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Title: The influence of particulate matter nanoparticles on bronchial epithelium and vascular endothelium - new mechanisms of adverse health effects of industrial air pollution

Abstract:

Particulate matter with an aerodynamic diameter of less than 2.5 µm, i.e. PM2.5, are considered to be the most toxic components of air pollution. They contain a fraction of nanoparticles (NPs), i.e. particles with a diameter less than 0.1 µm, which can enter the circulation through bronchial epithelium and alveoli. Epidemiological and experimental studies strongly indicate that PM2.5 have harmful effects on human health and are associated with an increased prevalence of respiratory and cardiovascular diseases. Nevertheless, the exact mechanisms of PM2.5 biological actions are still unclear.The aim of the study was to assess the potential toxicity of the real particulate matter and selected nanoparticles on human bronchial epithelium and vascular endothelium. PM2.5 were collected in Krakow during the winter months of 2010 and 2011, near a road with heavy traffic and at a location 1 km away from heavy traffic. Elemental composition and polycyclic aromatic hydrocarbon (PAHs) content was assessed in both samples. Cytotoxicity of PM2.5 and their organic extracts was examined by testing the viability and genomic response in three-dimensional cultures of normal human bronchial epithelium (EpiAirway) and human umbilical vein endothelial cells (HUVEC). In addition, the bioreactivity of zinc oxide (ZnO), silicon oxide (SiO2) in crystalline and amorphous forms, carbon black (CB) and nickel (Ni) NPs, the smallest size fraction of a PM2.5 metric, was estimated. To accomplish this, zeta potential was measured, the degree of plasmid DNA damage was assessed, hemolytic properties were determined, as well as the effect of NPs on vascular endothelial cell motility was examined.Elements associated with individual heating houses (Al, Fe, Zn, Pb, K, P) and adaptation of roads for winter use (Na, Si, Ca, Mg) were found in PM2.5 near and away from heavily trafficked road, yet in different proportions. Moreover, a presence of benzo[a]pyrene in concentration exceeding limit values, and 12 other PAHs, which originated from traffic and households emissions, was confirmed. Differences in chemical composition of PM2.5 samples from both locations significantly affected a degree of cytotoxicity in the three-dimensional cultures of bronchial epithelium. Histopathological analysis revealed the presence of numerous vacuoles deforming the pseudo-stratified structure of the tissue and cytolysis at the highest used concentration 180 μg/cm2. Disturbed integrity of the bronchial epithelium was also confirmed by measuring a trans-epithelial electrical resistance. Analysis of gene expression associated with oxidative stress showed that the four-hour incubation of bronchial epithelium with PM2.5 particles from both sites, at a dose 20 μg/cm2, and the corresponding quantities of organic extracts, induced increased expression of cp1a1 gene, which encoded a cytochrome P450 involved in phase I xenobiotic biotransformation. Interestingly, PM2.5 collected away from the busy road was more bioreactive, as it also up-regulated 10 genes encoding proteins associated with inflammation and apoptosis: transcription factor NFκB, interleukins (IL-1α, IL-1β), protein p21, factor CDK, and 5 heat shock proteins HSP. While the organic fraction of the sample caused increased expression of genes encoding XRCC2 protein, which is involved in the repair of damaged DNA, inducible nitric oxide synthase (iNOS) and tumor necrosis factor α (TNF-α). The large difference in bioreactivity of PM2.5 collected at sites remote from each other only 1 km most probably stemmed from the different inorganic compositions, as the analysis of PAHs in both samples did not show significant differences in the content of individual hydrocarbons. Elements absent or present in trace quantities in the air near a busy road in the first collection period were P, Zn and Fe. In particular, transition metals such as Fe and Zn may have contributed to the formation of free radicals and promoted inflammation. ; No increase in the expression of any of the analyzed genes was detected in endothelial cells exposed to PM2.5 collected near a busy road at concentration of 15 μg/cm2. In contrast, the organic fraction obtained from the PM2.5 up-regulated genes involved in repair of damaged endothelial cells: fibronectin 1 (FN1) receptor 2 vascular endothelial growth factor (VEGFR-2), von Willebrand factor, and metalloproteinase 2 (MMP-2). These findings were suggestive of a low-grade cell injury, as 4 hours after dosing mainly genes responsible for vascular endothelium repair were detected. A similar response was observed in case of ZnO NPs at a concentration of 5 μg/cm2, which up-regulated FN1, cell adhesion molecule ICAM-1, ADAM17 glycoprotein, which stimulated the release of L-selectin and TNFAPI3 protein involved in the reduction of inflammation.The degree of cytotoxicity of individual NPs depended on both the NP type and the used test. The most toxic to vascular endothelial cells, ZnO NPs induced a dose dependent decrease in cell viability and motility. In case of CB NPs and amorphous form of SiO2 no significant apoptosis was detected; although a significant decrease in cell proliferation in the following days of exposure was observed. The disturbance of proper endothelial function was probable due to accumulation of NPs inside cells. Ni and ZnO NPs with positive zeta potential caused the highest percentage of damage to plasmid DNA, whereas both forms of negatively charged SiO2 NPs elicited minimal bioreactivity. Interestingly, ZnO NPs exerted DNA damage at one hundred times lower dose than the other tested NPs. Hemolytic activity was observed only in case of SiO2 NPs, especially the amorphous form. It was also demonstrated that all NPs, once in solutions, underwent aggregation and showed an instable dispersion.In summary, the results confirmed bioreactivity of airborne particles, which was demonstrated by up-regulation of genes involved in inflammation and repair processes in both the bronchial epithelium and vascular endothelial cells. It was also shown that the same concentration of PM2.5 collected in different places produced various degrees of cytotoxicity, which strongly depended on chemical composition of particles. Experiments on different types of NPs showed that despite no immediate decrease in cell viability, NPs were able to affect normal cell function, including migration activity. Further studies are needed to elucidate various mechanisms underlying harmful effects of PM2.5 on human health.

Place of publishing:

Kraków

Level of degree:

2 - studia doktoranckie

Degree discipline:

biochemia ; choroby układu krążenia ; pulmonologia

Degree grantor:

Uniwersytet Jagielloński. Collegium Medicum. Wydział Lekarski.

Promoter:

Anetta Undas

Date issued:

2005

Format:

application/pdf

Identifier:

oai:dl.cm-uj.krakow.pl:3461

Call number:

ZB-117134

ControlNumberVIRTUA:

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Language:

pol

Access rights:

tylko w bibliotece

Location of original object:

Biblioteka Medyczna Uniwersytetu Jagiellońskiego- Collegium Medicum

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Last modified:

May 24, 2021

In our library since:

Mar 7, 2013

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ZB-117134 May 24, 2021
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