Transforming growth factor beta abrogates the effects of hematopoietins on eosinophils and induces their apoptosis

The interplay of inflammation and remodeling in the pathogenesis of chronic rhinosinusitis: current understanding and future directions

Chronic rhinosinusitis (CRS), a common clinical condition characterized by persistent mucosal inflammation and tissue remodeling, has a complex pathogenesis that is intricately linked to innate and adaptive immunity. A number of studies have demonstrated that a variety of immune cells and cytokines that play a vital role in mediating inflammation in CRS are also involved in remodeling of the nasal mucosa and the cells as well as different cytokines involved in remodeling in CRS are also able to exert some influence on inflammation, even though the exact relationship between inflammation and remodeling in CRS has not yet been fully elucidated. In this review, the potential role of immune cells and cytokines in regulating inflammation and remodeling of CRS mucosa has been described, starting with the immune cells and cytokines that act together in inflammation and remodeling. The goal is to aid researchers in understanding intimate connection between inflammation and remodeling of CRS and to offer novel ideas for future research.

Suppression of airway allergic eosinophilia by Hp-TGM, a helminth mimic of TGF-β

Type 2-high asthma is a chronic inflammatory disease of the airways which is increasingly prevalent in countries where helminth parasite infections are rare, and characterized by T helper 2 (Th2)-dependent accumulation of eosinophils in the lungs. Regulatory cytokines such as TGF-β can restrain inflammatory reactions, dampen allergic Th2 responses, and control eosinophil activation. The murine helminth parasite Heligmosomoides polygyrus releases a TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β despite bearing no structural similarity to the mammalian protein. Here, we investigated if Hp-TGM could alleviate allergic airway inflammation in mice exposed to Alternaria alternata allergen, house dust mite (HDM) extract or alum-adjuvanted ovalbumin protein (OVA). Intranasal administration of Hp-TGM during Alternaria exposure sharply reduced airway and lung tissue eosinophilia along with bronchoalveolar lavage fluid IL-5 and lung IL-33 cytokine levels at 24 h. The protective effect of Hp-TGM on airway eosinophilia was also obtained in the longer T-cell mediated models of HDM or OVA sensitisation with significant inhibition of eotaxin-1, IL-4 and IL-13 responses depending on the model and time-point. Hp-TGM was also protective when administered parenterally either when given at the time of allergic sensitisation or during airway allergen challenge. This project has taken the first steps in identifying the role of Hp-TGM in allergic asthma and highlighted its ability to control lung inflammation and allergic pathology. Future research will investigate the mode of action of Hp-TGM against airway allergic eosinophilia, and further explore its potential to be developed as a biotherapeutic in allergic asthma.

Local IL-10 replacement therapy was effective for steroid-insensitive asthma in mice

Subgroups of patients with severe asthma showing marked increases in sputum eosinophils and/or neutrophils are insensitive to corticosteroids. Previous reports have shown that exogenous administration of an anti-inflammatory cytokine, interleukin (IL)-10 negatively regulated both eosinophilic and neutrophilic migration into tissues. The objective of this study was to elucidate whether intratracheal IL-10 administration suppresses asthmatic responses in a steroid-insensitive model of mice. Ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at 500 µg/animal four times. Dexamethasone (1 mg/kg, intraperitoneal) or IL-10 (25 ng/mouse, intratracheal) was administered during the multiple challenges. The number of leukocytes, expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and IL-10 receptor in the lung, and the development of airway remodeling and hyperresponsiveness were evaluated after the fourth challenge. Consistent with our previous study, dexamethasone hardly suppressed the development of airway remodeling and hyperresponsiveness. Although intratracheal IL-10 administration did not affect the development of airway remodeling, the infiltration of eosinophils and neutrophils, and the development of airway hyperresponsiveness were significantly inhibited. Moreover, IL-10 administration significantly decreased the numbers of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, which express IL-10 receptor 1, even though neither production of eosinophilic nor neutrophilic cytokines in the lung was inhibited. Therefore, IL-10 can suppress eosinophil and neutrophil infiltration by inhibiting the proliferation of ICAM-1⁺ and VCAM-1⁺ pulmonary vascular endothelial cells, resulting in inhibition of airway hyperresponsiveness in steroid-insensitive asthmatic mice. IL-10 replacement therapy may be clinically useful for the treatment of steroid-insensitive asthma.

Cytokine Signature and Involvement in Chronic Rhinosinusitis with Nasal Polyps

Cytokines are well known to play a central role in chronic rhinosinusitis with nasal polyps (CRSwNP), particularly in maintenance of the inflammatory response and the recruitment of eosinophils. The pathophysiological concepts concerning the involvement of inflammatory cytokines in CRSwNP have gradually evolved. Although the Th2 cytokines environment associated with an eosinophilic infiltration has retained a central role in the genesis of polyps, the role of other cytokine subpopulations has also and more recently been detailed, leading to a specific and complex signature in CRSwNP. The purpose of this review is to summarize the current state of knowledge about the cytokine signature in CRSwNP, the role of cytokines in the pathogenesis of this disease and in the intercellular dialog between epithelial cells, fibroblasts and inflammatory cells. Knowledge of this precise cytokine signature in CRSwNP is fundamental in the perspective of potential targeting biotherapies.

Potent Anti-Inflammatory Effects of Tetracyclines on Human Eosinophils

Eosinophils are potent pro-inflammatory cells. Not only in allergic diseases but also in other diseases there is a need for treatment strategies to induce resolution of eosinophil-mediated inflammation. During the last years beneficial non-antibiotic activities of tetracyclines (TCNs) have been shown in different diseases in which eosinophils play a role, for example, asthma and bullous pemphigoid. The working mechanism of these effects remains to be clarified. Aim of the present study was to investigate the effects of TCNs on eosinophils. Flow cytometry analysis of apoptosis, mitochondrial membrane potential, activation of caspases, intracellular H₂O₂ and calcium, surface expression of eosinophil activation markers was performed in highly purified peripheral blood eosinophils of non-atopic donors. Tetracycline hydrochloride, minocycline and doxycycline significantly induced eosinophil apoptosis. All TCNs were able to significantly overcome the strong survival enhancing effects of pro-eosinophilic cytokines and staphylococcus aureus enterotoxins. Tetracycline hydrochloride induced eosinophil apoptosis was accompanied by intracellular production of hydrogen peroxide, loss of mitochondrial membrane potential and activation of caspases. Moreover, tetracycline hydrochloride significantly down regulated eosinophil surface expression of CD9 and CD45, and of the activation markers CD11b and CD69, but not of CD54, CD63, or CD95. Our data, propably for the first time, point to a potent anti-inflammatory role of TCNs on eosinophils.

Eosinophils and eosinophil-associated disorders: immunological, clinical, and molecular complexity

Eosinophils and their mediators play a crucial role in various reactive states such as bacterial and viral infections, chronic inflammatory disorders, and certain hematologic malignancies. Depending on the underlying pathology, molecular defect(s), and the cytokine- and mediator-cascades involved, peripheral blood and tissue hypereosinophilia (HE) may develop and may lead to organ dysfunction or even organ damage which usually leads to the diagnosis of a HE syndrome (HES). In some of these patients, the etiology and impact of HE remain unclear. These patients are diagnosed with idiopathic HE. In other patients, HES is diagnosed but the etiology remains unknown — these patients are classified as idiopathic HES. For patients with HES, early therapeutic application of agents reducing eosinophil counts is usually effective in avoiding irreversible organ damage. Therefore, it is important to systematically explore various diagnostic markers and to correctly identify the disease elicitors and etiology. Depending on the presence and type of underlying disease, HES are classified into primary (clonal) HES, reactive HES, and idiopathic HES. In most of these patients, effective therapies can be administered. The current article provides an overview of the pathogenesis of eosinophil-associated disorders, with special emphasis on the molecular, immunological, and clinical complexity of HE and HES. In addition, diagnostic criteria and the classification of eosinophil disorders are reviewed in light of new developments in the field.

Lactococcus lactis NZ9000 Prevents Asthmatic Airway Inflammation and Remodelling in Rats through the Improvement of Intestinal Barrier Function and Systemic TGF-β Production

INTRODUCTION

The use of probiotics has been broadly popularized due to positive effects in the attenuation of aberrant immune responses such as asthma. Allergic asthma is a chronic respiratory disease characterized by airway inflammation and remodelling.

OBJECTIVE

This study was aimed to evaluate the effect of oral administration of Lactococcus lactis NZ9000 on asthmatic airway inflammation and lung tissue remodelling in rats and its relation to the maintenance of an adequate intestinal barrier.

METHODS

Wistar rats were ovalbumin (OVA) sensitized and challenged and orally treated with L. lactis. Lung inflammatory infiltrates and cytokines were measured, and remodelling was evaluated. Serum OVA-specific immunoglobulin (Ig) E levels were assessed. We also evaluated changes on intestinal environment and on systemic immune response.

RESULTS

L. lactis diminished the infiltration of proinflammatory leucocytes, mainly eosinophils, in the bronchoalveolar compartment, decreased lung IL-4 and IL-5 expression, and reduced the level of serum allergen-specific IgE. Furthermore, L. lactis prevented eosinophil influx, collagen deposition, and goblet cell hyperplasia in lung tissue. In the intestine, L. lactis-treated asthmatic rats increased Peyer's patch and goblet cell quantity and mRNA expression of IgA, MUC-2, and claudin. Additionally, intestinal morphological alterations were normalized by L. lactis administration. Splenocyte proliferative response to OVA was abolished, and serum levels of transforming growth factor (TGF)-β were increased by L. lactis treatment.

CONCLUSIONS

These findings suggest that L. lactis is a potential candidate for asthma prevention, and the effect is mediated by the improvement of intestinal barrier function and systemic TGF-β production.

Allergen-induced asthma, chronic rhinosinusitis and transforming growth factor-β superfamily signaling: mechanisms and functional consequences

Introduction: Often co-associated, asthma and chronic rhinosinusitis (CRS) are complex heterogeneous disease syndromes. Severity in both is related to tissue inflammation and abnormal repair (termed remodeling). Understanding signaling factors that can modulate, integrate the activation, and regulation of such key processes together is increasingly important. The transforming growth factor (TGF)-β superfamily of ligands comprise a versatile system of immunomodulatory molecules that are gaining recognition as having an essential function in the immunopathogenesis of asthma. Early data suggest an important role in CRS as well. Abnormal or dysregulated signaling may contribute to disease pathogenesis and severity.Areas covered: The essential biology of this complex family of growth factors in relation to the excess inflammation and remodeling that occurs in allergic asthma and CRS is reviewed. The need to understand the integration of signaling pathways together is highlighted. Studies in human airway tissue are evaluated and only selected key animal models relevant to human disease discussed given the highly context-dependent signaling and function of these ligands.Expert opinion: Abnormal or dysregulated TGF-β superfamily signaling may be central to the excess inflammation and tissue remodeling in asthma, and possibly CRS. Therefore, the TGF-β superfamily signaling pathways represent an emerging and attractive therapeutic target.

Wentong decoction cures allergic bronchial asthma by regulating the apoptosis imbalance of EOS

Background

Eosinophils (EOS) is one of the most important cells involved in the pathogenesis of chronic airway inflammation in asthma, and its apoptosis is part of the mechanisms of asthma. Therefore, this study aimed to observe the effect of Chinese medicine Wentong decoction (WTD) in EOS apoptosis in asthmatic rats. This work also explored the mechanism of WTD regulation in EOS apoptosis and provided a new target for clinical treatment of asthma.

Methods

Asthmatic rats induced by ovalbumin were treated with WTD. Lung function of rats in each group was detected, and lung tissue pathology, EOS counts in blood and bronchoalveolar lavage fluid were observed. The degree of the EOS apoptosis in rats was detected. The expression content of interleukin (IL)-5, IL-10, chemokine (C-C motif) ligand 5 (CCL5), granulocyte-macrophage colony-stimulating factor (GM-CSF), transforming growth factor beta 1 (TGF-β1), interferon (IFN)-γ, and other cytokines in rat serum and the genes of Eotaxin mRNA, Fas mRNA, FasL mRNA, Fas/FasL and Bcl-2 mRNA in the lung tissues were determined.

Results

WTD can reduced airway resistance in rat models and improved airway compliance. The pathological changes of lung tissue in WTD group were significantly alleviated, at the same time, WTD could reduce the EOS count in the blood and BALF smears of the asthmatic model rats. Compared with the model group, the apoptosis degree of EOS significantly increased in rats in the WTD group. The expression of IL-5, CCL5, and GM-CSF in the serum and the expression of Eotaxin mRNA, Bcl-2 mRNA in the lung tissues in rats in the WTD group rats decreased. Moreover, the expression of IL-10, TGF-β1, and IFN-γ in the serum and the expression of Fas mRNA, FasL mRNA in the lung tissues in rats in the WTD group rats increased compared with that in rats in the model group.

Conclusions

Wentong decoction may accelerate EOS apoptosis, reduce asthma inflammation, and alleviate the disease through regulating and controlling the factors related to the anti-apoptosis and pro-apoptosis.

Histopathological Features of Nasal Polyps with Asthma Association: An Immunohistochemical Study

Background

Myofibroblasts are related to airway remodeling and may play an important role in the pathogenesis of the histological features of nasal polyps associated with asthma. The aim of this study was to analyze and compare the eosinophilic cationic protein, transforming growth factor (TGF) β, and myofibroblasts in the nasal polyps of patients with chronic sinusitis associated with and without asthma.

Methods

Nasal polyp samples were obtained during endoscopic sinus surgery and were classified into asthma and nonasthma groups. Immunohistochemistry was performed using antibodies against activated eosinophils, TGF-β, and myofibroblasts.

Results

The asthma group showed an increased number of activated eosinophils, TGF-β, and myofibroblasts compared with the nonasthma and control groups. We found no correlation of asthma and aspirin intolerance with the immunohistochemical findings.

Conclusion

The increased number of myofibroblasts in the nasal polyps of the asthma group may be responsible for the extracellular matrix accumulation, polyp formation, and polyp recurrence.

Gene Transfection and Expression of Transforming Growth Factor-β1 in Nonobese Diabetic Mouse Islets Protects β-Cells in Syngeneic Islet Grafts from Autoimmune Destruction

Nonobese diabetic (NOD) mice develop diabetes and destroy syngeneic islet grafts through an autoimmune response. Because transforming growth factor (TGF)-β1 downregulates immune responses, we tested whether overexpression of TGF-β1 by gene transfection of NOD mouse islets could protect β-cells in islet grafts from autoimmune destruction. NOD mouse islet cells were transfected with an adenoviral DNA expression vector encoding porcine latent TGF-β1 (Ad TGF- β1) or the adenoviral vector alone (control Ad vector). The frequency of total islet cells expressing TGF-1 protein was increased from 12±1% in control Ad vector-transfected cells to 89 ± 4% in Ad TGF-β1-transfected islet cells, and the frequency of β-cells that expressed TGF-β1 was increased from 12 ± 1% to 60 ± 7%. Also, secretion of TGF-β1 was significantly increased in islets that overexpressed TGF-β1. Ad TGF-β1-transfected NOD mouse islets that overexpressed TGF-β1 prevented diabetes recurrence after transplantation into diabetic NOD mice for a median of 22 days compared with only 7 days for control Ad vector-transfected islets (p = 0.001). Immunohistochemical examination of the islet grafts revealed significantly more TGF-β1+ cells and insulin+ cells and significantly fewer CD45+ leukocytes in Ad TGF-β1-transfected islet grafts. Also, islet β-cell apoptosis was significantly decreased whereas apoptosis of graft-infiltrating leukocytes was significantly increased in Ad TGF-β1-transfected islet grafts. These observations demonstrate that overexpression of TGF-β1, by gene transfection of NOD mouse islets, protects islet β-cells from apoptosis and autoimmune destruction and delays diabetes recurrence after islet transplantation.

Regulation of the Immune Response by TGF-β: From Conception to Autoimmunity and Infection

Transforming growth factor β (TGF-β) is a pleiotropic cytokine involved in both suppressive and inflammatory immune responses. After 30 years of intense study, we have only begun to elucidate how TGF-β alters immunity under various conditions. Under steady-state conditions, TGF-β regulates thymic T-cell selection and maintains homeostasis of the naïve T-cell pool. TGF-β inhibits cytotoxic T lymphocyte (CTL), Th1-, and Th2-cell differentiation while promoting peripheral (p)Treg-, Th17-, Th9-, and Tfh-cell generation, and T-cell tissue residence in response to immune challenges. Similarly, TGF-β controls the proliferation, survival, activation, and differentiation of B cells, as well as the development and functions of innate cells, including natural killer (NK) cells, macrophages, dendritic cells, and granulocytes. Collectively, TGF-β plays a pivotal role in maintaining peripheral tolerance against self- and innocuous antigens, such as food, commensal bacteria, and fetal alloantigens, and in controlling immune responses to pathogens.

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.

A novel approach to understanding the role of polymorphic forms of the NR3C1 and TGF-β1 genes in the modulation of the expression of IL-5 and IL-15 mRNA in asthmatic inflammation

The aim of the present study was to identify polymorphic forms of the nuclear receptor subfamily 3, group C, member 1 (NR3C1) and transforming growth factor β1 (TGF-β1) genes and evaluate their impact on the expression levels of interleukin (IL)-5 and IL‑15 in asthma. The study was conducted on a control group consisting of 91 people (54 women and 37 men). The patient group consisted of 130 participants (86 women and 44 men). Genotyping was performed by polymerase chain reaction‑restriction fragment length polymorphism (PCR‑RFLP) and PCR‑high resolution melting (HRM) methods. Interleukin expression was measured by reverse transcription‑quantitative polymerase chain reaction. The frequency of the polymorphic forms in the analyzed group were observed to be: Tth111I (rs10052957) controls AA 0.0440, AG 0.5714, GG 0.3846, patients AA 0.1538/AG 0.4692, GG 0.3769; ER22/23EK (rs6189 /rs6190) controls AG 0.0556, GG 0.9444, patients AG 0.0385, GG 0.9615; N363S (rs6195) controls AA 0.6444, AG 0.2667, GG 0.0889, patients AA 0.7846, AG 0.1385, GG 0.0769; BclI (rs41423247) controls CC 0.0879, CG 0.5604, GG 0.3516, patients CC 0.1008, CG 0.5736, GG 0.3256; C‑509T (rs1800469) controls TT 0.0805, CT 0.6322, CC 0.2874, patients TT 0.1102, CT 0.5669, CC 0.3228. The results indicated that the C‑509T single nucleotide polymorphism (SNP) of the TGF-β1 gene contributed to an increase in the IL‑5 mRNA expression levels. The GG genotype of the N363S SNP of the NR3C1 gene was observed to result in an increase in the expression levels of IL‑15. The present study indicated that the selected SNPs of the NR3C1 and TGF‑β1 genes demonstrate a regulatory effect on the expression of IL‑5 and IL‑15. Therefore, genetic variation affects inflammation in asthma and the clinical course of the disease.

TGF-β decreases the stability of IL-18-induced IFN-γ mRNA through the expression of TGF-β-induced tristetraprolin in KG-1 cells

We have previously reported that transforming growth factor-β (TGF-β) down-regulates interferon-γ (IFN-γ) production in an interleukin-18 (IL-18) treated mouse natural killer (NK) cell line, LNK5E6. In LNK5E6 cells, TGF-β exhibited no inhibition of the IL-18-induced transcription of IFN-γ, but did stimulate the degradation of IFN-γ mRNA induced by IL-18. In the present study, we investigated the mechanism of the down-regulatory effects of TGF-β on IFN-γ mRNA expression in a human myelomonocytic cell line, KG-1, which produces IFN-γ in response to IL-18 alone. Interestingly, IL-18 induced the production of the IFN-γ through the stabilization of IFN-γ mRNA, but not the enhanced transcription of IFN-γ gene. The stability of IFN-γ mRNA was regulated by mRNA destabilizing elements in the 3'untranslated region (UTR) of IFN-γ mRNA, especially adenylate-uridylate (AU)-rich elements (AREs) in the 5' half of 3'UTR. Tristetraprolin (TTP), one of the ARE-binding proteins, destabilizes IFN-γ mRNA, and IL-18 repressed the expression of TTP mRNA. Moreover, TGF-β repressed the IL-18-induced expression of IFN-γ mRNA through the induction of TTP mRNA to destabilize IFN-γ mRNA. Our data is the first to reveal that the crosstalk between IL-18 and TGF-β through the expression of TTP regulates the production of IFN-γ.

Determinants of eosinophil survival and apoptotic cell death

Eosinophils (Eos) are potent inflammatory cells and abundantly present in the sputum and lung of patients with allergic asthma. During both transit to and residence in the lung, Eos contact prosurvival cytokines, particularly IL-3, IL-5 and GM-CSF, that attenuate cell death. Cytokine signaling modulates the expression and function of a number of intracellular pro- and anti-apoptotic molecules. Both intrinsic mitochondrial and extrinsic receptor-mediated pathways are affected. This article discusses the fundamental role of the extracellular and intracellular molecules that initiate and control survival decisions by human Eos and highlights the role of the cis-trans isomerase, Pin1 in controlling these processes.

RNA Seq profiling reveals a novel expression pattern of TGF-β target genes in human blood eosinophils

Despite major advances in our understanding of TGF-β signaling in multiple cell types, little is known about the direct target genes of this pathway in human eosinophils. These cells constitute the major inflammatory component present in the sputum and lung of active asthmatics and their numbers correlate well with disease severity. During the transition from acute to chronic asthma, TGF-β levels rise several fold in the lung which drives fibroblasts to produce extracellular matrix (ECM) and participate in airway and parenchymal remodeling. In this report, we use purified blood eosinophils from healthy donors and analyze baseline and TGF-β responsive genes by RNA Seq, and demonstrate that eosinophils (PBE) express 7981 protein-coding genes of which 178 genes are up-regulated and 199 genes are down-regulated by TGF-β. While 18 target genes have been previously associated with asthma and eosinophilic disorders, the vast majority have been implicated in cell death and survival, differentiation, and cellular function. Ingenuity pathway analysis revealed that 126 canonical pathways are activated by TGF-β including iNOS, TREM1, p53, IL-8 and IL-10 signaling. As TGF-β is an important cytokine for eosinophil function and survival, and pulmonary inflammation and fibrosis, our results represent a significant step toward the identification of novel TGF-β responsive genes and provide a potential therapeutic opportunity by selectively targeting relevant genes and pathways.

Wogonin induces eosinophil apoptosis and attenuates allergic airway inflammation

RATIONALE

Eosinophils are key effector cells in allergic diseases, including allergic rhinitis, eczema, and asthma. Their tissue presence is regulated by both recruitment and increased longevity at inflamed sites.

OBJECTIVES

To investigate the ability of the flavone wogonin to induce eosinophil apoptosis in vitro and attenuate eosinophil-dominant allergic inflammation in vivo in mice.

METHODS

Human and mouse eosinophil apoptosis in response to wogonin was investigated by cellular morphology, flow cytometry, mitochondrial membrane permeability, and pharmacological caspase inhibition. Allergic lung inflammation was modeled in mice sensitized and challenged with ovalbumin. Bronchoalveolar lavage (BAL) and lung tissue were examined for inflammation, mucus production, and inflammatory mediator production. Airway hyperresponsiveness to aerosolized methacholine was measured.

MEASUREMENTS AND MAIN RESULTS

Wogonin induced time- and concentration-dependent human and mouse eosinophil apoptosis in vitro. Wogonin-induced eosinophil apoptosis occurred with activation of caspase-3 and was inhibited by pharmacological caspase inhibition. Wogonin administration attenuated allergic airway inflammation in vivo with reductions in BAL and interstitial eosinophil numbers, increased eosinophil apoptosis, reduced airway mucus production, and attenuated airway hyperresponsiveness. This wogonin-induced reduction in allergic airway inflammation was prevented by concurrent caspase inhibition in vivo.

CONCLUSIONS

Wogonin induces eosinophil apoptosis and attenuates allergic airway inflammation, suggesting that it has therapeutic potential for the treatment of allergic inflammation in humans.

Regulation of spontaneous eosinophil apoptosis-a neglected area of importance

Asthma is characterized by the accumulation of eosinophils in the airways in most phenotypes. Eosinophils are inflammatory cells that require an external survival-prolonging stimulus such as granulocyte macrophage-colony-stimulating factor (GM-CSF), interleukin (IL)-5, or IL-3 for survival. In their absence, eosinophils are programmed to die by spontaneous apoptosis in a few days. Eosinophil apoptosis can be accelerated by Fas ligation or by pharmacological agents such as glucocorticoids. Evidence exists for the relevance of these survival-prolonging and pro-apoptotic agents in the regulation of eosinophilic inflammation in inflamed airways. Much less is known about the physiological significance and mechanisms of spontaneous eosinophil apoptosis even though it forms the basis of regulation of eosinophil longevity by pathophysiological factors and pharmacological agents. This review concentrates on discussing the mechanisms of spontaneous eosinophil apoptosis compared to those of glucocorticoid- and Fas-induced apoptosis. We aim to answer the question whether the external apoptotic stimuli only augment the ongoing pathway of spontaneous apoptosis or truly activate a specific pathway.

Pathogenesis and classification of eosinophil disorders: a review of recent developments in the field

Eosinophils and their products play an essential role in the pathogenesis of various reactive and neoplastic disorders. Depending on the underlying disease, molecular defect and involved cytokines, hypereosinophilia may develop and may lead to organ damage. In other patients, persistent eosinophilia is accompanied by typical clinical findings, but the causative role and impact of eosinophilia remain uncertain. For patients with eosinophil-mediated organ pathology, early therapeutic intervention with agents reducing eosinophil counts can be effective in limiting or preventing irreversible organ damage. Therefore, it is important to approach eosinophil disorders and related syndromes early by using established criteria, to perform all appropriate staging investigations, and to search for molecular targets of therapy. In this article, we review current concepts in the pathogenesis and evolution of eosinophilia and eosinophil-related organ damage in neoplastic and non-neoplastic conditions. In addition, we discuss classifications of eosinophil disorders and related syndromes as well as diagnostic algorithms and standard treatment for various eosinophil-related disorders.

Cockroach allergens induce biphasic asthma-like pulmonary inflammation in outbred mice

OBJECTIVES

The aim of this study is to define the kinetics of the pulmonary inflammatory response in cockroach allergen (CRA) sensitized and challenged outbred mice.

METHODS

Asthma-like pulmonary inflammation was induced with three pulmonary exposures to CRA, without the use of adjuvants. Mice were sacrificed at multiple time points and asthma-like pulmonary inflammation quantified.

RESULTS

Several pulmonary parameters showed a pronounced biphasic inflammatory response with an early stage (1.5 hours post challenge) and late stage (24 hours). The initial phase was characterized by the production of multiple inflammatory mediators, including CXC chemokines, and the recruitment of neutrophils to the lung. The number of pulmonary eosinophils decreased in the early phase but quickly rebounded. Both the early and late phases had increases in TNF production in addition to airways hyperreactivity. The model also demonstrated early production of mucin with clearance by 12 hours followed by new accumulation of mucin in the pulmonary epithelial cells. Eotaxins within the lung peaked at about 12 hours and the numbers of eosinophils in the lung remained constant throughout the 48 hours of the study.

CONCLUSIONS

The pulmonary inflammatory parameters in response to a clinically relevant allergen define a biphasic response. These data may be used to investigate the pathogenesis of the disease and develop targeted therapies for the distinct phases.

Distribution of Inflammatory Cells, Adhesion Molecules, Intermediate Filaments, and Chemokine Receptors in Subgroups of Nasal Polyp Patients

Background

The pathogenesis of nasal polyps (NPs) is incompletely understood. The aim of this study was to investigate the distribution of inflammatory cells, adhesion molecules, intermediate filaments, and chemokine receptors in subgroups of NP patients.

Methods

In total, 35 patients were enrolled (group 1, 10 patients with Samter syndrome; group 2, 10 patients with diffuse polyposis without signs of Samter syndrome; group 3: 5 patients with solitary nasal polyps; group 4, 10 controls). Immunohistochemical staining was performed for CD105, CD106, CD62E, CD4, CD8, CXCR4, CD147, CD90, CD104, BF45, vimentin, pancytokeratin, and muscle-specific actin (MSA) in all patients’ specimens.

Results

Expression of CD4, CD8, and CD106 were similar between the groups. Number of patients expressing CD4 in groups 1, 2, and 3 were higher than the controls. Number of patients expressing CD8 antigen were significantly higher in all three groups than in the control group. Expression of CD147 in groups 3 and 4 was significantly higher than in groups 1 and 2. CD98 expression was higher in groups 1, 2, and 3 than in group 4. The number of patients expressing vimentin in groups 1, 2, and 3 was significantly higher than in group 4. Immunostaining for pancytokeratin was positive in all patients.

Conclusion

In conclusion, inflammatory cell, adhesion molecule, intermediate filament, and chemokine receptor profiles in nasal polyps differ among different patient groups and control subjects. Additional specific immunohistochemical studies are necessary for development of more specific immunotherapies.

Eosinophils: multifaceted biological properties and roles in health and disease

Eosinophils are leukocytes resident in mucosal tissues. During T-helper 2 (Th2)-type inflammation, eosinophils are recruited from bone marrow and blood to the sites of immune response. While eosinophils have been considered end-stage cells involved in host protection against parasite infection and immunopathology in hypersensitivity disease, recent studies changed this perspective. Eosinophils are now considered multifunctional leukocytes involved in tissue homeostasis, modulation of adaptive immune responses, and innate immunity to certain microbes. Eosinophils are capable of producing immunoregulatory cytokines and are actively involved in regulation of Th2-type immune responses. However, such new information does not preclude earlier observations showing that eosinophils, in particular human eosinophils, are also effector cells with proinflammatory and destructive capabilities. Eosinophils with activation phenotypes are observed in biological specimens from patients with disease, and deposition of eosinophil products is readily seen in the affected tissues from these patients. Therefore, it would be reasonable to consider the eosinophil a multifaceted leukocyte that contributes to various physiological and pathological processes depending on their location and activation status. This review summarizes the emerging concept of the multifaceted immunobiology of eosinophils and discusses the roles of eosinophils in health and disease and the challenges and perspectives in the field.

Effects of the cyclin-dependent kinase inhibitor R-roscovitine on eosinophil survival and clearance

BACKGROUND

Eosinophils are pro-inflammatory cells implicated in the pathogenesis of asthma and atopy. Apoptosis has been proposed as a potential mechanism underlying the resolution of eosinophilic inflammation and studies have indicated the ability of interventions that induce human eosinophil apoptosis to promote the resolution of eosinophilic inflammation. Recently, the cyclin-dependent kinase (CDK) inhibitor R-roscovitine was shown to enhance neutrophil apoptosis and promote the resolution of neutrophilic inflammation.

OBJECTIVE

The purpose of this study was to examine the expression of CDKs in human blood eosinophils, the effects of R-roscovitine on eosinophil survival in vitro and whether R-roscovitine could influence eosinophilic lung inflammation in vivo.

METHODS

Eosinophils were isolated from human peripheral blood and the effects of R-roscovitine on apoptosis, degranulation and phagocytic uptake examined in vitro. The effects of R-roscovitine on eosinophilic lung inflammation in vivo were also assessed using an ovalbumin mouse model.

RESULTS

Our data demonstrate that human eosinophils express five known targets for R-roscovitine: CDK1, -2, -5, -7 and -9. R-roscovitine induced eosinophil apoptosis in a time- and concentration-dependent manner but also accelerated transition to secondary necrosis as assessed by microscopy, flow cytometry and caspase activation. In addition, we show that R-roscovitine can override the anti-apoptotic signals of GM-CSF and IL-5. We report that the pro-apoptotic effect of R-roscovitine is associated with suppression of Mcl-1L expression and that this compound enhanced phagocytic clearance of eosinophils by macrophages. Finally, we show that R-roscovitine induces apoptosis in murine peripheral blood and spleen-derived eosinophils; despite this, R-roscovitine did not modulate the tissue and lumen eosinophilia characteristic of the ovalbumin mouse model of airway eosinophilia.

CONCLUSION AND CLINICAL RELEVANCE

These data demonstrate that R-roscovitine is capable of inducing rapid apoptosis and secondary necrosis in eosinophils but does not affect the onset or improve the resolution of eosinophilic airway inflammation in vivo.

Transforming Growth Factor-β1 Antagonizes Interleukin-5 Pro-Survival Signaling by Activating Calpain-1 in Primary Human Eosinophils

BACKGROUND

Eosinophils rapidly undergo apoptosis unless exposed to prosurvival cytokines such as interleukin 5 (IL-5) or granulocyte-macrophage colony stimulating factor (GM-CSF). In vivo, eosinophils are exposed to TGF-β 1 which can induce apoptosis suggesting it may function to counteract the effects of IL-5 or GM-CSF and limit, in vivo tissue eosinophilia.

OBJECTIVE

The objective of this study was to investigate the proapoptotic effects of TGF-β alone and in combination with IL-5 on eosinophils.

METHODS

Peripheral blood eosinophil (PBEos) viability was assessed using flow cytometry after exposure to TGF-β1 and IL-5. Calpain-1 activation was determined in cell extracts by western blot analysis of endogenous substrates and with a fluorogenic α-spectrin substrate. Molecular interactions between calpain1 and calpastatin were assessed by immunoprecipitation and western blotting.

RESULTS

Physiologic concentrations of TGF-β1 significantly antagonized the prosurvival effects of IL-5. TGF-β1-induced apoptosis was suppressed by inhibitors of calpain, or its downstream target, caspase 3. TGF-β1 signaling through Smad3 was unaffected by IL-5 and was required for the pro-apoptotic effects of TGF-β1. However, IL-5 induced Akt phosphorylation was inhibited by TGF-β1 and was associated with accelerated calpain cleavage and eosinophil death.

CONCLUSION

TGF-β1 induces calpain-1 activation through antagonism of Akt which induces caspase activation and eosinophil apoptosis.

Eosinophil survival and apoptosis in health and disease

Eosinophilia is common feature of many disorders, including allergic diseases. There are many factors that influence the production, migration, survival and death of the eosinophil. Apoptosis is the most common form of physiological cell death and a necessary process to maintain but limit cell numbers in humans and other species. It has been directly demonstrated that eosinophil apoptosis is delayed in allergic inflammatory sites, and that this mechanism contributes to the expansion of eosinophil numbers within tissues. Among the proteins known to influence hematopoiesis and survival, expression of the cytokine interleukin-5 appears to be uniquely important and specific for eosinophils. In contrast, eosinophil death can result from withdrawal of survival factors, but also by activation of pro-apoptotic pathways via death factors. Recent observations suggest a role for cell surface death receptors and mitochondria in facilitating eosinophil apoptosis, although the mechanisms that trigger each of these death pathways remain incompletely delineated. Ultimately, the control of eosinophil apoptosis may someday become another therapeutic strategy for treating allergic diseases and other eosinophil-associated disorders.

A TLR2 agonist in German cockroach frass activates MMP-9 release and is protective against allergic inflammation in mice

The role of TLR2 in modulating experimentally induced asthma is not fully understood. We recently identified that German cockroach (GC) frass contains a TLR2 ligand allowing us to investigate the role of a TLR2 agonist in a complex real world allergen in mediating allergic airway inflammation. GC frass exposure significantly increased airway inflammation, airway hyperresponsiveness and serum IgE levels in wild-type mice; however the same exposure in TLR2-deficient mice resulted in greatly exaggerated serum IgE and eosinophilia but diminished airway neutrophilia, suggesting a protective role for TLR2. Since GC frass inhalation usually induces airway neutrophilia, we queried the effect of neutrophil depletion on airway responses. Inhibition of neutrophil recruitment into the airways of naive wild-type mice before intratracheal inhalation of GC frass resulted in significantly increased levels of serum IgE and eosinophilia. Neutrophils are a rich source of MMP-9, and we found that MMP-9 levels were significantly increased in the airways of mice following exposure to GC frass. Importantly the levels of MMP-9 were significantly decreased in neutrophil-depleted and TLR2-deficient mice after exposure to GC frass, suggesting that TLR2 regulated MMP-9 release from neutrophils. Functionally, MMP-9-deficient mice had more acute allergic inflammation than wild-type mice, suggesting that MMP-9 was protective against experimentally induced asthma. These data suggest that TLR2 activation of neutrophils leads to release of MMP-9 which decreases allergic responses to GC frass. This suggests a protective role for TLR2 activation and MMP-9 release in the context of experimentally induced asthma in mice.

Age-related changes of transforming growth factor beta1 in Japanese children

BACKGROUND

Transforming growth factor beta1 (TGF beta 1) is an important factor in immunomodulation. The expression of TGF beta 1 has been shown to be influenced by the C-509T polymorphism in the TGF beta 1 gene. We investigated age-related changes of plasma TGF beta 1 levels in a birth-cohort study. In addition, the genotypes of the C-509T polymorphism were investigated in allergic and non-allergic subjects.

METHODS

Sixty-four neonates who met the following criteria were enrolled in this cohort study: 1) full-term vaginally delivery; 2) underwent DNA polymorphism analysis; and 3) questionnaire forms were filled out by parents at 0, 6 and 14 months of age. The umbilical cord blood at 0 months and peripheral blood at 6, and 14 months were collected. Plasma TGF beta1 levels were measured at 0, 6 and 14 months of age. Genomic DNA was extracted from their umbilical cord blood. The genotype of the subjects was examined for the presence of C-509T.

RESULTS

The plasma TGF beta 1 level at 6 months was the highest of the 3 measurements (at 0, 6, and 14 months of age). The TGF beta 1 levels at 14 months in allergic subjects were significantly higher than those in non-allergic subjects (p = 0.03). All subjects with bronchial asthma (n = 3) had the TT genotype of the C-509T polymorphism.

CONCLUSIONS

The plasma TGF beta 1 levels change with age. In addition, TGF beta 1 may play a role in the pathogenesis of bronchial asthma.

A phosphosite screen identifies autocrine TGF-beta-driven activation of protein kinase R as a survival-limiting factor for eosinophils

The differential usage of signaling pathways by chemokines and cytokines in eosinophils is largely unresolved. In this study, we investigate signaling similarities and differences between CCL11 (eotaxin) and IL-5 in a phosphosite screen of human eosinophils. We confirm many previously known pathways of cytokine and chemokine signaling and elucidate novel phosphoregulation in eosinophils. The signaling molecules that were stimulated by both agents were members of the ERK1/2 and p38 MAPK pathways and their downstream effectors such as RSK and MSK1/2. Both agents inhibited S6 kinase, protein kinase Cepsilon, and glycogen synthase kinase 3 alpha and beta. The molecules that were differentially regulated include STATs and protein kinase R (PKR). One of the chief findings in this investigation was that PKR and eukaryotic initiation factor 2alpha are phosphorylated under basal conditions in eosinophils and neutrophils. This basal phosphorylation was linked to autocrine secretion of TGF-beta in eosinophils. TGF-beta directly activates PKR in eosinophils. Basal phosphorylation of PKR was inhibited by incubation of eosinophils with a neutralizing anti-TGF-beta Ab suggesting its physiological importance. We show that inhibition of PKR activity prolongs eosinophil survival. The eosinophil survival factor IL-5 strongly suppresses phosphorylation of PKR. The biological relevance of IL-5 inhibition of phospho-PKR was established by the observation that ex vivo bone marrow-derived eosinophils from OVA-immunized mice had no PKR phosphorylation in contrast to the high level of phosphorylation in sham-immunized mice. Together, our findings suggest that survival of eosinophils is in part controlled by basal activation of PKR through autocrine TGF-beta and that this could be modulated by a Th2 microenvironment in vivo.

Transforming growth factor-beta regulates house dust mite-induced allergic airway inflammation but not airway remodeling

RATIONALE

It is now believed that both chronic airway inflammation and remodeling contribute significantly to airway dysfunction and clinical symptoms in allergic asthma. Transforming growth factor (TGF)-beta is a powerful regulator of both the tissue repair and inflammatory responses, and numerous experimental and clinical studies suggest that it may play an integral role in the pathogenesis of asthma.

OBJECTIVES

We investigated the role of TGF-beta in the regulation of allergic airway inflammation and remodeling using a mouse model of house dust mite (HDM)-induced chronic allergic airway disease.

METHODS

We have previously shown that intranasal administration of an HDM extract (5 d/wk for 5 wk) elicits robust Th2-polarized airway inflammation and remodeling that is associated with increased airway hyperreactivity. Here, Balb/c mice were similarly exposed to HDM and concurrently treated with a pan-specific TGF-beta neutralizing antibody.

MEASUREMENTS AND MAIN RESULTS

We observed that anti-TGF-beta treatment in the context of either continuous or intermittent HDM exposure had no effect on the development of HDM-induced airway remodeling. To further confirm these findings, we also subjected SMAD3 knockout mice to 5 weeks of HDM and observed that knockout mice developed airway remodeling to the same extent as HDM-exposed littermate controls. Notably, TGF-beta neutralization exacerbated the eosinophilic infiltrate and led to increased airway hyperreactivity.

CONCLUSIONS

Collectively, these data suggest that TGF-beta regulates HDM-induced chronic airway inflammation but not remodeling, and furthermore, caution against the use of therapeutic strategies aimed at interfering with TGF-beta activity in the treatment of this disease.

TGFB1 promoter polymorphism C-509T and pathophysiology of asthma

BACKGROUND

TGF-beta1 can modulate airway inflammation and exaggerate airway remodeling. A polymorphism of a promoter region of TGFB1, C-509T, might be associated with the development of asthma, but its pathophysiologic relevance remains poorly understood.

OBJECTIVE

We investigated relations of the C-509T polymorphism to airflow obstruction, sputum eosinophilia, and airway wall thickening, as assessed by means of computed tomography, in 85 patients with stable asthma.

METHODS

The CC, CT, and TT genotypes were examined by means of PCR and restriction enzyme fragment length polymorphism. At a selected bronchus, 3 indices of airway wall thickness were measured with an automatic method.

RESULTS

The CC, CT, and TT genotypes were found in 22, 46, and 17 patients, respectively. Serum TGF-beta1 levels were significantly associated with the polymorphism and were increased in the CT/TT genotypes. FEV(1) and sputum eosinophil percentages were also significantly associated with the polymorphism and were both decreased in the CT/TT genotypes. The polymorphism was unrelated to airway wall thickness.

CONCLUSION

In addition to increased serum TGF-beta1 levels, the T allele of the C-509T polymorphism is related to increased airflow obstruction but attenuated eosinophilic inflammation. The former relation is not attributed to thickening of the central airway walls. The latter relation might reflect the anti-inflammatory effect of TGF-beta1. The C-509T polymorphism has a complex role in asthma pathophysiology, presumably because of the diverse functions of TGF-beta1 and its various interactions with cells and humoral factors in vivo.

Mechanisms of eosinophilia in the pathogenesis of hypereosinophilic disorders

The increased numbers of activated eosinophils in the blood and tissues that typically accompany hypereosinophilic disorders result from a variety of mechanisms. Exciting advances in translating discoveries achieved from mouse models and molecular strategies to the clinic have led to a flurry of new therapeutics specifically designed to target eosinophil-associated diseases. So far, this form of hypothesis testing in humans in vivo through pharmacology generally has supported the paradigms generated in vitro and in animal models, raising hopes that a spectrum of novel therapies soon may become available to help those who have eosinophil-associated diseases.

Eosinophil apoptosis induced by fungal immunomodulatory peptide-fve via reducing IL-5alpha receptor

BACKGROUND/PURPOSE

Eosinophils are important effector cells in the pathogenesis of allergic bronchial asthma. Enhancement of eosinophil apoptosis has been considered to have therapeutic effect on allergic disease. Fungal immunomodulatory peptide (FIP)-fve has been reported to possess immunoprophylactic activities for allergic diseases. The purpose of this study was to investigate the modulation of FIP-fve on human eosinophil survival derived from allergic asthmatic patients.

METHODS

Eosinophils were obtained from allergic asthmatic patients and purified with the use of density gradients and immunomagnetic beads negative selection. Apoptosis was assessed by annexin V and propidium iodide. The apoptotic signal protein, CD95 and IL-5 receptor expression were assessed by Western blot and flow cytometric analysis.

RESULTS

When the eosinophils were treated with FIP-fve in the presence of IL-5, IL-5-enhanced eosinophil survival diminished. FIP-fve could reduce IL-5-mediated survival of eosinophils and decrease IL-5Ralpha expression. In the presence of FIP-fve, CD95 expression was upregulated and Bcl-xL and pro-caspase 3 expression were downregulated in cultured eosinophils.

CONCLUSION

The results suggest that FIP-fve can inhibit IL-5-mediated survival of eosinophils through the modulation of cytokine receptor expression and apoptotic signal protein production. The modulatory effect of FIP-fve on eosinophil apoptosis in vitro indicates that it may have some therapeutic effect on eosinophil-related allergic inflammation in vivo.

Pathogenesis of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogenous disorder and represents a major public health problem. Although insights into the pathophysiology of CRS have largely expanded over the last two decades, the exact etiology and mechanism of persistence is still unrevealed. CRS is a multifactorial disease, and, with variable evidence, impaired ostial patency, mucociliary impairment, allergy, bacterial or fungal infection (or triggering), immunocompromised state, and environmental and genetic factors have been suggested to be associated or risk factors. Pathomechanisms in CRS are better understood currently, allowing us to characterize and differentiate the heterogeneous pathology of chronic sinonasal inflammation based on histopathology, inflammatory pattern, cytokine profile, and remodeling processes. In nasal polyposis (NP), but not CRS without NP, an abundant eosinophilic inflammation and local immunoglobulin E production could be demonstrated, and Staphylococcus-derived superantigens may at least modulate disease severity and expression. These findings question the current assumption that NP is a subgroup of CRS, but suggest that CRS and NP should probably be considered as distinct disease entities.

Pattern of inflammation and impact of Staphylococcus aureus enterotoxins in nasal polyps from southern China

BACKGROUND

This study analyzes the impact of Staphylococcus aureus enterotoxins (SAEs) and the inflammatory pattern in polyps from China.

METHODS

Nasal tissue was obtained from 27 consecutive bilateral nasal polyps and 15 control patients and assayed for eotaxin, interleukin-5, soluble interleukin-2 receptor, transforming growth factor (TGF) beta, myeloperoxidase, eosinophil cationic protein, total IgE, and specific IgE to SAEs. Activated eosinophils were stained using EG2 antibodies in polyps from Chinese and comparative white patients.

RESULTS

The number of EG2+ eosinophils was significantly lower in polyps from Chinese patients versus white patients. Chinese polyps showed significantly increased IgE and soluble interleukin-2 receptor versus control samples, whereas TGF-beta1 was significantly decreased. Ten of 27 samples in the polyp group versus 0 of 15 controls contained SAE-IgE (p < 0.01). TGF-beta1 was significantly down-regulated in SAE+ samples versus SAE- samples (p = 0.04).

CONCLUSION

Nasal polyps from China are characterized by B- and T-cell activation, a minor eosinophilic inflammation compared with polyps from white subjects, and a decrease in TGF-beta1 in comparison with control inferior turbinate tissue. One-third of patients with polyps showed an IgE response to SAEs.

Human eosinophils have an intact Smad signaling pathway leading to a major transforming growth factor-beta target gene expression

BACKGROUND

There is a paradoxical finding that eosinophils are frequently accumulated at the sites of allergic inflammation where transforming growth factor (TGF)-beta, a negative regulator of eosinophil survival, is upregulated; however, eosinophil accumulation is persistent. We thus hypothesized that eosinophils might have aberrant TGF-beta signaling and be unresponsive to TGF-beta. To test the hypothesis, we examined the expression and function of Smad proteins, which are central mediators for TGF-beta signaling, in human eosinophils.

METHODS

Eosinophils were isolated from the peripheral blood of normal donors, and the expression and activation of endogenous Smad proteins were examined by reverse transcription polymerase chain reaction and Western blotting. The Smad function in the transcription of the major TGF-beta target gene Smad7 was investigated using a dominant negative form of Smad3. The effect of TGF-beta on eosinophil survival was then evaluated by a cell viability assay using normal and asthmatic eosinophils.

RESULTS

Human eosinophils expressed mRNAs and proteins of TGF-beta typeI and type II receptors, Smad2, Smad3 and Smad4. TGF-beta induced the phosphorylation of Smad2 in eosinophils, which was blocked by SB431542, an inhibitor of TGF-beta type I receptor kinase. A dominant negative Smad3 protein suppressed TGF-beta-induced Smad7 mRNA expression in eosinophils. Finally, TGF-beta prevented granulocyte macrophage colony-stimulating factor- or interferon-gamma-mediated survival of eosinophils obtained from asthmatic patients as well as normal subjects.

CONCLUSION

Human eosinophils have an intact Smad signaling pathway leading to a major TGF-beta target gene expression. Thus, eosinophils might become resistant to TGF-beta only in in vivo circumstances.

Differentiation of chronic sinus diseases by measurement of inflammatory mediators

BACKGROUND

Chronic rhinosinusitis (CRS) clinically is a heterogeneous group of sinus diseases, which may cover different disease entities, or may represent a disease continuum. Studying inflammatory cells and mediators in clearly defined disease subgroups may lead to a better differentiation of chronic sinus diseases.

METHODS

Sinonasal mucosal tissue from 10 nasal polyp (NP) patients, 13 cystic fibrosis patients (CF-NP), eight CRS subjects without polyps, and nine control patients were stained for CD3, CD25, CD68, CD20, myeloperoxidase (MPO), CD138 and tissue homogenates were assayed for eotaxin, interleukin (IL)-1beta, IL-2sRalpha, IL-5, interferon (IFN)-gamma, IL-8, transforming growth factor (TGF)-beta1, tumor necrosis factor-alpha, and MPO by enzyme-linked immunosorbent assay or UNICAP system.

RESULTS

Nasal polyp and CF-NP showed increased numbers and activation of T cells, while only NP displayed an increase in plasma cells. Nasal polyp had significantly higher levels of eosinophilic markers [eosinophils, eotaxin, and eosinophil cationic protein (ECP)] compared with CRS, controls and CF-NP. Chronic rhinosinusitis was characterized by a Th1 polarization with high levels of IFN-gamma and TGF-beta, while NP showed a Th2 polarization with high IL-5 and immunoglobulin (Ig) E concentrations. Nasal polyp and CF-NP were discriminated by edema from CRS and controls, with CF-NP displaying a very prominent neutrophilic inflammation.

CONCLUSION

Based on cellular and mediator profiles, we suggest that CRS, NP, and CF-NP are distinct disease entities within the group of chronic sinus diseases.

The role of sinus disease in asthma

PURPOSE OF REVIEW

Some time ago, a link between upper and lower respiratory disease was described, which gave rise to the concept of 'united airways disease'. This concept primarily refers to the well established link between allergic rhinitis and asthma, but it also covers a possible link between sinus disease and asthma (allergic or nonallergic) and other lower airway disease.

RECENT FINDINGS

The current classification of chronic rhinosinusitis (CRS) includes disease without and with nasal polyps, which are considered subgroups of CRS. Different patterns of inflammatory and regulatory cytokines (involving distinguishable T-helper lymphocyte populations) and of remodelling markers, however, were recently described to differentiate nasal polyposis from CRS, yielding two discrete entities. These patterns resemble those of lower airway diseases, such as asthma and chronic obstructive pulmonary disease, and suggest a common aetiological/pathogenetic background. Whereas the link between nasal polyps and asthma is well established (indeed, asthma improves after medical or surgical treatment of sinus disease), that between CRS and lower airway disease is not well understood. Recently, Staphylococcus aureus enterotoxins, acting as superantigens, were identified as a possible link between nasal polyps and asthma, resulting in severe disease manifestations in both upper and lower airways.

SUMMARY

The role played by sinus disease in asthma is only partially understood, largely because of deficits in the clinical classification and in basic knowledge of pathophysiological pathways. Recent research into upper airway and sinus inflammation and remodelling may reveal new perspectives and lead to a classification of sinus disease, which will facilitate appropriate clinical and epidemiological studies.

Transforming growth factor-beta regulation of immune responses

Transforming growth factor-beta (TGF-beta) is a potent regulatory cytokine with diverse effects on hemopoietic cells. The pivotal function of TGF-beta in the immune system is to maintain tolerance via the regulation of lymphocyte proliferation, differentiation, and survival. In addition, TGF-beta controls the initiation and resolution of inflammatory responses through the regulation of chemotaxis, activation, and survival of lymphocytes, natural killer cells, dendritic cells, macrophages, mast cells, and granulocytes. The regulatory activity of TGF-beta is modulated by the cell differentiation state and by the presence of inflammatory cytokines and costimulatory molecules. Collectively, TGF-beta inhibits the development of immunopathology to self or nonharmful antigens without compromising immune responses to pathogens. This review highlights the findings that have advanced our understanding of TGF-beta in the immune system and in disease.

Apoptosis Induction by Retinoids in Eosinophilic Leukemia Cells: Implication of Retinoic Acid Receptor-α Signaling in All-Trans-Retinoic Acid Hypersensitivity

Hypereosinophilic syndrome (HES) has recently been recognized as a clonal leukemic lesion, which is due to a specific oncogenic event that generates hyperactive platelet-derived growth factor receptor-alpha-derived tyrosine kinase fusion proteins. In the present work, the effect of retinoids on the leukemic hypereosinophilia-derived EoL-1 cell line and on primary HES-derived cells has been investigated. We show that all-trans-retinoic acid (ATRA) inhibits eosinophil colony formation of HES-derived bone marrow cells and is a powerful inducer of apoptosis of the EoL-1 cell line. Apoptosis was shown in the nanomolar concentration range by phosphatidylserine externalization, proapoptotic shift of the Bcl-2/Bak ratio, drop in mitochondrial membrane potential, activation of caspases, and cellular morphology. Unlike in other ATRA-sensitive myeloid leukemia models, apoptosis was rapid and was not preceded by terminal cell differentiation. Use of isoform-selective synthetic retinoids indicated that retinoic acid receptor-alpha-dependent signaling is sufficient to induce apoptosis of EoL-1 cells. Our work shows that the scope of ATRA-induced apoptosis of malignancies may be wider within the myeloid lineage than thought previously, that the EoL-1 cell line constitutes a new and unique model for the study of ATRA-induced cell death, and that ATRA may have potential for the management of clonal HES.

Growth, phenotype, and function of human intestinal mast cells are tightly regulated by transforming growth factor beta1

BACKGROUND AND AIMS

Transforming growth factor beta1 (TGF-beta1) is expressed in the healthy human intestine and controls mucosal immune responses and inflammation by regulating the function of lymphocytes, macrophages, dendritic cells, and eosinophils. Here, we asked whether human intestinal mast cells (MC) might also be subject to immunoregulation by TGF-beta1.

METHODS

MC were isolated from the intestinal mucosa, purified, and cultured in vitro in the presence of stem cell factor (SCF) with or without TGF-beta1. Growth characteristics, phenotype, and immunological mediator release of MC were analysed by reverse transcription-polymerase chain reaction, flow cytometry, immunocytochemistry, western blot, and different immunoassays, respectively.

RESULTS

TGF-beta1 dose dependently (ED50 approximately = 0.1 ng/ml) inhibited SCF dependent growth of human intestinal MC by both enhancing apoptosis and decreasing proliferation. In parallel, TGF-beta1 increased the percentage of connective tissue-type MC expressing tryptase and chymase while downregulating expression of the receptors for IgE and SCF. Furthermore, TGF-beta1 dramatically changed the profile of mediators released by MC following IgE receptor crosslinking. Release of histamine, cysteinyl-leukotrienes, and tumour necrosis factor alpha was strongly reduced whereas prostaglandin D2 generation and cyclooxygenase 1 and 2 expression were upregulated by TGF-beta1.

CONCLUSIONS

Our data indicate that TGF-beta1 acts as a novel potent inhibitor and modulator of human intestinal MC effector functions. The change in MC mediator release profile and protease expression induced by TGF-beta1 might be of relevance for the control of MC associated disorders of the intestine such as allergic reactions, Crohn's disease, irritable bowel syndrome, and parasitic infection.

Expression of interleukin-13 receptor alpha 1-subunit on peripheral blood eosinophils is regulated by cytokines

Interleukin-13 (IL-13) is critical for the development of allergic asthma and is involved in the activation of eosinophils within the airways. IL-13 exerts its activity on target cells via the dimeric IL-13 receptor (IL-13R), which comprises the IL-13 receptor alpha1-chain (IL-13Ralpha1) as a specific component. The aim of this study was to investigate the expression of the IL-13Ralpha1-chain on primary human eosinophilic granulocytes. Furthermore, it addresses the regulatory influence of cytokines on the level of surface abundance of this receptor subunit. Expression of IL-13- and IL-4-receptor subunits in purified primary human eosinophils was monitored at the messenger RNA level by reverse transcription polymerase chain reaction and at the protein level by flow cytometry. For the analysis of IL-13Ralpha1 surface expression, a new monoclonal antibody, which was generated using genetic immunization, was employed. Different cytokines with established activity on eosinophils were studied with regard to their influence on IL-13Ralpha1 in vitro by flow cytometry. Whereas IL-13 and IL-4 had inhibitory effects on IL-13Ralpha1 expression on eosinophils, interferon-gamma, tumour necrosis factor-alpha, and, to the largest extent, transforming growth factor-beta, enhanced the expression of this receptor subunit. A positive regulatory response evoked by transforming growth factor-beta and interferon-gamma does not prevent inhibitory effects caused by IL-13. These findings suggest a regulatory cytokine network influencing the reactivity of eosinophils to IL-13.

In vitro effects of flunisolide on MMP-9, TIMP-1, fibronectin, TGF-beta1 release and apoptosis in sputum cells freshly isolated from mild to moderate asthmatics

BACKGROUND

Corticosteroids play an important role in inflammation and remodelling of airways and are considered an important therapeutic target in asthma. Inflammation in asthma is characterized by a dysregulation of eosinophil apoptosis and of markers of airways remodelling. We evaluated the ability of flunisolide to inhibit in vitro the release of metalloproteinases-9 (MMP-9), tissue inhibitor metalloproteinases-1 (TIMP-1), transforming growth factor (TGF-beta) and fibronectin by sputum cells (SC) as well as to induce sputum eosinophil apoptosis.

METHODS

The SC, isolated from induced sputum samples of 12 mild-to-moderate asthmatics, were cultured for 24 h in the presence or absence of flunisolide (1, 10 and 100 microM). The release of mediators was assessed by enzyme-linked immunosorbent assay (ELISA) whereas apoptosis was studied by TUNEL technique.

RESULTS

Flunisolide (10 microM) significantly reduced MMP-9 and TIMP-1 (P = 0.0011 and P < 0.0001 respectively) and increased MMP-9/TIMP-1 molar ratio (P = 0.004). In addition, flunisolide decreased TGF-beta and fibronectin release by SC (P = 0.006; and P < 0.0001 respectively) and increased eosinophil apoptosis (P < 0.001).

CONCLUSIONS

These results demonstrate that flunisolide may play an important role in the inhibition of airway inflammation and remodelling, by promoting the resolution of eosinophilic inflammation and by inhibiting the release of MMP-9, TIMP-1, TGF-beta and fibronectin.