Background Exposures to environmental pollution and specific occupational hazards exacerbate pulmonary fibrosis which has a complex pathogenesis and lacks effective therapeutic drugs. The extract from Dracocephalum moldavica L. can alleviate pulmonary fibrosis through anti-inflammatory and anti-pyroptosis pathways, but its mechanism of prevention and treatment for pulmonary fibrosis remains unclear.

Objective To elucidate the targets and potential mechanism underlying the anti-pulmonary fibrosis efficacy of Dracocephalum moldavica L. extract by employing an amalgamation of network pharmacology and empirical verification.

Methods The chemical composition of the extract of Dracocephalum moldavica L. was retrieved with the help of China National Knowledge Infrastructure (CNKI) and Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP). The disease targets related to pulmonary fibrosis were inquired using Gene Cards and DisGeNET. A protein-protein interaction (PPI) was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) database and Cytoscape software. The predicted potential targets were analyzed by the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses through the Database for Annotation, Visualization and Integrated Discovery (DAVID) and validated by molecular docking. Thirty-two rats were randomly divided into a control group, a model group, a low-dose group of Dracocephalum moldavica L. extract (100 mg·kg⁻¹), and a high-dose group of Dracocephalum moldavica L. extract (400 mg·kg⁻¹), with eight rats in each group. A rat model of pulmonary fibrosis was constructed using bleomycin (5 mg·kg⁻¹) intratracheal instillation, and an equal volume of saline was instilled into the control group. After modelling, 400 and 100 mg·kg⁻¹ of Dracocephalum moldavica L. extract were given the high-dose and low-dose groups by gavage, and an equal volume of saline was given by gavage to the control group and the model group, once per day, for consecutive 28 d. The animals were then neutralized, and lung tissues were collected. Structural changes in rat lung tissue were evaluated by observing stained pathological sections. Western blot (WB) was used to detect fibrosis-related proteins type I collagen (Col-I), α-smooth muscle actin (α-SMA), phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT) in lung tissues. Real-time fluorescence quantitative PCR (RT-qPCR) was used to detect α-SMA and Col-I mRNA levels in lung tissue. Enzyme-linked immunosorbent assay (ELISA) was used to detect tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) in rats.

Results A total of 378 key chemical components of the Dracocephalum moldavica L. extract and 1611 lung fibrosis-related targets were identified. Among them, 574 potential targets of Dracocephalum moldavica L. extract acting on lung fibrosis were obtained. The key targets determined by Degree value were albumin (ALB), tumour necrosis factor (TNF), AKT1, etc. The results of KEGG analysis suggested that the potential targets of Dracocephalum moldavica L. extract against pulmonary fibrosis mainly involved the PI3K-AKT, HIF-1 signaling pathway, TNF signaling pathway, and MAPK signaling pathway. The molecular docking results showed that the binding energy between the active components (quercetin, apigenin, aesculetin, quercitrin) of Dracocephalum moldavica L. extract and the core targets of pulmonary fibrosis (TNF, IL-6, ALB, AKT1) were all <-29.288 kJ·mol⁻¹, indicating good binding ability. The animal validation results showed that compared with the control group, the rats in the model group had disrupted alveolar structure, obvious inflammatory cell infiltration, positive blue-striped collagen fibre deposition, and increased Col-I and α-SMA protein expression and transcription levels (P<0.001), p-PI3K and p-AKT expression levels (P<0.001), and levels of inflammatory factors TNF-α, IL-6, and IL-1β (P<0.001). Compared with the model group, the high- and low-dose groups of Dracocephalum moldavica L. extract alleviated the progression of pulmonary fibrosis, reduced inflammatory cell infiltration, and attenuated collagen fibre deposition in rats, with a decrease in the protein expression and transcription levels of Col-I and α-SMA (P<0.01), the expression levels of p-PI3K and p-AKT (P<0.001), and the levels of inflammatory factors IL-6 and TNF-α (P<0.05, P<0.001).

Conclusion Dracocephalum moldavica L. extract manifests anti-pulmonary fibrotic properties through the modulation of the PI3K-AKT signaling cascade and the suppression of inflammatory reactions.