Acute pulmonary and hematological effects of two types of particle surrogates are influenced by their elemental composition

Association of household air pollution exposure and anemia among pregnant women: Analysis of baseline data from 'Household Air Pollution Intervention Network (HAPIN)' trial

BACKGROUND

Anemia is common in low- and middle-income countries (LMICs), causing significant health issues and social burdens. Exposure to household air pollution from using biomass fuels for cooking and heating has been associated with anemia, but the exposure-response association has not been studied.

OBJECTIVES

We evaluated the associations between personal exposure to air pollution and both hemoglobin levels and anemia prevalence among pregnant women in a multi-country randomized controlled trial.

METHODS

We studied 3,163 pregnant women aged 18-35 years with 9-20 weeks of gestation, recruited as part of the Household Air Pollution Intervention Network (HAPIN) randomized controlled trial in Guatemala, India, Peru, and Rwanda. We assessed 24-hour personal exposures to fine particulate matter (PM2.5), black carbon (BC), and carbon monoxide (CO), and measured hemoglobin levels at baseline (15 ± 3 weeks gestation). Linear and logistic regression models were used to examine the associations of measured pollutants with hemoglobin levels and anemia prevalence, adjusting for confounding.

RESULTS

Single-pollutant models showed associations of CO with higher hemoglobin levels and lower anemia prevalence. Bipollutant models involving CO and PM2.5 also revealed that an interquartile range (IQR) increase in CO concentrations (2.26 ppm) was associated with higher hemoglobin levels [β = 0.04; 95 % confidence interval (CI): 0.01, 0.07], and a lower odds of anemia prevalence [odds ratios (OR) = 0.90; 95 % CI: 0.83, 0.98]. PM2.5 was inversely related to hemoglobin and positively associated with anemia, but results were not statistically significant at the 0.05 alpha level. County-specific results showed that 3 of 4 countries showed a similar association between CO and hemoglobin. We found no association of BC levels with hemoglobin levels or with anemia prevalence.

CONCLUSION

Our findings suggest that exposure to CO is associated with higher hemoglobin and lower anemia prevalence among pregnant women, whereas PM2.5 showed the opposite associations.

Moderate aerobic training is safe and improves glucose intolerance induced by the association of high fat diet and air pollution

Obesity and exposure to fine particulate matter (PM_2.5) are risk factors for insulin resistance, to which physical exercise is the most powerful non-pharmacological strategy. However, public concern over whether exercise could be protective in a polluted environment exists. Therefore, evaluating the possible benefits of exercise in polluted conditions in different contexts (age, gender, and cardiometabolic health) is imperative. In this sense, muscle plays a major role in maintaining glucose homeostasis, and its oxidative status is closely affected during exercise. This study tested whether moderate aerobic training could alleviate the metabolic and oxidative impairment in the gastrocnemius induced by the combination of a high-fat diet (HFD) and PM_2.5 exposure. Female mice (B6129SF2/J) received HFD (58.3% of fat) or standard diet, intranasal instillation of 20 μg residual oil fly ash (ROFA: inorganic portion of PM_2.5), or saline seven times per week for 19 weeks. In the 13th week, animals were submitted to moderate training or remained sedentary. Trained animals followed a progressive protocol for 6 weeks, ending at swimming with 5% body weight of workload for 60 min, while sedentary animals remained in shallow water. Aerobic moderate training attenuated weight gain and glucose intolerance and prevented muscle and pancreatic mass loss induced by a HFD plus ROFA exposure. Interestingly, a HFD combined with ROFA enhanced the catalase antioxidant activity, regardless of physical exercise. Therefore, our study highlights that, even in polluted conditions, moderate training is the most powerful non-pharmacological treatment for obesity and insulin resistance.

Gestational PM2.5 exposure may increase the risk of small for gestational age through maternal blood pressure and hemoglobin: A mediation analysis based on a prospective cohort in China, 2014-2018

BACKGROUND

Maternal gestational PM_2.5 exposure was associated with small for gestational age (SGA). Identifying potential mediating factors may help design preventive strategies to reduce this risk.

OBJECTIVE

This study aimed to explore the roles of maternal blood pressure and hemoglobin may play in the PM_2.5 exposure and SGA relationship among 117,162 births in 16 counties across China during 2014-2018.

METHODS

Daily PM_2.5 concentration was collected from China National Environmental Monitoring Center. According to maternal residency during pregnancy, the PM_2.5 exposure for each trimester and the whole pregnancy was assessed using an inverse-distance weighting approach. Repeated measurements of maternal blood pressure and hemoglobin during pregnancy were collected for each woman. We estimated the total effect of gestational PM_2.5 exposure on SGA, and further tested the mediation effects of maternal blood pressure and hemoglobin concentration during pregnancy.

RESULTS

Of 117,162 included mother-infant pairs, 11,361 (9.7 %) were SGA. The odds ratios of SGA associated with PM_2.5 exposure (per 10 μg/m³ increase) in the second trimester and the whole pregnancy were 1.023 (95 % CI: 1.009, 1.037) and 1.024 (1.001, 1.048), respectively. We identified the independent mediating effect of blood pressure and hemoglobin in the second and third trimesters, with the proportion of mediation ranging from 1.64 % to 5.78 % and 2.40 % to 8.70 %, respectively. When considering the mediators jointly, we found a stronger mediating effect with a proportion of mediation ranging from 3.93 % to 13.69 %.

DISCUSSION

Increases in maternal blood pressure and hemoglobin in the second and third trimesters can independently and jointly mediate the effects of gestational PM_2.5 exposure on SGA. Monitoring and managing maternal blood pressure and hemoglobin during prenatal care may constitute a promising avenue to reducing SGA risk associated with gestational PM_2.5 exposure.

Association between air particulate matter pollution and blood cell counts of women preparing for pregnancy: Baseline analysis of a national birth cohort in China

BACKGROUND

Limited evidence is known about whether long-term exposures to air borne particulate matters of 2.5 μm or less (PM_2.5) impact human hematologic index for women preparing for pregnancy. No study assessed the effect of PM₁, which is small enough to reach the blood circulation.

OBJECTIVE

To evaluate whether exposure to PM₁ and PM_2.5 is associated with blood cell count of woman preparing for pregnancy.

METHOD

Based on the baseline data of a national birth cohort in China, we analysed the white blood cell (WBC), red blood cells (RBC) and thrombocyte counts of 1,203,565 women who are aged 18-45 years, being Han ethnicity, had no chronic disease and preparing for pregnancy. We matched their home addresses and examination date with daily concentrations of PM₁ and PM_2.5 which were estimated by a machine learning method with remote sensing, meteorological and land use information. Generalized additive mixed model to examine the associations between exposure to one-year average exposure to PMs prior to the health examination and the blood cells counts, after adjustment for potential individual variables.

RESULTS

A 10 μg/m³ PM₁ increment was associated with -1.49% (95%CI: 1.56%, -1.42%) difference in WBC count; with 0.33% (95%CI: 0.30%, 0.36%) difference of RBC count; and with 1.08% (95%CI: 1.01%, 1.15%) difference of thrombocyte count. For PM_2.5, the corresponding difference was -0.47% (95%CI: 0.54%, -0.39%) for WBC; was 0.06% (95%CI: 0.03%, 0.09%) for RBC; and was 1.10% (95%CI: 1.02%, 1.18%) for thrombocyte. Women working as workers, being overweight and with tobacco smoking exposure had higher associations between PMs and hematologic index than their counterparts (p < 0.05 for interaction test).

CONCLUSION

Long-term exposure to PMs were associated with decrement in WBC, as well as increment in RBC and thrombocytes among Han Chinese women preparing for pregnancy. Measures such as using air purifiers and wearing a mask in polluted areas should be improved to prevent women from the impact of PMs.

Ovariectomy reduces the cardiac cytoprotection in rats exposed to particulate air pollutant

Fine particulate matter (PM_2.5) has been considered a risk factor for cardiovascular diseases by inducing an oxidative and inflammatory phenotype. Besides, the reduction of 17β-estradiol (E2) levels during menopause is a natural risk for cardiovascular outcomes. During the E2 downfall, there is a high requirement of the 70-kDa heat shock proteins (HSP70), which present essential antioxidant, anti-inflammatory, and anti-senescence roles. We investigated if the ovariectomy, an animal model for menopause, could induce additional effects in cardiac health by impairing oxidative and heat shock response parameters of female rats chronically exposed to residual oil fly ash (ROFA; an inorganic fraction of PM_2.5). Thus, ROFA was obtained from São Paulo (Brazil) and solubilized it in saline. Further, female Wistar rats were exposed to 50 μL of saline (control group) or ROFA solution (250 μg) (polluted) by intranasal instillation, 5 days/week, 12 weeks. At the 12th week, animals were subdivided into four groups (n = 6 p/group): control, OVX, polluted, and polluted + OVX. Control and polluted were submitted to false surgery, while OVX and polluted + OVX were ovariectomized. ROFA or saline exposure continued for 12 weeks. Ovariectomy reduced the cardiac catalase activity and iHSP70 expression in female rats exposed to ROFA. Neither plasma eHSP72 levels nor H-index (eHSP72 to cardiac iHSP70 ratio) was affected. In conclusion, ovariectomy reduces the cardiac cytoprotection and antioxidant defense, and enhances the susceptibility to premature cellular senescence in rats exposed to ROFA.

Ovariectomy enhances female rats' susceptibility to metabolic, oxidative, and heat shock response effects induced by a high-fat diet and fine particulate matter

Obesity and exposure to fine particulate matter (air pollutant PM_2.5) are important risk factors for metabolic and cardiovascular diseases. They are also related to early menopause. The reduction of 17β-estradiol (E2) levels during female climacteric, marked by menopause, is of significant concern because of its imminent influence on metabolism, redox and inflammatory status. This complex homeostasis-threatening scenario may induce a heat shock response (HSR) in cells, enhancing the expression of the 70 kDa heat shock protein (HSP70). A failure in this mechanism could predispose women to cardiovascular diseases. In this study, we evaluated if the climacteric could represent an additional risk among obese rats exposed to PM_2.5 by worsening lipid, oxidative, and inflammatory parameters and HSP70 in cardiac tissue. We induced obesity in female Wistar rats using a high-fat diet (HFD) (58.3% as fats) and exposed them to 50 μL of saline 0.9% (control, n = 15) or 250 μg residual oil fly ash (ROFA, the inorganic portion of PM_2.5) (polluted, n = 15) by intranasal instillation, 5 days/w for 12 weeks. At the 12th week, we subdivided these animals into four groups: control (n = 6), OVX (n = 9), polluted (n = 6) and polluted + OVX (n = 9). OVX and polluted + OVX were submitted to a bilateral ovariectomy (OVX), a surgical model for menopause, while control and polluted received a false surgery (sham). ROFA exposure and HFD consumption were continued for 12 additional weeks, after which the animals were euthanized. ROFA enhanced the susceptibility to ovariectomy-induced dyslipidemia, while ovariectomy predisposed female rats to the ROFA-induced decrease of cardiac iHSP70 expression. Ovariectomy also decreased the IL-6 levels and IL-6/IL-10 in obese animals, reinforcing a metabolic impairment and a failure to respond to unfavorable conditions. Our results support the hypothesis that obese ovariectomized animals are predisposed to a metabolic worsening under polluted conditions and are at higher risk of cardiovascular diseases.

The association of subchronic exposure to low concentration of PM2.5 and high-fat diet potentiates glucose intolerance development, by impairing adipose tissue antioxidant defense and eHSP72 levels

The subchronic exposure to fine particulate matter (PM2.5) and high-fat diet (HFD) consumption lead to glucose intolerance by different mechanisms involving oxidative stress and inflammation. Under stressful conditions, the cells exert a heat shock response (HSR), by releasing the 72-kDa heat shock proteins (eHSP72), fundamental chaperones. The depletion of the HSR can exacerbate the chronic inflammation. However, there are few studies about the early effects of the association of HFD consumption and exposure to low concentrations of PM2.5 in the oxidative stress and HSR, in the genesis of glucose intolerance. Thus, we divided 23 male B6129SF2/J mice into control (n = 6), polluted (n = 6), HFD (n = 6), and high-fat diet + polluted (HFD + polluted) (n = 5) groups. Control and polluted received a standard diet (11.4% of fats), while HFD and HFD + polluted received HFD (58.3% of fats). Simultaneously, polluted and HFD + polluted received 5 μg/10 μL of PM2.5, daily, 7×/week, while control and HFD were exposed to 10 μL of saline solution 0.9% for 12 weeks. At the 12th week, animals were euthanized. We collected the metabolic tissues to analyze oxidative parameters, total blood to the hematological parameters, and plasma to eHSP72 measurement. The association of HFD and PM2.5 impaired glucose tolerance in the 12th week. Besides, it triggered an antioxidant defense by the adipose tissue, which was negatively correlated with eHSP72 levels. In conclusion, a low concentration of PM2.5 exposure associated with HFD consumption leads to glucose intolerance, by impairing adipose tissue antioxidant defense and systemic eHSP72 levels.

Inhale, exhale: Why particulate matter exposure in animal models are so acute? Data and facts behind the history

We present a dataset obtained by extracting information from an extensive literature search of toxicological experiments using mice and rat animal models to study the effects of exposure to airborne particulate matter (PM). Our dataset covers results reported from 75 research articles considering paper published in 2017 and seminal papers from previous years. The compiled data and normalization were processed with an equation based on a PM dosimetry model. This equation allows the comparison of different toxicological experiments using instillation and inhalation as PM exposure protocols with respect to inhalation rates, concentrations and PM exposure doses of the toxicological experiments performed by different protocols using instillation and inhalation PM as exposure methods. This data complements the discussions and interpretations presented in the research article “Inhale, exhale: why particulate matter exposure in animal models are so acute?” Curbani et al., 2019.

Ovariectomy predisposes female rats to fine particulate matter exposure's effects by altering metabolic, oxidative, pro-inflammatory, and heat-shock protein levels

The reduction of estrogen levels, as a result of menopause, is associated with the development of metabolic diseases caused by alterations in oxidative stress (OS), inflammatory biomarkers, and 70-kDa heat-shock protein (HSP70) expression. Additionally, exposure to fine particulate matter air pollution modifies liver OS levels and predisposes organisms to metabolic diseases, such as type 2 diabetes (T2DM). We investigated whether ovariectomy affects hepatic tissue and alters glucose metabolism in female rats exposed to particulate air pollution. First, 24 female Wistar rats received an intranasal instillation of saline or particles suspended in saline 5 times per week for 12 weeks. The animals then received either bilateral ovariectomy (OVX) or false surgery (sham) and continued to receive saline or particles for 12 additional weeks, comprising four groups: CTRL, Polluted, OVX, and Polluted+OVX. Ovariectomy increased body weight and adiposity and promoted edema in hepatic tissue, hypercholesterolemia, glucose intolerance, and a pro-inflammatory profile (reduced IL-10 levels and increased IL-6/IL-10 ratio levels), independent of particle exposure. The Polluted+OVX group showed an increase in neutrophils and neutrophil/lymphocyte ratios, decreased antioxidant defense (SOD activity), and increased liver iHSP70 levels. In conclusion, alterations in the reproductive system predispose female organisms to particulate matter air pollution effects by affecting metabolic, oxidative, pro-inflammatory, and heat-shock protein expression.

Prenatal exposure to fine particulate matter, maternal hemoglobin concentration, and fetal growth during early pregnancy: associations and mediation effects analysis

BACKGROUND

Fetal essential organ development is completed during early pregnancy which is important for fetal and postnatal health. However, the effect of exposure to PM_2.5 on fetal growth during early pregnancy is less studied and the related mechanisms are largely unknown.

METHODS

We conducted a birth cohort study of 1945 pregnant women with measurement of the fetal crown to rump length (CRL) by ultrasound between the gestational age of 11 and 14 weeks. We estimated residential exposures of PM_2.5 from the date of LMP to the date of ultrasound examination using a spatial-temporal land use regression model. Maternal hemoglobin concentration was examined by maternal blood samples during the same gestational period or ±1 week of the ultrasound examination. The associations of exposure to PM_2.5 with maternal hemoglobin concentration, and exposure to PM_2.5 with fetal CRL during early pregnancy were estimated by multiple linear regression models. The mediation effect of maternal hemoglobin concentration on the association between exposure to PM_2.5 and fetal CRL was explored by a casual mediation analysis.

RESULTS

One IQR increment of prenatal exposure to PM_2.5 was associated with a 0.929 g/L (95% CI: 0.068, 1.789) increase in maternal hemoglobin concentration, and associated with a -0.082 cm (95% CI: 0.139, -0.025) decrease in fetal CRL. One g/L increment of maternal hemoglobin concentration was associated a -0.011 cm (95% CI: 0.014, -0.008) decrease in fetal CRL. The mediation analysis indicated that 12.1% of the total effect of prenatal exposure to PM_2.5 on reducing fetal CRL was mediated by increased maternal hemoglobin concentration.

CONCLUSION

Exposure to PM_2.5 was associated with reduced fetal growth during early pregnancy and elevated maternal hemoglobin concentration mediated this association.

Aerobic training reduces oxidative stress in skeletal muscle of rats exposed to air pollution and supplemented with chromium picolinate

Objective: The purpose of this study was to investigate the effects of chromium picolinate (CrPic) supplementation associated with aerobic exercise using measures of oxidative stress in rats exposed to air pollution.

Methods: Sixty-one male Wistar rats were divided into eight groups: residual oil fly ash (ROFA) exposure and sedentary (ROFA-SED); ROFA exposure, sedentary and supplemented (ROFA-SED-CrPic); ROFA exposure and trained (ROFA-AT); ROFA exposure, supplemented and trained (ROFA-AT-CrPic); sedentary (Sal-SED); sedentary and supplemented (Sal-SED-CrPic); trained (Sal-AT); and supplemented and trained (Sal-AT-CrPic). Rats exposed to ROFA (air pollution) received 50 µg of ROFA daily via intranasal instillation. Supplemented rats received CrPic (1 mg/kg/day) daily by oral gavage. Exercise training was performed on a rat treadmill (5×/week). Oxidative parameters were evaluated at the end of protocols.

Results: Trained groups demonstrated lower gain of body mass (P < .001) and increased exercise tolerance (P < .0001). In the gastrocnemius, trained groups demonstrated increased SOD activity (P < .0001) and decrease levels of TBARS (P = .0014), although CAT activity did not differ among groups (P = .4487).

Conclusion: Air pollution exposure did not lead to alterations in oxidative markers in lungs and heart, and exercise training was responsible for decreasing oxidative stress of the gastrocnemius.

Acute exposure to diesel and sewage biodiesel exhaust causes pulmonary and systemic inflammation in mice

Biodiesel is a renewable energy source that reduces particle emission, but few studies have assessed its effects. To assess the effects of acute inhalation of two doses (600 and 1200 μg/m³) of diesel (DE) and biodiesel (BD) fuels on the inflammatory pulmonary and systemic profile of mice. Animals were exposed for 2 h in an inhalation chamber inside the Container Laboratory for Fuels. Heart rate, heart rate variability (HRV) and blood pressure were determined 30 min after exposure. After 24 h, we analyzed the lung inflammation using bronchoalveolar lavage fluid (BALF); neutrophil and macrophage quantification in the lung parenchyma was performed, and blood and bone marrow biomarkers as well as receptor of endothelin-A (ET-Ar), receptor of endothelin-B (ET-Br), vascular cell adhesion molecule 1 (VCAM-1), inducible nitric oxide synthase (iNOs) and isoprostane (ISO) levels in the pulmonary vessels and bronchial epithelium were evaluated. HRV increased for BD600, D600 and D1200 compared to filtered air (FA). Both fuels (DE and BD) produced alterations in red blood cells independent of the dose. BALF from the BD600 and BD1200 groups showed an increase in neutrophils compared to those of the FA group. Numeric density of the polymorphonuclear and mononuclear cells was elevated with BD600 compared to FA. In the peribronchiolar vessels, there was an increase in ET-Ar and ET-Br expression following BD600 compared to FA; and there was a reduction in the iNOs expression for BD1200 and the VCAM-1 for D1200 compared to FA. In the bronchial epithelium, there was an increase in ETAr at BD600, ET-Br at two doses (600 and 1200 μg/m³) of DE and BD, iNOs at D600 and VCAM-1 at BD1200 and D600; all groups were compared to the FA group. Acute exposure to DE and BD derived from sewage methyl esters triggered pulmonary and cardiovascular inflammatory alterations in mice.

Fine particulate matter potentiates type 2 diabetes development in high-fat diet-treated mice: stress response and extracellular to intracellular HSP70 ratio analysis

Exposure to fine particulate matter (PM_2.5) air pollution is a risk factor for type 2 diabetes (T2DM). We argue whether the potentiating effect of PM_2.5 over the development of T2DM in high-fat diet (HFD)-fed mice would be related to modification in cell stress response, particularly in antioxidant defenses and 70-kDa heat shock proteins (HSP70) status. Male mice were fed standard chow or HFD for 12 weeks and then randomly exposed to daily nasotropic instillation of PM_2.5 for additional 12 weeks under the same diet schedule, divided into four groups (n = 14-15 each): Control, PM_2.5, HFD, and HFD + PM_2.5 were evaluated biometric and metabolic profiles of mice, and cellular stress response (antioxidant defense and HSP70 status) of metabolic tissues. Extracellular to intracellular HSP70 ratio ([eHSP72]/[iHSP70]), viz. H-index, was then calculated. HFD + PM_2.5 mice presented a positive correlation between adiposity, increased body weight and glucose intolerance, and increased glucose and triacylglycerol plasma levels. Pancreas exhibited lower iHSP70 expression, accompanied by 3.7-fold increase in the plasma to pancreas [eHSP72]/[iHSP70] ratio. Exposure to PM_2.5 markedly potentiated metabolic dysfunction in HFD-treated mice and promoted relevant alteration in cell stress response assessed by [eHSP72]/[iHSP70], a relevant biomarker of chronic low-grade inflammatory state and T2DM risk.

Silica nanoparticles induced the pre-thrombotic state in rats via activation of coagulation factor XII and the JNK-NF-κB/AP-1 pathway

The pre-thrombotic state induced by SiNPsviathe interaction between platelet activation, coagulation hyperfunction, anti-coagulation and fibrinolytic resistance.

Time course of pulmonary burden in mice exposed to residual oil fly ash

Residual oil fly ash (ROFA) is a common pollutant in areas where oil is burned. This particulate matter (PM) with a broad distribution of particle diameters can be inhaled by human beings and putatively damage their respiratory system. Although some studies deal with cultured cells, animals, and even epidemiological issues, so far a comprehensive analysis of respiratory outcomes as a function of the time elapsed after exposure to a low dose of ROFA is wanted. Thus, we aimed to investigate the time course of mechanical, histological, and inflammatory lung changes, as well as neutrophils in the blood, in mice exposed to ROFA until 5 days after exposure. BALB/c mice (25 ± 5 g) were randomly divided into 7 groups and intranasally instilled with either 10 μL of sterile saline solution (0.9% NaCl, CTRL) or ROFA (0.2 μg in 10 μL of saline solution). Pulmonary mechanics, histology (normal and collapsed alveoli, mononuclear and polymorphonuclear cells, and ultrastructure), neutrophils (in blood and bronchoalveolar lavage fluid) were determined at 6 h in CTRL and at 6, 24, 48, 72, 96, and 120 h after ROFA exposure. ROFA contained metal elements, especially iron, polycyclic aromatic hydrocarbons (PAHs), and organochlorines. Lung resistive pressure augmented early (6 h) in the course of lung injury and other mechanical, histological and inflammatory parameters increased at 24 h, returning to control values at 120 h. Blood neutrophilia was present only at 24 and 48 h after exposure. Swelling of endothelial cells with adherent neutrophils was detected after ROFA instillation. No neutrophils were present in the lavage fluid. In conclusion, the exposure to ROFA, even in low doses, induced early changes in pulmonary mechanics, lung histology and accumulation of neutrophils in blood of mice that lasted for 4 days and disappeared spontaneously.

Acute cardiopulmonary effects induced by the inhalation of concentrated ambient particles during seasonal variation in the city of São Paulo

Ambient particles may undergo modifications to their chemical composition as a consequence of climatic variability. The determination of whether these changes modify the toxicity of the particles is important for the understanding of the health effects associated with particle exposure. The objectives were to determine whether low levels of particles promote cardiopulmonary effects, and to assess if the observed alterations are influenced by season. Mice were exposed to 200 μg/m3 concentrated ambient particles (CAPs) and filtered air (FA) in cold/dry and warm/humid periods. Lung hyperresponsiveness, heart rate, heart rate variability, and blood pressure were evaluated 30 min after each exposure. After 24 h, blood and tissue samples were collected. During both periods (warm/humid and cold/dry), CAPs induced alterations in red blood cells and lung inflammation. During the cold/dry period, CAPs reduced the mean corpuscular volume levels and increased erythrocytes, hemoglobin, mean corpuscular hemoglobin concentration, and red cell distribution width coefficient variation levels compared with the FA group. Similarly, CAPs during the warm/humid period decreased mean corpuscular volume levels and increased erythrocytes, hemoglobin, hematocrit, and red cell distribution width coefficient variation levels compared with the FA group. CAPs during the cold/dry period increased the influx of neutrophils in the alveolar parenchyma. Short-term exposure to low concentrations of CAPs elicited modest but significant pulmonary inflammation and, to a lesser extent, changes in blood parameters. In addition, our data support the concept that changes in climate conditions slightly modify particle toxicity because equivalent doses of CAPs in the cold/dry period produced a more exacerbated response.

Particulate matter disrupts human lung endothelial barrier integrity via ROS- and p38 MAPK-dependent pathways

Epidemiologic studies have linked exposure to airborne pollutant particulate matter (PM) with increased cardiopulmonary mortality and morbidity. The mechanisms of PM-mediated lung pathophysiology, however, remain unknown. We tested the hypothesis that PM, via enhanced oxidative stress, disrupts lung endothelial cell (EC) barrier integrity, thereby enhancing organ dysfunction. Using PM collected from Ft. McHenry Tunnel (Baltimore, MD), we assessed PM-mediated changes in transendothelial electrical resistance (TER) (a highly sensitive measure of barrier function), reactive oxygen species (ROS) generation, and p38 mitogen-activated protein kinase (MAPK) activation in human pulmonary artery EC. PM induced significant dose (10-100 microg/ml)- and time (0-10 h)-dependent EC barrier disruption reflected by reduced TER values. Exposure of human lung EC to PM resulted in significant ROS generation, which was directly involved in PM-mediated EC barrier dysfunction, as N-acetyl-cysteine (NAC, 5 mM) pretreatment abolished both ROS production and barrier disruption induced by PM. Furthermore, PM induced p38 MAPK activation and HSP27 phosphorylation, events that were both attenuated by NAC. In addition, PM-induced EC barrier disruption was partially prevented by the p38 MAP kinase inhibitor SB203580 (10 microM) as well as by reduced expression of either p38 MAPK beta or HSP27 (siRNA). These results demonstrate that PM induces ROS generation in human lung endothelium, resulting in oxidative stress-mediated EC barrier disruption via p38 MAPK- and HSP27-dependent pathways. These findings support a novel mechanism for PM-induced lung dysfunction and adverse cardiopulmonary outcomes.

Chronic nasal instillation of residual-oil fly ash (ROFA) induces brain lipid peroxidation and behavioral changes in rats

Several epidemiological studies have linked particulate matter exposure to numerous adverse health effects on the respiratory, cardiovascular, and reproductive systems (Braga et al., 1999; Zanobetti et al., 2000; Anderson et al., 2001; Farhat et al., 2005). More recently, ambient levels of black carbon were associated to impaired cognitive function in children (Suglia et al., 2008), suggesting that the central nervous system (CNS) may be a target of air pollutants. The present study was conducted to (a) determine whether chronic residual oil fly ash (ROFA) exposure promotes behavioral changes and lipid peroxidation in rat brain areas, and (b) determine whether N-acetylcysteine (NAC), a general antioxidant, prevents these effects. Forty-five-day-old male Wistar rats were exposed or not to ROFA by intranasal instillation and were treated or not with NAC (150 mg/kg) ip for 30 days. One day later, rats were submitted to the open field test to evaluate the motor/exploratory activities and emotionality followed by decapitation. Striatum and cerebellum were dissected to determine lipid peroxidation by the accumulation of thiobarbituric acid-reactive substances (TBARS). ROFA instillation induced an increase in lipid peroxidation level in striatum (p = .033) and cerebellum (p = .030), as compared with the control group. NAC treatment blocked these changes. ROFA promoted a decrease in the frequency of peripheral walking (p = .006) and a decrease in exploration (p = .001), which were not blocked by N-acetylcysteine. The present study provides evidence that toxic particles, administered by the respiratory route, induce oxidative stress in structures of the central nervous system, as well as behavioral alterations. The administration of NAC reduces lipid peroxidation at the striatum and cerebellum levels, but does not influence behavioral disturbances.

Ambient particulate matter exhibits direct inhibitory effects on oxidative stress enzymes

A primary mechanistic hypothesis by which ambient air particles have a significant negative impact on human health is via the induction of pulmonary inflammatory responses mediated through the generation of reactive oxygen species (ROS). Development of a biosensor for the assessment of particulate ROS activity would be a significant advance in air pollution monitoring. The objective of this study was to evaluate whether air particulates interact directly with protective enzymes involved in oxidative stress responses. We performed enzyme activity assays on four enzymes involved in oxidative stress responses (Cu/Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, and glutathione reductase) in the presence of particles of varying toxicities and found distinctive inhibition patterns. On the basis of these findings, we suggest a strategy for an enzyme bioassay that could be used to assess the potential of particles to generate ROS-induced responses.

Gene expression pattern in spontaneously hypertensive rats exposed to urban particulate matter (EHC-93)

Epidemiological studies show associations of short-term exposure to particulate matter with morbidity and mortality. Although many studies investigate the health effects of ambient particulate matter, the associated mechanisms, and the causality, they often focus on classical parameters. The objective of the present study was to gain insight into the roles of a wide range of genes in this process. Particular attention has been paid to immediate oxidative stress in the lung. We isolated total lung RNA from spontaneously hypertensive male rats 2-40 h after exposure to reference EHC-93 (10 mg/kg). Our results show that exposure to particulate matter generates a time-dependent pattern of gene expression. From the 8799 genes or expressed sequence tags tested, we see that 132 genes were up- or downregulated shortly after exposure (i.e., 2-6 h), whereas after 15-21 h and 24-40 h, 46 and 56 genes showed altered expression, respectively. Focusing on the earliest point, 99 of the 132 genes were identified as unique. They include genes involved in an oxidative stress response (hemeoxygenase-1, metallothioneins, and thioredoxin reductase), an inflammatory response macrophage inflammatory protein-2, and tumor necrosis factor alpha), transcription factors belonging to the activating protein-1 family, and genes involved in cardiovascular functions. The present study, although not representing an ambient situation, is used to identify the biological pathways implicated in the initial injury response to PM exposure. Using Affymetrix chips, this study shows time-dependent gene expression, it identifies many genes that can be affected by exposure to particulate matter, and it confirms the involvement of oxidative stress in particulate-matter-related effects.

Acute cardiopulmonary alterations induced by fine particulate matter of São Paulo, Brazil

The mechanisms involved in the association between air pollution and increased cardiovascular morbidity are not fully understood. The objective of this study was to test the hypothesis that fine particulate matter (PM(2.5)) induces systemic inflammation and vasoconstriction of small arteries in the lung and heart of rats. Thirty-eight healthy Wistar rats were anesthetized, intubated, and submitted to the instillation of 1 ml of distilled water diluted in the following solution: blank filter, 100 microg and 500 microg of PM(2.5). PM(2.5) was collected in glass fiber filters with a high-volume sampler. The animals were sacrificed 24 h after instillation when blood, heart, and lung samples were collected for morphological and wet-to-dry weight ratio analysis. PM(2.5) consisted of the following elements: sulphur, arsenic, bromine, chlorine, cobalt, iron, lanthanum, manganese, antimony, scandium, and thorium. Total reticulocytes significantly increased at both PM(2.5) doses (p < 0.05) while hematocrit levels increased in the 500 microg group (p < 0.05). Quantification of segmented neutrophils and fibrinogen levels showed a significant decrease, while lymphocytes counting increased with 100 microg of PM(2.5) (p < 0.05). A significant dose-dependent decrease of intra-acinar pulmonary arteriole lumen/wall ratio (L/W) was observed in PM groups (p < 0.001). Peribronchiolar arterioles L/W showed a significant decrease in the 500 microg group (p < 0.001). A significant increase in heart wet-to-dry weight ratio was observed in the 500 microg group (p < 0.001). In conclusion, fine environment particles in the city of São Paulo promote pulmonary and cardiac histological alterations. Pulmonary vasculature was markedly affected by particle instillation, resulting in significant vasoconstriction in healthy rats.

Respiratory function among waste incinerator workers

INTRODUCTION

Whereas air pollutants have been measured in incinerator working areas, few studies have focused on the effects of these pollutants on the lung function of incinerator workers. In France, a study was performed among workers at two urban incinerators, aimed at identifying a link between exposure to different pollutants in incinerator plants and respiratory lung function impairments.

METHODS

A follow-up of lung function was carried out on 83 incinerator workers from two incinerator plants, comparing them with a group of 76 non-exposed workers recruited by the same occupational physician. Workers' lung functions were measured during their yearly occupational medical examination, for 3 years. The American Thoracic Society quality criteria were used to control the quality of the flow-volume curves.

RESULTS

Base-line lung functions were lower among incinerator workers than among non-exposed workers. The few significant differences were indicative of obstructive symptoms. During the first year the differences observed between the two groups were close to the significant threshold value of 5% for FEF(75)/ PV and FEF(25-75)/PV. During the third year significant differences covered three parameters: FEF(50)/PV, FEF(25-75)/PV and FEF(25-75)/FVC. After smoking habits (pack-years), medical history of allergy or lung diseases and the examination centres had been taken into account in a linear regression, the reduction of FEF(75)/PV in the first year and FEF(25-75)/FVC in the third year was linked to exposure in incinerator plants. There was no significant association between exposure and the differences observed in the FEF(25-75)/PV in the first year or in the FEF(50)/PV and the FEF(25-75)/PV in the third year.

CONCLUSION

This analysis of incinerator workers' lung functions has identified some lung impairments among workers exposed to incinerator air pollutants compared to non-exposed workers, thus indicating possible obstructive disorders among incinerator workers. However, these impairments are moderate and in accordance with the low levels of airborne pollutants identified in a previous study.