Vanadium pentoxide induces pulmonary inflammation and tumor promotion in a strain-dependent manner

Metabolic alterations and mitochondrial dysfunction in human airway BEAS-2B cells exposed to vanadium pentoxide

Vanadium pentoxide (V+5) is a hazardous material that has drawn considerable attention due to its wide use in industrial sectors and increased release into environment from human activities. It poses potential adverse effects on animals and human health, with pronounced impact on lung physiology and functions. In this study, we investigated the metabolic response of human bronchial epithelial BEAS-2B cells to low-level V+5 exposure (0.01, 0.1, and 1 ppm) using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Exposure to V+5 caused extensive changes to cellular metabolism in BEAS-2B cells, including TCA cycle, glycolysis, fatty acids, amino acids, amino sugars, nucleotide sugar, sialic acid, vitamin D3, and drug metabolism, without causing cell death. Altered mitochondrial structure and function were observed with as low as 0.01 ppm (0.2 μM) V+5 exposure. In addition, decreased level of E-cadherin, the prototypical epithelial marker of epithelial-mesenchymal transition (EMT), was observed following V+5 treatment, supporting potential toxicity of V+5 at low levels. Taken together, the present study shows that V+5 has adverse effects on mitochondria and the metabolome which may result in EMT activation in the absence of cell death. Furthermore, results suggest that high-resolution metabolomics could serve as a powerful tool to investigate metal toxicity at levels which do not cause cell death.

Potent lung tumor promotion by inhaled MWCNT

In the lung, carcinogenesis is a multi-stage process that includes initiation by a genotoxic agent, promotion that expands the population of cells with damaged DNA to form a tumor, and progression from benign to malignant neoplasms. We have previously shown that Mitsui-7, a long and rigid multi-walled carbon nanotube (MWCNT), promotes pulmonary carcinogenesis in a mouse model. To investigate the potential exposure threshold and dose-response for tumor promotion by this MWCNT, 3-methylcholanthrene (MC) initiated (10 μg/g, i.p., once) or vehicle (corn oil) treated B6C3F1 mice were exposed by inhalation to filtered air or MWCNT (5 mg/m3) for 5 h/day for 0, 2, 5, or 10 days and were followed for 17 months post-exposure for evidence of lung tumors. Pulmonary neoplasia incidence in MC-initiated mice significantly increased with each MWCNT exposure duration. Exposure to either MC or MWCNT alone did not affect pulmonary neoplasia incidence compared with vehicle controls. Lung tumor multiplicity in MC-initiated mice also significantly increased with each MWCNT exposure duration. Thus, a significantly higher lung tumor multiplicity was observed after a 10-day MWCNT exposure than following a 2-day exposure. Both bronchioloalveolar adenoma and bronchioloalveolar adenocarcinoma multiplicity in MC-initiated mice were significantly increased following 5- and 10-day MWCNT exposure, while a 2-day MWCNT exposure in MC-initiated mice significantly increased the multiplicity of adenomas but not adenocarcinomas. In this study, even the lowest MWCNT exposure promoted lung tumors in MC-initiated mice. Our findings indicate that exposure to this MWCNT strongly promotes pulmonary carcinogenesis.

Low-dose vanadium pentoxide perturbed lung metabolism associated with inflammation and fibrosis signaling in male animal and in vitro models

Vanadium is available as a dietary supplement and also is known to be toxic if inhaled, yet little information is available concerning the effects of vanadium on mammalian metabolism when concentrations found in food and water. Vanadium pentoxide (V+5) is representative of the most common dietary and environmental exposures, and prior research shows that low-dose V+5 exposure causes oxidative stress measured by glutathione oxidation and protein S-glutathionylation. We examined the metabolic impact of V+5 at relevant dietary and environmental doses (0.01, 0.1, and 1 ppm for 24 h) in human lung fibroblasts (HLFs) and male C57BL/6J mice (0.02, 0.2, and 2 ppm in drinking water for 7 mo). Untargeted metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) showed that V+5 induced significant metabolic perturbations in both HLF cells and mouse lungs. We noted 30% of the significantly altered pathways in HLF cells, including pyrimidines and aminosugars, fatty acids, mitochondrial and redox pathways, showed similar dose-dependent patterns in mouse lung tissues. Alterations in lipid metabolism included leukotrienes and prostaglandins involved in inflammatory signaling, which have been associated with the pathogenesis of idiopathic pulmonary fibrosis (IPF) and other disease processes. Elevated hydroxyproline levels and excessive collagen deposition were also present in lungs from V+5-treated mice. Taken together, these results show that oxidative stress from environmental V+5, ingested at low levels, could alter metabolism to contribute to common human lung diseases.NEW & NOTEWORTHY We used relevant dietary and environmental doses of Vanadium pentoxide (V+5) to examine its metabolic impact in vitro and in vivo. Using liquid chromatography-high-resolution mass spectrometry (LC-HRMS), we found significant metabolic perturbations, with similar dose-dependent patterns observed in human lung fibroblasts and male mouse lungs. Alterations in lipid metabolism included inflammatory signaling, elevated hydroxyproline levels, and excessive collagen deposition were present in V+5-treated lungs. Our findings suggest that low levels of V+5 could trigger pulmonary fibrotic signaling.

Metabolomics of V2O5 nanoparticles and V2O5 nanofibers in human airway epithelial BEAS-2B cells

Vanadium is a toxic metal listed by the IARC as possibly carcinogenic to humans. Manufactured nanosize vanadium pentoxide (V2O5) materials are used in a wide range of industrial sectors and recently have been developed as nanomedicine for cancer therapeutics, yet limited information is available to evaluate relevant nanotoxicity. In this study we used high-resolution metabolomics to assess effects of two V2O5 nanomaterials, nanoparticles and nanofibers, at exposure levels (0.01, 0.1, and 1 ppm) that did not cause cell death (i.e., non-cytotoxic) in a human airway epithelial cell line, BEAS-2B. As prepared, V2O5 nanofiber exhibited a fibrous morphology, with a width approximately 63 ± 12 nm and length in average 420 ± 70 nm; whereas, V2O5 nanoparticles showed a typical particle morphology with a size 36 ± 2 nm. Both V2O5 nanoparticles and nanofibers had dose-response effects on aminosugar, amino acid, fatty acid, carnitine, niacin and nucleotide metabolism. Differential effects of the particles and fibers included dibasic acid, glycosphingolipid and glycerophospholipid pathway associations with V2O5 nanoparticles, and cholesterol and sialic acid metabolism associations with V2O5 nanofibers. Examination by transmission electron microscopy provided evidence for mitochondrial stress and increased lysosome fusion by both nanomaterials, and these data were supported by effects on mitochondrial membrane potential and lysosomal activity. The results showed that non-cytotoxic exposures to V2O5 nanomaterials impact major metabolic pathways previously associated with human lung diseases and suggest that toxico-metabolomics may be useful to evaluate health risks from V2O5 nanomaterials.

Vanadium pentoxide induced oxidative stress and cellular senescence in human lung fibroblasts

Both environmental exposure to vanadium pentoxide (V2O5, V+5 for its ionic counterparts) and fibroblast senescence are associated with pulmonary fibrosis, but whether V+5 causes fibroblast senescence remains unknown. We found in a dose-response study that 2-40 μM V+5 caused human lung fibroblasts (HLF) senescence with increased senescence-associated β-galactosidase activity and p16 expression, while cell death occurred at higher concentration (LC50, 82 μM V+5). Notably, measures of reactive oxygen species (ROS) production with fluorescence probes showed no association of ROS with V+5-dependent senescence. Preloading catalase (polyethylene-conjugated), a H2O2 scavenger, did not alleviate the cellular senescence induced by V+5. Analyses of the cellular glutathione (GSH) system showed that V+5 oxidized GSH, increased GSH biosynthesis, stimulated cellular GSH efflux and increased protein S-glutathionylation, and addition of N-acetyl cysteine inhibited V+5-elevated p16 expression, suggesting that thiol oxidation mediates V+5-caused senescence. Moreover, strong correlations between GSSG/GSH redox potential (Eh), protein S-glutathionylation, and cellular senescence (R2 > 0.99, p < 0.05) were present in V+5-treated cells. Studies with cell-free and enzyme-free solutions showed that V+5 directly oxidized GSH with formation of V+4 and GSSG in the absence of O2. Analyses of V+5 and V+4 in HLF and culture media showed that V+5 was reduced to V+4 in cells and that a stable V+4/V+5 ratio was rapidly achieved in extracellular media, indicating ongoing release of V+4 and reoxidation to V+5. Together, the results show that V+5-dependent fibroblast senescence is associated with a cellular/extracellular redox cycling mechanism involving the GSH system and occurring under conditions that do not cause cell death. These results establish a mechanism by which environmental vanadium from food, dietary supplements or drinking water, can cause or contribute to lung fibrosis in the absence of high-level occupational exposures and cytotoxic cell death.

Association between Serum Level of Multiple Trace Elements and Esophageal Squamous Cell Carcinoma Risk: A Case-Control Study in China

We investigated the associations between multiple serum trace element levels and risk for esophageal squamous cell carcinoma (ESCC). A total of 185 ESCC patients and 191 healthy individuals were recruited in our study. The concentration of 13 trace elements (Al, V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Sr, Cd and Pb) in serum was determined with inductively coupled plasma mass spectrometry (ICP-MS). Logistic regression and the Probit extension of Bayesian Kernel Machine Regression (BKMR) models was established to explore the associations and the cumulative and mixed effects of multiple trace elements on ESCC. Three elements (Zn, Se and Sr) displayed a negative trend with risk for ESCC, and a significant overall effect of the mixture of Al, V, Mn, Ni, Zn, Se and Sr on ESCC was found, with the effects of V, Ni and Sr being nonlinear. Bivariate exposure-response interactions among these trace elements indicated a synergistic effect between Zn and Se, and an impactful difference of V combined with Ni, Sr or Zn. Our results indicate that Ni, V, Al, Mn, Zn, Se and Sr are associated with ESCC risk, providing additional evidence of the complex effects of trace elements disorder during the etiology of EC development.

Will Vanadium-Based Electrode Materials Become the Future Choice for Metal-Ion Batteries?

Metal-ion batteries have emerged as promising candidates for energy storage system due to their unlimited resources and competitive price/performance ratio. Vanadium-based compounds have diverse oxidation states rendering various open-frameworks for ions storage. To date, some vanadium-based polyanionic compounds have shown great potential as high-performance electrode materials. However, there has been a growing concern regarding the cost and environmental risk of vanadium. In this Review, all links in the industry chain of vanadium-based electrodes were comprehensively summarized, starting with an analysis of the resources, applications, and price fluctuation of vanadium. The manufacturing processes of the vanadium extraction and recovery technologies were discussed. Moreover, the commercial potentials of some typical electrode materials were critically appraised. Finally, the environmental impact and sustainability of the industry chain were evaluated. This critical Review will provide a clear vision of the prospects and challenges of developing vanadium-based electrode materials.

Recent advances in removal techniques of vanadium from water: A comprehensive review

In recent years, with the development of economy and industry, water contaminated with heavy metal has become a global environmental problem. Vanadium (V) is an emerging contaminant reported in wastewater along with the increasing mining, smelting and recovering of vanadium ores and application in many fields as a significant national strategy resource. The increasing attention has been paid to the separations of V from water due to its potential toxic to animals and human beings. In the present study, the most common V removal techniques including adsorption, microbiological treatment, chemical precipitation, solvent extraction, electrokinetic remediation, photocatalysis, coagulation and membrane filtration are presented with discussion of their advantages, limitations and the recent achievements. Several major influencing factors and mechanisms of various processes have been briefly analyzed. Some research perspectives are proposed for improving the capacities to remove V from water. The core objective of this review is to provide comprehensive information or database for the superior approach for V removal.

Associations of prenatal exposure to vanadium with early-childhood growth: A prospective prenatal cohort study

Prenatal vanadium exposure is reported to be associated with restricted fetal growth and adverse birth outcomes. However, trimester-specific vanadium exposure in relation to early-childhood growth still remains unclear. A total of 1873 Chinese mother-infant pairs from whom a complete series of maternal urinary samples were collected over three stages of pregnancy were included from 2014 to 2016. The urinary concentrations of vanadium were analyzed. Children's anthropometric parameters were measured at birth, 6, 12 and 24 months. In boys, each doubling increase in vanadium concentrations at middle pregnancy was inversely associated with weight-for-length [- 9.07% (-17.21%, -0.93%)] and BMI z-score [- 9.66% (-18.05%, -1.28%)] at 24 months. Moreover, vanadium exposure at late pregnancy was negatively associated with weight [- 9.85% (-16.42%, -3.28%)], weight-for-length [- 11.00% (-18.40%, -3.60%)], and BMI z-scores [- 11.05% (-18.67%, -3.42%)] at 24 months in boys. However, the negative associations were not observed in girls, and we found evidence for sex difference (FDR p for interaction=0.01, 0.01 and 0.03 for weight, weight-for-length and BMI z-scores, respectively). Prenatal vanadium exposure may have an adverse effect on early-childhood growth, and the middle and late pregnancy could be windows of vulnerability for the adverse effects of vanadium exposure on growth development.

Long-term exposure to fine particle elemental components and lung cancer incidence in the ELAPSE pooled cohort

BACKGROUND

An association between long-term exposure to fine particulate matter (PM_2.5) and lung cancer has been established in previous studies. PM_2.5 is a complex mixture of chemical components from various sources and little is known about whether certain components contribute specifically to the associated lung cancer risk. The present study builds on recent findings from the "Effects of Low-level Air Pollution: A Study in Europe" (ELAPSE) collaboration and addresses the potential association between specific elemental components of PM_2.5 and lung cancer incidence.

METHODS

We pooled seven cohorts from across Europe and assigned exposure estimates for eight components of PM_2.5 representing non-tail pipe emissions (copper (Cu), iron (Fe), and zinc (Zn)), long-range transport (sulfur (S)), oil burning/industry emissions (nickel (Ni), vanadium (V)), crustal material (silicon (Si)), and biomass burning (potassium (K)) to cohort participants' baseline residential address based on 100 m by 100 m grids from newly developed hybrid models combining air pollution monitoring, land use data, satellite observations, and dispersion model estimates. We applied stratified Cox proportional hazards models, adjusting for potential confounders (age, sex, calendar year, marital status, smoking, body mass index, employment status, and neighborhood-level socio-economic status).

RESULTS

The pooled study population comprised 306,550 individuals with 3916 incident lung cancer events during 5,541,672 person-years of follow-up. We observed a positive association between exposure to all eight components and lung cancer incidence, with adjusted HRs of 1.10 (95% CI 1.05, 1.16) per 50 ng/m³ PM_2.5 K, 1.09 (95% CI 1.02, 1.15) per 1 ng/m³ PM_2.5 Ni, 1.22 (95% CI 1.11, 1.35) per 200 ng/m³ PM_2.5 S, and 1.07 (95% CI 1.02, 1.12) per 200 ng/m³ PM_2.5 V. Effect estimates were largely unaffected by adjustment for nitrogen dioxide (NO₂). After adjustment for PM_2.5 mass, effect estimates of K, Ni, S, and V were slightly attenuated, whereas effect estimates of Cu, Si, Fe, and Zn became null or negative.

CONCLUSIONS

Our results point towards an increased risk of lung cancer in connection with sources of combustion particles from oil and biomass burning and secondary inorganic aerosols rather than non-exhaust traffic emissions. Specific limit values or guidelines targeting these specific PM_2.5 components may prove helpful in future lung cancer prevention strategies.

Effects of vanadium (sodium metavanadate) and aflatoxin-B1 on cytochrome p450 activities, DNA damage and DNA methylation in human liver cell lines

Vanadium is considered as "possibly carcinogenic to humans" (V₂O₅, IARC Group 2B), yet uncertainties persist related to the toxicity mechanisms of the multiple forms of vanadium. Exposure to vanadium often co-occurs with other metals or with organic compounds that can be transformed by cytochrome p450 (CYP) enzymes into DNA-reactive carcinogens. Therefore, effects of a soluble form of vanadium (sodium metavanadate, NaVO₃) and aflatoxin-B1 (AFB1) were tested separately and together, for induction of CYP activities, DNA damage (γH2AX and DNA alkaline unwinding assays), and DNA methylation changes (global genome and DNA repeats) in HepaRG or HepG2 liver cell lines. NaVO₃ (≥ 2.3 μM) reduced CYP1A1 and CYP3A4 activities and induced DNA damage, butcaused important cell proliferation only in HepaRG cells. As a binary mixture, NaVO₃ did not modify the effects of AFB1. There was no reproducible effect of NaVO₃ (<21 μM) on DNA methylation in AluYb8, satellite-α, satellite-2, and by the luminometric methylation assay, but DNA methylation flow-cytometry signals in HepG2 cells (25-50 μM) increased at the G1 and G2 cell cycle phases. In conclusion, cell lines responded differently to NaVO₃ supporting the importance of investigating more than one cell line, and a carcinogenic role of NaVO₃ might reside at low concentrations by stimulating the proliferation of tumorigenic cells.

Two-stage 3-methylcholanthrene and butylated hydroxytoluene-induced lung carcinogenesis in mice

Lung cancer is one of the deadliest types of cancer and as such requires disease models that are useful for identification of novel pathways for biomarkers as well as to test therapeutic agents. Adenocarcinoma (ADC), the most prevalent type of lung cancer, is a subtype of non-small cell lung carcinoma (NSCLC) and a disease driven mainly by smoking. However, it is also the most common subtype of lung cancer found in non-smokers with environmental exposures. Chemically driven models of lung cancer, also called primary models of lung cancer, are important because they do not overexpress or delete oncogenes or tumor suppressor genes, respectively, to increase oncogenesis. Instead these models test tumor development without forcing a specific pathway (i.e., Kras). The primary focus of this chapter is to discuss a well-established 2-stage mouse model of lung adenocarcinomas. The initiator (3-methylcholanthrene, MCA) does not elicit many, if any, tumors if not followed by exposure to the tumor promoter (butylated hydroxytoluene, BHT). In sensitive strains, such as A/J, FVB, and BALB, significantly greater numbers of tumors develop following the MCA/BHT protocol compared to MCA alone. BHT does not elicit tumors on its own; it is a non-genotoxic carcinogen and promoter. In these sensitive strains, promotion is also associated with inflammation characterized by infiltrating macrophages, lymphocytes, and neutrophils, and other inflammatory cell types in addition to increases in total protein content reflective of lung hyperpermeability. This 2-stage model is a useful tool to identify unique promotion specific events to then test in future intervention studies.

The limitations of using the NTP chronic bioassay on vanadium pentoxide in risk assessments

Regulatory interest in assessing the health effects of vanadium compounds is hindered by the limited chronic toxicity data available. The National Toxicology Program (NTP) conducted a robust chronic inhalation bioassay of crystalline vanadium pentoxide (V₂O₅), but this study has noteworthy limitations. Multiple dose range-finding studies were conducted at two separate laboratories that showed cross-laboratory differences in lung pathology (inflammation) in both species and likely complicated dose-selection. In mice, the only tissue pathology (inflammation and tumors) was at the site of entry, the respiratory system. Although significantly different from control, because lung tumor incidences were at a maximal level across all concentrations tested, the ability to extrapolate risks to the public is problematic. In rats, lung inflammation and vanadium lung burdens were comparable to those of mice, but lung tumorigenicity was not substantiated, further raising questions about appropriate species extrapolation. Open questions also exist regarding test material chemical characterization, as the laboratory relied on vanadium measurement in test chambers as a surrogate for V₂O₅. In sum, the NTP V₂O₅ study does not provide an appropriate dataset for purposes of classification and risk assessment. Additional repeat exposure studies of vanadium compounds are needed and recommendations for future studies are provided.

Protective Effects of Dietary Antioxidants against Vanadium-Induced Toxicity: A Review

Vanadium (V) in its inorganic forms is a toxic metal and a potent environmental and occupational pollutant and has been reported to induce toxic effects in animals and people. In vivo and in vitro data show that high levels of reactive oxygen species are often implicated in vanadium deleterious effects. Since many dietary (exogenous) antioxidants are known to upregulate the intrinsic antioxidant system and ameliorate oxidative stress-related disorders, this review evaluates their effectiveness in the treatment of vanadium-induced toxicity. Collected data, mostly from animal studies, suggest that dietary antioxidants including ascorbic acid, vitamin E, polyphenols, phytosterols, and extracts from medicinal plants can bring a beneficial effect in vanadium toxicity. These findings show potential preventive effects of dietary antioxidants on vanadium-induced oxidative stress, DNA damage, neurotoxicity, testicular toxicity, and kidney damage. The relevant mechanistic insights of these events are discussed. In summary, the results of studies on the role of dietary antioxidants in vanadium toxicology appear encouraging enough to merit further investigations.

F4/80+ Macrophages Contribute to Clearance of Senescent Cells in the Mouse Postpartum Uterus

Cellular senescence, defined as an irreversible cell cycle arrest, exacerbates the tissue microenvironment. Our previous study demonstrated that mouse uterine senescent cells were physiologically increased according to gestational days and that their abnormal accumulation was linked to the onset of preterm delivery. We hypothesized that there is a mechanism for removal of senescent cells after parturition to maintain uterine function. In the current study, we noted abundant uterine senescent cells and their gradual disappearance in wild-type postpartum mice. F4/80+ macrophages were present specifically around the area rich in senescent cells. Depletion of macrophages in the postpartum mice using anti-F4/80 antibody enlarged the area of senescent cells in the uterus. We also found excessive uterine senescent cells and decreased second pregnancy success rate in a preterm birth model using uterine p53-deleted mice. Furthermore, a decrease in F4/80+ cells and an increase in CD11b+ cells with a senescence-associated inflammatory microenvironment were observed in the p53-deleted uterus, suggesting that uterine p53 deficiency affects distribution of the macrophage subpopulation, interferes with senescence clearance, and promotes senescence-induced inflammation. These findings indicate that the macrophage is a key player in the clearance of uterine senescent cells to maintain postpartum uterine function.

The distance-to-source trend in vanadium and arsenic exposures for residents living near a petrochemical complex

Biological monitoring of vanadium (V) and arsenic (As) for residents living near a big petrochemical complex has not been previously studied. This study aims to investigate distance-to-source trends in urinary levels and dispersion-estimated concentrations of V and As in areas surrounding a petrochemical complex in central Taiwan. Our study subjects were 1424 residents living in the townships up to ~40 km from the petrochemical complex, and categorized as near (Zone A), further (Zone B) and furthest (Zone C) from the complex. Urinary and ambient V and As levels were analyzed by inductively coupled plasma mass spectrometry. Two-stage dispersion model was used to estimate V and As concentrations at each study subject's address. Multiple linear regression models were used to study the effects of distance-to-source and estimated air concentrations of V and As on the urinary V and As levels of study subjects. Area-wide levels of both V and As showed a high-to-low trend in urinary levels (μg/g-creatinine) from Zone A (V with 2.86±2.30 and As with 104.6±147.9) to Zone C (V with 0.73±0.72 and As with 73.8±90.8). For study subjects, urinary V and As levels were decreased by 0.09 and 1.17 μg/g-creatinine, respectively, with 1 km away from the emission source of the petrochemical complex, and urinary V levels were significantly elevated by 0.38 μg/g-creatinine with a 1 ng/m(3) increase in estimated ambient V concentrations at their addresses. Our study concludes a distance-to-source gradient in V and As exposures exists for residents living near a petrochemical complex with oil refineries and coal-fired power plants and two-stage dispersion model can predict such a trend for V when inhalation is the major exposure route, but not for As that exposure may be from multiple sources and exposure routes.

Differential innate immune cell signatures and effects regulated by toll-like receptor 4 during murine lung tumor promotion

Tumor promotion is an early and critical stage during lung adenocarcinoma (ADC). We previously demonstrated that Tlr4 mutant mice were more susceptible to butylated hydroxytoluene (BHT)-induced pulmonary inflammation and tumor promotion in comparison to Tlr4-sufficient mice. Our study objective was to elucidate the underlying differences in Tlr4 mutant mice in innate immune cell populations, their functional responses, and the influence of these cellular differences on ADC progenitor (type II) cells following BHT-treatment. BALB (Tlr4-sufficient) and C.C3-Tlr4(Lps-d)/J (BALB(Lpsd); Tlr4 mutant) mice were treated with BHT (promoter) followed by bronchoalveolar lavage (BAL) and flow cytometry processing on the lungs. ELISAs, Club cell enrichment, macrophage function, and RNA isolation were also performed. Bone marrow-derived macrophages (BMDM) co-cultured with a type II cell line were used for wound healing assays. Innate immune cells significantly increased in whole lung in BHT-treated BALB(Lpsd) mice compared to BALB mice. BHT-treated BALB(Lpsd) mice demonstrated enhanced macrophage functionality, increased epithelial wound closure via BMDMs, and increased Club cell number in BALB(Lpsd) mice, all compared to BALB BHT-treated mice. Cytokine/chemokine (Kc, Mcp1) and growth factor (Igf1) levels also significantly differed among the strains and within macrophages, gene expression, and cell surface markers collectively demonstrated a more plastic phenotype in BALB(Lpsd) mice. Therefore, these correlative studies suggest that distinct innate immune cell populations are associated with the differences observed in the Tlr4-mutant model. Future studies will investigate the macrophage origins and the utility of the pathways identified herein as indicators of immune system deficiencies and lung tumorigenesis.

Epiregulin is required for lung tumor promotion in a murine two-stage carcinogenesis model

Adenocarcinoma accounts for ∼40% of lung cancer, equating to ∼88 500 new patients in 2015, most of who will succumb to this disease, thus, the public health burden is evident. Unfortunately, few early biomarkers as well as effective therapies exist, hence the need for novel targets in lung cancer treatment. We previously identified epiregulin (Ereg), an EGF-like ligand, as a biomarker in several mouse lung cancer models. In the present investigation we used a primary two-stage initiation/promotion model to test our hypothesis that Ereg deficiency would reduce lung tumor promotion in mice. We used 3-methylcholanthrene (initiator) or oil vehicle followed by multiple weekly exposures to butylated hydroxytoluene (BHT; promoter) in mice lacking Ereg (Ereg^-/- ) and wildtype controls (BALB/ByJ; Ereg^+/+ ) and examined multiple time points and endpoints (bronchoalveolar lavage analysis, tumor analysis, mRNA expression, ELISA, wound assay) during tumor promotion. At the early time points (4 and 12 wk), we observed significantly reduced amounts of inflammation (macrophages, PMNs) in the Ereg^-/- mice compared to controls (Ereg^+/+ ). At 20 wk, tumor multiplicity was also significantly decreased in the Ereg^-/- mice versus controls (Ereg^+/+ ). IL10 expression, an anti-inflammatory mediator, and downstream signaling events (Stat3) were significantly increased in the Ereg^-/- mice in response to BHT, supporting both reduced inflammation and tumorigenesis. Lastly, wound healing was significantly increased with recombinant Ereg in both human and mouse lung epithelial cell lines. These results indicate that Ereg has proliferative potential and may be utilized as an early cancer biomarker as well as a novel potential therapeutic target. © 2016 Wiley Periodicals, Inc.

SATB2 expression increased anchorage-independent growth and cell migration in human bronchial epithelial cells

The special AT-rich sequence-binding protein 2 (SATB2) is a protein that binds to the nuclear matrix attachment region of the cell and regulates gene expression by altering chromatin structure. In our previous study, we reported that SATB2 gene expression was induced in human bronchial epithelial BEAS-2B cells transformed by arsenic, chromium, nickel and vanadium. In this study, we show that ectopic expression of SATB2 in the normal human bronchial epithelial cell-line BEAS-2B increased anchorage-independent growth and cell migration, meanwhile, shRNA-mediated knockdown of SATB2 significantly decreased anchorage-independent growth in Ni transformed BEAS-2B cells. RNA sequencing analyses of SATB2 regulated genes revealed the enrichment of those involved in cytoskeleton, cell adhesion and cell-movement pathways. Our evidence supports the hypothesis that SATB2 plays an important role in BEAS-2B cell transformation.

Vanadium compounds in medicine

Vanadium is a transition metal that, being ubiquitously distributed in soil, crude oil, water and air, also found roles in biological systems and is an essential element in most living beings. There are also several groups of organisms which accumulate vanadium, employing it in their biological processes. Vanadium being a biological relevant element, it is not surprising that many vanadium based therapeutic drugs have been proposed for the treatment of several types of diseases. Namely, vanadium compounds, in particular organic derivatives, have been proposed for the treatment of diabetes, of cancer and of diseases caused by parasites. In this work we review the medicinal applications proposed for vanadium compounds with particular emphasis on the more recent publications. In cells, partly due to the similarity of vanadate and phosphate, vanadium compounds activate numerous signaling pathways and transcription factors; this by itself potentiates application of vanadium-based therapeutics. Nevertheless, this non-specific bio-activity may also introduce several deleterious side effects as in addition, due to Fenton's type reactions or of the reaction with atmospheric O2, VCs may also generate reactive oxygen species, thereby introducing oxidative stress with consequences presently not well evaluated, particularly for long-term administration of vanadium to humans. Notwithstanding, the potential of vanadium compounds to treat type 2 diabetes is still an open question and therapies using vanadium compounds for e.g. antitumor and anti-parasitic related diseases remain promising.

Using gene expression profiling to evaluate cellular responses in mouse lungs exposed to V2O5 and a group of other mouse lung tumorigens and non-tumorigens

Many compounds test positive for lung tumors in two-year NTP carcinogenicity bioassays in B6C3F1 mice. V2O5 was identified as a lung carcinogen in this assay, leading to its IARC (International Agency for Research on Cancer) classification as group 2b or a "possible" human carcinogen. To assess potential tumorigenic mode of action of V2O5, we compared gene expression and gene ontology enrichment in lung tissue of female B6C3F1 mice exposed for 13 weeks to a V2O5 particulate aerosol at a tumorigenic level (2.0 mg/m(3)). Relative to 12 other compounds also tested for carcinogenicity in 2-year bioassays in mice, there were 1026 differentially expressed genes with V2O5, of which 483 were unique to V2O5. Ontology analysis of the 1026 V2O5 differentially expressed genes showed enrichment for hyaluronan and sphingolipid metabolism, adenylate cyclase functions, c-AMP signaling and PKA activation/signaling. Enrichment of lipids/lipoprotein metabolism and inflammatory pathways were consistent with previously reported clinical findings. Enrichment of c-AMP and PKA signaling pathways may arise due to inhibition of phosphatases, a known biological action of vanadate. We saw no enrichment for DNA-damage, oxidative stress, cell cycle, or apoptosis pathway signaling in mouse lungs exposed to V2O5 which is in contrast with past studies evaluating in vivo gene expression in target tissues of other carcinogens (arsenic, formaldehyde, naphthalene and chloroprene).

Single Exposure to near Roadway Particulate Matter Leads to Confined Inflammatory and Defense Responses: Possible Role of Metals

Inhalation of traffic-associated atmospheric particulate matter (PM2.5) is recognized as a significant health risk. In this study, we focused on a single ("subclinical response") exposure to water-soluble extracts from PM collected at a roadside site in a major European city to elucidate potential components that drive pulmonary inflammatory, oxidative, and defense mechanisms and their systemic impacts. Intratracheal instillation (IT) of the aqueous extracts induced a 24 h inflammatory response characterized by increased broncho-alveolar lavage fluid (BALF) cells and cytokines (IL-6 and TNF-α), increased reactive oxygen species production, but insignificant lipids and proteins oxidation adducts in mouse lungs. This local response was largely self-resolved by 48 h, suggesting that it could represent a subclinical response to everyday-level exposure. Removal of soluble metals by chelation markedly diminished the pulmonary PM-mediated response. An artificial metal solution (MS) recapitulated the PM extract response. The self-resolving nature of the response is associated with activating defense mechanisms (increased levels of catalase and glutathione peroxidase expression), observed with both PM extract and MS. In conclusion, metals present in PM collected near roadways are largely responsible for the observed transient local pulmonary inflammation and oxidative stress. Simultaneous activation of the antioxidant defense response may protect against oxidative damage.

Cyclooxygenase-1 as the main source of proinflammatory factors after sodium orthovanadate treatment

Vanadium is a metal present in air pollution. Its compounds may have both anticancer and carcinogenic properties. Vanadium compounds are tested in treatment of diabetes and cancer. An important research direction aimed at better understanding of the mechanisms of action of the vanadium compounds is a more detailed insight into their impact on inflammatory reactions. The aim of this study was to examine the effect of micromolar concentrations of sodium orthovanadate, Na3VO4, on the activity and expression of cyclooxygenases: COX-1 and COX-2. PMA-activated THP-1 macrophages were incubated in vitro for 48 h with micromolar concentrations of sodium orthovanadate. As shown by an ELISA assay, sodium orthovanadate increases the quantity of prostaglandin E2 being released into the medium in a dose-dependent manner as well as impacts the quantity of the stable metabolite of thromboxane A2: thromboxane B2. The use of a COX-2 inhibitor, NS-398, revealed that this effect was independent of changes in the activity of COX-2. Western blotting analysis showed that sodium orthovanadate increased the expression of COX-2 when used with NS-398. Quantitative real-time PCR measurements of mRNA levels of genes PTGS1 and PTGS2 revealed no effect of the tested vanadium compound on the levels of analyzed transcripts.

Functional and morphological olfactory bulb modifications in mice after vanadium inhalation

Neurodegenerative disorders, such as Parkinson's and Alzheimer's diseases, have olfaction impairment. These pathologies have also been linked to environmental pollutants. Vanadium is a pollutant, and its toxic mechanisms are related to the production of oxidative stress. In this study, we evaluated the effects of inhaled vanadium on olfaction, the olfactory bulb antioxidant, through histological and ultrastructural changes in granule cells. Mice in control group were made to inhale saline; the experimental group inhaled 0.02-M vanadium pentoxide (V2O5) for 1 hr twice a week for 4 weeks. Animals were sacrificed at 1, 2, 3, and 4 weeks after inhalation. Olfactory function was evaluated by the odorant test. The activity of glutathione peroxidase (GPx) and glutathione reductase (GR) was assayed in olfactory bulbs and processed for rapid Golgi method and ultrastructural analysis. Results show that olfactory function decreased at 4-week vanadium exposure; granule cells showed a decrease in dendritic spine density and increased lipofuscin, Golgi apparatus vacuolation, apoptosis, and necrosis. The activity of GPx and GR in the olfactory bulb was increased compared to that of the controls. Our results demonstrate that vanadium inhalation disturbs olfaction, histology, and the ultrastructure of the granule cells that might be associated with oxidative stress, a risk factor in neurodegenerative diseases.

A comparative study of the toxicological aspects of vanadium pentoxide and vanadium oxide nanoparticles

Indiscriminate use of vanadium oxide nanoparticles (NPs) in steel industries and their release during combustion of fossil fuels makes it essential to study their toxic potential. Herein, we assessed the toxicological effects of two types of in-house synthesized vanadium oxide NPs in Wistar rats exposed to NPs through inhalation route. V2O5 and VO2 NPs exhibited rod and spherical symmetry, respectively with a mean diameter of 50±20 and 30±10 nm. Assessment of bronchoalveolar lavage fluid parameters demonstrated that VO2 NP-exposed animals had higher levels of lactate dehydrogenase, gamma-glutamyl transpeptidase and alkaline phosphatase as compared to V2O5 NP-exposed animals. The levels of oxidative stress markers malondialdehyde and reduced glutathione also indicated higher toxic potential of VO2 NPs. Moreover, after 7-day recovery, the levels of the above parameters were closer to normal levels only in V2O5-exposed animals. Interestingly, histopathological and immune-histopathology analysis (TNF-α) of lung tissue showed higher damage and inflammatory response in VO2 NP-exposed animals, which persisted even after 7 days of recovery period. Surprisingly, the carcinogenic potential of vanadium oxide NPs came into light which was indicated by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay as well as the decreased levels of p53 and Bax, in lung tissue of NP-exposed animals. Notably, the physiochemical characterization of NPs, especially the shape and the size, play a central role in shaping the toxicity of these NPs and thus should be extensively evaluated for outlining the regulatory guidelines.

The role of neutrophil myeloperoxidase in models of lung tumor development

Chronic inflammation plays a key tumor-promoting role in lung cancer. Our previous studies in mice demonstrated that neutrophils are critical mediators of tumor promotion in methylcholanthrene (MCA)-initiated, butylated hydroxytoluene (BHT)-promoted lung carcinogenesis. In the present study we investigated the role of neutrophil myeloperoxidase (MPO) activity in this inflammation promoted model. Increased levels of MPO protein and activity were present in the lungs of mice administered BHT. Treatment of mice with N-acetyl lysyltyrosylcysteine amide (KYC), a novel tripeptide inhibitor of MPO, during the inflammatory stage reduced tumor burden. In a separate tumor model, KYC treatment of a Lewis Lung Carcinoma (LLC) tumor graft in mice had no effect on tumor growth, however, mice genetically deficient in MPO had significantly reduced LLC tumor growth. Our observations suggest that MPO catalytic activity is critical during the early stages of tumor development. However, during the later stages of tumor progression, MPO expression independent of catalytic activity appears to be required. Our studies advocate for the use of MPO inhibitors in a lung cancer prevention setting.

Promotion of lung adenocarcinoma following inhalation exposure to multi-walled carbon nanotubes

BACKGROUND

Engineered carbon nanotubes are currently used in many consumer and industrial products such as paints, sunscreens, cosmetics, toiletries, electronic processes and industrial lubricants. Carbon nanotubes are among the more widely used nanoparticles and come in two major commercial forms, single-walled carbon nanotubes (SWCNT) and the more rigid, multi-walled carbon nanotubes (MWCNT). The low density and small size of these particles makes respiratory exposures likely. Many of the potential health hazards have not been investigated, including their potential for carcinogenicity. We, therefore, utilized a two stage initiation/promotion protocol to determine whether inhaled MWCNT act as a complete carcinogen and/or promote the growth of cells with existing DNA damage. Six week old, male, B6C3F1 mice received a single intraperitoneal (ip) injection of either the initiator methylcholanthrene(MCA, 10 μg/g BW, i.p.), or vehicle (corn oil). One week after i.p. injections, mice were exposed by inhalation to MWCNT (5 mg/m³, 5 hours/day, 5 days/week) or filtered air (controls) for a total of 15 days. At 17 months post-exposure, mice were euthanized and examined for lung tumor formation.

RESULTS

Twenty-three percent of the filtered air controls, 26.5% of the MWCNT-exposed, and 51.9% of the MCA-exposed mice, had lung bronchiolo-alveolar adenomas and lung adenocarcinomas. The average number of tumors per mouse was 0.25, 0.81 and 0.38 respectively. By contrast, 90.5% of the mice which received MCA followed by MWCNT had bronchiolo-alveolar adenomas and adenocarcinomas with an average of 2.9 tumors per mouse 17 months after exposure. Indeed, 62% of the mice exposed to MCA followed by MWCNT had bronchiolo-alveolar adenocarcinomas compared to 13% of the mice that received filtered air, 22% of the MCA-exposed, or 14% of the MWCNT-exposed. Mice with early morbidity resulting in euthanasia had the highest rate of metastatic disease. Three mice exposed to both MCA and MWCNT that were euthanized early had lung adenocarcinoma with evidence of metastasis (5.5%). Five mice (9%) exposed to MCA and MWCNT and 1 (1.6%) exposed to MCA developed serosal tumors morphologically consistent with sarcomatous mesotheliomas, whereas mice administered MWCNT or air alone did not develop similar neoplasms.

CONCLUSIONS

These data demonstrate that some MWCNT exposures promote the growth and neoplastic progression of initiated lung cells in B6C3F1 mice. In this study, the mouse MWCNT lung burden of 31.2 μg/mouse approximates feasible human occupational exposures. Therefore, the results of this study indicate that caution should be used to limit human exposures to MWCNT.

Sodium metavanadate exhibits carcinogenic tendencies in vitro in immortalized human bronchial epithelial cells

Pentavalent vanadium compounds induce intracellular changes in vitro that are consistent with those of other carcinogenic substances. While there is no clear evidence that vanadium compounds cause cancer in humans, vanadium pentoxide causes lung cancer in rodents after long-term inhalation exposures and in turn IARC has categorized it as a group 2B possible human carcinogen. The goal of this study was to investigate the carcinogenicity of NaVO3 in the human immortalized bronchial epithelial cell line, Beas-2B. Cells were treated with 10 μM NaVO3 for 5 weeks, with or without recovery time, followed by gene expression microarray analysis. In a separate experiment, cells were exposed to 1-10 μM NaVO3 for 4 weeks and then grown in soft agar to test for anchorage-independent growth. A dose-dependent increase in the number of colonies was observed. In scratch tests, NaVO3-transformed clones could repair a wound faster than controls. In a gene expression microarray analysis of soft agar clones there were 2010 differentially expressed genes (DEG) (adjusted p-value ≤ 0.05) in NaVO3-transformed clones relative to control clones. DEG from this experiment were compared with the DEG of 5 week NaVO3 exposure with or without recovery, all with adjusted p-values < 0.05, and 469 genes were altered in the same direction for transformed clones, 5 week NaVO3-treated cells, and the recovered cells. The data from this study imply that chronic exposure to NaVO3 causes changes that are consistent with cellular transformation including anchorage-independent growth, enhanced migration ability, and gene expression changes that were likely epigenetically inherited.

Lung tumor promotion by chromium-containing welding particulate matter in a mouse model

BACKGROUND

Epidemiology suggests that occupational exposure to welding particulate matter (PM) may increase lung cancer risk. However, animal studies are lacking to conclusively link welding with an increased risk. PM derived from stainless steel (SS) welding contains carcinogenic metals such as hexavalent chromium and nickel. We hypothesized that welding PM may act as a tumor promoter and increase lung tumor multiplicity in vivo. Therefore, the capacity of chromium-containing gas metal arc (GMA)-SS welding PM to promote lung tumors was evaluated using a two-stage (initiation-promotion) model in lung tumor susceptible A/J mice.

METHODS

Male mice (n = 28-30/group) were treated either with the initiator 3-methylcholanthrene (MCA;10 μg/g; IP) or vehicle (corn oil) followed by 5 weekly pharyngeal aspirations of GMA-SS (340 or 680 μg/exposure) or PBS. Lung tumors were enumerated at 30 weeks post-initiation.

RESULTS

MCA initiation followed by GMA-SS welding PM exposure promoted tumor multiplicity in both the low (12.1 ± 1.5 tumors/mouse) and high (14.0 ± 1.8 tumors/mouse) exposure groups significantly above MCA/sham (4.77 ± 0.7 tumors/mouse; p = 0.0001). Multiplicity was also highly significant (p < 0.004) across all individual lung regions of GMA-SS-exposed mice. No exposure effects were found in the corn oil groups at 30 weeks. Histopathology confirmed the gross findings and revealed increased inflammation and a greater number of malignant lesions in the MCA/welding PM-exposed groups.

CONCLUSIONS

GMA-SS welding PM acts as a lung tumor promoter in vivo. Thus, this study provides animal evidence to support the epidemiological data that show welders have an increased lung cancer risk.

Polycyclic aromatic hydrocarbon-induced signaling events relevant to inflammation and tumorigenesis in lung cells are dependent on molecular structure

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental and occupational toxicants, which are a major human health concern in the U.S. and abroad. Previous research has focused on the genotoxic events caused by high molecular weight PAHs, but not on non-genotoxic events elicited by low molecular weight PAHs. We used an isomeric pair of low molecular weight PAHs, namely 1-Methylanthracene (1-MeA) and 2-Methylanthracene (2-MeA), in which only 1-MeA possessed a bay-like region, and hypothesized that 1-MeA, but not 2-MeA, would affect non-genotoxic endpoints relevant to tumor promotion in murine C10 lung cells, a non-tumorigenic type II alveolar pneumocyte and progenitor cell type of lung adenocarcinoma. The non-genotoxic endpoints assessed were dysregulation of gap junction intercellular communication function and changes in the major pulmonary connexin protein, connexin 43, using fluorescent redistribution and immunoblots, activation of mitogen activated protein kinases (MAPK) using phosphospecific MAPK antibodies for immunoblots, and induction of inflammatory genes using quantitative RT-PCR. 2-MeA had no effect on any of the endpoints, but 1-MeA dysregulated gap junctional communication in a dose and time dependent manner, reduced connexin 43 protein expression, and altered membrane localization. 1-MeA also activated ERK1/2 and p38 MAP kinases. Inflammatory genes, such as cyclooxygenase 2, and chemokine ligand 2 (macrophage chemoattractant 2), were also upregulated in response to 1-MeA only. These results indicate a possible structure-activity relationship of these low molecular weight PAHs relevant to non-genotoxic endpoints of the promoting aspects of cancer. Therefore, our novel findings may improve the ability to predict outcomes for future studies with additional toxicants and mixtures, identify novel targets for biomarkers and chemotherapeutics, and have possible implications for future risk assessment for these PAHs.

Occupational chronic obstructive pulmonary disease: an update

Chronic obstructive pulmonary disease represents a major cause of morbidity and mortality in industrialized and nonindustrialized countries. Although tobacco use remains the main factor associated with development of the disease, occupational risk factors represent an important and preventable cause. The most common occupationally related factors include exposure to organic dusts, metallic fumes, and a variety of other mineral gases and/or vapors. This article summarizes the literature on the subject and provides an update of the most recent advances in the field.

Novel ternary vanadium-betaine-peroxido species suppresses H-ras and matrix metalloproteinase-2 expression by increasing reactive oxygen species-mediated apoptosis in cancer cells

Vanadium is known for its antitumorigenicity. Poised to investigate the impact of well-defined forms of vanadium on processes and specific biomolecules (oncogenes-proteins) involved in cancer cell physiology, a novel ternary V(V)-peroxido-betaine compound was employed in experiments targeting cell viability, apoptosis, reactive oxygen species (ROS) production, H-ras signaling, and matrix metalloproteinase-2 (MMP-2) expression in human breast cancer epithelial and lung adenocarcinoma cells. The results reveal that vanadium imparts a significant decrease in cancer cell viability, reducing H-ras and MMP-2 expression by increasing ROS-mediated apoptosis, distinctly emphasizing the nature, structure and properties of ternary ligands on vanadium anti-tumor activity and its future potential as a metallodrug.

The potentiality of vanadium in medicinal applications

In the early treatment of diabetes with vanadium, inorganic vanadium compounds have been the focus of attention; organic vanadium compounds are nowadays increasingly attracting attention. A key compound is bis(maltolato)oxidovanadium, which became introduced into clinical tests Phase IIa. Organic ligands help modulate the bioavailability, transport and targeting mechanism of a vanadium compound. Commonly, however, the active onsite species is vanadyl (VO(2+)) or vanadate (H(2)VO(4) (-)), generated by biospeciation. The mode of operation can be ascribed to interaction of vanadate with phosphatases and kinases, and to modulation of the level of reactive oxygen species interfering with phosphatases and/or DNA. This operating mode has also been inferred for most cancerostatic vanadium compounds, although some, for example vanadocenes, may directly intercalate with DNA. Novel medicinal potentiality of vanadium compounds is geared towards endemic diseases in tropical countries, in particular leishmaniasis, Chagas' disease and amoebiasis, and viral infections such as Dengue fever, SARS and HIV.

Bronchoalveolar Lavage Fluid Utilized Ex Vivo to Validate In Vivo Findings: Inhibition of Gap Junction Activity in Lung Tumor Promotion is Toll-Like Receptor 4-Dependent

TLR4 protects against lung tumor promotion and pulmonary inflammation in mice. Connexin 43 (Cx43), a gap junction gene, was increased in Tlr4 wildtype compared to Tlr4-mutant mice in response to promotion, which suggests gap junctional intercellular communication (GJIC) may be compromised. We hypothesized that the early tumor microenvironment, represented by Bronchoalveolar Lavage Fluid (BALF) from Butylated hydroxytoluene (BHT; promoter)-treated mice, would produce TLR4-dependent changes in pulmonary epithelium, including dysregulation of GJIC in the Tlr4-mutant (BALB^Lps-d) compared to the Tlr4-sufficient (BALB; wildtype) mice. BHT (4 weekly doses) was injected ip followed by BALF collection at 24 h. BALF total protein and total macrophages were significantly elevated in BHT-treated BALB^Lps-d over BALB mice, similar to previous findings. BALF was then utilized in an ex vivo manner to treat C10 cells, a murine alveolar type II cell line, followed by the scrape-load dye transfer assay (GJIC), Cx43 immunostaining, and quantitative RT-PCR (Mcp-1, monocyte chemotactic protein 1). GJIC was markedly reduced in C10 cells treated with BHT-treated BALB^Lps-d BALF for 4 and 24 h compared to BALB and control BALF from the respective mice (p < 0.05). Mcp-1, a chemokine, was also significantly increased in the BHT-treated BALB^Lps-d BALF compared to the BALB mice, and Cx43 protein expression in the cell membrane altered. These novel findings suggest signaling from the BALF milieu is involved in GJIC dysregulation associated with promotion and links gap junctions to pulmonary TLR4 protection in a novel ex vivo model that could assist in future potential tumor promoter screening.

B-cells and IL-4 promote methylcholanthrene-induced carcinogenesis but there is no evidence for a role of T/NKT-cells and their effector molecules (Fas-ligand, TNF-α, perforin)

Mice deficient either in subtypes of immune cells, cytokines or lytic pathways have been subjected to chemical carcinogenesis by methylcholanthrene to evaluate whether these components of the immune system affect tumor development. Inbred mice of the same genotype but from different sources differed in tumor development in magnitude comparable to that previously attributed to differences in immunocompetence. This suggested that genetic drift between separate inbred colonies of mice and/or environmental factors (e.g., transport of the animals) influenced carcinogenesis. Therefore, littermates were used as control in subsequent experiments. Although deficiency of T-cells, NKT-cells, perforin, Fas-ligand, TNF-α-receptor failed to reveal significant differences in tumor development, the presence of B-cells and IL-4 enhanced tumor development under similar experimental conditions.

Neutrophils are required for 3-methylcholanthrene-initiated, butylated hydroxytoluene-promoted lung carcinogenesis

Multiple studies have shown a link between chronic inflammation and lung tumorigenesis. Inbred mouse strains vary in their susceptibility to methylcholanthrene (MCA)-initiated butylated hydroxytoluene (BHT)-promoted lung carcinogenesis. In the present study we investigated whether neutrophils play a role in strain dependent differences in susceptibility to lung tumor promotion. We observed a significant elevation in homeostatic levels of neutrophils in the lungs of tumor-susceptible BALB/cByJ (BALB) mice compared to tumor-resistant C57BL/6J (B6) mice. Additionally, BHT treatment further elevated neutrophil numbers as well as neutrophil chemoattractant keratinocyte-derived cytokine (KC)/chemokine (C-X-C motif) ligand 1 (Cxcl1) levels in BALB lung airways. Lung CD11c+ cells were a major source of KC expression and depletion of neutrophils in BALB mice resulted in a 71% decrease in tumor multiplicity. However, tumor multiplicity did not depend on the presence of T cells, despite the accumulation of T cells following BHT treatment. These data demonstrate that neutrophils are essential to promote tumor growth in the MCA/BHT two-step lung carcinogenesis model.

First Steps Towards an Understanding of a Mode ofCarcinogenic Action for Vanadium Pentoxide

Inhalation of vanadium pentoxide clearly increases the incidence of alveolar/bronchiolar neoplasms in male and female B6C3F1 mice at all concentrations tested (1, 2 or 4 mg/m³), whereas responses in F344/N rats was, at most, ambiguous. While vanadium pentoxide is mutagenic in vitro and possibly in vivo in mice, this does not explain the species or site specificity of the neoplastic response. A nose-only inhalation study was conducted in female B6C3F1 mice (0, 0.25, 1 and 4 mg/m³, 6 h/day for 16 days) to explore histopathological, biochemical (α-tocopherol, glutathione and F2-isoprostane) and genetic (comet assays and 9 specific DNA-oxo-adducts) changes in the lungs. No treatment related histopathology was observed at 0.25 mg/m³. At 1 and 4 mg/m³, exposure-dependent increases were observed in lung weight, alveolar histiocytosis, sub-acute alveolitis and/or granulocytic infiltration and a generally time-dependent increased cell proliferation rate of histiocytes. Glutathione was slightly increased, whereas there were no consistent changes in α-tocopherol or 8-isoprostane F2α. There was no evidence for DNA strand breakage in lung or BAL cells, but there was an increase in 8-oxodGuo DNA lesions that could have been due to vanadium pentoxide induction of the lesions or inhibition of repair of spontaneous lesions. Thus, earlier reports of histopathological changes in the lungs after inhalation of vanadium pentoxide were confirmed, but no evidence has yet emerged for a genotoxic mode of action. Evidence is weak for oxidative stress playing any role in lung carcinogenesis at the lowest effective concentrations of vanadium pentoxide.

Identification of candidate genes downstream of TLR4 signaling after ozone exposure in mice: a role for heat-shock protein 70

BACKGROUND

Toll-like receptor 4 (TLR4) is involved in ozone (O3)-induced pulmonary hyperpermeability and inflammation, although the downstream signaling events are unknown.

OBJECTIVES

The aims of our study were to determine the mechanism through which TLR4 modulates O3-induced pulmonary responses and to use transcriptomics to determine potential TLR4 effector molecules.

METHODS

C3H/HeJ (HeJ; Tlr4 mutant) and C3H/HeOuJ (OuJ; Tlr4 normal) mice were exposed continuously to 0.3 ppm O3 or filtered air for 6, 24, 48, or 72 hr. We assessed inflammation using bronchoalveolar lavage and molecular analysis by mRNA microarray, quantitative RT-PCR (real-time polymerase chain reaction), immunoblots, immunostaining, and ELISAs (enzyme-linked immunosorbent assays). B6-Hspa1a/Hspa1btm1Dix/NIEHS (Hsp70-/-) and C57BL/6 (B6; Hsp70+/+ wild-type control) mice were used for candidate gene validation studies.

RESULTS

O3-induced TLR4 signaling occurred through myeloid differentiation protein 88 (MyD88)-dependent and -independent pathways in OuJ mice and involved multiple downstream pathways. Genomewide transcript analyses of lungs from air- and O3-exposed HeJ and OuJ mice identified a cluster of genes that were significantly up-regulated in O3-exposed OuJ mice compared with O3-exposed HeJ mice or air-exposed controls of both strains; this cluster included genes for heat-shock proteins (e.g., Hspa1b, Hsp70). Moreover, O3-induced inflammation, MyD88 up-regulation, extracellular-signal-related kinase-1/2 (ERK1/2) and activator protein-1 (AP-1) activation, and kerotinocyte-derived chemokine (KC) protein content were significantly reduced in Hspa1a/Hspa1btm1Dix (Hsp70-/-) compared with Hsp70+/+ mice (p < 0.05).

CONCLUSIONS

These studies suggest that HSP70 is an effector molecule downstream of TLR4 and is involved in the regulation of O3-induced lung inflammation by triggering similar pathways to TLR4. These novel findings may have therapeutic and preventive implications for inflammatory diseases resulting from environmental exposures.

Lung tumor production and tissue metal distribution after exposure to manual metal ARC-stainless steel welding fume in A/J and C57BL/6J mice

Stainless steel welding produces fumes that contain carcinogenic metals. Therefore, welders may be at risk for the development of lung cancer, but animal data are inadequate in this regard. Our main objective was to examine lung tumor production and histopathological alterations in lung-tumor-susceptible (A/J) and -resistant C57BL/6J (B6) mice exposed to manual metal arc-stainless steel (MMA-SS) welding fume. Male mice were exposed to vehicle or MMA-SS welding fume (20 mg/kg) by pharyngeal aspiration once per month for 4 mo. At 78 wk postexposure, gross tumor counts and histopathological changes were assessed and metal analysis was done on extrapulmonary tissue (aorta, heart, kidney, and liver). At 78 wk postexposure, gross lung tumor multiplicity and incidence were unremarkable in mice exposed to MMA-SS welding fume. Histopathology revealed that only the exposed A/J mice contained minimal amounts of MMA-SS welding fume in the lung and statistically increased lymphoid infiltrates and alveolar macrophages. A significant increase in tumor multiplicity in the A/J strain was observed at 78 wk. Metal analysis of extrapulmonary tissue showed that only the MMA-SS-exposed A/J mice had elevated levels of Cr, Cu, Mn, and Zn in kidney and Cr in liver. In conclusion, this study further supports that MMA-SS welding fume does not produce a significant tumorigenic response in an animal model, but may induce a chronic lung immune response. In addition, long-term extrapulmonary tissue alterations in metals in the susceptible A/J mouse suggest that the adverse effects of this fume might be cumulative.