Eotaxin expression by epithelial cells and plasma cells in chronic asthma

Differences in Eotaxin Serum Levels between Polytraumatized Patients with and without Concomitant Traumatic Brain Injury-A Matched Pair Analysis

Background/Objectives: Early detection of traumatic brain injury (TBI) is crucial for minimizing secondary neurological damage. Our study aimed to assess the potential of IL-4, IL-6, IL-7, IL-8, IL-10, TNF, and eotaxin serum levels-as a single clinical tool or combined into a panel-for diagnosing TBI in multiple injured patients. Methods: Out of 110 prospectively enrolled polytrauma victims (median age, 39 years; median ISS, 33; 70.9% male) admitted to our level I trauma center over four years, we matched 41 individuals with concomitant TBI (TBI cohort) to 41 individuals without TBI (non-TBI cohort) based on age, gender, Injury Severity Score (ISS), and mortality. Patients' protein levels were measured upon admission (day 0) and on days 1, 3, 5, 7, and 10 during routine blood withdrawal using one separation gel tube each time. Results: The median serum levels of IL-4, IL-6, IL-7, IL-8, IL-10, and TNF exhibited non-similar time courses in the two cohorts and showed no significant differences on days 0, 1, 3, 5, and 7. However, the median eotaxin levels had similar trend lines in both cohorts, with consistently higher levels in the TBI cohort, reaching significance on days 0, 3, and 5. In both cohorts, the median eotaxin level significantly decreased from day 0 to day 1, then significantly increased until day 10. We also found a significant positive association between day 0 eotaxin serum levels and the presence of TBI, indicating that for every 20 pg/mL increase in eotaxin level, the odds of a prevalent TBI rose by 10.5%. ROC analysis provided a cutoff value of 154 pg/mL for the diagnostic test (sensitivity, 0.707; specificity, 0.683; AUC = 0.718). Conclusions: Our findings identified the brain as a significant source, solely of eotaxin release in humans who have suffered a TBI. Nevertheless, the eotaxin serum level assessed upon admission has limited diagnostic value. IL-4, IL-6, IL-7, IL-8, IL-10, and TNF do not indicate TBI in polytraumatized patients.

Mouse Model of Nitrogen Mustard Ocular Surface Injury Characterization and Sphingolipid Signaling

Vesicating chemicals like sulfur mustard (SM) or nitrogen mustard (NM) can cause devastating damage to the eyes, skin, and lungs. Eyes, being the most sensitive, have complicated pathologies that can manifest immediately after exposure (acute) and last for years (chronic). No FDA-approved drug is available to be used as medical counter measures (MCMs) against such injuries. Understanding the pathological mechanisms in acute and chronic response of the eye is essential for developing effective MCMs. Here, we report the clinical and histopathological characterization of a mouse model of NM-induced ocular surface injury (entire surface) developed by treating the eye with 2% (w/v) NM solution for 5 min. Unlike the existing models of specific injury, our model showed severe ocular inflammation, including the eyelids, structural deformity of the corneal epithelium and stroma, and diminished visual and retinal functions. We also observed alterations of the inflammatory markers and their expression at different phases of the injury, along with an activation of acidic sphingomyelinase (aSMase), causing an increase in bioactive sphingolipid ceramide and a reduction in sphingomyelin levels. This novel ocular surface mouse model recapitulated the injuries reported in human, rabbit, and murine SM or NM injury models. NM exposure of the entire ocular surface in mice, which is similar to accidental or deliberate exposure in humans, showed severe ocular inflammation and caused irreversible alterations to the corneal structure and significant vision loss. It also showed an intricate interplay between inflammatory markers over the injury period and alteration in sphingolipid homeostasis in the early acute phase.

Effects of combination treatment with tezepelumab and allergen immunotherapy on nasal responses to allergen: A randomized controlled trial

BACKGROUND

Thymic stromal lymphopoietin (TSLP) has been shown to play a central role in the initiation and persistence of allergic responses.

OBJECTIVE

We evaluated whether tezepelumab, a human monoclonal anti-TSLP antibody, improved the efficacy of subcutaneous allergen immunotherapy (SCIT) and promoted the development of tolerance in patients with allergic rhinitis.

METHODS

We conducted a double-blind parallel design trial in patients with cat allergy. A total of 121 patients were randomized to receive either intravenous tezepelumab plus subcutaneous cat SCIT, cat SCIT alone, tezepelumab alone, or placebo for 52 weeks, followed by 52 weeks of observation. Nasal allergen challenge (NAC), skin testing, and blood and nasal samples were obtained throughout the study.

RESULTS

At week 52, the NAC-induced total nasal symptom scores (TNSS) (calculated as area under the curve [AUC0-1h] and as peak score [Peak0-1h] during the first hour after NAC) were significantly reduced in patients receiving tezepelumab/SCIT compared to SCIT alone. At week 104, one year after stopping treatment, the primary end point TNSS AUC0-1h was not significantly different in the tezepelumab/SCIT group compared to SCIT alone, while TNSS Peak0-1h was significantly lower in those receiving combination treatment versus SCIT. Transcriptomic analysis of nasal epithelial samples demonstrated that treatment with the combination of SCIT/tezepelumab, but neither monotherapy, caused persistent downregulation of a gene network related to type 2 inflammation that was associated with improvement in NAC responses.

CONCLUSIONS

Inhibition of TSLP augments the efficacy of SCIT during therapy and may promote tolerance after a 1-year course of treatment. (ClinicalTrials.gov NCT02237196).

Allergic Inflammation: Effect of Propolis and Its Flavonoids

The incidence of allergic diseases and their complications are increasing worldwide. Today, people increasingly use natural products, which has been termed a "return to nature". Natural products with healing properties, especially those obtained from plants and bees, have been used in the prevention and treatment of numerous chronic diseases, including allergy and/or inflammation. Propolis is a multi-component resin rich in flavonoids, collected and transformed by honeybees from buds and plant wounds for the construction and adaptation of their nests. This article describes the current views regarding the possible mechanisms and multiple benefits of flavonoids in combating allergy and allergy-related complications. These benefits arise from flavonoid anti-allergic, anti-inflammatory, antioxidative, and wound healing activities and their effects on microbe-immune system interactions in developing host responses to different allergens. Finally, this article presents various aspects of allergy pathobiology and possible molecular approaches in their treatment. Possible mechanisms regarding the antiallergic action of propolis on the microbiota of the digestive and respiratory tracts and skin diseases as a method to selectively remove allergenic molecules by the process of bacterial biotransformation are also reported.

Adenovirus vector-mediated YKL-40 shRNA attenuates eosinophil airway inflammation in a murine asthmatic model

Recent studies have revealed that YKL-40 is involved in the pathogenesis of asthma. However, its specific mechanism remains unclear. The present study aims to investigate the effect of adenovirus vector-mediated YKL-40 short hairpin RNA (shRNA) on regulation of airway inflammation in a murine asthmatic model. Mice were assessed for airway hyperresponsiveness (AHR), total leukocytes and the percentage of eosinophil cells in bronchoalveolar lavage fluid (BALF). YKL-40 mRNA and protein expression levels were detected using quantitative real-time PCR and western blot assays. Enzyme-linked immunosorbent assay (ELISA) was used to detect YKL-40 and eosinophil-related chemokine expression levels in BALF and serum. Lung histology analyses were performed to evaluate the degree of inflammatory cell infiltration around the airway and airway mucus secretion.YKL-40 shRNA significantly inhibited the YKL-40 gene expression in asthmatic mice. In addition, YKL-40 shRNA alleviated eosinophilic airway inflammation, AHR, airway mucus secretion and decreased the levels of YKL-40 in BALF and serum in a murine asthmatic model. The levels and mRNA expression of IL-5, IL-13 in asthmatic mice lung tissues, eotaxin, and GM-CSF in BALF and serum significantly decreased. Bone marrow signaling molecules including IL-5, eotaxin, and GM-CSF were correlated with decreased levels of YKL-40. The study reveals that YKL-40 could be involved in asthma inflammation by altering bone marrow signaling molecules. YKL-40 gene RNA interference could provide new therapeutic strategies for asthma.

Modeling TH 2 responses and airway inflammation to understand fundamental mechanisms regulating the pathogenesis of asthma

In this review, we highlight experiments conducted in our laboratories that have elucidated functional roles for CD4⁺ T-helper type-2 lymphocytes (T_H 2 cells), their associated cytokines, and eosinophils in the regulation of hallmark features of allergic asthma. Notably, we consider the complexity of type-2 responses and studies that have explored integrated signaling among classical T_H 2 cytokines (IL-4, IL-5, and IL-13), which together with CCL11 (eotaxin-1) regulate critical aspects of eosinophil recruitment, allergic inflammation, and airway hyper-responsiveness (AHR). Among our most important findings, we have provided evidence that the initiation of T_H 2 responses is regulated by airway epithelial cell-derived factors, including TRAIL and MID1, which promote T_H 2 cell development via STAT6-dependent pathways. Further, we highlight studies demonstrating that microRNAs are key regulators of allergic inflammation and potential targets for anti-inflammatory therapy. On the background of T_H 2 inflammation, we have demonstrated that innate immune cells (notably, airway macrophages) play essential roles in the generation of steroid-resistant inflammation and AHR secondary to allergen- and pathogen-induced exacerbations. Our work clearly indicates that understanding the diversity and spatiotemporal role of the inflammatory response and its interactions with resident airway cells is critical to advancing knowledge on asthma pathogenesis and the development of new therapeutic approaches.

Reduced allergic lung inflammation by root extracts from two species of Peucedanum through inhibition of Th2 cell activation

ETHNOPHARMACOLOGICAL EVIDENCE

Peucedani Radix (PR), the root of Peucedanum praeruptorum Dunn (PPD) or Peucedanum decursivum (Miq.) Maxim. (PDM), has long been used in Korea to eliminate sputum, relieve cough, and reduce bronchus contraction. Furthermore, these therapeutic strategies are recognized as general and effective methods in western medicine as well as traditional Korean medicine.

AIM OF THE STUDY

To determine and compare the anti-inflammatory effects of PPD extracts (PPDE) and PDM extracts (PDME) on allergic lung inflammation, using in vivo OVA-induced airway inflammation in mice and in vitro primary cell culture systems.

MATERIALS AND METHODS

Eight-week-old female C57BL/6 mice were placed into four groups (n=4 per group): saline control, OVA-induced allergic lung inflammation with vehicle, or PPDE (200mg/kg) or PDME (200mg/kg) treatment. PR extracts (PRE) were administered from 1 week before 1st OVA sensitization to the day before sacrifice. Mice were sacrificed 18h after last OVA intra-nasal challenge followed by histological and biochemical analyses.

RESULTS

Inflammatory phenotypes were alleviated with oral administration of PRE. PRE treatment decreased mucus production in airway epithelium, inflammatory cell number, eosinophilia, type 2 cytokines, and histamine in bronchoalveolar lavage fluid (BALF). Mice with PRE administration showed diminished activated CD4 T cell (CD4⁺CD25⁺ cell) and GATA-3 level in the lung. In addition, PRE treatment reduced Th2 cell activation in vitro, using Th2 polarization system.

CONCLUSION

Our findings indicate that the anti-inflammatory effects of PRE arise from reduced Th2 cell activation and validate the clinical use of PR in traditional Korean medicine.

Effect of tranilast in comparison with beclomethasone in chronic murine model of asthma

AIM OF THE STUDY

The current investigation was taken to scrutinize the action of tranilast on the airway remodeling in chronic asthma in mice.

MATERIALS AND METHODS

Intraperitoneal injection of ovalbumin was applied to mice for sensitization and subsequent inhalation of 1% ovalbumin three times week for 10 weeks for challenge. Beclomethasone or tranilast were given daily for the 10 week challenge period. At the end of the study, lung weight index, total collagen content, bronchoalveolar lavage level of total and differential cell counts, interleukin-13, in addition to lung tissue nitrate/nitrite and transforming growth beta-1 were measured. Also, histological analysis was done.

RESULTS

Asthmatic mice demonstrated apparent fibrotic changes. Significant airway fibrosis was demonstrated by hyperplasia of goblet cells and thickening of airway epithelium, increased content of lung collagen, lung and bronchoalveolar lavage of transforming growth factor beta-1 and interleukin-13 mutually accompanied by reduction in nitrate/nitrite generation.

CONCLUSIONS

Beclomethasone influence on airway remodeling was mediated mainly via suppression of eosinophilic recruitment into the airways and reduction of interleukin-13 cytokine levels. Whereas, tranilast effects on airway remodeling was found to be mainly mediated via its inhibitory effect on transforming growth beta-1. Both beclomethasone and tranilast influence airway remodeling by different degrees and mechanisms.

Inhibitory effect of dexamethasone on expression of cysteine-rich 61 protein in airway epithelial cells of allergic mouse models

In order to study whether cysteine-rich 61 protein (cyr61) is involved in the pathogenesis of asthma and its relation to airway inflammation, the effect of dexamethasone (Dxm) on the expression of cyr61 in the lung tissues of asthmatic mice was investigated. Forty BALB/c mice were divided into asthma group (n=15), control group (n=10) and Dxm group (n=15). The asthma group was sensitized and challenged by ovalbumin (OVA). The mice in Dxm group were intraperitoneally administered with Dxm after OVA challenge. The expression of cyr61 in the lung tissues was detected by using immunohistochemistry, and that of eotaxin protein in the bronchoalveolar lavage fluid (BALF) by using enzyme-linked immunosorbent assay (ELISA). The number of inflammatory cells in BALF was also analyzed. The results showed that the cyr61 expression was highest in asthma group (P<0.05), followed by Dxm group (P<0.05) and control group. The cyr61 had a positive correlation with the total nucleated cells (r=0.867, P<0.05), especially eosinophils (r=0.856, P<0.05), and eotaxin level (r=0.983, P<0.05) in the BALF. Our findings suggested that cyr61 is expressed in airway epithelial cells and has a positive correlation with eotaxin and number of airway infiltrating eosinophils.

Interleukin-33 drives activation of alveolar macrophages and airway inflammation in a mouse model of acute exacerbation of chronic asthma

We investigated the role of interleukin-33 (IL-33) in airway inflammation in an experimental model of an acute exacerbation of chronic asthma, which reproduces many of the features of the human disease. Systemically sensitized female BALB/c mice were challenged with a low mass concentration of aerosolized ovalbumin for 4 weeks to induce chronic asthmatic inflammation and then received a single moderate-level challenge to trigger acute airway inflammation simulating an asthmatic exacerbation. The inflammatory response and expression of cytokines and activation markers by alveolar macrophages (AM) were assessed, as was the effect of pretreatment with a neutralizing antibody to IL-33. Compared to chronically challenged mice, AM from an acute exacerbation exhibited significantly enhanced expression of markers of alternative activation, together with enhanced expression of proinflammatory cytokines and of cell surface proteins associated with antigen presentation. In parallel, there was markedly increased expression of both mRNA and immunoreactivity for IL-33 in the airways. Neutralization of IL-33 significantly decreased both airway inflammation and the expression of proinflammatory cytokines by AM. Collectively, these data indicate that in this model of an acute exacerbation of chronic asthma, IL-33 drives activation of AM and has an important role in the pathogenesis of airway inflammation.

Hypothetical pathogenesis of eosinophilic infiltration in Langerhans cell histiocytosis of the jaw

OBJECTIVE

The present study investigated the densities of mast cells and CCL-11/eotaxin-1 expression of tumor cells in Langerhans cell histiocytosis (LCH) of the jaw.

STUDY DESIGN

Eleven LCH cases arising in the jaws were selected. We evaluated eotaxin-1 expression in LCH cells via immunohistochemical staining. Toluidine blue was used to stain mast cells, with 20 periapical granuloma specimens serving as the control group.

RESULTS

In all 7 patients with multifocal LCH, jaw lesions were the earliest manifestation. Toluidine blue staining revealed that most of the mast cells involved in LCH were degranulated, and the number of mast cells in LCH lesions was not significantly higher than in periapical granulomas. Upon immunohistochemical examination, all patients but one showed positivity for eotaxin-1 in LCH cells.

CONCLUSION

This preliminary study suggests that eotaxin-1 expression in LCH cells may contribute to eosinophilic infiltration. Further studies of chemokine-receptor interactions will be needed to confirm this.

Influence of inhaled beclomethasone and montelukast on airway remodeling in mice

This study examined the effect of montelukast and beclomethasone on airway remodeling in murine model of asthma. Mice were sensitized by i.p. injection of ovalbumin (OVA) on days 0 and 14, and then challenged by nebulization of 1% OVA 3 days/week for 6 or 10 weeks. Results of 6-week OVA-challenged group showed moderate inflammation, but the 10-week OVA-challenged group exhibited mild inflammation. The OVA challenge (6 and 10 weeks) exhibited marked airway fibrosis, illustrated by significant increase in goblet cell hyperplasia and epithelial thickness, increased lung content of collagen and transforming growth factor-β(1), together with a decrease in nitric oxide production; also, there was an increase in bronchoalveolar lavage fluid level of interleukin-13. Administration of montelukast or beclomethasone before each OVA challenge was capable of restoring most of the measured parameters to near normal levels. Inhalation of beclomethasone has a similar role in airway remodeling as montelukast, but its effects in regulating inflammatory changes is less pronounced than montelukast.

Altered expression of microRNA in the airway wall in chronic asthma: miR-126 as a potential therapeutic target

Background

The role of microRNAs (miRNAs) in regulating gene expression is currently an area of intense interest. Relatively little is known, however, about the role of miRNAs in inflammatory and immunologically-driven disorders. In a mouse model, we have previously shown that miRNAs are potentially important therapeutic targets in allergic asthma, because inhibition of miR-126, one of a small subset of miRNAs upregulated in the airway wall, effectively suppressed Th2-driven airway inflammation and other features of asthma. In the present study, we extended investigation of the therapeutic potential of miRNA inhibition to our well-established model of chronic asthma.

Methods

Female BALB/c mice were systemically sensitised with ovalbumin (OVA) and chronically challenged with low mass concentrations of aerosolised OVA for up to 6 weeks. Airway tissue was obtained by blunt dissection and RNA was isolated for miRNA profiling. On the basis of the results obtained, animals were subsequently treated with either an antagomir to miR-126 (ant-miR-126) or a scrambled control antagomir once weekly during the 6 weeks of chronic challenge, and the effects on airway inflammation and remodelling were assessed using established morphometric techniques.

Results

Compared to naïve mice, there was selective upregulation of a modest number of miRNAs, notably miR-126, in the airway wall tissue of chronically challenged animals. The relative increase was maximal after 2 weeks of inhalational challenge and subsequently declined to baseline levels. Compared to treatment with the scrambled control, ant-miR-126 significantly reduced recruitment of intraepithelial eosinophils, but had no effect on the chronic inflammatory response, or on changes of airway remodelling.

Conclusions

In this model of chronic asthma, there was an initial increase in expression of a small number of miRNAs in the airway wall, notably miR-126. However, this later declined to baseline levels, suggesting that sustained changes in miRNA may not be essential for perpetuation of chronic asthma. Moreover, inhibition of miR-126 by administration of an antagomir suppressed eosinophil recruitment into the airways but had no effect on chronic inflammation in the airway wall, or on changes of remodelling, suggesting that multiple miRNAs are likely to regulate the development of these lesions.

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

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

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

BACKGROUND

In a mouse model of mild chronic asthma, both inflammation and remodelling can be suppressed by dexamethasone (a glucocorticoid) and roflumilast (a selective phosphodiesterase-4 inhibitor).

OBJECTIVE

To better understand the underlying molecular mechanisms, we investigated the effects of treatment on airway expression of inflammation-related cytokines, as well as on epithelial expression of growth factors.

METHODS

BALB/c mice systemically sensitized to ovalbumin were challenged with aerosolized antigen for 6 weeks and treated with roflumilast or dexamethasone during the final 2 weeks. Expression of mRNA, for a variety of cytokines and growth factors, was assessed in selectively dissected proximal airways or in airway epithelium obtained by laser capture microdissection.

RESULTS

In the airway wall of vehicle-treated challenged animals, there was significantly elevated expression of mRNA for a variety of pro-inflammatory and T helper type 2 cytokines, as well as for IFN-gamma. All these cytokines were suppressed by dexamethasone. Treatment with roflumilast reduced expression of IL-17A, TNF-alpha, granulocyte-macrophage colony-stimulating factor and IL-6, but did not inhibit other cytokines. Both drugs suppressed the enhanced expression of mRNA for growth factors such as TGF-beta1 and FGF-2 in airway epithelium.

CONCLUSIONS

Whereas dexamethasone non-specifically inhibits numerous mediators involved in inflammation and the immune response, roflumilast selectively inhibits a subset of pro-inflammatory cytokines and growth factors. These mediators and/or the cells that produce them may have critical roles in the pathogenesis of the lesions of chronic asthma.

Comparison of Airway Remodeling in Acute, Subacute, and Chronic Models of Allergic Airways Disease

The relationship between airway inflammation and structural changes of airway remodeling, and their relative effects on airway function, are poorly understood. Remodeling is thought to result from chronic repetitive injury to the airway wall caused by airway inflammation; however, the mechanisms regulating remodeling changes have not been clearly defined. We examined the sequence of events in remodeling using three commonly used mouse models of allergic airways disease in which mice are exposed to nebulized ovalbumin for four consecutive days (acute), seven consecutive days (subacute), or three times a week for 6 wk (chronic). Surprisingly, we found that a very short period of exposure to ovalbumin was sufficient to elicit early changes of remodeling. Goblet cell hyperplasia and epithelial thickening were evident after just 4 d. In chronically challenged mice, these changes persisted and, in addition, subepithelial collagen deposition was significantly increased. This collagen deposition was associated with a failure to upregulate matrix metalloproteinase (MMP)-2, in conjunction with increased transforming growth factor-beta and MMP-9 expression. The relationship between inflammation, remodeling changes, and airway hyperresponsiveness (AHR) were examined. The acute and subacute models exhibited marked airway inflammation, whereas the chronic model had very modest inflammation. Conversely, airway fibrosis was only evident in the chronic model. AHR was present in all three models; however, it was significantly higher in the chronic model compared with the acute (P<0.05) and subacute (P<0.05) models. These data demonstrate that both airway inflammation and airway fibrosis may contribute to AHR, with airway fibrosis leading to the greatest increases in AHR.

Airway hyperreactivity in exacerbation of chronic asthma is independent of eosinophilic inflammation

We have developed an animal model to investigate the mechanisms underlying an acute exacerbation of chronic asthma. Sensitized BALB/c mice were exposed to aerosolized ovalbumin, either as chronic low-level challenge (mass concentration approximately 3 mg/m(3)) for 4 wk, a single moderate-level challenge (approximately 30 mg/m(3)), or chronic low-level followed by single moderate-level challenge (the acute exacerbation group). Compared with animals receiving chronic challenge alone, mice in the acute exacerbation group exhibited a more marked inflammatory response, with involvement of intrapulmonary airways and lung parenchyma, and increased numbers of lymphocytes and eosinophils in bronchoalveolar lavage fluid. They also developed airway hyperreactivity (AHR) to methacholine, demonstrable as increased transpulmonary resistance and decreased compliance. This pattern of AHR was absent in chronically challenged animals, but was also present in animals given single moderate-level challenge. However, compared with animals receiving a single moderate-level challenge, inflammation and AHR were induced more rapidly in the acute exacerbation group. Eosinophil-deficient GATA1 Deltadbl mice exhibited undiminished AHR in the acute exacerbation model. We conclude that in mice with pre-existing airway lesions resembling mild chronic asthma, exposure to a moderately high concentration of inhaled antigen induces features of an acute exacerbation. The inflammatory response involves distal airways and is associated with a distinct pattern of AHR, which develops independent of the enhanced eosinophilic inflammation.

Adenoviral gene transfer of the NF-kappa B inhibitory protein ABIN-1 decreases allergic airway inflammation in a murine asthma model

Airway inflammation is a characteristic of many lung disorders, including asthma and chronic obstructive pulmonary disease. Using a murine model of allergen-induced asthma, we have demonstrated that adenovirus-mediated delivery of the nuclear factor-kappaB (NF-kappaB) inhibitory protein ABIN-1 to the lung epithelium results in a considerable reduction of allergen-induced eosinophil infiltration into the lungs. This is associated with an ABIN-1-induced decrease in allergen-specific immunoglobulin E levels in serum, as well as a significant reduction of eotaxin, interleukin-4, and interleukin-1beta in bronchoalveolar lavage fluid. These findings not only prove that NF-kappaB plays a critical role in the pathogenesis of allergic inflammation but also illustrate that inhibiting NF-kappaB could have therapeutic value in the treatment of asthma and potentially other chronic inflammatory lung diseases.

Expression of growth factors by airway epithelial cells in a model of chronic asthma: regulation and relationship to subepithelial fibrosis

BACKGROUND

Growth factors produced by airway epithelial cells may be important in the pathogenesis of subepithelial fibrosis, a distinctive lesion of chronic human asthma.

OBJECTIVE

To examine the relationship between the development of subepithelial fibrosis and the expression of transforming growth factor-beta 1 (TGF-beta 1) and ligands for the epidermal growth factor receptor.

METHODS

BALB/c mice sensitized to ovalbumin were chronically challenged by inhalation of low levels of antigen, leading to development of subepithelial fibrosis and other changes of airway wall remodelling. Growth factor expression was assessed by immunohistochemistry and enzyme immunoassay.

RESULTS

Allergic sensitization directly correlated with airway epithelial expression of both the cleaved, potentially biologically active form of TGF-beta 1 and of amphiregulin in response to allergen challenge. Accumulation of TGF-beta 1 was related to remodelling of the airway wall in chronic asthma, whereas expression of amphiregulin did not exhibit a similar relationship. Production of epithelial cell-derived TGF-beta 1 appeared to be regulated by IL-13, while both IL-13 and CD4(+) T cells regulated accumulation of TGF-beta 1. In contrast to results reported in high-level exposure models of airway fibrosis, eosinophils did not appear to be a significant source of TGF-beta 1.

CONCLUSION

Airway epithelial cell-derived TGF-beta 1 has a potentially crucial role in the development of airway wall remodelling in asthma. Immunological mechanisms may regulate the release and accumulation of TGF-beta 1.

Marked Up-regulation of T Lymphocytes and Expression of Interleukin-9 in Bronchial Biopsies From Patients With Chronic Bronchitis With Obstruction *

STUDY OBJECTIVE

To examine the differences in the inflammatory cell and cytokine profile between patients with chronic bronchitis (CB) with and without airway obstruction compared to control subjects.

DESIGN

We used bronchial biopsy samples from the patients and control subjects and analyzed them for the presence of CD3 T cells, CD68, major basic protein (MBP), elastase, and tryptase, as well as expression of messenger RNA (mRNA) coding for interleukin (IL)-4, IL-5, interferon (IFN)-gamma, IL-9, eotaxin, and IFN-gamma-inducible protein (IP)-10. The techniques of immunocytochemistry and in situ hybridization were used. Results were expressed as the number of immunoreactive and mRNA-positive cells per field.

RESULTS

Increased number of elastase, CD68, and MBP-positive cells (n = 9, p < 0.01) was demonstrated in both groups of patients with CB compared to control subjects. In patients with CB and obstruction, the number of elastase, CD68, and the number of CD3-positive cells was significantly increased compared to patients with CB without obstruction (n = 9, p < 0.01). IFN-gamma mRNA expression was increased in both groups of patients with CB compared to control subjects (n = 9, p < 0.01). IL-9 mRNA was significantly increased only in patients with CB and obstruction (n = 9, p < 0.01). Co-localization studies demonstrated > 80% of all IL-9-positive cells to be CD3-positive T cells. IP-10 mRNA was significantly increased in both groups of patients with CB compared to control subjects (n = 9, p < 0.01).

CONCLUSIONS

These results indicate a differential expression of inflammatory markers and cytokine mRNA in patients with obstructive CB. Increased presence of T lymphocytes and up-regulation of IL-9 and IP-10 mRNA expression in the bronchial biopsy samples may contribute to the airway obstruction in these patients.

Inhibition of inflammation and remodeling by roflumilast and dexamethasone in murine chronic asthma

Phosphodiesterase (PDE) inhibitors have potential as alternatives or adjuncts to glucocorticoid therapy in asthma. We compared roflumilast (a selective PDE4 inhibitor) with pentoxifylline (a nonselective inhibitor) and dexamethasone in ameliorating the lesions of chronic asthma in a mouse model. BALB/c mice sensitized to ovalbumin were chronically challenged with aerosolized antigen for 6 weeks. During weeks 5 and 6, groups of animals were treated with roflumilast or dexamethasone by daily gavage or with pentoxifylline by daily intraperitoneal injection. Airway hyper-reactivity (AHR) was evaluated by whole-body plethysmography and airway lesions by histomorphometry and immunohistochemistry. Compared with vehicle alone, treatment with roflumilast or dexamethasone significantly reduced accumulation of eosinophils and chronic inflammatory cells, subepithelial collagenization, and thickening of the airway epithelium. Dexamethasone also reduced goblet cell hyperplasia/metaplasia, subepithelial accumulation of transforming growth factor-beta1, and epithelial cytoplasmic immunoreactivity for nuclear factor-kappaB. Treatment with pentoxifylline inhibited only eosinophil recruitment and epithelial thickening. Roflumilast and dexamethasone slightly decreased AHR, whereas this was significantly reduced by pentoxifylline. Thus, in this model of chronic asthma, both roflumilast and dexamethasone were potent inhibitors of airway inflammation and remodeling. Roflumilast did not diminish accumulation of transforming growth factor-beta1, suggesting that it might affect remodeling by mechanisms distinct from glucocorticoids.

Dissociation of T helper type 2 cytokine-dependent airway lesions from signal transducer and activator of transcription 6 signalling in experimental chronic asthma

BACKGROUND

Type 2 T helper lymphocytes (Th2 cells) and their cytokine products are important in the pathogenesis of asthma.

OBJECTIVE

To examine the contribution of the signal transducer and activator of transcription (STAT) 6 pathway, involved in Th2 cytokine signalling, to the development of lesions of chronic asthma.

METHODS

BALB/c mice sensitized to ovalbumin were chronically challenged by inhalational of low mass concentrations of antigen for 6 weeks. Airway lesions in wild-type mice were compared with those in STAT6-deficient mice and in IL-4/13 double-deficient mice by histomorphometry and immunohistochemistry. Airway responses to methacholine were evaluated by whole-body plethysmography. Cytokine production by peribronchial lymph node cells was quantified by enzyme immunoassay.

RESULTS

STAT6-/- mice developed a variety of airway lesions that were at least equivalent to those in wild-type mice, including accumulation of intraepithelial eosinophils and of chronic inflammatory cells in the lamina propria, subepithelial fibrosis and epithelial thickening. In addition, STAT6-/- mice exhibited exaggerated airway hyper-reactivity (AHR) compared to wild-type animals. This was despite a shift from a Th2 to a Th1 pattern of immunoglobulin production by plasma cells in the inflammatory infiltrate and diminished mucous cell hyperplasia/metaplasia, together with increased production of IFN-gamma by peribronchial lymph node cells, consistent with absence of signalling via the STAT6 pathway. In contrast, gene-targeted IL-4/13-/- mice exhibited markedly diminished eosinophil recruitment and airway remodelling, as well as absence of AHR.

CONCLUSIONS

In this model, the effects of STAT6 deficiency were in marked contrast to the suppression of inflammation and AHR described in models of allergic bronchopulmonary inflammation. These results, which provide evidence of STAT6-independent AHR in an inhalational challenge model of chronic asthma, emphasize the critical effector roles of IL-4 and IL-13, as well as the need to use appropriate models to understand cytokine signalling pathways that may be potential therapeutic targets in asthma.

Modeling allergic asthma in mice: pitfalls and opportunities

Studies in murine experimental models have contributed greatly to understanding the mechanisms of allergic inflammation underlying asthma. However, models involving short-term high-level exposure of sensitized animals to antigen have significant limitations for investigating the pathogenesis of the lesions of chronic asthma. Modeling chronic asthma is problematic, because long-term antigenic challenge often triggers widespread pulmonary parenchymal inflammation or leads to eventual downregulation of inflammation and airway hyperreactivity. We have developed an improved murine model in which animals are exposed to low mass concentrations of aerosolized antigen for 6-8 wk. The mice exhibit airway-specific acute-on-chronic inflammation and changes of airway wall remodeling as seen in human asthma, together with hyperreactivity to a cholinergic agonist which can be specifically attributed to airway disease. This more realistic model of asthma offers a number of opportunities for investigation of pathogenetic mechanisms and novel therapeutic agents.

CD4(+) T-lymphocytes regulate airway remodeling and hyper-reactivity in a mouse model of chronic asthma

Asthma is an acute-on-chronic inflammatory disease of the airways, characterized by airflow obstruction and hyper-reactivity of the airways to a variety of stimuli. Chronic asthma is associated with remodeling of the airway wall, which may contribute to hyper-reactivity and fixed airflow obstruction. We used an improved mouse model of chronic asthma to investigate the role of CD4(+) T-lymphocytes in airway remodeling and hyper-reactivity. Animals functionally depleted of CD4(+) T-lymphocytes by repeated administration of a monoclonal antibody exhibited markedly decreased airway responsiveness. In addition, these mice had greatly diminished subepithelial fibrosis, epithelial thickening, and mucous cell hyperplasia/metaplasia. Chronic inflammation in the airway wall was moderately reduced, with a marked decrease in the accumulation of immunoglobulin-synthesizing plasma cells. However, intraepithelial accumulation of eosinophils was not significantly inhibited and airway epithelial expression of eotaxin was undiminished. This work provides the first experimental evidence that CD4(+) T-lymphocytes play a crucial role in the pathogenesis of the lesions of chronic asthma and lends support to the notion that functional inhibition of these cells may be an important therapeutic target.