Protective effect of curcumin on pulmonary and cardiovascular effects induced by repeated exposure to diesel exhaust particles in mice

Amorphous silica nanoparticles impair vascular homeostasis and induce systemic inflammation

Amorphous silica nanoparticles (SiNPs) are being used in biomedical, pharmaceutical, and many other industrial applications entailing human exposure. However, their potential vascular and systemic pathophysiologic effects are not fully understood. Here, we investigated the acute (24 hours) systemic toxicity of intraperitoneally administered 50 nm and 500 nm SiNPs in mice (0.5 mg/kg). Both sizes of SiNPs induced a platelet proaggregatory effect in pial venules and increased plasma concentration of plasminogen activator inhibitor-1. Elevated plasma levels of von Willebrand factor and fibrinogen and a decrease in the number of circulating platelets were only seen following the administration of 50 nm SiNPs. The direct addition of SiNPs to untreated mouse blood significantly induced in vitro platelet aggregation in a dose-dependent fashion, and these effects were more pronounced with 50 nm SiNPs. Both sizes of SiNPs increased lactate dehydrogenase activity and interleukin 1β concentration. However, tumor necrosis factor α concentration was only increased after the administration of 50 nm SiNPs. Nevertheless, plasma markers of oxidative stress, including 8-isoprostane, thiobarbituric acid reactive substances, catalase, and glutathione S-transferase, were not affected by SiNPs. The in vitro exposure of human umbilical vein endothelial cells to SiNPs showed a reduced cellular viability, and more potency was seen with 50 nm SiNPs. Both sizes of SiNPs caused a decrease in endothelium-dependent relaxation of isolated small mesenteric arteries. We conclude that amorphous SiNPs cause systemic inflammation and coagulation events, and alter vascular reactivity. Overall, the effects observed with 50 nm SiNPs were more pronounced than those with 500 nm SiNPs. These findings provide new insight into the deleterious effect of amorphous SiNPs on vascular homeostasis.

Potentiation of cisplatin-induced nephrotoxicity by repeated exposure to diesel exhaust particles: An experimental study in rats

Several epidemiological and clinical studies have shown that exposure to particulate air pollution is associated with increases in morbidity and mortality, and this is more evident in patients with renal diseases. However, the basis of the possible exacerbating effect of particulate air pollution on animal model of renal injury has received scant attention. Here, we assessed the effect of repeated exposure to diesel exhaust particles (DEP) on cisplatin (CP)-induced nephrotoxicity in rats. DEP (0.5 m/kg) was intratracheally (i.t.) instilled every second day for eight days (a total of five exposures). CP, 6 mg/kg was given 1 h before the third exposure to DEP. Two days following the last exposure to either DEP or saline (control), various renal endpoints were measured. Water intake, urine volume, and relative kidney weight were significantly increased in CP + DEP versus DEP and CP + saline versus saline. Plasma creatinine increased and creatinine clearance decreased in CP + DEP versus DEP and CP + saline versus saline. Interestingly, blood urea nitrogen, albumin concentrations, and gamma-glutamyl transpeptidase (GGT) activity in urine were significantly increased in DEP + CP compared with either DEP or saline + CP. The combination of DEP and CP enhanced kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, 8-isoprostane and total nitric oxide in the kidney compared with either saline + CP or DEP. Similarly, systolic blood pressure was increased in CP + DEP versus CP + saline or DEP. The renal tubular necrosis observed in kidneys of CP-treated rats was aggravated by the combination of CP + DEP. We conclude that repeated exposure to DEP potentiated CP-induced nephrotoxicity. Our data provide experimental evidence that patients with kidney injury could be at higher risk than the general population.

Recent developments in delivery, bioavailability, absorption and metabolism of curcumin: the golden pigment from golden spice

Curcumin (diferuloylmethane) is a yellow pigment present in the spice turmeric (Curcuma longa) that has been associated with antioxidant, anti-inflammatory, anticancer, antiviral, and antibacterial activities as indicated by over 6,000 citations. In addition, over one hundred clinical studies have been carried out with curcumin. One of the major problems with curcumin is perceived to be the bioavailability. How curcumin should be delivered in vivo, how bioavailable is it, how well curcumin is absorbed and how it is metabolized, is the focus of this review. Various formulations of curcumin that are currently available are also discussed.

Acute effects of diesel exhaust particles and cisplatin on oxidative stress in cultured human kidney (HEK 293) cells, and the influence of curcumin thereon

Particulate air pollution with particle diameters less than 2.5μm contribute to respiratory and extra-respiratory morbidity and mortality. We have recently reported the first in vivo experimental evidence that Diesel exhaust particles (DEP) in the lung aggravated the renal, pulmonary, and systemic effects of cisplatin (CP)-induced acute renal failure in rats. This in vitro study sought to determine whether and to what extent does DEP exposure exacerbate the effects of CP-induced oxidative stress in human embryonic kidney (HEK-293) cells, and to examine if these effects could be mitigated/prevented with curcumin (the yellow pigment isolated from turmeric). Cells viability, cysteine uptake and oxidative stress indices [glutathione (GSH), total antioxidant capacity (TAC), and the activities of antioxidant enzymes (catalase; glutathione peroxidase; superoxide dismutase)] were evaluated in all study groups. DEP aggravated the CP- induced HEK-293 cells toxicity, as evidenced by decreasing cell viability and by inducing oxidative stress (GSH depletion, TAC impairment, and antioxidant enzymes inhibition). DEP, but not CP, significantly reduced cysteine uptake. Curcumin prevented the observed DEP and CP-induced cellular insults. These findings suggest that DEP augmented the CP-induced toxicity in HEK-293 cells. Curcumin exhibited a strong potential for protection against DEP and CP-induced cytotoxicity.

Nose-only water-pipe smoking effects on airway resistance, inflammation, and oxidative stress in mice

Water-pipe smoking (WPS) is a common practice in the Middle East and is now gaining popularity in Europe and the United States. However, there is a limited number of studies on the respiratory effects of WPS. More specifically, the underlying pulmonary pathophysiological mechanisms related to WPS exposure are not understood. Presently, we assessed the respiratory effects of nose-only exposure to mainstream WPS generated by commercially available honey flavored "moasel" tobacco. The duration of the session was 30 min/day and 5 days/wk for 1 mo. Control mice were exposed to air only. Here, we measured in BALB/c mice the airway resistance using forced-oscillation technique. Lung inflammation was assessed histopathologically and by biochemical analysis of bronchoalveolar lavage (BAL) fluid, and oxidative stress was evaluated biochemically by measuring lipid peroxidation, reduced glutathione and several antioxidant enzymes. Pulmonary inflammation assessment showed an increase in neutrophil and lymphocyte numbers. Likewise, airway resistance was significantly increased in the WPS group compared with controls. Tumor necrosis factor α and interleukin 6 concentrations were significantly increased in BAL fluid. Lipid peroxidation in lung tissue was significantly increased whereas the level and activity of antioxidants including reduced glutathione, glutathione S transferase, and superoxide dismutase were all significantly decreased following WPS exposure, indicating the occurrence of oxidative stress. Moreover, carboxyhemoglobin levels were significantly increased in the WPS group. We conclude that 1-mo nose-only exposure to WPS significantly increased airway resistance, inflammation, and oxidative stress. Our results provide a mechanistic explanation for the limited clinical studies that reported the detrimental respiratory effects of WPS.

Recent advances in particulate matter and nanoparticle toxicology: a review of the in vivo and in vitro studies

Epidemiological and clinical studies have linked exposure to particulate matter (PM) to adverse health effects, which may be registered as increased mortality and morbidity from various cardiopulmonary diseases. Despite the evidence relating PM to health effects, the physiological, cellular, and molecular mechanisms causing such effects are still not fully characterized. Two main approaches are used to elucidate the mechanisms of toxicity. One is the use of in vivo experimental models, where various effects of PM on respiratory, cardiovascular, and nervous systems can be evaluated. To more closely examine the molecular and cellular mechanisms behind the different physiological effects, the use of various in vitro models has proven to be valuable. In the present review, we discuss the current advances on the toxicology of particulate matter and nanoparticles based on these techniques.

Impact of experimental type 1 diabetes mellitus on systemic and coagulation vulnerability in mice acutely exposed to diesel exhaust particles

Background

Epidemiological evidence indicates that diabetic patients have increased susceptibility to adverse cardiovascular outcomes related to acute increases in exposures to particulate air pollution. However, mechanisms underlying these effects remain unclear.

Methods

To evaluate the possible mechanisms underlying these actions, we assessed the systemic effects of diesel exhaust particles (DEP) in control mice, and mice with streptozotocin–induced type 1 diabetes. Four weeks following induction of diabetes, the animals were intratracheally instilled (i.t.) with DEP (0.4 mg/kg) or saline, and several cardiovascular endpoints were measured 24 h thereafter.

Results

DEP caused leukocytosis and a significant increase in plasma C-reactive protein and 8-isoprostane concentrations in diabetic mice compared to diabetic mice exposed to saline or non-diabetic mice exposed to DEP. The arterial PO₂ as well as the number of platelets and the thrombotic occlusion time in pial arterioles assessed in vivo were significantly decreased following the i.t. instillation of DEP in diabetic mice compared to diabetic mice exposed to saline or non-diabetic mice exposed to DEP. Both alanine aminotransferase and aspartate transaminase activities, as well as the plasma concentrations of plasminogen activator inhibitor and von Willebrand factor were significantly increased in DEP-exposed diabetic mice compared to diabetic mice exposed to saline or DEP-exposed non-diabetic mice. The in vitro addition of DEP (0.25-1 μg/ml) to untreated mouse blood significantly and dose-dependently induced in vitro platelet aggregation, and these effects were exacerbated in blood of diabetic mice.

Conclusion

This study has shown that systemic and coagulation events are aggravated by type 1 diabetes in mice, acutely exposed to DEP and has described the possible mechanisms for these actions that may also be relevant to the exacerbation of cardiovascular morbidity accompanying particulate air pollution in diabetic patients.

Curcumin attenuates endothelial cell oxidative stress injury through Notch signaling inhibition

Previous studies have demonstrated that Notch signaling pathway plays a regulatory role in cellular oxidative stress injury (OSI). In this study, our aim was to explore the role of the Notch signaling pathway in hydrogen peroxide (H(2)O(2))-induced OSI and the protective effect of curcumin during (H(2)O(2))-induced injury in human umbilical vein endothelial cells (HUVECs). DAPT, a specific inhibitor of the Notch signaling pathway, and Notch1 siRNA were used to study Notch activity. Further, HUVECs were exposed to H(2)O(2) in the absence or presence of curcumin. DAPT and Notch1 siRNA significantly inhibited OSI and the expression of Notch1 and Hes1. Curcumin conferred a protective effect on the HUVECs against H(2)O(2), which was evidenced by improved cell viability, adhesive ability and migratory ability and a decreased apoptotic index, decreased production of reactive oxygen species (ROS) and a reduction in several biochemical parameters. Immunofluorescence and Western blotting analyses demonstrated that H(2)O(2) treatment upregulated the expression of Notch1, Hes1, Caspase3, Bax and cytochrome c downregulated the expression of Bcl2, and treatment with curcumin reversed these effects. We demonstrated for the first time that the inhibition of Notch signaling pathway imparts a protective effect against endothelial OSI. The protective effects of curcumin against OSI are at least in part dependent on Notch1 inhibition.