Human eosinophils express transforming growth factor alpha

Tumor-associated tissue eosinophilia promotes angiogenesis and metastasis in head and neck squamous cell carcinoma

Eosinophils are terminally differentiated leukocytes that participate in the process of chronic inflammation and allergy and are able to release multiple cytokines into the surrounding tissue environment. Tumor-associated tissue eosinophilia (TATE) is the presence of eosinophils in the tumor or in the neighboring stroma and has been observed in various types of cancer. In head and neck squamous cell carcinoma (HNSCC), the clinical relevance of TATE has not been concluded yet because of the inconsistent results in different studies. In our study, we focus on the prognostic effects of TATE on HNSCC and how TATE can influence tumor behavior and tumor microenvironment. We first showed that in both the TCGA-HNSC cohort and our cohort of patients with HNSCC who had received curative surgery, TATE is correlated with worse overall survival. To investigate the underlying mechanism of how TATE leads to poor clinical outcomes, we showed that activated eosinophils produce a variety of cytokines and chemokines, and activated TATE-derived culture medium promotes tumor migration mainly through CCL2. We also showed that eosinophils are capable of inducing angiogenesis and that HNSCC samples enriched with TATE are highly correlated with tumor angiogenesis. Furthermore, HNSCC enriched with TATE had more aggressive pathological features, including regional lymph node metastasis, perineural invasion, lymphovascular invasion, and tumor growth. Lastly, we showed that HNSCC enriched with TATE is associated with immunosuppressive tumor microenvironment. Taken together, our results suggest that TATE promotes cancer metastasis and angiogenesis which results in a poor clinical outcomes in HNSCC.

Role of EGF Receptor Regulatory Networks in the Host Response to Viral Infections

In this review article, we will first provide a brief overview of EGF receptor (EGFR) structure and function, and its importance as a therapeutic target in epithelial carcinomas. We will then compare what is currently known about canonical EGFR trafficking pathways that are triggered by ligand binding, versus ligand-independent pathways activated by a variety of intrinsic and environmentally induced cellular stresses. Next, we will review the literature regarding the role of EGFR as a host factor with critical roles facilitating viral cell entry and replication. Here we will focus on pathogens exploiting virus-encoded and endogenous EGFR ligands, as well as EGFR-mediated trafficking and signaling pathways that have been co-opted by wild-type viruses and recombinant gene therapy vectors. We will also provide an overview of a recently discovered pathway regulating non-canonical EGFR trafficking and signaling that may be a common feature of viruses like human adenoviruses which signal through p38-mitogen activated protein kinase. We will conclude by discussing the emerging role of EGFR signaling in innate immunity to viral infections, and how viral evasion mechanisms are contributing to our understanding of fundamental EGFR biology.

Tissue factor promotes airway pathological features through epithelial-mesenchymal transition of bronchial epithelial cells in mice with house dust mite-induced asthma

It has recently been shown that expression levels of tissue factor (TF) are high in the serum and peripheral blood mononuclear cells of patients with asthma. However, whether TF impacts airway inflammation and remodelling in asthma remains unknown. The aim of this study was to investigate the effect of TF in asthma airway inflammation and remodelling using a house dust mite (HDM)-induced chronic asthma model and human bronchial epithelial (16HBE) cells. A chronic asthma model was constructed in BALB/c mice by the intranasal instillation of HDM. Mice were treated with short hairpin TF (shTF), and airway inflammation and remodelling features of asthma and epithelial-mesenchymal transition (EMT) were assessed. 16HBE cells were induced by transforming growth factor-β1 (TGF-β1) and HDM in the presence or absence of shTF; then, EMT markers and invasion and migration ability were determined. TF expression increased in the lung tissue and 16HBE cells when exposed to HDM. TF downregulation in the lung significantly reduced airway hyperresponsiveness, eosinophil inflammation, the EMT process, and levels of interleukin (IL)-4, IL-6, IL-13, and TGF-β1 in bronchoalveolar lavage fluid of asthmatic mice. Moreover, TF downregulation inhibited migration and incursion and decreased the expression levels of fibronectin 1 and TGF-β1, but increased the expression of E-cadherin in HDM- and TGF-β1-stimulated 16HBE cells. These results demonstrated that TF promoted airway pathological features by enhancing the EMT of bronchial epithelial cells both in vitro and in mice with house dust mite-induced asthma.

Eosinophils in Eosinophilic Esophagitis: The Road to Fibrostenosis is Paved With Good Intentions

Eosinophilic esophagitis (EoE) is an antigen-driven disease associated with epithelial barrier dysfunction and chronic type 2 inflammation. Eosinophils are the defining feature of EoE histopathology but relatively little is known about their role in disease onset and progression. Classically defined as destructive, end-stage effector cells, eosinophils (a resident leukocyte in most of the GI tract) are increasingly understood to play roles in local immunity, tissue homeostasis, remodeling, and repair. Indeed, asymptomatic esophageal eosinophilia is observed in IgE-mediated food allergy. Interestingly, EoE is a potential complication of oral immunotherapy (OIT) for food allergy. However, we recently found that patients with peanut allergy may have asymptomatic esophageal eosinophilia at baseline and that peanut OIT induces transient esophageal eosinophilia in most subjects. This is seemingly at odds with multiple studies which have shown that EoE disease severity correlates with tissue eosinophilia. Herein, we review the potential role of eosinophils in EoE at different stages of disease pathogenesis. Based on current literature we suggest the following: (1) eosinophils are recruited to the esophagus as a homeostatic response to epithelial barrier disruption; (2) eosinophils mediate barrier-protective activities including local antibody production, mucus production and epithelial turnover; and (3) when type 2 inflammation persists, eosinophils promote fibrosis.

Biomarkers for Overweight in Adult-Onset Asthma

Purpose

Overweight and obesity are associated with one of the severe phenotypes of asthma, with an increased rate of exacerbations, low level of lung function, and reduced response to corticosteroid therapy. The present study focused on identifying useful biomarkers of severity in overweight patients with adult-onset asthma using real-world data.

Patients and Methods

A total of 56 patients with adult-onset asthma who visited Saga University Hospital between 2018 and 2019 were retrospectively reviewed. Overweight was defined as a body mass index (BMI) greater than 25 kg/m². Blood eosinophils, cytokines, and chemokines were compared between non-overweight asthma and overweight asthma patients.

Results

Overweight asthma patients had a higher annual exacerbation rate, lower pulmonary function even when treated frequently with high-dose inhaled corticosteroids, and a significantly lower percentage of eosinophils and lower eosinophil count compared to non-overweight asthma patients (p<0.01, p=0.03). Moreover, the percentage of eosinophils was significantly negatively correlated with BMI (ρ=−0.38, p<0.01) (Figure 1). On serum cytokine and chemokine analyses, the overweight asthma group included significantly more patients with a lower level of tissue growth factor α (TGF-α) (1.1 pg/mL) and higher levels of hsIL-6 (2.5 pg/mL), RANTES/CCL5 (298.5 pg/mL), and vascular endothelial growth factor A (VEGF-A) (63.7 pg/mL), than the non-overweight asthma group (p=0.02, p<0.01, p=0.02, p=0.01, respectively).

Conclusion

The present study showed that overweight patients with adult-onset asthma were characterized by a higher rate of annual exacerbations and worse lung function despite treatment with high-dose inhaled corticosteroids and lower blood eosinophil counts than non-overweight patients with asthma. On blood cytokine and chemokine analyses, a low level of TGF-α and high levels of hsIL-6, RANTES/CCL5, and VEGF-A might be biomarkers reflecting the pathophysiology in overweight patients with asthma.

Elevated eosinophil level predicted long time to next treatment in relapsed or refractory myeloma patients treated with lenalidomide

Lenalidomide is an immunomodulatory drug that is administered commonly in patients with relapsed or refractory multiple myeloma (RRMM). Eosinophils have immunological functions, for instance, in allergic diseases and asthma. The purpose of this study was to investigate the clinical significance of elevated eosinophil levels in patients with RRMM treated with lenalidomide. A total of 59 patients were included. Elevated eosinophil level was defined as an increase in the eosinophil count of ≥250/µL from the eosinophil count on day 1 during the first cycle. The percentage of patients with elevated eosinophil levels was 22.0%. The overall response ratio in the elevated eosinophil group and nonelevated eosinophil group was 84.6% and 63.0% (P = .189), respectively. The median time to next treatment (TTNT) in the elevated eosinophil group was significantly longer than that in the nonelevated group (40.3 months vs 8.4 months; P = .017). Additionally, TTNT in the elevated eosinophil group with partial response (PR) or better was significantly longer than that in the nonelevated eosinophil group with PR or better (40.3 months vs 11.9 months; P = .021). We concluded that elevated eosinophil levels were frequently observed and might predict a longer TTNT in patients with RRMM treated with lenalidomide.

Synergy of Interleukin (IL)-5 and IL-18 in eosinophil mediated pathogenesis of allergic diseases

Eosinophils are circulating granulocytes that have pleiotropic effects in response to inflammatory signals in the body. In response to allergens or pathogens, exposure eosinophils are recruited in various organs that execute pathological immune responses. IL-5 plays a key role in the differentiation, development, and survival of eosinophils. Eosinophils are involved in a variety of allergic diseases including asthma, dermatitis and various gastrointestinal disorders (EGID). IL-5 signal transduction involves JAK-STAT-p38MAPK-NFκB activation and executes extracellular matrix remodeling, EMT transition and immune responses in allergic diseases. IL-18 is a classical cytokine also involved in immune responses and has a critical role in inflammasome pathway. We recently identified the IL-18 role in the generation, transformation, and maturation of (CD101+CD274+) pathogenic eosinophils. In, addition, several other cytokines like IL-2, IL-4, IL-13, IL-21, and IL-33 also contribute in advancing eosinophils associated immune responses in innate and adaptive immunity. This review discusses with a major focus (1) Eosinophils and its constituents, (2) Role of IL-5 and IL-18 in eosinophils development, transformation, maturation, signal transduction of IL-5 and IL-18, (3) The role of eosinophils in allergic disorders and (4) The role of several other associated cytokines in promoting eosinophils mediated allergic diseases.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

Eosinophil cytokines, chemokines, and growth factors: emerging roles in immunity

Eosinophils derive from the bone marrow and circulate at low levels in the blood in healthy individuals. These granulated cells preferentially leave the circulation and marginate to tissues, where they are implicated in the regulation of innate and adaptive immunity. In diseases such as allergic inflammation, eosinophil numbers escalate markedly in the blood and tissues where inflammatory foci are located. Eosinophils possess a range of immunomodulatory factors that are released upon cell activation, including over 35 cytokines, growth factors, and chemokines. Unlike T and B cells, eosinophils can rapidly release cytokines within minutes in response to stimulation. While some cytokines are stored as pre-formed mediators in crystalloid granules and secretory vesicles, eosinophils are also capable of undergoing de novo synthesis and secretion of these immunological factors. Some of the molecular mechanisms that coordinate the final steps of cytokine secretion are hypothesized to involve binding of membrane fusion complexes comprised of soluble N-ethylmaleimide sensitive factor attachment protein receptors (SNAREs). These intracellular receptors regulate the release of granules and vesicles containing a range of secreted proteins, among which are cytokines and chemokines. Emerging evidence from both human and animal model-based research has suggested an active participation of eosinophils in several physiological/pathological processes such as immunomodulation and tissue remodeling. The observed eosinophil effector functions in health and disease implicate eosinophil cytokine secretion as a fundamental immunoregulatory process. The focus of this review is to describe the cytokines, growth factors, and chemokines that are elaborated by eosinophils, and to illustrate some of the intracellular events leading to the release of eosinophil-derived cytokines.

Eosinophil secretion of granule-derived cytokines

Eosinophils are tissue-dwelling leukocytes, present in the thymus, and gastrointestinal and genitourinary tracts of healthy individuals at baseline, and recruited, often in large numbers, to allergic inflammatory foci and sites of active tissue repair. The biological significance of eosinophils is vast and varied. In health, eosinophils support uterine and mammary gland development, and maintain bone marrow plasma cells and adipose tissue alternatively activated macrophages, while in response to tissue insult eosinophils function as inflammatory effector cells, and, in the wake of an inflammatory response, promote tissue regeneration, and wound healing. One common mechanism driving many of the diverse eosinophil functions is the regulated and differential secretion of a vast array of eosinophil-derived cytokines. Eosinophils are distinguished from most other leukocytes in that many, if not all, of the over three dozen eosinophil-derived cytokines are pre-synthesized and stored within intracellular granules, poised for very rapid, stimulus-induced secretion. Eosinophils engaged in cytokine secretion in situ utilize distinct pathways of cytokine release that include classical exocytosis, whereby granules themselves fuse with the plasma membrane and release their entire contents extracellularly; piecemeal degranulation, whereby granule-derived cytokines are selectively mobilized into vesicles that emerge from granules, traverse the cytoplasm and fuse with the plasma membrane to release discrete packets of cytokines; and eosinophil cytolysis, whereby intact granules are extruded from eosinophils, and deposited within tissues. In this latter scenario, extracellular granules can themselves function as stimulus-responsive secretory-competent organelles within the tissue. Here, we review the distinctive processes of differential secretion of eosinophil granule-derived cytokines.

Genes and oral cancer

Oral cancers have been one of the leading causes of deaths particularly in the developing countries. Prime reason for this high mortality and morbidity is attributed to the delay in diagnosis and prompt treatment. Relentless research in the field of oncology has led to the advent of novel procedures for the early detection of oral cancers. Molecular biology is highly promising in this regard. It is a procedure that detects alterations at a molecular level much before they are seen under a microscope and much before clinical changes occur. Molecular studies serve as the basis by which we will eventually be able not only to augment clinical assessment and classification of oral lesions but also predict malignant potential of oral lesions, thus reducing the incidence and increasing the scope for early diagnosis and treatment of oral cancers. However, making such sophisticated tools available for the common man in developing countries is one of the most important challenges faced today.

Potential for improving therapy and defining new research targets in eosinophilic oesophagitis based on understanding of immunopathogenesis

OBJECTIVES

This review considers the potential for therapeutic advances in the management of eosinophilic oesophagitis (EoE) based on recently increased understanding of the pathophysiology of the disorder.

METHODS

This is a review of publications characterising mucosal changes and leucocyte recruitment patterns in human and experimental EoE.

RESULTS

EoE, although diagnosed by epithelial infiltration of eosinophils, is actually a transmural inflammation in which eosinophil recruitment occurs via the deeper layers. Penetration of eosinophils into the epithelium is variable, explaining the need for multiple biopsies to diagnose what may be a clearly visible disorder. Fibrosis and neuromuscular dysfunction both occur within the subepithelial tissues. Recent murine studies have identified that T-cell recruitment underpins antigen-specific oesophageal eosinophil recruitment. Involvement of innate immunity is also suggested by the role of invariant natural killer T cells in experimental EoE.

CONCLUSIONS

Looking beyond present therapeutic options with a view to future studies, we identify T cells as candidates for "upstream therapy" if antigen specificity or homing markers are determined. Evidence of aeroallergen sensitisation suggests the possibility of lymphocyte priming within nasal-associated lymphoid tissue or Waldeyer ring, with the potential for topical therapy. We consider acquired neuromuscular dysfunction as a therapeutic target in acute symptomatic deterioration or bolus obstruction. We assess possible similarities with therapeutic stratagems for chronic asthma, recognising at the same time the anatomic specificity of the oesophagus and the difficulty in delivering effective topical medication to subepithelial tissues in this location compared with the airway.

Bronchiolitis obliterans associated with Stevens-Johnson Syndrome: histopathological bronchial reconstruction of the whole lung and immunohistochemical study

This study presents an extremely rare case of constrictive bronchiolitis obliterans (BO) associated with Stevens-Johnson Syndrome (SJS) provides the morphological and immunohistochemical features using histopathological bronchial reconstruction technique. A 27-year-old female developed progressive dyspnea after SJS induced by taking amoxicillin at the age of 10. Finally, she died of exacerbation of type II respiratory failure after 17 years from clinically diagnosed as having BO. Macroscopic bronchial reconstruction of the whole lungs at autopsy showed the beginning of bronchial obliterations was in the 4th to 5th branches, numbering from each segmental bronchus. Once they were obliterated, the distal and proximal bronchi were dilated. Microscopic bronchial reconstruction demonstrated the localization of obliteration was mainly from small bronchi to membranous bronchioli with intermittent airway luminal narrowing or obliteration. Moreover, CD3-, CD20-, and CD68-positive cells were found in the BO lesions. CD34- and D2-40-positive cells were mainly distributed in the peribronchiolar lesions and bronchiolar lumens, respectively. SMA- and TGF-β-positive cells were seen in the fibrous tissue of BO lesions.

Therapeutic strategies for harnessing human eosinophils in allergic inflammation, hypereosinophilic disorders, and cancer

The eosinophil is a multifunctional granulocyte best known for providing host defense against parasites. Paradoxically, eosinophils are also implicated in the pathogenesis of allergic inflammation, asthma, and hypereosinophilic syndromes. Emerging evidence also supports the potential for harnessing the cytotoxic power of eosinophils and redirecting it to kill solid tumors. Central to eosinophil physiology is interleukin-5 (IL-5) and its receptor (IL-5R) which is composed of a ligand-specific alpha chain (IL-5Rα) and the common beta chain (βc). Eosinophil activation can lead to their degranulation, resulting in rapid release of an arsenal of tissue-destructive proinflammatory mediators and cytotoxic proteins that can be both beneficial and detrimental to the host. This review discusses eosinophil immunobiology and therapeutic strategies for targeting of IL-5 and IL-5R, as well as the potential for harnessing eosinophil cytotoxicity as a tumoricide.

Th2 cells and cytokine networks in allergic inflammation of the lung

The cytokines released from Th2 and Th2-like cells are likely to be central to the pathophysiolgy of asthma and allergy, contributing to aberrant IgE production, eosinophilia and, perhaps, mucosal susceptibility to viral infection. IL-4 has emerged as a central target, not only for B cell IgE production, but also in the commitment of both CD4+ and CD8+ T cells to cells with Th2 effector function capable of secreting IL-5 resultlng in eosinophilic inflammation. In view of the central role of this cytokine and the evidence that glucocorticoids are unable to modify many IL-4 dependent effects, Th2 inhibitors may prove to be novel therapies for the treatment of bronchial asthma.

Serum Levels of Epidermal Growth Factor, Transforming Growth Factor, and c-erbB2 in Ovarian Cancer

Objective

This study aimed to investigate serum levels of epidermal growth factor (EGF), transforming growth factor α (TGF-α), and c-erbB2 in patients with ovarian cancer.

Materials and Methods

In this retrospective cohort study, the study and control groups were composed of 43 women with a prediagnosis of ovarian cancer and 43 healthy women, respectively. Blood samples from all women were obtained and studied by enzyme-linked immunosorbent assay kits for EGF, TGF-α, and c-erbB2. After surgery of the study group, ovarian cancer was confirmed and compared with control group. Stage, grade, and histological types were defined after histopathologic examination, and subgroups were constructed and compared.

Results

Serum EGF, TGF-α, and c-erbB2 levels were significantly increased in study group compared with those in the control group (P < 0.001). There were no differences in serum levels of EGF, TGF-α, and c-erbB2 among all stages, grades, and histological types of ovarian cancer. If 47.90 pg/mL was selected as the cutoff value, EGF has an 80% sensitivity and a 65% specificity for detecting ovarian cancer. The cutoff value of 41,095.00 pg/mL for TGF-α has a 90% sensitivity and a 72% specificity for detecting ovarian cancer. The c-erbB2 level of 4.63 pg/mL as the cutoff value has an 83% sensitivity and a 76% specificity for predicting ovarian cancer.

Conclusions

Serum levels of EGF, TGF-α, and c-erbB2 may be used for diagnosing ovarian cancer.

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.

Piecemeal degranulation in human eosinophils: a distinct secretion mechanism underlying inflammatory responses

Secretion is a fundamental cell process underlying different physiological and pathological events. In cells from the human immune system such as eosinophils, secretion of mediators generally occurs by means of piecemeal degranulation, an unconventional secretory pathway characterized by vesicular transport of small packets of materials from the cytoplasmic secretory granules to the cell surface. During piecemeal degranulation in eosinophils, a distinct transport vesicle system, which includes large, pleiomorphic vesiculo-tubular carriers is mobilized and enables regulated release of granule-stored proteins such as cytokines and major basic protein. Piecemeal degranulation underlies distinct functions of eosinophils as effector and immunoregulatory cells. This review focuses on the structural and functional advances that have been made over the last years concerning the intracellular trafficking and secretion of eosinophil proteins by piecemeal degranulation during inflammatory responses.

Role of transforming growth factor-β in airway remodeling in asthma

TGF-β is one of the main mediators involved in tissue remodeling in the asthmatic lung. This profibrotic cytokine is produced by a number of cells, including macrophages, epithelial cells, fibroblasts, and eosinophils. High expression of TGF-β in patients with asthma was reported by many investigators. However, controversy remains whether the concentration of TGF-β correlates with disease severity. TGF-β is believed to play an important role in most of the cellular biological processes leading to airway remodeling. It was shown to be involved in epithelial changes, subepithelial fibrosis, airway smooth muscle remodeling, and microvascular changes. Here, sources of TGF-β, as well as its role in the development of airway remodeling, will be reviewed. Therapeutic strategies that modulate TGF-β will also be discussed.

Eosinophilia in very low birth weight infants

BACKGROUND

Eosinophilia is common in premature infants, though its clinical significance remains unknown. This study investigated the pattern of eosinophilia and related factors in very low birth-weight (VLBW) infants.

METHODS

The medical records of VLBW infants (birth body weight < 1500 g) admitted to the neonatal intensive care unit of a tertiary care center of Cheng Kung University Hospital between January 2005 and June 2007 were analyzed. Complete blood counts (CBC) with differential leukocyte counts were performed weekly. Eosinophilia was defined as an eosinophil count of more than 0.700 x 10(9)/L. The possible related factors were analyzed.

RESULTS

A total of 142 infants were recruited into the study. Those who did not survive after the first 28 days and those with less than four available CBCs were excluded, leaving 107 infants and 828 CBC measurements. Overall, 19.0% of CBCs (157/828) indicated eosinophilia and 69.0% of all infants had at least one instance of eosinophilia during their hospital stay. Eosinophilia mainly occurred in the third week of life (27.1%), with an average peak eosinophil count of 0.520 x 10(9)/L. There were 37.3% of patients with mild eosinophilia (0.700-0.999 x 10(9)/L), 50.7% with moderate eosinophilia (1.000-2.999 x 10(9)/L), and 12% with severe eosinophilia (> or =3.000 x 10(9)/L). The demographic data and perinatal characteristics of infants with and without eosinophilia were comparable. Medical treatments including mechanical ventilation, antibiotic administration, total parenteral nutrition, intravenous catheterization, transfusion, and body weight gains were similar between the two groups. The eosinophil counts in the first week of life were significantly higher in infants with bronchopulmonary dysplasia (p < 0.05). They were also greater in VLBW infants with sepsis at the first, the third, the fourth, the fifth and the seventh weeks (p < 0.05).

CONCLUSION

Eosinophilia is common in VLBW infants and occurs mainly in the third week of life. Higher eosinophil counts were associated with sepsis and family history of atopic eczema. Bronchopulmonary dysplasia was associated with higher eosinophil counts in the first week of life.

G protein-coupled receptor 30 expression is up-regulated by EGF and TGF alpha in estrogen receptor alpha-positive cancer cells

In the present study, we evaluated the regulation of G protein-coupled receptor (GPR)30 expression in estrogen receptor (ER)-positive endometrial, ovarian, and estrogen-sensitive, as well as tamoxifen-resistant breast cancer cells. We demonstrate that epidermal growth factor (EGF) and TGF alpha transactivate the GPR30 promoter and accordingly up-regulate GPR30 mRNA and protein levels only in endometrial and tamoxifen-resistant breast cancer cells. These effects exerted by EGF and TGF alpha were dependent on EGF receptor (EGFR) expression and activation and involved phosphorylation of the Tyr(1045) and Tyr(1173) EGFR sites. Using gene-silencing experiments and specific pharmacological inhibitors, we have ascertained that EGF and TGF alpha induce GPR30 expression through the EGFR/ERK transduction pathway, and the recruitment of c-fos to the activator protein-1 site located within GPR30 promoter sequence. Interestingly, we show that functional cross talk of GPR30 with both activated EGFR and ER alpha relies on a physical interaction among these receptors, further extending the potential of estrogen to trigger a complex stimulatory signaling network in hormone-sensitive tumors. Given that EGFR/HER2 overexpression is associated with tamoxifen resistance, our data may suggest that ligand-activated EGFR could contribute to the failure of tamoxifen therapy also by up-regulating GPR30, which in turn could facilitates the action of estrogen. In addition, important for resistance is the ability of tamoxifen to bind to and activate GPR30, the expression of which is up-regulated by EGFR activation. Our results emphasize the need for new endocrine agents able to block widespread actions of estrogen without exerting any stimulatory activity on transduction pathways shared by the steroid and growth factor-signaling networks.

Immune cells and angiogenesis

Both innate and adaptive immune cells are involved in the mechanisms of endothelial cell proliferation, migration and activation, through the production and release of a large spectrum of pro-angiogenic mediators. These may create the specific microenvironment that favours an increased rate of tissue vascularization. In this review, we will focus on the immune cell component of the angiogenic process in inflammation and tumour growth. As angiogenesis is the result of a net balance between the activities exerted by positive and negative regulators, we will also provide information on some antiangiogenic properties of immune cells that may be utilized for a potential pharmacological use as antiangiogenic agents in inflammation as well as in cancer.

Intestinal hormones and growth factors: effects on the small intestine

There are various hormones and growth factors which may modify the intestinal absorption of nutrients, and which might thereby be useful in a therapeutic setting, such as in persons with short bowel syndrome. In part I, we focus first on insulin-like growth factors, epidermal and transferring growth factors, thyroid hormones and glucocorticosteroids. Part II will detail the effects of glucagon-like peptide (GLP)-2 on intestinal absorption and adaptation, and the potential for an additive effect of GLP2 plus steroids.

Allergy, asthma, and inflammation: which inflammatory cell type is more important?

: A recent review in Allergy, Asthma, and Clinical Immunology suggested that eosinophils play a minor role, if any, in the inflammatory spectrum of asthma and allergic inflammation. The article that dealt with mast cells suggested that the presence of these important cells within the smooth muscle layer in asthmatic airways renders this cell type primal in asthma and an obvious and important target for therapy. This article proposes that in a complex inflammatory milieu characterizing the complex syndromes we call asthma, no single cell phenotype is responsible for the condition and thus should be a sole target for therapeutic strategies. Our reductionist approach to research in asthma and related conditions has provided us with convincing evidence for multiple roles that immune, inflammatory, and structural cell types can play in complex diseases. The next stage in understanding and ameliorating these complex conditions is to move away from the simplistic notion of one cell type being more important than another. Instead, what is needed is to acquire knowledge of intricate and exquisite biological systems that regulate such conditions in both health and disease involving various cell types, mediators, pharmacologically active products, their multifaceted capacities, and their socio-biological networking.

Essential role of phosphoinositide 3-kinase gamma in eosinophil chemotaxis within acute pulmonary inflammation

We and others have established an important role for phosphoinositide-3 kinase gamma (PI3Kgamma) in the chemotactic responses of macrophages and neutrophils. The involvement of this lipid kinase in allergic inflammatory responses is, however, yet to be fully determined. Here we compare wild-type (WT) and PI3Kgamma(-/-) (KO) mice within a model of ovalbumin (OVA) -specific pulmonary inflammation. Upon OVA aerosol challenge, cell influx into the bronchoalveolar lavage (BAL) fluid consisted of neutrophils, macrophages and, more significantly, eosinophils - which are key effector cells in allergic inflammation. Each population was reduced by up to 80% in KO mice, demonstrating a role for PI3Kgamma in cell infiltration into the airways. The mechanism of reduced eosinophilia was analysed within both development and effector stages of the immune response. Comparable levels of OVA-specific T-cell proliferation and immunoglobulin production were established in both strains. Furthermore, no significant differences between WT and KO chemokine production were observed. Having identified the critical point of PI3Kgamma involvement, KO eosinophil chemotactic dysfunction was confirmed in vitro. These data are the first to demonstrate the vital role of PI3Kgamma in acute allergic inflammation. The profound dependency of eosinophils on PI3Kgamma for pulmonary influx identifies this lipid kinase as an attractive target for the pharmacological intervention of asthma.

Mucosal remodeling in chronic rhinosinusitis

BACKGROUND

Despite pathophysiologic similarities, mucosal remodeling is well described in asthma but not chronic rhinosinusitis (CRS).

OBJECTIVE

This study attempts to identify mucosal remodeling in CRS and correlate it with clinical information.

METHODS

Charts and histopathology from 53 CRS patients who underwent functional endoscopic sinus surgery were reviewed. Clinical data and basement membrane (BM) thickness were recorded. BM thickness was graded as 0 (no thickening), 1 (mild thickening), 2 (moderate thickening), or 3 (marked thickening). Control mucosae from ten patients without CRS were analyzed for comparison.

RESULTS

Duration of CRS symptoms positively correlated with BM thickness (p = 0.007). Also, patients with a markedly thickened BM (score of 3) had a significantly greater duration of CRS symptoms (120 months) compared to patients with a thinner BM (score < or =2) (33 months) (p = 0.010). Markedly thickened BM was associated with increased coincidence of asthma (p = 0.019) and aspirin sensitivity (p = 0.003). No correlation was found between BM thickness and preoperative Lund-MacKay score. There was no statistically significant difference between markedly thickened BM and thinner BM with respect to coincidence of polyps, course of preoperative systemic steroids, estimated blood loss at surgery, and number of prior surgeries.

CONCLUSION

Increased BM thickness is correlated with prolonged duration of symptoms and the coincidence of asthma. This may indicate paranasal sinus remodeling akin to that which occurs in the bronchioles of persistent asthmatic sufferers.

The role of eosinophils in airway tissue remodelling in asthma

There is an increasing evidence that airway structural change (termed remodelling) is associated with the severity and chronicity of asthma. Recent studies support an important role for eosinophils in the remodelling process. In particular eosinophil depletion studies have demonstrated that several aspects of remodelling are attenuated. Eosinophils have been confirmed as an important source of TGF-beta(1) as well as other important cytokines that can lead to the direct activation of epithelium and mesenchymal cells that are considered to drive airway remodelling. The current studies that support a role for eosinophils in airway remodelling are reviewed in article.

Divergent immune responses to house dust mite lead to distinct structural-functional phenotypes

Asthma is a chronic airway inflammatory disease that encompasses three cardinal processes: T helper (Th) cell type 2 (Th2)-polarized inflammation, bronchial hyperreactivity, and airway wall remodeling. However, the link between the immune-inflammatory phenotype and the structural-functional phenotype remains to be fully defined. The objective of these studies was to evaluate the relationship between the immunologic nature of chronic airway inflammation and the development of abnormal airway structure and function in a mouse model of chronic asthma. Using IL-4-competent and IL-4-deficient mice, we created divergent immune-inflammatory responses to chronic aeroallergen challenge. Immune-inflammatory, structural, and physiological parameters of chronic allergic airway disease were evaluated in both strains of mice. Although both strains developed airway inflammation, the profiles of the immune-inflammatory responses were markedly different: IL-4-competent mice elicited a Th2-polarized response and IL-4-deficient mice developed a Th1-polarized response. Importantly, this chronic Th1-polarized immune response was not associated with airway remodeling or bronchial hyperresponsiveness. Transient reconstitution of IL-4 in IL-4-deficient mice via an airway gene transfer approach led to partial Th2 repolarization and increased bronchial hyperresponsiveness, along with full reconstitution of airway remodeling. These data show that distinct structural-functional phenotypes associated with chronic airway inflammation are strictly dependent on the nature of the immune-inflammatory response.

Signal peptide of eosinophil cationic protein upregulates transforming growth factor-alpha expression in human cells

Eosinophil cationic protein (ECP) is a major component of eosinophil granule protein that is used as a clinical bio-marker for asthma and allergic inflammatory diseases. Previously, it has been reported that the signal peptide of human ECP (ECPsp) inhibits the cell growth of Escherichia coli (E. coli) and Pichia pastoris (P. pastoris), but not mammalian A431 cells. The inhibitory effect is due to the lack of human signal peptide peptidase (hSPP), a protease located on the endoplasmic reticulum (ER) membrane, in the lower organisms. In this study, we show that the epidermal growth factor receptor (EGFR) is upregulated by the exogenous ECPsp-eGFP as a result of the increased expression of the transforming growth factor-alpha (TGF-alpha) at both transcriptional and translational levels in A431 and HL-60 clone 15 cell lines. Furthermore, the N-terminus of ECPsp fragment generated by the cleavage of hSPP (ECPspM1-G17) gives rise to over threefold increase of TGF-alpha protein expression, whereas another ECPsp fragment (ECPspL18-A27) and the hSPP-resistant ECPsp (ECPspG17L) do not show similar effect. Our results indicate that the ECPspM1-G17 plays a crucial role in the upregulation of TGF-alpha, suggesting that the ECPsp not only directs the secretion of mature ECP, but also involves in the autocrine system.

Innate immune mucin production via epithelial cell surface signaling: relationship to allergic disease

PURPOSE OF REVIEW

Airway epithelial surface signaling is provided by epidermal growth factor receptor (EGFR) phosphorylation, resulting in innate immune responses. Here the focus is the EGFR cascades leading to immune mucin responses. The review is timely because recent discoveries implicate these pathways in multiple innate immune defenses in addition to mucin production.

RECENT FINDINGS

EGFR activation causes mucin production and inhibition prevents mucin production by multiple stimuli. The receptors and their epithelial-bound proligands are examined. Proteases cleave and release soluble ligand, which then activates EGFR. A surface metalloprotease, tumor necrosis factor alpha-converting enzyme (TACE), modulates proligand release (and thus EGFR activation). TACE is activated by reactive oxygen species, which can be produced by a novel molecule, dual oxidase-1, which provides reactive oxygen species for TACE cleavage. Upstream of dual oxidase-1 are epithelial receptors that receive messages from inhaled irritants and stimulate the dual oxidase-1-TACE-ligand-EGFR cascade.

SUMMARY

The EGFR surface signaling pathways are reviewed, with the focus on mucin production, involving human airway epithelial cultures and animal studies, including relevant studies of asthma in humans. Future studies may broaden the innate defenses and utilize these surface signaling pathways in various epithelia, with a variety of pathophysiologic stimuli, with the ultimate aim of examining these pathways in inflammatory diseases.

Eosinophilic granulocytes and damage-associated molecular pattern molecules (DAMPs): role in the inflammatory response within tumors

The development of a tumor over many years typically leads to reciprocal alternations in the host and the tumor, enabling tumor growth paradoxically in the setting of substantial necrosis and inflammation. When evaluating a tumor, it is important to assess 3 elements: (1) the quantity and quality of tumor-associated leukocytes, (2) their state of activation, and (3) tumor microenvironment. Peripheral blood eosinophilia and tumor-associated tissue eosinophilia are frequently associated with some tumor types and also found after immunotherapy with IL-2, IL-4, granulocyte-macrophage colony-stimulating factor, and antibody to CTLA-4. Within several tumor types including gastrointestinal tumors, tumor-associated tissue eosinophilia is associated with a significantly better prognosis. The converse is true in other tumor types such as differentiated oral squamous cell carcinoma. On the basis of the emergent data, tumor-associated eosinophils have at least 2 dominant nonoverlapping activities: (1) destructive effector functions potentially limiting tumor growth as well as causing recruitment and activation of other leukocytes, (2) immunoregulative and remodeling activities which suppress immune response and promote tumor proliferation. The mechanism by which eosinophils in particular are recruited into tumor tissue is largely unknown. Candidates for causing eosinophil chemotaxis into tumor tissue are the released damage-associated molecular pattern molecules (DAMPs) including the nuclear protein high mobility group box 1. High mobility group box 1 is released upon necrotic cell death and secreted by many cells, particularly during periods of nutrient, hypoxic, or oxidant stress. This overview on eosinophil biology in the context of cancer and necrosis, introduces intriguing and novel strategies targeting eosinophils to enable more effective biologic therapy for cancer patients.

Regulation of mucin expression: mechanistic aspects and implications for cancer and inflammatory diseases

Mucins are large multifunctional glycoproteins whose primary functions are to protect and lubricate the surfaces of epithelial tissues lining ducts and lumens within the human body. Several lines of evidence also support the involvement of mucins in more complex biological processes such as epithelial cell renewal and differentiation, cell signaling, and cell adhesion. Recent studies have uncovered the role of select mucins in the pathogenesis of cancer, underscoring the importance of a detailed knowledge about mucin biology. Under normal physiological conditions, the production of mucins is optimally maintained by a host of elaborate and coordinated regulatory mechanisms, thereby affording a well-defined pattern of tissue-, time-, and developmental state-specific distribution. However, mucin homeostasis may be disrupted by the action of environmental and/or intrinsic factors that affect cellular integrity. This results in an altered cell behavior that often culminates into a variety of pathological conditions. Deregulated mucin production has indeed been associated with numerous types of cancers and inflammatory disorders. It is, therefore, crucial to comprehend the underlying basis of molecular mechanisms controlling mucin production in order to design and implement adequate therapeutic strategies for combating these diseases. Herein, we discuss some physiologically relevant regulatory aspects of mucin production, with a particular emphasis on aberrations that pertain to pathological situations. Our views of the achievements, the conceptual and technical limitations, as well as the future challenges associated with studies of mucin regulation are exposed.

Intragranular vesiculotubular compartments are involved in piecemeal degranulation by activated human eosinophils

Eosinophils, leukocytes involved in allergic, inflammatory and immunoregulatory responses, have a distinct capacity to rapidly secrete preformed granule-stored proteins through piecemeal degranulation (PMD), a secretion process based on vesicular transport of proteins from within granules for extracellular release. Eosinophil-specific granules contain cytokines and cationic proteins, such as major basic protein (MBP). We evaluated structural mechanisms responsible for mobilizing proteins from within eosinophil granules. Human eosinophils stimulated for 30-60 min with eotaxin, regulated on activation, normal, T-cell expressed and secreted (RANTES) or platelet activating factor exhibited ultrastructural features of PMD (e.g. losses of granule contents) and extensive vesiculotubular networks within emptying granules. Brefeldin A inhibited granule emptying and collapsed intragranular vesiculotubular networks. By immunonanogold ultrastructural labelings, CD63, a tetraspanin membrane protein, was localized within granules and on vesicles outside of granules, and mobilization of MBP into vesicles within and extending from granules was demonstrated. Electron tomography with three dimension reconstructions revealed granule internal membranes to constitute an elaborate tubular network able to sequester and relocate granule products upon stimulation. We provide new insights into PMD and identify eosinophil specific granules as organelles whose internal tubulovesicular networks are important for the capacity of eosinophils to secrete, by vesicular transport, their content of preformed and granule-stored cytokines and cationic proteins.

Human peripheral blood eosinophils induce angiogenesis

Eosinophils play a crucial role in allergic reactions and asthma. They are also involved in responses against parasites, in autoimmune and neoplastic diseases, and in fibroses. There is increasing evidence that angiogenesis plays an important role in these processes. Since eosinophils are known to produce angiogenic mediators, we have hypothesized a direct contribution of these cells to angiogenesis. The effect of human peripheral blood eosinophil sonicates on rat aortic endothelial cell proliferation (in vitro), rat aorta sprouting (ex vivo) and angiogenesis in the chick embryo chorioallantoic membrane (in vivo) have been investigated. To determine whether eosinophil-derived vascular endothelial growth factor influences the eosinophil pro-angiogenic activity, eosinophil sonicates were incubated with anti-vascular endothelial growth factor antibodies and then added to the chorioallantoic membrane. Vascular endothelial growth factor mRNA expression and vascular endothelial growth factor receptor density on the endothelial cells were also evaluated. Eosinophils were found to enhance endothelial cell proliferation and to induce a strong angiogenic response both in the aorta rings and in the chorioallantoic membrane assays. Pre-incubation of eosinophil sonicates with anti-vascular endothelial growth factor antibodies partially reduced the angiogenic response of these cells in the chorioallantoic membrane. Eosinophils also increased vascular endothelial growth factor mRNA production on endothelial cells. Eosinophils are able to induce angiogenesis and this effect is partially mediated by their pre-formed vascular endothelial growth factor. This strongly suggests an important role of eosinophils in angiogenesis-associated diseases such as asthma.

Evaluation of eosinophilia in hospitalized preterm infants

OBJECTIVE

To characterize changes in eosinophil counts over time, and to draw comparisons across four gestational age groups with respect to the incidence of, and clinical conditions associated with eosinophilia over the first months of life in a single neonatal intensive care unit (NICU).

STUDY DESIGN

Weekly complete blood counts (CBCs) were collected from all NICU patients. Eosinophilia was classified as mild, moderate, or severe. Changes in eosinophil counts were examined over time, the incidence of eosinophilia was determined by gestational age group, and clinical correlations sought.

RESULTS

Eosinophil data from 1652 CBCs were analyzed from 332 infants. Eosinophilia occurred in 148 infants (45%) during their hospitalization. The prevalence, severity, and timing of eosinophilia varied by gestational age, infection, and red blood cell transfusions.

CONCLUSIONS

The incidence and severity of eosinophilia increased with immaturity, and was temporally associated with infection, necrotizing enterocolitis, and packed red blood cell transfusion.

Anti-interleukin-5 therapy for asthma and hypereosinophilic syndrome

Interleukin 5 (IL-5) is a key cytokine in the regulation of eosinophilia and eosinophil activation in humans. Monoclonal antibodies to anti-IL-5 have become available for use in clinical studies in humans. This article discusses the rationale for the use of anti-IL-5 therapy in asthma and hypereosinophilic syndrome and summarizes the available clinical data on the use of anti-IL-5 to treat these disorders.

Roles of epidermal growth factor receptor activation in epithelial cell repair and mucin production in airway epithelium

The epithelial cells lining the airways serve protective functions. The "barrier function" of the epithelium protects the individual from damage by inhaled irritants. The epithelium produces mucins which become hydrated and form a viscoelastic gel which spreads over the epithelial surface. In healthy individuals inhaled foreign materials become entrapped in the mucus and are cleared by mucociliary transport and by coughing. In many chronic inflammatory airway diseases, however, excessive mucus is produced and is inadequately cleared, leading to mucous obstruction and infection. At present there is no specific treatment for hypersecretion. However, the discovery that an epidermal growth factor receptor (EGFR) cascade is involved in mucin production by a wide variety of stimuli suggests that blockade may provide specific treatment for hypersecretory diseases. EGFR pathways have also been implicated in the repair of damaged airway epithelium. The roles of EGFR in airway epithelial cell hypersecretion and epithelial damage and repair are reviewed and future potential treatments are suggested.

A role for eosinophils in airway remodelling in asthma

Over the years, the role of the eosinophil in asthma and allergic processes has been disputed. Recent human experiments using a humanised monoclonal antibody to interleukin-5 (IL-5), and animal studies involving specific IL-5 gene deletion, indicates that eosinophils might control downstream repair and remodelling processes. Eosinophils are a rich source of fibrogenic factors, particularly transforming growth factor-beta (TGF-beta), the latent form of which is activated by epithelial-cell expression of the intergin alpha(v)beta(6). The emerging role for the eosinophil in airway remodelling might be important in future anti-asthma strategies. However, more effective eosinophil-depleting agents than anti-IL-5 are required before the definitive role of this cell type in asthma airway pathophysiology can be established.

Cytokine-regulated accumulation of eosinophils in inflammatory disease

The role of cytokines in the accumulation of eosinophil granulocytes in inflamed tissue has been studied extensively during recent years, and these molecules have been found to participate throughout the whole process of eosinophil recruitment. Haematopoietic cytokines such as IL-3, IL-5 and GM-CSF stimulate the proliferation and differentiation of eosinophils in the bone marrow, and the release of mature eosinophils from the bone marrow into the blood is probably promoted by IL-5. Priming of eosinophils in the blood following, for example, allergen challenge is performed mainly by IL-3, IL-5 and GM-CSF. An important step in the extravasation of eosinophils is their adhesion to the vascular endothelium. Adhesion molecules are upregulated by, e.g. IL-1, IL-4, TNF-alpha and IFN-gamma and the same cytokines may also increase the affinity of adhesion molecules both on eosinophils and endothelial cells. Finally, a number of cytokines have been shown to act as eosinophil chemotactic factors, attracting the cells to the inflammatory focus in the tissue. Some of the most important eosinophil chemoattractant cytokines are IL-5, IL-8, RANTES, eotaxin, eotaxin-2, eotaxin-3, MCP-3, MCP-4 and TNF-alpha. Th2 cells, mast cells and epithelial cells are important sources of proinflammatory cytokines, but in recent years, the eosinophils have also been recognized as cytokine-producing and thereby immunoregulatory cells. The aim of this paper is to review the role of cytokines in the process of eosinophil recruitment in asthma, allergy and ulcerative colitis.

Anti-IL-5 treatment reduces deposition of ECM proteins in the bronchial subepithelial basement membrane of mild atopic asthmatics

Eosinophil-derived TGF-beta has been implicated in remodeling events in asthma. We hypothesized that reduction of bronchial mucosal eosinophils with anti-IL-5 would reduce markers of airway remodeling. Bronchial biopsies were obtained before and after three infusions of a humanized, anti-IL-5 monoclonal antibody (mepolizumab) in 24 atopic asthmatics in a randomized, double-blind, placebo-controlled study. The thickness and density of tenascin, lumican, and procollagen III in the reticular basement membrane (RBM) were quantified immunohistochemically by confocal microscopy. Expression of TGF-beta1 mRNA by airway eosinophils was assessed by in situ hybridization, and TGF-beta1 protein was measured in bronchoalveolar lavage (BAL) fluid by ELISA. At baseline, airway eosinophil infiltration and ECM protein deposition was increased in the RBM of asthmatics compared with nonasthmatic controls. Treating asthmatics with anti-IL-5 antibody, which specifically decreased airway eosinophil numbers, significantly reduced the expression of tenascin, lumican, and procollagen III in the bronchial mucosal RBM when compared with placebo. In addition, anti-IL-5 treatment was associated with a significant reduction in the numbers and percentage of airway eosinophils expressing mRNA for TGF-beta1 and the concentration of TGF-beta1 in BAL fluid. Therefore eosinophils may contribute to tissue remodeling processes in asthma by regulating the deposition of ECM proteins.

Glucocorticoid regulation of human eosinophil gene expression

Molecular analysis of steroid-regulated gene expression in freshly isolated human eosinophils is difficult due to the inherent high rate of spontaneous apoptosis and elevated levels of endogenous ribonucleases. To circumvent these limitations, we determined if the human eosinophilic cell line EoL-1 could serve as an in vitro model of glucocorticoid signaling. We found by optimizing growth conditions in low serum-containing media that dexamethasone (Dex) treatment of EoL-1 cells induced an apoptotic pathway that was inhibited by interleukin-5 (IL-5). Moreover, gene expression profiling using RNA from untreated EoL-1 cells and from freshly isolated human eosinophils identified 380 commonly expressed genes, including the eosinophil markers granule major basic protein, prostaglandin-endoperoxide synthase 1 and arachidonate 15-lipoxygenase. Expression profiling was performed using EoL-1 cells that had been treated with dexamethasone for 0, 4, 12, 24 and 48h identifying 162 genes as differentially expressed. Two of the most highly upregulated genes based on expression profiling were the transcription factor Ets-2 and the MHC Class II genes (Q, R, and P). Expression of these genes in EoL-1 cells was shown to be dexamethasone-induced at the RNA and protein levels which is consistent with the known function of Ets-2 in controlling cell cycle progression and the role of MHC Class II antigens in mediating eosinophil functions.

Human eosinophils produce neurotrophins and secrete nerve growth factor on immunologic stimuli

Neurotrophins, such as nerve growth factor (NGF) and neurotrophin-3 (NT-3), are essential for development, function, and survival of peripheral sympathetic and sensory neurons. Most eosinophilic leukocytes in the human body are localized in mucosal tissues; however, the roles of eosinophils in human diseases are not fully understood. We found that human eosinophils constitutively express messenger RNA for NGF and NT-3, synthesize and store these proteins intracellularly, and continuously replenish them. Incubation of eosinophils with a transcription inhibitor, actinomycin D, for 8 hours completely depletes intracellular NGF and NT-3. New synthesis of NGF is enhanced by Fc-receptor-mediated stimuli, such as immunoglobulin (Ig)A and IgG immune complexes; in contrast, production of NT-3 is not affected by these stimuli. Notably, supernatants of eosinophils stimulated with IgA immune complex and interleukin 5 promote neurite extension of the PC-12 pheochromocytoma cell line; this effect is abolished by pretreatment of the supernatants with anti-NGF-neutralizing antibody. By enzyme-linked immunosorbent assay, substantial amounts of NGF protein are also detected in the supernatants of stimulated eosinophils. Furthermore, in patients with seasonal allergic rhinitis, the concentrations of NGF in nasal secretions correlate with the magnitudes of eosinophilic inflammation in the airway, suggesting a potential clinical implication of eosinophil NGF. Our observations propose a new pathologic mechanism by which eosinophils may contribute to enhanced neurologic responses in patients with allergic diseases and other eosinophilic disorders. Alternatively, eosinophils may play important roles in maintenance and restoration of homeostatic functions of mucosal tissues through the pleitropic activities of NGF.

Human eosinophils induce mucin production in airway epithelial cells via epidermal growth factor receptor activation

Eosinophil recruitment and mucus hypersecretion are characteristic of asthmatic airway inflammation, but eosinophils have not been shown to induce mucin production. Because an epidermal growth factor receptor (EGFR) cascade induces MUC5AC mucin in airways, and because EGFR is up-regulated in asthmatic airways, we examined the effect of eosinophils on MUC5AC mucin production in NCI-H292 cells (a human airway epithelial cell line that produces mucins). Eosinophils were isolated from the peripheral blood of allergic patients, and their effects on MUC5AC mucin gene and protein synthesis were assessed using in situ hybridization and ELISAs. When IL-3 plus GM-CSF or IL-3 plus IL-5 were added to eosinophils cultured with NCI-H292 cells, MUC5AC mucin production increased; eosinophils or cytokines alone had no effect. Eosinophil supernatant obtained by culturing eosinophils with IL-3 plus GM-CSF or IL-3 plus IL-5 also increased MUC5AC synthesis in NCI-H292 cells, an effect that was prevented by selective EGFR inhibitors (AG1478, BIBX1522). Supernatant of activated eosinophils induced EGFR phosphorylation in NCI-H292 cells. Supernatant of activated eosinophils contained increased concentrations of TGF-alpha protein (an EGFR ligand) and induced up-regulation of TGF-alpha expression and release in NCI-H292 cells. A blocking Ab to TGF-alpha reduced activated eosinophil-induced MUC5AC synthesis in NCI-H292 cells. These results show that activated eosinophils induce mucin synthesis in human airway epithelial cells via EGFR activation, and they implicate TGF-alpha produced by eosinophils and epithelial cells in the EGFR activation that results in mucin production in human airway epithelium.

Pulmonary T cells and eosinophils: coconspirators or independent triggers of allergic respiratory pathology?

Etiologic discussions of allergic respiratory pathology frequently engender rabid constituencies of pro-T cell or proeosinophil disciples, each claiming, often with religious fervor, the importance of their leukocyte. However, increasing evidence suggests that the exclusionary rhetoric from either camp is inadequate to explain many of the pathologic changes occurring in the lung. Data from both asthmatic patient and mouse models of allergic respiratory inflammation suggest that, in addition to cell-autonomous activities, T-cell and eosinophil interactions may be critical to the onset and progression of pulmonary pathology. These studies also suggest that T-lymphocyte subpopulations and eosinophils communicate by means of both direct cell-cell interactions and through the secretion of inflammatory signals. Collectively, the data support an expanded view of T-cell and eosinophil activities in the lung, including both immunoregulative activities and downstream effector functions impinging directly on lung function.