Pirouz Shirali

Genotoxic potential of Polycyclic Aromatic Hydrocarbons-coated onto airborne Particulate Matter (PM2.5) in human lung epithelial A549 cells

To improve the knowledge of the underlying mechanisms of action involved in air pollution Particulate Matter (PM)-induced toxicity in human lungs, with a particular interest of the crucial role played by coated-organic chemicals, we were interested in the metabolic activation of Polycyclic Aromatic Hydrocarbons (PAH)-coated onto air pollution PM, and, thereafter, the formation of PAH-DNA adducts in a human lung epithelial cell model (A549 cell line). Cells were exposed to Dunkerque citys PM(2.5) at its Lethal Concentrations at 10% and 50% (i.e. LC(10)=23.72 microg/mL or 6.33 microg/cm2, and LC(50)=118.60 microg/mL or 31.63 microg/cm2), and the study of Cytochrome P450 (CYP) 1A1 gene expression (i.e. RT-PCR) and protein activity (i.e. EROD activity), and the formation of PAH-DNA adducts (i.e. 32P-postlabeling), were investigated after 24, 48, and/or 72 h. PAH, PolyChlorinated Dibenzo-p-Dioxins and -Furans (PCDD/F), Dioxin-Like PolyChlorinated Biphenyls (DLPCB), and PolyChlorinated Biphenyls (PCB)-coated onto collected PM were determined (i.e. GC/MS and HRGC/HRMS, respectively), Negative (i.e. TiO2 or desorbed PM, dPM; EqLC10=19.42 microg/mL or 5.18 microg/cm2, and EqLC50=97.13 microg/mL or 25.90 microg/cm2), and positive (i.e. benzo(a)pyrene; 1 microM) controls were included in the experimental design. Statistically significant increases of CYP1A1 gene expression and protein activity were observed in A549 cells, 24, 48 and 72 h after their exposure to dPM, suggesting thereby that the employed outgassing method was not efficient enough to remove total PAH. Both the CYP1A1 gene expression and EROD activity were highly induced 24, 48 and 72 h after cell exposure to PM. However, only very low levels of PAH-DNA adducts, also not reliably quantifiable, were reported 72 h after cell exposure to dPM, and, particularly, PM. The relatively low levels of PAH together with the presence of PCDD/F, DLPCB, and PCB-coated onto Dunkerque Citys PM 2.5 could notably contribute to explain the borderline detection of PAH-DNA adducts in dPM and/or PM-exposed A549 cells. Hence, remaining very low doses of PAH in dPM or relatively low doses of PAH-coated onto PM were involved in enzymatic induction, a key feature in PAH-toxicity, but failed to show a clear genotoxicity in this in vitro study. We also concluded that, in the human lung epithelial cell model we used, and in the experimental conditions we chose, bulky-DNA adduct formation was apparently not a major factor involved in the Dunkerque Citys PM 2.5-induced toxicity.

Biologic markers of oxidative stress and nephrotoxicity as studied in biomonitoring of adverse effects of occupational exposure to lead and cadmium

Objectives: In this work, we studied impregnation levels of workers occupationally exposed to lead (Pb) and cadmium (Cd), usefulness of early urinary markers of nephrotoxicity, and occurrence of oxidative stress as the underlying mechanism involved in Pb- or Cd-induced adverse effects. Thirty-five men were recruited from a nonferrous metal smelter. Pb and Cd in blood (B-Pb, B-Cd) and urine (U-Pb, U-Cd) were measured. Relations between oxidative stress markers (malondialdehyde, superoxide dismutase, glutathione peroxidase, selenium, glutathione reductase, glutathione status, 8-hydroxy-2′-deoxyguanosine) and exposure levels, on the one hand, and early urinary markers (alpha-1-microprotein, beta-2-microglobulin, retinol binding protein, alpha and pi-glutathione S-transferases) and exposure levels, on the other hand, were evaluated. Results: Mean exposure levels were moderate (B-Pb = 395.71 &mgr;g Pb/L; U-Pb = 95.19 &mgr;g Pb/g creatinine; B-Cd = 5.83 &mgr;g Cd/L; U-Cd = 4.67 &mgr;g Cd/g creatinine). Changes in malondialdehyde, glutathione status, 8-hydroxy-2′-deoxyguanosine, and alpha-glutathione S-transferases were closely correlated with exposure levels and did not depend on tobacco consumption. We showed that these workers showed moderate Pb and Cd exposure levels. Conclusions: Taken together, the data suggests the use of alpha-glutathione S-transferases excretion in urine as a hallmark of early changes in the proximal tubular integrity that could later lead to clinical disease if exposure is not reduced.

Relationship between physicochemical characterization and toxicity of fine particulate matter (PM2.5) collected in Dakar city (Senegal).

The massive increase in emissions of air pollutants due to economic and industrial growth in developing countries has made air quality a crucial health problem in this continent. Hence, it is somewhat critical to have a better knowledge on the air pollution in Sub-Saharan Africa countries. Three air pollution PM2.5 samples were also collected in two urban sites (i.e., Fann and Faidherbe) in Dakar (Senegal) and in a rural site near Dakar (i.e., Ngaparu). The two urban sites mainly differ in the type of used vehicles: in Fann, most of the traffic is made of buses, which are absent, in Faidherbe. The physicochemical characteristics of the three PM2.5 samples revealed their high heterogeneities and complexities, related to the multiple natural and anthropogenic emission sources. Results from 5-bromodeoxyuridine incorporation into DNA, mitochondrial dehydrogenase activity, and extracellular lactate dehydrogenase activity in PM2.5-exposed BEAS-2B cells suggested the exposure conditions (i.e., 3 and 12 μg PM/cm² during 24, 48, and 72 h) to further consider. The organic fractions (i.e., mainly PAHs) of the PM(2.5) samples were able to induce a time and/or concentration-dependent gene expression of CYP1A1 and CYP1B1, and, to a lesser extent, NQO1. There was a time and/or dose-dependent increase of both the gene expression and/or protein secretion of inflammatory mediators (i.e., TNF-α, IL-1β, IL-6, and/or IL-8) in PM(2.5)-exposed BEAS-2B cells. In agreement with the physicochemical characterization, urban PM(2.5) samples caused greater biological responses in BEAS-2B cells than the rural one. Variable concentrations of transition metals (i.e., Fe, Al, Pb, Mn, Zn) and organic compounds (i.e., PAHs) founded in the three PM2.5 samples might be firmly involved in a time- and/or dose-dependent toxicity, relying on inflammatory processes.

Air pollution particulate matter (PM2.5)-induced gene expression of volatile organic compound and/or polycyclic aromatic hydrocarbon-metabolizing enzymes in an in vitro coculture lung model

The overarching goals were: (i) to develop an in vitro coculture model, including two relevant lung target cells: human alveolar macrophage (AM) isolated from bronchoalveolar lavage fluid, and immortalized cells originated from the normal lung tissue of a human embryo (L132 cell line), as a future strategy for near-realistic exposures to air pollution particulate matter (PM), and (ii) to study the gene expression of volatile organic compound (VOC) and/or polycyclic aromatic hydrocarbons (PAH)-metabolizing enzymes in this in vitro coculture model. Human AM and/or L132 cells in mono- and coculture were exposed for 24, 48 and 72h to Dunkerque Citys PM2.5 at its lethal concentrations at 10% and 50% (i.e. AM: LC10=14.93 microgPM/mL and LC50=74.63 microgPM/mL; L132: LC10=18.84 microgPM/mL and LC50=75.36 microgPM/mL), and the gene expression (i.e. Cytochrome P450 1A1, CYP1A1; CYP2E1; CYP2F1; microsomal Epoxide Hydrolase; NADPH Quinone Oxydo-Reductase-1, NQO1; and Glutathione S-Transferase pi-1 and mu-3, GST-pi1 and GST-mu3) was studied. In human AM in mono- and coculture, and in L132 cells in monoculture, VOC and/or PAH-coated onto PM induced the gene expression of CYP1A1, CYP2E1, NQO1, GST-pi1, and/or GST-mu3. However, there were quiet different outcomes based on the use of L132 cells in mono- vs. coculture: the pattern of VOC and/or PAH-metabolizing enzymes induced by PM in L132 cells in monoculture remained almost unaffected when in coculture with AM. Taken together, these results reinforced the key role of PM-exposed target human AM in the defenses of the human lung from external injuries, notably through their higher capacity to retain PM, and indicated that carbonaceous cores of PM, as physical vector of the penetration and retention of coated-VOC and/or PAH into cells, enabled them to exert a longer toxicity. The use of such a near realistic exposure system could also be a very useful and powerful tool to identify the mechanisms by which air pollution PM induced adverse health effects.

Pulmonary induction of proinflammatory mediators following the rat exposure to benzo(a)pyrene-coated onto Fe2O3 particles.

Epidemiological evidence firmly implicated an interactive effect between Fe2O3 and benzo(a)pyrene (B(a)P) in causing lung cancer. However, despite intensive investigation, the mechanism involved is not precisely established. Since the accumulation of reactive oxygen intermediates (ROI)-mediated damage and/or immune-induced injury might be a possible cause of lung cancer, we studied the oxidative and the inflammatory effects of Fe2O3 (3 mg), B(a)P (3 mg) or B(a)P (3 mg)-coated onto Fe2O3 (3 mg) particles on this relevant organ target in Sprague-Dawley rats. We investigated lipid peroxidation (malondialdehyde; MDA) and secretion of some inflammatory mediators (tumor necrosis factor-alpha, TNF-alpha; interleukin-1 beta, IL-1beta; nitric oxide, NO) in lungs. In addition, mRNA expressions of TNF-alpha, IL-1beta and inducible nitric oxide synthase (iNOS) were evaluated. Our results show that exposure to Fe2O3 and B(a)P, alone or in association, induced 2-fold increases in MDA production suggesting thereby oxidative stress conditions (P<0.01). Exposure to Fe2O3, B(a)P or B(a)P-coated onto Fe2O3 particles significantly increased both mRNA expression and/or synthesis of inflammatory mediators. The main findings of this work were that the association of Fe2O3 and B(a)P induces more pronounced induction of inflammatory mediators (IL-1beta secretion, P<0.01; IL-1beta mRNA expression, P<0.01; iNOS mRNA expression, P<0.05) than B(a)P by itself. Hence, our results may explain why concurrent exposure to Fe2O3 and B(a)P is more deleterious in lungs than exposure to B(a)P alone.

Influence of fly ash aided phytostabilisation of Pb, Cd and Zn highly contaminated soils on Lolium perenne and Trifolium repens metal transfer and physiological stress

Due to anthropogenic activities, large extends of soils are highly contaminated by Metal Trace Element (MTE). Aided phytostabilisation aims to establish a vegetation cover in order to promote in situ immobilisation of trace elements by combining the use of metal-tolerant plants and inexpensive mineral or organic soil amendments. Eight years after Coal Fly Ash (CFA) soil amendment, MTE bioavailability and uptake by two plants, Lolium perenne and Trifolium repens, were evaluated, as some biological markers reflecting physiological stress. Results showed that the two plant species under study were suitable to reduce the mobility and the availability of these elements. Moreover, the plant growth was better on CFA amended MTE-contaminated soils, and the plant sensitivity to MTE-induced physiological stress, as studied through photosynthetic pigment contents and oxidative damage was lower or similar. In conclusion, these results supported the usefulness of aided phytostabilisation of MTE-highly contaminated soils.

Temporal-spatial variations of the physicochemical characteristics of air pollution Particulate Matter (PM2.5-0.3) and toxicological effects in human bronchial epithelial cells (BEAS-2B).

While the evidence for the health adverse effects of air pollution Particulate Matter (PM) has been growing, there is still uncertainty as to which constituents within PM are most harmful. Hence, to contribute to fulfill this gap of knowledge, some physicochemical characteristics and toxicological endpoints (i.e. cytotoxicity, oxidative damage, cytokine secretion) of PM2.5-0.3 samples produced during two different seasons (i.e. spring/summer or autumn/winter) in three different surroundings (i.e. rural, urban, or industrial) were studied, thereby expecting to differentiate their respective adverse effects in human bronchial epithelial cells (BEAS-2B). Physicochemical characteristics were closely related to respective origins and seasons of the six PM2.5-0.3 samples, highlighting the respective contributions of industrial and heavy motor vehicle traffic sources. Space- and season-dependent differences in cytotoxicity of the six PM2.5-0.3 samples could only be supported by considering both the physicochemical properties and the variance in air PM concentrations. Whatever spaces and seasons, dose- and even time-dependent increases in oxidative damage and cytokine secretion were reported in PM2.5-0.3-exposed BEAS-2B cells. However, the relationship between the chemical composition of each of the six PM2.5-0.3 samples and their oxidative or inflammatory potentials seemed to be very complex. These results supported the role of inorganic, ionic and organic components as exogenous source of Reactive Oxygen Species and, thereafter, cytokine secretion. Nevertheless, one of the most striking observation was that some inorganic, ionic and organic chemical components were preferentially associated with early oxidative events whereas others in the later oxidative damage and/or cytokine secretion. Taken together, these results indicated that PM mass concentration alone might not be able to explain the health outcomes, because PM is chemically nonspecific, and supported growing evidence that PM-size, composition and emission source, together with sampling season, interact in a complex manner to produce PM2.5-0.3-induced human adverse health effects.

Antioxidant defense disruption by polycyclic aromatic hydrocarbons-coated onto Fe2O3 particles in human lung cells (A549)

We addressed the hypothesis that in vitro short-term exposure to hematite (Fe(2)O(3)) and polycyclic aromatic hydrocarbons (PAHs) is more deleterious by virtue of their combinations being able to cause higher oxidative stress conditions in human lung cells (A549), than either chemical alone. Lipid peroxidation (malondialdehyde; MDA), antioxidant enzyme activities (superoxide dismutase; SOD, glutathione peroxidase; GPx, glutathione reductase; GR), glutathione status (reduced glutathione; GSH, oxidized glutathione; GSSG) and alpha-tocopherol (alpha-Toc) consumption were studied in cells exposed to Fe(2)O(3), benzo(a)pyrene (B(a)P) or pyrene, alone or in association. We found that increases in GSSG/GSH (P<0.01) and in alpha-Toc consumption (P<0.01) counteracted Fe(2)O(3)-induced lipid peroxidation. Exposure to B(a)P did not induce oxidative injury because of the involvement of non-enzymatic antioxidants in cell homeostasis. Pyrene did not induce free radicals (FR)-induced injury. Exposure to PAHs-coated onto Fe(2)O(3) particles damaged both the enzymatic (i.e. increases in SOD and GR activities; P<0.01) and the non-enzymatic (i.e. increases in GSSG/GSH; P<0.001, alpha-Toc consumption; P<0.01) antioxidant defenses, thereby allowing lipid peroxidation (i.e. MDA production; P<0.05). Exposure to PAHs-coated onto Fe(2)O(3) particles induced not only higher lipid peroxidation (i.e. MDA production; P<0.05) but also higher antioxidant alterations (i.e. SOD and GR activities; P<0.05, GSSH/GSH; P<0.01 or P<0.05) than either chemical alone. Several mechanisms could account for this result, enhanced uptake of Fe(2)O(3) and/or greater availability of PAHs. Hence, our results indicate that exposure to PAHs-coated onto Fe(2)O(3) particles is more deleterious in lungs than either chemical alone.

Polycyclic aromatic hydrocarbons within airborne particulate matter (PM2.5) produced DNA bulky stable adducts in a human lung cell coculture model

To extend current knowledge on the underlying mechanisms of air pollution particulate matter (PM2.5)‐induced human lung toxicity, the metabolic activation of polycyclic aromatic hydrocarbons (PAH) within PM2.5 and PAH–DNA bulky stable adduct patterns in human alveolar macrophage (AM) and/or human lung epithelial L132 cells in mono‐ and cocultures were studied. In the coculture system, only human AM were exposed to air pollution PM2.5, unlike L132 cells. Particles, inorganic fraction and positive controls [i.e. TiO2, thermally desorbed PM (dPM) and benzo[a]pyrene, B[a]P, respectively] were included in the experimental design. Cytochrome P450 (CYP) 1A1 gene expression, CYP1A1 catalytic activity and PAH–DNA bulky stable adducts were studied after 24, 48 and/or 72 h. Relatively low doses of PAH within PM2.5 induced CYP1A1 gene expression and CYP1A1 catalytic activity in human AM and, thereafter, PAH–DNA bulky stable adduct formation. Adduct spots in PM2.5‐exposed human AM were higher than those in dPM‐exposed ones, thereby showing the incomplete removal of PAH by thermal desorption. PAH within air pollution PM2.5 induced CYP1A1 gene expression but not CYP1A1 catalytic activity in L132 cells. However, despite the absence of PAH–DNA bulky stable adduct in L132 cells from human AM/L132 cell cocultures exposed to dPM2.5 or PM2.5, reliable quantifiable PAH–DNA bulky stable adducts were observed in L132 cells from human AM/L132 cell coculture exposed to B[a]P. Taken together, these results support the exertion of genotoxicity of highly reactive B[a]P‐derived metabolites produced within human AM not only in primary target human AM, but also in secondary target L132 cells. Copyright

Assessment of fly ash-aided phytostabilisation of highly contaminated soils after an 8-year field trial Part 2. Influence on plants

Aided phytostabilisation is a cost-efficient technique to manage metal-contaminated areas, particularly in the presence of extensive pollution. Plant establishment and survival in highly metal-contaminated soils are crucial for phytostabilisation success, as metal toxicity for plants is widely reported. A relevant phytostabilisation solution must limit metal transfer through the food chain. Therefore, this study aimed at evaluating the long-term efficiency of aided phytostabilisation on former agricultural soils highly contaminated by cadmium, lead, and zinc. The influence of afforestation and fly ash amendments on reducing metal phytoavailability was investigated as were their effects on plant development. Before being planted with a tree mix, the site was divided into three plots: a reference plot with no amendment, a plot amended with silico-aluminous fly ash and one with sulfo-calcic fly ash. Unlike Salix alba and Quercus robur, Alnus glutinosa, Acer pseudoplatanus and Robinia pseudoacacia grew well on the site and accumulated, overall, quite low concentrations of metals in their leaves and young twigs. This suggests that these three species have an excluder phenotype for Cd, Zn and Pb. After 8 years, metal availability to A. glutinosa, A. pseudoplatanus and R. pseudoacacia, and translocation to their above-ground parts, strongly decreased in fly ash-amended soils. Such decreases fit well together with the depletion of CaCl(2)-extractable metals in amended soils. Although both fly ashes were effective to decrease Cd, Pb and Zn concentrations in above-ground parts of trees, the sulfo-calcic ash was more efficient.