Therapeutic administration of Budesonide ameliorates allergen-induced airway remodelling

BACKGROUND: Airway inflammation and remodelling are important pathophysiologic features of chronic asthma. Although current steroid use demonstrates anti-inflammatory activity, there are limited effects on the structural changes in the lung tissue. OBJECTIVE: We have used a mouse model of prolonged allergen challenge that exhibits many of the salient features of airway remodelling in order to investigate the anti-remodelling effects of Budesonide. METHODS: Treatment was administered therapeutically, with dosing starting after the onset of established eosinophilic airway inflammation and hyper-reactivity. RESULTS: Budesonide administration reduced airway hyper-reactivity and leukocyte infiltration in association with a decrease in production of the Th2 mediators, IL-4, IL-13 and eotaxin-1. A reduction in peribronchiolar collagen deposition and mucus production was observed. Moreover, our data show for the first time that, Budesonide treatment regulated active transforming growth factor (TGF)-beta signalling with a reduction in the expression of pSmad 2 and the concomitant up-regulation of Smad 7 in lung tissue sections. CONCLUSIONS: Therefore, we have determined that administration of Budesonide modulates the progression of airway remodelling following prolonged allergen challenge via regulation of inflammation and active TGF-beta signalling.     

The effect of eosinophils on collagen gel contraction and implications for tissue remodelling

Asthma is characterized by an eosinophilic inflammation and a subepithelial fibrosis in the airways. Eosinophils contain several cytotoxic substances, such as eosinophil cationic protein (ECP), which can promote inflammation and cause tissue damage. This has generated the hypothesis that eosinophils may drive remodelling of extracellular matrix (ECM). To investigate the role of eosinophils we used an in vitro model for remodelling, the three-dimensional collagen gel contraction assay. Two sources of eosinophils were used in this study, isolated human peripheral eosinophils (purity > 95%) and stimulated [interleukin (IL)-5, IL-3 and granulocyte macrophage-colony stimulating factor (GM-CSF)] HL-60 clone 15 cells. Human eosinophils or HL-60 cells were cast together with human lung fibroblasts (HFL1) in type I collagen gels. Both types of eosinophils augmented fibroblast-mediated collagen gel contraction in a time and concentration-dependent manner. At 48 h, the gel area in HFL1/eosinophil co-culture was 46.5% +/- 0.5 (mean +/- s.e.m.) of initial area and in HFL1 culture 52.3% +/- 0.1 (P < 0.001). Respective figures for HFL1/stimulated HL-60 co-culture and HFL1 culture only were 44.1% +/- 0.5 and 52.4% +/- 0.4 (P < 0.001). The release of ECP was increased when fibroblasts were cultured with eosinophils compared to eosinophils cultured alone. In addition, native ECP added to fibroblast gel cultures also augmented contraction. Our results suggest that eosinophils may interact with mesenchymal cells, promoting remodelling of ECM and that ECP constitutes one potential eosinophil-derived mediator driving this process. We conclude that this may be one important mechanism by which eosinophil-ECM interactions will lead to airway tissue remodelling in asthma.     

Involvement of distal airways in a chronic model of experimental asthma

BACKGROUND: Bronchial asthma is characterized by chronic airway inflammation and airway remodelling which occurs in both proximal and distal airways. These changes are associated with development of airway hyper-responsiveness and airflow limitation. OBJECTIVE: This study was aimed to analyse whether chronic inhalative allergen challenges in mice lead to morphological and physiological changes comparable with this phenotype. METHODS: For this purpose, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed by aerosol allergen challenges on 2 consecutive days per week for 12 weeks. RESULTS: In chronically challenged mice, tissue inflammation in proximal as well as distal airways was observed with a predominance of lymphocytes within the cellular infiltrate. In contrast, inflammation in the airway lumen decreased over time. These changes were associated by a shift in bronchoalveolar lavage-cytokine levels from IL-4, IL-5 and TNF-alpha production (during the acute phase) towards markedly increased levels of TGF-beta during the chronic phase. Goblet cell hyperplasia and subepithelial fibrosis occurred throughout the airway tree. In terms of lung function, chronically challenged mice developed persistent bronchial hyper-responsiveness and progressive airflow limitation. Six weeks after OVA aerosol discontinuation, airway inflammation still persisted although lung function was normalized. CONCLUSION: These data indicate that our model of chronic aerosol allergen challenges leads to a phenotype of experimental asthma with participation of distal airways and persistence of inflammation thereby resembling many morphological and physiological aspects of human bronchial asthma.     

Eosinophils: important players in humoral immunity

Eosinophils perform numerous tasks. They are involved in inflammatory reactions associated with innate immune defence against parasitic infections and are also involved in pathological processes in response to allergens. Recently, however, it has become clear that eosinophils also play crucial non‐inflammatory roles in the generation and maintenance of adaptive immune responses. Eosinophils, being a major source of the plasma cell survival factor APRIL (activation and proliferation‐induced ligand), are essential not only for the long‐term survival of plasma cells in the bone marrow, but also for the maintenance of these cells in the lamina propria which underlies the gut epithelium. At steady state under non‐inflammatory conditions eosinophils are resident cells of the gastrointestinal tract, although only few are present in the major organized lymphoid tissue of the gut – the Peyer's patches (PP). Surprisingly, however, lack of eosinophils abolishes efficient class‐switching of B cells to immunoglobulin (Ig)A in the germinal centres of PP. Thus, eosinophils are required to generate and to maintain mucosal IgA plasma cells, and as a consequence their absence leads to a marked reduction of IgA both in serum and in the gut‐associated lymphoid tissues (GALT). Eosinophils thus have an essential part in long‐term humoral immune protection, as they are crucial for the longevity of antibody‐producing plasma cells in the bone marrow and, in addition, for gut immune homeostasis.     

Variations of Blood Eosinophils and Eosinophil Cationic Protein in Serum in Patients with Bronchial Asthma

Inhalation challenge test was performed in 12 patients with bronchial asthma. The subsequent variation in blood eosinophils and serum-eosinophil canonic protein was followed up. Uniform patterns in both parameters were seen suggesting active participation of the eosinophil leucocyte in allergic: inflammation.     

Reversibility of airway inflammation and remodelling following cessation of antigenic challenge in a model of chronic asthma

BACKGROUND: Asthma is associated with recruitment of eosinophils, accumulation of chronic inflammatory cells in the airway walls, subepithelial fibrosis and other structural changes of airway wall remodelling. The role of ongoing exposure to allergens in their pathogenesis remains unclear. OBJECTIVE: To examine whether changes of inflammation and remodelling were reversible following cessation of antigenic challenge in a mouse model of chronic asthma. METHODS: BALB/c mice sensitized to ovalbumin (OVA) were chronically challenged by inhalation of a low mass concentration of antigen for 8 weeks, leading to development of acute-on-chronic airway inflammation, subepithelial fibrosis and other changes of airway wall remodelling. Epithelial injury was assessed by immunohistochemistry, while inflammation and remodelling were quantified by appropriate histomorphometric techniques. Regression of lesions was assessed in animals examined at 1, 2 and 4 weeks after exposure to OVA ceased. RESULTS: We did not find evidence of airway epithelial injury in this model of low-level chronic inhalational exposure to antigen. Persistence of the recruitment of eosinophils and chronic inflammatory cells in the airway walls was dependent on continuing antigenic challenge, as was persistence of mucous cell hyperplasia/metaplasia. Subepithelial fibrosis and epithelial hypertrophy exhibited delayed reversibility following cessation of exposure to antigen, possibly related to matrix-associated accumulation of transforming growth factor-beta(1). CONCLUSION: In chronic asthma, low-level antigenic challenge may be required to maintain the inflammatory response in the airway wall, but airway remodelling may persist in its absence.     

Platelet-derived growth factor and transforming growth factor-β modulate the expression of matrix metalloproteinases and migratory function of human airway smooth muscle cells

Background Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinase (TIMPs) have been suggested to be involved in the pathogenesis of asthma. Their expression in airway smooth muscle (ASM) cells could be involved in collagen turnover and migration of these cells and thus may contribute to airway remodelling.
Objective To examine the effect of pro-fibrotic growth factors TGF-β and platelet-derived growth factor (PDGF) on the expression of MMPs/TIMPs in cultured human ASM cells and to examine the role of MMP in the migration of ASM cells.
Methods ASM cells were stimulated with TGF-β and/or PDGF. Expression and activity of MMP-1, MMP-2, MMP-3, TIMP-1 and TIMP-2 were evaluated by quantitative RT-PCR, Western blot and zymography. Modified Boyden-chamber migration assay was performed to investigate the effect of secreted MMP-3 and TIMP-1 on ASM-cell migration.
Results PDGF strongly up-regulated the expression of MMP-1 at mRNA and protein levels. PDGF, when combined with TGF-β, caused synergistic up-regulation of MMP-3. TIMP-1 was additively up-regulated by TGF-β and PDGF. These growth factors had no effect on the expression of MMP-2 and TIMP-2. U0126, an extracellular signal-regulated kinase (ERK) pathway inhibitor, inhibited the up-regulation of MMP-1 by PDGF. The synergistic/additive up-regulation of MMP-3 and TIMP-1 was inhibited by U0126 and SB431542, a Smad pathway inhibitor. Supernatant from ASM cells in which MMP-3 production was knocked down by RNA interference showed a decreased migratory effect on ASM cells, whereas supernatant from cells with suppressed TIMP-1 expression resulted in increased migration.
Conclusion Our results suggest that PDGF with/without TGF-β could facilitate migration of ASM cells by modification of MMP–TIMP balance through the ERK pathway.     

哮喘患者血浆类胰蛋白酶、血嗜酸粒细胞和气道高反应性相互关系

为探讨肥大细胞、嗜酸粒细胞和气道高反应性相互关系 ,本文检测了 36例哮喘患者 (哮喘组 )及 2 9例健康人 (对照组 )血浆中激活肥大细胞的特征性标志物类胰蛋白酶值、血嗜酸粒细胞 (EOS )值及乙酰甲胆碱的支气管激发试验 (PC2 0 )值 ,并对三者关系进行分析比较 ,结果 :(1)哮喘组血浆类胰蛋白酶增高率为 36 11% (13/ 36)和EOS增高率为 38 89% (14/ 36 ) ,明显高于对照组 (P分别 <0 0 0 5 ) ;(2 )哮喘组PC2 0 值 <8g/L者占 81 82 % (2 7/ 33) ,显著低于对照组 (P <0 0 0 5 ) ;(3)哮喘EOS增高组的PC2 0 值为 1 2 1g/L ,明显低于EOS正常组的 5 11g/L (P <0 0 1) ;(4 )哮喘类胰蛋白酶增高组中有 61 5 3% (8/13)EOS值增高 ,明显高于类胰蛋白酶正常组的 2 6 0 9% (6/ 2 3) (P <0 0 5 )。综上所述 ,哮喘患者呈气道高反应 ,血EOS和类胰蛋白酶值增高 ;EOS与气道高反应性有关 ;类胰蛋白酶与EOS增高有关 ,但未直接与气道高反应性相关     

Enhanced osteopontin expression in a murine model of allergen-induced airway remodelling

BACKGROUND: Airway remodelling is a central pathophysiological feature of chronic asthma. A wide variety of cytokines and growth factors are likely to be involved in the development of airway remodelling. Osteopontin (OPN) is a cytokine with pro-fibrotic properties; however, its role in airway remodelling in asthma has not been explored. OBJECTIVE: To determine the expression and cellular sources of OPN in a murine model of chronic allergen-induced airway remodelling. METHODS: BALB/c mice were sensitized and exposed to ovalbumin (OVA) or saline inhalations for 5 weeks and killed 24 h after the last inhalation. The following parameters of inflammation and remodelling were assessed: differential cell counts in bronchoalveolar lavage (BAL) fluid lung collagen content (colorimetric biochemical assay) and peribronchial smooth muscle content (immunohistochemistry, followed by image analysis). OPN expression in BAL and lung tissue was determined by PCR and ELISA. The cellular source and distribution of OPN were evaluated by immunohistochemistry and immunofluorescence. RESULTS: OPN expression is up-regulated in lung tissue and in BAL fluid of OVA-treated mice and correlates with collagen content and peribronchial smooth muscle area. In addition, OPN significantly increases collagen deposition in vitro in a murine lung cell line. Cells producing OPN include the airway epithelium and cells of the submucosal inflammatory infiltrate (T cells, eosinophils, and macrophages). Positive staining for OPN was also observed in bronchial tissue from human asthmatic subjects. CONCLUSION: OPN expression in the lungs is increased in a murine model of allergen-induced chronic airway remodelling, suggesting a role for this cytokine in airway remodelling in asthma.     

Idiopathic pulmonary fibrosis: immunohistochemical analysis provides fresh insights into lung tissue remodelling with implications for novel prognostic markers

Aim

This study explored the cellular and biological interrelationships involved in Idiopathic Pulmonary Fibrosis (IPF) lung tissue remodelling using immunohistochemical analysis.

Methods and results

IPF and control lung tissues were examined for localisation of Epithelial Mesenchymal Transition (EMT), proliferation and growth factor markers assessing their relationship to key histological aberrations. E-cadherin was expressed in IPF and control (Alveolar type II) ATII cells (>75%). In IPF, mean expression of N-cadherin was scanty (<10%): however 4 cases demonstrated augmented expression in ATII cells correlating to histological disease status (Pearson correlation score 0.557). Twist was expressed within fibroblastic foci but not in ATII cells. Transforming Growth Factor- β (TGF-β) protein expression was significantly increased in IPF ATII cells with variable expression within fibroblastic foci. Antigen Ki-67 was observed within hyperplastic ATII cells but not in cells overlying foci. Collagen I and α-smooth muscle actin (α-SMA) were strongly expressed within fibroblastic foci (>75%); cytoplasmic collagen I in ATII cells was present in 3 IPF cases. IPF ATII cells demonstrated variable Surfactant Protein-C (SP-C).

Conclusions

The pathogenesis of IPF is complex and involves multiple factors, possibly including EMT. Histological analysis suggests TGF-β-stimulated myofib rob lasts initiate a contractile response within established fibroblastic foci while proliferating ATII cells attempt to instigate alveolar epithelium repair. Marker expression (N-cadherin and Ki-67) correlation with histological disease activity (as reflected by fibroblastic foci extent) may emerge as future prognostic indicators for IPF.     

动载荷作用下骨重建力学调控机制

目的探讨动载荷作用下骨重建的力学调控机制。方法对骨重建力学调控机制进行分析,吸纳力学疲劳强度理论思想,提出动载荷作用下骨重建力学调控机制;选取损伤作为力学激励,建立动载荷骨重建模型;分析动态载荷成骨效果优于静态载荷现象,数值模拟运动防治骨质疏松。结果动态载荷成骨效果优于静态载荷现象得到较为合理的解释;运动量增加10%~30%,骨密度增加3.13%~8.61%。结论动载荷作用下骨重建的力学调控机制可为机械振动防治骨代谢相关疾病提供理论指导,是骨重建力学调控理论的补充和完善。     

The roles of CyPA and CD147 in cardiac remodelling

Cyclophilin A (CyPA), an abundantly expressed protein belonging to the immunophilin family, is involved in a variety of physiological and pathological activities together with its extracellular receptor, CD147. Many studies have provided compelling evidence supporting critical roles of CyPA in immune and infectious diseases and malignant tumours. Recent studies have revealed that both CyPA and CD147 strongly promote cardiovascular inflammation, myocardial ischaemia-reperfusion injury, and myocardial remodelling processes. Here, we review the potential roles of CyPA and CD147 in cardiac remodelling and their implications for the development of novel pharmacological therapies for heart failure.