Physico-chemical characterization and in vitro inflammatory and oxidative potency of atmospheric particles collected in Dakar city's (Senegal)

Oxidative stress response in pulmonary cells exposed to different fractions of PM2.5-0.3 from urban, traffic and industrial sites

The aim of this work was to study the relationship between oxidative stress damages and particulate matter (PM) chemical composition, sources, and PM fractions. PM_2.5-0.3 (PM with equivalent aerodynamic diameter between 2.5 and 0.3 μm) were collected at urban, road traffic and industrial sites in the North of France, and were characterized for major and minor chemical species. Four different fractions (whole PM_2.5-0.3, organic, water-soluble and non-extractable matter) were considered for each of the PM_2.5-0.3 samples from the three sites. After exposure of BEAS-2B cells to the four different fractions, oxidative stress was studied in cells by quantifying reactive oxygen species (ROS) accumulation, oxidative damage to proteins (carbonylated proteins), membrane alteration (8-isoprostane) and DNA damages (8-OHdG). Whole PM_2.5-0.3 was capable of inducing ROS overproduction and caused damage to proteins at higher levels than other fractions. Stronger cell membrane and DNA damages were found associated with PM and organic fractions from the urban site. ROS overproduction was correlated with level of expression of carbonylated proteins, DNA damages and membrane alteration markers. The PM_2.5-0.3 collected under industrial influence appears to be the less linked to cell damages and ROS production in comparison with the other influences.

Cytotoxicity of Particulate Matter PM10 Samples from Ouagadougou, Burkina Faso

Particulate matter (PM) is one of the main air pollutants with 257,000 deaths per year in Africa. Studying their toxic mechanisms of action could provide a better understanding of their effects on the population health. The objective of this study was to describe the PM₁₀ toxic mechanism of action collected in 3 districts of Ouagadougou. Once per month and per site between November 2015 and February 2016, PM₁₀ was sampled for 24 hours using the MiniVol TAS (AirMetrics, Eugene, USA). The collected filters were then stored in Petri dishes at room temperature for in vitro toxicological studies using human pulmonary artery endothelial cells (HPAEC) at the Bordeaux INSERM-U1045 Cardio-thoracic Research Center. The three study districts were classified based on PM₁₀ level (high, intermediate, and low, respectively, for districts 2, 3, and 4). PM₁₀ induced a concentration-dependent decrease in cell viability. A significant decrease in cell viability was observed at 1 µg/cm², 10 µg/cm², and 25 µg/cm² for, respectively, districts 2, 3, and 4. A significant increase in the production of reactive oxygen species (ROS) was observed at 10 µg/cm² for district 2 versus 5 µg/cm² and 1 µg/cm² for districts 3 and 4, respectively. Finally, a significant production of IL-6 was recorded from 5 µg/cm² for district 4 versus 10 µg/cm² for districts 2 and 3. Consequently, Ouagadougou is subjected to PM₁₀ pollution, which can induce a significant production of ROS and IL-6 to cause adverse effects on the health of the population.

Study on Lung Injury Caused by Fine Particulate Matter and Intervention Effect of Rhodiola wallichiana

Objective

The objective of this study was to observe the protective effect of Rhodiola wallichiana drops in a rat model of fine particulate matter (PM2.5) lung injury.

Methods

Forty male Wistar rats were randomly divided into blank control (NC), normal saline (NS), PM2.5-infected (PM), and Rhodiola wallichiana (RW) groups. Rats in the NC group were not provided any interventions, whereas those in the NS and PM groups were administered normal saline and PM2.5 suspension by trachea drip once a week for four weeks. Rats in the RW group were intraperitoneally administered Rhodiola wallichiana for 14 days and then administered PM2.5 suspension by trachea drip 7 days after drug delivery. The levels of inflammatory factors such as interleukin-6, interleukin-1β, and tumor necrosis factor-alpha and oxidative stress biomarkers such as 8-hydroxy-2′-deoxyguanosine, 4-hydroxynonenal, and protein carbonyl content were determined in the serum and bronchoalveolar lavage fluid by ELISA. The level of 4-hydroxynonenal in the lung was also determined using Western blotting and immunohistochemical staining.

Results

Levels of inflammatory factors and oxidative stress biomarkers were all increased in the PM group but decreased in the RW group. Western blotting revealed increased 4-hydroxynonenal levels in the PM group but decreased levels in the RW group. Immunohistochemical staining also provided similar results.

Conclusion

Rhodiola wallichiana could protect rats from inflammation and oxidative stress injury caused by PM2.5.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

The effect of PM2.5-related hazards on biomarkers of bronchial epithelial cells (A549) inflammation in Karaj and Fardis cities

Fine particles (especially PM_2.5 particles) in ambient air can cause irreversible effects on human health. In the present study, seasonal variations in toxicity PM_2.5 (cell viability and release of pro-inflammatory cytokines) were exposed human lung cells (A549) to concentrations of PM_2.5 samples in summer (sPM_2.5) and winter (wPM_2.5) seasons. Cells were separately exposed to three concentrations of PM_2.5 (25, 50, and 100 μg/mL) and three times (12 h, 1 and 2 days). We evaluated cell viability by MTT assay [3- (4, 5-dimethylthiazol-2-yl) -2, 5-diphenyltetrazolium bromide] and liberation of pro-inflammatory cytokines (interleukin-6 and interleukin-8) by the ELISA method. The toxicological results of this study showed that increasing the concentration of PM_2.5 particulates and contact time with it reduces cell viability and increases inflammatory responses. Seasonal cytotoxicity of PM_2.5 particles in high-traffic areas at summer season compared to winter season was lower. The lowest percent of viability at 2 days of exposure and 100 μg/mL exposure in the winter sample was observed. Also, PM_2.5 particles were influential in the amount of interleukins 8 and 6. The average release level of IL-6 and IL-8 in the cold season (winter) and the enormous exposure time and concentrations (2 days-100 μg/mL) was much higher than in the hot season (summer). These values were twice as high for winter PM_2.5 samples as for summer samples. The compounds in PM_2.5 at different seasons can cause some biological effects. The samples' chemical characteristics in two seasons displayed that the PMs were diverse in chemical properties. In general, heavy metals and polycyclic aromatic hydrocarbons were more in the winter samples. However, the samples of wPM_2.5 had a lower mass quota of metals such as aluminum, iron, copper, zinc, and magnesium. Concentrations of chromium, cadmium, arsenic, mercury, nickel, and lead were more significant in the sample of wPM_2.5.

Tissue-Protective Effect of Erdosteine on Multiple-Organ Injuries Induced by Fine Particulate Matter

Background

Fine particulate matter (PM2.5) is the air pollutant that most threatens global public health. The purpose of this study was to observe the inflammatory and oxidative stress injury of multiple organs induced by PM2.5 in rats and to explore the tissue-protective effect of erdosteine.

Material/Methods

We randomly divided 40 male Wistar rats into a blank control group, a saline group, a PM2.5 exposure group, and an erdosteine intervention group. We assessed changes in organs tissue homogenate and biomarkers of inflammation and oxidative stress in serum and bronchoalveolar lavage fluid (BALF).

Results

(1) The expressions of IL-6, IL-1β, TNF-α, 8-OHdG, 4-HNE, and PCC in serum and BALF of the PM2.5 exposure group increased, but decreased after treatment with erdosteine, suggesting that erdosteine treatment attenuates inflammatory and oxidative stress injury. (2) The expression of γ-GCS in serum and lungs in the PM2.5 exposure group increased, but did not change significantly after treatment with erdosteine. This suggests that PM2.5 upregulates the level of γ-GCS, while erdosteine does not affect this protective response. (3) The expression of T-AOC in serum, lungs, spleens, and kidneys of the PM2.5 exposure group decreased, but increased after treatment with erdosteine. Our results suggest that PM2.5 can cause imbalance of oxidation/anti-oxidation in multiple organs, and erdosteine can alleviate this imbalance.

Conclusions

PM2.5 exposure can lead to inflammatory and oxidative stress damage in serum and organ tissues of rats. Erdosteine may be an effective anti-inflammatory and antioxidant that can reduce this injury.

Potential cytotoxicity of trace elements and polycyclic aromatic hydrocarbons bounded to particulate matter: a review on in vitro studies on human lung epithelial cells

A large number of studies have been conducted for clarifying toxicological mechanisms of particulate matter (PM) aimed to investigate the physicochemical properties of PM and providing biological endpoints such as inflammation, perturbation of cell cycle, oxidative stress, or DNA damage. However, although several studies have presented some effects, there is still no consensus on the determinants of biological responses. This review attempts to summarize all past research conducted in recent years on the physicochemical properties of environmental PM in different places and the relationship between different PM components and PM potential cytotoxicity on the human lung epithelial cells. Among 447 papers with our initial principles, a total of 50 articles were selected from 1986 to April 2020 based on the chosen criteria for review. According to the results of selected studies, it is obvious that cytotoxicity in human lung epithelial cells is created both directly or indirectly by transition metals (such as Cu, Cr, Fe, Zn), polycyclic aromatic hydrocarbons (PAH), and ions that formed on the surface of particles. In the selected studies, the findings of the correlation analysis indicate that there is a significant relationship between cell viability reduction and secretion of inflammatory mediators. As a result, it seems that the observed biological responses are related to the composition and the physicochemical properties of the PMs. Therefore, the physicochemical properties of PM should be considered when explaining PM cytotoxicity, and long-term research data will lead to improved strategies to reduce air pollution.

Cellular effects of PM2.5 from Suzhou, China: relationship to chemical composition and endotoxin content

Exposure to PM_2.5 can cause adverse health outcomes. In this study, we analyzed PM_2.5 samples collected from suburban and urban sites, including a traffic tunnel in Suzhou, China, for their physicochemical properties, endotoxin contents, and effects on HepG2 and A549 cells in vitro. The greatest cellular responses, including oxidative stress, cytotoxicity, genotoxicity, inflammatory, and transcriptional activation of stress-responsive genes (i.e., HSPA1A, GADD45α), were observed in cells treated with traffic tunnel PM_2.5. Cytokine expression was also measured and closely correlated with endotoxin content, while other toxic effects were largely related to PM_2.5-bound metals and polycyclic aromatic hydrocarbons (PAHs). These findings suggested that chemical and biological composition of PM_2.5, including adsorbed trace metals, PAHs, and endotoxin, may contribute significantly to their toxicity. In addition to commonly used in vitro toxicity tests, HSPA1A and GADD45α promoter-driven luciferase reporter cells may provide a potential new tool for rapid screening and quantification of PM_2.5 toxicity.

Airborne Aerosols and Human Health: Leapfrogging from Mass Concentration to Oxidative Potential

The mass concentration of atmospheric particulate matter (PM) has been systematically used in epidemiological studies as an indicator of exposure to air pollutants, connecting PM concentrations with a wide variety of human health effects. However, these effects can be hardly explained by using one single parameter, especially because PM is formed by a complex mixture of chemicals. Current research has shown that many of these adverse health effects can be derived from the oxidative stress caused by the deposition of PM in the lungs. The oxidative potential (OP) of the PM, related to the presence of transition metals and organic compounds that can induce the production of reactive oxygen and nitrogen species (ROS/RNS), could be a parameter to evaluate these effects. Therefore, estimating the OP of atmospheric PM would allow us to evaluate and integrate the toxic potential of PM into a unique parameter, which is related to emission sources, size distribution and/or chemical composition. However, the association between PM and particle-induced toxicity is still largely unknown. In this commentary article, we analyze how this new paradigm could help to deal with some unanswered questions related to the impact of atmospheric PM over human health.

Individual exposure level following indoor and outdoor air pollution exposure in Dakar (Senegal)

The consequences of indoor and outdoor air pollution on human health are of great concern nowadays. In this study, we firstly evaluated indoor and outdoor air pollution levels (CO, CO₂, NO, NO₂, PM₁₀) at an urban site in Dakar city center and at a rural site. Then, the individual exposure levels to selected pollutants and the variations in the levels of biomarkers of exposure were investigated in different groups of persons (bus drivers, traders working along the main roads and housemaids). Benzene exposure levels were higher for housemaids than for bus drivers and traders. High indoor exposure to benzene is probably due to cooking habits (cooking with charcoal), local practices (burning of incense), the use of cleaning products or solvent products which are important emitters of this compound. These results are confirmed by the values of S-PMA, which were higher in housemaids group compared to the others. Urinary 1-HOP levels were significantly higher for urban site housemaids compared to semirural district ones. Moreover, urinary levels of DNA oxidative stress damage (8-OHdG) and inflammatory (interleukin-6 and -8) biomarkers were higher in urban subjects in comparison to rural ones. The air quality measurement campaign showed that the bus interior was more polluted with PM₁₀, CO, CO₂ and NO than the market and urban or rural households. However, the interior of households showed higher concentration of VOCs than outdoor sites confirming previous observations of higher indoor individual exposure level to specific classes of pollutants.