Introduction
Ulcerative Colitis (UC) is a nonspecific gastrointestinal inflammatory disease characterized by diarrhea, mucus, and blood in the stool [
1]. Its pathogenesis is complex, and studies have shown that the disease is closely related to genetics, environmental factors, intestinal flora imbalance [
2], immune disorders, and other factors [
3]. At present, the incidence and prevalence of UC are increasing due to the irregularity of people’s diet and work and rest time. It is showing an increasing trend year by year, with an average of 1.2–20.3 and 7.6–24.5 cases per 100,000 people per year [
4,
5]. The pathogenesis of UC is not clear, so far there is no targeted radical cure measures. Therefore, it is of certain significance to carry out research on the treatment of UC and related diseases.
Traditional Chinese herbal medicine has been widely used to treat UC for many years [
6]. Wumei Pill is originated from Treatise on Cold Damage and Miscellaneous Diseases (200–210, AD), consisting of 10 herbs (as shown in Table
1) [
7]. Wumei pill effectively relieve typical symptoms of UC, such as abdominal pain, diarrhea and loss of appetite [
8‐
10]. Fructus Mume and Rhizoma Coptidis (FM-RC) as the main percent herb of Wumei Pill, their compatibility is commonly used in dysentery, diarrhea, intestinal adenoma and its carcinogenesis. Its mechanism of action may be related to the inhibition of inflammation and epithelial-mesenchymal transition [
11,
12]. Previous studies have shown that the main components of FM are organic acids, flavonoids and fatty acids, and the main active ingredient is citric acid [
13], the main components of RC include alkaloids, lignans, flavonoids, etc., and alkaloids are the main pharmacological components, berberine is the most abundant and representative compound [
14]. Jiang et al. [
15] showed that the compatibility of the herbal pair of FM-RC could alter the internal proportion of intestinal flora, promote the regulation of intestinal system balance, which played an important role in the treatment of UC. In addition, more and more studies have shown that FM not only has anti-tumor, antibacterial and anti-inflammatory effects, but also significantly improved weight loss and intestinal bleeding caused by UC, and inhibited expression of inflammatory factors such as TNF-α and IL-1β in the colon tissue of UC rats [
16]. Li et al. [
17] systematically evaluated the efficacy and safety of RC intervention in patients with UC to further guide its promotion and application. However, there is a lack of further research on the mechanism of FM-RC for the treatment of UC.
Table 1
The Composition of Wumei Pill
Fructus Mume | Wumei | Prunus mume Sieb.et Zuce | 24 |
Rhizoma coptidis | Huanglian | Coptis chinensis Franch | 24 |
Rhizoma Zingiberis | Ganjiang | Zingiber officinale Rosc | 15 |
Rhizoma Radix Asari | Xixin | Asarum heterotropoides Fr. Schmidt | 9 |
Radix Aconiti Lateralis Praeparata | Fuzi | Typhonium giganteum Engl | 9 |
Ramulus Cinnamomi | Guizhi | Cinnamomum cassia Presl | 9 |
Radix Ginseng | Renshen | Panax ginseng C. A. Meyer | 9 |
Cortex Phellodender | Huangbai | Phellodendron chinense Schneid | 9 |
Radix Angelicae Sinen sis | Danggui | Angelica sinensis (Oliv.) Diels | 6 |
Pericarpium Zanthoxyli | Huajiao | Zanthoxylum bungeanum Maxim | 6 |
Network pharmacology and molecular docking are new technologies based on systems biology and databased molecular correlation analysis in the exploration of new drugs and prediction of drug targets [
18,
19]. Zhou et al. [
20] combined the results of network pharmacology, molecular docking, and experimental verification indicated that FM promoted colorectal cell apoptosis and inhibited the development of colorectal cancer (CRC) mainly by inhibiting the expression of RelA. An et al. [
21] with the help of a network pharmacology strategy, molecular docking and experimental validation, investigated that RC could be used to treat Type 2 Diabetes Mellitus (T2DM).To broaden the mechanism of FM-RC in the treatment of UC, using a system-integrated method to study the treatment of UC by FM-RC from the perspective of system level [
22,
23].
Therefore, the aim of our study is to further consider the detailed mechanism of FM-RC herb pair in the treatment of UC systematically through network pharmacology, molecular docking and experimental validation in vivo, thereby providing new theoretical basis for Chinese medicine in the treatment of UC.
Discussion
In the present study, a protective effect of FM-RC on the intestine was investigated in a model of DSS-induced colitis. Our data showed that FM-RC administration attenuated DSS-induced body weight loss, diarrhea, and colon shortening in rats. Further analysis demonstrated that DSS administration led to an increase in the concentrations of TNF-α, IL-8, and IL-17 concentrations in serum and colon tissues, as well as reduced protein levels of IL-4 in serum and colon tissues of rats. Notably, DSS-induced colonic damage, as indicated by histological alterations, was greatly attenuated by FM-RC administration. These beneficial effects of FM-RC were associated with quercetin and MAPK1 signaling.
From the TCMSP database, Swiss, and other databases, a total of 18 potential active ingredients of FM-RC, 110 common targets in the herb pair and UC were identified. Subsequently, we further screened essential genes and core-dependent pathways through the PPI network. The Database for Annotation, Visualization and Integrated Discovery (DAVID,
https://david.ncifcrf.gov/) provides systematic, comprehensive biological annotation information for large-scale genes or proteins, and provides the most significantly enriched biological annotations. The DAVID web server was adopted to conduct GO enrichment analysis for the candidate target protein obtained after network merging. Subsequently, KEGG pathway enrichment analysis was conducted to explore biological pathways where relevant proteins were covered. A
P value ≤ 0.05 was considered signifcant, and enriched GO terms were identifed by the hypergeometric test. A bubble plot of bioprocess and pathways were drawn by bioinformatics data analysis (
www.bioinformatics.com.cn). Ultimately, the three bioactive compounds (quercetin, kaempferol, and palmidin A) and genes (SRC, MAPK1, and PIK3CA) with the highest differential expression within the constraints and the apoptosis-associated pathway were identified. Quercetin is a flavonoid molecule [
32]. Ye et al. [
33] studied the mechanism of quercetin in the treatment of Rheumatoid Arthritis (RA) and confirmed that quercetin exerted various biological activities such as inhibition of inflammatory cytokines, antioxidants, and immune regulation.Kaempferol is a polyphenol antioxidant [
34]. Rajendran et al. [
35] studied the mechanism of kaempferol in the prevention of CRC, indicating that kaempferol can reduce the expression of the CRC inhibitor DACT2 gene by regulating DNMT and HDAC proteins, and can also inhibit the migration of metastatic tumors. SRC is a non-receptor tyrosine protein kinase. The increased activity of SRC kinase not only reduces the adhesion between tumor cells but also increases the permeability of endothelial cells, thereby promoting the metastasis of tumor cells [
36,
37]. Therefore, regulating the activity of SRC kinase plays a key role in the occurrence and development of UC. MAPK1, or mitogen-activated protein kinase 1, is involved in various pathophysiological processes such as gene transcription, apoptosis, cell growth, and immune response. When external factors cause activation of MAPK protein, NF-kB is activated by MAPK phosphorylation with specific substrates and translocated into the nucleus, where transcriptases initiate gene expression programs that regulate the production of inflammatory factors such as TNF-α, IL-8, and IL-17, exacerbating the inflammatory response [
38‐
40]. PIK3CA regulates cell proliferation, differentiation, apoptosis, and other functions by activating the PI3K-AKT-mTOR pathway. When this gene was mutated, the PI3K-AKT-mTOR pathway could be abnormally activated, leading to the occurrence of colorectal cancer [
41]. We then performed molecular fitting scoring and molecular docking for the top three genes and bioactive components. The results indicated that quercetin and MAPK1 were bioactive compounds and genes, respectively, with the best affinity and reasonable degree in FM-RC for the treatment of UC.
Accumulating evidence has shown that overactivation of the inflammatory response contributes to the initiation and development of IBD or DSS-induced colitis. TNF-α, IL-8, and IL-17 are considered key pro-inflammatory cytokines that lead to the development of UC [
42,
43]. TNF-α is a monokine produced by monocytes and macrophages, which can promote the occurrence of an inflammatory response [
44]. IL-8 is an inflammatory cytokine promoted by TNF-α and participates in the intestinal inflammatory response by chemotaxis of basophils and T cells and promote neutrophil adhesion and activation [
45]. IL-17 is mainly secreted by T helper 17 cells, which not only induce endothelial cells and epithelial cells to analyze inflammatory factors such as IL-8 but also increase intestinal mucosa permeability and recruit neutrophils to induce inflammation of the intestinal mucosa of UC [
46]. Conversely, IL-4 is an important anti-inflammatory cytokine with multiple functions [
47], which can effectively inhibit the synthesis and antigen presentation of pro-inflammatory cytokines, thus reducing the inflammatory response, leading to the appearance of UC.
In this study, we combined the results of network pharmacology, molecular docking, and experimental in animal models at three levels. Among the bioactive ingredients associated with UC in FM-RC, quercetin and MAPK showed the highest degree of molecular docking. We also verified the effects of inflammatory factors associated with the MAPK pathway on the animal model of UC.
However, this study also presented some limitations. First, the data on various drugs, genes, and proteins were not comprehensive, and appropriate computing software has not been developed. Second, the bioactive ingredients of FM-RC should be verified individually by experiments. Finally, it is necessary to explore the direct regulation of bioactive ingredients on MAPK1 in future studies.
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