Eosinophils in the pathogenesis of allergic airways disease

Eosinophils induces glioblastoma cell suppression and apoptosis - Roles of GM-CSF and cysteinyl-leukotrienes

BACKGROUND

Glioblastoma is the most common and lethal primary brain tumor in adults. Despite the available cancer treatments, the recurrence of the tumor is high, and the survival rate is low. New approaches to antitumor therapies are needed. Eosinophils are prominent in allergic diseases and accumulate in several human brain tumors. Recently, the antitumor role of eosinophils has been targeted as eosinophils release several cytotoxic factors that induce cell impairment and death.

OBJECTIVE

Here we aim to evaluate the interaction of the eosinophil and glioblastoma cells, the mechanism involved in the potential killing of the glioblastoma cells by the eosinophils, and how allergy/asthma could confer a better glioblastoma prognosis.

METHODS

Eosinophils and serum from asthmatic and non-asthmatic donors were cultivated with different glioblastoma cell lines.

RESULTS

Glioblastoma cells recruit eosinophils via GM-CSF signaling, activating and increasing eosinophil survivability and function on a GM-CSF-dependent manner. Eosinophils reduce glioblastoma cells metabolism, proliferation, and migration, via Fas/FasL. Cysteinyl-leukotrienes are accounted for the asthmatic serum enhancement of the glioblastoma cell migration and proliferation. Cysteinyl-leukotrienes enhance glioblastoma cell proliferation and migration, albeit activate eosinophils that suppress glioblastoma cells.

CONCLUSION

Eosinophils have the potential to be key cells on glioblastoma therapeutics, as allergy and eosinophilia are correlated with a better glioblastoma prognosis. Eosinophils are elicited and attach to glioblastoma cells, where, by its cytotoxic function, via Fas/FasL, hind glioblastoma cell metabolism, proliferation, migration, and induce cell death.

Management of eosinophil-associated inflammatory diseases: the importance of a multidisciplinary approach

Elevated eosinophil counts in blood and tissue are a feature of many pathological processes. Eosinophils can migrate and accumulate in a wide variety of tissues and, by infiltrating a target organ, can mediate the development of several inflammatory diseases. The normalization of eosinophilia is a common biomarker of a treatable trait and can also be used as a prognostic and predictive biomarker since it implies a reduction in type 2 inflammation that contributes to disease pathogenesis. Biological therapies targeting this cell type and its proinflammatory mediators have been shown to be effective in the management of a number of eosinophilic diseases, and for this reason they constitute a potential common strategy in the treatment of patients with various multimorbidities that present with type 2 inflammation. Various biological options are available that could be used to simultaneously treat multiple target organs with a single drug, bearing in mind the need to offer personalized treatments under the umbrella of precision medicine in all patients with eosinophil-associated diseases (EADs). In addition to reviewing these issues, we also discuss a series of perspectives addressing the management of EAD patients from a multidisciplinary approach, with the collaboration of health professionals from different specialties who manage the different multimorbidities that frequently occur in these patients. We examine the basic principles of care that this multidisciplinary approach must cover and present a multidisciplinary expert opinion regarding the ideal management of patients with EADs, from diagnosis to therapeutic approach and follow-up.

Eosinophilic Airway Diseases: From Pathophysiological Mechanisms to Clinical Practice

Eosinophils play a key role in airway inflammation in many diseases, such as allergic and non-allergic asthma, chronic rhinosinusitis with nasal polyps, and chronic obstructive pulmonary disease. In these chronic disabling conditions, eosinophils contribute to tissue damage, repair, remodeling, and disease persistence through the production a variety of mediators. With the introduction of biological drugs for the treatment of these respiratory diseases, the classification of patients based on clinical characteristics (phenotype) and pathobiological mechanisms (endotype) has become mandatory. This need is particularly evident in severe asthma, where, despite the great scientific efforts to understand the immunological pathways underlying clinical phenotypes, the identification of specific biomarkers defining endotypes or predicting pharmacological response remains unsatisfied. In addition, a significant heterogeneity also exists among patients with other airway diseases. In this review, we describe some of the immunological differences in eosinophilic airway inflammation associated with severe asthma and other airway diseases and how these factors might influence the clinical presentation, with the aim of clarifying when eosinophils play a key pathogenic role and, therefore, represent the preferred therapeutic target.

Serum interleukin 38 (IL-38) as a new potential biomarker of pediatric asthma

Background

Bronchial asthma is considered the most prevalent chronic respiratory disease worldwide and is one of the main causes of hospitalization in the pediatric population. Serum interleukin 38 (IL-38) levels are elevated in several inflammatory and autoimmune diseases. However, its exact role in the pathogenesis of these diseases is unclear.

Objectives

To investigate the role of IL-38 as a potential biomarker in pediatric patients with bronchial asthma.

Methods

Serum IL-38 levels were measured in 73 pediatric patients with bronchial asthma (34 atopic and 39 non-atopic) and 30 age- and sex-matched healthy control subjects using enzyme-linked immunosorbent assay.

Results

Serum IL-38 levels were significantly higher in patients with bronchial asthma compared to the control group (p < 0.001). A significant negative correlation was found between serum IL-38 levels and both relative and absolute eosinophilic counts in the atopic group (R = −0.575, p < 0.001 and R = −0.474, p = 0.005, respectively).

Conclusion

IL-38 could be a useful prognostic and therapeutic biomarker of atopic asthma in pediatric patients.

Exploring the Potential Effects and Mechanisms of Asarum sieboldii Radix Essential Oil for Treatment of Asthma

Asthma, a common chronic pulmonary disorder characterized by airway remodeling, hyperresponsiveness and obstruction, can be aggravated by repeated exposure to particulate matter (PM). The potential effect and mechanisms of Asarum sieboldii Radix essential oil (AEO) against asthma were explored based on network pharmacology. AEO was pre-treated using a nebulizer for 3 weeks and the mice were sensitized to ovalbumin (OVA) and PM10 with the co-treatment of AEO for 4 weeks. In addition, A549 lung epithelial cells were sensitized with PM10 to investigate the underlying mechanisms of AEO regarding the lung-fibrosis-related mediators. The target genes of methyl eugenol, a main compound of AEO, were highly matched by 48% with the gene set of asthma. AEO markedly inhibited the increase in epithelial thickness through the accumulation of goblet cells in the airways. Collagen deposition in the lung tissues of OVA+PM10-challenged asthmatic mice was significantly decreased by AEO. AEO also inhibited the influx of inflammatory cells in the bronchoalveolar lavage fluid, as well as the increases in serum IgE and IgG2a and cytokines in the lung tissues. Furthermore, AEO regulated the expressions of fibrotic mediators, especially POSTN and TGF-β. In conclusion, we expect that AEO can be one of the effective alternative therapeutics to relieve asthma.

The anti-inflammatory effect of dapsone on ovalbumin-induced allergic rhinitis in balb/c mice

AIMS

Allergic rhinitis (AR), a major chronic inflammatory disease of the respiratory system, is a public health issue because of its substantial negative impact on quality of life and work efficiency alongside its high prevalence and costs. Dapsone is a sulfone chemical with reported anti-inflammatory and antibacterial properties. Accordingly, we investigated the anti-inflammatory impact of dapsone on ovalbumin-induced allergic rhinitis in balb/c mice.

MAIN METHODS

Intraperitoneal ovalbumin and hydroxide aluminum injection followed by intranasal ovalbumin administration sensitized female Balb/c mice. Mice received intraperitoneal dapsone either acute (5, 10, 20 mg/kg) 30 min before the last ovalbumin challenge, or chronic (20 mg/kg) on days 21 to 35.

KEY FINDINGS

Both acute and chronic intraperitoneal usage of dapsone showed a considerable decrease in the nasal scratching behavior, the number of sneezing, serum IL-4 and IgE levels of ovalbumin-induced AR in balb/c mice, but there was a significant increase in serum IFNγ level. Histopathological analysis demonstrated a significant reduction of eosinophil numbers, following dapsone injection. Goblet cell hyperplasia and respiratory epithelial-thickness decreased significantly in the acute and chronic 20 mg/kg dapsone groups compared to the ovalbumin-induced controls.

SIGNIFICANCE

This study shows that there is an association between acute and chronic dapsone treatment and some anti-allergic effects through an inflammation cascade.

[Possible therapeutic use of L-type amino acid transporter 1 (LAT1)-specific inhibitor for intractable asthma treatment]

Bronchial asthma (asthma) is characterized by chronic airway inflammation, reversible obstruction, and hyperresponsive conditions. Although most asthma patients have been becoming controllable by virtue of inhaled corticosteroid (ICS), substantial number of patients still do not respond to the steroid-based therapy. Mast cells, eosinophils, and helper T (Th) 2 cells have been considered as key players in asthma pathogenesis. However, emerging studies have revealed that Th subsets other than Th2, as well as various other immune cells, significantly contribute to the development of steroid-resistant intractable asthma. T cells and other inflammatory cells require incorporating a large amount of nutrients such as amino acids and glucose to exhibit their full function following activation. Based on this remarkable character, it has recently been suggested that the pharmacological inhibition of amino acid transporters is promising for treating immunological and inflammatory disorders through the suppression of inflammatory cell activation. In this review, we explore the possible management of intractable asthma by developing a selective inhibitor for L-type amino acid transporter (LAT) 1.

The Effect of Curcuma longa on Inflammatory Mediators and Immunological, Oxidant, and Antioxidant Biomarkers in Asthmatic Rats

The effects of Curcuma longa (C. longa) on total and differential WBC, inflammatory and immunologic mediators, and oxidant and antioxidant biomarkers in bronchoalveolar lavage fluid (BALF) of rats model of asthma were assessed. Animals were divided to 5 groups including control (C), asthma (sensitized to ovalbumin), and asthmatic groups treated with 0.75, 1.50, and 3.00 mg/ml C. longa (CL) and 1.25 μg/ml dexamethasone (D) (8 rats in each group). Total and differential WBC count, concentrations of phospholipase A₂ (PLA₂), total protein (TP), interferon-gamma (IFN-γ), interleukin-4 (IL-4), immunoglobulin E (IgE), NO₂, NO₃, malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and thiol in BALF were assessed. Total and most differential WBC counts and BALF levels of PLA₂, TP, IgE, IL-4, and oxidants in asthma group were higher but antioxidants and IFN-γ levels as well as IFN-γ/IL-4 ratio were lower than control group (p < 0.001 for all cases). Total WBC and levels of PLA₂, IgE, NO₂, and NO₃ were significantly reduced following treatment with C. longa, compared to asthma group (p < 0.001 for all cases). In groups treated with dexamethasone and two higher concentrations of C. longa, neutrophil and eosinophil counts as well as TP, IL-4, and MDA levels were significantly decreased but IFN-γ, IFN-γ/IL-4 ratio, and antioxidants were increased (except IFN-γ/IL-4 ratio), compared to asthma group (p < 0.05 to p < 0.001). Compared to dexamethasone, C. longa exerted more pronounced effects on lung inflammation, oxidative stress, and immune system in asthmatic rats.

Lipoxin A4 inhibits ovalbumin-induced airway inflammation and airway remodeling in a mouse model of asthma

Asthma is a chronic respiratory disease, which is characterized by airway inflammation, remodeling and airway hyperresponsiveness. Airway remodeling is caused by long-term inflammation of the airways. Lipoxin A4 (LXA4) is a natural eicosanoid with powerful anti-inflammatory properties, and has been shown to serve a critical role in orchestrating pulmonary inflammation and airway hyper-responsiveness in asthmatic mice. However, its effect on airway remodeling is unknown. Female BALB/c mice were used to establish a mouse model of asthma which were sensitized and challenged by ovalbumin (OVA). LXA4 was intranasally administrated prior to the challenge. The results of our study indicated that LXA4 suppressed the OVA-induced inflammatory cell infiltration and T helper type 2 (Th2) cytokines secretion in the mouse model of asthma. Characteristics of airway remodeling, such as thickening of the bronchial wall and smooth muscle, overdeposition of collagen, and overexpression of α-smooth muscle actin (α-SMA) and collagen-I were reversed by LXA4. Furthermore, LXA4 suppressed the aberrant activation of the signal transducer and activator of transcription 3 (STAT3) pathway in the lung tissues of asthmatic mice. In conclusion, these findings demonstrated that LXA4 alleviated allergic airway inflammation and remodeling in asthmatic mice, which may be related to the inhibition of STAT3 pathway.

Predicting treatment outcomes following an exacerbation of airways disease

Background

COPD and asthma exacerbations result in many emergency department admissions. Not all treatments are successful, often leading to hospital readmissions.

Aims

We sought to develop predictive models for exacerbation treatment outcome in a cohort of exacerbating asthma and COPD patients presenting to the emergency department.

Methods

Treatment failure was defined as the need for additional systemic corticosteroids (SCS) and/or antibiotics, hospital readmissison or death within 30 days of initial emergency department visit. We performed univariate analysis comparing characteristics of patients either given or not given SCS at exacerbation and of patients who succeeded versus failed treatment. Patient demographics, medications and exacerbation symptoms, physiology and biology were available. We developed multivariate random forest models to identify predictors of SCS prescription and for predicting treatment failure.

Results

Data were available for 81 patients, 43 (53%) of whom failed treatment. 64 (79%) of patients were given SCS. A random forest model using presence of wheeze at exacerbation and blood eosinophil percentage predicted SCS prescription with area under receiver operating characteristic curve (AUC) 0.69. An 11 variable random forest model (which included medication, previous exacerbations, symptoms and quality of life scores) could predict treatment failure with AUC 0.81. A random forest model using just the two best predictors of treatment failure, namely, visual analogue scale for breathlessness and sputum purulence, predicted treatment failure with AUC 0.68.

Conclusion

Prediction of exacerbation treatment outcome can be achieved via supervised machine learning combining different predictors at exacerbation. Validation of our predictive models in separate, larger patient cohorts is required.

Mendelian randomization under the omnigenic architecture

Mendelian randomization (MR) is a common analytic tool for exploring the causal relationship among complex traits. Existing MR methods require selecting a small set of single nucleotide polymorphisms (SNPs) to serve as instrument variables. However, selecting a small set of SNPs may not be ideal, as most complex traits have a polygenic or omnigenic architecture and are each influenced by thousands of SNPs. Here, motivated by the recent omnigenic hypothesis, we present an MR method that uses all genome-wide SNPs for causal inference. Our method uses summary statistics from genome-wide association studies as input, accommodates the commonly encountered horizontal pleiotropy effects and relies on a composite likelihood framework for scalable computation. We refer to our method as the omnigenic Mendelian randomization, or OMR. We examine the power and robustness of OMR through extensive simulations including those under various modeling misspecifications. We apply OMR to several real data applications, where we identify multiple complex traits that potentially causally influence coronary artery disease (CAD) and asthma. The identified new associations reveal important roles of blood lipids, blood pressure and immunity underlying CAD as well as important roles of immunity and obesity underlying asthma.

Treatment Challenges in Severe Eosinophilic Asthma: Differential Response to Anti-IL-5 and Anti-IL-5R Therapy

Severe asthma greatly affects patients' quality of life. Major advances have occurred in the management of severe eosinophilic asthma the past few years due to the new targeted biological therapies. There are three anti-IL-5 mAbs, mepolizumab, reslizumab and benralizumab. Despite the different mechanism of blocking IL-5 the clinical effects are quite similar as randomized controlled trials and real-life studies have shown. Moreover, there are reports of responding to one after failing to respond to another anti-IL-5 therapy. Accordingly, it is challenging to explore the possible differences in the response to anti-IL-5 treatments. This might help us not only understand possible mechanisms that contribute to the resistance to treatment in this particular asthma endotype, but also to phenotype within severe eosinophilic asthma in order to treat our patients more efficiently.

Interleukin-1α Is a Critical Mediator of the Response of Human Bronchial Fibroblasts to Eosinophilic Inflammation

Eosinophils contribute to allergic inflammation in asthma in part via elaboration of a complex milieu of soluble mediators. Human bronchial fibroblasts (HBF) respond to stimulation by these mediators by acquiring a pro-inflammatory profile including induction of interleukin 6 (IL6) and IL8. This study sought to determine key component(s) of eosinophil soluble factors that mediate IL6 and IL8 induction in HBF. HBF treated with eosinophil-derived soluble mediators were analyzed for gene expression, intracellular signaling, and IL6 and IL8 secretion following inhibition of inflammatory signaling. Segmental allergen bronchoprovocation (SBP-Ag) was performed in mild asthmatics and bronchoalveolar lavage fluid was analyzed for eosinophils and cytokines. We found that signaling via the IL1α/IL1 receptor is an essential component of the response of HBF to eosinophil-derived soluble factors. IL1α-dependent activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) signaling is required to induce IL6 secretion. However, NFκB signaling is dispensable for the induction of IL8, whereas Src is required. IL1α is associated with eosinophilic inflammation in human airways after SBP-Ag. Conclusions: IL1α appears to be a critical component of the soluble eosinophil-derived milieu that drives pro-inflammatory bronchial fibroblast responses and associates with eosinophilic inflammation following SBP-Ag. Disruption of IL1α-signaling could modify the downstream effects of eosinophilic inflammation on airway remodeling.

Boysenberry and apple juice concentrate reduced acute lung inflammation and increased M2 macrophage-associated cytokines in an acute mouse model of allergic airways disease

Bioactive compounds including anthocyanins and other polyphenols are associated with reduced lung inflammation and improved lung function in asthma and other lung diseases. This study investigated the effects of a Boysenberry and apple juice concentrate, high in cyanidin glycosides, ellagitannins, and chlorogenic acid, on a mouse model of allergic airways inflammation. Male C57BL/6J mice were orally gavaged with 2.5 mg/kg of total anthocyanins (TAC) from BerriQi® Boysenberry and apple juice concentrate (0.2 mg/kg human equivalent dose) or water control 1 hr before an acute intranasal ovalbumin (OVA) challenge and were gavaged again 2 days after the intranasal challenge. Consumption of BerriQi® Boysenberry and apple juice concentrate significantly decreased OVA-induced infiltrating eosinophils, neutrophils, and T cells in the lung, and mucous production. Quantification of gene expression for arginase (Arg1), chitinase 3-like 3 (Ym-1), found in inflammatory zone (Fizz1), which have been associated with an anti-inflammatory macrophage phenotype (M2), found significantly increased Arg1 expression in the lung in the Boysenberry and apple juice concentrate treatment group. There was also increased production of M2-associated cytokines C-X-C motif chemokine ligand (CXCL) 10 and C-C motif chemokine ligand (CCL) 4. These results suggest that consumption of BerriQi® Boysenberry and apple juice concentrate promoted a shift toward an anti-inflammatory environment within the lung leading to reduced immune cell infiltration and tissue damage.

Eosinophils and childhood asthma

Eosinophils are a type of granulocyte with eosinophilic granules in the cytoplasm that play an important role in allergic and parasitic diseases. Eosinophils are important in the pathogenesis of asthma, and many studies have examined the relationship between them. In allergic eosinophilic asthma, eosinophils act not only as important effector cells but also as antigen-presenting cells in allergic inflammatory reactions. In nonallergic eosinophilic asthma, type 2 innate lymphoid cells in the airways play an important role in eosinophil activation. Direct methods, including bronchial biopsy, bronchoalveolar lavage, and the induced sputum test, are used to evaluate eosinophilic inflammatory reactions in patients with asthma, however, because of difficulty with their implementation, they are sometimes replaced by measurements of blood eosinophils, fraction of exhaled nitric oxide, and serum periostin level. However, these tests are less accurate than direct methods. For the treatment of patients with severe eosinophilic asthma, anti-interleukin-5 preparations such as mepolizumab, reslizumab, and benralizumab have recently been introduced and broadened the scope of asthma treatment. Although eosinophils are already known to play an important role in asthma, we expect that further studies will reveal more details of their action.

Loss of versican and production of hyaluronan in lung epithelial cells are associated with airway inflammation during RSV infection

Airway inflammation is a critical feature of lower respiratory tract infections caused by viruses such as respiratory syncytial virus (RSV). A growing body of literature has demonstrated the importance of extracellular matrix changes such as the accumulation of hyaluronan (HA) and versican in the subepithelial space in promoting airway inflammation; however, whether these factors contribute to airway inflammation during RSV infection remains unknown. To test the hypothesis that RSV infection promotes inflammation via altered HA and versican production, we studied an ex vivo human bronchial epithelial cell (BEC)/human lung fibroblast (HLF) coculture model. RSV infection of BEC/HLF cocultures led to decreased hyaluronidase expression by HLFs, increased accumulation of HA, and enhanced adhesion of U937 cells as would be expected with increased HA. HLF production of versican was not altered following RSV infection; however, BEC production of versican was significantly downregulated following RSV infection. In vivo studies with epithelial-specific versican-deficient mice [SPC-Cre(+) Vcan-/-] demonstrated that RSV infection led to increased HA accumulation compared with control mice, which also coincided with decreased hyaluronidase expression in the lung. SPC-Cre(+) Vcan-/- mice demonstrated enhanced recruitment of monocytes and neutrophils in bronchoalveolar lavage fluid and increased neutrophils in the lung compared with SPC-Cre(-) RSV-infected littermates. Taken together, these data demonstrate that altered extracellular matrix accumulation of HA occurs following RSV infection and may contribute to airway inflammation. In addition, loss of epithelial expression of versican promotes airway inflammation during RSV infection further demonstrating that versican's role in inflammatory regulation is complex and dependent on the microenvironment.

Juvenile, but Not Adult, Mice Display Increased Myeloid Recruitment and Extracellular Matrix Remodeling during Respiratory Syncytial Virus Infection

Early life respiratory syncytial virus (RSV) infection has been linked to the onset of asthma. Despite this association, our knowledge of the progression of the initial viral infection is limited, and no safe or effective vaccine currently exists. Bronchioalveolar lavage, whole-lung cellular isolation, and gene expression analysis were performed on 3-wk- (juvenile) and 8-wk-old (adult) RSV-infected C57BL/6 mice to investigate age-related differences in immunologic responses; juvenile mice displayed a sustained myeloid infiltrate (including monocytes and neutrophils) with increased RNA expression of Ccl2, Ccl3, and Ccl4, when compared with adult mice, at 72 h postinfection. Juvenile mice demonstrated αSma expression (indicative of myofibroblast activity), increased hyaluronan deposition in the lung parenchyma (attributed to asthma progression), and a lack of CD64 upregulation on the surface of monocytes (which, in conjunction with serum amyloid P, is responsible for clearing residual hyaluronan and cellular debris). RSV infection of human airway epithelial cell, human lung fibroblast, and U937 monocyte cocultures (at air-liquid interface) displayed similar CCL expression and suggested matrix metalloproteinase-7 and MMP9 as possible extracellular matrix modifiers. These mouse data, in conjunction with our findings in human monocytes, suggest that the sustained influx of myeloid cells in the lungs of juvenile mice during acute RSV infection could potentiate extracellular matrix remodeling, facilitating conditions that support the development of asthma.

Long Noncoding RNAs in the Regulation of Asthma: Current Research and Clinical Implications

Asthma is a chronic airway inflammatory disorder related to variable expiratory airflow limitation, leading to wheeze, shortness of breath, chest tightness, and cough. Its characteristic features include airway inflammation, airway remodeling and airway hyperresponsiveness. The pathogenesis of asthma remains extremely complicated and the detailed mechanisms are not clarified. Long noncoding RNAs (lncRNAs) have been reported to play a prominent role in asthma and function as modulators of various aspects in pathological progress of asthma. Here, we summarize recent advances of lncRNAs in asthma pathogenesis to guide future researches, clinical treatment and drug development, including their regulatory functions in the T helper (Th) 1/Th2 imbalance, Th17/T regulatory (Treg) imbalance, eosinophils dysfunction, macrophage polarization, airway smooth muscle cells proliferation, and glucocorticoid insensitivity.

Limonene-induced activation of A2A adenosine receptors reduces airway inflammation and reactivity in a mouse model of asthma

Animal models of asthma have shown that limonene, a naturally occurring terpene in citrus fruits, can reduce inflammation and airway reactivity. However, the mechanism of these effects is unknown. We first performed computational and molecular docking analyses that showed limonene could bind to both A_2A and A_2B receptors. The pharmacological studies were carried out with A_2A adenosine receptor knock-out (A_2AKO) and wild-type (WT) mice using ovalbumin (OVA) to generate the asthma phenotype. We investigated the effects of limonene on lung inflammation and airway responsiveness to methacholine (MCh) and NECA (nonselective adenosine analog) by administering limonene as an inhalation prior to OVA aerosol challenges in one group of allergic mice for both WT and KO. In whole-body plethysmography studies, we observed that airway responsiveness to MCh in WT SEN group was significantly lowered upon limonene treatment but no effect was observed in A_2AKO. Limonene also attenuated NECA-induced airway responsiveness in WT allergic mice with no effect being observed in A_2AKO groups. Differential BAL analysis showed that limonene reduced levels of eosinophils in allergic WT mice but not in A_2AKO. However, limonene reduced neutrophils in sensitized A_2AKO mice, suggesting that it may activate A_2B receptors as well. These data indicate that limonene-induced reduction in airway inflammation and airway reactivity occurs mainly via activation of A_2AAR but A_2B receptors may also play a supporting role.

Role of myeloid cells in the regulation of group 2 innate lymphoid cell-mediated allergic inflammation

Group 2 innate lymphoid cells (ILC2s) are an important component of the innate immune system that execute important effector functions at barrier surfaces, such as lung and skin. Like T helper type 2 cells, ILC2s are able to release high amounts of type 2 cytokines that are essential in inducing allergic inflammation and eliminating helminth infections. The past few years have contributed to our better understanding of the interactions between ILC2s and other cells of the immune system via soluble factors or in a cell-cell contact manner. Myeloid cells, including mononuclear leukocytes and polymorphonuclear leukocytes, are excellent sensors of tissue damage and infection and can influence ILC2 responses in the process of allergic inflammation. In this review, we summarize recent insights on how myeloid cell subsets regulate ILC2 activation with focus on soluble factors in the context of allergic inflammation.

Severe Eosinophilic Asthma

Asthma is a heterogeneous disease with varying severity. Severe asthma is a subject of constant research because it greatly affects patients’ quality of life, and patients with severe asthma experience symptoms, exacerbations, and medication side effects. Eosinophils, although at first considered insignificant, were later specifically associated with features of the ongoing inflammatory process in asthma, particularly in the severe case. In this review, we discuss new insights into the pathogenesis of severe asthma related to eosinophilic inflammation and the pivotal role of cytokines in a spectrum that is usually referred to as “T2-high inflammation” that accounts for almost half of patients with severe asthma. Recent literature is summarized as to the role of eosinophils in asthmatic inflammation, airway remodeling, and airway hypersensitivity. Major advances in the management of severe asthma occurred the past few years due to the new targeted biological therapies. Novel biologics that are already widely used in severe eosinophilic asthma are discussed, focusing on the choice of the right treatment for the right patient. These monoclonal antibodies primarily led to a significant reduction of asthma exacerbations, as well as improvement of lung function and patient quality of life.

Intervention of Orai1 Influences the Response of Nuocytes From Allergic Rhinitis Mice to IL-33

OBJECTIVE

Nuocytes are essential in innate type-2 immunity and contribute to the exacerbation of allergic rhinitis (AR). This study aimed to evaluate the intervention of Orai1 on the response of nuocytes from AR mice to interleukin (IL)-33.

METHODS

We established a murine model of AR. Nuocytes were obtained from the mouse nasal-associated lymphoid tissue. Then, we assessed expressions of Orai1, Ca²⁺ mean fluorescence intensity (MFI) in nuocytes, and their cellular response to mouse recombinant (rm) IL-33. After that, we administered rmlentivirus vectors (lenti) that encoded small hairpin RNA (shRNA) against ORAI1 (lenti-ORAI1) into nuocytes cultures and again evaluated Orai1 and Ca²⁺ MFI in nuocytes and their response to rmIL-33. Finally, we adoptively transferred nuocytes alone or nuocytes transfected by lenti or lenti-ORAI1 to AR models to investigate their roles during allergic inflammation.

RESULTS

We showed that Orai1 and Ca²⁺ MFI were upregulated in AR mice nuocytes. These cells were induced to produce more IL-5 and IL-13 by rmIL-33. However, the intervention of Orai1 by lenti-ORAI1 in nuocytes decreased Orai1 and Ca²⁺ MFI and reduced productions of aforementioned cytokines even after the administration of rmIL-33. Numbers of sneezing, nasal rubbing, and counts of eosinophils were all enhanced after the adoptive transfer of nuocytes. Concentrations of IL-5, IL-13, and IL-33 in the nasal lavage fluid (NLF) of allergic mice were also increased. However, the adoptive transfer of nuocytes transfected by lenti-ORAI1 decreased aforementioned parameters.

CONCLUSION

These findings show that the intervention of Orai1 in nuocytes influences the response of nuocytes to rmIL-33.

Role of angiotensin II type 1 (AT1) and type 2 (AT2) receptors in airway reactivity and inflammation in an allergic mouse model of asthma

Objective: Angiotensin II (Ang II) exerts its effects through two G-protein coupled receptors: angiotensin II type 1 receptors (AT1) and type 2 receptors (AT2). Both these receptor subtypes are poorly understood in asthma. In this study, we investigated effects of AT1 receptor antagonist losartan, novel AT2 receptor agonist novokinin and AT2 receptor antagonist PD 123319 in a mouse model of asthma. Methods: Mice were divided into control (CON) and allergen sensitized (SEN) groups. SEN was sensitized with ovalbumin (OVA) on days 1 and 6 (30 μg; i.p.), followed by 5% OVA aerosol challenge (days 11-13). Treatments included (a) losartan (SEN + LOS; 20 mg/kg i.p., day 14), (b) novokinin (SEN + NOV; 0.3 mg/kg i.p., day 14), and (c) PD 123319 (SEN + PD; 5 mg/kg i.p., day 14). Experiments for airway responsiveness, bronchoalveolar lavage, and tracheal ring reactivity using isolated organ bath were performed. Results: Airway responsiveness to methacholine (MCh) (48 mg/mL) was significantly higher in SEN (563.71 ± 40% vs. 294.3 ± 123.84 in CON). This response was potentiated in SEN + PD group (757 ± 30%; p < .05 compared to SEN). SEN + LOS (247.61 ± 86.85%) and SEN + NOV (352 ± 11%) had significantly lower response compared to SEN. SEN + LOS (26.22 ± 0.29%) and SEN + NOV (46.20 ± 0.76%) treatment significantly (p < .001) attenuated total cell count and eosinophils compared to SEN group (69.38 ± 1.5%), while SEN + PD (73.04 ± 0.69%) had highest number of eosinophils. Tracheal response to MCh was significantly higher in SEN group compared to controls, and this response was significantly lowered with the losartan and novokinin treatments. Conclusions: These data suggest that AT1 and AT2 receptors have opposite effects in modulating airway hyperresponsiveness and inflammation in asthma.

Bu-Shen-Yi-Qi formula ameliorates airway remodeling in murine chronic asthma by modulating airway inflammation and oxidative stress in the lung

Bu-Shen-Yi-Qi formula (BSYQF) could suppress chronic airway inflammation according to previous studies. However, there is relatively little direct experimental evidence to evaluate the effects of BSYQF treatment on airway remodeling in chronic asthma. Recent evidence suggests that oxidative stress is involved in airway inflammation and airway remodeling in chronic asthma. BSYQF which includes various of chemical components having antioxidant effects, could be beneficial in attenuating airway remodeling in chronic asthma. The purpose of this study was to elucidate the effect of BSYQF treatment on airway remodeling and investigate its potential mechanisms in chronic asthma. To develop the murine models of chronic asthma, BALB/c mice were sensitized and challenged to ovalbumin for 8 weeks. BSYQF (5, 10, 20 g raw herbs/kg body weight) or tiotropium bromide (0.1 mM) were administered orally and intranasal instillation, respectively. The effect of BSYQF on pulmonary inflammation and remodeling was evaluated. The parameters of oxidative stress in the lung were analyzed. BSYQF treatment reduced airway hyperresponsiveness (AHR), Th2 response including IL-4, IL-13, and OVA-specific IgE and IgG1, transforming growth factor-β (TGF-β), vascular endothelium growth factor (VEGF), airway inflammation and airway remodeling including smooth muscle thickening and peribronchial collagen deposition. As for oxidative stress, BSYQF treatment reduced reactive oxygen species (ROS), Malondialdehyde (MDA), NO, and the expression of inducible nitric oxide synthase (iNOS), but increased significantly glutathione (GSH) /Oxidized glutathione(GSSH) ratios in the lung, restored mitochondrial ultrastructural changes of bronchial epithelia and ATP levels in the lung. In summary, this study suggested that BSYQF treatment ameliorated airway remodeling and alleviated asthmatic features in chronic asthma models. Anti-inflammatory and antioxidant effect of BSYQF may explain why BSYQF has effects on preventing airway remodeling.

Hydro-Ethanolic Extract of Portulaca Oleracea Ameliorates Total and Differential WBC, Lung Pathology and Oxidative Biomarkers in Asthmatic Rats

The effects of Portulaca oleracea (P. oleracea; PO) on total and differential WBC count, and oxidant/antioxidant biomarkers in bronchoalveolar lavage fluid (BALF) as well as on lung pathology in asthmatic rats were examined. Rats were randomly divided into; control group (C), asthma group, asthma groups treated with either P. oleracea (rats that received PO 1, 2 and 4 mg/mL) or dexamethasone 1.25 μg/mL (D), (n = 8 in each group). Total and differential white blood cells (WBC) count, nitrite (NO₂), nitrate (NO₃), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and thiol levels in rats BALF were evaluated and lung pathological features were studied. Total WBC count, eosinophil, neutrophil and monocyte percentages, levels of NO₂, NO₃, MDA in the BALF and most pathological scores in the lung were increased but lymphocyte percentage, SOD, CAT and thiol levels were decreased in the BALF of asthmatic animals (p < 0.05 to p < 0.001). Treatment with P. oleracea significantly reduced total WBC, neutrophil, eosinophil, monocyte, NO₂, and NO₃, MDA, interstitial fibrosis, emphysema, interstitial inflammation and epithelial damage, but increased lymphocyte, SOD, CAT and thiol levels compared to asthma group (p < 0.05 to p < 0.001). Dexamethasone-treated rats also showed significant improvements in most parameters compared to asthma group (p < 0.05 to p < 0.001). Our results demonstrated the ameliorative effects of P. oleracea on total and differential WBC count and oxidant-antioxidant biomarkers levels in BALF as well as lung pathological features in asthmatic rats, which propose the usage of this extract as a preventive anti-inflammatory treatment against asthma.

Progress in the understanding of the pathology of allergic asthma and the potential of fruit proanthocyanidins as modulators of airway inflammation

Allergic asthma is a chronic inflammatory lung disease characterized by sensitization of the airways, and the development of immunoglobulin E antibodies, to benign antigens. The established pathophysiology of asthma includes recurrent lung epithelial inflammation, excessive mucus production, bronchial smooth muscle hyperreactivity, and chronic lung tissue remodeling, resulting in reversible airflow restriction. Immune cells, including eosinophils and the recently characterized type 2 innate lymphoid cells, infiltrate into the lung tissue as part of the inflammatory response in allergic asthma. It is well established that a diet high in fruits and vegetables results in a reduction of the risk of developing inflammatory diseases. Secondary plant metabolites, such as proanthocyanidins which are found in apples, blackcurrants, boysenberries, cranberries, and grapes, have shown promising results in reducing or preventing allergic asthma airway inflammation. Recent evidence has also highlighted the importance of microbiome-mediated metabolism of plant polyphenols in modulating the immune system. In this review, we will discuss advances in our understanding of the pathophysiology of allergic asthma, including the role of the microbiome in lung immune function, and how proanthocyanidins modulate the airway inflammation. We will highlight the potential of dietary proanthocyanidins to impact on allergic asthma and the immune system.

Immunomodulation of allergic response in children and adolescents: What we can learn from lymphatic filarial infection

BACKGROUND

Although it is well known that allergic diseases involve a strong Th2 immune response, with production of high levels of specific IgE allergen, knowledge on the association between filarial infection and allergies, among paediatric patients is scarce.

OBJECTIVE

To evaluate the allergic response patterns in cases of filarial infection by comparing peripheral eosinophils, total IgE levels, immediate hypersensitivity and cytokine levels in children and adolescents in Brazil.

METHODS

This was an exploratory study with three groups: (I) with filarial infection and without allergic diseases; (II) without filarial infection and with allergic diseases; and (III) without filarial infection and without allergic diseases. The prick test and specific IgE tests for aeroallergens were performed using five antigens. Peripheral eosinophils and total IgE were also evaluated. IL-4 and IL-5 were determined using whole-blood culture stimulated by three antigens.

RESULTS

Eosinophilia and elevated levels of total IgE (≥400IU/dl) were observed in all groups. The prick test was positive in 56.6% of the cases. Group I presented hypersensitive responses similar to the allergic disease groups. In the whole-blood culture stimulated by Dermatophagoides pteronyssinus, average IL-4 production did not differ significantly among the groups, but IL5 production resulting from stimulation was greater in the allergic disease groups (p<0.05).

CONCLUSIONS

The allergic response pattern in group with filarial infection was similar to that of the groups with and without allergic diseases, but the response to IL-5 in the culture stimulated by D. pteronyssinus was an exclusive characteristic of the allergic group.

Regulation of Eosinophil Recruitment and Activation by Galectins in Allergic Asthma

Eosinophils are differentiated granulocytes that are recruited from the bone marrow to sites of inflammation via the vascular system. Allergic asthma is characterized by the presence of large numbers of eosinophils in the lungs and airways. Due to their capacity to rapidly release inflammatory mediators such as cytokines, chemokines, growth factors, and cytotoxic granule proteins upon stimulation, eosinophils play a critical role in pro-inflammatory processes in allergen-exposed lungs. Identifying key players and understanding the molecular mechanisms directing eosinophil trafficking and recruitment to inflamed airways is a key to developing therapeutic strategies to limit their influx. Recent studies have brought to light the important role of glycans and glycan binding proteins in regulating recruitment of eosinophils. In addition to the role of previously identified eosinophil- and endothelial-expressed adhesion molecules in mediating eosinophil trafficking and recruitment to the inflamed airways, studies have also indicated a role for galectins (galectin-3) in this process. Galectins are mammalian lectins expressed by various cell types including eosinophils. Intracellularly, they can regulate biological processes such as cell motility. Extracellularly, galectins interact with β-galactosides in cell surface-expressed glycans to regulate cellular responses like production of inflammatory mediators, cell adhesion, migration, and apoptosis. Eosinophils express galectins intracellularly or on the cell surface where they interact with cell surface glycoconjugate receptors. Depending on the type (galectin-1, -3, etc.) and location (extracellular or intracellular, endogenous or exogenously delivered), galectins differentially regulate eosinophil recruitment, activation, and apoptosis and thus exert a pro- or anti-inflammatory outcome. Here, we have reviewed information pertaining to galectins (galectin-1, -3 -9, and -10) that are expressed by eosinophils themselves and/or other cells that play a role in eosinophil recruitment and function in the context of allergic asthma and their potential use as disease biomarkers or therapeutic targets for immunomodulation.

Blackcurrant anthocyanins modulate CCL11 secretion and suppress allergic airway inflammation

CCL11, a chemokine, is linked to the early development of airways eosinophilia in allergic asthma. Therefore, CCL11 production is a target for abrogating eosinophilic-driven airway inflammation. Blackcurrants are high in compounds that regulate inflammation, particularly anthocyanins. In this study, we investigated the effect of oral blackcurrant supplementation on allergen-induced eosinophilia and CCL11 production; we also profiled key compounds in blackcurrants that were linked to this effect. Ten milligram per kilogram (total anthocyanins) of a commercially available, anthocyanin-rich New Zealand "Ben Ard" blackcurrant extract ("Currantex 30") attenuated ovalbumin-induced inflammation, eosinophilia (by 52.45 ± 38.50%), and CCL11 production (by 48.55 ± 28.56%) in a mouse model of acute allergic lung inflammation. Ten blackcurrant polyphenolic extracts were also found to suppress CCL11 secretion by stimulated human lung epithelial cells in vitro. Correlation analysis identified potential blackcurrant polyphenolic anthocyanin constituents specifically delphinidins and cyanidins, involved in CCL11 suppression. Our findings show oral supplementation with New Zealand blackcurrant is effective in reducing lung inflammation, and highlight the potential benefit of developing cultivars with specific polyphenolic profiles for the creation of functional foods with desirable biological activity.

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.

Immune cells in liver regeneration

After partial hepatectomy, hepatocytes proliferate to restore mass and function of the liver. Macrophages, natural killer (NK) cells, natural killer T (NKT) cells, dendritic cells (DC), eosinophils, gamma delta T (γδT) cells, and conventional T cells, as well as other subsets of the immune cells residing in the liver control liver regeneration, either through direct interactions with hepatocytes or indirectly by releasing inflammatory cytokines. Here, we review recent progress regarding the immune cells in the liver and their functions during liver regeneration.

The Role and Immunobiology of Eosinophils in the Respiratory System: a Comprehensive Review

The eosinophil is a fully delineated granulocyte that disseminates throughout the bloodstream to end-organs after complete maturation in the bone marrow. While the presence of eosinophils is not uncommon even in healthy individuals, these granulocytes play a central role in inflammation and allergic processes. Normally appearing in smaller numbers, higher levels of eosinophils in the peripheral blood or certain tissues typically signal a pathologic process. Eosinophils confer a beneficial effect on the host by enhancing immunity against molds and viruses. However, tissue-specific elevation of eosinophils, particularly in the respiratory system, can cause a variety of short-term symptoms and may lead to long-term sequelae. Eosinophils often play a role in more commonly encountered disease processes, such as asthma and allergic responses in the upper respiratory tract. They are also integral in the pathology of less common diseases including eosinophilic pneumonia, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and drug reaction with eosinophilia and systemic symptoms. They can be seen in neoplastic disorders or occupational exposures as well. The involvement of eosinophils in pulmonary disease processes can affect the method of diagnosis and the selection of treatment modalities. By analyzing the complex interaction between the eosinophil and its environment, which includes signaling molecules and tissues, different therapies have been discovered and created in order to target disease processes at a cellular level. Innovative treatments such as mepolizumab and benralizumab will be discussed. The purpose of this article is to further explore the topic of eosinophilic presence, activity, and pathology in the respiratory tract, as well as discuss current and future treatment options through a detailed literature review.

The soluble guanylyl cyclase activator BAY 60-2770 inhibits murine allergic airways inflammation and human eosinophil chemotaxis

OBJECTIVES

Activators of soluble guanylyl cyclase (sGC) act preferentially in conditions of enzyme oxidation or haem group removal. This study was designed to investigate the effects of the sGC activator BAY 60-2770 in murine airways inflammation and human eosinophil chemotaxis.

METHODS

C57Bl/6 mice treated or not with BAY 60-2770 (1 mg/kg/day, 14 days) were intranasally challenged with ovalbumin (OVA). At 48 h, bronchoalveolar lavage fluid (BALF) was performed, and circulating blood, bone marrow and lungs were obtained. Human eosinophils purified from peripheral blood were used to evaluate the cell chemotaxis.

RESULTS

OVA-challenge promoted marked increases in eosinophil number in BAL, lung tissue, circulating blood and bone marrow, all of which were significantly reduced by BAY 60-2770. The IL-4 and IL-5 levels in BALF were significantly reduced by BAY 60-2770. Increased protein expression of iNOS, along with decreases of expression of sGC (α1 and β1 subunits) and cGMP levels were detected in lung tissue of OVA-challenged mice. BAY 60-2770 fully restored to baseline the iNOS and sGC subunit expressions, and cGMP levels. In human isolated eosinophils, BAY 60-2770 (1-5 μM) had no effects on the cGMP levels and eotaxin-induced chemotaxis; however, prior incubation with ODQ (10 μM) markedly elevated the BAY 60-2770-induced cyclic GMP production, further inhibiting the eosinophil chemotaxis.

CONCLUSIONS

BAY 60-2770 reduces airway eosinophilic inflammation and rescue the sGC levels. In human eosinophils under oxidized conditions, BAY 60-2770 elevates the cGMP levels causing cell chemotaxis inhibition. BAY 60-2770 may reveal a novel therapeutic target for asthma treatment.

Tbet Deficiency Causes T Helper Cell Dependent Airways Eosinophilia and Mucus Hypersecretion in Response to Rhinovirus Infection

Current understanding of adaptive immune, particularly T cell, responses to human rhinoviruses (RV) is limited. Memory T cells are thought to be of a primarily T helper 1 type, but both T helper 1 and T helper 2 memory cells have been described, and heightened T helper 2/ lessened T helper 1 responses have been associated with increased RV-induced asthma exacerbation severity. We examined the contribution of T helper 1 cells to RV-induced airways inflammation using mice deficient in the transcription factor T-Box Expressed In T Cells (Tbet), a critical controller of T helper 1 cell differentiation. Using flow cytometry we showed that Tbet deficient mice lacked the T helper 1 response of wild type mice and instead developed mixed T helper 2/T helper 17 responses to RV infection, evidenced by increased numbers of GATA binding protein 3 (GATA-3) and RAR-related orphan receptor gamma t (RORγt), and interleukin-13 and interleukin-17A expressing CD4+ T cells in the lung. Forkhead box P3 (FOXP3) and interleukin-10 expressing T cell numbers were unaffected. Tbet deficient mice also displayed deficiencies in lung Natural Killer, Natural Killer T cell and γδT cell responses, and serum neutralising antibody responses. Tbet deficient mice exhibited pronounced airways eosinophilia and mucus production in response to RV infection that, by utilising a CD4+ cell depleting antibody, were found to be T helper cell dependent. RV induction of T helper 2 and T helper 17 responses may therefore have an important role in directly driving features of allergic airways disease such as eosinophilia and mucus hypersecretion during asthma exacerbations.

Inundation of asthma target research: Untangling asthma riddles

Asthma is an inveterate inflammatory disorder, delineated by the airway inflammation, bronchial hyperresponsiveness (BHR) and airway wall remodeling. Although, asthma is a vague term, and is recognized as heterogenous entity encompassing different phenotypes. Targeting single mediator or receptor did not prove much clinical significant, as asthma is complex disease involving myriad inflammatory mediators. Asthma may probably involve a large number of different types of molecular and cellular components interacting through complex pathophysiological pathways. This review covers the past, present, and future therapeutic approaches and pathophysiological mechanisms of asthma. Furthermore, review describe importance of targeting several mediators/modulators and receptor antagonists involved in the physiopathology of asthma. Novel targets for asthma research include Galectins, Immunological targets, K ⁺ Channels, Kinases and Transcription Factors, Toll-like receptors, Selectins and Transient receptor potential channels. But recent developments in asthma research are very promising, these include Bitter taste receptors (TAS2R) abated airway obstruction in mouse model of asthma and Calcium-sensing receptor obliterate inflammation and in bronchial hyperresponsiveness allergic asthma. All these progresses in asthma targets, and asthma phenotypes exploration are auspicious in untangling of asthma riddles.

Toll-like receptor-mediated involvement of innate immune cells in asthma disease

BACKGROUND

Innate immune cells as the first line of defense are adept at recognizing and triggering appropriate response against various pathogens. Apart from the protective functions, the innate immunity plays an essential role in mediation of allergic responses. Dendritic cells (DCs) and airway epithelial cells (AECs) along with other innate cells such as granulocytes, natural killer cells (NKs), natural killer T cells (NKTs), and alternatively activated macrophages (AAMs) are able to orchestrate allergic responses, especially asthma. Chronic stimulation of TLRs by airway stimuli induces local inflammation which gradually results in the recruitment and settling of innate cells around airways.

SCOPE OF REVIEW

This review discusses how recruitment and accumulation of the inflammatory cells in the site of insult facilitate hypersensitivity reactions and initiate airway inflammation. We indicate that these cells are well equipped to highly sensitive receptors known as toll-like receptors (TLRs) making them fit to prime adaptive immune response. Based on emerging findings, we highlight the pivotal role of TLRs in regulation of innate cells function in the context of asthma disease.

MAJOR CONCLUSIONS

Stimulation of the TLRs of innate cells by allergens has been found to accelerate and regulate allergic airway inflammation. In fact, the sophisticated interaction between environmental allergens and TLRs leads to release of various pro-inflammatory mediators from innate cells supporting asthma development.

GENERAL SIGNIFICANCE

This review highlights that TLRs have a substantial role in priming innate cells and cytokine release, suggesting that the involvement of TLRs of innate immune cells can modulate the function of these cells in asthma disease.

Interaction Between Helminths and Toll-Like Receptors: Possibilities and Potentials for Asthma Therapy

Toll-like receptors (TLRs) are essential components of the innate immune system. They play an important role in the pathogenesis of allergic diseases, especially asthma. Since TLRs significantly orchestrate innate and adaptive immune response, their manipulation has widely been considered as a potential approach to control asthma symptoms. It is well established that helminths have immunoregulatory effects on host immune responses, especially innate immunity. They release bioactive molecules such as excretory-secretory (ES) products manipulating TLRs expression and signaling. Thus, given the promising results derived from preclinical studies, harnessing helminth-derived molecules affecting TLRs can be considered as a potential biological therapy for allergic diseases. Prospectively, the data that are available at present suggest that, in the near future, it is possible that helminth antigens will offer new therapeutic strategies and druggable targets for fighting allergic diseases. This review describes the interactions between helminths and TLRs and discusses the potential possibilities for asthma therapy. In this opinion paper, the authors aimed to review the updated literatures on the interplay between helminths, TLRs, and asthma with a view to proposing helminth-based asthma therapy.

Serum decoy receptor 3 is a biomarker for disease severity in nonatopic asthma patients

BACKGROUND/PURPOSE

Decoy receptor 3 (DcR3), a soluble receptor of the tumor necrosis factor receptor superfamily, is a pleiotropic immunomodulator. The aim of this study was to investigate serum DcR3 levels in atopic and nonatopic asthma patients.

METHODS

The serum DcR3 levels of 70 adults with asthma and 20 healthy controls were determined by enzyme-linked immunosorbent assay (ELISA). The asthma patients were divided into atopic and nonatopic subgroups, based on the presence or absence of immunoglobulin E (IgE) specific to allergen. Correlations between serum DcR3 levels and blood total-eosinophil counts, forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity (FVC), and Asthma Control Test (ACT) scores were analyzed.

RESULTS

The mean serum DcR3 level was significantly higher in asthma patients than in healthy controls (266.1 ± 60.6 pg/mL vs. 63.7 ± 21.9 pg/mL, p = 0.003), but there was no significant difference between the mean serum DcR3 level of asthma patients with atopy (37 patients) and patients without atopy (33 patients; 298.7 ± 111.2 pg/mL vs. 230.6 ± 38.5 pg/mL, p = 0.064). However, the serum DcR3 level was positively correlated with the total eosinophil count (r = 0.448, p = 0.012) and inversely correlated with the percentages of predicted FEV1, FEV1/FVC, and ACT score (r = 0.409, p = 0.018; r = -0.399, p = 0.021; and r = -0.505, p = 0.003, respectively) in nonatopic asthma patients, but not in atopic patients.

CONCLUSION

High serum DcR3 levels are associated with disease severity in nonatopic asthma patients, which suggests that DcR3 is a potential biomarker that can be used to predict the severity of nonatopic asthma.

Ethyl pyruvate attenuates murine allergic rhinitis partly by decreasing high mobility group box 1 release

High-mobility group box 1 (HMGB1) protein, a pro-inflammatory DNA-binding protein, meditates inflammatory responses through Toll-like receptor-4 signals and amplifies allergic inflammation by interacting with the receptor for advanced glycation end products. Previous studies have shown that HMGB1 is elevated in the nasal lavage fluids (NLF) of children suffering from allergic rhinitis (AR) and is associated with the severity of this disease. Furthermore, HMGB1 has been implicated in the pathogenesis of lower airway allergic diseases, such as asthma. Ethyl pyruvate (EP) has proven to be an effective anti-inflammatory agent for numerous airway diseases. Moreover, EP can inhibit the secretion of HMGB1. However, few studies have examined the effect of EP on AR. We hypothesized that HMGB1 plays an important role in the pathogenesis of AR and studied it using an AR mouse model. Forty BALB/c mice were divided into four groups: the control group, AR group, 50 mg/kg EP group, and 100 mg/kg EP group. The mice in the AR and EP administration groups received ovalbumin (OVA) sensitization and challenge, whereas those in the control group were given sterile saline instead of OVA. The mice in the EP administration group were given an intraperitoneal injection of EP 30 min before each OVA treatment. The number of nasal rubbings and sneezes of each mouse was counted after final treatment. Hematoxylin-eosin staining, AB-PAS staining, interleukin-4 and 13 in NLF, IgE, and the protein expression of HMGB1 were measured. Various features of the allergic inflammation after OVA exposure, including airway eosinophilia, Th-2 cytokine production, total IgE, and goblet cell hyperplasia were significantly inhibited by treatment with EP and the expression and release of HMGB1 were reduced after EP administration in a dose-dependent manner. These results indicate that HMGB1 is a potential therapeutic target of AR and that EP attenuates AR by decreasing HMGB1 expression.

Host lung immunity is severely compromised during tropical pulmonary eosinophilia: role of lung eosinophils and macrophages

Eosinophils play a central role in the pathogenesis of tropical pulmonary eosinophilia, a rare, but fatal, manifestation of filariasis. However, no exhaustive study has been done to identify the genes and proteins of eosinophils involved in the pathogenesis of tropical pulmonary eosinophilia. In the present study, we established a mouse model of tropical pulmonary eosinophilia that mimicked filarial manifestations of human tropical pulmonary eosinophilia pathogenesis and used flow cytometry-assisted cell sorting and real-time RT-PCR to study the gene expression profile of flow-sorted, lung eosinophils and lung macrophages during tropical pulmonary eosinophilia pathogenesis. Our results show that tropical pulmonary eosinophilia mice exhibited increased levels of IL-4, IL-5, CCL5, and CCL11 in the bronchoalveolar lavage fluid and lung parenchyma along with elevated titers of IgE and IgG subtypes in the serum. Alveolar macrophages from tropical pulmonary eosinophilia mice displayed decreased phagocytosis, attenuated nitric oxide production, and reduced T-cell proliferation capacity, and FACS-sorted lung eosinophils from tropical pulmonary eosinophilia mice upregulated transcript levels of ficolin A and anti-apoptotic gene Bcl2,but proapoptotic genes Bim and Bax were downregulated. Similarly, flow-sorted lung macrophages upregulated transcript levels of TLR-2, TLR-6, arginase-1, Ym-1, and FIZZ-1 but downregulated nitric oxide synthase-2 levels, signifying their alternative activation. Taken together, we show that the pathogenesis of tropical pulmonary eosinophilia is marked by functional impairment of alveolar macrophages, alternative activation of lung macrophages, and upregulation of anti-apoptotic genes by eosinophils. These events combine together to cause severe lung inflammation and compromised lung immunity. Therapeutic interventions that can boost host immune response in the lungs might thus provide relief to patients with tropical pulmonary eosinophilia.

p-STAT6, PU.1, and NF-κB are involved in allergen-induced late-phase airway inflammation in asthma patients

Background

Previous in vitro and animal studies demonstrated that transcription factors p-STAT6 and PU.1 are required to induce interleukin (IL)-9 secretion by T helper (Th) 9 cells. It is believed that n factor-kappaB (NF-κB) plays a role in eosinophil survival. The importance of these transcription factors in the pathogenesis of allergic asthma (AA) in humans is poorly understood. We evaluated p-STAT6 and PU.1 expression in peripheral blood Th9 cells and NF-κB expression in eosinophils during late-phase airway inflammation in AA patients.

Methods

Nineteen adults with AA and 14 adult healthy individuals (HI) were examined. Peripheral blood collected 24 h before (baseline) and 24 h after bronchial allergen challenge. CD4⁺ cells and eosinophils were isolated by high-density gradient centrifugation and magnetic separation. The percentage of Th9 cells and apoptotic eosinophils was estimated by flow cytometry. p-STAT6 and PU.1 expression was expressed as mean fluorescence intensity (MFI) in Th9 cells. NF-κB levels were expressed as MFI in peripheral blood eosinophils. Serum IL-9 and IL-5 levels were determined by enzyme-linked immunosorbent assay.

Results

At baseline, MFI of p-STAT6 and PU.1 in peripheral blood Th9 cells and MFI of NF-κB in eosinophils and, serum IL-5 and IL-9 levels were greater in AA patients (P < 0.05). Decreased eosinophil apoptosis was seen in the AA group compared with HI (P < 0.05). MFI of p-STAT6, PU.1, and NF-κB and serum levels of IL-5 and IL-9 were increased in the AA group 24 h after challenge compared with baseline (P < 0.05). In the AA group, a correlation between serum IL-9 and Th9 cells (r = 0.7, P = 0.001) and MFI of PU.1 (r = 0.6, P = 0.01) 24 h after bronchial allergen challenge was observed. A correlation between Th9 cells and MFI of p-STAT6 (r = 0.45, P = 0.03) as well as MFI of PU.1 (r = 0.5, P = 0.02) 24 h after challenge was only observed in AA patients. A correlation between the MFI of NF-κB and eosinophil apoptosis was observed in AA patients 24 h before (r = −0.46, P = 0.02) and after (r = −0.5, P = 0.02) challenge.

Discussions

p-STAT6 and PU.1 may be associated with Th9 cells and IL-9 production, whereas NF-κB and IL-5 may be associated with reduced eosinophil apoptosis in allergen-induced late-phase airway inflammation.

Trial registration

ClinicalTrials.gov NCT02214303

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0119-7) contains supplementary material, which is available to authorized users.

Maternal obesity alters immune cell frequencies and responses in umbilical cord blood samples

BACKGROUND

Maternal obesity is one of the several key factors thought to modulate neonatal immune system development. Data from murine studies demonstrate worse outcomes in models of infection, autoimmunity, and allergic sensitization in offspring of obese dams. In humans, children born to obese mothers are at increased risk for asthma. These findings suggest a dysregulation of immune function in the children of obese mothers; however, the underlying mechanisms remain poorly understood. The aim of this study was to examine the relationship between maternal body weight and the human neonatal immune system.

METHODS

Umbilical cord blood samples were collected from infants born to lean, overweight, and obese mothers. Frequency and function of major innate and adaptive immune cell populations were quantified using flow cytometry and multiplex analysis of circulating factors.

RESULTS

Compared to babies born to lean mothers, babies of obese mothers had fewer eosinophils and CD4 T helper cells, reduced monocyte and dendritic cell responses to Toll-like receptor ligands, and increased plasma levels of IFN-α2 and IL-6 in cord blood.

CONCLUSION

These results support the hypothesis that maternal obesity influences programming of the neonatal immune system, providing a potential link to increased incidence of chronic inflammatory diseases such as asthma and cardiovascular disease in the offspring.

γδT cells regulate chronic airway inflammation and development of airway remodelling

BACKGROUND

γδT cells play a crucial immunoregulatory role in the lung, maintaining normal airway tone and preventing hyperresponsiveness to innocuous allergen. During acute inflammatory episodes, γδT cells promote resolution of acute inflammation. However, their contribution to inflammation-associated airway remodelling remains unexplored. Here we investigate the effects of γδT cell blockade on established allergic airway inflammation and development of remodelling.

METHODS

Sensitised mice were exposed to prolonged ovalbumin challenge or continuous house-dust mite exposure to induce chronic inflammation and remodelling. Functional blocking anti-TCRδ antibody was administered therapeutically, and parameters of airway inflammation and remodelling were examined.

RESULTS

Therapeutic blockade of γδT cells prevented the typical resolution of acute airway inflammation characterised by elevated eosinophil and Th2 cell numbers. Moreover, the lung displayed exacerbated airway remodelling, typified by excess peribronchiolar collagen deposition.

CONCLUSIONS

These results demonstrate a unique role for γδT cells in constraining allergen-induced airway remodelling. Manipulating the γδT cell compartment may therefore contribute to strategies to prevent and treat remodelling.

The normative value of inflammatory cells in the nasal perfusate of Chinese adults: a pilot study

OBJECTIVE

To establish stable, well-accepted nasal perfusion and a normative value of classifying cells in the nasal perfusate of Chinese adults.

METHODS

A total of 500 healthy adults were divided into two groups of 250 people per group (group A, 16-30 years old and group B, 31-60 years old; male-to-female ratio, 1:1). All volunteers were non-smokers; they were irrigated with saline, and multiple inflammatory cells in the perfusate were analyzed.

RESULTS

Irrigation was successfully performed in 479 cases, a success rate of 95.80%. The types of inflammatory cells showed a skewed distribution. The median number and interquartile range (IQR) of eosinophils were 0 and 0.2, respectively. These values were 0.4 and 2.2, respectively, for neutrophils and 0 and 0, respectively, for both lymphocytes and macrophages. There was no significant difference between males and females (P>0.05). There was a significant difference in the numbers of neutrophils and lymphocytes in the different age groups (P=0.000), but there was no significant difference in the numbers of eosinophils and macrophages (P>0.05). The 95% unilateral upper limited values (UULVs) of eosinophils and neutrophils in the nasal perfusates were 2.99 and 14.94, respectively, for group A and 1.41 and 17.08 for group B. As a result, the total 95% UULVs of eosinophils and neutrophils in the nasal perfusate were 2.00 and 16.80.

CONCLUSIONS

We established stable, well-accepted nasal perfusions and normal values for classifying the cells in the nasal perfusate of Chinese adults; the normative values of the inflammatory cells in nasal perfusate are 2.00 for the 95% UULV of eosinophils and 16.80 for neutrophils. Age might be one of the factors affecting the cells in rhinitis.

Sex-response differences of immunological and histopathological biomarkers in gill of Prochilodus argenteus from a polluted river in southeast Brazil

The fish gill is in direct and standing contact with the immediate external environment and, therefore, is highly vulnerable to aquatic pollutants. In this study, Prochilodus argenteus were caught at two different points in São Francisco river. The first point is located near Três Marias dam, while the second is placed downstream the Abaeté river. Chemical approaches showed the presence of metals contamination in the first point. Thus, the main goal of this study was to investigate the possible toxic effects of these contaminants and the likely use of biomarkers on fish gills. Biometric data of length and weight of fish were obtained in order to calculate the condition factor as an organismal biomarker. The histological changes in gills and alterations in mucous and rodlet cells occurrence were detected microscopically and evaluated with quantitative analyses. Myeloperoxidase (MPO) and Eosinophil Peroxidase (EPO) were also assessed in fish gill. The analysis of the water and sediment samples revealed the presence of metals at the two points. As and Cd were detected at higher concentrations at point 1. The presence of lamellar cell hyperplasia, lamellar fusion, lamellar edema and inflammatory foci varied according to the point. Additionally, mucous and rodlet cells and MPO and EPO activities showed variability according to the environmental conditions. Furthermore, with exception of lamellar hyperplasia and eosinophil peroxidase activity, all others parameters showed sex-variation responses. At the first point, male fish showed a chronical inflammation in gills due to the lowest activity of MPO and EPO, as well as low occurrence of inflammatory foci and glycoprotein secretion by mucous cells, while female fish presented an opposite pattern of response to the same environmental conditions. Therefore, we suggest the use of such biomarkers in future monitoring of aquatic systems, taking into account the sex-variation responses.

Antiallergic and antiasthmatic effects of a novel enhydrazinone ester (CEE-1): inhibition of activation of both mast cells and eosinophils

Activation of mast cells and eosinophils is a fundamental process in the pathophysiology of allergic diseases. We have previously reported that the novel enhydrazinone ester CEE-1 (ethyl 4-phenylhydrazinocyclohex-3-en-2-oxo-6-phenyl-1-oate) possesses potent anti-inflammatory activity. We have now tested whether the compound also possesses antiallergic and antiasthmatic effects in vitro and in vivo. The compound significantly inhibited degranulation and leukotriene C4 (LTC4) release from activated human eosinophils, as well as IgE-dependent degranulation and LTC4 release from passively sensitized rat basophilic leukemia cells and bone marrow-derived mouse mast cells. In human eosinophils, the drug was more potent in inhibiting degranulation than LTC4 release {IC50 = 0.4 μM [confidence interval (CI): 0.1-0.9] versus 3.8 μM (CI: 0.9-8.3)}, whereas in mast cells the reverse was essentially the case. The drug did not affect stimulus-induced calcium transients in eosinophils but significantly inhibited early phosphorylation of extracellular signal-regulated kinases 1/2 and p38-mitogen-activated protein kinases (MAPK). In vivo, topical application of 4.5-15 mg/kg of the compound significantly inhibited allergen-induced passive cutaneous anaphylaxis in mice. Similarly, in the mouse asthma model, the intranasal administration of 6.5-12.5 mg/kg of the compound significantly inhibited bronchial inflammation and eosinophil accumulation in bronchial lavage fluid, as well as abolishing airway hyper-responsiveness to methacholine. These results show that CEE-1 inhibits the activation of both mast cells and eosinophils in vitro, probably by blocking MAPK-activation pathways, and that these effects are translated into antiallergic and antiasthmatic effects in vivo. The compound, therefore, has potential application in the treatment of asthma and other allergic diseases.

Eosinophilic oesophagitis: clinical presentation and pathogenesis

Eosinophilic oesophagitis (EoE) is an inflammatory disorder of the oesophagus which has become increasingly recognised over recent years, although it remains underdiagnosed in many centres. It is characterised histologically by a significant eosinophilic infiltration of the oesophageal mucosa (>15 eosinophils per high powered field), and clinically with features of oesophageal dysfunction such a dysphagia, food impaction, and proton pump inhibitor (PPI) resistant dyspepsia. Fibrosis and oesophageal remodelling may occur and lead to oesophageal strictures. An allergic predisposition is common in the EoE population, which appears to be primarily food antigen driven in children and aeroallergen driven in adults. Evidence suggests that the pathogenesis of EoE is due to a dysregulated immunological response to an environmental allergen, resulting in a T helper type 2 (Th2) inflammatory disease and remodelling of the oesophagus in genetically susceptible individuals. Allergen elimination and anti-inflammatory therapy with corticosteroids are currently the mainstay of treatment; however, an increasing number of studies are now focused on targeting different stages in the disease pathogenesis. A greater understanding of the underlying mechanisms resulting in EoE will allow us to improve the therapeutic options available.

Mitochondria in the center of human eosinophil apoptosis and survival

Eosinophils are abundantly present in most phenotypes of asthma and they contribute to the maintenance and exacerbations of the disease. Regulators of eosinophil longevity play critical roles in determining whether eosinophils accumulate into the airways of asthmatics. Several cytokines enhance eosinophil survival promoting eosinophilic airway inflammation while for example glucocorticoids, the most important anti-inflammatory drugs used to treat asthma, promote the intrinsic pathway of eosinophil apoptosis and by this mechanism contribute to the resolution of eosinophilic airway inflammation. Mitochondria seem to play central roles in both intrinsic mitochondrion-centered and extrinsic receptor-mediated pathways of apoptosis in eosinophils. Mitochondria may also be important for survival signalling. In addition to glucocorticoids, another important agent that regulates human eosinophil longevity via mitochondrial route is nitric oxide, which is present in increased amounts in the airways of asthmatics. Nitric oxide seems to be able to trigger both survival and apoptosis in eosinophils. This review discusses the current evidence of the mechanisms of induced eosinophil apoptosis and survival focusing on the role of mitochondria and clinically relevant stimulants, such as glucocorticoids and nitric oxide.