Inhalable ligustrazine powders relieve inflammation of COPD via regulation of neutrophil extracellular traps and gut-lung axis microbiota

Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways, lung parenchyma, and pulmonary vasculature. Recurrent exacerbations can lead to the development of pulmonary hypertension (PH) and cor pulmonale. Ligustrazine (LIG) is an active ingredient derived from Ligusticum chuanxiong hort. Due to the existence of long-term inflammatory response and limited drug treatments in COPD, a new pulmonary dry powder inhaler was designed to deliver ligustrazine (LIG) via a novel, biodegradable, cross-linked covalent cyclodextrin framework (OC-COF), ensuring effective LIG delivery to the deep alveolar region. Yet, the therapeutic effect of LIG@OC-COF in COPD is still unclear. Network pharmacology was used to screen the intersection targets among LIG, COPD, and PH. Molecular docking and molecular dynamics simulation (MD) were used to further predict interaction mode among LIG and intersection targets. Modelling methods with swimming, hypoxia, and smoking were applied to establish COPD rats. 16 S rRNA sequencing was used to evaluate the microbial changes in pulmonary and intestinal respectively, then explore the abundance of richness and diversity, and predict the function and enrichment pathway. Anti-inflammatory effect of LIG@OC-COF was demonstrated by western blotting, immunohistochemistry, ELISA and immunofluorescence. Meanwhile, correlation analysis among the lung function, inflammatory factors and microbiota were predicted the regulatory effect of LIG@OC-COF. C-C motif chemokine receptor 1 (CCR1) and myeloperoxidase (MPO) were screened as potential targets of LIG for treating COPD and PH. A good stable binding between LIG and MPO, CCR1 was verified through molecular docking, and MD. neutrophil extracellular traps (NETs) pathway was significant by KEGG. Expression of MPO and CitH3, biomarkers of NETs, and their related molecules CCR1, IFN-γ, TNF-α, IL-6, and IL-1β, were verified to increase in COPD rats. LIG@OC-COF down-regulated the expression of NETs pathway to relieve inflammation of COPD. Microbiota results indicated that LIG@OC-COF had potential therapeutic effects, including microbiota imbalance of richness and diversity, the disorder of amino acid metabolism and glycolysis, which related closely to lung function and inflammatory response. LIG@OC-COF, as a novel dry powder inhaler, can be used to ameliorate inflammation and balance the micro-environment of lung and gut in COPD. This study also enriches understanding of regulatory links between microbiota and inflammation in COPD.