Low-Dose Azithromycin Attenuates OVA-Induced Airway Remodeling and Inflammation via Down-Regulating TGF-βl Expression in RAT

Effect of azithromycin on bronchial wall thickness in severe persistent asthma: A double-blind placebo-controlled randomized clinical trial

BACKGROUND

Azithromycin reduced airway remodeling in animal models of asthma. However, its effect on human subjects has not been studied yet. This study aimed to investigate the effect of long-term treatment with azithromycin on airways wall thickness in patients with severe persistent asthma.

METHODS

In this randomized, double-blind, placebo-controlled clinical trial, patients with severe persistent asthma received azithromycin (250 mg, BID, three days a week), prednisolone (5 mg, BID), or placebo for eight months in three separate groups in addition to the standard therapy. The improvement in right upper lobe apical segmental bronchus (RB1) wall thickness obtained by high resolution computed tomography was set as the primary outcome. Secondary outcomes included: cough severity, dyspnea severity, asthma control test (ACT) score, asthma exacerbation rate, pulmonary function tests, and fractional exhaled nitric oxide (FENO).

RESULTS

Seventy-eight out of ninety randomized subjects completed eight months of treatment with azithromycin (n = 25), prednisolone (n = 27), or placebo (n = 26). Bronchial wall thickness percentage did not change significantly in any of the groups. However, the inner radius and lumen area of azithromycin and prednisolone-treated subjects increased significantly (p < 0.05 for both). Azithromycin also significantly improved the dyspnea severity, ACT score, FENO, and FEV1, FEF_25-75, and FEV1/FVC (p < 0.05 for all). Cough severity or asthma exacerbation rate did not change significantly after eight months of treatment with azithromycin.

CONCLUSION

Long-term treatment with azithromycin increased lumen radius and lumen area in patients with severe persistent asthma. However, there was no significant change in wall thickness in any of the treatment groups.

TRIAL REGISTRATION

IRCT.com (IRCT20091111002695N8).

Azithromycin ameliorates airway remodeling via inhibiting airway epithelium apoptosis

AIMS

Azithromycin can benefit treating allergic airway inflammation and remodeling. In the present study, we hypothesized that azithromycin alleviated airway epithelium injury through inhibiting airway epithelium apoptosis via down regulation of caspase-3 and Bax/Bcl2 ratio in vivo and in vitro.

MAIN METHODS

Ovalbumin induced rat asthma model and TGF-β1-induced BEAS-2B cell apoptosis model were established, respectively. In vivo experiments, airway epithelium was stained with hematoxylin and eosin (HE) and periodic acid-Schiff (PAS) to histologically evaluate the airway inflammation and remodeling. Airway epithelium apoptotic index (AI) was further analyzed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), while expression of apoptosis related gene (Bax, Bcl2, Caspase-3) in lungs were measured by qRT-PCR and western blotting, respectively. In vitro experiments, apoptosis were evaluated by Flow cytometry (FCM) and TUNEL. Above apoptosis related gene were also measured by qRT-PCR and western blotting.

KEY FINDINGS

Compared with the OVA group, azithromycin significantly reduced the inflammation score, peribronchial smooth muscle layer thickness, epithelial thickening and goblet cell metaplasia (P<0.05), and effectively suppressed AI of airway epithelium (P<0.05). Moreover, the increasing mRNA and protein expressions of Caspase-3 and Bax/Bcl-2 ratio in lung tissue were all significantly decreased in azithromycin-treated rats (P<0.05). In vitro, azithromycin significantly suppressed TGF-β1-induced BEAS-2B cells apoptosis (P<0.05) and reversed TGF-β1 elevated Caspase-3 mRNA level and Bax/Bcl-2 ratio (P<0.05).

SIGNIFICANCE

Azithromycin is an attractive treatment option for reducing airway epithelial cell apoptosis by improving the imbalance of Bax/Bcl-2 ratio and inhibiting Caspase-3 level in airway epithelium.