Enhanced levels of prostaglandin E2 and matrix metalloproteinase-2 correlate with the severity of airflow limitation in stable COPD

Assessment of MMP-9 and clinical characteristics in dogs with tracheal collapse based on cough severity and fluoroscopic findings: a cross-sectional study

BACKGROUND

Tracheal collapse (TC), a common disease in dogs, is characterized by cough; however, little is known about the serum biomarkers that can objectively evaluate the severity of cough in canine TC. Furthermore, studies elucidating the relationship of fluoroscopic characteristics with the severity of cough are lacking. Therefore, this study aimed to evaluate the relationship between cough severity and clinical characteristics, fluoroscopic images, and new serum biomarkers in canine TC.

RESULTS

Fifty-one client-owned dogs diagnosed with TC based on fluoroscopic and clinical signs were enrolled in this study and divided into three groups according to the severity of cough (grade of cough: 0, 1, and 2). Signalments, comorbidities, and fluoroscopic characteristics were compared among the groups retrospectively. The serum matrix metalloproteinase-9 (MMP-9), interleukin-6 (IL-6), surfactant protein-A (SP-A), and syndecan-1 (SDC-1) levels were measured in all groups. No significant differences in age, breed, sex, or clinical history were observed among the groups. Concomitant pharyngeal collapse increased significantly with the severity of cough (p = .031). Based on the fluoroscopic characteristics, the TC grade of the carinal region increased significantly and consistently with the grade of cough (p = .03). The serum MMP-9 level was significantly higher in the grade 2 group than that in the grade 0 group (p = .014). The serum IL-6 level was significantly lower in the grade 1 group than that in the grade 0 group (p = .020). The serum SP-A and SDC-1 levels did not differ significantly among the groups.

CONCLUSIONS

The severity of cough with the progression of TC can be predicted with the fluoroscopic TC grade at the carinal region. MMP-9 may be used as an objective serum biomarker that represents cough severity to understand the pathogenesis.

Silica Nanoparticles Shed Light on Intriguing Cellular Pathways in Human Tracheal Smooth Muscle Cells: Revealing COX-2/PGE2 Production through the EGFR/Pyk2 Signaling Axis

The use of manufactured silica nanoparticles (SiNPs) has become widespread in everyday life, household products, and various industrial applications. While the harmful effects of crystalline silica on the lungs, known as silicosis or chronic pulmonary diseases, are well understood, the impact of SiNPs on the airway is not fully explored. This study aimed to investigate the potential effects of SiNPs on human tracheal smooth muscle cells (HTSMCs). Our findings revealed that SiNPs induced the expression of cyclooxygenase-2 (COX-2) mRNA/protein and the production of prostaglandin E2 (PGE2) without causing cytotoxicity. This induction was transcription-dependent, as confirmed by cell viability assays and COX-2 luciferase reporter assays. Further analysis, including Western blot with pharmacological inhibitors and siRNA interference, showed the involvement of receptor tyrosine kinase (RTK) EGF receptor (EGFR), non-RTK Pyk2, protein kinase Cα (PKCα), and p42/p44 MAPK in the induction process. Notably, EGFR activation initiated cellular signaling that led to NF-κB p65 phosphorylation and translocation into the cell nucleus, where it bound and stimulated COX-2 gene transcription. The resulting COX-2 protein triggered PGE2 production and secretion into the extracellular space. Our study demonstrated that SiNPs mediate COX-2 up-regulation and PGE2 secretion in HTSMCs through the sequential activation of the EGFR/Pyk2/PKCα/p42/p44MAPKs-dependent NF-κB signaling pathway. Since PGE2 can have both physiological bronchodilatory and anti-inflammatory effects, as well as pathological pro-inflammatory effects, the increased PGE2 production in the airway might act as a protective compensatory mechanism and/or a contributing factor during airway exposure to SiNPs.

Role of prostanoids, nitric oxide and endothelin pathways in pulmonary hypertension due to COPD

Pulmonary hypertension (PH) due to chronic obstructive pulmonary disease (COPD) is classified as Group 3 PH, with no current proven targeted therapies. Studies suggest that cigarette smoke, the most risk factor for COPD can cause vascular remodelling and eventually PH as a result of dysfunction and proliferation of pulmonary artery smooth muscle cells (PASMCs) and pulmonary artery endothelial cells (PAECs). In addition, hypoxia is a known driver of pulmonary vascular remodelling in COPD, and it is also thought that the presence of hypoxia in patients with COPD may further exaggerate cigarette smoke-induced vascular remodelling; however, the underlying cause is not fully understood. Three main pathways (prostanoids, nitric oxide and endothelin) are currently used as a therapeutic target for the treatment of patients with different groups of PH. However, drugs targeting these three pathways are not approved for patients with COPD-associated PH due to lack of evidence. Thus, this review aims to shed light on the role of impaired prostanoids, nitric oxide and endothelin pathways in cigarette smoke- and hypoxia-induced pulmonary vascular remodelling and also discusses the potential of using these pathways as therapeutic target for patients with PH secondary to COPD.

Attenuation of Cigarette-Smoke-Induced Oxidative Stress, Senescence, and Inflammation by Berberine-Loaded Liquid Crystalline Nanoparticles: In Vitro Study in 16HBE and RAW264.7 Cells

Cigarette smoke is considered a primary risk factor for chronic obstructive pulmonary disease. Numerous toxicants present in cigarette smoke are known to induce oxidative stress and airway inflammation that further exacerbate disease progression. Generally, the broncho-epithelial cells and alveolar macrophages exposed to cigarette smoke release massive amounts of oxidative stress and inflammation mediators. Chronic exposure of cigarette smoke leads to premature senescence of airway epithelial cells. This impairs cellular function and ultimately leads to the progression of chronic lung diseases. Therefore, an ideal therapeutic candidate should prevent disease progression by controlling oxidative stress, inflammation, and senescence during the initial stage of damage. In our study, we explored if berberine (an alkaloid)-loaded liquid crystalline nanoparticles (berberine-LCNs)-based treatment to human broncho-epithelial cells and macrophage inhibits oxidative stress, inflammation, and senescence induced by cigarette-smoke extract. The developed berberine-LCNs were found to have favourable physiochemical parameters, such as high entrapment efficiency and sustained in vitro release. The cellular-assay observations revealed that berberine-LCNs showed potent antioxidant activity by suppressing the generation of reactive oxygen species in both broncho-epithelial cells (16HBE) and macrophages (RAW264.7), and modulating the genes involved in inflammation and oxidative stress. Similarly, in 16HBE cells, berberine-LCNs inhibited the cigarette smoke-induced senescence as revealed by X-gal staining, gene expression of CDKN1A (p21), and immunofluorescent staining of p21. Further in-depth mechanistic investigations into antioxidative, anti-inflammatory, and antisenescence research will diversify the current findings of berberine as a promising therapeutic approach for inflammatory lung diseases caused by cigarette smoking.

Aberrant Post-Transcriptional Regulation of Protein Expression in the Development of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is an incurable and prevalent respiratory disorder that is characterized by chronic inflammation and emphysema. COPD is primarily caused by cigarette smoke (CS). CS alters numerous cellular processes, including the post-transcriptional regulation of mRNAs. The identification of RNA-binding proteins (RBPs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) as main factors engaged in the regulation of RNA biology opens the door to understanding their role in coordinating physiological cellular processes. Dysregulation of post-transcriptional regulation by foreign particles in CS may lead to the development of diseases such as COPD. Here we review current knowledge about post-transcriptional events that may be involved in the pathogenesis of COPD.

Effect of Methylation Status of lncRNA-MALAT1 and MicroRNA-146a on Pulmonary Function and Expression Level of COX2 in Patients With Chronic Obstructive Pulmonary Disease

This study aimed to investigate the role of methylation of MALAT1 and miR-146a in the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD patients were grouped according to their methylation status of MALAT1 and miR-146a promoters, and we found that forced vital capacity, volume that has been exhaled at the end of the first second of forced expiration, and diffusion capacity for carbon monoxide were the highest in the MALAT1 HYPO + miR-146a HYPER group and lowest in the MALAT1 HYPER + miR-146a HYPO group, and COPD patients with hypermethylated MALAT1 showed lower expression of MALAT1 than that in the COPD patients with hypomethylated MALAT1. Meanwhile, miR-146a was the most significantly upregulated in the MALAT1 HYPER + miR-146a HYPO group and the most significantly downregulated in the MALAT1 HYPO + miR-146a HYPER group. Both prostaglandin E₁ and cyclooxygenase 2 (COX2) expression were the highest in the MALAT1 HYPO + miR-146a HYPER group and the lowest in the MALAT1 HYPER + miR-146a HYPO group. In conclusion, our results established a MALAT1/miR-146a/COX2 signaling axis. The overexpression of MALAT1 could increase the expression of COX2 by inhibiting the expression of miR-146a, thus affecting the pulmonary function of COPD patients.

Smoking induces sex-specific changes in the small airway proteome

Introduction

Cigarette smoke triggers many cellular and signaling responses in the lung and the resulting inflammation plays a central role in smoke-related lung diseases, such as COPD. We explored the effects of smoking on the small airway proteome in samples obtained by collection of exhaled particles with the aim to identify specific proteins dysregulated by smoking.

Methods

Exhaled particles were obtained from 38 current smokers, 47 former smokers and 22 healthy controls with the PExA method. 120 ng of sample was collected from individual subjects and analyzed with the SOMAscan proteomics platform. General linear model-based statistics were performed.

Results

Two hundred and three proteins were detected in at least half of 107 total samples. Active smoking exerted a significant impact on the protein composition of respiratory tract lining fluid (RTLF), with 81 proteins altered in current smokers compared to never smokers (p < 0.05, q < 0.124). Among the proteins most clearly discriminating between current and never smokers were sRAGE, FSTL3, SPOCK2 and protein S, all of them being less abundant in current smokers. Analysis stratified for sex unveiled sex differences with more pronounced proteomic alterations due to active smoking in females than males. Proteins whose abundance was altered by active smoking in women were to a larger extent related to the complement system. The small airway protein profile of former smokers appeared to be more similar to that observed in never smokers.

Conclusions

The study shows that smoking has a strong impact on protein expression in the small airways, and that smoking affects men and women differently, suggesting PExA sampling combined with high sensitivity protein analysis offers a promising platform for early detection of COPD and identification of novel COPD drug targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01825-6.

Role of Farnesoid X Receptor in the Pathogenesis of Respiratory Diseases

Farnesoid X receptor (FXR) is a bile acid receptor encoded by the Nr1h4 gene. FXR plays an important role in maintaining the stability of the internal environment and the integrity of many organs, including the liver and intestines. The expression of FXR in nondigestible tissues other than in the liver and small intestine is known as the expression of “nonclassical” bile acid target organs, such as blood vessels and lungs. In recent years, several studies have shown that FXR is widely involved in the pathogenesis of various respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, and idiopathic pulmonary fibrosis. Moreover, a number of works have confirmed that FXR can regulate the bile acid metabolism in the body and exert its anti-inflammatory and antifibrotic effects in the airways and lungs. In addition, FXR may be used as a potential therapeutic target for some respiratory diseases. For example, FXR can regulate the tumor microenvironment by regulating the balance of inflammatory and immune responses in the body to promote the occurrence and development of non-small-cell lung cancer (NSCLC), thereby being considered a potential target for immunotherapy of NSCLC. In this article, we provide an overview of the internal relationship between FXR and respiratory diseases to track the progress that has been achieved thus far in this direction and suggest potential therapeutic prospects of FXR in respiratory diseases.

An ex vivo skin model to probe modulation of local cutaneous arachidonic acid inflammation pathway

There is a need for inexpensive and reliable means to determine the modulation of cutaneous inflammation. The method outlined in this article draws together a number of scientific techniques and makes use of generally unwanted biological tissues as a means of determining skin inflammation ex vivo, and focuses on probing aspects of the arachidonic acid inflammation pathway. Freshly excised skin contains elevated levels of short-lived inducible cyclooxygenase-2 (COX-2) and, under viable conditions, COX-2 and its eicosanoid products will continue to be produced until tissue necrosis, providing a window of time in which relative levels can be probed to determine exacerbation due to an upregulating factor or downregulation due the presence of an agent exerting anti-inflammatory activity. Ex vivo porcine skin, mounted in Franz diffusion cells, is dosed topically with the xenobiotic challenge and then techniques such as Western blotting and immunohistochemistry can then be used to probe relative COX-2 levels on a semi-quantitative or qualitative level. Enzyme-linked immunosorbent assay or LCMS can be used to determine relative prostaglandin E-2 (PGE-2) levels. Thus far, the technique has been used to examine the effects of topically applied anti-inflammatories (betamethasone, ibuprofen, ketoprofen and methotrexate), natural products (fish oil, Devil’s claw extract and pomegranate rind extract) and drug delivery vehicle (polyNIPAM nanogels). Topically applied xenobiotics that modulate factors such as COX-2 and PGE-2 must penetrate the intact skin, and this provides direct evidence of overcoming the "barrier function" of the stratum corneum in order to target the viable epidermis in sufficient levels to be able to elicit such effects. This system has particular potential as a pre-clinical screening tool for those working on the development of topical delivery systems, and has the additional advantage of being in line with 3 Rs philosophy.

A SNP of miR-146a is involved in bladder cancer relapse by affecting the function of bladder cancer stem cells via the miR-146a signallings

MiR‐146a‐5p in urine samples was recently reported to be possibly used as a prognostic marker for bladder cancer (BC). Interestingly, YAP1 and COX2 were both demonstrated to function as stem cell regulators in BC. Therefore, in this study, we aimed to establish the molecular mechanism underlying the role of miR‐146a, YAP1 and COX2 in BC relapse. We also studied the possibility of using the C > G genotype of miR‐146a rs2910164 SNP as an indicator of BC relapse. A total of 170 BC patients were assigned into different groups based on their genotypes of rs2910164 SNP. Kaplan‐Meier survival curves were plotted to compare the recurrence‐free rate among these groups. Real‐time PCR, Western Blot, bioinformatic analysis, luciferase assay and IHC assay were conducted to study the role of rs2910164 SNP in the progression of BC. Accordingly, GC/CC‐genotyped patients presented a higher risk of recurrence when compared with GG‐genotyped patients, while the expression of BC regulators was influenced by the presence of rs2910164. COX2 mRNA and YAP1 mRNA were, respectively, validated as direct target genes of miR‐146a, and the expression of YAP1 and COX2 mRNA/protein was both suppressed by miR‐146a precursors. The expression of ALDH1A1 mRNA/protein was inhibited upon the down‐regulation of YAP1, while the expression of let7 and SOX2 mRNA/protein was inhibited upon the down‐regulation of COX2. In conclusion, two signalling pathways, miR‐146a/YAP1/ALDH1A1 and miR‐146a/COX2/PGE2/let7/SOX2, were modulated by miR‐146a. As an SNP regulating the expression of miR‐146a, the rs2910164 G > C SNP could be utilized as a biomarker for BC relapse.

Aberrant subchondral osteoblastic metabolism modifies NaV1.8 for osteoarthritis

Pain is the most prominent symptom of osteoarthritis (OA) progression. However, the relationship between pain and OA progression remains largely unknown. Here we report osteoblast secret prostaglandin E2 (PGE2) during aberrant subchondral bone remodeling induces pain and OA progression in mice. Specific deletion of the major PGE2 producing enzyme cyclooxygenase 2 (COX2) in osteoblasts or PGE2 receptor EP4 in peripheral nerve markedly ameliorates OA symptoms. Mechanistically, PGE2 sensitizes dorsal root ganglia (DRG) neurons by modifying the voltage-gated sodium channel Na_V1.8, evidenced by that genetically or pharmacologically inhibiting Na_V1.8 in DRG neurons can substantially attenuate OA. Moreover, drugs targeting aberrant subchondral bone remodeling also attenuates OA through rebalancing PGE2 production and Na_V1.8 modification. Thus, aberrant subchondral remodeling induced Na_V1.8 neuronal modification is an important player in OA and is a potential therapeutic target in multiple skeletal degenerative diseases.

Many people will suffer from joint pain as they age, particularly in their knees. The most common cause of this pain is osteoarthritis, a disease that affects a tissue inside joints called cartilage. In a healthy knee, cartilage acts as a shock absorber. It cushions the ends of bones and enables them to move smoothly against one another. But in osteoarthritis, cartilage gradually wears away. As a result, the bones within a joint rub against each other whenever a person moves. This makes activities such as running or climbing stairs painful.

But how does this pain arise? Previous work has implicated cells called osteoblasts. Osteoblasts are found in the area of the bone just below the cartilage. They produce new bone tissue throughout our lives, enabling our bones to regenerate and repair. Each time we move, forces acting on the knee joint activate osteoblasts. The cells respond by releasing a key molecule called PGE2, which is a factor in pain pathways. The joints of people with osteoarthritis produce too much PGE2. But exactly how this leads to increased pain sensation has been unclear.

Zhu et al. now complete this story by working out how PGE2 triggers pain. Experiments in mice reveal that PGE2 irritates the nerve fibers that carry pain signals from the knee joint to the brain. It does this by activating a channel protein called Na_v1.8, which allows sodium ions through the membranes of those nerve fibers. Zhu et al. show that, in a mouse model of osteoarthritis, Na_v1.8 opens too widely in response to binding of PGE2, so the nerve cells become overactive and transmit a stronger pain sensation. This means that even small movements cause intense pain signals to travel from the joints to the brain.

Building on their findings, Zhu et al. developed a drug that acts directly on bone to reduce PGE2 production, and show that this drug reduces pain in mice with osteoarthritis. At present, there are no treatments that reverse the damage that occurs during osteoarthritis, but further testing will determine whether this new drug could one day relieve joint pain in patients.

Chronic E-Cigarette Use Increases Neutrophil Elastase and Matrix Metalloprotease Levels in the Lung

Rationale: Proteolysis is a key aspect of the lung's innate immune system. Proteases, including neutrophil elastase and MMPs (matrix metalloproteases), modulate cell signaling, inflammation, tissue remodeling, and leukocyte recruitment via cleavage of their target proteins. Excessive proteolysis occurs with chronic tobacco use and is causative for bronchiectasis and emphysema. The effect of e-cigarettes (vaping) on proteolysis is unknown.

Objectives: We used protease levels as biomarkers of harm to determine the impact of vaping on the lung.

Methods: We performed research bronchoscopies on healthy nonsmokers, cigarette smokers, and e-cigarette users (vapers), and determined protease levels in BAL. In parallel, we studied the effects of e-cigarette components on protease secretion in isolated human blood neutrophils and BAL-derived macrophages. We also analyzed the nicotine concentration in induced sputum and BAL.

Measurements and Main Results: Neutrophil elastase, MMP-2, and MMP-9 activities and protein levels were equally elevated in both vapers' and smokers' BAL relative to nonsmokers. In contrast, antiprotease levels were unchanged. We also found that exposure of isolated neutrophils and macrophages to nicotine elicited dose-dependent increases in protease release. After vaping, measurable levels of nicotine were detectable in sputum and BAL, which corresponded to the half-maximal effective concentration values for protease release seen in immune cells.

Conclusions: We conclude that vaping induces nicotine-dependent protease release from resident pulmonary immune cells. Thus, chronic vaping disrupts the protease-antiprotease balance by increasing proteolysis in lung, which may place vapers at risk of developing chronic lung disease. These data indicate that vaping may not be safer than tobacco smoking.

Chronic Obstructive Pulmonary Disease and Lung Cancer: Underlying Pathophysiology and New Therapeutic Modalities

Chronic obstructive pulmonary disease (COPD) and lung cancer are major lung diseases affecting millions worldwide. Both diseases have links to cigarette smoking and exert a considerable societal burden. People suffering from COPD are at higher risk of developing lung cancer than those without, and are more susceptible to poor outcomes after diagnosis and treatment. Lung cancer and COPD are closely associated, possibly sharing common traits such as an underlying genetic predisposition, epithelial and endothelial cell plasticity, dysfunctional inflammatory mechanisms including the deposition of excessive extracellular matrix, angiogenesis, susceptibility to DNA damage and cellular mutagenesis. In fact, COPD could be the driving factor for lung cancer, providing a conducive environment that propagates its evolution. In the early stages of smoking, body defences provide a combative immune/oxidative response and DNA repair mechanisms are likely to subdue these changes to a certain extent; however, in patients with COPD with lung cancer the consequences could be devastating, potentially contributing to slower postoperative recovery after lung resection and increased resistance to radiotherapy and chemotherapy. Vital to the development of new-targeted therapies is an in-depth understanding of various molecular mechanisms that are associated with both pathologies. In this comprehensive review, we provide a detailed overview of possible underlying factors that link COPD and lung cancer, and current therapeutic advances from both human and preclinical animal models that can effectively mitigate this unholy relationship.

An Updated Overview of Metabolomic Profile Changes in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), a common and heterogeneous respiratory disease, is characterized by persistent and incompletely reversible airflow limitation. Metabolomics is applied to analyze the difference of metabolic profile based on the low-molecular-weight metabolites (<1 kDa). Emerging metabolomic analysis may provide insights into the pathogenesis and diagnosis of COPD. This review aims to summarize the alteration of metabolites in blood/serum/plasma, urine, exhaled breath condensate, lung tissue samples, etc. from COPD individuals, thereby uncovering the potential pathogenesis of COPD according to the perturbed metabolic pathways. Metabolomic researches have indicated that the dysfunctions of amino acid metabolism, lipid metabolism, energy production pathways, and the imbalance of oxidations and antioxidations might lead to local and systematic inflammation by activating the Nuclear factor kappa-light-chain-enhancer of activated B cells signaling pathway and releasing inflammatory cytokines, like interleutin-6 (IL-6), tumor necrosis factor-α, and IL-8. In addition, they might cause protein malnutrition and oxidative stress and contribute to the development and exacerbation of COPD.

Lipid metabolism in chronic obstructive pulmonary disease

Dysregulated lipid metabolism plays crucial roles in various diseases, including diabetes mellitus, cancer, and neurodegeneration. Recent studies suggest that alterations in major lipid metabolic pathways contribute to pathogenesis of lung diseases, including chronic obstructive pulmonary disease (COPD). These changes allow lung tissue to meet the energy needs and trigger anabolic pathways that initiate the synthesis of active molecules directly involved in the inflammation. In this review, we summarize the changes of catabolism and anabolism of lipids, lipid molecules including lipid mediators, lipid synthesis transcription factors, cholesterol, and phospholipids, and how those lipid molecules participate in the initiation and resolution of inflammation in COPD.

The COX-2/prostanoid signaling cascades in seizure disorders

Introduction：A robust neuroinflammatory response is a prevalent feature of multiple neurological disorders, including epilepsy and acute status epilepticus. One component of this neuroinflammatory reaction is the induction of cyclooxygenase-2 (COX-2), synthesis of several prostaglandins and endocannabinoid metabolites, and subsequent activation of prostaglandin and related receptors. Neuroinflammation mediated by COX-2 and its downstream effectors has received considerable attention as a potential target class to ameliorate the deleterious consequences of neurological injury. Areas covered: Here we describe the roles of COX-2 as a major inflammatory mediator. In addition, we discuss the receptors for prostanoids PGE₂, prostaglandin D2, and PGF_2α as potential therapeutic targets for inflammation-driven diseases. The consequences of prostanoid receptor activation after seizure activity are discussed with an emphasis on the utilization of small molecules to modulate prostanoid receptor activity. Expert opinion: Limited clinical trial experience is supportive but not definitive for a role of the COX signaling cascade in epileptogenesis. The cardiotoxicity associated with chronic coxib use, and the expectation that COX-2 inhibition will influence the levels of endocannabinoids, leukotrienes, and lipoxins as well as the prostaglandins and their endocannabinoid metabolite analogs, is shifting attention toward downstream synthases and receptors that mediate inflammation in the brain.

Combined Effects of PVT1 and MiR-146a Single Nucleotide Polymorphism on the Lung Function of Smokers with Chronic Obstructive Pulmonary Disease

Non-coding RNAs play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study was performed to investigate the role of PVT1 and miR-146a single nucleotide polymorphisms (SNPs) in the lung function of COPD smokers. Real-time PCR and Western blot analyses were performed to measure the expression of miR-146 and PVT1 SNPs and determine the effect of these SNPs on the pathogenesis of COPD. A total of 100 COPD smokers were enrolled in this study and divided into four groups as follows: Rs2910164CC/GC + Rs13281615GG; Rs2910164CC/GC + Rs13281615GA/AA; Rs2910164GG + Rs13281615GG; and Rs2910164GG + Rs13281615GA/AA. No obvious differences in terms of age, sex, and body height and weight were found among the four groups. However, the Rs2910164GG + Rs13281615GA/AA was associated with the highest stage of the Global Initiative for Chronic Obstructive Lung Disease and the highest values of the forced vital capacity, forced expiratory volume, and diffusing capacity of carbon monoxide, while the lowest values of these parameters were observed in the Rs2910164CC/GC + Rs13281615GG group. In addition, the highest and lowest COX2 levels were observed in the Rs2910164GG + Rs13281615GA/AA and Rs2910164CC/GC + Rs13281615GG groups, respectively. PVT1 directly and negatively regulated the miR-146a expression, which in turn directly and negatively regulated COX2 expression. Thus, the combined actions of SNP in PVT1 Rs13281615 and miR-146a Rs2910164 affected the lung function in COPD smokers.

Reduced microRNA-503 expression augments lung fibroblast VEGF production in chronic obstructive pulmonary disease

Alterations in microRNA (miRNA) expression may contribute to COPD pathogenesis. In COPD, lung fibroblast repair functions are altered in multiple ways, including extracellular mediator release. Our prior study revealed miR-503 expression is decreased in COPD lung fibroblasts, although the exact role played by miR-503 is undetermined. The current study examined a role of miR-503 in cytokine, growth factor and fibronectin production by lung fibroblasts from patients with and without COPD. Primary adult lung fibroblasts were isolated from patients with or without COPD. MiR-503 expression and interleukin (IL)-6, -8, PGE2, HGF, KGF, VEGF and fibronectin release were examined with or without inflammatory cytokines, IL-1β and tumor necrosis factor (TNF)-α. MiR-503 expression was decreased in COPD lung fibroblasts. The expression of miR-503 was positively correlated with %FVC, %FEV1, and %DLco as well as IL-6, -8, PGE2, HGF, KGF, and VEGF in the absence or presence of IL-1ß/TNF-α. In addition, IL-8 and VEGF release from COPD lung fibroblasts were increased compared to those from control. Exogenous miR-503 inhibited VEGF release from primary adult and fetal lung fibroblasts but not IL-8 release. As expected, COPD fibroblasts proliferated more slowly than control fibroblasts. MiR-503 did not affect proliferation of either control or COPD lung fibroblasts. MiR-503 inhibition of VEGF protein production and mRNA was mediated by direct binding to the 3' untranslated region of VEGF mRNA. Endogenous miR-503 was differently regulated by exogenous stimulants associated with COPD pathogenesis, including IL-1ß/TNF-α, TGF-ß1 and PGE2. Endogenous miR-503 inhibition augmented VEGF release by IL-1ß/TNF-α and TGF-ß1 but not by PGE2, demonstrating selectivity of miR-503 regulation of VEGF. In conclusions, reduced miR-503 augments VEGF release from lung fibroblasts from patients with COPD. Since VEGF contributes to disturbed vasculature in COPD, altered miR-503 production might play a role in modulating fibroblast-mediated vascular homeostasis in COPD.

Neurophenotypes in Airway Diseases. Insights from Translational Cough Studies

RATIONALE

Most airway diseases, including chronic obstructive pulmonary disease (COPD), are associated with excessive coughing. The extent to which this may be a consequence of increased activation of vagal afferents by pathology in the airways (e.g., inflammatory mediators, excessive mucus) or an altered neuronal phenotype is unknown. Understanding whether respiratory diseases are associated with dysfunction of airway sensory nerves has the potential to identify novel therapeutic targets.

OBJECTIVES

To assess the changes in cough responses to a range of inhaled irritants in COPD and model these in animals to investigate the underlying mechanisms.

METHODS

Cough responses to inhaled stimuli in patients with COPD, healthy smokers, refractory chronic cough, asthma, and healthy volunteers were assessed and compared with vagus/airway nerve and cough responses in a cigarette smoke (CS) exposure guinea pig model.

MEASUREMENTS AND MAIN RESULTS

Patients with COPD had heightened cough responses to capsaicin but reduced responses to prostaglandin E2 compared with healthy volunteers. Furthermore, the different patient groups all exhibited different patterns of modulation of cough responses. Consistent with these findings, capsaicin caused a greater number of coughs in CS-exposed guinea pigs than in control animals; similar increased responses were observed in ex vivo vagus nerve and neuron cell bodies in the vagal ganglia. However, responses to prostaglandin E2 were decreased by CS exposure.

CONCLUSIONS

CS exposure is capable of inducing responses consistent with phenotypic switching in airway sensory nerves comparable with the cough responses observed in patients with COPD. Moreover, the differing profiles of cough responses support the concept of disease-specific neurophenotypes in airway disease. Clinical trial registered with www.clinicaltrials.gov (NCT 01297790).

Intratracheal transplantation of endothelial progenitor cells attenuates smoking-induced COPD in mice

Background

Endothelial progenitor cells (EPCs) might play a protective role in COPD. The aim of this study was to investigate whether intratracheal allogeneic transplantation of bone-marrow-derived EPCs would attenuate the development of smoking-induced COPD in mice.

Methods

Isolated mononuclear cells from the bone marrow of C57BL/6J mice were cultured in endothelial cell growth medium-2 for 10 days, yielding EPCs. A murine model of COPD was established by passive 90-day exposure of cigarette smoke. On day 30, EPCs or phosphate-buffered saline alone was administered into the trachea. On day 90, EPCs or 30 μL phosphate-buffered saline alone was administered into the trachea, and on day 120, inflammatory cells, antioxidant activity, apoptosis, matrix metalloproteinase (MMP)-2, and MMP-9 were measured.

Results

After EPC treatment, the lung function of the mice had improved compared with the untreated mice. Mean linear intercept and destructive index were reduced in the EPCs-treated group compared with the untreated group. In addition, the EPCs-treated mice exhibited less antioxidant activity in bronchoalveolar lavage fluid compared with the untreated mice. Moreover, decreased activities of MMP-2, MMP-9, and TUNEL-positive cells in lung tissues were detected in EPCs-treated mice.

Conclusion

Intratracheal transplantation of EPCs attenuated the development of pulmonary emphysema and lung function disorder probably by alleviating inflammatory infiltration, decelerating apoptosis, inhibiting proteolytic enzyme activity, and improving antioxidant activity.

The role of cyclooxygenase-2 in the protection against apoptosis in vascular endothelial cells induced by cigarette smoking

BACKGROUND

Apoptosis has been demonstrated to be an important upstream event in the pathogenesis of chronic obstructive pulmonary disease (COPD). Cyclooxygenase-2 (COX-2) seems to be biologically relevant in COPD. However, the role of COX-2 in the apoptosis in vascular endothelial cells induced by cigarette smoke extract (CSE) remains to be elucidated. Our recent study found that the prostacyclin, one of the COX products in the microvascular endothelium, inhibited apoptosis in the emphysematous lungs of rats induced by CSE. In order to clarify the role of COX-2 in the apoptosis of vascular endothelial cells induced by CSE, we performed the present experiment to elucidate it.

METHODS

Twenty surgical lung specimens were obtained from 6 patients with COPD, 7 smoking controls and seven nonsmoking controls. The apoptotic index (AI) and COX-2 protein expression were detected in lung tissues. To further investigate the effects of CSE on the apoptosis and COX-2 expression in a human vascular endothelial cell line, the apoptosis rate and COX-2 expression were examined in human umbilical vein endothelial cells (ECV304) under exposure to varied concentrations of CSE as well as under exposure to 5.0% CSE for varied durations. Repeatedly, the apoptosis rate and COX-2 expression in ECV304 cells under 5.0% CSE were examined after exposing to varied concentrations of celecoxib, a highly selective COX-2 inhibitor.

RESULTS

Significantly increased AI and expression of COX-2 were found both in the lungs of patients with COPD and smoking controls compared with nonsmoking controls. The CSE induced apoptosis in ECV304 cells in means of both dose-dependent and time-dependent manners. The COX-2 was slightly expressed in the cells after exposing to 5% CSE for 3 and 6 h, and markedly expressed after the exposure time for 9 and 12 h, but vanished after 24 h of the exposure. Of interest, with the completely block of the COX-2 expression by celecoxib at 50.0 µmol/L, the apoptosis rate was markedly increased again in ECV304 cells under exposure to 5.0% CSE.

CONCLUSIONS

Endothelial cell apoptosis and the expression of COX-2 protein were increased in both COPD patients and CSE-induced vascular endothelial cells. Of interest, it seems that the COX-2 probably had a protective role against the apoptosis in the vascular endothelial cells induced by cigarette smoking.

Overexpression of farnesoid X receptor in small airways contributes to epithelial to mesenchymal transition and COX-2 expression in chronic obstructive pulmonary disease

BACKGROUND

Epithelial-mesenchymal transition (EMT) and cyclooxygenase-2 (COX-2) contribute to airway remodelling and inflammation in chronic obstructive pulmonary disease (COPD). Recent data suggest that the farnesoid X receptor (FXR), a nuclear receptor traditionally considered as bile acid-activated receptor, is also expressed in non-classical bile acids target tissues with novel functions beyond regulating bile acid homeostasis. This study aimed to investigate the potential role of FXR in the development of COPD, as well as factors that affect FXR expression.

METHODS

Expression of FXR, EMT biomarkers and COX-2 was examined by immunohistochemistry in lung tissues from non-smokers, smokers, and smokers with COPD. The role of FXR in TGF-β1-induced EMT and COX-2 expression in human bronchial epithelial (HBE) cells was evaluated in vitro. Factors regulating FXR expression were assessed in cultured HBE cells and a cigarette smoke-induced rat model of COPD.

RESULTS

Expression of FXR, EMT markers and COX-2 was significantly elevated in small airway epithelium of COPD patients compared with controls. The staining scores of FXR in small airway epithelium were negatively related with FEV₁% of predicted of smokers without and with COPD. FXR agonist GW4064 remarkably enhanced and FXR antagonist Z-Guggulsterone significantly inhibited EMT changes in TGF-β1-treated HBE cells. Both chenodeoxycholic acid (CDCA) and GW4064 increased COX-2 expression in HBE cells, whereas Z-Guggulsterone dramatically restrained CDCA-induced COX-2 expression. Finally, FXR expression is induced by IL-4 and IL-13 in HBE cells, as well as by cigarette smoke exposure in a rat model of COPD.

CONCLUSIONS

Overexpression of FXR in small airway may contribute to airway remodelling and inflammation in COPD by regulating EMT and COX-2 expression.

Role of EP2 and EP4 receptors in airway microvascular leak induced by prostaglandin E2

BACKGROUND AND PURPOSE

Airway microvascular leak (MVL) involves the extravasation of proteins from post-capillary venules into surrounding tissue. MVL is a cardinal sign of inflammation and an important feature of airway inflammatory diseases such as asthma. PGE2, a product of COX-mediated metabolism of arachidonic acid, binds to four receptors, termed EP1–4. PGE2 has a wide variety of effects within the airway, including modulation of inflammation, sensory nerve activation and airway tone. However, the effect of PGE2 on airway MVL and the receptor/s that mediate this have not been described.

EXPERIMENTAL APPROACH

Evans Blue dye was used as a marker of airway MVL, and selective EP receptor agonists and antagonists were used alongside EP receptor-deficient mice to define the receptor subtype involved.

KEY RESULTS

PGE2 induced significant airway MVL in mice and guinea pigs. A significant reduction in PGE2-induced MVL was demonstrated in Ptger2−/− and Ptger4−/− mice and in wild-type mice pretreated simultaneously with EP2 (PF-04418948) and EP4 (ER-819762) receptor antagonists. In a model of allergic asthma, an increase in airway levels of PGE2 was associated with a rise in MVL; this change was absent in Ptger2−/− and Ptger4−/− mice.

CONCLUSIONS AND IMPLICATIONS

PGE2 is a key mediator produced by the lung and has widespread effects according to the EP receptor activated. Airway MVL represents a response to injury and under ‘disease’ conditions is a prominent feature of airway inflammation. The data presented highlight a key role for EP2 and EP4 receptors in MVL induced by PGE2.

Prostanoids in Asthma and COPD: Actions, Dysregulation, and Therapeutic Opportunities

Pathophysiologic gaps in the actions of currently available treatments for asthma and COPD include neutrophilic inflammation, airway remodeling, and alveolar destruction. All of these processes can be modulated by cyclic adenosine monophosphate-elevating prostaglandins E2 and I2 (also known as prostacyclin). These prostanoids have long been known to elicit bronchodilation and to protect against bronchoconstriction provoked by a variety of stimuli. Much less well known is their capacity to inhibit inflammatory responses involving activation of lymphocytes, eosinophils, and neutrophils, as well as to attenuate epithelial injury and mesenchymal cell activation. This profile of actions identifies prostanoids as attractive candidates for exogenous administration in asthma. By contrast, excessive prostanoid production and signaling might contribute to both the increased susceptibility to infections that drive COPD exacerbations and the inadequate alveolar repair that characterizes emphysema. Inhibition of endogenous prostanoid synthesis or signaling, thus, has therapeutic potential for these types of patients. By virtue of their pleiotropic capacity to modulate numerous pathophysiologic processes relevant to the expression and natural history of airway diseases, prostanoids emerge as attractive targets for therapeutic manipulation.

Factors Associated with Multiple Biomarkers of Systemic Inflammation

BACKGROUND

While much is known about correlates of C-reactive protein (CRP), little is known about correlates of other inflammation biomarkers. As these measures are increasingly being used in epidemiologic studies, it is important to determine what factors affect inflammation biomarker concentrations.

METHODS

Using age, sex, and body mass index (BMI) adjusted linear regression, we examined 38 exposures (demographic and anthropometric measures, chronic disease history, NSAIDs, dietary factors, and supplement use) of 8 inflammation biomarkers [CRP, IL1β, IL6, IL8, TNFα, and soluble TNF receptors (sTNFR) in plasma; and prostaglandin E2 metabolite (PGE-M) in urine] in 217 adults, ages 50 to 76 years.

RESULTS

Increasing age was associated with higher concentrations of all biomarkers except IL1β. BMI was positively associated with CRP and sTNFR I and II. Saturated fat intake was associated with increased CRP, sTNFRII, TNFα, and IL1β, whereas eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) intake (diet or total) was associated with decreased CRP, TNFα, and IL1β. Results for sex were varied: CRP and IL6 were lower among men, whereas PGE-M and sTNFRI were higher. Higher CRP was also associated with smoking, hormone replacement therapy use, and γ-tocopherol intake; lower CRP with physical activity, and intakes of dietary vitamin C and total fiber.

CONCLUSIONS

Although the associations varied by biomarker, the factors having the greatest number of significant associations (P ≤ 0.05) with the inflammation biomarkers were age, BMI, dietary saturated fat, and EPA+DHA omega-3 fatty acids.

IMPACT

Our results suggest that potential confounders in epidemiologic studies assessing associations with inflammation biomarkers vary across specific biomarkers.

Combinations of indole-3-carbinol and silibinin suppress inflammation-driven mouse lung tumorigenesis by modulating critical cell cycle regulators

Chronic inflammation is an important risk factor for lung cancer. Therefore, identification of chemopreventive agents that suppress inflammation-driven lung cancer is indispensable. We studied the efficacy of combinations of indole-3-carbinol (I3C) and silibinin (Sil), 20 µmol/g diet each, against mouse lung tumors induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and driven by lipopolysaccharide (LPS), a potent inflammatory agent and constituent of tobacco smoke. Mice treated with NNK + LPS developed 14.7±4.1 lung tumors/mouse, whereas mice treated with NNK + LPS and given combinations of I3C and Sil had 7.1±4.5 lung tumors/mouse, corresponding to a significant reduction of 52%. Moreover, the number of largest tumors (>1.0mm) was significantly reduced from 6.3±2.9 lung tumors/mouse in the control group to 1.0±1.3 and 1.6±1.8 lung tumors/mouse in mice given I3C + Sil and I3C alone, respectively. These results were paralleled by significant reductions in the level of proinflammatory and procarcinogenic proteins (pSTAT3, pIκBα and COX-2) and proteins that regulate cell proliferation (pAkt, cyclin D1, CDKs 2, 4, 6 and pRB). Further studies in premalignant bronchial cells showed that the antiproliferative effects of I3C + Sil were higher than the individual compounds and these effects were mediated by targeting cyclin D1, CDKs 2, 4 and 6 and pRB. I3C + Sil suppressed cyclin D1 by reducing its messenger RNA level and by enhancing its proteasomal degradation. Our results showed the potential lung cancer chemopreventive effects of I3C + Sil in smokers/former smokers with chronic pulmonary inflammatory conditions.

Effect of a single nucleotide polymorphism in miR-146a on COX-2 protein expression and lung function in smokers with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the effect of a single nucleotide polymorphism (rs2910164) in the miR-146a precursor on the expression level of miR-146a, cyclooxygenase-2 (COX2), and production of prostaglandin E2 (PGE2) in lung tissue harvested from smokers with chronic obstructive pulmonary disease, as well as the lung function and disease stages from the same patient population.

METHODS AND RESULTS

One-hundred and sixty-eight smokers with diagnosed chronic obstructive pulmonary disease were recruited. The patients were genotyped for rs2910164 polymorphism using Sanger sequencing, and their lung function/disease stages were evaluated following Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria. Meanwhile, messenger ribonucleic acid and protein expression levels of miR-146a and COX2 as well as PGE2 production were determined in 66 lung tissue samples collected in the patients who received surgical treatment. We confirmed that COX2 is a validated target of miR-146a in human fibroblast cells, and identified the differential expression patterns of miR-146a and COX2 in each rs2910164 genotype group. We observed a significant association between rs2910164 in miR-146a and the levels of either COX2 or PGE2 using real-time polymerase chain reaction and Western blot. Consistently, we were able to demonstrate that the rs2910164 single nucleotide polymorphism has a functional effect on the baseline lung function in the study population.

CONCLUSION

In the present study, the rs2910164 CC and GC genotype was found to be associated with an improved lung function and milder disease stages, at least partially, mediated by its ability to increase in COX2 expression and PGE2 production.

Effect of culture conditions on microRNA expression in primary adult control and COPD lung fibroblasts in vitro

In vitro cell cultures, including lung fibroblasts, have been used to identify microRNAs (miRNAs) associated with chronic obstructive pulmonary disease (COPD) pathogenesis. However, culture conditions may affect miRNA expression. We examined whether miRNA expression in primary adult lung fibroblasts varies with cell density or passage in vitro and whether culture conditions confound the identification of altered miRNA expression in COPD lung fibroblasts. Primary adult control and COPD lung fibroblasts were cultured until passage 3 or 8, after which cells were further cultured for 3 or 7 d (low vs. high density). Then, cells at low density were cultured with serum-free media, and those at high density were cultured with serum-free media in the absence or presence of interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) for 24 h. RNA was extracted to perform miRNA microarray from which 1.25-fold differential expression and 10% false discovery rate were applied to identify "invariant" and "variant" miRNA for the various culture conditions. Of the 2226 miRNAs evaluated, 39.0% for cell density, 40.7% for cell passage, and 29.4% for both conditions were identified as "invariant" miRNAs. Furthermore, 38.1% of the evaluated miRNAs were "invariant" for cell passage with IL-1β and TNF-α. Differentially expressed miRNAs between control and COPD lung fibroblasts were identified with and without IL-1β and TNF-α, and of these, 32 out of the 34 top-ranked miRNAs exceeded the differences due to culture conditions. Thus, culture conditions may affect miRNA expression of adult human lung fibroblasts. Nevertheless, in vitro cultures can be used to assess differential miRNA expression in COPD lung fibroblasts.

Relationships of COX2 and MMP12 genetic polymorphisms with chronic obstructive pulmonary disease risk: a meta-analysis

We performed the present meta-analysis in an attempt to confirm the correlation of genetic polymorphisms in the COX2 and MMP12 genes with the susceptibility to chronic obstructive pulmonary disease (COPD). We searched English database such as PubMed, CISCOM, CINAHL, Web of Science, Google Scholar and several Chinese database for meta-analysis. There were no specific language restrictions. Two investigators systematically extracted relevant data within those included studies. Crude ORs with its corresponding 95 % CI were calculated. STATA 12.0 software was adopted for statistical analysis. The impact of COX2 and MMP12 genetic polymorphisms on the pathogenesis of COPD was investigated in the current study with a total of 10 case-control studies, which includes 1,751 COPD patients and 2,472 healthy subjects. Four common polymorphisms, including rs689466 G > A and rs20417 G > C in the COX2 gene, rs652438 A > G and rs2276109 A > G were evaluated in the MMP12 gene. Pooled OR of the present studies and results showed that the frequency of COX2 rs20417 polymorphism was prevalent in COPD patients than those of healthy subjects (C allele vs. G allele OR = 1.33, 95 % CI 1.06-1.67, P = 0.014; GC + CC vs. GG OR = 1.86, 95 % CI 1.07-3.24, P = 0.029; respectively). However, we found no significant correlation between COX2 rs689466 polymorphism and the risk of COPD (all P > 0.05). Furthermore, our meta-analysis illustrated that individuals with MMP12 rs652438 polymorphism had significantly increased risk of developing COPD (G allele vs. A allele OR = 1.62, 95 % CI 1.08-2.42, P = 0.020; AG + GG vs. AA OR = 2.14, 95 % CI 1.12-4.09, P = 0.021; respectively). Nevertheless, no positive relation was detected between MMP12 rs2276109 variant and the risk of COPD. Our meta-analysis indicates that COX2 and MMP12 genetic polymorphisms may be strongly implicated in the development of COPD, especially for the COX2 rs20417 and MMP12 rs652438 polymorphisms. Thus, COX2 and MMP12 genetic polymorphisms could potentially be utilized as helpful biomarkers for early diagnosis of COPD.

Upregulation of gelatinases and epithelial-mesenchymal transition in small airway remodeling associated with chronic exposure to wood smoke

BACKGROUND

Peribronchiolar fibrosis is an important feature of small airway remodeling (SAR) in cigarette smoke-induced COPD. The aim of this study was to investigate the role of gelatinases (MMP9, MMP2) and epithelial-mesenchymal transition (EMT) in SAR related to wood smoke (WS) exposure in a rat model.

METHODS

Forty-eight female Sprague-Dawley rats were randomly divided into the WS group, the cigarette smoke (CS) group and the clean air control group. After 4 to 7 months of smoke exposure, lung tissues were examined with morphometric measurements, immunohistochemistry and Western blotting. Serum MMP9 and TIMP1 concentrations were detected by ELISA. In vitro, primary rat tracheal epithelial cells were stimulated with wood smoke condensate for 7 days.

RESULTS

The COPD-like pathological alterations in rats exposed chronically to WS were similar to those exposed to CS; the area of collagen deposition was significantly increased in the small airway walls of those exposed to WS or CS for 7 months. The expression of gelatinases in rats induced by WS or CS exposure was markedly increased in whole lung tissue, and immunohistochemistry showed that MMP9, MMP2 and TIMP1 were primarily expressed in the airway epithelium. The serum levels of MMP9 and TIMP1 were significantly higher in rats secondary to WS or CS exposure. Few cells that double immunostained for E-cadherin and vimentin were observed in the airway subepithelium of rats exposed to WS for 7 months (only 3 of these 8 rats). In vitro, the expression of MMP9 and MMP2 proteins was upregulated in primary rat tracheal epithelial cells following exposure to wood smoke condensate for 7 days by Western blotting; positive immunofluorescent staining for vimentin and type I collagen was also observed.

CONCLUSIONS

These findings suggest that the upregulation of gelatinases and EMT might play a role in SAR in COPD associated with chronic exposure to wood smoke.

Sputum eicosanoid profiling in exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Eicosanoids are small lipid molecules with diverse biological functions in the airways.

OBJECTIVES

The aim of this study was to investigate changes in leukotriene B4 (LTB4), 8-isoprostane, prostaglandin E2 (PGE2) and cysteinyl-leukotriene (cys-LT) levels in the sputum of patients with chronic obstructive pulmonary disease (COPD) at the onset of a severe exacerbation and during the course of recovery.

METHODS

Thirty-seven ex-smoker COPD patients suffering an episode of acute exacerbation were enrolled. Samples were taken (i) on hospital admission and (ii) after regular treatment. Twenty-five stable ex-smoker COPD patients served as controls. Eicosanoids were determined by enzyme immunoassay.

RESULTS

Sputum PGE2 [39.8 (13.3-103.3) vs. 5.05 (2.3-12.1) pg/ml, p < 0.001], 8-isoprostane [89.5 (36.9-184.7) vs. 29.7 (13.8-68.8) pg/ml, p < 0.01] and LTB4 [587.7 (252.9-774.8) vs. 276.1 (105.4-594.7) pg/ml, p < 0.05] levels were increased in patients with exacerbation compared to stable subjects. After treatment only PGE2 levels decreased significantly [at discharge: 19.6 (4.6-52.5) pg/ml, p < 0.01], the levels of other eicosanoids remained elevated (p = NS). Sputum cys-LT levels were similar in stable patients and in those with exacerbation and treatment did not influence cys-LTs either. There was a significant correlation between PGE2 and sputum neutrophil and lymphocyte cell counts in patients with exacerbation.

CONCLUSIONS

Our results suggest that 8-isoprostane, LTB4 and PGE2 but not cys-LTs may be involved in exacerbation-associated inflammatory processes in the airways of patients with COPD. Validation of PGE2 for use as a biomarker of recovery from an exacerbation requires further studies.

Significant increase of prostaglandin E-major urinary metabolite in male smokers: a screening study of age and gender differences using a simple radioimmunoassay

BACKGROUND

For the assessment of inflammatory status, we have developed a simple, reliable radioimmunoassay (RIA) of prostaglandin E-major urinary metabolite (PGE-MUM), which remains stable in urine after it is metabolized. Using this method, we conducted a screening study to compare standard values of PGE-MUM to serum C-reactive protein (CRP) levels in health check volunteers.

METHODS

PGE-MUM (micrograms per gram creatinine) was measured in normal urine samples obtained from 797 samples in volunteers for health check, using a newly developed RIA, and analyzed in relation to age, gender, smoking, and drinking habits. Results were compared to serum CRP.

RESULTS

PGE-MUM was significantly higher in males than in females. It was significantly higher in smoking males, compared to males who had never smoked (nonsmokers), particularly in those above 40 years of age. In nonsmokers, PGE-MUM declined in males with advancing age, while it rose in females. Although PGE-MUM reflected current smoking status, independent of smoking index (SI), serum CRP indicated both current and former smoking condition, rather dependent upon SI.

CONCLUSIONS

PGE-MUM increases in smokers, as suggested by possible inflammatory injury of pulmonary tissue. This RIA method for PGE-MUM may be thus a sensitive and reliable biomarker for current inflammation, different from serum CRP.

PGE 2 desensitizes β -agonist effect on human lung fibroblast-mediated collagen gel contraction through upregulating PDE4

In the current study, we investigated the effect of a long-acting β-agonist (salmeterol) and a phosphodiesterase 4 (PDE4) inhibitor (cilomilast) on human lung fibroblast-mediated collagen gel contraction. Higher concentrations of salmeterol (10⁻⁷ and 10⁻⁶ M) inhibited fibroblast-mediated collagen gel contraction. No effect was observed with cilomilast alone (up to 10⁻⁵ M). In the presence of 10⁻⁸ M salmeterol, however, cilomilast could significantly inhibit fibroblast-mediated collagen gel contraction in a concentration-dependent manner (10⁻⁷~10⁻⁵ M). Blockade of endogenous PGE₂ by indomethacin further potentiated the inhibitory effect of salmeterol on fibroblast-mediated collagen gel contraction, but it did not affect cilomilast's effect. Pretreatment with PGE₂ abolished the inhibitory effect of salmeterol, but it potentiated the inhibitory effect of cilomilast on fibroblast-mediated collagen gel contraction. Finally, indomethacin slightly inhibited PDE4C expression, while PGE₂ stimulated the expression of PDE4A and -4C in human lung fibroblasts. These findings suggest that long-acting β-agonist and PDE4 inhibitor have a synergistic effect in regulating fibroblast tissue repair functions and that PGE₂ can modulate the effect of β-agonist and PDE4 inhibitor at least in part through the mechanism of regulating PDE4 expression.

Aryl hydrocarbon receptor-dependent retention of nuclear HuR suppresses cigarette smoke-induced cyclooxygenase-2 expression independent of DNA-binding

The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor that responds to man-made environmental toxicants, has emerged as an endogenous regulator of cyclooxygenase-2 (Cox-2) by a mechanism that is poorly understood. In this study, we first used AhR-deficient (AhR^−/−) primary pulmonary cells, together with pharmacological tools to inhibit new RNA synthesis, to show that the AhR is a prominent factor in the destabilization of Cox-2 mRNA. The destabilization of Cox-2 mRNA and subsequent suppression of cigarette smoke-induced COX-2 protein expression by the AhR was independent of its ability to bind the dioxin response element (DRE), thereby differentiating the DRE-driven toxicological AhR pathway from its anti-inflammatory abilities. We further describe that the AhR destabilizes Cox-2 mRNA by sequestering HuR within the nucleus. The role of HuR in AhR stabilization of Cox-2 mRNA was confirmed by knockdown of HuR, which resulted in rapid Cox-2 mRNA degradation. Finally, in the lungs of AhR^−/− mice exposed to cigarette smoke, there was little Cox-2 mRNA despite robust COX-2 protein expression, a finding that correlates with almost exclusive cytoplasmic HuR within the lungs of AhR^−/− mice. Therefore, we propose that the AhR plays an important role in suppressing the expression of inflammatory proteins, a function that extends beyond the ability of the AhR to respond to man-made toxicants. These findings open the possibility that a DRE-independent AhR pathway may be exploited therapeutically as an anti-inflammatory target.

Discovery and characterization of carbamothioylacrylamides as EP2 selective antagonists

Prostanoid receptor EP2 is emerging as a novel target for development of anti-inflammatory drugs for the treatment of chronic neurodegenerative and peripheral diseases; however, the availability of EP2 antagonist probes for exploration of peripheral disease models is very limited. We now report identification and characterization of a novel chemical class of compounds that show nanomolar potency and competitive antagonism of the EP2 receptor. A compound in this class, TG6-129, showed prolonged plasma half-life and did not cross the blood brain barrier. This compound also suppressed the induction of inflammatory mRNA markers in a macrophage cell line upon activation of EP2. Thus, this compound could be useful as a probe for a variety of peripheral chronic inflammatory diseases such as rheumatoid arthritis and chronic obstructive pulmonary disease, in which EP2 appears to play a pathogenic role.

Increased levels of urinary PGE-M, a biomarker of inflammation, occur in association with obesity, aging, and lung metastases in patients with breast cancer

Elevated levels of COX-derived prostaglandin E2 (PGE2) occur in inflamed tissues. To evaluate the potential links between inflammation and breast cancer, levels of urinary prostaglandin E metabolite (PGE-M), a stable end metabolite of PGE2, were quantified. We enrolled 400 patients with breast cancer: controls with early breast cancer (n = 200), lung metastases (n = 100), and metastases to other sites (n = 100). Patients completed a questionnaire, provided urine, and had measurements of height and weight. Urinary PGE-M was quantified by mass spectrometry. Ever smokers with lung metastasis who had not been exposed to nonsteroidal anti-inflammatory drugs (NSAIDs) had the highest PGE-M levels. PGE-M levels were increased in association with elevated body mass index (BMI; P < 0.001), aging (P < 0.001), pack-year smoking history (P = 0.02), lung metastases (P = 0.02), and recent cytotoxic chemotherapy (P = 0.03). Conversely, use of NSAIDs, prototypic inhibitors of COX activity, was associated with reduced PGE-M levels (P < 0.001). On the basis of the current findings, PGE-M is likely to be a useful biomarker for the selection of high-risk subgroups to determine the use of interventions that aim to reduce inflammation and possibly the development and progression of breast cancer, especially in overweight and obese women.

Attenuation of inhibitory prostaglandin E2 signaling in human lung fibroblasts is mediated by phosphodiesterase 4

The etiology of chronic obstructive pulmonary disease (COPD) is complex and involves an aberrant inflammatory response. Prostaglandin (PG)E2 is elevated in COPD, is a key modulator of lung fibroblast functions, and may influence COPD progression. Most studies evaluating the effects of PGE2 on lung fibroblasts have used acute exposures. The current study evaluated whether longer-term exposure would induce attenuation of PGE2 signaling as part of an autoregulatory pathway. Human fetal lung fibroblasts were pretreated with PGE2 for 24 hours, and migration and cAMP accumulation in response to acute stimulation with PGE2 were assessed. Fibroblasts from adults with and without COPD were pretreated, and migration was assessed. PGE2 pretreatment attenuated subsequent PGE2-mediated inhibition of chemotaxis and cAMP stimulation. This attenuation was predominantly due to an increase in phosphodiesterase (PDE)4-mediated degradation of cAMP rather than to decreased activation of PGE2 receptors (receptor desensitization). Albuterol- and iloprost-mediated signaling were also attenuated after PGE2 pretreatment, suggesting that activation of PDE4 was able to broadly modulate multiple cAMP-coupled pathways. Lung fibroblasts from adult control subjects pretreated with PGE2 also developed attenuation of PGE2-mediated inhibition of chemotaxis. In contrast, fibroblasts obtained from patients with COPD maintained inhibitory PGE2 signaling after PGE2 pretreatment. These data identify a PDE4-mediated attenuation of PGE2 inhibitory signaling in normal fibroblasts that appears to be altered in COPD fibroblasts. These alterations may contribute to COPD pathogenesis and could provide novel therapeutic targets.

Serum amyloid A opposes lipoxin A₄ to mediate glucocorticoid refractory lung inflammation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) will soon be the third most common cause of death globally. Despite smoking cessation, neutrophilic mucosal inflammation persistently damages the airways and fails to protect from recurrent infections. This maladaptive and excess inflammation is also refractory to glucocorticosteroids (GC). Here, we identify serum amyloid A (SAA) as a candidate mediator of GC refractory inflammation in COPD. Extrahepatic SAA was detected locally in COPD bronchoalveolar lavage fluid, which correlated with IL-8 and neutrophil elastase, consistent with neutrophil recruitment and activation. Immunohistochemistry detected SAA was in close proximity to airway epithelium, and in vitro SAA triggered release of IL-8 and other proinflammatory mediators by airway epithelial cells in an ALX/FPR2 (formyl peptide receptor 2) receptor-dependent manner. Lipoxin A(4) (LXA(4)) can also interact with ALX/FPR2 receptors and lead to allosteric inhibition of SAA-initiated epithelial responses (pA(2) 13 nM). During acute exacerbation, peripheral blood SAA levels increased dramatically and were disproportionately increased relative to LXA(4). Human lung macrophages (CD68(+)) colocalized with SAA and GCs markedly increased SAA in vitro (THP-1, pEC(50) 43 nM). To determine its direct actions, SAA was administered into murine lung, leading to induction of CXC chemokine ligand 1/2 and a neutrophilic response that was inhibited by 15-epi-LXA(4) but not dexamethasone. Taken together, these findings identify SAA as a therapeutic target for inhibition and implicate SAA as a mediator of GC-resistant lung inflammation that can overwhelm organ protective signaling by lipoxins at ALX/FPR2 receptors.

Combined histone deacetylase and cyclooxygenase inhibition achieves enhanced antiangiogenic effects in lung cancer cells

Prostaglandin E2 (PGE2) is an important pro-angiogenic and pro-proliferative cytokine and the key enzymes modulating its levels, cyclooxygenase (COX)-2 and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) play important opposing roles in carcinogenesis. Previously we found loss of 15-PGDH expression in lung cancer and its reactivation leads to strong in vivo tumor-suppressive effect via an antiangiogenic mechanism. Here, we find that HDAC inhibitors (HDACI), such as trichostatin A (TSA) and vorinostat could reactivate 15-PGDH expression but overall induce PGE2 generation and this is the result of concomitant induction of COX-1 and -2 leading to functional promotion of endothelial cell proliferation and capillary formation. Direct TSA treatment inhibits endothelial cell proliferation and capillary formation in our study in line with prior reports as HDACIs have been shown to directly inhibit angiogenesis. The elevation of PGE2 levels induced by HDACI is potently neutralized by indomethacin (INN) or Celecoxib co-treatment and accordingly, angiogenesis is more effectively inhibited when using conditioned medium of co-treatment than either alone confirming that this effect is mediated via the PGE2 axis. Accordingly, blockage of EP2/4 receptors mitigates the stimulation of angiogenesis by excessive PGE2 generation mediated by TSA. In this study, we identify a potentially adverse effect of HDACIs through induction of both 15-PGDH and COX-2 leading to elevated PGE2 levels and thereby stimulation of angiogenesis. Co-treatment of TSA and INN shows more potent anti-angiogenic effects by inducing 15-PGDH and inhibiting COX-2. Overall, our results suggest that combined HDACI and COX inhibition should be explored clinically to achieve more meaningful benefits from HDACI therapy in lung cancer.

Regulation of cyclooxygenase-2 and cytosolic phospholipase A2 gene expression by lipopolysaccharide through the RNA-binding protein HuR: involvement of NADPH oxidase, reactive oxygen species and mitogen-activated protein kinases

BACKGROUND AND PURPOSE Lipopolysaccharide (LPS)-induced expression of cyclooxygenase-2 (COX-2) and cytosolic phospholipase A(2) (cPLA(2) ) has been implicated in several respiratory diseases. HuR is known to enhance the expression of genes by binding to 3'-untranslated region (3'-UTR) of mRNA and stabilizing mRNA. However, the exact mechanisms by which HuR affects the stability of mRNA and modulates LPS-induced COX-2 and cPLA(2) expression in human tracheal smooth muscle cells (HTSMCs) are not known. EXPERIMENTAL APPROACH The expression of prostaglandin E(2) (PGE(2) ) was measured by ELISA, and pro-inflammatory proteins were determined by use of a promoter assay, PCR or Western blot analysis. Overexpression of siRNAs to knock down the target components was used to manipulate the expression of HuR. Release of reactive oxygen species (ROS) was detected by fluorescence dye. The activation of signalling components was assessed by comparing phosphorylation levels, localization of protein kinases or coimmunoprecipitation assay. KEY RESULTS LPS induced COX-2 and cPLA(2) expression via post-translational regulation of mRNA stabilization, which were attenuated by transfection with HuR siRNA in HTSMCs. In addition, LPS-stimulated NADPH oxidase activation and ROS generation were attenuated by the NADPH oxidase inhibitors diphenyleneiodonium chloride (DPI) and apocynin (APO). Generation of ROS induced phosphorylation of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK and JNK1/2, which was attenuated by DPI and APO and the ROS scavenger N-acetylcysteine. CONCLUSIONS AND IMPLICATIONS These results suggested that in HTSMCs, LPS-induced COX-2 and cPLA(2) expression is mediated through NADPH oxidase/ROS-dependent MAPKs associated with HuR accumulation in the cytoplasm. Activated MAPKs may regulate the nucleocytoplasmic shuttling of HuR, and thus induce the cytoplasmic accumulation of HuR.

Fibrotic response of tissue remodeling in COPD

Lung tissue remodeling in chronic obstructive pulmonary disease (COPD) involves diverse processes characterized by epithelial disruption, smooth muscle hypertrophy/hyperplasia, airway wall fibrosis, and alveolar destruction. According to the accepted current theory of COPD pathogenesis, tissue remodeling in COPD is predominantly a consequence of an imbalance between proteolytic and antiproteolytic activities. However, most of the studies carried out during the last few years have focused on mechanisms related to degradation of extracellular matrix (ECM) structural proteins, neglecting those involved in ECM protein deposition. This review revisits some of the latest findings related to fibrotic changes that occur in the airway wall of COPD patients, as well as the main cellular phenotypes relevant to these processes.

Cooperation of TLR2 with MyD88, PI3K, and Rac1 in lipoteichoic acid-induced cPLA2/COX-2-dependent airway inflammatory responses

Lipoteichoic acid (LTA) plays a role in the pathogenesis of severe inflammatory responses induced by Gram-positive bacterial infection. Cytosolic phospholipase A(2) (cPLA(2)), cyclooxygenase-2 (COX-2), prostaglandin E(2) (PGE(2)), and interleukin (IL)-6 have been demonstrated to engage in airway inflammation. In this study, LTA-induced cPLA(2) and COX-2 expression and PGE(2) or IL-6 synthesis were attenuated by transfection with siRNAs of TLR2, MyD88, Akt, p42, p38, JNK2, and p65 or pretreatment with the inhibitors of PI3K (LY294002), p38 (SB202190), MEK1/2 (U0126), JNK1/2 (SP600125), and NF-kappaB (helenalin) in human tracheal smooth muscle cells (HTSMCs). LTA also induced cPLA(2) and COX-2 expression and leukocyte count in bronchoalveolar lavage fluid in mice. LTA-regulated PGE(2) or IL-6 production was inhibited by pretreatment with the inhibitors of cPLA(2) (AACOCF(3)) and COX-2 (NS-398) or transfection with cPLA(2) siRNA or COX-2 siRNA, respectively. LTA-stimulated NF-kappaB translocation or cPLA(2) phosphorylation was attenuated by pretreatment with LY294002, SB202190, U0126, or SP600125. Furthermore, LTA could stimulate TLR2, MyD88, PI3K, and Rac1 complex formation. We also demonstrated that Staphylococcus aureus could trigger these responses through a similar signaling cascade in HTSMCs. It was found that PGE(2) could directly stimulate IL-6 production in HTSMCs or leukocyte count in bronchoalveolar lavage fluid in mice. These results demonstrate that LTA-induced MAPKs activation is mediated through the TLR2/MyD88/PI3K/Rac1/Akt pathway, which in turn initiates the activation of NF-kappaB, and ultimately induces cPLA(2)/COX-2-dependent PGE(2) and IL-6 generation.

Differential expression of tissue repair genes in the pathogenesis of chronic obstructive pulmonary disease

RATIONALE

The airflow limitation that defines severity of chronic obstructive pulmonary disease (COPD) is caused by a combination of small airway obstruction and emphysematous lung destruction.

OBJECTIVES

To examine the hypothesis that small airway obstructive and emphysematous destructive lesions are produced by differential expression of genes associated with tissue repair.

METHODS

The expression of 54 genes associated with repair of repetitively damaged tissue was measured in 136 paired samples of small bronchioles and surrounding lung tissue separated by laser capture microdissection. These samples were collected from 63 patients at different levels of disease severity who required surgery for either lung cancer or lung transplantation for very severe COPD. Gene expression was measured by quantitative polymerase chain reaction in these paired samples and compared with the FEV(1) by linear regression analysis.

MEASUREMENTS AND MAIN RESULTS

After corrections for false discovery rates, only 2 of 10 genes (serpin peptidase inhibitor/plasminogen activator inhibitor member 2 and matrix metalloproteinase [MMP] 10) increased, whereas 8 (MMP2, integrin-alpha1, vascular endothelial growth factor, a disintegrin and metallopeptidase domain 33, scatter factor/hepatocyte growth factor, tissue inhibitor of matrix metalloproteinase-2, fibronectin, and collagen 3alpha1) decreased in small airways in association with FEV(1). In contrast, 8/12 genes (early growth response factor 1, MMP1, MMP9, MMP10, plasminogen activator urokinase, plasminogen activator urokinase receptor, tumor necrosis factor, and IL13) increased and 4/12 (MMP2, tissue inhibitor of matrix metalloproteinase-1, collagen 1alpha1, and transforming growth factor-beta3) decreased in the surrounding lung tissue in association with progression of COPD.

CONCLUSIONS

The progression of COPD is associated with the differential expression of a cluster of genes that favor the degradation of the tissue surrounding the small conducting airways.

Levels of prostaglandin E metabolite and leukotriene E(4) are increased in the urine of smokers: evidence that celecoxib shunts arachidonic acid into the 5-lipoxygenase pathway

Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO) play a role in inflammation and carcinogenesis. Biomarkers that reflect tobacco smoke-induced tissue injury are needed. In this study, levels of urinary prostaglandin E metabolite (PGE-M) and leukotriene E(4) (LTE(4)), biomarkers of the COX and 5-LO pathways, were compared in never smokers, former smokers, and current smokers. The effects of celecoxib, a selective COX-2 inhibitor, on levels of PGE-M and LTE(4) were determined. Baseline levels of PGE-M and LTE(4) were positively associated with smoking status; levels of PGE-M and LTE(4) were higher in current versus never smokers. Treatment with 200 mg celecoxib twice daily for 6 +/- 1 days led to a reduction in urinary PGE-M levels in all groups but exhibited the greatest effect among subjects with high baseline PGE-M levels. Thus, high baseline PGE-M levels in smokers reflected increased COX-2 activity. In individuals with high baseline PGE-M levels, treatment with celecoxib led to a significant increase in levels of urinary LTE(4), an effect that was not found in individuals with low baseline PGE-M levels. In conclusion, increased levels of urinary PGE-M and LTE(4) were found in human smokers, a result that may reflect subclinical lung inflammation. In individuals with high baseline levels of PGE-M (elevated COX-2 activity), celecoxib administration shunted arachidonic acid into the proinflammatory 5-LO pathway. Because 5-LO activity and LTE(4) have been suggested to play a role in cardiovascular disease, these results may help to explain the link between use of COX-2 inhibitors and cardiovascular complications.