Active Components and Potential Targets of HDW. A total of 142 related components of HDW was retrieved from TCMSP and the published literature. According to pharmacokinetic characteristics (OB ≥ 30% and DL ≥ 0.18) and ADME information, 11 active components were selected from 142 ingredients of HDW. The TCMSP and Swiss Target Prediction databases were used to determine the pharmacological targets of the HDW components. Table 1 shows active components and the number of the corresponding potential targets of HDW. Detailed information of these components and targets is listed in Supplementary Table 1. Eventually, 180 potential targets were identified (after removing duplicates) using the Uniprot database.
Table 1. Active components and numbers of corresponding potential HDW targets.
PubChem CID
|
active components
|
Target number
|
5281330
|
poriferasterol
|
2
|
10514946
|
2-methoxy-3-methyl-9,10-anthraquinone
|
31
|
5280794
|
stigmasterol
|
31
|
222284
|
β-sitosterol
|
38
|
5280343
|
quercetin
|
154
|
5280863
|
kaempferol
|
17
|
5280460
|
scopoletin
|
3
|
637542
|
p-coumaric acid
|
13
|
72
|
3, 4-dihydroxybenzoic acid
|
8
|
445858
|
ferulic acid
|
8
|
135
|
p-hydroxybenzoic acid
|
12
|
Identification of the Potential Targets of RA. Using“Rheumatoid Arthritis” as the search term, 42, 192, 141, 174, and 623 disease-targets were obtained from the OMIM, DrugBank, TTD, GeneCards, and DisGeNET databases, respectively. Merging all results from the five databases and removing duplicates, 942 related-RA potential targets were finally collected.
Construction of the Active Components -Common Targets-RA Network. Applying a Venn diagram, 85 common targets were found overlapped between HDW compound targets and RA-related targets (Figure 2A). We imported 11 active components and 85 common targets into Cytoscape 3.9.0 software to construct a components-targets-RA network. Among these, the active ingredients with the highest degree value were stigmasterol, β-sitosterol, quercetin, kaempferol and 2-methoxy-3-methyl-9,10-anthraquinone. However, poriferasterol and scopoletin were removed since they lacked common targets in the network. The active ingredients-targets-RA network is shown in Figure 2B. Results indicate that 5 components may provide the key to successful treatment of RA.
GO and KEGG Enrichment Analysis. In total, GO analysis identified 1,542 significantly enriched GO terms (P.adjusted < 0.01 adjusted with Benjamini-Hochberg), consisting mainly of 1,459 biological processes, 18 cellular components, and 65 molecular functions. We screened the top 10 ranked GO terms shown in Figure 3A. In the biological process (GO: BP) category, the top terms were involved in responses to lipopolysaccharides, molecules of bacterial origin, and reactive oxygen species metabolic processes. In the cellular component (GO:CC) category, the top terms included membrane rafts, membrane microdomains, and membrane regions. In the molecular function (GO:MF) category, the top terms consisted of nuclear receptor activity, transcription factor activity, and cytokine receptor binding. To further identify underlying signaling pathways, we analyzed KEGG pathways. The top 20 significantly enriched pathways (P.adjusted value < 0.01) are shown in Figure 3B. A list of genes contributing to the 20 selected pathways is provided in Supplementary Table 2. Numerous targets were found associated with the AGE-RAGE, TNF, IL17, and PI3K-Akt signaling pathways, all of which are associated with the prognosis and onset of RA.
Network Visualization and Identification of Hub targets. Next, we analyzed 85 potential therapeutic targets by using the STRING database to obtain a PPI network to explore the relationship between RA-related targets. The PPI relationship network, with a total of 85 nodes, 238 edges and an average node degree of 5.6 was generated with a confidence of 0.9 (Supplementary Figure 1). PPI network diagrams were imported into Cytoscape 3.9.0 software for visualization (Figure 4A). We further identified the subnetwork and hub targets from the PPI network using the CytoNCA plug-in (Figure 4B) . As shown in Figure 4C, a subnetwork was identified, including 8 nodes and 27 edges. Moreover, RELA, TNF, IL6, TP53, MAPK1, AKT1, IL10, and ESR1 were identified as the hub targets in the HDW for RA treatment (Supplementary Table 3).
Validation of the Expression of the Hub Targets. To further validate the expression of 8 hub genes in RA, 3 gene expression microarray data sets were downloaded from the GEO database. Based on these, we obtained a normalized expression of hub genes in synovial cells, CD4+T cells and macrophages, as shown in Figure 5. Of the targets, RELA, TNF, IL6, MAPK1, and IL10 were significantly associated with key cells of RA pathogenic mechanism (FLS, CD4+T cells, and macrophages). To further analyze the functions of hub targets in RA in different cell types, we determined the expression of 8 hub targets in the HPA database (Figures 6 and Supplementary Figure 2). The results indicated that TNF and IL10 had high immune cell specificity, while IL6 was specifically expressed in fibroblast-like synoviocytes.
Molecular Docking. Candidate compounds stigmasterol, β-sitosterol, quercetin and kaempferol, and 2-methoxy-3-methyl-9,10-anthraquinone, are the top 5 (ranked by degree) in the compounds-targets-RA network. The hub targets, RELA, TNF, IL6, TP53, MAPK1, AKT1, IL10, and ESR1, play a significant role in the action of HDW against RA. Molecular docking of the 5 compounds and 8 hub genes revealed binding energies shown in Figure 7. Five components of HDW exhibited strong binding to the 8 core targets with β-sitosterol showing the highest binding energy. these results imply that treatment with HDW may affect all the Figure targets in RA patients. The target proteins and the small molecules with strong binding affinity were visualized by PyMoL software (Figure 8).