Anus eczema-related genes, SDG target genes, and common targets
A total of 958 potential gene candidates were screened in Genecards and 634 in OMIM databases, while duplicates were excluded. To gain a comprehensive understanding of anal eczema-related genes, the findings from multiple databases were amalgamated, yielding a total of 958 distinct genes. Consequently, a protein-protein interaction network (PPI) specific to anal eczema was meticulously formulated. SDG is composed of five traditional Chinese medicines, namely indigo naturalis, golden cypress, calcined gypsum, calamine, and Chinese Gall15,16. The main component of calcined gypsum is anhydrous calcium sulfate (CaSO4), while the main component of calamine is zinc carbonate (ZnCO3). Indigo naturalis, golden cypress, and Chinese Gall have complex ingredients. From the TCMSP database, the drugs contain 92 compound components, obtaining a total of 867 reliable drug targets (Table 1).
Through the overlaying of both target gene datasets, a total of 149 frequently co-occurring target genes were pinpointed (Figure 2A), followed by the construction of an essential target protein-protein interaction (PPI) network (Figure 2B). Through a median-based screening method for degree, closeness, and betweenness, 59 key targets were selected as potential anal eczema drug targets. The median degree, closeness, and betweenness scores for the key targets were 49, 40.31947, and 0.522, respectively. The top 10 genes with a high degree score included AKT1, TNF, TP53, EGFR, STAT3, SRC, JUN, CASP3, HRAS, and PTGS2 (Table 2). These genes are highly relevant to anal eczema.
Pathways and networks involving common targets
KEGG and GO enrichment methods were utilized to analyze 59 key targets, revealing 218 associated pathways and over 3000 associated biological processes. Analysis uncovered pathways that strongly correlate with SDG and anal eczema proteins, including Cherry simplex virus 1 infection, Shigellosis, TNF signaling pathway, EGFR tyrosine kinase inhibitor resistance, Human cytomegalovirus infection, and T cell receptor signaling pathway (Figure 3A). These pathways primarily relate to genes such as AKT1, TNF, TP53, STAT3, SRC, EGFR, and CASP3. Figure 3B provides a detailed depiction of target genes and pathways. GO analysis was performed on biological processes (BP), cell composition (CC), and molecular function (MF) (Figure 4A). Results suggest that this study primarily focuses on common targets for SDG and anal eczema in biological processes, with a few relevant to CC and MF. Biological functions that were particularly relevant include peptidyl-tyrosine phosphorylation, peptidyl-tyrosine modification, regulation of cell-cell adhesion, positive regulation of cell adhesion, T cell activation, regulation of leukocyte cell-cell adhesion (Figure 4B-D).
Predicting the binding of SDG active components to anus eczema targets
Based on the median values of degree, closeness, and betweenness, 59 key targets were screened, including AKT1, TNF, TP53, EGFR, STAT3, SRC, JUN, CASP3, HRAS, and PTGS2. Further analysis of the GEO database revealed upregulation of PPARG, EGFR, and TNF, while PTPRC, MMP9, MAPK14, and CASP3 were downregulated in the experimental group (atopic dermatitis) (Figure 5). Through the analysis of common gene pathway enrichment, it was determined that these genes predominantly participated in the TNF signaling cascade and the MAPK signaling pathway. In the TNF signaling pathway, TNF expression was upregulated, while MMP9, MAPK14, and CASP3 expression were downregulated. In the MAPK signaling pathway, EGFR and TNF expression were upregulated, while MAPK14 and CASP3 were downregulated (Figure 6). Based on these findings, TNF, MAPK14, and CASP3 were considered as potential targets in SDG therapy.
To validate candidate targets in active components of SDG, docking analysis was used to test the accuracy between the active component structure and potential target proteins. These target proteins are involved in various functional connections and are the high nodes in the network, suggesting that they play a crucial role in the SDG response to anal eczema. The negative value of docking binding energy indicates the ability of SDG to dock with disease targets in vivo, with a more negative value indicating easier docking. In this investigation, the successful molecular docking of core active components with the key target was achieved, and the docking binding energy was negative, with values less than -1 kcal/mol. Indigo and berberrubine have good binding activity, with binding energy less than -5 kcal/mol (Table 3, Figure 7). Taken together, these results provide further evidence that these proteins corresponding to gene loci can act as SDG targets in anus eczema.

Figure 1: Network pharmacology analysis workflow. GO, Gene Ontology; KEGG,Kyoto Encyclopedia of Genes and Genomes; TCMSP, Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform; GEO, Gene Expression Omnibus. Please click here to view a larger version of this figure.

Figure 2: Venn diagram and PPI network of the common targets. (A) Venn diagram of intersection of drug target and disease target. (B) Common target PPI network by STRING. Please click here to view a larger version of this figure.

Figure 3: KEGG pathway enrichment analysis. (A) KEGG pathway enrichment analysis. The top 10 KEGG pathways are ranked according to the P-values in ascending order. (B) The connection between the pathway and the target: pathway (yellow), targets (red). Please click here to view a larger version of this figure.

Figure 4: GO enrichment analysis. (A) GO results of three ontology. (B) Biological process (BP) bubble chart. (C) Cell component (CC) bubble chart. (D) Molecular function (MF) bubble chart. Please click here to view a larger version of this figure.

Figure 5: Predicting potential targets result. (A) Heatmap of hub gene expression in GEO database, group A is the experimental group (atopic dermatitis), and group B is the control group (non-atopic dermatitis); (B) PPI network nodes represent proteins, edge represent the relationships. Please click here to view a larger version of this figure.

Figure 6: The signaling pathway. (A) MAPK signaling pathway. (B) TNF signaling pathway. Please click here to view a larger version of this figure.

Figure 7: Molecular docking of core genes and ingredients. Magenta represents the core components of SDG, and blue represents the residues of the core genes. Please click here to view a larger version of this figure.
| Traditional Chinese medicines | Active ingredients |
| Indigo naturalis | 9alpha,13alpha-dihydroxylisopropylidenylisatisine,a, bisindigotin, indicant, isatan B, isatisine,a, isoorientin, isoscoparin, isovitexin, (+)-isolariciresinol, 10h-indolo,[3,2-b],quinolone, Isoindigo, Saponarin, Indigo, tryptanthrin, 6-(3-oxoindolin-2-ylidene)indolo[2,1-b]quinazolin-12-one |
| Indirubin, beta-sitosterol, Lariciresinol, Nonacosane, isovitexin, Dotriacontanol |
| Golden cypress | berberine, coptisine, Dauricine (8CI), Javanicin, (±)-lyoniresinol, Kihadalactone A, Obacunoic acid, Obacunone, phellavin, Phellavin_qt, phellodendrine,delta 7-stigmastenol, Phellopterin, Vanilloloside, Coniferin, Dehydrotanshinone II A, delta7-Dehydrosophoramine, Amurensin, Amurensin_qt, dihydroniloticin, hispidol B, kihadalactone B, kihadanin A, niloticin, nomilin, rutaecarpine, Skimmianin, Chelerythrine, Stigmasterol, Worenine, Campesteryl ferulate, Cavidine, Candletoxin A, Hericenone H, Hispidone, Syrigin, beta-sitosterol, Magnograndiolide, (2S,3S)-3,5,7-trihydroxy-2-(4-hydroxyphenyl)chroman-4-one, Palmidin A, magnoflorine, Menisporphine, palmatine, Fumarine, Isocorypalmine, quercetin, Sitogluside, Friedelin |
| STOCK1N-14407, jatrorrizine, menisperine, phellamurin_qt, (S)-Canadine, columbamine, poriferast-5-en-3beta-ol, magnoflorine, berberrubine, phellodendrine, limonin, Hyperin, campesterol, SMR000232320, Canthin-6-one, 4-[(1R,3aS,4R,6aS)-4-(4-hydroxy-3,5-dimethoxyphenyl)-1,3,3a,4,6,6a-hexahydrofuro[4,3-c]furan-1-yl]-2,6-dimethoxyphenol, dihydroniloticin, melianone, phellochin, thalifendine, vanilloloside, Auraptene |
| Calcined gypsum | anhydrous calcium sulfate (CaSO4) |
| Calamine | zinc carbonate (ZnCO3) |
| Chinese Gall | digallate |
Table 1: Active ingredients in SDG.
| Gene | Degree | Betweenness Centrality | Closeness Centrality |
| AKT1 | 204 | 1669.1692 | 0.765625 |
| TNF | 202 | 1988.4543 | 0.761658 |
| TP53 | 190 | 1590.9288 | 0.73134327 |
| EGFR | 174 | 686.3063 | 0.7033493 |
| STAT3 | 168 | 673.03723 | 0.6869159 |
| SRC | 162 | 568.1574 | 0.69014084 |
| JUN | 162 | 435.33737 | 0.6805556 |
| CASP3 | 156 | 483.45276 | 0.67431194 |
| HRAS | 148 | 515.28815 | 0.65625 |
| PTGS2 | 134 | 761.34094 | 0.6447368 |
Table 2: Characteristics of the top 10 hub genes.
| Target (PDB ID) | Affinity (kcal/mol) |
| Indigo | Berberrubine | Digallate |
| TNF (1A8M) | -5.96 | -5.19 | -2.22 |
| MAPK14 (1A9U) | -5.51 | -5.41 | -1.93 |
| CASP3 (1CP3) | -5.77 | -4.98 | -1.06 |
Table 3: The molecular docking binding energy of the ingredients and core genes.