BackgroundRecent studies suggest that YKL-40, also called chitinase-3-like-1 protein, has been implicated in the pathogenesis of various inflammatory diseases. It is currently unknown, however, whether YKL-40 plays a role in acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and airway remodeling.MethodsWe evaluated serum YKL-40 levels in patients with AECOPD (n = 37) and stable COPD (n = 44), as well as in controls (n = 47). The association between YKL-40 expression and airway remodeling was analyzed. The effects of YKL-40 on collagen synthesis of primary human lung fibroblasts were also evaluated.ResultsSerum YKL-40 levels were elevated at AECOPD onset as compared to stable disease (median [interquartile range], 78.6 [52.3–122.2] ng/ml versus 46.7 [31.2–75.5] ng/ml; p = 0.0005). The ideal cutoff point for distinguishing patients with AECOPD from those with stable COPD was 64.7 ng/ml (AUC: 0.71; 95%CI: 0.596 to 0.823). YKL-40 expression correlated with airflow obstruction, C-reactive protein, and collagen deposition. Stimulation with YKL-40 promoted collagen production in lung fibroblasts through ERK- and p38-dependent mechanisms.ConclusionsYKL-40 expression is up-regulated in patients with COPD and correlates with exacerbation attacks and may contribute to airway remodeling by acting on lung fibroblasts. The current data may provide insight into the underlying pathogenesis of COPD, in which YKL-40 has an important pathogenic role.Trial registrationChiCTR-OCC-13003567Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-016-0338-3) contains supplementary material, which is available to authorized users.

Interleukin 31 (IL-31) is a novel T helper type 2 effector cytokine that plays an important role in the pathogenesis of allergic diseases. However, its role in human asthma remains unclear. The aim of this study was to measure IL-31 levels in the serum, bronchoalveolar lavage fluid (BALF) and bronchial tissue of asthmatics and healthy subjects, and identify its possible correlation to disease severity. We quantified IL-31 levels in the serum of patients with asthma (n = 44), as well as in controls (n = 22). Of these subjects, 9 asthmatics and five controls underwent bronchoscopy with endobronchial biopsy and BALF collection. Our data showed that serum and BALF IL-31 levels were significantly elevated in patients with asthma compared with controls. Expressions of IL-31 and IL-31 receptor (IL-31RA and OSMR) were more prominent in the bronchial tissue in severe compared to mild asthma and controls. Serum IL-31 levels correlated positively with Th2 related cytokines (IL-5, IL-13, and TSLP), asthma severity or total serum immunoglobulin E (IgE), and inversely with asthma control and the forced expiratory volume in 1 second (FEV1). The current data may provide insight into the underlying pathogenesis of asthma, in which IL-31 has an important pathogenic role.

Background and objective: Silent information regulator 1 (SIRT1) is a class III histone deacetylase that exerts both anti-inflammatory and anti-aging effects. However, no data are available regarding SIRT1 expression in patients with asthma. Here, we studied SIRT1 levels in the serum of patients with asthma and analysed the distribution of SIRT1 in both the serum and the lungs in an asthmatic mouse model to determine its clinical significance. Methods: Serum SIRT1 levels, total immunoglobulin E (IgE) levels and peripheral blood eosinophil percentages as well as pulmonary function were quantified in 97 patients with asthma and 118 healthy volunteers. BALB/c mice were sensitized and challenged using ovalbumin (OVA) to produce the asthmatic model, and SIRT1 levels in both the serum and the lung tissues were subsequently measured. Results: The serum SIRT1 levels were significantly elevated in the patients with asthma compared with the controls. Serum SIRT1 levels positively correlated with total IgE levels and negatively correlated with pulmonary function. In the OVA-sensitized and challenged mice, an increased serum SIRT1 level was confirmed, whereas decreased SIRT1 expression was observed in the lung tissues. Conclusions: These data indicate that lung SIRT1 expression decreased while serum SIRT1 increased in the setting of asthma. Serum SIRT1 levels correlate positively with both IgE levels and negatively with pulmonary function, suggesting that increased peripheral SIRT1 levels represent a new biological characteristic of asthma. Increased serum SIRT1 may be an auxiliary index for the diagnosis of asthma and elevating lung SIRT1 levels may be a new strategy for asthma therapy.

Purpose Particulate matter (PM) has been implicated as a risk factor for airway injury. However, the molecular mechanisms remain largely unclear. The goal of this study was to determine whether sirtuin1 (SIRT1), an anti-inflammatory and antiaging protein, protects against PM-induced airway inflammation. Methods The effect of SIRT1 on PM-induced airway inflammation was assessed by using in vivo models of airway inflammation induced by PM and in vitro culture of human bronchial epithelial (HBE) cells exposed to PM, resveratrol (SIRT1 activator), or both. Results PM-stimulated HBE cells showed a significant decrease in SIRT1 but a notable increase in inflammatory cytokines. SIRT1 gene silencing further enhanced PM-induced expression of inflammatory cytokines. In contrast, resveratrol, a SIRT1 activator, reduced the expression of these cytokines compared with the control cells. In vivo, SIRT1 expression was significantly decreased in lung tissues of PM-exposed mice. Interestingly, resveratrol treatment reversed the enhanced total cells, neutrophils and inflammatory cytokines in PM-induced mice. Moreover, SIRT1 mediated PM-induced inflammatory cytokines expression at least partly through MAPK pathways. Conclusion These findings suggest that SIRT1 is involved in the pathogenesis of PM-induced airway inflammation and activation of SIRT1 could prevent airway disorders or disease exacerbations induced by airborne particulate pollution.

PurposeFibrosis in peripheral airways is responsible for airflow limitation in chronic obstructive pulmonary disease (COPD). Annexin A1 modulates several key biological events during inflammation. However, little is known about its role in airway fibrosis in COPD. We investigated whether levels of Annexin A1 were upregulated in patients with COPD, and whether it promoted airway fibrosis.MethodsWe quantified serum Annexin A1 levels in never-smokers (n=12), smokers without COPD (n=11), and smokers with COPD (n=22). Correlations between Annexin A1 expression and clinical indicators (eg, lung function) were assessed. In vitro, human bronchial epithelial (HBE) cells were exposed to cigarette smoke extract (CSE) and Annexin A1 expression was assessed. Primary human lung fibroblasts were isolated from patients with COPD and effects of Annexin A1 on fibrotic deposition of lung fibroblasts were evaluated.ResultsSerum Annexin A1 was significantly higher in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines stage III or IV than in those with GOLD stages I or II (12.8±0.8 ng/mL versus 9.8±0.7 ng/mL; p=0.016). Annexin A1 expression was negatively associated with airflow obstruction (forced expiratory volume in one second % predicted; r=−0.72, p<0.001). In vitro, Annexin A1 was significantly increased in CSE-exposed HBE cells in a time- and concentration-dependent manner. Annexin A1 promoted lung fibroblasts proliferation, migration, differentiation, and collagen deposition via the ERK1/2 and p38 mitogen-activated protein kinase pathways.ConclusionAnnexin A1 expression is upregulated in patients with COPD and affects lung fibroblast function. However, more studies are needed to clarify the role of Annexin A1 in airway fibrosis of COPD.

Etiological evidence demonstrates that there is a significant association between cigarette smoking and chronic airway inflammatory disease. Abnormal expression of placental growth factor (PlGF) has been reported in COPD, and its downstream signaling molecules have been reported to contribute to the pathogenesis of airway epithelial cell apoptosis and emphysema. However, the signaling mechanisms underlying cigarette smoke extract (CSE)-induced PlGF expression in airway microenvironment remain unclear. Herein, we investigated the effects of reactive oxygen species (ROS)-dependent activation of the mitogen-activated protein kinase (MAPK) (extracellular signal-regulated kinase1/2 [ERK-1/2])/early growth response-1 (Egr-1) pathway on CSE-induced PlGF upregulation in human bronchial epithelium (HBE). The data obtained with quantitative reverse transcription polymerase chain reaction, Western blot, enzyme-linked immunosorbent assay (ELISA) and immunofluorescence staining analyses showed that CSE-induced Egr-1 activation was mainly mediated through production of ROS and activation of the MAPK (ERK-1/2) cascade. The binding of Egr-1 to the PlGF promoter was corroborated by an ELISA-based DNA binding activity assay. These results demonstrate that ROS activation of the MAPK (ERK-1/2)/Egr-1 pathway is a main player in the regulatory mechanism for CSE-induced PlGF production and that the use of an antioxidant could partly abolish these effects. Understanding the mechanisms of PlGF upregulation by CSE in the airway microenvironment may provide rational therapeutic interventions for cigarette smoking-related airway inflammatory diseases.

PurposeChoosing the appropriate time to switch to noninvasive positive-pressure ventilation (NPPV) plays a crucial role in promoting successful weaning. However, optimal timing for transitioning and weaning patients from mechanical ventilation (MV) to NPPV has not been clearly established. In China, the pulmonary infection control (PIC) window as a switching point for weaning from MV has been performed for many years, without definitive evidence of clinical benefit. This study aimed to summarize the evidence for NPPV at the PIC window for patients with respiratory failure from COPD.MethodsA comprehensive search for randomized controlled trials (RCTs) was performed. The trials were all parallel studies comparing the PIC window weaning strategy versus conventional weaning strategy in treatment of patients with respiratory failure due to COPD.ResultsSixteen studies of 647 participants were eligible. When compared with conventional weaning strategy, early extubation followed by NPPV at the point of PIC window significantly reduced the mortality rate (risk ratios [RRs] 0.36, 95% confidence interval [CI] 0.23 to 0.57) and ventilator-associated pneumonia (VAP) (RR 0.28, 95% CI 0.19 to 0.41); it also decreased the duration of invasive ventilation (weighted mean difference [WMD] −7.68 days, 95% CI −9.43 to −5.93) and total duration of ventilation (WMD −5.93 days, 95% CI −7.29 to −4.58), which also shortened the lengths of stay in an intensive care unit (WMD −8.51 days, 95% CI −10.23 to −6.79), as well as length of stay in hospital (WMD −8.47 days, 95% CI −8.61 to −7.33).ConclusionThe results showed that the PIC window as a switching point for sequential ventilation in treatment of respiratory failure in COPD patients may be beneficial. It might yield not only relevant information for caregivers in China but also new insights for considering the PIC window by physicians in other countries.

Although airway fibrosis and epithelial-mesenchymal transition (EMT) contribute to airway remodeling in chronic obstructive pulmonary disease (COPD), the mechanisms underlying their development have not been fully elucidated. In the present study, we aimed to assess heparin-binding epidermal growth factor (HB-EGF) expression in the airways of patients with COPD and to elucidate the possible role of HB-EGF in the pathology of COPD. Sputum and lung tissue HB-EGF expression was evaluated in control subjects and patients with COPD. The relationships between HB-EGF expression, disease severity, collagen deposition (fibrosis), and EMT were investigated. In vitro, human bronchial epithelial (HBE) cells and lung fibroblast cells exposed to the recombinant HB-EGF, collagen deposition and EMT were assessed. We found that sputum HB-EGF expression was significantly increased in patients with COPD compared with non-smokers and smokers without COPD. There was a significant positive correlation between sputum HB-EGF and COPD assessment test (CAT) score. HB-EGF expression was significantly increased in the lung tissue samples of patients with COPD and associated with collagen deposition and N- and E-cadherin, and vimentin expression. In vitro, HB-EGF promoted collagen production in lung fibroblasts. Moreover, HB-EGF induced the EMT process through induction of N-and E-cadherin, and vimentin expression in HBE cells. Collectively, HB-EGF induces airway remodeling by modulating airway fibrosis and pulmonary EMT, and contributes to the COPD severity. The current data may provide insight into the underlying pathogenesis of COPD, in which HB-EGF has an important pathogenic role.