Related Experiment Videos
Intervention by azithromycin on bleomycin-induced lung injury in rats and its mechanisms
1Department of Pulmonary Medicine, Peking University First Hospital, Beijing 100034, China.
Objective:
To study the role of Th1/Th2 balance in the pathogenesis of pulmonary fibrosis and to investigate the therapeutic mechanisms of azithromycin.
Methods:
Male wistar rats were randomly divided into three experimental groups: the bleomycin A(5) (BLM) group (BLM group), the azithromycin (AZI) group (AZI group) and the control group. Quantitative analysis of the histopathologic changes was performed by computer gray scan. The expression of IL-10 mRNA and IFN-gamma mRNA was examined by RNase protection assay (RPA).
Results:
(1) In the BLM group, up-regulation of IL-10 mRNA was stronger than that of IFN-gamma mRNA, resulting in the inversion of the IL-10/IFN-gamma mRNA ratio, a shift from the Th1-like response of IFN-gamma predominance in the control group to the Th2-like response of IL-10 predominance in the BLM group. (2) The oral administration of AZI inhibited the expression of IL-10 and IFN-gamma mRNA; reversed the Th2-like response in the BLM group to the Th1-like response on day 7; and decreased the exudation of inflammatory cells as well as the degree of fibrosis.
Conclusions:
(1) At the early stage of fibrosing alveolitis, Th2 domination and the lack of IFN-gamma in the presence of alveolar epithelial and basement membrane injury may promote the development of fibrosis. (2) Azithromycin can inhibit the expression of IL-10 and IFN-gamma, and reverse the Th2-like response in the BLM group to a Th1-like response, and as a result, decrease the inflammatory injury as well as the degree of BLM-induced lung injury in rats.
Insights
Pulmonary fibrosis involves a Th2 immune response. Azithromycin treatment reversed this Th2 dominance to a Th1 response, reducing lung injury and fibrosis in rats.
Area of Science:
- Immunology
- Pulmonary Medicine
- Pharmacology
Background:
- Pulmonary fibrosis is a debilitating lung disease characterized by progressive scarring.
- The balance between T-helper 1 (Th1) and T-helper 2 (Th2) immune responses plays a critical role in fibrosis pathogenesis.
- Understanding the specific immune mechanisms driving fibrosis is crucial for developing effective treatments.
Purpose of the Study:
- To elucidate the role of the Th1/Th2 balance in the development of pulmonary fibrosis.
- To investigate the therapeutic mechanisms of azithromycin in mitigating pulmonary fibrosis.
Main Methods:
- Male Wistar rats were allocated to bleomycin (BLM)-induced pulmonary fibrosis, azithromycin (AZI) treatment, or control groups.
- Histopathological changes were quantified using computer gray scan analysis.
- The expression levels of Interleukin-10 (IL-10) mRNA and Interferon-gamma (IFN-gamma) mRNA were assessed using RNase protection assay (RPA).
Main Results:
- In the BLM group, IL-10 mRNA upregulation exceeded IFN-gamma mRNA, indicating a shift from a Th1 to a Th2-dominant response.
- Azithromycin administration inhibited both IL-10 and IFN-gamma mRNA expression.
- AZI treatment reversed the Th2-like response to a Th1-like response by day 7 and reduced inflammatory cell exudation and fibrosis severity.
Conclusions:
- Th2 immune cell dominance, coupled with a lack of IFN-gamma, contributes to fibrosing alveolitis and promotes lung fibrosis.
- Azithromycin effectively modulates the Th1/Th2 balance by inhibiting IL-10 and IFN-gamma expression.
- Azithromycin treatment ameliorates bleomycin-induced lung injury in rats by shifting the immune response towards a Th1 profile and reducing inflammation and fibrosis.