T cells are necessary for ILC2 activation in house dust mite‐induced allergic airway inflammation in mice

Allergic asthma is a chronic inflammation of the airways mediated by an adaptive type 2 immune response. Upon allergen exposure, group 2 innate lymphoid cells (ILC2s) can be rapidly activated and represent an early innate source of IL‐5 and IL‐13. Here, we used a house dust mite (HDM)‐driven asthma mouse model to study the induction of ILC2s in allergic airway inflammation. In BALF, lungs, and lymph nodes, ILC2 activation is critically dependent on prior sensitization with HDM. Importantly, T cells are required for ILC2 induction, whereby T‐cell activation precedes ILC2 induction. During HDM‐driven allergic airway inflammation the accumulation of ILC2s in BALF is IL‐33 independent, although infiltrating ILC2s produce less cytokines in Il33^?/? mice. Transfer of in vitro polarized OVA‐specific OT‐II Th2 cells alone or in combination with Th17 cells followed by OVA and HDM challenge is not sufficient to induce ILC2, despite significant eosinophilic inflammation and T‐cell activation. In this asthma model, ILC2s are therefore not an early source of Th2 cytokines, but rather contribute to type 2 inflammation in which Th2 cells play a key role. Taken together, ILC2 induction in HDM‐mediated allergic airway inflammation in mice critically depends on activation of T cells.     

Influenza A facilitates sensitization to house dust mite in infant mice leading to an asthma phenotype in adulthood

The origins of allergic asthma, particularly in infancy, remain obscure. Respiratory viral infections and allergen sensitization in early life have been associated with asthma in young children. However, a causal link has not been established. We investigated whether an influenza A infection in early life alters immune responses to house dust mite (HDM) and promotes an asthmatic phenotype later in life. Neonatal (8-day-old) mice were infected with influenza virus and 7 days later, exposed to HDM for 3 weeks. Unlike adults, neonatal mice exposed to HDM exhibited negligible immune responsiveness to HDM, but not to influenza A. HDM responsiveness in adults was associated with distinct Ly6c+ CD11b+ inflammatory dendritic cell and CD8α+ plasmacytoid (pDC) populations that were absent in HDM-exposed infant mice, suggesting an important role in HDM-mediated inflammation. Remarkably, HDM hyporesponsiveness was overcome when exposure occurred concurrently with an acute influenza infection; young mice now displayed robust allergen-specific immunity, allergic inflammation, and lung remodeling. Remodeling persisted into early adulthood, even after prolonged discontinuation of allergen exposure and was associated with marked impairment of lung function. Our data demonstrate that allergen exposure coincident with acute viral infection in early life subverts constitutive allergen hyporesponsiveness and imprints an asthmatic phenotype in adulthood.     

In utero exposure to second‐hand smoke activates pro‐asthmatic and oncogenic miRNAs in adult asthmatic mice

Exposures to environmental pollutants contribute to dysregulated microRNA (miRNA) expression profiles, which have been implicated in various diseases. Previously, we reported aggravated asthmatic responses in ovalbumin (OVA)‐challenged adult mice that had been exposed in utero to second‐hand smoke (SHS). Whether in utero SHS exposure dysregulates miRNA expression patterns in the adult asthma model has not been investigated. Pregnant BALB/c mice were exposed (days 6–19 of pregnancy) to SHS (10 mg/m³) or HEPA‐filtered air. All offspring were sensitized and challenged with OVA (19–23 weeks) before sacrifice. RNA samples extracted from lung homogenates, were subjected to RNA sequencing (RNA‐seq). RNA‐seq identified nine miRNAs that were most significantly up‐regulated by in utero SHS exposure. Among these nine, miR‐155‐5p, miR‐21‐3p, and miR‐18a‐5p were also highly correlated with pro‐asthmatic Th2 cytokine levels in bronchoalveolar lavage fluid. Further analysis indicated that these up‐regulated miRNAs shared common chromosome locations, particularly Chr 11C, with pro‐asthmatic genes. These three miRNAs have also been characterized as oncogenic miRNAs (oncomirs). We cross‐referenced miRNA‐mRNA expression profiles and identified 16 tumor suppressor genes that were down‐regulated in the in utero‐exposed offspring and that are predicted targets of the up‐regulated oncomirs. In conclusion, in utero SHS exposure activates pro‐asthmatic genes and miRNAs, which colocalize at specific chromosome locations, in OVA‐challenged adult mice. The oncogenic characteristics of the miRNAs and putative miRNA‐mRNA regulatory networks suggest that the synergistic effect of in utero SHS exposure and certain adult irritants may promote an oncogenic milieu in mouse lungs via inhibition of miRNA‐regulated tumor suppressor genes. Environ. Mol. Mutagen. 57:190–199, 2016. © 2016 Wiley Periodicals, Inc.     

Early-life exposure to combustion-derived particulate matter causes pulmonary immunosuppression

Elevated levels of combustion-derived particulate matter (CDPM) are a risk factor for the development of lung diseases such as asthma. Studies have shown that CDPM exacerbates asthma, inducing acute lung dysfunction and inflammation; however, the impact of CDPM exposure on early immunological responses to allergens remains unclear. To determine the effects of early-life CDPM exposure on allergic asthma development in infants, we exposed infant mice to CDPM and then induced a mouse model of asthma using house dust mite (HDM) allergen. Mice exposed to CDPM+HDM failed to develop a typical asthma phenotype including airway hyper-responsiveness, T-helper type 2 (Th2) inflammation, Muc5ac expression, eosinophilia, and HDM-specific immunoglobulin (Ig) compared with HDM-exposed mice. Although HDM-specific IgE was attenuated, total IgE was twofold higher in CDPM+HDM mice compared with HDM mice. We further demonstrate that CDPM exposure during early life induced an immunosuppressive environment in the lung, concurrent with increases in tolerogenic dendritic cells and regulatory T cells, resulting in the suppression of Th2 responses. Despite having early immunosuppression, these mice develop severe allergic inflammation when challenged with allergen as adults. These findings demonstrate a mechanism whereby CDPM exposure modulates adaptive immunity, inducing specific antigen tolerance while amplifying total IgE, and leading to a predisposition to develop asthma upon rechallenge later in life.     

IL‐33 citrine reporter mice reveal the temporal and spatial expression of IL‐33 during allergic lung inflammation

Interleukin‐33 (IL‐33) is an IL‐1 family cytokine that signals via its receptor T1/ST2, and is a key regulator of inflammation, notably the type‐2 response implicated in allergic asthma. Critical to our understanding of the role of IL‐33 is the identification of the cellular sources of IL‐33. Although progress has been made in this area, the development of a robust live cell reporter of expression would allow the localisation of IL‐33 during ongoing immune responses. We have generated a fluorescent reporter mouse line, Il33^Cit/+, to define the expression profile of IL‐33 in vivo and demonstrate its temporal and spatial expression during experimental allergic asthma responses. We found that type‐2 pneumocytes constitute the major source of IL‐33 upon allergic lung inflammation following exposure to OVA, fungal extract or ragweed pollen. Using Il33^Cit/Cit mice (IL‐33‐deficient), we establish a role for IL‐33 early in the initiation of type‐2 responses and the induction of nuocytes (ILC2). We also demonstrate a potential mechanism of action by which IL‐33 rapidly initiates type‐2 immune responses. Il33^Cit/+ mice have enabled new insights into the initiation of type‐2 responses and will provide an important tool for further dissection of this important inflammatory pathway in vivo.     

Der p 1 and Der p 2 induce less severe late asthmatic responses than native Dermatophagoides pteronyssinus extract after a similar early asthmatic response

Background The models for exposure to house dust in research and clinical practice are selected with respect to their role in IgE‐mediated immediate hypersensitivity. The use of isolated major allergens instead of complex allergen extracts is becoming increasingly popular as it offers some important advantages for quantitative measures in diagnosis and research. Objective To compare house dust mite extract and isolated mite major allergens with respect to their ability to induce early and late asthmatic responses and bronchial hyperreactivity. Methods Bronchial responses to house dust mite (HDM, Dermatophagoides pteronyssinus) extract and isolated major allergens from HDM (Der p 1 and Der p 2) were compared in a double‐blind, randomized, cross‐over study in 20 patients with mild to moderate asthma who were allergic to HDM. Allergen was titrated to a standardized early asthmatic response. Bronchial hyper‐responsiveness to histamine (PC₂₀histamine) was determined before and after allergen inhalation to assess allergen‐induced bronchial hyper‐responsiveness and IL‐5 was measured in serum. In addition, the allergens were applied in intracutaneous skin tests and activation of basophil leucocytes and proliferation of peripheral blood mononuclear cells was tested in vitro. Results After a similar early asthmatic response (mean Δforced expiratory volume in 1 s (FEV₁)_,max?29.4 (SD 7.2) vs. ?33.1 (8.6) %; mean difference 3.6 (95% CI ?0.9 to 8.2) %), the late asthmatic response (mean ΔFEV_1,max?45.9 (21.9) vs. ?32.7 (22.3) %; mean difference 13.2 (3.8–22.3) %), the degree of allergen‐induced bronchial hyper‐responsiveness (mean ΔPC₂₀histamine, 1.8 (1.0) vs. 1.2 (0.9) doubling dose; mean difference 0.6 (0.2–1.1) doubling dose) and serum IL‐5 at 6 h were found to be significantly higher after bronchial challenge with HDM extract than after challenge with an isolated HDM major allergen. Likewise, there was an increased late skin reaction with HDM compared with isolated major allergen after a similar early skin reaction. Conclusion Constituents of HDM extract, other than Der p 1 or Der p 2, with no significant influence on the IgE‐mediated early asthmatic response contribute significantly to the allergen‐induced late asthmatic response and bronchial hyper‐reactivity.     

Airway remodelling and inflammation in asthma are dependent on the extracellular matrix protein fibulin‐1c

Asthma is a chronic inflammatory disease of the airways. It is characterized by allergic airway inflammation, airway remodelling, and airway hyperresponsiveness (AHR). Asthma patients, in particular those with chronic or severe asthma, have airway remodelling that is associated with the accumulation of extracellular matrix (ECM) proteins, such as collagens. Fibulin‐1 (Fbln1) is an important ECM protein that stabilizes collagen and other ECM proteins. The level of Fbln1c, one of the four Fbln1 variants, which predominates in both humans and mice, is increased in the serum and airways fluids in asthma but its function is unclear. We show that the level of Fbln1c was increased in the lungs of mice with house dust mite (HDM)‐induced chronic allergic airway disease (AAD). Genetic deletion of Fbln1c and therapeutic inhibition of Fbln1c in mice with chronic AAD reduced airway collagen deposition, and protected against AHR. Fbln1c‐deficient (Fbln1c^–/–) mice had reduced mucin (MUC) 5 AC levels, but not MUC5B levels, in the airways as compared with wild‐type (WT) mice. Fbln1c interacted with fibronectin and periostin that was linked to collagen deposition around the small airways. Fbln1c^–/– mice with AAD also had reduced numbers of α‐smooth muscle actin‐positive cells around the airways and reduced airway contractility as compared with WT mice. After HDM challenge, these mice also had fewer airway inflammatory cells, reduced interleukin (IL)‐5, IL‐13, IL‐33, tumour necrosis factor (TNF) and CXCL1 levels in the lungs, and reduced IL‐5, IL‐33 and TNF levels in lung‐draining lymph nodes. Therapeutic targeting of Fbln1c reduced the numbers of GATA3‐positive Th2 cells in the lymph nodes and lungs after chronic HDM challenge. Treatment also reduced the secretion of IL‐5 and IL‐13 from co‐cultured dendritic cells and T cells restimulated with HDM extract. Human epithelial cells cultured with Fbln1c peptide produced more CXCL1 mRNA than medium‐treated controls. Our data show that Fbln1c may be a therapeutic target in chronic asthma. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

OX40 blockade inhibits house dust mite driven allergic lung inflammation in mice and in vitro allergic responses in humans

The costimulatory receptor OX40 is expressed on activated T cells and regulates T‐cell responses. Here, we show the efficacy and mechanism of action of an OX40 blocking antibody using the chronic house dust mite (HDM) mouse model of lung inflammation and in vitro HDM stimulation of cells from HDM allergic human donors. We have demonstrated that OX40 blockade leads to a reduction in the number of eosinophils and neutrophils in the lavage fluid and lung tissue of HDM sensitized mice. This was accompanied by a decrease in activated and memory CD4⁺ T cells in the lungs and further analysis revealed that both the Th2 and Th17 populations were inhibited. Improved lung function and decreased HDM‐specific antibody responses were also noted. Significantly, efficacy was observed even when anti‐OX40 treatment was delayed until after inflammation was established. OX40 blockade also inhibited the release of the Th2 cytokines IL‐5 and IL‐13 from cells isolated from HDM allergic human donors. Altogether, our data provide evidence of a role of the OX40/OX40L pathway in ongoing allergic lung inflammation and support clinical studies of a blocking OX40 antibody in Th2 high severe asthma patients.     

Subcutaneous immunotherapy with purified Der p1 and 2 suppresses type 2 immunity in a murine asthma model

Background

Allergen‐specific immunotherapy can induce long‐term suppression of allergic symptoms, reduce medication use, and prevent exacerbations of allergic rhinitis and asthma. Current treatment is based on crude allergen extracts, which contain immunostimulatory components such as β‐glucans, chitins, and endotoxin. Use of purified or recombinant allergens might therefore increase efficacy of treatment.

Aims

Here, we test application of purified natural group 1 and 2 allergens from Dermatophagoides pteronyssinus (Der p) for subcutaneous immunotherapy (SCIT) treatment in a house dust mite (HDM)‐driven mouse model of allergic asthma.

Materials and methods

HDM‐sensitized mice received SCIT with crude HDM extract, a mixture of purified Der p1 and 2 (DerP1/2), or placebo. Upon challenges, we measured specific immunoglobulin responses, allergen‐induced ear swelling response (ESR), airway hyperresponsiveness (AHR), and inflammation in bronchoalveolar lavage fluid (BAL) and lung tissue.

Results

ESR measurement shows suppression of early allergic response in HDM‐SCIT– and DerP1/2‐SCIT–treated mice. Both HDM‐SCIT and DerP1/2‐SCIT are able to suppress AHR and eosinophilic inflammation. In contrast, only DerP1/2‐SCIT is able to significantly suppress type 2 cytokines in lung tissue and BAL fluid. Moreover, DerP1/2‐SCIT treatment is uniquely able suppress CCL20 and showed a trend toward suppression of IL‐33, CCL17 and eotaxin levels in lung tissue.

Discussion

Taken together, these data show that purified DerP1/2‐SCIT is able to not only suppress AHR and inflammation, but also has superior activity toward suppression of Th2 cells and HDM‐induced activation of lung structural cells including airway epithelium.

Conclusions

We postulate that treatment with purified natural major allergens derived from HDM will likely increase clinical efficacy of SCIT.     

Effects of various anti-asthmatic agents on mite allergen-pulsed murine bone marrow-derived dendritic cells

Background Dendritic cells (DCs) play an important role in the immune response and are critically involved in asthma. β₂‐agonists could potentially exacerbate type 2 T helper (Th2) cell‐mediated immune response. Objectives To determine the effects of various anti‐asthmatic agents on DCs function both in vitro and in vivo. Methods Murine bone marrow‐derived DCs were pulsed with mite allergen in the presence of pranlukast, salbutamol, salmeterol or fluticasone. These DCs were then inoculated intranasally into naïve mice to induce allergic airway inflammation in vivo. Results Pranlukast reduced IL‐10 and increased IL‐12, while fluticasone reduced both IL‐10 and IL‐12 production by mite allergen‐pulsed DCs. Allergic airway inflammation in pranlukast‐ and fluticasone‐treated and mite allergen pulsed DCs‐harbouring mice was attenuated and such response was associated with inhibition of Th2 response in the airway. Salbutamol did not alter cytokine production, while salmeterol reduced IL‐12 production by mite allergen‐pulsed DCs. Lung pathology in β₂‐agonist‐harbouring mice was comparable with those of mite allergen‐pulsed DCs‐harbouring mice. Conclusions Our results indicate that leukotriene receptor antagonists and corticosteroids inhibit DCs‐induced Th2 skewed immune response, and that short‐ and long‐acting β₂‐agonists do not modify DCs‐induced allergic airway inflammation.     

A low dose of Mycoplasma pneumoniae infection enhances an established allergic inflammation in mice: the role of the prostaglandin E2 pathway

Background Over 40% of chronic stable asthma patients have evidence of respiratory Mycoplasma pneumoniae (Mp) infection as detected by PCR, but not by serology and culture, suggesting that a low‐level Mp is involved in chronic asthma. However, the role of such a low‐level Mp infection in the regulation of allergic inflammation remains unknown. Objective To determine the impact of a low‐level Mp infection in mice with established airway allergic inflammation on allergic responses such as eosinophilia and chemokine eotaxin‐2, and the underlying mechanisms [i.e. the prostaglandin E₂ (PGE₂) pathway] since PGE₂ inhalation before an allergen challenge suppressed the eosinophil infiltration in human airways. Methods BALB/c mouse models of ovalbumin (OVA)‐induced allergic asthma with an ensuing low‐ or high‐dose Mp were used to assess IL‐4 expression, bronchoalveolar lavage (BAL) eosinophil, eotaxin‐2 and PGE₂ levels, and lung mRNA levels of microsomal prostaglandin E synthase‐1 (mPGES‐1). Primary alveolar macrophages (pAMs) from naïve BALB/c mice were cultured to determine whether Mp‐induced PGE₂ or exogenous PGE₂ down‐regulates IL‐4/IL‐13‐induced eotaxin‐2. Results Low‐dose Mp in allergic mice significantly enhanced IL‐4 and eotaxin‐2, and moderately promoted lung eosinophilia, whereas high‐dose Mp significantly reduced lung eosinophilia and tended to decrease IL‐4 and eotaxin‐2. Moreover, in both OVA‐naïve and allergic mice, lung mPGES‐1 mRNA and BAL PGE₂ levels were elevated in mice infected with high‐dose, but not low‐dose Mp. In pAMs, IL‐4/IL‐13 significantly increased eotaxin‐2, which was reduced by Mp infection accompanied by dose‐dependent PGE₂ induction. Exogenous PGE₂ inhibited IL‐4/IL‐13‐induced eotaxin‐2 in a dose‐dependent manner. Conclusions This study highlights a novel concept on how different bacterial loads in the lung modify the established allergic airway inflammation and thus interact with an allergen to further induce Th2 responses. That is, unlike high‐level Mp, low‐level Mp fails to effectively induce PGE₂ to down‐regulate allergic responses (e.g. eotaxin‐2), thus maintaining or even worsening allergic inflammation in asthmatic airways.     

T cells and ILC2s are major effector cells in influenza‐induced exacerbation of allergic airway inflammation in mice

Influenza virus infection is an important cause of severe asthma exacerbations, but it remains unclear how a Th1‐mediated antiviral response triggers a prototypical Th2 disease. We investigated CD4⁺ T cells and group 2 innate lymphoid cells (ILC2s) in influenza virus‐infected mice. We found that ILC2s accumulated in the lung rapidly after influenza virus infection, but the induction of IL‐5 and IL‐13 secretion was delayed and concomitant with T cell activation. In an influenza‐induced exacerbation of allergic airway inflammation model we noticed an initial reduction of ILC2 numbers and cytokine production in broncho‐alveolar lavage compared to chronic house dust mite (HDM)‐mediated airway inflammation alone. ILC2s phenotype was characterized by low T1/ST2, ICOS, KLRG1, and CD25 expression, resembling naïve ILC2s. The contribution of ILC2s to type 2 cytokine production in the early stage of the influenza‐induced exacerbation was limited. In contrast, T cells showed increased IL‐4 and IL‐5 production when exposed to both HDM and influenza virus. Upon virus clearance, ILC2s regained an activated T1/ST2^highICOS^highKLRG1^highCD25^high phenotype paired with cytokine production and were major contributors to the type 2 cytokine milieu. Collectively, our data indicate that both T cells and ILC2s contribute to influenza‐induced exacerbation of allergic airway inflammation, but with different kinetics.     

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.     

Histamine induces Th2 activation through the histamine receptor 1 in house dust mite rhinitic but not asthmatic patients

Background Effects of mast cell‐released histamine on smooth muscle and endothelial cells are considered as responsible of immediate symptoms of anaphylaxis. However, little is known about histamine effects on Th2 lymphocytes, which orchestrate the allergic reaction upstream of mast cells. Objective We addressed this question in house dust mite (HDM) allergics, according to the presence of rhinitis or asthma and allergen stimulation. Methods Peripheral blood mononuclear cell from 15 rhinitic and 14 asthmatic HDM‐allergic subjects and 16 controls were cultured with Der p 1 or histamine. The effect of Der p 1 on histamine receptor (H1R and H2R) expression was studied. T‐cell cytokine production was studied upon Der p 1 or histamine stimulation. The role of H1R in histamine effects was assessed with levocetirizine. Results H1R and H2R are overexpressed on T cells from asthmatic but not from rhinitic subjects. Der p 1 increases H1R expression on CD4⁺ cells from both allergic groups, and decreases it in controls, on CD4⁺ and CD8⁺ subsets. Der p 1 decreases T‐cell H2R expression in asthmatics. Allergen increases IL‐4 and IL‐13 in both allergic groups. Histamine increases Th2 cytokines in rhinitics only, and levocetirizine abolishes this effect. In asthmatics and controls, histamine decreases T‐cell cytokines through a non‐H1R dependent pathway. Conclusion In rhinitis but not in asthma, histamine is able to increase allergic inflammation by increasing Th2 cytokine production in a positive feedback dependent on H1R. This result could explain in part why H1R antagonists, are very efficient in rhinitis, but not in asthma. Cite this as: K. Botturi, Y. Lacoeuille, D. Vervloet and A. Magnan, Clinical & Experimental Allergy, 2010 (40) 755–762.     

Role of Galectin‐3 in the pathophysiology underlying allergic lung inflammation in a tissue inhibitor of metalloproteinases 1 knockout model of murine asthma

Asthma is a chronic inflammatory respiratory disease characterized by airway inflammation, airway hyperresponsiveness and reversible airway obstruction. Understanding the mechanisms that underlie the various endotypes of asthma could lead to novel and more personalized therapies for individuals with asthma. Using a tissue inhibitor of metalloproteinases 1 (TIMP‐1) knockout murine allergic asthma model, we previously showed that TIMP‐1 deficiency results in an asthma phenotype, exhibiting airway hyperreactivity, enhanced eosinophilic inflammation and T helper type 2 cytokine gene and protein expression following sensitization with ovalbumin. In the current study, we compared the expression of Galectins and other key cytokines in a murine allergic asthma model using wild‐type and TIMP‐1 knockout mice. We also examined the effects of Galectin‐3 (Gal‐3) inhibition on a non‐T helper type 2 cytokine interleukin‐17 (IL‐17) to evaluate the relationship between Gal‐3 and the IL‐17 axis in allergic asthma. Our results showed a significant increase in Gal‐3, IL‐17 and transforming growth factor‐β₁ gene expression in lung tissue isolated from an allergic asthma murine model using TIMP‐1 knockout. Gal‐3 gene and protein expression levels were also significantly higher in lung tissue from an allergic asthma murine model using TIMP‐1 knockout. Our data show that Gal‐3 may regulate the IL‐17 axis and play a pivotal role in the modulation of inflammation during experimental allergic asthma.     

Effects of furosemide on allergic asthmatic responses in mice

Background The syndrome of allergic asthma features reversible bronchoconstriction, airway inflammation and hyperresponsiveness as well as airway remodelling, including goblet cell hyperplasia. Managing severe asthma is still a clinical challenge. Numerous studies report that furosemide, an inhibitor of Na⁺–K⁺–Cl^? cotransporter (NKCC) reduces airway hyperresponsiveness (AHR) in asthmatic patients. However, the mechanism by which furosemide exerts anti‐asthmatic action remains unclear. Objective This study sought to investigate the cellular profile of NKCC1 expression in the lung and examine the effects of furosemide on several outcome measurements in a mouse model of allergic asthma. Methods Mice were sensitized and challenged with ovalbumin (OVA). Before challenge, the OVA‐sensitized mice were treated with furosemide (4.0 mg/kg/day, via daily intraperitoneal injection for 5 days). Outcome measurements in naïve, OVA‐exposure, furosemide‐treated naïve and furosemide‐treated OVA‐exposed mice included the slope of the relationship between inhaled methacholine (MCh) concentration and respiratory system resistance (Slope·R_RS), bronchoalveolar lavage (BAL) cell counts and immunohistochemical and immunoblotting assays of lung tissues. Results NKCC1 immunoreactivity was observed in airway epithelial cells (AECs) and alveolar type II (ATII) cells of the control mice. OVA exposure enhanced the expression of NKCC1 in AECs and ATII cells, and increased the infiltration of NKCC1‐expressing T lymphocytes in the lung. NKCC1 immunoreactivity was not detected in the airway smooth muscle (ASM) cells. Furosemide treatment reduced the Slope·R_RS in both naïve and OVA‐exposed mice by about 50%. Furosemide treatment also increased T lymphocyte infiltration to the lung in OVA‐exposed mice by approximately 53%, but had no effect on pulmonary goblet cell hyperplasia. Conclusions and Clinical Relevance Furosemide decreases basal airway responsiveness, thereby reducing the extent of allergen‐induced AHR. However, the same treatment also increases T lymphocytes infiltration in the course of allergic asthma. Further studies are necessary to address the usefulness of furosemide in the clinical treatment of asthma. Cite this as: S. Wang, Y.‐Y. Xiang, R. Ellis, J. Wattie, M. Feng, M. D. Inman and W.‐Y. Lu, Clinical & Experimental Allergy, 2011 (41) 1456–1467.     

Treatment with anti-CC chemokine receptor 3 monoclonal antibody or dexamethasone inhibits the migration and differentiation of bone marrow CD34 progenitor cells in an allergic mouse model

Background: The migration and in situ differentiation of CD34⁺ progenitors contribute to inflammatory eosinophilia in asthma and corticosteroids have been widely used in asthma. However, little is know about whether and how corticosteroids modulate the migration and differentiation of CD34⁺ progenitors. This study was aimed to investigate the impact of anti‐CC chemokine receptor 3 (CCR3) or dexamethasone on inflammatory eosinophilia in asthma and possible mechanism(s) underlying the action of dexamethasone or anti‐CCR3 on migration and differentiation of CD34⁺ progenitors in asthmatic context. Methods: Using an asthmatic mouse model, airway inflammation of anti‐CCR3‐ or dexamethasone‐treated mice and that of controls were characterized. And the migration and differentiation of CD34⁺ progenitor cells were analyzed in vivo, ex vivo or in vitro. Results: Treatment with anti‐CCR3 or dexamethasone significantly inhibited allergen‐induced eosinophilia and CD34⁺ progenitor cell infiltration in the lung, which was accompanied by lower levels of airway hyper‐responsiveness and mucus production. Moreover, anti‐CCR3 inhibited the eotaxin‐mediated migration and IL‐5/eotaxin‐induced differentiation of CD34⁺ progenitors in vitro. Dexamethasone was also shown to mitigate eotaxin‐mediated migration and IL‐5 or eotaxin‐promoted differentiation of CD34⁺ progenitor cells ex vivo, which were associated with the down‐regulation of CCR3 expression on bone marrow progenitor cells. Conclusions: Treatment with anti‐CCR3 or dexamethasone can inhibit the migration and differentiation of CD34⁺ progenitor cells by regulating the eotaxin/CCR3 axis in asthmatic mice. Our findings provide new insights into understanding the mechanism(s) underlying the action of dexamethasone and CCR3‐mediated signaling in allergic inflammation and aid in the design of new immunotherapy for intervention of human asthma.     

Effects of 4 months of smoking in mice with ovalbumin-induced airway inflammation

Background The effects of smoking on asthma pathogenesis are complex and not well studied. We have shown recently that 3 weeks of smoking attenuates ovalbumin (OVA)‐induced airway inflammation in mice and that 4–6 months of smoking induces emphysema in mice without airway inflammation. Effects of combined long‐term smoking and OVA exposure have not been investigated so far. Objective To study whether long‐term smoking affects progression of allergic airway inflammation and/or enhances the development of emphysema in mice. Methods Mice were sensitized to OVA and challenged with saline or OVA aerosols for 6 months. From 2 months onwards, mice were also exposed to air or smoke. Lung tissue was analysed for extent of inflammation, emphysema, remodelling and for cytokine levels, and serum for OVA‐specific IgE levels. Results Chronic OVA exposure of 6 months resulted in a T helper type 2 (Th2)‐type inflammation with increased levels of IL‐4, IL‐5, IL‐6 and infiltration of eosinophils, CD4⁺ T cells, macrophages and plasma cells. Smoking induced a Th17‐type of airway inflammation, characterized by neutrophils, macrophages, B cells and increased levels of IL‐17, IL‐6, granulocyte‐macrophage colony‐stimulating factor, granulocyte colony‐stimulating factor and monocyte chemoattractant protein‐1. Concomittant smoking and OVA exposure resulted in inflammation similar to OVA exposure alone. OVA exposure increased IgE levels compared with saline exposure, and smoking did not further increase these levels. Conclusion We did not find evidence for increased inflammation, IgE levels or emphysema in mice with allergic airway inflammation after 4 months of smoking compared with non‐smoking. However, a 4‐month exposure to smoke alone did enhance neutrophilic airway inflammation characterized by high pulmonary IL‐17 levels. A Th2 inflammatory environment due to OVA exposure may be one explanation as to why no further detrimental effects of smoking on allergic airway inflammation were found.     

General,but not myeloid or type II lung epithelial cell,myeloid differentiation factor 88 deficiency abrogates house dust mite induced allergic lung inflammation

Asthma is a highly prevalent chronic allergic inflammatory disease of the airways affecting people worldwide. House dust mite (HDM) is the most common allergen implicated in human allergic asthma. HDM‐induced allergic responses are thought to depend upon activation of pathways involving Toll‐like receptors and their adaptor protein myeloid differentiation factor 88 (MyD88). We sought here to determine the role of MyD88 in myeloid and type II lung epithelial cells in the development of asthma‐like allergic disease using a mouse model. Repeated exposure to HDM caused allergic responses in control mice characterized by influx of eosinophils into the bronchoalveolar space and lung tissue, lung pathology and mucus production and protein leak into bronchoalveolar lavage fluid. All these responses were abrogated in mice with a general deficiency of MyD88 but unaltered in mice with MyD88 deficiency, specifically in myeloid or type II lung epithelial cells. We conclude that cells other than myeloid or type II lung epithelial cells are responsible for MyD88‐dependent HDM‐induced allergic airway inflammation.     

An intranasal administration of Lactococcus lactis strains expressing recombinant interleukin‐10 modulates acute allergic airway inflammation in a murine model

Background Around 300 million people world‐wide suffer from asthma, and the prevalence of allergic diseases has increased. Much effort has been used in the study of mechanisms involved in the immune response observed in asthma to intervene for the treatment of this condition. During inflammation in asthma, Th2 cytokines and eosinophils are essential components of the host immune system. Furthermore, for therapeutic interventions against this disease, IL‐10 is an important cytokine because it has a central role in the regulation of inflammatory cascades. Objective To evaluate the immunomodulatory effect of Lactococcus lactis strains expressing recombinant IL‐10 in a mouse model of ovalbumin (OVA)‐induced acute airway inflammation. Methods L. lactis expressing recombinant IL‐10 in a cytoplasmic (LL‐CYT) or secreted form (LL‐SEC) and wild‐type (LL‐WT) were used. IL‐10 production by the recombinant strains was evaluated by ELISA. After an intranasal administration of L. lactis producing recombinant IL‐10 and the induction of acute allergic airway inflammation in mice, blood samples were collected to detect IgE anti‐OVA, and bronchoalveolar lavage (BAL) was harvested for eosinophil count. Additionally, the lungs were collected for the detection of the eosinophil peroxidase (EPO) activity, measurement of cytokines and chemokines and evaluation of pathology. Results Mice that received LL‐CYT and LL‐SEC strains showed a significant decrease in eosinophils numbers, EPO activity, anti‐OVA IgE and IgG1 levels, IL‐4 and CCL3 production and pulmonary inflammation and mucus hypersecretion, compared with the asthmatic group. Only the LL‐CYT/OVA group showed reduced levels of IL‐5, CCL2, CCL5 and CCL11. Conclusion Treatment with L. lactis producing recombinant IL‐10 used in this study (LL‐CYT and LL‐SEC) modulated experimental airway inflammation in the mouse model independently of Treg cells. Additionally, the LL‐CYT strain was more efficient in the suppression of lung inflammation. Cite this as: F. A. V. Marinho, L. G. G. Pacífico, A. Miyoshi, V. Azevedo, Y. Le Loir, V. D. Guimarães, P. Langella, G. D. Cassali, C. T. Fonseca and S. C. Oliveira, Clinical & Experimental Allergy, 2010 (40) 1541–1551.