Ambient particulate matter induces an exacerbation of airway inflammation in experimental asthma: role of interleukin‐33

High levels of ambient environmental particulate matter (PM10 i.e. < 10 μm median aerodynamic diameter) have been linked to acute exacerbations of asthma. We examined the effects of delivering a single dose of Sydney PM10 by intranasal instillation to BALB/c mice that had been sensitized to ovalbumin and challenged repeatedly with a low (≈3 mg/m³) mass concentration of aerosolized ovalbumin for 4 weeks. Responses were compared to animals administered carbon black as a negative control, or a moderate (≈30 mg/m³) concentration of ovalbumin to simulate an allergen‐induced acute exacerbation of airway inflammation. Delivery of PM10 to mice, in which experimental mild chronic asthma had previously been established, elicited characteristic features of enhanced allergic inflammation of the airways, including eosinophil and neutrophil recruitment, similar to that in the allergen‐induced exacerbation. In parallel, there was increased expression of mRNA for interleukin (IL)‐33 in airway tissues and an increased concentration of IL‐33 in bronchoalveolar lavage fluid. Administration of a monoclonal neutralizing anti‐mouse IL‐33 antibody prior to delivery of particulates significantly suppressed the inflammatory response induced by Sydney PM10, as well as the levels of associated proinflammatory cytokines in lavage fluid. We conclude that IL‐33 plays a key role in driving airway inflammation in this novel experimental model of an acute exacerbation of chronic allergic asthma induced by exposure to PM10.     

Recombinant pyrin domain protein attenuates allergic inflammation by suppressing NF‐κB pathway in asthmatic mice

Pyrin domain (PYD), a subclass of protein motif known as the death fold, is frequently involved in inflammation and immune responses. PYD modulates nuclear factor‐kappa B (NF‐κB) signalling pathway upon various stimuli. Herein, a novel recombinant pyrin domain protein (RPYD) was generated. Its role and mechanism in inflammatory response in an ovalbumin (OVA) induced asthma model was investigated. After OVA challenge, there was inflammatory cell infiltration in the lung, as well as airway hyper‐responsiveness (AHR) to inhaled methacholine. In addition, eosinophils increased in the bronchoalveolar lavage fluids, alone with the elevated levels of Th‐2 type cytokines [interleukin (IL)‐4, IL‐5 and IL‐13], eotaxin, and adhesion molecules. However, the transnasal administration of RPYD before the OVA challenge significantly inhibited these asthmatic reactions. Moreover, RPYD markedly suppressed NF‐κB translocation, reduced phosphorylation of p38 MAPK, and thus attenuated the expression of intercellular adhesion molecule 1 and IL‐6 in the BEAS‐2B cells stimulated by proinflammatory cytokines in vitro. These findings indicate that RPYD can protect asthma host from OVA‐induced airway inflammation and AHR via down‐regulation of NF‐κB and p38 MAPK activities. RPYD may be used as a potential medicine for the treatment of asthma in clinic.     

The role of interleukin‐4Rα in the induction of glutamic acid decarboxylase in airway epithelium following acute house dust mite exposure

Background Asthma is a disease characterized by airway inflammation, remodelling and dysfunction. Airway inflammation contributes to remodelling, a term that is used to describe structural changes including goblet cell metaplasia (GCM), matrix deposition, and smooth muscle hyperplasia/hypertrophy. GCM has been implicated in asthma mortality by contributing to mucus plugs and leading to asphyxiation. In animal models, this process is highly dependent on IL‐13. Recently, we have described an IL‐13‐dependent up‐regulation of a GABAergic signalling system in airway epithelium that contributes to GCM. The mechanism by which IL‐13 up‐regulates GABA signalling in airway epithelium is unknown. Objectives To test the hypothesis that IL‐4Rα signalling is required for allergen induced up‐regulation of GABAergic signalling and GCM. Methods BALB/c mice were exposed to an acute house dust mite (HDM) protocol and received vehicle, anti‐IL‐4Rα‐monoclonal antibody, or control antibody. Outcomes included airway responses to inhaled methacholine (MCh), histology for eosinophilia and GCM, phosphorylated STAT6 levels using immunohistochemistry and immunoblot, and glutamic acid decarboxylase (GAD) 65/67 and GABA_Aβ_2/3 receptor subunit expression using confocal microscopy. Results Acute HDM exposure resulted in increased airway responses to MCh, lung eosinophilia, STAT6 phosphorylation, elevations in GAD65/67 and GABA_Aβ_2/3 receptor expression, and GCM that were inhibited with anti‐IL‐4Rα‐monoclonal treatment. Control antibody had no effect. Conclusion The IL‐4Rα is required for allergen‐induced up‐regulation of a GABAergic system in airway epithelium implicated in GCM following acute HDM exposure. Cite this as: J. A. Hirota, A. Budelsky, D. Smith, B. Lipsky, R. Ellis, Y‐Y. Xiang, W‐Y. Lu and M. D. Inman, Clinical & Experimental Allergy, 2010 (40) 820–830.     

Distinct sustained structural and functional effects of interleukin‐33 and interleukin‐25 on the airways in a murine asthma surrogate

Interleukin‐25 (IL‐25) and IL‐33, which belong to distinct cytokine families, induce and promote T helper type 2 airway inflammation. Both cytokines probably play a role in asthma, but there is a lack of direct evidence to clarify distinctions between their functions and how they might contribute to distinct ‘endotypes’ of disease. To address this, we made a direct comparison of the effects of IL‐25 and IL‐33 on airway inflammation and physiology in our established murine asthma surrogate, which involves per‐nasal, direct airway challenge. Intranasal challenge with IL‐33 or IL‐25 induced inflammatory cellular infiltration, collagen deposition, airway smooth muscle hypertrophy, angiogenesis and airway hyper‐responsiveness, but neither increased systemic production of IgE or IgG1. Compared with that of IL‐25, the IL‐33‐induced response was characterized by more sustained laying down of extracellular matrix protein, neoangiogenesis, T helper type 2 cytokine expression and elevation of tissue damping. Hence, both IL‐25 and IL‐33 may contribute significantly and independently to asthma ‘endotypes’ when considering molecular targets for the treatment of human disease.     

Prenatal environmental tobacco smoke exposure increases allergic asthma risk with methylation changes in mice

Allergic asthma remains an inadequately understood disease. In utero exposure to environmental tobacco smoke (ETS) has been identified as an environmental exposure that can increase an individual's asthma risk. To improve our understanding of asthma onset and development, we examined the effect of in utero ETS exposure on allergic disease susceptibility in an asthmatic phenotype using a house dust mite (HDM) allergen‐induced murine model. Pregnant C57BL/6 mice were exposed to either filtered air or ETS during gestation, and their offspring were further exposed to HDM at 6–7 weeks old to induce allergic inflammation. Methylation in the promoter regions of allergic inflammation‐related genes and genomic DNA was quantified. Exposure to HDM resulted in the onset of allergic lung inflammation, with an increased presence of inflammatory cells, Th2 cytokines (IL‐4, IL‐5, and IL‐13), and airway remodeling. These asthmatic phenotypes were significantly enhanced when the mice had been exposed to in utero ETS. Furthermore, prenatal ETS exposure and subsequent HDM (ETS/HDM)‐induced asthmatic phenotypes agree with methylation changes in the selected asthma‐related genes, including IL‐4, IL‐5, IL‐13, INF‐γ, and FOXP3. Global DNA methylation was significantly lower in ETS/HDM‐exposed mice than that of controls, which coincides with the results observed in lung, spleen, and blood DNAs. Prenatal ETS exposure resulted in a severe increase in allergic inflammatory responses after an HDM challenge, with corresponding methylation changes. Prenatal ETS exposure may influence developmental plasticity and result in altered epigenetic programming, leading to an increased susceptibility to asthma. Environ. Mol. Mutagen. 58:423–433, 2017. © 2017 Wiley Periodicals, Inc.     

Post-allergen challenge inhibition of poly(ADP-ribose) polymerase harbors therapeutic potential for treatment of allergic airway inflammation

Background Identifying therapeutic drugs that block the release or effects of T‐helper type 2 (Th2) cytokines after allergen exposure is an important goal for the treatment of allergic inflammatory diseases including asthma. We recently showed, using a murine model of allergic airway inflammation, that poly(ADP‐ribose) polymerase (PARP) plays an important role in the pathogenesis of asthma‐related lung inflammation. PARP inhibition, by single injection of a novel inhibitor, thieno[2,3‐c]isoquinolin‐5‐one (TIQ‐A), before ovalbumin (OVA) challenge, prevented airway eosinophilia in C57BL/6 mice with concomitant suppression of Th2 cytokine production and mucus secretion. Objective To evaluate the efficacy of the drug when it is given after OVA challenge for its possible therapeutic potential. Methods This study was conducted using a murine model of allergic airway inflammation. Results A single injection of TIQ‐A (6 mg/kg) one or 6 h post‐allergen challenge conferred similar reduction in OVA challenge‐induced eosinophilia. More significantly, post‐allergen challenge administration of the drug exerted even better suppression on the production of IL‐4, IL‐5, IL‐13, and IgE and prevented airway hyperresponsiveness to inhaled‐methacholine. The significant decrease in IL‐13 was accompanied by a complete absence of airways mucus production indicating a potential protection against allergen‐induced airway remodelling. Conclusion The coincidence of the inflammation trigger and the time of drug administration appear to be important for the drug's more pronounced protection. The observed time window for efficacy, 1 or 6 h after allergen challenge may be of great clinical interest. These findings may provide a novel therapeutic strategy for the treatment of allergic airway inflammation, including asthma.     

Group 2 innate lymphoid cells in lung inflammation

Although allergic asthma is a heterogeneous disease, allergen‐specific T helper 2 (Th2) cells producing the key cytokines involved in type 2 inflammation, interleukin‐4 (IL‐4), IL‐5 and IL‐13, are thought to play a major role in asthma pathogenesis. This model is challenged by the recent discovery of group 2 innate lymphoid cells (ILC2) that represent a critical innate source of type 2 cytokines. These ILC2 are activated by epithelial cell‐derived cytokines, including IL‐25 and IL‐33, which have been implicated in the initiation of asthma. In this review, we will discuss recent studies supporting a significant role for ILC2 in lung inflammation, with special attention to allergen‐induced asthma.     

Oral myeloid cells uptake allergoids coupled to mannan driving Th1/Treg responses upon sublingual delivery in mice

Background

Polymerized allergoids coupled to nonoxidized mannan (PM‐allergoids) may represent novel vaccines targeting dendritic cells (DCs). PM‐allergoids are better captured by DCs than native allergens and favor Th1/Treg cell responses upon subcutaneous injection. Herein we have studied in mice the in vivo immunogenicity of PM‐allergoids administered sublingually in comparison with native allergens.

Methods

Three immunization protocols (4‐8 weeks long) were used in Balb/c mice. Serum antibody levels were tested by ELISA. Cell responses (proliferation, cytokines, and Tregs) were assayed by flow cytometry in spleen and lymph nodes (LNs). Allergen uptake was measured by flow cytometry in myeloid sublingual cells.

Results

A quick antibody response and higher IgG2a/IgE ratio were observed with PM‐allergoids. Moreover, stronger specific proliferative responses were seen in both submandibular LNs and spleen cells assayed in vitro. This was accompanied by a higher IFNγ/IL‐4 ratio with a quick IL‐10 production by submandibular LN cells. An increase in CD4⁺CD25^highFOXP3⁺ Treg cells was detected in LNs and spleen of mice treated with PM‐allergoids. These allergoids were better captured than native allergens by antigen‐presenting (CD45⁺MHC‐II⁺) cells obtained from the sublingual mucosa, including DCs (CD11b⁺) and macrophages (CD64⁺). Importantly, all the differential effects induced by PM‐allergoids were abolished when using oxidized instead of nonoxidized PM‐allergoids.

Conclusion

Our results demonstrate for the first time that PM‐allergoids administered through the sublingual route promote the generation of Th1 and FOXP3⁺ Treg cells in a greater extent than native allergens by mechanisms that might well involve their better uptake by oral antigen‐presenting cells.     

Evaluation of peroxisome proliferator‐activated receptor agonists on interleukin‐5‐induced eosinophil differentiation

Peroxisome proliferator‐activated receptor (PPAR) agonists have been suggested as novel therapeutics for the treatment of inflammatory lung disease, such as allergic asthma. Treatment with PPAR agonists has been shown to inhibit airway eosinophilia in murine models of allergic asthma, which can occur through several mechanisms including attenuated generation of chemoattractants (e.g. eotaxin) and decreased eosinophil migrational responses. In addition, studies report that PPAR agonists can inhibit the differentiation of several cell types. To date, no studies have examined the effects of PPAR agonists on interleukin‐5 (IL‐5) ‐induced eosinophil differentiation from haemopoietic progenitor cells. Non‐adherent mononuclear cells or CD34⁺ cells isolated from the peripheral blood of allergic subjects were grown for 2 weeks in Methocult^® cultures with IL‐5 (10 ng/ml) and IL‐3 (25 ng/ml) in the presence of 1–1000 nm PPARα agonist (GW9578), PPARβ/δ agonist (GW501516), PPARγ agonist (rosiglitazone) or diluent. The number of eosinophil/basophil colony‐forming units (Eo/B CFU) was quantified by light microscopy. The signalling mechanism involved was assessed by phosphoflow. Blood‐extracted CD34⁺ cells cultured with IL‐5 or IL‐5 + IL‐3 formed Eo/B CFU, which were significantly inhibited by rosiglitazone (100 nm , P < 0·01) but not GW9578 or GW501516. In addition, rosglitazone significantly inhibited IL‐5‐induced phosphorylation of extracellular signal‐regulated kinase 1/2. We observed an inhibitory effect of rosiglitazone on eosinophil differentiation in vitro, mediated by attenuation of the extracellular signal‐regulated kinase 1/2 signalling pathway. These findings indicate that the PPARγ agonist can attenuate tissue eosinophilia by interfering with local differentiative responses.     

Regulatory T cells and type 2 innate lymphoid cell‐dependent asthma

Group 2 innate lymphoid cells (ILC2s) are a recently identified group of cells with the potent capability to produce Th2‐type cytokines such as interleukin (IL)‐5 and IL‐13. Several studies suggest that ILC2s play an important role in the development of allergic diseases and asthma. Activation of pulmonary ILC2s in murine models lacking T and B cells induces eosinophilia and airway hyper‐reactivity (AHR), which are cardinal features of asthma. More importantly, numerous recent studies have highlighted the role of ILC2s in asthma persistence and exacerbation among human subjects, and thus, regulation of pulmonary ILC2s is a major area of investigation aimed at curbing allergic lung inflammation and exacerbation. Emerging evidence reveals that a group of regulatory T cells, induced Tregs (iTregs), effectively suppress the production of ILC2‐driven, pro‐inflammatory cytokines IL‐5 and IL‐13. The inhibitory effects of iTregs are blocked by preventing direct cellular contact or by inhibiting the ICOS‐ICOS‐ligand (ICOSL) pathway, suggesting that both direct contact and ICOS‐ICOSL interaction are important in the regulation of ILC2 function. Also, cytokines such as IL‐10 and TGF‐β1 significantly reduce cytokine secretion by ILC2s. Altogether, these new findings uncover iTregs as potent regulators of ILC2 activation and implicate their utility as a therapeutic approach for the treatment of ILC2‐mediated allergic asthma and respiratory disease.     

Suppression of cytokine expression by roflumilast and dexamethasone in a model of chronic asthma

Background In a mouse model of mild chronic asthma, both inflammation and remodelling can be suppressed by dexamethasone (a glucocorticoid) and roflumilast (a selective phosphodiesterase‐4 inhibitor). Objective To better understand the underlying molecular mechanisms, we investigated the effects of treatment on airway expression of inflammation‐related cytokines, as well as on epithelial expression of growth factors. Methods BALB/c mice systemically sensitized to ovalbumin were challenged with aerosolized antigen for 6 weeks and treated with roflumilast or dexamethasone during the final 2 weeks. Expression of mRNA, for a variety of cytokines and growth factors, was assessed in selectively dissected proximal airways or in airway epithelium obtained by laser capture microdissection. Results In the airway wall of vehicle‐treated challenged animals, there was significantly elevated expression of mRNA for a variety of pro‐inflammatory and T helper type 2 cytokines, as well as for IFN‐γ. All these cytokines were suppressed by dexamethasone. Treatment with roflumilast reduced expression of IL‐17A, TNF‐α, granulocyte‐macrophage colony‐stimulating factor and IL‐6, but did not inhibit other cytokines. Both drugs suppressed the enhanced expression of mRNA for growth factors such as TGF‐β1 and FGF‐2 in airway epithelium. Conclusions Whereas dexamethasone non‐specifically inhibits numerous mediators involved in inflammation and the immune response, roflumilast selectively inhibits a subset of pro‐inflammatory cytokines and growth factors. These mediators and/or the cells that produce them may have critical roles in the pathogenesis of the lesions of chronic asthma.     

Nasal administration of interleukin‐33 induces airways angiogenesis and expression of multiple angiogenic factors in a murine asthma surrogate

The T‐helper cell type 2‐promoting cytokine interleukin‐33 (IL‐33) has been implicated in asthma pathogenesis. Angiogenesis is a feature of airways remodelling in asthma. We hypothesized that IL‐33 induces airways angiogenesis and expression of angiogenic factors in an established murine surrogate of asthma. In the present study, BALB/c mice were subjected to serial intranasal challenge with IL‐33 alone for up to 70 days. In parallel, ovalbumin (OVA) ‐sensitized mice were subjected to serial intranasal challenge with OVA or normal saline to serve as positive and negative controls, respectively. Immunohistochemical analysis of expression of von Willebrand factor and erythroblast transformation‐specific‐related gene, both blood vessel markers, and angiogenic factors angiogenin, insulin‐like growth factor‐1, endothelin‐1, epidermal growth factor and amphiregulin was performed in lung sections ex vivo. An established in‐house assay was used to test whether IL‐33 was able to induce microvessel formation by human vascular endothelial cells. Results showed that serial intranasal challenge of mice with IL‐33 or OVA resulted in proliferation of peribronchial von Willebrand factor‐positive blood vessels to a degree closely related to the total expression of the angiogenic factors amphiregulin, angiogenin, endothelin‐1, epidermal growth factor and insulin‐like growth factor‐1. IL‐33 also induced microvessel formation by human endothelial cells in a concentration‐dependent fashion in vitro. Our data are consistent with the hypothesis that IL‐33 has the capacity to induce angiogenesis at least partly by increasing local expression of multiple angiogenic factors in an allergen‐independent murine asthma surrogate, and consequently that IL‐33 or its receptor is a potential novel molecular target for asthma therapy.     

Interleukin-9 induces goblet cell hyperplasia during repair of human airway epithelia

Asthma is characterized by airway inflammation, smooth muscle hyperreactivity, and airway remodeling with excessive mucus production. The effect cytokines like interleukin (IL)-9 have on airway epithelia has been addressed using murine models of asthma, as well as transgenic and knockout mice. Though highly informative, differences exist between mouse and human airway epithelia, including cellular composition (e.g., Clara cells) and stem cell/plasticity capabilities. Therefore, to address cytokine effects on human airway epithelia, we have used a primary model system to ask whether IL-9 can alter cell fates of human airway epithelia. Here, we show that IL-9 has little effect on fully differentiated ciliated human airway epithelia. However, in the setting of airway injury repair, IL-9 results in goblet cell hyperplasia. A similar response was observed when the epithelium was exposed to IL-9 before it became fully differentiated. Moreover, exposure to IL-9 resulted in increased lysozyme and mucus production by the epithelia. Thus, a combination of IL-9 and mechanical injury can explain, in part, goblet cell hyperplasia that is evident in the lungs of individuals with asthma. These data suggest that interventions that limit airway epithelial damage, block IL-9, or modulate the repair process should result in decreased airway remodeling and prevent the chronic manifestations of this disease.     

Revisiting Type 2‐high and Type 2‐low airway inflammation in asthma: current knowledge and therapeutic implications

Asthma is a complex respiratory disorder characterized by marked heterogeneity in individual patient disease triggers and response to therapy. Several asthma phenotypes have now been identified, each defined by a unique interaction between genetic and environmental factors, including inflammatory, clinical and trigger‐related phenotypes. Endotypes further describe the functional or pathophysiologic mechanisms underlying the patient's disease. type 2‐driven asthma is an emerging nomenclature for a common subtype of asthma and is characterized by the release of signature cytokines IL‐4, IL‐5 and IL‐13 from cells of both the innate and adaptive immune systems. A number of well‐recognized biomarkers have been linked to mechanisms involved in type 2 airway inflammation, including fractional exhaled nitric oxide, serum IgE, periostin, and blood and sputum eosinophils. These type 2 cytokines are targets for pharmaceutical intervention, and a number of therapeutic options are under clinical investigation for the management of patients with uncontrolled severe asthma. Anticipating and understanding the heterogeneity of asthma and subsequent improved characterization of different phenotypes and endotypes must guide the selection of treatment to meet individual patients’ needs.     

Rhinovirus infection and house dust mite exposure synergize in inducing bronchial epithelial cell interleukin‐8 release

Background Human rhinoviruses (HRVs) and house dust mites (HDMs) are among the most common environmental factors able to induce airway inflammation in asthma. Although epidemiological studies suggest that they also synergize in inducing asthma exacerbations, there is no experimental evidence to support this, nor any information on the possible mechanisms involved. Objective To investigate their interaction on the induction of airway epithelial inflammatory responses in vitro. Methods BEAS‐2B cells were exposed to activated HDM Dermatophagoides pteronyssinus major allergen I (Der p I), HRVs (HRV1b or HRV16) or both in different sequences. IL‐8/CXCL8 release, intercellular adhesion molecule (ICAM)‐1 surface expression and nuclear factor κB (NF‐κB) translocation were evaluated. Complementary, primary human bronchial epithelial cells (HBECs) exposed to both Der p I and RVs and IL‐8, IL‐6, IFN‐γ‐induced protein (IP)‐10/CXCL10, IFN‐λ1/IL‐29, regulated upon activation normal T lymphocyte expressed and secreted (RANTES)/CCL5 release were measured. Results RV and Der p I up‐regulated IL‐8 release, ICAM‐1 expression and NF‐κB translocation in BEAS‐2B cells. Simultaneous exposure to both factors, as well as when cells were initially exposed to HRV and then to Der p I, resulted in further induction of IL‐8 in a synergistic manner. Synergism was not observed when cells were initially exposed to Der p I and then to HRV. This was the pattern in ICAM‐1 induction although the phenomenon was not synergistic. Concurrent exposure induced an early synergistic NF‐κB translocation induction, differentiating with time, partly explaining the above observation. In HBECs, both HRV and Der p I induced IL‐8, IL‐6, IL‐29 and IP‐10, while RANTES was induced only by HRV. Synergistic induction was observed only in IL‐8. Conclusion HRV and enzymatically active Der p I can act synergistically in the induction of bronchial epithelial IL‐8 release, when HRV infection precedes or is concurrent with Der p I exposure. Such a synergy may represent an important mechanism in virus‐induced asthma exacerbations.     

Asthma: The importance of dysregulated barrier immunity

Chronic asthma is an inflammatory disease of the airway wall that leads to bronchial smooth muscle hyperreactivity and airway obstruction, caused by inflammation, goblet cell metaplasia, and airway wall remodeling. In response to allergen presentation by airway DCs, T‐helper lymphocytes of the adaptive immune system control many aspects of the disease through secretion of IL‐4, IL‐5, IL‐13, IL‐17, and IL‐22, and these are counterbalanced by cytokines produced by Treg cells. Many cells of the innate immune system such as mast cells, basophils, neutrophils, eosinophils, and innate lymphoid cells also play an important role in disease pathogenesis. Barrier epithelial cells are being ever more implicated in disease pathogenesis than previously thought, as these cells have in recent years been shown to sense exposure to allergens via pattern recognition receptors and to activate conventional and inflammatory‐type DCs and other innate immune cells through the secretion of thymic stromal lymphopoietin, granulocyte‐macrophage colony stimulating factor, IL‐1, IL‐33, and IL‐25. Understanding this cytokine crosstalk between barrier epithelial cells, DCs, and immune cells provides important insights into the mechanisms of allergic sensitization and asthma progression as discussed in this review.     

An engineered 3D human airway mucosa model based on an SIS scaffold

To investigate interrelations of human obligate airway pathogens, such as Bordetella pertussis, and their hosts test systems with high in vitro/in vivo correlation are of urgent need. Using a tissue engineering approach, we generated a 3D test system of the airway mucosa with human tracheobronchial epithelial cells (hTEC) and fibroblasts seeded on a clinically implemented biological scaffold. To investigate if hTEC display tumour-specific characteristics we analysed Raman spectra of hTEC and the adenocarcinoma cell line Calu-3. To establish optimal conditions for infection studies, we treated human native airway mucosa segments with B. pertussis. Samples were processed for morphologic analysis. Whereas our test system consisting of differentiated epithelial cells and migrating fibroblasts shows high in vitro/in vivo correlation, hTEC seeded on the scaffold as monocultures did not resemble the in vivo situation. Differences in Raman spectra of hTEC and Calu-3 were identified in distinct wave number ranges between 720 and 1662 cm⁻¹ indicating that hTEC do not display tumour-specific characteristics. Infection of native tissue with B. pertussis led to cytoplasmic vacuoles, damaged mitochondria and destroyed epithelial cells. Our test system is suitable for infection studies with human obligate airway pathogens by mimicking the physiological microenvironment of the human airway mucosa.     

What goes up must come down: biomarkers and novel biologicals in severe asthma

Asthma is a heterogeneous airway disease characterized by typical symptoms in combination with variable airway obstruction. Most patients with asthma have well controlled symptoms and a low risk of asthma attacks with inhaled corticosteroid (ICS) treatment. However, a clinically important subgroup (~ 10%) remains symptomatic and/or at risk of asthma attacks despite maximum inhaled therapy. Patients with severe asthma are responsible for a significant proportion of healthcare costs attributable to asthma and have a large unmet need for better treatments. An important advance in recent years has been the recognition that severe asthma is heterogeneous with respect to clinical problems and the pattern of lower airway inflammation. Identification of eosinophilic inflammation in the airways has become an important priority as novel biologicals that target Th2 cytokines, such as anti‐IL5, anti‐IL‐13 and combined anti‐IL‐4/13 are showing considerable promise as treatments for this subgroup. It has also become clear that anti‐IgE (Omalizumab), the first monoclonal antibody registered for treatment of severe asthma, is only active in patients with active eosinophilic airway inflammation. The future will be identification of potentially responsive patients on the basis of raised biomarkers and, as suggested by the title of this review, targeted treatment with specific cytokine blockade that has a direct effect on the biomarkers. In this review, we outline an approach to the clinical assessment of patients potentially suitable for biological treatment and describe in detail the likely clinical impact of established and new biological treatments.     

The role of particulate matter in exacerbation of atopic asthma

Increasing evidence shows that elevated levels of particulate matter (PM) can exacerbate existing asthma, while evidence that PM can promote the induction of asthma is limited. PM in ambient air has been associated with increased emergency room visits and medication use by asthmatics. Controlled human exposure studies of acid aerosols suggest increased responses among adolescent asthmatics. Increased ambient and indoor levels of bioaerosols (e.g., house dust mite, fungal spores, endotoxin) have been associated with exacerbation of asthma. Environmental Protection Agency (EPA) studies focus on the effects of exposing humans and animal models to a combination of various PM samples (e.g., diesel exhaust particles, oil fly ash) and allergens (e.g., house dust mite, ovalbumin). These research efforts to understand the mechanisms by which PM exposure can promote allergic sensitization and exacerbate existing asthma concentrate on the role of transition metals. Exposure of animal models to combined PM and allergen promotes allergic sensitization and increases allergic inflammation and airway hyperresponsiveness. Exposure of healthy human volunteers to emission source PM samples promotes inflammation and increased indices of oxidant formation correlating with the quantity of transition metals in the samples. Results of these studies suggest that transition metals in ambient PM promote the formation of reactive oxygen species and subsequent lung injury, inflammation, and airway hyperresponsiveness leading to airflow limitation and symptoms of asthma.     

M2 polarization of murine peritoneal macrophages induces regulatory cytokine production and suppresses T‐cell proliferation

Bone‐marrow‐derived macrophages are divided into two phenotypically and functionally distinct subsets, M1 and M2 macrophages. Recently, it was shown that adoptive transfer of M2‐polarized peritoneal macrophages reduced the severity of experimental colitis in mice. However, it is still unclear whether peritoneal macrophages possess the same ability to be polarized to cells with functionally different phenotypes and cytokine production patterns as bone‐marrow‐derived macrophages. To address this question, we examined the ability of peritoneal macrophages to be polarized to the M1 and M2 phenotypes and determined the specific cytokine profiles of cells with each phenotype. We showed that peritoneal macrophages, as well as bone‐marrow‐derived macrophages, were differentiated into M1 and M2 phenotypes following stimulation with interferon‐γ (IFN‐γ) and interleukin‐4 (IL‐4)/IL‐13, respectively. Following in vitro stimulation with lipopolysaccharide, M2‐polarized peritoneal macrophages predominantly expressed T helper type 2 (Th2) cytokines and regulatory cytokines, including IL‐4, IL‐13, transforming growth factor‐β and IL‐10, whereas M1‐polarized peritoneal macrophages expressed negligible amounts of Th1 and pro‐inflammatory cytokines. ELISA showed that M2‐polarized peritoneal macrophages produced significantly more IL‐10 than M1‐polarized peritoneal macrophages. Notably, M2‐polarized peritoneal macrophages contributed more to the suppression of T‐cell proliferation than did M1‐polarized peritoneal macrophages. The mRNA expression of Th2 cytokines, including IL‐4 and IL‐13, increased in T‐cells co‐cultured with M2‐polarized macrophages. Hence, our findings showed that M2 polarization of peritoneal macrophages induced regulatory cytokine production and suppressed T‐cell proliferation in vitro, and that resident peritoneal macrophages could be used as a new adoptive transfer therapy for autoimmune/inflammatory diseases after polarization to the regulatory phenotype ex vivo.