IL-17A induces chromatin remodeling promoting IL-8 release in bronchial epithelial cells: Effect of Tiotropium

Tiao-Bu-Fei-Shen Formula Improves Glucocorticoid Resistance of Chronic Obstructive Pulmonary Disease via Downregulating the PI3K-Akt Signaling Pathway and Promoting GRα Expression

Objective

To predict and determine the mechanism through which Tiao-Bu-Fei-Shen (TBFS) formula improves glucocorticoid resistance in chronic obstructive pulmonary disease (COPD), using network pharmacology, molecular docking technology, and in vitro studies.

Methods

The main active components and associated targets of TBFS were screened using the systems pharmacology database of traditional Chinese medicine database (TCMSP). The main COPD targets were retrieved from the Human Gene (GeneCards) and DrugBank databases. A protein-protein interaction (PPI) network was constructed using the protein interaction platform STRING and Cytoscape 3.6.1. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genome Pathway (KEGG) analyses were performed using the biological information annotation database Metascape. Molecular docking was performed using the AutoDock Vina software. THP-1 monocytes were treated with TBFS-containing serum and cigarette smoke extract (CSE) for 48 h, and cell proliferation in each group was determined using cell counting kit-8 (CCK-8). A COPD cell model was constructed by stimulating THP-1 monocytes with CSE for 12 h. A lentivirus vector for RNA interference of histone deacetylase 2 (HDAC2) gene was constructed and transfected into the THP-1 monocytes, and the transfection efficiency was verified using quantitative polymerase chain reaction (qPCR) and western blotting (WB). The expression of HDAC2 in each group of cells was detected using qPCR, and the expression of HDAC2, phosphoinositide-3 kinase (PI3K) p85α, glucocorticoid receptor α (GRα), and P-AKT1 in each group of cells was detected through WB.

Results

A total of 344 TBFS active components, 249 related drug targets, 1,171 COPD target proteins, and 138 drug and disease intersection targets were obtained. Visual analysis of the PPI network map revealed that the core COPD targets of TBFS were AKT1, IL-6, TNF, TP53, and IL1-β. KEGG pathway enrichment analysis resulted in the identification of 20 signaling pathways as the main pathways involved in the action of TBFS against COPD, including the PI3K-Akt, TNF, and IL-17 signaling pathways. Molecular docking experiments revealed a strong binding capacity of kaempferol, luteolin, and quercetin to the ATK1 protein in TBFS, with quercetin performing the best. PCR results showed that treatment with TBFS significantly increased the expression levels of HDAC2 in the COPD model. WB results showed that TBFS treatment significantly increased the expression levels of GRα and HDAC2 in the COPD model, while reducing the expression levels of P-AKT1.

Conclusion

TBFS treatment improves glucocorticoid resistance observed in COPD through downregulation of the PI3K-Akt signaling pathway and promotion of GRα expression.

Tiotropium Bromide Improves Neutrophilic Asthma by Recovering Histone Deacetylase 2 Activity

BACKGROUND

The value of tiotropium bromide (TIO) in neutrophilic asthma was meaningful in previous study. We hypothesized that TIO's mechanism of action is associated with histone deacetylase 2 (HDAC2) activity, which is key for controlling the transcription of inflammatory cytokines and usually downregulated in neutrophilic asthma.

METHODS

The effects of TIO and dexamethasone (DEX) on HDAC2 activity, nuclear factor kappa B (NF-κB), and C-X-C motif chemokine ligand 1 (CXCL1) were evaluated in neutrophilic asthma mouse model (C57BL, 6-week-old). An in-vitro study was conducted using primary human bronchial/tracheal epithelial (HBE) cells from asthma patients. Western blot analyses were performed for phospho-phospholipase Cγ-1 (PLCγ-1) and inositol trisphosphate (IP₃) receptors (IP₃R) with treating lipopolysaccharide (LPS) and TIO.

RESULTS

Ovalbumin was used to induce eosinophilic inflammation in this study. After neutrophilic asthma was induced by LPS (O+L group), HDAC2 activity was diminished with increased NF-κB activity and CXCL1 compared to the control group. TIO significantly improved NF-κB activity, CXCL1, and HDAC2 activity compared with the O+L group in in-vivo study (P < 0.05, each). Western blot analyses showed that LPS treated HBE cells from asthma patients increased PLCγ-1 and diminished IP₃ receptor levels. After TIO treatment, recovery of IP₃R and improved PLCγ-1 levels were observed.

CONCLUSION

These results support the hypothesis that TIO modulates inflammation by recovering HDAC2 activity from the acetylcholine-stimulated inflammation cascade in neutrophilic asthma. The detailed inflammation cascade of recovering HDAC2 activity by TIO might be associated with PLCγ-1-IP₃-IP₃R mediated intracellular calcium ion pathway.

EphA2 recognizes Dermatophagoidespteronyssinus to mediate airway inflammation in asthma

Most of the asthma with low Th2 is severe steroid-resistant asthma, the exact pathogenesis of which has not yet been fully elucidated. We found that IL-6 and IL-8 were highly expressed in the sputum supernatant of severe asthma and ephrin type-A receptor 2 (EphA2) was highly expressed on bronchial epithelial cells. So, is there a connection between these two phenomena? To clarify this issue, we stimulated bronchial epithelial cells 16HBE with Dermatophagoides pteronyssinus and its compontents LPS, respectively, and detected the activation of EphA2, activation of downstream pathways and secretion of inflammatory cytokines. A mouse asthma model was established, and the therapeutic effects of inhibiting or blocking EphA2 on mouse asthma were investigated. The results showed that D. pteronyssinus and its component LPS phosphorylated EphA2 on 16HBE, activated downstream signaling pathways STAT3 and p38 MAPK, and promoted the secretion of IL-6 and IL-8. After knockout of EphA2 on 16HBE, the activation of inflammatory pathways was attenuated and the secretion of IL-6 and IL-8 was significantly reduced. Inhibition or blockade of EphA2 on mouse airways resulted in a significant reduction in airway hyperresponsiveness and airway inflammation, and a significant decrease in the expression levels of IL-6, IL-17F, IL-1α, IL-1β and TNF in bronchoalveolar lavage fluid and lung tissue. Our study uncovers a novel role for EphA2 expressed on airway epithelial cells in the pathogenesis of asthma; EphA2 recognizes D. pteronyssinus or its component LPS and promotes the secretion of IL-6 and IL-8 by airway epithelial cell, thereby mediating airway inflammation. Thus, it is possible to provide a new molecular therapy for severe asthma.

Muscarinic receptor antagonists and airway inflammation: A systematic review on pharmacological models

Airway inflammation is crucial in the pathogenesis of many respiratory diseases, including chronic obstructive pulmonary disease (COPD) and asthma. Current evidence supports the beneficial impact of muscarinic receptor antagonists against airway inflammation from bench-to-bedside. Considering the numerous sampling approaches and the ethical implications required to study inflammation in vivo in patients, the use of pre-clinical models is inevitable. Starting from our recently published systematic review concerning the impact of muscarinic antagonists, we have systematically assessed the current pharmacological models of airway inflammation and provided an overview on the advances in in vitro and ex vivo approaches. The purpose of in vitro models is to recapitulate selected pathophysiological parameters or processes that are crucial to the development of new drugs within a controlled environment. Nevertheless, immortalized cell lines or primary airway cells present major limitations, including the inability to fully replicate the conditions of the corresponding cell types within a whole organism.

Induced animal models are extensively used in research in the attempt to replicate a respiratory condition reflective of a human pathological state, although considering animal models with spontaneously occurring respiratory diseases may be more appropriate since most of the clinical features are accompanied by lung pathology resembling that of the human condition.

In recent years, three-dimensional organoids have become an alternative to animal experiments, also because animal models are unable to fully mimic the complexity of human pulmonary diseases. Ex vivo studies performed on human isolated airways have a superior translational value compared to in vitro and animal models, as they retain the morphology and the microenvironment of the lung in vivo.

In the foreseeable future, greater effort should be undertaken to rely on more physiologically relevant models, that provide translational value into clinic and have a direct impact on patient outcomes.

Neutrophils and Asthma

Although eosinophilic inflammation is characteristic of asthma pathogenesis, neutrophilic inflammation is also marked, and eosinophils and neutrophils can coexist in some cases. Based on the proportion of sputum cell differentiation, asthma is classified into eosinophilic asthma, neutrophilic asthma, neutrophilic and eosinophilic asthma, and paucigranulocytic asthma. Classification by bronchoalveolar lavage is also performed. Eosinophilic asthma accounts for most severe asthma cases, but neutrophilic asthma or a mixture of the two types can also present a severe phenotype. Biomarkers for the diagnosis of neutrophilic asthma include sputum neutrophils, blood neutrophils, chitinase-3-like protein, and hydrogen sulfide in sputum and serum. Thymic stromal lymphoprotein (TSLP)/T-helper 17 pathways, bacterial colonization/microbiome, neutrophil extracellular traps, and activation of nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 pathways are involved in the pathophysiology of neutrophilic asthma and coexistence of obesity, gastroesophageal reflux disease, and habitual cigarette smoking have been associated with its pathogenesis. Thus, targeting neutrophilic asthma is important. Smoking cessation, neutrophil-targeting treatments, and biologics have been tested as treatments for severe asthma, but most clinical studies have not focused on neutrophilic asthma. Phosphodiesterase inhibitors, anti-TSLP antibodies, azithromycin, and anti-cholinergic agents are promising drugs for neutrophilic asthma. However, clinical research targeting neutrophilic inflammation is required to elucidate the optimal treatment.

Cellular and Molecular Signatures of Oxidative Stress in Bronchial Epithelial Cell Models Injured by Cigarette Smoke Extract

Exposure of the airways epithelium to environmental insults, including cigarette smoke, results in increased oxidative stress due to unbalance between oxidants and antioxidants in favor of oxidants. Oxidative stress is a feature of inflammation and promotes the progression of chronic lung diseases, including Chronic Obstructive Pulmonary Disease (COPD). Increased oxidative stress leads to exhaustion of antioxidant defenses, alterations in autophagy/mitophagy and cell survival regulatory mechanisms, thus promoting cell senescence. All these events are amplified by the increase of inflammation driven by oxidative stress. Several models of bronchial epithelial cells are used to study the molecular mechanisms and the cellular functions altered by cigarette smoke extract (CSE) exposure, and to test the efficacy of molecules with antioxidant properties. This review offers a comprehensive synthesis of human in-vitro and ex-vivo studies published from 2011 to 2021 describing the molecular and cellular mechanisms evoked by CSE exposure in bronchial epithelial cells, the most used experimental models and the mechanisms of action of cellular antioxidants systems as well as natural and synthetic antioxidant compounds.

Tiotropium bromide has a more potent effect than corticosteroid in the acute neutrophilic asthma mouse model

Background

Neutrophilic asthma (NeuA) is usually resistant to corticosteroids. Tiotropium bromide (TIO) is a bronchodilator that is used as an add-on therapy to inhaled corticosteroid and long-acting β2 agonist in asthma treatment. However, the role of TIO in NeuA is not fully known. Thus, the aim of this study was to evaluate the effect of TIO on NeuA compared to that of corticosteroids.

Methods

C57BL/6 female mice were sensitized with ovalbumin and lipopolysaccharide to induce neutrophilic inflammation. Dexamethasone (DEX) was administered on days 14, 17, 20, and 23. TIO was inhaled on days 21, 21, and 23. On day 24, mice were sacrificed. Airway hyper-responsiveness, levels of cytokines in bronchoalveolar lavage (BAL) and lung homogenates, and lung tissue histopathology were compared between the two groups.

Results

Neutrophil counts, T helper 2 cells (T_H2)/T_H17 cytokines, and pro-inflammatory cytokine in BAL fluids were elevated in the NeuA group. TIO group showed lower total cells, neutrophil counts, and eosinophil counts in BAL fluids than the DEX group (p<0.001, p<0.05, and p<0.001, respectively). Airway resistance was attenuated in the TIO group but elevated in the NeuA group (p<0.001). Total protein, interleukin (IL)-5, and IL-17A levels in BAL fluids were lower in the TIO group than in the NeuA group (all p<0.05).

Conclusion

TIO showed more potent effects than DEX in improving airway inflammation and attenuating airway resistance in NeuA.

Emerging Biological Functions of IL-17A: A New Target in Chronic Obstructive Pulmonary Disease?

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease that causes high rates of disability and mortality worldwide because of severe progressive and irreversible symptoms. During the period of COPD initiation and progression, the immune system triggers the activation of various immune cells, including Regulatory T cells (Tregs), dendritic cells (DCs) and Th17 cells, and also the release of many different cytokines and chemokines, such as IL-17A and TGF-β. In recent years, studies have focused on the role of IL-17A in chronic inflammation process, which was found to play a highly critical role in facilitating COPD. Specially, IL-17A and its downstream regulators are potential therapeutic targets for COPD. We mainly focused on the possibility of IL-17A signaling pathways that involved in the progression of COPD; for instance, how IL-17A promotes airway remodeling in COPD? How IL-17A facilitates neutrophil inflammation in COPD? How IL-17A induces the expression of TSLP to promote the progression of COPD? Whether the mature DCs and Tregs participate in this process and how they cooperate with IL-17A to accelerate the development of COPD? And above associated studies could benefit clinical application of therapeutic targets of the disease. Moreover, four novel efficient therapies targeting IL-17A and other molecules for COPD are also concluded, such as Bufei Yishen formula (BYF), a Traditional Chinese Medicine (TCM), and curcumin, a natural polyphenol extracted from the root of Curcuma longa.

Effects of indacaterol on the LPS-evoked changes in fluid secretion rate and pH in swine tracheal membrane

An acquired dysregulation of airway secretion is likely involved in the pathophysiology of chronic bronchitis and chronic obstructive pulmonary disease (COPD). Nowadays, it is widely known that several kinds of long-acting bronchodilators reduce the frequency of COPD exacerbations. However, limited data are available concerning the complementary additive effects on airflow obstruction. Using an optical method and a selective pH indicator, we succeeded in evaluating the gland secretion rate and the pH in swine tracheal membrane. A physiologically relevant concentration of acetylcholine (ACh) 100 nM induced a gradual increase in the amount of gland secretion. Lipopolysaccharides (LPS) accelerated the ACh-induced secretory responses up to around threefold and lowered the pH level significantly. Long-acting β₂-agonists (LABAs) including indacaterol (IND), formoterol, and salmeterol restored the LPS-induced changes in both the hypersecretion and acidification. The subsequent addition of the long-acting muscarine antagonist, glycopyrronium, further increased the pH values. Two different inhibitors for cystic fibrosis transmembrane conductance regulator (CFTR), NPPB and CFTR_inh172, abolished the IND-mediated pH normalization in the presence of both ACh and ACh + LPS. Both immunofluorescence staining and western blotting analysis revealed that LPS downregulated the abundant expression of CFTR protein. However, IND did not restore the LPS-induced decrease in CFTR expression on Calu-3 cells. These findings suggest that the activation of cAMP-dependent HCO₃⁻ secretion through CFTR would be partly involved in the IND-mediated pH normalization in gland secretion and may be suitable for the maintenance of airway defense against exacerbating factors including LPS.

Comparative studies of dual bronchodilation in COPD

Dual bronchodilation therapy is becoming the cornerstone for the treatment of COPD because the clinical benefits of LABA/LAMA fixed-dose combinations (FDCs) are now extensively established. Therefore, it not surprising that a number of LAMA/LABA combinations in a single inhaler have now been approved for clinical use as treatments for patients with COPD. Regrettably, very few head-to-head studies between all of the available LABA/LAMA FDCs have been carried out. This makes choosing the most appropriate FDC difficult. Comparative effectiveness research that also uses conventional meta-analyses to compare different care strategies can help generate useful information. A bidimensional comparative analysis across LAMA/LABA FDCs has suggested constant superiority for tiotropium/olodaterol. However, considering that there is not an equivalent amount of evidence on efficacy outcomes for all LAMA/LABA FDCs, a proper comparison between the different LAMA/LABA FDCs cannot be made yet, and the information available is still rather inconsistent.

The Impact of Muscarinic Receptor Antagonists on Airway Inflammation: A Systematic Review

Long-acting muscarinic receptor antagonists (LAMAs) are the cornerstone for the treatment of chronic obstructive pulmonary disease (COPD); furthermore, tiotropium is approved as add-on therapy in severe asthmatic patients. Accumulating evidence suggests that LAMAs may modulate airway contractility and airway hyperresponsiveness not only by blocking muscarinic acetylcholine receptors (mAchRs) expressed on airway smooth muscle but also via anti-inflammatory mechanisms by blocking mAchRs expressed on inflammatory cells, submucosal glands, and epithelial cells. The aim of this systematic review, performed according to the PRISMA-P guidelines, was to provide a synthesis of the literature on the anti-inflammatory impact of muscarinic receptor antagonists in the airways. Most of the current evidence originates from studies on tiotropium, that demonstrated a reduction in synthesis and release of cytokines and chemokines, as well as the number of total and differential inflammatory cells, induced by different pro-inflammatory stimuli. Conversely, few data are currently available for aclidinium and glycopyrronium, whereas no studies on the potential anti-inflammatory effect of umeclidinium have been reported. Overall, a large body of evidence supports the beneficial impact of tiotropium against airway inflammation. Further well-designed randomized controlled trials are needed to better elucidate the anti-inflammatory mechanisms leading to the protective effect of LAMAs against exacerbations via identifying suitable biomarkers.

Tiotropium in asthma - perspectives for the primary care physician

Asthma is a heterogeneous disease characterized by airway inflammation resulting from complex interactions between multiple hosts as well as environmental factors. As a chronic respiratory condition, asthma exerts a significant impact on patients and the healthcare system. Per the Global Initiative for Asthma (GINA), inhaled corticosteroids (ICS) with/without long-acting beta₂-agonists (LABAs) should be used as the preferred controllers for the management of asthma. Despite a range of therapeutic options, many patients with asthma remain uncontrolled, resulting in an increased risk of hospitalization and emergency room visits and a worsened quality of life. Tiotropium (Spiriva®, Boehringer Ingelheim Pharmaceuticals, Inc; 1.25 µg, two puffs, once daily), delivered via the Respimat® inhaler (Boehringer Ingelheim Pharmaceuticals, Inc.), was the first long-acting muscarinic antagonist to be approved as an add-on maintenance treatment option for patients with asthma aged ≥6 years at GINA steps 4 and 5. By binding to the muscarinic receptors M1 and M3 in the bronchial airways, tiotropium antagonizes the action of acetylcholine, leading to smooth muscle relaxation and reduced mucus secretion.The efficacy and safety of tiotropium add-on to ICS±LABA maintenance treatment have been evaluated in randomized controlled trials (RCTs) involving patients with a range of asthma severities (mild, moderate, and severe) and across age groups (children, adolescents, and adults). Add-on tiotropium was found to be well tolerated and efficacious in all RCTs. Moreover, the findings from real-world studies complement results from RCTs, showing beneficial effects of tiotropium in reducing exacerbations, hospitalization, emergency room visits, and asthma worsening.In this review article, we discuss the pathophysiology of asthma and the role of tiotropium in the management of asthma from the perspective of a primary care physician.

Tiotropium is Predicted to be a Promising Drug for COVID-19 Through Transcriptome-Based Comprehensive Molecular Pathway Analysis

The coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects almost everyone in the world in many ways. We previously predicted antivirals (atazanavir, remdesivir and lopinavir/ritonavir) and non-antiviral drugs (tiotropium and rapamycin) that may inhibit the replication complex of SARS-CoV-2 using our molecular transformer-drug target interaction (MT-DTI) deep-learning-based drug-target affinity prediction model. In this study, we dissected molecular pathways upregulated in SARS-CoV-2-infected normal human bronchial epithelial (NHBE) cells by analyzing an RNA-seq data set with various bioinformatics approaches, such as gene ontology, protein-protein interaction-based network and gene set enrichment analyses. The results indicated that the SARS-CoV-2 infection strongly activates TNF and NFκB-signaling pathways through significant upregulation of the TNF, IL1B, IL6, IL8, NFKB1, NFKB2 and RELB genes. In addition to these pathways, lung fibrosis, keratinization/cornification, rheumatoid arthritis, and negative regulation of interferon-gamma production pathways were also significantly upregulated. We observed that these pathologic features of SARS-CoV-2 are similar to those observed in patients with chronic obstructive pulmonary disease (COPD). Intriguingly, tiotropium, as predicted by MT-DTI, is currently used as a therapeutic intervention in COPD patients. Treatment with tiotropium has been shown to improve pulmonary function by alleviating airway inflammation. Accordingly, a literature search summarized that tiotropium reduced expressions of IL1B, IL6, IL8, RELA, NFKB1 and TNF in vitro or in vivo, and many of them have been known to be deregulated in COPD patients. These results suggest that COVID-19 is similar to an acute mode of COPD caused by the SARS-CoV-2 infection, and therefore tiotropium may be effective for COVID-19 patients.

The Airways' Mechanical Stress in Lung Disease: Implications for COPD Pathophysiology and Treatment Evaluation

The airway epithelium stretches and relaxes during the normal respiratory cycle, and hyperventilation exaggerates this effect, resulting in changes in lung physiology. In fact, stretching of the airways influences lung function and the secretion of airway mediators, which in turn may cause a potentially injurious inflammatory response. This aim of the present narrative review was to illustrate the current evidence on the importance of mechanical stress in the pathophysiology of lung diseases with a particular focus on chronic obstructive pulmonary disease (COPD) and to discuss how this may influence pharmacological treatment strategies. Overall, treatment selection should be tailored to counterpart the effects of mechanical stress, which influences inflammation both in asthma and COPD. The most suitable treatment approach between a long-acting β2-agonists/long-acting antimuscarinic-agonist (LABA/LAMA) alone or with the addition of inhaled corticosteroids should be determined based on the underlying mechanism of inflammation. Noteworthy, the anti-inflammatory effects of the glycopyrronium/indacaterol combination on hyperinflation and mucociliary clearance may decrease the rate of COPD exacerbations, and it may synergistically improve bronchodilation with a double action on both the cyclic adenosine monophosphate (cAMP) and the acetylcholine pathways.

Tiotropium inhibits proinflammatory microparticle generation by human bronchial and endothelial cells

Tiotropium is a muscarinic antagonist that reduces the risk of acute exacerbations of chronic obstructive pulmonary disease, possibly through an as yet incompletely characterized anti-inflammatory activity. We hypothesized that muscarinic activation of bronchial epithelial cells and endothelial cells causes the release of proinflammatory microparticles and that tiotropium inhibits the phenomenon. Microparticle generation was assessed by a functional assay, by flow cytometry and by NanoSight technology. Immortalized bronchial epithelial cells (16HBE) and umbilical vein endothelial cells were treated with acetylcholine in the presence of varying concentrations of tiotropium. Intracellular calcium concentration, extracellular regulated kinase phosphorylation and chemokine content in the conditioned media were assessed by commercial kits. Acetylcholine causes microparticle generation that is completely inhibited by tiotropium (50 pM). Microparticles generated by acetylcholine-stimulated cells increase the synthesis of proinflammatory mediators in an autocrine fashion. Acetylcholine-induced upregulation of microparticle generation is inhibited by an inhibitor of extracellular regulated kinase phosphorylation and by a phospholipase C inhibitor. Tiotropium blocks both extracellular regulated kinase phosphorylation and calcium mobilization, consistent with the hypothesis that the drug prevents microparticle generation through inhibition of these critical pathways. These results might contribute to explain the effect of tiotropium in reducing acute exacerbations of chronic obstructive pulmonary disease.

The Cholinergic Pathways in Inflammation: A Potential Pharmacotherapeutic Target for COPD

In COPD, the activity of the cholinergic system is increased, which is one of the reasons for the airflow limitation caused by the contraction of airway smooth muscles. Therefore, blocking the contractive actions with anticholinergics is a useful therapeutic intervention to reduce the airflow limitation. In addition to the effects of bronchoconstriction and mucus secretion, accumulating evidence from animal models of COPD suggest acetylcholine has a role in inflammation. Experiments using muscarinic M₃-receptor deficient mice or M₃ selective antagonists revealed that M₃-receptors on parenchymal cells, but not on hematopoietic cells, are involved in the pro-inflammatory effect of acetylcholine. Recently, combinations of long-acting β2 adrenergic agonists (LABAs) and long-acting muscarinic antagonists (LAMAs) have become available for COPD treatment. These dual long-acting bronchodilators may have synergistic anti-inflammatory effects because stimulation of β2 adrenergic receptors induces inhibitory effects in inflammatory cells via a different signaling pathway from that by antagonizing M₃-receptor, though these anti-inflammatory effects have not been clearly demonstrated in COPD patients. In contrast to the pro-inflammatory effects by ACh via muscarinic receptors, it has been demonstrated that the cholinergic anti-inflammatory pathway, which involves the parasympathetic nervous systems, regulates excessive inflammatory responses to protect organs during tissue injury and infection. Stimulation of acetylcholine via the α7 nicotinic acetylcholine receptor (α7nAChR) exerts inhibitory effects on leukocytes including macrophages and type 2 innate lymphoid cells. Although it remains unclear whether the inhibitory effects of acetylcholine via α7nAChR in inflammatory cells can regulate inflammation in COPD, neuroimmune interactions including the cholinergic anti-inflammatory pathway might serve as potential therapeutic targets.

IL-17A-associated IKK-α signaling induced TSLP production in epithelial cells of COPD patients

Thymic stromal lymphopoietin (TSLP) is a cytokine expressed in the epithelium, involved in the pathogenesis of chronic disease. IL-17A regulates airway inflammation, oxidative stress, and reduction of steroid sensitivity in chronic obstructive pulmonary disease (COPD). TSLP and IL-17A were measured in induced sputum supernatants (ISs) from healthy controls (HC), healthy smokers (HS), and COPD patients by enzyme-linked immunosorbent assay. Human bronchial epithelial cell line (16HBE) and normal bronchial epithelial cells were stimulated with rhIL-17A or ISs from COPD patients to evaluate TSLP protein and mRNA expression. The effects of the depletion of IL-17A in ISs, an anticholinergic drug, and the silencing of inhibitor kappa kinase alpha (IKKα) on TSLP production were evaluated in 16HBE cells. Coimmunoprecipitation of acetyl-histone H3(Lys14)/IKKα was evaluated in 16HBE cells treated with rhIL-17A and in the presence of the drug. TSLP and IL-17A levels were higher in ISs from COPD patients and HS compared with HC. TSLP protein and mRNA increased in 16HBE cells and in normal bronchial epithelial cells stimulated with ISs from COPD patients compared with ISs from HC and untreated cells. IKKα silencing reduced TSLP production in 16HBE cells stimulated with rhIL-17A and ISs from COPD patients. RhIL-17A increased the IKKα/acetyl-histone H3 immunoprecipitation in 16HBE cells. The anticholinergic drug affects TSLP protein and mRNA levels in bronchial epithelial cells treated with rhIL-17A or with ISs from COPD patients, and IKKα mediated acetyl-histone H3(Lys14). IL-17A/IKKα signaling induced the mechanism of chromatin remodeling associated with acetyl-histone H3(Lys14) and TSLP production in bronchial epithelial cells. Anticholinergic drugs might target TSLP derived from epithelial cells during the treatment of COPD.

Association of brain natriuretic peptide gene polymorphisms with chronic obstructive pulmonary disease complicated with pulmonary hypertension and its mechanism

Objective: To examine the association between brain natriuretic peptide (BNP) gene single nucleotide polymorphisms (SNPs) and chronic obstructive pulmonary disease (COPD) and COPD with pulmonary hypertension (PH) and to analyze its mechanism. Methods: The genotypes of BNP at the rs198389, rs6668352, and rs198388 loci in 339 patients with COPD (205 in the COPD/PH⁻ group and 134 in the COPD/PH⁺ group) and 125 healthy subjects were detected by PCR/Sanger sequencing. The serum levels of BNP, fibrinogen (Fbg), and Apelin were measured in all subjects by ELISA. Results: The BNP rs198389 locus G allele, rs6668352 locus A allele, and 198388 locus T allele were high risk factors for COPD (P<0.001). Logistics regression analysis showed that BNP rs198389 locus G allele, rs6668352 locus A allele, and rs198388 locus T allele were high risk factors for PH in COPD patients (all P<0.001). The levels of the serum BNP and Fbg protein in the control group, COPD/PH⁻ group, and COPD/PH⁺ group increased successively, and the expression levels of Apelin protein decreased successively (all P<0.001). The BNP and Fbg protein levels in the wild-type, heterozygote, and mutant homozygote in BNP rs198389, rs6668352, and rs198388 loci increased successively, and the serum Apelin protein levels decreased successively (all P<0.001). Conclusion: The polymorphisms of BNP at the rs198389, rs6668352, and rs198388 loci are associated with the occurrence of COPD and COPD with PH, and the occurrence may be related to the abnormal expression level of BNP, Fbg, and Apelin protein in the serum.

Possible involvement of acetylcholine-mediated inflammation in airway diseases

Inhaled bronchodilator treatment with a long acting muscarinic antagonist (LAMA) reduces symptoms and the risk of exacerbations in COPD and asthma. However, increasing evidence from cell culture and animal studies suggests that anti-muscarinic drugs could also possess anti-inflammatory effects. Recent studies have revealed that acetylcholine (ACh) can be synthesized and released from both neuronal and non-neuronal cells, and the released ACh can potentiate airway inflammation and remodeling in airway diseases. However, these anti-inflammatory effects of anti-muscarinic drugs have not yet been confirmed in COPD and asthma patients. This review will focus on recent findings about the possible involvement of ACh in airway inflammation and remodeling, and the anti-inflammatory effect of anti-muscarinic drugs in airway diseases. Clarifying the acetylcholine-mediated inflammation could provide insights into the mechanisms of airway diseases, which could lead to future therapeutic strategies for inhibiting the disease progression and exacerbations.