Identifying the mechanisms and molecular targets of Hongjingtian injection on treatment of TGFβ1-induced HK-2 cells: coupling network pharmacology with experimental verification

The study was designed to investigate the mechanism of Hongjingtian injection (HJT) in treating tubulointerstitial fibrosis (TIF) in chronic kidney diseases (CKD) based on network pharmacology and experimental verification.

This study comprehensively illuminated the active compounds, potential targets, and molecular mechanism of HJT against TIF. HJT treatment of TIF may reverse EMT caused by TGF-β1 by targeting SPHK1.

First, active ingredients of HJT obtained from literature were screened using the Traditional Chinese Medicine Systems Pharmacology (TCMSP) database and putative targets of active ingredients were predicted using the Chemmapper, SEA and Swiss Target Prediction database. Subsequently, the "compound-target" network for HJT was established. In addition, TIF disease targets were obtained from the GEO gene chips (accession number GSE20247). The intersecting targets of HJT and TIF obtained through Venny 2.1.0. The key targets and signaling pathways were determined by protein-protein interaction (PPI) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Finally, quantitative polymerase chain reaction (qPCR) and Western blot (WB) were used to validate the predicted five key genes targets (GAD1, SPHK1, P4HA2, AKR1B1, PTGES). And immunofluorescence, wound healing assay and transwell assay were used to verify the anti-fibrosis effect of HJT on TGFβ1-induced HK-2 cells.

The network pharmacology analysis results showed that there are 36 active compounds and 1,044 putative target genes in HJT. HJT may exert its inhibitory effects against TIF by acting on 79 key targets. Besides, KEGG analysis indicated that the anti-TIF effect of HJT was mediated by multiple pathways, such as the metabolic pathway, pathways in cancer and gap junction. Among them, GAD1, SPHK1, P4HA2, AKR1B1 and PTGES are enriched in the metabolic pathway. In vitro induced cell model experiments, the immunofluorescence experience showed that HJT could restore EMT of HK-2 cells. In addition, the qPCR and WB results showed that HJT significantly restored the expression of the SPHK1 in HK-2 cells induced by TGF-β1. Conclusions: This study comprehensively illuminated the active compounds, potential targets, and molecular mechanism of HJT against TIF. HJT treatment of TIF may reverse EMT caused by TGF-β1 by targeting SPHK1.