Activation of CD4+ T cells, increased TH2-type cytokine mRNA expression, and eosinophil recruitment in bronchoalveolar lavage after allergen inhalation challenge in patients with atopic asthma

Circulating level of CD4+ CD25+ FOXP3+ T cells in patients with chronic urticaria

BACKGROUND

CD4+ CD25+ T-regulatory (Treg) cells play critical roles in maintaining peripheral tolerance and preventing autoimmunity. As characteristics of Treg cells have not been precisely investigated in chronic urticaria (CU) yet, this study was performed.

OBJECTIVE

To determine the frequencies of circulating CD4+ CD25+ FOXP3+ T cells and serum levels of interleukin (IL)-10, transforming growth factor (TGF)-β, and IL-17 in patients with chronic autoimmune urticaria and chronic idiopathic urticaria compared to healthy controls.

METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from patients with CU and healthy controls. The frequency of CD4+ CD25+ T cells in PBMCs and expression levels of FOXP3 were detected by flow cytometry. The serum levels of IL-10, TGF-β, and IL-17 were measured by enzyme-linked immunosorbent assay.

RESULTS

A significant decrease in the percentage of circulating CD4+ CD25+ FOXP3+ T cells was detected in patients with CU, compared to control subjects. However, no significant difference was detected on the serum levels of IL-10, TGF-β, and IL-17 between patients with CU and control subjects.

CONCLUSIONS

This study demonstrated that the frequency of Treg cells in PBMCs was decreased in patients with CU. Further studies are needed to clarify the exact role of Treg cells in the pathogenesis of CU and factors regulating their function.

Attenuation of airway inflammation by simvastatin and the implications for asthma treatment: is the jury still out?

Although some studies have explained the immunomodulatory effects of statins, the exact mechanisms and the therapeutic significance of these molecules remain to be elucidated. This study not only evaluated the therapeutic potential and inhibitory mechanism of simvastatin in an ovalbumin (OVA)-specific asthma model in mice but also sought to clarify the future directions indicated by previous studies through a thorough review of the literature. BALB/c mice were sensitized to OVA and then administered three OVA challenges. On each challenge day, 40 mg kg⁻¹ simvastatin was injected before the challenge. The airway responsiveness, inflammatory cell composition, and cytokine levels in bronchoalveolar lavage (BAL) fluid were assessed after the final challenge, and the T cell composition and adhesion molecule expression in lung homogenates were determined. The administration of simvastatin decreased the airway responsiveness, the number of airway inflammatory cells, and the interleukin (IL)-4, IL-5 and IL-13 concentrations in BAL fluid compared with vehicle-treated mice (P<0.05). Histologically, the number of inflammatory cells and mucus-containing goblet cells in lung tissues also decreased in the simvastatin-treated mice. Flow cytometry showed that simvastatin treatment significantly reduced the percentage of pulmonary CD4⁺ cells and the CD4⁺/CD8⁺ T-cell ratio (P<0.05). Simvastatin treatment also decreased the expression of the vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 proteins, as measured in homogenized lung tissues (P<0.05) and human epithelial cells. The reduction in the T cell influx as a result of the decreased expression of cell adhesion molecules is one of the mechanisms by which simvastatin attenuates airway responsiveness and allergic inflammation. Rigorous review of the literature together with our findings suggested that simvastatin should be further developed as a potential therapeutic strategy for allergic asthma.

Atopy and the gastrointestinal tract--a review of a common association in unexplained gastrointestinal disease

In addition to diseases conventionally associated with atopy there is increasing recognition that atopy is also linked to a spectrum of gastrointestinal (GI) manifestations, including food allergy, primary eosinophilic GI disease, functional gastrointestinal disorders, gluten interactions, gastroesophageal reflux disease and inflammatory bowel disease. These associations may be underpinned by shared genetic susceptibilities, initiation of related immune pathways and common patterns of exposure to environmental cues, including allergen/pathogen encounters and variations in the composition of the intestinal microbiota. Further scrutiny of GI diseases with prominent allergic-type immune responses may yet redefine treatment paradigms for these common and important atopy-associated diseases. Looking forward, interventions by manipulation of the microbiota or host immune responses hold promise, but there is still room for further exploration of this novel field of host susceptibility, host-microbe interactions and atopy-associated GI diseases.

Comparisons on enhancing the immunity of fresh and dry Cordyceps militaris in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

The immunomodulatory capacities of fresh Cordyceps militaris (FCM) and dry Cordyceps militaris (DCM) were compared.

MATERIALS AND METHODS

In vivo immunomodulatory assay, different doses of FCM and DCM were orally administrated over a period of 15 days in a cyclophosphamide (CY) induced immunosuppression mice; in vitro testing, the spleen cells were extracted from healthy mice and treaded with CY, then cultured with different dose of FCM or DCM; the contents of Cordyceps militaris polysaccharide (CMP), cordycepin, adenosine, total polyphenol (TP) and total flavonoids (TF) in FCM and DCM were measured.

RESULTS

Our studys indicated that, FCM was significantly stronger than DCM on increasing the spleen and thymus indexes, spleen lymphocyte activity, macrophage function, and promoting the levels of IL-2, IFN-γ in vivo and in vitro. The contents of immunomodulatory CMP and TF in FCM were markedly higher than in DCM.

CONCLUSION

All these results suggested that FCM was superior to DCM on enhancing immunity.

Expression of lymphocyte cell surface markers in workers exposed to different respiratory hazards: biomarkers of occupational respiratory disease

This study was designed to evaluate the potential of flow cytometry to measure biomarkers of airways inflammation in the peripheral blood of two cohorts of workers reporting work related respiratory symptoms, who were exposed to different respiratory hazards. Nine bakers exposed to wheat flour and 10 glass bottle manufacturers exposed to a range of irritant chemicals were selected for study. Phenotypic and inducible cell surface markers were measured by flow cytometry. Results were compared with a control population of 58 volunteers reporting no respiratory problems. The bakers showed a significant increase above control values for cell types associated with inflammation; in particular CD3 CD4 cells p 0.005 and CD4 CD25 cells p 0.01 . In contrast, the workers reporting work related respiratory symptoms who were exposed to a range of irritant chemicals showed a different pattern of cell surface lymphocyte markers, with a significant decrease in the total T cell population p 0.05 . Comparison of results from a subset of smoking controls with the population of bakers who were all heavy smokers confirmed that the increase in CD3 CD4 cells and CD4 CD25 cells could not be ascribed to the effects of smoking alone. We have shown activation of helper T cells in the peripheral blood of bakers reporting work related respiratory symptoms consistent with the changes observed in mild to severe asthmatics. However, workers with similar symptoms who were exposed to irritant chemicals did not show this pattern of phenotypic or inducible cell surface markers, reflecting an absence of airways inflammation in these individuals. Our results suggest that flow cytometry may be of use as an objective test for detecting workers with airways inflammation to allow the identification of workers at risk of developing occupational asthma.

The association between asthma and Helicobacter pylori: a meta-analysis

OBJECTIVE

The severity and incidence of asthma have increased drastically in the developed nations of the world over the last decades. Currently, some evidences indicate an inverse association between Helicobacter pylori and asthma, but some studies did not get the same conclusion. To make this question clear, we systematically reviewed the published evidence for an association between H. pylori infection and asthma.

METHODS

Medline and SCI databases up to April 2012 were searched to identify studies that evaluated the association between H. pylori and asthma. Relevant publications were searched using the following keywords or synonyms: asthma or Helicobacter pylori. Methodologic quality was scored by using a standardized list of criteria, and meta-analysis was conducted to calculate crude odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

Nineteen studies met our inclusion criteria: nine cross-sectional studies, seven case-control studies, and three prospective cohort studies. The overall methodologic quality score was high. Pooled ORs for the association between asthma and H. pylori infection were 0.84 (95% CI: 0.74-0.96) in nine cross-sectional studies, 0.94 (95% CI: 0.79-1.12) in seven case-control studies, and 0.82 (95% CI: 0.53-1.27) in three cohort studies. The pooled OR for all included studies was 0.81 (95% CI: 0.72-0.91) in children and 0.88 (95% CI: 0.71-1.08) in adults.

CONCLUSIONS

We found a weak evidence for an inverse association between asthma and H. pylori infection both in children and in adults.

Review of the occupational exposure to isocyanates: Mechanisms of action

Polyurethanes are useful polymers in a large variety of technical and consumer products that are generally made from diisocyanates and polyols or similar compounds. Toluene diisocyanate (TDI), 4,4'-methylenediphenyl diisocyanate (MDI) and 1,6'-hexamethylene diisocyanate (HDI) are useful for polyurethane products. Isocyanates are reactive chemicals that can be handled without problems in manufacturing or technical environments. In general, consumers may only have contact with these chemicals on rare occasions. The objective of this study was to review the mechanisms of action of inhalation of isocyanates. This paper describes, in summary, the potential occupational exposure to isocyanates, the chemistry and reactivity of isocyanates, the results from genotoxicity studies, investigative toxicity studies, metabolism and results from epidemiology studies on isocyanate-exposed workers. The overall conclusion is that because humans are not exposed to high levels of respiratory isocyanate particles, concerns over the possible development of lung tumors should not be relevant. There are many mechanisms of action induced by isocyanates, but those entities are unclear. This is because these mechanisms act simultaneously and are complex.

Phenotypic characterization of lung macrophages in asthmatic patients: overexpression of CCL17

BACKGROUND

Studies with monocyte-derived macrophages (MDMs) and animal models have suggested a role for alternatively activated (M2) macrophages in asthmatic inflammation, but in vivo evidence for this phenotype in human asthma is lacking.

OBJECTIVE

To characterize the phenotype of lung macrophages from asthmatic patients in relation to disease severity and treatment.

METHODS

M2 biomarkers were first identified by using MDMs exposed to T(H)2 cytokines and then used to phenotype sputum and bronchoalveolar lavage (BAL) macrophages from 12 healthy control subjects, 12 patients with mild asthma, and 14 patients with moderate asthma and to assess the effects of corticosteroids and phosphatidylinositol 3-kinase (PI3K) inhibitors.

RESULTS

Sputum macrophages from asthmatic patients expressed significantly more CCL17 mRNA but less CD163 than macrophages from healthy subjects. However, none of the other M2 biomarkers were differentially expressed in asthmatic patients, and ex vivo BAL cells spontaneously produced similar amounts of M2 cytokines/chemokines (IL-10, CCL17, and CCL22). CCL17 mRNA overexpression correlated weakly but significantly with sputum eosinophilia (P = .0252) and was also observed in macrophages from patients with moderate asthma treated with inhaled steroids, suggesting relative insensitivity to inhibition by corticosteroids. The PI3K inhibitor LY294002 inhibited basal CCL17 release from BAL cells and IL-4-stimulated release from MDMs.

CONCLUSIONS

This study does not support the existence in human asthma of the full M2 phenotype described to date but points to upregulation of CCL17 in both patients with mild and those with moderate asthma, providing a further source for this ligand of CCR4(+) cells that contributes to airways inflammation. CCL17 expression is corticosteroid resistant but suppressed by PI3K enzyme inhibitors.

Cytokines and cytokine-specific therapy in asthma

Asthma is increasing in prevalence worldwide. It is characterized by typical symptoms and variable airway obstruction punctuated with episodes of worsening symptoms known as exacerbations. Underlying this clinical expression of disease is airway inflammation and remodeling. Cytokines and their networks are implicated in the innate and adaptive immune responses driving airway inflammation in asthma and are modulated by host-environment interactions. Asthma is a complex heterogeneous disease, and the paradigm of Th2 cytokine-mediated eosinophilic inflammation as a consequence of allergic sensitization has been challenged and probably represents a subgroup of asthma. Indeed, as attention has switched to the importance of severe asthma, which represents the highest burden both to the patient and health care provider, there is an increasing recognition of inflammatory subphenotypes that are likely to be driven by different cytokine networks. Interestingly, these networks may be specific to aspects of clinical expression as well as inflammatory cell profiles and therefore present novel phenotype-specific therapeutic strategies. Here, we review the breadth of cytokines implicated in the pathogenesis of asthma and focus upon the outcomes of early clinical trials conducted using cytokines or cytokine-blocking therapies.

Diospyros blancoi attenuates asthmatic effects in a mouse model of airway inflammation

Asthma is a complex disease linked to various pathophysiological events, including proteinase activity. In this study, we examined whether a Diospyros blancoi methanolic extract (DBE) exerts protective effects on allergic asthma in a murine asthma model. To investigate the specific role of DBE, we employed a murine model of allergic airway inflammation. BALB/c mice sensitized and challenged with ovalbumin (OVA) were orally administered 20 or 40 mg/kg DBE for 3 days during OVA challenge. DBE induced significant suppression of the number of OVA-induced total inflammatory cells, including eosinophils, macrophages, and lymphocytes, in bronchoalveolar lavage fluid (BALF). Moreover, treatment with DBE led to significant decreases in interleukin (IL)-4, IL-5, and eotaxin levels in BALF and OVA-specific immunoglobulin (Ig)E and IgG1 levels in serum. Histological examination of lung tissue revealed marked attenuation of allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. Additionally, DBE suppressed matrix metalloproteinase-9 activity and induced heme oxygenase-1 expression. The present findings collectively suggest that DBE exhibits anti-inflammatory activity in an airway inflammation mouse model, supporting its therapeutic potential for the treatment of allergic bronchial asthma.

Allergen challenge differentially affects the number of circulating monocyte subsets

Peripheral blood monocyte (PBM) subsets play different roles in inflammatory response and tissue remodelling. The aim of this study was to investigate how allergen challenge affects the number of circulating PBMs in Dermatophagoides pteronyssinus (Dp) allergic patients (Dp-APs). Among 34 Dp-APs challenged, in 22 patients significant bronchoconstriction was demonstrated [responders (Rs)], while in 12, only upper respiratory symptoms were seen [non-responders (NRs)]. Twelve healthy, non-atopic subjects were used as controls (HCs). Expression of CD14, CD16 and CCR4 was evaluated by flow cytometry on the whole-blood samples before (T(0) ), 6 h (T(6) ) and 24 h (T(24) ) after the challenge. Plasma concentrations of CCL2, CX3CL1 and CCL17 were evaluated using ELISA. At T(0) , the mean percentage of CD14++ CD16+ PBMs in Rs (35.4%; 95%CI 26.9-43.9%) was significantly greater than in HCs (14.6%; 95%CI 7.3-21.8%; P = 0.006) and in NRs (17.5%; 95%CI 9.6-25.4%; P = 0.001). The baseline number of CD14++ CD16+ PBMs correlated with airway hyper responsiveness (AHR) (r = -0.507; 95%CI -0.834 to -0.432, P < 0.001). At T(24) , the number of CD14++ CD16+ PBMs significantly decreased in Rs but not in NRs and the numbers inversely correlated with plasma CCL17 concentration. Changes in the number of circulating CD14++ CD16+ cells after Dp challenge correlated with AHR (r = 0.706, 95%CI 0.43-0.861; P < 0.001). In all subjects, the greatest expression of CCR4 was found on CD14++ CD16+ PBMs. Expansion of CD14++ CD16+ monocytes in the peripheral blood with subsequent mobilization of those cells after allergen challenge may facilitate the development of AHR in Dp-APs.

The association of ambient air pollution with airway inflammation in schoolchildren

The biologic mechanisms involved in airway inflammatory response to air pollution are not clearly understood. The authors conducted a longitudinal study to investigate whether exposure to ambient air pollutants affected inflammatory cells and mediators from nasal lavage in schoolchildren. Study participants were 100 elementary and middle-school students in New Taipei City, Taiwan. A structured respiratory health questionnaire was administered in September 2007, followed by monthly measurement of nasal inflammation from October 2007 to November 2009. During the study period, daily concentrations of air pollutants were obtained from the Environmental Protection Administration monitoring station and the Aerosol Supersite. Mixed-effects models were applied to examine the association between air pollution and nasal inflammatory cells and mediators, including percentages of neutrophils, eosinophils, and monocytes in lavaged cells and interleukin-8. A total of 824 measurements were obtained from 100 participants over a period of 10 months. The level of particulate matter with an aerodynamic diameter of 2.5 μm or less (PM(2.5)) was found to be associated with percentage of neutrophils (β = 3.45%, 95% confidence interval: 0.89, 6.01) and interleukin-8 level (β = 29.98 pg/mL, 95% confidence interval: 3.26, 56.69) in the nasal lavage on the day of exposure. In this longitudinal cohort study of schoolchildren, results indicated that exposure to PM(2.5) might induce nasal inflammation.

Short-term roxithromycin treatment attenuates airway inflammation via MAPK/NF-κB activation in a mouse model of allergic asthma

OBJECTIVE

We investigated whether roxithromycin reduces ovalbumin-specific allergic asthma symptoms in mice, and we further investigated the inhibitory mechanism of roxithromycin in ovalbumin-specific allergic asthma.

METHODS

Mice were divided into five groups (n = 10 for each): control group, roxithromycin-treated groups (5, 20 and 40 mg/kg) and ovalbumin-challenged group. We measured the recruitment of inflammatory cells into the bronchoalveolar lavage fluid (BALF) or the lung tissues by Kwik-Diff and hematoxylin and eosin (H&E) staining, goblet cell hyperplasia by alcian blue-periodic acid-Schiff (AB-PAS) staining, airway hyperresponsiveness (AHR) by whole-body plethysmograph chamber, cytokine and immunoglobulin E (IgE) levels by ELISA, and the activation of mitogen-activated protein (MAP) kinases and nuclear factor-kappa B (NF-κB) in the lung tissues by Western blotting.

RESULTS

Treatment with roxithromycin resulted in fewer inflammatory cells in the BALF and peribronchial areas, and decreased AHR, goblet cell hyperplasia, IgE levels and inflammatory cytokines, as well as MAP kinases and NF-κB activation, which are increased in lung tissues of mice with ovalbumin-induced allergic asthma.

CONCLUSIONS

Our data suggest that oral administration of roxithromycin suppresses ovalbumin-induced airway inflammation and AHR by regulating the inflammatory cytokines via MAP kinases/NF-κB pathway in inflammatory cells. Based on these results, we suggest that roxithromycin may be used as a therapeutic agent for allergy-induced asthma.

Inflammatory effects on human lung epithelial cells after exposure to diesel exhaust micron sub particles (PM₁.₀) and pollen allergens

Asthma is currently defined as a chronic inflammatory disease of the airway. Several evidence indicate that vehicle emissions in cities is correlated with the allergic respiratory diseases. In the present study, we evaluated in the A549 cells the production and release of IL-4, IL-5 and IL-13 after treatment with sub-micron PM(1.0) particles (PM(1.0)), Parietaria officinalis (ALL), and PM(1.0) + ALL together. Our data demonstrated that PM(1.0) + ALL together exhibited the greatest capacity to induce A549 cells to enhance the expression of IL-4 and IL-5 compared with the only PM(1.0) or ALL treatment. Interestingly, IL-13 that is necessary for allergen-induced airway hyper responsiveness, is increased in cells treated with PM(1.0) + ALL together, but is higher expressed when the cells are treated only with the allergen. Our data support the hypothesis that the urban environment damage the acinar lung units and activates cells of the immune system.

Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's βc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common βc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

CD44 is critical for airway accumulation of antigen-specific Th2, but not Th1, cells induced by antigen challenge in mice

CD44 is a cell adhesion molecule involved in lymphocyte infiltration of inflamed tissues. We previously demonstrated that CD44 plays an important role in the development of airway inflammation in a murine model of allergic asthma. In this study, we investigated the role of CD44 expressed on CD4(+) T cells in the accumulation of T-helper type 2 (Th2) cells in the airway using CD44-deficient mice and anti-CD44 monoclonal antibodies. Antigen-induced Th2-mediated airway inflammation and airway hyperresponsiveness (AHR) in sensitized mice were reduced by CD44-deficiency. These asthmatic responses induced by the transfer of antigen-sensitized splenic CD4(+) T cells from CD44-deficient mice were weaker than those from WT mice. Lack of CD44 failed to induce AHR by antigen challenge. Expression level and hyaluronic acid receptor activity of CD44, as well as Neu1 sialidase expression on antigen-specific Th2 cells, were higher than those on antigen-specific Th1 cells. Anti-CD44 antibody preferentially suppressed the accumulation of those Th2 cells in the airway induced by antigen challenge. Our findings indicate that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells, but not Th1 cells, in the airway and in the development of AHR induced by antigen challenge.

Current understanding of Th2 cell differentiation and function

Helper T cell (Th) has been identified as a critical immune cell for regulating immune response since 1980s. The type 2 helper Tcell (Th2), characterized by the production of interleukin-4 (IL-4), IL-5 and IL-13, plays a critical role in immune response against helminths invading cutaneous or mucosal sites. It also has a functional role in the pathophysiology of allergic diseases such as asthma and allergic diarrhea. Currently, most studies have shed light on Th2 cell function and behavior in specific diseases, such as asthma and helminthes inflammation, but not on Th2 cell itself and its differentiation. Based on different cytokines and specific behavior in recent research, Th2 cell is also regarded as new subtypes of T cell, such as IL-9 secreting T cell (Th9) and CXCR5(+) T follicular helper cells. Here, we will discuss the latest view of Th2 cell towards their function and the involvement of Th2 cell in diseases.

Effect of heat-inactivated kefir-isolated Lactobacillus kefiranofaciens M1 on preventing an allergic airway response in mice

In this study, we assessed the anti-asthmatic effects of heat-inactivated Lactobacillus kefiranofaciens M1 (HI-M1) and its fermented milk using different feeding procedures and at various dosage levels. The possible mechanisms whereby HI-M1 has anti-allergic asthmatic effects were also evaluated. Ovalbumin (OVA)-allergic asthma mice that have been orally administrated the HI-M1 samples showed strong inhibition of production of T helper cell (Th) 2 cytokines, pro-inflammatory cytokines, and Th17 cytokines in splenocytes and bronchoalveolar fluid compared to control mice. An increase in regulatory T cell population in splenocytes in the allergic asthma mice after oral administration of H1-M1 was also observed. In addition, all of the features of the asthmatic phenotype, including specific IgE production, airway inflammation, and development of airway hyperresponsiveness, were depressed in a dose-dependent manner by treatment. These findings support the possibility that oral feeding of H1-M1 may be an effective way of alleviating asthmatic symptoms in humans.

Psychological considerations of the child with asthma

Asthma, the most common chronic disease in children and adolescents in industrialized countries, is typified by airway inflammation and obstruction leading to wheezing, dyspnea, and cough. However, the effect of asthma does not end with pulmonary changes. Research has shown a direct link between asthma and stress and psychiatric illness, which if untreated results in heightened morbidity and effects on society. The link between asthma and psychiatric illness, however, is often underappreciated by many pediatric and child mental health professionals. This article reviews the diagnosis and treatment of asthma as well as the correlation between asthma and psychiatric illness in children in an effort to improve management and treatment strategies for this prevalent disease.

Anti-allergic Activity of Stem Bark of Myrica esculenta Buch.-Ham. (Myricaceae)

Allergic diseases, such as allergic asthma, are hypersensitivity reactions initiated by immunological mechanisms. Myrica esculenta (M. esculenta) is known traditionally in Ayurveda to possess anti-asthmatic activity. The present investigation was undertaken to evaluate the effect of crude extract of stem bark of M. esculenta (Family Myricaceae, commonly known as Kaiphal) on experimental allergic reactions. Experimental models studied were allergic pleurisy and vascular permeability induced by acetic acid in mice. Pretreatment with M. esculenta (75 mg/kg and 150 mg/kg, p.o.) significantly inhibited the eosinophil accumulation (P < 0.01) respectively in the pleural cavity. M. esculenta (75 and 150 mg/kg, p.o.) significantly inhibited the rise in plasma exudation (57.12% and 59.77%, P < 0.01) induced by acetic acid in mice. These findings demonstrate that the crude extract from the stem bark of M. esculenta possesses antiallergic activity. This activity may be mediated by reducing the release of mediators such as histamine, inhibition of mast cell degranulation, and inhibition of eosinophil accumulation thereby preventing the release of cytokines and chemokines.

Inhibition of house dust mite-induced allergic airways disease by antagonism of microRNA-145 is comparable to glucocorticoid treatment

BACKGROUND

Glucocorticoids are used as mainstay therapy for asthma, but some patients remain resistant to therapy. MicroRNAs (miRNAs) are important regulators of the immune system by promoting the catabolism of their target transcripts as well as attenuating their translation. The role of miRNA in regulating allergic inflammation remains largely unknown. Blocking miRNA function may provide a new nonsteroidal anti-inflammatory approach to treatment.

OBJECTIVES

To (1) determine the role of specific miRNAs in the regulation of hallmark features of allergic airways inflammation and (2) compare the efficacy of antagonizing miRNA function with that of steroid treatment.

METHODS

Mice were sensitized and then aeroallergen-challenged with house dust mite to induce allergic airways disease, and alterations in the expression of miRNAs were characterized. Next mice were treated with antagomirs that inhibited the function of specific miRNAs in the lung or treated with dexamethasone and inflammatory lesions, and airway hyperresponsiveness was measured.

RESULTS

miR-145, miR-21, and let-7b have been implicated in airway smooth muscle function, inflammation, and airways epithelial cell function, respectively. Inhibition of miR-145, but not miR-21 or lethal-7b, inhibited eosinophilic inflammation, mucus hypersecretion, T(H)2 cytokine production, and airway hyperresponsiveness. The anti-inflammatory effects of miR-145 antagonism were comparable to steroid treatment.

CONCLUSION

Our study highlights the importance of understanding the contribution of miRNAs to pathogenesis of human allergic disease and their potential as novel anti-inflammatory targets.

Pharmacokinetics and pharmacodynamics of mepolizumab, an anti-interleukin-5 monoclonal antibody

Mepolizumab is a fully humanized monoclonal antibody (IgG1/κ) targeting human interleukin-5 (IL-5), a key haematopoietin needed for eosinophil development and function. Mepolizumab blocks human IL-5 from binding to the α-chain of the IL-5 receptor complex on the eosinophil cell surface, thereby inhibiting IL-5 signalling. The pharmacokinetics of mepolizumab have been evaluated in clinical studies at doses of 0.05-10 mg/kg and at 250 mg, 750 mg and 1500 mg. Mepolizumab was eliminated slowly, with mean initial and terminal phase half-life values of approximately 2 and 20 days, respectively. Plasma clearance ranged from 0.064 to 0.163 mL/h/kg and steady-state volume of distribution ranged from 49 to 93 mL/kg. Pharmacokinetics were dose proportional and time independent. Estimates based on a two-compartment intravenous infusion model from patients with asthma or healthy subjects following single doses predicted mepolizumab plasma concentrations in multiple-dose studies involving patients with hypereosinophilic syndrome (HES), asthma or eosinophilic oesophagitis. The absolute bioavailability of mepolizumab was 64-75% following subcutaneous injection and 81% following intramuscular injection. Peripheral blood eosinophil levels decreased in healthy subjects and patients with HES, asthma, eosinophilic oesophagitis or atopic dermatitis after intravenous mepolizumab infusion and subcutaneous injection. Reductions in eosinophil counts in oesophagus, sputum, skin, bone marrow, nasal lavage fluid and/or bronchial mucosa after treatment with mepolizumab were observed in placebo-controlled studies in various indications. The relationship between percentage change from baseline in blood eosinophils and mepolizumab plasma concentrations was described by an indirect pharmacological response model. The estimated maximal decrease in eosinophil count was approximately 85% from baseline and the half-maximal inhibitory concentration (IC50) was approximately 0.45 μg/mL.

High-affinity IgE receptors on dendritic cells exacerbate Th2-dependent inflammation

The IgE-mediated and Th2-dependent late-phase reaction remains a mechanistically enigmatic and daunting element of human allergic inflammation. In this study, we uncover the FcεRI on dendritic cells (DCs) as a key in vivo component of this form of allergy. Because rodent, unlike human, DCs lack FcεRI, this mechanism could be revealed only by using a new transgenic mouse model with human-like FcεRI expression on DCs. In the presence of IgE and allergen, FcεRI(+) DCs instructed naive T cells to differentiate into Th2 cells in vitro and boosted allergen-specific Th2 responses and Th2-dependent eosinophilia at the site of allergen exposure in vivo. Thus, FcεRI on DCs drives the cascade of pathogenic reactions linking the initial allergen capture by IgE with subsequent Th2-dominated T cell responses and the development of late-phase allergic tissue inflammation.

Role of macrophage migration inhibitory factor in the Th2 immune response to epicutaneous sensitization

We examined the role of macrophage migration inhibitory factor (MIF) in the generation of the Th2 response using MIF-deficient mice in a model of epicutaneous sensitization to ovalbumin. Lymph node cells from sensitized MIF-deficient mice produce lower levels of Th2 cytokines after antigen challenge when compared to their wild-type counterparts. Sensitized mice lacking MIF show less pulmonary inflammation after intranasal antigen exposure. Mice deficient in CD74, the MIF receptor, also are unable to generate an inflammatory response to epicutaneous sensitization. Examination of the elicitation phase of the atopic response using DO11.10 OVA TCR transgenic animals shows that T cell proliferation and IL-2 production are strongly impaired in MIF-deficient T cells. This defect is most profound when both T cells and antigen-presenting cells are lacking MIF. These data suggest that MIF is crucial both for the sensitization and the elicitation phases of a Th2-type immune response in allergic disease.

IL-12-STAT4-IFN-gamma axis is a key downstream pathway in the development of IL-13-mediated asthma phenotypes in a Th2 type asthma model

IL-4 and IL-13 are closely related cytokines that are produced by Th2 cells. However, IL-4 and IL-13 have different effects on the development of asthma phenotypes. Here, we evaluated downstream molecular mechanisms involved in the development of Th2 type asthma phenotypes. A murine model of Th2 asthma was used that involved intraperitoneal sensitization with an allergen (ovalbumin) plus alum and then challenge with ovalbumin alone. Asthma phenotypes, including airway-hyperresponsiveness (AHR), lung inflammation, and immunologic parameters were evaluated after allergen challenge in mice deficient in candidate genes. The present study showed that methacholine AHR and lung inflammation developed in allergen-challenged IL-4-deficient mice but not in allergen-challenged IL-13-deficient mice. In addition, the production of OVA-specific IgG2a and IFN-gamma-inducible protein (IP)-10 was also impaired in the absence of IL-13, but not of IL-4. Lung-targeted IFN-gamma over-expression in the airways enhanced methacholine AHR and non-eosinophilic inflammation; in addition, these asthma phenotypes were impaired in allergen-challenged IFN-gamma-deficient mice. Moreover, AHR, non-eosinophilic inflammation, and IFN-gamma expression were impaired in allergen-challenged IL-12Rbeta2- and STAT4-deficient mice; however, AHR and non-eosinophilic inflammation were not impaired in allergen-challenged IL-4Ralpha-deficient mice, and these phenomena were accompanied by the enhanced expression of IL-12 and IFN-gamma. The present data suggest that IL-13-mediated asthma phenotypes, such as AHR and non-eosinophilic inflammation, in the Th2 type asthma are dependent on the IL-12-STAT4-IFN-gamma axis, and that these asthma phenotypes are independent of IL-4Ralpha-mediated signaling.

Proteomic Analysis of Anti-inflammatory Effects of a Kampo (Japanese Herbal) Medicine "Shoseiryuto (Xiao-Qing-Long-Tang)" on Airway Inflammation in a Mouse Model

Effects of a Kampo (Japanese herbal) medicine "shoseiryuto (SST, xiao-qing-long-tang in Chinese)", which has been used for the treatment of allergic bronchial asthma clinically, were examined on ovalbumin (OVA)-sensitized allergic airway inflammation model (i.e., bronchial asthma) in a mouse. When SST was orally administered at 0.5 g kg(-1) day(-1) from day 1 to 6 after OVA inhalation, SST reduced the inflammation in lung tissue, the number of eosinophils and the OVA-specific immunoglobulin E (IgE) antibody titer in bronchoalveolar lavage (BAL) fluids at 7 days after the OVA inhalation. SST also reduced the airway hyperreactivity at 6 days after the OVA inhalation. Proteomic analysis with the agarose two-dimensional electrophoresis showed that the expression of spectrin α2 was reduced in the lung tissue of OVA-sensitized mice and SST recovered the expression. Western blot and immunohistochemical analyses of lung tissue also confirmed this result. When prednisolone was orally administered at 3 mg kg(-1) day(-1) from day 1 to 6 after OVA inhalation, the inflammation in lung tissue, the number of eosinophils in BAL fluids and airway hyperreactivity were reduced in the OVA-sensitized mice. However, prednisolone did not reduce the OVA-specific IgE antibody titer in BAL fluids and did not recover the expression of spectrin α2 in lung tissue. These results suggest that at least a part of action mechanism of SST against OVA-sensitized allergic airway inflammation in a mouse model is different from that of prednisolone.

The role of toll-like receptors in acute and chronic lung inflammation

By virtue of its direct contact with the environment, the lung is constantly challenged by infectious and non-infectious stimuli that necessitate a robust yet highly controlled host response coordinated by the innate and adaptive arms of the immune system. Mammalian Toll-like receptors (TLRs) function as crucial sentinels of microbial and non-infectious antigens throughout the respiratory tract and mediate host innate immunity. Selective induction of inflammatory responses to harmful environmental exposures and tolerance to innocuous antigens are required to maintain tissue homeostasis and integrity. Conversely, dysregulated innate immune responses manifest as sustained and self-perpetuating tissue damage rather than controlled tissue repair. In this article we review aspects of Toll-like receptor function that are relevant to the development of acute lung injury and chronic obstructive lung diseases as well as resistance to frequently associated microbial infections.

MicroRNAs in inflammatory lung disease--master regulators or target practice?

MicroRNAs (miRNAs) have emerged as a class of regulatory RNAs with immense significance in numerous biological processes. When aberrantly expressed miRNAs have been shown to play a role in the pathogenesis of several disease states. Extensive research has explored miRNA involvement in the development and fate of immune cells and in both the innate and adaptive immune responses whereby strong evidence links miRNA expression to signalling pathways and receptors with critical roles in the inflammatory response such as NF-κB and the toll-like receptors, respectively. Recent studies have revealed that unique miRNA expression profiles exist in inflammatory lung diseases such as cystic fibrosis, chronic obstructive pulmonary disease, asthma, idiopathic pulmonary fibrosis and lung cancer. Evaluation of the global expression of miRNAs provides a unique opportunity to identify important target gene sets regulating susceptibility and response to infection and treatment, and control of inflammation in chronic airway disorders. Over 800 human miRNAs have been discovered to date, however the biological function of the majority remains to be uncovered. Understanding the role that miRNAs play in the modulation of gene expression leading to sustained chronic pulmonary inflammation is important for the development of new therapies which focus on prevention of disease progression rather than symptom relief. Here we discuss the current understanding of miRNA involvement in innate immunity, specifically in LPS/TLR4 signalling and in the progression of the chronic inflammatory lung diseases cystic fibrosis, COPD and asthma. miRNA in lung cancer and IPF are also reviewed.

IL-2 and IL-4 stimulate MEK1 expression and contribute to T cell resistance against suppression by TGF-beta and IL-10 in asthma

The T cell-driven airway inflammation in chronic asthma is uninhibited and sustained. We examined the resistance of T cells from asthmatic patients against suppression by TGF-β, IL-10 and glucocorticoids and explored its signaling mechanism. CD4(+)CD25(-) T cells from allergic asthmatic subjects demonstrated increased TCR-stimulated proliferation as compared with healthy and chronic obstructive pulmonary disease controls. This proliferation was resistant to inhibition by TGF-β, IL-10, and dexamethasone and to anergy induction. CD4 T cells from asthmatic patients, but not chronic obstructive pulmonary disease, allergic rhinitis, and healthy subjects, showed increased expression of MEK1, heightened phosphorylation of ERK1/2, and increased levels of c-Fos. IL-2 and IL-4 stimulated the expression of MEK1 and c-Fos and induced T cell resistance. The inhibition of MEK1 reversed, whereas induced expression of c-Fos and JunB promoted T cell resistance against TGF-β- and IL-10-mediated suppression. We have uncovered an IL-2- and IL-4-driven MEK1 induction mechanism that results in heightened ERK1/2 activation in asthmatic T cells and make them resistant to certain inhibitory mechanisms.

Epinephrine-primed murine bone marrow-derived dendritic cells facilitate production of IL-17A and IL-4 but not IFN-γ by CD4+ T cells

Sympathetic activation leading to the release of epinephrine and norepinephrine, is known as an important regulatory circuit related to immune-mediated diseases. However, questions still remain on the behavior of antigen presenting cells (APC) dictated by stress-induced sympathetic neurotransmitters. The purpose of this study was to examine the fate of bone marrow-derived dendritic cell (BMDC)-associated influences on resting CD4(+) T cell activation. We hypothesize that pre-exposure of dendritic cells (DCs) can modify the intensity of cytokine production, leading to preference in resting CD4(+) T cell activation. BMDCs were pre-treated with epinephrine for 2h followed by subsequent treatment of lipopolysaccharide (LPS). Subsequently, BMDCs were cocultured with purified CD4(+) T cells from mouse spleen in the absence or presence of anti-CD3 stimulation in epinephrine-free media. Epinephrine pre-treatment enhanced surface expression of MHCII, CD80 and CD86. Quantitative RT-PCR showed that epinephrine pre-treatment induced a significant transcriptional decrease of IL-12p40 and a significant increase of IL-12p35 and IL-23p19. In addition, β2-adrenergic-blockade was shown to reverse these effects. Epinephrine pre-treatment also induced a significant decrease of IL-12p70 and a significant increase of IL-23 and IL-10 cytokine production. Importantly, these changes corresponded with increased IL-4 and IL-17A, but not IFN-g cytokine production by CD4(+) T cells in a b2-adrenergic receptor-dependent manner. These results suggest that exposure to stress-derived epinephrine dictates dendritic cells to generate a dominant Th2/Th17 phenotype in the context of subsequent exposure to a pathogenic stimulus.

The effect of Helicobacter pylori on asthma and allergy

Current evidence indicates an inverse association between Helicobacter pylori and asthma and allergy. H. pylori is a Gram-negative bacterium which represents the major cause of peptic ulcer and gastric cancer, and preferentially elicits a T helper (Th)-1 response. Many H. pylori factors, such as the neutrophil-activating factor of H. pylori (HP-NAP), are able to drive Th-1 polarization and to display a powerful inhibition of allergic Th-2 response. This article proposes an overview of the actual knowledge about the effects of H. pylori on asthma and allergy. Special attention has been drawn to HP-NAP as a potential novel strategy for the prevention and treatment of asthma and atopy.

The role of the T cell in asthma

Since the initial detection of T(H)2 cytokines in asthmatic airways, our understanding of the complexity of T-cell subtypes and flexibility and of the potential role of airway structural cells in the immunopathology of asthma has increased. Cytokines derived from airway epithelium, including IL-25, IL-33, and thymic stromal lymphopoietin, might be important drivers of T(H)2-type inflammation in asthma. The balance between effector T(H)2 cells and suppressive regulatory T cells is skewed toward a proinflammatory T(H)2 response in atopy and asthma, and there is much interest in how to redress this equilibrium. Novel T-cell subsets, including T(H)17, T(H)9, and T(H)22, have been described, although their role in asthma remains unclear. Other T cells, including natural killer T cells, γδ T cells, and CD8 T cells, have also been implicated in asthma, although their importance remains to be confirmed. Therapeutic strategies aimed at T(H)2 cytokines are beginning to bear fruit in patients with asthma, although like many biologic agents, these might need specific targeting at subgroups of patients. Strategies directed specifically at the T cells are currently being evaluated, including novel forms of allergen immunotherapy. T cells remain an exciting potential target for new treatments in patients with asthma.

Pathogens and immunologic memory in asthma: what have we learned?

Animal models and clinical studies of asthma have generated important insights into the first effector phase leading to the development of allergic airway disease and bronchial hyper-reactivity. In contrast, mechanisms related to asthma chronicity or persistence are less well understood. The CD4(+) T-helper 2 lymphocytes are known initiators of the inflammatory response associated with asthma. There is now increasing evidence that memory T-cells, sensitized against allergenic, occupational or viral antigens, are also involved in the persistence of asthma. Additionally, the role of pathogens in asthma has been linked to both the initial susceptibility to and flares of this disease. This review will discuss the potential links between infection and asthma, the role of the memory T-cells in asthma, and the potential mechanisms by which these factors interact to lead to the development and/or persistence of asthma.

Crosstalk between T cells and bronchial fibroblasts obtained from asthmatic subjects involves CD40L/alpha 5 beta 1 interaction

BACKGROUND

Allergic asthma is characterized by infiltration of inflammatory cells into the airways. T cell-derived cytokines regulate both airway inflammation and remodelling. In the human airways, T cell-fibroblast interactions may have a role in regulating inflammation and remodelling.

OBJECTIVES

To evaluate the effect of bronchial fibroblast-T cell interaction on profibrogenic cytokine release and determine the nature of the molecules involved in this interaction.

METHODS

Human bronchial fibroblasts obtained from healthy and asthmatic donors were co-cultured with purified T cells derived from peripheral blood of the same subjects. IL-6 mRNA and protein levels were measured by real time PCR and ELISA. CD40, CD40L and alpha 5 beta 1 were evaluated by flow cytometry. Bronchial fibroblasts were stimulated with rsCD40L. Neutralisation was performed using neutralizing antibodies anti-CD40L and anti-alpha 5.

RESULTS

Contact of T cells with bronchial fibroblasts up-regulated IL-6 at both gene and protein levels. This effect was significantly higher in fibroblasts from asthmatics than those from controls. Blocking CD40L and alpha 5 beta 1 integrin showed a significant inhibition of IL-6 expression in asthmatics but not in healthy controls. Stimulation of fibroblasts with recombinant soluble CD40L up-regulated IL-6 production in asthmatics but not in controls. Adhesion to fibronectin, a alpha 5 beta 1 integrin ligand, is increased in fibroblasts from asthmatics compared to fibroblasts from controls.

CONCLUSION

These results showed that interaction of bronchial fibroblasts with T cells increases the production of profibrogenic cytokine IL-6. In asthmatic condition this interaction involves CD40L/alpha 5 beta 1. These results suggest that T cells and structural cells crosstalk in asthma may maintain local mucosal inflammation.

A review of treatment with mepolizumab, an anti-IL-5 mAb, in hypereosinophilic syndromes and asthma

The hypereosinophilic syndromes (HESs) are a heterogeneous group of diseases characterized by peripheral blood eosinophilia with end-organ damage and varying in severity from nonspecific symptoms to life-threatening. Treatment objectives are a safe reduction of blood and tissue eosinophil levels and prevention of eosinophil-mediated tissue damage. Current treatment of patients with HESs, who lack the FIP-1-like 1-platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) fusion gene, is mainly systemic corticosteroid therapy. Eosinophil development from hematopoietic progenitor cells is regulated by IL-5, which influences maturation, differentiation, mobilization, activation, and survival. Consequently, inhibiting IL-5 is a logical therapeutic objective for patients with HESs or selected patients with asthma. Mepolizumab is a fully humanized anti-IL-5 monoclonal IgG(1) antibody that binds to free IL-5 with high affinity and specificity to prevent IL-5 from associating with the IL-5 receptor complex alpha-chain on the surface of eosinophils. In clinical trials with patients with HESs, mepolizumab reduced blood eosinophil counts and the maintenance corticosteroid dose and had no major safety concerns. Mepolizumab reduced airway and blood eosinophils and prevented asthma exacerbations. Thus, mepolizumab may be effective for long-term treatment of patients with selected eosinophilic disorders.

Psychological considerations of the child with asthma

Asthma, the most common chronic disease in children and adolescents in industrialized countries, is typified by airway inflammation and obstruction leading to wheezing, dyspnea, and cough. However, the effect of asthma does not end with pulmonary changes. Research has shown a direct link between asthma and stress and psychiatric illness, which if untreated results in heightened morbidity and effects on society. The link between asthma and psychiatric illness, however, is often underappreciated by many pediatric and child mental health professionals. This article reviews the diagnosis and treatment of asthma as well as the correlation between asthma and psychiatric illness in children in an effort to improve management and treatment strategies for this prevalent disease.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.

New immune pathways from chronic post-viral lung disease

To better understand the immunopathogenesis of chronic inflammatory lung disease, we established a mouse model of disease that develops after respiratory viral infection. The disease that develops in this model is similar to chronic obstructive lung disease in humans. Using this model we have characterized two distinct phases in the chronic disease process. The first phase appears at three weeks after viral infection and depends on type I interferon‐dependent expression and then subsequent activation of the high‐affinity IgE receptor (FcɛRI) on conventional lung dendritic cells, which in turn recruit IL‐13‐producing CD4⁺ T cells to the lower airways. The second phase becomes maximal at seven weeks after infection and depends on invariant natural killer T (iNKT) cells and lung macrophages. Cellular cross‐talk relies on interactions between the semi‐invariant Vα14Jα18 T‐cell receptor on lung iNKT cells and CD1d on macrophages as well as iNKT cell‐derived IL‐13 and IL‐13 receptor on macrophages. These interactions drive macrophages to a pattern of alternative activation and overproduction of IL‐13. This innate immune axis is also activated in patients with chronic obstructive lung disease, as evidenced by increased numbers of iNKT cells and IL‐13‐producing alternatively activated macrophages marked by chitinase 1 production. Together the findings identify two new immune pathways responsible for early and late phases of chronic inflammatory lung disease in experimental and clinical settings. These findings extend our understanding of the complex mechanisms that underlie chronic obstructive lung disease and provide useful targets for diagnosis and therapy of this common disorder.

The Clinical Application of Ozonetherapy

The reader may be eager to examine in which diseases ozonetherapy can be proficiently used and she/he will be amazed by the versatility of this complementary approach (Table 9 1). The fact that the medical applications are numerous exposes the ozonetherapist to medical derision because superficial observers or sarcastic sceptics consider ozonetherapy as the modern panacea. This seems so because ozone, like oxygen, is a molecule able to act simultaneously on several blood components with different functions but, as we shall discuss, ozonetherapy is not a panacea. The ozone messengers ROS and LOPs can act either locally or systemically in practically all cells of an organism. In contrast to the dogma that “ozone is always toxic”, three decades of clinical experience, although mostly acquired in private clinics in millions of patients, have shown that ozone can act as a disinfectant, an oxygen donor, an immunomodulator, a paradoxical inducer of antioxidant enzymes, a metabolic enhancer, an inducer of endothelial nitric oxide synthase and possibly an activator of stem cells with consequent neovascularization and tissue reconstruction.

Increased vascular permeability precedes cellular inflammation as asthma control deteriorates

BACKGROUND

Airway microcirculation is abnormal in asthma but the role of vascular changes in asthma deteriorations remains poorly defined. We prospectively assessed the vascular changes accompanying worsening of asthma control by using an inhaled corticosteroid (ICS) dose-reduction model.

OBJECTIVES

To evaluate airway vascularity, vascular permeability and expression of vascular endothelial growth factor (VEGF) in early asthma deterioration induced by ICS back-titration.

METHODS

Twenty mild-to-moderate persistent symptomatic asthmatics on low-to-moderate ICS were recruited and treated with 4 weeks of high-dose fluticasone propionate (1000 microg/day) to achieve symptom control. This was followed by dose reduction to half of the pre-study doses for 4-8 weeks until the symptoms began to return. Endobronchial biopsy and bronchoalveolar lavage (BAL) samples were obtained after both treatment periods.

RESULTS

Vascularity as measured by the number and size of blood vessels, as well as VEGF expression did not change following ICS reduction. Even on high-dose ICS, perivascular albumin staining and BAL microalbumin levels in asthmatic subjects, as markers of permeability, were elevated when compared with normal subjects and both further increased significantly after ICS reduction. There was a significant association between changes in vascular leakiness and clinical deterioration. Increases in airway albumin correlated with previously reported increases in airway wall infiltration with T lymphocytes.

CONCLUSIONS

Our results suggest that airway vascular leakage is a major pathophysiologic feature of early asthma deterioration, occurring before recrudescence of cellular inflammation.

Antagonism of microRNA-126 suppresses the effector function of TH2 cells and the development of allergic airways disease

Allergic asthma is an inflammatory disease of the lung characterized by abnormal T helper-2 (T(H)2) lymphocyte responses to inhaled antigens. The molecular mechanisms leading to the generation of T(H)2 responses remain unclear, although toll-like receptors (TLRs) present on innate immune cells play a pivotal role in sensing molecular patterns and in programming adaptive T cell responses. Here we show that in vivo activation of TLR4 by house dust mite antigens leads to the induction of allergic disease, a process that is associated with expression of a unique subset of small, noncoding microRNAs. Selective blockade of microRNA (miR)-126 suppressed the asthmatic phenotype, resulting in diminished T(H)2 responses, inflammation, airways hyperresponsiveness, eosinophil recruitment, and mucus hypersecretion. miR-126 blockade resulted in augmented expression of POU domain class 2 associating factor 1, which activates the transcription factor PU.1 that alters T(H)2 cell function via negative regulation of GATA3 expression. In summary, this study presents a functional connection between miRNA expression and asthma pathogenesis, and our data suggest that targeting miRNA in the airways may lead to anti-inflammatory treatments for allergic asthma.

Activin and transforming growth factor-beta signaling pathways are activated after allergen challenge in mild asthma

BACKGROUND

Both transforming growth factor (TGF)-beta(1) and activin-A have been implicated in airway remodeling in asthma, but the modulation of their specific signaling pathways after disease activation remains undefined.

OBJECTIVE

To define the expression kinetics of TGF-beta(1), activin-A ligands, and follistatin (a natural activin inhibitor), their type I and type II receptors (activin-like kinase[ALK]-1, ALK-5, ALK-4, TbetaRII, and ActRIIA/RIIB) and activation of signaling (via phosphorylated (p) Smad2), in the asthmatic airway after allergen challenge.

METHODS

Immunohistochemistry was performed on bronchial biopsies from 15 mild atopic patients with asthma (median age, 25 years; median FEV(1)% predicted, 97%) at baseline and 24 hours after allergen inhalation. Functional effects of activin-A were evaluated by using cultured normal human bronchial epithelial (NHBE) cells.

RESULTS

pSmad2(+) epithelial cells increased at 24 hours (P = .03), and pSmad2 was detected in submucosal cells. No modulation of activin-A, follistatin, or TGF-beta(1) expression was demonstrated. Activin receptor(+) cells increased after allergen challenge: ALK-4 in epithelium (P = .04) and submucosa (P = .04), and ActRIIA in epithelium (P = .01). The TGF-beta receptor ALK-5 expression was minimal in the submucosa at baseline and after challenge and was downregulated in the epithelium after challenge (P = .02), whereas ALK-1 and TbetaRII expression in the submucosa increased after allergen challenge (P = .03 and P = .004, respectively). ALK-1 and ALK-4 expression by T cells was increased after allergen challenge. Activin-A induced NHBE cell proliferation, was produced by NHBE cells in response to TNF-alpha, and downregulated TNF-alpha and IL-13-induced chemokine production by NHBE cells.

CONCLUSION

Both TGF-beta and activin signaling pathways are activated on allergen provocation in asthma. Activin-A may contribute to resolution of inflammation.

Novel biomarkers in asthma: chemokines and chitinase-like proteins

PURPOSE OF REVIEW

Allergic asthma is a frequent lung disease in Western civilizations and is characterized by airway inflammation and tissue remodeling. Without early diagnosis and specific treatment, asthma results in a loss of lung function, impaired quality of life and the risk to die from uncontrolled asthma attacks. Thus, there is a need for specific biomarkers to detect asthma as soon as possible and to initiate the correct clinical treatment.

RECENT FINDINGS

Recent studies have highlighted the potential role of the chemokine (C-C motif) ligand 17 and the chitinase-like protein YKL-40 as novel biomarkers in asthma. Patient studies suggest that these proteins could be useful to identify asthmatics, to characterize disease severity or both in patients with asthma. Functional studies indicate that these molecules are more than correlated epiphenomena and instead contribute in significant ways to asthma pathogenesis.

SUMMARY

Assessments of chemokine (C-C motif) ligand 17 and YKL-40 may allow physicians to more accurately diagnose and predict the course of asthma and thereby allow therapy to be appropriately tailored for a given patient.

Inhibition of aldose reductase prevents experimental allergic airway inflammation in mice

BACKGROUND

The bronchial asthma, a clinical complication of persistent inflammation of the airway and subsequent airway hyper-responsiveness, is a leading cause of morbidity and mortality in critically ill patients. Several studies have shown that oxidative stress plays a key role in initiation as well as amplification of inflammation in airways. However, still there are no good anti-oxidant strategies available for therapeutic intervention in asthma pathogenesis. Most recent studies suggest that polyol pathway enzyme, aldose reductase (AR), contributes to the pathogenesis of oxidative stress-induced inflammation by affecting the NF-kappaB-dependent expression of cytokines and chemokines and therefore inhibitors of AR could be anti-inflammatory. Since inhibitors of AR have already gone through phase-III clinical studies for diabetic complications and found to be safe, our hypothesis is that AR inhibitors could be novel therapeutic drugs for the prevention and treatment of asthma. Hence, we investigated the efficacy of AR inhibition in the prevention of allergic responses to a common natural airborne allergen, ragweed pollen that leads to airway inflammation and hyper-responsiveness in a murine model of asthma.

METHODS AND FINDINGS

Primary Human Small Airway Epithelial Cells (SAEC) were used to investigate the in vitro effects of AR inhibition on ragweed pollen extract (RWE)-induced cytotoxic and inflammatory signals. Our results indicate that inhibition of AR prevents RWE -induced apoptotic cell death as measured by annexin-v staining, increase in the activation of NF-kappaB and expression of inflammatory markers such as inducible nitric oxide synthase (iNOS), cycloxygenase (COX)-2, Prostaglandin (PG) E(2), IL-6 and IL-8. Further, BALB/c mice were sensitized with endotoxin-free RWE in the absence and presence of AR inhibitor and followed by evaluation of perivascular and peribronchial inflammation, mucin production, eosinophils infiltration and airway hyperresponsiveness. Our results indicate that inhibition of AR prevents airway inflammation and production of inflammatory cytokines, accumulation of eosinophils in airways and sub-epithelial regions, mucin production in the bronchoalveolar lavage fluid and airway hyperresponsiveness in mice.

CONCLUSIONS

These results suggest that airway inflammation due to allergic response to RWE, which subsequently activates oxidative stress-induced expression of inflammatory cytokines via NF-kappaB-dependent mechanism, could be prevented by AR inhibitors. Therefore, inhibition of AR could have clinical implications, especially for the treatment of airway inflammation, a major cause of asthma pathogenesis.

Activin-A induces regulatory T cells that suppress T helper cell immune responses and protect from allergic airway disease

Activin-A is a pleiotropic cytokine that participates in developmental, inflammatory, and tissue repair processes. Still, its effects on T helper (Th) cell–mediated immunity, critical for allergic and autoimmune diseases, are elusive. We provide evidence that endogenously produced activin-A suppresses antigen-specific Th2 responses and protects against airway hyperresponsiveness and allergic airway disease in mice. Importantly, we reveal that activin-A exerts suppressive function through induction of antigen-specific regulatory T cells that suppress Th2 responses in vitro and upon transfer in vivo. In fact, activin-A also suppresses Th1-driven responses, pointing to a broader immunoregulatory function. Blockade of interleukin 10 and transforming growth factor β1 reverses activin-A–induced suppression. Remarkably, transfer of activin-A–induced antigen-specific regulatory T cells confers protection against allergic airway disease. This beneficial effect is associated with dramatically decreased maturation of draining lymph node dendritic cells. Therapeutic administration of recombinant activin-A during pulmonary allergen challenge suppresses Th2 responses and protects from allergic disease. Finally, we demonstrate that immune cells infiltrating the lungs from individuals with active allergic asthma, and thus nonregulated inflammatory response, exhibit significantly decreased expression of activin-A's responsive elements. Our results uncover activin-A as a novel suppressive factor for Th immunity and a critical controller of allergic airway disease.

Histamine H1-receptor antagonists with immunomodulating activities: potential use for modulating T helper type 1 (Th1)/Th2 cytokine imbalance and inflammatory responses in allergic diseases

Being a first-line treatment for hypersensitivity allergic disease, histamine H1-receptor antagonists possess anti-inflammatory activity in addition to being H1-receptor antagonists. While it is not purely a histamine-related condition, hypersensitivity allergic disease is associated with an increase in the number of T helper type 2 (Th2) cells and Th2 cytokines, and a decrease in the number of Th1 cells and Th1 cytokines. Suppression of Th2-type cytokine production in addition to H1-receptor blockade may therefore represent a successful therapeutic strategy for the treatment of hypersensitivity allergic diseases. H1-receptor antagonists have been reported to modulate immune cascade at various points by acting on T cell-related inflammatory molecules, including adhesion molecules, chemokines and inflammatory cytokines. These effects of H1-receptor antagonists may be optimized for the treatment of allergic diseases. Besides their ability to regulate inflammatory molecules, some H1-receptor antagonists have been reported to down-regulate Th2 cytokine production. In particular, it has been shown that several H1-receptor antagonists specifically inhibit the production of Th2, but not Th1, cytokines. Accumulating evidence indicates a crucial role for Th1/Th2 cytokine imbalance on the development of allergic diseases. Accordingly, the use of H1-receptor antagonist with Th2 cytokine inhibitory activity to modulate Th1/Th2 cytokine imbalance might be a favourable strategy for the treatment of hypersensitivity allergic diseases. Furthermore, the identification of H1-receptor antagonists which possess immunoregulatory activities in addition to their anti-histamine activity will provide an important insight into the development of novel immunoregulatory drugs.