Differential elemental distribution of retained particles along the respiratory tract

Association of pulmonary black carbon accumulation with cardiac fibrosis in residents of Sao Paulo, Brazil

Evidence suggests that myocardial interstitial fibrosis, resulting from cardiac remodeling, may possibly be influenced by mechanisms activated through the inhalation of airborne pollutants. However, limited studies have explored the relationship between lifetime exposure to carbon-based particles and cardiac fibrosis, specially using post-mortem samples. This study examined whether long-term exposure to air pollution (estimated by black carbon accumulated in the lungs) is associated with myocardial fibrosis in urban dwellers of megacity of Sao Paulo. Data collection included epidemiological and autopsy-based approaches. Information was obtained by interviewing the next of kin and through the pathologist's report. The individual index of exposure to carbon-based particles, which we designed as the fraction of black carbon (FBC), was estimated through quantification of particles on the macroscopic lung surface. Myocardium samples were collected for histopathological analysis to evaluate the fraction of cardiac fibrosis. The association between cardiac fibrosis and FBC, age, sex, smoking status and hypertension was assessed by means of multiple linear regression models. Our study demonstrated that the association of FBC with cardiac fibrosis is influenced by smoking status and hypertension. Among hypertensive individuals, the cardiac fibrosis fraction tended to increase with the increase of the FBC in both groups of smokers and non-smokers. In non-hypertensive individuals, the association between cardiac fibrosis fraction and FBC was observed primarily in smokers. Long-term exposure to tobacco smoke and environmental particles may contribute to the cardiac remodeling response in individuals with pre-existing hypertension. This highlights the importance of considering hypertension as an additional risk factor for the health effects of air pollution on the cardiovascular system. Moreover, the study endorses the role of autopsy to investigate the effects of urban environment and personal habits in determining human disease.

Pleural anthracosis as an indicator of lifetime exposure to urban air pollution: An autopsy-based study in Sao Paulo

Many studies have been conducted to evaluate the association between air pollution and adverse health effects using a wide variety of methods to assess exposure. However, the assessment of individual long-term exposure to ambient air pollution is a challenging task and has not been evaluated in a large autopsy study. Our goal was to investigate whether exposure to urban air pollution is associated to the degree of lung anthracosis, considering modifying factors such as personal habits, mobility patterns and occupational activities. We conducted a study in Sao Paulo, Brazil from February 2017 to June 2018, combining epidemiological, spatial analysis and autopsy-based approaches. Information about residential address, socio-demographic details, occupation, smoking status, time of residence in the city and time spent commuting was collected via questionnaires applied to the next-of-kin. Images of the pleura surface from upper and lower lobes were used to quantify anthracosis in the lungs. We used multiple regression models to assess the association between the amount of carbon deposits in human lungs, measured by the fraction of pleural anthracosis (FA), and potential explanatory variables. We analyzed 413 cases and our data showed that for each additional hour spent in daily commuting, the ratio FA/(1-FA) is multiplied by 1.05 (95% confidence interval: [1.02; 1.08]). The estimated coefficient for daily hours spent in traffic was not considerably affected by the inclusion of socio-demographic variables and smoking habits. We estimate a tobacco equivalent dose of 5 cigarettes per day in a city where annual PM_2.5 concentration oscillates around 25 μg/m³. Pleural anthracosis is a potential index of lifetime exposure to traffic-derived air pollution.

Identification of Foreign Particles in Human Tissues Using Raman Microscopy

The goal of this study was to precisely and unambiguously identify foreign particles in human tissues using a combination of polarized light microscopy and Raman microscopy, which provides chemical composition and microstructural characterization of complex materials with submicrometer spatial resolution. This identification for patient care and research has been traditionally studied using polarized light microscopy, electron microscopy with X-ray analysis, and electron diffraction, all with some limitations. We designed a model system of stained and unstained cells that contained birefringent talc particles and systematically investigated the influence of slide and coverslip materials, laser wavelengths, and mounting media on the Raman spectra obtained. Hematoxylin and eosin stained slides did not produce useful results because of fluorescence interference from the stains. Unstained cell samples prepared with standard slides and coverslips produce high quality Raman spectra when excited at 532 nm; the spectra are uniquely assigned to talc. We also obtain high quality Raman spectra specific for talc in unstained tissue samples (pleural tissue following talc pleurodesis and ovarian tissue following long-term perineal talc exposure). Raman microscopy is sufficiently sensitive and compositionally selective to identify particles as small as one micrometer in diameter. Raman spectra have been catalogued for thousands of substances, which suggests that this approach is likely to be successful in identifying other particles of interest in tissues, potentially making Raman microscopy a powerful new tool in pathology.

Association between Traffic Air Pollution and Reduced Forced Vital Capacity: A Study Using Personal Monitors for Outdoor Workers

Background

The effects of outdoor air pollution on lung function in adults are still controversial.

Objective

Evaluate the effects of exposure to different levels of traffic-generated PM_2.5 on workers’ lung functions in São Paulo, Brazil.

Methods

To cover a wide range of exposures, 101 non-smoking workers from three occupations (taxi drivers, traffic controllers, and forest rangers) were selected for the study. After clinical evaluation, the participants were scheduled to attend four consecutive weekly visits in which they received a 24-hour personal PM_2.5 sampler and had lung function tests measured on the following day. The association between the spirometric variables and the averaged PM_2.5 levels was assessed using robust regression models adjusted for age, waist circumference, time at the job, daily work hours, diabetes or hypertension and former smoking habits.

Results

Relative to workers in the lowest exposed group (all measures < 25 μg/m³), those with the highest level of exposure (all measures > 39.6 μg/m³) showed a reduction of predicted FVC (-12.2%; CI 95%: [-20.0% to -4.4%]), a marginal reduction of predicted FEV₁ (-9.1%; CI 95%: [-19.1% to 0.9%]) and an increase of predicted FEF_25-75%/FVC (14.9%; CI 95%: [2.9% to 26.8%]) without changes of FEV₁/FVC.

Conclusions

Exposure to vehicular traffic air pollution is associated with a small but significant reduction of FVC without a reduction of FEV₁/FVC.

The oxidative potential of differently charged silver and gold nanoparticles on three human lung epithelial cell types

BACKGROUND

Nanoparticle (NPs) functionalization has been shown to affect their cellular toxicity. To study this, differently functionalized silver (Ag) and gold (Au) NPs were synthesised, characterised and tested using lung epithelial cell systems.

METHODS

Monodispersed Ag and Au NPs with a size range of 7 to 10 nm were coated with either sodium citrate or chitosan resulting in surface charges from -50 mV to +70 mV. NP-induced cytotoxicity and oxidative stress were determined using A549 cells, BEAS-2B cells and primary lung epithelial cells (NHBE cells). TEER measurements and immunofluorescence staining of tight junctions were performed to test the growth characteristics of the cells. Cytotoxicity was measured by means of the CellTiter-Blue ® and the lactate dehydrogenase assay and cellular and cell-free reactive oxygen species (ROS) production was measured using the DCFH-DA assay.

RESULTS

Different growth characteristics were shown in the three cell types used. A549 cells grew into a confluent mono-layer, BEAS-2B cells grew into a multilayer and NHBE cells did not form a confluent layer. A549 cells were least susceptible towards NPs, irrespective of the NP functionalization. Cytotoxicity in BEAS-2B cells increased when exposed to high positive charged (+65-75 mV) Au NPs. The greatest cytotoxicity was observed in NHBE cells, where both Ag and Au NPs with a charge above +40 mV induced cytotoxicity. ROS production was most prominent in A549 cells where Au NPs (+65-75 mV) induced the highest amount of ROS. In addition, cell-free ROS measurements showed a significant increase in ROS production with an increase in chitosan coating.

CONCLUSIONS

Chitosan functionalization of NPs, with resultant high surface charges plays an important role in NP-toxicity. Au NPs, which have been shown to be inert and often non-cytotoxic, can become toxic upon coating with certain charged molecules. Notably, these effects are dependent on the core material of the particle, the cell type used for testing and the growth characteristics of these cell culture model systems.