Acute Asthma Model Research Articles

Effect of aging on airway remodeling and muscarinic receptors in a murine acute asthma model

Background and objectivesThe influence of aging on the development of asthma has not been studied thoroughly. The aim of this study was to investigate age-related airway responses involving lung histology and expression of muscarinic receptors in a murine model of acute asthma.MethodsFemale BALB/c mice at the ages of 6 weeks and 6, 9, and 12 months were sensitized and challenged with ovalbumin (OVA) for 1 month (n = 8–12 per group). We analyzed inflammatory cells and T-helper (Th)2 cytokines in bronchoalveolar lavage (BAL) fluid and parameters of airway remodeling and expression of muscarinic receptors in lung tissue.ResultsAmong the OVA groups, total cell and eosinophil numbers in BAL fluid were significantly higher in the older (6-, 9-, and 12-month-old) mice than in the young (6-week-old) mice. Interleukin (IL) 4 (IL-4) concentration increased, but IL-5 and IL-13 concentrations showed a decreased tendency, with age. IL-17 concentration tended to increase with age, which did not reach statistical significance. Periodic acid-Schiff (PAS) staining area, peribronchial collagen deposition, and area of α-smooth muscle staining were significantly higher in the 6-month older OVA group than in the young OVA group. The expression of the M3 and M2 muscarinic receptors tended to increase and decrease, respectively, with age.ConclusionThe aged mice showed an active and unique pattern not only on airway inflammation, but also on airway remodeling and expression of the muscarinic receptors during the development of acute asthma compared with the young mice. These findings suggest that the aging process affects the pathogenesis of acute asthma and age-specific approach might be more appropriate for better asthma control in a clinical practice.

Breast regression protein-39 (BRP-39) promotes dendritic cell maturation in vitro and enhances Th2 inflammation in murine model of asthma

To determine the roles of breast regression protein-39 (BRP-39) in regulating dendritic cell maturation and in pathology of acute asthma. Mouse bone marrow-derived dendritic cells (BMDCs) were prepared, and infected with adenovirus over-expressing BRP-39. Ovalbumin (OVA)-induced murine model of acute asthma was made in female BALB/c mice by sensitizing and challenging with chicken OVA and Imject Alum. The transfected BMDCs were adoptively transferred into OVA-treated mice via intravenous injection. Airway hyperresponsiveness (AHR), inflammation and pulmonary histopathology were characterized. The expression of BRP-39 mRNA and protein was significantly increased in lung tissues of OVA-treated mice. The BMDCs infected with adenovirus BRP-39 exhibited greater maturation and higher activity in vitro. Adoptive transfer of the cells into OVA-treated mice significantly augmented OVA-induced AHR and eosinophilic inflammation. Meanwhile, BRP-39 further enhanced the production of OVA-induced Th2 cytokines IL-4, IL-5 and IL-13, but significantly attenuated OVA-induced IFN-γ production in bronchoalveolar lavage fluid. In OVA-induced murine model of acute asthma, BRP-39 is over-expressed in lung tissue and augments Th2 inflammatory response and AHR. BRP-39 promotes dendritic cell maturation in vitro. Therefore, BRP-39 may be a potential therapeutic target of asthma.

Neuropeptides control the dynamic behavior of airway mucosal dendritic cells.

The airway mucosal epithelium is permanently exposed to airborne particles. A network of immune cells patrols at this interface to the environment. The interplay of immune cells is orchestrated by different mediators. In the current study we investigated the impact of neuronal signals on key functions of dendritic cells (DC). Using two-photon microscopic time-lapse analysis of living lung sections from CD11c-EYFP transgenic mice we studied the influence of neuropeptides on airway DC motility. Additionally, using a confocal microscopic approach, the phagocytotic capacity of CD11c+ cells after neuropeptide stimulation was determined. Electrical field stimulation (EFS) leads to an unspecific release of neuropeptides from nerves. After EFS and treatment with the neuropeptides vasoactive intestinal peptide (VIP) or calcitonin gene-related peptide (CGRP), airway DC in living lung slices showed an altered motility. Furthermore, the EFS-mediated effect could partially be blocked by pre-treatment with the receptor antagonist CGRP8–37. Additionally, the phagocytotic capacity of bone marrow-derived and whole lung CD11c+ cells could be inhibited by neuropeptides CGRP, VIP, and Substance P. We then cross-linked these data with the in vivo situation by analyzing DC motility in two different OVA asthma models. Both in the acute and prolonged OVA asthma model altered neuropeptide amounts and DC motility in the airways could be measured. In summary, our data suggest that neuropeptides modulate key features motility and phagocytosis of mouse airway DC. Therefore altered neuropeptide levels in airways during allergic inflammation have impact on regulation of airway immune mechanisms and therefore might contribute to the pathophysiology of asthma.

Grape Seed Proanthocyanidin Extract Attenuates Allergic Inflammation in Murine Models of Asthma

Antioxidants have been suggested to alleviate the pathophysiological features of asthma, and grape seed proanthocyanidin extract (GSPE) has been reported to have powerful antioxidant activity. This study was performed to determine whether GSPE has a therapeutic effect on allergic airway inflammation in both acute and chronic murine model of asthma. Acute asthma model was generated by intraperitoneal sensitization of ovalbumin (OVA) with alum followed by aerosolized OVA challenges, whereas chronic asthma model was induced by repeated intranasal challenges of OVA with fungal protease twice a week for 8weeks. GSPE was administered by either intraperitoneal injection or oral gavage before OVA challenges. Airway hyperresponsiveness (AHR) was measured, and airway inflammation was evaluated by bronchoalveolar lavage (BAL) fluid analysis and histopathological examination of lung tissue. Lung tissue levels of various cytokines, chemokines, and growth factors were analyzed by quantitative polymerase chain reaction and ELISA. Glutathione assay was done to measure oxidative burden in lung tissue. Compared to untreated asthmatic mice, mice treated with GSPE showed significantly reduced AHR, decreased inflammatory cells in the BAL fluid, reduced lung inflammation, and decreased IL-4, IL-5, IL-13, and eotaxin-1 expression in both acute and chronic asthma models. Moreover, airway subepithelial fibrosis was reduced in the lung tissue of GSPE-treated chronic asthmatic mice compared to untreated asthmatic mice. Reduced to oxidized glutathione (GSH/GSSG) ratio was increased after GSPE treatment in acute asthmatic lung tissue. GSPE effectively suppressed inflammation in both acute and chronic mouse models of asthma, suggesting a potential role of GSPE as a therapeutic agent for asthma.

Volatile Organic Compounds Enhance Allergic Airway Inflammation in an Experimental Mouse Model

BackgroundEpidemiological studies suggest an association between exposure to volatile organic compounds (VOCs) and adverse allergic and respiratory symptoms. However, whether VOCs exhibit a causal role as adjuvants in asthma development remains unclear.MethodsTo investigate the effect of VOC exposure on the development of allergic airway inflammation Balb/c mice were exposed to VOCs emitted by new polyvinylchloride (PVC) flooring, sensitized with ovalbumin (OVA) and characterized in acute and chronic murine asthma models. Furthermore, prevalent evaporated VOCs were analyzed and mice were exposed to selected single VOCs.ResultsExposure of mice to PVC flooring increased eosinophilic lung inflammation and OVA-specific IgE serum levels compared to un-exposed control mice. The increased inflammation was associated with elevated levels of Th2-cytokines. Long-term exposure to PVC flooring exacerbated chronic airway inflammation. VOCs with the highest concentrations emitted by new PVC flooring were N-methyl-2-pyrrolidone (NMP) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB). Exposure to NMP or TXIB also increased the allergic immune response in OVA-sensitized mice. In vitro or in vivo exposure to NMP or TXIB reduced IL-12 production in maturing dendritic cells (DCs) and enhanced airway inflammation after adoptive DC transfer into Balb/c mice. At higher concentrations both VOCs induced oxidative stress demonstrated by increased isoprostane and glutathione-S-transferase-pi1 protein levels in the lung of non-sensitized mice. Treatment of PVC flooring-exposed mice with N-acetylcysteine prevented the VOC-induced increase of airway inflammation.ConclusionsOur results demonstrate that exposure to VOCs may increase the allergic immune response by interfering with DC function and by inducing oxidative stress and has therefore to be considerate as risk factor for the development of allergic diseases.

Interleukin-13 peptide kinoid vaccination attenuates allergic inflammation in a mouse model of asthma

Asthma is an atopic disorder with increasing frequency and severity in developed nations. Interleukin-13 (IL-13) is one of the most critical mediators of asthma pathology. In the present study, we developed a vaccine comprised of a keyhole limpet hemocyanin-mIL-13 heterocomplex immunogen to persistently neutralize excessive endogenous IL-13. Our results showed that the IL-13 peptide kinoid vaccine could induce sustained and high titer of IL-13-specific IgG when using aluminum hydroxide as an adjuvant, and could suppress the accumulation of eosinophils as well as IL-13 levels in bronchoalveolar lavage fluid (BALF). In addition, total IgE and ovalbumin (OVA)-specific IgE in serum were significantly inhibited. This study also showed that vaccination could prevent airway inflammation and epithelial cell proliferation with goblet cell hyperplasia in a mouse model of acute asthma. In summary, our findings suggest that the IL-13 peptide kinoid can serve as an innovative and effective vaccine against asthma.

Effect of tiotropium bromide on airway remodeling in a chronic asthma model

BackgroundRecent evidence suggests that acetylcholine acting through muscarinic receptors may play an inhibitory role in the mechanisms that drive the structural changes in the airways called airway remodeling. The novel anticholinergic drug tiotropium bromide, which selectively antagonizes muscarinic receptors, especially the M3 subtype, and is long acting, could be beneficial in attenuating airway remodeling in chronic asthma. ObjectiveTo investigate the effect of tiotropium bromide on parameters of airway remodeling, including smooth muscle hypertrophy and peribronchial thickening, in a mouse model of chronic asthma. MethodsTo develop the murine models of acute and chronic asthma, BALB/c mice were sensitized and challenged to ovalbumin for 1 and 3 months, respectively. The effect of tiotropium bromide (0.1mM in 50 μL of phosphate-buffered saline) on pulmonary inflammation and remodeling was evaluated. The expression of muscarinic receptors M2 and M3 was analyzed. ResultsIn the chronic asthma model, the tiotropium-treated group significantly decreased smooth muscle thickening and peribronchial collagen deposition. As for pulmonary inflammation, the chronic asthma model had a reduction of inflammatory cells and TH2 cytokines by tiotropium bromide, but the effects in the asthma acute model were reversed. In the chronic asthma model, expression of the M3 receptor was inhibited and that of the M2 receptor was elevated by the administration of tiotropium bromide. ConclusionThis study suggests that tiotropium bromide might have an inhibitory effect on airway remodeling in a murine model of chronic asthma. Differential effects on muscarinic receptor subtypes may explain why tiotropium bromide has different effects on acute and chronic asthma.

MicroRNA-181a, -146a and -146b in spleen CD4+ T lymphocytes play proinflammatory roles in a murine model of asthma

CD4+ T lymphocytes can be primarily polarized to differentiate into Th2 cells, and are heavily involved in the Th2 inflammation of asthma. Little is known about the correlation between microRNAs and Th2 inflammation in asthma, therefore we explore the roles of five microRNAs (microRNA-181a, -155, -150, -146a and -146b) in Th2 inflammation of asthma by tracking their expression levels in splenic CD4+ T lymphocytes under different conditions. Using quantitative real-time polymerase chain reaction (qPCR), the dynamic changes of these microRNAs in murine models of acute asthma (i.e. the OVA group) were analyzed, in comparison to a control group. The effects of dexamethasone on the miRNA expression levels were also investigated. The results showed that the expression levels of microRNA-181a, -150, -146a and -146b were higher in the OVA group compared to the control group in the beginning of the disease, and after 5days dropped to control group levels because there was no new airway challenge. Moreover, the miRNA-146a expression was down-regulated by treatment with dexamethasone. MicroRNA-181a had a positive linear correlation with the numbers of inflammatory cells (i.e. the numbers of total cells or of the eosinophils in the BALF) by Spearman correlation analysis, so did miRNA-146a and miRNA-146b. These observations suggest that microRNA-181a, -146a and -146b are proinflammatory factors in asthma, and that down-regulation of miRNA-146a may partially account for the anti-inflammatory effect of dexamethasone.

Allergic Eosinophils Alter Immune Responses to Influenza A Virus. (49.24)

Abstract WHO estimates that 235 million people globally suffer from asthma, which was among the important risk factors for hospitalization during the 2009 influenza pandemic. Using a novel co-morbidity model of acute allergic asthma and influenza, we demonstrate that mice with acute asthma are protected from influenza-induced morbidity. Asthmatic mice did not lose weight or exhibit typical, severe, clinical signs of infection. In spite of having a greater infiltration of cells into the airways, these mice had suppressed Th1- and Th2-type cytokines compared to flu-only controls. Resistin-like molecules were highly expressed during early timepoints that correlated with eosinophil influx indicating that responding eosinophils may be mediating protection against influenza. Eosinophils were harvested from allergic airways and adoptively transferred to matched mice infected with pandemic influenza virus. Eosinophil transfer into flu-infected non-allergic mice markedly altered cellular influx into the airways. Significantly more CD4+ Th2 lymphocytes, macrophages, neutrophils, and eosinophils were present compared to control mice. Viral titers were reduced 5 days after eosinophil transfer, and the host immune response was altered. We conclude that allergy-induced eosinophils modulate immune responses to influenza virus. The role of eosinophils in protecting the acutely allergen-sensitized host from viral mediated immunopathology merits further investigation.

Synergistic Effect of Cysteinyl Leukotriene Receptor Antagonist and H‐1 Receptor Antagonist in Acute and Chronic Guinea Pig Asthma Models

Histamine and cysteinyl leukotrienes are pivotal mast cell mediators which contribute considerably and likely complementary to the symptoms of asthma. The present study hypothesized to explore the direct actions of histamine and cysteinyl leukotrienes, on acute platelet activating factor and chronic Ovalbumin induced guinea pig asthma models. In our In‐ vivo guinea pig studies, oral levocetrizine (0.1mg/kg) and montelukast (0.1mg/kg) had significantly reduced antigen‐induced total leukocyte count and eosinophil count. Similarly, the dose–response characteristics of montelukast (0.1–10mg/kg) was observed against ovalbumin induced guinea pig asthma model. Our studies support the position that histamine and cysteinyl leukotrienes may act collaboratively to elicit infiltration of leukocytes especially eosinophils are the target to treat asthma. Levocetrizine and Montelukast had reduction in IL‐4 &IL‐5 in bronchoalveolar lavage fluid. Combination of levocetrizine and montelukast had produces synergistic effect in both models. Therefore, this combination may therefore useful for treating airway inflammation in bronchial asthma.

The Role of Natural Killer T Cells in the Pathogenesis of Acute Exacerbation of Human Asthma

Background: Natural killer T (NKT) cells have been reported to play a crucial role in the pathogenesis of asthma in a mouse model of acute asthma. The present study aimed to investigate the role of NKT cells in the immune pathogenesis of acute exacerbation of human asthma. Methods: Blood and sputum were obtained at baseline and 8 h after a challenge in 20 asthmatics who underwent allergen bronchial provocation testing and during exacerbation and convalescence in 9 asthmatics who were admitted to hospital with an acute exacerbation after an upper respiratory tract infection. 6B11+ or Vα24+ NKT cells were measured with flow cytometry. Inflammatory cells, cytokines and chemokines were determined in sputum. Results: The number of blood NKT cells did not change after a positive allergen challenge compared to the baseline. However, blood CD4+Vα24+ NKT cells decreased during infection-associated asthma exacerbations compared to the convalescence measurements of the same patients (p < 0.05) or the baseline measurements of asthmatics who underwent allergen challenges (p < 0.01). The number of sputum NKT cells did not change after a positive allergen challenge or during infection-associated asthma exacerbations. Eosinophils and various cytokines and chemokines increased in sputum during infection-associated asthma exacerbations. Blood CD4+Vα24+ NKT cells were inversely related to sputum eosinophils (Spearman’s correlation coefficient = –0.62; p < 0.01). Conclusion: Blood NKT cells decreased during infection-associated asthma exacerbation and were inversely associated with eosinophilic airway inflammation, suggesting that blood NKT cells might be mobilized to the airways and lungs during asthma exacerbation in humans.

Airway dendritic cell behaviour is influenced by neuropeptide release from sensory nerves

The airway mucosal epithelium permanently faces airborne particles. A network of immune cells patrols at this frontier to the environmental surface. The interplay of immune cells is orchestrated by different mediators. In the current study we questioned whether neuropeptides can alter key features of DC as there are movement behavior and phagocytosis capacity. With a two-photon microscopic time-lapse analysis of DC in the airways of ex vivo vital lung sections of CD11c-EYFP transgenic mice we focused on the influence of neuropeptides on dendritic cells (DC). Additionally, with a confocal microscopic approach and by means of particles being fluorescent in the phagolysosomal milieu we determined the phagocytosis capacity of CD11c+ cells. Irritation, here mimicked by electrical field stimulation (EFS) leads to an unspecific release of several neuropeptides from nerves. After EFS of vital lung slices, airway DC showed an increased motility. In subsequent experiments this effect could be reproduced by specific application of the neuropeptide calcitonin gene-related peptide (CGRP). In contrast, the application of the neuropeptide vasoactive intestinal peptide (VIP) led to a decrease of airway DC motility. Furthermore, the EFS-mediated effect could specifically be blocked by pre-treatment with the neuropeptide receptor antagonist CGRP8–37. Additionally, neuropeptides CGRP, VIP and Substance P (SP) negatively affected the phagocytosis capacity of bone marrow-derived and whole lung CD11c+ cells. We then cross-linked these data with the in vivo situation by analysing DC motility in two different asthma models. Both in the acute and prolonged asthma model we could determine altered neuropeptide content in the airways combined with a differenzial DC motility. In summary, these data suggest that neuropeptides alter key features motility and phagocytosis of mouse airway DC. Furthermore we presume that neuropeptides are responsible for fine-tuning of DC behaviour in the airways upon external stimuli. This work was funded by SFB587.

Intra-airway administration of small interfering RNA targeting plasminogen activator inhibitor-1 attenuates allergic asthma in mice

Recent studies suggest that plasminogen activator inhibitor-1 (PAI-1), a major inhibitor of the fibrinolytic system, may promote the development of asthma. To further investigate the significance of PAI-1 in the pathogenesis of asthma and determine the possibility that PAI-1 could be a therapeutic target for asthma, this study was conducted. First, PAI-1 levels in induced sputum (IS) from asthmatic subjects and healthy controls were measured. In asthmatic subjects, IS PAI-1 levels were elevated, compared with that of healthy controls, and were significantly higher in patients with long-duration asthma compared with short-duration asthma. PAI-1 levels were also found to correlate with IS transforming growth factor-β levels. Then, acute and chronic asthma models induced by ovalbumin were established in PAI-1-deficient mice and wild-type mice that received intra-airway administrations of small interfering RNA against PAI-1 (PAI-1-siRNA). We could demonstrate that eosinophilic airway inflammation and airway hyperresponsiveness were reduced in an acute asthma model, and airway remodeling was suppressed in a chronic asthma model in both PAI-1-deficient mice and wild-type mice that received intra-airway administration of PAI-1-siRNA. These results indicate that PAI-1 is strongly involved in the pathogenesis of asthma, and intra-airway administration of PAI-1-siRNA may be able to become a new therapeutic approach for asthma.

Airway Delivery of Soluble Factors from Plastic-Adherent Bone Marrow Cells Prevents Murine Asthma

Asthma affects an estimated 300 million people worldwide and accounts for 1 of 250 deaths and 15 million disability-adjusted life years lost annually. Plastic-adherent bone marrow-derived cell (BMC) administration holds therapeutic promise in regenerative medicine. However, given the low cell engraftment in target organs, including the lung, cell replacement cannot solely account for the reported therapeutic benefits. This suggests that BMCs may act by secreting soluble factors. BMCs also possess antiinflammatory and immunomodulatory properties and may therefore be beneficial for asthma. Our objective was to investigate the therapeutic potential of BMC-secreted factors in murine asthma. In a model of acute and chronic asthma, intranasal instillation of BMC conditioned medium (CdM) prevented airway hyperresponsiveness (AHR) and inflammation. In the chronic asthma model, CdM prevented airway smooth muscle thickening and peribronchial inflammation while restoring blunted salbutamol-induced bronchodilation. CdM reduced lung levels of the T(H)2 inflammatory cytokines IL-4 and IL-13 and increased levels of IL-10. CdM up-regulated an IL-10-induced and IL-10-secreting subset of T regulatory lymphocytes and promoted IL-10 expression by lung macrophages. Adiponectin (APN), an antiinflammatory adipokine found in CdM, prevented AHR, airway smooth muscle thickening, and peribronchial inflammation, whereas the effect of CdM in which APN was neutralized or from APN knock-out mice was attenuated compared with wild-type CdM. Our study provides evidence that BMC-derived soluble factors prevent murine asthma and suggests APN as one of the protective factors. Further identification of BMC-derived factors may hold promise for novel approaches in the treatment of asthma.

Mepyramine–JNJ7777120-hybrid compounds show high affinity to hH1R, but low affinity to hH4R

In literature, a synergism between histamine H(1) and H(4) receptor is discussed. Furthermore, it was shown, that the combined application of mepyramine, a H(1) antagonist and JNJ7777120, a H(4) receptor ligand leads to a synergistic effect in the acute murine asthma model. Thus, the aim of this study was to develop new hybrid ligands, containing one H(1) and one H(4) pharmacophor, connected by an appropriate spacer, in order to address both, H(1)R and H(4)R. Within this study, we synthesized nine hybrid compounds, which were pharmacologically characterized at hH(1)R and hH(4)R. The new compounds revealed (high) affinity to hH(1)R, but showed only low affinity to hH(4)R. Additionally, we performed molecular dynamic studies for some selected compounds at hH(1)R, in order to obtain information about the binding mode of these compounds on molecular level.

Acute severe asthma

Exacerbation of asthma can be seen during air transport. Severe patients, not responding to conventional therapy, require ventilator support. We evaluated the performance of two transport ventilators, built with turbine technology, the T-birdVSO2 and the LTV-1000, for use during aeromedical evacuation of acute severe asthma. We have assessed the ability of both the ventilators to deliver to an acute severe asthma model a tidal volume (Vt) set at different simulated altitudes, by changing the ambient air pressure. The simulated cabin altitudes were 1500, 2500, and 3000 m (decompression chamber). Vt was set at 700 and 400 ml in an acute severe asthma lung model. Comparisons of the preset with the actual measured values were accomplished using a t-test. Comparisons between the actual delivered Vt and set Vt showed a significant difference starting at 1500 m for both the ventilators. The T-birdVSO2 showed a decrease in the volume delivered, with a negative variation of more than 10% compared with the Vt set. The LTV-1000 showed mostly an increase in the volume delivered. The delivered Vt remained within 10% of the set Vt. The accuracy of Vt delivery was superior with the LTV-1000 than with the T-birdVSO2, but the higher delivered Vt of the LTV-1000 are likely to be more harmful than lower delivered Vt of the T-birdVSO2.

Effect of short-term oral and inhaled corticosteroids on airway inflammation and responsiveness in a feline acute asthma model

The objective of this study was to investigate whether high-dose inhaled fluticasone propionate (FP), alone or in combination with salmeterol (SAL), is as effective as oral prednisolone in reducing airway inflammation and obstruction in cats with experimentally-induced acute asthma. Six cats sensitised to Ascaris suum (AS) were enrolled in a prospective controlled therapeutic trial and underwent four aerosol challenges, at 1-month intervals with AS allergen. The allergen - stimulated animals received four consecutive days treatment with either oral prednisolone at 1mg/kg twice daily, 500 μg of FP inhaled twice daily, or a combination of FP/SAL at 500 μg/50 μg inhaled twice daily, respectively, according to a randomised cross-over design. Treatment-related changes in lung function, airway responsiveness (AR) and bronchoalveolar lavage fluid (BALF) cytology were assessed. Barometric whole-body plethysmography (BWBP) was used for the assessment of respiratory variables and AR. No significant differences in respiratory rate or Penh (an estimate of airflow limitation measured by BWBP) were detected among treatment groups. Allergen-induced airway hyper-responsiveness was significantly inhibited by all three steroid treatments (P<0.05). The mean BALF eosinophil percentage (±SEM) was lower after oral and inhaled corticosteroid treatment and these changes were significant for groups receiving prednisolone and the FP/SAL combination. Findings suggest high-dose FP, particularly in combination with SAL, is effective in ameliorating airway inflammation and hyper-responsiveness in this model of acute feline asthma, and highlight the potential use of these drugs in cats experiencing acute exacerbations of the naturally occurring disease.

MicroRNAs Profiling in Murine Models of Acute and Chronic Asthma: A Relationship with mRNAs Targets

BackgroundmiRNAs are now recognized as key regulator elements in gene expression. Although they have been associated with a number of human diseases, their implication in acute and chronic asthma and their association with lung remodelling have never been thoroughly investigated.Methodology/Principal FindingsIn order to establish a miRNAs expression profile in lung tissue, mice were sensitized and challenged with ovalbumin mimicking acute, intermediate and chronic human asthma. Levels of lung miRNAs were profiled by microarray and in silico analyses were performed to identify potential mRNA targets and to point out signalling pathways and biological processes regulated by miRNA-dependent mechanisms. Fifty-eight, 66 and 75 miRNAs were found to be significantly modulated at short-, intermediate- and long-term challenge, respectively. Inverse correlation with the expression of potential mRNA targets identified mmu-miR-146b, -223, -29b, -29c, -483, -574-5p, -672 and -690 as the best candidates for an active implication in asthma pathogenesis. A functional validation assay was performed by cotransfecting in human lung fibroblasts (WI26) synthetic miRNAs and engineered expression constructs containing the coding sequence of luciferase upstream of the 3′UTR of various potential mRNA targets. The bioinformatics analysis identified miRNA-linked regulation of several signalling pathways, as matrix metalloproteinases, inflammatory response and TGF-β signalling, and biological processes, including apoptosis and inflammation.Conclusions/SignificanceThis study highlights that specific miRNAs are likely to be involved in asthma disease and could represent a valuable resource both for biological makers identification and for unveiling mechanisms underlying the pathogenesis of asthma.

Immunoregulatory role of secretory leukocyte protease inhibitor in allergic asthma

Results Allergic SLPI transgenic mice showed a significant decrease in airway resistance compared to wild-type mice (6.3 ± 1.1 vs. 8.0 ± 2.1 cm H20 × s/ml, p < 0.001), the same effect was observed with inflammatory cell infiltration, eosinophil percentage (24 ± 1.1% vs. 29 ± 2.3%, p < 0.001), goblet cells (6 ± 1.4 vs. 36 ± 4.0%, p < 0.001) in the lungs and IgE levels (2014.1 ± 309.2 vs. 4173.2 ± 685.6 ng/ml, p < 0.001) in plasma. Allergic SLPI knock-out mice displayed significantly higher values compared to wild-type mice. They include lung resistance (8.6 ± 2.7 vs. 6.6 ± 0.5 cm H20*s/ml, p < 0.001), inflammatory cell influx, eosinophils (36.0 ± 2.7 vs. 29.0 ± 1.5%, p < 0.001), goblet cells (40 ± 4.1 vs. 30 ± 1.4%, p < 0.001), cytokine levels in the lungs (p < 0.05) and plasma IgE levels (3598 ± 204.7 vs. 2763 ± 220.3 ng/ml, p < 0.001). Expression of SLPI decreased inflammation in the lungs, plasma IgE levels, and lung resistance, whereas the ablation of SLPI has the opposite effect. Treatment with resiquimod improved airway resistance and inflammation of the lungs in SLPI knockout and wild type, demonstrating that its effect is independent of the expression of SLPI. Conclusions SLPI plays an immunoregulatory role in the respiratory tract by reducing the inflammatory process and by improving lung physiology in a murine model of acute allergic asthma.

A crucial role of sialidase Neu1 in hyaluronan receptor function of CD44 in T helper type 2-mediated airway inflammation of murine acute asthmatic model

CD44 is a highly glycosylated cell adhesion molecule that is involved in lymphocyte infiltration of inflamed tissues. We have demonstrated previously that sialic acid residues of CD44 negatively regulates its receptor function and CD44 plays an important role in the accumulation of T helper type 2 (Th2) cells in the airway of a murine model of acute asthma. Here we evaluated the role of sialidase in the hyaluronic acid (HA) receptor function of CD44 expressed on CD4+ T cells, as well as in the development of a mite antigen-induced murine model of acute asthma. Splenic CD4+ T cell binding of HA was examined with flow cytometry. Expression of sialidases (Neu1, Neu2, Neu3 and Neu4) in spleen cells was evaluated by quantitative real-time reverse transcription-polymerase chain reaction. Airway inflammation and airway hyperresponsiveness (AHR) were evaluated in the asthmatic Neu1-deficient mouse strain SM/J model. Splenic CD4+ T cells from asthmatic model mice displayed increased HA receptor activity of CD44 after culture with the antigen, along with characteristic parallel induction of sialidase (Neu1) expression. This induction of HA binding was suppressed significantly by a sialidase inhibitor and was not observed in SM/J mice. Th2 cytokine concentration and absolute number of Th2 cells in the bronchoalveolar lavage fluid, and AHR were decreased in SM/J mice. In conclusion, HA receptor activity of CD44 and acute asthmatic reactions, including Th2-mediated airway inflammation and AHR, are dependent upon Neu1 enzymatic activity. Our observation suggests that Neu1 may be a target molecule for the treatment of asthma.