Exposure to nanoparticles: in vitro and in vivo studies to evaluate cardiovascular risk factors in normal and pathological cardiac tissues

Diesel Exhaust Particulates Exacerbate Asthma-Like Inflammation by Increasing CXC Chemokines

BackgroundMechanisms of cardiovascular injuries from exposure to gas and particulate air pollutants are unknown.ObjectiveWe sought to determine whether episodic exposure of rats to ozone or diesel exhaust particles (DEP) causes differential cardiovascular impairments that are exacerbated by ozone plus DEP.Methods and resultsMale Wistar Kyoto rats (10–12 weeks of age) were exposed to air, ozone (0.4 ppm), DEP (2.1 mg/m3), or ozone (0.38 ppm) + DEP (2.2 mg/m3) for 5 hr/day, 1 day/week for 16 weeks, or to air, ozone (0.51 or 1.0 ppm), or DEP (1.9 mg/m3) for 5 hr/day for 2 days. At the end of each exposure period, we examined pulmonary and cardiovascular biomarkers of injury. In the 16-week study, we observed mild pulmonary pathology in the ozone, DEP, and ozone + DEP exposure groups, a slight decrease in circulating lymphocytes in the ozone and DEP groups, and decreased platelets in the DEP group. After 16 weeks of exposure, mRNA biomarkers of oxidative stress (hemeoxygenase-1), thrombosis (tissue factor, plasminogen activator inhibitor-1, tissue plasminogen activator, and von Willebrand factor), vasoconstriction (endothelin-1, endothelin receptors A and B, endothelial NO synthase) and proteolysis [matrix metalloprotease (MMP)-2, MMP-3, and tissue inhibitor of matrix metalloprotease-2] were increased by DEP and/or ozone in the aorta, but not in the heart. Aortic LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) mRNA and protein increased after ozone exposure, and LOX-1 protein increased after exposure to ozone + DEP. RAGE (receptor for advanced glycation end products) mRNA increased in the ozone + DEP group. Exposure to ozone or DEP depleted cardiac mitochondrial phospholipid fatty acids (DEP > ozone). The combined effect of ozone and DEP exposure was less pronounced than exposure to either pollutant alone. Exposure to ozone or DEP for 2 days (acute) caused mild changes in the aorta.ConclusionsIn animals exposed to ozone or DEP alone for 16 weeks, we observed elevated biomarkers of vascular impairments in the aorta, with the loss of phospholipid fatty acids in myocardial mitochondria. We conclude that there is a possible role of oxidized lipids and protein through LOX-1 and/or RAGE signaling.

Small animal models have been widely used in cardiovascular research when studying the development and treatment of different diseases. This kind of research has promoted the development of noninvasive techniques to assess cardiac tissue and blood vessels of small animals. Recently, we have developed a high-frequency ultrasound imaging system for small animals, in particular, mouse and rat models. In this work, we aim to elucidate the usefulness of using spectral analysis of the received radiofrequency (RF) ultrasound signals to extract quantitative parameters to assess mechanical properties of cardiac and vascular tissues. A custom system that employs high-frequency single-element ultrasound transducers (30–120 MHz) is used for scanning. Various signal and image processing techniques are applied on the received ultrasound signals to reconstruct high resolution B-mode and spectral images. In vitro imaging of isolated heart and vessels of APOE-KO “knock-out” mouse model with atherosclerosis was performed. Power spectral densities (PSD) of RF signals were evaluated within various regions of interests (ROI) including degassed water, normal cardiac tissue, and cardiac tissue with atheroma. Various parameters were extracted from the power spectrum such as the maximum power (Pmax), the frequency at maximum power (Fpeak), and the variance of power spectrum (Pvar). Results of the preliminary spectral analysis indicated larger values for the Pmax, Fpeak, and Pvar parameters for ROI contains atheroma than other regions. For example using the envelop data, the normalized maximum power (Pmax) value for cardiac tissue with atheroma was 0.0 ± 0.789 (dB), whereas for normal tissues it was about −13.71± 0.267 (dB). These results suggest the use spectral images as a quantitative method when assessing mouse hearts and blood vessels noninvasively.

The effects of diesel exhaust particles (DEP) on pulmonary functions and consequent diseases are well known, but there have been few reports concerning involvement of the cardiovascular system. In order to assess a direct action of DEP on cardiac tissue, the effects on blood pressure of intravenous administration of 12 or 120 mg/kg DEP to anesthetized rats were studied for a 15-min period. DEP (120 mg/kg) significantly lowered blood pressure for 25 s with no signs of arrhythmia or mortality, a phenomenon seen in guinea pigs. After 25 s blood pressure gradually returned to control levels and was maintained for 15 min. The 12-mg/kg DEP concentration did not markedly affect rat blood pressure. Pretreatment with atropine (24 mg/kg) blocked the DEP-induced fall in blood pressure, while pretreatment with propranolol (48 mg/kg) proved ineffective against DEP, suggesting involvement of the parasympathetic system. Data show that the rat is less sensitive to DEP-induced effects on blood pressure and may be a poor model to reflect cardiovascular changes.

BackgroundIn light of recent developments in nanotechnologies, interest is growing to better comprehend the interaction of nanoparticles with body tissues, in particular within the cardiovascular system. Attention has recently focused on the link between environmental pollution and cardiovascular diseases. Nanoparticles <50 nm in size are known to pass the alveolar–pulmonary barrier, enter into bloodstream and induce inflammation, but the direct pathogenic mechanisms still need to be evaluated. We thus focused our attention on titanium dioxide (TiO2) nanoparticles, the most diffuse nanomaterial in polluted environments and one generally considered inert for the human body.MethodsWe conducted functional studies on isolated adult rat cardiomyocytes exposed acutely in vitro to TiO2 and on healthy rats administered a single dose of 2 mg/Kg TiO2 NPs via the trachea. Transmission electron microscopy was used to verify the actual presence of TiO2 nanoparticles within cardiac tissue, toxicological assays were used to assess lipid peroxidation and DNA tissue damage, and an in silico method was used to model the effect on action potential.ResultsVentricular myocytes exposed in vitro to TiO2 had significantly reduced action potential duration, impairment of sarcomere shortening and decreased stability of resting membrane potential. In vivo, a single intra-tracheal administration of saline solution containing TiO2 nanoparticles increased cardiac conduction velocity and tissue excitability, resulting in an enhanced propensity for inducible arrhythmias. Computational modeling of ventricular action potential indicated that a membrane leakage could account for the nanoparticle-induced effects measured on real cardiomyocytes.ConclusionsAcute exposure to TiO2 nanoparticles acutely alters cardiac excitability and increases the likelihood of arrhythmic events.Electronic supplementary materialThe online version of this article (doi:10.1186/s12989-014-0063-3) contains supplementary material, which is available to authorized users.

Inhalation of diesel exhaust particles (DEP) is implicated in cardiovascular disease. DEP gain access to the vasculature, but how is unknown. To examine this, human umbilical vein endothelial cells in monolayer culture and in in vitro‐assembled capillary tubes, were treated with DEP sonicated to an average size of 2.5 um (PM2.5). DEP were diluted in medium to 1, 10, and 100 ug/ml for application to cells. Cell junction integrity was evaluated using confocal microscopy, and cytotoxicity was assayed to determine cell viability at 4, 24, and 48 hr after adding DEP. Z‐stack confocal images of capillary tubes incubated for 24 hr with different concentrations of DEP demonstrated that particles adhere to the surface and also gain access to the lumen. Increasing DEP concentration increases redistribution of the junctional protein, VE‐cadherin, from the cell‐cell borders to an intracellular localization. At 100 ug/ml DEP, junctions were totally disrupted. DEP at 1 ug/ml was not toxic to monolayer cultures: these cells doubled every 24 hr as did untreated controls. Cells treated with 10 ug/ml DEP doubled in 48 hr. TUNEL assays demonstrate 10 ug/ml caused some cell death. 100 ug/ml DEP was very toxic, killing 65% of cells by 24 hr. This data suggest DEP may gain access to the vasculature by causing alterations in the endothelial cell‐cell junctions and/or by killing vessel endothelia.

Respiratory exposure to Particulate Matter (PM), including Diesel exhaust particulate (DEP), causes oxidative stress-induced lung inflammation. Especially, fine particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) is a serious air pollutant associated with various health problems. DEP and PM2.5 pollutants in the air are enter into pulmonary and even bloodstream, and can be causes of inflammatory disorders that are related with respiratory response. The present study aimed to examine the inhibitory effect of Securiniga suffruticosa (S. suffruiticosa) on DEP-induced lung and cardiovascular diseases. The mice groups are follows; sham group: C57BL6 male mice, DEP group: C57BL6 male mice inhaled DEP, S. suffruiticosa Low group: DEP + 100 mg/kg/day S. suffruiticosa, and S. suffruiticosa High group: DEP + 300 mg/kg/day S. suffruiticosa. Mice inhaled DEP by using nebulizer chamber and were sacrificed 48 hours after final exposure of DEP. Treatment with S. suffruiticosa reduced the expression of inducible CXCL1 and CXCL2 in bronchoalveolar lavage fluid and Muc5ac, ICAM-1, TNF-α, IL-6 mRNA in lung were also attenuated by S. suffruiticosa. In thoracic aorta, DEP increased CAMs, TNF-α and inflammasome markers such as NLRP3, Caspase-1, and ASC. However, S. suffruiticosa suppressed these levels. In HUVECs, S. suffruiticosa inhibited PM2.5 induced production of intracellular reactive oxygen species (ROS); and inhibited the translocation of NF-κB p65 to the nucleus in HUVECs (human umbilical vein endothelial cells). Taken together, this study proved that exposure to PM2.5 induced both lung and vascular inflammation, however, S. suffruiticosa attenuated this injury via the downregulation of the NLRP3 signaling pathway. These findings suggest that S. suffruiticosa may have potential therapeutic benefit against air pollution-mediated lung and cardiovascular diseases. This study was supported by a National Research Foundation of Korea (NRF) Grant funded by the Korean government (MSIP) (2017R1A5A2015805) (2021R1I1A1A01056937). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Anxiety and Depression Following Diesel Exhaust Nano-Particles Exposure in Male and Female Mice

Heart failure (HF) constitutes a major public health problem worldwide. Operationally it is defined as a clinical syndrome characterized by the marked and progressive inability of the ventricles to fill and generate adequate cardiac output to meet the demands of cellular metabolism. HF may have significant variability in its etiology and it is the final common pathway of various cardiac pathologies. Susceptibility to cardiac arrhythmias is increased in account of failing phenotype. Much attention has been paid to the understanding of the arrhythmogenic mechanisms induced by the structural, electrical, and metabolic remodeling of the failing heart. Due to the complexity of the electrophysiological changes that may occur during heart failure, the scientific literature is complex and sometimes equivocal. Nevertheless, a number of common features of failing hearts have been documented. At the cellular level, prolongation of the action potential (AP) involving ion channel remodeling and alterations in calcium handling have been established as the hallmark characteristics of myocytes isolated from failing hearts. At the tissue level, intercellular uncoupling and fibrosis are identified as major arrhythmogenic factors. The rapid development of biophysically detailed computer models of single myocytes and cardiac tissues have contributed greatly to our understanding of processes underlying excitation and repolarization in the heart. In that sense, a model of the failing human ventricular myocyte was proposed, based on modifications to the Grandi et al. and O?Hara et al. human ventricular AP models, to study the mechanisms of HF-associated arrhythmias. Multiscale simulations to characterize the arrhythmia phenotype associated to this pathology were performed. At the single cell level, we specifically looked at the role of the late sodium current (INaL), including the formulation of this current. Experimental data from several sources were used to validate the model. Due to variability in literature a sensitivity analysis was performed to assess the influence of main ionic currents and parameters upon most related biomarkers. The role of electrophysiological and structural heart failure remodeling in setting the stage for malignant arrhythmias was assessed through several configurations of transmural ventricular strands and the presence of controversial M cells was evaluated as well. Furthermore, the effect of fibrotic content and intercellular uncoupling on vulnerability to reentry was tested in transmural heterogeneous failing tissues. The proposed model for the human INaL and the electrophysiological remodeling of myocytes from failing hearts accurately reproduce experimental observations. An enhanced INaL appears to be an important contributor to the electrophysiological phenotype and to the dysregulation of calcium homeostasis of failing myocytes. Our strand simulation results illustrate how the presence of M cells and heterogeneous electrophysiological remodeling in the human failing ventricle modulate the dispersion of action potential duration (APD) and repolarization time (RT). Conduction velocity (CV) and the safety factor for conduction (SF) were also reduced by the progressive structural remodeling during heart failure. In our transmural ventricular tissue simulations, no reentry was observed in normal conditions or in the presence of HF ionic remodeling. However, defined amount of fibrosis and/or cellular uncoupling were sufficient to elicit reentrant activity. Under conditions where reentry was generated, HF electrophysiological remodeling did not alter the width of the vulnerable window (VW). However, intermediate fibrosis and cellular uncoupling significantly widened the VW. In addition, biphasic behavior was observed, as very high fibrotic content or very low tissue conductivity hampered the development of reentry. Detailed phase analysis of reentry dynamics revealed an increase of phase singularities with progressive fibrotic components. In conclusion, enhanced fibrosis in failing hearts, as well as reduced intercellular coupling, combine to increase electrophysiological gradients and reduce electrical propagation. In that sense, structural remodeling is a key factor in the genesis of vulnerability to reentry, mainly at intermediates levels of fibrosis and intercellular uncoupling. Electrophysiological remodeling promotes arrhythmogenesis and could be altered by the stage of HF.

Combustion-derived nanoparticles (CDNP) are exemplified by diesel exhaust particles (DEP) and DEP have been studied extensively as to their mechanism of adverse action. These adverse actions include effects on the lungs in exacerbating existing airways disease and adverse effects in cardiovascular disease. Toxicologists seek to link particle structure to toxicity and studies have shown that DEP and other CDNP have components capable of causing oxidative stress in the lungs following deposition, i.e., the carbon core, metals and a range of organics. Oxidative stress can be measured in cells in culture and in tissues from animals and humans exposed to DEP and other CDNP. Oxidative stress is linked to inflammation by well-recognised signalling pathways and pro-inflammatory effects are induced in cells, animals and humans exposed to CDNP. Inflammation is an underlying mechanism in the major pulmonary effects of DEP and particulates in human populations. Oxidative stress and inflammation are known to be involved in atherosclerosis development and in their destabilisation and rupture, leading to heart attacks and strokes. Wood-smoke appears to be less potent than DEP in causing pulmonary oxidative stress and inflammation and impacts little on the cardiovascular system. Difference in composition between DEP and wood-smoke can reasonably explain the differences in potency between DEP and wood-smoke, and this suggests that CDNP from various sources will have different potency depending on their composition.

Objective: Exposure to diesel exhaust particles (DEP) is strongly linked to the development and exacerbation of cardiovascular diseases. Statins are effective drugs in the prevention and treatment of cardiovascular disorders. The aim of this study was to investigate the potential protective effect of rosuvastatin on DEP-induced endothelial dysfunction.Methods and results: Spontaneously hypertensive rats (SHR) were treated for 5 weeks with rosuvastatin and exposed, intratracheally, for the last 4 weeks, to either DEP suspensions or saline vehicle. Rings of thoracic aortas were used to assess superoxide anion production through the lucigenin-enhanced chemiluminescence technique. Real-time quantitative polymerase chain reaction analysis was performed on aortic segments to assess eNOS, iNOS, p22phox, gp91phox, Rac-1 and TNF-α mRNA expression. Human umbilical vein endothelial cells (HUVECs) were also used for the measurement of oxidative stress after DEP and/or rosuvastatin incubation. In thoracic aortic rings isolated from SHR, superoxide anion formation was increased after DEP exposure. This oxidative stress was markedly decreased in the rosuvastatin-treated group. DEP exposure also induced a downregulation of eNOS mRNA expression and a slight increase in gp91phox mRNA expression, which were reversed in the rosuvastatin group. In HUVECs, similar results were observed: DEP generated an accumulation of superoxide anion, which was significantly attenuated by rosuvastatin.Conclusions: Our results suggest that rosuvastatin interacts with the eNOS and NADPH oxidase pathways in hypertensive rats and therefore might counteract the oxidative stress induced by DEP. This effect was also observed in vitro in human endothelial cells (HUVECs).

DEP induction of ROS in capillary-like endothelial tubes leads to VEGF-A expression

Altered cardiac bradykinin metabolism in experimental diabetes caused by the variations of angiotensin-converting enzyme and other peptidases

Defibrillation threshold computed from normal and supernormal excitable cardiac tissue

In support of the spiral wave theory of reentry, simulation studies and animal models have been utilized to show various patterns of spiral wave tip motion such as meandering and drifting. However, the demonstration of these or any other patterns in cardiac tissues have been limited. Whether such patterns of spiral tip motion are commonly observed in fibrillating cardiac tissues is unknown, and whether such patterns form the basis of ventricular tachycardia or fibrillation remain debatable. Using a computerized dynamic activation display, 108 episodes of atrial and ventricular tachycardia and fibrillation in isolated and intact canine cardiac tissues, as well as in vitro swine and myopathic human cardiac tissues, were analyzed for patterns of nonstationary, spiral wave tip motion. Among them, 46 episodes were from normal animal myocardium without pharmacological perturbations, 50 samples were from normal animal myocardium, either treated with drugs or had chemical ablation of the subendocardium, and 12 samples were from diseased human hearts. Among the total episodes, 11 of them had obvious nonstationary spiral tip motion with a life span of >2 cycles and with consecutive reentrant paths distinct from each other. Four patterns were observed: (1) meandering with an inward petal flower in 2; (2) meandering with outward petals in 5; (3) irregularly concentric in 3 (core moving about a common center); and (4) drift in 1 (linear core movement). The life span of a single nonstationary spiral wave lasted no more than 7 complete cycles with a mean of 4.6+/-4.3, and a median of 4.5 cycles in our samples. Conclusion: (1) Patently evident nonstationary spiral waves with long life spans were uncommon in our sample of mostly normal cardiac tissues, thus making a single meandering spiral wave an unlikely major mechanism of fibrillation in normal ventricular myocardium. (2) A tendency toward four patterns of nonstationary spiral tip motion was observed. (c) 1998 American Institute of Physics.