Fritillaria cirrhosa D. Don Alleviates Inflammatory Progression and Suppresses M1 Polarization of Macrophages in Chronic Obstructive Pulmonary Disease

Introduction: Chronic obstructive pulmonary disease (COPD) is a progressive and largely irreversible disease. Current therapeutic approaches for COPD are limited in terms of slowing disease progression and suppressing pulmonary inflammation. Therefore, this study aimed to identify a method for alleviating inflammation in COPD. Methods: A COPD-like mouse model was established and treated with or without Fritillaria cirrhosa D. Don (hereinafter referred to as Fritillaria). The expression levels of inflammatory cytokines in mouse serum were detected by using enzyme-linked immunosorbent assay (ELISA). Additionally, lung tissue was analyzed by hematoxylin-eosin staining and immunohistochemistry analysis, respectively. MLE-12 cells were exposed to cigarette smoke extract (CSE) and treated with or without Fritillaria. The MTT assay was conducted to assess cell viability. The activation of NF-κB p65 was determined by Western blotting (WB). Finally, flow cytometry was applied to analyze the M1 macrophage percentage. Results: The results displayed that Fritillaria downregulated the levels of IL-1β, IL-6, IL-8, and TNF-α in the COPD-like mouse serum and MLE-12 cells. Fritillaria alleviated the inflammatory response in lung tissue of COPD-like mice. The cell viability of MLE-12 cells considerably decreased when exposed to CSE, which could be restored by adding Fritillaria. The Fritillaria reduced the activation of the pro-inflammatory factor NF-κB p65 and inhibited M1 polarization of macrophages, thereby mitigating the inflammatory response. Conclusion: In conclusion, Fritillaria exhibits beneficial effects in suppressing pulmonary infection-related inflammation in both the COPD-like mouse model and in vitro cell experiments.