No abstract

Objective Up to 44% of particulates of food-grade titanium dioxide (TiO2) are in nanoscale, while the effect and combined effect of which with other substances on intestinal barrier haven’t been fully understood yet. This study is aimed to study the effect of two kinds of TiO2 nanoparticles (TiO2 NPs and TiO2 MPs) on intestinal barrier functions, to reveal the combined effect of TiO2 NPs and Lipopolysaccharide (LPS) on intestinal barrier. Methods Male ICR mice were randomly divided into 18 groups (3 feed types * 3 exposure length * 2 LPS dosage) and were fed with normal or TiO2-mixed feed (containing 1% (mass fraction, w/w) TiO2 NPs or TiO2 MPs) for 1, 3, 6 months, followed by a single oral administration of 0 or 10 mg/(kg body weight) LPS. Four hours later, the transportation of TiO2, the intestinal barrier functions and the inflammatory response were evaluated. Results Both TiO2 notably increased the intestinal villi height / crypt depth ratios after 1 and 3 months of exposure, and increased the expression of ileal tight junction proteins (ZO-1 and occludin) after 1 month of exposure. After 6 months of exposure, TiO2 NPs led to reduced feed consumption, TiO2 MPs caused spare microvilli in small intestine and elevated Ti content in the blood cells. The intestinal permeability didn’t change in both TiO2 exposed groups. After LPS administration, we observed altered intestinal villi height / crypt depth ratios, lowered intestinal permeability (DAO) and upregulated expression of ileal ZO-1 in both (TiO2 +LPS) exposed groups. There are no significant changes of ileal or serum cytokines except for a higher serum TNF-α level in LPS treated group. The antagonistic effect was found between TiO2 NPs and LPS, but there are complicated interactions between TiO2 MPs and LPS. Conclusion Long-term intake of food additive TiO2 could alter the intestinal epithelial structure without influencing intestinal barrier function. Co-exposure of TiO2 and LPS would enhance intestinal barrier function without causing notable inflammatory responses, and there is antagonistic effect between TiO2 NPs and LPS. All the minor effects observed might associate with the gentle exposure method where TiO2 being ingested with feed.

Background: Using engineered nanomaterial-based toners, laser printers generate aerosols with alarming levels of nanoparticles that bear high bioactivity and potential health risks. Yet, the cardiac impacts of printer-emitted particles (PEPs) are unknown. Inhalation of particulate matter (PM) promotes cardiovascular morbidity and mortality, and ultra-fine particulates (< 0.1 μm aerodynamic diameter) may bear toxicity unique from larger particles. Toxicological studies suggest that PM impairs left ventricular (LV) performance; however, such investigations have heretofore required animal restraint, anesthesia, or ex vivo preparations that can confound physiologic endpoints and/or prohibit LV mechanical assessments during exposure. To assess the acute and chronic effects of PEPs on cardiac physiology, male Sprague Dawley rats were exposed to PEPs (21 days, 5 h/day) while monitoring LV pressure (LVP) and electrocardiogram (ECG) via conscious telemetry, analyzing LVP and heart rate variability (HRV) in four-day increments from exposure days 1 to 21, as well as ECG and baroreflex sensitivity. At 2, 35, and 70 days after PEPs exposure ceased, rats received stress tests. Results: On day 21 of exposure, PEPs significantly (P < 0.05 vs. Air) increased LV end systolic pressure (LVESP, + 18 mmHg) and rate-pressure-product (+ 19%), and decreased HRV indicating sympathetic dominance (root means squared of successive differences [RMSSD], − 21%). Overall, PEPs decreased LV ejection time (− 9%), relaxation time (− 3%), tau (− 5%), RMSSD (− 21%), and P-wave duration (− 9%). PEPs increased QTc interval (+ 5%) and low:high frequency HRV (+ 24%; all P < 0.05 vs. Air), while tending to decrease baroreflex sensitivity and contractility index (− 15% and − 3%, P < 0.10 vs. Air). Relative to Air, at both 2 and 35 days after PEPs, ventricular arrhythmias increased, and at 70 days post-exposure LVESP increased. PEPs impaired ventricular repolarization at 2 and 35 days postexposure, but only during stress tests. At 72 days post-exposure, PEPs increased urinary dopamine 5-fold and protein expression of ventricular repolarizing channels, K v 1.5, K v 4.2, and K v 7.1, by 50%. Conclusions: Our findings suggest exposure to PEPs increases cardiovascular risk by augmenting sympathetic influence, impairing ventricular performance and repolarization, and inducing hypertension and arrhythmia. PEPs may present significant health risks through adverse cardiovascular effects, especially in occupational settings, among susceptible individuals, and with long-term exposure.