Effect of adenosine A2A receptor activation in murine models of respiratory disorders

Activation of the adenosine A(2A) receptor has been postulated as a possible treatment for lung inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD). In this report, we have studied the anti-inflammatory properties of the reference A(2A) agonist CGS-21680, given intranasally at doses of 10 and 100 microg/kg, in a variety of murine models of asthma and COPD. After an acute ovalbumin challenge of sensitized mice, prophylactic administration of CGS-21680 inhibited the bronchoalveolar lavage fluid inflammatory cell influx but not the airway hyperreactivity to aerosolized methacholine. After repeated ovalbumin challenges, CGS-21680 given therapeutically inhibited the bronchoalveolar lavage fluid inflammatory cell influx but had no effect on the allergen-induced bronchoconstriction, the airway hyperreactivity, or the bronchoalveolar lavage fluid mucin levels. As a comparator, budesonide given intranasally at doses of 0.1-1 mg/kg fully inhibited all the parameters measured in the latter model. In a lipopolysaccharide-driven model, CGS-21680 had no effect on the bronchoalveolar lavage fluid inflammatory cell influx or TNF-alpha, keratinocyte chemoattractant, and macrophage inflammatory protein-2 levels, but potently inhibited neutrophil activation, as measured by bronchoalveolar lavage fluid elastase levels. With the use of a cigarette smoke model of lung inflammation, CGS-21680 did not significantly inhibit bronchoalveolar lavage fluid neutrophil infiltration but reversed the cigarette smoke-induced decrease in macrophage number. Together, these results suggest that activation of the A(2A) receptor would have a beneficial effect by inhibiting inflammatory cell influx and downregulating inflammatory cell activation in asthma and COPD, respectively.     

Neutrophil elastase induces mucus cell metaplasia in mouse lung

Goblet cell hyperplasia in the superficial airway epithelia is a signature pathological feature of chronic bronchitis and cystic fibrosis. In these chronic inflammatory airway diseases, neutrophil elastase (NE) is found in high concentrations in the epithelial lining fluid. NE has been reported to trigger mucin secretion and increase mucin gene expression in vitro. We hypothesized that chronic NE exposure to murine airways in vivo would induce goblet cell metaplasia. Human NE (50 microg) or PBS saline was aspirated intratracheally by male Balb/c (6 wk of age) mice on days 1, 4, and 7. On days 8, 11, and 14, lung tissues for histology and bronchoalveolar lavage (BAL) samples for cell counts and cytokine levels were obtained. NE induced Muc5ac mRNA and protein expression and goblet cell metaplasia on days 8, 11, and 14. These cellular changes were the result of proteolytic activity, since the addition of an elastase inhibitor, methoxysuccinyl Ala-Ala-Pro-Val chloromethylketone (AAPV-CMK), blocked NE-induced Muc5ac expression and goblet cell metaplasia. NE significantly increased keratinocyte-derived chemokine and IL-5 in BAL and increased lung tissue inflammation and BAL leukocyte counts. The addition of AAPV-CMK reduced these measures of inflammation to control levels. These experiments suggest that NE proteolytic activity initiates an inflammatory process leading to goblet cell metaplasia.     

High-dose but not low-dose mainstream cigarette smoke suppresses allergic airway inflammation by inhibiting T cell function

Epidemiological studies have identified childhood exposure to environmental tobacco smoke as a significant risk factor for the onset and exacerbation of asthma, but studies of smoking in adults are less conclusive, and mainstream cigarette smoke (MCS) has been reported to both enhance and attenuate allergic airway inflammation in animal models. We sensitized mice to ovalbumin (OVA) and exposed them to MCS in a well-characterized exposure system. Exposure to MCS (600 mg/m(3) total suspended particulates, TSP) for 1 h/day suppresses the allergic airway response, with reductions in eosinophilia, tissue inflammation, goblet cell metaplasia, IL-4 and IL-5 in bronchoalveolar lavage (BAL) fluid, and OVA-specific antibodies. Suppression is associated with a loss of antigen-specific proliferation and cytokine production by T cells. However, exposure to a lower dose of MCS (77 mg/m(3) TSP) had no effect on the number of BAL eosinophils or OVA-specific antibodies. This is the first report to demonstrate, using identical smoking methodologies, that MCS inhibits immune responses in a dose-dependent manner and may explain the observation that, although smoking provokes a systemic inflammatory response, it also inhibits T cell-mediated responses involved in a number of diseases.     

Aggravation of Allergic Airway Inflammation by Cigarette Smoke in Mice Is CD44-Dependent

Background

Although epidemiological studies reveal that cigarette smoke (CS) facilitates the development and exacerbation of allergic asthma, these studies offer limited information on the mechanisms involved. The transmembrane glycoprotein CD44 is involved in cell adhesion and acts as a receptor for hyaluronic acid and osteopontin. We aimed to investigate the role of CD44 in a murine model of CS-facilitated allergic airway inflammation.

Methods

Wild type (WT) and CD44 knock-out (KO) mice were exposed simultaneously to house dust mite (HDM) extract and CS. Inflammatory cells, hyaluronic acid (HA) and osteopontin (OPN) levels were measured in bronchoalveolar lavage fluid (BALF). Proinflammatory mediators, goblet cell metaplasia and peribronchial eosinophilia were assessed in lung tissue. T-helper (Th) 1, Th2 and Th17 cytokine production was evaluated in mediastinal lymph node cultures.

Results

In WT mice, combined HDM/CS exposure increased the number of inflammatory cells and the levels of HA and OPN in BALF and Th2 cytokine production in mediastinal lymph nodes compared to control groups exposed to phosphate buffered saline (PBS)/CS, HDM/Air or PBS/Air. Furthermore, HDM/CS exposure significantly increased goblet cell metaplasia, peribronchial eosinophilia and inflammatory mediators in the lung. CD44 KO mice exposed to HDM/CS had significantly fewer inflammatory cells in BALF, an attenuated Th2 cytokine production, as well as decreased goblet cells and peribronchial eosinophils compared to WT mice. In contrast, the levels of inflammatory mediators were similar or higher than in WT mice.

Conclusion

We demonstrate for the first time that the aggravation of pulmonary inflammation upon combined exposure to allergen and an environmental pollutant is CD44-dependent. Data from this murine model of concomitant exposure to CS and HDM might be of importance for smoking allergic asthmatics.     

Inhibition of Th1- and Th2-mediated airway inflammation by the sphingosine 1-phosphate receptor agonist FTY720

The sphingosine 1-phosphate receptor agonist FTY720 is a novel immunomodulator that sequesters lymphocytes in secondary lymphoid organs and thereby prevents their migration to sites of inflammation. However, there is currently no information available on whether this drug affects Th1 or Th2 cell-mediated lung-inflammatory responses. The effect of FTY720 was therefore investigated in a murine airway inflammation model using OVA-specific, in vitro differentiated, and adoptively transferred Th1 and Th2 cells. Both Th1 and Th2 cells express a similar pattern of FTY720-targeted sphingosine 1-phosphate receptors. The OVA-induced Th1-mediated airway inflammation characterized by increased numbers of lymphocytes and neutrophils in bronchoalveolar lavage fluid was significantly inhibited by oral FTY720 treatment. Similarly, FTY720 suppressed the Th2 cell-induced bronchoalveolar lavage fluid eosinophilia and the infiltration of T lymphocytes and eosinophils into the bronchial tissue. Moreover, the Ag-induced bronchial hyperresponsiveness to inhaled metacholine was almost completely blocked. The inhibitory effect of FTY720 on airway inflammation, induction of bronchial hyperresponsiveness, and goblet cell hyperplasia could be confirmed in an actively Ag-sensitized murine asthma model, clearly indicating that Th2 cell-driven allergic diseases such as asthma could benefit from such treatment.     

Role of CXCR2 in cigarette smoke-induced lung inflammation

It has been hypothesized that the destruction of lung tissue observed in smokers with chronic obstructive pulmonary disease and emphysema is mediated by neutrophils recruited to the lungs by smoke exposure. This study investigated the role of the chemokine receptor CXCR2 in mediating neutrophilic inflammation in the lungs of mice acutely exposed to cigarette smoke. Exposure to dilute mainstream cigarette smoke for 1 h, twice per day for 3 days, induced acute inflammation in the lungs of C57BL/6 mice, with increased neutrophils and the neutrophil chemotactic CXC chemokines macrophage inflammatory protein (MIP)-2 and KC. Treatment with SCH-N, an orally active small molecule inhibitor of CXCR2, reduced the influx of neutrophils into the bronchoalveolar lavage (BAL) fluid. Histological changes were seen, with drug treatment reducing perivascular inflammation and the number of tissue neutrophils. beta-Glucuronidase activity was reduced in the BAL fluid of mice treated with SCH-N, indicating that the reduction in neutrophils was associated with a reduction in tissue damaging enzymes. Interestingly, whereas MIP-2 and KC were significantly elevated in the BAL fluid of smoke exposed mice, they were further elevated in mice exposed to smoke and treated with drug. The increase in MIP-2 and KC with drug treatment may be due to the decrease in lung neutrophils that either are not present to bind these chemokines or fail to provide a feedback signal to other cells producing these chemokines. Overall, these results demonstrate that inhibiting CXCR2 reduces neutrophilic inflammation and associated lung tissue damage due to acute cigarette smoke exposure.     

IL-4 induces mucin gene expression and goblet cell metaplasia in vitro and in vivo

Goblet cell metaplasia and mucus hypersecretion are important features in the pathogenesis of asthma. The cytokine IL-4 has been shown to play a role in animal models of asthma, where it induces Th2 lymphocyte differentiation and B lymphocyte IgE class switch. IL-4 has also been implicated in the differentiation of goblet cells via effects on lymphocytes and eosinophils. In this study we hypothesized that IL-4 induces airway epithelial cell mucin gene expression and mucous glycoconjugate production by direct action on these cells. In vitro, cultured airway epithelial cells (NCI-H292) expressed IL-4R constitutively, and IL-4 (10 ng/ml) induced MUC2 gene expression and mucous glycoconjugate production. In vivo, mouse airway epithelial cells expressed IL-4R constitutively, and IL-4 (250 ng) increased MUC5 gene expression and Alcian blue/periodic acid-Schiff-positive staining at 24 h; IL-4 did not increase inflammatory cell numbers in airway tissue or in bronchoalveolar lavage. TNF-alpha and IL-1beta levels in bronchoalveolar lavage were not increased in response to IL-4 instillation. These results indicate that airway epithelial cells express IL-4R constitutively and that IL-4 directly induces the differentiation of epithelium into mucous glycoconjugate-containing goblet cells.     

O3-induced change in bronchial reactivity to methacholine and airway inflammation in humans

The increase in airway responsiveness induced by O3 exposure in dogs is associated with airway epithelial inflammation, as evidenced by an increase in the number of neutrophils (polymorphonuclear leukocytes) found in epithelial biopsies and in bronchoalveolar lavage fluid. We investigated in 10 healthy, human subjects whether O3-induced hyperresponsiveness was similarly associated with airway inflammation by examining changes in the types of cells recovered in bronchoalveolar lavage fluid obtained after exposure to air or to O3 (0.4 or 0.6 ppm). We also measured the concentrations of cyclooxygenase and lipoxygenase metabolites of arachidonic acid in lavage fluid. We measured airway responsiveness to inhaled methacholine aerosol before and after each exposure and performed bronchoalveolar lavage 3 h later. We found more neutrophils in the lavage fluid from O3-exposed subjects, especially in those in whom O3 exposure produced an increase in airway responsiveness. We also found significant increases in the concentrations of prostaglandins E2, F2 alpha, and thromboxane B2 in lavage fluid from O3-exposed subjects. These results show that in human subjects O3-induced hyperresponsiveness to methacholine is associated with an influx of neutrophils into the airways and with changes in the levels of some cyclooxygenase metabolites of arachidonic acid.     

Inhibition of tobacco smoke-induced lung inflammation by a catalytic antioxidant

Cigarette smokers experience airway inflammation and epithelial damage, the mechanisms of which are unknown. One potential cause may be free radicals either in tobacco smoke or produced during persistent inflammation. Inflammation may also be a driving force to cause airway epithelium to undergo changes leading to squamous cell metaplasia. To test whether tobacco smoke-induced inflammation could be reduced by a catalytic antioxidant, manganese(III)meso-tetrakis(N,N'-diethyl-1,3-imidazolium-2-yl) porphyrin (AEOL 10150) was given by intratracheal instillation to rats exposed to filtered air or tobacco smoke. Exposure to tobacco smoke for 2 d or 8 weeks (6 h/d, 3 d/week) significantly increased the number of cells recovered by bronchoalveolar lavage (BAL). AEOL 10150 significantly decreased BAL cell number in tobacco smoke-treated rats. Significant reductions in neutrophils were noted at 2 d and macrophages at 8 weeks. Lymphocytes were significantly reduced by AEOL 10150 at both time points. Squamous cell metaplasia following 8 weeks of tobacco smoke exposure was 12% of the total airway epithelial area in animals exposed to tobacco smoke without AEOL 10150, compared with 2% in animals exposed to tobacco smoke, but treated with AEOL 10150 (p <.05). We conclude that a synthetic catalytic antioxidant decreased the adverse effects of exposure to tobacco smoke.     

Activation of epidermal growth factor receptors is responsible for mucin synthesis induced by cigarette smoke

Mucus hypersecretion from hyperplastic airway goblet cells is a hallmark of chronic obstructive pulmonary disease (COPD). Although cigarette smoking is thought to be involved in mucus hypersecretion in COPD, the mechanism by which cigarette smoke induces mucus overproduction is unknown. Here we show that activation of epidermal growth factor receptors (EGFR) is responsible for mucin production after inhalation of cigarette smoke in airways in vitro and in vivo. In the airway epithelial cell line NCI-H292, exposure to cigarette smoke upregulated the EGFR mRNA expression and induced activation of EGFR-specific tyrosine phosphorylation, resulting in upregulation of MUC5AC mRNA and protein production, effects that were inhibited completely by selective EGFR tyrosine kinase inhibitors (BIBX1522, AG-1478) and that were decreased by antioxidants. In vivo, cigarette smoke inhalation increased MUC5AC mRNA and goblet cell production in rat airways, effects that were prevented by pretreatment with BIBX1522. These effects may explain the goblet cell hyperplasia that occurs in COPD and may provide a novel strategy for therapy in airway hypersecretory diseases.     

Antibody to mCLCA3 Suppresses Symptoms in a Mouse Model of Asthma

Background

Asthma is a complex and heterogeneous chronic inflammatory disorder that is associated with mucous cell metaplasia and mucus hypersecretion. Functional genomic analysis indicates that mucous cell metaplasia and mucus hypersecretion depend on members of the calcium-activated chloride channel (CLCA) gene family. It has been reported that the inhibition of CLCAs could relieve the symptoms of asthma. Thus, the mCLCA3 antibody may be a promising strategy to treat allergic diseases such as asthma.

Methods

We constructed asthmatic mouse models of OVA-induced chronic airway inflammatory disorder to study the function of the mCLCA3 antibody. Airway inflammation was measured by HE staining; goblet cell hyperplasia and mucus hypersecretion were detected by PAS staining; muc5ac, IL-13, IFN-γ levels in bronchoalveolar lavage fluid (BALF) were examined by ELISA; Goblet cell apoptosis was measured by TUNEL assay and alcian blue staining; mCLCA3, Bcl-2 and Bax expression were detected by RT-PCR, Western blotting and immunohistochemical analysis.

Results

In our study, mice treated with mCLCA3 antibody developed fewer pathological changes compared with control mice and asthmatic mice, including a remarkable reduction in airway inflammation, the number of goblet cells and mCLCA3 expression in lung tissue. The levels of muc5ac and IL-13 were significantly reduced in BALF. We also found that the rate of goblet cell apoptosis was increased after treatment with mCLCA3 antibody, which was accompanied by an increase in Bax levels and a decrease in Bcl-2 expression in goblet cells.

Conclusions

Taken together, our results indicate that mCLCA3 antibody may have the potential as an effective pharmacotherapy for asthma.     

Cigarette smoke-induced lung emphysema in mice is associated with prolyl endopeptidase, an enzyme involved in collagen breakdown

There is increasing evidence that the neutrophil chemoattractant proline-glycine-proline (PGP), derived from the breakdown of the extracellular matrix, plays an important role in neutrophil recruitment to the lung. PGP formation is a multistep process involving neutrophils, metalloproteinases (MMPs), and prolyl endopeptidase (PE). This cascade of events is now investigated in the development of lung emphysema. A/J mice were whole body exposed to cigarette smoke for 20 wk. After 20 wk or 8 wk after smoking cessation, animals were killed, and bronchoalveolar lavage fluid and lung tissue were collected to analyze the neutrophilic airway inflammation, the MMP-8 and MMP-9 levels, the PE activity, and the PGP levels. Lung tissue degradation was assessed by measuring the mean linear intercept. Additionally, we investigated the effect of the peptide L-arginine-threonine-arginine (RTR), which binds to PGP sequences, on the smoke-induced neutrophil influx in the lung after 5 days of smoke exposure. Neutrophilic airway inflammation was induced by cigarette smoke exposure. MMP-8 and MMP-9 levels, PE activity, and PGP levels were elevated in the lungs of cigarette smoke-exposed mice. PE was highly expressed in epithelial and inflammatory cells (macrophages and neutrophils) in lung tissue of cigarette smoke-exposed mice. After smoking cessation, the neutrophil influx, the MMP-8 and MMP-9 levels, the PE activity, and the PGP levels were decreased or reduced to normal levels. Moreover, RTR inhibited the smoke-induced neutrophil influx in the lung after 5 days' smoke exposure. In the present murine model of cigarette smoke-induced lung emphysema, it is demonstrated for the first time that all relevant components (neutrophils, MMP-8, MMP-9, PE) involved in PGP formation from collagen are upregulated in the airways. Together with MMPs, PE may play an important role in the formation of PGP and thus in the pathophysiology of lung emphysema.     

Alteration of platelet activating factor (PAF) metabolism in rat pulmonary alveolar macrophages and plasma by cigarette smoking.

The pathophysiological role of platelet activating factor (PAF) in smoking-induced disorders was examined in rats exposed daily to smoke for 10, 18 and 26 weeks. The concentration of PAF in bronchoalveolar lavage fluid and the activities of PAF biosynthetic and catabolic enzymes in alveolar macrophages and in plasma were determined. The concentration of PAF in lavage fluid of the smoke-exposed group was significantly lower than that in the sham group for each duration of smoke exposure. The PAF biosynthetic enzyme, acetyl transferase, activity in alveolar macrophages of smoked group was less than that in the sham group although the difference was not statistically significant. PAF catabolic enzyme, acetyl hydrolase, activities in alveolar macrophages and in plasma were all significantly higher in every smoked group than in the sham group. These data indicate that cigarette smoking alters PAF metabolism in the respiratory tract and in plasma and such an alteration may contribute, at least in part, to smoking induced cardiopulmonary disorders.     

Paeonol attenuates airway inflammation and hyperresponsiveness in a murine model of ovalbumin-induced asthma

Paeonol, the main active component isolated from Moutan Cortex, possesses extensive pharmacological activities such as anti-inflammatory, anti-allergic, and immunoregulatory effects. In the present study, we examined the effects of paeonol on airway inflammation and hyperresponsiveness in a mouse model of allergic asthma. BALB/c mice sensitized and challenged with ovalbumin were administered paeonol intragastrically at a dose of 100?mg/kg daily. Paeonol significantly suppressed ovalbumin-induced airway hyperresponsiveness to acetylcholine chloride. Paeonol administration significantly inhibited the total inflammatory cell and eosinophil count in bronchoalveolar lavage fluid. Treatment with paeonol significantly enhanced IFN-γ levels and decreased interleukin-4 and interleukin-13 levels in bronchoalveolar lavage fluid and total immunoglobulin E levels in serum. Histological examination of lung tissue demonstrated that paeonol significantly attenuated allergen-induced lung eosinophilic inflammation and mucus-producing goblet cells in the airway. These data suggest that paeonol exhibits anti-inflammatory activity in allergic mice and may possess new therapeutic potential for the treatment of allergic bronchial asthma.     

Meconium aspiration produces airway hyperresponsiveness and eosinophilic inflammation in a murine model

Meconium aspiration syndrome is a cause of significant morbidity and mortality in the perinatal period and has been implicated in the pathogenesis of airway dysfunction. In this study, we developed a murine model to evaluate the effects of meconium aspiration on airway physiology and lung cellular responses. Under light anesthesia, BALB/c mice received a single intratracheal instillation of meconium or physiological saline. Respiratory mechanics were measured in unrestrained animals and expressed as percent increase in enhanced pause to increasing concentrations of methacholine (MCh). Furthermore, we assessed the changes in cells and cytokines into the bronchoalveolar lavage fluid (BALF). We found meconium aspiration produced increased airway responsiveness to MCh at 7 days. These functional changes were associated with lymphocytic/eosinophilic inflammation, goblet cell metaplasia, and increased concentrations of IL-5 and IL-13 in the BALF. Our findings suggest meconium aspiration leads to alterations of airway function, lung eosinophilia, goblet cell metaplasia, and cytokine imbalance, thus providing the first evidence of meconium-induced airway dysfunction in a mouse model.     

A relation between TGF-β and mast cell tryptase in experimental emphysema models

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease characterized by emphysema and/or chronic bronchitis. The aim of this study was to investigate the effect of cigarette smoke exposure on mast cells and mast cell function in vitro and in vivo in order to get further insight in the role of mast cells in the pathogenesis of emphysema. Cigarette smoke conditioned medium (CSM) induced the expression of mast cell tryptase (MMCP-6) in primary cultured mast cells. This tryptase expression was caused by the CSM-stimulated production of TGF-β in culture and neutralization of TGF-β suppressed the CSM-induced expression of tryptase in mast cells. An increase in mast cell tryptase expression was also found in an experimental model for emphysema. Exposure of mice to cigarette smoke increased the number of mast cells in the airways and the expression of mast cell tryptase. In accordance with the in vitro findings, TGF-β in bronchoalveolar lavage fluid of smoke-exposed animals was significantly increased. Our study indicates that mast cells may be a source of TGF-β production after cigarette smoke exposure and that in turn TGF-β may change the tryptase expression in mast cells.     

The differential expression of novel circular RNAs in an acute lung injury rat model caused by smoke inhalation

Acute lung injury caused by smoke inhalation is a common severe clinical syndrome. This study aimed to investigate the potential expression of circular RNAs during acute lung injury triggered by smoke inhalation. The acute lung injury rat model was established with smoke inhalation from a self-made smoke generator. The occurrence of acute lung injury was validated by an analysis of the bronchoalveolar lavage fluid and hematoxylin-eosin (HE) staining of lung tissues. Next-generation sequencing and quantitative PCR were performed to identify the differentially expressed circular RNAs associated with acute lung injury that was caused by smoke inhalation. The circular form of the identified RNAs was finally verified by multiple RT-PCR-based assays. The bronchoalveolar lavage fluid (BALF) and lung tissue analysis showed that smoke inhalation successfully induced acute injury in rats, as evidenced by the significantly altered cell numbers, including macrophages, neutrophils, and red blood cells, disrupted cell lining, and increased levels of interleukin-1β, tumor necrosis factor-alpha, and IL-8 in lung tissues. Ten significantly differentially expressed circular RNAs were identified with next-generation sequencing and RT-PCR. The circular form of these RNAs was verified by multiple RT-PCR-based assays. In conclusion, the identified circular RNAs were prevalently and differentially expressed in rat lungs after acute lung injury caused by smoke inhalation.     

Aldose reductase inhibition prevents metaplasia of airway epithelial cells

Background

Goblet cell metaplasia that causes mucus hypersecretion and obstruction in the airway lumen could be life threatening in asthma and chronic obstructive pulmonary disease patients. Inflammatory cytokines such as IL-13 mediate the transformation of airway ciliary epithelial cells to mucin-secreting goblet cells in acute as well as chronic airway inflammatory diseases. However, no effective and specific pharmacologic treatment is currently available. Here, we investigated the mechanisms by which aldose reductase (AR) regulates the mucus cell metaplasia in vitro and in vivo.

Methodology/Findings

Metaplasia in primary human small airway epithelial cells (SAEC) was induced by a Th2 cytokine, IL-13, without or with AR inhibitor, fidarestat. After 48 h of incubation with IL-13 a large number of SAEC were transformed into goblet cells as determined by periodic acid-schiff (PAS)-staining and immunohistochemistry using antibodies against Mucin5AC. Further, IL-13 significantly increased the expression of Mucin5AC at mRNA and protein levels. These changes were significantly prevented by treatment of the SAEC with AR inhibitor. AR inhibition also decreased IL-13-induced expression of Muc5AC, Muc5B, and SPDEF, and phosphorylation of JAK-1, ERK1/2 and STAT-6. In a mouse model of ragweed pollen extract (RWE)-induced allergic asthma treatment with fidarestat prevented the expression of IL-13, phosphorylation of STAT-6 and transformation of epithelial cells to goblet cells in the lung. Additionally, while the AR-null mice were resistant, wild-type mice showed goblet cell metaplasia after challenge with RWE.

Conclusions

The results show that exposure of SAEC to IL-13 caused goblet cell metaplasia, which was significantly prevented by AR inhibition. Administration of fidarestat to mice prevented RWE-induced goblet cell metaplasia and AR null mice were largely resistant to allergen induced changes in the lung. Thus our results indicate that AR inhibitors such as fidarestat could be developed as therapeutic agents to prevent goblet cell metaplasia in asthma and related pathologies.     

CD8+ T cell-mediated airway hyperresponsiveness and inflammation is dependent on CD4+IL-4+ T cells

CD4+ T cells, particularly Th2 cells, play a pivotal role in allergic airway inflammation. However, the requirements for interactions between CD4+ and CD8+ T cells in airway allergic inflammation have not been delineated. Sensitized and challenged OT-1 mice in which CD8+ T cells expressing the transgene for the OVA(257-264) peptide (SIINFEKL) failed to develop airway hyperresponsiveness (AHR), airway eosinophilia, Th2 cytokine elevation, or goblet cell metaplasia. OT-1 mice that received naive CD4+IL-4+ T cells but not CD4+IL-4- T cells before sensitization developed all of these responses to the same degree as wild-type mice. Moreover, recipients of CD4+IL-4+ T cells developed significant increases in the number of CD8+IL-13+ T cells in the lung, whereas sensitized OT-1 mice that received primed CD4+ T cells just before challenge failed to develop these responses. Sensitized CD8-deficient mice that received CD8+ T cells from OT-1 mice that received naive CD4+ T cells before sensitization increased AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged with allergen. In contrast, sensitized CD8-deficient mice receiving CD8+ T cells from OT-1 mice without CD4+ T cells developed reduced AHR and eosinophil numbers in bronchoalveolar lavage fluid when challenged. These data suggest that interactions between CD4+ and CD8+ T cells, in part through IL-4 during the sensitization phase, are essential to the development of CD8+IL-13+ T cell-dependent AHR and airway allergic inflammation.