Jinzhuo Zhao

The biological effects of individual-level PM2.5 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/m3 and 86.48 μg/m3 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.

Rat lung response to ozone and fine particulate matter (PM2.5) exposures

Exposure to different ambient pollutants maybe more toxic to lung than exposure to a single pollutant. In this study, we discussed the inflammation and oxidative stress responses of rat lung caused by ozone and PM2.5 versus that of rats exposed to saline, ozone, or single PM2.5. Wistar rats inhaled 0.8 ppm ozone or air for 4 h and then placed in air for 3 h following intratracheal instillation with 0, 0.2 (low dose), 0.8 (medium dose), 3.2 (high dose) mg/rat PM2.5 dissolved in sterile saline (0.25 mL/rat), repeated twice per week for 3 weeks, the cumulative doses of PM2.5 in animals were 1.2, 4.8, and 19.2 mg. Rats were sacrificed 24 h after the last (sixth) exposure. The collected bronchoalveolar lavage fluid (BALF) was analyzed for inflammatory cells and cytokines. Lung tissues were processed for light microscopic and transmission electron microscopic (TEM) examinations. Results showed that total cell number in BALF of PM2.5‐exposed groups were higher than control (p < 0.05). PM2.5 instillation caused dose‐trend increase in tumor necrosis factor alpha (TNF‐α), interleukin‐6, lactate dehydrogenase, and total protein of BALF. Exposure to ozone alone only caused TNF‐α significant change in above‐mentioned indicators of lung injury. On the other hand, ozone could enhance PM2.5‐induced inflammatory changes and pathological characters in rat lungs. SOD and GSH‐Px activities in lung were reduced in PM2.5‐exposed rats with and without prior ozone exposure compared to control. To determine whether the PM2.5 and ozone affect endothelium system, iNOS, eNOS, and ICAM‐1 mRNA levels in lung were analyzed by real‐time PCR. These data demonstrated that inflammation and oxidative stress were involved in toxicology mechanisms of PM2.5 in rat lung and ozone potentiated these effects induced by PM2.5. These results have implications for understanding the pulmonary effects induced by ozone and PM2.5.

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

The study is to explore the potential mechanisms linking fine particles and cardiovascular toxicity. Spontaneous hypertensive rats (SHR) and age-matched 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 continuous days. Twenty-four hours after the last exposure, the rats were killed and the levels of high sensitive C-reactive proteins (hsCRPs), nitrous oxide (NO), D-dimer and endothelin-1 (ET-1) were measured in blood. Reverse transcriptase polymerase chain reaction (RT-PCR) assay assessed the expression of interleukin-1 beta (IL-1beta), intercellular adhesion molecule-1 (ICAM-1), ET-1, Bax and Bcl-2 in left ventricle of rats. Meanwhile, cardiac histological lesions were assessed. The expression transforming growth factor-beta 1 (TGF-beta(1)) in left ventricle was measured by immunohistochemical staining. The results showed that the levels of hsCRP, D-dimer, ET-1 and the expression of IL-1beta, ICAM-1, ET-1, Bax and TGF-beta(1) increased in a dose-dependent manner, but NO and Bcl-2 decreased. Cardiac histology demonstrated exacerbated cardiac lesions in SHR when compared to WKY rats. Meanwhile, at the same dose exposed, the levels of hsCRP, d-dimer, ET-1 and the expression of IL-1beta, ICAM-1, ET-1, Bax and TGF-beta(1) were higher in SHR than those in WKY rats. The results indicated that ambient fine particles which entered into lungs could influence the cardiovascular system. When exposed to fine particles, SHR exhibited more severe cardiovascular injury in comparison to WKY rats. The results indicated that the inflammation, endothelial dysfunction, coagulation disorders and imbalance of apoptosis/anti-apoptosis might be the mechanisms of cardiovascular injury induced by fine particles. Different response between SHR and WKY rats after exposed to fine particles indicated that SHR was more susceptible than WKY rats to acute cardiac impairments from fine particle exposure.

Effect of Vitamin E and Omega-3 Fatty Acids on Protecting Ambient PM2.5-Induced Inflammatory Response and Oxidative Stress in Vascular Endothelial Cells.

Although the mechanisms linking cardiopulmonary diseases to ambient fine particles (PM2.5) are still unclear, inflammation and oxidative stress play important roles in PM2.5-induced injury. It is well known that inflammation and oxidative stress could be restricted by vitamin E (Ve) or omega-3 fatty acids (Ω-3 FA) consumption. This study investigated the effects of Ve and Ω-3 FA on PM2.5-induced inflammation and oxidative stress in vascular endothelial cells. The underlying mechanisms linking PM2.5 to vascular endothelial injury were also explored. Human umbilical vein endothelial cells (HUVECs) were treated with 50 μg/mL PM2.5 in the presence or absence of different concentrations of Ve and Ω-3 FA. The inflammatory cytokines and oxidative stress markers were determined. The results showed that Ve induced a significant decrease in PM2.5-induced inflammation and oxidative stress. Malondialdehyde (MDA) in supernatant and reactive oxygen species (ROS) in cytoplasm decreased by Ve, while the superoxide dismutase (SOD) activity elevated. The inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) also reduced by Ve. Moreover, Ω-3 FA played the same role on decreasing the inflammation and oxidative stress. IL-6 and TNF-α expressions were significantly lower in combined Ve with Ω-3 FA than treatment with Ve or Ω-3 FA alone. The Ve and Ω-3 FA intervention might abolish the PM2.5-induced oxidative stress and inflammation in vascular endothelial cells. There might be an additive effect of these two nutrients in mediating the PM2.5-induced injury in vascular endothelial cells. The results suggested that inflammation and oxidative stress might be parts of the mechanisms linking PM2.5 to vascular endothelial injury.

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.

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 Eagles 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.

Effects of Fine Particulate Matter (PM2.5) on Systemic Oxidative Stress and Cardiac Function in ApoE−/− Mice

Aim: In this study, we aimed to explore the toxic mechanisms of cardiovascular injuries induced by ambient fine particulate matter (PM2.5) in atherosclerotic-susceptible ApoE−/− mice. An acute toxicological animal experiment was designed with PM2.5 exposure once a day, every other day, for three days. Methods: ApoE−/− and C57BL/6 mice were randomly categorized into four groups, respectively (n = 6): one control group, three groups exposed to PM2.5 alone at low-, mid-, and high-dose (3, 10, or 30 mg/kg b.w.). Heart rate (HR) and electrocardiogram (ECG) were monitored before instillation of PM2.5 and 24 h after the last instillation, respectively. Cardiac function was monitored by echocardiography (Echo) after the last instillation. Biomarkers of systemic oxidative injuries (MDA, SOD), heart oxidative stress (MDA, SOD), and NAD(P)H oxidase subunits (p22phox, p47phox) mRNA and protein expression were analyzed in mice. The results showed that PM2.5 exposure could trigger the significant increase of MDA, and induce the decrease of heart rate variability (HRV), a marker of cardiac autonomic nervous system (ANS) function with a dose–response manner. Meanwhile, abnormal ECG types were monitored in mice after exposure to PM2.5. The expression of cytokines related with oxidative injuries, and mRNA and protein expression of NADPH, increased significantly in ApoE−/− mice in the high-dose group when compared with the dose-matched C57BL6 mice, but no significant difference was observed at Echo. In conclusion, PM2.5 exposure could cause oxidative and ANS injuries, and ApoE−/− mice displayed more severe oxidative effects induced by PM2.5.

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.

Association between individual PM2.5 exposure and DNA damage in traffic policemen.

Objective: The aim of this study was to explore the association between individual PM2.5 and DNA damage in traffic policemen. Methods: The participants included 110 traffic policemen and 101 common populations. The continuous 24-hour individual PM2.5 measurement was performed in participants. BPDE (benzo[a]pyrene 7,8-diol-9,10-epoxide)-DNA adducts and 1-OHP were detected. Results: The average concentration of 24-hour personal PM2.5 for traffic policemen was significantly higher than that in the control group. PM2.5 exposure is associated with a 1.1% increase in 1-OHP and 0.8% increase in BPDE-DNA adducts after adjusted for body mass index, educational time period, and alcohol intake. Exposure group has 2.04 times higher of 1-OHP and 1.25 times higher of BPDE-DNA adducts when compared to the control group. Conclusions: These results demonstrated that traffic policemen have been a high-risk group suffering DNA damage because of the high PM2.5 exposure.

Combined effects of vitamin E and omega-3 fatty acids on protecting ambient PM2.5-induced cardiovascular injury in rats

OBJECTIVE This study aims to observe whether the combined treatment with vitamin E (vit E) and omega-3 polyunsaturated fatty acids (Ω-3 FA) could prevent the fine particulate matter (PM2.5)-induced cardiovascular injury through alleviating inflammation and oxidative stress. At the same time, the appropriate combination dosage of vit E and Ω-3 FA was explored to find an optimized protective dose to protect the injury induced by PM2.5. METHODS The SD rats were pretreated with different concentration of vit E and Ω-3 FA separately or jointly. Then the rats were exposed to ambient PM2.5 by intratracheal instillation for three times. The expression of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) in serum and supernatant of cardiac tissue were detected by ELISA kits. The levels of malondialdehyde (MDA), superoxide Dismutase (SOD) and glutathione-peroxidase (GSH-Px) in myocardium and the level of MDA in serum were measured. Meanwhile, the cardiac injury was evaluated by histopathological examination. RESULTS Compared with the severe injury of rats in PM2.5 exposure group, the rats in vit E or Ω-3 FA-pretreated groups had a slighter injury in heart. Meanwhile, pretreatment with vit E or Ω-3 FA induced a significantly alleviation of the inflammatory cytokines (TNF-α, IL-1β, IL-6) and the elevation of the anti-oxidative activity especially in the rats pretreated with combined vit E and Ω-3 FA. In addition, the combined protecting effects of vit E and Ω-3 FA showed a dose-dependent manner. CONCLUSION Supplementation with vit E and Ω-3 FA could protect the PM2.5-induced injury, and the combination of vit E and Ω-3 FA might produce more effective effects than the separate nutrient did.