Effect of erythromycin on the ultrastructure of human macrophages exposed to cigarette smoke extract in vitro.

Macrophages serve an active role in the pathophysiology of chronic obstructive pulmonary disease (COPD). Erythromycin (EM) has been verified as an effective treatment for COPD. However, there are few studies on the effect of EM on the ultrastructure of macrophages exposed to cigarette smoke extract (CSE). In the present study, human macrophages were randomly divided into three groups: The control, CSE and the CSE+EM group, using electron microscopy, the effect of EM was evaluated by comparing the ultrastructural changes between these groups. The macrophages were additionally divided into a further four groups: The control, CSE, CSE+EM 24 h and CSE+EM 48 h groups. The generation of reactive oxygen species (ROS) in each group was evaluated by detecting fluorescence intensity. It was observed that the cellular ultrastructure of the CSE group exhibited abnormal changes, though this effect was reversed back to the level of the control in the CSE+EM group. Compared with the control group, the ROS expression level was significantly increased in the CSE group (P < .05); however, compared with the CSE group, the ROS concentration was decreased in the CSE+EM 24 h (P < .05) and CSE+EM 48 h groups (P < .05), though this was more apparent in the EM 48 h group. It was concluded that EM protects human macrophages against CSE. Moreover, it was hypothesized that EM may reduce the symptoms of patients with COPD by protecting the macrophage ultrastructure from the effects of CSE, resulting in the decreased generation of ROS, inhibiting autophagy and reducing endoplasmic reticulum stress.

Erythromycin inhibits cigarette smoke-induced inflammation through regulating the PPARγ/NF-κB signaling pathway in macrophages.

Chronic obstructive pulmonary disease is characterized by chronic inflammation of the airway and lungs. Accumulating evidence has suggested that erythromycin (EM) plays a protective role against cigarette smoke-induced oxidative stress and the inflammatory response. However, the underlying mechanisms remain relatively unclear. The present study aimed to investigate the role of EM in inhibiting cigarette smoke-induced inflammation in human macrophages and its potential mechanism. A Cell Counting Kit-8 assay was used to determine the optimum concentration of EM and cigarette smoke extract (CSE) and it was found that 0.1 and 1% CSE and 0.1, 1.0 and 10 µg/ml EM exerted no significant effect on the cell proliferation activity, whereas 2 and 3% CSE exerted a significant inhibitory effect over the cell proliferation activity. We observed that 10 µmol/ml GW9662 (A PPARγ antagonist) and the presence of 1% CSE could promote the expression and activation of NF-κB p65. And this increased the expression of IL-6, IL-8 and reactive oxygen species (ROS). At the same time, 10 µmol/ml GW9662 and 1% CSE was found to inhibit the expression and activation of peroxisome proliferator activated receptors γ (PPARγ); However, 1 µg/ml EM was discovered to reverse these effects. Co-immunoprecipitation subsequently discovered an interaction between PPARγ and NF-κB p65. In conclusion, the present study suggested that EM may reduce the damage of PPARγ by inhibiting oxidative stress and reducing the expression of ROS and finally relieving cigarette smoke-induced inflammation through the PPARγ/NF-κB signaling pathway in macrophages.

Erythromycin Regulates Cigarette Smoke-Induced Proinflammatory Mediator Release Through Sirtuin 1-Nuclear Factor κB Axis in Macrophages and Mice Lungs.

BACKGROUND: Macrolides have anti-inflammatory and antioxidative stress function, but their pharmacological regulation remains unclear. Sirtuin 1 (SIRT1) is redox-sensitive protein belongs to class III histone/protein deacetylases, SIRT1 regulates the acetylation/expression of nuclear factor κB (NF-κB) and is involved in the airway inflammation of chronic obstructive pulmonary disease. OBJECTIVES: The present study was designed to examine the effects of erythromycin (EM) on the SIRT1-NF-κB axis and NF-κB-dependent proinflammatory cytokines. METHODS: Human macrophages were preincubated with EM and then treated with cigarette smoke extract (CSE). The mice were treated by injecting drugs to gastric with EM before cigarette smoke exposure. Reactive oxygen species (ROS) released by treated human macrophages were detected using flow cytometry. The expression of SIRT1 and NF-κB was analyzed by western blotting. SIRT1 and the RelA/p65 subunits of NF-κB interaction were detected by coimmunoprecipitation. We found that EM suppressed CSE-induced ROS released in human macrophages, which coincided with increases in SIRT1 protein expression in the macrophages and lungs of mice, resulting in suppressed -NF-κB acetylation and expression correlated with a reduction of inflammatory mediators. CONCLUSION: These findings suggest that EM increased SIRT1, leading to acetylation/expression of NF-κB, and thereby decreasing cigarette smoke-driven NF-κB-dependent proinflammatory cytokine.