3.1 Identification of COVID-19/Stroke–associated genes
Figure 1 illustrates the workflow of this research.
To scrutinize the relationships and implications between COVID-19 and stroke, human RNA-seq and microarray datasets from the GEO were analyzed to identify genes that are disrupted in both conditions. A total of 3566 DEGs were obtained from the COVID-19 dataset, comprising 483 upregulated DEGs and 3,083 downregulated genes. Similarly, in the stroke blood dataset, a total of 511 DEGs were identified through differential expression analysis, with 267 genes exhibiting upregulation and 244 genes exhibiting downregulation.
The two volcano plots presented in Fig. 2 visually represent the comprehensive transcriptional gene expression patterns for COVID-19 and stroke. In these plots, red dots signify genes exhibiting upregulation, while blue dots indicate genes exhibiting downregulation with significant differences (Figs. 2A, 2B).(Lu et al., 2022)
Additionally, Fig. 2C illustrates 205 overlapping DEGs that were identified in both COVID-19 and stroke.
3.2 Functions and Pathways Enrichment Analyses
Utilizing the 205 overlapped DEGs, enrichment analyses were conducted to delve into their functional roles and associated pathways. The outcome revealed enrichment in 150 GO-BP, 26 GO-CC, 2 GO-MF, and 7 KEGG pathways. The top 10 results of biological processes as per BH adjusted P-value < 0.05 and 7 KEGG pathways were chosen for visualization in a scatter plot (Figs. 3A and 3B). Notably, the DEGs exhibited prominent enrichment in GO-BP terms related to the immune response to activating signal transduction and the immune response to activating cell surface receptor signaling pathways, among others. Additionally, KEGG pathways, encompassing Th17 cell differentiation and Th1 and Th2 cell differentiation, among others, were highlighted.
Consistent with these findings, enrichment analysis conducted through the Metascape database revealed significant enrichment in pathways related to inflammation, signaling, immune responses, and regulatory processes (Fig. 3C). Furthermore, the enrichment analysis demonstrated that overlapped DEGs were related to diseases associated with inflammation, vascular issues, and infections in DisGeNET (Fig. 3D). Transcription factor–target analysis demonstrated that numerous overlapped DEGs were regulated by TFs in the TRRUST database (Fig. 3E), highlighting that the TF regulatory network might participate in the progression of COVID-19 and stroke.
3.3 The TF Regulatory Network and Potential Drugs for COVID-19 and Stroke
To further unveil the TFs-target network in COVID-19 and stroke, 795 individual TFs and their corresponding target genes retrieved from the TRRUST database served as the foundational data. The criteria for selection involved identifying TFs present in COVID-19 and DEGs in stroke that coexist in COVID-19. Specifically, TFs in stroke DEGs and its downstream target gene in at least COVID-19 and one disease DEGs in stroke are key genes in COVID-19 and stroke.
Six hub TFs are determined in Figure 4A. The TF regulatory network in COVID-19 and stroke is depicted in Figure 4B and Table S1.
Subsequently, an analysis of potential drugs for treating both COVID-19 and stroke was undertaken. Utilizing the DGIbd database (https: //dgidb.org/), 64 drugs that could be used to treat both COVID-19 and stroke were identified. A comparison was made between 4130 COVID-19 drugs and 5892 stroke drugs obtained from the CTD database, and a Venn diagram analysis was performed. The results revealed 17 drugs predicted by the DGIbd database capable of treating both COVID-19 and stroke (Figure 5A). Finally, the relationship between these potential drugs and their respective targets was visualized using the R-language Sankeywheel package to create a Sankey diagram (Figure 5B)(Zhang et al., 2021).
Among these potential drugs, curcumin emerged as a promising candidate due to its ability to inhibit NF-κB and MAPKs and its recognized pharmacological impacts, comprising anti-inflammatory, anti-oxidant, anti-proliferation, and anti-angiogenesis properties. Curcumin was predicted as a candidate drug utilizing the CMap database (Table S2). Consequently, curcumin was selected for subsequent functional assay.
3.4 Identification of Curcumin Targets in COVID-19 and Stroke
Pharmacological targets of curcumin were downloaded from four public online databases: SEA, Swiss Target Prediction, TargetNet, and TCMSP. After identification, correction, and elimination of duplicate values through the UniProt database, 1890 pharmacological targets associated with curcumin were acquired. In the previous analysis, 29 common TF and its downstream target genes for COVID-19 and stroke were retrieved from the TRRUST database, and the above two groups of genes were assessed utilizing the Venn diagram. Ten overlapping genes were identified among the pharmacological targets of curcumin and the TFs-target genes shared by COVID-19 and stroke. These shared genes encompass ANPEP, MMP9, PTGS2, STAT3, XBP1, AURKA, CCNA2, JAK2, PPARG, PLK1, which are pharmacological targets of curcumin against both COVID-19 and stroke (Figure 6A).
Figure 6B shows the PPI network of the ten intersection targets assessed utilizing STRING. Subsequently, in Figures 6C and 6D, the six core gene targets identified by cytoHubba—namely, PTGS2, STAT3, CCNA2, JAK2, PPARG, and MMP9—are presented. Utilizing the MCC algorithm in cytoHubba, the top 6 nodes in terms of importance were summarized in Table 1.
Rank
|
Name
|
Score
|
1
|
STAT3
|
28
|
2
|
MMP9
|
26
|
2
|
PPARG
|
26
|
4
|
PTGS2
|
24
|
4
|
JAK2
|
24
|
6
|
CCNA2
|
4
|
Table 1 | Top 6 core target genes in the PPI network.
3.5 Development of network diagram
The GO enrichment analysis was executed utilizing the six curcumin anti-stroke and COVID-19 pharmacological targets. The top 20 pathways for BP, CC, and MF are illustrated in Figures 7A, 7B, and 7C, respectively. The outcomes highlight significant enrichment in pharmacological target genes of curcumin, particularly in essential biological processes such as smooth muscle cell proliferation, regulation of smooth muscle cell proliferation, and regulation of cysteine-type endopeptidase activity involved in the apoptotic signaling pathway, among others.
Moreover, KEGG enrichment analysis was conducted on these curcumin anti-stroke and COVID-19 pharmacological targets, followed by visualization analysis of the top 20 enrichment pathways (Figure 7D). The results indicated that the major enrichment pathways of curcumin anti-stroke and COVID-19 pharmacological target genes included Transcriptional misregulation in cancer, TNF signaling pathway, Toxoplasmosis, Th17 cell differentiation, etc.
Utilizing Cytoscape, a network visualization of curcumin against COVID-19/stroke targets and an interaction diagram for core target-related pathways (top 20 pathways) were generated (Figure 8).
3.6 Binding of curcumin to intersecting potential target genes in COVID-19 and Stroke
To gain deeper insights into the interaction of curcumin with pharmacological targets against COVID-19 and stroke, AutoDock Vina software was employed to analyze potential binding between the protein macromolecules of curcumin and the six core targets (CCNA2, JAK2, MMP9, PPARG, PTGS2, STAT3). The molecular docking scores were as follows: -2.86, -2.98, -5.01, -2.42, -3.83, -2.28. The evaluation of molecular docking was based on the principle of energy minimization, where a higher absolute value of the score indicates a better binding degree(Lu et al., 2022). Figure 9(A, B, C, D, E) illustrates the docking interactions of CCNA2, JAK2, MMP9, PPARG, PTGS2, and STAT3 with curcumin.