Cross-talk between human mast cells and bronchial epithelial cells in plasminogen activator inhibitor-1 production via transforming growth factor-β1

Myocardial fibrosis in right heart dysfunction

Cardiac fibrosis, associated with right heart dysfunction, results in significant morbidity and mortality. Stimulated by various cellular and humoral stimuli, cardiac fibroblasts, macrophages, CD4+ and CD8+ T cells, mast and endothelial cells promote fibrogenesis directly and indirectly by synthesizing numerous profibrotic factors. Several systems, including the transforming growth factor-beta and the renin-angiotensin system, produce type I and III collagen, fibronectin and α-smooth muscle actin, thus modifying the extracellular matrix. Although magnetic resonance imaging with gadolinium enhancement remains the gold standard, the use of circulating biomarkers represents an inexpensive and attractive means to facilitate detection and monitor cardiovascular fibrosis. This review explores the use of protein and nucleic acid (miRNAs) markers to better understand underlying pathophysiology as well as their role in the development of therapeutics to inhibit and potentially reverse cardiac fibrosis.

GW0742 reduces mast cells degranulation and attenuates neurological impairments via PPARβ/δ/CD300a/SHP1 pathway after GMH in neonatal rats

BACKGROUND

Activation of mast cells plays an important role in brain inflammation. CD300a, an inhibitory receptor located on mast cell surfaces, has been reported to reduce the production of pro-inflammatory cytokines and exert protective effects in inflammation-related diseases. Peroxisome proliferator-activated receptor β/δ (PPARβ/δ), a ligand-activated nuclear receptor, activation upregulates the transcription of CD300a. In this study, we aim to investigate the role of PPARβ/δ in the attenuation of germinal matrix hemorrhage (GMH)-induced mast cell activation via CD300a/SHP1 pathway.

METHODS

GMH model was induced by intraparenchymal injection of bacterial collagenase into the right hemispheric ganglionic eminence in P7 Sprague Dawley rats. GW0742, a PPARβ/δ agonist, was administered intranasally at 1 h post-ictus. CD300a small interfering RNA (siRNA) and PPARβ/δ siRNA were injected intracerebroventricularly 5 days and 2 days before GMH induction. Behavioral tests, Western blot, immunofluorescence, Toluidine Blue staining, and Nissl staining were applied to assess post-GMH evaluation.

RESULTS

Results demonstrated that endogenous protein levels of PPARβ/δ and CD300a were decreased, whereas chymase, tryptase, IL-17A and transforming growth factor β1 (TGF-β1) were elevated after GMH. GMH induced significant short- and long-term neurobehavioral deficits in rat pups. GW0742 decreased mast cell degranulation, improved neurological outcomes, and attenuated ventriculomegaly after GMH. Additionally, GW0742 increased expression of PPARβ/δ, CD300a and phosphorylation of SHP1, decreased phosphorylation of Syk, chymase, tryptase, IL-17A and TGF-β1 levels. PPARβ/δ siRNA and CD300a siRNA abolished the beneficial effects of GW0742.

CONCLUSIONS

GW0742 inhibited mast cell-induced inflammation and improved neurobehavior after GMH, which is mediated by PPARβ/δ/CD300a/SHP1 pathway. GW0742 may serve as a potential treatment to reduce brain injury for GMH patients.

Research Progress of Myocardial Fibrosis and Atrial Fibrillation

With the aging population and the increasing incidence of basic illnesses such as hypertension and diabetes (DM), the incidence of atrial fibrillation (AF) has increased significantly. AF is the most common arrhythmia in clinical practice, which can cause heart failure (HF) and ischemic stroke (IS), increasing disability and mortality. Current studies point out that myocardial fibrosis (MF) is one of the most critical substrates for the occurrence and maintenance of AF. Although myocardial biopsy is the gold standard for evaluating MF, it is rarely used in clinical practice because it is an invasive procedure. In addition, serological indicators and imaging methods have also been used to evaluate MF. Nevertheless, the accuracy of serological markers in evaluating MF is controversial. This review focuses on the pathogenesis of MF, serological evaluation, imaging evaluation, and anti-fibrosis treatment to discuss the existing problems and provide new ideas for MF and AF evaluation and treatment.

Asthma and obesity: endotoxin another insult to add to injury?

Low-grade inflammation is often an underlying cause of several chronic diseases such as asthma, obesity, cardiovascular disease, and type 2 diabetes mellitus (T2DM). Defining the mediators of such chronic low-grade inflammation often appears dependent on which disease is being investigated. However, downstream systemic inflammatory cytokine responses in these diseases often overlap, noting there is no doubt more than one factor at play to heighten the inflammatory response. Furthermore, it is increasingly believed that diet and an altered gut microbiota may play an important role in the pathology of such diverse diseases. More specifically, the inflammatory mediator endotoxin, which is a complex lipopolysaccharide (LPS) derived from the outer membrane cell wall of Gram-negative bacteria and is abundant within the gut microbiota, and may play a direct role alongside inhaled allergens in eliciting an inflammatory response in asthma. Endotoxin has immunogenic effects and is sufficiently microscopic to traverse the gut mucosa and enter the systemic circulation to act as a mediator of chronic low-grade inflammation in disease. Whilst the role of endotoxin has been considered in conditions of obesity, cardiovascular disease and T2DM, endotoxin as an inflammatory trigger in asthma is less well understood. This review has sought to examine the current evidence for the role of endotoxin in asthma, and whether the gut microbiota could be a dietary target to improve disease management. This may expand our understanding of endotoxin as a mediator of further low-grade inflammatory diseases, and how endotoxin may represent yet another insult to add to injury.

Cardiac Fibrosis: Cellular Effectors, Molecular Pathways, and Exosomal Roles

Cardiac fibrosis, a common pathophysiologic process in most heart diseases, refers to an excess of extracellular matrix (ECM) deposition by cardiac fibroblasts (CFs), which can lead to cardiac dysfunction and heart failure subsequently. Not only CFs but also several other cell types including macrophages and endothelial cells participate in the process of cardiac fibrosis via different molecular pathways. Exosomes, ranging in 30-150 nm of size, have been confirmed to play an essential role in cellular communications by their bioactive contents, which are currently a hot area to explore pathobiology and therapeutic strategy in multiple pathophysiologic processes including cardiac fibrosis. Cardioprotective factors such as RNAs and proteins packaged in exosomes make them an excellent cell-free system to improve cardiac function without significant immune response. Emerging evidence indicates that targeting selective molecules in cell-derived exosomes could be appealing therapeutic treatments in cardiac fibrosis. In this review, we summarize the current understandings of cellular effectors, molecular pathways, and exosomal roles in cardiac fibrosis.

Tranilast prevents doxorubicin-induced myocardial hypertrophy and angiotensin II synthesis in rats

An increase in oxidative stress is an important pathological mechanism of heart injury induced by doxorubicin (DOX). Tranilast is an anti-allergy drug that has been shown to possess good antioxidant activity in previous studies. The overexpression and secretion of chymase by mast cells (MCs) increase the pathological overexpression of angiotensin II (Ang II), which plays a crucial role in myocardial hypertrophy and the deterioration of heart disease. The MC stabilizer tranilast (N-(3,4-dimethoxycinnamoyl) anthranilic acid; tran) prevents mast cells from degranulating, which may reduce DOX-induced Ang II synthesis. Therefore, in the present study, we hypothesized that tranilast will protect rats from DOX-induced myocardial damage via its antioxidant activity, thereby inhibiting Ang II expression. Thirty male Wistar rats were divided into three groups (n = 10 in each group) that received DOX, a combination of DOX and tranilast or saline (the control group) to test this hypothesis. Tranilast suppressed chymase expression, reduced Ang II levels and prevented the myocardial hypertrophy and the deterioration of heart function induced by DOX. Based on the findings of the present study, the suppression of chymase-dependent Ang-II production and the direct effect of tranilast on the inhibition of apoptosis and fibrosis because of its antioxidant stress capacity may contribute to the protective effect of tranilast against DOX-induced myocardial hypertrophy.

Dermal Extracellular Matrix-Derived Hydrogels as an In Vitro Substrate to Study Mast Cell Maturation

Mast cells (MCs) are pro-inflammatory tissue-resident immune cells that play a key role in inflammation. MCs circulate in peripheral blood as progenitors and undergo terminal differentiation in the tissue microenvironment where they can remain for many years. This in situ maturation results in tissue- and species-specific MC phenotypes, culminating in significant variability in response to environmental stimuli. There are many challenges associated with studying mature tissue-derived MCs, particularly in humans. In cases where cultured MCs are able to differentiate in two-dimensional in vitro cultures, there remains an inability for full maturation. Extracellular matrix (ECM) scaffolds provide for a more physiologically relevant environment for cells in vitro and have been shown to modulate the response of other immune cells such as T cells, monocytes, and macrophages. To improve current in vitro testing platforms of MCs and to assess future use of ECM scaffolds for MC regulation, we studied the in vitro response of human MCs cultured on decellularized porcine dermis hydrogels (dermis extracellular matrix hydrogel [dECM-H]). This study investigated the effect of dECM-H on cellular metabolic activity, cell viability, and receptor expression compared to collagen type I hydrogel (Collagen-H). Human MCs showed different metabolic activity when cultured in the dECM-H and also upregulated immunoglobulin E (IgE) receptors associated with MC maturation/activation compared to collagen type I. These results suggest an overall benefit in the long-term culture of human MCs in the dECM-H compared to Collagen-H providing important steps toward a model that is more representative of in vivo conditions. Graphical abstract [Formula: see text] Impact statement Mast cells (MCs) are difficult to culture in vitro as current culture conditions and substrates fail to promote similar phenotypic features observed in vivo. Extracellular matrix (ECM)-based biomaterials offer three-dimensional, tissue-specific environments that more closely resemble in vivo conditions. Our study explores the use of dermal ECM hydrogels for MC culture and shows significant upregulation of metabolic activity, cell viability, and gene expression of markers associated with MC maturation or activation compared to collagen type I-hydrogel and tissue culture plastic controls at 7 days. These results are among the first to describe MC behavior in response to ECM hydrogels.

Impact of Polytrauma and Acute Respiratory Distress Syndrome on Markers of Fibrinolysis: A Prospective Pilot Study

Acute respiratory distress syndrome (ARDS), which is associated with major morbidity and high mortality, is commonly developed by polytraumatized patients. Its pathogenesis is complex, and its development is difficult to anticipate, as candidate biomarkers for the prediction of ARDS were found not to be reliable for clinical use. In this prospective study, we assessed the serum antigen levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) of 28 survivors of blunt polytrauma (age ≥18 years; injury severity score ≥16) at admission and on days 1, 3, 5, 7, 10, 14, and 21 of hospitalization. Our results show that these patients presented high mean tPA and PAI-1 antigen levels at admission; despite their decline, these parameters remained elevated for 3 weeks. Over this period, the mean tPA antigen level was higher in polytrauma victims suffering from ARDS than in those without ARDS, whereas the mean PAI-1 level was higher in polytrauma victims sustaining pneumonia than in those without pneumonia. Moreover, in each individual developing ARDS, the polytrauma-related elevated tPA antigen level either continued to rise after admission or suffered a second increase up to the onset of ARDS, declining immediately thereafter. Therefore, our findings support the assessment of serum tPA antigen levels after the initial treatment of polytraumatized patients, as this parameter shows potential as a biomarker for the development of ARDS and for the consequent identification of high-risk individuals.

Novel Insight into the in vivo Function of Mast Cell Chymase: Lessons from Knockouts and Inhibitors

Mast cells are now recognized as key players in diverse pathologies, but the mechanisms by which they contribute in such settings are only partially understood. Mast cells are packed with secretory granules, and when they undergo degranulation in response to activation the contents of the granules are expelled to the extracellular milieu. Chymases, neutral serine proteases, are the major constituents of the mast cell granules and are hence released in large amounts upon mast cell activation. Following their release, chymases can cleave one or several of a myriad of potential substrates, and the cleavage of many of these could potentially have a profound impact on the respective pathology. Indeed, chymases have recently been implicated in several pathological contexts, in particular through studies using chymase inhibitors and by the use of chymase-deficient animals. In many cases, chymase has been shown to account for mast cell-dependent detrimental effects in the respective conditions and is therefore emerging as a promising drug target. On the other hand, chymase has been shown to have protective roles in other pathological settings. More unexpectedly, chymase has also been shown to control certain homeostatic processes. Here, these findings are reviewed.

The emerging role of mast cell proteases in asthma

It is now well established that mast cells (MCs) play a crucial role in asthma. This is supported by multiple lines of evidence, including both clinical studies and studies on MC-deficient mice. However, there is still only limited knowledge of the exact effector mechanism(s) by which MCs influence asthma pathology. MCs contain large amounts of secretory granules, which are filled with a variety of bioactive compounds including histamine, cytokines, lysosomal hydrolases, serglycin proteoglycans and a number of MC-restricted proteases. When MCs are activated, e.g. in response to IgE receptor cross-linking, the contents of their granules are released to the exterior and can cause a massive inflammatory reaction. The MC-restricted proteases include tryptases, chymases and carboxypeptidase A3, and these are expressed and stored at remarkably high levels. There is now emerging evidence supporting a prominent role of these enzymes in the pathology of asthma. Interestingly, however, the role of the MC-restricted proteases is multifaceted, encompassing both protective and detrimental activities. Here, the current knowledge of how the MC-restricted proteases impact on asthma is reviewed.

The Transferrin Receptor CD71 Delineates Functionally Distinct Airway Macrophage Subsets during Idiopathic Pulmonary Fibrosis

Rationale: Idiopathic pulmonary fibrosis (IPF) is a devastating progressive disease with limited therapeutic options. Airway macrophages (AMs) are key components of the defense of the airways and are implicated in the pathogenesis of IPF. Alterations in iron metabolism have been described during fibrotic lung disease and in murine models of lung fibrosis. However, the role of transferrin receptor 1 (CD71)-expressing AMs in IPF is not known. Objectives: To assess the role of CD71-expressing AMs in the IPF lung. Methods: We used multiparametric flow cytometry, gene expression analysis, and phagocytosis/transferrin uptake assays to delineate the role of AMs expressing or lacking CD71 in the BAL of patients with IPF and of healthy control subjects. Measurements and Main Results: There was a distinct increase in proportions of AMs lacking CD71 in patients with IPF compared with healthy control subjects. Concentrations of BAL transferrin were enhanced in IPF-BAL, and furthermore, CD71- AMs had an impaired ability to sequester transferrin. CD71+ and CD71- AMs were phenotypically, functionally, and transcriptionally distinct, with CD71- AMs characterized by reduced expression of markers of macrophage maturity, impaired phagocytosis, and enhanced expression of profibrotic genes. Importantly, proportions of AMs lacking CD71 were independently associated with worse survival, underlining the importance of this population in IPF and as a potential therapeutic target. Conclusions: Taken together, these data highlight how CD71 delineates AM subsets that play distinct roles in IPF and furthermore show that CD71- AMs may be an important pathogenic component of fibrotic lung disease.

Mast cell chymase impairs bronchial epithelium integrity by degrading cell junction molecules of epithelial cells

BACKGROUND

An increased degree of mast cell (MC) degranulation and damage to the epithelial lining are prominent features of bronchial asthma. In asthmatic airways, it seems likely that epithelial cells will be exposed to increased concentrations of proteases from MC, though their actions on the epithelium are still not very clear.

METHODS

Bronchial rings from human lung tissue or 16HBE cell monolayer were incubated with MC chymase in different doses or various inhibitors. The sections of paraffin-embedded tissue were haematoxylin-eosin stained and computerized by image analysis for epithelial damage-scale-evaluation; the cell viability, proliferation, adhesion and lactate dehydrogenase activity release were assayed; the expressions of gelatinases, cell junction molecules and structure proteins of 16HBE were examined.

RESULTS

Mast cell chymase was found to provoke profound changes in the morphology of bronchi epithelial layer. Following incubation with chymase, there was 40% reduction in the length of epithelium that was intact, with detachment of columnar epithelial cells and basal cells. Chymase reduced epithelial cell proliferation and induced cell detachment, which were associated with the changes in secretion and activation of matrix metalloproteinase-2/9. In intact epithelial cell layers, immunocytochemistry study revealed that chymase reduced the expressions of occludin, claudin-4, ZO-1, E-cadherin, focal adhesion kinase and cytokeratin. Overall data of this study indicated that MC chymase can influence tissue remodelling, disrupt epithelial cell junctions, inhibit wound healing and impair the barrier function of epithelium, resulting in dysfunction of airway wall and ECM remodelling in pathogenesis of asthma.

CONCLUSION

Mast cell chymase plays a key role in inducing the damage to bronchial epithelium in asthma.

Soy isoflavones reduce asthma exacerbation in asthmatic patients with high PAI-1-producing genotypes

BACKGROUND

The 4G4G genotype of plasminogen activator inhibitor 1 (PAI-1) is associated with increased plasma PAI-1 levels and poor asthma control. Previous studies suggest that soy isoflavones can reduce PAI-1 levels.

OBJECTIVE

We sought to investigate PAI-1 genotype-specific differences of the soy isoflavone response in asthma outcomes.

METHODS

A PAI-1 functional polymorphism (rs1799768, 4G5G) was characterized in subjects with poorly controlled asthma enrolled in a randomized clinical trial of soy isoflavones (n = 265). Genotype-specific treatment responses on asthma outcomes were compared between soy isoflavones and placebo. Normal human bronchial epithelial cells were cultured with or without TGF-β1, genistein, or both, and PAI-1 levels were measured.

RESULTS

The 4G4G/4G5G genotype was associated with a greater risk for allergy-related worsened asthma symptoms and eczema at baseline compared with the 5G5G genotype. There was a significant interaction between the genotype and soy isoflavone intervention on oral corticosteroid use for asthma exacerbation (P = .005). In a subgroup analysis soy isoflavones significantly reduced the use of oral corticosteroids (number of events/person-year) by 4-fold compared with placebo in the 4G4G/4G5G genotype (0.2 vs 0.8; relative risk, 0.28; P < .001) but not in the 5G5G genotype. Soy isoflavones reduced plasma PAI-1 levels compared with placebo. Genistein treatment reduced TGF-β1-induced PAI-1 production in normal human bronchial epithelial cells.

CONCLUSIONS

This study demonstrates that soy isoflavone treatment provides a significant benefit in reducing the number of severe asthma exacerbations in asthmatic patients with the high PAI-1-producing genotype. PAI-1 polymorphisms can be used as a genetic biomarker for soy isoflavone-responsive patients with asthma.

Mast Cells in Cardiac Fibrosis: New Insights Suggest Opportunities for Intervention

Mast cells (MC) are innate immune cells present in virtually all body tissues with key roles in allergic disease and host defense. MCs recognize damage-associated molecular patterns (DAMPs) through expression of multiple receptors including Toll-like receptors and the IL-33 receptor ST2. MCs can be activated to degranulate and release pre-formed mediators, to synthesize and secrete cytokines and chemokines without degranulation, and/or to produce lipid mediators. MC numbers are generally increased at sites of fibrosis. They are potent, resident, effector cells producing mediators that regulate the fibrotic process. The nature of the secretory products produced by MCs depend on micro-environmental signals and can be both pro- and anti-fibrotic. MCs have been repeatedly implicated in the pathogenesis of cardiac fibrosis and in angiogenic responses in hypoxic tissues, but these findings are controversial. Several rodent studies have indicated a protective role for MCs. MC-deficient mice have been reported to have poorer outcomes after coronary artery ligation and increased cardiac function upon MC reconstitution. In contrast, MCs have also been implicated as key drivers of fibrosis. MC stabilization during a hypertensive rat model and an atrial fibrillation mouse model rescued associated fibrosis. Discrepancies in the literature could be related to problems with mouse models of MC deficiency. To further complicate the issue, mice generally have a much lower density of MCs in their cardiac tissue than humans, and as such comparing MC deficient and MC containing mouse models is not necessarily reflective of the role of MCs in human disease. In this review, we will evaluate the literature regarding the role of MCs in cardiac fibrosis with an emphasis on what is known about MC biology, in this context. MCs have been well-studied in allergic disease and multiple pharmacological tools are available to regulate their function. We will identify potential opportunities to manipulate human MC function and the impact of their mediators with a view to preventing or reducing harmful fibrosis. Important therapeutic opportunities could arise from increased understanding of the impact of such potent, resident immune cells, with the ability to profoundly alter long term fibrotic processes.

miR-122-SOCS1-JAK2 axis regulates allergic inflammation and allergic inflammation-promoted cellular interactions

The regulatory role of suppressor of cytokine signaling 1 (SOCS1) in inflammation has been reported. However, its role in allergic inflammation has not been previously reported. SOCS1 mediated in vitro and in vivo allergic inflammation. Histone deacetylase-3 (HDAC3), a mediator of allergic inflammation, interacted with SOCS1, and miR-384 inhibitor, a positive regulator of HDAC3, induced features of allergic inflammation in an SOCS1-dependent manner. miRNA array analysis showed that the expression of miR-122 was decreased by antigen-stimulation. TargetScan analysis predicted the binding of miR-122 to the 3′-UTR of SOCS1. miR-122 inhibitor induced in vitro and in vivo allergic features in SOCS1-dependent manner. SOCS1 was necessary for allergic inflammation-promoted enhanced tumorigenic and metastatic potential of cancer cells. SOCS1 and miR-122 regulated cellular interactions involving cancer cells, mast cells and macrophages during allergic inflammation. SOCS1 mimetic peptide, D-T-H-F-R-T-F-R-S-H-S-D-Y-R-R-I, inhibited in vitro and in vivo allergic inflammation, allergic inflammation-promoted enhanced tumorigenic and metastatic potential of cancer cells, and cellular interactions during allergic inflammation. Janus kinase 2 (JAK2) exhibited binding to SOCS1 mimetic peptide and mediated allergic inflammation. Transforming growth factor- Δ1 (TGF-Δ1) was decreased during allergic inflammation and showed an anti-allergic effect. SOCS1 and JAK2 regulated the production of anti-allergic TGF-Δ1. Taken together, our results show that miR-122-SOCS1 feedback loop can be employed as a target for the development of anti-allergic and anti-cancer drugs.

Role of Proteases in Lung Disease: A Brief Overview

Proteases play an important role in health and disease of the lung. In the normal lungs, proteases maintain their homeostatic functions that regulate processes like its regeneration and repair. Dysregulation of proteases–antiproteases balance is crucial in the manifestation of different types of lung diseases. Chronic inflammatory lung pathologies are associated with a marked increase in protease activities. Thus, in addition to protease activities, inhibition of anti-proteolytic control mechanisms are also important for effective microbial infection and inflammation in the lung. Herein, we briefly summarize the role of different proteases and to some extent antiproteases in regulating a variety of lung diseases.

Regulation of Innate and Adaptive Immunity by TGFβ

Immune regulation by cytokines is crucial in maintaining immune homeostasis, promoting responses to infection, resolving inflammation, and promoting immunological memory. Additionally, cytokine responses drive pathology in immune-mediated disease. A crucial cytokine in the regulation of all aspects of an immune response is transforming growth factor beta (TGFβ). Although best known as a crucial regulator of T cell responses, TGFβ plays a vital role in regulating responses mediated by virtually every innate and adaptive immune cell, including dendritic cells, B cells, NK cells, innate lymphoid cells, and granulocytes. Here, we review our current knowledge of how TGFβ regulates the immune system, highlighting the multifunctional nature of TGFβ and how its function can change depending on location and context of action.

Glucocorticoid Insensitivity in Virally Infected Airway Epithelial Cells Is Dependent on Transforming Growth Factor-β Activity

Asthma and chronic obstructive pulmonary disease (COPD) exacerbations are commonly associated with respiratory syncytial virus (RSV), rhinovirus (RV) and influenza A virus (IAV) infection. The ensuing airway inflammation is resistant to the anti-inflammatory actions of glucocorticoids (GCs). Viral infection elicits transforming growth factor-β (TGF-β) activity, a growth factor we have previously shown to impair GC action in human airway epithelial cells through the activation of activin-like kinase 5 (ALK5), the type 1 receptor of TGF-β. In the current study, we examine the contribution of TGF-β activity to the GC-resistance caused by viral infection. We demonstrate that viral infection of human bronchial epithelial cells with RSV, RV or IAV impairs GC anti-inflammatory action. Poly(I:C), a synthetic analog of double-stranded RNA, also impairs GC activity. Both viral infection and poly(I:C) increase TGF-β expression and activity. Importantly, the GC impairment was attenuated by the selective ALK5 (TGFβRI) inhibitor, SB431542 and prevented by the therapeutic agent, tranilast, which reduced TGF-β activity associated with viral infection. This study shows for the first time that viral-induced glucocorticoid-insensitivity is partially mediated by activation of endogenous TGF-β.

In this study, we investigate how respiratory viral infection interferes with the anti-inflammatory actions of glucocorticoid (GC) drugs, which are a highly effective group of anti-inflammatory agents widely used in the treatment of chronic inflammatory airway diseases, including asthma and chronic obstructive pulmonary disease (COPD). Exacerbations of both asthma (“asthma attacks”) and COPD are often caused by viral infection, which does not respond well to GC therapy. Patients are often hospitalized placing a large burden on healthcare systems around the world, with the young, elderly, and those with a poor immune system particularly at risk. We show that viral infection of airway epithelial cells causes increased expression and activity of transforming growth factor-beta (TGF-β), which interferes with GC drug action. Importantly, we have shown for the first time that inhibiting TGF-β activity in the airways could serve as a new strategy to prevent and/or treat viral exacerbations of chronic airway diseases.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

TGF-β1-induced PAI-1 contributes to a profibrotic network in patients with eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an allergic disease of increasing worldwide incidence. Complications are due to tissue remodeling and involve TGF-β1-mediated fibrosis. Plasminogen activator inhibitor 1 (PAI-1/serpinE1) can be induced by TGF-β1, but its role in EoE is not known.

OBJECTIVE

We sought to understand the expression and role of PAI-1 in patients with EoE.

METHODS

We used esophageal biopsy specimens and plasma samples from control subjects and patients with EoE, primary human esophageal epithelial cells, and fibroblasts from patients with EoE in immunohistochemistry, quantitative PCR, and immunoassay experiments to understand the induction of PAI-1 by TGF-β1, the relationship between PAI-1 and esophageal fibrosis, and the role of PAI-1 in fibrotic gene expression.

RESULTS

PAI-1 expression was significantly increased in epithelial cells of biopsy specimens from patients with active EoE compared with that seen in biopsy specimens from patients with inactive EoE or control subjects (P < .001). Treatment of primary esophageal epithelial cells with recombinant TGF-β1 increased PAI-1 transcription, intracellular protein expression, and secretion. Esophageal PAI-1 expression correlated with basal zone hyperplasia, fibrosis, and markers of esophageal remodeling, including vimentin, TGF-β1, collagen I, fibronectin, and matrix metalloproteases, and plasma PAI-1 levels correlated with plasma TGF-β1 levels. PAI-1 inhibition significantly decreased baseline and TGF-β1-induced fibrotic gene expression.

CONCLUSIONS

PAI-1 expression is significantly increased in the epithelium in patients with EoE and reflects fibrosis, and its inhibition decreases TGF-β1-induced gene expression. Epithelial PAI-1 might serve as a marker of EoE severity and form part of a TGF-β1-induced profibrotic network.

Prothrombotic state in patients with severe and prednisolone-dependent asthma

BACKGROUND

Epidemiologic studies have shown that asthmatic patients, in particular those with severe disease, have increased risk of pulmonary embolism. It is unknown whether these patients have a prothrombotic state under stable conditions.

OBJECTIVE

We sought to compare coagulation and fibrinolysis parameters between healthy subjects and patients with mild, severe, and prednisolone-dependent asthma under stable conditions and to investigate whether hemostatic markers correlate with airway inflammation.

METHODS

In 126 adults (33 healthy control subjects, 31 patients with mild asthma, 32 patients with severe asthma, and 30 patients with prednisolone-dependent asthma) parameters of inflammation (peripheral blood eosinophils and neutrophils) and markers of hemostasis (endogenous thrombin potential [ETP], thrombin-antithrombin complex, plasmin-α2-antiplasmin complex, plasminogen activator inhibitor type 1 [PAI-1], D-dimer, and von Willebrand factor [vWF]) were measured in plasma. One-way ANOVA with the post hoc Bonferroni test was used for group comparison, and linear regression analysis was used for correlations.

RESULTS

We observed increased ETP (121% vs 99%, overall P < .01), plasmin-α2-antiplasmin complex (520 vs 409 μg/L, overall P = .04), PAI-1 (10 vs 7 ng/mL, overall P = .02), and vWF (142% vs 87%, overall P < .01) levels in asthmatic patients compared with healthy control subjects. ETP, PAI-1, and vWF levels increased with increasing asthma severity. In addition, we found a correlation between ETP and vWF with neutrophil but not eosinophil counts.

CONCLUSION

Asthmatic patients have a prothrombotic state that increases with asthma severity. This might explain why patients with asthma, in particular those with severe disease, have an increased risk of venous thromboembolism.