PM2.5 impairs macrophage functions to exacerbate pneumococcus-induced pulmonary pathogenesis

Short-term exposure to fine particulate matter exposure impairs innate immune and inflammatory responses to a pathogen stimulus: A functional study in the zebrafish model

Short-term exposure to fine particulate matter (PM2.5) is associated with the activation of adverse inflammatory responses, increasing the risk of developing acute respiratory diseases, such as those caused by pathogen infections. However, the functional mechanisms underlying this evidence remain unclear. In the present study, we generated a zebrafish model of short-term exposure to a specific PM2.5, collected in the northern metropolitan area of Milan, Italy. First, we assessed the immunomodulatory effects of short-term PM2.5 exposure and observed that it elicited pro-inflammatory effects by inducing the expression of cytokines and triggering hyper-activation of both neutrophil and macrophage cell populations. Moreover, we examined the impact of a secondary infectious pro-inflammatory stimulus induced through the injection of Pseudomonas aeruginosa lipopolysaccharide (Pa-LPS) molecules after exposure to short-term PM2.5. In this model, we demonstrated that the innate immune response was less responsive to a second pro-inflammatory infectious stimulus. Indeed, larvae exhibited dampened leukocyte activation and impaired production of reactive oxygen species. The obtained results indicate that short-term PM2.5 exposure alters the immune microenvironment and affects the inflammatory processes, thus potentially weakening the resistance to pathogen infections.

Immune Dysregulation in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a disease whose incidence increase with age and is characterised by chronic inflammation and significant immune dysregulation. Inhalation of toxic substances cause oxidative stress in the lung tissue as well as airway inflammation, under the recruitment of chemokines, immune cells gathered and are activated to play a defensive role. However, persistent inflammation damages the immune system and leads to immune dysregulation, which is mainly manifested in the reduction of the body's immune response to antigens, and immune cells function are impaired, further destroy the respiratory defensive system, leading to recurrent lower respiratory infections and progressive exacerbation of the disease, thus immune dysregulation play an important role in the pathogenesis of COPD. This review summarizes the changes of innate and adaptive immune-related cells during the pathogenesis of COPD, aiming to control COPD airway inflammation and improve lung tissue remodelling by regulating immune dysregulation, for further reducing the risk of COPD progression and opening new avenues of therapeutic intervention in COPD.

Fine particulate matter 2.5 induces susceptibility to Pseudomonas aeruginosa infection via expansion of PD-L1high neutrophils in mice

BACKGROUND

Exposure to PM2.5 has been implicated in a range of detrimental health effects, particularly affecting the respiratory system. However, the precise underlying mechanisms remain elusive.

METHODS

To address this objective, we collected ambient PM2.5 and administered intranasal challenges to mice, followed by single-cell RNA sequencing (scRNA-seq) to unravel the heterogeneity of neutrophils and unveil their gene expression profiles. Flow cytometry and immunofluorescence staining were subsequently conducted to validate the obtained results. Furthermore, we assessed the phagocytic potential of neutrophils upon PM2.5 exposure using gene analysis of phagocytosis signatures and bacterial uptake assays. Additionally, we utilized a mouse pneumonia model to evaluate the susceptibility of PM2.5-exposed mice to Pseudomonas aeruginosa infection.

RESULTS

Our study revealed a significant increase in neutrophil recruitment within the lungs of PM2.5-exposed mice, with subclustering of neutrophils uncovering subsets with distinct gene expression profiles. Notably, exposure to PM2.5 was associated with an expansion of PD-L1high neutrophils, which exhibited impaired phagocytic function dependent upon PD-L1 expression. Furthermore, PM2.5 exposure was found to increase the susceptibility of mice to Pseudomonas aeruginosa, due in part to increased PD-L1 expression on neutrophils. Importantly, monoclonal antibody targeting of PD-L1 significantly reduced bacterial burden, dissemination, and lung inflammation in PM2.5-exposed mice upon Pseudomonas aeruginosa infection.

CONCLUSIONS

Our study suggests that PM2.5 exposure promotes expansion of PD-L1high neutrophils with impaired phagocytic function in mouse lungs, contributing to increased vulnerability to bacterial infection, and therefore targeting PD-L1 may be a therapeutic strategy for reducing the harmful effects of PM2.5 exposure on the immune system.

Causal relationship between particulate matter 2.5 and infectious diseases: A two-sample Mendelian randomization study

Background

Previous observational studies suggested a correlation between particulate matter 2.5 (PM2.5) and infectious diseases, but causality remained uncertain. This study utilized Mendelian randomization (MR) analysis to investigate causal relationships between PM2.5 concentrations and various infectious diseases (COVID-19 infection, hospitalized COVID-19, very severe COVID-19, urinary tract infection, bacterial pneumonia, and intestinal infection).

Methods

Inverse variance weighted (IVW) was the primary method for evaluating causal associations. For significant causal estimates, multiple sensitivity tests were further performed: (i) three additional MR methods (MR-Egger, weighted median, and maximum likelihood method) for supplementing IVW; (ii) Cochrane's Q test for assessing heterogeneity; (iii) MR-Egger intercept test and MR-PRESSO global test for evaluating horizontal pleiotropy; (iv) leave-one-out sensitivity test for determining the stability.

Results

PM2.5 concentration significantly increased the risk of hospitalized COVID-19 (OR = 1.91, 95 % CI: 1.06-3.45, P = 0.032) and very severe COVID-19 (OR = 3.29, 95 % CI: 1.48-7.35, P = 3.62E-03). However, no causal effect was identified for PM2.5 concentration on other infectious diseases (P > 0.05). Furthermore, various sensitivity tests demonstrated the reliability of significant causal relationships.

Conclusions

Overall, lifetime elevated PM2.5 concentration increases the risk of hospitalized COVID-19 and very severe COVID-19. Therefore, controlling air pollution may help mitigate COVID-19 progression.

ATM participates in fine particulate matter-induced airway inflammation through regulating DNA damage and DNA damage response

The relationship between fine particulate matter (PM2.5) and chronic airway inflammatory diseases, such as chronic obstructive pulmonary disease and asthma, have garnered public attention, while the detailed mechanisms of PM2.5-induced airway inflammation remain unclear. This study reveals that PM2.5 induces airway inflammation both in vivo and in vitro, and, moreover, identifies DNA damage and DNA damage repair (DDR) as results of this exposure. Ataxia telangiectasia-mutated heterozygous (ATM+/- ) and wild-type C57BL/6 (WT) mice were exposed to PM2.5. The results show that, following exposure to PM2.5, the number of neutrophils in broncho alveolar lavage fluid and the mRNA expression of CXCL-1 in lung tissues of the ATM+/- mice were lower than those of the WT mice. The mRNA expression of FANCD2 and FANCI were also down-regulated. Human bronchial epithelial (HBE) cells were transfected with ATM-siRNA to induce down-regulation of ATM gene expression and were subsequently stimulated with PM2.5. The results show that the mRNA expression of TNF-α decreased in the ATM-siRNA-transfected cells. The mRNA expression of CXCL-1 and CXCL-2 in peritoneal macrophages, derived from ATM-null mice in which experiments showed that the protein expression of FANCD2 and FANCI decreased, were also decreased after PM2.5 exposure in ATM-siRNA-transfected HBE cells. In conclusion, PM2.5-induced airway inflammation is alleviated in ATM+/- mice compared with WT mice. ATM promotes PM2.5-induced airway inflammation, which may be attributed to the regulation of DNA damage and DDR.

Elucidating disease-associated mechanisms triggered by pollutants via the epigenetic landscape using large-scale ChIP-Seq data

BACKGROUND

Despite well-documented effects on human health, the action modes of environmental pollutants are incompletely understood. Although transcriptome-based approaches are widely used to predict associations between chemicals and disorders, the molecular cues regulating pollutant-derived gene expression changes remain unclear. Therefore, we developed a data-mining approach, termed "DAR-ChIPEA," to identify transcription factors (TFs) playing pivotal roles in the action modes of pollutants.

METHODS

Large-scale public ChIP-Seq data (human, n = 15,155; mouse, n = 13,156) were used to predict TFs that are enriched in the pollutant-induced differentially accessible genomic regions (DARs) obtained from epigenome analyses (ATAC-Seq). The resultant pollutant-TF matrices were then cross-referenced to a repository of TF-disorder associations to account for pollutant modes of action. We subsequently evaluated the performance of the proposed method using a chemical perturbation data set to compare the outputs of the DAR-ChIPEA and our previously developed differentially expressed gene (DEG)-ChIPEA methods using pollutant-induced DEGs as input. We then adopted the proposed method to predict disease-associated mechanisms triggered by pollutants.

RESULTS

The proposed approach outperformed other methods using the area under the receiver operating characteristic curve score. The mean score of the proposed DAR-ChIPEA was significantly higher than that of our previously described DEG-ChIPEA (0.7287 vs. 0.7060; Q = 5.278 × 10-42; two-tailed Wilcoxon rank-sum test). The proposed approach further predicted TF-driven modes of action upon pollutant exposure, indicating that (1) TFs regulating Th1/2 cell homeostasis are integral in the pathophysiology of tributyltin-induced allergic disorders; (2) fine particulates (PM2.5) inhibit the binding of C/EBPs, Rela, and Spi1 to the genome, thereby perturbing normal blood cell differentiation and leading to immune dysfunction; and (3) lead induces fatty liver by disrupting the normal regulation of lipid metabolism by altering hepatic circadian rhythms.

CONCLUSIONS

Highlighting genome-wide chromatin change upon pollutant exposure to elucidate the epigenetic landscape of pollutant responses outperformed our previously described method that focuses on gene-adjacent domains only. Our approach has the potential to reveal pivotal TFs that mediate deleterious effects of pollutants, thereby facilitating the development of strategies to mitigate damage from environmental pollution.

Three-dimensional label-free visualization of the interactions of PM2.5 with macrophages and epithelial cells using optical diffraction tomography

Particulate matter ≤ 2.5 µm (PM2.5) poses health risks related to various diseases and infections. However, the interactions between PM2.5 and cells such as uptake and cell responses have not been fully investigated despite advances in bioimaging techniques, because the heterogeneous morphology and composition of PM2.5 make it challenging to employ labeling techniques, such as fluorescence. In this work, we visualized the interaction between PM2.5 and cells using optical diffraction tomography (ODT), which provides quantitative phase images by refractive index distribution. Through ODT analysis, the interactions of PM2.5 with macrophages and epithelial cells, such as intracellular dynamics, uptake, and cellular behavior, were successfully visualized without labeling techniques. ODT analysis clearly shows the behavior of phagocytic macrophages and nonphagocytic epithelial cells for PM2.5. Moreover, ODT analysis could quantitatively compare the accumulation of PM2.5 inside the cells. PM2.5 uptake by macrophages increased substantially over time, but uptake by epithelial cells increased only marginally. Our findings indicate that ODT analysis is a promising alternative approach to visually and quantitatively understanding the interaction of PM2.5 with cells. Therefore, we expect ODT analysis to be employed to investigate the interactions of materials and cells that are difficult to label.

Lung-gut axis of microbiome alterations following co-exposure to ultrafine carbon black and ozone

BACKGROUND

Microbial dysbiosis is a potential mediator of air pollution-induced adverse outcomes. However, a systemic comparison of the lung and gut microbiome alterations and lung-gut axis following air pollution exposure is scant. In this study, we exposed male C57BL/6J mice to inhaled air, CB (10 mg/m3), O3 (2 ppm) or CB + O3 mixture for 3 h/day for either one day or four consecutive days and were euthanized 24 h post last exposure. The lung and gut microbiome were quantified by 16 s sequencing.

RESULTS

Multiple CB + O3 exposures induced an increase in the lung inflammatory cells (neutrophils, eosinophils and B lymphocytes), reduced absolute bacterial load in the lungs and increased load in the gut. CB + O3 exposure was more potent as it decreased lung microbiome alpha diversity just after a single exposure. CB + O3 co-exposure uniquely increased Clostridiaceae and Prevotellaceae in the lungs. Serum short chain fatty acids (SCFA) (acetate and propionate) were increased significantly only after CB + O3 co-exposure. A significant increase in SCFA producing bacterial families (Ruminococcaceae, Lachnospiraceae, and Eubacterium) were also observed in the gut after multiple exposures. Co-exposure induced significant alterations in the gut derived metabolite receptors/mediator (Gcg, Glp-1r, Cck) mRNA expression. Oxidative stress related mRNA expression in lungs, and oxidant levels in the BALF, serum and gut significantly increased after CB + O3 exposures.

CONCLUSION

Our study confirms distinct gut and lung microbiome alterations after CB + O3 inhalation co-exposure and indicate a potential homeostatic shift in the gut microbiome to counter deleterious impacts of environmental exposures on metabolic system.

Effects of short-term high-concentration exposure to PM2.5 on pulmonary tissue damage and repair ability as well as innate immune events

Short-term heavy air pollution still occurs frequently worldwide, especially during the winter heating period in some developing countries, which is usually accompanied by the temporary explosive growth of PM_2.5. The pulmonary damage caused by PM_2.5 exposure has been determined, but there have been few studies on the repair ability after the cessation of exposure and the important role of innate immune events. This study established a short-term (30 days) high-concentration (15 mg/kg body weight) PM_2.5 exposure and recovery (15 days of exposure cessation) model by intratracheal instillation. The results showed that short-term PM_2.5 exposure increased the content of collagen fiber in rat lung tissue, which was significantly repaired after recovery by 15 days of exposure cessation. Meanwhile, exposure to PM_2.5 also caused changes in lung epithelial function, macrophage polarization and cell autophagy function. Most of these changes could be restored or reversed to a certain extent after recovery. However, there were also some biomarkers, including CLDN18.1, SP-A, SP-D, iNOS, CD206, Beclin1, p62 and LC3B, that were still significantly different between the exposure and control groups after recovery, suggesting that some toxic effects, especially epithelial function damage, were not completely repaired. In addition, there was a significant correlation between pulmonary fibrosis and innate immunity. The present study demonstrated that short-term high-concentration exposure to PM_2.5 could cause temporary lung tissue damage and related innate immune events in rats, and the repair ability existed after the cessation of exposure, but part of the damage that required special attention still persisted.

On-Chip Free-Flow Measurement Revealed Possible Depletion of Macrophages by Indigestible PM2.5 within a Few Hours by the Fastest Intervals of Serial Phagocytosis

To understand the influence of indigestible particles like particulate matter 2.5 (PM2.5) on macrophages, we examined the time course of the series phagocytosis of indigestible 2 μm polystyrene spheres (PS). Five kinds of antigens were used as samples for phagocytosis; Zymosan, non-coated 2 μm PS, bovine serum albumin (BSA)-coated PS (BSA-PS), IgG-coated PS (IgG-PS), and IgG-BSA-coated PS (IgG/BSA-PS). To keep the surrounding concentration of antigens against single macrophages constant, antigens flowed at a continuous rate of 0.55 μm/s within a culture dish as a free-flow measurement assay (on-chip free-flow method). The interval of series phagocytosis for IgG/BSA-PS was the shortest among five samples; it was six times faster than Zymosan in terms of engulfment frequency, and up to 50 particles were engulfed within two hours, maintaining constant intervals until reaching the maximum number. The rate of increase in the total number of phagocytozed IgG/BSA-PS over time was constant, at 1.5 particles/min, in series phagocytosis with a 33-cell population, indicating that the phagocytosis rate constant remained constant independent of the number of phagocytoses. Reaction model fitting of the results showed that IgG/BSA-PS had the highest efficiency in terms of the phagocytosis rate constant, 2.3 × 10-2 particles/min, whereas those of IgG-PS, BSA-PS, PS, and Zymosan were 1.4 × 10-2, 1.1 × 10-2, 4.2 × 10-3, and 3.6 × 10-3 particles/min, respectively. One-by-one feeding of IgG/BSA-PS with optical tweezers was examined to confirm the phagocytosis intervals, and we found that the intervals remained constant until several times before the maximum number of antigens for engulfment, also indicating no change in the phagocytosis rate constant regardless of the history of former phagocytosis and phagocytosis number. Simultaneous phagocytosis of two IgG-BSA-decorated microneedle engulfments also showed that the initiation and progress of two simultaneous engulfments on the two different places on a cell were independent and had the same elongation velocity. Therefore, each phagocytosis of indigestible antigens does not affect both in series or in simultaneous subsequent phagocytosis until reaching the maximum capacity of the phagocytosis number. The results suggest (1) no change in the phagocytosis rate constant regardless of the history of phagocytosis numbers and attachment timing and positions, and (2) IgG-BSA decoration of indigestible microparticles in blood accelerates their engulfment faster, resulting in a severe shortage of macrophages within the shortest time.

Pulmonary microbiota intervention alleviates fine particulate matter-induced lung inflammation in broilers

Fine particulate matter (PM2.5) released during the livestock industry endangers the respiratory health of animals. Our previous findings suggested that broilers exposed to PM2.5 exhibited lung inflammation and changes in the pulmonary microbiome. Therefore, this study was to investigate whether the pulmonary microbiota plays a causal role in the pathogenesis of PM2.5-induced lung inflammation. We first used antibiotics to establish a pulmonary microbiota intervention broiler model, which showed a significantly reduced total bacterial load in the lungs without affecting the microbiota composition or structure. Based on it, 45 AA broilers of similar body weight were randomly assigned to three groups: control (CON), PM2.5 (PM), and pulmonary microbiota intervention (ABX-PM). From 21 d of age, broilers in the ABX-PM group were intratracheally instilled with antibiotics once a day for 3 d. Meanwhile, broilers in the other two groups were simultaneously instilled with sterile saline. On 24 and 26 d of age, broilers in the PM and ABX-PM groups were intratracheally instilled with PM2.5 suspension to induce lung inflammation, and broilers in the CON group were simultaneously instilled with sterile saline. The lung histomorphology, inflammatory cytokines' expression levels, lung microbiome, and microbial growth conditions were analyzed to determine the effect of the pulmonary microbiota on PM2.5-induced lung inflammation. Broilers in the PM group showed lung histological injury, while broilers in the ABX-PM group had normal lung histomorphology. Furthermore, microbiota intervention significantly reduced mRNA expression levels of interleukin-1β, tumor necrosis factor-α, interleukin-6, interleukin-8, toll-like receptor 4 and nuclear factor kappa-B. PM2.5 induced significant changes in the β diversity and structure of the pulmonary microbiota in the PM group. However, no significant changes in microbiota structure were observed in the ABX-PM group. Moreover, the relative abundance of Enterococcus cecorum in the PM group was significantly higher than that in the CON and ABX-PM groups. And sterile bronchoalveolar lavage fluid from the PM group significantly promoted the growth of E. cecorum, indicating that PM2.5 altered the microbiota's growth condition. In conclusion, pulmonary microbiota can affect PM2.5-induced lung inflammation in broilers. PM2.5 can alter the bacterial growth environment and promote dysbiosis, potentially exacerbating inflammation.

Combined effect of preconceptional and prenatal exposure to air pollution and temperature on childhood pneumonia: A case-control study

Mounting evidence have linked ambient air pollution and temperature with childhood pneumonia, but it is unclear whether there is an interaction between air pollution and temperature on childhood pneumonia. We aim to assess the combined effect of ambient air pollution and temperature exposure during preconception and pregnancy on pneumonia by a case-control study of 1510 children aged 0-14 years in Changsha, China. We obtained the data of childhood pneumonia from XiangYa Hospital electrical records. We estimated personal exposure to outdoor air pollution (PM₁₀, SO₂ and NO₂) by inverse distance weighted (IDW) method and temperature indicators. Multiple logistic regression models were used to evaluate associations of childhood pneumonia with air pollution, temperature (T), and diurnal temperature variation (DTV). We found that exposure to industry-related air pollution (PM₁₀ and SO₂) during preconception and pregnancy were associated with childhood pneumonia, with ORs (95% CI) of 1.72 (1.48-1.98) and 2.96 (2.50-3.51) during 1 year before pregnancy and 1.83 (1.59-2.11) and 3.43 (2.83-4.17) in pregnancy. Childhood pneumonia was negatively associated with T exposure during 1 year before pregnancy and pregnancy, with ORs (95% CI) of 0.57 (0.41-0.80) and 0.85 (0.74-0.98). DTV exposure during pregnancy especially during the 1st and 2nd trimesters significantly increased pneumonia risk, with ORS (95% CI) of 1.77 (1.19-2.64), 1.47 (1.18-1.83), and 1.37 (1.07-1.76) respectively. We further observed interactions of PM₁₀ and SO₂ exposure with low T and high DTV during conception and pregnancy in relation to childhood pneumonia. This study suggests that there were interactions air pollution with temperature and DTV on pneumonia development.

Pretreatment with rosavin attenuates PM2.5-induced lung injury in rats through antiferroptosis via PI3K/Akt/Nrf2 signaling pathway

Inflammation and oxidative stress caused by fine particulate matter (PM2.5) increase the incidence and mortality rates of respiratory disorders. Rosavin is the main chemical component of Rhodiola plants, which exerts anti-oxidative and antiinflammatory effects. In this research, the potential therapeutic effect of rosavin was investigated by the PM2.5-induced lung injury rat model. Rats were instilled with PM2.5 (7.5 mg/kg) suspension intratracheally, while rosavin (50 mg/kg, 100 mg/kg) was delivered by intraperitoneal injection before the PM2.5 injection. It was observed that rosavin could prevent lung injury caused by PM2.5. PM2.5 showed obvious ferroptosis-related ultrastructural alterations, which were significantly corrected by rosavin. The pretreatment with rosavin downregulated the levels of tissue iron, malondialdehyde, and 4-hydroxynonenal, and increased the levels of glutathione. The expression of nuclear factor E2-related factor 2 (Nrf2) was upregulated by rosavin, together with other ferroptosis-related proteins. RSL3, a specific ferroptosis agonist, reversed the beneficial impact of rosavin. The network pharmacology approach predicted the activation of rosavin on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. LY294002, a potent PI3K inhibitor, decreased the upregulation of Nrf2 induced by rosavin. In conclusion, rosavin prevented lung injury induced by PM2.5 stimulation and suppressed ferroptosis via upregulating PI3K/Akt/Nrf2 signaling pathway.

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.

Comparing the Therapeutic Efficacies of Lung Cancer: Network Meta-Analysis Approaches

BACKGROUND

In recent years, reduction of nuclear power generation and the use of coal-fired power for filling the power supply gap might have increased the risk of lung cancer. This study aims to explore the most effective treatment for different stages of lung cancer patients.

METHODS

We searched databases to investigate the treatment efficacy of lung cancer. The network meta-analysis was used to explore the top three effective therapeutic strategies among all collected treatment methodologies.

RESULTS

A total of 124 studies were collected from 115 articles with 171,757 participants in total. The results of network meta-analyses showed that the best top three treatments: (1) in response rate, for advanced lung cancer were Targeted + Targeted, Chemo + Immuno, and Targeted + Other Therapy with cumulative probabilities 82.9, 80.8, and 69.3%, respectively; for non-advanced lung cancer were Chemoradio + Targeted, Chemoradi + Immuno, and Chemoradio + Other Therapy with cumulative probabilities 69.0, 67.8, and 60.7%, respectively; (2) in disease-free control rate, for advanced lung cancer were Targeted + Others, Chemo + Immuno, and Targeted + Targeted Therapy with cumulative probabilities 93.4, 91.5, and 59.4%, respectively; for non-advanced lung cancer were Chemo + Surgery, Chemoradio + Targeted, and Surgery Therapy with cumulative probabilities 80.1, 71.5, and 43.1%, respectively.

CONCLUSION

The therapeutic strategies with the best effectiveness will be different depending on the stage of lung cancer patients.

Role of Macrophages in Air Pollution Exposure Related Asthma

Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction, bronchial hyper-responsiveness, and airway inflammation. The chronic inflammation of the airway is mediated by many cell types, cytokines, chemokines, and inflammatory mediators. Research suggests that exposure to air pollution has a negative impact on asthma outcomes in adult and pediatric populations. Air pollution is one of the greatest environmental risks to health, and it impacts the lungs' innate and adaptive defense systems. A major pollutant in the air is particulate matter (PM), a complex component composed of elemental carbon and heavy metals. According to the WHO, 99% of people live in air pollution where air quality levels are lower than the WHO air quality guidelines. This suggests that the effect of air pollution exposure on asthma is a crucial health issue worldwide. Macrophages are essential in recognizing and processing any inhaled foreign material, such as PM. Alveolar macrophages are one of the predominant cell types that process and remove inhaled PM by secreting proinflammatory mediators from the lung. This review focuses on macrophages and their role in orchestrating the inflammatory responses induced by exposure to air pollutants in asthma.

The effects of air pollutants exposure on the transmission and severity of invasive infection caused by an opportunistic pathogen Streptococcus pyogenes

Currently, urbanization is associated with an increase in air pollutants that contribute to invasive pathogen infections by altering the host's innate immunity and antimicrobial resistance capability. Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is a gram-positive opportunistic pathogen that causes a wide range of diseases, especially in children and immunosuppressed individuals. Diesel exhaust particle (DEP), a significant constituent of particulate matter (PM), are considered a prominent risk factor for respiratory illness and circulatory diseases worldwide. Several clinical and epidemiological studies have identified a close association between PM and the prevalence of viral and bacterial infections. This study investigated the role of DEP exposure in increasing pulmonary and blood bacterial counts and mortality during GAS M1 strain infection in mice. Thus, we characterized the upregulation of reactive oxygen species production and disruption of tight junctions in the A549 lung epithelial cell line due to DEP exposure, leading to the upregulation of GAS adhesion and invasion. Furthermore, DEP exposure altered the leukocyte components of infiltrated cells in bronchoalveolar lavage fluid, as determined by Diff-Quik staining. The results highlighted the DEP-related macrophage dysfunction, neutrophil impairment, and imbalance in pro-inflammatory cytokine production via the toll-like receptor 4/mitogen-activated protein kinase signaling axis. Notably, the tolerance of the GAS biofilms toward potent antibiotics and bacterial resistance against environmental stresses was also significantly enhanced by DEP. This study aimed to provide a better understanding of the physiological and molecular interactions between exposure to invasive air pollutants and susceptibility to invasive GAS infections.

Short-term effects of gaseous air pollutants on outpatient visits for respiratory diseases: a case-crossover study in Baotou, China

Air pollution is a major public health problem throughout the world. Although there have been several studies in this field, most of them have focused on particulate matter and only covered a few key cities. This study aimed to assess a potential association between exposure to gaseous air pollutants and outpatient visits for respiratory diseases in Baotou, China. Daily outpatient visits for respiratory diseases and daily averages of air pollutants and meteorological parameters from 2015 to 2020 were obtained. Time-stratified case-crossover design and restricted cubic splines were used to perform the analyses. Stratified analyses were performed in different hospital departments and districts. Significant association between the concentrations of air pollutants and outpatient visits for respiratory diseases was observed. The odds ratios of outpatient visits for respiratory diseases associated with per 10 μg/m³ increases in concentrations of NO₂ and SO₂, and per 10 mg/m³ increases in concentrations of CO were 1.033 (95% CI: 1.018 to 1.049), 0.965 (95% CI: 0.954 to 0.976), and 1.038 (95% CI: 1.006 to 1.071), respectively. Short-term exposure to NO₂, SO₂, and CO was positively associated with outpatient visits for respiratory diseases, with stronger effects among children. The relationship between O₃ and respiratory diseases varied at different concentrations.

PM2.5 increases mouse blood pressure by activating toll-like receptor 3

BACKGROUND AND AIMS

Plenty of literature has documented that fine particulate matter (PM2.5) exposure is related to blood pressure (BP) elevation. Vascular dysfunction is the initiation of cardiovascular diseases, such as hypertension. This thesis set out to assess the role of Toll-like receptor 3 (TLR3) in the increase in BP induced by PM2.5.

METHODS

C57BL/6 and TLR3 deficient (TLR3-/-) male mice were randomly allocated to filtered air chamber or real-world inhaled concentrated PM2.5 chamber. BP was evaluated using non-invasive BP recordings. After euthanasia, the aortas and small mesenteric arteries (SMAs) were isolated, and vascular tone was measured using a wire myograph. Leucocytes were detached to assess myeloid-derived suppressor cells using flow cytometry. siRNA transfection was performed to silence TLR3 expression in the human vascular endothelial cells incubated with PM2.5. The gene expression levels of inflammation, adhesion molecules, and oxidative stress in the aortas were assessed by quantitative PCR.

RESULTS

Exposure to PM2.5 increased mouse BP, and TLR3 deficiency protected against PM2.5 exposure-induced BP increase. Additionally, the injury of vascular function in the aortas and SMAs was inhibited in TLR3-/- mice. The intercellular adhesion molecule-1 (ICAM-1) was attenuated in TLR3-/- mice, accompanied by the inhibition of inflammatory and oxidized genes of the aortas, such as F4/80, interleukin-6, interleukin-1 beta, and NADPH oxidase 4. In vitro, the enhanced mRNA expression of genes encoding inflammation, oxidative stress, and ICAM-1 by PM2.5 was inhibited by TLR3 silence as well.

CONCLUSIONS

PM2.5 exposure increased BP via TLR3 activation and impaired vascular function.

Fetal Liver-Derived Alveolar-like Macrophages: A Self-Replicating Ex Vivo Model of Alveolar Macrophages for Functional Genetic Studies

Alveolar macrophages (AMs) are tissue-resident cells in the lungs derived from the fetal liver that maintain lung homeostasis and respond to inhaled stimuli. Although the importance of AMs is undisputed, they remain refractory to standard experimental approaches and high-throughput functional genetics, as they are challenging to isolate and rapidly lose AM properties in standard culture. This limitation hinders our understanding of key regulatory mechanisms that control AM maintenance and function. In this study, we describe the development of a new model, fetal liver-derived alveolar-like macrophages (FLAMs), which maintains cellular morphologies, expression profiles, and functional mechanisms similar to murine AMs. FLAMs combine treatment with two key cytokines for AM maintenance, GM-CSF and TGF-β. We leveraged the long-term stability of FLAMs to develop functional genetic tools using CRISPR-Cas9-mediated gene editing. Targeted editing confirmed the role of AM-specific gene Marco and the IL-1 receptor Il1r1 in modulating the AM response to crystalline silica. Furthermore, a genome-wide knockout library using FLAMs identified novel genes required for surface expression of the AM marker Siglec-F, most notably those related to the peroxisome. Taken together, our results suggest that FLAMs are a stable, self-replicating model of AM function that enables previously impossible global genetic approaches to define the underlying mechanisms of AM maintenance and function.

PP2A-mTOR-p70S6K/4E-BP1 axis regulates M1 polarization of pulmonary macrophages and promotes ambient particulate matter induced mouse lung injury

To identify key signaling pathways involved in ambient particulate matter (PM)-induced pulmonary injury, we generated a mouse model with myeloid-specific deletion of Ppp2r1a gene (encoding protein phosphatase 2 A (PP2A) A subunit), and conducted experiments in a real-ambient PM exposure system. PP2A Aα^-/- homozygote (Aα HO) mice and matched wild-type (WT) littermates were exposed to PM over 3-week and 6-week. The effects of PM exposure on pulmonary inflammation, oxidative stress, and apoptosis were significantly enhanced in Aα HO compared to WT mice. The number of pulmonary macrophages increased by 74.8~88.0% and enhanced M1 polarization appeared in Aα HO mice upon PM exposure. Secretion of M1 macrophage-related inflammatory cytokines was significantly increased in Aα HO vs. WT mice following PM exposure. Moreover, we demonstrated that PP2A-B56α holoenzyme regulated M1 polarization and that the mTOR signaling pathway mediated the persistent M1 polarization upon PM2.5 exposure. Importantly, PP2A-B56α holoenzyme was shown to complex with mTOR/p70S6K/4E-BP1, and suppression of B56α led to enhanced phosphorylation of mTOR, p70S6K, and 4E-BP1. These observations demonstrate that the PP2A-mTOR-p70S6K/4E-BP1 signaling is a critical pathway in mediating macrophage M1 polarization, which contributes to PM-induced pulmonary injury.

The Social and Natural Environment's Impact on SARS-CoV-2 Infections in the UK Biobank

COVID-19 has caused a global pandemic with considerable impact. Studies have examined the influence of socioeconomic status and air pollution on COVID-19 risk but in low detail. This study seeks to further elucidate the nuances of socioeconomic status, as defined by the Index of Multiple Deprivation (IMD), air pollution, and their relationship. We examined the effect of IMD and air pollution on the likelihood of testing positive for SARS-CoV-2 among 66,732 UKB participants tested for SARS-CoV-2 from 16 March 2020 through 16 March 2021. Logistic regression was performed controlling for age, sex, ancestry and IMD or air pollution in the respective models. IMD and its sub-scores were significantly associated with increased risk of testing positive for SARS-CoV-2. All particulate matter less than 2.5 μm (PM2.5), nitrogen oxide (NO_x), and nitrogen dioxide (NO₂) levels were associated with increased likelihood of testing positive for SARS-CoV-2. Measures of green space and natural environment around participants' homes were associated with reduced likelihood of SARS-CoV-2. Socioeconomic status and air pollution have independent effects on the risk of testing positive for SARS-CoV-2. Green space and natural environment space in the proximity of people's homes may mediate the effect of air pollution on the risk of testing positive for SARS-CoV-2.

Associations between lung-deposited dose of particulate matter and culture-positive pulmonary tuberculosis pleurisy

Epidemiological studies identified the relationship between air pollution and pulmonary tuberculosis. Effects of lung-deposited dose of particulate matter (PM) on culture-positive pulmonary tuberculosis remain unclear. This study investigates the association between lung-deposited dose of PM and pulmonary tuberculosis pleurisy. A case-control study of subjects undergoing pleural effusion drainage of pulmonary tuberculosis (case) and chronic heart failure (control) was conducted. Metals and biomarkers were quantified in the pleural effusion. The air pollution exposure was measured and PM deposition in the head, tracheobronchial, alveolar region, and total lung region was estimated by Multiple-path Particle Dosimetry (MPPD) Model. We performed multiple logistic regression to examine the associations of these factors with the risk of tuberculosis. We observed that 1-μg/m³ increase in PM₁₀ was associated with 1.226-fold increased crude odds ratio (OR) of tuberculosis (95% confidence interval (CI): 1.023-1.469, p<0.05), 1-μg/m³ increase in PM_2.5-10 was associated with 1.482-fold increased crude OR of tuberculosis (95% CI: 1.048-2.097, p < 0.05), 1-ppb increase in NO₂ was associated with 1.218-fold increased crude OR of tuberculosis (95% CI: 1.025-1.447, p < 0.05), and 1-ppb increase in O₃ was associated with 0.735-fold decreased crude OR of tuberculosis (95% CI: 0.542 0.995). We observed 1-μg/m³ increase in PM deposition in head and nasal region was associated with 1.699-fold increased crude OR of tuberculosis (95% CI: 1.065-2.711, p < 0.05), 1-μg/m³ increase in PM deposition in tracheobronchial region was associated with 1.592-fold increased crude OR of tuberculosis (95% CI: 1.095-2.313, p < 0.05), 1-μg/m³ increase in PM deposition in alveolar region was associated with 3.981-fold increased crude OR of tuberculosis (95% CI: 1.280-12.386, p < 0.05), and 1-μg/m³ increase in PM deposition in total lung was associated with 1.511-fold increased crude OR of tuberculosis (95% CI: 1.050-2.173, p < 0.05). The results indicate that particle deposition in alveolar region could cause higher risk of pulmonary tuberculosis pleurisy than deposition in other lung regions.

Investigation on the mechanisms of biochanin A alleviate PM10-induced acute pulmonary cell injury

Epidemiological studies have shown that the elevated concentration of particulate matter with aerodynamic diameter less than 10 µm (PM10) is closely related to the increased risk of heart and lung diseases in the population. Natural isoflavone compound biochanin A (BCA) has anti-inflammatory and antioxidant activities, and has efficacy in alleviating lung injury. The objective of this study was to investigate the inhibitory effect of BCA on PM10 induced acute human bronchial epithelial cells injury. The results showed that PM10 decreased intracellular catalase level to 1.19 ± 0.01 nmol/min/mg prot and induce a surge of reactive oxygen species (ROS). It also increased lactate dehydrogenase (LDH) activity by 428.89% and caused the lipid peroxidation phenomenon. PM10 exposure also upregulates the expression of inflammatory cytokines and mediators. However, BCA could interfere with the above changes caused by PM10, inhibit the LDH level to 8.22 ± 0.03 u/mL, and show anti-inflammatory and antioxidant activities. In addition, the phosphatidylinositol 3-kimase (PI3K) /protein kinase B (PKB/Akt) is a key signal pathway in response to PM10 exposure. In this study, PI3K/Akt signaling pathway is seriously affected by PM10 exposure. PI3K/Akt signaling pathway, PI3K, AKT, tensin homolog deleted on chromosome 10 (PTEN), mechanistic target of rapamycin (mTOR) and p53 protein were all inhibited by PM10 exposure, and PI3K/Akt signaling pathway was inactivated. BCA exert anti-damage function by regulating the activation process of PI3K protein, intervening the regulation process of PI3K/Akt by PTEN, and intervening the expression and phosphorylation of downstream Akt protein.

Beyond "Big Eaters": The Versatile Role of Alveolar Macrophages in Health and Disease

Macrophages act as immune scavengers and are important cell types in the homeostasis of various tissues. Given the multiple roles of macrophages, these cells can also be found as tissue resident macrophages tightly integrated into a variety of tissues in which they fulfill crucial and organ-specific functions. The lung harbors at least two macrophage populations: interstitial and alveolar macrophages, which occupy different niches and functions. In this review, we provide the latest insights into the multiple roles of alveolar macrophages while unraveling the distinct factors which can influence the ontogeny and function of these cells. Furthermore, we will highlight pulmonary diseases, which are associated with dysfunctional macrophages, concentrating on congenital diseases as well as pulmonary infections and impairment of immunological pathways. Moreover, we will provide an overview about different treatment approaches targeting macrophage dysfunction. Improved knowledge of the role of macrophages in the onset of pulmonary diseases may provide the basis for new pharmacological and/or cell-based immunotherapies and will extend our understanding to other macrophage-related disorders.

Metformin Increases Survival in Hypopharyngeal Cancer Patients with Diabetes Mellitus: Retrospective Cohort Study and Cell-Based Analysis

Hypopharyngeal squamous cell carcinoma (HSCC) is usually diagnosed at an advanced stage, leading to a poor prognosis. Even after improvement of surgical techniques, chemotherapy, and radiation technology, the survival rate of HSCC remains poor. Metformin, which is commonly used for type 2 diabetes mellitus (DM), has been suggested to reduce the risk of various cancer types. However, only a few clinical studies mentioned the relationship between metformin use and HSCC. Hence, the aim of this study was to elucidate the specific effect and mechanism of action of metformin in hypopharyngeal cancer. We first assessed whether metformin use has an effect on hypopharyngeal cancer patients with DM by conducting a retrospective cohort study. Our results showed that DM hypopharyngeal cancer patients who used metformin exhibited significantly better overall survival rates than that without metformin treatment. The cell-based analysis further indicated that metformin treatment regulated p38/JNK pathway to reduce Cyclin D1 and Bcl-2 expressions. In addition, metformin activated the pathways of AMPKα and MEK/ERK to phosphorylate p27(Thr198) and reduce mTOR phosphorylation in cells. These actions direct cells toward G1 cell cycle arrest, apoptosis, and autophagy. Our results, through combining a clinical cohort analysis with an in vitro study, demonstrate that metformin can be used for drug repositioning in the treatment of DM patients with hypopharyngeal cancer.

Campylobacter jejuni Cytolethal Distending Toxin C Exploits Lipid Rafts to Mitigate Helicobacter pylori-Induced Pathogenesis

Helicobacter pylori infection is associated with several gastrointestinal diseases, including gastritis, peptic ulcer, and gastrointestinal adenocarcinoma. Two major cytotoxins, vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA), interact closely with lipid rafts, contributing to H. pylori-associated disease progression. The Campylobacter jejuni cytolethal distending toxin consists of three subunits: CdtA, CdtB, and CdtC. Among them, CdtA and CdtC bind to membrane lipid rafts, which is crucial for CdtB entry into cells. In this study, we employed recombinant CdtC (rCdtC) to antagonize the functions of H. pylori cytotoxin in cells. Our results showed that rCdtC alleviates cell vacuolation induced by H. pylori VacA. Furthermore, rCdtC reduces H. pylori CagA translocation, which decreases nuclear factor kappa-B activation and interleukin-8 production, resulting in the mitigation of gastric epithelial cell inflammation. These results reveal that CdtC hijacks cholesterol to compete for H. pylori cytotoxin actions via lipid rafts, ameliorating H. pylori-induced pathogenesis.

Emerging role of mitochondria in airborne particulate matter-induced immunotoxicity

The immune system is one of the primary targets of airborne particulate matter. Recent evidence suggests that mitochondria lie at the center of particulate matter-induced immunotoxicity. Particulate matter can directly interact with mitochondrial components (proteins, lipids, and nucleic acids) and impairs the vital mitochondrial processes including redox mechanisms, fusion-fission, autophagy, and metabolic pathways. These disturbances impede different mitochondrial functions including ATP production, which acts as an important platform to regulate immunity and inflammatory responses. Moreover, the mitochondrial DNA released into the cytosol or in the extracellular milieu acts as a danger-associated molecular pattern and triggers the signaling pathways, involving cGAS-STING, TLR9, and NLRP3. In the present review, we discuss the emerging role of mitochondria in airborne particulate matter-induced immunotoxicity and its myriad biological consequences in health and disease.

Fine Particulate Matter Exposure Alters Pulmonary Microbiota Composition and Aggravates Pneumococcus-Induced Lung Pathogenesis

Exposure to fine particulate matter (PM) with aerodynamic diameter ≤2.5 μm (PM2. 5) is closely correlated with respiratory diseases. Microbiota plays a key role in maintaining body homeostasis including regulation of host immune status and metabolism. As reported recently, PM2. 5 exposure causes microbiota dysbiosis and thus promotes disease progression. However, whether PM2. 5 alters pulmonary microbiota distribution and aggravates bacteria-induced pathogenesis remains unknown. In this study, we used mouse experimental models of PM2. 5 exposure combined with Streptococcus pneumonia infection. We characterized the airway microbiota of bronchoalveolar lavage fluid (BALF) by sequencing the 16S rRNA V3-V4 amplicon on the Illumina MiSeq platform, followed by a combination of bioinformatics and statistical analyses. Shannon-diversity index, observed ASVs, and Fisher's diversity index indicated that microbiota richness was significantly decreased in the mice treated with either PM2. 5 or pneumococcus when compared with the control group. The genera Streptococcus, Prevotella, Leptotrichia, and Granulicatella were remarkably increased in mice exposed to PM2. 5 combined with pneumococcal infection as compared to mice with pneumococcal infection alone. Histopathological examination exhibited that a more pronounced inflammation was present in lungs of mice treated with PM2. 5 and pneumococcus than that in mouse groups exposed to either PM2. 5 or pneumococcal infection alone. Our results demonstrate that PM2. 5 alters the microbiota composition, thereby enhancing susceptibility to pneumococcal infection and exacerbating lung pathogenesis.