Eosinophils: biological properties and role in health and disease

Anti-inflammatory effect of wogonin on allergic responses in ovalbumin-induced allergic rhinitis in the mouse

Background

Wogonin is commonly used for the treatment of allergic diseases. However, neither its precise effect in preventing allergic rhinitis (AR) nor its mechanism of action are known.

Objectives

In this study, the effect of wogonin on allergic responses in ovalbumin (OVA) induced AR was investigated in mice.

Methods

BALB/c mice were sensitized with intraperitoneal (i.p.) OVA and then challenged intranasally with OVA. Wogonin (10 and 30 mg/kg) was given to the treatment groups, and the effect of wogonin on the release of allergic inflammatory mediators, specifically OVA-specific immunoglobulin E (IgE) and inflammatory cytokines, was explored. Eosinophil infiltration and the levels of interleukin (IL) 5 and IL-13 were measured by immunohistochemistry.

Results

In mice with AR, wogonin decreased OVA-specific IgE levels in serum, and the levels of the cytokines IL-4, IL-5, IL-13, eotaxin, and RANTES in nasal lavage fluid. Serum levels of IL-4, IL-5, and IL-13 were lower in both groups of wogonin-pretreated mice than in the OVA group. A reduction in eosinophil infiltration of the nasal mucosa and inhibition of the expression of IL-5 and IL-13 were also noted in the treated groups.

Conclusion

Wogonin induced antiallergic effects in a murine model of AR by decreasing the infiltration of eosinophils and levels of T-helper type 2 cytokines. Thus, wogonin merits consideration as a therapeutic agent for treating AR.

Important and specific role for basophils in acute allergic reactions

IgE‐mediated allergic reactions involve the activation of effector cells, predominantly through the high‐affinity IgE receptor (FcεRI) on mast cells and basophils. Although the mast cell is considered the major effector cell during acute allergic reactions, more recent studies indicate a potentially important and specific role for basophils and their migration which occurs rapidly upon allergen challenge in humans undergoing anaphylaxis. We review the evidence for a role of basophils in contributing to clinical symptoms of anaphylaxis and discuss the possibility that basophil trafficking during anaphylaxis might be a pathogenic (to target organs) or protective (preventing degranulation in circulation) response. Finally, we examine the potential role of basophils in asthma exacerbations. Understanding the factors that regulate basophil trafficking and activation might lead to new diagnostic and therapeutic strategies in anaphylaxis and asthma.

Benralizumab in the treatment of severe asthma: design, development and potential place in therapy

Asthma is a widespread and heterogeneous inflammatory disease of the airways, which is characterized by several different phenotypes and endotypes. In particular, eosinophilic airway inflammation is a common pathologic trait of both allergic and nonallergic asthma. The key cytokine responsible for maturation, activation, recruitment, and survival of eosinophils is interleukin (IL)-5, which is mainly produced by T helper 2 (Th2) lymphocytes and group 2 innate lymphoid cells. Therefore, for uncontrolled patients with severe eosinophilic asthma, who are not fully responsive to corticosteroids, IL-5 represents a very important molecular target for add-on biological therapies. Among these new treatments, anti-IL-5 monoclonal antibodies such as mepolizumab and reslizumab have been developed and clinically evaluated. Furthermore, benralizumab is currently the only available biologic drug that specifically binds to the IL-5 receptor, thus preventing the interaction with its ligand and the consequent pro-inflammatory effects. The effectiveness of benralizumab in improving severe eosinophilic asthma has been well-documented by many randomized controlled trials.

Integrin αM activation and upregulation on esophageal eosinophils and periostin-mediated eosinophil survival in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an increasingly recognized allergic disease associated with dysphagia and esophageal fibrosis. We aimed to determine expression patterns of specific eosinophil integrins that promote eosinophilic infiltration of the esophageal epithelium, and to determine how key EoE-related cytokines influence eosinophil activation and survival. Esophageal and peripheral eosinophils were isolated from 20 adult subjects with EoE for immunophenotyping and integrin profiling using multicolor flow cytometry and immunohistochemistry. Expression signatures of eosinophil integrins were further assessed by immunohistochemistry using serial sections of esophageal biopsy specimens. Purified eosinophils were used to assess the effect of EoE-relevant cytokines and recombinant periostin on expression of known eosinophil integrins and eosinophil survival and activation. We found that resting eosinophils express high levels of the β2-pairing integrins αL and αM, and lower levels of α4, α6 and α4β7. The migration of peripheral eosinophils to the esophagus is characterized by the specific induction of αM, and a significant increase in the proportion of αM in high-activity conformation. Periostin, a secreted extracellular matrix protein that is significantly overexpressed in EoE, enhances eosinophil survival, and this effect is mediated by αM interaction. Integrin αM is a specific marker of activated tissue eosinophils in EoE, and promotes eosinophil survival through interactions with periostin. The ability of αMβ2 to mediate eosinophil tissue residency via periostin represents a key mechanism for disease development and a potential therapeutic target in EoE.

Mast cells, basophils and eosinophils: From allergy to cancer

Basophils, eosinophils and mast cells were first recognized by Paul Ehrlich in the late 19th century. These cells have common, but non-redundant roles, in the pathogenesis of allergic diseases and in the protection against parasites. Nevertheless, in virtue of their shared-adeptness to produce a huge variety of immunological mediators and express membrane-bound receptors, they are able to interact with immune and non-immune components of the tissue microenvironment, contributing to the regulation of tissue homeostasis and immune response while participating to further deregulation of tissues transforming into neoplasia.

Eosinophils from Physiology to Disease: A Comprehensive Review

Despite being the second least represented granulocyte subpopulation in the circulating blood, eosinophils are receiving a growing interest from the scientific community, due to their complex pathophysiological role in a broad range of local and systemic inflammatory diseases as well as in cancer and thrombosis. Eosinophils are crucial for the control of parasitic infections, but increasing evidence suggests that they are also involved in vital defensive tasks against bacterial and viral pathogens including HIV. On the other side of the coin, eosinophil potential to provide a strong defensive response against invading microbes through the release of a large array of compounds can prove toxic to the host tissues and dysregulate haemostasis. Increasing knowledge of eosinophil biological behaviour is leading to major changes in established paradigms for the classification and diagnosis of several allergic and autoimmune diseases and has paved the way to a "golden age" of eosinophil-targeted agents. In this review, we provide a comprehensive update on the pathophysiological role of eosinophils in host defence, inflammation, and cancer and discuss potential clinical implications in light of recent therapeutic advances.

Quail egg homogenate alleviates food allergy induced eosinophilic esophagitis like disease through modulating PAR-2 transduction pathway in peanut sensitized mice

The present pharmacotherapy for eosinophilic esophagitis (EoE) fundamentally depend on inhaled corticosteroids. Despite the fact that oral intake of topical steroids can be successful in restricting EoE-related inflammation, there are concerns with respect to the long term utilization of steroids, especially in kids. In the current research, we assess the effect of quail egg, which is reportedly a known serine protease inhibitor, on symptomatology and immune responses in a peanut-sensitized mouse model of food allergy induced EoE. Daily oral treatment with quail egg attenuated mice symptomatology and immune response. Treatment with quail egg inhibited antigen-prompted increments in mouse tryptase and eosinophil cationic protein (ECP) in serum and eosinophil in inflamed tissues like oesophagus, lung, and digestive system. Quail egg treatment resulted in decreased antibody specific IgE and IgG1 and a variety of inflammatory genes that were abnormally expressed in EoE. Other effects included increased IL-10, decreased PAR-2 activation and NF-kB p65 in inflamed tissues. Our results suggest that quail egg treatment may have therapeutic potential in attenuating the symptoms of food allergy induced EoE like disease through regulating PAR-2 downstream pathway by blocking the activation of the transcription factor NF-kB p65 activity.

Role of eosinophils in airway inflammation of chronic obstructive pulmonary disease

COPD is a significant cause of morbidity and mortality. In some patients with COPD, eosinophils contribute to inflammation that promotes airway obstruction; approximately a third of stable COPD patients have evidence of eosinophilic inflammation. Although the eosinophil threshold associated with clinical relevance in patients with COPD is currently subject to debate, eosinophil counts hold potential as biomarkers to guide therapy. In particular, eosinophil counts may be useful in assessing which patients may benefit from inhaled corticosteroid therapy, particularly regarding exacerbation prevention. In addition, several therapies targeting eosinophilic inflammation are available or in development, including monoclonal antibodies targeting the IL5 ligand, the IL5 receptor, IL4, and IL13. The goal of this review was to describe the biologic characteristics of eosinophils, their role in COPD during exacerbations and stable disease, and their use as biomarkers to aid treatment decisions. We also propose an algorithm for inhaled corticosteroid use, taking into consideration eosinophil counts and pneumonia history, and emerging eosinophil-targeted therapies in COPD.

Peripheral Eosinophilia and Clinico-radiological Characteristics among Health Screening Program Recipients

Background

Eosinophilia is well recognized in specific conditions. The objective of the present study was to determine clinico-radiologic characteristics of eosinophilia and changes in prevalence over 10 years in recipients of private health screening program at a tertiary hospital in Korea.

Methods

Data of private health screening program recipients at the health promotion center of Chung-Ang University Hospital from 2004 to 2013 were collected. Health-related questionnaires and laboratory findings of private health screening program with possible relation with eosinophilia were reviewed. Results of enzyme-linked immunosorbent assay (ELISA) for parasite, chest computed tomography, and pulmonary function test were also reviewed.

Results

The cumulative prevalence of eosinophilia was 4.0% (1,963 of 48,928). Prevalence of eosinophilia showed a decreased trend from 2004 to 2013. Most cases (96.6%) had mild degree of eosinophilia. Eosinophilic subjects were older and male-predominant. They showed lower levels of forced expiratory volume in 1 second (FEV₁%), forced vital capacity (FVC%), and FEV₁/FVC than those without eosinophilia. Eosinophilic subjects showed higher positive rate for common parasite in ELISA than those without eosinophilia. On radiologic findings, consolidation and ground glass opacities were positively associated with the degree of eosinophilia. When eosinophil was classified based on severity, statistically significant correlation between the severity of eosinophil and radiologic abnormalities was found.

Conclusion

Eosinophilia is uncommon in healthy population. It usually occurs at a mild degree. Eosinophilic patients have more radiologic abnormalities compared to those without eosinophilia. Such radiologic abnormalities are associated with the severity of eosinophilia.

Oxidative stress and cellular pathways of asthma and inflammation: Therapeutic strategies and pharmacological targets

Asthma is a complex inflammatory disease characterized by airway inflammation and hyperresponsiveness. The mechanisms associated with the development and progression of asthma have been widely studied in multiple populations and animal models, and these have revealed involvement of various cell types and activation of intracellular signaling pathways that result in activation of inflammatory genes. Significant contributions of Toll-like-receptors (TLRs) and transcription factors such as NF-кB, have been reported as major contributors to inflammatory pathways. These have also recently been associated with mechanisms of oxidative biology. This is of important clinical significance as the observed inefficacy of current available treatments for severe asthma is widely attributed to oxidative stress. Therefore, targeting oxidizing molecules in conjunction with inflammatory mediators and transcription factors may present a novel therapeutic strategy for asthma. In this review, we summarize TLRs and NF-кB pathways in the context of exacerbation of asthma pathogenesis and oxidative biology, and we discuss the potential use of polyphenolic flavonoid compounds, known to target these pathways and possess antioxidant activity, as potential therapeutic agents for asthma.

Different durations of whole raw soybean supplementation during the prepartum period: Measures of cellular immune function in transition cows

The objective of this study was to evaluate different durations of whole raw soybean (WS) supplementation (diet rich in n-6 fatty acid) during the prepartum period on cellular immune function of dairy cows in the transition period and early lactation. Thirty-one Holstein cows were used in a completely randomized design and assigned to 4 experimental groups (G) [G90, G60, G30, and G0 (control)] supplemented with a diet containing 12% of WS from 90, 60, 30 and 0 d relative to the calving date, respectively. Cows were dried off 60 d before the expected calving date. After parturition, all cows were fed a diet containing 12% of WS until 84 DIM. Blood samples were collected before the morning feeding (d -56 ± 2, -28 ± 2, -14 ± 2, -7 ± 2, at the day of partum, 7 ± 2, 14 ± 2, 28 ± 2, and 56 ± 2 relative to parturition). Cell phenotyping and phagocytosis assays were carried out using monoclonal antibodies and flow cytometry technique. Duration of WS supplementation linearly increased the percentage of blood CD3+ cells, as well as increased the percentage of blood CD8+ cells in the postpartum period, notably in G30, whereas the lowest values were observed in G0. Further, the duration of WS supplementation linearly increased the reactive oxygen species median fluorescence intensity of CH138+ cells after phagocytizing Staphylococcus aureus in the postpartum period. Longer periods of WS supplementation linearly increased phagocytosis median fluorescence intensity of CH138+ cells in the prepartum period of cows. Duration of WS supplementation linearly increased the percentage of blood CD14+ cells producing reactive oxygen species when stimulated either by Staph. aureus or Escherichia coli in the postpartum period. In conclusion, longer periods of WS supplementation during late lactation and the dry period (beginning on d 90 of the expected calving date) alter the leukocyte population and improve neutrophil immune response in the postpartum period with no detrimental effects on cow performance.

High-fat diet-induced obesity impairs insulin signaling in lungs of allergen-challenged mice: Improvement by resveratrol

Insulin resistance plays an important role in obesity-associated asthma exacerbations. Using a murine model of allergic airway inflammation, we evaluated the insulin signaling transmission in lungs of obese compared with lean mice. We further evaluated the effects of the polyphenol resveratrol in the pulmonary insulin signaling. In lean mice, insulin stimulation significantly increased phosphorylations of AKT, insulin receptor substrate 1 (IRS-1) and insulin receptor β (IRβ) in lung tissue and isolated bronchi (p < 0.05), which were impaired in obese group. Instead, obese mice displayed increased tyrosine nitrations of AKT, IRβ and IRS-1 (p < 0.05). Two-week therapy of obese mice with resveratrol (100 mg/kg/day) restored insulin-stimulated AKT, IRS-1 and IRβ phosphorylations, and simultaneously blunted the tyrosine nitration of these proteins. Additionally, the c-Jun N-terminal kinase (JNK) and inhibitor of NF-κB Kinase (IκK) phosphorylations were significantly increased in obese group, an effect normalized by resveratrol. In separate experiments, the inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (20 mg/kg/day, three weeks) mimicked the protective effects exerted by resveratrol in lungs of obese mice. Lungs of obese mice display nitrosative-associated impairment of insulin signaling, which is reversed by resveratrol. Polyphenols may be putative drugs to attenuate asthma exacerbations in obese individuals.

[A predictive bacterial infection score according to eosinophil level: An observational study]

INTRODUCTION

Several studies have shown that eosinopenia less than 0.04g/L is a marker of bacterial infection in the presence of unexplained inflammatory syndrome. The aim of our study was to test this hypothesis and to propose a predictive score for bacterial infection (score CIBLE, C reactive protein, bacterial infections, levels of leucocytes and eosinophils).

PATIENTS AND METHODS

This was a single-center observational study of patients admitted to an internal medicine department in the year 2015 and presenting with an inflammatory biological syndrome. Patients were divided into 2 groups: bacterial infections (group 1) and nonbacterial inflammatory diseases (group 2).

RESULTS

One hundred and ninety patients were included: 92 men (48.4 %) and 98 women (51.6 %). Mean age was 73.5±18.2 years [19-104]. Group 1 consisted of 124 patients (65.2 %) and group 2 of 66 patients (34.8 %). ROC analysis confirmed a cut-off level for eosinophils count at 0.04g/L as discriminant to predict bacterial infection. In a multivariate analysis, the eosinophil/neutrophil ratio, a history of COPD, the C reactive protein concentration, patient age and initial temperature were the most significant variables. They were used to build the CIBLE score. For a score higher than or equal to 87, the probability of a bacterial infection is at least 70 %.

CONCLUSION

The CIBLE score appears to be a relevant and inexpensive tool to establish a probability for bacterial infection.

Prevalence of persistent blood eosinophilia: relation to outcomes in patients with COPD

The impact of blood eosinophilia in chronic obstructive pulmonary disease (COPD) remains controversial.

To evaluate the prevalence and stability of a high level of blood eosinophils (≥300 cells·μL–1) and its relationship to outcomes, we determined blood eosinophils at baseline and over 2 years in 424 COPD patients (forced expiratory volume in 1 s (FEV1) 60% predicted) and 67 smokers without COPD from the CHAIN cohort, and in 308 COPD patients (FEV1 60% predicted) in the BODE cohort. We related eosinophil levels to exacerbations and survival using Cox hazard analysis.

In COPD patients, 15.8% in the CHAIN cohort and 12.3% in the BODE cohort had persistently elevated blood eosinophils at all three visits. A significant proportion (43.8%) of patients had counts that oscillated above and below the cut-off points, while the rest had persistent eosinophil levels <300 cells·μL–1. A similar eosinophil blood pattern was observed in controls. Exacerbation rates did not differ in patients with and without eosinophilia. All-cause mortality was lower in patients with high eosinophils compared with those with values <300 cells·μL–1 (15.8% versus 33.7%; p=0.026).

In patients with COPD, blood eosinophils ≥300 cells·μL–1 persisting over 2 years was not a risk factor for COPD exacerbations. High eosinophil count was associated with better survival.

Eosinophils: The unsung heroes in cancer?

Prolonged low-grade inflammation or smoldering inflammation is a hallmark of a cancer. Eosinophils are components of the immune microenvironment that modulates tumor initiation and progression. Although canonically associated with a detrimental role in allergic disorders, these cells can induce a protective immune response against helminthes, viral and bacterial pathogens. Eosinophils are a source of anti-tumorigenic (e.g., TNF-α, granzyme, cationic proteins, and IL-18) and protumorigenic molecules (e.g., pro-angiogenic factors) depending on the milieu. In several neoplasias (e.g., melanoma, gastric, colorectal, oral and prostate cancer) eosinophils play an anti-tumorigenic role, in others (e.g., Hodgkin's lymphoma, cervical carcinoma) have been linked to poor prognosis, whereas in yet others they are apparently innocent bystanders. These seemingly conflicting results suggest that the role of eosinophils and their mediators could be cancer-dependent. The microlocalization (e.g., peritumoral vs intratumoral) of eosinophils could be another important aspect in the initiation/progression of solid and hematological tumors. Increasing evidence in experimental models indicates that activation/recruitment of eosinophils could represent a new therapeutic strategy for certain tumors (e.g., melanoma). Many unanswered questions should be addressed before we understand whether eosinophils are an ally, adversary or neutral bystanders in different types of human cancers.

Severe eosinophilic asthma: from the pathogenic role of interleukin-5 to the therapeutic action of mepolizumab

Mepolizumab is an anti-interleukin-5 (IL-5) humanized monoclonal antibody that has been recently approved as an add-on biological treatment for severe eosinophilic asthma, by both the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Moreover, mepolizumab is also currently included within the step 5 of the Global Initiative for Asthma guidelines, as an add-on therapy for severe uncontrolled asthma. The relevant therapeutic benefits detectable in patients with refractory eosinophilic asthma receiving mepolizumab depend on the pivotal pathogenic role played by IL-5 in these subjects. Indeed, IL-5 is the key cytokine responsible for maturation, activation, proliferation, and survival of eosinophils. Therefore, IL-5 represents a strategic molecular target for anti-eosinophilic treatments. By selectively inhibiting the biological actions of IL-5, mepolizumab provides a valuable therapeutic option for patients with severe eosinophilic asthma, refractory to standard treatments including inhaled and even systemic corticosteroids. In particular, the very important advantages linked to the use of mepolizumab in these difficult-to-treat asthmatic individuals have been well documented by several different trials performed worldwide.

Propofol inhibits NF-κB activation to ameliorate airway inflammation in ovalbumin (OVA)-induced allergic asthma mice

Propofol, one of the most commonly used intravenous anesthetic agents, has been reported to have anti-inflammatory property. However, the anti-allergic inflammation effect of propofol and its underlying molecular mechanisms have not been elucidated. In the present study, we aim to investigate the roles of NF-kB activation in propofol anti-asthma effect on OVA-induced allergic airway inflammation in mice. In a standard experimental asthma model, Balb/c mice were sensitized with ovalbumin, treated with propofol (50,100,150mg/kg) or a vehicle control 1h before OVA challenge. Blood samples, bronchoalveolar lavage fluid (BALF) and lung tissues were harvested after measurement of airway hyperresponsiveness. Results revealed that propofol not only significantly inhibit airway hyperresponsiveness, but also inhibited the production of Th2 cytokines, NO, Ova-specific IgE and eotaxin. Histological studies indicated that propofol significantly attenuated OVA-induced inflammatory cell infiltration in the peribronchial areas and mucus hypersecretion. Meanwhile, our results indicated that propofol was found to inhibit NF-kB activation in OVA-Induced mice. Furthermore, propofol significantly reduced the TNF-α-induced NF-kB activation in A549 cells. In conclusion, our study suggested that propofol effectively reduced allergic airway inflammation by inhibiting NF-kB activation and could thus be used as a therapy for allergic asthma.

Blood eosinophilia as a marker of early and late treatment failure in severe acute exacerbations of COPD

BACKGROUND

Blood eosinophilia is frequently encountered in patients with AECOPD. However the impact of blood eosinophilia at admission in patients with AECOPD on outcome on the short and long term has not been extensively studied which was the objective of the present study.

METHODS

We used data of 207 exacerbations from a randomized clinical trial on antibiotic prescription based upon CRP-levels versus GOLD guided strategy and analyzed the impact of blood eosinophils (≥2% of total white cell count and eosinophil count ≥300 cell/microliter) on clinical outcome.

RESULTS

207 patients were included of whom 39 (18·8%) had eosinophilia ≥2%, 23 patients (11.1%) had blood eosinophil ≥300 cell/microliter. Eosinophilia was associated with shorter median length of stay in the eosinophilic groups(≥2% and ≥300 cell/microliter) compared to the non-eosinophilic groups. Early treatment failure was reduced in the both the eosinophilic groups (≥2% and ≥300 cell/microliter). Late treatment failure (day 11-30) did not differ between the groups. Relapse, was more frequent the eosinophilic groups (≥2% and ≥300 cell/microliter), however in the latter group this did not reach statistical significance. Eosinophilia ≥2% was a risk factor for having relapse (eosinophilia ≥2%: HR = 2·351; 95%CI 1·335-4·139), whereas eosinophilia <2% was associated with a lower risk factor for having early treatment failure (HR = 0·339 95%CI 0·122-0·943).

CONCLUSION

We showed that blood eosinophilia at admission in patients with an AECOPD is associated with higher short-term treatment success rate. However, blood eosinophilia ≥2% predicts a less favorable outcome due to an increased risk of relapse.

CLINICAL TRIAL REGISTRATION

NCT01232140.

Fine particulate matter aggravates allergic airway inflammation through thymic stromal lymphopoietin activation in mice

Fine particulate matter (PM2.5) has been linked to exacerbation of allergic airway inflammation in mice. However, the mechanism underlying exposure to PM2.5 and subsequent and adverse effects remains to be fully elucidated. Therefore, the present study aimed to investigate the effects of PM2.5 by different levels on airway inflammation in mouse models of in allergic and steroid‑resistant asthma. BALB/c mice were nasally instilled with PBS (control) or 10, 31.6 or 100 µg PM2.5, and randomly assigned into nine groups. The acute asthma model was previously induced to investigate the change of inflammatory cells in bronchoalveolar lavage fluid (BALF). Histopathological changes of the lung were assessed, in addition to levels of interleukin (IL)‑4 and IL‑13 in BALF and immunoglobulin Ein serum. Thymic stromal lymphopoietin (TSLP) proteinexpression levels were assessed by western blotting. The present study demonstrated that medium‑ and high‑dose PM2.5 is linked to acute exacerbation of allergic airway inflammation in mice. In conclusion, the pathological mechanisms of PM2.5 may be associated with allergic/steroid‑resistant airway inflammation, T‑cell helper (Th)1/Th2 cytokine production and upregulation of TSLP expression in a murine model of allergic and steroid-resistant asthma.

Activation of Human Peripheral Blood Eosinophils by Cytokines in a Comparative Time-Course Proteomic/Phosphoproteomic Study

Activated eosinophils contribute to airway dysfunction and tissue remodeling in asthma and thus are considered to be important factors in asthma pathology. We report here comparative proteomic and phosphoproteomic changes upon activation of eosinophils using eight cytokines individually and in selected cytokine combinations in time-course reactions. Differential protein and phosphoprotein expressions were determined by mass spectrometry after 2-dimensional gel electrophoresis (2DGE) and by LC-MS/MS. We found that each cytokine-stimulation produced significantly different changes in the eosinophil proteome and phosphoproteome, with phosphoproteomic changes being more pronounced and having an earlier onset. Furthermore, we observed that IL-5, GM-CSF, and IL-3 showed the greatest change in protein expression and phosphorylation, and this expression differed markedly from those of the other five cytokines evaluated. Comprehensive univariate and multivariate statistical analyses were employed to evaluate the comparative results. We also monitored eosinophil activation using flow cytometry (FC) analysis of CD69. In agreement with our proteomic studies, FC indicated that IL-5, GM-CSF, and IL-3 were more effective than the other five cytokines studied in stimulating a cell surface CD69 increase indicative of eosinophil activation. Moreover, selected combinations of cytokines revealed proteomic patterns with many proteins in common with single cytokine expression patterns but also showed a greater effect of the two cytokines employed, indicating a more complex signaling pathway that was reflective of a more typical inflammatory pathology.

Novel Modulators of Asthma and Allergy: Exosomes and MicroRNAs

Intercellular communication is crucial to the immune system response. In the recent years, the discovery of exosomes has changed the way immune response orchestration was understood. Exosomes are able to operate as independent units that act as mediators in both physiological and pathological conditions. These structures contain proteins, lipidic mediators, and nucleic acids and notoriously include microRNAs (miRNAs). miRNAs are short RNA sequences (around 19-22 nucleotides) with a high phylogenetic conservation and can partially or totally regulate multiple mRNAs, inhibiting protein synthesis. In respiratory diseases such as asthma and allergic sensitization, exosomes released by several cell types and their specific content perform crucial functions in the development and continuation of the pathogenic mechanisms. Released exosomes and miRNAs inside them have been found in different types of clinical samples, such as bronchoalveolar lavage fluids and sputum supernatants, providing new data about the environmental factors and mediators that participate in the inflammatory responses that lead to the exacerbation of asthma. In this review, we summarize our current knowledge of the role of exosomes and miRNAs in asthma and allergic sensitization, paying attention to the functions that both exosomes and miRNAs are described to perform through the literature. We review the effect of exosomes and miRNAs in cells implicated in asthma pathology and the genes and pathways that they modify in them, depicting how their behavior is altered in disease status. We also describe their possible repercussion in asthma diagnosis through their possible role as biomarkers. Therefore, both exosomes and miRNAs can be viewed as potential tools to be added to the arsenal of therapeutics to treat this disease.

New Insights Into the Relationship Between Chitinase-3-Like-1 and Asthma

PURPOSE OF REVIEW

CHI3L1 (also known as YKL-40), a member of "mammalian chitinase-like proteins," is a serum protein lacking enzymatic activity. Although the protein is highly conserved in mammals, a consensus regarding its role in human pathologies is currently lacking. In an attempt to shed light on the many physiological functions of the protein, specifically with regard to asthma, a comprehensive overview of recent studies is provided.

RECENT FINDINGS

In asthma, CHI3L1 is secreted from macrophages and airway epithelial cells through an IL-13 related mechanism. Th2-associated inflammatory responses due to allergen exposure, resulting in airway hyper-responsiveness and smooth muscle contraction, play a role in tissue remodeling. The importance of CHI3L1 in initiation and development of asthma is not limited to its involvement in highly orchestrated events of inflammatory cytokines but further research is needed for further elucidation. Levels of the protein are associated with severity for numerous pathologies, including asthma, suggesting limited specificity as a biomarker.

Eosinophil Cationic Protein (ECP), a predictive marker of bullous pemphigoid severity and outcome

Bullous Pemphigoid (BP) is an inflammatory rare autoimmune bullous dermatosis, which outcome cannot be predicted through clinical investigations. Eosinophils are the main immune infiltrated cells in BP. However, the release of Major Basic Protein (MBP), Eosinophil Derived Neurotoxin (EDN), and Eosinophil Cationic Protein (ECP) upon eosinophil activation has still not been evaluated with respect to BP development. MBP, EDN and ECP were measured by ELISA in serum (n = 61) and blister fluid (n = 20) of patients with BP at baseline, and in serum after 2 months of treatment (n = 41). Eosinophil activation in BP patients was illustrated at baseline by significantly higher MBP, EDN and ECP serum concentrations as compared with control subjects (n = 20), but without distinction according to disease severity or outcome. EDN and ECP values were even higher in the blister fluids (P < 0.01 and P < 0.05, respectively), whereas MBP values were lower (P < 0.001). ECP serum concentration decreased after 60 days of treatment in BP patients with ongoing remission but not in patients who later relapsed (P < 0.05). A reduction of at least 12.8 ng/mL in ECP concentrations provided a positive predictive value for remission of 81%, showing that ECP serum variation could be a useful biomarker stratifying BP patients at risk of relapse.

Eosinophilic Esophagitis in a Kitten

A 4 mo old intact male kitten was presented for chronic regurgitation and failure to thrive after weaning to dry food. Esophageal dilatation and severe diffuse proliferative lesions of the esophageal mucosa were found via radiography and esophagoscopy, respectively. Histopathologic examination revealed severe, chronic, diffuse, hyperplastic eosinophilic and mastocytic esophagitis. Eosinophilic infiltrates were prominent, with a mean of 29.8 eosinophils per high power field, supportive of eosinophilic esophagitis (EoE). Significant clinical improvement was seen with dietary modification using a hydrolyzed diet. The addition of glucocorticoids did not result in further improvement in clinical signs. Repeat histopathology showed near resolution of eosinophilic infiltration. EoE is an uncommon and rarely reported condition in dogs and cats. Diagnosis involves histopathologic confirmation and exclusion of other causes of eosinophilic infiltration within the esophagus. This case report demonstrates the importance of biopsy in identification of EoE and the efficacy of dietary modification in the treatment of this disease in a kitten.

Human eosinophils constitutively express a unique serine protease, PRSS33

BACKGROUND

Eosinophils play important roles in asthma, especially airway remodeling, by producing various granule proteins, chemical mediators, cytokines, chemokines and proteases. However, protease production by eosinophils is not fully understood. In the present study, we investigated the production of eosinophil-specific proteases/proteinases by transcriptome analysis.

METHODS

Human eosinophils and other cells were purified from peripheral blood by density gradient sedimentation and negative/positive selections using immunomagnetic beads. Protease/proteinase expression in eosinophils and release into the supernatant were evaluated by microarray analysis, qPCR, ELISA, flow cytometry and immunofluorescence staining before and after stimulation with eosinophil-activating cytokines and secretagogues. mRNAs for extracellular matrix proteins in human normal fibroblasts were measured by qPCR after exposure to recombinant protease serine 33 (PRSS33) protein (rPRSS33), created with a baculovirus system.

RESULTS

Human eosinophils expressed relatively high levels of mRNA for metalloproteinase 25 (MMP25), a disintegrin and metalloprotease 8 (ADAM8), ADAM10, ADAM19 and PRSS33. Expression of PRSS33 was the highest and eosinophil-specific. PRSS33 mRNA expression was not affected by eosinophil-activating cytokines. Immunofluorescence staining showed that PRSS33 was co-localized with an eosinophil granule protein. PRSS33 was not detected in the culture supernatant of eosinophils even after stimulation with secretagogues, but its cell surface expression was increased. rPRSS33 stimulation of human fibroblasts increased expression of collagen and fibronectin mRNAs, at least in part via protease-activated receptor-2 activation.

CONCLUSIONS

Activated eosinophils may induce fibroblast extracellular matrix protein synthesis via cell surface expression of PRSS33, which would at least partly explain eosinophils' role(s) in airway remodeling.

The Biology of Eosinophils and Their Role in Asthma

This review will describe the structure and function of the eosinophil. The roles of several relevant cell surface molecules and receptors will be discussed. We will also explore the systemic and local processes triggering eosinophil differentiation, maturation, and migration to the lungs in asthma, as well as the cytokine-mediated pathways that result in eosinophil activation and degranulation, i.e., the release of multiple pro-inflammatory substances from eosinophil-specific granules, including cationic proteins, cytokines, chemokines growth factors, and enzymes. We will discuss the current understanding of the roles that eosinophils play in key asthma processes such as airway hyperresponsiveness, mucus hypersecretion, and airway remodeling, in addition to the evidence relating to eosinophil–pathogen interactions within the lungs.

Patient profiles and clinical utility of mepolizumab in severe eosinophilic asthma

Mepolizumab (Nucala^®) is an effective and specific anti-eosinophil molecular therapy that has recently been approved as add-on therapy for the management of severe eosinophilic asthma by the US Food and Drug Administration (FDA), European Medicines Agency (EMA; European Union) and more recently National Institute for Health and Care Excellence (NICE; UK). It is one of several molecular therapies in development for this indication and is illustrative of the strategic trajectory for pharmaceutical drug development taken over the past decade in several disease areas. Molecular therapies offer the prospect of improved specificity and effectiveness of biological effect. However, this necessitates a clear understanding of the underlying mechanistic pathways underpinning pathological processes, to inform drug development that yields novel more efficacious treatment options with a better clinical profile than existing agents. For the first time, utilization of molecular therapies in clinical trials is providing a novel in vivo model to characterize the association between specific pathways and clinical disease expression. It is increasingly recognized that asthma exhibits both clinical and pathological heterogeneity. It follows that a one-size-fits-all approach will not be appropriate and cost-effectiveness may only be achieved by identifying responder subgroups. This so-called personalized approach to therapy is being supported by the parallel development of companion biomarkers for clinical application. In this review, the author summarizes the clinical studies, their interpretation and the lessons learnt with mepolizumab that have informed our understanding of the approach to personalized molecular therapy in asthma.

Immune signatures of pathogenesis in the peritoneal compartment during early infection of sheep with Fasciola hepatica

Immune signatures of sheep acutely-infected with Fasciola hepatica, an important pathogen of livestock and humans were analysed within the peritoneal compartment to investigate early infection. Within the peritoneum, F. hepatica antibodies coincided with an intense innate and adaptive cellular immune response, with infiltrating leukocytes and a marked eosinophilia (49%). However, while cytokine qPCR analysis revealed IL-10, IL-12, IL-13, IL-23 and TGFβ were elevated, these were not statistically different at 18 days post-infection compared to uninfected animals indicating that the immune response is muted and not yet skewed to a Th2 type response that is associated with chronic disease. Proteomic analysis of the peritoneal fluid identified infection-related proteins, including several structural proteins derived from the liver extracellular matrix, connective tissue and epithelium, and proteins related to the immune system. Periostin and vascular cell adhesion protein 1 (VCAM-1), molecules that mediate leukocyte infiltration and are associated with inflammatory disorders involving marked eosinophilia (e.g. asthma), were particularly elevated in the peritoneum. Immuno-histochemical studies indicated that the source of periostin and VCAM-1 was the inflamed sheep liver tissue. This study has revealed previously unknown aspects of the immunology and pathogenesis associated with acute fascioliasis in the peritoneum and liver.

Rapid Evolution of Primate Type 2 Immune Response Factors Linked to Asthma Susceptibility

Host immunity pathways evolve rapidly in response to antagonism by pathogens. Microbial infections can also trigger excessive inflammation that contributes to diverse autoimmune disorders including asthma, lupus, diabetes, and arthritis. Definitive links between immune system evolution and human autoimmune disease remain unclear. Here we provide evidence that several components of the type 2 immune response pathway have been subject to recurrent positive selection in the primate lineage. Notably, substitutions in the central immune regulator IL13 correspond to a polymorphism linked to asthma susceptibility in humans. We also find evidence of accelerated amino acid substitutions as well as gene gain and loss events among eosinophil granule proteins, which act as toxic antimicrobial effectors that promote asthma pathology by damaging airway tissues. These results support the hypothesis that evolutionary conflicts with pathogens promote tradeoffs for increasingly robust immune responses during animal evolution. Our findings are also consistent with the view that natural selection has contributed to the spread of autoimmune disease alleles in humans.

Interleukin-5 Inhibitors for Severe Asthma: Rationale and Future Outlook

In this review, we outline the pathophysiology of severe asthma and discuss the role of anti-interleukin (IL)-5 inhibitors for the treatment of asthma. Anti-IL-5 treatments have shown efficacy in reducing the rate of severe asthma attacks in eosinophilic asthma. We review the history of the development of these agents, lessons learnt about severe asthma along the way and key clinical trials supporting efficacy of the three anti-IL-5 treatments that are clinically available or undergoing clinical trials in asthma.

Activation of Eosinophils Interacting with Bronchial Epithelial Cells by Antimicrobial Peptide LL-37: Implications in Allergic Asthma

The role of antimicrobial peptide LL-37 in asthma exacerbation is unclear. Microbial infection, which is the most common inducer of asthma exacerbation, is accompanied by elevated LL-37. The present study found that co-culture of eosinophils and bronchial epithelial cell line BEAS-2B significantly enhanced intercellular adhesion molecule-1 on both cells and CD18 expression on eosinophils upon LL-37 stimulation. IL-6, CXCL8 and CCL4 were substantially released in co-culture in the presence of LL-37. LL-37 triggered the activation of eosinophils interacting with BEAS-2B cells in a P2X purinoceptor 7/epidermal growth factor receptor-dependent manner. Eosinophils and BEAS-2B cells differentially contribute to the expression of cytokines/chemokines in co-culture, while soluble mediators were sufficient to mediate the intercellular interactions. Intracellular p38-mitogen-activated protein kinase, extracellular signal-regulated kinase and NF-κB signaling pathways were essential for LL-37-mediated activation of eosinophils and BEAS-2B cells. By using the ovalbumin-induced asthmatic model, intranasal administration of mCRAMP (mouse ortholog of LL-37) in combination with ovalbumin during the allergen challenge stage significantly enhanced airway hyperresponsiveness and airway inflammation in sensitized mice, thereby implicating a deteriorating role of LL-37 in allergic asthma. This study provides evidence of LL-37 in triggering asthma exacerbation via the activation of eosinophils interacting with bronchial epithelial cells in inflammatory airway.

Innate immunity as the orchestrator of allergic airway inflammation and resolution in asthma

The respiratory system is constantly in direct contact with the environment and, has therefore, developed strong innate and adaptive immune responses to combat pathogens. Unlike adaptive immunity which is mounted later in the course of the immune response and is naive at the outset, innate immunity provides the first line of defense against microbial agents, while also promoting resolution of inflammation. In the airways, innate immune effector cells mainly consist of eosinophils, neutrophils, mast cells, basophils, macrophages/monocytes, dendritic cells and innate lymphoid cells, which attack pathogens directly or indirectly through the release of inflammatory cytokines and antimicrobial peptides, and coordinate T and B cell-mediated adaptive immunity. Airway epithelial cells are also critically involved in shaping both the innate and adaptive arms of the immune response. Chronic allergic airway inflammation and linked asthmatic disease is often considered a result of aberrant activation of type 2 T helper cells (Th2) towards innocuous environmental allergens; however, innate immune cells are increasingly recognized as key players responsible for the initiation and the perpetuation of allergic responses. Moreover, innate cells participate in immune response regulation through the release of anti-inflammatory mediators, and guide tissue repair and the maintenance of airway homeostasis. The scope of this review is to outline existing knowledge on innate immune responses involved in allergic airway inflammation, highlight current gaps in our understanding of the underlying molecular and cellular mechanisms and discuss the potential use of innate effector cells in new therapeutic avenues.

Resolution of a steroid-resistant, hypereosinophilic immune diathesis with mepolizumab and concomitant amelioration of a mixed thrombotic microangiopathy

The anaphylatoxins produced by an unbridled complement cascade in atypical hemolytic uremic syndrome (aHUS) can alter the leukocyte environment in tissues and peripheral blood, causing clinically significant eosinophilia. While the membrane attack complex and C5a anaphlatoxin can be suppressed with anti-C5 biologics, the production of C3a is still capable of driving a destructive hypereosinophilic syndrome in spite of anticomplement therapy. The side-effects of glucocorticoids in treating hypereosinophilic syndrome limit their therapeutic index in long-term treatment and this behooves the use of alternative strategies. While use of the anti-IL-5 antibody, mepolizumab, has been reported for treatment of primary hypereosinophilic syndromes off-label, its usage in the setting of complement-driven thrombotic microangiopathy has not been attempted. We report mepolizumab's rapid resolution of a glucocorticoid-resistant hypereosinophilic syndrome that caused multi-organ dysfunction in a patient with a complex immune diathesis. The patient's long standing TTP/aHUS disease activity, shown to have direct correlation with his eosinophil count, improved with anti-IL-5 therapy, suggesting a reciprocal enhancement between the conditions.

Functional and phenotypic evaluation of eosinophils from patients with the acute form of paracoccidioidomycosis

BACKGROUND

Eosinophilia is a typical finding of the acute/juvenile form of paracoccidioidomycosis (PCM), a systemic mycosis endemic in Latin America. This clinical form is characterized by depressed cellular immune response and production of Th2 cytokines. Moreover, it has been shown that the increased number of eosinophils in peripheral blood of patients returns to normal values after antifungal treatment. However, the role of eosinophils in PCM has never been evaluated. This study aimed to assess the phenotypic and functional characteristics of eosinophils in PCM.

METHODS/PRINCIPAL FINDINGS

In 15 patients with the acute form of the disease, we detected expression of MBP, CCL5 (RANTES) and CCL11 (eotaxin) in biopsies of lymph nodes and liver. In addition, there were higher levels of chemokines and granule proteins in the peripheral blood of patients compared to controls. Isolation of eosinophils from blood revealed a higher frequency of CD69+ and TLR2+ eosinophils in patients compared to controls, and a lower population of CD80+ cells. We also evaluated the fungicidal capacity of eosinophils in vitro. Our results revealed that eosinophils from PCM patients and controls exhibit similar ability to kill P. brasiliensis yeast cells, although eosinophils of patients were less responsive to IL-5 stimulation than controls.

CONCLUSION/PRINCIPAL FINDINGS

In conclusion, we suggest that eosinophils might play a role in the host response to fungi and in the pathophysiology of PCM by inducing an intense and systemic inflammatory response in the initial phase of the infection.

An early innate response underlies severe influenza-induced exacerbations of asthma in a novel steroid-insensitive and anti-IL-5-responsive mouse model

BACKGROUND

Acute worsening of asthma symptoms (exacerbation) is predominantly triggered by respiratory viruses, with influenza causing the most severe exacerbations. The lack of an adequate animal model hampers mechanistic insight and the development of new therapeutics.

AIM

We developed and characterized a robust, consistent, and reproducible mouse model of severe exacerbation of chronic allergic asthma.

METHODS

Chronic allergic airway inflammation was induced following a house dust mite (HDM) sensitization protocol. HDM-sensitized mice and controls were infected with influenza virus A/X31 H3N2 and either or not treated with inhaled fluticasone propionate (FP), systemic corticosteroids (Pred), or anti-IL-5. Mice were killed at different time points after infection: Cellular accumulation and cytokines levels in the airways, PenH as a measure of airway hyper-responsiveness (AHR), and lung histology and viral replication were assessed.

RESULTS

Infection with low-dose A/X31 H3N2 led to prolonged deterioration of lung function, aggravated mucus production, peri-vascular, peri-bronchial, and allergic inflammation that was unresponsive to inhaled corticosteroids, but responsive to systemic corticosteroids. The exacerbation was preceded at 14 h after virus exposure by a marked innate, but no Th2 and Th1 response subsequently followed by enhanced numbers of eosinophils, neutrophils, dendritic, and T cells into the lung lumen, parenchyma, and draining lymph nodes in HDM-sensitized mice. Anti-IL-5 treatment attenuated eosinophils and prevented the X31-induced exacerbation.

CONCLUSIONS

Together, these findings indicate that an early innate response that involves eosinophils underlies the exacerbation. This model recapitulates all major features of severe asthma exacerbations and can serve to discern driving mechanisms and promote the development of novel therapeutics.

The Innate Immune Cross Talk between NK Cells and Eosinophils Is Regulated by the Interaction of Natural Cytotoxicity Receptors with Eosinophil Surface Ligands

Previous studies suggested that the cross talk between NK cells and other cell types is crucial for the regulation of both innate and adaptive immune responses. In the present study, we analyzed the phenotypic and functional outcome of the interaction between resting or cytokine-activated NK cells and eosinophils derived from non-atopic donors. Our results provide the first evidence that a natural cytotoxicity receptor (NCR)/NCR ligand-dependent cross talk between NK cells and eosinophils may be important to upregulate the activation state and the effector function of cytokine-primed NK cells. This interaction also promotes the NK-mediated editing process of dendritic cells that influence the process of Th1 polarization. In turn, this cross talk also resulted in eosinophil activation and acquisition of the characteristic features of antigen-presenting cells. At higher NK/eosinophil ratios, cytokine-primed NK cells were found to kill eosinophils via NKp46 and NKp30, thus suggesting a potential immunoregulatory role for NK cells in dampening inflammatory responses involving eosinophils.

Branchial Pathomorphology of Southern Bluefin Tuna Thunnus maccoyii (Castelnau, 1872) Infected by Helminth and Copepodan Parasites

Three metazoan parasites, a monogenean Hexostoma thynni and two species of copepods Pseudocycnus appendiculatus and Euryphorus brachypterus are known to parasitize the gills of ranched southern bluefin tuna (SBT) and other tuna species. However, there is no detailed information describing the pathological response to infection by these parasites in this species. Wild southern bluefin tuna Thunnus maccoyii (approximately 3 years of age), captured and towed to a grow-out site in the waters immediately south of Port Lincoln, South Australia were subsequently sampled (n = 10) monthly from March until August 2004 during commercial harvest operations. Longitudinal sections of gill hemibranchs with attached parasites were excised and fixed for routine histology and immunohistochemistry. Reference samples were also collected from fish displaying no signs of parasitism or other grossly observable anomalies. Two morphologically distinct granulocytes were observed and putatively identified as eosinophils and mast cells. Pathology was localized to filaments upon and immediately adjacent to parasite attachment sites. Branchial cellular responses, adjunct to the attachment of H. thynni by its opisthaptoral clamps, included hyperplasia and inflammation resulting in structural remodeling of branchial tissues. Inflammatory infiltrates were often dominated by putative eosinophils and lymphocytes when parasitized by H. thynni and P. appendiculatus. Gill associated lymphoid tissue infiltrated the lamellar regions particularly in response to helminth infection. A variable response ranging from hemorrhage with minor hyperplasia or fibroplasia and eosinophilic inflammation to a barely discernible change was seen for gill sections harboring P. appendiculatus and E. brachypterus. The magnitude of the host response to attachment by the latter was congruent with attachment proximity and parasite load. On the basis of the host responses reported here and the low intensity of infection observed in other associated studies these gill ectoparasites are currently considered a low risk for wild and ranched adult SBT.

The Role of the T lymphocytes and Remodeling in Asthma

In allergic asthma (AA), inflammatory changes in the airway epithelium may contribute to the characteristic pathophysiology and symptoms. The presence of T lymphocytes, eosinophils, mast cells and macrophages, the presence of cytokines, and also structural changes in the airway mucous membrane are characteristic for asthma. Bronchial biopsy specimens were obtained from 33 AA, 25 nonallergic asthma (NAA), and 20 healthy controls (HC). This study used immunohistochemical techniques for identified monoclonal antibodies (CD3, CD4, CD8, CD25, ECP, MBP, tenascin, and laminin) in the bronchi. The highest number of eosinophils and T lymphocyte cells in bronchial biopsies was found in AA, and NAA. The number of T lymphocytes in AA was significantly higher than in NAA and HC. The degree of epithelial damage was higher in the AA group compared to the other groups. The tenascin- and laminin-positive layers in AA were thicker than other groups. In AA, a significant negative correlation was found between epithelial integrity and the count for eosinophils or T lymphocytes. T lymphocytes and eosinophils in AA were found in the area of epithelial and lamina propria damage. This article suggests that T lymphocytes may not only contribute to the chronic airway inflammatory response, airway remodeling, and symptomatology but may also have a central role at the initiation of the allergic immune response. Th-targeted therapy would be of considerable interest in controlling AA. Having more knowledge on the roles of T lymphocytes in the pathogenesis of allergic inflammation highlights the contributions of these cells in regulating and may lead to a new therapeutic target-AA.

A possible role for neutrophils in allergic rhinitis revealed after cellular subclassification

A re-examination of former concepts is required to meet today’s medical challenges in allergic rhinitis. Previously, neutrophils have been treated as a relatively homogenous cell population found in the nose both when the patient is suffering at the height of the allergic season as well as when the patient report no symptoms. However, new data indicates that neutrophils can be divided into different subsets with diverse roles in inflammation. We showed increased levels of neutrophils in peripheral blood, nasal biopsies and nasal lavage fluid (NAL) from allergic patients during the pollen season compared to healthy controls. A closer examination revealed that the activated subset of neutrophils, CD16^high CD62L^dim, outweighed the normal form CD16^high CD62L^high in nasal tissue among these patients. This skewed distribution was not seen in controls. The normal subset prevailed in peripheral blood from patients as well as controls, whereas CD16^high CD62L^dim and CD16^dim CD62L^dim subsets, the latter considered “end state” neutrophils before apoptosis, were elevated in NAL. Functional in vitro experiments revealed that activated neutrophils exhibit a T cell priming capacity and an ability to enhance eosinophil migration. Activated neutrophils may thus contribute to allergic inflammation seen in allergic rhinitis by priming T cells and attracting eosinophils.

Comparison of ultrastructural and nanomechanical signature of platelets from acute myocardial infarction and platelet activation

Acute myocardial infarction (AMI) initiation and progression follow complex molecular and structural changes in the nanoarchitecture of platelets. However, it remains poorly understood how the transformation from health to AMI alters the ultrastructural and biomechanical properties of platelets within the platelet activation microenvironment. Here, we show using an atomic force microscope (AFM) that platelet samples, including living human platelets from the healthy and AMI patient, activated platelets from collagen-stimulated model, show distinct ultrastructural imaging and stiffness profiles. Correlative morphology obtained on AMI platelets and collagen-activated platelets display distinct pseudopodia structure and nanoclusters on membrane. In contrast to normal platelets, AMI platelets have a stiffer distribution resulting from complicated pathogenesis, with a prominent high-stiffness peak representative of platelet activation using AFM-based force spectroscopy. Similar findings are seen in specific stages of platelet activation in collagen-stimulated model. Further evidence obtained from different force measurement region with activated platelets shows that platelet migration is correlated to the more elasticity of pseudopodia while high stiffness at the center region. Overall, ultrastructural and nanomechanical profiling by AFM provides quantitative indicators in the clinical diagnostics of AMI with mechanobiological significance.

Ribosomal protein S3 gene silencing protects against experimental allergic asthma

BACKGROUND AND PURPOSE

Ribosomal protein S3 (RPS3) is a 40S ribosomal protein of the S3P family essential for implementing protein translation. RPS3 has recently been found to interact with the p65 subunit of the NF-κB complex and promote p65 DNA-binding activity. Persistent activation of the NF-κB pathway is evident in allergic asthma. We hypothesized that gene silencing of lung RPS3 can ameliorate allergic airway inflammation.

EXPERIMENTAL APPROACH

The gene silencing efficacy of RPS3 siRNA was screened in three different mouse cell lines by real-time PCR and immunoblotting. Protective effects of intratracheal RPS3 siRNA in a house dust mite (HDM) mouse asthma model were determined by measuring cell counts in lung lavage fluid and lung sections, lung cytokine profiles and airway hyperresponsiveness (AHR).

KEY RESULTS

RPS3 siRNA markedly knocked down RPS3 levels in all mouse cell lines tested, and in mouse lung tissues, blocked TNF-α- or HDM-induced release of mediators by the cultured cells and reduced eosinophil counts in lung lavage fluid from the HDM mouse asthma model. RPS3 siRNA lessened HDM-induced airway mucus hypersecretion, cytokine production and serum IgE elevation. Moreover, RPS3 knockdown significantly suppressed methacholine-induced AHR in experimental asthma. RPS3 siRNA disrupted TNF-α-induced NF-κB activation in a NF-κB reporter gene assay in vitro and prevented the nuclear accumulation of p65 subunit and p65 transcriptional activation in HDM-challenged lungs and cells.

CONCLUSIONS AND IMPLICATIONS

RPS3 gene silencing ameliorates experimental asthma, probably by disrupting NF-κB activity. RPS3 could be a novel therapeutic target for allergic airway inflammation.

Hypereosinophilic cardiac disease

Hypereosinophilia may be due to several aetiologies. Cardiac complications are not uncommon, whatever the causes. Clinical presentations of hypereosinophilic cardiac diseases may vary widely from asymptomatic form to fatal necrotic myocarditis or irreversible restrictive cardiomyopathy. As a major cause of morbidity and mortality, diagnosis of cardiac involvement is crucial. Until recently the diagnosis was exclusively based on cardiac biopsy. Nowadays, multimodal cardiac imaging, including echocardiography and cardiac magnetic resonance imaging, is the cornerstone of the diagnosis. Cardiac magnetic resonance imaging has emerged as a very useful tool for the diagnosis allowing precise tissue characterization. It has even been proposed as a surrogate to cardiac biopsy. It should be systematically performed in case of hypereosinophilia. Early and appropriate treatment is crucial to avoid the evolution toward irreversible cardiac lesions. These treatments are symptomatic but should also be adapted to the underlying diseases.

Role of Eosinophil Granulocytes in Allergic Airway Inflammation Endotypes

Eosinophil granulocytes are intriguing members of the innate immunity system that have been considered important defenders during parasitic diseases as well as culprits during allergy-associated inflammatory diseases. Novel studies have, however, found new homoeostasis-maintaining roles for the cell. Recent clinical trials blocking different Th2 cytokines have uncovered that asthma is heterogeneous entity and forms different characteristic endotypes. Although eosinophils are present in allergic asthma with early onset, the cells may not be essential for the pathology. The cells are, however, likely disease causing in asthma with a late onset, which is often associated with chronic rhinosinusitis. Assessment of eosinophilia, fraction exhaled nitric oxide (FeNO) and periostin are markers that have emerged useful in assessing and monitoring asthma severity and endotype. Current scientific knowledge suggests that eosinophils are recruited by the inflammatory environment, activated by the innate interleukin (IL)-33 and prevented from apoptosis by both lymphocytes and innate immune cells such as type two innate immune cells. Eosinophils contain four specific granule proteins that exhibit an array of toxic and immune-modulatory activates. The granule proteins can be released by different mechanisms. Additionally, eosinophils contain a number of inflammatory cytokines and lipid mediators as well as radical oxygen species that might contribute to the disease both by the recruitment of other cells and the direct damage to supporting cells, leading to exacerbations and tissue fibrosis. This review aimed to outline current knowledge how eosinophils are recruited, activated and mediate damage to tissues and therapies used to control the cells.

The transition of sputum inflammatory cell profiles is variable in stable asthma patients

Background

The sputum inflammatory cell profile is an important indicator for classifying asthma phenotypes.

Objective

To investigate if sputum inflammatory cell profile remains stable and there are different characteristics between groups that show different profile over time in stable asthmatic patients.

Methods

A total of 149 asthmatic patients, who were clinically stable at the time of sputum examination and had undergone sputum analysis twice, were subjected to a detailed review. Eosinophilic inflammation was diagnosed when the proportion of the sputum eosinophils was >3%. We divided the patients into 4 groups according to the transition patterns of their sputum profiles: group 1, persistent eosinophilia; group 2, eosinophilic to noneosinophilic; group 3, noneosinophilic to eosinophilic; and group 4, persistent noneosinophilia. The results of the pulmonary function tests and other clinical parameters were compared between these 4 groups.

Results

Thirty-four of the initially eosinophilic asthmatic patients (39.5%; 34 of 86 patients) demonstrated noneosinophilic airway inflammation at their second sputum examination, and 24 of the initially noneosinophilic patients (38.1%; 24 of 63 patients) demonstrated eosinophilic airway inflammation at follow-up. Various clinical parameters, except the blood eosinophil count, demonstrated no significant differences between the eosinophilic and noneosinophilic asthmatic patients or among the 4 groups.

Conclusion

A substantial proportion of asthmatic patients who demonstrate a certain sputum inflammatory cell profile at the initial examination demonstrated profile transition in clinically stable settings over time. The clinical significance of using induced sputum analysis to phenotype stable asthmatic patients requires further evaluation.

Impact of Dietary Protein Concentration and Quality on Immune Function of Cats

Protein levels and quality in cat food can vary significantly and might affect immune function in various ways. In the present study, 3 diets with a low protein quality (LQ) and 3 diets with a high protein quality (HQ) were offered to 10 healthy adult cats for 6 weeks each, using a randomized cross-over design. The LQ and HQ diets differed in the collagen content and had low (36.7% and 36.2%), medium (45.0% and 43.3%) and high (56.1% and 54.9%) protein levels. At the end of each feeding period, blood was collected for phenotyping of leukocyte subsets, lymphocyte proliferation assay and cytokine measurements, phagocytosis assay and differential blood count. The results demonstrated no group differences for numbers of CD4⁺CD8^-, CD4⁺CD8⁺, CD4^-CD8⁺, MHCII⁺, CD21⁺, SWC3⁺ and CD14⁺ cells in the blood of the cats. Proliferative activity of lymphocytes when stimulated with pokeweed mitogen, Concanavalin A and Phytohemagglutinin, M form did not differ depending on the dietary protein concentration and quality. Concentrations of tumor necrosis factor alpha and interferon gamma in the supernatant of the proliferation assay were also not affected by the dietary treatment. Blood monocyte phagocytic activity was higher (P = 0.048) and cell numbers of eosinophilic granulocytes in the blood were lower (P = 0.047) when cats were fed the low protein diets. In conclusion, only a few differences in feline immune cell populations and activity depending on dietary protein supply could be detected. However, the observed increase of eosinophilic granulocytes by a higher protein intake indicates an activation of immunological mechanisms and requires further investigation.