Morus alba L.-Glycyrrhiza uralensis alleviate chronic obstructive pulmonary disease by inhibiting the arachidonic acid metabolism pathway.

ETHNOPHARMACOLOGICAL RELEVANCE

The compatibility of natural herbs has been gradually recognized for its efficacy and safety in treating lung diseases. Morus alba L. root bark (MRB) and Glycyrrhiza uralensis (Licorice) are traditional Chinese medicines (TCM) with a long history of use. They are often combined to treat chronic obstructive pulmonary disease (COPD). However, the optimal ratio for combining MRB and licorice and the underlying mechanism of this combination in the treatment of COPD need to be further clarified.

AIM OF THE STUDY

To determine the optimal compatibility dose relationship of MRB-Licorice in the current prescriptions and investigate its potential mechanism in the treatment of COPD.

MATERIALS AND METHODS

We collected the published clinical intervention literature and TCM prescription databases related to COPD treatment. R software (3.3.1) was used to analyze the frequency of medicine use, properties, combination methods, and to explore the core drug combinations in COPD treatment. A rat model of COPD was established through smoke inhalation and airway Lipopolysaccharide (LPS) instillation to evaluate the compatible dosage and effectiveness of the MRB-Licorice combination. Respiratory function, pathological morphology of lung tissue, and the expression of inflammatory factor were observed in rats to assess the effect of core combination of drugs in treating COPD. Subsequently, network pharmacology was constructed to predict the targets of core drugs for COPD treatment. Liquid chromatography-mass spectrometry was used to study plasma metabolomics and explore the regulatory effect of the core Chinese medicines on metabolites. A joint analysis of predicted targets and differential metabolites was conducted using MetaboAnalyst to identify critical metabolites and metabolic pathways. Additionally, intersection genes from human and rat Gene Expression Omnibus (GEO) datasets were analyzed. Finally, ELISA validation was conducted on key metabolic enzymes and genes.

RESULTS

MRB-Licorice exhibit the core Chinese herbal medicine compatibility for COPD treatment. MRB-Licorice improved respiratory function and lung histopathology, and reduced the expression of IL-1β, TNF-α, and MUC5AC proteins in COPD rats. Furthermore, significant differences were observed across different dosages, with the MRB-Licorice 2:1 group showing better therapeutic effects on COPD rats. In network pharmacology, 80 compounds from MRB-Licorice modulated 112 targets and acted by regulating pathways like glutathione metabolism and arachidonic acid (AA) metabolism. Metabolomics analysis showed that MRB-Licorice regulated 13 differential metabolites, and accordingly, regulated pathways, such as AA metabolism and arginine biosynthesis. Co-analysis of the 112 targets and 13 metabolites revealed that leukotriene B4 (LTB4) was the key differential metabolite, and AA metabolism was the key metabolic pathway. Arachidonic acid 5-lipoxygenase (ALOX5) and leukotriene A4 hydrolase (LTA4H) were identified as key genes through a joint analysis of the intersection genes from human and rat GEO datasets, key metabolic pathway genes, and core drug genes. Based on these results, we further verified MRB-Licorice reduced the levels of ALOX5, LTA4H, and LTB4 in the plasma of COPD rats.

CONCLUSION

The MRB-Licorice 2:1 treatment was more effective in alleviating inflammation and mucus secretion in COPD rats, probably via the regulation of AA metabolism.