Exploration of the mechanism of Traditional Chinese Medicine for anxiety and depression in patients with diarrheal irritable bowel syndrome based on network pharmacology and meta-analysis

Background The efficacy of Chinese herbal medicine (CHM) in managing irritable bowel syndrome with diarrhea (IBS-D) accompanied by anxiety and depression remains uncertain. Thus, a systematic review was carried out employing meta-analysis and network pharmacology to ascertain the efficacy and underlying mechanisms of CHM therapy. Methods By conducting a systematic review, including literature search, screening, and data extraction, we identified 25 randomized controlled trials to assess CHM’s effectiveness in treating irritable bowel syndrome alongside anxiety and depression. Network pharmacology was utilized to scrutinize the metabolite utility of CHM in addressing this condition. Potential primary mechanisms were synthesized using information sourced from the PubMed database. Results Twenty-five studies, including 2055 patients, were analyzed, revealing significant treatment efficacy for IBS-D in the trial group compared to controls [OR = 4.01, 95% CI (2.99, 5.36), I2 = 0%] Additionally, treatment for depression [SMD = −1.08, 95% CI (-1.30, −0.86), p < 0.00001, I2 = 68%; SDS: SMD = -1.69, 95% CI (-2.48, −0.90), p < 0.0001, I2 = 96%] and anxiety [HAMA: SMD = -1.29, 95% CI (-1.68, −0.91), p < 0.00001, I2 = 89%; SAS: SMD = -1.75, 95% CI (-2.55, −0.95), p < 0.00001, I2 = 96%] significantly improved in the trial group. Furthermore, the trial group exhibited a significantly lower disease relapse rate [OR = 0.30, 95% CI (0.20, 0.44), p < 0.00001, I2 = 0%]. CHM treatment consistently improved IBS severity (IBS-SSS) and symptom scores. Network pharmacology analysis identified key chemical metabolites in traditional Chinese medicine formulations, including Beta-sitosterol, Stigmasterol, Quercetin, Naringenin, Luteolin, Kaempferol, Nobiletin, Wogonin, Formononetin, and Isorhamnetin. Utilizing the STRING database and Cytoscape v3.9.0 software, a protein-protein interaction (PPI) network revealed the top eight key targets: IL-6, TNF, PPARG, PTGS2, ESR1, NOS3, MAPK8, and AKT1, implicated in anti-inflammatory responses, antioxidant stress modulation, and neurotransmitter homeostasis maintenance. Conclusion Chinese Herbal Medicine (CHM) offers a promising and safe treatment approach for patients dealing with Diarrheal Irritable Bowel Syndrome (IBS-D) accompanied by anxiety and depression; thus, indicating its potential for practical implementation. The most active metabolites of CHM could simultaneously act on the pathological targets of IBS-D, anxiety, and depression.The diverse scope of CHM’s therapeutic role includes various aspects and objectives, underscoring its potential for broad utilization.


Introduction
Abdominal pain or discomfort and alterations in defecation patterns are prevalent symptoms of Irritable Bowel Syndrome (IBS), a common functional gastrointestinal disorder.IBS can be categorized into diarrhea-type, constipation-type, mixed-type, and indeterminate-type based on abnormal defecation patterns (Drossman, 2016).Its etiology is complex, involving visceral hypersensitivity, abnormal gastrointestinal motility, and psychological stress (Ford et al., 2017).Many individuals with IBS-D often encounter psychological symptoms alongside gastrointestinal ones.Growing evidence highlights the strong link between IBS-D and anxiety as well as depression (Chen et al., 2022).The prevalence of anxiety symptoms among IBS patients is estimated at 1.28%, while that of depression symptoms is 8.11% (Zamani et al., 2019).Notably, individuals with IBS-D are three times more likely to experience anxiety or depression compared to healthy individuals (Kurokawa et al., 2018).Anxiety and depressive symptoms may exacerbate gastrointestinal and extragastrointestinal symptoms by altering visceral hypersensitivity and the intestinal microenvironment, influencing the microbiotaintestinal-brain axis (Moloney et al., 2016;Ford et al., 2017).Moreover, psychological factors have the potential to disrupt intestinal mucosal integrity, modify gut microbiota composition, impair mucosal barrier function, and modulate immune responses.Taken together, these factors play a collective role in the manifestation of symptoms such as diarrhea in individuals with IBS-D, thereby complicating the management of IBS-D patients.Currently, Western medicine lacks specific medication for treating (HAMD) or Self-rating Depression Scale (SDS), as well as the Hamilton Anxiety Scale (HAMA) or Self-rating Anxiety Scale (SAS).5) Efficacy indicators included ① Severity of irritable bowel syndrome (IBS-SSS) score, ② TCM symptom score, ③ Clinical efficacy, ④ Recurrence rate, ⑤ Adverse effects.

Study exclusion criteria
1) Non-clinical investigations, case reports, non-randomized controlled trials, and reviews; 2) patients with unclear diagnostic criteria and methods for assessing effectiveness; 3) investigations where the comparison group received CHM treatment; 4) investigations lacking data on reliable endpoint indicators or having inadequately designed experimental protocols; and 5) interventions incorporating additional traditional Chinese medicine physical therapies (e.g., acupuncture, massage, music, etc.).

Literature review and data extraction
Two researchers independently evaluated the gathered literature according to predefined inclusion and exclusion criteria.Information was collected from the selected studies, including the primary author's name, publication year, sample size, age distribution, gender composition, treatment protocol, treatment duration, form and metabolites of herbal dosage, as well as outcome measures.

Quality assessment
The evaluation of bias risk utilized the bias risk assessment tool suggested in the Cochrane 5.1.0manual for randomized controlled trials, as outlined by (Cumpston et al., 2019).This assessment included six key aspects: random allocation sequence, concealed allocation scheme, blinding, incomplete outcome data, selective outcome reporting, and "other issues" for methodological quality appraisal.Two researchers performed quality assessment independently, crosschecking each other's evaluations.Any discrepancies were resolved through consultation with a third researcher.

Data analysis and synthesis
The meta-analysis, conducted using Cochrane Collaboration's RevMan 5.3 software, involved separate entry of outcome indicators for data processing and analysis.Odds ratio (OR) and standard mean difference (SMD) were utilized to evaluate combined effects for dichotomous outcomes and continuous variables, respectively.Heterogeneity was assessed using the chi-squared test, with I 2 indicating the degree of heterogeneity.For studies with low heterogeneity (I 2 < 50%), a fixed-effects model was employed; whereas for those with significant heterogeneity (I 2 ≥ 50%), subgroup analyses were conducted to explore potential sources.If heterogeneity persisted, a random-effects model was applied for effect size combination, with subgroup analysis based on TCM evidence type, interventions, and intervention time.Publication bias was examined using a funnel plot subsequent to presenting results via a forest plot in the meta-analysis.A significance level of p < 0.05 was used to determine statistical significance.

Metabolites of Chinese medicines and their mechanisms of action
The compositions of the formulations and patented drugs are detailed in Supplementary Table S2.The frequency analysis of each CHM is shown in Supplementary Table S3.Network pharmacology analysis was performed on CHMs with a frequency of at least five to identify the main active metabolites and disease targets.

Target identification of Chinese herbal metabolites
Active metabolites from Chinese herbal medicine were gathered using the Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) analysis platform, adhering to criteria of oral bioavailability (OB) > 30% and drug-likeness (DL) ≥ 0.18.Subsequently, the corresponding targets of these active metabolites were assembled and refined utilizing UniProt data, excluding non-human genes and redundant or ineffective targets.

Identification of disease-related targets
Keyword searches for "irritable bowel syndrome," "depression," and "anxiety" were performed using the GeneCards database and DisGeNET to retrieve pertinent targets linked with these conditions.Next, all identified targets from these databases were consolidated in Excel, eliminating duplicate genes.The gathered information was then cross-referenced and refined utilizing the UniProt database to ensure accurate gene information for disease targets.

Drug-disease target prediction
The acquired targets of drug metabolites were mapped against disease targets, and then a Venn diagram was generated to obtain the intersecting genes.These intersection targets were inputted into Cytoscape software (version 3.9.0) to construct the herb-metabolite-target network.Additionally, the primary potential mechanisms of action of the top 10 main agents were summarized from the PubMed database.

Constructing a CHM-disease target proteinprotein interaction network
The TCM-disease targets were inputted into the STRING online software, with Homo sapiens selected as the species for filtering conditions.This process facilitated the construction of a proteinprotein interaction network (PPI network) for drug-disease interactions.A minimum interaction score of 0.4 was set.The degree of each node in the network indicates the protein's significance in interactions, with a higher number of connections reflecting greater importance within the PPI network.

Literature search results
A total of 1,475 relevant original studies were retrieved from eight databases, including the China National Knowledge Internet (150), VIP (225), Wan Fang (269), SinoMed (757), PubMed (1 study), Web of Science ( 16), Cochrane Library (43), and Embase (14).A total of 549 duplicates were eliminated.After excluding 843 articles by screening the title and abstract, 83 articles remained for full-text analysis.In total, 58 papers were rejected, and 25 items were included in this study (Figure 1).

Study characteristics and quality
The selected RCTs included 2055 people, 1,028 of whom were in the trial groups and 1,027 of whom were in the control groups.The baseline information for the trial and control groups was similar.The treatment course in all studies varied from 2 weeks to 3 months.The main characteristics of the included studies are summarized in Table 1.

Meta-analysis of Chinese medicine for the treatment of diarrheal irritable bowel syndrome patients with anxiety and depression
In the majority of studies, significant improvements were observed in HAMA, HAMD, SDS, SAS, IBS-SSS, and TCM symptom scores within the trial group.Consequently, the primary outcome indicators were consolidated to elucidate the efficacy of CHM in treating IBS-D with anxiety and depression.

Clinical effectiveness
There is a pressing need for more standardized efficacy assessment criteria in treating IBS-D.The included studies conducted this investigation to establish their judgment criteria for determining treatment effectiveness.They categorized effective indicators such as cure, apparent effect, and effectiveness, while ineffective indicators were classified accordingly.A total of 21 studies (Fu and Xu, 2013;Zhu, 2013;Nie et al., 2014;Zhu et al., 2015;Zhang, 2016;Guo, 2019;Majing, 2019;Wu, 2019;Cai et al., 2020;Liu, 2020;Sun et al., 2020;Zhou and Chu, 2020;Feng, 2021;He et al., 2021;Li, 2021;Lu and Wang, 2021;Liu, 2022;Su and Zhang, 2022;Gu and Xu, 2022;Zhang et al., 2023;Chen et al., 2024) reported clinical effectiveness rates.The heterogeneity test results (p = 1.00,I 2 = 0%) indicated no statistical heterogeneity among the studies; thus, a fixed-effects model was utilized for the combined analysis.The difference was statistically significant in the test of combined statistics (Z = 9.32, p < 0.00001, OR = 4.01, 95% CI [2.99,5.36],I 2 = 0%), suggesting that the trial group exhibited a higher total effective rate of clinical improvement in IBS-D compared to the control group.These results are illustrated in Figure 2.

FIGURE 3
Forest plot comparing the HAMD scores of the trial group and the control group after treatment.
Frontiers in Pharmacology frontiersin.org07 Bai et al. 10.3389/fphar.2024.1404738indicated that HAMD scores of the trial group were lower than those of the control group (SMD = -1.08,95% CI [-1.30, −0.86], p < 0.00001).Subgroup analyses were carried out to investigate the source of heterogeneity based on intervention time, TCM syndrome of included patients, and interventions (Supplementary Table S4).S4; Figure 3.

HAMA score
Fifteen studies (Fu and Xu, 2013;Zhu, 2013;Guo, 2019;Majing, 2019;Wu, 2019;Cai et al., 2020;Liu, 2020;Feng, 2021;He et al., 2021;Li, 2021;Yang, 2021;Liu, 2022;Su and Zhang, 2022;Zhang, 2023;Chen et al., 2024) reported HAMA scores of IBS-D patients treated with CHM.Initially, a heterogeneity test was conducted, revealing significant heterogeneity among the studies (p < 0.00001, I 2 = 89%).Therefore, a random-effects model was employed for the combined analysis.The difference was statistically significant in the combined statistic test (Z = 6.60, p < 0.00001).Subgroup analyses of intervention time, TCM syndrome of included patients, and interventions were conducted to explore the source of heterogeneity, but none of them were found to be significant sources (Supplementary Table S5).A sensitivity analysis was performed to investigate the source of heterogeneity further, and excluding individual studies did not reduce heterogeneity.Metaanalysis results indicated that the HAMA scores of the trial group were lower than those of the control group (SMD = -1.29,95% CI [-1.68, −0.91], p < 0.00001).This suggests that CHM treatment significantly reduced HAMA scores in the trial group compared with the control group, with a statistically significant difference.The results are presented in Supplementary Table S5; Figure 4.

SAS score
Ten studies (Nie et al., 2014;Zhu et al., 2015;Zhang, 2016;Xu, 2017;Sun et al., 2020;Zhou and Chu, 2020;Ding et al., 2021;Lu and Wang, 2021;Mou, 2021;Gu and Xu, 2022) reported SAS scores of IBS-D patients treated with CHM.Initially, a heterogeneity test was conducted, revealing significant statistical heterogeneity among the studies (p < 0.00001, I 2 = 96%).Therefore, a random-effects model was applied for the combined analysis, with the combined statistic test yielding a statistically significant difference (Z = 4.28, p < Forest plot comparing HAMA scores of the trial group and the control group after treatment.0.0001).Subgroup analyses of intervention time, evidence type of the included patients, and intervention were conducted to explore the source of heterogeneity, but none of them were found to be significant sources (Supplementary Table S7).A sensitivity analysis was performed to investigate the source of heterogeneity further, but no reduction in heterogeneity was observed after individual studies were excluded.Meta-analysis results indicated that the SAS scores of the trial group were lower than those of the control group (SMD = -1.75,95% CI [-2.55, −0.95], p < 0.00001).This suggests that CHM treatment exhibited significant advantages in reducing SAS scores in the trial group compared with the control group, with a statistically significant difference.The results are presented in Supplementary Table S7; Figure 6.

IBS-SSS irritable bowel syndrome severity scale
Eleven studies (Fu and Xu, 2013;Xu, 2017;Guo, 2019;Wu, 2019;Liu, 2020;Ding et al., 2021;He et al., 2021;Yang, 2021;Liu, 2022;Su and Zhang, 2022;Chen et al., 2024) reported the IBS-SSS score of IBS-D patients treated with CHM.Initially, a heterogeneity test was conducted, revealing significant statistical heterogeneity among the studies (p < 0.00001, I 2 = 82%).Therefore, a random-effects model was employed for the combined analysis, with the combined statistic test showing a statistically significant difference (Z = 6.70, p < 0.00001).Subgroup analyses of intervention time, evidence type of the included patients, and intervention were conducted to explore the source of heterogeneity, but none of them were identified as significant sources (Supplementary Table S8).Sensitivity analysis was performed to investigate the source of heterogeneity further, but heterogeneity could not be reduced after individual studies were excluded one by one.Meta-analysis results indicated that IBS-SSS scores of the trial group were lower than those of the control group (SMD = -1.24,95% CI [-1.60, −0.88], p < 0.00001), suggesting that CHM treatment had a significant advantage in reducing IBS-SSS scores in the trial group compared with the control group, with a statistically significant difference.The results are presented in Supplementary Table S8; Figure 7.

Total clinical symptom scores in Chinese medicine for irritable bowel syndrome (IBS-D)
Seventeen studies (Nie et al., 2014;Xu, 2017;Guo, 2019;Majing, 2019;Wu, 2019;Liu, 2020;Zhou and Chu, 2020;Ding et al., 2021;Feng, 2021;He et al., 2021;Li, 2021;Mou, 2021;Gu and Xu, 2022;Liu, 2022;Su and Zhang, 2022;Zhang, 2023;Chen FIGURE 5 Forest plot comparing the SDS scores of the trial group and the control group after treatment.Forest plot comparing SAS scores of the trial group and the control group after treatment. et al., 2024) reported the TCM symptom scores of IBS-D patients treated with CHM.Due to scoring bias across different studies, significant heterogeneity was observed in the TCM symptom scores.The results of the heterogeneity test (p < 0.00001, I 2 = 95%) indicated statistically significant heterogeneity among the studies.Therefore, a random-effects model was utilized for the merged analysis, with the combined statistic test showing a statistically significant difference (Z = 6.38, p < 0.00001).Subgroup analyses of intervention time, evidence type of included patients, and intervention were conducted to explore the source of heterogeneity, but none of them were identified as significant sources (Supplementary Table S9).Sensitivity analysis was employed to further investigate the source of heterogeneity, but heterogeneity could not be reduced after excluding individual studies one by one.Meta-analysis results revealed that TCM symptom scores in the trial group were lower than those in the control group (SMD = -1.90,95% CI [-2.48, −1.31], p < 0.00001), indicating that treatment in the trial group had a significant advantage in reducing TCM symptom scores compared with the control group, with a statistically significant difference.The results are presented in Supplementary Table S9; Figure 8.

Recurrence rate
Ten studies (Fu and Xu, 2013;Guo, 2019;Majing, 2019;Wu, 2019;Sun et al., 2020;Zhou and Chu, 2020;Ding et al., 2021;Feng, 2021;Li, 2021;Gu and Xu, 2022) reported recurrence rates, and the heterogeneity test results (p = 0.64, I 2 = 0%), which indicated no statistical heterogeneity among the studies, were combined and analyzed using a fixed-effects model.The results showed that the difference between the trial group and the control group was statistically significant and that CHM treatment could significantly reduce the recurrence rate of IBS-D (Z = 6.11, p < 0.00001, OR = 0.30, 95% CI [0.20, 0.44], I² = 0%).The results are shown in Figure 9. Forest plot comparing the IBS-SSS scores of the trial group and the control group after treatment.

Publication bias
Publication bias was assessed by generating a funnel plot with OR values on the horizontal axis and the standard error (SE) of LogOR on the vertical axis for the primary outcome indicator of this study, which is clinical effectiveness.The funnel plot revealed some asymmetry between the left and right sides, suggesting the presence of publication bias that could influence the combined effect size to some degree.This bias may be attributed to factors such as inconsistent study evaluation, low quality, and small sample size.The results are depicted in Figure 10.

Active metabolites and treatment targets of CHM
Given the predominance of literature indicating the effectiveness of CHM in treating IBS-D, statistical analysis was conducted to ascertain the frequency of CHM usage and identify commonly employed medications across various groups.CHM metabolites with a frequency of occurrence equal to or greater than five were selected as the primary active metabolites (Supplementary Table S3).The results revealed that Atractylodes macrocephala Koidz., [Asteraceae; Atractylodis macrocephalae rhizoma], Paeonia lactiflora Pall., [Paeoniaceae; Paeoniae radix alba], Citrus × aurantium L., [Rutaceae; Citri reticulatae pericarpium], Glycyrrhiza uralensis Fisch.ex DC., [Fabaceae; Glycyrrhizae radix et rhizoma praeparata cum Forest plot comparing the recurrence rates of the trial group and the control group after treatment.

Disease targets and CHM targets.
Utilizing the GeneCards and DisGeNet disease databases, we conducted a screening for target information associated with IBS-D, anxiety, and depression.The target information from these different diseases was intersected.Subsequently, intersection processing was carried out between the target genes corresponding to the ultimately obtained effective active metabolites of CHM and the disease targets.Consequently, 115 common genes were identified as crucial targets for Traditional Chinese Medicine in treating IBS-D along with anxiety and depression.

Key target protein interaction network
We utilized a combined_score threshold of 0.4 in the String database to generate a network diagram of target interactions.Following this, the genes underwent network topology analysis using Cytoscape 3.9.0.According to the topological analysis, genes such as IL-6, TNF, PPARG, PTGS2, ESR1, NOS3, MAPK8, and AKT1 are identified as potential targets for CHM in the treatment of IBS-D along with anxiety and depression.

Mechanism of activity
The actions and mechanisms of the top 10 major active metabolites, as presented in Table 3, were investigated by searching the PubMed database.

Study of potential mechanisms
The PubMed database was queried to elucidate the mechanism of action of the primary active metabolites (top 10).As indicated in Table 3, beta-sitosterol, quercetin, and luteolin were investigated in studies related to IBS-D, anxiety, and depression.Additionally, studies focusing on anxiety and depression have explored stigmasterol, naringenin, nobiletin, wogonin, and kaempferol.Commonly utilized animal models for IBS-D include the maternally separated (MS) IBS-D rat model, the 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced postinflammatory IBS-D rat model, and models induced by water avoidance stress (WAS).Furthermore, animal models commonly used for depression and anxiety include multiple-stress mice, LPS/CORT mice, and Danio rerio models.
Table 3 illustrates the mechanisms attributed to these ten active metabolites concerning IBS-D, anxiety, and depression.These metabolites effectively address visceral sensitivity, normalize gastrointestinal dynamics, diminish inflammatory responses, and regulate mood.They exhibit anti-inflammatory and antioxidative stress effects while maintaining neurotransmitter balance.IBS-D is currently associated with various mechanisms like gut microbiota, visceral hypersensitivity, low-grade inflammation, and brain-gut axis interactions.Beta-sitosterol, quercetin, and luteolin alleviate intestinal symptoms by targeting visceral hypersensitivity, gastrointestinal infections, inflammation, and psychosocial aspects.They regulate sensory nerve pathways and neurotransmitter signaling, reducing gastrointestinal discomfort such as abdominal pain.Additionally, their anti-inflammatory properties alleviate chronic gastrointestinal inflammation, easing symptoms like diarrhea and rectal bleeding.Moreover, these metabolites modulate neuroendocrine and neuroimmune pathways linked to stress response, anxiety, and depression, thereby improving psychosocial wellbeing and gastrointestinal health overall.
With the exception of stigmasterol, wogonin, and formononetin, the other active metabolites exhibit potent anti-inflammatory and antioxidant properties.These metabolites inhibit the release of inflammatory mediators, diminish inflammatory cell activity, and improve immune system function.They play a crucial role in mitigating oxidative stress, a contributing factor to various diseases.Kaempferol, abundant in plant-based foods, demonstrates robust anti-inflammatory effects by inhibiting proinflammatory cytokines and scavenging free radicals, thereby safeguarding against tissue damage induced by oxidative stress.Naringenin scavenges free radicals and reactive oxygen species, shielding cells from oxidative harm and modulating inflammatory signaling pathways.Isorhamnetin suppresses NF-κB activation and dampens inflammatory gene expression while possessing antioxidant properties that protect against cellular damage induced by oxidative stress, particularly in

Discussion
There is increasing evidence indicating a high prevalence of depression and anxiety among patients with IBS-D.Current medical approaches for treating IBS-D include pharmacological symptomatic treatments, dietary adjustments, and psychotherapies.Chinese medicine has emerged as a significant modality in managing IBS-D with comorbid anxiety and depression, offering enhanced efficacy and fewer side effects compared to conventional treatments.Several clinical studies have highlighted its precise efficacy and safety.However, further validation of CHM's effectiveness in treating IBS-D with anxiety and depression is needed, particularly due to concerns regarding methodological quality.
This study conducted a comprehensive review of domestic and international research on treating IBS-D with depression and anxiety using CHM.The analysis included 25 studies, comprising 22 CHM metabolite prescriptions and involving 2055 patients.The findings revealed that the CHM-based trial group exhibited superior efficacy compared to the control group (p < 0.05).Additionally, the trial group showed significant improvements in depression scale scores (HAMD and SDS) and anxiety scale scores (HAMA and SAS) compared to the control group (p < 0.05), indicating the potential of CHM treatment to ameliorate mood disorders in IBS-D patients.Moreover, CHM treatment demonstrated advantages in alleviating clinical gastrointestinal discomfort, accompanying symptoms (evaluated by IBS-SSS and total TCM symptom scores), and improving patients' quality of life (p < 0.05).The recurrence rates in the trial group were lower (14.52%)compared to the control group (33.03%), suggesting a reduced recurrence risk of irritable bowel syndrome with depression and anxiety following CHM intervention.In conclusion, CHM exhibits clinical effectiveness in managing IBS-D with depression and anxiety without increasing the risk of adverse effects.
The gastrointestinal tract operates under a complex network involving central, autonomic, and enteric nervous systems, making it susceptible to influences from adverse emotions and psychological factors (Aburto and Cryan, 2024).This disruption in the brain-gut axis can lead to gastrointestinal dysfunction due to imbalances between the hypothalamus and limbic system, as well as reduced vagal nerve excitability.The mechanism of TCM in the management of IBS-D involves various aspects.Firstly, Chinese herbs alleviate patients' symptoms by regulating intestinal function, modulating intestinal motility and peristalsis, possibly affecting the smooth muscle of the intestines to promote the normalization of peristalsis.Secondly, TCM can rebalance the yin and yang imbalance in the body by regulating the neuroendocrine system.Through the microbiota-intestinal-brain axis, CHM can ameliorate patients' abdominal discomfort and psychological symptoms.Additionally, certain CHM enhance the function of the digestive system, promoting the absorption of nutrients, thereby alleviating symptoms in patients with IBS-D.Finally, several herbal medicines possess anti-inflammatory and antioxidant properties, aiding in reducing inflammation reactions in the intestinal mucosa, improving the intestinal environment, and thereby alleviating symptoms.CHM offers a promising approach to managing IBS-D alongside depression and anxiety by employing a multifaceted, multitarget strategy.To investigate the utilization of CHM further, this study analyzed commonly used herbal medications using network pharmacology.The findings revealed several frequently used herbs, including A. macrocephala Koidz.,These herbs contain active metabolites that, according to network pharmacology, can concurrently target disease-related pathways associated with IBS-D, anxiety, and depression.Notable among these active metabolites are beta-sitosterol, stigmasterol, quercetin, naringenin, luteolin, kaempferol, nobiletin, wogonin, formononetin, and isorhamnetin.These metabolites exhibit potential therapeutic effects on the interconnected targets of IBS-D, anxiety, and depression, underscoring the holistic approach of CHM in addressing these complex conditions.
Herbal metabolites like beta-sitosterol, quercetin, and luteolin are pivotal in addressing the intricate relationship between IBS-D and concurrent depression and anxiety.On the other hand, stigmasterol, naringenin, kaempferol, nobiletin, and wogonin target depression and anxiety symptoms.Additionally, formononetin and isorhamnetin play essential roles in treating depression.Beta-sitosterol, a phytosterol, exhibits antiinflammatory and immunomodulatory effects.Quercetin, known for its anti-inflammatory, antioxidant, and anticancer properties, positively influences immune function by activating AMP-activated protein kinase (AMPK) (Chiang et al., 2023).Luteolin regulates the Nrf2 signaling pathway, protecting against excessive intestinal motility and diarrhea (Xia et al., 2024).Naringenin enhances cell survival by reducing apoptosis rates induced by CORT (Zhang et al., 2023).Stigmasterol demonstrates anti-inflammatory, antioxidant, and neuroprotective characteristics, potentially alleviating depression and anxiety symptoms by maintaining neurotransmitter balance.Kaempferol exhibits anti-ulcerative colitis effects, suggesting promising therapeutic mechanisms (Qu et al., 2021).Nobiletin inhibits pro-inflammatory cytokines and enzymes like COX-2 and iNOS, scavenges free radicals, and reduces oxidative stress.Wogonin suppresses NF-κB activation and the production of inflammatory mediators such as TNF-α and IL-6.Formononetin displays antioxidant effects by mitigating neuronal damage and promoting neurogenesis (Zhang et al., 2022).Isorhamnetin possesses antioxidant, anti-inflammatory, and neuroprotective attributes, hindering the production of inflammatory cytokines and mediators, reducing oxidative stress, and enhancing neuronal survival and synaptic plasticity.Inflammation significantly contributes to the pathophysiology of IBS-D and its associated psychiatric comorbidities, exacerbating symptoms and fostering mood disorders like depression and anxiety.The bidirectional communication of the gut-brain axis is pivotal, wherein gut-derived inflammatory signals influence central nervous system function and mood regulation.CHM metabolites exhibit anti-inflammatory and neurological protection effects by modulating signaling molecules and oxidative stress, alongside antioxidant properties by neutralizing free radicals and curtailing cellular damage in order to improve diarrhea, abdominal discomfort, and mood in patients.
Based on the intersection of metabolite-disease targets, these CHM can target multiple receptors, including PPARG, PTGS2, ESR1, NOS3, MAPK8,1L-6, TNF, and AKT1, to elicit synergistic treatment of diseases effects.PPARG, expressed in various tissues, regulates lipid catabolism and exhibits anti-inflammatory effects when activated, potentially ameliorating colitis symptoms.PTGS2, encoding a crucial cellular protein, modulates anti-inflammatory responses and immune regulation; thus, impacting mood regulation.AKT1, a ubiquitous intracellular kinase, regulates cell metabolism, survival, and proliferation.Phosphorylated AKT1 can activate NLRP3 inflammatory vesicles, contributing to inflammation in colitis-related diseases (Guo et al., 2014).TNF enhances chemokine and cytokine production, amplifying the inflammatory cascade and organ damage, while IL-6, a key cytokine in inflammation induction and maintenance, may contribute to systemic inflammatory responses and mood dysregulation (Ridker, 2016).ESR1, functioning as a transcription factor, regulates gene expression, affecting processes like cell proliferation, differentiation, and apoptosis.NO, a signaling molecule involved in neurotransmission and immune response, plays a crucial role in inflammation, with NOS3-derived NO potentially impacting mood regulation through its involvement in inflammatory processes.MAPK8 responds to various extracellular stimuli, including stress and cytokines, regulating gene expression implicated in inflammation and neuronal plasticity, thereby modulating depression and anxiety.
In summary, the effectiveness of CHM in treating IBS-D patients with anxiety and depression is evident.Importantly, CHM appears to exert multi-metabolite and multi-targeted effects on signaling pathways involved in various aspects of the biology of IBS-D patients with anxiety and depression, including anti-injury/apoptosis, antiinflammation, antioxidative stress, and neurotransmitter homeostasis maintenance.CHM may ameliorate symptoms of IBS-D that cooccur with anxiety and depression by addressing different facets of the condition.

Limitations
Firstly, the quality of the included studies was subpar, characterized by low methodological quality.Most studies lacked details on allocation concealment and blinding, and some exhibited selective reporting bias.In future clinical trials, we aim to adhere to the international CONSORT standards to ensure robust study design and reporting.Secondly, many of the included studies had small sample sizes, diminishing the statistical power of our analysis.Moreover, the absence of rigorous sample size estimation in these studies undermines the validity of the findings.Additionally, variations in conventional interventions introduced clinical heterogeneity, such as differing choices of conventional Western medicine, varying intervention durations, and diverse criteria for evaluating efficacy.Subgroup analyses to identify factors influencing heterogeneity were inadequate.Future research endeavors should prioritize rigorous, multicenter, large-sample size randomized controlled trials to furnish high-quality evidence for clinical practice.

Conclusion
CHM demonstrates efficacy in ameliorating symptoms associated with irritable bowel syndrome (IBS-D) in individuals suffering from anxiety and depression.The principal mechanisms underlying the actions of these herbal active metabolites likely involve anti-inflammatory and antioxidative stress effects, along with the regulation of neurotransmitter homeostasis and modulation of autophagy.

FIGURE 1 PRISMA
FIGURE 1 PRISMA flow diagram and risk-of-bias assessment; (A) literature screening process; (B) risk-of-bias summary.

FIGURE 8
FIGURE 8Forest plot comparing TCM symptom scores of the trial group and the control group after treatment.

FIGURE 10 Funnel
FIGURE 10Funnel plot of publication bias in clinical treatment effectiveness rates.

TABLE 1
Basic characteristics of included articles.

TABLE 1 (
Continued) Basic characteristics of included articles.

TABLE 2
Occurrence of adverse effects.

TABLE 3
Actions and mechanisms of the top 10 major active metabolites.

TABLE 3 (
Continued) Actions and mechanisms of the top 10 major active metabolites.