Cytotoxicity of 2D engineered nanomaterials in pulmonary and corneal epithelium.

Two-dimensional (2D) engineered nanomaterials are widely used in consumer and industrial goods due to their unique chemical and physical characteristics. Engineered nanomaterials are incredibly small and capable of being aerosolized during manufacturing, with the potential for biological interaction at first-contact sites such as the eye and lung. The unique properties of 2D nanomaterials that make them of interest to many industries may also cause toxicity towards epithelial cells. Using murine and human respiratory epithelial cell culture models, we tested the cytotoxicity of eight 2D engineered nanomaterials: graphene (110 nm), graphene oxide (2 um), graphene oxide (400 nm), reduced graphene oxide (2 um), reduced graphene oxide (400 nm), partially reduced graphene oxide (400 nm), molybdenum disulfide (400 nm), and hexagonal boron nitride (150 nm). Non-graphene nanomaterials were also tested in human corneal epithelial cells for ocular epithelial cytotoxicity. Hexagonal boron nitride was found to be cytotoxic in mouse tracheal, human alveolar, and human corneal epithelial cells. Hexagonal boron nitride was also tested for inhibition of wound healing in alveolar epithelial cells; no inhibition was seen at sub-cytotoxic doses. Nanomaterials should be considered with care before use, due to specific regional cytotoxicity that also varies by cell type. Supported by U01ES027288 and T32HL007013 and T32ES007059.

Metabolomics of Lung Microdissections Reveals Region- and Sex-Specific Metabolic Effects of Acute Naphthalene Exposure in Mice.

Naphthalene is a ubiquitous environmental contaminant produced by combustion of fossil fuels and is a primary constituent of both mainstream and side stream tobacco smoke. Naphthalene elicits region-specific toxicity in airway club cells through cytochrome P450 (P450)-mediated bioactivation, resulting in depletion of glutathione and subsequent cytotoxicity. Although effects of naphthalene in mice have been extensively studied, few experiments have characterized global metabolomic changes in the lung. In individual lung regions, we found metabolomic changes in microdissected mouse lung conducting airways and parenchyma obtained from animals sacrificed at 3 timepoints following naphthalene treatment. Data on 577 unique identified metabolites were acquired by accurate mass spectrometry-based assays focusing on lipidomics and nontargeted metabolomics of hydrophilic compounds. Statistical analyses revealed distinct metabolite profiles between the 2 lung regions. Additionally, the number and magnitude of statistically significant exposure-induced changes in metabolite abundance were different between airways and parenchyma for unsaturated lysophosphatidylcholines, dipeptides, purines, pyrimidines, and amino acids. Importantly, temporal changes were found to be highly distinct for male and female mice with males exhibiting predominant treatment-specific changes only at 2 h postexposure. In females, metabolomic changes persisted until 6 h postnaphthalene treatment, which may explain the previously characterized higher susceptibility of female mice to naphthalene toxicity. In both males and females, treatment-specific changes corresponding to lung remodeling, oxidative stress response, and DNA damage were observed. Overall, this study provides insights into potential mechanisms contributing to naphthalene toxicity and presents a novel approach for lung metabolomic analysis that distinguishes responses of major lung regions.

S-nitrosoglutathione preserves platelet function during in vitro ventricular assist device circulation.

Complications (severe bleeding/thromboembolism) may occur during ventricular assist device (VAD) circulation, caused mainly by platelet dysfunction from platelet activation. We hypothesized that S-nitrosoglutathione (GSNO), having platelet activity preservation properties like nitric oxide (NO), may be a titratable agent to diminish platelet activation and thus preserve platelet function. Dose-response measurement of platelet aggregation by GSNO was performed using an aggregometer. GSNO (1,000 microM) caused inhibition of collagen and ristocetin induced aggregation by approximately 50%. Next, in vitro ventricular assist device (VAD) circulation was performed (over 48 hours using human whole blood), both without (control) and with GSNO (1,000 microM), and the aggregability of perfusate was measured at 0, 0.5, 1, 3, 6, 12, 24, and 48 hours. In control VAD circuits, collagen induced platelet aggregability gradually decreased and became significantly lower after 3 hours of circulation. With GSNO, platelet function did not significantly decrease until after 12 hours. Similar results were seen for ristocetin induced aggregation; control aggregation dropped significantly after 6 hours, but not until after 24 hours with GSNO. Liquid phase measurement of total nitrogen oxides (NO(T)) confirmed added GSNO maintained high perfusate NO(T) compared with control. GSNO is effective in preserving platelet aggregation during the first 12 to 24 hours in vitro and may be effective in preserving platelet function by inhibiting platelet activation during in vivo VAD circulation.