Laiyu Liu

High mobility group protein B1 (HMGB1) in Asthma: comparison of patients with chronic obstructive pulmonary disease and healthy controls.

High mobility group protein B1 (HMGB1) has been implicated as an important mediator in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). However, the expression of HMGB1 in plasma and sputum of patients with asthma and COPD across disease severity needs to be defined. The objective of the study was to examine the induced sputum and plasma concentrations of HMGB1 in COPD and asthmatic patients to determine differences in HMGB1 levels between these diseases and their relationship with airway obstruction and inflammatory patterns. A total of 147 participants were enrolled in this study. The participants included 34 control subjects, 61 patients with persistent asthma (according to the Global Initiative for Asthma [GINA] guidelines) and 47 patients with stable COPD (stratified by Global Initiative for Chronic Obstructive Lung Disease [GOLD] status). Spirometry was performed before sputum induction. HMGB1 levels in induced sputum and plasma were determined by enzyme-linked immunosorbent assay. Sputum and plasma concentrations of HMGB1 in patients with asthma and COPD were significantly higher than concentrations in control subjects and were significantly negatively correlated with forced expiratory volume in 1 s (FEV1), FEV1 (% predicted) in all 147 participants. The levels of HMGB1 in induced sputum of COPD patients were significantly higher than those of asthma patients and healthy controls (P < 0.001). This difference was present even after adjusting for sex, age, smoking status, daily dose of inhaled corticosteroids and disease severity. There were no significant differences in HMGB1 levels between patients with eosinophilic and noneosinophilic asthma. HMGB1 levels in asthmatic and COPD patients were positively correlated with neutrophil counts and percentage of neutrophils. In multivariate analysis, the two diseases (asthma and COPD) and disease severity were independent predictors of sputum HMGB1, but not smoking, age or use of inhaled corticosteroids. In conclusion, these data support a potential role for HMGB1 as a biomarker and diagnostic tool for the differential diagnosis of asthma and COPD. The importance of this observation on asthma and COPD mechanisms and outcomes should be further investigated in large prospective studies.

Mechanism of E-cadherin redistribution in bronchial airway epithelial cells in a TDI-induced asthma model☆

E-cadherin (epithelial cadherin), a transmembrane protein, provides essential architecture and immunological function to the airway epithelium, a barrier structure that plays an essential role in asthma pathogenesis. Toluene diisocyanate (TDI) is currently one of the leading causes of occupational asthma. However, relatively few studies have been undertaken to determine the biological effects of TDI on the barrier properties of airway epithelium, but it is known that TDI can damage airway epithelial tight junctions in vitro. Here, we hypothesize that TDI can injure E-cadherin both in normal and allergic-induced airway epithelium. To test this, we developed a murine model of TDI-induced asthma characterized by neutrophil-dominated airway inflammation, epithelial shedding, and obvious aberrant distribution of E-cadherin. Pretreatment with dexamethasone (DEX) significantly rescued the immunoreactivity of E-cadherin, accompanied by increased neutrophils in bronchoalveolar lavage fluid (BALF). In vitro, TDI-human serum albumin (HSA)-induced redistribution of E-cadherin was associated with extracellular signal-regulated kinase (ERK)1/2 activation. The inhibition of phospho-ERK (p-ERK)1/2 by DEX can partly reverse this reaction. These results indicate that E-cadherin redistribution may be an important contributor in the generation of TDI-induced asthma.

Erratum to: Increased heat shock protein 70 levels in induced sputum and plasma correlate with severity of asthma patients

Damage-associated molecular pattern molecules such as high-mobility group box 1 protein (HMGB1) and heat shock protein 70 (HSP70) have been implicated in the pathogenesis of asthma. The aim of our study was to examine the induced sputum and plasma concentrations of HSP70 in asthmatic patients to determine their relationship with airway obstruction. Thirty-four healthy controls and 56 patients with persistent bronchial asthma matched for gender and age were enrolled in this study. Spirometry measurements were performed before sputum induction. HSP70 levels in induced sputum and plasma were measured using the ELISA Kit. Sputum and plasma concentrations of HSP70 in asthmatics patients were significantly higher than that in control subjects (sputum, (0.88 ng/ml (0.27–1.88 ng/ml) versus 0.42 ng/ml (0.18–0.85 ng/ml), p < 0.001); plasma, (0.46 ng/ml (0.20–0.98 ng/ml) versus 0.14 ng/ml (0.11–0.37 ng/ml), p < 0.001) and were significantly negatively correlated with forced expiratory volume in 1 s (FEV1), FEV1 (percent predicted), and FEV1/FVC in all 90 participants and 56 patients with asthma. There were no significant differences in HSP70 levels between patients with eosinophilic and non-eosinophilic asthma. HSP70 levels in plasma were positively correlated with neutrophil count, and HSP70 levels in induced sputum were positively correlated with lymphocyte count. In multivariate analysis, independent predictors of sputum HSP70 were diseases and disease severity but not smoking, age, or gender, and independent predictors of plasma HSP70 were also diseases and disease severity. In conclusion, this study indicates that induced sputum and plasma HSP70 could serve as a useful marker for assessing the degree of airway obstruction in patients with asthma. However, further investigation is needed to establish the role of circulating and sputum HSP70 in the pathogenesis of asthma.

Distinct roles of short and long thymic stromal lymphopoietin isoforms in house dust mite-induced asthmatic airway epithelial barrier disruption

Loss of airway epithelial integrity contributes significantly to asthma pathogenesis. Thymic stromal lymphopoietin (TSLP) may have dual immunoregulatory roles. In inflammatory disorders of the bowel, the long isoform of TSLP (lfTSLP) promotes inflammation while the short isoform (sfTSLP) inhibits inflammation. We hypothesize that lfTSLP contributes to house dust mite (HDM)-induced airway epithelial barrier dysfunction and that synthetic sfTSLP can prevent these effects. In vitro, airway epithelial barrier function was assessed by monitoring transepithelial electrical resistance, fluorescent-dextran permeability, and distribution of E-cadherin and β-catenin. In vivo, BALB/c mice were exposed to HDM by nasal inhalation for 5 consecutive days per week to establish an asthma model. sfTSLP and 1α,25-Dihydroxyvitamin D3 (1,25D3) were administered 1 h before HDM exposure. After 8 weeks, animal lung function tests and pathological staining were performed to evaluate asthma progression. We found that HDM and lfTSLP impaired barrier function. Treatment with sfTSLP and 1,25D3 prevented HDM-induced airway epithelial barrier disruption. Moreover, sfTSLP and 1,25D3 treatment ameliorated HDM-induced asthma in mice. Our data emphasize the importance of the different expression patterns and biological properties of sfTSLP and lfTSLP. Moreover, our results indicate that sfTSLP and 1,25D3 may serve as novel therapeutic agents for individualized treatment of asthma.

1,25-Dihydroxyvitamin D3 prevents toluene diisocyanate-induced airway epithelial barrier disruption

The loss of airway epithelial integrity contributes significantly to asthma pathogenesis. Evidence suggests that vitamin D plays an important role in the prevention and treatment of asthma. However, its role in airway epithelial barrier function remains uncertain. We have previously demonstrated impaired epithelial junctions in a model of toluene diisocyanate (TDI)-induced asthma. In the present study, we hypothesized that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] may prevent TDI-induced epithelial barrier disruption. Male BALB/c mice were dermally sensitized and then challenged with TDI. The mice were then administered 1,25(OH)2D3 intraperitoneally prior to challenge with TDI. For in vitro experiments, 16HBE bronchial epithelial cells were cultured and stimulated with TDI-human serum albumin (HSA). The results revealed that the mice treated with 1,25(OH)2D3 displayed decreased airway hyperresponsiveness (AHR), suppressed neutrophil and eosinophil infiltration into the airways, as well as an increased E-cadherin and zonula occludens-1 (ZO-1) expression at the cell-cell contact sites. In vitro, exposure of the cells to TDI-HSA induced a rapid decline in transepithelial electrical resistance (TER) and an increase in cell permeability, followed by a decrease in occludin expression and the redistribution of E-cadherin, accompanied by a significant upregulation in the levels of phosphorylated extracellular signal-regulated kinase (ERK)1/2. These effects were all partly reversed by treatment with either 1,25(OH)2D3 or an ERK1/2 inhibitor. In conclusion, the findings of our study demonstrate that 1,25(OH)2D3 prevents TDI-induced epithelial barrier disruption, and that the ERK1/2 pathway may play a role in this process.

The receptor for advanced glycation end products is required for β-catenin stabilization in a chemical -induced asthma model.

Cytoplasmic retention of β‐catenin will lead to its nuclear translocation and subsequent interaction with the transcription factor TCF/LEF that regulates target gene expression. We have previously demonstrated aberrant expression of β‐catenin in a model of asthma induced by toluene diisocyanate (TDI). The aim of this study was to examine whether the receptor for advanced glycation end products (RAGE) can regulate β‐catenin expression in TDI‐induced asthma.

Phosphatidylinositol 3-kinases pathway mediates lung caspase-1 activation and high mobility group box 1 production in a toluene-diisocyanate induced murine asthma model

We have previously demonstrated that downregulating HMGB1 decreases airway neutrophil inflammation in a toluene-diisocyanate (TDI)-induced murine asthma model, yet how HMGB1 is regulated in the lung remains uncertain. In this study, we intended to explore whether PI3K signaling pathway mediates pulmonary HMGB1 production in TDI-induced asthma model and the possible roles of NLRP3 inflammasome and caspase-1 in this process. BALB/c mice were sensitized and challenged with TDI to establish a TDI-induced asthma model. LY294002, a specific inhibitor of PI3K, was given intratracheally 1h before each challenge. Here we showed that airway hypersensitivity, airway infiltration of neutrophils and eosinophils, serum IgE and IL-4 in supernatant of cervical lymphocytes in TDI induced asthmatic mice were all markedly decreased by LY294002, accompanied by suppressed pulmonary expression of HMGB1. At the same time, we observed elevated protein levels of cleaved caspase-1 and IL-1β after TDI challenge, as well as increased immunoreactivity in lung, all of which were significantly recovered by LY294002. While both the protein expression and immunodistribution of NLRP3 in the lung stayed unchanged. These data suggest that PI3K mediates lung caspase-1 activation and HMGB1 production in TDI-induced murine asthma model.

Blockade of β-catenin signaling attenuates toluene diisocyanate-induced experimental asthma

Aberrant activation of β‐catenin signaling by both WNT‐dependent and WNT‐independent pathways has been demonstrated in asthmatic airways, which is thought to contribute critically in remodeling of the airways. Yet, the exact role of β‐catenin in asthma is very poorly defined. As we have previously reported abnormal expression of β‐catenin in a toluene diisocyanate (TDI)‐induced asthma model, in this study, we evaluated the therapeutic efficacy of two small molecules XAV‐939 and ICG‐001 in TDI‐asthmatic male BALB/c mice, which selectively block β‐catenin‐mediated transcription.

TSLP signaling blocking alleviates E-cadherin dysfunction of airway epithelium in a HDM-induced asthma model

Recent studies have indicated that Thymic stromal lymphopoietin (TSLP) plays an important role in the prevention and treatment of asthma. However the role of TSLP in dysfunction of airway epithelial adherens junctions E-cadherin in house dust mite (HDM)-induced asthma has not been addressed. We hypothesized that TSLP contributed to HDM-induced E-cadherin dysfunction in asthmatic BALB/c mice and 16HBE cells. In vivo, a HDM-induced asthma mouse model was set up for 8weeks. Mice inhaled an anti-TSLP monoclonal antibody (mAb) before HDM. The mice treated with the anti-TSLP mAb ameliorated airway inflammation, the decreasing and aberrant distribution of E-cadherin and β-catenin as well as phosphorylation(p)-AKT induced by HDM. In vitro, HDM increased the expression of TSLP and E-cadherin dysfunction by PI3K/Akt signaling pathway. The exposure of 16HBE to TSLP resulted in redistribution of E-cadherin. These results indicate that TSLP may be an important contributor in E-cadherin dysfunction of HDM-induced asthma. TSLP signaling blocking shows a protective effect in mice and that the PI3K/Akt pathway may play a role in this process.

A Systemic Inflammatory Endotype of Asthma With More Severe Disease Identified by Unbiased Clustering of the Serum Cytokine Profile.

AbstractAsthma is considered as a clinical and molecularly heterogeneous disorder. Systemic inflammation is suggested to play an important role in a group of asthma patients. We hypothesized that there is a subgroup of patients with asthma characterized by systemic inflammation. In this study, we aimed to discriminate asthma subtypes based on circulating biomarkers and to determine whether a systemic inflammatory endotype of asthma could be identified. In the present cross-sectional study, 50 patients with untreated asthma were prospectively recruited from a single academic outpatient clinic, and characterized with respect to clinical, functional, and inflammatory parameters. The expression profiles of 20 serum cytokines were assessed by anti-human cytokine antibody array. Then, hierarchical clustering analysis was performed based on principal component analysis (PCA)-transformed data to classify the clinical groups. PCA showed that 6 independent components accounted for 80.113% of the variance, and PCA-based hierarchical clustering identified 3 endotypes. One of the endotypes was evidenced by elevated systemic inflammation markers such as leptin, vascular endothelial growth factor (VEGF), and reduced levels of soluble receptor for advanced glycation end products (sRAGE), an anti-inflammatory molecule. More female patients were included, with higher circulating neutrophil counts and more severe symptoms. In conclusion, we identified an endotype of asthma characterized by systemic inflammation and severe symptoms. Increased levels of VEGF, leptin and decreased level of sRAGE may contribute to the systemic inflammation of this asthma endotype.