Increased levels of Th17 cells are associated with non-neuronal acetylcholine in COPD patients

Th17/Treg Imbalance: Implications in Lung Inflammatory Diseases

Regulatory T cells (Tregs) and T helper 17 cells (Th17) are two CD4⁺ T cell subsets with antagonist effects. Th17 cells promote inflammation, whereas Tregs are crucial in maintaining immune homeostasis. Recent studies suggest that Th17 cells and Treg cells are the foremost players in several inflammatory diseases. In this review, we explore the present knowledge on the role of Th17 cells and Treg cells, focusing on lung inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), sarcoidosis, asthma, and pulmonary infectious diseases.

Caveolin-1 Promotes the Imbalance of Th17/Treg in Chronic Obstructive Pulmonary Disease by Regulating Hsp70 Expression

Objective

To investigate whether the expression of Hsp70 is associated with Cav-1 in promoting the imbalance of Th17/Treg cells in COPD.

Methods

The plasma Cav-1, Hsp70 expression were quantified by enzyme-linked immunosorbent assay (ELISA). The frequencies of circulating Th17, Treg cells and Th17/Treg ratio were determined by flow cytometry. Peripheral blood mononuclear cells (PBMCs) from subjects were transfected with Cav-1 or control plasmids and Hsp70 plasmid.

Results

We found that Cav-1 expression was lower but the levels of Hsp70 and Th17 cells were higher in COPD than in healthy control (HC). Hsp70 expressions were positively correlated with Cav-1 levels, Th17 cells, and Th17/Treg ratio in COPD but not in HC. Cav-1 over-expression resulted in an increase in Hsp70 and Th17 levels. Suppressing Hsp70 expressing by small interfering RNA (siRNA), the decline of Th17 frequency was observed in Cav-1-overexpressed PBMCs.

Conclusion

Collectively, our results illuminate that Cav-1 contributes to the imbalance of Th17/Treg through potentially regulating Hsp70 expression.

Th17/Treg Imbalance in Chronic Obstructive Pulmonary Disease: Clinical and Experimental Evidence

The imbalance between pro- and anti-inflammatory immune responses mediated by Th17 and Treg cells is deeply involved in the development and progression of inflammation in chronic obstructive pulmonary disease (COPD). Several clinical and experimental studies have described the Th17/Treg imbalance in COPD progression. Due to its importance, many studies have also evaluated the effect of different treatments targeting Th17/Treg cells. However, discrepant results have been observed among different lung compartments, different COPD stages or local and systemic markers. Thus, the data must be carefully examined. In this context, this review explores and summarizes the recent outcomes of Th17/Treg imbalance in COPD development and progression in clinical, experimental and in vitro studies.

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.

Regulatory T Cells in Respiratory Health and Diseases

Respiratory diseases compromise the health of millions of people all over the world and are strongly linked to the immune dysfunction. CD4+FOXP3+ T regulatory cells, also known as Tregs, have a central role maintaining tissue homeostasis during immune responses. Their activity and clinical impact have been widely studied in different clinical conditions including autoimmune diseases, inflammatory conditions, and cancer, amongst others. Tregs express transcription factor forkhead box P3 (FOXP3), which allows regulation of the immune response through anti-inflammatory cytokines such as IL-10 or transforming growth factor beta (TGF-β) and direct cell-to-cell interaction. Maintenance of immune tolerance is achieved via modulation of effector CD4+ T helper 1, 2 or 17 (Th1, Th2, Th17) cells by Tregs. This review highlights the recent progress in the understanding of Tregs in different disorders of the respiratory system.

Cholinergic signalling mechanisms and early implant healing phases in healthy versus generalized aggressive periodontitis patients: A prospective, case-control study

AIMS

Periodontal diseases negatively affect implant osseointegration. Perturbations in non-neuronal cholinergic signalling mechanisms are associated with periodontitis; however, their role in generalized aggressive periodontitis (GAgP) is unknown. The aim of this prospective case-control study was to determine the relationship between non-neuronal cholinergic signalling mechanisms, secreted Ly-6/uPAR-related protein-1 (SLURP-1), interleukin-17 (IL-17) family cytokines and healing of dental implants in health and GAgP.

MATERIAL AND METHODS

Thirteen GAgP patients and seven periodontally healthy individuals (PH) were recruited. Peri-implant crevicular fluid (PICF) was obtained at baseline and 1 month post-placement. Acetylcholine (ACh) levels and cholinesterase activity were determined biochemically. SLURP-1, IL-17A and IL-17E levels were determined by ELISA. Marginal bone loss (MBL) at 1 and 6 months post-placement was determined radiographically.

RESULTS

The concentration of ACh, cholinesterase activity and IL-17A levels was elevated in PICF of patients with GAgP compared to PH individuals at baseline and 1 month post-placement. The concentration of ACh and cholinesterase activity levels in PICF correlated with levels of IL-17A and MBL around implants 1 month post-placement in patients with GAgP.

CONCLUSIONS

Non-neuronal cholinergic mechanisms may play a role in the aetiopathogenesis of GAgP and may directly or indirectly, through modulation of IL-17A, influence early implant osseointegration and potential long-term implant survival.

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.

Acetylcholine-treated murine dendritic cells promote inflammatory lung injury

In recent years a non-neuronal cholinergic system has been described in immune cells, which is often usually activated during the course of inflammatory processes. To date, it is known that Acetylcholine (ACh), a neurotransmitter extensively expressed in the airways, not only induces bronchoconstriction, but also promotes a set of changes usually associated with the induction of allergic/Th2 responses. We have previously demonstrated that ACh polarizes human dendritic cells (DC) toward a Th2-promoting profile through the activation of muscarinic acetylcholine receptors (mAChR). Here, we showed that ACh promotes the acquisition of an inflammatory profile by murine DC, with the increased MHC II IA^d expression and production of two cytokines strongly associated with inflammatory infiltrate and tissue damage, namely TNF-α and MCP-1, which was prevented by blocking mAChR. Moreover, we showed that ACh induces the up-regulation of M3 mAChR expression and the blocking of this receptor with tiotropium bromide prevents the increase of MHC II IAd expression and TNF-α production induced by ACh on DC, suggesting that M3 is the main receptor involved in ACh-induced activation of DC. Then, using a short-term experimental murine model of ovalbumin-induced lung inflammation, we revealed that the intranasal administration of ACh-treated DC, at early stages of the inflammatory response, might be able to exacerbate the recruitment of inflammatory mononuclear cells, promoting profound structural changes in the lung parenchyma characteristic of chronic inflammation and evidenced by elevated systemic levels of inflammatory marker, TNF-α. These results suggest a potential role for ACh in the modulation of immune mechanisms underlying pulmonary inflammatory processes.

Th17/Treg immunoregulation and implications in treatment of sulfur mustard gas-induced lung diseases

INTRODUCTION

Sulfur mustard (SM) is an extremely toxic gas used in chemical warfare to cause massive lung injury and death. Victims exposed to SM gas acutely present with inhalational lung injury, but among those who survive, some develop obstructive airway diseases referred to as SM-lung syndrome. Pathophysiologically, SM-lung shares many characteristics with smoking-induced chronic obstructive pulmonary disease (COPD), including airway remodeling, goblet cell metaplasia, and obstructive ventilation defect. Some of the hallmarks of COPD pathogenesis, which include dysregulated lung inflammation, neutrophilia, recruitment of interleukin 17A (IL -17A) expressing CD4⁺T cells (Th17), and the paucity of lung regulatory T cells (Tregs), have also been described in SM-lung. Areas covered: A literature search was performed using the MEDLINE, EMBASE, and Web of Science databases inclusive of all literature prior to and including May 2017. Expert commentary: Here we review some of the recent findings that suggest a role for Th17 cell-mediated inflammatory changes associated with pulmonary complications in SM-lung and suggest new therapeutic approaches that could potentially alter disease progression with immune modulating biologics that can restore the lung Th17/Treg balance.

Bifunctional Drugs for the Treatment of Respiratory Diseases

Over the last decade, there has been a steady increase in the use of fixed dose combinations for the treatment of a range of diseases, including cancer, AIDS, tuberculosis and other infectious diseases. It is now evident that patients with asthma or chronic obstructive pulmonary disease (COPD) can also benefit from the use of fixed dose combinations, including combinations of a long-acting β₂-agonist (LABA) and an inhaled corticosteroid (ICS), and combinations of LABAs and long-acting muscarinic receptor antagonists (LAMAs). There are now also "triple inhaler" fixed dose combinations (containing a LABA, LAMA and ICS) under development and already being made available in clinical practice, with the first such triple combination having been approved in India. The use of combinations containing drugs with complementary pharmacological actions in the treatment of patients with asthma or COPD has led to the discovery and development of drugs having two different primary pharmacological actions in the same molecule that we have called "bifunctional drugs". In this review we have discussed the state of the art of bifunctional drugs that can be categorized as bifunctional bronchodilators, bifunctional bronchodilator/anti-inflammatory drugs, bifunctional anti-inflammatory drugs and bifunctional mucolytic and anti-inflammatory drugs.

Intracellular interactions of umeclidinium and vilanterol in human airway smooth muscle

Background

Intracellular mechanisms of action of umeclidinium (UMEC), a long-acting muscarinic receptor antagonist, and vilanterol (VI), a long-acting β₂-adrenoceptor (β₂R) agonist, were investigated in target cells: human airway smooth-muscle cells (ASMCs).

Materials and methods

ASMCs from tracheas of healthy lung-transplant donors were treated with VI, UMEC, UMEC and VI combined, or control compounds (salmeterol, propranolol, ICI 118.551, or methacholine [MCh]). Cyclic adenosine monophosphate (cAMP) was measured using an enzyme-linked immunosorbent assay, intracellular free calcium ([Ca²⁺]_i) using a fluorescence assay, and regulator of G-protein signaling 2 (RGS2) messenger RNA using real-time quantitative polymerase chain reaction.

Results

VI and salmeterol (10⁻¹²–10⁻⁶ M) induced cAMP production from ASMCs in a concentration-dependent manner, which was greater for VI at all concentrations. β₂R antagonism by propranolol or ICI 118.551 (10⁻¹²–10⁻⁴ M) resulted in concentration-dependent inhibition of VI-induced cAMP production, and ICI 118.551 was more potent. MCh (5×10⁻⁶ M, 30 minutes) attenuated VI-induced cAMP production (P<0.05), whereas pretreatment with UMEC (10⁻⁸ M, 1 hour) restored the magnitude of VI-induced cAMP production. ASMC stimulation with MCh (10⁻¹¹–5×10⁻⁶ M) resulted in a concentration-dependent increase in [Ca²⁺]_i, which was attenuated with UMEC pretreatment. Reduction of MCh-induced [Ca²⁺]_i release was greater with UMEC + VI versus UMEC. UMEC enhanced VI-induced RGS2 messenger RNA expression.

Conclusion

These data indicate that UMEC reverses cholinergic inhibition of VI-induced cAMP production, and is a more potent muscarinic receptor antagonist when in combination with VI versus either alone.

Cigarette smoking increases bronchial mucosal IL-17A expression in asthmatics, which acts in concert with environmental aeroallergens to engender neutrophilic inflammation

BACKGROUND

Mild asthmatics who smoke cigarettes may develop unstable disease and neutrophilic infiltration of the airways, features more usually associated with severe asthmatic disease. The mechanisms giving rise to this response remain unclear.

OBJECTIVE

To address the hypothesis that smoking increases bronchial mucosal production of IL-17A which acts on bronchial epithelial cells directly and in concert with other environmental stimuli to induce the production of IL-6 and neutrophil chemotaxins.

METHODS

IL-17A, IL-8, IL-6, neutrophils and eosinophils were detected and quantified by immunohistochemistry in endobronchial biopsy sections from smoking and non-smoking asthmatics. Human tracheal epithelial cells (HTEpC) were cultured with IL-17A in the presence/absence of cigarette smoke extract (CSE) and aeroallergens lacking intrinsic protease activity, and IL-6 and IL-8 production measured in vitro.

RESULTS

Expression of IL-17A, IL-6 and IL-8 and neutrophil numbers was significantly elevated in the bronchial mucosa of the asthmatic smokers compared to the non-smokers. Expression of IL-17A correlated with that of IL-8 and neutrophil numbers. In the smoking asthmatics, eosinophil numbers also correlated with expression of IL-8 and IL-17A. Exposure of HTEpC cells to both CSE and IL-17A increased expression of IL-6 and IL-8 in a concentration-dependent and synergistic manner. Co-stimulation with CSE, IL-17A and aeroallergens further increased IL-6 and IL-8 production synergistically.

CONCLUSIONS

The data support the hypothesis that asthmatic smokers develop neutrophilic inflammation of the airways propagated at least partly by smoke-induced production of IL-17A which together with smoke and other environmental stimuli acts on airways epithelial cells to induce neutrophil chemotaxins.

TGF-β/BAMBI pathway dysfunction contributes to peripheral Th17/Treg imbalance in chronic obstructive pulmonary disease

BMP and activin membrane-bound inhibitor (BAMBI) is postulated to inhibit or modulate transforming growth factor β (TGF-β) signaling. Furthermore, strong upregulation of BAMBI expression following in vitro infection of chronic obstructive pulmonary disease (COPD) lung tissue has been demonstrated. In this study, we investigated whether TGF-β/BAMBI pathway is associated with COPD. Blood samples were obtained from 27 healthy controls (HC), 24 healthy smokers (HS) and 29 COPD patients. Elevated Th17/Treg ratios, and increased levels of BAMBI protein and mRNA (in plasma and CD4(+) T cells respectively), were observed in COPD compared with HC and HS. BAMBI expression was first observed on human CD4(+) T cells, with a typical membrane-bound pattern. The enhanced plasma BAMBI levels in COPD positively correlated with the increased plasma TGF-β1 levels and Th17/Treg ratio. Together, an impaired TGF-β/BAMBI pathway may promote the inflammation leading to Th17/Treg imbalance, which is a new mechanism in smokers who develop COPD.

COPD immunopathology

The immunopathology of chronic obstructive pulmonary disease (COPD) is based on the innate and adaptive inflammatory immune responses to the chronic inhalation of cigarette smoking. In the last quarter of the century, the analysis of specimens obtained from the lower airways of COPD patients compared with those from a control group of age-matched smokers with normal lung function has provided novel insights on the potential pathogenetic role of the different cells of the innate and acquired immune responses and their pro/anti-inflammatory mediators and intracellular signalling pathways, contributing to a better knowledge of the immunopathology of COPD both during its stable phase and during its exacerbations. This also has provided a scientific rationale for new drugs discovery and targeting to the lower airways. This review summarises and discusses the immunopathology of COPD patients, of different severity, compared with control smokers with normal lung function.

Autocrine Acetylcholine, Induced by IL-17A via NFκB and ERK1/2 Pathway Activation, Promotes MUC5AC and IL-8 Synthesis in Bronchial Epithelial Cells

IL-17A is overexpressed in the lung during acute neutrophilic inflammation. Acetylcholine (ACh) increases IL-8 and Muc5AC production in airway epithelial cells. We aimed to characterize the involvement of nonneuronal components of cholinergic system on IL-8 and Muc5AC production in bronchial epithelial cells stimulated with IL-17A. Bronchial epithelial cells were stimulated with recombinant human IL-17A (rhIL-17A) to evaluate the ChAT expression, the ACh binding and production, the IL-8 release, and the Muc5AC production. Furthermore, the effectiveness of PD098,059 (inhibitor of MAPKK activation), Bay11-7082 (inhibitor of IkBα phosphorylation), Hemicholinium-3 (HCh-3) (choline uptake blocker), and Tiotropium bromide (Spiriva®) (anticholinergic drug) was tested in our in vitro model. We showed that rhIL-17A increased the expression of ChAT, the levels of ACh binding and production, and the IL-8 and Muc5AC production in stimulated bronchial epithelial cells compared with untreated cells. The pretreatment of the cells with PD098,059 and Bay11-7082 decreased the ChAT expression and the ACh production/binding, while HCh-3 and Tiotropium decreased the IL-8 and Muc5AC synthesis in bronchial epithelial cells stimulated with rhIL-17A. IL-17A is involved in the IL-8 and Muc5AC production promoting, via NFκB and ERK1/2 pathway activation, the synthesis of ChAT, and the related activity of autocrine ACh in bronchial epithelial cells.

CD4(+)CD25(high)CD127(-) regulatory T-cells in COPD: smoke and drugs effect

Background

Chronic obstructive pulmonary disease (COPD) is a progressive lung disorder characterized by poorly reversible airway obstruction and its pathogenesis remains largely misunderstood. Local changes of regulatory T-cell populations in the lungs of COPD patients have been demonstrated although data concerning their pathologic role are contrasting. The aim of our study was to evaluate the relative percentage of regulatory T-cells in the peripheral blood of current and former smoker subjects, affected or not by COPD. Furthermore, the effect of different concentrations of budesonide and formoterol, on regulatory T-cells has been investigated.

Methods

T regulatory lymphocytes were isolated and assessed as CD4⁺CD25^highCD127^- cells by flow cytometry and cultured for 48 hours in the absence or in the presence of budesonide and/or formoterol at different doses.

Results

CD4⁺CD25^highCD127^- regulatory T-cells percentage was significantly reduced in COPD patients, both current and former smokers, with respect to volunteers. Furthermore, CD4⁺CD25^highCD127^- cells of COPD patients showed a not statistically significant response to drugs compared to healthy subjects.

Discussion

Our results evidenced a different behaviour of CD4⁺CD25^highCD127^- Treg cells in COPD patients after in vitro treatments.

Conclusions

Based on our data, we suggested a possible role of CD4 CD25^highCD127 T-cells in COPD pathogenesis.

Positioning new pharmacotherapies for COPD

COPD imposes considerable worldwide burden in terms of morbidity and mortality. In recognition of this, there is now extensive focus on early diagnosis, secondary prevention, and optimizing medical management of the disease. While established guidelines recognize different grades of disease severity and offer a structured basis for disease management based on symptoms and risk, it is becoming increasingly evident that COPD is a condition characterized by many phenotypes and its control in a single patient may require clinicians to have access to a broader spectrum of pharmacotherapies. This review summarizes recent developments in COPD management and compares established pharmacotherapy with new and emerging pharmacotherapies including long-acting muscarinic antagonists, long-acting β-2 sympathomimetic agonists, and fixed-dose combinations of long-acting muscarinic antagonists and long-acting β-2 sympathomimetic agonists as well as inhaled cortiocosteroids, phosphodiesterase inhibitors, and targeted anti-inflammatory drugs. We also review the available oral medications and new agents with novel mechanisms of action in early stages of development. With several new pharmacological agents intended for the management of COPD, it is our goal to familiarize potential prescribers with evidence relating to the efficacy and safety of new medications and to suggest circumstances in which these therapies could be most useful.

Targeted lung denervation for moderate to severe COPD: a pilot study

BACKGROUND

Parasympathetic pulmonary nerves release acetylcholine that induces smooth muscle constriction. Disruption of parasympathetic pulmonary nerves improves lung function and COPD symptoms.

AIMS

To evaluate 'targeted lung denervation' (TLD), a novel bronchoscopic therapy based on ablation of parasympathetic pulmonary nerves surrounding the main bronchi, as a potential therapy for COPD.

METHODS

This 1-year, prospective, multicentre study evaluated TLD in patients with COPD forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) (FEV1/FVC <0.70; FEV1 30%-60% predicted). Patients underwent staged TLD at 20 watts (W) or 15 W following baseline assessment off bronchodilators. Assessments were repeated on tiotropium before treatment and off bronchodilators at 30, 90, 180, 270 and 365 days after TLD. The primary endpoint was freedom from documented and sustained worsening of COPD directly attributable to TLD to 1 year. Secondary endpoints included technical feasibility, change in pulmonary function, exercise capacity, and quality of life.

RESULTS

Twenty-two patients were included (n=12 at 20 W, n=10 at 15 W). The procedures were technically feasible 93% of the time. Primary safety endpoint was achieved in 95%. Asymptomatic bronchial wall effects were observed in 3 patients at 20 W. The clinical safety profiles were similar between the two energy doses. At 1 year, changes from baseline in the 20 W dose compared to the 15 W dose were: FEV1 (+11.6%±32.3 vs +0.02%±15.1, p=0.324), submaximal cycle endurance (+6.8 min±12.8 vs 2.6 min±8.7, p=0.277), and St George's Respiratory Questionnaire (-11.1 points ±9.1 vs -0.9 points ±8.6, p=0.044).

CONCLUSIONS

Bronchoscopic TLD, based on the concept of ablating parasympathetic pulmonary nerves, was feasible, safe, and well tolerated. Further investigation of this novel therapy is warranted.

TRIAL REGISTRATION NUMBER

NCT01483534.

IL-33/ST2 axis controls Th2/IL-31 and Th17 immune response in allergic airway diseases

IL-33 targeting ST2 receptor (T1/ST2), expressed on Th2 cell surface, regulates the production of cytokines like IL-17A and IL-31. We studied the role of IL-33/ST2 axis in IL-31 and IL-17A production in patients with allergic rhinitis (AR) and with concomitant allergic asthma and rhinitis (AAR). 20 healthy control subjects (HC), 14 AR and 17 AAR subjects were recruited and blood samples collected. IL-33, soluble ST2 (sST2), IL-17A and IL-31 plasma concentrations were measured by ELISA method. T1/ST2, IL-31 and IL-17A cellular expression were studied in peripheral blood mononuclear cells (PBMC) from HC, AR and AAR (n=6 for each group) by flow-cytometry. In vitro, we also evaluated the effect of beclomethasone dipropionate (BDP) on T1/ST2, IL-31 and IL-17A expression in CD3(+)T-cells from PBMC of AAR (n=6). Plasma levels of IL-33, IL-31 and IL-17A were significantly higher and sST2 was lower in patients with AR and AAR than in HC. IL-31 and IL-17A intracellular levels significantly increased, whereas T1/ST2 expression was significantly lower, in CD3(+)T-cells from AR and AAR compared to HC. Positive correlations were observed between plasmatic components of IL-33/ST2 axis and IL-31 in both AR and AAR and IL-17A in AAR. In vitro IL-31 and IL-17A intracellular levels decreased after BDP treatment, whereas T1/ST2 expression increased in cultured CD3(+)T-cells obtained from AAR. IL-33/ST2 axis is involved in Th2/IL-31 and Th17 immune response during the progression of allergic airway disease. In vitro BDP is able to control Th2/IL-31 and Th17 immune response in PBMC from allergic patients.

Molecular pathogenesis of cigarette smoking-induced stable COPD

Inflammation is a central feature of stable chronic obstructive pulmonary disease (COPD) and involves both activation of structural cells of the airways and the lungs and the activation and/or recruitment of infiltrating inflammatory cells. This results in enhanced expression of many pro-inflammatory proteins and reduced expression of some anti-inflammatory mediators. An altered protein expression is generally associated with concomitant changes in gene expression profiles in a cell-specific manner. Increased understanding of the role of transcription factors and of the signaling pathways leading to their activation in stable COPD will provide new targets to enable the development of potential anti-inflammatory drugs. Several new compounds targeting these pathways and/or transcription factors are now in development for the treatment of stable COPD. Furthermore, glucocorticoids drugs already in clinical use act through their own transcription factor, the glucocorticoid receptor, to control the expression of inflammatory and anti-inflammatory genes.

Cigarette smoking promotes inflammation in patients with COPD by affecting the polarization and survival of Th/Tregs through up-regulation of muscarinic receptor 3 and 5 expression

Background

CD4⁺ T cells in the lung are involved in the pathogenesis of chronic obstructive pulmonary disease (COPD), although CD4⁺ T cell subsets and the direct effect of smoking on these cells, especially the expression of MRs, have not been comprehensively examined.

Methods

First, circulating CD4⁺ T cell subsets in healthy nonsmokers, patients with SCOPD and patients with AECOPD were evaluated by flow cytometry. Then, differentiation experiments were carried out using RT-PCR, and Ki-67/Annexin V antibodies were used to measure proliferation and apoptosis. We also explored the impact of CSE on the differentiation and survival of CD4⁺Th/Tregs and examined the expression of MRs in healthy nonsmokers and patients with SCOPD.

Results

We found the percentages of circulating Th1 and Th17 cells were increased in patients with AECOPD, while the percentage of Th2 cells was decreased in patients with SCOPD. The percentages of Th10 cells were decreased in both patients with SCOPD and patients with AECOPD, while the percentages of Tregs were increased. In addition, the percentages of CD4⁺α-7⁺ T cells were decreased in patients with SCOPD and patients with AECOPD. However, only the decrease observed in patients with AECOPD was significant. In vitro studies also revealed MR expression affected the polarization of T cells, with different CD4⁺ T cell subtypes acquiring different MR expression profiles. The addition of CSE facilitated CD4⁺ T cell polarization towards pro-inflammatory subsets (Th1 and Th17) and affected the survival of CD4⁺ T cells and Treg cells by up-regulating the expression of MR3 and 5, resulting in an imbalance of CD4⁺ T cell subsets.

Conclusions

Our findings suggest an imbalance of circulating CD4⁺ T cell subsets is involved in COPD pathogenesis in smokers. Cigarette smoking may contribute to this imbalance by affecting the polarization and survival of Th/Tregs through the up-regulation of MR3 and MR5.

Impaired function of regulatory T-cells in patients with chronic obstructive pulmonary disease (COPD)

Anti-inflammatory pathways affecting chronic obstructive pulmonary disease (COPD) are poorly understood. Regulatory T-cells (Tregs) are important negative regulators of T-cell activity and hence were investigated in COPD patients in this study. We hypothesised that functional defects in Tregs may promote increased inflammation contributing to the pathogenesis of COPD. Peripheral blood mononuclear cells (PBMC) were isolated from patients with stable COPD and age-matched non-smoking controls. Treg-mediated suppression of memory non-Treg (Foxp3(-)CD45RO(+)) CD4(+) T-cell activation was analysed by comparing PBMC responses to staphylococcal enterotoxin-B (SEB) pre- and post-depletion of Tregs (CD25(+)CD127(low)CD4(+) T-cells) by fluorescence-activated cell sorting (FACS). Activation of T-cells was assessed by HLA-DR expression. Levels of secreted cytokines were measured by ELISA. Depletion of Tregs increased SEB-induced activation of Foxp3(-)CD45RO(+) CD4(+) T-cells in samples from 15/15 healthy controls (demonstrating Treg-mediated suppression) and 9/14 COPD patients (Fisher's test, p=0.017). A screen of clinical data associated a failure of Treg-mediated suppression in the remaining five COPD patients with a higher body mass index (BMI) (33-38 kg/m(2)) compared to patients with unimpaired Treg function (20-32 kg/m(2)). In conclusion, we demonstrate impaired Treg-mediated suppression of CD4(+) T-cell activation in a subset of COPD patients, all of whom had high BMI. Obesity and/or perturbed homeostasis of Treg subsets may explain this defect and therefore contribute to increased inflammation observed in COPD.