The inflammatory response in lungs of rats exposed on the airborne particles collected during different seasons in four European cities

Post-Effect of Air Quality Improvement on Biomarkers for Systemic Inflammation and Microparticles in Asthma Patients After the 2008 Beijing Olympic Games: a Pilot Study

This study's aim was to investigate the post-effect of an air quality improvement on systemic inflammation and circulating microparticles in asthmatic patients during, and 2 months after, the Beijing Olympics 2008. We measured the levels of circulating inflammatory cytokines and microparticles in the peripheral blood from asthma patients and healthy controls during (phase 1), and 2 months after (phase 2) the Beijing 2008 Olympic Games. The concentrations of circulating cytokines (including TNFα, IL-6, IL-8, and IL-10) were still seen reduced in phase 2 when compared with those in phase 1. The number of circulating endothelial cell-derived microparticles was significantly lower during the phase 2 than that during phase 1 in asthma patients. The level of plasma lipopolysaccharide-binding protein (LBP) was significantly decreased in asthmatics in phase 2. The level of norepinephrine was significantly higher in phase 2 than that in phase 1 in plasma from both asthma patients and healthy subjects. There were no significant differences in the gene profile for the toll-like receptor (TLR) signaling from peripheral blood mononuclear cells. In vitro, microvesicles from patients with asthma impaired the relaxation to bradykinin and contraction to acetylcholine, whereas microparticles from healthy subjects did not. These data suggested that reduction in systemic pro-inflammatory responses and circulating LBP and increased level of norepinephrine in asthma patients persisted even after 2 months of the air pollution intervention. These changes were independent of the TLR signaling pathway. Circulating microparticles might be associated with airway smooth muscle dysfunction.

Reduced serum club cell protein as a pulmonary damage marker for chronic fine particulate matter exposure in Chinese population

BACKGROUND

Exposure to fine particulate matter (PM_2.5) pollution is associated with increased morbidity and mortality from respiratory diseases. However, few population-based studies have been conducted to assess the alterations in circulating pulmonary proteins due to long-term PM_2.5 exposure.

METHODS

We designed a two-stage study. In the first stage (training set), we assessed the associations between PM_2.5 exposure and levels of pulmonary damage markers (CC16, SP-A and SP-D) and lung function in a coke oven emission (COE) cohort with 558 coke plant workers and 210 controls. In the second stage (validation set), significant initial findings were validated by an independent diesel engine exhaust (DEE) cohort with 50 DEE exposed workers and 50 controls.

RESULTS

Serum CC16 levels decreased in a dose response manner in association with both external and internal PM_2.5 exposures in the two cohorts. In the training set, serum CC16 levels decreased with increasing duration of occupational PM_2.5 exposure history. An interquartile range (IQR) (122.0μg/m³) increase in PM_2.5 was associated with a 5.76% decrease in serum CC16 levels, whereas an IQR (1.06μmol/mol creatinine) increase in urinary 1-hydroxypyrene (1-OHP) concentration was associated with a 5.36% decrease in serum CC16 levels in the COE cohort. In the validation set, the concentration of serum CC16 in the PM_2.5 exposed group was 22.42% lower than that of the controls and an IQR (1.24μmol/mol creatinine) increase in urinary 1-OHP concentration was associated with a 12.24% decrease in serum CC16 levels in the DEE cohort.

CONCLUSIONS

Serum CC16 levels may be a sensitive marker for pulmonary damage in populations with high PM_2.5 exposure.

Perfluoroalkyl substance exposure and urine CC16 levels among asthmatics: A case-control study of children

BACKGROUND

Studies have reported an association between serum perfluoroalkyl substances (PFASs) and asthma. However, few studies have examined the possible associations between PFASs and the 16-kDa club cell secretory protein (Clara) (CC16) level, a prominent biomarker of asthma, among adolescents.

METHODS

We recruited a total of 231 asthmatic children and 225 non-asthmatic controls in the Genetic and Biomarkers study for Childhood Asthma (GBCA) in northern Taiwan from 2009 to 2010. Structured questionnaires were administered by face-to-face interview. Urine CC16 was determined by an enzyme-link immunoassay kit. Multiple general linear models were employed to examine the associations between PFASs and urinary CC16 levels.

RESULTS

Asthmatic participants had significantly higher serum PFAS concentrations overall than the healthy controls. After adjusting for confounding factors, urinary CC16 was significantly, negatively associated with PFASs, especially PFOS, PFOA, PFDA and PFNA, and especially among males, as follows: PFOS (β = -0.003, 95% confidence interval [CI]: -0.004, -0.002), PFOA (β = -0.045, 95% CI: -0.086, -0.004), and PFHxA (β = -0.310, 95% CI: -0.455, -0.165) among asthmatic boys, and PFDA (β = -0.126, 95%CI: -0.241, -0.012) and PFNA (β = -0.329, 95% CI: -0.526, -0.132) among non-asthmatic boys. Among girls, PFDA (β = -0.088, 95% CI: -0.172, -0.004), was the only PFAS significantly associated with CC16. Significant interaction effects (p < 0.15) on CC16 levels were found between asthma and PFOS, PFOA, PFBS and PFHxA in all participants.

CONCLUSION

Our overall results showed that serum PFASs were significantly, inversely associated with CC16 levels. Associations were stronger among males.

In Vitro Toxicity and Epigenotoxicity of Different Types of Ambient Particulate Matter

Exposure to ambient particulate matter (PM) has been associated with adverse health effects, including pulmonary and cardiovascular disease. Studies indicate that ambient PM originated from different sources may cause distinct biological effects. In this study, we sought to investigate the potential of various types of PM to cause epigenetic alterations in the in vitro system. RAW264.7 murine macrophages were exposed for 24 and 72 h to 5- and 50-μg/ml doses of the water soluble extract of 6 types of PM: soil dust, road dust, agricultural dust, traffic exhausts, biomass burning, and pollen, collected in January-April of 2014 in the area of Little Rock, Arkansas. Cytotoxicity, oxidative potential, epigenetic endpoints, and chromosomal aberrations were addressed. Exposure to 6 types of PM resulted in induction of cytotoxicity and oxidative stress in a type-, time-, and dose-dependent manner. Epigenetic alterations were characterized by type-, time-, and dose-dependent decreases of DNA methylation/demethylation machinery, increased DNA methyltransferases enzymatic activity and protein levels, and transcriptional activation and subsequent silencing of transposable elements LINE-1, SINE B1/B2. The most pronounced changes were observed after exposure to soil dust that were also characterized by hypomethylation and reactivation of satellite DNA and structural chromosomal aberrations in the exposed cells. The results of our study indicate that the water-soluble fractions of the various types of PM have differential potential to target the cellular epigenome.

Alterations in rat pulmonary phosphatidylcholines after chronic exposure to ambient fine particulate matter

This study elucidated the underlying pathophysiological changes that occur after chronic ambient fine particulate matter (PM2.5) exposure via a lipidomic approach. Five male Sprague-Dawley rats were continually whole-body exposed to ambient air containing PM2.5 at 16.7 ± 10.1 μg m(-3) from the outside of the building for 8 months, whereas a control group (n = 5) inhaled filtered air. Phosphorylcholine-containing lipids were extracted from lung tissue and profiled using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The phosphatidylcholine (PC) signal features of the two groups were compared using partial least squares discriminant analysis (PLS-DA) and Wilcoxon rank sum tests. The PC profile of the exposure group differed from that of the control group; the R(2)Y and Q(2) were 0.953 and 0.677, respectively, in the PLS-DA model. In the exposure group, a significant 0.66- to 0.80-fold reduction in lyso-PC levels, which may have resulted from repeated inflammation, was observed. Decreased surfactant PCs by 16% at most may indicate injuries to alveolar type II cells. Cell function and cell signalling are likely to be altered because the decrease in unsaturated PCs may reduce membrane fluidity. Accompanied by the decline in plasmenylcholines, decreased unsaturated PCs may indicate the attack of reactive oxygen species generated by PM2.5 exposure. The physiological findings conformed to the histopathological changes in the exposed animals. PC profiling using UPLC-MS/MS-based lipidomics is sensitive for reflecting pathophysiological perturbations in the lung after long-term and low concentration PM2.5 exposure.

Markers of inflammation and coagulation after long-term exposure to coarse particulate matter: a cross-sectional analysis from the multi-ethnic study of atherosclerosis

BACKGROUND

Toxicological research suggests that coarse particles (PM10-2.5) are inflammatory, but responses are complex and may be best summarized by multiple inflammatory markers. Few human studies have investigated associations with PM10-2.5 and, of those, none have explored long-term exposures. Here we examine long-term associations with inflammation and coagulation in the Multi-Ethnic Study of Atherosclerosis.

METHODS

Participants included 3,295 adults (45-84 years of age) from three metropolitan areas. Site-specific spatial models were used to estimate 5-year concentrations of PM10-2.5 mass and copper, zinc, phosphorus, silicon, and endotoxin found in PM10-2.5. Outcomes included interleukin-6, C-reactive protein, fibrinogen, total homocysteine, D-dimer, factor VIII, plasmin-antiplasmin complex, and inflammation and coagulation scores. We used multivariable regression with multiply imputed data to estimate associations while controlling for potential confounders, including co-pollutants such as fine particulate matter.

RESULTS

Some limited evidence was found of relationships between inflammation and coagulation and PM10-2.5. Endotoxin was the PM10-2.5 component most strongly associated with inflammation, with an interquartile range (IQR) increase (0.08 EU/m3) associated with 0.15 (95% CI: 0.01, 0.28; p = 0.03) and 0.08 (95% CI: -0.07, 0.23; p = 0.28) higher inflammation scores before and after control for city, respectively. Copper was the component with the strongest association with coagulation, with a 4-ng/m3 increase associated with 0.19 (95% CI: 0.08, 0.30; p = 0.0008) and 0.12 (95% CI: -0.05, 0.30; p = 0.16) unit higher coagulation scores before and after city adjustment, respectively.

CONCLUSIONS

Our cross-sectional analysis provided some evidence that long-term PM10-2.5 exposure was associated with inflammation and coagulation, but associations were modest and depended on particle composition.

Rat lung response to PM2.5 exposure under different cold stresses

Ambient particulate matters and temperature were reported to have additive effects over the respiratory disease hospital admissions and deaths. The purpose of this study is to discuss the interactive pulmonary toxicities of cold stress and fine particulate matter (PM2.5) exposure by estimating inflammation and oxidative stress responses. 48 Wistar male rats, matched by weight and age, were randomly assigned to six groups, which were treated with cold stress alone (0 °C, 10 °C, and 20 °C (Normal control)) and cold stresses plus PM2.5 exposures respectively. Cold stress alone groups were intratracheal instillation of 0.25 mL normal saline, while cold stress plus PM2.5 exposure groups were intratracheal instillation of 8 mg/0.25 mL PM2.5. These procedures were carried out for three times with an interval of 48 hours for each treatment. All rats were sacrificed after 48 hours of the third treatment. The bronchoalveolar lavage fluid (BALF) was collected for analyzing inflammatory cells and cytokines, and lung homogenate MDA was determined for oxidative stress estimation. Results showed higher level of total cell and neutrophil in the BALF of PM2.5 exposed groups (p < 0.05). Negative relationships between cold stress intensity and the level of tumor necrosis factor alpha (TNF-a), C-reactive protein (CRP) interleukin-6 (IL-6) and interleukin-8 (IL-8) in BALF were indicated in PM2.5 exposure groups. Exposure to cold stress alone caused significant increase of inflammatory cytokines and methane dicarboxylic aldehyde (MDA) and decline of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity only in 0 °C exposure group (p < 0.05). The two-way ANOVA found significant interactive effects between PM2.5 exposure and cold stress in the level of neutrophil, IL-6 and IL-8 and SOD activity (p < 0.05). These data demonstrated that inflammation and oxidative stress involved in the additive effect of PM2.5 exposure and cold stress on pulmonary toxicity, providing explanation for epidemiological studies on the health effect of ambient PM2.5 and cold stress.

Ambient vapor samples activate the Nrf2-ARE pathway in human bronchial epithelial BEAS-2B cells

Ambient air pollutants have been reported to induce oxidative stress based inflammatory responses in humans and experimental animals. However, most of these reports describe the actions of the particulate phase of ambient and exhaust samples. We describe here results of studies investigating the actions of the vapor phase of ambient air samples collected in the midtown area of Los Angeles on human bronchial epithelial BEAS-2B cells using DNA microarray analysis. Among 26 genes whose expression increased fourfold or more, four genes were associated with detoxifying genes regulated by the transcription factor Nrf2. Consistent with these results, the vapor samples activate the Nrf2-ARE pathway, resulting in up-regulation of heme oxygenase-1 (HO-1), glutamate cysteine ligase modifier subunit, and cystine transporter (xCT) mRNA and proteins. No appreciable increases in pro-inflammatory genes were observed. These results suggest that ambient vapor samples activate the Nrf2-ARE pathway but not an inflammatory response. Also, treatment of the vapor samples with glutathione resulted in reduction in the Nrf2 activation and HO-1 induction, suggesting that electrophiles in vapor samples contribute to this Nrf2-dependent antioxidant or adaptive response.

Particulate matter beyond mass: recent health evidence on the role of fractions, chemical constituents and sources of emission

Particulate matter (PM) is regulated in various parts of the world based on specific size cut offs, often expressed as 10 or 2.5 µm mass median aerodynamic diameter. This pollutant is deemed one of the most dangerous to health and moreover, problems persist with high ambient concentrations. Continuing pressure to re-evaluate ambient air quality standards stems from research that not only has identified effects at low levels of PM but which also has revealed that reductions in certain components, sources and size fractions may best protect public health. Considerable amount of published information have emerged from toxicological research in recent years. Accumulating evidence has identified additional air quality metrics (e.g. black carbon, secondary organic and inorganic aerosols) that may be valuable in evaluating the health risks of, for example, primary combustion particles from traffic emissions, which are not fully taken into account with PM2.5 mass. Most of the evidence accumulated so far is for an adverse effect on health of carbonaceous material from traffic. Traffic-generated dust, including road, brake and tire wear, also contribute to the adverse effects on health. Exposure durations from a few minutes up to a year have been linked with adverse effects. The new evidence collected supports the scientific conclusions of the World Health Organization Air Quality Guidelines and also provides scientific arguments for taking decisive actions to improve air quality and reduce the global burden of disease associated with air pollution.

The effect of particle size, location and season on the toxicity of urban and rural particulate matter

Particulate matter (PM) varies in chemical composition and mass concentration based on a number of factors including location, season, source and particle size. The aim of this study was to evaluate the in vitro and in vivo toxicity of coarse and fine PM simultaneously collected at three rural and two urban sites within the metropolitan New York City (NYC) region during two seasons, and to assess how particle size and elemental composition affect toxicity. Human pulmonary microvascular endothelial (HPMEC-ST1.6R) and bronchial epithelial (BEAS-2B) cell lines were exposed to PM (50 μg/mL) and analyzed for reactive oxygen species (ROS). Mice (FVB/N) were exposed by oropharyngeal aspiration to 50 µg PM, and lavage fluid was analyzed for total protein and PMN influx. The ROS response was greater in the HPMEC-ST1.6R cell line compared to BEAS-2B cells, but the responses were significantly correlated (p < 0.01). The ROS response was affected by location, locale and the location:size interaction in both cell lines, and an additional association for size was observed from HPMEC-ST1.6R cells. Urban fine PM generated the highest ROS response. In the mouse model, inflammation was associated with particle size and by a season:size interaction, with coarse PM producing greater PMN inflammation. This study showed that the aerodynamic size, locale (i.e. urban versus rural), and site of PM samples affected the ROS response in pulmonary endothelial and epithelial cells and the inflammatory response in mice. Importantly, these responses were dependent upon the chemical composition of the PM samples.

Comparison of neurobehavioral and biochemical effects in rats exposed to dusts from copper smelter plant at different locations

Mixed exposure to metals (including arsenic and lead) associated with the neurological and respiratory effects constitute one of the major health problems of copper smelting. Chemical composition of the dust, and the expected health effect of inhalation can be very diverse at different parts of the smelter plant. The aims of this study were to compare lung responses and behavioral effects in female Wistar rats after instillation of dust collected from different production processes at the same smelter department. Dusts collected at two different locations of furnace hall were sifted through 25-μm-mesh sieve. Obtained dust fractions, P-25(I) collected near stove, rich in heavy metals and arsenic, and P-25(II) collected near anode residue storage site, rich in aluminium, were instilled to rats. At 1, 7 and 30 days after dusts instillation, lung injury and inflammation were measured by analyzing sings of lung permeability in the bronchoalveolar lavage fluid (BALF), cell differentiation in BALF sediment and lung morphology. The behavioral studies were done 30 days after exposure. Results of biochemical tests showed a strong pro-inflammatory effect of P-25(I) fractions. Mostly characteristic effects after instillation of P-25(I) samples were 10× increased protein leakages in BALF. Both P-25(I) and P-25(II) fractions caused a reduction of Clara-cell 16 protein concentration (CC16) in BALF and activation of serum butyrylcholinesterase (BChE) at all time points. The morphological studies after exposure to P-25(I) fractions showed multi-focal infiltrations in the alveoli. The behavioral results, especially P-25(II) group rats (in open filed, passive avoidance and hot plate tests), indicated adverse effects in the nervous system, which may be related to changes in the dopaminergic and cholinergic pathway. The symptoms were noted in the form of persistent neurobehavioral changes which might be associated with the content of neurotoxic metals. e.g. Al, Mn and/or As. Decrease of CC16 concentration that occurred immediately after instillation of both dust samples, point out impaired anti-inflammatory potential, resulted in early harmful effect not only to the respiratory tract but also to the whole body, including the nervous system.

Respirable antimony and other trace-elements inside and outside an elementary school in Flagstaff, AZ, USA

Because people spend almost 90% of their time indoors, ambient air monitors may severely underestimate actual exposure to atmospheric particulate matter (PM). Therefore, it becomes increasingly important to better understand the microenvironments where people are spending their time. For preadolescent children, the best estimates of exposure may be inside of their school. In this study, 11 size fractions of PM were collected inside and outside of an elementary school in Flagstaff, AZ, USA. In particles<1 μm (PM1), the total mass indoors was similar to the mass outdoors (indoor:outdoor, I:O, ratio=0.92 ± 0.16). In the PM1-10 fraction, however, the mass concentration inside the school was highly elevated relative to outside the school (I:O ratios=13 ± 3). Mass concentrations of 27 elements were analyzed by ICP-MS. For all metals except for antimony (Sb), the PM1 and PM1-10 I:O ratios are found to be similar to the overall PM mass (near 1 and 13, respectively). In addition, indoor and outdoor particle size distributions reveal a crustal character for every element except Cu, Zn, Pb, and Sb. Therefore, we hypothesize that most of the PM mass inside the school is a result of transport from outside the school followed by resuspension from floors and clothing. In the PM1 fraction, the indoor mass of Sb was 86 times greater than the outdoor mass and had an air concentration of 17 ngm(-3) - greater than many urban areas around the world. Cu:Sb ratios and size distribution functions suggest that the excess source of PM1 indoor Sb results from the suspension of embedded Sb (used as a flame retardant) in the carpeting. This is the first study to observe elevated submicron Sb in schools and further studies are required to determine if this is a widespread health risk.