Particulate matter disrupts human lung endothelial cell barrier integrity via Rho-dependent pathways

Particulate matter promotes the epithelial to mesenchymal transition in human lung epithelial cells via the ROS pathway

OBJECTS

Epidemiologic studies have linked exposure to airborne pollutant particulate matter (PM) with increased rates of chronic cardiopulmonary diseases, including asthma and idiopathic pulmonary fibrosis (IPF). Several investigations have suggested that the epithelial-to-mesenchymal transition (EMT) may contribute to the complex pathobiology of environmental exposure-mediated pulmonary fibrosis. The present study was designed to characterize the mechanisms of PM-mediated EMT in human lung epithelial cells (HBECs).

METHODS AND RESULTS

PM induced significant dose (0-100 μg/ml) and time (0-72 h)-dependent increases in transforming growth factor β (TGFβ) and fibronectin (FN) protein levels in HBECs lysates. PM-activated TGFβ and FN protein production in HBECs was prevented by the antioxidant N-acetyl-cysteine (NAC, 5 mM). Furthermore, the NF-κB inhibitor BAY11-7082 (5 μM) abolished PM-induced FN production in HBECs. Biomarkers of EMT (ACTA2, SNAIL1 and SNAIL2) in PM-treated HBECs were significantly increased at the mRNA level compared to control cells.

CONCLUSIONS

These results demonstrate that PM increases protein levels of TGFβ and FN via reactive oxygen species (ROS)-dependent pathways. In addition, PM exposure induces EMT in human lung epithelial cells, supporting a novel mechanism for PM-induced pulmonary fibrosis.

Eicosapentaenoic acid (EPA) reduces pulmonary endothelial dysfunction and inflammation due to changes in protein expression during exposure to particulate matter air pollution

AIMS

Inhalation of air pollution small particle matter (PM) is a leading cause of cardiovascular (CV) disease. Exposure to PMs causes endothelial cell (EC) dysfunction as evidenced by nitric oxide (NO) synthase uncoupling, vasoconstriction and inflammation. Eicosapentaenoic acid (EPA) has been shown to mitigate PM-induced adverse cardiac changes in patients receiving omega-3 fatty acid supplementation. We set out to determine the pro-inflammatory effects of multiple PMs (urban and fine) on pulmonary EC NO bioavailability and protein expression, and whether EPA restores EC function under these conditions.

METHODS AND RESULTS

We pretreated pulmonary ECs with EPA and then exposed them to urban or fine air pollution PMs. LC/MS-based proteomic analysis to assess relative expression levels. Expression of adhesion molecules was measured by immunochemistry. The ratio of NO to peroxynitrite (ONOO-) release, an indication of eNOS coupling, was measured using porphyrinic nanosensors following calcium stimulation. Urban/fine PMs also modulated 9/12 and 13/36 proteins, respectively, linked to platelet and neutrophil degranulation pathways and caused > 50% (p < 0.001) decrease in the stimulated NO/ONOO- release ratio. EPA treatment altered expression of proteins involved in these inflammatory pathways, including a decrease in peroxiredoxin-5 and an increase in superoxide dismutase-1. EPA also increased expression of heme oxygenase-1 (HMOX1), a cytoprotective protein, by 2.1-fold (p = 0.024). EPA reduced elevations in sICAM-1 levels by 22% (p < 0.01) and improved the NO/ONOO- release ratio by > 35% (p < 0.05).

CONCLUSION

These cellular changes may contribute to anti-inflammatory, cytoprotective and lipid changes associated with EPA treatment during air pollution exposure.

The Road to Malignant Cell Transformation after Particulate Matter Exposure: From Oxidative Stress to Genotoxicity

In cells, oxidative stress is an imbalance between the production/accumulation of oxidants and the ability of the antioxidant system to detoxify these reactive products. Reactive oxygen species (ROS), cause multiple cellular damages through their interaction with biomolecules such as lipids, proteins, and DNA. Genotoxic damage caused by oxidative stress has become relevant since it can lead to mutation and play a central role in malignant transformation. The evidence describes chronic oxidative stress as an important factor implicated in all stages of the multistep carcinogenic process: initiation, promotion, and progression. In recent years, ambient air pollution by particulate matter (PM) has been cataloged as a cancer risk factor, increasing the incidence of different types of tumors. Epidemiological and toxicological evidence shows how PM-induced oxidative stress could mediate multiple events oriented to carcinogenesis, such as proliferative signaling, evasion of growth suppressors, resistance to cell death, induction of angiogenesis, and activation of invasion/metastasis pathways. In this review, we summarize the findings regarding the involvement of oxidative and genotoxic mechanisms generated by PM in malignant cell transformation. We also discuss the importance of new approaches oriented to studying the development of tumors associated with PM with more accuracy, pursuing the goal of weighing the impact of oxidative stress and genotoxicity as one of the main mechanisms associated with its carcinogenic potential.

Effect of Quercetin on mitoBKCa Channel and Mitochondrial Function in Human Bronchial Epithelial Cells Exposed to Particulate Matter

Particulate matter (PM) exposure increases reactive oxygen species (ROS) levels. It can lead to inflammatory responses and damage of the mitochondria thus inducing cell death. Recently, it has been shown that potassium channels (mitoK) located in the inner mitochondrial membrane are involved in cytoprotection, and one of the mechanisms involves ROS. To verify the cytoprotective role of mitoBKCa, we performed a series of experiments using a patch-clamp, transepithelial electrical resistance assessment (TEER), mitochondrial respiration measurements, fluorescence methods for the ROS level and mitochondrial membrane potential assessment, and cell viability measurements. In the human bronchial epithelial cell model (16HBE14σ), PM < 4 μm in diameter (SRM-PM4.0) was used. We observed that PM decreased TEER of HBE cell monolayers. The effect was partially abolished by quercetin, a mitoBKCa opener. Consequently, quercetin decreased the mitochondrial membrane potential and increased mitochondrial respiration. The reduction of PM-induced ROS level occurs both on cellular and mitochondrial level. Additionally, quercetin restores HBE cell viability after PM administration. The incubation of cells with PM substantially reduced the mitochondrial function. Isorhamnetin had no effect on TEER, the mitoBKCa activity, respiratory rate, or mitochondrial membrane potential. Obtained results indicate that PM has an adverse effect on HBE cells at the cellular and mitochondrial level. Quercetin is able to limit the deleterious effect of PM on barrier function of airway epithelial cells. We show that the effect in HBE cells involves mitoBKCa channel-activation. However, quercetin’s mechanism of action is not exclusively determined by modulation of the channel activity.

Selenium-enriched soybean peptides pretreatment attenuates lung injury in mice induced by fine particulate matters (PM2.5) through inhibition of TLR4/NF-κB/IκBα signaling pathway and inflammasome generation

This study aimed to identify and prepare peptides from selenium (Se)-enriched soybeans and determine whether dietary Se-enriched soybean peptides (Se-SPep) could inhibit lung injury in mice induced by fine particulate matter 2.5 (PM2.5). BALB/c mice were randomly divided into six groups. The mice in the prevention groups were pretreated with 378 mg kg^-1 of Se-SPep, soybean peptides (SPep), and Se-enriched soybean protein (Se-SPro), respectively, for four weeks. The mice in the PM2.5 exposure group received concentrated PM2.5 (15 μg per day mice) for 1 h daily from the third week for two weeks. The results showed that the leukocyte and cytokine (IL-1β, IL-6, TNF-α) levels in the bronchoalveolar lavage fluid (BALF) of the PM2.5 exposure group were higher than those in the control group. Se-SPep pretreatment decreased the IL-1β, IL-6, and TNF-α levels compared with the PM2.5 exposure group. Additionally, Se-SPep pretreatment inhibited TLR4/NF-κB/IκBα and NLRP3/ASC/caspase-1 protein expression in the lungs. In conclusion, Se-SPep pretreatment may protect the lungs of the mice against PM2.5-induced inflammation, suggesting that Se-SPep represents a potential preventative agent to inhibit PM2.5-induced lung injury.

Serum peptidome: diagnostic window into pathogenic processes following occupational exposure to carbon nanomaterials

BACKGROUND

Growing industrial use of carbon nanotubes and nanofibers (CNT/F) warrants consideration of human health outcomes. CNT/F produces pulmonary, cardiovascular, and other toxic effects in animals along with a significant release of bioactive peptides into the circulation, the augmented serum peptidome. While epidemiology among CNT/F workers reports on few acute symptoms, there remains concern over sub-clinical CNT/F effects that may prime for chronic disease, necessitating sensitive health outcome diagnostic markers for longitudinal follow-up.

METHODS

Here, the serum peptidome was assessed for its biomarker potential in detecting sub-symptomatic pathobiology among CNT/F workers using label-free data-independent mass spectrometry. Studies employed a stratified design between High (> 0.5 µg/m3) and Low (< 0.1 µg/m3) inhalable CNT/F exposures in the industrial setting. Peptide biomarker model building and refinement employed linear regression and partial least squared discriminant analyses. Top-ranked peptides were then sequence identified and evaluated for pathological-relevance.

RESULTS

In total, 41 peptides were found to be highly discriminatory after model building with a strong linear correlation to personal CNT/F exposure. The top-five peptide model offered ideal prediction with high accuracy (Q2 = 0.99916). Unsupervised validation affirmed 43.5% of the serum peptidomic variance was attributable to CNT/F exposure. Peptide sequence identification reveals a predominant association with vascular pathology. ARHGAP21, ADAM15 and PLPP3 peptides suggest heightened cardiovasculature permeability and F13A1, FBN1 and VWDE peptides infer a pro-thrombotic state among High CNT/F workers.

CONCLUSIONS

The serum peptidome affords a diagnostic window into sub-symptomatic pathology among CNT/F exposed workers for longitudinal monitoring of systemic health risks.

Activation of mTOR mediates hyperglycemia-induced renal glomerular endothelial hyperpermeability via the RhoA/ROCK/pMLC signaling pathway

OBJECTIVE

Hyperglycemia is associated with albuminuria and renal glomerular endothelial dysfunction in patients with diabetic nephropathy. The mTOR and RhoA/ROCK signaling pathways are involved in glomerular filtration barrier (GFB) regulation, but their role in high glucose (HG)-induced GFB dysfunction in human renal glomerular endothelial cells (HRGECs) has not been investigated. This study aimed to investigate the mechanisms of HG-induced GFB dysfunction in vitro.

MATERIALS AND METHODS

HRGECs were cultured in vitro and exposed to HG. The horseradish peroxidase-albumin leakage and transendothelial electrical resistance of the endothelial monolayer were measured after HG treatment with or without rapamycin preincubation. A fluorescence probe was used to study the distribution of F-actin reorganization. The phosphorylation levels of myosin light chain (MLC) and mTOR were measured via western blotting. RhoA activity was evaluated via GTPase activation assay. The effects of blocking mTOR or the RhoA/ROCK pathway on endothelial permeability and MLC phosphorylation under HG conditions were observed.

RESULTS

HG exposure induced F-actin reorganization and increased MLC phosphorylation, leading to EC barrier disruption. This effect was attenuated by treatment with rapamycin or Y-27632. Phospho-MLC (pMLC) activation in HRGECs was mediated by RhoA/ROCK signaling. mTOR and RhoA/ROCK inhibition or knockdown attenuated pMLC activation, F-actin reorganization and barrier disruption that occurred in response to HG exposure.

CONCLUSIONS

Our results revealed that HG stimulation upregulated RhoA expression and activity through an mTOR-dependent pathway, leading to MLC-mediated endothelial cell cytoskeleton rearrangement and glomerular endothelial barrier dysfunction.

An Integrated Approach of the Potential Underlying Molecular Mechanistic Paradigms of SARS-CoV-2-Mediated Coagulopathy

Coronavirus disease 2019 (Covid-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a pandemic disease which has affected more than 6.2 million people globally, with numbers mounting considerably daily. However, till date, no specific treatment modalities are available for Covid-19 and also not much information is known about this disease. Recent studies have revealed that SARS-CoV-2 infection is associated with the generation of thrombosis and coagulopathy. Fundamentally, it has been believed that a diverse array of signalling pathways might be responsible for the activation of coagulation cascade during SARS-CoV-2 infection. Henceforth, a detailed understanding of these probable underlying molecular mechanistic pathways causing thrombosis in Covid-19 disease deserves an urgent exploration. Therefore, in this review, the hypothetical crosstalk between distinct signalling pathways including apoptosis, inflammation, hypoxia and angiogenesis attributable for the commencement of thrombotic events during SARS-CoV-2 infection has been addressed which might further unravel promising therapeutic targets in Covid-19 disease.

Inhibitory effects of cudratricusxanthone O on particulate matter-induced pulmonary injury

Particulate matter 2.5 (PM_2.5), aerodynamic diameter ≤ 2.5 μm, is the primary air pollutant that plays the key role for lung injury resulted from the loss of vascular barrier integrity. Cudratricusxanthone O (CTXO) is a novel xanthone compound isolated from the root of Cudrania tricuspidata Bureau. Here, we investigated the beneficial effects of CTXO against PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM_2.5-treated ECs and mice. CTXO significantly scavenged PM_2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, CTXO activated Akt, which helped maintain endothelial integrity. Furthermore, CTXO reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid in PM-induced lung tissues. These results indicated that CTXO may exhibit protective effects against PM-induced inflammatory lung injury and vascular hyperpermeability.

Prognostic value of aberrantly expressed methylation genes in human hepatocellular carcinoma

Objectives: To identify the prognostic value of aberrantly methylated differentially expressed genes (DEGs) in hepatocellular carcinoma (HCC) and to explore the underlying mechanisms of tumorigenesis.

Methods: Gene expression profiles (GSE65372 and GSE37988) were analyzed using GEO2R to obtain aberrantly methylated DEGs. Functional enrichment analysis of screened genes was performed by the Database for Annotation, Visualization, and Integrated Discovery (DAVID). Cytoscape software was used to analyze the PPI network and to select hub genes. Transcriptional and proteinic expression data of hub genes were obtained through UALCAN and the Human Protein Reference Database. Finally, we analyzed the prognostic value of hub genes with the Kaplan–Meier Plotter and MethSurv database.

Results: In total, 24 up-hypomethylated oncogenes and 37 down-hypermethylated tumor suppressor genes (TSGs) were identified, and 8 hub genes, including 4 up-hypomethylated oncogenes (CDC5L, MERTK, RHOA and YBX1) and 4 down-hypermethylated TSGs (BCR, DFFA, SCUBE2 and TP63), were selected by PPI. Higher expression of methylated CDC5L-cg05671347, MERTK-cg08279316, RHOA-cg05657651 and YBX1-cg16306148, and lower expression of methylated BCR-cg25410636, DFFA-cg20696875, SCUBE2-cg19000089 and TP63-cg06520450, were associated with better overall survival (OS) in HCC patients. Multivariate analysis also showed they were independent prognostic factors for OS of HCC patients.

Conclusions: In summary, different expression of methylated genes above mentioned were associated with better prognosis in HCC patients. Altering the methylation status of these genes may be a therapeutic target for HCC, but it should be further evaluated in clinical studies.

P53 Regulates the Redox Status of Lung Endothelial Cells

The anti-inflammatory activities of P53 in the vasculature have been associated with the enhancement of the endothelial barrier function. In the present study, we employed human and bovine lung endothelial cells, to investigate whether P53 expression levels affect the redox status of pulmonary cells. Moreover, we tested the possibility that those events affect the endothelial integrity of the lung microvascular monolayers. Our observations suggest that P53 suppression by LPS, pifithrin, or small interfering RNA increased the expression of the redox marker malondialdehyde. In contrast, P53 induction by Nutlin or the Hsp90 inhibitor AUY922 exerted the opposite effects, namely, suppressed that lipid oxidation marker. The direct measurement of the reactive oxygen species by 2,7-Dichlorodihydrofluorescein diacetate confirmed the antioxidant activity of P53 in the vasculature. Furthermore, the increased reactive oxygen species production due to P53 suppression was associated with lung hyperpermeability responses. In conclusion, P53 supports endothelial barrier function, at least in part, via the modulation of the reactive oxygen species.

The critical role of endothelial function in fine particulate matter-induced atherosclerosis

Ambient and indoor air pollution contributes annually to approximately seven million premature deaths. Air pollution is a complex mixture of gaseous and particulate materials. In particular, fine particulate matter (PM2.5) plays a major mortality risk factor particularly on cardiovascular diseases through mechanisms of atherosclerosis, thrombosis and inflammation. A review on the PM2.5-induced atherosclerosis is needed to better understand the involved mechanisms. In this review, we summarized epidemiology and animal studies of PM2.5-induced atherosclerosis. Vascular endothelial injury is a critical early predictor of atherosclerosis. The evidence of mechanisms of PM2.5-induced atherosclerosis supports effects on vascular function. Thus, we summarized the main mechanisms of PM2.5-triggered vascular endothelial injury, which mainly involved three aspects, including vascular endothelial permeability, vasomotor function and vascular reparative capacity. Then we reviewed the relationship between PM2.5-induced endothelial injury and atherosclerosis. PM2.5-induced endothelial injury associated with inflammation, pro-coagulation and lipid deposition. Although the evidence of PM2.5-induced atherosclerosis is undergoing continual refinement, the mechanisms of PM2.5-triggered atherosclerosis are still limited, especially indoor PM2.5. Subsequent efforts of researchers are needed to improve the understanding of PM2.5 and atherosclerosis. Preventing or avoiding PM2.5-induced endothelial damage may greatly reduce the occurrence and development of atherosclerosis.

Inhibitory functions of cardamonin against particulate matter-induced lung injury through TLR2,4-mTOR-autophagy pathways

Particulate matter with an aerodynamic diameter equal to or less than 2.5 μm (PM_2.5) is a form of air pollutant that causes significant lung damage when inhaled. Cardamonin, a flavone found in Alpinia katsumadai Heyata seeds, has been reported to have anti-inflammatory and anticoagulative activity. The aim of this study was to determine the protective effects of cardamonin on PM_2.5-induced lung injury. Mice were treated with cardamonin via tail-vein injection 30 min after the intratracheal instillation of PM_2.5. The results showed that cardamonin markedly reduced the pathological lung injury, lung wet/dry weight ratio, and hyperpermeability caused by PM_2.5. Cardamonin also significantly inhibited PM_2.5-induced myeloperoxidase (MPO) activity in lung tissue, decreased the levels of PM_2.5-induced inflammatory cytokines and effectively attenuated PM_2.5-induced increases in the number of lymphocytes in the bronchoalveolar lavage fluid (BALF). And, cardamonin increased the phosphorylation of mammalian target of rapamycin (mTOR) and dramatically suppressed the PM_2.5-stimulated expression of toll-like receptor 2 and 4 (TLR 2,4), MyD88, and the autophagy-related proteins LC3 II and Beclin 1. In conclusion, these findings indicate that cardamonin has a critical anti-inflammatory effect due to its ability to regulate both the TLR2,4-MyD88 and mTOR-autophagy pathways and may thus be a potential therapeutic agent against PM_2.5-induced lung injury.

The Enigma of Endothelium in COVID-19

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has affected millions of people globally. Clinically, it presents with mild flu-like symptoms in most cases but can cause respiratory failure in high risk population. With the aim of unearthing newer treatments, scientists all over the globe are striving hard to comprehend the underlying mechanisms of COVID-19. Several studies till date have indicated a dysregulated host immune response as the major cause of COVID-19 induced mortality. In this Perspective, we propose a key role of endothelium, particularly pulmonary endothelium in the pathogenesis of COVID-19. We draw parallels and divergences between COVID-19-induced respiratory distress and bacterial sepsis-induced lung injury and recommend the road ahead with respect to identification of endothelium-based biomarkers and plausible treatments for COVID-19.

Inhibitory functions of maslinic acid on particulate matter-induced lung injury through TLR4-mTOR-autophagy pathways

Particulate matter (PM), the collection of all liquid and solid particles suspended in air, includes both organic and inorganic particles, many of which are health-hazards. PM particles with a diameter equal to or less than 2.5 μm (PM_2.5) is a form of air pollutant that causes significant lung damage when inhaled. Maslinic acid (MA) prevents oxidative stress and pro-inflammatory cytokine generation, but there is little information available regarding its role in PM-induced lung injury. Therefore, the purpose of this study was to determine the protective activity of MA against PM_2.5-induced lung injury. The mice were divided into seven groups (n = 10 each): a mock control group, an MA control (0.8 mg/kg mouse body weight) group, an opted PM_2.5 produced from diesel (10 mg/kg mouse body weight) group, a diesel PM_2.5+MA (0.2, 0.4, 0.6, and 0.8 mg/kg mouse body weight) groups. Mice were treated with MA via tail-vein injection 30 min after the intratracheal instillation of a diesel PM_2.5. Changes in the wet/dry weight ratio of the lung tissue, total protein/total cell and lymphocyte counts, inflammatory cytokines in the bronchoalveolar lavage fluid (BALF), vascular permeability, and histology were monitored in diesel PM_2.5-treated mice. The results showed that MA reduced pathological lung injury, the wet/dry weight ratio of the lung tissue, and hyperpermeability caused by diesel PM_2.5. MA also inhibited diesel PM_2.5-induced myeloperoxidase (MPO) activity in the lung tissue, decreased the levels of diesel PM_2.5-induced inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-1β, reduced nitric oxide (NO) and total protein in the BALF, and effectively attenuated diesel PM_2.5-induced increases in the number of lymphocytes in the BALF. In addition, MA increased the protein phosphorylation of the mammalian target of rapamycin (mTOR) and dramatically suppressed diesel PM_2.5-stimulated expression of toll-like receptor 4 (TLR4), MyD88, and the autophagy-related proteins LC3 II and Beclin 1. In conclusion, these findings indicate that MA has a critical anti-inflammatory effect due to its ability to regulate both the TLR4-MyD88 and mTOR-autophagy pathways and may thus be a potential therapeutic agent against diesel PM_2.5-induced lung injury.

PM2.5 induces vascular permeability increase through activating MAPK/ERK signaling pathway and ROS generation

Although in-vivo exposure of PM_2.5 has been suggested to initiate a disorder on vascular permeability, the effects and related mechanism has not been well defined. In this work, an obvious increase on vascular permeability has been confirmed in vivo by vein injection of PM_2.5 into Balb/c mouse. Human umbilical vein vascular endothelial cells and the consisted ex-vivo vascular endothelium were used as model to investigate the effects of PM_2.5 on the vascular permeability and the underlying molecular mechanism. Upon PM_2.5 exposure, the vascular endothelial growth factor receptor 2 on cell membrane phosphorylates and activates the downstream mitogen-activated protein kinase (MAPK)/ERK signaling. The adherens junction protein VE-cadherin sheds and the intercellular junction opens, damaging the integrity of vascular endothelium via paracellular pathway. Besides, PM_2.5 induces the intracellular reactive oxygen species (ROS) production and triggers the oxidative stress including activity decrease of superoxide dismutase, lactate dehydrogenase release and permeability increase of cell membrane. Taken together, the paracellular and transcellular permeability enhancement jointly contributes to the significant increase of endothelium permeability and thus vascular permeability upon PM_2.5 exposure. This work provides an insight into molecular mechanism of PM_2.5 associated cardiovascular disease and offered a real-time screening method for the health risk of PM_2.5.

Biapenem as a Novel Insight into Drug Repositioning against Particulate Matter-Induced Lung Injury

The screening of biologically active chemical compound libraries can be an efficient way to reposition Food and Drug Adminstration (FDA)-approved drugs or to discover new therapies for human diseases. Particulate matter with an aerodynamic diameter equal to or less than 2.5 μm (PM_2.5) is a form of air pollutant that causes significant lung damage when inhaled. This study illustrates drug repositioning with biapenem (BIPM) for the modulation of PM-induced lung injury. Biapenem was used for the treatment of severe infections. Mice were treated with BIPM via tail-vein injection after the intratracheal instillation of PM_2.5. Alterations in the lung wet/dry weight, total protein/total cell count and lymphocyte count, inflammatory cytokines in the bronchoalveolar lavage fluid (BALF), vascular permeability, and histology were monitored in the PM_2.5-treated mice. BIPM effectively reduced the pathological lung injury, lung wet/dry weight ratio, and hyperpermeability caused by PM_2.5. Enhanced myeloperoxidase (MPO) activity by PM_2.5 in the pulmonary tissue was inhibited by BIPM. Moreover, increased levels of inflammatory cytokines and total protein by PM_2.5 in the BALF were also decreased by BIPM treatment. In addition, BIPM markedly suppressed PM_2.5-induced increases in the number of lymphocytes in the BALF. Additionally, the activity of mammalian target of rapamycin (mTOR) was increased by BIPM. Administration of PM_2.5 increased the expression levels of toll-like receptor 4 (TLR4), MyD88, and the autophagy-related proteins LC3 II and Beclin 1, which were suppressed by BIPM. In conclusion, these findings indicate that BIPM has a critical anti-inflammatory effect due to its ability to regulate both the TLR4-MyD88 and mTOR-autophagy pathways, and may thus be a potential therapeutic agent against diesel PM_2.5-induced pulmonary injury.

Deciphering the Code between Air Pollution and Disease: The Effect of Particulate Matter on Cancer Hallmarks

Air pollution has been recognized as a global health problem, causing around 7 million deaths worldwide and representing one of the highest environmental crises that we are now facing. Close to 30% of new lung cancer cases are associated with air pollution, and the impact is more evident in major cities. In this review, we summarize and discuss the evidence regarding the effect of particulate matter (PM) and its impact in carcinogenesis, considering the “hallmarks of cancer” described by Hanahan and Weinberg in 2000 and 2011 as a guide to describing the findings that support the impact of particulate matter during the cancer continuum.

Inhibitory Effects of Black Ginseng on Particulate Matter-Induced Pulmonary Injury

Inhalation of fine particulate matter (PM2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Black ginseng (BG), steamed and dried ginseng nine times, exhibits various pharmacological activities such as antibacterial, antihyperglycemic, anti-atopic, antibacterial, and anti-inflammatory activities. In this study, we investigated the beneficial effects of black ginseng extract (BGE) against PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM2.5-treated ECs and mice. BGE significantly scavenged PM2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, BGE activated Akt, which helped maintain endothelial integrity. Furthermore, BGE reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid in PM-induced lung tissues. These results indicated that BGE may exhibit protective effects against PM-induced inflammatory lung injury and vascular hyperpermeability.

Inhibitory effects of collismycin C and pyrisulfoxin A on particulate matter-induced pulmonary injury

BACKGROUND

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Marine microbial natural products isolated from microbial culture broths were screened for pulmonary protective effects against PM_2.5. Two 2,2'-bipyridine compounds isolated from a red alga-associated Streptomyces sp. MC025-collismycin C (2) and pyrisulfoxin A (5)-were found to inhibit PM_2.5-mediated vascular barrier disruption.

PURPOSE

To confirm the inhibitory effects of collismycin C and pyrisulfoxin A on PM_2.5-induced pulmonary injury STUDY DESIGN: In this study, we investigated the beneficial effects of collismycin C and pyrisulfoxin A on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation.

METHODS

Permeability, leukocyte migration, proinflammatory protein activation, reactive oxygen species (ROS) generation, and histology were evaluated in PM_2.5-treated ECs and mice.

RESULTS

Collismycin C and pyrisulfoxin A significantly scavenged PM_2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase as well as activated Akt, which helped in maintaining endothelial integrity, in purified pulmonary endothelial cells. Furthermore, collismycin C and pyrisulfoxin A reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid of PM-treated mice.

CONCLUSION

These data suggested that collismycin C and pyrisulfoxin A might exert protective effects on PM-induced inflammatory lung injury and vascular hyperpermeability.

Inhibitory effects of compounds isolated from Dioscorea batatas Decne peel on particulate matter-induced pulmonary injury in mice

Particulate matter 2.5 (PM_2.5), with an aerodynamic diameter of ≤2.5 μm, is the primary air pollutant that plays a key role associated with lung injury produced by loss of vascular barrier integrity. Dioscorea batatas Decne (Chinese yam), a perennial plant belonging to Dioscoreaceae family, is widely cultivated in tropical and subtropical regions across Asia. Both aerial parts and root of D. batatas are consumed for nutritional and medicinal purposes. The aim of this study was to (1) identify the bioactive compounds present in D. batatas peel which may be responsible for inhibition of PM_2.5-induced pulmonary inflammation in mice and (2) examine in vitro mechanisms underlying the observed effects of these compounds on mouse lung microvascular endothelial cells. The measured parameters include permeability, leukocyte migration, proinflammatory protein activation, reactive oxygen species (ROS) generation, and histology. Two phenanthrene compounds, 2,7-dihydroxy-4,6-dimethoxyphenanthrene (1) and 6,7-dihydroxy-2,4-dimethoxyphenanthrene (2) were isolated from D. batatas peels. Both these phenanthrene compounds exhibited significant scavenging activity against PM_2.5-induced ROS and inhibited ROS-induced activation of p38 mitogen-activated protein kinase. In addition, enhancement of Akt pathway, involved in the maintenance of endothelial integrity, was noted. These phenanthrene compounds also reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid obtained from PM_2.5-induced lung tissues. Evidence thus indicates that phenanthrene compounds derived from D. batatas may exhibit protective effects against PM_2.5-induced inflammatory lung injury and vascular hyperpermeability in mice.

Inhibitory effects of Kyung-Ok-Ko, traditional herbal prescription, on particulate matter-induced vascular barrier disruptive responses

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. A traditional herbal prescription, Kyung-Ok-Ko (KOK), has long been used in Oriental medicine as a tonic for age-related diseases. In this study, we investigated the beneficial effects of KOK on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM_2.5-treated EC and mice. KOK significantly scavenged PM_2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, KOK activated Akt, which helped maintain endothelial integrity. Furthermore, KOK reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in PM-induced lung tissues. These data suggested that KOK might exhibit protective effects in PM-induced inflammatory lung injury and vascular hyperpermeability.

Respirable Uranyl-Vanadate-Containing Particulate Matter Derived From a Legacy Uranium Mine Site Exhibits Potentiated Cardiopulmonary Toxicity

Exposure to windblown particulate matter (PM) arising from legacy uranium (U) mine sites in the Navajo Nation may pose a human health hazard due to their potentially high metal content, including U and vanadium (V). To assess the toxic impact of PM derived from Claim 28 (a priority U mine) compared with background PM, and consider the putative role of metal species U and V. Two representative sediment samples from Navajo Nation sites (Background PM and Claim 28 PM) were obtained, characterized in terms of chemistry and morphology, and fractioned to the respirable (≤ 10 μm) fraction. Mice were dosed with either PM sample, uranyl acetate, or vanadyl sulfate via aspiration (100 µg), with assessments of pulmonary and vascular toxicity 24 h later. Particulate matter samples were also examined for in vitro effects on cytotoxicity, oxidative stress, phagocytosis, and inflammasome induction. Claim 28 PM10 was highly enriched with U and V and exhibited a unique nanoparticle ultrastructure compared with background PM10. Claim 28 PM10 exhibited enhanced pulmonary and vascular toxicity relative to background PM10. Both U and V exhibited complementary pulmonary inflammatory potential, with U driving a classical inflammatory cytokine profile (elevated interleukin [IL]-1β, tumor necrosis factor-α, and keratinocyte chemoattractant/human growth-regulated oncogene) while V preferentially induced a different cytokine pattern (elevated IL-5, IL-6, and IL-10). Claim 28 PM10 was more potent than background PM10 in terms of in vitro cytotoxicity, impairment of phagocytosis, and oxidative stress responses. Resuspended PM10 derived from U mine waste exhibit greater cardiopulmonary toxicity than background dusts. Rigorous exposure assessment is needed to gauge the regional health risks imparted by these unremediated sites.

Inhibitory effects of protopanaxatriol type ginsenoside fraction (Rgx365) on particulate matter-induced pulmonary injury

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury attributed to the loss of vascular barrier integrity. Black ginseng (BG), steamed 9 times and dried ginseng, and its major protopanaxatriol type ginsenosides (ginsenoside Rg4, Rg6, Rh4, Rh1, and Rg2) exhibited various biological activities including anti-septic, anti-diabetic, wound healing, immune-stimulatory, and anti-antioxidant activity. The aim of this study was to investigate the beneficial effects of Rgx365 (a protopanaxatriol type rare ginsenosides fraction) on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM_2.5-treated EC and mice. Rgx365 significantly scavenged PM_2.5-induced ROS, inhibited ROS-induced activation of p38 mitogen-activated protein kinase (MAPK), activated Akt in purified pulmonary EC, which helped maintain endothelial integrity. Further, Rgx365 reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in PM-induced mouse lung tissues. Data suggested that Rgx365 might exhibit protective effects in PM-induced inflammatory lung injury and vascular hyperpermeability.

Role of truncated oxidized phospholipids in acute endothelial barrier dysfunction caused by particulate matter

Particulate matter (PM) air pollution is a global environmental health problem contributing to more severe lung inflammation and injury. However, the molecular and cellular mechanisms of PM-induced exacerbation of lung barrier dysfunction and injury are not well understood. In the current study, we tested a hypothesis that PM exacerbates vascular barrier dysfunction via ROS-induced generation of truncated oxidized phospholipids (Tr-OxPLs). Treatment of human pulmonary endothelial cells with PM caused endothelial cell barrier disruption in a dose-dependent fashion. Biochemical analysis showed destabilization of cell junctions by PM via tyrosine phosphorylation and internalization of VE-cadherin. These events were accompanied by PM-induced generation of Tr-OxPLs, detected by mass spectrometry analysis. Furthermore, purified Tr-OxPLs: POVPC, PGPC and lyso-PC alone, caused a rapid increase in endothelial permeability and augmented pulmonary endothelial barrier dysfunction induced by submaximal doses of PM. In support of a role of TR-OxPLs-dependent mechanism in mediation of PM effects, ectopic expression of intracellular type 2 platelet-activating factor acetylhydrolase (PAFAH2), which specifically hydrolyzes Tr-OxPLs, significantly attenuated PM-induced endothelial hyperpermeability. In summary, this study uncovered a novel mechanism of PM-induced sustained dysfunction of pulmonary endothelial cell barrier which is driven by PM-induced generation of truncated products of phospholipid oxidation causing destabilization of cell junctions.

Microtubule destabilization caused by particulate matter contributes to lung endothelial barrier dysfunction and inflammation

Exposure to particulate matter (PM) associated with air pollution remains a major public health concern, as it has been linked to significant increase in cardiopulmonary morbidity and mortality. Lung endothelial cell (EC) dysfunction is one of the hallmarks of cardiovascular events of lung exposure to PM. However, the role of PM in acute lung injury (ALI) exacerbation and delayed recovery remains incompletely understood. This study tested a hypothesis that PM augments lung injury and EC barrier dysfunction via microtubule-dependent mechanisms. Our data demonstrate that in pulmonary EC PM caused time- and dose-dependent remodeling of actin cytoskeleton and considerable destabilization of the microtubule (MT) network. These events led to the weakening of cell junctions and formation of actin stress fibers, resulting in disruption of lung EC monolayer and increased permeability. PM also caused ROS-dependent activation of MT-specific deacetylase, HDAC6. Suppression of HDAC6 activity by pharmacological inhibitors or siRNA-based depletion of HDAC6 abolished PM-induced EC permeability increase, which was accompanied by reduced activation of stress kinase signaling, inhibition of Rho cascade, decreased IL-6 production and suppressed activation of its downstream target STAT3. Pretreatment of pulmonary EC with IL-6 inhibitor led to inhibition of STAT3 activity and decreased PM-induced hyper-permeability. Because one of the major activators of Rho-GTPase, GEFH1, is localized on the MT, we examined its involvement in PM-caused EC barrier compromise. Inhibition of GEF-H1 activation significantly attenuated PM-induced permeability increase. Moreover, combined inhibition of IL-6 and GEF-H1 signaling exhibited additive protective effect. Taken together, these results demonstrate a critical involvement of MT-associated signaling in the PM-induced exacerbation of lung EC barrier compromise and inflammatory response.

Adenoviral vector-induced silencing of RGMa attenuates blood-brain barrier dysfunction in a rat model of MCAO/reperfusion

BACKGROUND

Repulsive guidance molecule A (RGMa) is implicated in focal cerebral ischemia-reperfusion (I/R) injury, but its mechanisms are still largely unknown. This work focused on the effects of RGMa on the blood-brain barrier (BBB) after focal cerebral I/R injury.

METHODS

Sprague-Dawley (SD) rats were randomly divided into four groups: sham, middle cerebral artery occlusion (MCAO)/reperfusion (I/R), MCAO/reperfusion administered recombinant adenovirus expressing sh-con (I/R + sh-con) and MCAO/reperfusion administered recombinant adenovirus expressing sh-RGMa (I/R + sh-RGMa) groups. Infarct volume, brain edema and neurological scores were evaluated at 3 day after reperfusion. Evens blue leakage and transmission electron microscopy was performed. And the expression level of claudin-5 and ZO-1, CDC-42 and PAK-1, RGMa were detected by western blot.

RESULTS

Compared with I/R or I/R + sh-con groups, I/R + sh-RGMa group showed smaller infarction volume, attenuated brain edema, improved neurological scores and better BBB integrity, such as reduced Evans blue leakage and ultra-structural change. We also observed improved BBB function followed by down-regulation of MMP-9 and up-regulation of claudin-5 and ZO-1 in the I/R + sh-RGMa group. In addition, up-regulation of the CDC-42 and PAK-1 in the I/R + sh-RGMa group was obtained.

CONCLUSIONS

RGMa may be involved in I/R injury associated with BBB dysfunction via the CDC-42/PAK-1 signal pathway and may be a promising therapeutic target for I/R injury.

Fine Particulate Matter Pollution and Risk of Community-Acquired Sepsis

While air pollution has been associated with health complications, its effect on sepsis risk is unknown. We examined the association between fine particulate matter (PM_2.5) air pollution and risk of sepsis hospitalization. We analyzed data from the 30,239 community-dwelling adults in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort linked with satellite-derived measures of PM_2.5 data. We defined sepsis as a hospital admission for a serious infection with ≥2 systemic inflammatory response (SIRS) criteria. We performed incidence density sampling to match sepsis cases with 4 controls by age (±5 years), sex, and race. For each matched group we calculated mean daily PM_2.5 exposures for short-term (30-day) and long-term (one-year) periods preceding the sepsis event. We used conditional logistic regression to evaluate the association between PM_2.5 exposure and sepsis, adjusting for education, income, region, temperature, urbanicity, tobacco and alcohol use, and medical conditions. We matched 1386 sepsis cases with 5544 non-sepsis controls. Mean 30-day PM_2.5 exposure levels (Cases 12.44 vs. Controls 12.34 µg/m³; p = 0.28) and mean one-year PM_2.5 exposure levels (Cases 12.53 vs. Controls 12.50 µg/m³; p = 0.66) were similar between cases and controls. In adjusted models, there were no associations between 30-day PM_2.5 exposure levels and sepsis (4th vs. 1st quartiles OR: 1.06, 95% CI: 0.85–1.32). Similarly, there were no associations between one-year PM_2.5 exposure levels and sepsis risk (4th vs. 1st quartiles OR: 0.96, 95% CI: 0.78–1.18). In the REGARDS cohort, PM_2.5 air pollution exposure was not associated with risk of sepsis.