Xenobiotic pulmonary exposure and systemic cardiovascular response via neurological links

Whole-body inhalation of nano-sized carbon black: a surrogate model of military burn pit exposure

OBJECTIVE

Chronic multisymptom illness (CMI) is an idiopathic disease affecting thousands of U.S. Veterans exposed to open-air burn pits emitting aerosolized particulate matter (PM) while serving in Central and Southwest Asia and Africa. Exposure to burn pit PM can result in profound biologic consequences including chronic fatigue, impaired cognition, and respiratory diseases. Dysregulated or unresolved inflammation is a possible underlying mechanism for CMI onset. We describe a rat model of whole-body inhalation exposure using carbon black nanoparticles (CB) as a surrogate for military burn pit-related exposure. Using this model, we measured biomarkers of inflammation in multiple tissues.

RESULTS

Male Sprague Dawley rats were exposed to CB aerosols by whole body inhalation (6 ± 0.83 mg/m3). Proinflammatory biomarkers were measured in multiple tissues including arteries, brain, lung, and plasma. Biomarkers of cardiovascular injury were also assayed in plasma. CB inhalation exposure increased CMI-related proinflammatory biomarkers such as IFN-γ and TNFα in multiple tissue samples. CB exposure also induced cardiovascular injury markers (adiponectin, MCP1, sE-Selectin, sICam-1 and TIMP1) in plasma. These findings support the validity of our animal exposure model for studies of burn pit-induced CMI. Future studies will model more complex toxicant mixtures as documented at multiple burn pit sites.

Exacerbation of Thrombotic Responses to Silver Nanoparticles in Hypertensive Mouse Model

With advent of nanotechnology, silver nanoparticles, AgNPs owing majorly to their antibacterial properties, are used widely in food industry and biomedical applications implying human exposure by various routes including inhalation. Several reports have suggested AgNPs induced pathophysiological effects in a cardiovascular system. However, cardiovascular diseases such as hypertension may interfere with AgNPs-induced response, yet majority of them are understudied. The aim of this work was to evaluate the thrombotic complications in response to polyethylene glycol- (PEG-) coated AgNPs using an experimental hypertensive (HT) mouse model. Saline (control) or PEG-AgNPs (0.5 mg/kg) were intratracheally (i.t.) instilled four times, i.e., on days 7, 14, 21, and 28 post-angiotensin II-induced HT, or vehicle (saline) infusion. On day 29, various parameters were assessed including thrombosis in pial arterioles and venules, platelet aggregation in whole blood in vitro, plasma markers of coagulation, and fibrinolysis and systemic oxidative stress. Pulmonary exposure to PEG-AgNPs in HT mice induced an aggravation of in vivo thrombosis in pial arterioles and venules compared to normotensive (NT) mice exposed to PEG-AgNPs or HT mice given saline. The prothrombin time, activated partial thromboplastin time, and platelet aggregation in vitro were exacerbated after exposure to PEG-AgNPs in HT mice compared with either NT mice exposed to nanoparticles or HT mice exposed to saline. Elevated concentrations of fibrinogen, plasminogen activator inhibitor-1, and von Willebrand factor were seen after the exposure to PEG-AgNPs in HT mice compared with either PEG-AgNPs exposed NT mice or HT mice given with saline. Likewise, the plasma levels of superoxide dismutase and nitric oxide were augmented by PEG-AgNPs in HT mice compared with either NT mice exposed to nanoparticles or HT mice exposed to saline. Collectively, these results demonstrate that PEG-AgNPs can potentially exacerbate the in vivo and in vitro procoagulatory and oxidative stress effect in HT mice and suggest that population with hypertension are at higher risk of the toxicity of PEG-AgNPs.

Identification and quantification of gold engineered nanomaterials and impaired fluid transfer across the rat placenta via ex vivo perfusion

Development and implementation of products incorporating nanoparticles are occurring at a rapid pace. These particles are widely utilized in domestic, occupational, and biomedical applications. Currently, it is unclear if pregnant women will be able to take advantage of the potential biomedical nanoproducts out of concerns associated with placental transfer and fetal interactions. We recently developed an ex vivo rat placental perfusion technique to allow for the evaluation of xenobiotic transfer and placental physiological perturbations. In this study, a segment of the uterine horn and associated placenta was isolated from pregnant (gestational day 20) Sprague-Dawley rats and placed into a modified pressure myography vessel chamber. The proximal and distal ends of the maternal uterine artery and the vessels of the umbilical cord were cannulated, secured, and perfused with physiological salt solution (PSS). The proximal uterine artery and umbilical artery were pressurized at 80 mmHg and 50 mmHg, respectively, to allow countercurrent flow through the placenta. After equilibration, a single 900 μL bolus dose of 20 nm gold engineered nanoparticles (Au-ENM) was introduced into the proximal maternal artery. Distal uterine and umbilical vein effluents were collected every 10 min for 180 min to measure placental fluid dynamics. The quantification of Au-ENM transfer was conducted via inductively coupled plasma mass spectrometry (ICP-MS). Overall, we were able to measure Au-ENM within uterine and umbilical effluent with 20 min of material infusion. This novel methodology may be widely incorporated into studies of pharmacology, toxicology, and placental physiology.

Impact of pulmonary exposure to gold core silver nanoparticles of different size and capping agents on cardiovascular injury

BACKGROUND

The uses of engineered nanomaterials have expanded in biomedical technology and consumer manufacturing. Furthermore, pulmonary exposure to various engineered nanomaterials has, likewise, demonstrated the ability to exacerbate cardiac ischemia reperfusion (I/R) injury. However, the influence of particle size or capping agent remains unclear. In an effort to address these influences we explored response to 2 different size gold core nanosilver particles (AgNP) with two different capping agents at 2 different time points. We hypothesized that a pulmonary exposure to AgNP induces cardiovascular toxicity influenced by inflammation and vascular dysfunction resulting in expansion of cardiac I/R Injury that is sensitive to particle size and the capping agent.

METHODS

Male Sprague-Dawley rats were exposed to 200 μg of 20 or 110 nm polyvinylprryolidone (PVP) or citrate capped AgNP. One and 7 days following intratracheal instillation serum was analyzed for concentrations of selected cytokines; cardiac I/R injury and isolated coronary artery and aorta segment were assessed for constrictor responses and endothelial dependent relaxation and endothelial independent nitric oxide dependent relaxation.

RESULTS

AgNP instillation resulted in modest increase in selected serum cytokines with elevations in IL-2, IL-18, and IL-6. Instillation resulted in a derangement of vascular responses to constrictors serotonin or phenylephrine, as well as endothelial dependent relaxations with acetylcholine or endothelial independent relaxations by sodium nitroprusside in a capping and size dependent manner. Exposure to both 20 and 110 nm AgNP resulted in exacerbation cardiac I/R injury 1 day following IT instillation independent of capping agent with 20 nm AgNP inducing marginally greater injury. Seven days following IT instillation the expansion of I/R injury persisted but the greatest injury was associated with exposure to 110 nm PVP capped AgNP resulted in nearly a two-fold larger infarct size compared to naïve.

CONCLUSIONS

Exposure to AgNP may result in vascular dysfunction, a potentially maladaptive sensitization of the immune system to respond to a secondary insult (e.g., cardiac I/R) which may drive expansion of I/R injury at 1 and 7 days following IT instillation where the extent of injury could be correlated with capping agents and AgNP size.