The top 20 KEGG pathway.

Background
Pulmonary fibrosis (PF) is a common interstitial pneumonia disease, also occurred in post-COVID-19 survivors. The mechanism underlying the anti-PF effect of Qing Fei Hua Xian Decotion (QFHXD), a traditional Chinese medicine formula applied for treating PF in COVID-19 survivors, is unclear. This study aimed to uncover the mechanisms related to the anti-PF effect of QFHXD through analysis of network pharmacology and experimental verification.
Methods
The candidate chemical compounds of QFHXD and its putative targets for treating PF were achieved from public databases, thereby we established the corresponding “herb-compound-target” network of QFHXD. The protein–protein interaction network of potential targets was also constructed to screen the core targets. Furthermore, Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to predict targets, and pathways, then validated by in vivo experiments.
Results
A total of 188 active compounds in QFHXD and 50 target genes were identified from databases. The key therapeutic targets of QFHXD, such as PI3K/Akt, IL-6, TNF, IL-1β, STAT3, MMP-9, and TGF-β1 were identified by KEGG and GO analysis. Anti-PF effects of QFHXD (in a dose-dependent manner) and prednisone were confirmed by HE, Masson staining, and Sirius red staining as well as in vivo Micro-CT and immunohistochemical analysis in a rat model of bleomycin-induced PF. Besides, QFXHD remarkably inhibits the activity of PI3K/Akt/NF-κB and TGF-β1/Smad2/3.
Conclusions
QFXHD significantly attenuated bleomycin-induced PF via inhibiting inflammation and epithelial-mesenchymal transition. PI3K/Akt/NF-κB and TGF-β1/Smad2/3 pathways might be the potential therapeutic effects of QFHXD for treating PF.

背景
肺纤维化（Pulmonary Fibrosis, PF）是一类常见的间质性肺炎，亦可发生于新冠病毒感染后康复者群体中。清肺化纤汤（Qing Fei Hua Xian Decotion, QFHXD）是用于治疗新冠感染后幸存者肺纤维化的中药复方，但其抗肺纤维化作用的潜在分子机制尚未阐明。本研究旨在通过网络药理学分析与实验验证，揭示清肺化纤汤发挥抗肺纤维化作用的相关机制。

方法
从公共数据库中获取清肺化纤汤的候选化学成分及其治疗肺纤维化的潜在靶点，进而构建该方剂对应的“药材-化合物-靶点”调控网络。同时构建潜在靶点的蛋白质相互作用网络，以筛选核心靶点。此外，通过基因本体（Gene Ontology, GO）富集分析及京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路富集分析对靶点及通路进行预测，并通过体内实验完成验证。

结果
从数据库中共筛选得到清肺化纤汤的188个活性成分及50个靶点基因。通过KEGG及GO分析，鉴定出清肺化纤汤的关键治疗靶点，包括PI3K/Akt、IL-6、TNF、IL-1β、STAT3、MMP-9及TGF-β1。在博莱霉素诱导的肺纤维化大鼠模型中，通过苏木精-伊红（HE）染色、Masson染色、天狼星红染色、体内Micro-CT检测及免疫组化分析，证实清肺化纤汤可呈剂量依赖性发挥抗肺纤维化作用，泼尼松亦展现出明确的抗肺纤维化效果。此外，清肺化纤汤可显著抑制PI3K/Akt/NF-κB及TGF-β1/Smad2/3通路的活性。

结论
清肺化纤汤可通过抑制炎症反应与上皮间质转化，显著减轻博莱霉素诱导的肺纤维化。PI3K/Akt/NF-κB及TGF-β1/Smad2/3通路可能是清肺化纤汤治疗肺纤维化的潜在作用靶点与通路。