Rat Model Of Chronic Asthma Research Articles

Systemic administration of c-Kit+ cells diminished pulmonary and vascular inflammation in rat model of chronic asthma

BackgroundTo circumvent some pitfalls related to acute status, chronic model of asthma is conceived to be more suitable approach to guarantee the conditions which are similar to human pulmonary disease. Here, possible therapeutic mechanisms were monitored by which c-kit+ bone marrow cells can attenuate vascular inflammation in rat model of chronic asthma.ResultsData revealed c-Kit+ cells could significantly reduce pathological injures in asthmatic rats via modulating the expression of IL-4, INF-γ, ICAM-1 and VCAM-1 in lung tissues and TNF-α, IL-1β and NO levels in BALF (p < 0.001 to p < 0.05). Besides, c-Kit+ cells reduced increased levels of VCAM-1 evaluated by immunohistochemistry staining. In contrast to c-Kit+ cells, c-Kit− cells could not exert beneficial effects in the asthmatic conditions.ConclusionOverall, we found that systemic administration of C-kit positive cells can diminish pulmonary and vascular inflammation of chronic asthmatic changes in a rat model. These cells are eligible to suppress inflammation and nitrosative stress in lung tissue coincides with the reduction of pathological changes. These data indicate that C-kit positive cells be used as an alternative cell source for the amelioration of asthmatic changes.

Effects of Aspergillus fumigatus on glucocorticoid receptor and β2-adrenergic receptor expression in a rat model of asthma

ABSTRACTPurpose: Conventional inhaled corticosteroids or β2-adrenergic receptor agonists do not work well in some asthmatic populations while empirical antifungal therapy has obvious impact on those patients. The study was designed to investigate whether short-term exposure to Aspergillus fumigatus (A. fumigatus) could decrease glucocorticoid receptor (GCR) and β2-adrenergic receptor (ADRB2) expression in lung tissue of asthmatic rats. Materials and Methods: A rat model of chronic asthma was first established by ovalbumin sensitization and challenge. Rats with chronic asthma were then exposed to short-term application of A. fumigatus spores. Airway hyper-responsiveness, eosinophil ratio in bronchoalveolar lavage (BAL) fluid and total IgE in serum were counted in these experimental animals. GCR and ADRB2 expression in the lung were detected and analyzed. Furthermore, the levels of toll-like receptors (TLRs) 2, 3 and 4 in lung tissue were measured. Results: Short-term exposure to A. fumigatus could down-regulate the expression of GCR, aggravate airway hyper-responsiveness and increase the level of TLR2 in rats with asthma. There were no obvious changes in the levels of ADRB2 expression, recruited eosinophils, total IgE, TLR3 and TLR4 after application of A. fumigatus in asthmatic rats. Conclusions: These findings indicate that A. fumigatus exposure may be involved in glucocorticoids unresponsiveness by down-regulating the expression of GCR in asthmatics. The possibility of A. fumigatus colonization or infection should not be ignored in patients of steroid-resistant asthma.

Cordycepin inhibits airway remodeling in a rat model of chronic asthma.

The potential suppression role of cordycepin (Cor) on airway remodeling in a rat model of chronic asthma was investigated in this paper. We evaluated the anti-remodeling of Cor (50mg/kg) combined with or without budesonide (BUD) and investigated the possible underlying molecular mechanisms. We found that Cor attenuated immunoglobulin (Ig) E, alleviated the airway wall thickness, and decreased eosinophils and neutrophils in the bronchoalveolar lavage fluid (BALF). Notably, Cor reduced the up-regulation of IL-5, IL-13 and TNF-α in the BALF. Cor also regulated the increase of A2AARmRNA and the decrease of TGF-β1 expression. Furthermore, Cor markedly blocked p38MAPK signaling pathway activation in the OVA-driven asthmatic mice. The combination treatment of Cor and BUD showed profound efficacy in regulating the levels of inflammatory cells and the expression of IL-13, TGF-β1 and A2AARmRNA. Collectively, this study demonstrated that Cor combined with glucocorticoids treatment shows synergistically profound efficacy in inhibiting airway remodeling, and some benefits of Cor may result from the increased A2AARmRNA expression, the reduced TGF-β1 levels and the inhibition of Th2-cytokines through the suppression of the p38MAPK signaling pathways.

Role of the extracellular signal-regulated kinase 1/2 signaling pathway in the process of thrombin-promoting airway remodeling in ovalbumin-allergic rats

Context: Although it is recognized that thrombin plays a key role in airway remodeling during chronic asthma. In a previous study, we have proved that thrombin promotes airway remodeling via PAR-1 in OVA-allergic rats, but little is known about intracellular signaling pathway involved in the event.Objective: In this study, we intend to explore the impact of pERK1/2 signaling pathway on the process of thrombin-induced airway remodeling in OVA-allergic rats.Materials and methods: A rat model of chronic asthma was set up by systemic sensitization and repeated challenge to OVA. The doses of thrombin, recombinant hirudin, PAR-1 inhibitor ER-112780-06, and pERK1/2 inhibitor PD98059 varied for different groups. The expression of pERK1/2 was analyzed by western blot and RT-PCR. Secretion of TGF-β1 and IL-6 was detected by ELISA.Results: The expression of pERK1/2 was higher in the airway of asthmatic rats than those of normal rats, and was significantly increased by thrombin treatment but decreased by thrombin-inhibitor treatment. Airway remodeling was enhanced by thrombin but weakened by pERK1/2 inhibitor. Expression of growth factors and IL-6 in asthmatic rats was significantly increased by thrombin treatment and decreased by thrombin-inhibitor treatment and pERK1/2 inhibitor treatment.Conclusion: These results suggest that ERK1/2 signaling pathway may play an important role in the process of thrombin-promoting airway remodeling in OVA-allergic rats, and pERK1/2 inhibitor effectively inhibits the process.

Effects of chronic exposure to Aspergillus fumigatus on epidermal growth factor receptor expression in the airway epithelial cells of asthmatic rats

ABSTRACTEpidemiologic studies suggest that increased concentrations of airborne spores of Aspergillus fumigatus closely relate to asthma aggravation. Chronic exposure to A. fumigatus aggravates airway inflammation, remodeling, and airway hyperresponsiveness in asthmatic rats. The effects of chronic exposure to A. fumigatus on epidermal growth factor receptor (EGFR) expression in the airway epithelial cells of asthmatic rats remain unclear. This study aimed to investigate the effects of chronic exposure to A. fumigatus on injury and shedding of airway epithelium, goblet cell metaplasia, and EGFR expression in the airway epithelial cells of asthmatic rats. A rat model of chronic asthma was established using ovalbumin (OVA) sensitization and challenge. Rats with chronic asthma were then exposed to long-term inhalation of spores of A. fumigatus, and the dynamic changes in injury and shedding of airway epithelium, goblet cell metaplasia, and EGFR expression were observed and analyzed. Chronic exposure to A. fumigatus could aggravate airway epithelial cell damage, upregulate the expression of EGFR and its ligands EGF and TGF-α, promote goblet cell metaplasia, and increase airway responsiveness in rats with asthma. Chronic exposure to A. fumigatus upregulates the expression of EGFR and its ligands in asthmatic rats. The EGFR pathway may play a role in asthma aggravation induced by exposure to A. fumigatus.

Role of prostaglandin D2/CRTH2 pathway on asthma exacerbation induced by Aspergillus fumigatus

Aspergillus fumigatus is often associated in asthmatic patients with the exacerbation of asthma symptoms. The pathomechanism of this phenomenon has not been fully understood. Here, we evaluated the immunological mechanisms and the role of the prostaglandin D2 / Chemoattractant Receptor-Homologous Molecule Expressed on Th2 Cells (CRTH2) pathway in the development of Aspergillus-associated asthma exacerbation. We studied the effects of A.fumigatus on airway inflammation and bronchial hyper-responsiveness in a rat model of chronic asthma. Inhalation delivery of A.fumigatus conidia increased the airway eosinophilia and bronchial hyper-responsiveness in ovalbumin-sensitized, challenged rats. These changes were associated with prostaglandin D2 synthesis and CRTH2 expression in the lungs. Direct inflammation occurred in ovalbumin-sensitized, challenged animals, whereas pre-treatment with an antagonist against CRTH2 nearly completely eliminated the A.fumigatus-induced worsening of airway eosinophilia and bronchial hyper-responsiveness. Our data demonstrate that production of prostaglandin D2 followed by eosinophil recruitment into the airways via a CRTH2 receptor are the major pathogenic factors responsible for the A.fumigatus-induced enhancement of airway inflammation and responsiveness.

Nerve growth factor exacerbates allergic lung inflammation and airway remodeling in a rat model of chronic asthma

Nerve growth factor (NGF) is critical in the pathogenesis of allergic airway inflammation in vivo and induces proliferation of airway smooth muscle cells and matrix metalloproteinase-9 (MMP-9) expression in vitro. However, the effects of NGF on chronic pulmonary diseases of allergic origin remain unknown. To investigate the effects of NGF on lung inflammation and airway remodeling, 32 Wistar rats were randomly divided into four groups: control, NGF, ovalbumin (OVA) and anti-rat-β-NGF antibody (anti-NGF). Aerosolized OVA was administered to the rats in the NGF, OVA and anti-NGF groups to generate the asthmatic rat model, and NGF or anti-NGF was administered 3 h prior to OVA inhalation every two days. On day 70, bronchial responsiveness tests, bronchoalveolar lavage (BAL) and cell counting were conducted. The levels of serum OVA-specific immunoglobulin E (IgE) and of T-helper cell type-2 (Th2) cytokines [interleukin (IL)-4 and IL-13] in the BAL fluid were measured by enzyme-linked immunosorbent assay. The expression levels of NGF protein and MMP-9 mRNA, and the activity of MMP-9 in the lungs were detected by western blot analysis, quantitative polymerase chain reaction and gelatin zymography analysis, respectively. Our results showed that NGF significantly increased eosinophilic airway inflammation, persistent airway hyperresponsiveness (AHR), the serum levels of OVA-specific IgE and the levels of Th2 cytokines in the BAL fluid, and also increased the expression levels and activity of MMP-9. However, anti-NGF treatment significantly inhibited eosinophilic airway inflammation, persistent AHR and airway remodeling. The results showed that NGF may have exacerbated the development of airway inflammation, AHR and airway remodeling through a Th2 pathway and by increasing the level of MMP-9 expression. Therefore, anti-NGF is potentially beneficial for preventing and treating patients with asthma.

Thrombin promotes airway remodeling via protease-activated receptor-1 and transforming growth factor-β1 in ovalbumin-allergic rats

Background: Protease-activated receptor-1 (PAR-1) is widely distributed in platelets and involved in coagulation cascade activated by thrombin. In this study, we intend to explore the role of PAR-1 in the process of thrombin-inducing transforming growth factor-β1 (TGF-β1) to promote airway remodeling in ovalbumin (OVA)-allergic rats.Materials and methods: A rat model of chronic asthma was set up by systemic sensitization and repeated challenge to OVA. The doses of thrombin, recombinant hirudin, PAR-1 inhibitor ER-112780-06 varied for different groups. We evaluated the bronchoalveolar lavage fluid (BALF) concentration of thrombin in these groups. The protein and gene expression of PAR-1 was assessed and the expression of TGF-β1 was also detected.Results: The PAR-1 mRNA level and the protein level were higher in the airway of asthmatic rats than those of normal rats, and were significantly increased by thrombin treatment but decreased by thrombin-inhibitor treatment. Airway remodeling was strengthened by thrombin but weakened by thrombin inhibitor and PAR-1 antagonist. Expression of TGF-β1 protein in asthmatic rats was significantly increased by thrombin treatment and decreased by thrombin-inhibitor treatment and PAR-1 antagonist treatment.Conclusion: The expression of PAR-1 is regulated by thrombin that induces the expression of TGF-β1 to promote airway remodeling via PAR-1 in OVA-allergic rats.

Chronic Aspergillus fumigatus exposure upregulates the expression of mucin 5AC in the airways of asthmatic rats

ABSTRACTBackground: Airway mucus hypersecretion is associated with increased morbidity and mortality in patients with asthma. Chronic Aspergillus fumigatus (A. fumigatus) exposure leads to aggravation of airway inflammation and remodeling, including goblet cell hyperplasia (GCH) and mucus hypersecretion in a rat model of asthma. The effects of chronic A. fumigatus exposure on the expression of airway mucin 5AC (MUC5AC) are unknown. Methods: The rat model of chronic asthma was set up by systemic sensitization and repeated challenge to ovalbumin (OVA). The asthmatic rats were exposed to chronic intranasal inhalation of A. fumigatus spores. The changes of MUC5AC expression, the extent of GCH, and airway hyperreactivity (AHR) were measured after exposure to the fungus. Results and Conclusions: Chronic exposure to A. fumigatus upregulates the expression of MUC5AC, and induces GCH in the airways of asthma rats, and the remodeling changes of the airway epithelium was positively correlated with AHR. Upregulation of MUC5AC and induction of GCH may be mechanisms by which chronic A. fumigatus exposure promotes the progression of asthma.

Chronic intranasal administration of Aspergillus fumigatus spores leads to aggravation of airway inflammation and remodelling in asthmatic rats

Epidemiological evidence indicates a close link between exposure to fungi and deterioration of asthma. However, the role of fungi as an exogenous precipitant for initiation and progression of asthma has been incompletely explored. In this study, the effects of Aspergillus fumigatus exposure on airway inflammation and remodelling in a rat model of chronic asthma were investigated. The rat model of chronic asthma was established by systemic sensitization and repeated challenge with ovalbumin (OVA). The asthmatic rats were exposed to chronic intranasal inhalation of A. fumigatus spores. Changes in airway inflammation, remodelling and BHR were measured after exposure to the fungus. Chronic inhalation of A. fumigatus spores elevated the production of T helper 2 (Th2) cytokines, increased the concentration of total serum IgE, and resulted in the recruitment of eosinophils and lymphocyte infiltration into the airways of asthmatic rats. Goblet cell hyperplasia, mucus hyperproduction and subepithelial collagen deposition were also induced by inhalation of the fungus. The remodelling changes induced by inhalation of the fungus paralleled the changes in BHR in this rat model of asthma. Chronic exposure to A. fumigatus aggravated Th2 airway inflammation, promoted airway remodelling and increased BHR in OVA-sensitized and -challenged rats.

Role of the extracellular signal-regulated kinase 1/2 signaling pathway in regulating the secretion of bronchial smooth muscle cells in a rat model of chronic asthma

Although it is recognized that bronchial smooth muscle cells (BSMCs) play a key role in airway remodeling during chronic asthma, it is not well understood how BSMCs exert their inflammatory functions. The extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway is an important signaling pathway in chronic asthma, but its influence on secretion by BSMCs has not been well-studied. We investigated the impact of ERK1/2 signaling pathway on secretion by BSMCs in a rat model of chronic asthma in this study. To create a rat model of chronic asthma, Wistar rats underwent ovalbumim (OVA) injection and eight weeks of inhalation. BSMCs were isolated and cultured in vitro. Epidermal growth factor, PD98059 and ERK1/2 antisense oligonucleotide were used to explore the role of ERK1/2 signaling pathway. The expression of P-ERK1/2 (phospho-ERK1/2) in BSMCs was analyzed by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR). Secretion of BSMCs was detected by enzyme-linked immunosorbent assay (ELISA). Phospho-ERK1/2 expression was increased in BSMCs of chronic asthmatic rats compared with the controls. PD98059 inhibited expression of phospho-ERK1/2 protein, while treatment with an antisense oligonucleotide inhibited the expression of P-ERK1/2 mRNA and protein. BSMCs obtained from the chronic asthma group secreted significantly greater quantities of growth factors (transforming growth factor (TGF)-beta(1), vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF)), cytokines (regulated upon activation, normal T cell-expressed and secreted (RANTES) and eotaxin), and extracellular matrix (fibronectin and collagen I) compared with normal controls. Epidermal growth factor stimulated secretion in both groups, but the response of the chronic asthma group was more intense. Both PD98059 and antisense oligonucleotide suppressed secretion by BSMCs in chronic ashmatic rats. Antisense oligonucleotide reduced the level of RANTES nearly to that of normal controls, while PD98059 could not. These results suggest that ERK1/2 signaling pathway may play an important role in the augmented secretion of BSMCs in chronic asthmatic rats, and ERK1/2 antisense oligonucleotide effectively inhibits the process.

ERK1/2 Signaling Pathway Modulates the Airway Smooth Muscle Cell Phenotype in the Rat Model of Chronic Asthma

Background: It has been demonstrated that the phenotypic modulation of airway smooth muscle cells (ASMCs) is important to the pathogenesis of airway remodeling in chronic asthma. The extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway is one of the most important transduction pathways involved in the process of asthma; however, its role in the phenotypic transition of ASMCs remains unclear. Objectives: To examine the role of ERK1/2 in the phenotypic modulation of ASMCs in the rat model of chronic asthma. Methods: Bronchial smooth muscle strips were cultured in vitro in the presence of the ERK1/2 agonist epidermal growth factor or/and the MEK inhibitor PD98059. The phenotype of ASMCs was determined by observing these cells under an electron microscope and analyzing expression of phenotypic markers (smooth muscle α-actin for the contractile phenotype and osteopontin for the synthetic) by using Western blot and reverse-transcriptase polymerase chain reaction, respectively. Results: The phenotype of the ASMCs from the chronic asthmatic rats changed from the contractile type to the synthetic type with synthetic organelles abundantly gathered around the nucleus and altered expression of phenotypic markers. ERK1/2 was strongly expressed in the ASMCs of the chronic asthmatic rats and its activation by epidermal growth factor excessively promoted the synthetic function of ASMCs; the MEK inhibitor PD98059, however, reversed this phenotypic change in the ASMCs. Conclusions: Our results reveal a key role of the ERK1/2 signaling pathway in the phenotypic modulation of ASMCs in chronic asthmatic rats, indicating that specific inhibition of ERK1/2 in ASMCs may be therapeutically valuable in the control of airway remodeling in chronic asthma.

Keratinocyte growth factor improves alterations of lung permeability and bronchial epithelium in allergic rats

Chronic allergic asthma is associated with marked inflammatory reaction, microvascular leakage and epithelium injury. As previously shown in a rat model of chronic asthma, these alterations increase lung permeability and distal airway fluid clearance. Keratinocyte growth factor (KGF) has been shown to induce epithelial cell proliferation and to protect from acute lung injuries. Therefore, the current authors evaluated the potential role of KGF treatment on lung permeability and airway inflammation in rats with chronic asthma. KGF (1 mg x kg(-1)) was administered intravenously before the last ovalbumin (OVA) challenge in sensitised rats. Permeability was assessed by the leak of radiolabelled albumin from the alveolar and systemic compartments. Histopathological analysis was also performed. Treatment with KGF decreased the leak of both markers and decreased the level of extravascular lung water in sensitised rats challenged with OVA. KGF treatment also reduced the inflammatory cell number in bronchoalveolar lavage fluid but not in bronchial mucosa. KGF markedly limited the allergen-induced alterations in epithelium integrity and the expression of the intercellular junction proteins beta-catenin and zonula occludens protein-1. In conclusion, keratinocyte growth factor administration markedly limits lung permeability and airway inflammation, an effect associated with a decrease in epithelium alterations during chronic allergic asthma. These data open new prospects in the therapeutic strategy of asthma.