Acute effects of fine particles on cardiovascular system: Differences between the spontaneously hypertensive rats and wistar kyoto rats

Effects of subcutaneous vs. oral nanoparticle-mediated insulin delivery on hemostasis disorders in type 1 diabetes: A rat model study

Complications associated with Type 1 diabetes (T1D) have complex origins that revolve around chronic hyperglycemia; these complications involve hemostasis disorders, coagulopathies, and vascular damage. Our study aims to develop innovative approaches to minimize these complications and to compare the outcomes of the new approach with those of traditional methods. To achieve our objective, we designed novel nanoparticles comprising covalent organic frameworks (nCOF) loaded with insulin, termed nCOF/Insulin, and compared it to subcutaneous insulin to elucidate the influence of insulin delivery methods on various parameters, including bleeding time, coagulation factors, platelet counts, cortisol plasma levels, lipid profiles, and oxidative stress parameters. Traditional subcutaneous insulin injections exacerbated hemostasis disorder and vascular injuries in streptozotocin (STZ)-induced diabetic rats through increasing plasma triglycerides and lipid peroxidation. Conversely, oral delivery of nCOF/Insulin ameliorated hemostatic disorders and restored the endothelial oxidant/antioxidant balance by reducing lipid peroxidation and enhancing the lipid profile. Our study pioneers the understanding of how STZ-induced diabetes disrupts bleeding time, induces a hypercoagulable state, and causes vascular damage through lipid peroxidation. Additionally, it provides the first evidence for the involvement of subcutaneous insulin treatment in exacerbating vascular and hemostasis disorders in type 1 diabetes (T1D). Introducing an innovative oral insulin delivery via the nCOF approach represents a potential paradigm shift in diabetes management and patient care and promises to improve treatment strategies for type 1 Diabetes.

PM2.5-Associated Hospitalization Risk of Cardiovascular Diseases in Wuhan: Cases Alleviated by Residential Greenness

PM_2.5, a type of particulate matter with an aerodynamic diameter of less than 2.5 μm, is associated with the occurrence of cardiovascular diseases (CVDs), while greenness seems to be associated with better cardiovascular health. We identified 499,336 CVD cases in Wuhan's 74 municipal hospitals between 2017 and 2019. A high-resolution PM_2.5 model and a normalized difference vegetation index (NDVI) map were established to estimate individual exposures. The time-stratified case-crossover design and conditional logistic regression models were applied to explore the associations between PM_2.5 and CVDs under different levels of environmental factors. Greenness could alleviate PM_2.5-induced hospitalization risks of cardiovascular diseases. Compared with patients in the low-greenness group (ER = 0.99%; 95% CI: 0.71%, 1.28%), patients in the high-greenness group (ER = 0.45%; 95% CI: 0.13%, 0.77%) showed a lower increase in total CVD hospitalizations. After dividing the greenness into quartiles and adding long-term PM_2.5 exposure as a control factor, no significant PM_2.5-associated hospitalization risks of CVD were identified in the greenest areas (quartile 4), whether the long-term PM_2.5 exposure level was high or low. Intriguingly, in the least green areas (quartile 1), the PM_2.5-induced excess risk of CVD hospitalization was 0.58% (95% CI: 0.04%, 1.11%) in the long-term high-level PM_2.5 exposure group, and increased to 1.61% (95% CI: 0.95%, 2.27%) in the long-term low-level PM_2.5 exposure group. In the subgroup analysis, males and participants aged 55-64 years showed more significant increases in the PM_2.5-induced risk of contracting CVDs with a reduction in greenness and fine particle exposure conditions. High residential greenness can greatly alleviate the PM_2.5-induced risk of cardiovascular admission. Living in the areas with long-term low-level PM_2.5 may make people more sensitive to short-term increases in PM_2.5, leading to CVD hospitalization.

Combined Effects of Methyldopa and Baicalein or Scutellaria baicalensis Roots Extract on Blood Pressure, Heart Rate, and Expression of Inflammatory and Vascular Disease-Related Factors in Spontaneously Hypertensive Pregnant Rats

The aim of the study was to investigate the effect of baicalein or Scutellaria baicalensis root extract interaction with methyldopa in pregnant spontaneously hypertensive rats (SHR) at the pharmacodynamic, molecular, and biochemical levels. The rats, after confirming pregnancy, received baicalein (200 mg/kg/day, p.o.) and extract (1000 mg/kg/day, p.o.), in combination with methyldopa (400 mg/kg/day; p.o.), for 14 consecutive days, 1 h before blood pressure and heart rate measurements. In the heart and placenta from mothers after giving birth to their offspring, mRNA expression of factors related to inflammatory processes (TNF-α, Il-1β, IL-6) and vascular diseases (TGF-β, HIF-1α, VEGF, PlGF) was measured. Levels of markers of oxidative stress (superoxide dismutase and malondialdehyde) in the placenta and indicators of myocardial damage (troponin cTnC and cTnI, creatine kinase, myoglobin, and lactate dehydrogenase) in the heart were also assessed. Baicalein co-administered with methyldopa was associated with reduced blood pressure, especially during the first three days. The interactions were more pronounced for such factors as TGF-β, HIF-1α, VEGF, and PlGF than TNF-α, Il-1β, and IL-6. Combined application of baicalein and extract with methyldopa may be of value in the development of a new antihypertensive medication intended for patients suffering from preeclampsia or pregnancy-induced hypertension.

The protective effects of selenium supplementation on ambient PM2.5-induced cardiovascular injury in rats

Substantial epidemiological and experimental studies have shown that ambient fine particulate matter (PM_2.5) exposure can lead to myocardial damage in human and animal through the mechanism of inflammation and oxidative stress. The purpose of the current study was to investigate whether selenium yeast (SeY) supplementation could prevent cardiovascular injury caused by PM_2.5 in rats. Fifty-six Sprague-Dawley rats were randomly divided into seven groups: saline control group; solvent control group, low-, middle-, and high-dose Se pretreatment groups, PM_2.5 exposure group, and high-dose Se control group. The rats were pretreated with different concentration of dietary SeY for 28 days, then were exposed to PM₂.₅ by intratracheal instillation every other day, a total of three times. The levels of inflammatory markers (tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), soluble intercellular adhesion molecule-1 (sICAM-1), and oxidative responses-related indicators total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) were measured in blood and myocardium of the left ventricle. The results showed that although PM_2.5 caused a decrease of T-AOC, T-AOD, and GSH-Px and increase of MDA and sICM-1, pretreatment with SeY induced a dose-dependent increase in these anti-oxidative indicators and a decrease in oxidative indicators. In addition, the levels of TNF-α and IL-1β in Se pretreatment groups were significantly lower than that in PM_2.5 exposure group. The results indicated that Se supplementation could effectively prevent cardiovascular inflammation and oxidative stress induced by PM_2.5. The results also indicated that the nutritional supplementation might be an effective way to protecting people's health from air pollution.

Investigation of selenium pretreatment in the attenuation of lung injury in rats induced by fine particulate matters

Selenium (Se) is vital for health because of its antioxidative and anti-inflammation functions. The aim of this study was to determine if dietary selenium could inhibit the rat lung injury induced by ambient fine particulate matter (PM_2.5). Sprague-Dawley rats were randomly allocated in seven groups (n = 8). The rats in PM_2.5 exposure group were intratracheally instilled with 40 mg/kg of body weight (b.w.) of PM_2.5 suspension. The rats in Se prevention groups were pretreated with 17.5, 35, or 70 μg/kg b.w. of Se for 4 weeks, respectively. Then, the rats were exposed to 40 mg/kg b.w. of PM_2.5 in the fifth week. The bronchoalveolar lavage fluid (BALF) was collected to count the neutrophil numbers and to analyze the cytokines (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), soluble intercellular adhesion molecule-1 (sICAM-1)) related to inflammation, the markers related to oxidative stress (total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), and malondialdehyde (MDA)), and the indicators related to cell damage (lactate dehydrogenase (LDH), total protein (TP), alkaline phosphatase (AKP)). The lung lobe that has not undergone bronchoalveolar lavage was processed for light microscopic examination. The results showed that the proportions of neutrophils in the BALF and the pathologic scores of the lung in PM_2.5-exposed groups were higher than that in the control group (P < 0.05). Se pretreatment caused a dose-dependent decrease in TNF-α, IL-1β, sICAM-1, LDH, TP, AKP, and MDA when compared with the PM_2.5-only exposure group. Meanwhile, the dose-dependent increase in T-AOC, T-SOD, and GSH-Px activities were observed in rats pretreated with Se. In conclusion, Se pretreatment may protect rat lungs against inflammation and oxidative stress induced by PM_2.5, which suggests that Se plays an important role as a kind of potential preventative agent to inhibit the PM_2.5-induced lung injury.

Individual PM2.5 exposure is associated with the impairment of cardiac autonomic modulation in general residents

Fine particulate matter (PM2.5) is one of the major pollutants in metropolitan areas. The current study was conducted to observe the effects of PM2.5 on cardiac autonomic modulation. The participants included 619 men and women aged from 35-75 in a residential area in Shanghai, China. All the participants were divided into four categories according to the distance between their apartments and major road. In addition, individual PM2.5 was measured using SIDEPAKTM AM510 (TSI, USA) from 8:00 am to 6:00 pm. At the end of the individual PM2.5 measurement, the systolic pressure, diastolic pressure, heart rate (HR), low-frequency (LF), high-frequency (HF), and LF/HF were determined. The association between individual PM2.5 level and the above health effects was analyzed using generalized linear regression. The results showed that the average concentration of individual PM2.5 was 95.5 and 87.0 μg/m(3) for men and women. Residential distance to major road was negatively correlated with the individual PM2.5. The results indicated that per 1.0 μg/m(3) increase of individual PM2.5 was associated with a 2.3 % increase for systolic pressure, 0.3 % increase for diastolic pressure, 0.4 % decrease for LF, and 0.4 % decrease for HF. Nevertheless, there was no statistical association between individual PM2.5 and heart rate and LF/HF in the total model. In addition, the similar results were found in men and women excluding a significant association between PM2.5 and the heart rate in men. The alterations of cardiac autonomic modulation hinted that PM2.5 exposure might be associated with the potential occurrence of cardiovascular disease, such as arrhythmia and ischemic heart diseases.

Acute Effects of Particulate Air Pollution on the Incidence of Coronary Heart Disease in Shanghai, China

INTRODUCTION

Evidence based on ecological studies in China suggests that short-term exposure to particulate matter (PM) is associated with cardiovascular mortality. However, there is less evidence of PM-related morbidity for coronary heart disease (CHD) in China. This study aims to investigate the relationship between acute PM exposure and CHD incidence in people aged above 40 in Shanghai.

METHODS

Daily CHD events during 2005-2012 were identified from outpatient and emergency department visits. Daily average concentrations for particulate matter with aerodynamic diameter less than 10 microns (PM10) were collected over the 8-year period. Particulate matter with aerodynamic diameter less than 2.5 microns (PM2.5) were measured from 2009 to 2012. Analyses were performed using quasi-poisson regression models adjusting for confounders, including long-term trend, seasonality, day of the week, public holiday and meteorological factors. The effects were also examined by gender and age group (41-65 years, and >65 years).

RESULTS

There were 619928 CHD outpatient and emergency department visits. The average concentrations of PM10 and PM2.5 were 81.7 μg/m3 and 38.6 μg/m3, respectively. Elevated exposure to PM10 and PM2.5 was related with increased risk of CHD outpatients and emergency department visits in a short time course. A 10 μg/m3 increase in the 2-day PM10 and PM2.5 was associated with increase of 0.23% (95% CI: 0.12%, 0.34%) and 0.74% (95% CI: 0.44%, 1.04%) in CHD morbidity, respectively. The associations appeared to be more evident in the male and the elderly.

CONCLUSION

Short-term exposure to high levels of PM10 and PM2.5 was associated with increased risk of CHD outpatient and emergency department visits. Season, gender and age were effect modifiers of their association.

Toxicological effect of TiO2 nanoparticle-induced myocarditis in mice

Currently, impacts of exposure to TiO2 nanoparticles (NPs) on the cardiovascular system are not well understood. The aim of this study was to investigate whether TiO2 NPs induce myocarditis and its underlying molecular mechanism in the cardiac inflammation in mice. Mice were exposed to TiO2 NPs for 6 months; biochemical parameters of serum and expression of Th1-related and Th2-related cytokines in the heart were investigated. The results showed that TiO2 NP exposure resulted in cardiac lesions coupling with pulmonary inflammation; increases of aspartate aminotransferase (AST), creatine kinase (CK), C-reaction protein (CRP), lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBDH), adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) levels; and a reduction of nitric oxide (NOx) level in the serum. These were associated with increases of nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α), interleukin (IL)-4, IL-6, transforming growth factor-β (TGF-β), creatine kinase, CRP, adhesion molecule-1, and monocyte chemoattractant protein-1, interferon-γ (IFN-γ), signal transducers and activators of transcription (STAT)1, STAT3, or STAT6, GATA-binding domain-3, GATA-binding domain-4, endothelin-1 expression levels, and T-box expressed in T cells expression level that is the master regulator of pro-inflammatory cytokines and transcription factors in the heart. These findings imply that TiO2 NP exposure may increase the occurrence and development of cardiovascular diseases.

Silica nanoparticles induce oxidative stress, inflammation, and endothelial dysfunction in vitro via activation of the MAPK/Nrf2 pathway and nuclear factor-κB signaling

Despite the widespread application of silica nanoparticles (SiNPs) in industrial, commercial, and biomedical fields, their response to human cells has not been fully elucidated. Overall, little is known about the toxicological effects of SiNPs on the cardiovascular system. In this study, SiNPs with a 58 nm diameter were used to study their interaction with human umbilical vein endothelial cells (HUVECs). Dose- and time-dependent decrease in cell viability and damage on cell plasma-membrane integrity showed the cytotoxic potential of the SiNPs. SiNPs were found to induce oxidative stress, as evidenced by the significant elevation of reactive oxygen species generation and malondialdehyde production and downregulated activity in glutathione peroxidase. SiNPs also stimulated release of cytoprotective nitric oxide (NO) and upregulated inducible nitric oxide synthase (NOS) messenger ribonucleic acid, while downregulating endothelial NOS and ET-1 messenger ribonucleic acid, suggesting that SiNPs disturbed the NO/NOS system. SiNP-induced oxidative stress and NO/NOS imbalance resulted in endothelial dysfunction. SiNPs induced inflammation characterized by the upregulation of key inflammatory mediators, including IL-1β, IL-6, IL-8, TNFα, ICAM-1, VCAM-1, and MCP-1. In addition, SiNPs triggered the activation of the Nrf2-mediated antioxidant system, as evidenced by the induction of nuclear factor-κB and MAPK pathway activation. Our findings demonstrated that SiNPs could induce oxidative stress, inflammation, and NO/NOS system imbalance, and eventually lead to endothelial dysfunction via activation of the MAPK/Nrf2 pathway and nuclear factor-κB signaling. This study indicated a potential deleterious effect of SiNPs on the vascular endothelium, which warrants more careful assessment of SiNPs before their application.

Particle-size-dependent cytokine responses and cell damage induced by silica particles and macrophages-derived mediators in endothelial cell

Epidemiological evidence reports silica dust exposure has been associated with increased risk of cardiovascular diseases, but the mechanisms are largely unknown. In this study, endothelial cells were exposed to increasing concentrations of two sizes silica particles and the soluble mediators released by macrophages treated with the same particles for 24 h. Expression and release of cytokines (IL-1β, TNF-α and IL-6) were measured by using ELISA. Cytotoxicity was measured by MTT assay and LDH release. We show that both ways induced increases in cell toxicity and cytokines in a dose-dependent manner. For smaller particles, the soluble mediators are more capable of increasing cytokines compared with the effect of particles directly. For larger particles, evaluating results of these two ways are similar. Either way, smaller particles make the increasing action of cell toxicity and cytokines more remarkable. Our results indicate both silica particle and macrophage-derived mediators can induce endothelial cell injury and inflammation and demonstrate the potential importance of the particle sizes in this effect.

Preexposure to PM2.5 exacerbates acute viral myocarditis associated with Th17 cell

BACKGROUND

It is increasingly recognized that exposure to ambient fine particles (PM(2.5)) is a risk factor for the development of cardiovascular events. This study was to explore the link between PM(2.5) exposure and viral myocarditis in the functional mechanism of Th17 cells.

METHODS

Male BALB/c mice were administered an intratracheal (i.t.) instillation of 10 mg/kg b.w. PM(2.5) particles. Twenty-four hours later, the mice were injected intraperitoneally (i.p.) with 100 μl of coxsackievirus B3 (CVB3) diluted in Eagle's minimal essential medium (EMEM). Seven days after the treatment, pulmonary and cardiac tissues were examined.

RESULTS

The results showed that preexposure to PM(2.5) increased the cardiac and pulmonary injuries and viral replication in the heart of CVB3-infected mice along with an increase in CD4(+) IL-17(+) cells in the spleen and heart. The mRNA expressions of interleukin-17A (IL-17A), perforin, transforming growth factor-β (TGF-β) and RORγt were up-regulated in PM(2.5)-pretreated mice than that in the virus-treated mice. Additionally, compared to virus-treated mice, the cardiac protein expressions of IL-17A and matrix metalloproteinases-2 (MMP-2) were increased, but interferon-γ (IFN-γ) and metalloproteinases-1 (TIMP-1) were decreased in PM(2.5)-pretreated mice. Interestingly, PM(2.5) caused IFN-γ decreased, whereas CVB3 caused a dramatic increase in IFN-γ. Subsequently, preexposure to PM(2.5) induced a slight increase of IFN-γ in the sera of CVB3-infected mice.

CONCLUSIONS

These results demonstrated that PM(2.5) exposure exacerbated virus-induced myocarditis possibly through the increase in Th17-mediated viral replication, perforin response and imbalance of MMP-2/TIMP-1. These findings provided supportive evidence for the epidemiological research that ambient particles could increase the occurrence and development of cardiovascular diseases.

The biological effects of individual-level PM(2.5) exposure on systemic immunity and inflammatory response in traffic policemen

BACKGROUND

Ambient fine-particle particulate matter (PM2.5) exposure is associated with the decline in pulmonary function, prevalence of coronary heart disease and incidence of myocardial infarction. The study is to observe the effects of ambient PM2.5 on the cardiovascular system and to explore the potential inflammatory and immune mechanisms.

METHODS

The subjects included 110 traffic policemen in Shanghai, China, who were aged 25-55 years. Two-times continuous 24 h individual-level PM2.5 measurements were performed in winter and summer, respectively. The inflammatory marker (high-sensitivity C-reactive protein, hs-CRP), immune parameters (IgA, IgG, IgM and IgE) and lymphocyte profiles (CD4 T cells, CD8 T cells, CD4/CD8 T cells) were measured in blood. The associations between individual-level PM2.5 and inflammatory marker and immune parameters were analysed by multiple linear regression.

RESULTS

The average concentration of 24 h personal PM2.5 for participants was 116.98 μg/m(3) and 86.48 μg/m(3) in winter and summer, respectively. In the main analysis, PM2.5 exposure is associated with the increases in hs-CRP of 1.1%, IgG of 6.7%, IgM of 11.2% and IgE of 3.3% in participants, and decreases in IgA of 4.7% and CD8 of 0.7%, whereas we found no statistical association in CD4 T cells and CD4/CD8 T cells. In the adjusted model, the results showed that the increase of PM2.5 was associated with the changes of inflammatory markers and immune markers both in winter and summer.

CONCLUSIONS

Traffic policeman have been a high-risk group suffering inflammatory response or immune injury because of the high exposure to PM2.5. These findings provided new insight into the mechanisms linking ambient PM2.5 and inflammatory and immune response.

Milan PM1 induces adverse effects on mice lungs and cardiovascular system

Recent studies have suggested a link between inhaled particulate matter (PM) exposure and increased mortality and morbidity associated with cardiorespiratory diseases. Since the response to PM1 has not yet been deeply investigated, its impact on mice lungs and cardiovascular system is here examined. A repeated exposure to Milan PM1 was performed on BALB/c mice. The bronchoalveolar lavage fluid (BALf) and the lung parenchyma were screened for markers of inflammation (cell counts, tumor necrosis factor-α (TNF-α); macrophage inflammatory protein-2 (MIP-2); heme oxygenase-1 (HO-1); nuclear factor kappa-light-chain-enhancer of activated B cells p50 subunit (NFκB-p50); inducible nitric oxide synthetase (iNOS); endothelial-selectin (E-selectin)), cytotoxicity (lactate dehydrogenase (LDH); alkaline phosphatase (ALP); heat shock protein 70 (Hsp70); caspase-8-p18), and a putative pro-carcinogenic marker (cytochrome 1B1 (Cyp1B1)). Heart tissue was tested for HO-1, caspase-8-p18, NFκB-p50, iNOS, E-selectin, and myeloperoxidase (MPO); plasma was screened for markers of platelet activation and clot formation (soluble platelet-selectin (sP-selectin); fibrinogen; plasminogen activator inhibitor 1 (PAI-1)). PM1 triggers inflammation and cytotoxicity in lungs. A similar cytotoxic effect was observed on heart tissues, while plasma analyses suggest blood-endothelium interface activation. These data highlight the importance of lung inflammation in mediating adverse cardiovascular events following increase in ambient PM1 levels, providing evidences of a positive correlation between PM1 exposure and cardiovascular morbidity.

Pulmonary exposure to particles from diesel exhaust, urban dust or single-walled carbon nanotubes and oxidatively damaged DNA and vascular function in apoE(-/-) mice

This study compared the oxidative stress level and vasomotor dysfunction after exposure to urban dust, diesel exhaust particles (DEP) or single-walled carbon nanotubes (SWCNT). DEP and SWCNT increased the production of reactive oxygen species (ROS) in cultured endothelial cells and acellullarly, whereas the exposure to urban dust did not generate ROS. The apoE(-/-) mice, which were exposed twice to 0.5 mg/kg of the particles by intratracheal (i.t.) instillation, had unaltered acetylcholine-elicited vasorelaxation in aorta segments. There was unaltered pulmonary expression level of Vcam-1, Icam-1, Hmox-1 and Ogg1. The levels of oxidatively damaged DNA were unchanged in lung tissue. The exposure to SWCNT significantly increased the expression of Ccl-2 in the lung tissue of the mice. The exposure to DEP and SWCNT was associated with elevated ROS production in cultured cells, whereas i.t. instillation of the same particles had no effect on biomarkers of pulmonary oxidative stress and dilatory dysfunction in the aorta.

Manufactured and airborne nanoparticle cardiopulmonary interactions: a review of mechanisms and the possible contribution of mast cells

Human inhalation exposures to manufactured nanoparticles (NP) and airborne ultrafine particles (UFP) continues to increase in both occupational and environmental settings. UFP exposures have been associated with increased cardiovascular mortality and morbidity, while ongoing research supports adverse systemic and cardiovascular health effects after NP exposures. Adverse cardiovascular health effects include alterations in heart rate variability, hypertension, thrombosis, arrhythmias, increased myocardial infarction, and atherosclerosis. Exactly how UFP and NP cause these negative cardiovascular effects is poorly understood, however a variety of mediators and mechanisms have been proposed. UFP and NP, as well as their soluble components, are known to systemically translocate from the lung. Translocated particles could mediate cardiovascular toxicity through direct interactions with the vasculature, blood, and heart. Recent study suggests that sensory nerve stimulation within the lung may also contribute to UFP- and NP-induced acute cardiovascular alterations. Activation of sensory nerves, such as C-fibers, within the lung may result in altered cardiac rhythm and function. Lastly, release of pulmonary-derived mediators into systemic circulation has been proposed to facilitate cardiovascular effects. In general, these proposed pulmonary-derived mediators include proinflammatory cytokines, oxidatively modified macromolecules, vasoactive proteins, and prothrombotic factors. These pulmonary-derived mediators have been postulated to contribute to the subsequent prothrombotic, atherogenic, and inflammatory effects after exposure. This review will evaluate the potential contribution of individual mediators and mechanisms in facilitating cardiopulmonary toxicity following inhalation of UFP and NP. Lastly, we will appraise the literature and propose a hypothesis regarding the possible role of mast cells in contributing to these systemic effects.

Diesel exhaust particulate induces pulmonary and systemic inflammation in rats without impairing endothelial function ex vivo or in vivo

Background

Inhalation of diesel exhaust impairs vascular function in man, by a mechanism that has yet to be fully established. We hypothesised that pulmonary exposure to diesel exhaust particles (DEP) would cause endothelial dysfunction in rats as a consequence of pulmonary and systemic inflammation.

Methods

Wistar rats were exposed to DEP (0.5 mg) or saline vehicle by intratracheal instillation and hind-limb blood flow, blood pressure and heart rate were monitored in situ 6 or 24 h after exposure. Vascular function was tested by administration of the endothelium-dependent vasodilator acetylcholine (ACh) and the endothelium-independent vasodilator sodium nitroprusside (SNP) in vivo and ex vivo in isolated rings of thoracic aorta, femoral and mesenteric artery from DEP exposed rats. Bronchoalveolar lavage fluid (BALF) and blood plasma were collected to assess pulmonary (cell differentials, protein levels & interleukin-6 (IL-6)) and systemic (IL-6), tumour necrosis factor alpha (TNFα) and C-reactive protein (CRP)) inflammation, respectively.

Results

DEP instillation increased cell counts, total protein and IL-6 in BALF 6 h after exposure, while levels of IL-6 and TNFα were only raised in blood 24 h after DEP exposure. DEP had no effect on the increased hind-limb blood flow induced by ACh in vivo at 6 or 24 h. However, responses to SNP were impaired at both time points. In contrast, ex vivo responses to ACh and SNP were unaltered in arteries isolated from rats exposed to DEP.

Conclusions

Exposure of rats to DEP induces both pulmonary and systemic inflammation, but does not modify endothelium-dependent vasodilatation. Other mechanisms in vivo limit dilator responses to SNP and these require further investigation.

Imbalance of Th1 and Th2 cells in cardiac injury induced by ambient fine particles

The study was to explore the potential immunoregulatory mechanisms linking fine particles and cardiac injury. Wistar kyoto (WKY) rats were exposed by intratracheal instillation to fine particles with the doses of 0.0, 1.6, 8.0 and 40.0mg/kg b.w., respectively. The exposure was conducted once a day, for three consecutive days. Twenty-four hours after the last exposure, the rats were sacrificed. Th1- and Th2-related transcription factors and cytokines were assessed in left ventricle of rats. The mRNA expressions of Th1- and Th2-related transcription factors signal transducer and activator of transcriptionl 1 (STAT1), signal transducer and activator of transcriptional 6 (STAT6), GATA-3 and T-bet were assessed in left ventricle of rats using real-time PCR. Meanwhile, the levels of Th1- and Th2-related cytokines IL-4, IL-13 and interferon gamma (IFN-γ) were determined by ELISA kits in cardiac homogenate supernatant of rats. Furthermore, the protein expression of IL-4 and IFN-γ were detected in myocardium by Western blot. The results of cardiac histology demonstrated exacerbated cardiac lesions and histological characterization of inflammation and degeneration in rats after exposure to fine particles. Moreover, fine particles induced significant increase of IL-4 and IL-13 and decrease of IFN-γ in myocardium of rats. The mRNA expression of STAT1, STAT6 and GATA-3 were up-regulated in left ventricle of rats in a dose-dependent manner, whereas T-bet was significantly down-regulated. The variations of these cytokines demonstrated the imbalance of Th1 and Th2 cytokines existed in cardiac injuries induced by fine particle. The imbalance of Th1/Th2 cytokines might be one of the mechanisms of immunotoxicity of cardiovascular system induced by ambient fine particles.

Activation of stress-related signalling pathway in human cells upon SiO2 nanoparticles exposure as an early indicator of cytotoxicity

BACKGROUND

Nanomaterials such as SiO2 nanoparticles (SiO2NP) are finding increasing applications in the biomedical and biotechnological fields such as disease diagnostics, imaging, drug delivery, food, cosmetics and biosensors development. Thus, a mechanistic and systematic evaluation of the potential biological and toxic effects of SiO2NP becomes crucial in order to assess their complete safe applicability limits.

RESULTS

In this study, human monocytic leukemia cell line THP-1 and human alveolar epithelial cell line A549 were exposed to a range of amorphous SiO2NP of various sizes and concentrations (0.01, 0.1 and 0.5 mg/ml). Key biological indicators of cellular functions including cell population density, cellular morphology, membrane permeability, lysosomal mass/pH and activation of transcription factor-2 (ATF-2) were evaluated utilizing quantitative high content screening (HCS) approach and biochemical techniques. Despite the use of extremely high nanoparticle concentrations, our findings showed a low degree of cytotoxicity within the panel of SiO2NP investigated. However, at these concentrations, we observed the onset of stress-related cellular response induced by SiO2NP. Interestingly, cells exposed to alumina-coated SiO2NP showed low level, and in some cases complete absence, of stress response and this was consistent up to the highest dose of 0.5 mg/ml.

CONCLUSIONS

The present study demonstrates and highlights the importance of subtle biological changes downstream of primary membrane and endocytosis-associated phenomena resulting from high dose SiO2NP exposure. Increased activation of transcription factors, such as ATF-2, was quantitatively assessed as a function of i) human cell line specific stress-response, ii) SiO2NP size and iii) concentration. Despite the low level of cytotoxicity detected for the amorphous SiO2NP investigated, these findings prompt an in-depth focus for future SiO2NP-cell/tissue investigations based on the combined analysis of more subtle signalling pathways associated with accumulation mechanisms, which is essential for establishing the bio-safety of existing and new nanomaterials.

Effects of atorvastatin on fine particle-induced inflammatory response, oxidative stress and endothelial function in human umbilical vein endothelial cells

The study is to explore the toxicity of organic extracts and water-soluble fraction of fine particles on human umbilical vein endothelial cells (HUVECs). The exposure doses were 100, 200 and 400 μg/ml, respectively, for two kinds of fractions. Moreover, atorvastatin was used for intervention study. HUVECs were stimulated by 400 μg/ml organic and water soluble extracts, respectively, immediately followed by treatment with atorvastatin in concentrations of 0.1 μmol/L, 1 μmol/L and 10 μmol/L, respectively. Cell viability, malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), reactive oxygen species (ROS) and the expression of interleukin-6 beta (IL-6), tumor necrosis factor-α (TNF-α), endothelin-1 and P-selectin were determined in cells. The results showed that MDA and ROS increased in HUVECs after exposed to organic extracts and water-soluble fraction, whereas cell viability, NO and SOD decreased. The mRNA expression of IL-6, TNF-α, endothelin-1 (ET-1) and P-selectin increased after exposed to different fractions. Meanwhile, at the same exposure dose, water-soluble fraction caused more significant increase of MDA, IL-6, TNF-α and P-selectin and decrease of cell viability and NO when compared to organic extracts. Compared to no atorvastatin group, the levels of MDA, ROS and the expression of IL-6, TNF-α, ET-1 and P-selectin decreased in HUVECs in adding atorvastatin group, but cell viability, NO and SOD increased, which indicated that atorvastatin attenuated fine particle-induced inflammatory response, oxidative stress and endothelial damage. The results hinted that the inflammatory response, oxidative stress and endothelial dysfunction might be the mechanisms of cardiovascular injury induced by different fractions of ambient fine particles.

Mast cells contribute to altered vascular reactivity and ischemia-reperfusion injury following cerium oxide nanoparticle instillation

Cerium oxide (CeO₂) represents an important nanomaterial with wide ranging applications. However, little is known regarding how CeO₂ exposure may influence pulmonary or systemic inflammation. Furthermore, how mast cells would influence inflammatory responses to a nanoparticle exposure is unknown. We thus compared pulmonary and cardiovascular responses between C57BL/6 and B6.Cg-Kit(W-sh) mast cell deficient mice following CeO₂ nanoparticle instillation. C57BL/6 mice instilled with CeO₂ exhibited mild pulmonary inflammation. However, B6.Cg-Kit(W-sh) mice did not display a similar degree of inflammation following CeO₂ instillation. Moreover, C57BL/6 mice instilled with CeO₂ exhibited altered aortic vascular responses to adenosine and an increase in myocardial ischemia/reperfusion injury which was absent in B6.Cg-Kit(W-sh) mice. In vitro CeO₂ exposure resulted in increased production of PGD₂, TNF-α, IL-6 and osteopontin by cultured mast cells. These findings demonstrate that CeO₂ nanoparticles activate mast cells contributing to pulmonary inflammation, impairment of vascular relaxation and exacerbation of myocardial ischemia/reperfusion injury.

Cardiovascular and inflammatory effects of intratracheally instilled ambient dust from Augsburg, Germany, in spontaneously hypertensive rats (SHRs)

Rationale

Several epidemiological studies associated exposure to increased levels of particulate matter in Augsburg, Germany with cardiovascular mortality and morbidity. To elucidate the mechanisms of cardiovascular impairments we investigated the cardiopulmonary responses in spontaneously hypertensive rats (SHR), a model for human cardiovascular diseases, following intratracheal instillation of dust samples from Augsburg.

Methods

250 μg, 500 μg and 1000 μg of fine ambient particles (aerodynamic diameter <2.5 μm, PM_2.5-AB) collected from an urban background site in Augsburg during September and October 2006 (PM_2.5 18.2 μg/m³, 10,802 particles/cm³) were instilled in 12 months old SHRs to assess the inflammatory response in bronchoalveolar lavage fluid (BALF), blood, lung and heart tissues 1 and 3 days post instillation. Radio-telemetric analysis was performed to investigate the cardiovascular responses following instillation of particles at the highest dosage based on the inflammatory response observed.

Results

Exposure to 1000 μg of PM_2.5-AB was associated with a delayed increase in delta mean blood pressure (ΔmBP) during 2^nd-4^th day after instillation (10.0 ± 4.0 vs. -3.9 ± 2.6 mmHg) and reduced heart rate (HR) on the 3^rd day post instillation (325.1 ± 8.8 vs. 348.9 ± 12.5 bpm). BALF cell differential and inflammatory markers (osteopontin, interleukin-6, C-reactive protein, and macrophage inflammatory protein-2) from pulmonary and systemic level were significantly induced, mostly in a dose-dependent way. Protein analysis of various markers indicate that PM_2.5-AB instillation results in an activation of endothelin system (endothelin1), renin-angiotensin system (angiotensin converting enzyme) and also coagulation system (tissue factor, plasminogen activator inhibitor-1) in pulmonary and cardiac tissues during the same time period when alternation in ΔmBP and HR have been detected.

Conclusions

Our data suggests that high concentrations of PM_2.5-AB exposure triggers low grade PM mediated inflammatory effects in the lungs but disturbs vascular homeostasis in pulmonary tissues and on a systemic level by affecting the renin angiotensin system, the endothelin system and the coagulation cascade. These findings are indicative for promotion of endothelial dysfunction, atherosclerotic lesions, and thrombogeneis and, thus, provide plausible evidence that susceptible-predisposed individuals may develop acute cardiac events like myocardial infarction when repeatedly exposed to high pollution episodes as observed in epidemiological studies in Augsburg, Germany.