Effect of erythromycin on bronchial hyperreactivity and inflammation in ovalbumin-sensitized brown Norway rats

Effects of aminophylline on airway epithelial-mesenchymal transition in brown Norway rats after repeated allergen challenge

Purpose: Chronic asthma is characterized by airway inflammation and remodeling. The aim of this study is to evaluate the effects of aminophylline on airway epithelial-mesenchymal transition (EMT). Materials and methods: Two experimental groups of brown Norway rats that were repeatedly challenged with aerosolized ovalbumin (OA) were given oral aminophylline (OA-aminophylline group) or saline only (OA-saline group). A third group was challenged by saline as a control. The rats were anesthetized and pulmonary function were performed. Immuno-histochemical staining of epithelial markers (zonula occludens-1 (ZO-1)) and mesenchymal markers (vimentin) in the airway were performed. The protein expressions of ZO-1, E-cadherin, vimentin, fibronectine, TGF-ß1, SMAD 2/3, JNK, and p38 MAPK were examined by western blot. Results: Aminophylline had beneficial effects on airway inflammation, and airway remodeling in the OA-aminophylline group compared to the OA-saline group. The OA-saline group had decreased ZO-1 but increased vimentin according to immuno-histochemical staining. The protein expression indicated decreases in ZO-1 and E-cadherin but increases in vimentin, fibronectine, TGF-ß1, SMAD 2/3, JNK, and p38 MAPK in comparison to the other two groups. The OA-aminophylline group had higher ZO-1 but lower vimentin in immuno-histochemical staining compared to the OA-saline group. The protein expression showed higher ZO-1 and E-cadherin but lower vimentin, fibronectine, TGF-ß1, SMAD 2/3, JNK, and p38 MAPK when compared to the OA-saline group. Conclusions: Ovalbumin increases airway remodeling and airway EMT. Aminophylline is effective in preventing airway remodeling and airway EMT in Brown Norway rats after repeated allergen challenge.

Clarithromycin might attenuate the airway inflammation of smoke-exposed asthmatic mice via affecting HDAC2

BACKGROUND

Smoke has been proved to be one of the most dangerous ingredients leading to the unsatisfying treatment response of asthmatics to inhaled corticosteroids (ICS) therapy. Macrolides, a class of antibiotics, possess the traits of immunomodulation and anti-inflammation besides antimicrobial activity. Given that studies on the efficacy of macrolides on the refractory asthma patient have diverting conclusions, this article was carried on to investigate the effects of macrolide on the airway inflammation of smoke-exposed asthmatic mice.

METHODS

BALB/c mice were chosen to be the subjects of this study. They were raised to establish asthma model (OVA group); and one asthma group were exposed to the smoke (SEA group), one asthma group were treat with clarithromycin (CAM group) after smoke exposure. Control group mice were used as parallel comparison. Total inspiratory resistance (RL), expiratory resistance of the lung (Re) and lung compliance (Cdyn) were the main index to evaluate airway hyperresponsiveness (AHR). The histopathological change was studied to assess lung tissue inflammation. Cell counts in bronchoalveolar lavage fluid (BALF) were also tested to represent airway inflammation. IL-4 and CXCL1 in BALF and serum were also used to evaluate the airway inflammation. Histone deacelytase2 (HDAC2) activity of lung tissues was measure by assay kit. HDAC2 expression in the lung tissue had been detected by western blot.

RESULTS

Re, RL and Cdyn were monitored to represent airway responsiveness. All of the three indicators in SEA group were significantly different from control group, while clarithromycin improved airway responsiveness and the three indicator were statistically significant (P<0.01). Histopathology observation had showed massive infiltration of inflammatory cells in both OVA group and SEA group, while inflammation infiltration attenuated in CAM group. Total cell counts in SEA group was much higher than that in CAM group (P=0.019), so were neutrophils (P=0.022) and eosinophils (P=0.042); while macrophages in SEA group decreased when compared to CAM group (P=0.026), IL-4 and CXCL1 level in CAM group were significantly decreased in comparison to those in SEA group (P=0.031, P=0.017). HDAC2 activity in SEA group decreased significantly when compared to control group (P=0.010); while HDAC2 activity in CAM group was improved and significantly better than that in SEA group (P=0.038). The expression of HADC2 in CAM group improved significantly when compared to that in SEA group (P=0.022).

CONCLUSIONS

Clarithromycin could improve AHR and attenuate airway inflammation in smoke exposed asthmatic mice which may involve HDAC2. Macrolides might have the potential to serve as the adjunctive treatment to some refractory asthmatics who are smokers or passive smokers.

Effects of zileuton on airway smooth muscle remodeling after repeated allergen challenge in brown Norway rats

BACKGROUND

Chronic asthma is characterized by airway inflammation and remodeling.

OBJECTIVE

This study aimed to evaluate the effects of zileuton on bronchial hyperresponsiveness, airway inflammation and airway smooth muscle (ASM) remodeling.

METHODS

Two experimental groups of brown Norway rats sensitized and repeatedly challenged with aerosolized ovalbumin (OA) were given oral zileuton (OA-zileuton group) and oral saline only (OA-saline group). A third, control group was sensitized and challenged by saline. The rats were anesthetized and paralyzed. Pulmonary function tests were performed at baseline and after varying doses of acetylcholine. Bronchoalveolar lavage fluid and lung tissues were examined.

RESULTS

Zileuton had beneficial effects on pulmonary function, airway inflammation and ASM remodeling in the OA-zileuton group compared to the OA-saline group. Zileuton inhibited an OA-stimulated increase in ASM by inhibiting hypertrophy, hyperplasia and increased extracellular matrix via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, thereby reducing cyclin D1 expression and attenuating bronchial hyperresponsiveness.

CONCLUSION

OA increases airway inflammation and ASM mass. Zileuton effectively prevents bronchial hyperresponsiveness, airway inflammation and ASM remodeling in sensitized rats through the PI3K/Akt pathway, which reduces cyclin D1 expression.

Azithromycin inhibits IL-5 production of T helper type 2 cells from asthmatic children

BACKGROUND

Childhood asthma is a type 2 helper T (Th2) cell-driven inflammatory airway disease characterized by recurrent episodes of airway obstruction. Azithromycin (AZM), a macrolide antibiotic exhibiting anti-inflammatory activity aside from its antibacterial effect, may prove beneficial for asthmatic children. This study aimed to determine the effect of AZM on Th2 cells from atopic asthmatic children and non-atopic controls.

METHODS

CD4+ cells were isolated from peripheral blood mononuclear cells of 9 patients with asthma and 9 non-atopic individuals. Cells were activated as Th0 and differentiated into Th2 cells. The effect of AZM on activated CD4+ cells was evaluated with respective cell proliferation and cytokine production.

RESULTS

Th0 and Th2 CD4+ T cells from atopic asthmatic children produced greater interleukin (IL)-5 (Th2 cytokine) but lower interferon (IFN)-γ (Th1 cytokine) compared to the non-atopic controls, respectively. AZM inhibited IL-5 production of Th0 and Th2 cells from atopic asthmatics in a dose-dependent fashion, without significantly affecting their IL-13 and IFN-γ production. A similar effect was observed in non-atopic controls except that AZM did inhibit IFN-γ production of their Th0 cells. AZM at a higher dose decreased cell viability by inhibiting CD4+ T cell proliferation and enhanced their apoptosis, an effect similarly observed in Th0 and Th2 cells, and did not differ between asthmatic children and controls.

CONCLUSION

Our finding that AZM preferentially downregulates IL-5 production suggests its therapeutic potentials in controlling childhood asthma.

Effects of erlotinib on pulmonary function and airway remodeling after sensitization and repeated allergen challenge in Brown-Norway rats

Erlotinib, an EGFR tyrosine kinase inhibitor, can inhibit the proliferation and survival of cancer cells. It has been widely used to treat non-small cell lung cancer. This study aimed to evaluate the effects of erlotinib on bronchial hyperresponsiveness, airway inflammation, and airway remodeling in sensitized, ovalbumin-challenged rats. Two experimental groups of Brown-Norway rats were sensitized and repeatedly challenged by breathing aerosolized ovalbumin. Since Day 1, one group was given oral erlotinib (OA-erlotinib group) while the other group was given only oral saline (OA-saline group). The control group was sensitized and challenged using saline. All were anesthetized and paralyzed, and pulmonary function tests conducted at baseline and after provocation with varying doses of acetylcholine. Lung tissues were examined for airway inflammation, airway remodeling, and Th2-related cytokine mRNA expression. Results showed that the OA-erlotinib group had better pulmonary function and less airway inflammation, Th2-related cytokines and their mRNA expression, and airway remodeling compared to the OA-saline group. In conclusion, erlotinib effectively prevents bronchial hyperreactivity, airway inflammation, Th2-related cytokine mRNA expression, and airway remodeling after sensitization and repeated allergen challenge in Brown-Norway rats.

Mechanisms of action and clinical application of macrolides as immunomodulatory medications

Macrolides have diverse biological activities and an ability to modulate inflammation and immunity in eukaryotes without affecting homeostatic immunity. These properties have led to their long-term use in treating neutrophil-dominated inflammation in diffuse panbronchiolitis, bronchiectasis, rhinosinusitis, and cystic fibrosis. These immunomodulatory activities appear to be polymodal, but evidence suggests that many of these effects are due to inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and nuclear factor kappa B (NF-kappaB) activation. Macrolides accumulate within cells, suggesting that they may associate with receptors or carriers responsible for the regulation of cell cycle and immunity. A concern is that long-term use of macrolides increases the emergence of antimicrobial resistance. Nonantimicrobial macrolides are now in development as potential immunomodulatory therapies.

Clarithromycin suppresses airway hyperresponsiveness and inflammation in mouse models of asthma

Macrolide antibiotics, a class of potent antimicrobials, also possess immunomodulatory/anti-inflammatory properties. These properties are considered fundamental for the efficacy of macrolide antibiotics in the treatment of diffuse panbronchiolitis and cystic fibrosis. In patients with asthma, macrolide antibiotics have been reported to reduce airway hyperresponsiveness and improve pulmonary function. However, their beneficial actions in asthmatics possibly could be attributed to antimicrobial activity against atypical pathogens (e.g. Chlamydia pneumoniae), corticosteroid-sparing effect (inhibition of exogenous corticosteroid metabolism), and/or their anti-inflammatory/immunomodulatory effects. In order to investigate whether efficacy of macrolide antibiotics in asthma results from their immunomodulatory/anti-inflammatory activity, the influence of clarithromycin pretreatment (2 h before challenge) was examined on ovalbumin-induced airway hyperresponsiveness and airway inflammation in the mouse. Clarithromycin treatment (200 mg/kg intraperitoneally) decreased IL-4, IL-5, IL-13, CXCL2 and CCL2 concentrations in bronchoalveolar lavage fluid and markedly reduced inflammatory cell accumulation in bronchoalveolar lavage fluid and into the lungs, as revealed by histopathological examination. Furthermore, clarithromycin-induced reduction in inflammation was accompanied by normalization of airway hyperresponsiveness. In summary, in ovalbumin-induced mouse models, clarithromycin efficiently inhibited two important pathological characteristics of asthma, airway hyperresponsiveness and inflammation. These data suggest that the efficacy of clarithromycin, as well as of other macrolide antibiotics, in asthmatic patients could be attributed to their anti-inflammatory/immunomodulatory properties, and not only to their antimicrobial activity or exogenous corticosteroid-sparing effects.