PM2.5-related cell death patterns

Network pharmacology and phytochemical composition combined with validation in vivo and in vitro reveal the mechanism of platycodonis radix ameliorating PM2.5-induced acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

Platycodonis radix (PR), the root of Platycodon grandiflorus (Jacq.) A. DC., is a traditional Chinese medicine recognized for its dual role as both a medicinal and dietary substance, exhibiting significant anti-inflammatory properties. It is frequently utilized in the treatment of lung diseases. However, the molecular mechanisms by which PR exerts its effects in the treatment of acute lung injury (ALI) remain unclear.

AIM OF THE STUDY

This study presents a novel strategy that integrates network pharmacology, molecular docking, untargeted metabolomics analysis and experimental validation to investigate the molecular mechanisms through which PR treats ALI.

MATERIALS AND METHOD

Initially, the bioactive components of PR, along with its targets and pathways in the treatment of ALI, were identified using network pharmacology. Following this, preliminary validation was conducted through molecular docking. The active ingredients in the aqueous extract of PR were characterized using HPLC-MS. Finally, in vivo and in vitro experiments were performed to further validate the findings from the network pharmacology.

RESULTS

A total of 14 bioactive components and 156 effective targets were identified using the TCMSP, DisGeNET, Genecard, OMIM databases and Venny 2.1.0. Protein-protein interaction (PPI) analysis revealed 22 core targets including TP53, AKT1, STAT3 and JUN. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that these targets primarily participate in the regulation of cellular apoptosis, lung cancer and inflammatory pathways. Molecular docking demonstrated that four bioactive components exhibited strong affinities with their respective docking targets. LC-MS analysis confirmed that the aqueous extract of PR contained 87 components, including two active ingredients identified through network pharmacology and molecular docking. Preliminary validation was conducted in mice with ALI induced by acute PM2.5 exposure, revealing that the aqueous extract of PR reduced inflammatory factor levels in bronchoalveolar lavage fluid, enhanced antioxidant capacity in lung tissue, and decreased lung cell apoptosis in PM2.5-exposed mice. Notably, PR alleviated PM2.5-induced ALI through the STAT3, JUN, and AKT1 signaling pathways. Similarly, the results of in vitro intervention experiments further confirmed that the aqueous extract of PR protected pulmonary epithelial cells against PM2.5 exposure through activating AKT1 sinalling pathway, and inhibiting STAT3 and JUN signalling pathways.

CONCLUSION

This study identifies the active components of PR and elucidates the molecular mechanisms by which PR alleviates ALI, specifically by inhibiting the phosphorylation levels of STAT3 and c-JUN, or by activating the phosphorylation level of AKT1. These results provide a foundational basis for the application of PR in the treatment or prevention of lung injuries induced by particulate matter.

Effect of Particulate Matter 2.5 on Primary Gingival Keratinocyte and Human Gingival Fibroblast Cell Lines

OBJECTIVE

 Particulate matter 2.5 (PM2.5), an important air pollution particle, has been previously studied for its effects on various normal and cancer tissues. However, research on the impact of PM2.5, specifically on normal cavity tissue, is still limited. This study aimed to assess the effects of PM2.5 on cell vitality, cell cycle, and apoptosis in PGK (normal oral keratinocyte) and HGF (human gingival fibroblast) cell lines.

MATERIALS AND METHODS

 The effect of PM2.5 was examined through cell vitality using the Cell Counting Kit-8 (CCK8) assay, while cell cycle and apoptosis were determined via flow cytometry. Cells incubated with 0.05% dimethyl sulfoxide were used as the negative control.

RESULTS

 In a concentration-dependent manner, PM2.5 inhibited the proliferation of HGF and PGK cells. The half-maximal inhibitory concentration (IC50) of PM2.5 after 24 hours of incubation was 400 ng/µL for HGF cells and 100 ng/µL for PGK cells. This particulate matter arrested the cell cycles of both HGF and PGK cells at the G0/G1 phase. Additionally, PM2.5 was found to trigger apoptosis in both HGF and PGK cell lines and also cause necrosis in the PGK cell line at higher concentrations.

STATISTICAL ANALYSIS

 Kruskal-Wallis tests were employed to evaluate all quantitative data.

CONCLUSION

 The findings indicated that PM2.5 decreases cell viability, halts cell cycle progression, and triggers apoptosis in normal oral cavity cell lines. Therefore, it is advisable to avoid PM2.5 exposure in order to mitigate potential health risks. To understand PM2.5-induced oral cellular damage, more research is needed.

Risk assessment of PM2.5 from fossil energy consumption on the respiratory health of the elderly

Air pollution mainly comes from fossil energy consumption (FEC), and it brings great threat to public health. The respiratory system of the elderly is highly susceptible to the effects of air pollution due to the decline in body functions. PM2.5 is a major component of air pollution, so the study of the impact of PM2.5 generated by FEC on the respiratory health of the elderly is of great significance. The existing studies have focused more on the effect of PM2.5 on mortality, and this paper is a useful addition to the existing studies by examining the effect of PM2.5 from FEC on the health of the elderly from the perspective of prevalence. In this paper, the binary Logistic regression model was used to calculate the exposure-response relationship coefficient for respiratory health in older adults using the data in 2018 from the Chinese Longitudinal Healthy Longevity Survey. And referring to the Dynamic Projection model for Emissions in China, the changes in the number of older persons suffering from respiratory diseases due to PM2.5 from FEC in the baseline scenario, the clean air scenario, and the on-time peak-clean air scenario were predicted. The results indicated that: (1) PM2.5 from FEC mainly came from coal; (2) PM2.5 from FEC was detrimental to the respiratory health of the elderly, and older seniors were more affected as they age; (3) In the on-time peak-clean air scenario, the number of elderly people suffering from respiratory diseases due to PM2.5 from FEC was growing at the slowest rate. Based on the above results, this paper raised recommendations for reducing the effect of PM2.5 from FEC on the health of the elderly.

Co-exposure of ferruginous components of subway particles with lipopolysaccharide impairs vascular function: A comparative study with ambient particulate matter

Several empirical studies have linked subway and ambient particle exposure to toxicity, pro-inflammatory responses, and vascular dysfunction. However, the health effects of pollutants generated from varying sources, particularly when combined with lipopolysaccharide (LPS), are still unexplored. Therefore, the aim of this study was to investigate the characteristic health effects of iron oxide particles (the main components of subway particles) in comparison with urban aerosols (UA) and vehicle exhaust particles (VEP), alone and in combination with LPS. This study revealed that iron oxides caused a more significant reduction in human umbilical vein endothelial cell viability, increased lactate dehydrogenase release, and decreased the production of plasminogen activator inhibitor-1, a fibrinolytic modulator, and endothelin-1, a vasoconstrictor, compared to those by VEP and UA at marginally toxic and toxic concentrations. While VEP and UA induced an increase in interleukin (IL)-6 production, iron oxides, particularly Fe3O4, increased IL-8 production at slightly toxic and non-cytotoxic concentrations. In addition, co-exposure of all particles and LPS at non-cytotoxic concentrations promoted pro-inflammatory cytokine (IL-6 and IL-8) production relative to exposure to the particles alone. Interestingly, the tendency towards either coagulation or fibrinolytic conditions was dependent on the concentration of exposed particles at the same LPS concentration. Furthermore, increases in inflammation, neutrophil and lymphocyte recruitment around blood vessels, and edema were observed in murine lungs exposed to a combination of iron oxides and LPS compared to those in mice exposed to iron oxide alone. Thus, iron oxide-rich subway particulate poses more health risks than outdoor ambient particles since they can significantly impair endothelial function, particularly through gross cellular and vascular homeostatic protein damage, and induce exacerbated inflammatory responses during co-exposure. These findings provide novel empirical evidence for epidemiological studies seeking mechanisms responsible for the observed health impact of transport- and occupational-related exposures on vascular dysfunction.

Ferroptosis in the Substantia Nigra Pars Compacta of Mice: Triggering Role of Ultrafine Diesel Exhaust Particles and Mitigation by α-Lipoic Acid

Recent epidemiological and experimental studies have increasingly highlighted the association between environmental pollution, especially ultrafine particulate matter (PM), and the risk of neurodegenerative diseases, such as Parkinson's disease (PD). These previous studies suggest a potential mechanism by which ultrafine PM contributes to neuronal damage through processes, such as iron accumulation and oxidative stress. In this study, we aimed to elucidate the effects of ultrafine PM on ferroptosis, an iron-dependent form of cell death, in the mouse substantia nigra pars compacta (SNc) and to evaluate the protective role of α-lipoic acid (ALA). Mice were exposed to ultrafine diesel exhaust particles (ufDEP), a type of ultrafine PM, intranasally and injected ALA intraperitoneally for seven consecutive days. Iron accumulation and lipid peroxidation were significantly increased, and antioxidant capacity was significantly decreased in the SNc after ufDEP exposure, highlighting the deleterious effects of ufDEP on tyrosine hydroxylase (TH)-positive neurons. In contrast, ALA treatment effectively mitigated these effects by reducing iron accumulation, decreasing lipid peroxidation, and restoring antioxidant levels, resulting in the protection of TH-positive neurons from ferroptotic damage. Our results provide evidence that ufDEP can induce ferroptosis in dopaminergic neurons in the SNc, potentially contributing to PD pathogenesis. Furthermore, ALA showed protective effects against ufDEP-induced ferroptotic damage, suggesting its potential as a therapeutic intervention for PD.

Redox cell signalling triggered by black carbon and/or radiofrequency electromagnetic fields: Influence on cell death

The capacity of environmental pollutants to generate oxidative stress is known to affect the development and progression of chronic diseases. This scientific review identifies previously published experimental studies using preclinical models of exposure to environmental stress agents, such as black carbon and/or RF-EMF, which produce cellular oxidative damage and can lead to different types of cell death. We summarize in vivo and in vitro studies, which are grouped according to the mechanisms and pathways of redox activation triggered by exposure to BC and/or EMF and leading to apoptosis, necrosis, necroptosis, pyroptosis, autophagy, ferroptosis and cuproptosis. The possible mechanisms are considered in relation to the organ, cell type and cellular-subcellular interaction with the oxidative toxicity caused by BC and/or EMF at the molecular level. The actions of these environmental pollutants, which affect everyday life, are considered separately and together in experimental preclinical models. However, for overall interpretation of the data, toxicological studies must first be conducted in humans, to enable possible risks to human health to be established in relation to the progression of chronic diseases. Further actions should take pollution levels into account, focusing on the most vulnerable populations and future generations.

Influence of air pollution on the nonaccidental death before and after the outbreak of COVID-19

BACKGROUND

During the COVID-19 pandemic, non-therapeutic interventions (NPIs), such as traffic restrictions, work stoppages, and school suspensions, have led to a sharp decline in the concentration of air pollutants in the epidemic sites. However, few studies focused on the impact of air pollutant changes on the risk of nonaccidental death.

METHOD

We selected Yancheng City, China, as the study site and applied a Generalized Additive Model (GAM) based on the quasi-Poisson distribution to evaluate the impact of atmospheric pollutants exposure on the nonaccidental death of local residents. The time span of this study was set from January 1, 2013, to December 21, 2022, that is, before and after the outbreak of COVID-19.

RESULTS

The concentration of some air pollutants has greatly varied after the outbreak of COVID-19, with a significant decline for PM2.5 (- 43.4%), PM10 (- 38.5%), SO2 (- 62.9%), and NO2 (- 22.6%), but an increase for O3 (+ 4.3%). Comparative analysis showed that PM2.5 contributed to an increased risk of nonaccidental death after the outbreak of COVID-19. With an increase in PM2.5 by 10 µg/m³, the excess relative risks (ER) of nonaccidental death of residents increased by 1.01% (95%CI: 0.19%,1.84%). The stratified analysis revealed that air pollutants impacted nonaccidental deaths in both men and women before the outbreak of COVID-19. After the outbreak of COVID-19, PM10 had a significant effect on male nonaccidental deaths. The concentrations of PM2.5, PM10, and SO2 increased by 10 µg/m³, the ER of PM2.5, PM10, and SO2 on female nonaccidental death increased by 1.52% (0.38%,2.67%), 0.58% (0.02%,1.13%), and 15.09% (5.73%,25.28%), respectively. Before the outbreak of COVID-19, five air pollutants had an impact on the death of residents from cardiovascular disease (CVD). After the outbreak of COVID-19, only PM10 significantly affected the death risk of CVD. In addition, we discovered that PM2.5, PM10, and SO2 significantly impacted the risk of death due to respiratory diseases before and after the outbreak of COVID-19.

CONCLUSIONS

Air pollutants have different effects on nonaccidental deaths before and after the COVID-19 outbreak. A decrease in air pollutant concentration due to the NPIs for COVID-19 had a significant effect on the reduction of the risk of nonaccidental death.

Particulate matter 2.5 accelerates aging: Exploring cellular senescence and age-related diseases

Exposure to Particulate matter 2.5 (PM2.5) accelerates aging, causing declines in tissue and organ function, and leading to diseases such as cardiovascular, neurodegenerative, and musculoskeletal disorders. PM2.5 is a major environmental pollutant and an exogenous pathogen in air pollution that is now recognized as an accelerator of human aging and a predisposing factor for several age-related diseases. In this paper, we seek to elucidate the mechanisms by which PM2.5 induces cellular senescence, such as genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, and mitochondrial dysfunction, and age-related diseases. Our goal is to increase awareness among researchers within the field of the toxicity of environmental pollutants and to advocate for personal and public health initiatives to curb their production and enhance population protection. Through these endeavors, we aim to promote longevity and health in older adults.

The association between airborne particulate matter (PM2.5) exposure level and primary open-angle glaucoma

The eye is vulnerable to the adverse effects of air pollution. Previous experimental study found that fine particulate matter (PM2.5) had a direct toxic effect on intraocular tissues. However, clinical evidence for the impact of air pollutants exposure on functional and structural changes in glaucoma remains scarce. A total of 120 patients with primary open-angle glaucoma (POAG) who met the inclusion criteria were included in this retrospective study. The standardized ophthalmic examination, such as intraocular pressure (IOP), visual field, optical coherence tomography, and comprehensive physical examination, were performed. The air pollution data, including PM2.5 concentration and air quality index (AQI), were collected. PM2.5 and AQI for the day of the medical examination, as well as one month, and three months before the medical examination date, were investigated. In our results, higher average exposure levels for one-month and three-month, were associated with increased IOP (r=0.229, P=0.013; r=0.204, P=0.028, respectively) and decreased visual field mean sensitivity (MS) (r=-0.212, P=0.037; r=-0.305, P=0.002, respectively). PM2.5 concentrations for the day of the medical examination was not significantly associated with ocular parameters. In multiple linear regression analysis adjusted for demographic and clinical factors, higher PM2.5 exposure for one month was associated with elevated IOP (P=0.040, β=0.173, 95 %CI=0.008-0.337). We also found an association between PM2.5 and MS (one-month exposure: β=-0.160, P=0.029; three-month exposure: β=-0.238, P=0.002). The logistic regression analysis found that three-month average PM2.5 exposure level was significantly associated with the disease severity (β=0.043, P=0.025, 95 %CI=1.005-1.084). In conclusion, this study is the first to investigate the relationship between air pollution and detailed ocular parameters of POAG patients in Shanghai over a three-year period, and to explore the effects of different exposure times of PM2.5 on glaucoma. This study found that PM2.5 exposure was correlated with elevated IOP and decreased MS. The one-month PM2.5 exposure level had the most significant effects on IOP. The three-month PM2.5 exposure level was an independent risk factor for POAG severity. Current evidence suggests there may be an association between PM2.5 exposure and POAG.

PM2.5 is linked to Alzheimer's syndrome and delirium: a mendelian randomization analysis

BACKGROUND

Increasing air pollution has drawn our attention to particulate matter (PM2.5), which has been shown to correlate significantly with respiratory and cardiovascular systems. However, whether PM2.5 is causally associated with Alzheimer's syndrome or delirium is unclear.

METHODS

We retrieved the genetic summary data of PM2.5 from genome-wide association studies (GWAS). The genetic information for Alzheimer's disease was obtained from the IEU OpenGWAS project, and that for delirium was obtained from FinnGen. We used two-sample Mendelian randomization analysis (MR) to associate PM2.5 with Alzheimer's disease or delirium.

RESULTS

The odds ratio (OR) for Alzheimer's disease was 0.996 with a p-value of 0.443 using the inverse variance weighted algorithm, and the OR associated with the outcome variable of delirium was 0.393 with a p-value of 0.343.

CONCLUSION

With the exclusion of confounding factors, our findings do not support a genetic association between PM2.5 and Alzheimer's disease or delirium. Further population-based and experimental studies are needed to dissect the complex correlation between PM2.5 and Alzheimer's disease or delirium.

Temporal change and impact on air quality of an energy recovery plant using the M-BACI design in Gipuzkoa

A significant concern in our society is the potential impact on both health and the environment of air pollutants released during the incineration of waste. Therefore, it is crucial to conduct thorough control and monitoring measures. In this context, the objective of this research was to study the evolution of particulate matter (PM2.5) and associated trace elements during the period before and after the installation of an Energy Recovery Plant (ERP). For that, a descriptive and temporal analysis of PM2.5 concentration and composition were performed on two similar areas (impact/control) using the Before-After/Control-Impact (BACI) design and two periods (before from January 01, 2018 to February 06, 2020 and after from December 10, 2020 to September 30, 2022). Results showed a decrease in the levels of PM2.5 and associated trace elements is observed in the impact zone (IZ) and in the control zone (CZ) throughout the study period. In the case of PM2.5, the most notable decrease occurred in the period of the start-up of the ERP, a period that coincides with the confinement and restrictions of COVID, with a subsequent increase in both zones, without reaching the levels observed in the period prior to the start-up of the ERP. Selenium is the only trace element that increases significantly in the IZ. In conclusion, a decrease is observed for all pollutants except selenium in both zones, although less pronounced in the IZ. Since selenium already showed an upward trend in the phase prior to the start of the ERP, it is necessary to investigate its evolution and find out the possible cause.

The Association between Exposure to Fine Particulate Air Pollution and the Trajectory of Internalizing and Externalizing Behaviors during Late Childhood and Early Adolescence: Evidence from the Adolescent Brain Cognitive Development (ABCD) Study

BACKGROUND

Exposure to high levels of fine particulate matter (PM) with aerodynamic diameter ≤ 2.5 μ m (PM 2.5 ) via air pollution may be a risk factor for psychiatric disorders during adulthood. Yet few studies have examined associations between exposure and the trajectory of symptoms across late childhood and early adolescence.

OBJECTIVE

The current study evaluated whether PM 2.5 exposure at 9-11 y of age affects both concurrent symptoms as well as the longitudinal trajectory of internalizing and externalizing behaviors across the following 3 y. This issue was examined using multiple measures of exposure and separate measures of symptoms of internalizing disorders (e.g., depression, anxiety) and externalizing disorders (e.g., conduct disorder), respectively.

METHODS

In a sample of more than 10,000 youth from the Adolescent Brain Cognitive Development (ABCD) Study, we used a dataset of historical PM 2.5 levels and growth curve modeling to evaluate associations of PM 2.5 exposure with internalizing and externalizing symptom trajectories, as assessed by the Child Behavioral Check List. Three distinct measures of PM 2.5 exposure were investigated: annual average concentration during 2016, number of days in 2016 above the US Environmental Protection Agency (US EPA) 24-h PM 2.5 standards, and maximum 24-h concentration during 2016.

RESULTS

At baseline, higher number of days with PM 2.5 levels above US EPA standards was associated with higher parent-reported internalizing symptoms in the same year. This association remained significant up to a year following exposure and after controlling for PM 2.5 annual average, maximum 24-h level, and informant psychopathology. There was also evidence of an association between PM 2.5 annual average and externalizing symptom levels at baseline in females only.

DISCUSSION

Results suggested PM 2.5 exposure during childhood is associated with higher symptoms of internalizing and externalizing disorders at the time of exposure and 1 y later. In addition, effects of PM 2.5 exposure on youth internalizing symptoms may be most impacted by the number of days of exposure above US EPA standards in comparison with annual average and maximum daily exposure. https://doi.org/10.1289/EHP13427.

PPARγ activation ameliorates PM2.5-induced renal tubular injury by inhibiting ferroptosis and epithelial-mesenchymal transition

Exposure to fine particulate matter (PM2.5) has been associated with the development and progression of renal disease. Peroxisome proliferator-activated receptor gamma (PPARγ), a key transcription factor involved in inflammation as well as lipid and glucose metabolism, helps maintain the integrity of tubular epithelial cells. However, the precise role of PPARγ in PM2.5-induced tubular injury remains unclear. In this study, we investigated the regulatory effects of PPARγ on PM2.5-induced ferroptotic stress and epithelial-mesenchymal transition (EMT) in tubular (HK-2) cells. We found that downregulation of PPARγ expression was correlated with EMT in PM2.5-exposed cells. Pretreatment with the PPARγ agonist 15d-PGJ2 protected the cells from EMT by reducing ferroptotic stress, whereas that with the PPARγ antagonist GW9662 promoted EMT. Furthermore, pretreatment with ferrostatin-1 (Fer-1) significantly prevented PM2.5-induced EMT and downregulation of PPARγ expression. Notably, overexpression of PPARγ blocked PM2.5-induced downregulation of E-cadherin and GPX4 expression and upregulation of α-SMA expression. This study highlights the complex associations of PPARγ with ferroptosis and EMT in PM2.5-exposed tubular cells. Our findings suggest that PPARγ activation confers protection against PM2.5-induced renal injury.

PM2.5 exposure inhibits osteoblast differentiation by increasing the ubiquitination and degradation of Smad4

Increasing epidemiological evidence has shown that PM2.5 exposure is significantly associated with the occurrence of osteoporosis. It has been well demonstrated that PM2.5 exposure enhanced the differentiation and function of osteoclasts by indirectly causing chronic inflammation, while the mechanism in osteoblasts remains unclear. In our study, toxic effects were evaluated by direct exposure of 20-80 μg/ml PM2.5 to MC3T3-E1 cells and BMSCs. The results showed that PM2.5 exposure did not affect cell viability via proliferation and apoptosis, but significantly inhibited osteoblast differentiation in a dose-dependent manner. Osteogenic transcription factors Runx2 and Sp7 and other biomarkers Alp and Ocn decreased after PM2.5 exposure. RNA-seq revealed TGF-β signaling was involved in PM2.5 exposure inhibited osteoblast differentiation, which led to P-Smad1/5 and P-Smad2 reduction in the nucleus by increasing the ubiquitination and degradation of Smad4. At last, the inflammation response increased in MC3T3-E1 cells with PM2.5 exposure. Moreover, the mRNA levels of Mmp9 increased in bone marrow-derived macrophage cells treated with the conditional medium collected from MC3T3-E1 cells exposed to PM2.5. Overall, these results indicated that PM2.5 exposure inhibits osteoblast differentiation and concurrently increases the maturation of osteoclasts. Our study provides in-depth mechanistic insights into the direct impact of PM2.5 exposure on osteoblast, which would indicate the unrecognized role of PM2.5 on osteoporosis.

Particulate Matter Induces NLRP3 Inflammasome-Mediated Pyroptosis in Human Nasal Epithelial Cells

Background and Objectives

Air pollution, particularly particulate matter (PM), has a variety of adverse effects on human health. PM is known to induce cell death through various pathways, including pyroptosis. Despite its significance, research on PM-induced pyroptosis in nasal epithelial cells remains limited. This study aimed to explore PM-induced pyroptosis in cultured human nasal epithelial cells.

Methods

For the in vitro experiments, human nasal epithelial cells were cultured. Cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, while cell death was evaluated through propidium iodide (PI) staining and lactate dehydrogenase (LDH) release measurement. Protein expression levels related to pyroptosis were examined via western blot using antibodies against NOD-like receptor family, pyrin domain containing 3 (NLRP3), cleaved caspase-1 (CASP1 P20), gasdermin D (GSDMD)-N, and glyceraldehyde phosphate dehydrogenase. Immunofluorescent staining with a CASP1 P20 antibody was conducted to visualize cellular localization. Enzyme-linked immunosorbent assay was utilized to quantify interleukin (IL)-1β and IL-18 protein levels.

Results

Treatment with PM resulted in decreased cell viability, elevated LDH release, and intensified PI staining, indicating cell death. Pyroptosis was confirmed by the elevated expression of NLRP3, CASP1 P20, and GSDMD-N, along with increased levels of IL-1β and IL-18. Inhibiting the NLRP3 inflammasome with MCC950 reduced the PM-induced effects on protein expression and cytokine release, highlighting the role of the NLRP3 inflammasome in PM-triggered pyroptosis in human nasal epithelial cells.

Conclusion

We showed that PM triggers pyroptosis in human nasal epithelial cells, driven by NLRP3 inflammasome-dependent signaling pathways.

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM2.5) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

FGF10 protects against particulate matter-induced lung injury by inhibiting ferroptosis via Nrf2-dependent signaling

Particulate matter (PM) is considered the fundamental component of atmospheric pollutants and is associated with the pathogenesis of many respiratory diseases. Fibroblast growth factor 10 (FGF10) mediates mesenchymal-epithelial signaling and has been linked with the repair process of PM-induced lung injury (PMLI). However, the pathogenic mechanism of PMLI and the specific FGF10 protective mechanism against this injury are still undetermined. PM was administered in vivo into murine airways or in vitro to human bronchial epithelial cells (HBECs), and the inflammatory response and ferroptosis-related proteins SLC7A11 and GPX4 were assessed. The present research investigates the FGF10-mediated regulation of ferroptosis in PMLI mice models in vivo and HBECs in vitro. The results showed that FGF10 pretreatment reduced PM-mediated oxidative damage and ferroptosis in vivo and in vitro. Furthermore, FGF10 pretreatment led to reduced oxidative stress, decreased secretion of inflammatory mediators, and activation of the Nrf2-dependent antioxidant signaling. Additionally, silencing of Nrf2 using siRNA in the context of FGF10 treatment attenuated the effect on ferroptosis. Altogether, both in vivo and in vitro assessments confirmed that FGF10 protects against PMLI by inhibiting ferroptosis via the Nrf2 signaling. Thus, FGF10 can be used as a novel ferroptosis suppressor and a potential treatment target in PMLI.

Association between long-term exposure to air pollution and diabetic retinopathy: Evidence from the Fujian Eye Study

BACKGROUND

Diabetic retinopathy (DR), one of the most common microvascular complications of diabetes mellitus (DM), is a major contributor of vision impairment and blindness worldwide. Studies have shown that air pollution exposure is adversely associated with DM. However, evidence is scarce regarding how air pollution exposure affects DR. This study aimed to investigate the association between ambient air pollution exposure and DR risk.

METHODS

The study population was based on the Fujian Eye Study (FJES), an ophthalmologic, epidemiologic survey investigating the eye health condition of residents in Fujian Province from 2018 to 2019. Daily average concentrations of ambient air pollutants (PM2.5, PM10, SO2, NO2, and O3) were acquired from a high-resolution air quality dataset in China from 2013 to 2018. We used a logistic regression model to examine the associations between DR risk and long-term air pollution at various exposure windows.

RESULTS

A total of 2405 out of the 8211 participants were diagnosed with diabetes, among whom 183 had DR. Ambient air pollution, especially particulate matter (i.e., PM2.5 and PM10) and NO2 were positively associated with DR prevalence among all the study subjects. Ambient SO2 and O3 concentrations were not associated with DR prevalence. PM2.5 and NO2 seemed to be borderline significantly associated with increased prevalence of DR in subjects with DM, especially under the model adjusted for sex, age, BMI, SBP, and DBP.

CONCLUSIONS

These findings showed that long-term exposure to ambient particulate matter and NO2 was associated with a high DR risk in Fujian province, where ambient air pollution is relatively low.

Air pollution from biomass burning disrupts early adolescent cortical microarchitecture development

Exposure to outdoor particulate matter (PM 2.5 ) represents a ubiquitous threat to human health, and particularly the neurotoxic effects of PM 2.5 from multiple sources may disrupt neurodevelopment. Studies addressing neurodevelopmental implications of PM exposure have been limited by small, geographically limited samples and largely focus either on macroscale cortical morphology or postmortem histological staining and total PM mass. Here, we leverage residentially assigned exposure to six, data-driven sources of PM 2.5 and neuroimaging data from the longitudinal Adolescent Brain Cognitive Development Study (ABCD Study®), collected from 21 different recruitment sites across the United States. To contribute an interpretable and actionable assessment of the role of air pollution in the developing brain, we identified alterations in cortical microstructure development associated with exposure to specific sources of PM 2.5 using multivariate, partial least squares analyses. Specifically, average annual exposure (i.e., at ages 8-10 years) to PM 2.5 from biomass burning was related to differences in neurite development across the cortex between 9 and 13 years of age.

Fine particulate matter aggravates smoking induced lung injury via NLRP3/caspase-1 pathway in COPD

BACKGROUND

Exposure to noxious particles, including cigarette smoke and fine particulate matter (PM2.5), is a risk factor for chronic obstructive pulmonary disease (COPD) and promotes inflammation and cell death in the lungs. We investigated the combined effects of cigarette smoking and PM2.5 exposure in patients with COPD, mice, and human bronchial epithelial cells.

METHODS

The relationship between PM2.5 exposure and clinical parameters was investigated in patients with COPD based on smoking status. Alveolar destruction, inflammatory cell infiltration, and pro-inflammatory cytokines were monitored in the smoking-exposed emphysema mouse model. To investigate the mechanisms, cell viability and death and pyroptosis-related changes in BEAS-2B cells were assessed following the exposure to cigarette smoke extract (CSE) and PM2.5.

RESULTS

High levels of ambient PM2.5 were more strongly associated with high Saint George's respiratory questionnaire specific for COPD (SGRQ-C) scores in currently smoking patients with COPD. Combined exposure to cigarette smoke and PM2.5 increased mean linear intercept and TUNEL-positive cells in lung tissue, which was associated with increased inflammatory cell infiltration and inflammatory cytokine release in mice. Exposure to a combination of CSE and PM2.5 reduced cell viability and upregulated NLRP3, caspase-1, IL-1β, and IL-18 transcription in BEAS-2B cells. NLRP3 silencing with siRNA reduced pyroptosis and restored cell viability.

CONCLUSIONS

PM2.5 aggravates smoking-induced airway inflammation and cell death via pyroptosis. Clinically, PM2.5 deteriorates quality of life and may worsen prognosis in currently smoking patients with COPD.

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.

Developmental Toxicity of Fine Particulate Matter: Multifaceted Exploration from Epidemiological and Laboratory Perspectives

Particulate matter of size ≤ 2.5 μm (PM2.5) is a critical environmental threat that considerably contributes to the global disease burden. However, accompanied by the rapid research progress in this field, the existing research on developmental toxicity is still constrained by limited data sources, varying quality, and insufficient in-depth mechanistic analysis. This review includes the currently available epidemiological and laboratory evidence and comprehensively characterizes the adverse effects of PM2.5 on developing individuals in different regions and various pollution sources. In addition, this review explores the effect of PM2.5 exposure to individuals of different ethnicities, genders, and socioeconomic levels on adverse birth outcomes and cardiopulmonary and neurological development. Furthermore, the molecular mechanisms involved in the adverse health effects of PM2.5 primarily encompass transcriptional and translational regulation, oxidative stress, inflammatory response, and epigenetic modulation. The primary findings and novel perspectives regarding the association between public health and PM2.5 were examined, highlighting the need for future studies to explore its sources, composition, and sex-specific effects. Additionally, further research is required to delve deeper into the more intricate underlying mechanisms to effectively prevent or mitigate the harmful effects of air pollution on human health.

Assessment of cellular senescence potential of PM2.5 using 3D human lung fibroblast spheroids in vitro model

Background

Epidemiological studies demonstrate that particulate matter 2.5 (PM2.5) exposure closely related to chronic respiratory diseases. Cellular senescence plays an important role in many diseases. However, it is not fully clear whether PM2.5 exposure could induce cellular senescence in the human lung. In this study, we generated a three-dimensional (3D) spheroid model using isolated primary human lung fibroblasts (HLFs) to investigate the effects of PM2.5 on cellular senescence at the 3D level.

Methods

3D spheroids were exposed to 25-100 μg/ml of PM2.5 in order to evaluate the impact on cellular senescence. SA-β-galactosidase activity, cell proliferation, and the expression of key genes and proteins were detected.

Results

Exposure of the HLF spheroids to PM2.5 yielded a more sensitive cytotoxicity than 2D HLF cell culture. Importantly, PM2.5 exposure induced the rapid progression of cellular senescence in 3D HLF spheroids, with a dramatically increased SA-β-Gal activity. In exploiting the mechanism underlying the effect of PM2.5 on senescence, we found a significant increase of DNA damage, upregulation of p21 protein levels, and suppression of cell proliferation in PM2.5-treated HLF spheroids. Moreover, PM2.5 exposure created a significant inflammatory response, which may be at least partially associated with the activation of TGF-β1/Smad3 axis and HMGB1 pathway.

Conclusions

Our results indicate that PM2.5 could induce DNA damage, inflammation, and cellular senescence in 3D HLF spheroids, which may provide a new evidence for PM2.5 toxicity based on a 3D model which has been shown to be more in vivo-like in their phenotype and physiology than 2D cultures.

The role of lysosomes in airborne particulate matter-induced pulmonary toxicity

An investigation of the potential role of lysosomes in airborne particulate matter (APM) induced health risks is essential to fully comprehend the pathogenic mechanisms of respiratory diseases. It is commonly accepted that APM-induced lung injury is caused by oxidative stress, inflammatory responses, and DNA damage. In addition, there exists abundant evidence that changes in lysosomal function are essential for cellular adaptation to a variety of particulate stimuli. This review emphasizes that disruption of the lysosomal structure/function is a key step in the cellular metabolic imbalance induced by APMs. After being ingested by cells, most particles are localized within lysosomes. Thus, lysosomes become the primary locus where APMs accumulate, and here they undergo degradation and release toxic components. Recent studies have provided incontrovertible evidence that a wide variety of APMs interfere with the normal function of lysosomes. After being stimulated by APMs, lysosome rupture leads to a loss of lysosomal acidic conditions and the inactivation of proteolytic enzymes, promoting an inflammatory response by activating the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Moreover, APMs interfere with autophagosome production or block autophagic flux, resulting in autophagy dysfunction. Additionally, APMs disrupt the normal function of lysosomes in iron metabolism, leading to disruption on iron homeostasis. Therefore, understanding the impacts of APM exposure from the perspective of lysosomes will provide new insights into the detrimental consequences of air pollution.

Fine particulate matter PM2.5 and its constituent, hexavalent chromium induce acute cytotoxicity in human airway epithelial cells via inflammasome-mediated pyroptosis

PM2.5-induced airway injury contributes to an increased rate of respiratory morbidity. However, the relationship between PM2.5 toxicants and acute cytotoxic effects remains poorly understood. This study aimed to investigate the mechanisms of PM2.5- and its constituent-induced cytotoxicity in human airway epithelial cells. Exposure to PM2.5 resulted in dose-dependent cytotoxicity within 24 h. Among the PM2.5 constituents examined, Cr(VI) at the dose found in PM2.5 exhibited cytotoxic effects. Both PM2.5 and Cr(VI) cause necrosis while also upregulating the expression of proinflammatory cytokine transcripts. Interestingly, exposure to the conditioned PM, obtained from adsorption in the Cr(VI)-reducing agents, FeSO4 and EDTA, showed a decrease in cytotoxicity. Furthermore, PM2.5 mechanistically enhances programmed pyroptosis through the activation of NLRP3/caspase-1/Gasdermin D pathway and increase of IL-1β. These pyroptosis markers were reduced when exposure to conditioned PM. These findings provide a deeper understanding of mechanisms underlying PM2.5 and Cr(VI) in acute airway toxicity.

PM2.5 induce neurotoxicity via iron overload and redox imbalance mediated-ferroptosis in HT22 cells

PM2.5 is an important risk factor for the development and progression of cognitive impairment-related diseases. Ferroptosis, a new form of cell death driven by iron overload and lipid peroxidation, is proposed to have significant implications. To verify the possible role of ferroptosis in PM2.5-induced neurotoxicity, we investigated the cytotoxicity, intracellular iron content, iron metabolism-related genes, oxidative stress indices and indicators involving in Nrf2 and ferroptosis signaling pathways. Neurotoxicity biomarkers as well as the ferroptotic cell morphological changes were determined by Western Blot and TEM analysis. Our results revealed that PM2.5 induced cytotoxicity, lipid peroxidation, as indicated by MDA content, and neurotoxicity via Aβ deposition in a dose-related manner. Decreased cell viability and excessive iron accumulation in HT-22 cells can be partially blocked by ferroptosis inhibitors. Interestingly, GPX activity, Nrf2, and its regulated ferroptotic-related proteins (i.e. GPX4 and HO-1) were significantly up-regulated by PM2.5. Moreover, gene expression of DMT1, TfR1, IRP2 and FPN1 involved in iron homeostasis and NCOA4-dependent ferritinophagy were activated after PM2.5 exposure. The results demonstrated that PM2.5 triggered ferritinophagy-dependent ferroptotic cell death due to iron overload and redox imbalance. Activation of Nrf2 signaling pathways may confer a protective mechanism for PM2.5-induced oxidative stress and ferroptosis.

The mechanism underlying correlation of particulate matter-induced ferroptosis with inflammasome activation and iron accumulation in macrophages

Particulate matter (PM) is a global environmental hazard, which affects human health through free radical production, cell death induction, and immune responses. PM activates inflammasomes leading to excessive inflammatory responses and induces ferroptosis, a type of cell death. Despite ongoing research on the correlation among PM-induced ferroptosis, immune response, and inflammasomes, the underlying mechanism of this relationship has not been elucidated. In this study, we demonstrated the levels of PM-induced cell death and immune responses in murine macrophages, J774A.1 and RAW264.7, depending on the size and composition of particulate matter. PM2.5, with extraction ions, induced significant levels of cell death and immune responses; it induces lipid peroxidation, iron accumulation, and reactive oxygen species (ROS) production, which characterize ferroptosis. In addition, inflammasome-mediated cell death occurred owing to the excessive activation of inflammatory responses. PM-induced iron accumulation activates ferroptosis and inflammasome formation through ROS production; similar results were observed in vivo. These results suggest that the link between ferroptosis and inflammasome formation induced by PM, especially PM2.5 with extraction ions, is established through the iron-ROS axis. Moreover, this study can effectively facilitate the development of a new therapeutic strategy for PM-induced immune and respiratory diseases.

Environmental pollutants and phosphoinositide signaling in autoimmunity

Environmental pollution stands as one of the most critical challenges affecting human health, with an estimated mortality rate linked to pollution-induced non-communicable diseases projected to range from 20% to 25%. These pollutants not only disrupt immune responses but can also trigger immunotoxicity. Phosphoinositide signaling, a pivotal regulator of immune responses, plays a central role in the development of autoimmune diseases and exhibits high sensitivity to environmental stressors. Among these stressors, environmental pollutants have become increasingly prevalent in our society, contributing to the initiation and exacerbation of autoimmune conditions. In this review, we summarize the intricate interplay between phosphoinositide signaling and autoimmune diseases within the context of environmental pollutants and contaminants. We provide an up-to-date overview of stress-induced phosphoinositide signaling, discuss 14 selected examples categorized into three groups of environmental pollutants and their connections to immune diseases, and shed light on the associated phosphoinositide signaling pathways. Through these discussions, this review advances our understanding of how phosphoinositide signaling influences the coordinated immune response to environmental stressors at a biological level. Furthermore, it offers valuable insights into potential research directions and therapeutic targets aimed at mitigating the impact of environmental pollutants on the pathogenesis of autoimmune diseases. SYNOPSIS: Phosphoinositide signaling at the intersection of environmental pollutants and autoimmunity provides novel insights for managing autoimmune diseases aggravated by pollutants.

MitoQ Alleviated PM2.5 Induced Pulmonary Epithelial Cells Injury by Inhibiting Mitochondrial-Mediated Apoptosis

Background

Fine particulate matter (PM2.5), an important component of ambient air pollution, induces significant adverse health effects. MitoQuinone (MitoQ), a mitochondria-targeted antioxidant, has been reported to play a protective role in various diseases. However, the roles of MitoQ in PM2.5 induced pulmonary toxicity remains to be elucidated.

Methods

All the experiments were performed at Higher Educational Key Laboratory for Translational Oncology of Fujian Province, Putian City, China in 2023. Pulmonary epithelial cells (A549) were pretreated with 4 μM MitoQ for 2 h and exposed to PM2.5 for 24 h. Cell viability was tested through CCK8 assay. Oxidative stress state and active mitochondria was used to study MitoQ's effect on PM2.5 induced injury, and cell apoptosis was measured using a flow cytometer and analyzed by Bcl-2 family.

Results

MitoQ pretreatment significantly relieved a decreased cell viability, subsequently, MitoQ alleviated ROS production and prevented the reduction of T-AOC and GSH and increased the expression of NF-E2-related factor 2 (Nrf2) and p62 in A549 cells exposed to PM2.5. MitoQ restored the decreased mitochondrial dysfunction and dynamics disorder and inhibited activated mitochondrial-mediated apoptosis induced by PM2.5. Furthermore, the decreased ratio of Bcl-2/Bax and expression of Mcl-1 and the enhanced expression of Caspase-3 were reversed by MitoQ pretreatment.

Conclusion

MitoQ might be regarded as a potential drug to relieve PM2.5 induced pulmonary epithelial cells damage.

Interleukin-37 relieves PM2.5-triggered lung injury by inhibiting autophagy through the AKT/mTOR signaling pathway in vivo and in vitro

Autophagy mediates PM2.5-related lung injury (LI) and is tightly linked to inflammation and apoptosis processes. IL-37 has been demonstrated to regulate autophagy. This research aimed to examine the involvement of IL-37 in the progression of PM2.5-related LI and assess whether autophagy serves as a mediator for its effects.To create a model of PM2.5-related LI, this research employed a nose-only PM2.5 exposure system and utilized both human IL-37 transgenic mice and wild-type mice. The hIL-37tg mice demonstrated remarkable reductions in pulmonary inflammation and pathological LI compared to the WT mice. Additionally, they exhibited activation of the AKT/mTOR signaling pathway, which served to regulate the levels of autophagy and apoptosis.Furthermore, in vitro experiments revealed a dose-dependent upregulation of autophagy and apoptotic proteins following exposure to PM2.5 DMSO extraction. Simultaneously, p-AKT and p-mTOR expression was found to decrease. However, pretreatment with IL-37 demonstrated a remarkable reduction in the levels of autophagy and apoptotic proteins, along with an elevation of p-AKT and p-mTOR. Interestingly, pretreatment with rapamycin, an autophagy inducer, weakened the therapeutic impact of IL-37. Conversely, the therapeutic impact of IL-37 was enhanced when treated with 3-MA, a potent autophagy inhibitor. Moreover, the inhibitory effect of IL-37 on autophagy was successfully reversed by administering AKT inhibitor MK2206. The findings suggest that IL-37 can inhibit both the inflammatory response and autophagy, leading to the alleviation of PM2.5-related LI. At the molecular level, IL-37 may exert its anti autophagy and anti apoptosis effects by activating the AKT/mTOR signaling pathway.

Astaxanthin alleviates fine particulate matter (PM2.5)-induced lung injury in rats by suppressing ferroptosis and apoptosis

Objectives: Fine particulate matter (PM2.5), a small molecule particulate pollutant, can reach the lungs via respiration and cause lung damage. Currently, effective strategies and measures are lacking to prevent and treat the pulmonary toxicity of PM2.5. Astaxanthin (ASX), a natural xanthophyll carotenoid, has attracted attention due to its unique biological activity. Our research aims to probe into the prevention and treatment of ASX on PM2.5-induced lung injury and clarify its potential mechanism. Methods: Sprague-Dawley (SD) rats were given olive oil and different concentrations of ASX orally daily for 21 days. PM2.5 suspension was instilled into the trachea of rats every two days for one week to successfully develop the PM2.5 exposure model in the PM2.5-exposed and ASX-treated groups of rats. The bronchoalveolar lavage fluid (BALF) was collected, and the content of lung injury-related markers was detected. Histomorphological changes and expression of markers associated with oxidative stress, inflammation, iron death, and apoptosis were detected in lung tissue. Results: PM2.5 exposure can cause changes in lung histochemistry and increase the expression levels of TP, AKP, ALB, and LDH in the BALF. Simultaneously, inflammatory responses and oxidative stress were promoted in rat lung tissue after exposure to particulate matter. Additionally, ASX preconditioning can alleviate histomorphological changes, oxidative stress, and inflammation caused by PM2.5 and reduce PM2.5-related ferroptosis and apoptosis. Conclusion: ASX preconditioning can alleviate lung injury after PM2.5 exposure by inhibiting ferroptosis and apoptosis.

Mechanism of Interaction between hsa_circ_0002854 and MAPK1 Protein in PM2.5-Induced Apoptosis of Human Bronchial Epithelial Cells

Fine particulate matter (PM2.5) pollution increases the risk of respiratory diseases and death, and apoptosis is an important factor in the occurrence of respiratory diseases caused by PM2.5 exposure. In addition, circular RNAs (circRNAs) can interact with proteins and widely participate in physiological and pathological processes in the body. The aim of this study was to investigate the mechanism of circRNA and protein interaction on PM2.5-induced apoptosis of human bronchial epithelial cells (16HBE) in vitro. In this study, we exposed human bronchial epithelial cells to a PM2.5 suspension with different concentration gradients for 24 h. The results showed that apoptosis of 16HBE cells after PM2.5 treatment was accompanied by cell proliferation. After exposure of PM2.5 to 16HBE cells, circRNAs related to apoptosis were abnormally expressed. We further found that the expression of hsa_circ_0002854 increased with the increase in exposure concentration. Functional analysis showed that knocking down the expression of hsa_circ_0002854 could inhibit apoptosis induced by PM2.5 exposure. We then found that hsa_circ_0002854 could interact with MAPK1 protein and inhibit MAPK1 phosphorylation, thus promoting apoptosis. Our results suggest that hsa_circ_0002854 can promote 16HBE apoptosis due to PM2.5 exposure, which may provide a gene therapy target and scientific basis for PM2.5-induced respiratory diseases.

The association between PM2.5 concentration and the severity of acute asthmatic exacerbation in hospitalized children: A retrospective study in Chongqing, China

BACKGROUND

Ambient PM2.5 is associated with asthma exacerbation. The association between the concentration of PM2.5 and the severity of asthma exacerbation has yet to be thoroughly clarified. The study aims to explore the association between the piror 30 days average concentration of PM2.5 and the severity of acute asthma exacerbation in hospitalized children.

METHODS

A total of 269 children with acute exacerbation of asthma were enrolled and divided into three groups according to the PM2.5 exposure concentrations: group 1 (PM2.5: <37.5 μg/m3 ), group 2 (PM2.5: 37.5-75 μg/m3 ), group 3 (PM2.5: ≥75 μg/m3 ), respectively. The ordered logistic regression modeling was conducted to explore the influence of daily PM2.5 concentration on the clinical severity of children's asthma exacerbation. Multiple linear regression was conducted to explore the association between the concentration of PM2.5 and the length of stay in the hospital (LOS). We also conducted a receiver operating characteristic (ROC) curve analysis to explore the cutoff value of PM2.5 to predict the children's asthma exacerbation.

RESULTS

There was no statistical difference among the three groups of children in gender, age, body mass index, ethnicity, the first diagnosis of asthma, allergic history, passive smoke exposure, or family history of asthma. There was a statistically significant difference in many hospitalization characteristics (p < 0.05) among the three groups of children. Significant differences were found in terms of accessory muscles of respiration (p = 0.005), respiratory failure (p = 0.012), low respiratory tract infectious (p = 0.020), and the severity of asthma exacerbation (p < 0.001) among the three groups. PM2.5 concentration was primarily positively correlated to neutrophile inflammation. The ordered multivariate logistic regression model showed that higher PM2.5 concentrations were significantly associated with greater odds of more severe asthma exacerbation in one and two-pollutant models. The adjusted odds ratio of severe asthma exacerbation was 1.029 (1.009, 1.049) in the one-pollutant model. The most significant odds ratio of severe asthma exacerbation was 1.050 (1.027, 1.073) when controlling NO2 in the two-pollutant models. Multiple linear regression showed that PM2.5 concentration was significantly associated with longer LOS in both one-pollutant and two-pollutant models. By performing ROC analysis, the average daily concentration of 44.5 µg/m3 of PM2.5 (AUC = 0.622, p = 0.002) provided the best performance to predict severe asthma of children exacerbation with a sensitivity of 59.2% and a specificity of 63.8%.

CONCLUSION

The increased prior 30 days average concentration of PM2.5 was associated with greater asthma exacerbation severity and longer length of stay in the hospital of children with asthma exacerbation.

PM2.5 mediates mouse testis Sertoli TM4 cell damage by reducing cellular NAD. Toxicol Mech Methods 2023;33:636-645. [PMID: 37202861 DOI: 10.1080/15376516.2023.2215862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

OBJECTIVE

This study aims to explore the mechanism of PM2.5 damage to the reproductive system of male mice.

METHODS

Mouse testis Sertoli TM4 cells were divided into four groups: a control group (no additional ingredients except for medium), PM2.5 group (medium containing 100 μg/mL PM2.5), PM2.5 + NAM group (medium containing 100 μg/mL PM2.5 and 5 mM NAM), and NAM group (medium containing 5 mM nicotinamide) and cultured in vitro for 24 or 48 h. The apoptosis rate of TM4 cells was measured using flow cytometry, the intracellular levels of NAD+ and NADH were detected using an NAD+/NADH assay kit, and the protein expression levels of SIRT1 and PARP1 were determined by western blotting.

RESULTS

Mouse testis Sertoli TM4 cells exposed to PM2.5 demonstrated an increase in the apoptosis rate and PARP1 protein expression, albeit a decrease in NAD+, NADH, and SIRT1 protein levels (p = 0.05). These changes were reversed in the group treated with a combination of PM2.5 and nicotinamide (p = 0.05).

CONCLUSION

PM2.5 can cause Sertoli TM4 cell damage in mouse testes by decreasing intracellular NAD+ levels.

Europium-Functionalized Graphitic Carbon Nitride for Efficient Chemiluminescence Detection of Singlet Oxygen

Enhancing the sensitivity and selectivity of chemiluminescence (CL) sensors for detecting chemical species in complex samples poses a significant challenge in nanoparticle surface engineering. Graphitic carbon nitride (CN) shows promise but suffers from weak CL intensity and unknown luminescence mechanisms. In this study, we propose a nitrogen defect strategy to enhance the CL efficiency of europium-functionalized graphitic carbon nitride (Eu-CNNPs). By controlling the dosage of the europium modification, we can adjust the nitrogen defect content to reduce the energy gap and improve the CL performance. Remarkably, Eu-CNNPs with rich nitrogen defects exhibit strong chemiluminescence emission specifically for singlet oxygen (1O2) without responding to other reactive oxygen species (ROS). Building upon this finding, we developed a direct, selective, and sensitive CL sensing platform for 1O2 in PM2.5 and monitored 1O2 production in photosensitizers without interference from metal ions. Through extensive experiments, we attribute the 1O2-driven CL response to the presence of abundant nitrogen defects in the CN material, accelerating electron transfer and yielding a high generation of 1O2. Furthermore, chemiluminescence resonance energy transfer (CRET) between (1O2)2* (1O2 dimeric aggregate) and Eu-CNNPs contributes to strong CL emission. This work provides insights into enhancing the CL performance of CN and offers new possibilities for advancing the practical analysis of nanomaterials using the intriguing mechanism of nitrogen defects.

PM2.5 contributed to pulmonary epithelial senescence and ferroptosis by regulating USP3-SIRT3-P53 axis

Pulmonary epithelial cells act as the first line of defense against various air pollutant particles. Previous studies have reported that particulate matter 2.5 (PM2.5) could trigger pulmonary inflammation and fibrosis by inducing pulmonary epithelial senescence and ferroptosis. Sirtuin 3 (SIRT3) is one of critical the mitochondrial NAD+-dependent deacetylases, exerting antioxidant and anti-aging effects in multiple diseases. The present study aimed to explore the role of SIRT3 in PM2.5-induced lung injury as well as possible mechanisms. The role of SIRT3 in PM2.5-induced lung injury was investigated by SIRT3 genetic depletion, adenovirus-mediated overexpression in type II alveolar epithelial (AT2) cells, and pharmacological activation by melatonin. The protein level and activity of SIRT3 in lung tissues and AT2 cells were significantly downregulated after PM2.5 stimulation. SIRT3 deficiency in AT2 cells aggravated inflammatory response and collagen deposition in PM2.5-treated lung tissues. RNA-sequence and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the differentially expressed genes (DEGs) between SIRT3 flox and SIRT3 CKO mice were mainly enriched in ferroptosis and cellular longevity. Western blot further showed that SIRT3 deficiency in AT2 cells significantly upregulated the proteins associated with ferroptosis and cell senescence in PM2.5-treated lung tissues. In vitro experiments also showed that SIRT3 overexpression could decrease the levels of ferroptosis and cell senescence in PM2.5-treated AT2 cells. In addition, we found that PM2.5 could increase the acetylation of P53 via triggering DNA damage in AT2 cells. And SIRT3 could deacetylate P53 at lysines 320 (K320), thus reducing its transcriptional activity. PM2.5 decreased the protein level of SIRT3 by inducing proteasome pathway through downregulating USP3. Finally, we found that SIRT3 agonist, melatonin treatment could alleviate PM2.5-induced senescence and ferroptosis in mice. In conclusion, targeting USP3-SIRT3-P53 axis may be a novel therapeutic strategy against PM2.5-induced pulmonary inflammation and fibrosis by decreasing pulmonary epithelial senescence and ferroptosis.

Salidroside pretreatment alleviates PM2.5 caused lung injury via inhibition of apoptosis and pyroptosis through regulating NLRP3 Inflammasome

Ambient fine particulate matter (PM_2.5) is considered a leading cause of pathogenic particulate matter induced lung injury. And Salidroside (Sal), the major bioactive constituent isolated from Rhodiola rosea L., has been shown to ameliorate lung injury in various conditions. To uncover the possible therapy for PM_2.5 related pulmonary disease, we evaluated the protective role of Sal pre-treatment on PM_2.5 induced lung injury in mice by utilizing the survival analysis, hematoxylin and eosin (H&E) staining, lung injury score, lung wet-to-dry weight ratio, enzyme-linked immunosorbent assay (ELISA) kits, immunoblot, immunofluorescence, and transmission electron microscopy (TEM). Impressively, our findings strongly indicated Sal as an effective precaution against PM_2.5 induced lung injury. Pre-administration of Sal before PM_2.5 treatment reduced the mortality within 120 h and alleviated inflammatory responses by reducing the release of proinflammatory cytokines, including TNF-α, IL-1β, and IL-18. Meanwhile, Sal pretreatment blocked apoptosis and pyroptosis that introduced the tissue damage under PM_2.5 treatment via regulating Bax/Bcl-2/caspase-3 and NF-κB/NLRP3/caspase-1 signal pathways. In summary, our research demonstrated that Sal could be a potential preventative therapy for PM_2.5 caused lung injury by inhibiting the initiation and development of apoptosis and pyroptosis through down-regulating NLRP3 inflammasome pathway.

Coelonin protects against PM2 .5 -induced macrophage damage via suppressing TLR4/NF-κB/COX-2 signaling pathway and NLRP3 inflammasome activation in vitro

One of the important monitoring indicators of the air pollution is atmospheric fine particulate matter (PM_2.5 ), which can induce lung inflammation after inhalation. Coelonin can alleviate PM_2.5 -induced macrophage damage through anti-inflammation. However, its molecular mechanism remains unclear. We hypothesized that macrophage damage may involve the release of inflammatory cytokines, activation of inflammatory pathways, and pyrosis induced by inflammasome. In this study, we evaluated the anti-inflammation activity of coelonin in PM_2.5 -induced macrophage and its mechanism of action. Nitric oxide (NO) and reactive oxygen species (ROS) production were measured by NO Assay kit and dichlorofluorescein-diacetate (DCFH-DA), and apoptosis were measured by Flow cytometry and TUNEL staining. The concentration of inflammatory cytokines production was measured with cytometric bead arrays and ELISA kits. The activation of NF-κB signaling pathway and NLRP3 inflammasome were measured by immunofluorescence, quantitative reverse transcription-polymerase chain reaction and western blot. As expected, coelonin pretreatment reduced NO production significantly as well as alleviated cell damage by decreasing ROS and apoptosis. It decreased generation of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in PM_2.5 -induced RAW264.7 and J774A.1 cells. Moreover, coelonin markedly inhibited upregulating the expression of toll-like receptor (TLR)4 and cyclo-oxygenase (COX)-2, blocked activation of p-nuclear factor-kappa B (NF-κB) signaling pathway, and suppressed expression of NLRP3 inflammasome, ASC, GSDMD, IL-18 and IL-1β. In conclusion, the results showed that coelonin could protect against PM_2.5 -induced macrophage damage via suppressing TLR4/NF-κB/COX-2 signaling pathway and NLRP3 inflammasome activation in vitro.

Sipeimine attenuates PM2.5-induced lung toxicity via suppression of NLRP3 inflammasome-mediated pyroptosis through activation of the PI3K/AKT pathway

Exposure to fine particulate matter (PM2.5), an environmental pollutant, significantly contributes to the incidence of and risk of mortality associated with respiratory diseases. Sipeimine (Sip) is a steroidal alkaloid in fritillaries that exerts antioxidative and anti-inflammatory effects. However, protective effect of Sip for lung toxicity and its mechanism to date remains poorly understood. In the present study, we investigated the lung-protective effect of Sip via establishing the lung toxicity model of rats with orotracheal instillation of PM2.5 (7.5 mg/kg) suspension. Sprague-Dawley rats were intraperitoneally administered with Sip (15 mg/kg or 30 mg/kg) or vehicle daily for 3 days before instillation of PM2.5 suspension to establish the model of lung toxicity. The results found that Sip significantly improved pathological damage of lung tissue, mitigated inflammatory response, and inhibited lung tissue pyroptosis. We also found that PM2.5 activated the NLRP3 inflammasome as evidenced by the upregulation levels of NLRP3, cleaved-caspase-1, and ASC proteins. Importantly, PM2.5 could trigger pyroptosis by increased levels of pyroptosis-related proteins, including IL-1β, cleaved IL-1β, and GSDMD-N, membrane pore formation, and mitochondrial swelling. As expected, all these deleterious alterations were reversed by Sip pretreatment. These effects of Sip were blocked by the NLRP3 activator nigericin. Moreover, network pharmacology analysis showed that Sip may function via the PI3K/AKT signaling pathway and animal experiment validate the results, which revealed that Sip inhibited NLRP3 inflammasome-mediated pyroptosis by suppressing the phosphorylation of PI3K and AKT. Our findings demonstrated that Sip inhibited NLRP3-mediated cell pyroptosis through activation of the PI3K/AKT pathway in PM2.5-induced lung toxicity, which has a promising application value and development prospect against lung injury in the future.

Pollutant-induced pyroptosis in humans and other animals

Pyroptosis is a form of lytic cell death with pro-inflammatory characteristics, induced upon the activation of certain inflammatory caspases by inflammasome complexes such as NLRP3 inflammasome. Gasdermin proteins as the mediators of pyroptosis form cell membrane pores upon activation, which release certain cellular contents into the extracellular space including inflammatory cytokines such as IL-1β and IL-18, and also damage the integrity of the cell membrane. Gasdermins have been implicated in autoimmune and inflammatory diseases, infectious diseases, deafness and cancer. Mostly in the last 2 years, diverse pollutant types including particulate matter, cadmium and polystyrene microplastics were reported to induce pyroptotic cell death in diverse tissues from mammals to birds. In the present study, we review our current understanding of pollutant-induced pyroptosis as well as current knowledge of upstream events leading to pyroptotic cell death upon exposure to pollutants.

Particulate matter induces ferroptosis by accumulating iron and dysregulating the antioxidant system

Particulate matter is an air pollutant composed of various components, and has adverse effects on the human body. Particulate matter is known to induce cell death by generating an imbalance in the antioxidant system; however, the underlying mechanism has not been elucidated. In the present study, we demonstrated the cytotoxic effects of the size and composition of particulate matter on small intestine cells. We found that particulate matter 2.5 (PM2.5) with extraction ion (EI) components (PM2.5 EI), is more cytotoxic than PM containing only polycyclic aromatic hydrocarbons (PAHs). Additionally, PM-induced cell death is characteristic of ferroptosis, and includes iron accumulation, lipid peroxidation, and reactive oxygen species (ROS) generation. Furthermore, ferroptosis inhibitor as liproxstatin-1 and iron-chelator as deferiprone attenuated cell mortality, lipid peroxidation, iron accumulation, and ROS production after PM2.5 EI treatment in human small intestinal cells. These results suggest that PM2.5 EI may increase ferroptotic-cell death by iron accumulation and ROS generation, and offer a potential therapeutic clue for inflammatory bowel diseases in human small intestinal cells. [BMB Reports 2023; 56(2): 96-101].

Particulate matter induces ferroptosis by accumulating iron and dysregulating the antioxidant system

Particulate matter is an air pollutant composed of various components, and has adverse effects on the human body. Particulate matter is known to induce cell death by generating an imbalance in the antioxidant system; however, the underlying mechanism has not been elucidated. In the present study, we demonstrated the cytotoxic effects of the size and composition of particulate matter on small intestine cells. We found that particulate matter 2.5 (PM2.5) with extraction ion (EI) components (PM2.5 EI), is more cytotoxic than PM containing only polycyclic aromatic hydrocarbons (PAHs). Additionally, PM-induced cell death is characteristic of ferroptosis, and includes iron accumulation, lipid peroxidation, and reactive oxygen species (ROS) generation. Furthermore, ferroptosis inhibitor as liproxstatin-1 and iron-chelator as deferiprone attenuated cell mortality, lipid peroxidation, iron accumulation, and ROS production after PM2.5 EI treatment in human small intestinal cells. These results suggest that PM2.5 EI may increase ferroptotic-cell death by iron accumulation and ROS generation, and offer a potential therapeutic clue for inflammatory bowel diseases in human small intestinal cells. [BMB Reports 2023; 56(2): 96-101].

Ferroptosis is involved in PM2.5-induced acute nasal epithelial injury via AMPK-mediated autophagy

PM2.5 is one of the main harmful environmental pollutants and can damage nasal epithelial carriers to worsen allergic rhinitis. Ferroptosis is a novel form of regulated cell death with iron-dependent lipid peroxidation. However, whether ferroptosis is involved in PM2.5-induced nasal epithelial injury has not been elucidated. To verify the vital role of ferroptosis in PM2.5-induced nasal epithelial injury and further explore the potential mechanism, we detected intracellular iron content, ROS release and lipid peroxidation and ferroptosis-related proteins in vitro as well as the pathological changes in the nasal epithelium and the levels of proinflammatory factors in nasal lavage fluid in vivo. Our results showed that PM2.5 exposure led to oxidative stress, labile iron accumulation and lipid peroxidation in HNEPCs. In addition, the expression levels of xCT, GPx4, FTH1 and FTL in HNEPCs were greatly inhibited by PM2.5. Treatment with the ferroptosis inhibitors deferoxamine (DFO) and ferrostatin-1 (Fer-1) significantly reversed the toxicity of PM2.5 to human nasal epithelial cells (HNEPCs). Mechanistically, AMPK-mediated autophagy was initiated during PM2.5 exposure, which drove ferroptosis of HNEPCs. Autophagy inhibitor remarkably improved cell death, oxidative stress, labile iron accumulation, lipid peroxidation, and the downregulated expression of xCT, GPx4, FTH1 and FTL in HNEPCs induced by PM2.5. Furthermore, an AMPK inhibitor (Compound C, CC) and siRNA-AMPKα suppressed autophagy activation and ferroptosis stimulated by PM2.5. In vivo, Fer-1 reduced nasal epithelial injury and mucus secretion in PM2.5-exposed mice. In addition, CC significantly improved nasal epithelial damage and proinflammatory factor production in mice caused by PM2.5 intranasal treatment. In addition, CC greatly inhibited autophagy activation but reversed the downregulation of GPX4 and FTH1 induced by PM2.5 in the nasal epithelium of mice. Together, these data suggest that AMPK-mediated autophagy plays an important role in PM2.5-induced ferroptosis and that AMPK might be a potential treatment target for PM2.5-induced nasal epithelial injury.

Organic extracts in PM2.5 are the major triggers to induce ferroptosis in SH-SY5Y cells

As a major air pollutant, PM2.5 can induce apoptosis of nerve cells, causing impairment of the learning and memory capabilities of humans and animals. Ferroptosis is a newly discovered way of programmed cell death. It is unclear whether the neurotoxicity induced by PM2.5 is related to the ferroptosis of nerve cells. In this study, we observed the changes in ferroptosis hallmarks of SH-SY5Y cells after exposure to various doses (40, 80, and 160 μg/mL PM2.5) for 24 h, exposure to 40 μg/mL PM2.5 for various times (24, 48, and 72 h), as well as exposure to various components (Po, organic extracts; Pw, water-soluble extracts; Pc, carbon core component). The results showed that PM2.5 reduced the cell viability, the content of GSH, and the activity of GSH-PX and SOD in SH-SY5Y cells with exposure dose and duration increasing. On the other hand, PM2.5 increased the content of iron, MDA, and the level of lipid ROS in SH-SY5Y cells with exposure dose and duration increasing. Additionally, PM2.5 reduced the expression levels of HO-1, NRF2, SLC7A11, and GPX4. The ferroptosis inhibitors Fer-1 and DFO significantly increase the cells viabilities and significantly reversed the changes of other above ferroptosis hallmarks. We also observed the different effects on ferroptosis hallmarks in the SH-SY5Y cells exposed to PM2.5 (160 μg/mL) and its various components (organic extracts, water-soluble extracts, and carbon core) for 24 h. We found that only the organic extracts shared similar results with PM2.5 (160 μg/mL). This study demonstrated that PM2.5 induced ferroptosis of SH-SY5Y cells, and organic extracts might be the primary component that caused ferroptosis.

Co-exposure of PM2.5 and high-fat diet induce lipid metabolism reprogramming and vascular remodeling

Fine particulate matter (PM_2.5) exposure has been proved to increase the cardiovascular disease risk. However, there is a lack of comprehensive knowledge on whether a high-fat diet (HFD) affects PM_2.5-induced cardiovascular disease. The purpose of this study was to investigate the impairment of lipid metabolism and vascular function by PM_2.5 and HFD exposure in ApoE^-/- mice. Oil red O staining indicated that co-treatment of PM_2.5 and HFD resulted in markedly lipid deposition in the mice aorta. Blood biochemical analysis demonstrated that co-exposure of PM_2.5 and HFD could cause dyslipidemia in vivo. Vascular Doppler ultrasound and histopathological analysis found that the functional and structural alterations with fibrosis and calcified remodeling of the vessels were detected after PM_2.5 and HFD exposure. For in-depth study, the genome-wide transcriptional analysis performed in macrophages was further revealed that the endoplasmic reticulum stress, immune system process, regulation of cell proliferation etc. were response to PM_2.5 exposure; while Lipid and atherosclerosis signaling pathways had a critical role in PM_2.5-induced vascular injury. Results from validation experiments manifested that the release of supernatant in PM_2.5- or ox-LDL-treated macrophages could decrease the cell viability and increase the lipid ROS in vascular smooth muscle cells (VSMCs). Moreover, the up-regulations of CCL2, IL-6 and IL-1β in aortic arch of mice were observed after co-exposure with PM_2.5 and HFD. Our data hinted that PM_2.5 could affect the lipid metabolism reprogramming and induce vascular remodeling, accompanied with synergistic effects of HFD.

Fibroblast growth factor 10 protects against particulate matter-induced lung injury by inhibiting oxidative stress-mediated pyroptosis via the PI3K/Akt/Nrf2 signaling pathway

Particulate matter (PM) is a major environmental contaminant that causes and worsens respiratory diseases. Fibroblast growth factor 10 (FGF10), a paracrine fibroblast growth factor that specifically stimulates repair and regeneration after injury, has been shown to protect against PM-induced lung injury. However, the underlying mechanisms are still unclear. In this study, the protective effects of FGF10 were investigated using a PM-induced lung injury mouse model in vivo and BEAS-2B cells in vitro. According to the findings, FGF10 treatment alleviated PM-induced oxidative damage and pyroptosis in vivo and in vitro. Mechanistically, FGF10 activated antioxidative Nrf2 signaling. Inhibition of PI3K signaling with LY294002 or Nrf2 signaling with ML385 revealed that FGF10-mediated lung protection was mediated by the PI3K/Akt/Nrf2 pathway. These results collectively indicate that FGF10 inhibits oxidative stress-mediated pyroptosis via the PI3K/Akt/Nrf2 pathway, suggesting a possible therapy for PM-induced lung injury.

A comprehensive understanding of ambient particulate matter and its components on the adverse health effects based from epidemiological and laboratory evidence

The impacts of air pollution on public health have become a great concern worldwide. Ambient particulate matter (PM) is a major air pollution that comprises a heterogeneous mixture of different particle sizes and chemical components. The chemical composition and physicochemical properties of PM change with space and time, which may cause different impairments. However, the mechanisms of the adverse effects of PM on various systems have not been fully elucidated and systematically integrated. The Adverse Outcome Pathway (AOP) framework was used to comprehensively illustrate the molecular mechanism of adverse effects of PM and its components, so as to clarify the causal mechanistic relationships of PM-triggered toxicity on various systems. The main conclusions and new insights of the correlation between public health and PM were discussed, especially at low concentrations, which points out the direction for further research in the future. With the deepening of the study on its toxicity mechanism, it was found that PM can still induce adverse health effects with low-dose exposure. And the recommended Air Quality Guideline level of PM_2.5 was adjusted to 5 μg/m³ by World Health Organization, which meant that deeper and more complex mechanisms needed to be explored. Traditionally, oxidative stress, inflammation, autophagy and apoptosis were considered the main mechanisms of harmful effects of PM. However, recent studies have identified several emerging mechanisms involved in the toxicity of PM, including pyroptosis, ferroptosis and epigenetic modifications. This review summarized the comprehensive evidence on the health effects of PM and the chemical components of it, as well as the combined toxicity of PM with other air pollutants. Based on the AOP Wiki and the mechanisms of PM-induced toxicity at different levels, we first constructed the PM-related AOP frameworks on various systems.

Wood smoke particulate matter (WSPM2.5) induces pyroptosis through both Caspase-1/IL-1β/IL-18 and ATP/P2Y-dependent mechanisms in human bronchial epithelial cells

Emerging evidences have linked the air pollution particulate matters, especially the fine particulate matter PM2.5, to the disease development of chronic obstructive pulmonary disease (COPD). Our previous studies reported that biofuel PM2.5 can induce devastated damage of human bronchial epithelial cells, this study aims to further investigate the underlying molecular mechanisms how biofuel PM2.5 induces bronchial epithelial cell death and dysfunction. In this study, biofuel PM2.5 extracted from wood smoke (WSPM2.5) was used according to our previous publication. A 16-HBE cell line was used as the cell model. Results showed that: Firstly, WSPM2.5 induced significant pyroptosis in 16-HBE cells, reflected by the typical changes including elevated release of lactate dehydrogenase release (LDH) and activated activity and expression of Caspase-1/IL-1β/IL-18 signaling pathway. Then, specific inhibitors for both Caspases (Z-VAD-FMK) and Caspase-1 (VX-765), as well as specific siRNA knockdown of IL-1β all effectively attenuated the WSPM2.5-induced upregulation of downstream inflammatory cytokines and chemokines (IL-6, IL-8, CXCL-1, CXCL-2, etc), respectively. Notably, WSPM2.5 caused a novel increase of intracellular-to-extracellular ATP secretion, which could also contribute to the WSPM2.5-induced pyroptosis and inflammation by activating the Caspase-1/IL-1β/IL-18 signaling pathway through possible autocrine and/or paracrine mechanisms. Antagonism of ATP (Apyrase) or specific siRNA knockdown against ATP receptors (P2Y2 and P2Y7) both significantly inhibited the WSPM2.5-induced pyroptosis and inflammation. These results add up to the current knowledge and bring up novel insights that WSPM2.5 could induce significant pyroptosis and inflammation of human bronchial epithelial cells, through both a classic NLRP3/Caspase-1/IL-1β-dependent and a novel ATP/P2Y-dependent mechanisms.

PM2.5 inhibits system Xc- activity to induce ferroptosis by activating the AMPK-Beclin1 pathway in acute lung injury

Urban airborne fine particulate matter (PM2.5) is a global pollution source that has been strongly related to multiple respiratory diseases involving various types of regulated cell death (RCD). However, the role of ferroptosis, a novel form of RCD, in PM2.5-induced acute lung injury (ALI), has not been elucidated. Herein, we define the role and mechanism of ferroptosis in a PM2.5-induced ALI model. First, we demonstrated that lipid peroxidation and iron accumulation were significantly enhanced in ALI models and were accompanied by activation of the AMP-activated protein kinase (AMPK)-Beclin1 signaling pathway and inhibition of the key subunit SLC7A11 of System Xc-. However, these abnormalities were partially reversed by ferroptosis inhibitors. We further revealed that Beclin1 knockdown or overexpression ameliorated or exacerbated PM2.5-induced ferroptosis, respectively. Mechanistically, we verified that Beclin1 blocks System Xc- activity to trigger ferroptosis by directly binding to SLC7A11. Finally, knockdown of Beclin1 by AAV-shRNA or inhibition of AMPK, an upstream activator of Beclin1, ameliorated PM2.5-induced ferroptosis and ALI. Taken together, our results revealed that ferroptosis plays a novel role in PM2.5-induced ALI and elucidated the specific mechanism involving the AMPK-Beclin1 pathway and System Xc-, which may provide new insight into the toxicological effects of PM2.5 on respiratory problems.

PM2.5 Exposure Induces Lung Injury and Fibrosis by Regulating Ferroptosis via TGF-β Signaling

Background. Lung fibrosis is a severe lung disorder featured by chronic nonspecific inflammation of the interstitial lung and deposition of collagen, leading to lung dysfunction. It has been identified that ferroptosis is involved in the progression of lung injury. Particulate matter (PM2.5) is reported to be correlated with the incidence of pulmonary fibrosis. However, mechanisms underlying ferroptosis in PM2.5-related lung fibrosis is unclear. In this study, we aimed to explore the effect of PM2.5 on ferroptosis in lung fibrosis and the related molecular mechanisms. Methods. PM2.5-treated mouse model and cell model were established. Fibrosis and tissue damage were measured by Masson’s trichrome staining and HE staining. Fibrosis biomarkers, such as α-SMA, collagen I, and collagen III, were examined by histological analysis. The ferroptosis phenotypes, including the levels of iron, Fe2+, MDA, and GSH, were measured by commercial kits. ROS generation was checked by DCFH-DA. The oxidative stress indicators, 3-nitro-L-tyrosine (3 $\prime$ -NT), 4-HNE, and protein carbonyl, were checked by enzyme linked immunosorbent assay (ELISA). The thiobarbituric acid reactive substances (TBARS) and GSH/GSSG ratio were assessed by TBARS assay kit and GSH/GSSG assay kit, respectively. TGF-β signaling was detected by Western blotting. Results. PM2.5 induced the lung injury and fibrosis in the mice model, along with elevated expression of fibrosis markers. PM2.5 enhanced oxidative stress in the lung of the mice. The SOD2 expression was reduced, and NRF2 expression was enhanced in the mice by the treatment with PM2.5. PM2.5 triggered ferroptosis, manifested as suppressed expression of GPX4 and SLC7A11, decreased levels of iron, Fe2+, and MDA, and increased GSH level in mouse model and cell model. The TGF-β and Smad3 signaling was inhibited by PM2.5. ROS inhibitor NAC reversed PM2.5-regulated ROS and ferroptosis in primary mouse lung epithelial cells. Conclusions. Therefore, we concluded that PM2.5 exposure induced lung injury and fibrosis by inducing ferroptosis via TGF-β signaling.