Similarities and differences in inflammatory mechanisms of asthma and COPD

Cellular probing using phytoceuticals encapsulated advanced delivery systems in ameliorating lung diseases: Current trends and future prospects

Chronic respiratory diseases such as Chronic Obstructive Pulmonary Disease (COPD) and asthma have posed a significant healthcare and economic cost over a prolonged duration worldwide. At present, available treatments are limited to a range of preventive medicines, such as mono- or multiple-drug therapy, which necessitates daily use and are not considered as viable treatments to reverse the inflammatory processes of airway remodelling which is inclusive of the alteration of intra and extracellular matrix of the airway tract, death of epithelial cells, the increase in smooth muscle cell and the activation of fibroblasts. Hence, with the problem in mind a considerable body of study has been dedicated to comprehending the underlying factors that contribute to inflammation within the framework of these disorders. Hence, adequate literature that has unveiled the necessary cellular probing to reduce inflammation in the respiratory tract by improving the selectivity and precision of a novel treatment. However, through cellular probing cellular mechanisms such as the downregulation of various markers, interleukin 8, (IL-8), Interleukin 6 (IL-6), interleukin 1β (IL-1β) and tumor necrosis factor-α (TNF-α) have been uncovered. Hence, to target such cellular probes implementation of phytoceuticals encapsulated in an advanced drug delivery system has shown potential to be a solution with in vitro and in vivo studies highlighting their anti-inflammatory and antioxidant effects. However, the high costs associated with advanced drug delivery systems and the limited literature focused exclusively on nanoparticles pose significant challenges. Additionally, the biochemical characteristics of phytoceuticals due to poor solubility, limited bioavailability, and difficulties in mass production makes it difficult to implement this product as a treatment for COPD and asthma. This study aims to examine the integration of many critical features in the context of their application for the treatment of chronic inflammation in respiratory disorders.

Inhaled RNA drugs to treat lung diseases: Disease-related cells and nano-bio interactions

In recent years, RNA-based therapies have gained much attention as biomedicines due to their remarkable therapeutic effects with high specificity and potency. Lung diseases offer a variety of currently undruggable but attractive targets that could potentially be treated with RNA drugs. Inhaled RNA drugs for the treatment of lung diseases, including asthma, chronic obstructive pulmonary disease, cystic fibrosis, and acute respiratory distress syndrome, have attracted more and more attention. A variety of novel nanoformulations have been designed and attempted for the delivery of RNA drugs to the lung via inhalation. However, the delivery of RNA drugs via inhalation poses several challenges. It includes protection of the stability of RNA molecules, overcoming biological barriers such as mucus and cell membrane to the delivery of RNA molecules to the targeted cytoplasm, escaping endosomal entrapment, and circumventing unwanted immune response etc. To address these challenges, ongoing researches focus on developing innovative nanoparticles to enhance the stability of RNA molecules, improve cellular targeting, enhance cellular uptake and endosomal escape to achieve precise delivery of RNA drugs to the intended lung cells while avoiding unwanted nano-bio interactions and off-target effects. The present review first addresses the pathologic hallmarks of different lung diseases, disease-related cell types in the lung, and promising therapeutic targets in these lung cells. Subsequently we highlight the importance of the nano-bio interactions in the lung that need to be addressed to realize disease-related cell-specific delivery of inhaled RNA drugs. This is followed by a review on the physical and chemical characteristics of inhaled nanoformulations that influence the nano-bio interactions with a focus on surface functionalization. Finally, the challenges in the development of inhaled nanomedicines and some key aspects that need to be considered in the development of future inhaled RNA drugs are discussed.

Eotaxin-1/CCL11 promotes cellular senescence in human-derived fibroblasts through pro-oxidant and pro-inflammatory pathways

Introduction

Eotaxin-1/CCL11 is a pivotal chemokine crucial for eosinophil homing to the lungs of asthmatic patients. Recent studies also suggest that CCL11 is involved in the aging process, as it is upregulated in elderly, and correlated with shorter telomere length in leukocytes from asthmatic children. Despite its potential pro-aging effects, the precise contribution of CCL11 and the underlying mechanisms involved in the promotion of cellular senescence remains unclear. Therefore, the primary goal of this study was to explore the role of CCL11 on senescence development and the signaling pathways activated by this chemokine in lung fibroblasts.

Methods

To investigate the targets potentially modulated by CCL11, we performed an in silico analysis using PseudoCell. We validated in vitro the activation of these targets in the human lung fibroblast cell line MRC-5 following rhCCL11 exposure. Finally, we performed differential gene expression analysis in human airway epithelial cells of asthmatic patients to assess CCL11 signaling and activation of additional senescent markers.

Results

Our study revealed that eotaxin-1/CCL11 promote reactive oxygen secretion (ROS) production in lung fibroblasts, accompanied by increased activation of the DNA damage response (DDR) and p-TP53 and γH2AX. These modifications were accompanied by cellular senescence promotion and increased secretion of senescence-associated secretory phenotype inflammatory cytokines IL-6 and IL-8. Furthermore, our data show that airway epithelial lung cells from atopic asthmatic patients overexpress CCL11 along with aging markers such as CDKN2A (p16INK4a) and SERPINE1.

Discussion

These findings provide new insights into the mechanisms underlying the pro-aging effects of CCL11 in the lungs of asthmatic patients. Understanding the role of CCL11 on senescence development may have important implications for the treatment of age-related lung diseases, such as asthma.

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.

Blood monocyte levels predict the risk of acute exacerbations of chronic obstructive pulmonary disease: a retrospective case-control study

Monocytes were critical cells in the innate immune system. Monocyte recruitment to the lungs is a crucial process of pathophysiology in chronic obstructive pulmonary disease (COPD). Current evidence on the association between the occurrence of acute exacerbations of COPD (AECOPD) and monocytes was unclear. This study aimed to examine whether blood monocytes are associated with the occurrence of AECOPD and to determine the specific blood monocyte level to predict AECOPD. A retrospective case-control study was conducted at Changhua Christian Hospital. A total of 444 eligible patients with COPD were included between January 2017 and December 2019. Restricted cubic splines were used to analyze the nonlinear relationships between continuous white blood cell values and the occurrence of AECOPD. The association between monocytes and the occurrence of AECOPD was assessed using the logistic, lasso, and ridge regression models. Restricted cubic splines revealed nonlinear associations among the monocyte level, the continuous value of the eosinophil-to-lymphocyte ratio, and the occurrence of AECOPD. The lowest risk of occurrence of AECOPD ranged from 7.4 to 10%; < 7.4% with an absolute count < 0.62 or > 10% indicated significant risk. No significant association was noted between the eosinophil-to-lymphocyte ratio categories in the tertiles (< 0.049, 0.049 to < 0.122, and ≥ 0.122) and the risk of AECOPD. A significantly higher risk was noted in the association of the occurrence of AECOPD with the CAT score; mMRC score; wheezing cough; preexisting chronic pulmonary disease; hypertension and malignancy; use of dual- and triple, and oral long-acting bronchodilators for COPD treatment; and WBC count. We reported a nonlinear relationship between monocytes and the occurrence of AECOPD. Patients with monocyte percentage of > 10% or < 7.4% with an absolute count < 0.62 had higher risk of occurrence of AECOPD. Overall, our study demonstrated the specific value of monocytes in identifying high risks of the occurrence of AECOPD; this value is an easy-to-obtain, inexpensive biomarker in patients with AECOPD and should be further investigated in future prospective clinical studies.

Recent Advances in β2-Agonists for Treatment of Chronic Respiratory Diseases and Heart Failure

β₂-Adrenoceptor (β₂-AR) agonists are widely used as bronchodilators. The emerge of ultralong acting β₂-agonists is an important breakthrough in pulmonary medicine. In this review, we will provide mechanistic insights into the application of β₂-agonists in asthma, chronic obstructive pulmonary disease (COPD), and heart failure (HF). Recent studies in β-AR signal transduction have revealed opposing functions of the β₁-AR and the β₂-AR on cardiomyocyte survival. Thus, β₂-agonists and β-blockers in combination may represent a novel strategy for HF management. Allosteric modulation and biased agonism at the β₂-AR also provide a theoretical basis for developing drugs with novel mechanisms of action and pharmacological profiles. Overlap of COPD and HF presents a substantial clinical challenge but also a unique opportunity for evaluation of the cardiovascular safety of β₂-agonists. Further basic and clinical research along these lines can help us develop better drugs and innovative strategies for the management of these difficult-to-treat diseases.

Aesculetin Attenuates Alveolar Injury and Fibrosis Induced by Close Contact of Alveolar Epithelial Cells with Blood-Derived Macrophages via IL-8 Signaling

Pulmonary fibrosis is a disease in which lung tissues become fibrous and thereby causes severe respiratory disturbances. Various stimuli induce infiltration of macrophages to the respiratory tract, secreting inflammatory cytokines, which subsequently leads to the development of pulmonary fibrosis. Aesculetin, a major component of the sancho tree and chicory, is known to biologically have antioxidant and anti-inflammatory effects. Human alveolar epithelial A549 cells were cultured for 24 h in conditioned media of THP-1 monocyte-derived macrophages (mCM) with 1–20 μM aesculetin. Micromolar aesculetin attenuated the cytotoxicity of mCM containing inflammatory tumor necrosis factor-α (TNF)-α and interleukin (IL)-8 as major cytokines. Aesculetin inhibited alveolar epithelial induction of the mesenchymal markers in mCM-exposed/IL-8-loaded A549 cells (≈47–51% inhibition), while epithelial markers were induced in aesculetin-treated cells subject to mCM/IL-8 (≈1.5–2.3-fold induction). Aesculetin added to mCM-stimulated A549 cells abrogated the collagen production and alveolar epithelial CXC-chemokine receptor 2 (CXCR2) induction. The production of matrix metalloproteinase (MMP) proteins in mCM-loaded A549 cells was reduced by aesculetin (≈52% reduction), in parallel with its increase in tissue inhibitor of metalloproteinases (TIMP) proteins (≈1.8-fold increase). In addition, aesculetin enhanced epithelial induction of tight junction proteins in mCM-/IL-8-exposed cells (≈2.3–2.5-fold induction). The inhalation of polyhexamethylene guanidine (PHMG) in mice accompanied neutrophil predominance in bronchoalveolar lavage fluid (BALF) and macrophage infiltration in alveoli, which was inhibited by orally administrating aesculetin to mice. Treating aesculetin to mice alleviated PHMG-induced IL-8-mediated subepithelial fibrosis and airway barrier disruption. Taken together, aesculetin may antagonize pulmonary fibrosis and alveolar epithelial barrier disruption stimulated by the infiltration of monocyte-derived macrophages, which is typical of PHMG toxicity, involving interaction of IL-8 and CXCR2. Aesculetin maybe a promising agent counteracting macrophage-mediated inflammation-associated pulmonary disorders.

Essential Role of Pharmacists in Asthma Care and Management

Asthma, a chronic respiratory disease characterized by chronic airway inflammation, bronchial hyperresponsiveness, and reversible airflow obstruction, poses a substantial economic burden on patients and caregivers alike. Moreover, the heterogeneous nature of the disease and the presence of various phenotypes make the treatment of asthma challenging and nuanced. Despite the availability of several approved pharmacological treatments, approximately half of patients with asthma in the United States experienced exacerbations in 2016, highlighting the need for effective add-on treatments. Furthermore, asthma control remains suboptimal due to low adherence to medications, poor inhaler technique, and several patient-related factors. Importantly, the primary care setting, in which pharmacists play an integral role, represents a critical environment for providing long-term follow-up care for the effective management of chronic diseases, such as asthma. Pharmacists are uniquely positioned to ensure optimal clinical outcomes in patients with asthma since they have the clinical expertise to educate patients on their disease state and the role of asthma medications, provide training on inhalation technique, address patients’ concerns about potential side effects of medications, and improve adherence to therapy. Therefore, in this review article, we discuss the overall role of pharmacists in effective asthma care and management.

Quantitative determination of potential urine biomarkers of respiratory illnesses using new targeted metabolomic approach

The diagnosis of asthma and chronic obstructive pulmonary disease (COPD) can be challenging due to the overlap in their clinical presentations in some patients. There is a need for a more objective clinical test that can be routinely used in primary care settings. Through an untargeted ¹H NMR urine metabolomic approach, we identified a set of endogenous metabolites as potential biomarkers for the differentiation of asthma and COPD. A subset of these potential biomarkers contains 7 highly polar metabolites of diverse physicochemical properties. To the best of our knowledge, there is no liquid chromatography-tandem mass spectrometry (LC-MS/MS) method that evaluated more than two of the target metabolites in a single analytical run. The target metabolites belong to the families of monosaccharides, organic acids, amino acids, quaternary ammonium compounds and nucleic acids, rendering hydrophilic interaction liquid chromatography (HILIC) an ideal technology for their quantification. Since a clinical decision is to be made from patients data, a fully validated analytical method is required for biomarker validation. Method validation for endogenous metabolites is a daunting task since current guidelines were designed for exogenous compounds. As such, innovative approaches were adopted to meet the validation requirements. Herein, we describe a sensitive HILIC-MS/MS method for the quantification of the 7 endogenous urinary metabolites. Detection was achieved in the multiple reaction monitoring (MRM) mode with polarity switching, using quadrupole-linear ion trap instrument (QTRAP 6500) as well as single ion monitoring in the negative-ion mode. The method was fully validated according to the regulatory guidelines. Linearity was established between 6 and 21000 ng/mL and quality control samples demonstrated acceptable intra- and inter-day accuracy (85.7%-112%), intra- and inter-day precision (CV% <11.5%) as well as stability under various storage and sample processing conditions. To illustrate the method's applicability, the validated method was applied to the analysis of a small set of urine samples collected from asthma and COPD patients. Preliminary modelling of separation was generated using partial least square discriminant analysis (R² 0.752 and Q² 0.57). The adequate separation between patient samples confirms the diagnostic potential of these target metabolites as a proof-of-concept for the differentiation between asthma and COPD. However, more patient urine samples are needed in order to increase the statistical power of the analytical model.

Comparative analysis of creatinine and osmolality as urine normalization strategies in targeted metabolomics for the differential diagnosis of asthma and COPD

INTRODUCTION

Urine is an ideal matrix for metabolomics investigation due to its non-invasive nature of collection and its rich metabolite content. Despite the advancements in mass spectrometry and ¹H-NMR platforms in urine metabolomics, the statistical analysis of the generated data is challenged with the need to adjust for the hydration status of the person. Normalization to creatinine or osmolality values are the most adopted strategies, however, each technique has its challenges that can hinder its wider application. We have been developing targeted urine metabolomic methods to differentiate two important respiratory diseases, namely asthma and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To assess whether the statistical model of separation of diseases using targeted metabolomic data would be improved by normalization to osmolality instead of creatinine.

METHODS

The concentration of 32 metabolites was previously measured by two liquid chromatography-tandem mass spectrometry methods in 51 human urine samples with either asthma (n = 25) or COPD (n = 26). The data was normalized to creatinine or osmolality. Statistical analysis of the normalized values in each disease was performed using partial least square discriminant analysis (PLS-DA). Models of separation of diseases were compared.

RESULTS

We found that normalization to creatinine or osmolality did not significantly change the PLS-DA models of separation (R²Q² = 0.919, 0.705 vs R²Q² = 0.929, 0.671, respectively). The metabolites of importance in the models remained similar for both normalization methods.

CONCLUSION

Our findings suggest that targeted urine metabolomic data can be normalized for hydration using creatinine or osmolality with no significant impact on the diagnostic accuracy of the model.

AFM-based nanomechanical characterization of bronchoscopic samples in asthma patients

Asthma is not a single disease, but recently, it is considered as a syndrome characterized through various clinical presentations and different etiopathologies. Large degree of the disease heterogeneity manifests in distinct characteristics that translate into variability of properties at single cell and molecular levels. Here, we conducted measurements of mechanical properties of bronchial tissue samples collected from patients suffering from asthma. The results obtained from different applied protocols for sample preparation may indicate that deep freezing and storage in liquid nitrogen, followed by consecutive unfreezing of tissue samples, preserve tissue mechanical properties as indicated by a parameter referred here as a tissue relative stiffness index. Tissue relative stiffness index quantifies both the degree of heterogeneity and deformability of tissue samples regarding healthy one. These studies demonstrate that the freezing protocol, optimized towards asthma tissue, can facilitate atomic force microscopy use what, together with recent findings on standardization of elasticity measurements, enables the measurements of large group of samples with minimized influence of errors stemming from the applied methodology of tissue stiffness determination.

[The respiratory effects of smoking]

A marked increase in the morbidity and mortality of a large number of broncho-pulmonary diseases has been documented in relation to smoking. The influence of tobacco smoking on various respiratory conditions. is discussed: incidence, severity or natural history modification of some respiratory illnesses: obstructive lung diseases (COPD, asthma), lung cancer, bacterial, viral respiratory infections, with the impact of smoking on tuberculosis. Finally, the relationship of tobacco with diffuse interstitial lung disease: protective role of smoking (controversial in sarcoidosis, real in hypersensitivity pneumonitis). The benefits of smoking cessation are described.

Azithromycin augments rhinovirus-induced IFNβ via cytosolic MDA5 in experimental models of asthma exacerbation

Deficient production of anti-viral interferons (IFNs) may be involved in causing viral-induced asthma exacerbations. Hence, drugs inducing lung IFN production would be warranted. Azithromycin may reduce asthma exacerbations but its modus operandi is unknown. Here, we investigated if azithromycin induces IFNβ expression in vitro in rhinovirus-infected bronchial epithelial cells from asthmatic donors and in vivo in our allergic inflammation-based mouse model of viral stimulus-induced asthma exacerbations. Azithromycin dose-dependently augmented viral-induced IFNβ expression in asthmatic, but not in healthy bronchial epithelial cells. The effect negatively correlated with viral load. Knockdown of MDA5 and RIG-I by siRNA showed involvement of MDA5 but not RIG-I in azithromycin's IFN-inducing effects in vitro. In vivo azithromycin induced IFNβ protein, restoring a reduced lung IFN response exclusively in allergic exacerbating mice. This was associated with induction of interferon-stimulated genes and MDA5, but not RIG-I. We suggest that clinically relevant concentrations of azithromycin produce MDA5-dependent, anti-viral, IFN-inducing effects in bronchial epithelium distinctly from asthmatic donors. Similarly, azithromycin induced MDA5-associated IFN in virally stimulated lungs in vivo exclusively in allergic mice. Effects of azithromycin and MDA5-active drugs on viral-induced exacerbations deserve further research.

The protective effect of eupafolin against TNF-α-induced lung inflammation via the reduction of intercellular cell adhesion molecule-1 expression

ETHNOPHARMACOLOGICAL RELEVANCE

Eupafolin, a major bioactive compound found in Phyla nodiflora, has the anti-inflammatory property. Upregulation of cell adhesion molecules in the lung airway epithelium is associated with the epithelium-leukocyte interaction and plays a critical role in the pathogenesis of lung airway inflammatory disorders. To investigate the effects of eupafolin on tumor necrosis factor-α (TNF-α)-induced intercellular cell adhesion molecule-1 (ICAM-1) expression in A549 human lung airway epithelial cells and the underlying mechanisms.

MATERIALS AND METHODS

The effect of eupafolin on ICAM-1 expression in A549 cells were examined by Western blotting and immunofluorescent staining. The mice were injected intraperitoneally with or without eupafolin and then were left untreated or were injected intratracheally with TNF-α. To detect the effect of eupafolin on ICAM-1 expression, the lung tissues were also examined by Western blotting and immunohistochemical staining.

RESULTS

Eupafolin pretreatment reduced the TNF-α-induced ICAM-1 expression and also the ERK1/2, JNK, p38, and AKT/PI3K phosphorylation. However, the increase in ICAM-1 expression with TNF-α treatment was unaffected by p38 and PI3K inhibitors. Eupafolin decreased the TNF-α-induced NF-κB p65 activation and its nuclear translocation. Furthermore, eupafolin reduced ICAM-1 expression in the lung tissues of TNF-α-treated mice.

CONCLUSIONS

Eupafolin exerts its anti-inflammatory activity by suppressing the TNF-α-induced ICAM-1 expression and subsequent monocyte adhesion via AKT/ERK1/2/JNK phosphorylation and nuclear translocation of NF-κB p65. These results suggest that eupafolin may represent a novel therapeutic agent targeting epithelial activation in lung inflammation.

Mechanisms of acute exacerbation of respiratory symptoms in chronic obstructive pulmonary disease

Exacerbations of chronic obstructive respiratory disease (ECOPD) are acute events characterized by worsening of the patient's respiratory symptoms, particularly dyspnoea, leading to change in medical treatment and/or hospitalisation. AECOP are considered respiratory diseases, with reference to the respiratory nature of symptoms and to the involvement of airways and lung. Indeed respiratory infections and/or air pollution are the main causes of ECOPD. They cause an acute inflammation of the airways and the lung on top of the chronic inflammation that is associated with COPD. This acute inflammation is responsible of the development of acute respiratory symptoms (in these cases the term ECOPD is appropriate). However, the acute inflammation caused by infections/pollutants is almost associated with systemic inflammation, that may cause acute respiratory symptoms through decompensation of concomitant chronic diseases (eg acute heart failure, thromboembolism, etc) almost invariably associated with COPD. Most concomitant chronic diseases share with COPD not only the underlying chronic inflammation of the target organs (i.e. lungs, myocardium, vessels, adipose tissue), but also clinical manifestations like fatigue and dyspnoea. For this reason, in patients with multi-morbidity (eg COPD with chronic heart failure and hypertension, etc), the exacerbation of respiratory symptoms may be particularly difficult to investigate, as it may be caused by exacerbation of COPD and/or ≥ comorbidity, (e.g. decompensated heart failure, arrhythmias, thromboembolisms) without necessarily involving the airways and lung. In these cases the term ECOPD is inappropriate and misleading.

Increased expression of CD4+IL-17+ cells in the lung tissue of patients with stable chronic obstructive pulmonary disease (COPD) and smokers

CD4(+)IL-17(+) cells have an important role in controlling immune and inflammatory reactions. The authors of the present study hypothesize that these cells may be involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). To characterize the frequency of CD4(+)IL-17(+) cells in the lung alveolar walls, small airways and muscular pulmonary arteries of nonsmokers, smokers with normal lung function and COPD patients, CD4(+)IL-17(+) cell number was assessed using double immunofluorescence staining, and IL-17 and IL-21 expression were measured using real-time quantitative PCR in the peripheral lung tissues of 10 nonsmokers, 10 smokers with normal lung function and 10 smokers with stable COPD. In the lung alveolar walls, the number of CD4(+)IL-17(+) cells was increased in COPD patients compared with nonsmokers and in normal smokers compared with nonsmokers. In the small airways, the CD4(+)IL-17(+) cell numbers were higher in COPD patients than in normal smokers and nonsmokers. A positive correlation was observed between CD4(+)IL-17(+) cell expression and pathological changes in the lung tissue. In the small airways, the number of CD4(+)IL-17(+) cells was positively correlated with airflow limitations. The IL-17 mRNA levels in lung tissues were increased in COPD patients and normal smokers compared with nonsmokers. Increased CD4(+)IL-17(+) cell number in lung tissue is involved in chronic inflammation of the lungs and parallels lung injury aggravation in COPD patients and in smokers without airway limitations. These findings contribute to a better understanding of CD4(+) cell-related pathogenesis in COPD.