PM2.5 promotes human bronchial smooth muscle cell migration via the sonic hedgehog signaling pathway

Biomass fuels related-PM2.5 promotes lung fibroblast-myofibroblast transition through PI3K/AKT/TRPC1 pathway

Emerging evidence has suggested that exposure to PM2.5 is a significant contributing factor to the development of chronic obstructive pulmonary disease (COPD). However, the underlying biological effects and mechanisms of PM2.5 in COPD pathology remain elusive. In this study, we aimed to investigate the implication and regulatory effect of biomass fuels related-PM2.5 (BRPM2.5) concerning the pathological process of fibroblast-to-myofibroblast transition (FMT) in the context of COPD. In vivo experimentation revealed that exposure to biofuel smoke was associated with airway inflammation in rats. After 4 weeks of exposure, there was inflammation in the small airways, but no significant structural changes in the airway walls. However, after 24 weeks, airway remodeling occurred due to increased collagen deposition, myofibroblast proliferation, and tracheal wall thickness. In vitro, cellular immunofluorescence results showed that with stimulation of BRPM2.5 for 72 h, the cell morphology of fibroblasts changed significantly, most of the cells changed from spindle-shaped to star-shaped irregular, α-SMA stress fibers appeared in the cytoplasm and the synthesis of type I collagen increased. The collagen gel contraction experiment showed that the contractility of fibroblasts was enhanced. The expression level of TRPC1 in fibroblasts was increased. Specific siRNA-TRPC1 blocked BRPM2.5-induced FMT and reduced cell contractility. Additionally, specific siRNA-TRPC1 resulted in a decrease in the augment of intracellular Ca2+ concentration ([Ca2+]i) induced by BRPM2.5. Notably, it was found that the PI3K inhibitor, LY294002, inhibited enhancement of AKT phosphorylation level, FMT occurrence, and elevation of TRPC1 protein expression induced by BRPM2.5. The findings indicated that BRPM2.5 is capable of inducing the FMT, with the possibility of mediation by PI3K/AKT/TRPC1. These results hold potential implications for the understanding of the molecular mechanisms involved in BRPM2.5-induced COPD and may aid in the development of novel therapeutic strategies for pathological conditions characterized by fibrosis.

PM2.5 exposure-induced senescence-associated secretory phenotype in airway smooth muscle cells contributes to airway remodeling

Fine particulate matter (PM2.5) has been linked to increased severity and incidence of airway diseases, especially chronic obstructive pulmonary disease (COPD) and asthma. Airway remodeling is an important event in both COPD and asthma, and airway smooth muscle cells (ASMCs) are key cells which directly involved in airway remodeling. However, it was unclear how PM2.5 affected ASMCs. This study investigates the effects of PM2.5 on airway smooth muscle and its mechanism. We first showed that inhaled particulate matter was distributed in the airway smooth muscle bundle, combined with increased airway smooth muscle bundle and collagen deposition in vivo. Then, we demonstrated that PM2.5 induced up-regulation of collagen-I and alpha-smooth muscle actin (α-SMA) expression in rat and human ASMCs in vitro. Next, we found PM2.5 led to rat and human ASMCs senescence and exhibited senescence-associated secretory phenotype (SASP) by autophagy-induced GATA4/TRAF6/NF-κB signaling, which contributed to collagen-I and α-SMA synthesis as well as airway smooth muscle remodeling. Together, our results provided evidence that SASP induced by PM2.5 in airway smooth muscle cells prompted airway remodeling.

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

Background

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

Methods

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

Results

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

Conclusions

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

The mediating role of exhaled breath condensate metabolites in the effect of particulate matter on pulmonary function in schoolchildren: A crossover intervention study

The role played by metabolites in exhaled breath condensate (EBC) in the effect of PM on schoolchildren's pulmonary function has received little attention. Accordingly, we examined whether metabolites in EBC mediated the effect of PM10, PM2.5, and PM1 on the pulmonary function of schoolchildren at a residential primary school who had received an air-cleaner cross-over intervention. Samples of EBC were collected from a total of 60 schoolchildren and subjected to metabolomics analysis. We found that the effect of PM on six pulmonary function indicators was mediated by the following nine lipid peroxidation-related and energy metabolism-related metabolites present in EBC: 4-hydroxynonenal, arachidoyl ethanolamide, dl-pyroglutamic acid, 5-deoxy-d-glucose, myristic acid, lauric acid, linoleic acid, l-proline, and palmitic acid. However, while all nine of these metabolites mediated the effects of PM on boys' pulmonary function, only 4-hydroxynonenal, arachidoyl ethanolamide, and dl-pyroglutamic acid mediated the effects of PM on girls' pulmonary function. Overall, our results show that (1) short-term exposure to PM affected the schoolchildren's pulmonary function by causing an imbalance between lipid peroxidation and glutathione-based antioxidant activity and by perturbing energy metabolism in respiratory system and (2) there was a sex-dependent antioxidant response to PM exposure, with boys being less resistant than girls.

BMAL1/p53 mediating bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma

BACKGROUND

Fine particulate matter (PM2.5) is associated with increased incidence and severity of asthma. PM2.5 exposure disrupts airway epithelial cells, which elicits and sustains PM2.5-induced airway inflammation and remodeling. However, the mechanisms underlying development and exacerbation of PM2.5-induced asthma were still poorly understood. The aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a major circadian clock transcriptional activator that is also extensively expressed in peripheral tissues and plays a crucial role in organ and tissue metabolism.

RESULTS

In this study, we found PM2.5 aggravated airway remodeling in mouse chronic asthma, and exacerbated asthma manifestation in mouse acute asthma. Next, low BMAL1 expression was found to be crucial for airway remodeling in PM2.5-challenged asthmatic mice. Subsequently, we confirmed that BMAL1 could bind and promote ubiquitination of p53, which can regulate p53 degradation and block its increase under normal conditions. However, PM2.5-induced BMAL1 inhibition resulted in up-regulation of p53 protein in bronchial epithelial cells, then increased-p53 promoted autophagy. Autophagy in bronchial epithelial cells mediated collagen-I synthesis as well as airway remodeling in asthma.

CONCLUSIONS

Taken together, our results suggest that BMAL1/p53-mediated bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma. This study highlights the functional importance of BMAL1-dependent p53 regulation during asthma, and provides a novel mechanistic insight into the therapeutic mechanisms of BMAL1. Video Abstract.

Stressed out - The role of oxidative stress in airway smooth muscle dysfunction in asthma and COPD

The airway smooth muscle (ASM) surrounding the airways is dysfunctional in both asthma and chronic obstructive pulmonary disease (COPD), exhibiting; increased contraction, increased mass, increased inflammatory mediator release and decreased corticosteroid responsiveness. Due to this dysfunction, ASM is a key contributor to symptoms in patients that remain symptomatic despite optimal provision of currently available treatments. There is a significant body of research investigating the effects of oxidative stress/ROS on ASM behaviour, falling into the following categories; cigarette smoke and associated compounds, air pollutants, aero-allergens, asthma and COPD relevant mediators, and the anti-oxidant Nrf2/HO-1 signalling pathway. However, despite a number of recent reviews addressing the role of oxidative stress/ROS in asthma and COPD, the potential contribution of oxidative stress/ROS-related ASM dysfunction to asthma and COPD pathophysiology has not been comprehensively reviewed. We provide a thorough review of studies that have used primary airway, bronchial or tracheal smooth muscle cells to investigate the role of oxidative stress/ROS in ASM dysfunction and consider how they could contribute to the pathophysiology of asthma and COPD. We summarise the current state of play with regards to clinical trials/development of agents targeting oxidative stress and associated limitations, and the adverse effects of oxidative stress on the efficacy of current therapies, with reference to ASM related studies where appropriate. We also identify limitations in the current knowledge of the role of oxidative stress/ROS in ASM dysfunction and identify areas for future research.

Biomass-related PM2.5 induces mitochondrial fragmentation and dysfunction in human airway epithelial cells

The use of biomass for cooking and heating is considered an important factor associated with chronic obstructive pulmonary disease (COPD), but few studies have previously addressed its underlying mechanisms. Therefore, this research aimed to evaluate the effects of biomass-related PM_2.5 (BRPM_2.5) exposure on 16HBE human airway epithelial cells and in mice with regard to mitochondrial dysfunction. Our study indicated that BRPM_2.5 exposure of 16HBE cells resulted in mitochondrial dysfunction, including decreased mitochondrial membrane potential, increased expression of fission proteins-phospho-DRP1, increased mitochondrial ROS (mtROS), and decreased levels of ATP. BRPM_2.5 altered the mitochondrial metabolism of 16HBE cells by decreasing mitochondrial oxygen consumption and glycolysis. However, Mitochondria targeted peptide SS-31 eliminated mitochondrial ROS and alleviated the ATP deficiency and proinflammatory cytokines release. BRPM2.5 exposure resulted in abnormal mitochondrial morphological alterations both in 16HBE and in lung tissue. Taken together, these results suggest that BRPM_2.5 has detrimental effects on human airway epithelial cells, leading to mitochondrial dysfunction, abnormal mitochondrial metabolism and altered mitochondrial dynamics. The present study provides the first evidence that disruption of mitochondrial structure and mitochondrial metabolism may be one of the mechanisms of BRPM_2.5-induced respiratory dysfunction.

Potential cellular endocrinology mechanisms underlying the effects of Chinese herbal medicine therapy on asthma

Asthma is a complex syndrome with polygenetic tendency and multiple phenotypes, which has variable expiratory airflow limitation and respiratory symptoms that vary over time and in intensity. In recent years, continuous industrial development has seriously impacted the climate and air quality at a global scale. It has been verified that climate change can induce asthma in predisposed individuals and that atmospheric pollution can exacerbate asthma severity. At present, a subset of patients is resistant to the drug therapy for asthma. Hence, it is urgent to find new ideas for asthma prevention and treatment. In this review, we discuss the prescription, composition, formulation, and mechanism of traditional Chinese medicine monomer, traditional Chinese medicine monomer complex, single herbs, and traditional Chinese patent medicine in the treatment of asthma. We also discuss the effects of Chinese herbal medicine on asthma from the perspective of cellular endocrinology in the past decade, emphasizing on the roles as intracellular and extracellular messengers of three substances-hormones, substances secreted by pulmonary neuroendocrine cells, and neuroendocrine-related signaling protein-which provide the theoretical basis for clinical application and new drug development.

Novel insights into the role of BRD4 in fine particulate matter induced airway hyperresponsiveness

Epidemiological research has identified that exposure to fine particulate matter (PM2.5) can increase airway hyperresponsiveness (AHR) which is considered a typical characteristic of asthma. Although the effect of PM2.5 on AHR has been elucidated to a certain degree, its exact mechanism remains unclear. Bromodomain-containing protein 4 (BRD4) is recognized as a member of the bromodomain and extraterminal (BET) family, with the ability to maintain higher-order chromatin configuration and regulate gene expression programs. The primary objective of our study was to examine the role of BRD4 in AHR triggered by PM2.5, and to elucidate its possible molecular mechanism. A mouse model with AHR was established using a nose-only PM2.5 exposure system. We observed that PM2.5 enhanced AHR in the experimental group compared to the control group, and this alteration was accompanied by increased lung inflammation and BRD4 expression in bronchi-lung tissue. However, the BRD4 inhibitor (ZL0420) could alleviate the aforementioned alterations in the mouse model with PM2.5 exposure. To explore the exact molecular mechanism, we further examined the role of BRD4 in human airway smooth muscle cells (hASMCs) after exposure to PM2.5 DMSO extracts. We found that PM2.5 DMSO extracts, which promoted the contraction and migration of hASMCs, was accompanied by an increase in the levels of BRD4, kallikrein 14 (KLK14), bradykinin 2 receptor (B2R), matrix metalloproteinases2(MMP-2), matrix metalloproteinases9(MMP-9), vimentin and bradykinin (BK) secretion, while ZL0420 and BRD4 gene silencing could reverse this response. In summary, these results demonstrate that BRD4 is an important player in AHR triggered by PM2.5, and BRD4 inhibition can ameliorate AHR induced by PM2.5. In addition, PM2.5 DMSO extracts can promote the contraction and migration of hASMCs by increasing BRD4 expression.

LncRNA RP11-86H7.1 promotes airway inflammation induced by TRAPM2.5 by acting as a ceRNA of miRNA-9-5p to regulate NFKB1 in HBECS

Traffic-related air pollution particulate matter 2.5 (TRAPM2.5), is involved in chronic obstructive pulmonary disease (COPD), which is characterized by airway inflammation. Specifically, these harmful particles or gases can increase chronic airway inflammation. Some recent studies have shown that lncRNAs are closely related to COPD and participate in the regulation of airway inflammation. However, the precise mechanisms remain unknown. In the present study, we investigated the effect of TRAPM2.5 on airway inflammation in human bronchial epithelial cells (HBECs) and the underlying mechanisms mediated by a lncRNA. After exposure to TRAPM2.5, the novel lncRNA RP11-86H7.1 was markedly upregulated in HBECs. Functional assays indicated that the lncRNA RP11-86H7.1 was required for the TRAPM2.5-induced expression of inflammatory factors in HBECs. A mechanistic study demonstrated that lncRNA RP11-86H7.1 might participate in TRAPM2.5-induced inflammatory responses by activating the NF-κB signaling pathway. Moreover, the lncRNA RP11-86H7.1 can promote the inflammatory response by acting as a competing endogenous RNA of miR-9-5p, reversing the inhibitory effect of its target gene NFKB1, and sustaining NF-κB activation. In summary, our study elucidates the pro-inflammatory roles of the lncRNA RP11-86H7.1–miR-9-5p–NFKB1 regulatory network in airway inflammation induced by TRAPM2.5 and indicates that the components of this network might serve as novel diagnostic biomarkers and potential therapeutic targets.

Nanodomains in cardiopulmonary disorders and the impact of air pollution

Air pollution is a major environmental threat and each year about 7 million people reported to die as a result of air pollution. Consequently, exposure to air pollution is linked to increased morbidity and mortality world-wide. Diesel automotive engines are a major source of urban air pollution in the western societies encompassing particulate matter and diesel exhaust particles (DEP). Air pollution is envisioned as primary cause for cardiovascular dysfunction, such as ischemic heart disease, cardiac dysrhythmias, heart failure, cerebrovascular disease and stroke. Air pollution also causes lung dysfunction, such as chronic obstructive pulmonary disease (COPD), asthma, idiopathic pulmonary fibrosis (IPF), and specifically exacerbations of these diseases. DEP induces inflammation and reactive oxygen species production ultimately leading to mitochondrial dysfunction. DEP impair structural cell function and initiate the epithelial-to-mesenchymal transition, a process leading to dysfunction in endothelial as well as epithelial barrier, hamper tissue repair and eventually leading to fibrosis. Targeting cyclic adenosine monophosphate (cAMP) has been implicated to alleviate cardiopulmonary dysfunction, even more intriguingly cAMP seems to emerge as a potent regulator of mitochondrial metabolism. We propose that targeting of the mitochondrial cAMP nanodomain bear the therapeutic potential to diminish air pollutant — particularly DEP — induced decline in cardiopulmonary function.

Immunologic and Non-Immunologic Mechanisms Leading to Airway Remodeling in Asthma

Asthma increases worldwide without any definite reason and patient numbers double every 10 years. Drugs used for asthma therapy relax the muscles and reduce inflammation, but none of them inhibited airway wall remodeling in clinical studies. Airway wall remodeling can either be induced through pro-inflammatory cytokines released by immune cells, or direct binding of IgE to smooth muscle cells, or non-immunological stimuli. Increasing evidence suggests that airway wall remodeling is initiated early in life by epigenetic events that lead to cell type specific pathologies, and modulate the interaction between epithelial and sub-epithelial cells. Animal models are only available for remodeling in allergic asthma, but none for non-allergic asthma. In human asthma, the mechanisms leading to airway wall remodeling are not well understood. In order to improve the understanding of this asthma pathology, the definition of “remodeling” needs to be better specified as it summarizes a wide range of tissue structural changes. Second, it needs to be assessed if specific remodeling patterns occur in specific asthma pheno- or endo-types. Third, the interaction of the immune cells with tissue forming cells needs to be assessed in both directions; e.g., do immune cells always stimulate tissue cells or are inflamed tissue cells calling immune cells to the rescue? This review aims to provide an overview on immunologic and non-immunologic mechanisms controlling airway wall remodeling in asthma.

PM2.5, Fine Particulate Matter: A Novel Player in the Epithelial-Mesenchymal Transition?

Epithelial-mesenchymal transition (EMT) refers to the conversion of epithelial cells to mesenchymal phenotype, which endows the epithelial cells with enhanced migration, invasion, and extracellular matrix production abilities. These characteristics link EMT with the pathogenesis of organ fibrosis and cancer progression. Recent studies have preliminarily established that fine particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5) is correlated with EMT initiation. In this pathological process, PM_2.5 particles, excessive reactive oxygen species (ROS) derived from PM_2.5, and certain components in PM_2.5, such as ions and polyaromatic hydrocarbons (PAHs), have been implicated as potential EMT mediators that are linked to the activation of transforming growth factor β (TGF-β)/SMADs, NF-κB, growth factor (GF)/extracellular signal-regulated protein kinase (ERK), GF/phosphatidylinositol 3-kinase (PI3K)/Akt, wingless/integrated (Wnt)/β-catenin, Notch, Hedgehog, high mobility group box B1 (HMGB1)-receptor for advanced glycation end-products (RAGE), and aryl hydrocarbon receptor (AHR) signaling cascades and to cytoskeleton rearrangement. These pathways directly and indirectly transduce pro-EMT signals that regulate EMT-related gene expression in epithelial cells, finally inducing the characteristic alterations in morphology and functions of epithelia. In addition, novel associations between autophagy, ATP citrate lyase (ACLY), and exosomes with PM_2.5-induced EMT have also been summarized. However, some debates and paradoxes remain to be consolidated. This review discusses the potential molecular mechanisms underlying PM_2.5-induced EMT, which might account for the latent role of PM_2.5 in cancer progression and fibrogenesis.

Crosstalk Between Signaling Pathways Involved in the Regulation of Airway Smooth Muscle Cell Hyperplasia

Increased ASM mass, primarily due to ASM hyperplasia, has been recognized as a hallmark of airway remodeling in asthma. Increased ASM mass is the major contributor to the airway narrowing, thus worsening the bronchoconstriction in response to stimuli. Inflammatory mediators and growth factors released during inflammation induce increased ASM mass surrounding airway wall via increased ASM proliferation, diminished ASM apoptosis and increased ASM migration. Several major pathways, such as MAPKs, PI3K/AKT, JAK2/STAT3 and Rho kinase, have been reported to regulate these cellular activities in ASM and were reported to be interrelated at certain points. This article aims to provide an overview of the signaling pathways/molecules involved in ASM hyperplasia as well as the mapping of the interplay/crosstalk between these major pathways in mediating ASM hyperplasia. A more comprehensive understanding of the complexity of cellular signaling in ASM cells will enable more specific and safer drug development in the control of asthma.

Fine-particulate matter aggravates cigarette smoke extract-induced airway inflammation via Wnt5a-ERK pathway in COPD

Background

Exposure to environmental particulate matter (PM) ≤2.5 μm in diameter (PM_2.5) and smoking are common contributors to COPD, and pertinent research implicates both factors in pulmonary inflammation. Using in vivo mouse and in vitro human cellular models, we investigated the joint impact of PM_2.5 pollution, and cigarette smoke (CS) in mice or cigarette-smoke extract (CSE) in cells on COPD inflammation, and explored potential mechanisms.

Methods

Tissue changes in lungs of C57BL/6 mice exposed to PM_2.5 and CS were studied by light microscopy, H&E, immunochemistry, and immunofluorescence-stained sections. Levels of inflammatory factors induced by PM_2.5/CS in mice and PM_2.5/CSE in 16HBE cells were also monitored by quantitative reverse-transcription (qRT)-PCR and ELISA. Expression of genes related to the Wnt5a-signaling pathway was assessed at transcriptional and protein levels using immunofluorescence, qRT-PCR, and Western blotting.

Results

Inflammatory response to combined exposure of PM_2.5 and CS or CSE in mouse and 16HBE cells surpassed responses incited separately. Although separate PM_2.5 and CS/CSE exposure upregulated the expression of Wnt5a (a member of the Wnt-secreted glycoprotein family), combined PM_2.5 and CS/CSE exposure produced a steeper rise in Wnt5a levels. Use of a Wnt5a antagonist (BOX5) successfully blocked related inflammatory effects. ERK phosphorylation appeared to mediate the effects of Wnt5a in the COPD model, promoting PM_2.5 aggravation of CS/CSE-induced airway inflammation.

Conclusion

Our findings suggest that combined PM_2.5 and CS/CSE exposure induce airway inflammation and Wnt5a expression in vivo in mice and in vitro in 16HBE cells. Furthermore, PM_2.5 seems to aggravate CS/CSE-induced inflammation via the Wnt5a–ERK pathway in the context of COPD.

Fine particulate matter (PM2.5) aggravates apoptosis of cigarette-inflamed bronchial epithelium in vivo and vitro

Fine particulate matter (PM2.5) is an essential risk factor of chronic obstructive pulmonary disease (COPD). Recent studies showed weak association between PM2.5 and COPD incidence, but smokers who exposed to higher PM2.5 concentration had more opportunity to gain COPD. Cigarette smoking is the most important risk factor of COPD. Thus, we hypothesized: the role of PM2.5 played on cigarette-inflamed airways was more significant than normal airways. The study firstly established an animal model of C57BL/6J mice with cigarette smoke exposure and PM2.5 orotracheal administration. After calculating pathological scores, mean linear intercept and mean alveolar area, we found PM2.5 aggravated pathological injury of cigarette-inflamed lungs, but the injury on normal lungs was not significant. Meanwhile, inflammatory factors as T-bet, IFN-γ and IL-1α were tested using qRT-PCR and ELISA. The results showed PM2.5 aggravated inflammation of cigarette-inflamed lungs, but the effect on normal lungs was not significant. The most important pathogenesis of COPD is abnormal apoptosis in airway epithelium, due to oxidative stress following long-term exposure to cigarette smoke. Then, apoptotic responses were detected in lungs. TUNEL analysis demonstrated that PM2.5 promoted DNA fragmentation of cigarette-inflamed lungs, but the effect on normal lungs was not significant. Western-blot and immunohistochemistry showed caspase activated significantly in PM2.5-cigarette smoke exposed lungs and activated caspase 3 located mainly on bronchial epithelium. Next, human bronchial epithelial cells were cultured treated with cigarette smoke solution (CSS) with or without PM2.5. Z-VAD-FMK, a pan-caspase inhibitor, was used to suppress the activation of caspases. After analyzing cell viability, DNA fragmentation, mitochondrial activities and caspase activities, the results clarified that PM2.5 aggravated apoptosis in cigarette-inflamed bronchial epithelial cells and the responses could be suppressed by Z-VAD-FMK. Our results gave a new idea about the mechanism of PM2.5 on COPD and inferred cigarette-inflamed airways were more vulnerable to PM2.5 than normal airways.

Effects of Different Components of PM2.5 on the Expression Levels of NF-κB Family Gene mRNA and Inflammatory Molecules in Human Macrophage

Background: Studies have found that exposure to fine particulate matter with sizes below 2.5 µm (PM2.5) might cause inflammation response via the NF-κB pathway. To date, only a few studies have focused on the toxicity of different components of PM2.5. We aimed to explore the effects of PM2.5 with different components on the expression levels of NF-κB family gene mRNA and inflammatory molecules in human macrophages. Methods: Human monocytic cell line THP-1-derived macrophages were exposed to water-soluble (W-PM2.5), fat-soluble (F-PM2.5), and insoluble (I-PM2.5) PM2.5. The cell survival rate was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of inflammatory molecules were determined by enzyme-linked immunosorbent assay (ELISA), and the relative mRNA levels of the NF-κB family gene were determined by real time PCR. Results: PM2.5 could decrease the cell viability. After exposure to W-PM2.5, the levels of interleukins (IL)-1β and IL-12 p70 significantly increased. After exposure to F-PM2.5, the levels of IL-12 p70 significantly increased. The levels of IL-12 p70 and TNF-α after exposure to I-PM2.5 were significantly higher than that in W- and F-PM2.5 treatment groups. The levels of IL-8, C reactive protein (CRP), and cyclooxygenase (COX)-2 increased only after exposure to I-PM2.5. F-PM2.5 increased the mRNA levels of NF-κB genes, especially NF-κB1 and RelA. Conclusions: PM2.5 can decrease the cell survival rate and up-regulate the expression of NF-κB family gene mRNA and inflammatory molecules. The main toxic components of PM2.5 related to inflammatory response in macrophages were the I-PM2.5.

MiR-520b promotes the progression of non-small cell lung cancer through activating Hedgehog pathway

Although the non-small cell lung cancer (NSCLC) is one of the most malignant tumours worldwide, the mechanisms controlling NSCLC tumourigenesis remain unclear. Here, we find that the expression of miR-520b is up-regulated in NSCLC samples. Further studies have revealed that miR-520b promotes the proliferation and metastasis of NSCLC cells. In addition, miR-520b activates Hedgehog (Hh) pathway. Inhibitor of Hh pathway could relieve the oncogenic effect of miR-520b upon NSCLC cells. Mechanistically, we demonstrate that miR-520b directly targets SPOP 3'-UTR and decreases SPOP expression, culminating in GLI2/3 stabilization and Hh pathway hyperactivation. Collectively, our findings unveil that miR-520b promotes NSCLC tumourigenesis through SPOP-GLI2/3 axis and provide miR-520b as a potential diagnostic biomarker and therapeutic target for NSCLC.

PM2.5 downregulates miR-194-3p and accelerates apoptosis in cigarette-inflamed bronchial epithelium by targeting death-associated protein kinase 1

Background

Persistent exposure to cigarette smoke or biomass fuels induces oxidative stress and apoptosis in bronchial epithelium, which is one of the most important pathogenic mechanisms of chronic obstructive pulmonary disease (COPD). Fine particulate matter (PM_2.5) is an aggravating risk factor of COPD exacerbation. Animal evidence showed PM_2.5accelerated lung inflammation and oxidative stress in COPD mice, but the mechanism is still not clear. Recently, we found that miR-194-3p is a novel biomarker of both COPD and PM_2.5 exposure, and miR-194 family has been reported to be involved in cell proliferation and apoptosis. Thus, we propose a hypothesis: PM_2.5 can accelerate apoptotic response of airway epithelial cells in COPD and miR-194 is a potential involved regulator.

Materials and methods

Human bronchial epithelial cells (HBEpiCs) were treated with normal media, cigarette smoke solution (CSS) and PM_2.5-CSS for 24 h. miR-194-3p mimics, inhibitors and scrambled controls were non-transfected or pre-transfected into HBEpiCs for 48 h. MircroRNAs and mRNA expression were quantified by qRT-PCR. Protein expression was analyzed by western blotting. Caspase activities, mitochondrial membrane potential and TUNEL-positive cells were detected to analyze apoptosis. Bioinformatics and luciferase analysis were used to identify the predicted binding site of miR-194-3p and potential targets.

Results

In our study, we found that PM_2.5 significantly aggravated apoptosis in cigarette-inflamed HBEpiCs. miR-194-3p was dramatically downregulated in PM_2.5-CSS-treated HBEpiCs. Bioinformatics and luciferase experiments reported that death-associated protein kinase 1 (DAPK1), regulating caspase 3 activities in apoptosis, was directly targeted by miR-194-3p. Inhibition of miR-194-3p increased DAPK1 expression and apoptosis in normal HBEpiCs. Importantly, overexpression of miR-194-3p suppressed apoptosis in PM_2.5-CSS HBEpiCs.

Conclusion

These results suggested that miR-194-3p was a protective regulator involved in apoptosis pathway and a potential therapeutic target for treatment of bronchial epithelial injury aggravation induced by PM_2.5.