day 21 post-exposure. In vitro tests using BEAS-2B cells showed that PHMG-P disturbed structural and functional homeostasis of organelles and that intracellular ROS increase was considered as an important cause of PHMG-P-induced cell death. Additionally, co-culture with DNA, a polyanionic compound, clearly inhibited PHMG-P-induced necrosis, and increased IL-1ß and TNF-α level and decreased IL-6 and IL-8 levels were observed following exposure to PHMG-P. Meanwhile, IL-8 secretion increased in cells exposed to PHMG-P-induced cell debris. Therefore, we suggest that necrotic cell debris may importantly contribute to the PHMG-P-induced inflammatory response and pathogenesis. In addition, PHMG-P-induced necrosis may be initiated by high affinity between PHMG-P and cell membrane.

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.

Therapeutic effect of intra-articular injected 3'-sialyllactose on a minipig model of rheumatoid arthritis induced by collagen.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic inflammatory disease of joint, but there is no known cure. 3'-sialyllactose (3'-SL) is an oligosaccharide that is abundant in breast milk of mammals, and has anti-inflammatory properties. However, the efficacy of 3'-SL on RA remains unclear. The objective of the present study was to evaluate the therapeutic effect of 3'-SL after it was directly injected into the knee joint cavity of a RA minipig model. RESULTS: Minipig RA model was induced by intra-articular injection of bovine type II collagen emulsified with complete or incomplete Freund's adjuvant into left knee joint. In clinical assessment, lameness and swelling of the hindlimb and increased knee joint width were observed in all animals. After the onset of arthritis, 3'-SL (0, 2, 10, and 50 mg/kg) was directly administered to the left knee joint cavity once a week for 4 weeks. Compared to the vehicle control group, no significant difference in macroscopic observation of the synovial pathology or the expression of inflammation-related genes (IL-1ß, TNF-α, and COX2) in the synovial membrane of the knee joint was found. In microscopic observation, cell cloning of the articular cartilage was significantly reduced in proportion to the concentration of 3'-SL administered. CONCLUSIONS: Our results suggest that intra-articular injected 3'-SL had a therapeutic effect on collagen-induced arthritis at the cellular level with potential as a medication for RA.

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.

Comparison of toxicity and cellular responses following pulmonary exposure to different types of nanofibers.

Pulmonary effects of inhaled microfibers are an emerging public health concern. In this study, we investigated toxicity following pulmonary exposure to synthetic polyethylene oxide fibroin (PEONF) and silk fibroin (SFNF) nanofibers and the cellular responses. When instilled intratracheally weekly for four weeks, body weight gain was significantly reduced in female mice exposed to the higher dose of SFNF when compared with the control group. The total number of cells in the lungs was more significant in all treated groups than in the control, whereas the relative portion of neutrophils and eosinophils increased significantly only in female mice exposed to SFNF. Both types of nanofibers induced notable pathological changes and increased pulmonary expression of MCP-1α, CXCL1, and TGF-ß. More importantly, blood calcium, creatinine kinase, sodium, and chloride concentration were affected significantly, showing sex- and material-dependent differences. The relative portion of eosinophils increased only in SFNF-treated mice. In addition, both types of nanofibers induced necrotic and late apoptotic cell death in alveolar macrophages after 24 h of exposure, with accompanying oxidative stress, increased NO production, cell membrane rupture, intracellular organelle damage, and intracellular calcium accumulation. Additionally, multinucleated giant cells were formed in cells exposed to PEONF or SFNF. Taken together, the findings indicate that inhaled PEONF and SFNF may cause systemic adverse health effects with lung tissue damage, showing differences by sex- and material. Furthermore, PEONF- and SFNF-induced inflammatory response may be partly due to the low clearance of dead (or damaged) pulmonary cells and the excellent durability of PEONF and SFNF.

Preparation and evaluation of rapid disintegrating formulation from coated microneedle.

Microneedles (MNs), one of the transdermal drug delivery systems, have received extensive interest as an alternative to parenteral or parenteral administrations. For the successful drug delivery of coated MNs, the coated drug or chemical of MNs should be dissolved by skin's interstitial fluid and completely released from the MNs. Thus, the rapid disintegration of the drug from MNs plays a crucial role in ideal drug delivery of MNs. In this study, we developed the rapid disintegration coating formulation to reduce the application time of MN. The rapid disintegration MN was developed using polymers (PVA or HPMC), glycerol, croscarmellose sodium, tween 80, and Brij, as thickener, plasticizer, disintegrating agent, and surfactants, respectively. HPMC MN showed the burst release and rapid disintegration. Moreover, the drug from HPMC MN was successfully delivered into porcine skin within 1 min. In toxicological evaluation, the HPMC MN did not alter the liver and kidney function. Besides, HPMC MN did not induce the acute inflammation and change of skin structure after the application on rat skin. Thus, the coating formulation in this study could be one of the options for the development of safe and rapid disintegration MN.

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.

Surgical removal of a telemetry system in a cynomolgus monkey (Macaca fascicularis): a 12-month observation study.

BACKGROUND: Telemetry is a wireless implanted device that measures biological signals in conscious animals and usually requires surgery for its removal when the study is finished. After removing the device, the animals are either used for other studies or euthanatized. CASE PRESENTATION: Herein, we report the case of a living cynomolgus monkey (Macaca fascicularis) that was used for the entire experimental period, instead of euthanasia, after surgical removal of an implanted telemetry system. Radiography was used to determine the status of the implanted telemetry, following which, a repair surgery was performed for removing the system; clinical signs were used to preserve the life of the cynomolgus monkey. Postoperative clinical signs, food consumption, hematology, and serum biochemistry were examined during the 12-month observational period. No abnormal readings or conditions were observed in the subject after implant removal. CONCLUSIONS: This study may be a useful case report for living cynomolgus monkeys in telemetry implantations used throughout the study period. We suggest minimizing the suffering and improving the welfare of these animals.

Exposure to cigarette smoke exacerbates polyhexamethylene guanidine-induced lung fibrosis in mice.

Cigarette smoke (CS) is the leading cause of chronic pulmonary diseases, including lung cancer, chronic obstructive pulmonary disease, and pulmonary fibrosis. In this study, we aimed to investigate the effects of repeated CS exposure on polyhexamethylene guanidine (PHMG)-induced pulmonary fibrosis in mice. A single intratracheal instillation of 0.6 mg/kg PHMG enhanced the immune response of mice by increasing the number of total and specific inflammatory cell types in the bronchoalveolar lavage fluid. It induced histopathological changes such as granulomatous inflammation/fibrosis and macrophage infiltration in the lungs. These responses were upregulated upon exposure to a combination of PHMG and CS. In contrast, a 4-hr/day exposure to 300 mg/m3 CS alone for 2 weeks by nose-only inhalation resulted in minimal inflammation in the mouse lung. Furthermore, PHMG administration increased the expression of fibrogenic mediators, especially in the pulmonary tissues of the PHMG + CS group compared with that in the PHMG alone group. However, there was no upregulation in the expression of inflammatory cytokines following exposure to a combination of PHMG and CS. Our results demonstrate that repeated exposure to CS may promote the development of PHMG-induced pulmonary fibrosis.

Toxicity of diclofenac sodium salt in Yucatan minipigs (Sus scrofa) following 4 weeks of daily intramuscular administration.

Diclofenac sodium salt (DSS) is a widely used nonsteroidal anti-inflammatory drug. The present study was performed under good laboratory practice (GLP) regulations to investigate the toxicity of DSS after 4 weeks of repeated intramuscular administration at doses of 0, 2, 10, or 20 mg/kg/day in 32 minipigs and to evaluate the DSS effect following a 2-week recovery period. Dose-related clinical signs and alterations of hematological or clinical chemistry parameters, organ weight, and macroscopic as well as histopathological findings in hepatic, renal, gastrointestinal, skin and injection sites were observed in both sexes' animals of the 10 or 20 mg/kg/day group. With the exception of the skin-related findings, most symptoms showed a tendency to resolve after the 2-week recovery period. The systemic exposure (AUClast) of DSS in plasma showed similar pattern to the increase rate of the dose and similar values between males and females except for the female 20 mg/kg dose group (56 %) on Day1. The systemic exposure showed a decreasing trend in the 10 or 20 mg/kg group after 4-week of repeated administration compared to Day1. The no-observed-adverse-effect level of DSS in this study was considered to be 2 mg/kg/day in both male and female minipigs.

Assessment of acute and repeated pulmonary toxicities of oligo(2-(2-ethoxy)ethoxyethyl guanidium chloride in mice.

Oligo(2-(2-ethoxy)ethoxyethyl guanidinium chloride (PGH) and polyhexamethyleneguanidine phosphate (PHMG-P) are cationic biocides containing a guanidine group. Direct exposure of the lungs to PHMG-P is known to induce pulmonary inflammation and fibrotic changes. Few studies have assessed the pulmonary toxicity of PGH, another member of the guanidine family. In this study, we assessed the acute and repeated toxicity of PGH and PHMG-P to compare the pathological progression induced by both chemicals. PGH (1.5 mg/kg) or PHMG (0.6 mg/kg) was instilled intratracheally to mice once or three times every 4 days; subsequently, cytokine levels were quantified and a histopathological examination was performed. To verify the toxic mechanism of PGH, we quantified cell viability and cytokine production induced by PGH or PHMG-P in the presence or absence of anionic material in cells. Instillation of PGH and PHMG-P into the mouse lung increased cytokine production, immune cell infiltration, and pulmonary fibrotic changes. These pathological changes were exacerbated over time in the single- and the repeated-dose PHMG-P groups, but were resolved over time in the PGH groups. PGH or PHMG-P showed cytotoxic effects, IL-1ß secretion, and ROS production in a dose-dependent manner in human cell lines. However, the co-treatment of anionic materials with PGH or PHMG-P significantly reduced these toxic responses, which confirmed that the cation of PGH disrupted the plasma membrane via ionic interaction, as observed for PHMG-P. In addition, we suggest the disruption of plasma membrane as a molecular initiating event of cationic chemicals-induced adverse outcomes when exposed directly to the lungs.

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.