Short-term PM2.5 exposure induces transient lung injury and repair

Immune-epithelial cell interactions in lung development, homeostasis and disease

The importance of the crosstalk between lung epithelial and immune cells, which emerges from early development and lasts throughout life, is corroborated by a growing body of scientific evidence. This communication not only has a role in driving lung morphogenesis during development, but it is also required in adulthood for the maintenance of homeostasis and repair following infection or injury. Disruption of the intricate immune-epithelial crosstalk can lead to diseases such as COPD and IPF. In this review we summarise the current knowledge regarding the communication between various immune and epithelial cells in development, homeostasis, regeneration and disease, while identifying the current gaps in our knowledge required to facilitate the development of more effective therapies.

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.

Particulate matter induces depression-like behavior through systemic inflammation and brain-derived neurotrophic factors

Particulate matter (PM) has always received widespread attention, PM2.5 pollution is associated with many adverse effects, including cardiovascular, respiratory and metabolic diseases and mood disorders. However, the underlying mechanisms are not yet clear. In this study, the small animal whole body inhalation exposure system collected real-time PM2.5 in the real environment, which can truly reflect the presence status of PM2.5 in the atmospheric environment. This study investigated the depressive like behavior of mice exposed to PM2.5 for a long time and proved its molecular mechanism through RNA-seq. C57BL/6 male mice were exposed to ambient air together with control mice, who breathed air filtered through high-efficiency air particulate filters. Depression like behavior was observed in mice exposed to PM for 4, 6, and 8 weeks through behavioral experiments, EEG signals, and pathological sections. RNA-seq results indicated that the depressive like behavior of mice exposed to PM2.5 might be related to pro-inflammatory and anti-inflammatory cytokines, as well as the BDNF pathways in the hippocampus and olfactory bulb. This study suggests that PM2.5 may induce depression in mice through the MAPK/CREB/BDNF pathway. ENVIRONMENTAL IMPLICATION: Atmospheric particulate matter has been classified as Class 1 pollutant by the International Agency for Research on Cancer. Current research mainly believed that PM2.5 seriously affected lung health, but there was little research on the effects of PM2.5 on other organs. With the improvement of quality of life, people were paying more attention to mental health, while there is little research on the effects of PM2.5 on brain. This study simulated a real PM2.5 exposure environment and explored the effects of PM2.5 on the brain of mice, provided a solid scientific basis for inducing depression after PM2.5 exposure.

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.

Individual and joint exposure to air pollutants and patterns of multiple chronic conditions

Existing research on the detrimental effects of air pollution and its mixture on multiple chronic conditions (MCC) is not yet fully recognized. Our objective was to examine if individual and joint exposure to air pollution is associated with the incidence and patterns of MCC. Totally 10,231 CHARLS 2015 participants aged over 45 years and 1,938 without MCC were followed up in 2018 and 2020. Residential-levelcumulative personal exposure concentrations of PM1, PM10, PM2.5, CO, O3, NO2, SO2, NO3-, Cl-, NH4+, and SO42- at the residential level were determined utilizing a spatio-temporal random forest model with a spatial resolution of 0.1° × 0.1°. In the cross-sectional and longitudinal research, logistic regression, cox regression analysis, and quantile g-computation were utilized to estimate the single and joint effect with MCC and its patterns, respectively. Interaction analyses and stratified analyses were also performed. A correlation was observed between the prevalence of cardiovascular illnesses and the presence of all 11 major air pollutants. PM2.5, PM10, NH4+, NO3-, CO, and SO42- are associated with an increased frequency of respiratory disorders. An increase of PM2.5, PM1, PM10, NO2, and SO2 (a 10 µg/m3 rise), CO (a 0.1 mg/m3 rise), and PMCs (Cl-, NH4+, NO3-, and SO42-) (a 1 µg/m3 rise) corresponded to the HRs (95% CI) for developing MCC of 1.194 (95% CI: 1.043, 1.367), 1.362 (95% CI: 1.073, 1.728), 1.115 (95% CI: 1.026, 1.212), 1.443 (95% CI: 1.151, 1.808), 3.175 (95% CI: 2.291, 4.401), 1.272 (95% CI: 1.149,1.410), 1.382 (95% CI: 1.011, 1.888), 1.107 (95% CI: 1.003, 1.222), 1.035 (95% CI: 0.984, 1.088), and 1.122 (95% CI: 1.086, 1.160), respectively. SO2 was the predominant contributor to the combined effect (HR: 2.083, 95% CI: 1.659-2.508). Gender, age, drinking, and health status could modify the effects of air pollutants on MCC patterns. Long-term exposure to air pollution is correlated to the incidence and patterns of MCC in middle-aged and elderly Chinese individuals. Preventive methods are essential to safeguarding those susceptible to MCC.

Disease types and pathogenic mechanisms induced by PM2.5 in five human systems: An analysis using omics and human disease databases

Atmospheric fine particulate matter (PM2.5) can harm various systems in the human body. Due to limitations in the current understanding of epidemiology and toxicology, the disease types and pathogenic mechanisms induced by PM2.5 in various human systems remain unclear. In this study, the disease types induced by PM2.5 in the respiratory, circulatory, endocrine, and female and male urogenital systems have been investigated and the pathogenic mechanisms identified at molecular level. The results reveal that PM2.5 is highly likely to induce pulmonary emphysema, reperfusion injury, malignant thyroid neoplasm, ovarian endometriosis, and nephritis in each of the above systems respectively. The most important co-existing gene, cellular component, biological process, molecular function, and pathway in the five systems targeted by PM2.5 are Fos proto-oncogene (FOS), extracellular matrix, urogenital system development, extracellular matrix structural constituent conferring tensile strength, and ferroptosis respectively. Differentially expressed genes that are significantly and uniquely targeted by PM2.5 in each system are BTG2 (respiratory), BIRC5 (circulatory), NFE2L2 (endocrine), TBK1 (female urogenital) and STAT1 (male urogenital). Important disease-related cellular components, biological processes, and molecular functions are specifically induced by PM2.5. For example, response to wounding, blood vessel morphogenesis, body morphogenesis, negative regulation of response to endoplasmic reticulum stress, and response to type I interferon are the top uniquely existing biological processes in each system respectively. PM2.5 mainly acts on key disease-related pathways such as the PD-L1 expression and PD-1 checkpoint pathway in cancer (respiratory), cell cycle (circulatory), apoptosis (endocrine), antigen processing and presentation (female urogenital), and neuroactive ligand-receptor interaction (male urogenital). This study provides a novel analysis strategy for elucidating PM2.5-related disease types and is an important supplement to epidemiological investigation. It clarifies the risks of PM2.5 exposure, elucidates the pathogenic mechanisms, and provides scientific support for promoting the precise prevention and treatment of PM2.5-related diseases.

Fine particulate matter manipulates immune response to exacerbate microbial pathogenesis in the respiratory tract

Particulate matter with a diameter ≤2.5 μm (PM2.5) poses a substantial global challenge, with a growing recognition of pathogens contributing to diseases associated with exposure to PM2.5 Recent studies have focused on PM2.5, which impairs the immune cells in response to microbial infections and potentially contributes to the development of severe diseases in the respiratory tract. Accordingly, changes in the respiratory immune function and microecology mediated by PM2.5 are important factors that enhance the risk of microbial pathogenesis. These factors have garnered significant interest. In this review, we summarise recent studies on the potential mechanisms involved in PM2.5-mediated immune system disruption and exacerbation of microbial pathogenesis in the respiratory tract. We also discuss crucial areas for future research to address the gaps in our understanding and develop effective strategies to combat the adverse health effects of PM2.5.

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.

Paeoniflorin attenuates particulate matter-induced acute lung injury by inhibiting oxidative stress and NLRP3 inflammasome-mediated pyroptosis through activation of the Nrf2 signaling pathway

Particulate matter (PM), the main component of air pollutants, emerges as a research hotspot, especially in the area of respiratory diseases. Paeoniflorin (PAE), known as anti-inflammatory and immunomodulatory effects, has been reported to alleviate acute lung injury (ALI). However, the effect of PAE on PM-induced ALI and the underlying mechanisms are still unclear yet. In this study, we established the PM-induced ALI model using C57BL/6J mice and BEAS-2B cells to explore the function of PAE. In vivo, mice were intraperitoneally injected with PAE (100 mg/kg) or saline 1 h before instilled with 4 mg/kg PM intratracheally and were euthanized on the third day. For lung tissues, HE staining and TUNEL staining were used to evaluate the degree of lung injury, ELISA assay was used to assess inflammatory mediators and oxidative stress level, Immunofluorescence staining and western blotting were applied to explore the role of pyroptosis and Nrf2 signaling pathway. In vitro, BEAS-2B cells were pretreated with 100 μM PAE before exposure to 200 μg/ml PM and were collected after 24h for the subsequent experiments. TUNEL staining, ROS staining, and western blotting were conducted to explore the underlying mechanisms of PAE on PM-induced ALI. According to the results, PAE can attenuate the degree of PM-induced ALI in mice and reduce PM-induced cytotoxicity in BEAS-2B cells. PAE can relieve PM-induced excessive oxidative stress and NLRP3 inflammasome-mediated pyroptosis. Additionally, PAE can also activate Nrf2 signaling pathway and inhibition of Nrf2 signaling pathway can impair the protective effect of PAE by aggravating oxidative stress and pyroptosis. Our findings demonstrate that PAE can attenuate PM-induced ALI by inhibiting oxidative stress and NLRP3 inflammasome-mediated pyroptosis, which is mediated by Nrf2 signaling pathway.

Air pollutants contribute to epithelial barrier dysfunction and allergic diseases

Air pollution is a global problem associated with various health conditions, causing elevated rates of morbidity and mortality. Major sources of air pollutants include industrial emissions, traffic-related pollutants, and household biomass combustion, in addition to indoor pollutants from chemicals and tobacco. Various types of air pollutants originate from both human activities and natural sources. These include particulate matter, pollen, greenhouse gases, and other harmful gases. Air pollution is linked to allergic diseases, including atopic dermatitis, allergic rhinitis, allergic conjunctivitis, food allergy, and bronchial asthma. These pollutants lead to epithelial barrier dysfunction, dysbiosis, and immune dysregulation. In addition, climate change and global warming may contribute to the exacerbation and the development of allergic diseases related to air pollutants. Epigenetic changes associated with air pollutants have also been connected to the onset of allergic diseases. Furthermore, these changes can be passed down through subsequent generations, causing a higher prevalence of allergic diseases in offspring. Modulation of the aryl hydrocarbon receptor could be a valuable strategy for alleviating air pollutant-induced epidermal barrier dysfunction and atopic dermatitis. A more effective approach to preventing allergic diseases triggered by air pollutants is to reduce exposure to them. Implementing public policies aimed at safeguarding individuals from air pollutant exposure may prove to be the most efficient solution. A pressing need exists for global policy initiatives that prioritize efforts to reduce the production of air pollutants.

Exercise ameliorates fine particulate matter-induced metabolic damage through the SIRT1/AMPKα/PGC1-α/NRF1 signaling pathway

Air pollution, particularly fine particulate matter (PM2.5), poses a major threat to human health. Exercise has long been recognized as a beneficial way to maintain physical health. However, there is limited research on whether exercise can mitigate the damage caused by PM2.5 exposure. In this study, the mice were exercised on the IITC treadmill for 1 h per day, then exposed to concentrated PM2.5 for 8 h. After 2, 4 and 6-month exercise and PM2.5 exposure, the glucose tolerance and insulin tolerance were determined. Meanwhile, the corresponding indicators in epididymal white adipose tissue (eWAT), brown adipose tissue (BAT) and skeletal muscle were detected. The results indicated that PM2.5 exposure significantly increased insulin resistance (IR), while exercise effectively attenuated this response. The observations of muscle, BAT and eWAT by transmission electron microscopy (TEM) showed that PM2.5 significantly reduced the number of mitochondria in all of the three tissues mentioned above, and decreased the mitochondrial area in skeletal muscle and BAT. Exercise reversed the changes in mitochondrial area in all of the three tissues, but had no effect on the reduction of mitochondrial number in skeletal muscle. At 2 months, the expressions of Mfn2, Mfn1, OPA1, Drp1 and Fis1 in eWAT of the PM mice showed no significant changes when compared with the corresponding FA mice. However, at 4 months and 6 months, the expression levels of these genes in PM mice were higher than those in the FA mice in skeletal muscle. Exercise intervention significantly reduced the upregulation of these genes induced by PM exposure. The study indicated that PM2.5 may impact mitochondrial biogenesis and dynamics by inhibiting the SIRT1/AMPKα/PGC1-α/NRF1 pathway, which further lead to IR, glucose and lipid disorders. However, exercise might alleviate the damages caused by PM2.5 exposure.

Impact of particulate air pollution on airway injury and epithelial plasticity; underlying mechanisms

Air pollution plays an important role in the mortality and morbidity of chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Particulate matter (PM) is a significant fraction of air pollutants, and studies have demonstrated that it can cause airway inflammation and injury. The airway epithelium forms the first barrier of defense against inhaled toxicants, such as PM. Airway epithelial cells clear airways from inhaled irritants and orchestrate the inflammatory response of airways to these irritants by secreting various lipid mediators, growth factors, chemokines, and cytokines. Studies suggest that PM plays an important role in the pathogenesis of chronic airway diseases by impairing mucociliary function, deteriorating epithelial barrier integrity, and inducing the production of inflammatory mediators while modulating the proliferation and death of airway epithelial cells. Furthermore, PM can modulate epithelial plasticity and airway remodeling, which play central roles in asthma and COPD. This review focuses on the effects of PM on airway injury and epithelial plasticity, and the underlying mechanisms involving mucociliary activity, epithelial barrier function, airway inflammation, epithelial-mesenchymal transition, mesenchymal-epithelial transition, and airway remodeling.

Particulate Matter and Its Impact on Macrophages: Unraveling the Cellular Response for Environmental Health

Particulate matter (PM) imposes a significant impact to environmental health with deleterious effects on the human pulmonary and cardiovascular systems. Macrophages (Mφ), key immune cells in lung tissues, have a prominent role in responding to inhaled cells, accommodating inflammation, and influencing tissue repair processes. Elucidating the critical cellular responses of Mφ to PM exposure is essential to understand the mechanisms underlying PM-induced health effects. The present review aims to give a glimpse on literature about the PM interaction with Mφ, triggering the cellular events causing the inflammation, oxidative stress (OS) and tissue damage. The present paper reviews the different pathways involved in Mφ activation upon PM exposure, including phagocytosis, intracellular signaling cascades, and the release of pro-inflammatory mediators. Potential therapeutic strategies targeting Mφ-mediated responses to reduce PM-induced health effects are also discussed. Overall, unraveling the complex interplay between PM and Mφ sheds light on new avenues for environmental health research and promises to develop targeted interventions to reduce the burden of PM-related diseases on global health.