Non-neuronal cholinergic system contributes to corticosteroid resistance in chronic obstructive pulmonary disease patients

Activated non-neuronal cholinergic system correlates with non-type 2 inflammation and exacerbations in severe asthma

BACKGROUND

Non-neuronal cholinergic system (NNCS) contributes to various inflammatory airway diseases. However, the role of NNCS in severe asthma (SA) remains largely unexplored.

OBJECTIVE

To explore airway NNCS in SA.

METHODS

In this prospective cohort study based on the Australasian Severe Asthma Network in a real-world setting, patients with SA (n = 52) and non-SA (n = 104) underwent clinical assessment and sputum induction. The messenger RNA (mRNA) levels of NNCS components and proinflammatory cytokines in the sputum were detected using real-time quantitative polymerase chain reaction, and the concentrations of acetylcholine (Ach)-related metabolites were evaluated using liquid chromatography coupled with tandem mass spectrometry. Asthma exacerbations were prospectively investigated during the next 12 months. The association between NNCS and future asthma exacerbations was also analyzed.

RESULTS

Patients with SA were less controlled and had worse airway obstruction, a lower bronchodilator response, higher doses of inhaled corticosteroids, and more add-on treatments. The sputum mRNA levels of NNCS components, such as muscarinic receptors M1R-M5R, OCT3, VACHT, and ACHE; proinflammatory cytokines; and Ach concentration in the SA group were significantly higher than those in the non-SA group. Furthermore, most NNCS components positively correlated with non-type (T) 2 inflammatory profiles, such as sputum neutrophils, IL8, and IL1B. In addition, the mRNA levels of sputum M2R, M3R, M4R, M5R, and VACHT were independently associated with an increased risk of moderate-to-severe asthma exacerbations.

CONCLUSION

This study indicated that the NNCS was significantly activated in SA, leading to elevated Ach and was associated with clinical features, non-T2 inflammation, and future exacerbations of asthma, highlighting the potential role of the NNCS in the pathogenesis of SA.

CLINICAL TRIAL REGISTRATION

ChiCTR-OOC-16009529 (http://www.chictr.org.cn).

Alpha-7 Nicotinic Receptor Agonist Protects Mice Against Pulmonary Emphysema Induced by Elastase

Pulmonary emphysema is a primary component of chronic obstructive pulmonary disease (COPD), a life-threatening disorder characterized by lung inflammation and restricted airflow, primarily resulting from the destruction of small airways and alveolar walls. Cumulative evidence suggests that nicotinic receptors, especially the α7 subtype (α7nAChR), is required for anti-inflammatory cholinergic responses. We postulated that the stimulation of α7nAChR could offer therapeutic benefits in the context of pulmonary emphysema. To investigate this, we assessed the potential protective effects of PNU-282987, a selective α7nAChR agonist, using an experimental emphysema model. Male mice (C57BL/6) were submitted to a nasal instillation of porcine pancreatic elastase (PPE) (50 µl, 0.667 IU) to induce emphysema. Treatment with PNU-282987 (2.0 mg/kg, ip) was performed pre and post-emphysema induction by measuring anti-inflammatory effects (inflammatory cells, cytokines) as well as anti-remodeling and anti-oxidant effects. Elastase-induced emphysema led to an increase in the number of α7nAChR-positive cells in the lungs. Notably, both groups treated with PNU-282987 (prior to and following emphysema induction) exhibited a significant decrease in the number of α7nAChR-positive cells. Furthermore, both groups treated with PNU-282987 demonstrated decreased levels of macrophages, IL-6, IL-1β, collagen, and elastic fiber deposition. Additionally, both groups exhibited reduced STAT3 phosphorylation and lower levels of SOCS3. Of particular note, in the post-treated group, PNU-282987 successfully attenuated alveolar enlargement, decreased IL-17 and TNF-α levels, and reduced the recruitment of polymorphonuclear cells to the lung parenchyma. Significantly, it is worth noting that MLA, an antagonist of α7nAChR, counteracted the protective effects of PNU-282987 in relation to certain crucial inflammatory parameters. In summary, these findings unequivocally demonstrate the protective abilities of α7nAChR against elastase-induced emphysema, strongly supporting α7nAChR as a pivotal therapeutic target for ameliorating pulmonary emphysema.

Mechanisms underlying corticosteroid resistance in patients with asthma: a review of current knowledge

INTRODUCTION

Corticosteroids are the most cost-effective anti-inflammatory drugs available for the treatment of asthma. Despite their effectiveness, several asthmatic patients have corticosteroid resistance or insensitivity and exhibit a poor response. Corticosteroid insensitivity implies a poor prognosis due to challenges in finding alternative therapeutic options for asthma.

AREAS COVERED

In this review, we describe asthma phenotypes and endotypes, as well as their differential responsiveness to corticosteroids. In addition, we describe the mechanism of action of corticosteroids underlying their regulation of the expression of glucocorticoid receptors (GRs) and their anti-inflammatory effects. Furthermore, we summarize the mechanistic evidence underlying corticosteroid-insensitive asthma, which is mainly related to changes in GR gene expression, structure, and post-transcriptional modifications. Finally, various pharmacological strategies designed to reverse corticosteroid insensitivity are discussed.

EXPERT OPINION

Corticosteroid insensitivity is influenced by the asthma phenotype, endotype, and severity, and serves as an indication for biological therapy. The molecular mechanisms underlying corticosteroid-insensitive asthma have been used to develop targeted therapeutic strategies. However, the lack of clinical trials prevents the clinical application of these treatments.

The Role of the Acetylcholine System in Common Respiratory Diseases and COVID-19

As an indispensable component in human beings, the acetylcholine system regulates multiple physiological processes not only in neuronal tissues but also in nonneuronal tissues. However, since the concept of the "Nonneuronal cholinergic system (NNCS)" has been proposed, the role of the acetylcholine system in nonneuronal tissues has received increasing attention. A growing body of research shows that the acetylcholine system also participates in modulating inflammatory responses, regulating contraction and mucus secretion of respiratory tracts, and influencing the metastasis and invasion of lung cancer. In addition, the susceptibility and severity of respiratory tract infections caused by pathogens such as Mycobacterium Tuberculosis and the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can also correlate with the regulation of the acetylcholine system. In this review, we summarized the major roles of the acetylcholine system in respiratory diseases. Despite existing achievements in the field of the acetylcholine system, we hope that more in-depth investigations on this topic will be conducted to unearth more possible pharmaceutical applications for the treatment of diverse respiratory diseases.

The diversity of neuroimmune circuits controlling lung inflammation

It is becoming increasingly appreciated that the nervous and immune systems communicate bidirectionally to regulate immunological outcomes in a variety of organs including the lung. Activation of neuronal signaling can be induced by inflammation, tissue damage, or pathogens to evoke or reduce immune cell activation in what has been termed a neuroimmune reflex. In the periphery, these reflexes include the cholinergic anti-inflammatory pathway, sympathetic reflex, and sensory nociceptor-immune cell pathways. Continual advances in neuroimmunology in peripheral organ systems have fueled small-scale clinical trials that have yielded encouraging results for a range of immunopathologies such as rheumatoid arthritis. Despite these successes, several limitations should give clinical investigators pause in the application of neural stimulation as a therapeutic for lung inflammation, especially if inflammation arises from a novel pathogen. In this review, the general mechanisms of each reflex, the evidence for these circuits in the control of lung inflammation, and the key knowledge gaps in our understanding of these neuroimmune circuits will be discussed. These limitations can be overcome not only through a better understanding of neuroanatomy but also through a systematic evaluation of stimulation parameters using immune activation in lung tissues as primary readouts. Our rapidly evolving understanding of the nervous and immune systems highlights the importance of communication between these cells in health and disease. This integrative approach has tremendous potential in the development of targeted therapeutics if specific challenges can be overcome.

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.

The pan-JAK inhibitor LAS194046 reduces neutrophil activation from severe asthma and COPD patients in vitro

Non-T2 severe asthma and chronic obstructive pulmonary disease (COPD) are airway chronic inflammatory disorders with a poor response to corticosteroids. LAS194046, a novel pan-Janus kinase (JAK) inhibitor, shows inhibitory effects on T2 allergic lung inflammation in rats. In this work we analyze the effects of LAS194046, fluticasone propionate and their combination in neutrophils from non-T2 severe asthma and COPD patients in vitro. Neutrophils from 23 healthy subjects, 23 COPD and 21 non-T2 severe asthma patients were incubated with LAS194046 (0.01 nM–1 µM), fluticasone propionate (0.1 nM–1 µM) or their combination and stimulated with lipopolysaccharide (LPS 1 µM). LAS194046 shows similar maximal % inhibition and potency inhibiting IL-8, MMP-9 and superoxide anion release in neutrophils from healthy, COPD and asthma. Fluticasone propionate suppresses mediator release only in neutrophils from healthy patients. The combination of LAS194046 with fluticasone propionate shows synergistic anti-inflammatory and anti-oxidant effects. The mechanisms involved in the synergistic effects of this combination include the increase of MKP1 expression, decrease of PI3Kδ, the induction of glucocorticoid response element and the decrease of ERK1/2, P38 and JAK2/STAT3 phosphorylation compared with monotherapies. In summary, LAS194046 shows anti-inflammatory effects in neutrophils from COPD and severe non-T2 asthma patients and induces synergistic anti-inflammatory effects when combined with fluticasone propionate.

Retinoic acid attenuates nuclear factor kappaB mediated induction of NLRP3 inflammasome

BACKGROUND

Acetylcholine (ACh), a neurotransmitter and a part of the cholinergic system, can modify immune responses. Expression of acetylcholine receptors (AChR) in immune cells, including macrophages, leads to modulation of their function. Inflammasomes are part of the innate immune system and have been linked to a variety of inflammatory diseases. The NLRP3/ASC/caspase-1/IL-1 axis has emerged as a critical signaling pathway in inflammation process initiation. The role of ACh in modulating inflammasomes in macrophages remains relatively under-explored.

METHODS

The effect of AChR agonist carbachol on inflammasome expression was investigated using murine and human macrophages. Cell lysates were assessed by western blot for protein analysis. Immunofluorescence studies were used to study the translocation of p65. The experiments were conducted in the presence of NF-ĸB inhibitor, AChR antagonists, and retinoic acid (RA) to study the role of NF-ĸB, ACh receptors, and RA, respectively.

RESULTS

We found that carbachol increased the expression of NLRP3 inflammasome (NLRP3, ASC, cleaved caspase-1, IL-1β, and IL-18). The treated cells also showed an increase in NF-ĸB activation. The effect of carbachol was diminished by NF-ĸB inhibitor and atropine, a mAChR antagonist. The addition of RA also significantly reduced the effect of carbachol on NLRP3 inflammasomes.

CONCLUSIONS

Our current study suggests that carbachol induces NLRP3 inflammasome activation through mAChR and NF-ĸB, and that RA abolishes the inflammatory response. It reveals the potentials of co-administration of RA with cholinergic drugs to prevent inflammatory responses during cholinergic medications.

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

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.

Using Blood Eosinophil Count as a Biomarker to Guide Corticosteroid Treatment for Chronic Obstructive Pulmonary Disease

Treating patients hospitalised with acute exacerbations of chronic obstructive pulmonary disease (COPD) usually involves administering systemic corticosteroids. The many unwanted side effects associated with this treatment have led to increased interest in minimising the accumulated corticosteroid dose necessary to treat exacerbations. Studies have shown that short-term treatment with corticosteroids is preferred, and recent trials have shown that biomarkers can be used to further reduce exposure to corticosteroids. Interestingly, high eosinophil counts in patients with acute exacerbations of COPD are indicative of an eosinophilic phenotype with a distinct response to treatment with corticosteroids. In addition, post-hoc analysis of randomised control trials have shown that higher blood eosinophil counts at the start of the study predict a greater response to inhaled corticosteroids in stable COPD. In this review, we examine the studies on this topic, describe how blood eosinophil cell count may be used as a biomarker to guide treatment with corticosteroids, and identify some relevant challenges.

Determining Pharmacological Mechanisms of Chinese Incompatible Herbs Fuzi and Banxia in Chronic Obstructive Pulmonary Disease: A Systems Pharmacology-Based Study

Aconiti Lateralis Radix Praeparata (Fuzi) and Pinelliae Rhizoma (Banxia) are among the 18 incompatible medications that are forbidden from use in one formulation. However, there is increasing evidence implying that this prohibition is not entirely correct. According to the theory of Chinese traditional medicine, they can be used for the treatment of chronic obstructive pulmonary disease (COPD). Thus, we analyzed the possible approaches for the treatment of COPD using network pharmacology. The active compounds of Fuzi and Banxia (FB) were collected, and their targets were identified. COPD-related targets were obtained by analyzing the differentially expressed genes between COPD patients and healthy individuals, which were expressed using a Venn diagram of COPD and FB. Protein-protein interaction data and network regarding COPD and drugs used were obtained. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis were conducted. The gene-pathway network was constructed to screen the key target genes. In total, 34 active compounds and 47 targets of FB were identified; moreover, 7,153 differentially expressed genes were identified between COPD patients and healthy individuals. The functional annotations of target genes were found to be related to mechanisms such as transcription, cytosol, and protein binding; furthermore, 68 pathways including neuroactive ligand-receptor interaction, Kaposi sarcoma-associated herpesvirus infection, apoptosis, and measles were significantly enriched. FOS CASP3, VEGFA, ESR1, and PTGS2 were the core genes in the gene-pathway network of FB for the treatment of COPD. Our results indicated that the effect of FB against COPD may involve the regulation of immunological function through several specific biological processes and their corresponding pathways. This study demonstrates the application of network pharmacology in evaluating mechanisms of action and molecular targets of herb-opponents FB.

Pharmacological strategies to regain steroid sensitivity in severe asthma and COPD

Corticosteroid is the most widely used anti-inflammatory agent for asthma and chronic obstructive pulmonary disease (COPD). However, most of the severe asthmatics and COPD patients show poor response to the anti-inflammatory benefits of corticosteroids. Corticosteroid resistance is a major therapeutic challenge to the treatment of severe asthma and COPD. Cellular and molecular mechanisms underlying steroid insensitivity in severe asthma and COPD are still not fully understood. This review aims to recapitulate recent discoveries of potential contributing mechanisms of steroid resistance, and to appraise new therapeutic strategies shown to restore steroid sensitivity in experimental models of severe asthma and COPD, and in human clinical trials. It has been revealed that pro-inflammatory cytokines such as IFN-γ, TNF-α, TGF-β, IL-17A, IL-27, IL-33 and thymic stromal lymphopoietin (TSLP) may contribute to steroid resistance in severe asthma and COPD. These cytokines together with allergens, pathogens, and cigarette smoke can modulate multiple signaling pathways including PI3Kδ/Akt/mTOR, JAK1/2-STAT1/5, p38MAPK/JNK, Nrf2/HDAC2/c-Jun, heightened glucocorticoid receptor (GR)β/GRα ratio, and casein kinase 1 (CK1δ/ε)/cofilin 1, to induce steroid insensitivity. More recently, microRNAs such as miR-9, miR-21, and miR-126 have been implicated for corticosteroid insensitivity in asthma and COPD. Therapeutic strategies such as cytokine-specific biologics, signaling molecule-specific small molecule inhibitors, and microRNA-specific antagomir oligonucleotides are potentially promising approaches to reverse corticosteroid resistance. A panel of clinically effective drugs have shown promise in restoring steroid resistance in experimental models, and it is highly probable that some of these molecules can be successfully repositioned for the clinical use in COPD and severe asthma.

Modulation of the extraneuronal cholinergic system on main innate response leukocytes

The expression of elements of the cholinergic system has been demonstrated in non-neuronal cells, such as immune cells, where acetylcholine modulates innate and adaptive responses. However, the study of the non-neuronal cholinergic system has focused on lymphocyte cholinergic mechanisms, with less attention to its role of innate cells. Considering this background, the aims of this review are 1) to review information regarding the cholinergic components of innate immune system cells; 2) to discuss the effect of cholinergic stimuli on cell functions; 3) and to describe the importance of cholinergic stimuli on host immunocompetence, in order to set the base for the design of intervention strategies in the biomedical field.

In vitro anti-inflammatory effects of AZD8999, a novel bifunctional muscarinic acetylcholine receptor antagonist /β2-adrenoceptor agonist (MABA) compound in neutrophils from COPD patients

Recent evidence indicates that AZD8999 (LAS190792), a novel muscarinic acetylcholine receptor antagonist and β2-adrenoceptor agonist (MABA) in development for chronic respiratory diseases, induces potent and sustained relaxant effects in human bronchi by adressing both muscarinic acetylcholine receptors and β2-adrenoceptor. However, the anti-inflammatory effects of the AZD8999 monotherapy or in combination with corticosteroids are unknown. This study investigates the anti-inflammatory effects of AZD8999 in monotherapy and combined with fluticasone propionate in neutrophils from healthy and chronic obstructive pulmonary disease (COPD) patients. Peripheral blood neutrophils from healthy and COPD patients were incubated with AZD8999 and fluticasone propionate, individually or in combination, for 1h followed by lipopolysaccharide (LPS) stimulation for 6h. The IL-8, MMP9, IL-1β, and GM-CSF release was measured in cell culture supernatants. AZD8999 shows ~ 50% maximum inhibitory effect and similar potency inhibiting the released cytokines in neutrophils from healthy and COPD patients. However, while fluticasone propionate suppresses mediator release in neutrophils from healthy patients, COPD neutrophils are less sensitive. The combination of non-effective concentrations of AZD8999 (0.01nM) with non-effective concentrations of fluticasone propionate (0.1nM) shows synergistic anti-inflammatory effects. The studied mechanisms that may be involved in the synergistic anti-inflammatory effects of this combination include the increase of glucocorticoid receptor (GR)α and MKP1 expression, the induction of glucocorticoid response element (GRE) activation and the decrease of ERK1/2, P38 and GR-Ser226 phosphorylations compared with monotherapies. In summary, AZD8999 shows anti-inflammatory effects in neutrophils from COPD patients and induces synergistic anti-inflammatory effects when combined with fluticasone propionate, supporting the use of MABA/ICS combination therapy in COPD.

Mucin 1 deficiency mediates corticosteroid insensitivity in asthma

BACKGROUND

The loss of corticosteroid efficacy is an important issue in severe asthma management and may lead to poor asthma control and deterioration of airflow. Recent data indicate that Mucin 1 (MUC1) membrane mucin can mediate corticosteroid efficacy in chronic rhinosinusitis, but the role of MUC1 in uncontrolled severe asthma is unknown. The objective was to analyze the previously unexplored role of MUC1 on corticosteroid efficacy in asthma.

METHODS

Mucin 1 expression was evaluated by real-time PCR in human bronchial epithelial cells (HBEC) and blood neutrophils from uncontrolled severe asthma (n = 27), controlled mild asthma (n = 16), and healthy subjects (n = 13). IL-8, MMP9, and GM-CSF were measured by ELISA in HBEC and neutrophils. An asthma model of ovalbumin (OVA) was used in MUC1 KO and WT C57BL/6 mice according to ARRIVE guidelines.

RESULTS

Mucin 1-CT expression was downregulated in bronchial epithelial cells and peripheral blood neutrophils from severe asthma patients compared with mild asthma and healthy subjects (P < 0.05). Daily dose of inhaled corticosteroids (ICS) inversely correlated with MUC1 expression in neutrophils from mild and severe asthma (ρ = -0.71; P < 0.0001). Dexamethasone showed lower anti-inflammatory effects in severe asthma peripheral blood neutrophils and HBECs stimulated with lipopolysaccharide (LPS) than in cells from mild asthma. Glucocorticoid receptor (GR)-α phosphorylated at serine 226 was increased in cells from severe asthma, and the MUC1-CT/GRα complex was downregulated in severe asthma cells. OVA asthma model in MUC1 KO mice was resistant to the anti-inflammatory effects of dexamethasone.

CONCLUSION

Mucin 1-CT modulates corticosteroid efficacy in vitro and in vivo asthma models.

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.

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.

Effects of Glutathione S-Transferase Gene Polymorphisms and Antioxidant Capacity per Unit Albumin on the Pathogenesis of Chronic Obstructive Pulmonary Disease

OBJECTIVES

To study the effects of GSTM1, GSTT1 gene polymorphisms, and organism antioxidant capacity and related indicators such as antioxidant capacity per unit of albumin (AC/ALB) on chronic obstructive pulmonary disease (COPD).

METHODS

Using polymerase chain reaction technology, GSTM1 and GSTT1 gene polymorphisms were detected in 33 COPD patients and 33 healthy people. The total antioxidant capacity (TAC) found in serum was determined using the I₂/KI potentiometric, KMnO₄ microtitration, and H₂O₂ potentiometric methods. The AC/ALB was defined as the TAC divided by the serum albumin concentration. Logistic regression analysis was carried out with biochemical screening indices, which was found to be closely related with the incidence of COPD.

RESULTS

The GSTM1 and GSTT1 gene deletion rate in the COPD group was significantly higher than that in the control group (P < 0.05). The differences in serum TAC between the COPD and control groups, GSTM1 (+) and GSTM1 (-) groups, and GSTT1 (+) and GSTT1 (-) groups were statistically significant (P < 0.001). In addition, there was a significant difference in the AC/ALB between the COPD and control groups (P < 0.05). Logistic regression analysis showed that the incidence of COPD was closely related to the AC/ALB (P < 0.05).

CONCLUSIONS

GSTM1 and GSTT1 gene polymorphisms are closely correlated with the pathogenesis of COPD, while the AC/ALB plays a decisive role in the occurrence and development of COPD.

Is aclidinium alone or combined with a LABA a rational choice for symptomatic COPD patients?

BACKGROUND

As emphasized by international recommendations and largely confirmed by clinical experience, long-acting bronchodilators play a central role in the maintenance treatment of chronic obstructive pulmonary disease (COPD) due to their proven efficacy in reducing airflow obstruction and improving symptoms.

MAIN BODY

There are some important aspects to define with regard to inhalation therapy for COPD, particularly those concerning the selection criteria and the optimal use of long-acting bronchodilators. First of all, it needs to be determined in which patients and clinical situations monotherapy with one bronchodilator, such as a long-acting muscarinic antagonist (LAMA), should be considered adequate, and in which cases the use of combination therapies, such as the "double bronchodilation" with a LAMA and a long-acting β2-agonist (LABA), should be preferred. Another critical issue concerns the effect of the frequency of daily administration of inhaled agents on the control of symptoms during the 24 h. COPD symptoms are known to exhibit considerable circadian variability with worsening in the early morning, and a significant proportion of patients have disease-related sleep disorders which can adversely affect their quality of life. The worsening of symptoms in the early morning may be due, at least in part, to a reduction in airway caliber caused by an increased "cholinergic tone" at night. As such, the coverage of nighttime and early morning symptoms is a reasonable therapeutic goal, which can be achieved by many patients using LAMAs such as aclidinium bromide twice daily (BID). Therapeutic adherence is known to be a multifactorial phenomenon that is frequently affected by other aspects than dosing frequency, including the technical features and ease of use of the inhalers. To this end, it should be mentioned that certain new-generation inhalers such as Genuair® have been associated in clinical trials with higher patient preference.

CONCLUSION

In this work, in addition to presenting an overview of the main evidence on the efficacy of COPD treatment with the LAMA aclidinium bromide BID, we suggest some selection criteria for the monotherapy with one long-acting bronchodilator or the combination therapy with LAMA and LABA in COPD patients, with particular reference to specific clinical scenarios.