REDUCTION OF PM2.5 TOXICITY ON HUMAN ALVEOLAR EPITHELIAL CELLS A549 BY TEA POLYPHENOLS

Phytochemical reduces toxicity of PM2.5: a review of research progress

Studies have shown that exposure to fine particulate matter (PM2.5) affects various cells, systems, and organs in vivo and in vitro. PM2.5 adversely affects human health through mechanisms such as oxidative stress, inflammatory response, autophagy, ferroptosis, and endoplasmic reticulum stress. Phytochemicals are of interest for their broad range of physiological activities and few side effects, and, in recent years, they have been widely used to mitigate the adverse effects caused by PM2.5 exposure. In this review, the roles of various phytochemicals are summarized, including those of polyphenols, carotenoids, organic sulfur compounds, and saponin compounds, in mitigating PM2.5-induced adverse reactions through different molecular mechanisms, including anti-inflammatory and antioxidant mechanisms, inhibition of endoplasmic reticulum stress and ferroptosis, and regulation of autophagy. These are useful as a scientific basis for the prevention and treatment of disease caused by PM2.5.

Selenium-Enriched Soybean Peptides as Novel Organic Selenium Compound Supplements: Inhibition of Occupational Air Pollution Exposure-Induced Apoptosis in Lung Epithelial Cells

The occupational groups exposed to air pollutants, particularly PM2.5, are closely linked to the initiation and advancement of respiratory disorders. The aim of this study is to investigate the potential protective properties of selenium-enriched soybean peptides (Se-SPeps), a novel Se supplement, in mitigating apoptosis triggered by PM2.5 in A549 lung epithelial cells. The results indicate a concentration-dependent reduction in the viability of A549 cells caused by PM2.5, while Se-SPeps at concentrations of 62.5-500 µg/mL showed no significant effect. Additionally, the Se-SPeps reduced the production of ROS, proinflammatory cytokines, and apoptosis in response to PM2.5 exposure. The Se-SPeps suppressed the PM2.5-induced upregulation of Bax/Bcl-2 and caspase-3, while also restoring reductions in p-Akt in A549 cells. The antiapoptotic effects of Se-SPeps have been found to be more effective compared to SPeps, SeMet, and Na2SeO3 when evaluated at an equivalent protein or Se concentration. Our study results furnish evidence that supports the role of Se-SPeps in reducing the harmful effects of PM2.5, particularly in relation to its effect on apoptosis, oxidative stress, and inflammation.

Tea polyphenols protect bovine intestinal epithelial cells from the adverse effects of heat-stress in vitro

Heat-stress (HS) leads to impaired gut health, adversely affecting milk production of dairy cows. In the present study, we investigated the protective effects of tea polyphenols (TP) against HS-induced damage in bovine intestinal epithelial cells (BIECs) and explored the underlying mechanisms. Primary BIECs were isolated from bovine duodenum, cultured and treated as follows: (1) control cells incubated in complete medium at 37 °C for 12 h, (2) TP group incubated in medium containing 100 μg/mL TP at 37 °C for 12 h, (3) HS group incubated in medium at 37 °C for 6 h followed by 6 h at 42 °C, and (4) HS + TP group incubated with 100 μg/mL TP for 6 h at 37 °C and 6 h at 42 °C. TP improved cell viability and antioxidant capacity, and decreased apoptosis and LDH activity. TP led to upregulation of Nrf2 and its target antioxidant genes HO-1, NQO1 and SOD1 expression. TP significantly decreased the expression of proinflammatory cytokine genes (NF-κB, IL-6 and TNF-α), and increased expression of the anti-inflammatory cytokine gene, IL-10. The above results suggested that TP protected BIECs from HS-induced adverse effects by alleviating oxidative stress and inflammatory responses, indicating that TP can alleviate HS-induced intestinal damage in dairy cows.

Assessing the cytotoxicity of aerosolized carbon black and benzo[a]pyrene with controlled physical and chemical properties on human lung epithelial cells

Atmospheric particulate matter (PM) is a complex mixture of hazardous particles containing hundreds of inorganic and organic species. Organic components, such as carbon black (CB) and benzo[a]pyrene (BaP), are known to exhibit diverse genotoxic and carcinogenic effects. The toxicity of CB and polycyclic aromatic hydrocarbons has been well studied, however the combined toxicity is much less understood. A spray-drying system was used to control the size and chemical composition of PMs. PMs were prepared by loading BaP on three different sized CBs (0.1 μm, 2.5 μm, and 10 μm) to obtain BaP-unloaded CB (CB0.1, CB2.5, and CB10) and BaP-loaded CB (CB0.1-BaP, CB2.5-BaP, and CB10-BaP). We analyzed cell viability, levels of oxidative stress, and pro-inflammatory cytokines using human lung cells (A549 epithelial cells). Cell viability decreased when exposed to all PMs (PM0.1, PM2.5, and PM10), regardless of the presence of BaP. The increase in PM size due to BaP-adsorption to CB resulted in insufficient toxic effects on human lung cells compared to CB alone. Smaller CBs reduced cell viability, leading to reactive oxygen species formation, which can cause damage to cellular structures deliver more harmful substances. Additionally, small CBs were predominant in inducing the expression of pro-inflammatory cytokines in A549 epithelial cells. These results indicate that the size of CB is a key factor that immediately affects the inflammation of lung cells, compared to the presence of BaP.

Dynamic Fluid Flow Exacerbates the (Pro-)Inflammatory Effects of Aerosolised Engineered Nanomaterials In Vitro

The majority of in vitro studies focusing upon particle-lung cell interactions use static models at an air-liquid interface (ALI). Advancing the physiological characteristics of such systems allows for closer resemblance of the human lung, in turn promoting 3R strategies. PATROLS (EU Horizon 2020 No. 760813) aimed to use a well-characterised in vitro model of the human alveolar epithelial barrier to determine how fluid-flow dynamics would impact the outputs of the model following particle exposure. Using the QuasiVivo^TM (Kirkstall Ltd., York, UK) system, fluid-flow conditions were applied to an A549 + dTHP-1 cell co-culture model cultured at the ALI. DQ₁₂ and TiO₂ (JRCNM01005a) were used as model particles to assess the in vitro systems' sensitivity. Using a quasi- and aerosol (VitroCell Cloud12, VitroCell Systems, Waldkirch, Germany) exposure approach, cell cultures were exposed over 24 h at IVIVE concentrations of 1 and 10 (DQ₁₂) and 1.4 and 10.4 (TiO₂) µg/cm², respectively. We compared static and fluid flow conditions after both these exposure methods. The co-culture was subsequently assessed for its viability, membrane integrity and (pro-)inflammatory response (IL-8 and IL-6 production). The results suggested that the addition of fluid flow to this alveolar co-culture model can influence the viability, membrane integrity and inflammatory responses dependent on the particle type and exposure.

Molecular mechanism of Pulmonary diseases caused by exposure to urban PM2.5 in Chengdu-Chongqing Economic Circle, China

Chengdu-Chongqing Economic Circle (CD-CQ Economic Circle) is one of China's four major economic circles and five major urban agglomerations located in Southwest China's Sichuan Basin. The CD-CQ Economic Circle, with its strong economic development and dense population, suffers from severe PM_2.5 pollution, which is known to cause chronic and acute respiratory ailments. This study examined the lung disease-related hub genes, functions, and pathways that are affected by PM_2.5 in summer and winter in the two central megacities of Chengdu and Chongqing. PM_2.5 frequently activates lung disease-associated hub genes, most notably the transcription factor TP53. TP53 interacts with the majority of lung disease-related genes and regulates important and commonly occurring biological functions and pathways, including gland development, aging, reactive oxygen species metabolic process, the response to oxygen levels, and fluid shear stress, among others. Thus, PM_2.5 has been shown to target TP53 for regulating lung disease genes/functions/pathways, thereby influencing the occurrence and progression of lung illnesses. Notably, PM_2.5 may be associated with small cell carcinoma of the lung due to the high number of lung disease genes, hub genes, critical functions, and pathways enriched in this kind of cancer. These findings shed fresh light on the molecular pathophysiology of PM_2.5 pollution on the respiratory system in the CD-CQ Economic Circle and aid in the development of novel techniques for mitigating PM_2.5 pollution-associated respiratory illness.

Pathogenic Mechanisms of Secondary Organic Aerosols

Air pollution represents a major health problem and an economic burden. In recent years, advances in air pollution research has allowed particle fractionation and identification of secondary organic aerosol (SOA). SOA is formed from either biogenic or anthropogenic emissions, through a mass transfer from the gaseous mass to the particulate phase in the atmosphere. They can have deleterious impact on health and the mortality of individuals with chronic inflammatory diseases. The pleiotropic effects of SOA could involve different and interconnected pathogenic mechanisms ranging from oxidative stress, inflammation, and immune system dysfunction. The purpose of this review is to present recent findings about SOA pathogenic roles and potential underlying mechanisms focusing on the lungs; the latter being the primary exposed organ to atmospheric pollutants.

The influence of exposure approaches to in vitro lung epithelial barrier models to assess engineered nanomaterial hazard

Exposure to engineered nanomaterials (ENM) poses a potential health risk to humans through long-term, repetitive low-dose exposures. Currently, this is not commonplace within in vitro lung cell cultures. Therefore, the purpose of this study was to consider the optimal exposure approach toward determining the stability, sensitivity and validity of using in vitro lung cell mono- and co-cultures to determine ENM hazard. A range of exposure scenarios were conducted with DQ₁₂ (previously established as a positive particle control) (historic and re-activated), TiO₂ (JRC NM-105) and BaSO₄ (JRC NM-220) on both monocultures of A549 cells as well as co-cultures of A549 cells and differentiated THP-1 cells. Cell cultures were exposed to either a single, or a repeated exposure over 24, 48- or 72-hours at in vivo extrapolated concentrations of 0-5.2 µg/cm², 0-6 µg/cm² and 0-1µg/cm². The focus of this study was the pro-inflammatory, cytotoxic and genotoxic response elicited by these ENMs. Exposure to DQ₁₂ caused pro-inflammatory responses after 48 hours repeat exposures, as well as increases in micronucleus frequency. Neither TiO₂ nor BaSO₄ elicited a pro-inflammatory response at this time point. However, there was induction of IL-6 after 24 hours TiO₂ exposure. In conclusion, it is important to consider the appropriateness of the positive control implemented, the cell culture model, the time of exposure as well as the type of exposure (bolus or fractionated) before establishing if an in vitro model is appropriate to determine the level of response to the specific ENM of interest.

The roles of catechins in regulation of systemic inflammation

Catechins are a phytochemical present in plants such as tea leaves, beans, black grapes, cherries, and cacao, and have various physiological activities. It is reported that catechins have a health improvement effect and ameliorating effect against various diseases. In addition, antioxidant activity, liver damage prevention, cholesterol lowering effect, and anti-obesity activity were confirmed through in vivo animal and clinical studies. Although most diseases are reported as ones mediating various inflammations, the mechanism for improving inflammation remains unclear. Therefore, the current review article evaluates the physiological activity and various pharmacological actions of catechins and conclude by confirming an improvement effect on the inflammatory response.

Food bioactives lowering risks of chronic diseases induced by fine particulate air pollution: a comprehensive review

Airborne particulate matter (PM) exerts huge negative impacts on human health worldwide, not only targeting the respiratory system but more importantly inducing and aggravating associated chronic diseases like asthma, lung cancer, atherosclerosis, diabetes mellitus and Alzheimer diseases. Food-derived bioactive compounds like vitamins, dietary polyphenols, omega-3 polyunsaturated fatty acids and sulforaphane are feasible alternative therapeutic approaches against PM-mediated potential health damages, drawing great attention in recent years. In this review, the association between PM exposure and risks of developing chronic diseases, and the detailed mechanisms underlying the detrimental effects of PM will be discussed. Subsequently, principal food-derived bioactive compounds, with emphasize on the preventative or protective effects against PM, along with potential mechanisms will be elucidated. This comprehensive review will discuss and present current research findings to reveal the nutritional intervention as a preventative or therapeutic strategy against ambient air pollution, thereby lowering the risk of developing chronic diseases.

Targeting mitochondrial permeability transition pore ameliorates PM2.5-induced mitochondrial dysfunction in airway epithelial cells

Particulate matter with aerodynamic diameter not larger than 2.5 μm (PM_2.5) escalated the risk of respiratory diseases. Mitochondrial dysfunction may play a pivotal role in PM_2.5-induced airway injury. However, the potential effect of PM_2.5 on mitochondrial permeability transition pore (mPTP)-related airway injury is still unknown. This study aimed to investigate the role of mPTP in PM_2.5-induced mitochondrial dysfunction in airway epithelial cells in vitro. PM_2.5 significantly reduced cell viability and caused apoptosis in BEAS-2B cells. We also found PM_2.5 caused cellular and mitochondrial morphological alterations, evidenced by the disappearance of mitochondrial cristae, mitochondrial swelling, and the rupture of the outer mitochondrial membrane. PM_2.5 induced mPTP opening via upregulation of voltage-dependent anion-selective channel (VDAC), leading to deprivation of mitochondrial membrane potential, increased mitochondrial reactive oxygen species (ROS) generation and intracellular calcium level. PM_2.5 suppressed mitochondrial respiratory function by reducing basal and maximal respiration, and ATP production. The mPTP targeting compounds cyclosporin A [CsA; a potent inhibitor of cyclophilin D (CypD)] and VBIT-12 (a selective VDAC1 inhibitor) significantly inhibited PM_2.5-induced mPTP opening and apoptosis, and preserved mitochondrial function by restoring mitochondrial membrane potential, reducing mitochondrial ROS generation and intracellular calcium content, and maintaining mitochondrial respiration function. Our data further demonstrated that PM_2.5 caused reduction in nuclear expressions of PPARγ and PGC-1α, which were reversed in the presence of CsA. These findings suggest that mPTP might be a potential therapeutic target in the treatment of PM_2.5-induced airway injury.

Powdered Green Tea (Matcha) Attenuates the Cognitive Dysfunction via the Regulation of Systemic Inflammation in Chronic PM2.5-Exposed BALB/c Mice

This study was conducted to evaluate the anti-amnesic effect of the aqueous extract of powdered green tea (matcha) (EM) in particulate matter (PM)_2.5-induced systemic inflammation in BALB/c mice. EM ameliorated spatial learning and memory function, short-term memory function, and long-term learning and memory function in PM_2.5-induced mice. EM protected against antioxidant deficit in pulmonary, dermal, and cerebral tissues. In addition, EM improved the cholinergic system through the regulation of acetylcholine (ACh) levels and acetylcholinesterase (AChE) activity in brain tissue, and it protected mitochondrial dysfunction by regulating the production of reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and ATP contents in brain tissue. EM attenuated systemic inflammation and apoptotic signaling in pulmonary, dermal, olfactory bulb, and hippocampal tissues. Moreover, EM suppressed neuronal cytotoxicity and cholinergic dysfunction in hippocampal tissue. This study suggests that EM might be a potential substance to improve PM_2.5-induced cognitive dysfunction via the regulation of systemic inflammation.

Development of alveolar-capillary-exchange (ACE) chip and its application for assessment of PM2.5-induced toxicity

Although standard two-dimensional (2D) cell culture is an effective tool for cell studies, monolayer cultivation can yield imperfect or misleading information about numerous biological functions. In this study, we developed an alveolar-capillary exchange (ACE) chip aiming to simulate the cellular microenvironment at the alveolar-capillary interface. The ACE chip was designed with two chambers for culturing alveolar epithelial cells and vascular endothelial cells separately, which are separated by a microporous polycarbonate film that allows for the exchange of soluble biomolecules. Using this model, we further tested the toxic effects of fine particulate matter (PM_2.5), a form of airborne pollutant known to induce adverse effects on human respiratory system. These effects are largely associated with the ability of PM_2.5 to penetrate the alveoli, where it negatively affects the pulmonary function. Our results indicate that alveolar epithelial cells cultured in the ACE chip in solo and coculture with vascular endothelial cells underwent oxidative injury-induced apoptosis mediated via the PEAK-eIF2α signaling pathway of endoplasmic reticulum stress. The use of ACE chip in an alveolar epithelial cell-vascular endothelial cell coculture model revealed cellular vulnerability to PM_2.5. Therefore, this chip provides a feasible surrogate approach in vitro for investigating and simulating the cellular microenvironment responses associated with ACE in vivo.

In vitro impact preliminary assessment of airborne particulate from metalworking and woodworking industries

Inhalation is the main route of exposure to airborne pollutants. To evaluate the safety and assess the risks of occupational hazards different testing approaches are used. 3D airway epithelial tissues allow to mimic exposure conditions in vitro, generates human-relevant toxicology data, allows to elucidate the mode of action of pollutants. Gillian3500 pumps were used to collect the airborne particulate from woodworking and metalworking environments. EpiAirway tissues were used to model half working day (4 h), full working day (8 h), and 3 working day exposures to occupational pollutants. Tissue viability was assessed using an MTT assay. For preliminary assessment, RT-qPCR analyses were performed to analyze the expression of gelsolin, caspase-3, and IL-6. Tissue morphology was assessed by hematoxylin/eosin staining. An effect on the proliferation of lung epithelial cell line A549 was assessed. Acute exposure to workspace pollutants slightly affected tissue viability and did not change the morphology. No inhibiting effect was observed on the proliferation of A549 cells. Preliminary analysis showed that both types of particles suppressed the expression of gelsolin, with the effect of metalworking samples being more pronounced. A slight reduction in caspase-3 expression was observed. Particles from metalworking suppressed IL-6 expression.

Polyphenols Could Prevent SARS-CoV-2 Infection by Modulating the Expression of miRNAs in the Host Cells

Coronaviruses (CoVs) are single-stranded RNA viruses which following virus attachment and entry into the host cell, particularly type 2 pneumocytes but also endothelial cells, release RNA into cytosol where it serves as a matrix for the host translation machinery to produce viral proteins. The viral RNA in cytoplasm can interact with host cell microRNAs which can degrade viral RNA and/or prevent viral replication. As such host cellular miRNAs represent key cellular mediators of antiviral defense. Polyphenols, plant food bioactives, exert antiviral properties, which is partially due to their capacity to modulate the expression of miRNAs. The objective of this work was to assess if polyphenols can play a role in prevention of SARS-CoV-2 associated complications by modulating the expression of host miRNAs. To test this hypothesis, we performed literature search to identify miRNAs that could bind SARS-CoV-2 RNA as well as miRNAs which expression can be modulated by polyphenols in lung, type 2 pneumocytes or endothelial cells. We identified over 600 miRNAs that have capacity to bind viral RNA and 125 miRNAs which expression can be modulated by polyphenols in the cells of interest. We identified that there are 17 miRNAs with both the capacity to bind viral RNA and which expression can be modulated by polyphenols. Some of these miRNAs have been identified as having antiviral properties or can target genes involved in regulation of processes of viral replication, apoptosis or viral infection. Taken together this analysis suggests that polyphenols could modulate expression of miRNAs in alveolar and endothelial cells and exert antiviral capacity.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

Nutraceuticals with anti-inflammatory and anti-oxidant properties as intervention for reducing the health effects of fine particulate matter: Potential and Prospects

Air pollution, especially particulate matter pollution adversely affects human health. A growing pool of evidence has emerged which underscores the potential of individual-level nutritional interventions in attenuating the adverse health impact of exposure to PM2.5. Although controlling emission and reducing the overall levels of air pollution remains the ultimate objective globally, the sustainable achievement of such a target and thus consequent protection of human health will require a substantial amount of time and concerted efforts worldwide. In the meantime, smaller-scale individual-level interventions that can counter the inflammatory or oxidative stress effects triggered by exposure to particulate matter may be utilized to ameliorate the health effects of PM2.5 pollution. One such intervention is incorporation of nutraceuticals in the diet. Here, we present a review of the evidence generated from various in vitro, in vivo and human studies regarding the effects of different anti-inflammatory and antioxidant nutraceuticals in ameliorating the health effects of particulate matter air pollution. The studies discussed in this review suggest that these nutraceuticals when consumed as a part of the diet, or as additional supplementation, can potentially negate the cellular level adverse effects of exposure to particulate pollution. The potential benefits of adopting a non-pharmacological diet-based approach to air pollution-induced disease management have also been discussed. We argue that before a nutraceuticals-based approach can be used for widespread public adoption, further research, especially human clinical trials, is essential to confirm the beneficial action of relevant nutraceuticals and to explore the safe limits of human supplementation and the risk of side effects. Future research should focus on systematically translating bench-based knowledge regarding nutraceuticals gained from in-vitro and in-vivo studies into clinically usable nutritional guidelines.

Natural compounds protect the skin from airborne particulate matter by attenuating oxidative stress

Particulate matter (PM) is a common indirect indicator of air pollution and threatens public health upon prolonged exposure, leading to oxidative stress, increasing the risk of develop respiratory and cardiovascular, as well as several autoimmune diseases and cancer. Nowadays, as a first line defense against PM, skin health attracted much attention. Our review summarized the skin damage mechanism induced by PM, including damage skin barrier directly, reactive oxygen species (ROS) accumulation, autophagy, and two canonical signaling pathways. Furthermore, ROS and oxidative stress have been considered pathogenesis centers, with essential skin damage roles. Extracts from plants and natural compounds which present high antioxidant capacity could be used to treat or protect against air pollution-related skin damage. We conclude the extracts reported in recent studies with protective effects on PM-mediated skin damage. Besides, the mechanism of extracts' positive effects has been revealed partially.

Comparative Toxic Effects of Manufactured Nanoparticles and Atmospheric Particulate Matter in Human Lung Epithelial Cells

Although nanoparticles (NPs) have been used as simplified atmospheric particulate matter (PM) models, little experimental evidence is available to support such simulations. In this study, we comparatively assessed the toxic effects of PM and typical NPs (four carbonaceous NPs with different morphologies, metal NPs of Fe, Al, and Ti, as well as SiO₂ NPs) on human lung epithelial A549 cells. The EC50 value of PM evaluated by cell viability assay was 148.7 μg/mL, closest to that of SiO₂ NPs, between the values of carbonaceous NPs and metal NPs. All particles caused varying degrees of reactive oxygen species (ROS) generation and adenosine triphosphate (ATP) suppression. TiO₂ NPs showed similar performance with PM in inducing ROS production (p < 0.05). Small variations between two carbonaceous NPs (graphene oxides and graphenes) and PM were also observed at 50 μg/mL. Similarly, there was no significant difference in ATP inhibition between carbonaceous NPs and PM, while markedly different effects were caused by SiO₂ NP and TiO₂ NP exposure. Our results indicated that carbonaceous NPs could be served as potential surrogates for urban PM. The identification of PM model may help us further explore the specific roles and mechanisms of various components in PM.

The Inducible Role of Ambient Particulate Matter in Cancer Progression via Oxidative Stress-Mediated Reactive Oxygen Species Pathways: A Recent Perception

Simple Summary

Particulate matter, especially the fine fraction PM2.5, is officially stated as carcinogenic to human. There are compelling evidences on the association between PM2.5 exposure and lung cancer, and there are also some preliminary data reporting the significant links between this fraction with non-lung cancers. The underlying mechanisms remain unclear. Further studies related to such scope are highly required. The purpose of this work is to systemically analyze recent findings concerning the relationship between PM2.5 and cancer, and to thoroughly present the oxidative stress pathways mediated by reactive oxygen species as the key mechanism for carcinogenesis induced by PM2.5. This will provide a more comprehensive and updated knowledge regarding carcinogenic capacity of PM2.5 to both clinicians and public health workers, contributing to preventive and therapeutic strategies to fight against cancer in human.

Abstract

Cancer is one of the leading causes of premature death and overall death in the world. On the other hand, fine particulate matter, which is less than 2.5 microns in aerodynamic diameter, is a global health problem due to its small diameter but high toxicity. Accumulating evidence has demonstrated the positive associations between this pollutant with both lung and non-lung cancer processes. However, the underlying mechanisms are yet to be elucidated. The present review summarizes and analyzes the most recent findings on the relationship between fine particulate matter and various types of cancer along with the oxidative stress mechanisms as its possible carcinogenic mechanisms. Also, promising antioxidant therapies against cancer induced by this poison factor are discussed.

Molecular mechanisms linking environmental toxicants to cancer development: Significance for protective interventions with polyphenols

Human exposure to environmental toxicants with diverse mechanisms of action is a growing concern. In addition to well-recognized carcinogens, various chemicals in environmental and occupational settings have been suggested to impact health, increasing susceptibility to cancer by inducing genetic and epigenetic changes. Accordingly, in this review, we have discussed recent insights into the pathological mechanisms of these chemicals, namely their effects on cell redox and calcium homeostasis, mitochondria and inflammatory signaling, with a focus on the possible implications for multi-stage carcinogenesis and its reversal by polyphenols. Plant-derived polyphenols, such as epigallocatechin-gallate, resveratrol, curcumin and anthocyanins reduce the incidence of cancer and can be useful nutraceuticals for alleviating the detrimental outcomes of harmful pollutants. However, development of therapies based on polyphenol administration requires further studies to validate the biological efficacy, identifying effective doses, mode of action and new delivery forms. Innovative microphysiological testing models are presented and specific proposals for future trials are given. Merging the current knowledge of multifactorial actions of specific polyphenols and chief environmental toxicants, this work aims to potentiate the delivery of phytochemical-based protective treatments to individuals at high-risk due to environmental exposure.