Airway remodeling in asthma and irreversible airflow limitation-ECM deposition in airway and possible therapy for remodeling-

YiQi GuBen formula alleviates airway inflammation and airway remodeling in OVA-induced asthma mice through TLR4/NF-κB signaling pathway

BACKGROUND

We aim to investigate the effect of YiQi GuBen formula (YQGB) on airway inflammation and airway remodeling in the ovalbumin (OVA)-induced asthma model to further explore the potential mechanisms of YQGB in treating allergic asthma.

METHODS

Mice were divided into five groups randomly (n = 10): the control group, OVA group, OVA + Dex (0.1 mg/kg) group, OVA + low-dose (1.1 g/kg) YQGB group, and OVA + high-dose (2.2 g/kg) YQGB group. Inflammatory cell count and IgE were detected in bronchoalveolar lavage fluid (BALF). Lung tissue histopathology was observed by using H&E, PAS, Masson, and immunohistochemistry staining. qRT-PCR and western blot were applied to analyze key genes and proteins associated with TLR4 and NF-κB signaling pathways.

RESULTS

In OVA-induced asthma mice, YQGB decreased eosinophils and IgE in BALF. YQGB alleviated the OVA-induced inflammatory infiltration and declined IL-4, IL-5, IL-13, Eotaxin, ECP, GM-CSF, LTC4, and LTD4. YQGB attenuated the OVA-induced goblet cell metaplasia and mucus hypersecretion. YQGB mitigated the OVA-induced subepithelial fibrosis and lowered TGF-β1, E-Cadherin, Vimentin, and Fibronectin. YQGB ameliorated the OVA-induced airway smooth muscle thickening and lessened α-SMA and PDGF levels. YQGB reduced the expression of TLR4, MyD88, TRAF6, IκBα, and p65 mRNAs, and IκBα and p-p65 protein levels were also reduced.

CONCLUSION

YQGB exhibits the anti-asthma effect by reducing airway inflammation and airway remodeling through suppressing TLR4/NF-κB signaling pathway, and is worth promoting clinically.

RNA Sequencing and Bioinformatics Analysis to Reveal Potential Biomarkers in Patients with Combined Allergic Rhinitis and Asthma Syndrome

Introduction

Combined allergic rhinitis and asthma syndrome (CARAS) is a concurrent clinical or subclinical allergic symptom of diseases of the upper and lower respiratory tract. This study is the first to explore the expression profiles of mRNA, lncRNA, and circRNA in CARAS using RNA sequencing, which may provide insight into the mechanisms underlying CARAS.

Material and Methods

Whole blood samples from nine participants (three CARAS patients, three AR patients, and three normal control participants) were subjected to perform RNA sequencing, followed by identification of differentially expressed lncRNAs (DElncRNAs), circRNAs (DEcircRNAs) and mRNAs (DEmRNAs). Then, lncRNA/circRNA-mRNA regulatory pairs were constructed, followed by functional analysis, immune infiltration analysis, drug prediction, and expression validation with RT-qPCR and ELISA.

Results

The results showed that 61 DEmRNAs, 23 DElncRNAs and 3 DEcircRNAs may be related to the occurrence and development of CARAS. KRT8 may be implicated in the development of AR into CARAS. Three immunity-related mRNAs (IDO1, CYSLTR2, and TEC) and two hypoxia-related mRNAs (TKTL1 and VLDLR) were associated with the occurrence and development of CARAS. TEC may be considered a drug target for Dasatinib in treating CARAS. Several lncRNA/circRNA-mRNA regulatory pairs were identified in CARAS, including LINC00452/MIR4280HG/hsa_circ_0007272/hsa_circ_0070934-CLC, HEATR6-DT/LINC00639/LINC01783/hsa_circ_0008903-TEC, RP11-71L14.3-IDO1/SMPD3, RP11-178F10.2-IDO1/HRH4, and hsa_circ_0008903-CYSLTR2, which may indicate potential regulatory effects of lncRNAs/circRNAs in CARAS. Dysregulated levels of immune cell infiltration may be closely related to CARAS.

Conclusion

The regulating effect of lncRNA/circRNA-immunity/hypoxia-related mRNA regulatory pairs may be involved in the occurrence and development of CARAS.

TSLP Induces Epithelial-Mesenchymal Transition in Nasal Epithelial Cells From Allergic Rhinitis Patients Through TGF-β1/Smad2/3 Signaling

BACKGROUND

Airway remodeling is demonstrated in Asian patients with allergic rhinitis (AR). The epithelial-mesenchymal transition (EMT) is one of the key mechanisms underlying airway remodeling. Thymic stromal lymphopoietin (TSLP) is an important contributor to airway remodeling. Although increased TSLP is found in AR, little is known about whether TSLP is involved in airway remodeling through induction of the EMT.

OBJECTIVE

We investigated the effect of TSLP on the EMT in human nasal epithelial cells (HNECs) from AR patients.

METHODS

Human nasal epithelial cells from AR patients were stimulated with TSLP in the absence or presence of the preincubation with a selective inhibitor of transforming growth factor beta 1 (TGF-β1) receptor (SB431542). The expression of TGF-β1 in the cells was evaluated by using real-time polymerase chain reaction, Western blotting, and immunocytochemistry. Western blotting and immunocytochemistry were used to assay EMT markers including vimentin, fibroblast-specific protein 1 (FSP1) and E-cadherin, small mothers against decapentaplegic homolog2/3 (Smad2/3), and phosphorylated Smad2/3 in the cells. The levels of extracellular matrix components such as collagens I and III in supernatants were measured by enzyme-linked immunoassay. Morphological changes of the cells were observed under inverted phase-contrast microscope.

RESULTS

A concentration-dependent increase of TGF-β1 mRNA and protein was observed following stimulation with TSLP. Furthermore, TSLP decreased the expression of E-cadherin protein, but upregulated the production of FSP1 and vimentin proteins along with increased levels of collagens I and III, and the morphology of the cells was transformed into fibroblast-like shape. Additionally, a significant increase was found in phosphorylation of Smad2/3 protein. However, these effects were reversed by SB431542 preincubation.

CONCLUSION

TSLP-induced HNECs to undergo the EMT process via TGF-β1-mediated Smad2/3 activation. TSLP is an activator of the EMT in HNECs and might be a potential target for inhibiting EMT and reducing airway remodeling in AR.

The Role of Vitamin D Supplementation on Airway Remodeling in Asthma: A Systematic Review

Asthma is a common chronic respiratory disease that affects millions of people worldwide, and its prevalence continues to increase. Vitamin D has been proposed as a potential environmental factor in asthma pathogenesis, due to its immunomodulatory effects. This systematic review aimed to evaluate the effect of vitamin D supplementation in order to prevent airway remodeling in asthmatic patients. Four electronic databases, namely PubMed, Embase, Clinical trails.gov, and CINAHL, were thoroughly searched to conduct a comprehensive literature review. The International Prospective Register of Systematic Reviews (CRD42023413798) contains a record of the registered protocol. We identified 9447 studies during the initial search; 9 studies (0.1%) met the inclusion criteria and were included in the systematic review. All included studies were experimental studies that investigated the impact of vitamin D supplementation on airway remodeling in asthma. The studies included in this review suggest that vitamin D inhibits airway smooth muscle cell contraction and remodeling, reduces inflammation, regulates collagen synthesis in the airways, and modulates the action of bronchial fibroblasts. However, one study suggests that TGF-β1 can impair vitamin D-induced and constitutive airway epithelial host defense mechanisms. Overall, vitamin D appears to have a potential role in the prevention and management of asthma.

Modulation of Arginase-2 mRNA Levels by ω-3 PUFAs and Aspirin in Asthmatic Human Lung Fibroblasts

Airway remodeling (AR) increases disease severity, and morbidity of asthmatic patients by contributing to irreversible airflow obstruction and progressive declines in lung function. Arginase isoenzymes and the downstream enzymes ornithine decarboxylase (ODC) and ornithine aminotransferase (OAT) have been implicated in the hyperplastic and fibrotic changes of AR, respectively. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) and resolvin metabolites have anti-AR effects, but whether they are mediated through the arginase pathway is unclear. Our study intended to determine the effects of the ω-3 PUFAs eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), resolvin D1 (RvD1), TH1 cytokines, acetylsalicylic acid (ASA), cAMP, and dexamethasone (DEX) on the expression of arginase isoenzymes arginase 1 (ARG1) and arginase 2 (ARG2), ODC, and OAT in human lung fibroblasts (HLF) from normal (NHLF) and diseased (DHLF) asthmatic donors using reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). Our data showed that EPA and EPA+DHA downregulated ARG2 mRNA 2-fold in both types of HLF. DHA, RvD1, and DEX did not alter mRNA levels for any of the genes studied. EPA lowered the ARG2 protein levels in DHLF, but did not affect those levels in NHLF. ASA upregulated ARG2 mRNA 5-fold and 7-fold in NHLF and DHLF, respectively, TH1 cytokines downregulated ARG2, ODC, and OAT mRNA in DHLF 10-fold, 2-fold, and 2.5-fold, respectively, and cAMP downregulated ARG2 mRNA 2-fold in DHLF. These results are the first to show a direct effect of ω-3 PUFAs on ARG2 mRNA levels and provide further evidence for a role of ω-3 PUFAs in AR.

Relaxin Affects Airway Remodeling Genes Expression through Various Signal Pathways Connected with Transcription Factors

Fibrosis is one of the parameters of lung tissue remodeling in asthma. Relaxin has emerged as a natural suppressor of fibrosis, showing efficacy in the prevention of a multiple models of fibrosis. Therefore, the aim of this study was to analyze the aptitudes of relaxin, in the context of its immunomodulatory properties, in the development of airway remodeling. WI-38 and HFL1 fibroblasts, as well as epithelial cells (NHBE), were incubated with relaxin. Additionally, remodeling conditions were induced with two serotypes of rhinovirus (HRV). The expression of the genes contributing to airway remodeling were determined. Moreover, NF-κB, c-Myc, and STAT3 were knocked down to analyze the pathways involved in airway remodeling. Relaxin decreased the mRNA expression of collagen I and TGF-β and increased the expression of MMP-9 (p < 0.05). Relaxin also decreased HRV-induced expression of collagen I and α-SMA (p < 0.05). Moreover, all the analyzed transcription factors—NF-κB, c-Myc, and STAT3—have shown its influence on the pathways connected with relaxin action. Though relaxin requires further study, our results suggest that this natural compound offers great potential for inhibition of the development, or even reversing, of factors related to airway remodeling. The presented contribution of the investigated transcription factors in this process additionally increases its potential possibilities through a variety of its activity pathways.

Amphiregulin induces CCN2 and fibronectin expression by TGF-β through EGFR-dependent pathway in lung epithelial cells

BACKGROUND

Airway fibrosis is one of the pathological characteristics of severe asthma. Transforming growth factor (TGF)-β has been known to promote epithelial-mesenchymal transition formation and to play a role in the progression of tissue fibrosis. Cellular communication network factor 2 (CCN2) and fibronectin (FN) are well-known markers of EMT and fibrosis. However, whether AREG is involved in TGF-β-induced CCN2 and FN expression in human lung epithelial cells is unknown.

METHODS

AREG and FN were analyzed by immunofluorescence staining on ovalbumin-challenged mice. CCN2 and FN expression were evaluated in human lung epithelial (A459) cells following TGF or AREG treatment for the indicated times. Secreted AREG from A549 cells was detected by ELISA. Cell migration was observed by a wound healing assay. Chromatin immunoprecipitation was used to detect the c-Jun binding to the CCN2 promoter.

RESULTS

AREG and FN expression colocalized in lung tissues from mice with ovalbumin-induced asthma by immunofluorescence staining. Moreover, TGF-β caused the release of AREG from A549 cells into the medium. Smad3 siRNA down-regulated AREG expression. AREG also stimulated CCN2 and FN expression, JNK and c-Jun phosphorylation, and cell migration in A549 cells. AREG small interfering (si) RNA inhibited TGF-β-induced expression of CCN2, FN, and cell migration. Furthermore, AREG-induced CCN2 and FN expression were inhibited by EGFR siRNA, a JNK inhibitor (SP600125), and an activator protein-1 (AP-1) inhibitor (curcumin). EGFR siRNA attenuated AREG-induced JNK and c-Jun phosphorylation. Moreover, SP600125 downregulated AREG-induced c-Jun phosphorylation.

CONCLUSION

These results suggested that AREG mediates the TGF-β-induced EMT in human lung epithelial cells through EGFR/JNK/AP-1 activation. Understanding the role of AREG in the EMT could foster the development of therapeutic strategies for airway remodeling in severe asthma.

Eupatilin alleviates airway remodeling via regulating phenotype plasticity of airway smooth muscle cells

Childhood asthma is a common chronic airway disease, and its severe form remains a challenge. Eupatilin is a bioactive natural flavone that has been found to possess potential anti-asthma activity. However, the roles of eupatilin in asthma remain to be elucidated. In the present study, airway smooth muscle cells (ASMCs) were applied for the in vitro investigation since their phenotype plasticity make great contribution to airway remodeling during asthma pathogenesis. Our results showed that eupatilin suppressed the transforming growth factor β1 (TGF-β1)-induced proliferation and migration of ASMCs. Exposure of ASMCs to eupatilin increased the expressions of contractile markers smooth muscle α-actin (α-SMA) and myocardin, whereas expressions of extracellular matrix (ECM) proteins type I collagen (Coll I) and fibronectin were reduced. Furthermore, eupatilin treatment reversed the activation of nuclear factor-κ B (NF-κB), signal transducer and activator of transcription 3 (STAT3) and AKT pathways caused by TGF-β1 in ASMCs. These findings suggested that eupatilin might attenuate airway remodeling via regulating phenotype plasticity of ASMCs.

Activation of AMPK suppresses S1P-induced airway smooth muscle cells proliferation and its potential mechanisms

The aims of the present study were to investigate the signaling mechanisms for sphingosine-1-phosphate (S1P)-induced airway smooth muscle cells (ASMCs) proliferation and to explore the effect of activation of adenosine monophosphate-activated protein kinase (AMPK) on S1P-induced ASMCs proliferation and its underlying mechanisms. S1P phosphorylated signal transducer and activator of transcription 3 (STAT3) through binding to S1PR_2/3, and this further sequentially up-regulated polo-like kinase 1 (PLK1) and inhibitor of differentiation 2 (ID2) protein expression. Pretreatment of cells with S1PR₂ antagonist JTE-013, S1PR₃ antagonist CAY-10444, knockdown of STAT3, PLK1 and ID2 attenuated S1P-triggered ASMCs proliferation. In addition, activation of AMPK by metformin inhibited S1P-induced ASMCs proliferation by suppressing STAT3 phosphorylation and therefore suppression of PLK1 and ID2 protein expression. Our study suggests that S1P promotes ASMCs proliferation by stimulating S1PR_2/3/STAT3/PLK1/ID2 axis, and activation of AMPK suppresses ASMCs proliferation by targeting on STAT3 signaling pathway. Activation of AMPK might benefit asthma by inhibiting airway remodeling.

Airway mechanical compression: its role in asthma pathogenesis and progression

The lung is a mechanically active organ, but uncontrolled or excessive mechanical forces disrupt normal lung function and can contribute to the development of disease. In asthma, bronchoconstriction leads to airway narrowing and airway wall buckling. A growing body of evidence suggests that pathological mechanical forces induced by airway buckling alone can perpetuate disease processes in asthma. Here, we review the data obtained from a variety of experimental models, including in vitro, ex vivo and in vivo approaches, which have been used to study the impact of mechanical forces in asthma pathogenesis. We review the evidence showing that mechanical compression alters the biological and biophysical properties of the airway epithelium, including activation of the epidermal growth factor receptor pathway, overproduction of asthma-associated mediators, goblet cell hyperplasia, and a phase transition of epithelium from a static jammed phase to a mobile unjammed phase. We also define questions regarding the impact of mechanical forces on the pathology of asthma, with a focus on known triggers of asthma exacerbations such as viral infection.

Evidence for Asthma in the Lungs of Mice Inoculated with Different Doses of Toxocara canis

Toxocara canis, a common roundworm that mainly causes toxocariasis, is a zoonotic parasite found worldwide. Humans, an accidental host, can acquire T. canis infection through accidental ingestion of T. canis-embryonated egg-contaminated food, water, and soil, and by encapsulated larvae in a paratenic host's viscera or meat. Long-term residence of T. canis larvae in a paratenic host's lungs may induce pulmonary inflammation that contributes to lung injury, airway inflammatory hyperresponsiveness, and collagen deposition in mice and clinical patients. This study intended to investigate the relationship between T. canis infection and allergic asthma in BALB/c mice inoculated with high, moderate, and low doses of T. canis eggs for a 13-week investigation. The airway hyperresponsiveness (AHR) to methacholine, collagen deposition, cytokine levels, and pathological changes in lung tissues was assessed in infected mice at weeks 1, 5, and 13 postinfection. The cell composition in bronchoalveolar lavage fluid of infected mice was assessed at weeks 5 and 13 postinfection. Compared with uninfected control mice, all groups of T. canis-infected mice exhibited significant AHR, a dose-dependent increase in eosinophilic infiltration leading to multifocal interstitial and alveolar inflammation with abundant mucus secretion, and collagen deposition in which the lesion size increased with the infective dose. Infected mice groups also showed significant expressions of eotaxin and type 2 T-helper-dominant cytokines such as interleukin (IL)-4, IL-5, and IL-13. Overall, these results suggest that T. canis larval invasion of the lungs may potentially cause pulmonary inflammatory injury and could subsequently contribute to the development of allergic manifestations such as asthma.

Periostin: An emerging biomarker for allergic diseases

Periostin is a matricellular protein as well as an extracellular matrix (ECM) protein belonging to the fasciclin family. Periostin plays important roles as a matricellular protein in the setting of allergic diseases by binding to several integrins on various cells. Since periostin is induced mainly by IL-4 and IL-13, signature type 2 cytokines, and it is highly expressed in the subepithelial regions of many chronic allergic diseases, periostin has emerged as a novel biomarker reflecting type 2 inflammation in allergic diseases. It has, moreover, been revealed that periostin has characteristics different from other type 2 biomarkers such as eosinophil count and fractional exhaled nitric oxide (FeNO), reflecting fibrosis or tissue remodeling. From this, we may say that serum periostin is a "chronic" type 2 biomarker, whereas FeNO and possibly the eosinophil count are "acute" type 2 biomarkers. In contrast, it is still uncertain how we can apply periostin measurement to the use of biologics for allergic diseases. By examining the roles of periostin in allergy and the utility and potential of periostin in developing diagnostics against allergic diseases, it is hoped that in the near future, we can develop a new strategy to treat allergic patients.

PPARγ Agonist PGZ Attenuates OVA-Induced Airway Inflammation and Airway Remodeling via RGS4 Signaling in Mouse Model

Peroxisome proliferator-activated receptor-γ (PPARγ) agonist pioglitazone (PGZ) exhibits potential protective effects in asthma. Recently, regulator of G protein 4 (RGS4) has been reported to be associated with immunological and inflammatory responses. However, no evidence has shown the influence of PPARγ on RGS4 expression in airway disorders. In this study, BALB/c mice received ovalbumin (OVA) sensitization followed by OVA intranasal challenge for 90 days to establish a chronic asthma mouse model. Accompanied with OVA challenge, the mice received administration of PPARγ agonist PGZ (10 mg/kg) intragastrically or RGS4 inhibitor CCG 63802 (0.5 mg/kg) intratracheally. Invasive pulmonary function tests were performed 24 h after last challenge. Serum, bronchoalveolar lavage fluid (BALF), and lung tissues were collected for further analyses after the mice were sacrificed. We found that PPARγ agonist PGZ administration significantly attenuated the pathophysiological features of OVA-induced asthma and increased the expression of RGS4. In addition, the attenuating effect of PGZ on airway inflammation, hyperresponsiveness (AHR), and remodeling was partially abrogated by administration of RGS4 inhibitor CCG 63802. We also found that the downregulation of RGS4 by CCG 63802 also significantly increased inflammatory cell accumulation and AHR, and increased levels of IL-4, IL-13, eotaxin, IFN-γ, and IL-17A in BALF, and total and OV-specific IgE in serum. Furthermore, the inhibitory effects of PGZ on the activations of ERK and Akt/mTOR signaling, and MMPs were apparently reversed by CCG 63802 administration. In conclusion, the protective effect of PGZ on OVA-induced airway inflammation and remodeling might be partly regulated by RGS4 expression through ERK and Akt/mTOR signaling.

Comparison of Subtyping Approaches and the Underlying Drivers of Microbial Signatures for Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a major human health problem that significantly reduces quality of life. While various microbes have been implicated, there is no clear understanding of the role they play in CRS pathogenesis. Another equally important observation made for CRS patients is that the epithelial barrier in the sinonasal cavity is defective. Finding a robust approach to subtype CRS patients would be the first step toward unravelling the pathogenesis of this heterogeneous condition. Previous work has explored stratification based on the clinical presentation of the disease (with or without polyps), inflammatory markers, pathology, or microbial composition. Comparisons between the different stratification approaches used in these studies have not been possible due to the different cohorts, analytical methods, or sample sites used. In this study, two approaches for subtyping CRS patients were compared, and the underlying drivers of the heterogeneity in CRS were also explored.

Chronic rhinosinusitis (CRS) is a heterogeneous condition characterized by persistent sinus inflammation and microbial dysbiosis. This study aimed to identify clinically relevant subgroups of CRS patients based on distinct microbial signatures, with a comparison to the commonly used phenotypic subgrouping approach. The underlying drivers of these distinct microbial clusters were also investigated, together with associations with epithelial barrier integrity. Sinus biopsy specimens were collected from CRS patients (n = 23) and disease controls (n = 8). The expression of 42 tight junction genes was evaluated using quantitative PCR together with microbiota analysis and immunohistochemistry for measuring mucosal integrity and inflammation. CRS patients clustered into two distinct microbial subgroups using probabilistic modelling Dirichlet (DC) multinomial mixtures. DC1 exhibited significantly reduced bacterial diversity and increased dispersion and was dominated by Pseudomonas, Haemophilus, and Achromobacter. DC2 had significantly elevated B cells and incidences of nasal polyps and higher numbers of Anaerococcus, Megasphaera, Prevotella, Atopobium, and Propionibacterium. In addition, each DC exhibited distinct tight junction gene and protein expression profiles compared with those of controls. Stratifying CRS patients based on clinical phenotypic subtypes (absence or presence of nasal polyps [CRSsNP or CRSwNP, respectively] or with cystic fibrosis [CRSwCF]) accounted for a larger proportion of the variation in the microbial data set than with DC groupings. However, no significant differences between CRSsNP and CRSwNP cohorts were observed for inflammatory markers, beta-dispersion, and alpha-diversity measures. In conclusion, both approaches used for stratifying CRS patients had benefits and pitfalls, but DC clustering provided greater resolution when studying tight junction impairment. Future studies in CRS should give careful consideration to the patient subtyping approach used.

IMPORTANCE Chronic rhinosinusitis (CRS) is a major human health problem that significantly reduces quality of life. While various microbes have been implicated, there is no clear understanding of the role they play in CRS pathogenesis. Another equally important observation made for CRS patients is that the epithelial barrier in the sinonasal cavity is defective. Finding a robust approach to subtype CRS patients would be the first step toward unravelling the pathogenesis of this heterogeneous condition. Previous work has explored stratification based on the clinical presentation of the disease (with or without polyps), inflammatory markers, pathology, or microbial composition. Comparisons between the different stratification approaches used in these studies have not been possible due to the different cohorts, analytical methods, or sample sites used. In this study, two approaches for subtyping CRS patients were compared, and the underlying drivers of the heterogeneity in CRS were also explored.

Extracts of Coleus forskohlii relieves cough and asthma symptoms via modulating inflammation and the extracellular matrix

Asthma is characterized by airway inflammatory infiltration, which leads to airway remodeling and airway hyperreactivity. Coleus forskohlii (CFK) has been used to treat asthma, however, the mechanism involved is not clear. To explore the antiasthma mechanism of extracts of Coleus forskohlii (ECFK), guinea pigs were administered with a spray of phosphoric acid histamine, and rats were sensitized with ovalbumin (OVA). Hematoxylin and eosin staining (H&E) were used to evaluate pathological changes in lung tissue. Enzyme-linked immunosorbent assay (ELISA) was used to determine cytokine levels in serum and bronchoalveolar lavage fluid (BALF). Immunohistochemistry and Western blot analysis were used to assess the expression of intercellular cell adhesion molecule-1 (ICAM-1), phosphorylation of p65 (p-p65), matrix metallopeptidase 9 (MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1). After ECFK treatment, the asthma incubation period of guinea pigs was significantly prolonged. The H&E results showed that the number of eosinophils in the 12.8 g/kg ECFK group was significantly lower when compared with the control group. Moreover, ELISA results demonstrated that interleukin (IL)-4, IL-5, and IL-17 in serum and BALF were significantly decreased, and interferon-γ (IFN-γ) and IL-10 were increased after ECFK treatment. In addition, ECFK treatment resulted in downregulation of ICAM-1, p-p65, MMP-9, and TIMP-1 in lung tissue after being sensitized by OVA. In conclusion, our findings indicated that ECFK significantly alleviated OVA-induced inflammatory infiltration and airway remodeling in asthma. This study laid a theoretical foundation for the clinical use of ECFK.

TSLP promotes asthmatic airway remodeling via p38-STAT3 signaling pathway in human lung fibroblast

PURPOSE

Thymic stromal lymphopoietin (TSLP) acts as a critical cytokine involved in asthmatic airway remodeling. Our study aimed to characterize the crosstalk between airway epithelial cells and fibroblasts regulated by TSLP through the signaling pathways of Mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3).

MATERIALS AND METHODS

Human biopsy specimens and lung tissues from mice were stained with hematoxylin and eosin (H&E) and immunohistochemistry. Human lung fibroblasts were stimulated with human recombinant TSLP. The protein expression of phosphorylation of STAT3 (p-STAT3) and phosphorylation of MAPK as well as the expression of collagen I and alpha-smooth muscle actin (α-SMA) were detected by Western blotting and immunofluorescence. Co-culture was performed to detect the influence of TSLP secreted by airway epithelial cells on fibroblasts. An ovalbumin (OVA)-induced asthmatic murine model was established with or without intraperitoneal injection of SB203580 (inhibitor of p-38). Protein expression in lung tissue was detected by immunohistochemistry and western blotting.

RESULT

TSLP could activate MAPK in HLF-1. SB203580 could inhibit the activation of p38, attenuate phosphorylation of STAT3, and decrease the expression of collagen I and α-SMA consequently in human fibroblasts. Co-culture demonstrated that TSLP secreted by epithelial cells could promote the expression of collagen I and α-SMA and aggravates airway remodeling in fibroblasts. In vivo, expression of TSLP, collagen I, α-SMA, p-p38 and p-STAT3 was upregulated in airway tissue of OVA-challenged mice and downregulated in mice which were treated by SB203580. The tissue staining showed that airway structure change was attenuated by SB203580 compared with OVA challenged mice as well.

CONCLUSIONS

TSLP might promote asthmatic airway remodeling via p38 MAPK-STAT3 axis activation and the crosstalk between airway epithelial cells and fibroblasts could aggravate remodeling. Blockade of p38 could alleviate airway remodeling which might provide a new therapeutic target for asthma.

Fibroblast-to-myofibroblast transition in bronchial asthma

Bronchial asthma is a chronic inflammatory disease in which bronchial wall remodelling plays a significant role. This phenomenon is related to enhanced proliferation of airway smooth muscle cells, elevated extracellular matrix protein secretion and an increased number of myofibroblasts. Phenotypic fibroblast-to-myofibroblast transition represents one of the primary mechanisms by which myofibroblasts arise in fibrotic lung tissue. Fibroblast-to-myofibroblast transition requires a combination of several types of factors, the most important of which are divided into humoural and mechanical factors, as well as certain extracellular matrix proteins. Despite intensive research on the nature of this process, its underlying mechanisms during bronchial airway wall remodelling in asthma are not yet fully clarified. This review focuses on what is known about the nature of fibroblast-to-myofibroblast transition in asthma. We aim to consider possible mechanisms and conditions that may play an important role in fibroblast-to-myofibroblast transition but have not yet been discussed in this context. Recent studies have shown that some inherent and previously undescribed features of fibroblasts can also play a significant role in fibroblast-to-myofibroblast transition. Differences observed between asthmatic and non-asthmatic bronchial fibroblasts (e.g., response to transforming growth factor β, cell shape, elasticity, and protein expression profile) may have a crucial influence on this phenomenon. An accurate understanding and recognition of all factors affecting fibroblast-to-myofibroblast transition might provide an opportunity to discover efficient methods of counteracting this phenomenon.

Tregitope-linked Refined Allergen Vaccines for Immunotherapy in Cockroach Allergy

Allergen-specific immunotherapy (AIT) facilitates long-term resolution of allergic morbidity resulting in reduced drug use and increased refractoriness to new sensitization. AIT effectiveness has been demonstrated in seasonal and perennial allergies, and insect stings. However, data and studies in AIT relative to cockroach (CR) allergy are relatively scarce. In this study, mice allergic to American CR (Periplaneta americana) were treated with a liposome (L)-entrapped vaccine made of mouse Tregitope289-Per a 9 of the CR, Tregitope167-Per a 9, or Per a 9 alone - or placebo. Allergic mice that received an individual vaccine intranasally had reduced Th2 response, reduced lung inflammation, and reduced respiratory tissue remodeling. However, only L-Tregitope289-Per a 9 and L-Tregitope167-Per a 9 induced expression of immunosuppressive cytokine genes (IL-10, TGF-β, and IL-35 for L-Tregitope289-Per a 9, and IL-10 and TGF-β for L-Tregitope167-Per a 9) and increment of idoleamine-2,3-dioxygenase 1 (IDO1), indicating that these vaccines caused allergic disease suppression and reversal of respiratory tissue remodeling via generation of regulatory lymphocytes. Liposome entrapped-recombinant Per a 9 (L-Per a 9) did not cause upregulation of immunosuppressive cytokine genes and IDO1 increment; rather, L-Per a 9 induced high expression of IFN-γ in lungs of treated mice, which resulted in mitigation of allergic manifestations. This study provides compelling evidence that both liposome-entrapped vaccines made of single refined major allergen alone and single refined major allergen linked with Tregitopes are effective for reducing allergen-mediated respiratory tissue inflammation and remodeling, but through different mechanisms.

The pertussis hypothesis: Bordetella pertussis colonization in the etiology of asthma and diseases of allergic sensitization

Decades of peer reviewed evidence demonstrate that: 1)Bordetellapertussisand pertussis toxin are potent adjuvants, inducing asthma and allergic sensitization in animal models of human disease, 2)Bordetella pertussisoften colonizes the human nasopharynx, and is well documented in highly pertussis-vaccinated populations and 3) in children, a history of whooping cough increases the risk of asthma and allergic sensitization disease. We build on these observations with six case studies and offer a pertussis-based explanation for the rapid rise in allergic disease in former East Germany following the fall of the Berlin Wall; the current asthma, peanut allergy, and anaphylaxis epidemics in the United States; the correlation between the risk of asthma and gross national income per capita by country; the lower risk of asthma and allergy in children raised on farms; and the reduced risk of atopy with increased family size and later sibling birth order. To organize the evidence for the pertussis hypothesis, we apply the Bradford Hill criteria to the association between Bordetella pertussisand asthma and allergicsensitization disease. We propose that, contrary to conventional wisdom that nasopharyngealBordetella pertussiscolonizing infections are harmless, subclinicalBordetella pertussiscolonization is an important cause of asthma and diseases of allergic sensitization.

Horses With Pasture Asthma Have Airway Remodeling That Is Characteristic of Human Asthma

Severe equine asthma, formerly recurrent airway obstruction (RAO), is the horse counterpart of human asthma, affecting horses maintained indoors in continental climates. Equine pasture asthma, formerly summer pasture RAO, is clinically similar but affects grazing horses during hot, humid conditions in the southeastern United States and United Kingdom. To advance translational relevance of equine pasture asthma to human asthma, histologic features of airway remodeling in human asthma were scored in lung lobes from 15 pasture asthma-affected and 9 control horses of mixed breeds. All noncartilaginous airways were scored using a standardized grading rubric (0-3) in hematoxylin and eosin (HE) and Movat's pentachrome-stained sections; 15 airways were chosen randomly from each lobe for analysis. Logistic regression identified disease, age, and lobe effects on probability of histologic outcomes. Airway smooth muscle (odds ratio [OR] = 2.5, P < .001), goblet cell hyperplasia/metaplasia (OR = 37.6, P < .0001), peribronchiolar elastic system fibers (OR = 4.2, P < .001), peribronchiolar fibrosis (OR = 3.8, P = .01), airway occlusion by mucus/inflammation (OR = 4.2, P = .04), and airway adventitial inflammation (OR = 3.0, P = .01) were significantly greater in diseased airways. A novel complex tissue disorganization, designated terminal bronchiolar remodeling, was overrepresented in diseased airways (OR = 3.7, P < .0001). Distribution of terminal bronchiolar remodeling corresponded to putative sites of air trapping in human asthma, at secondary pulmonary lobules. Age (>15 years) was an independent risk factor for increased peribronchiolar fibrosis, elastic system fibers, and terminal bronchiolar remodeling. Remodeling differed significantly between lung lobes, congruent with nonhomogeneous remodeling in human asthma. Equine pasture asthma recapitulates airway remodeling in human asthma in a manner not achieved in induced animal asthma models, endorsing its translational relevance for human asthma investigation.

Nitric oxide alters hyaluronan deposition by airway smooth muscle cells

Asthma is a chronic inflammatory disease that is known to cause changes in the extracellular matrix, including changes in hyaluronan (HA) deposition. However, little is known about the factors that modulate its deposition or the potential consequences. Asthmatics with high levels of exhaled nitric oxide (NO) are characterized by greater airway reactivity and greater evidence of airway inflammation. Based on these data and our previous work we hypothesized that excessive NO promotes the pathologic production of HA by airway smooth muscle cells (SMCs). Exposure of cultured SMCs to various NO donors results in the accumulation of HA in the form of unique, cable-like structures. HA accumulates rapidly after exposure to NO and can be seen as early as one hour after NO treatment. The cable-like HA in NO-treated SMC cultures supports the binding of leukocytes. In addition, NO produced by murine macrophages (RAW cells) and airway epithelial cells also induces SMCs to produce HA cables when grown in co-culture. The modulation of HA by NO appears to be independent of soluble guanylate cyclase. Taken together, NO-induced production of leukocyte-binding HA by SMCs provides a new potential mechanism for the non-resolving airway inflammation in asthma and suggests a key role of non-immune cells in driving the chronic inflammation of the submucosa. Modulation of NO, HA and the consequent immune cell interactions may serve as potential therapeutic targets in asthma.

Saponin-enriched extract of Asparagus cochinchinensis alleviates airway inflammation and remodeling in ovalbumin-induced asthma model

Asthma is a chronic inflammatory disease characterized by T-lymphocyte and eosinophil infiltration, mucus overproduction and airway hyper-responsiveness. The present study examined the therapeutic effects and action mechanism of a saponin-enriched extract of Asparagus cochinchinensis (SEAC) on airway inflammation and remodeling in an ovalbumin (OVA)-induced asthma model. To accomplish this, alterations of the nitric oxide (NO) level, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression levels, as well as variations in immune cell numbers, immunoglobulin E (IgE) concentration, histopathological structure and inflammatory cytokine levels were measured in lipopolysaccharide (LPS)-activated RAW264.7 cells or an OVA-induced mouse model of asthma treated with SEAC. The concentration of NO and mRNA levels of COX-2 and iNOS were significantly decreased in the SEAC + LPS-treated RAW264.7 cells compared with the vehicle + LPS-treated RAW264.7 cells. Additionally, in the OVA-induced asthma model, the number of immune cells in the bronchoalveolar lavage fluid, the concentration of OVA-specific IgE, the infiltration of inflammatory cells, the bronchial thickness and the levels of the inflammatory mediators interleukin-4 (IL-4), IL-13 and COX-2 were significantly lower in the OVA + SEAC-treated group compared with the OVA + vehicle-treated group. In addition, a significant reduction in goblet cell hyperplasia, peribronchiolar collagen layer thickness and VEGF expression for airway remodeling was detected in the OVA + SEAC-treated group compared with the OVA + vehicle-treated group. These findings indicate that SEAC is a suppressor of airway inflammation and remodeling, and may therefore be useful as an anti-inflammatory drug for the treatment of asthma.

An Official American Thoracic Society Research Statement: Current Challenges Facing Research and Therapeutic Advances in Airway Remodeling

BACKGROUND

Airway remodeling (AR) is a prominent feature of asthma and other obstructive lung diseases that is minimally affected by current treatments. The goals of this Official American Thoracic Society (ATS) Research Statement are to discuss the scientific, technological, economic, and regulatory issues that deter progress of AR research and development of therapeutics targeting AR and to propose approaches and solutions to these specific problems. This Statement is not intended to provide clinical practice recommendations on any disease in which AR is observed and/or plays a role.

METHODS

An international multidisciplinary group from within academia, industry, and the National Institutes of Health, with expertise in multimodal approaches to the study of airway structure and function, pulmonary research and clinical practice in obstructive lung disease, and drug discovery platforms was invited to participate in one internet-based and one face-to-face meeting to address the above-stated goals. Although the majority of the analysis related to AR was in asthma, AR in other diseases was also discussed and considered in the recommendations. A literature search of PubMed was performed to support conclusions. The search was not a systematic review of the evidence.

RESULTS

Multiple conceptual, logistical, economic, and regulatory deterrents were identified that limit the performance of AR research and impede accelerated, intensive development of AR-focused therapeutics. Complementary solutions that leverage expertise of academia and industry were proposed to address them.

CONCLUSIONS

To date, numerous factors related to the intrinsic difficulty in performing AR research, and economic forces that are disincentives for the pursuit of AR treatments, have thwarted the ability to understand AR pathology and mechanisms and to address it clinically. This ATS Research Statement identifies potential solutions for each of these factors and emphasizes the importance of educating the global research community as to the extent of the problem as a critical first step in developing effective strategies for: (1) increasing the extent and impact of AR research and (2) developing, testing, and ultimately improving drugs targeting AR.

Interstitial collagen turnover during airway remodeling in acute and chronic experimental asthma

Asthma airway remodeling is characterized by the thickening of the basement membrane (BM) due to an increase in extracellular matrix (ECM) deposition, which contributes to the irreversibility of airflow obstruction. Interstitial collagens are the primary ECM components to be increased during the fibrotic process. The aim of the present study was to examine the interstitial collagen turnover during the course of acute and chronic asthma, and 1 month after the last exposure to the allergen. Guinea pigs sensitized to ovalbumin (OVA) and exposed to 3 further OVA challenges (acute model) or 12 OVA challenges (chronic model) were used as asthma experimental models. A group of animals from either model was sacrificed 1 h or 1 month after the last OVA challenge. Collagen distribution, collagen content, interstitial collagenase activity and matrix metalloproteinase (MMP)-1, MMP-13 and tissue inhibitor of metalloproteinase (TIMP)-1 protein expression levels were measured in the lung tissue samples from both experimental models. The results revealed that collagen deposit in bronchiole BM, adventitial and airway smooth muscle layers was increased in both experimental models as well as lung tissue collagen concentration. These structural changes persisted 1 month after the last OVA challenge. In the acute model, a decrease in collagenase activity and in MMP-1 concentration was observed. Collagenase activity returned to basal levels, and an increase in MMP-1 and MMP-13 expression levels along with a decrease in TIMP-1 expression levels were observed in animals sacrificed 1 month after the last OVA challenge. In the chronic model, there were no changes in collagenase activity or in MMP-13 concentration, although MMP-1 expression levels increased. One month later, an increase in collagenase activity was observed, although MMP-1 and TIMP-1 levels were not altered. The results of the present study suggest that even when the allergen challenges were discontinued, and collagenase activity and MMP-1 expression increased, fibrosis remained, contributing to the irreversibility of bronchoconstriction.

Vitamin D and Lung Function Decline in Adults With Asthma: The HUNT Study

We investigated whether low 25-hydroxyvitamin D (25(OH)D) levels were associated with more lung function decline in adults with asthma and whether this association was modified by smoking status or inhaled corticosteroid (ICS) use. We analyzed data on 395 adults with asthma from the Nord-Trøndelag Health Study (1995-2008), Norway. Plasma 25(OH)D and lung function were measured at baseline, and lung function measurements were repeated at follow-up, approximately 11 years later. Linear regression was used to estimate lung function decline. Participants with low 25(OH)D (<50 nmol/L) had more decline in lung function measurements for forced expiratory volume in 1 second (FEV1) (388 mL), forced vital capacity (298 mL), and the FEV1/forced vital capacity ratio (3.7%) over the follow-up, compared with those with high 25(OH)D (≥50 nmol/L) who declined 314 mL, 246 mL, and 3.0%, respectively (P = 0.08, 0.30, and 0.23, respectively). The associations were stronger in never smokers and non-ICS users. In never smokers, low 25(OH)D levels were associated with more decline in FEV1 (445 vs. 222 mL) (P = 0.01). In non-ICS users, low 25(OH)D levels were associated with more decline in FEV1 (467 vs. 320 mL) (P = 0.02). Low serum 25(OH)D levels were weakly associated with more lung function decline in adults with asthma, and stronger associations were observed in never smokers and non-ICS users.

Kaempferol Inhibits Endoplasmic Reticulum Stress-Associated Mucus Hypersecretion in Airway Epithelial Cells And Ovalbumin-Sensitized Mice

Mucus hypersecretion is an important pathological feature of chronic airway diseases, such as asthma and pulmonary diseases. MUC5AC is a major component of the mucus matrix forming family of mucins in the airways. The initiation of endoplasmic reticulum (ER)-mediated stress responses contributes to the pathogenesis of airway diseases. The present study investigated that ER stress was responsible for airway mucus production and this effect was blocked by the flavonoid kaempferol. Oral administration of ≥10 mg/kg kaempferol suppressed mucus secretion and goblet cell hyperplasia observed in the bronchial airway and lung of BALB/c mice sensitized with ovalbumin (OVA). TGF-β and tunicamycin promoted MUC5AC induction after 72 h in human bronchial airway epithelial BEAS-2B cells, which was dampened by 20 μM kaempferol. Kaempferol inhibited tunicamycin-induced ER stress of airway epithelial cells through disturbing the activation of the ER transmembrane sensor ATF6 and IRE1α. Additionally, this compound demoted the induction of ER chaperones such as GRP78 and HSP70 and the splicing of XBP-1 mRNA by tunicamycin. The in vivo study further revealed that kaempferol attenuated the induction of XBP-1 and IRE1α in epithelial tissues of OVA-challenged mice. TGF-β and tunicamycin induced TRAF2 with JNK activation and such induction was deterred by kaempferol. The inhibition of JNK activation encumbered the XBP-1 mRNA splicing and MUC5AC induction by tunicamycin and TGF-β. These results demonstrate that kaempferol alleviated asthmatic mucus hypersecretion through blocking bronchial epithelial ER stress via the inhibition of IRE1α-TRAF2-JNK activation. Therefore, kaempferol may be a potential therapeutic agent targeting mucus hypersecretion-associated pulmonary diseases.

Astragalin inhibits autophagy-associated airway epithelial fibrosis

Background

Fibrotic remodeling of airway and lung parenchymal compartments is attributed to pulmonary dysfunction with an involvement of reactive oxygen species (ROS) in chronic lung diseases such as idiopathic pulmonary fibrosis and asthma.

Methods

The in vitro study elucidated inhibitory effects of astragalin, kaempferol-3-O-glucoside from leaves of persimmon and green tea seeds, on oxidative stress-induced airway fibrosis. The in vivo study explored the demoting effects of astragalin on epithelial to mesenchymal transition in BALB/c mice sensitized with ovalbumin (OVA).

Results

The exposure of 20 μM H₂O₂ for 72 h accelerated E-cadherin loss and vimentin induction in airway epithelial BEAS-2B cells, which was reversed by non-toxic astragalin at 1–20 μM. Astragalin allayed the airway tissue levels of ROS and vimentin enhanced by OVA challenge. Collagen type 1 production increased in H₂O₂–exposed epithelial cells and collagen fiber deposition was observed in OVA-challenged mouse airways. This study further investigated that the oxidative stress-triggered autophagic regulation was responsible for inducing airway fibrosis. H₂O₂ highly enhanced the expression induction of the autophagy-related beclin-1 and light chains 3A/B (LC3A/B) within 4 h and astragalin blocked such induction by H₂O₂. This compound deterred the ROS-promoted autophagosome formation in BEAS-2B cells. Consistently, in OVA-sensitized mice the expression of beclin-1 and LC3A/B was highly induced, and oral administration of astragalin suppressed the autophagosome formation with inhibiting the induction of these proteins in OVA-challenged airway subepithelium. Induction of autophagy by spermidine influenced the epithelial induction of E-cadherin and vimentin that was blocked by treating astragalin.

Conclusion

These results demonstrate that astragalin can be effective in allaying ROS-promoted bronchial fibrosis through inhibiting autophagosome formation in airways.

Comparative study of the effects of fetal bovine serum versus horse serum on growth and differentiation of primary equine bronchial fibroblasts

BACKGROUND

Airway fibroblasts have become a critical addition to all facets of structural lung tissue changes such as in human asthma and chronic obstructive pulmonary disease, but little is known about their role in the equine recurrent airway obstruction, a disease that resembles to the human asthma. Since the equine bronchial fibroblasts (EBF) have not been isolated and characterized yet, the use of defined medium was investigated.

RESULTS

Primary EBF were cultured on non-collagen coated flasks without serum or in the presence of fetal bovine serum (FBS) or horse serum (HS) or in serum depleted medium. EBF cultured in serum-free basal media and those serum deprived were not able to proliferate and even exhibited considerable cell death. In media containing FBS or HS, proliferation of the cells was reproducible between different primary cultures and cells demonstrated expression of vimentin. Large variations were found in the ability of FBS and HS to support growth and differentiation of EBF in monolayer culture. Indications of growth-promoting actions, increasing passage number as well as maintaining fibroblast morphology were found rather in FBS than in HS. EBF culturing in HS needed longer doubling and confluence time. The protein content of the cell pellets was higher in EBF cultured in medium containing HS than FBS. Alpha-smooth muscle actin seemed to be less expressed in EBF cultured in medium containing FBS than those in HS.

CONCLUSIONS

In sum, serum addition to basal EBF medium enhanced EBF differentiation into myofibroblasts, and these findings are useful to develop in vitro fibroblast culture models that mimic in vivo physiological processes and to study airway disease mechanisms and remodeling.

Link between vitamin D and airway remodeling

In the last decade, many epidemiologic studies have investigated the link between vitamin D deficiency and asthma. Most studies have shown that vitamin D deficiency increases the risk of asthma and allergies. Low levels of vitamin D have been associated with asthma severity and loss of control, together with recurrent exacerbations. Remodeling is an early event in asthma described as a consequence of production of mediators and growth factors by inflammatory and resident bronchial cells. Consequently, lung function is altered, with a decrease in forced expiratory volume in one second and exacerbated airway hyperresponsiveness. Subepithelial fibrosis and airway smooth muscle cell hypertrophy are typical features of structural changes in the airways. In animal models, vitamin D deficiency enhances inflammation and bronchial anomalies. In severe asthma of childhood, major remodeling is observed in patients with low vitamin D levels. Conversely, the antifibrotic and antiproliferative effects of vitamin D in smooth muscle cells have been described in several experiments. In this review, we briefly summarize the current knowledge regarding the relationship between vitamin D and asthma, and focus on its effect on airway remodeling and its potential therapeutic impact for asthma.

Inhibition of airway epithelial-to-mesenchymal transition and fibrosis by kaempferol in endotoxin-induced epithelial cells and ovalbumin-sensitized mice

Chronic airway remodeling is characterized by structural changes within the airway wall, including smooth muscle hypertrophy, submucosal fibrosis and epithelial shedding. Epithelial-to-mesenchymal transition (EMT) is a fundamental mechanism of organ fibrosis, which can be induced by TGF-β. In the in vitro study, we investigated whether 1-20 μM kaempferol inhibited lipopolysaccharide (LPS)-induced bronchial EMT in BEAS-2B cells. The in vivo study explored demoting effects of 10-20 mg/kg kaempferol on airway fibrosis in BALB/c mice sensitized with ovalbumin (OVA). LPS induced airway epithelial TGF-β1 signaling that promoted EMT with concurrent loss of E-cadherin and induction of α-smooth muscle actin (α-SMA). Nontoxic kaempferol significantly inhibited TGF-β-induced EMT process through reversing E-cadherin expression and retarding the induction of N-cadherin and α-SMA. Consistently, OVA inhalation resulted in a striking loss of epithelial morphology by displaying myofibroblast appearance, which led to bronchial fibrosis with submucosal accumulation of collagen fibers. Oral administration of kaempferol suppressed collagen deposition, epithelial excrescency and goblet hyperplasia observed in the lung of OVA-challenged mice. The specific inhibition of TGF-β entailed epithelial protease-activated receptor-1 (PAR-1) as with 20 μM kaempferol. The epithelial PAR-1 inhibition by SCH-79797 restored E-cadherin induction and deterred α-SMA induction, indicating that epithelial PAR-1 localization was responsible for resulting in airway EMT. These results demonstrate that dietary kaempferol alleviated fibrotic airway remodeling via bronchial EMT by modulating PAR1 activation. Therefore, kaempferol may be a potential therapeutic agent targeting asthmatic airway constriction.

Transforming growth factor-β1 induces bronchial epithelial cells to mesenchymal transition by activating the Snail pathway and promotes airway remodeling in asthma

Airway remodeling is characterized by airway wall thickening, subepithelial fibrosis, increased smooth muscle mass, angiogenesis and an increase in mucous glands, which may lead to a chronic and obstinate asthma with pulmonary function depression. In the present study, we observed substantially thickened lung tissue with extensive fibrosis in ovalbumin-sensitized mice, which was interrelated with transforming growth factor-β1 (TGF-β1) expression in bronchoalveolar lavage fluid. In vitro experiments further demonstrated that TGF-β1 resulted in epithelial-mesenchymal transition (EMT) in bronchial epithelial cells, which was characterized by the expected decrease in E-cadherin expression and the increase in vimentin and α-smooth muscle actin expression, as well as the associated increase in Snail expression at mRNA and protein levels. Furthermore, the downregulation of Snail by small interfering RNA (siRNA) attenuated the TGF-β1‑induced EMT-like phenotype. Of note, a significantly increased synthesis of fibronectin was observed following TGF-β1 treatment, which further supported the hypothesis that EMT is a pivotal factor in peribronchial fibrosis. In combination, the results indicated that myofibroblasts deriving from bronchial epithelial cells via EMT may contribute to peribronchial fibrosis and that Snail may be an important factor in this phenomenon.

Could FEV₁ decline have a role in daily clinical practice for asthma monitoring?

OBJECTIVE

The aim of this review was to understand whether FEV1 decline measured during the follow-up of asthmatic subjects (FEV1 variation between two different measurements at a distance of at least 5 years) may have a role in their management.

METHODS

Articles, commentaries and reviews relating to the topic were searched in PubMed.

RESULTS

Patients with an accelerated FEV1 decline (>30 ml/year) may be either steroid-resistant/difficult-to-treat asthmatics or not adequately treated because they are either under-perceivers or poorly adherent to their therapy. Sometimes they may be unable to use devices correctly. Untreated rhinitis and incorrect lifestyle (obesity status, a high-fat diet and lack of exercise) must be considered when facing a pulmonary function decline. Identifying asthmatics with an accelerated FEV1 decline, even with well controlled symptoms, may allow us to make possible treatment adjustments or to remove potentially harmful environmental exposure and suggest a correct lifestyle. Depending on FEV1 decline severity, we may detect different asthma phenotypes. One type is characterized by no/low lung function reduction. Among moderate/severe 'declining' subjects, there may be a group that might be responsive to treatment and a second one with a quicker loss in lung function that may be unresponsive to therapy.

CONCLUSION

FEV1 decline calculation should be assessed early in clinical practice over the course of time in order to make all possible variations in treatment, environmental exposure and lifestyle more efficacious overall for declining subjects responsive to anti-inflammatory therapy. Further studies are necessary to validate this approach to asthma.

A role for WNT1-inducible signaling protein-1 in airway remodeling in a rat asthma model

Over-expression of WISP1 has been described in multi-organ fibrosis and tissue remodeling. Moreover, it has recently been found that polymorphism of WISP1 gene is related with the change of lung function in asthmatic subjects. Therefore, we hypothesized that WISP1 might be closely linked to occurrence and development of asthmatic airway remodeling. Aim of this study was to examine the roles of WISP1 in an asthmatic model with airway remodeling and assess the specific effects of WISP1 on human lung fibroblast in vitro. Animal models were developed by challenged with ovalbumin. The levels of WISP1 expression in animal models were assessed by real-time PCR and immunohistochemistry. To examine the specific effects of WISP1 on airway remodeling, WISP1 was depleted by neutralizing α-WISP1 antibodies in vivo. Moreover, human lung fibroblast (HFL-1) was challenged with WISP1 in the presence and absence of SH-5 in vitro. Our study showed that OVA exposure increased the levels of WISP1 expression in a rat asthma model. WISP1 depletion could partially inhibit OVA-induced airway remodeling. In vitro, WISP1-treated HFL-1 cells presented abnormal proliferation and over-expression of Col1a1 and Fn1. However, WISP1-induced collagen release from HFL-1 cells could be attenuated by pretreatment with an Akt inhibitor. Moreover, the levels of p-Akt and p-GSK-3β in WISP1-treated HFL-1 cells were also significantly elevated. In summary, WISP1 might initiate and perpetuate the pathological remodeling of asthma by inducing fibroblast proliferation and ECM deposition. The specific effects of WISP1 were likely due to activation of pulmonary Akt/GSK-3β signaling.

Vitamin D deficiency and severe asthma

Vitamin D has received tremendous amount of attention recently due to the ever-increasing reports of association between vitamin D deficiency and a wide range of conditions, from cancer to fertility to longevity. The fascination of disease association with vitamin D deficiency comes from the relatively easy solution to overcome such a risk factor, that is, either by increase in sun exposure and/or diet supplementation. Many reviews have been written on a protective role of vitamin D in asthma and related morbidities; here, we will summarize the epidemiological evidence supporting a role of vitamin D against hallmark features of severe asthma, such as airway remodeling and asthma exacerbations. Furthermore, we discuss data from in vitro and in vivo studies which provide insights on the potential mechanisms of how vitamin D may protect against severe asthma pathogenesis and how vitamin D deficiency may lead to the development of severe asthma. Approximately 5-15% of asthmatic individuals suffer from the more severe forms of disease in spite of aggressive therapies and they are more likely to have irreversible airflow obstruction associated with airway remodeling. At present drugs commonly used to control asthma symptoms, such as corticosteroids, do not significantly reverse or reduce remodeling in the airways. Hence, if vitamin D plays a protective role against the development of severe asthma, then the most effective therapy may simply be a healthy dose of sunshine.

Effects of interleukin-9 blockade on chronic airway inflammation in murine asthma models

Purpose

Asthma is a chronic inflammatory disease of the airways associated with structural changes and airway remodeling. Interleukin (IL)-9 has pleiotropic effects on both inflammatory cells and airway structural cells, which are involved in asthma pathogenesis. We evaluated the effects of IL-9 blockade on chronic airway inflammation.

Methods

Acute airway inflammation was induced in Balb/c mice using aerosolized ovalbumin (OVA), whereas chronic asthma was induced by OVA exposure for 5 weeks with anti-IL-9 or isotype-matched antibody (Ab) treatment during the OVA challenge. Inflammatory cells in bronchoalveolar lavage fluid (BALF) were counted and lung tissues were stained to detect cellular infiltration, mucus deposition, and collagen accumulation. The levels of interferon (IFN)-γ, IL-4, IL-5, IL-9, IL-17, and immunoglobulin E (IgE) in BALF were measured using enzyme linked immunosorbent assays, and profiles of inflammatory cells and subsets of T helper (Th) cells were analyzed using flow cytometry.

Results

IL-9, IL-17, and IFN-γ levels were significantly increased in the chronic group compared to the acute asthma group. However, the number of IL-9-positive cells was not affected, with a decrease in Th17 cells in OVA-challenged caspase-1 knockout mice. Numbers of eosinophils, neutrophils, B cells, mast cells, and Th17 cells decreased after administration of anti-IL-9 Ab. Total IgE, IL-5, IL-9, and IL-17 levels were also lower in the anti-IL-9 group.

Conclusions

Our results suggest that anti-IL-9 Ab treatment inhibits pulmonary infiltration of inflammatory cells and cytokine production, especially IL-17. These results provide a basis for the use of an anti-IL-9 Ab to combat IL-17-mediated airway inflammation.

Sputum hyaluronan and versican in severe eosinophilic asthma

BACKGROUND

We examined levels of hyaluronan, a matrix glycosaminoglycan and versican, a matrix proteoglycan, in the sputum of asthmatics treated with mepolizumab (anti-IL-5 monoclonal antibody) versus placebo to evaluate the utility of these measurements as possible biomarkers of asthma control and airway remodeling.

METHODS

Patients with severe, prednisone-dependent asthma received either mepolizumab or placebo as described in a previously published randomized, double-blind, placebo-controlled study. We measured hyaluronan and versican levels by enzyme-linked immunosorbent assay in sputum collected before and after the 16-week treatment phase. Patients underwent a predefined prednisone tapering schedule if they remained exacerbation free, and sputum eosinophil percentage, asthma control questionnaire (ACQ) and spirometry were monitored.

RESULTS

After 6 months of mepolizumab therapy and prednisone tapering, there was a significant increase in sputum hyaluronan in the placebo group compared with baseline (p = 0.003). In contrast, there was a significant decrease in sputum hyaluronan in the active treatment group compared with placebo (p = 0.007), which correlated with improvements in percent forced expiratory volume in 1 s (FEV1%) (p = 0.001) and ACQ scores (p = 0.009) as well as a decrease in sputum eosinophils (p = 0.02). There was a nonsignificant increase in sputum versican in the placebo group (p = 0.16), a decrease in the mepolizumab group (p = 0.13) and a significant inverse correlation between versican reduction and FEV1% improvement (p = 0.03).

CONCLUSIONS

Sputum hyaluronan values are reduced with mepolizumab therapy and correlate with improved clinical and spirometry values, suggesting this measurement may serve as a noninvasive biomarker of asthma control.

Combination therapy with relaxin and methylprednisolone augments the effects of either treatment alone in inhibiting subepithelial fibrosis in an experimental model of allergic airways disease

Although CSs (corticosteroids) demonstrate potent effects in the control of airway inflammation in asthma, many patients continue to experience symptoms and AHR (airway hyper-responsiveness) despite optimal treatment with these agents, probably due to progressive airway remodelling. Identifying novel therapies that can target airway remodelling and/or airway reactivity may improve symptom control in these patients. We have demonstrated previously that the anti-fibrotic hormone RLN (relaxin) can reverse airway remodelling (epithelial thickening and subepithelial fibrosis) and AHR in a murine model of AAD (allergic airways disease). In the present study, we compared the effects of RLN with a CS (methylprednisolone) on airway remodelling and AHR when administered independently or in combination in the mouse AAD model. Female mice at 6-8 weeks of age were sensitized and challenged to OVA (ovalbumin) over a 9-week period and treated with methylprednisolone, RLN, a combination of both treatments or vehicle controls. Methylprednisolone was administered intraperitoneally on the same day as nebulization for 6 weeks, whereas recombinant human RLN-2 was administered via subcutaneously implanted osmotic mini-pumps from weeks 9-11. RLN or methylprednisolone alone were both able to significantly decrease subepithelial thickness and total lung collagen deposition; whereas RLN but not methylprednisolone significantly decreased epithelial thickness and AHR. Additionally, combination therapy with CS and RLN more effectively reduced subepithelial collagen thickness than either therapy alone. These findings demonstrate that RLN can modulate a broader range of airway remodelling changes and AHR than methylprednisolone and the combination of both treatments offers enhanced control of subepithelial fibrosis.

Beneficial effects of erythropoietin on airway histology in a murine model of chronic asthma

BACKGROUND

Erythropoietin (EPO) is originally defined as a haematopoietic growth factor, but also has anti-inflammatory effects through cytokine modulation. This anti-inflammatory and cytokine modulating effect has not been investigated for the treatment of asthma. We aimed to determine the beneficial effects of erythropoietin on lung histology of murine model of chronic asthma.

METHODS

Thirty-five BALB/c mice were divided into five groups: I; II; III; IV; and control group. All groups except control group were sensitised and challenged with ovalbumin. Mice with experimentally induced asthma in Group I received saline; Group II EPO 500IU/kg; Group III EPO 1000IU/kg; and Group IV dexamethasone 1mg/kg intraperitoneally once a day in the last five days of the challenge period. Animals were sacrificed 24h after the last administration of study drugs. Histological findings of airways were evaluated by light and electron microscopic examination.

RESULTS

All histological parameters of asthma in the group treated with a high dose of EPO (Group III) were significantly ameliorated when compared with the group treated with saline (Group I). In comparison to the group treated with low dose of EPO (Group II) and the group treated with saline (Group I), basement membrane thicknesses and number of mast cells were significantly lower in the group treated with low dose of EPO (Group II). All histological parameters were similar between the group treated with high dose of EPO (Group III) and the group treated with dexamethasone (Group IV) except higher number of mast cells in the group treated with high dose of EPO (Group III). Additionally, the results of all histological parameters in the group treated with high dose of EPO (Group III) were significantly better when compared with the group treated with low dose of EPO (Group II).

CONCLUSIONS

We found that EPO ameliorated histological changes of chronic murine model of asthma. Further studies are needed to evaluate the efficacy of EPO in the treatment of asthma.

The who, where, and when of IgE in allergic airway disease

Allergic asthma and allergic rhinitis/conjunctivitis are characterized by a T(H)2-dominated immune response associated with increased serum IgE levels in response to inhaled allergens. Because IgE is a key player in the induction and maintenance of allergic inflammation, it represents a prime target for therapeutic intervention. However, our understanding of IgE biology remains fragmentary. This article puts together our current knowledge on IgE in allergic airway diseases with a special focus on the identity of IgE-secreting cells ("who"), their location ("where"), and the circumstances in which they are induced ("when"). We further consider the therapeutic implications of the insights gained.

Chronic hepatitis C virus infection is associated with more severe asthma

BACKGROUND

Chronic hepatitis C virus (HCV) infection causes intra- and extra-hepatic complications. The elimination of HCV has been reported to be beneficial for asthmatic patients with HCV infection. Therefore, we hypothesized that chronic HCV infection might be associated with the severity of asthma.

METHODS

Asthmatic patients were prospectively enrolled from 13 outpatient settings. Hepatitis B surface (HBs) antigen and HCV-RNA were measured at the time of enrollment and evaluated along with the clinical characteristics of the patients including the age, sex, duration of asthma, atopic status, smoking history, and treatment step according to the Global Initiative for Asthma guideline.

RESULTS

Of 1327 asthmatic patients, 1258 patients (94.8%) were treated with inhaled corticosteroids, 18 patients were positive for HBs antigen (1.4%), and 32 patients (2.4%) were positive for HCV-RNA. When compared with HCV-RNA-negative patients, HCV-RNA-positive patients required significantly more drugs for the treatment of asthma. No such relationship was observed in patients with positive HBs antigen. A multivariate logistic regression analysis showed that the male sex, a long duration of asthma, status as a current smoker, and HCV-RNA positivity were independently associated with more severe asthma.

CONCLUSIONS

These results suggest that chronic HCV infection is an independent factor that predisposes asthmatic patients to more severe asthma. The evaluation of chronic HCV infection may be helpful for the management of severe asthmatic patients without obvious factors associated with severe asthma.

Hyaluronan deposition and correlation with inflammation in a murine ovalbumin model of asthma

Asthma is a chronic inflammatory disease of the airways characterized by airway remodeling, which includes changes in the extracellular matrix (ECM). However the role of the ECM in mediating these changes is poorly understood. Hyaluronan (HA), a major component of the ECM, has been implicated in asthma as well as in many other biological processes. Our study investigates the processes involved in HA synthesis, deposition, localization and degradation during an acute and chronic murine model of ovalbumin (OVA)-induced allergic pulmonary inflammation. Mice were sensitized, challenged to OVA and sacrificed at various time points during an 8-week challenge protocol. Bronchoalveolar lavage (BAL) fluids, blood, and lung tissue were collected for study. RNA, HA, protein and histopathology were analyzed. Analyses of lung sections and BAL fluids revealed an early deposition and an increase in HA levels within 24 h of antigen exposure. HA levels peaked at day 8 in BAL, while inflammatory cell recovery peaked at day 6. Hyaluronan synthase (HAS)1 and HAS2 on RNA levels peaked within 2 h of antigen exposure, while hyaluronidase (HYAL)1 and HYAL2 on RNA levels decreased. Both inflammatory cell infiltrates and collagen deposition co-localized with HA deposition within the lungs. These data support a role for HA in the pathogenesis of inflammation and airway remodeling in a murine model of asthma. HA deposition appears largely due to up regulation of HAS1 and HAS2. In addition, HA appears to provide the scaffolding for inflammatory cell accumulation as well as for new collagen synthesis and deposition.

Bone morphogenetic protein (BMP)-4 and BMP-7 regulate differentially transforming growth factor (TGF)-beta1 in normal human lung fibroblasts (NHLF)

Background

Airway remodelling is thought to be under the control of a complex group of molecules belonging to the Transforming Growth Factor (TGF)-superfamily. The Bone Morphogenetic Proteins (BMPs) belong to this family and have been shown to regulate fibrosis in kidney and liver diseases. However, the role of BMPs in lung remodelling remains unclear. BMPs may regulate tissue remodelling in asthma by controlling TGF-β-induced profibrotic functions in lung fibroblasts.

Methods

Cell cultures were exposed to TGF-β1 alone or in the presence of BMP-4 or BMP-7; control cultures were exposed to medium only. Cell proliferation was assessed by quantification of the incorporation of [3H]-thymidine. The expression of the mRNA encoding collagen type I and IV, tenascin C and fibronectin in normal human lung fibroblasts (NHLF) was determined by real-time quantitative PCR and the main results were confirmed by ELISA. Cell differentiation was determined by the analysis of the expression of α-smooth muscle actin (α-SMA) by western blot and immunohistochemistry. The effect on matrix metalloproteinase (MMP) activity was assessed by zymography.

Results

We have demonstrated TGF-β1 induced upregulation of mRNAs encoding the extracellular matrix proteins, tenascin C, fibronectin and collagen type I and IV when compared to unstimulated NHLF, and confirmed these results at the protein level. BMP-4, but not BMP-7, reduced TGF-β1-induced extracellular matrix protein production. TGF-β1 induced an increase in the activity of the pro-form of MMP-2 which was inhibited by BMP-7 but not BMP-4. Both BMP-4 and BMP-7 downregulated TGF-β1-induced MMP-13 release compared to untreated and TGF-β1-treated cells. TGF-β1 also induced a myofibroblast-like transformation which was partially inhibited by BMP-7 but not BMP-4.

Conclusions

Our study suggests that some regulatory properties of BMP-7 may be tissue or cell type specific and unveil a potential regulatory role for BMP-4 in the regulation of lung fibroblast function.

Thioredoxin mediates remodeling factors of human bronchial epithelial cells upon interaction with house dust mite-stimulated eosinophils

Bronchial epithelial cells exposed to allergens typically secrete chemokines to recruit eosinophils. Persistent inflammation and repair responses result in airway remodeling and irreversible airflow limitation. House dust mite (HDM) is a common allergen causing allergic disorders. Thioredoxin (TRX) is a redox protein that scavenges reactive oxygen species (ROS). This study was to elucidate how TRX mediates gene expression of remodeling factors of human bronchial epithelial cells in response to HDM stimuli interacting with eosinophils. This study cultured normal human bronchial epithelial (BEAS-2B) cells with eosinophils exposed to 0.5 microg/ml recombinant Dermatophagoides pteronyssinus 1 (rDer p1) protease to mimic the allergen-immune reaction. Eosinophils were induced by rDer p1 protease to secrete tumor necrosis factor (TNF)-alpha and generate ROS. When cultured with rDer p1-stimulated eosinophils, BEAS-2B cells released interleukin-6 and underwent apoptosis. The HDM-stimulated eosinophils applied oxidative stress and apoptosis to BEAS-2B cells through the release of mediators. Damaged BEAS-2B cells interfered with gene expression of remodeling factors, such as transforming growth factor (TGF)-beta 1, epidermal growth factor receptor (EGFR), cyclin dependent kinase inhibitor (p21(waf)) and matrix metalloproteinase (MMP) 9, relevant to inflammatory response and epithelial repair in airway remodeling. Notably, BEAS-2B cells over-expressing TRX reduced eosinophil-derived apoptosis and suppressed underlying airway remodeling via attenuation of TGF-beta1, EGFR and p21(waf) and up-regulation of MMP9 expression. Results of this study indicated TRX-over-expressing bronchial epithelial cells attenuated TGF-beta1 and activated MMP9 expression to prevent airway remodeling from HDM-induced inflammation. The finding can be as a reference for further therapeutic studies of TRX.

Efficacy of sulphasalazine on lung histopathology in a murine model of chronic asthma

Sulphasalazine is a specific inhibitor of nuclear factor kappa B (NF-kappa B) which plays a key role in asthma. To determine the impact of sulphasalazine in the treatment of chronic asthma, BALB/c mice were sensitized and challenged with ovalbumin. Mice with experimentally induced asthma in group I received saline, group II sulphasalazine 200 mg/kg, group III sulphasalazine 300 mg/kg, and group IV dexamethasone 1 mg/kg intraperitoneally once a day in the last 7 days of the challenge period. Histological findings of the airways were evaluated by light and electron microscopies. Dexamethasone and sulphasalazine in both doses significantly improved all airway histopathologic parameters of asthma except numbers of goblet cells. Both doses of sulphasalazine improved thicknesses of basement membrane better than dexamethasone. Dexamethasone reduced the number of mast cells better than sulphasalazine (200 mg/kg). Further studies are needed to evaluate the efficacy of sulphasalazine in the treatment of asthma.

Thioredoxin overexpression modulates remodeling factors in stress responses to cigarette smoke

Cigarette smoke (CS) generates reactive oxygen species (ROS) to produce oxidative damage of bronchial epithelial cells. Prolonged repair responses lead to airway remodeling and irreversible airflow limitation. Thioredoxin (TRX) is a redox protein that scavenges ROS to prevent oxidative stress. The aim of this study was to investigate the mechanisms underlying TRX-mediated CS-induced stress relevant to airway remodeling. Results showed that CS stimulated ROS generation and apoptosis in normal human bronchial epithelial (BEAS-2B) cells, and interfered with gene expression of remodeling factors, such as activation of transforming growth factor (TGF)-beta1, epidermal growth factor receptor (EGFR), and cyclin-dependent kinase inhibitor (p21), but repressed matrix metalloproteinases (MMP)-9. In particular, TRX-overexpressing bronchial epithelial (TRX-TD) cells reduced CS-induced apoptosis, and suppressed airway remodeling through attenuation of TGF-beta1, EGFR, and p21 and upregulation of MMP-9 expression. TGF-beta1 was shown to regulate MMP-9 as evidenced by suppression of MMP-9 protein induction by TGF-beta1 antibody. In addition, CS produced apoptosis of BEAS-2B cells via TRX oxidation, which activated signal transduction factors, including apoptosis signal-regulating kinase (ASK) 1 and c-Jun N-terminal kinase (JNK). In contrast, TRX-TD cells exposed to CS retained reduced-form TRX, and inactivated ASK1 and JNK to attenuate apoptosis. This study indicated TRX overexpression was involved in CS-induced apoptosis and prevented airway remodeling through ASK1-JNK inactivation and MMP-9 augmentation.