Oleic acid and derivatives affect human endothelial cell mitochondrial function and vasoactive mediator production.

BACKGROUND: Inhalation of common air pollutants such as diesel and biodiesel combustion products can induce vascular changes in humans which may contribute to increased mortality and morbidity associated with fine particulate matter exposures. Diesel, biodiesel, and other combustion byproducts contain fatty acid components capable of entering the body through particulate matter inhalation. Fatty acids can also be endogenously released into circulation following a systemic stress response to some inhaled pollutants such as ozone. When in the circulation, bioactive fatty acids may interact with cells lining the blood vessels, potentially inducing endothelial dysfunction. To examine whether fatty acids could potentially be involved in human vascular responses to air pollutants, we determined the effects of fatty acids and derivatives on important vascular cell functions. METHODS: Human umbilical vein endothelial cells (HUVEC) were exposed in vitro to oleic acid (OA) or OA metabolites for 4-48 h. Cytotoxicity, vasodilator production (by ELISA measurement), mitochondrial function (using Sea Horse assays), and iron metabolism (inferred by ICP-OES measurements) were examined, with standard statistical testing (ANOVA, t-tests) employed. RESULTS: Dose-dependent cytotoxicity was noted at 24 h, with 12-hydroxy OA more potent than OA. Mitochondrial stress testing showed that 12-hydroxy OA and OA induce mitochondrial dysfunction. Analysis of soluble mediator release from HUVEC showed a dose-dependent increase in prostaglandin F2α, a lipid involved in control of vascular tone, at 24 h (85% above controls) after OA-BSA exposure. RT-PCR analysis revealed OA did not induce changes in gene expression at noncytotoxic concentrations in exposed HUVEC, but 12-OH OA did alter ICAM and COX2 gene expression. CONCLUSIONS: Together, these data demonstrate that FA may be capable of inducing cytotoxic effects and altering expression of mediators of vascular function following inhalation exposure, and may be implicated in air pollutant-induced deaths and hospitalizations. (267 of max 350 words).

12-hydroxy oleic acid impairs endothelium-dependent vasorelaxation.

Diesel and biodiesel emissions exposures reduce vascular responsiveness in vivo, but the components of PM responsible for this effect are poorly understood. Fatty acids (FAs) represent a significant fraction of the compounds that make up organic combustion by-products, and may be involved in vascular responses following inhalation. It was hypothesized that vascular tissue exposed to a model FA might impair responses to vasoactive agonists ex vivo. Rat aortic rings were exposed to oleic acid or 12-hydroxy oleic acid and responses determined by myography. 12-Hydroxy oleic acid was found to significantly reduce endothelium-dependent vasodilation at sub-cytotoxic concentrations. This approach demonstrates the potential for FAs, especially oxidized forms, to play a role in the vascular responses observed following air pollution exposure.

Age-related differences in pulmonary effects of acute and subchronic episodic ozone exposures in Brown Norway rats.

Ozone (O3) is known to induce adverse pulmonary and systemic health effects. Importantly, children and older persons are considered at-risk populations for O3-induced dysfunction, yet the mechanisms accounting for the age-related pulmonary responses to O3 are uncertain. In this study, we examined age-related susceptibility to O3 using 1 mo (adolescent), 4 mo (young adult), 12 mo (adult) and 24 mo (senescent) male Brown Norway rats exposed to filtered air or O3 (0.25 and 1.00 ppm), 6 h/day, two days/week for 1 week (acute) or 13 weeks (subchronic). Ventilatory function, assessed by whole-body plethysmography, and bronchoalveolar lavage fluid (BALF) biomarkers of injury and inflammation were used to examine O3-induced pulmonary effects. Relaxation time declined in all ages following the weekly exposures; however, this effect persisted only in the 24 mo rats following a five days recovery, demonstrating an inability to induce adaptation commonly seen with repeated O3 exposures. PenH was increased in all groups with an augmented response in the 4 mo rats following the subchronic O3 exposures. O3 led to increased breathing frequency and minute volume in the 1 and 4 mo animals. Markers of pulmonary permeability were increased in all age groups. Elevations in BALF γ-glutamyl transferase activity and lung inflammation following an acute O3 exposure were noted in only the 1 and 4 mo rats, which likely received an increased effective O3 dose. These data demonstrate that adolescent and young adult animals are more susceptible to changes in ventilation and pulmonary injury/inflammation caused by acute and episodic O3 exposure.

Comparative cardiopulmonary toxicity of exhausts from soy-based biofuels and diesel in healthy and hypertensive rats.

Increased use of renewable energy sources raise concerns about health effects of new emissions. We analyzed relative cardiopulmonary health effects of exhausts from (1) 100% soy biofuel (B100), (2) 20% soy biofuel + 80% low sulfur petroleum diesel (B20), and (3) 100% petroleum diesel (B0) in rats. Normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats were exposed to these three exhausts at 0, 50, 150 and 500 µg/m(3), 4 h/day for 2 days or 4 weeks (5 days/week). In addition, WKY rats were exposed for 1 day and responses were analyzed 0 h, 1 day or 4 days later for time-course assessment. Hematological parameters, in vitro platelet aggregation, bronchoalveolar lavage fluid (BALF) markers of pulmonary injury and inflammation, ex vivo aortic ring constriction, heart and aorta mRNA markers of vasoconstriction, thrombosis and atherogenesis were analyzed. The presence of pigmented macrophages in the lung alveoli was clearly evident with all three exhausts without apparent pathology. Overall, exposure to all three exhausts produced only modest effects in most endpoints analyzed in both strains. BALF γ-glutamyl transferase (GGT) activity was the most consistent marker and was increased in both strains, primarily with B0 (B0 > B100 > B20). This increase was associated with only modest increases in BALF neutrophils. Small and very acute increases occurred in aorta mRNA markers of vasoconstriction and thrombosis with B100 but not B0 in WKY rats. Our comparative evaluations show modest cardiovascular and pulmonary effects at low concentrations of all exhausts: B0 causing more pulmonary injury and B100 more acute vascular effects. BALF GGT activity could serve as a sensitive biomarker of inhaled pollutants.

Inhaled ozone (O3)-induces changes in serum metabolomic and liver transcriptomic profiles in rats.

Air pollution has been linked to increased incidence of diabetes. Recently, we showed that ozone (O3) induces glucose intolerance, and increases serum leptin and epinephrine in Brown Norway rats. In this study, we hypothesized that O3 exposure will cause systemic changes in metabolic homeostasis and that serum metabolomic and liver transcriptomic profiling will provide mechanistic insights. In the first experiment, male Wistar Kyoto (WKY) rats were exposed to filtered air (FA) or O3 at 0.25, 0.50, or 1.0ppm, 6h/day for two days to establish concentration-related effects on glucose tolerance and lung injury. In a second experiment, rats were exposed to FA or 1.0ppm O3, 6h/day for either one or two consecutive days, and systemic metabolic responses were determined immediately after or 18h post-exposure. O3 increased serum glucose and leptin on day 1. Glucose intolerance persisted through two days of exposure but reversed 18h-post second exposure. O3 increased circulating metabolites of glycolysis, long-chain free fatty acids, branched-chain amino acids and cholesterol, while 1,5-anhydroglucitol, bile acids and metabolites of TCA cycle were decreased, indicating impaired glycemic control, proteolysis and lipolysis. Liver gene expression increased for markers of glycolysis, TCA cycle and gluconeogenesis, and decreased for markers of steroid and fat biosynthesis. Genes involved in apoptosis and mitochondrial function were also impacted by O3. In conclusion, short-term O3 exposure induces global metabolic derangement involving glucose, lipid, and amino acid metabolism, typical of a stress-response. It remains to be examined if these alterations contribute to insulin resistance upon chronic exposure.

Inhaled diesel emissions generated with cerium oxide nanoparticle fuel additive induce adverse pulmonary and systemic effects.

Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe results in greater adverse pulmonary effects compared with DE. Male Sprague Dawley rats were exposed to filtered air, DE, or DECe for 5 h/day for 2 days. N-acetyl glucosaminidase activity was increased in bronchial alveolar lavage fluid (BALF) of rats exposed to DECe but not DE. There were also marginal but insignificant increases in several other lung injury biomarkers in both exposure groups (DECe > DE for all). To further characterize DECe toxicity, rats in a second study were exposed to filtered air or DECe for 5 h/day for 2 days or 4 weeks. Tissue analysis indicated a concentration- and time-dependent accumulation of lung and liver cerium followed by a delayed clearance. The gas-phase and high concentration of DECe increased lung inflammation at the 2-day time point, indicating that gas-phase components, in addition to particles, contribute to pulmonary toxicity. This effect was reduced at 4 weeks except for a sustained increase in BALF γ-glutamyl transferase activity. Histopathology and transmission electron microscopy revealed increased alveolar septa thickness due to edema and increased numbers of pigmented macrophages after DECe exposure. Collectively, these findings indicate that DECe induces more adverse pulmonary effects on a mass basis than DE. In addition, lung accumulation of cerium, systemic translocation to the liver, and delayed clearance are added concerns to existing health effects of DECe.

Diesel exhaust induced pulmonary and cardiovascular impairment: the role of hypertension intervention.

Exposure to diesel exhaust (DE) and associated gases is linked to cardiovascular impairments; however, the susceptibility of hypertensive individuals is poorly understood. The objectives of this study were (1) to determine cardiopulmonary effects of gas-phase versus whole-DE and (2) to examine the contribution of systemic hypertension in pulmonary and cardiovascular effects. Male Wistar Kyoto (WKY) rats were treated with hydralazine to reduce blood pressure (BP) or l-NAME to increase BP. Spontaneously hypertensive (SH) rats were treated with hydralazine to reduce BP. Control and drug-pretreated rats were exposed to air, particle-filtered exhaust (gas), or whole DE (1500µg/m(3)), 4h/day for 2days or 5days/week for 4weeks. Acute and 4-week gas and DE exposures increased neutrophils and γ-glutamyl transferase (γ-GT) activity in lavage fluid of WKY and SH rats. DE (4weeks) caused pulmonary albumin leakage and inflammation in SH rats. Two-day DE increased serum fatty acid binding protein-3 (FABP-3) in WKY. Marked increases occurred in aortic mRNA after 4-week DE in SH (eNOS, TF, tPA, TNF-α, MMP-2, RAGE, and HMGB-1). Hydralazine decreased BP in SH while l-NAME tended to increase BP in WKY; however, neither changed inflammation nor BALF γ-GT. DE-induced and baseline BALF albumin leakage was reduced by hydralazine in SH rats and increased by l-NAME in WKY rats. Hydralazine pretreatment reversed DE-induced TF, tPA, TNF-α, and MMP-2 expression but not eNOS, RAGE, and HMGB-1. ET-1 was decreased by HYD. In conclusion, antihypertensive drug treatment reduces gas and DE-induced pulmonary protein leakage and expression of vascular atherogenic markers.