Model Of Chronic Airway Inflammation Research Articles

IL-33 blockade affects mediators of persistence and exacerbation in a model of chronic airway inflammation

Severe inflammatory airway diseases are associated with inflammation that does not resolve, leading to structural changes and an overall environment primed for exacerbations. We sought to identify and inhibit pathways that perpetuate this heightened inflammatory state because this could lead to therapies that allow for a more quiescent lung that is less predisposed to symptoms and exacerbations. Using prolonged exposure to house dust mite in mice, we developed a mouse model of persistent and exacerbating airway disease characterized by a mixed inflammatory phenotype. We show that lung IL-33 drives inflammation and remodeling beyond the type 2 response classically associated with IL-33 signaling. IL-33 blockade with an IL-33 neutralizing antibody normalized established inflammation and improved remodeling of both the lung epithelium and lung parenchyma. Specifically, IL-33 blockade normalized persisting and exacerbating inflammatory end points, including eosinophilic, neutrophilic, and ST2+CD4+ T-cell infiltration. Importantly, we identified a key role for IL-33 in driving lung remodeling because anti-IL-33 also re-established the presence of ciliated cells over mucus-producing cells and decreased myofibroblast numbers, even in the context of continuous allergen exposure, resulting in improved lung function. Overall, this study shows that increased IL-33 levels drive a self-perpetuating amplification loop that maintains the lung in a state of lasting inflammation and remodeled tissue primed for exacerbations. Thus IL-33 blockade might ameliorate symptoms and prevent exacerbations by quelling persistent inflammation and airway remodeling.

Sevoflurane Prevents Airway Remodeling via Downregulation of VEGF and TGF-β1 in Mice with OVA-Induced Chronic Airway Inflammation.

Asthma is characterized by chronic airway inflammation, which is the underlying cause of airway remodeling featured by goblet cell hyperplasia, subepithelial fibrosis, and proliferation of smooth muscle. Sevoflurane has been used to treat life-threatening asthma and our previous study shows that sevoflurane inhibits acute lung inflammation in ovalbumin (OVA)-induced allergic mice. However, the effect of sevoflurane on airway remodeling in the context of chronic airway inflammation and the underlying mechanism are still unknown. Here, female C57BL/6 mice were used to establish chronic airway inflammation model. Hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Sirius red (SR) staining were used to evaluate airway remodeling. Protein levels of α-SMA, VEGF, and TGF-β1 in lung tissues were detected by western blotting analyses and immunohistochemistry staining. Results showed that inhalation of sevoflurane inhibited chronic airway inflammation including inflammatory cell infiltration and pro-inflammatory cytokine production in BALF of the OVA-challenged mice. Meanwhile, sevoflurane suppressed airway thickening, goblet cell hyperplasia, smooth muscle hyperplasia, collagen deposition, and fiber hyperplasia in the lung tissues of the mice with airway remodeling. Most notably, sevoflurane inhibited the OVA-induced expressions of VEGF and TGF-β1. These results suggested that sevoflurane effectively inhibits airway remodeling in mouse model of chronic airway inflammation, which may be due to the downregulation of VEGF and TGF-β1in lung tissues. Therefore, our results indicate a potential role of sevoflurane in inhibiting airway remodeling besides its known suppression effect on airway inflammation, and support the use of sevoflurane in treating severe asthma in ICU.

The Role of Myristoylated, Alanine-rich C-kinase Substrate (MARCKS) in a Murine Model of Chronic Airway Inflammation

Abstract Severe asthma, a complicate chronic lung inflammation. Several chronic inflammatory cells that involved in the inflammatory responses, such as macrophages, neutrophils, and eosinophils, produce large amounts of ROS, the excess level of ROS would increase lung inflammation and lung injury. In fact, this inflammation is well controlled by steroid, but some subset of patients these glucocorticoids are less effective. Neutrophil recruitment is a prominent feature of acute exacerbations of chronic asthma. In patients with difficult-to-control asthma, neutrophilic inflammation rather than eosinophils often predominate. Myristoylated alanine-rich C kinase substrate (MARCKS), is a protein kinase C (PKC) substrate. MARCKS also plays a crucial role that phosphorylation of MARCKS by PKC leads its release from plasma membrane into the cytosol, participating in regulating cell migration such as macrophage and neutrophil. We found that increase of airway MARCKS phosphorylation in asthmatic patients and murine model of chronic steroid-resistance allergic asthma. In this report, our observations indicate that 1) targeting of MARCKS phosphorylation inhibited chronic asthmatic symptoms, such as eosinophil and neutrophil infiltrate into lung. MPS peptide inhibits mucus production, collagen deposition and airway hyperresponsiveness rather than steroid-resistance group; 2) targeting of MARCKS phosphorylation decreased IFN-r, IL-4, IL-17A, IL-33, eotaxin and KC production. MPS peptide also inhibit NADPH oxidase DUOX-1, 2 protein expression and end product 3-nitrotyrosine production; We found that MPS peptide shows a therapeutic potential for steroid-resistance allergic asthma.

Rho-kinase inhibition attenuates airway responsiveness, inflammation, matrix remodeling, and oxidative stress activation induced by chronic inflammation

Several studies have demonstrated the importance of Rho-kinase in the modulation of smooth muscle contraction, airway hyperresponsiveness, and inflammation. However, the effects of repeated treatment with a specific inhibitor of this pathway have not been previously investigated. We evaluated the effects of repeated treatment with Y-27632, a highly selective Rho-kinase inhibitor, on airway hyperresponsiveness, oxidative stress activation, extracellular matrix remodeling, eosinophilic inflammation, and cytokine expression in an animal model of chronic airway inflammation. Guinea pigs were subjected to seven ovalbumin or saline exposures. The treatment with Y-27632 (1 mM) started at the fifth inhalation. Seventy-two hours after the seventh inhalation, the animals' pulmonary mechanics were evaluated, and exhaled nitric oxide (E(NO)) was collected. The lungs were removed, and histological analysis was performed using morphometry. Treatment with Y-27632 in sensitized animals reduced E(NO) concentrations, maximal responses of resistance, elastance of the respiratory system, eosinophil counts, collagen and elastic fiber contents, the numbers of cells positive for IL-2, IL-4, IL-5, IL-13, inducible nitric oxide synthase, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, transforming growth factor-β, NF-κB, IFN-γ, and 8-iso-prostaglandin F2α contents compared with the untreated group (P < 0.05). We observed positive correlations among the functional responses and inflammation, remodeling, and oxidative stress pathway activation markers evaluated. In conclusion, Rho-kinase pathway activation contributes to the potentiation of the hyperresponsiveness, inflammation, the extracellular matrix remodeling process, and oxidative stress activation. These results suggest that Rho-kinase inhibitors represent potential pharmacological tools for the control of asthma.

Matrix Metalloproteinases-9 (MMPs-9) and -12 Are Upregulated in the Airways of Mice with Chronic Airway Inflammation and Remodeling

In the present study, we tried to develop a mouse model of chronic airway inflammation and remodeling induced by chronic exposure to antigen. Furthermore, the expressions of MMPs-9 and -12 were also investigated. BALB/c mice were sensitized and then repeatedly challenged with OVA every 3 days for 54 days. At the following day after the last challenge, of days 24, 39, and 54, histological changes of the airways were studied by hematoxylin-eosin and Masson's trichrome stains. The expressions of MMPs-9 and -12 were also measured by western blot. Persistent inflammatory cells infiltration and collagen deposition in the lung tissue were observed in repeatedly challenged mice. Furthermore, the expressions of MMPs-9 and -12 were increased in the airways after repeated antigen challenges. The severest inflammation was observed in the day-54 challenged group. These results suggest that MMPs-9 and -12 might be involved in the pathogenesis of chronic airway inflammation and remodeling induced by antigen exposure in mice.

Effects of Repeated Stress on Distal Airway Inflammation, Remodeling and Mechanics in an Animal Model of Chronic Airway Inflammation

Background/Aims: Epidemiological studies suggest that stress has an impact on asthmatic exacerbations. We evaluated if repeated stress, induced by forced swimming, modulates lung mechanics, distal airway inflammation and extracellular matrix remodeling in guinea pigs with chronic allergic inflammation. Methods: Guinea pigs were submitted to 7 ovalbumin or saline aerosols (1–5 mg/ml during 4 weeks; OVA and SAL groups). Twenty-four hours after the 4th inhalation, guinea pigs were submitted to the stress protocol 5 times a week during 2 weeks (SAL-S and OVA-S groups). Seventy-two hours after the 7th inhalation, guinea pigs were anesthetized and mechanically ventilated. Resistance and elastance of the respiratory system were obtained at baseline and after ovalbumin challenge. Lungs were removed, and inflammatory and extracellular matrix remodeling of distal airways was assessed by morphometry. Adrenals were removed and weighed. Results: The relative adrenal weight was greater in stressed guinea pigs compared to non-stressed animals (p < 0.001). Repeated stress increased the percent elastance of the respiratory system after antigen challenge and eosinophils and lymphocytes in the OVA-S compared to the OVA group (p < 0.001, p = 0.003 and p < 0.001). Neither collagen nor elastic fiber contents were modified by stress in sensitized animals. Conclusions: In this animal model, repeated stress amplified bronchoconstriction and inflammatory response in distal airways without interfering with extracellular matrix remodeling.

Gene Expression Profiling in Lungs of Chronic Asthmatic Mice Treated with Galectin-3: Downregulation of Inflammatory and Regulatory Genes

Background. Asthma is a disorder characterized by a predominance of Th2 cells and eosinophilic inflammation. Suppressors of cytokine signaling (SOCS) proteins act as negative regulators of cytokine signaling. In particular, SOCS1 and SOCS3 play an important role in immune response by controlling the balance between Th1 and Th2 cells. In a previous study, we demonstrated that treatment of chronic asthmatic mice with gene therapy using plasmid encoding galectin-3 (Gal-3) led to an improvement in Th2 allergic inflammation. Methods. Using a microarray approach, this study endeavored to evaluate the changes produced by therapeutic Gal-3 delivered by gene therapy in a well-characterized mouse model of chronic airway inflammation. Results were confirmed by real-time RT-PCR, Western blot and immunohistochemical analysis. Results. We identify a set of genes involved in different pathways whose expression is coordinately decreased/increased in mice treated with Gal-3 gene therapy. We report a correlation between Gal-3 treatment and inhibition of SOCS1 and SOCS3 expression in lungs. Conclusion. These results suggest that negative regulation of SOCS1 and 3 following Gal-3 treatment could be a valuable therapeutic approach in allergic disease.

Interference of methysergide, a specific 5‐hydroxytryptamine receptor antagonist, with airway chronic allergic inflammation and remodelling in a murine model of asthma

Airway remodelling encompasses the structural changes observed in asthmatic airways. Mast cells, through the release of histamine and 5-hydroxytryptamine (serotonin), are implicated in early asthmatic reactions, bronchoconstriction and mucosal oedema, and in the development of bronchial hyperresponsiveness. However, the association between serotonin and remodelling processes in murine model of airways inflammation remains to be elucidated. As serotonin is released by murine mast cells upon antigen challenge, we tested the hypothesis of its involvement in the development of inflammatory and remodelling processes in a murine model of chronic airway inflammation following prolonged allergen challenge. Methods BALB/c mice were exposed to aerosolized ovalbumin for 20 min 2 days a week, for 4 consecutive weeks. Two hours before each challenge, they were treated with methysergide (intranasally, 40 microg/kg). Forty-eight hours after the last aerosol challenge, bronchoalveolar lavage (BAL) and lung tissue were collected for analysis. Methysergide inhibited the allergen-induced increase in airway eosinophilia, reduced T helper type 2 (Th2) cytokines in lung, spleen or thoracic lymph nodes, and specific IgE levels. The extravasation of plasma and fibronectin production in the lung, and collagen deposition in the lung were also inhibited after methysergide treatment. Although methysergide treatment induced an increase in IFN-gamma levels, experiments with neutralizing antibody suggest that this is not responsible for inhibition. In addition, instillation of serotonin to immunized mice induced eosinophil recruitment to BAL, Th2 cytokine production and fibronectin release in lung as well as collagen deposition. Serotonin may contribute to the development and maintenance of remodelling through the release of cytokines and of fibrogenic mediators. Serotonin should therefore be considered as relevant for the development and maintenance of airway remodelling.

IL-1β–Induced Transcriptional Up-Regulation of Bradykinin B1and B2Receptors in Murine Airways

Hyperresponsiveness to bronchoconstrictor stimuli is a major pathophysiologic feature of asthma, but the molecular mechanisms behind this are not fully understood. The release of TNF-alpha and IL-1beta during the inflammatory process is believed to play an important role in airway hyperresponsiveness. We have previously demonstrated, using a murine in vitro model of chronic airway inflammation, that TNF-alpha up-regulated bradykinin B(1) and B(2) receptors in the airway smooth muscle. By using the same model, the present study was designed to investigate the effects of IL-1beta and its interaction with TNF-alpha on the expression of bradykinin B(1) and B(2) receptors in mouse tracheal smooth muscle. IL-1beta up-regulated bradykinin B(1) and B(2) receptor expression and increased contractile response to bradykinin B(1) and B(2) receptor agonists (des-Arg(9)-bradykinin and bradykinin, respectively) in the tracheal smooth muscle. Transcriptional inhibitor actinomycin D, c-Jun N-terminal kinase (JNK) inhibitors SP600125 and TAT-TI-JIP(153-163), but not extracellular signal-regulated kinase 1 and 2 (ERK 1/2) inhibitor PD98059, significantly attenuated this up-regulation, indicating that a transcriptional mechanism and intracellular JNK signal transduction pathway were involved. In addition, IL-1beta did not affect bradykinin B(1) and B(2) receptor mRNA stability. Remicade, an anti-TNF-alpha antibody, markedly suppressed IL-1beta-induced up-regulation of bradykinin B(1) and B(2) receptors, suggesting that TNF-alpha was involved in the up-regulation, which is further supported by the fact that IL-1beta enhanced TNF-alpha mRNA expression in the tracheae. Intracellular JNK pathway and TNF-alpha might provide key links between inflammatory mediators like IL-1beta and airway hyperresponsiveness to bradykinin.

Effect of salbutamol on pulmonary responsiveness in chronic pulmonary allergic inflammation in guinea pigs

Beta-2-agonists have been widely used by asthmatic subjects to relieve their obstructive symptoms. However, there are reports that continuous use could lead to loss of bronchial protection and exacerbation of asthma symptoms. We evaluated the effect of two regimens of salbutamol administration (twice and five times a week) in a model of chronic airway inflammation in male Hartley guinea pigs (protocol starting weight: 286 +/- 30 g) induced by repeated exposures to aerosols of ovalbumin (OVA). After sensitization, guinea pigs were exposed to aerosols of 0.1 mg/ml salbutamol solution twice a week (OVA + S2x, N = 7) or five times a week (OVA + S5x, N = 8). We studied allergen-specific (OVA inhalation time) and -nonspecific (response to methacholine) respiratory system responsiveness. Seventy-two hours after the last OVA challenge, guinea pigs were anesthetized and tracheostomized, respiratory system resistance and elastance were measured and a dose-response curve to inhaled methacholine chloride was obtained. Specific IgG1 was also quantified by the passive cutaneous anaphylactic technique. OVA-sensitized guinea pigs (N = 8) showed reduction of the time of OVA exposure before the onset of respiratory distress, at the 5th, 6th and 7th exposures (P < 0.001). The OVA + S2x group (but not the OVA + S5x group) showed a significant increase in OVA inhalation time. There were no significant differences in pulmonary responsiveness to methacholine among the experimental groups. OVA + S2x (but not OVA + S5x) animals showed a decrease in the levels of IgG(1)-specific anaphylactic antibodies compared to the OVA group (P < 0.05). Our results suggest that, in this experimental model, frequent administration of beta(2)-agonists results in a loss of some of their protective effects against the allergen.

Potential role of c-Jun NH 2-terminal kinase in allergic airway inflammation and remodelling: effects of SP600125

Asthma is a chronic inflammatory disease of the airways associated with structural changes such as increased airway smooth muscle mass, which may contribute to impairment of lung function. To determine whether c-Jun NH 2-terminal kinase (JNK) of the mitogen-activated protein kinase signalling pathway participated in these changes, the effects of an inhibitor, SP600125 (anthra [1, 9-cd] pyrazole-6 (2H)-one), were examined in a murine model of chronic airway inflammation and remodelling. Mice sensitised to ovalbumin were exposed to ovalbumin aerosol and were treated with SP600125 [30 mg kg −1 intraperitoneal (i.p.)] on days of exposure. SP600125 significantly reduced eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid, suppressed eosinophilic inflammation within the bronchial submucosa, inhibited goblet cell hyperplasia, and increased airway smooth muscle cell number in allergen-exposed mice. SP600125 also inhibited allergen-induced increase in bronchial responsiveness. SP600125 inhibited JNK activity in the challenged lungs. Although SP 600125 may also have other effects, we conclude that c-Jun NH 2-terminal kinase may play a role in allergen-induced inflammation and remodelling associated with bronchial hyperresponsiveness.

Is platelet activating factor (PAF) an important mediator in bronchial asthma?

The development of selective PAF receptor antagonists may provide a novel approach to the treatment of human bronchial asthma. In preclinical animal models of human asthma, PAF receptor antagonists have been found to be efficacious in blocking antigen-induced changes in lung function. However, the majority of these models involve acute inflammatory events and transient changes in lung function and, therefore, their relevance to human asthma is questionable. In a recent study with a primate model of chronic airway inflammation and hyperresponsiveness, we have shown that treatment with a PAF receptor antagonist had no effect on reducing chronic inflammation and hyperresponsiveness. Similarly, recent studies in human asthmatics with PAF receptor antagonists have failed to show efficacy in blocking allergen-induced airway responses or to have any steroid sparing effects in patients with ongoing asthma. Thus, it seems that PAF may not be a key mediator which can be blocked and thereby provide therapy for bronchial asthma.