Role of gut microbiota-derived signals in the regulation of gastrointestinal motility

Efficacy of a postbiotic and its components in promoting colonic transit and alleviating chronic constipation in humans and mice

This study evaluates the efficacy of the postbiotic Probio-Eco in alleviating constipation in humans and mice. A randomized, double-blind, placebo-controlled crossover trial involving 110 adults with chronic constipation (Rome IV criteria) demonstrates that a 3-week Probio-Eco intervention significantly improves constipation symptoms, stool straining, and worry scores. Gut microbiota and metabolomic analyses reveal modulations in specific gut microbiota, succinate, tryptophan derivatives, deoxycholate, propionate, butyrate, and cortisol, correlating with symptom relief. A loperamide-induced mouse model confirms that Probio-Eco and its bioactive components (succinate, 3-indoleacrylic acid, and 5-hydroxytryptophan) alleviate constipation by stimulating mucin-2 secretion, regulating intestinal transport hormones, and promoting anti-inflammatory responses. Multi-omics integration identifies key pathways, including succinate-short-chain fatty acid, tryptophan-5-hydroxytryptophan-serotonin, and tryptophan-3-indoleacrylic acid, driving intestinal homeostasis and motility. These findings highlight the comprehensive efficacy of Probio-Eco and provide robust evidence for its clinical application in constipation management. This study was registered at Chinese Clinical Trial Registry (ChiCTR2100054376).

Gut microbiota-derived short-chain fatty acids and their role in human health and disease

Short-chain fatty acids (SCFAs) are a group of organic compounds produced by the fermentation of dietary fibre by the human gut microbiota. They play diverse roles in different physiological processes of the host with implications for human health and disease. This Review provides an overview of the complex microbial metabolism underlying SCFA formation, considering microbial interactions and modulating factors of the gut environment. We explore the multifaceted mechanistic interactions between SCFAs and the host, with a particular focus on the local actions of SCFAs in the gut and their complex interactions with the immune system. We also discuss how these actions influence intestinal and extraintestinal diseases and emerging therapeutic strategies using SCFAs.

Effects of aged garlic extract on aging?related changes in gastrointestinal function and enteric nervous system cells

Dysmotility of the gastrointestinal (GI) tract is commonly seen in elderly individuals, where it causes significant morbidity and can lead to more severe conditions, including sarcopenia and frailty. Although the precise mechanisms underlying aging-related GI dysmotility are not fully understood, neuronal loss or degeneration in the enteric nervous system (ENS) may be involved. Aged garlic extract (AGE) has been shown to have several beneficial effects in the GI tract; however, it is not known whether AGE can improve GI motility in older animals. The aim of the present study was to examine the effects of AGE on the ENS and gut motility in older mice and elucidate potential mechanisms of action. An AGE-formulated diet was given to 18-month-old female mice for 2 weeks. Organ bath studies and cell culture demonstrated that AGE: i) Altered gut contractile activity; ii) enhanced viability of ENS cells; and iii) exhibited neuroprotective effects on the ENS via reduction in oxidative stress. These findings suggest that AGE could be used to develop novel dietary therapeutics for aging-related GI dysmotility by targeting the associated loss and damage of the ENS.

Measurement of Oro-Cecal Transit Time in LPS-Treated Pigs Fed High and Low Fiber Diets Using the Lactose-13C-Ureide Test in Breath and Saliva Samples

The lactose-13C-ureide (L13CU) test, used in humans to measure oro-cecal transit time (OCTT) in breath CO2, was assessed for its suitability in pigs as a noninvasive alternative to intestinal cannulation. The OCTT was determined with the L13CU test in breath and saliva samples when pigs were fed low or high dietary fiber (DF) (low fiber, 2.8% DF; high fiber 6.5% DF) diets, and 24 h after an i.m. injection with either lipopolysaccharide (LPS) or NaCl. The OCTT measured in breath was longer in LF-LPS than in LF-NaCl and HF-LPS groups (3.4 vs 2.9 h; p < 0.05). Additionally, LPS prolonged the OCTT of pigs, and DF prevented this effect. 90 % of OCTT estimates measured in saliva and breath CO2 did not differ. We conclude that the L13CU breath test is useful for determining OCTT in pigs; saliva is generally suitable as a sample matrix for OCTT, but its use requires further validation.

Antibiotic Cocktail Exacerbates Esomeprazole-Induced Intestinal Dysmotility While Ameliorating Gastric Dyspepsia in Mice

Background/Objectives: Esomeprazole, a proton pump inhibitor (PPI), is commonly prescribed for gastric-acid-related disorders but has been associated with impaired gastrointestinal (GI) motility with long-term use. However, the effect of concurrent antibiotic administration on this dysfunction remains unclear. Therefore, this study aimed to investigate the effects of antibiotics on esomeprazole-induced GI motility dysfunction and explore the underlying mechanisms in a mouse model. Methods: Male C57BL/6 mice were orally administered esomeprazole (160 mg/kg) five times per week for 4 weeks. Three days before initiating esomeprazole treatment, a broad-spectrum antibiotic cocktail (ABX) consisting of ampicillin (1 g/kg), neomycin (1 g/kg), metronidazole (1 g/kg), and vancomycin (0.5 g/kg) was provided in drinking water and maintained throughout the experimental period. Mosapride (3 mg/kg), a prokinetic agent, was used as a positive control. Results: Neither esomeprazole alone nor in combination with ABX affected body weight or food intake. Compared to normal controls, esomeprazole treatment significantly delayed both intestinal transit and gastric emptying. However, ABX co-administration further pronounced intestinal transit time and improved gastric motility. The potential mechanisms may involve interactions among gastric H+/K+-ATPase, CYP3A11, gastrointestinal hormones (secretin and motilin), and the gut microbiome. Conclusions: Long-term esomeprazole use can impair both gastric and intestinal motility, and ABX co-treatment further exacerbates intestinal transit delay while paradoxically enhancing gastric emptying. These findings highlight the critical role of the gut microbiota in esomeprazole-induced GI motility dysfunction and suggest that antibiotic use should be approached with caution, particularly when combined with PPI therapy.

Progresses in Questing for the Truth of Opioid-Related Constipation in Cancer Patients

Opioids are extensively utilised to manage pain in cancer patients, but may cause constipation which significantly impacts their prognosis and quality of life. Opioid-induced constipation (OIC) lacks effective drugs and management strategies. Opioids act on the enteric nervous system, intestinal barrier, intestinal immunity and intestinal microbiota, implying that OIC is a multifactorial process. This paper aims to examine the effects of opioids on the intestine, specifically the enteric nervous system, intestinal barrier and interstitial cells of Cajal (ICCs), and elucidate the primary mechanisms underlying OIC development and deterioration. This review suggests that enteric neurons, intestinal immunity and intestinal flora could serve as potential therapeutic targets for OIC.

The role of the gut microbiome in disorders of gut-brain interaction

Disorders of Gut-Brain Interaction (DGBI) are widely prevalent and commonly encountered in gastroenterology practice. While several peripheral and central mechanisms have been implicated in the pathogenesis of DGBI, a recent body of work suggests an important role for the gut microbiome. In this review, we highlight how gut microbiota and their metabolites affect physiologic changes underlying symptoms in DGBI, with a particular focus on their mechanistic influence on GI transit, visceral sensitivity, intestinal barrier function and secretion, and CNS processing. This review emphasizes the complexity of local and distant effects of microbial metabolites on physiological function, influenced by factors such as metabolite concentration, duration of metabolite exposure, receptor location, host genetics, and underlying disease state. Large-scale in vitro work has elucidated interactions between host receptors and the microbial metabolome but there is a need for future research to integrate such preclinical findings with clinical studies. The development of novel, targeted therapeutic strategies for DGBI hinges on a deeper understanding of these metabolite-host interactions, offering exciting possibilities for the future of treatment of DGBI.

Hesperidin enhances broiler growth performance by augmenting gastric acid secretion via the proton pump pathway

Hesperidin exhibits promising potential as a feed additive for augmenting gastric acid secretion in animals. Gastrointestinal function is essential for animal growth and the efficient digestion of dietary nutrients, with gastric acid secretion serving as one of its critical components. The secretion of gastric acid, together with other digestive fluids and substances, significantly influences the digestion and absorption of animal feed, which in turn affects growth performance. However, there is limited research regarding the application of hesperidin as a feed additive to enhance gastric acid secretion. The present study aims to evaluate the efficacy of hesperidin as a feed additive in enhancing gastric acid secretion and to elucidate its underlying mechanisms. A total of 200 newly hatched (1-day-old) broilers with similar body weight were randomly allocated into four groups as follows: the control group receiving only the basal diet, and the other three groups supplemented with 50, 100, and 150 mg of hesperidin per kg of the basal diet, respectively. Each group consisted of five replicates with ten broilers per replicate, and the feeding trial lasted for a duration of 21 days. The growth performance was evaluated by monitoring feed intake and body weight throughout the trial. A four-day nutrient utilization trial was conducted prior to the conclusion of the feeding experiment. Adoption of the total collection method, the collected droppings were weighed and dried at 65 °C. Fifteen broilers from each group were euthanized and immediately dissected to obtain gizzard, proventriculus, gizzard chyme, and jugular blood samples, The proventriculus and gizzard weight were weighed and the pH of gizzard chyme was measured at the same time. The collected jugular venous blood was used to assess gastrin levels, whereas chicken gizzard chyme was utilized for the analysis of lactate, hydrochloric acid, and pepsin activity. Proventriculus and gizzard tissues were used to evaluate pepsinogen levels, perform hematoxylin-eosin (H&E) staining, conduct enzyme-linked immunosorbent assays (ELISAs) for key proton pump components, and assess proton pump activity. The results demonstrated that, in comparison to the control group, both the 100mg/Kg and 150 mg/Kg groups exhibited a significant increase in final body weight (FBW) and average daily gain (ADG) (P < 0.05). Additionally, the feed to gain ratio (F/G) was significantly reduced in the 150mg/Kg group (P < 0.05). The results of the nutrient utilization trial indicate that all treatment groups had significantly higher levels of dry matter (DM) and ether extract (EE) compared to the control group (P < 0.05). Furthermore, crude protein (CP) and gross energy (ME) were significantly higher in the 100mg/Kg and 150mg/Kg groups than in both the control group and the 50mg/Kg group (P < 0.05). The inclusion of hesperidin in broiler diets leads to significant improvements in stomach development and lactic acid content, while pH and hydrochloric acid content exhibit opposite trends (P < 0.05). Supplementation of broiler diets with hesperidin at doses of 100 mg/Kg and 150 mg/Kg significantly up-regulates pepsin activity and pepsinogen levels (P < 0.05). Incorporation of hesperidin into the broilers' diet significantly enhances parietal cell numbers (P < 0.05). Dietary supplementation of hesperidin in broilers effectively up-regulates key signaling pathways and intracellular signal substances involved in proton pump activation (P < 0.05). The proton pump activity also exhibited a significant increase compared to the control group of 100mg/Kg and 150mg/Kg (P < 0.05) in our findings. In conclusion, hesperidin exhibits promising potential as a feed additive for broilers, and it can improve the growth performance of broilers by increasing gastric acid secretion and promoting nutrient utilization through activation of proton pump. Notably, basal diet supplemented with 150mg/Kg hesperidin demonstrates superior efficacy.

Nitric oxide in the mechanisms of inhibitory effects of sodium butyrate on colon contractions in a mouse model of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a multifactorial disorder, with altered intestinal motility, visceral hypersensitivity, and dysfunction of the gut-brain axis. The aim of our study was to analyze the role of nitric oxide (NO) in the inhibitory effects of sodium butyrate on spontaneous contractility of proximal colon in a mouse model of IBS. IBS was induced by intracolonic infusion of acetic acid in the early postnatal period. Spontaneous contractions of proximal colon segments were studied in isometric conditions. The amplitude and frequency of colon contractions were higher in the IBS group. Sodium butyrate exerted inhibitory effects on colon contractions, which were less pronounced in IBS group. NO donors decreased spontaneous colon contractility and prevented the inhibitory effects of sodium butyrate in control and IBS groups. Nitric oxide synthase (NOS) inhibition by L-NAME increased contractile activity more effective in the control group and decreased the inhibitory action of sodium butyrate. In IBS group, preliminary application of L-NAME did not prevent sodium butyrate action. Our data indicate that butyrate exerts its inhibitory effects on colon motility at least partially through activation of NO synthesis. In the IBS model group, the NO-dependent mechanisms were less effective probably due to downregulation of NOS.

Aromatic Amino Acid Metabolites: Molecular Messengers Bridging Immune-Microbiota Communication

Aromatic amino acid (AAA) metabolites, derived from tryptophan, phenylalanine, and tyrosine through coordinated host and microbial metabolism, have emerged as critical modulators of immune function. We examine the complex journey of AAAs from dietary intake through intestinal absorption and metabolic transformation, highlighting the crucial role of host-microbe metabolic networks in generating diverse immunomodulatory compounds. This review provides a unique integrative perspective by mapping the molecular mechanisms through which these metabolites orchestrate immune responses. Through detailed analysis of metabolite-receptor and metabolite-transporter interactions, we reveal how specific molecular recognition drives cell type-specific immune responses. Our comprehensive examination of signaling networks-from membrane receptor engagement to nuclear receptor activation to post-translational modifications- demonstrates how the same metabolite can elicit distinct functional outcomes in different immune cell populations. The context-dependent nature of these molecular interactions presents both challenges and opportunities for therapeutic development, particularly in inflammatory conditions where metabolite signaling pathways are dysregulated. Understanding the complexity of these regulatory networks and remaining knowledge gaps is fundamental for advancing metabolite-based therapeutic strategies in immune-mediated disorders.

New perspectives on microbiome-dependent gut-brain pathways for the treatment of depression with gastrointestinal symptoms: from bench to bedside

Patients with depression are more likely to have chronic gastrointestinal (GI) symptoms than the general population, but such symptoms are considered only somatic symptoms of depression and lack special attention. There is a chronic lack of appropriate diagnosis and effective treatment for patients with depression accompanied by GI symptoms, and studying the association between depression and GI disorders (GIDs) is extremely important for clinical management. There is growing evidence that depression is closely related to the microbiota present in the GI tract, and the microbiota-gut-brain axis (MGBA) is creating a new perspective on the association between depression and GIDs. Identifying and treating GIDs would provide a key opportunity to prevent episodes of depression and may also improve the outcome of refractory depression. Current studies on depression and the microbially related gut-brain axis (GBA) lack a focus on GI function. In this review, we combine preclinical and clinical evidence to summarize the roles of the microbially regulated GBA in emotions and GI function, and summarize potential therapeutic strategies to provide a reference for the study of the pathomechanism and treatment of depression in combination with GI symptoms.

Exploring Gut Microbiota Imbalance in Irritable Bowel Syndrome: Potential Therapeutic Effects of Probiotics and Their Metabolites

Irritable bowel syndrome is a common functional gastrointestinal disorder characterized by recurrent abdominal discomfort, bloating, cramping, flatulence, and changes in bowel movements. The pathophysiology of IBS involves a complex interaction between motor, sensory, microbiological, immunological, and psychological factors. Diversity, stability, and metabolic activity of the gut microbiota are frequently altered in IBS, thus leading to a situation of gut dysbiosis. Therefore, the use of probiotics and probiotic-derived metabolites may be helpful in balancing the gut microbiota and alleviating irritable bowel syndrome symptoms. This review aimed to report and consolidate recent progress in understanding the role of gut dysbiosis in the pathophysiology of IBS, as well as the current studies that have focused on the use of probiotics and their metabolites, providing a foundation for their potential beneficial effects as a complementary and alternative therapeutic strategy for this condition due to the current absence of effective and safe treatments.

Probiotic Formulation for Patients With Bipolar or Schizophrenia Spectrum Disorder: A Double-Blind, Randomized Placebo-Controlled Trial

BACKGROUND AND HYPOTHESIS

Probiotic augmentation offers a promising treatment for bipolar disorder (BD) and schizophrenia spectrum disorder (SSD). By targeting microbiome deviations, they may improve both gut and brain health.

STUDY DESIGN

In this double-blind, randomized, placebo-controlled trial with the multi-strain probiotic formulation Ecologic BARRIER, we aimed to improve psychiatric and cognitive symptoms, intestinal permeability, and gastrointestinal symptoms in patients with BD or SSD. A total of 131 patients were randomized 1:1 to receive either the probiotic supplement (n = 67) or a placebo (n = 64) for 3 months, in addition to treatment-as-usual. The primary outcomes were symptom severity assessed by the Brief Psychiatric Rating Scale and cognitive functioning by the Brief Assessment of Cognition in Schizophrenia.

STUDY RESULTS

No significant effect of probiotics was observed on psychiatric symptoms, but borderline significant improvement was observed in the cognition category of verbal memory (Linear Mixed Model (LMM) 0.33; adjusted P = .059). Probiotics beneficially affected markers of intestinal permeability and inflammation, including zonulin (LMMserum = -18.40; adjusted P = .002; LMMfecal = -10.47; adjusted P = .014) and alpha-1 antitrypsin (LMM 9.26; adjusted P = .025). Indigestion complaints significantly decreased in male participants in the probiotics group (LMM = -0.70; adjusted P = .010). Adverse events were similar between groups.

CONCLUSIONS

Our study observed significant advantages of probiotics for gut health in BD and SSD, with excellent safety and tolerability. A borderline effect on verbal memory was also indicated. These results underscore the need for further research into microbiome-targeted interventions for patients with complex brain disorders.

Ex vivo and miniaturized in vitro models to study microbiota-gut-brain axis

The microbiota-gut-brain axis involves complex bidirectional communication through neural, immune, and endocrine pathways. Microbial metabolites, such as short-chain fatty acids, influence gut motility and brain function by interacting with gut receptors and modulating hormone release. Additionally, microbial components such as lipopolysaccharides and cytokines can cross the gut epithelium and the blood-brain barrier, impacting immune responses and cognitive function. Ex vivo models, which preserve gut tissue and neural segments, offer insight into localized gut-brain communication by allowing for detailed study of nerve excitability in response to microbial signals, but they are limited in systemic complexity. Miniaturized in vitro models, including organ-on-chip platforms, enable precise control of the cellular environment and simulate complex microbiota-host interactions. These systems allow for the study of microbial metabolites, immune responses, and neuronal activity, providing valuable insights into gut-brain communication. Despite challenges such as replicating long-term biological processes and integrating immune and hormonal systems, advancements in bioengineered platforms are enhancing the physiological relevance of these models, offering new opportunities for understanding the mechanisms of the microbiota-gut-brain axis. This review aims to describe the ex vivo and miniaturized in vitro models which are used to mimic the in vivo conditions and facilitate more precise studies of gut brain communication.

Shatianyu (Citrus grandis L. Osbeck) whole fruit alleviated loperamide-induced constipation via enhancing gut microbiota-mediated intestinal serotonin secretion and mucosal barrier homeostasis

This study aims to explore the effects of Shatianyu (Citrus grandis L. Osbeck) whole fruit powder (SWFP) enriched in flavonoids and dietary fiber on loperamide-induced constipation after a 4-week administration in the diet, together with possible microbiota-mediated mechanisms. The SWFP intervention shortened the first defecation time and increased defecation frequency; it also increased the serum serotonin (5-HT) level and decreased the LPS level in constipation mice. SWFP promoted the development of colonic enterochromaffin cells (ECs) and upregulated the expression of 5-HT synthetic rate-limiting enzyme (Tph1) in ECs. Furthermore, SWFP downregulated the expression of colonic TLR-4, TNF-α and IL-1β and upregulated the expression of tight junction proteins. Besides promoting 5-HT secretion in ECs, butyrate was proved to play a positive role in enhancing intestinal barrier homeostasis through FFAR2/3. Notably, SWFP increased both the fecal butyrate contents and colonic FFAR3 expression in a dose-related manner. Likewise, SWFP enriched butyrate-production related microbes, such as Ruminococcus_torques_group, Ruminococcus, Dubosiella and Parasutterella. Thus, SWFP might alleviate constipation by regulating the microbiota to produce butyrate, thereby enhancing colonic 5-HT secretion and the FFAR3-mediated anti-inflammatory pathway.

Constipation is associated with an increased risk of major adverse cardiac events in a UK population

Traditional cardiovascular risk factors, including hypertension, only explain part of major adverse cardiac events (MACEs). Understanding what other risk factors contribute to MACE is essential for prevention. Constipation shares common risk factors with hypertension and is associated with an increased risk of several cardiovascular diseases. We hypothesized that constipation is an underappreciated risk factor for MACE. We used the population healthcare and genomic data in the UK Biobank (n = 408,354) to study the contribution of constipation (ICD10 K59.0) to the risk of MACE, defined by any episode of acute coronary syndrome (ACS), ischemic stroke, and heart failure (HF). Analyses were controlled for traditional cardiovascular risk factors. We also assessed genetic correlations (rg) between constipation and MACE. Constipation cases (n = 23,814) exhibited a significantly higher risk of MACE compared with those with normal bowel habits [odds ratio (OR) = 2.15, P < 1.00 × 10-300]. Constipation was also significantly associated with individual MACE subgroups, in order: HF (OR = 2.72, P < 1.00 × 10-300), ischemic stroke (OR = 2.36, P = 2.02 × 10-230), and ACS (OR = 1.62, P = 5.82 × 10-113). In comparison with patients with constipation-free hypertension, patients with hypertension with constipation showed significantly higher odds of MACE (OR = 1.68, P = 1.05 × 10-136) and a 34% increased risk of MACE occurrence (P = 2.3 × 10-50) after adjustment for medications that affect gut motility and other traditional cardiovascular risk factors. Finally, we detected positive genetic correlations between constipation and MACE subgroups ACS (rg = 0.27, P = 2.12 × 10-6), ischemic stroke (rg = 0.23, P = 0.011), and HF (rg = 0.21, P = 0.0062). We identified constipation as a potential risk factor independently associated with higher MACE prevalence. These findings warrant further studies on their causal relationship and identification of pathophysiological mechanisms.NEW & NOTEWORTHY Analyzing 408,354 participants of the UK Biobank, we show that constipation cases exhibited a significantly higher risk of major adverse cardiac events (MACEs) than those with regular bowel habits. In comparison with patients with constipation-free hypertension, patients with hypertension with constipation showed significantly higher odds of MACE and a 34% increased risk of subsequent MACE occurrence. Finally, we detected positive genetic correlations between constipation and MACE. This association holds potential for therapeutic exploitation and prevention based on individuals' risk assessment.

Dysbiosis of gut microbiota is associated with pathogenesis of peptic ulcer diseases through inflammatory proteins: A Mendelian randomization study

The gut microbiota and inflammatory proteins may affect the development of peptic ulcer disease. However, this association remains unclear. We analyzed genome-wide association study data of gut microbiota, inflammatory proteins, and peptic ulcer disease using Mendelian randomization with instrumental variables to assess causal relationships. Various statistical methods, including inverse variance weighting, Mendelian randomization Egger regression, and sensitivity analysis were employed to evaluate the data and calculate mediation ratios. Our findings reveal that the genus Butyriciccus plays a role in mitigating the adverse effects of gastric ulcers by 7.9%, primarily through reducing beta-negative growth factor levels. Additionally, the genus Lachnospiraceae UCG004 can significantly alleviate the negative outcomes of gastric ulcers and reduces hepatocyte growth factor and beta-reserve growth factor levels by 6.39% and 7.45%, respectively. This study highlights the independent and mediating effects of the gut microbiota and inflammatory proteins on peptic ulcers, offering insights on potential pathways and targets for future preventive interventions.

Addressing GI Health Through the Bidirectional Modulation of the Gut-Brain Axis With Herbal Extracts: A Narrative Review

Functional gastrointestinal disorders (FGIDs) refer to a group of disorders with chronic symptoms, such as abdominal pain, dysphagia, dyspepsia, diarrhea, constipation, and bloating. Among these, functional constipation significantly impacts the quality of life and is linked with comorbidities, such as anxiety and depression. The exact pathophysiology remains unclear despite the widespread occurrence. Research suggests that the gut-brain axis plays a role in FGIDs. Disruptions in the bidirectional communication between the brain and gastrointestinal (GI) tract contribute to GI symptoms and mood disturbances. The incomplete understanding of FGID pathophysiology has led to limited treatment options. Traditional treatments often focus on single symptoms and come with side effects, prompting the need for alternative approaches that address both GI and psychological components. Alternative approaches including herbal supplements offer a natural alternative to conventional medicine by promoting regularity and gut health. Abelmoschus esculentus L. or okra has a history of use in traditional medicine. Bioactive compounds such as polysaccharides and fibers found in okra offer gastroprotective benefits. Withania somnifera is a plant commonly referred to as ashwagandha. The plant root has been used for its health-promoting effects. Research supports the use of W. somnifera to help with stress and sleep. Digexin is a herbal supplement combining W. somnifera (ashwagandha) and A. esculentus (okra). It has shown promise in improving both GI regularity and mood by modulating the gut-brain axis. Clinical studies support the potential of a novel herbal supplement that aids in the management of FGIDs. This narrative review looks at FGIDs, etiologies, current treatment, and possible therapeutic supplements to aid in symptom management.

The gut-brain and gut-macrophage contribution to gastrointestinal dysfunction with systemic inflammation

The gastrointestinal tract is one of the main organs affected during systemic inflammation and disrupted gastrointestinal motility is a major clinical manifestation. Many studies have investigated the involvement of neuroimmune interactions in regulating colonic motility during localized colonic inflammation, i.e., colitis. However, little is known about how the enteric nervous system and intestinal macrophages contribute to dysregulated motility during systemic inflammation. Given that systemic inflammation commonly results from the innate immune response against bacterial infection, we mimicked bacterial infection by administering lipopolysaccharide (LPS) to rats and assessed colonic motility using ex vivo video imaging techniques. We utilized the Cx3cr1-Dtr rat model of transient depletion of macrophages to investigate the role of intestinal macrophages in regulating colonic motility during LPS infection. To investigate the role of inhibitory enteric neurotransmission on colonic motility following LPS, we applied the nitric oxide synthase inhibitor, Nω-nitro-L-arginine (NOLA). Our results confirmed an increase in colonic contraction frequency during LPS-induced systemic inflammation. However, neither the depletion of intestinal macrophages, nor the suppression of inhibitory enteric nervous system activity impacted colonic motility disruption during inflammation. This implies that the interplay between the enteric nervous system and intestinal macrophages is nuanced, and complex, and further investigation is needed to clarify their joint roles in colonic motility.

Bifidobacterium longum S3 alleviates loperamide-induced constipation by modulating intestinal acetic acid and stearic acid levels in mice

Constipation is a major gastrointestinal (GI) symptom worldwide, with diverse causes of formation, and requires effective and safe therapeutic measures. In the present study, we used loperamide hydrochloride to establish a constipation model and assessed the effect of Bifidobacterium on constipation and its possible mechanism of relief. The results showed that B. longum S3 exerted a constipation-relieving effect primarily by improving the gut microbiota, enriching genera including Lactobacillus, Alistipes, and Ruminococcaceae UCG-007, and decreasing the bacteria Lachnospiraceae NK4B4 group. These changes may thereby increase acetic acid and stearic acid (C18:0) levels, which significantly increase the expression levels of ZO-1 and MUC-2, repair intestinal barrier damage and reduce inflammation (IL-6). Furthermore, it also inhibited oxidative stress levels (SOD and CAT), decreased the expression of water channel proteins (AQP4 and AQP8), significantly elevated the Gas, 5-HT, PGE2, and Ach levels, and reduced nNOS and VIP levels to improve the intestinal luminal transit time and fecal water content. Collectively, these changes resulted in the alleviation of constipation.

Characterizing arginine, ornithine, and putrescine pathways in enteric pathobionts

Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream products of its metabolism remain undefined in various gut bacteria. To bridge this knowledge gap, we employed genomic screening to pinpoint relevant metabolic targets. We also devised a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method to measure the levels of arginine, its upstream precursors, and downstream products in cell-free conditioned media from enteric pathobionts, including Escherichia coli, Klebsiella aerogenes, K. pneumoniae, Pseudomonas fluorescens, Acinetobacter baumannii, Streptococcus agalactiae, Staphylococcus epidermidis, S. aureus, and Enterococcus faecalis. Our findings revealed that all selected bacterial strains consumed glutamine, glutamate, and arginine, and produced citrulline, ornithine, and GABA in our chemically defined medium. Additionally, E. coli, K. pneumoniae, K. aerogenes, and P. fluorescens were found to convert arginine to agmatine and produce putrescine. Interestingly, arginine supplementation promoted biofilm formation in K. pneumoniae, while ornithine supplementation enhanced biofilm formation in S. epidermidis. These findings offer a comprehensive insight into arginine-ornithine metabolism in enteric pathobionts.

Pharmacomicrobiomics of cell-cycle specific anti-cancer drugs - is it a new perspective for personalized treatment of cancer patients?

Intestinal bacteria are equipped with an enzyme apparatus that is involved in the active biotransformation of xenobiotics, including drugs. Pharmacomicrobiomics, a new area of pharmacology, analyses interactions between bacteria and xenobiotics. However, there is another side to the coin. Pharmacotherapeutic agents can significantly modify the microbiota, which consequently affects their efficacy. In this review, we comprehensively gathered scientific evidence on the interplay between anticancer therapies and gut microbes. We also underlined how such interactions might impact the host response to a given therapy. We discuss the possibility of modulating the gut microbiota to increase the effectiveness/decrease the incidence of adverse events during tumor therapy. The anticipation of the future brings new evidence that gut microbiota is a target of interest to increase the efficacy of therapy.

From trash to treasure: the role of bacterial extracellular vesicles in gut health and disease

Bacterial extracellular vesicles (BEVs) have emerged as critical factors involved in gut health regulation, transcending their traditional roles as byproducts of bacterial metabolism. These vesicles function as cargo carriers and contribute to various aspects of intestinal homeostasis, including microbial balance, antimicrobial peptide secretion, physical barrier integrity, and immune system activation. Therefore, any imbalance in BEV production can cause several gut-related issues including intestinal infection, inflammatory bowel disease, metabolic dysregulation, and even cancer. BEVs derived from beneficial or commensal bacteria can act as potent immune regulators and have been implicated in maintaining gut health. They also show promise for future clinical applications in vaccine development and tumor immunotherapy. This review examines the multifaceted role of BEVs in gut health and disease, and also delves into future research directions and potential applications.

Effects of Lactiplantibacillus plantarum GUANKE on Diphenoxylate-Induced Slow Transit Constipation and Gut Microbiota in Mice

Slow transit constipation (STC) is a prevalent gastrointestinal condition with slow transit, and some probiotics can effectively relieve constipation, but the exact mechanisms have not been fully understood. In this study, we evaluate the impact of Lactiplantibacillus plantarum GUANKE (GUANKE) on diphenoxylate-induced slow transit constipation and speculate on the underlying mechanisms in a mouse model. Administration of L. plantarum GUANKE alleviated constipation indexes, including defecation time, fecal output and water content, and gastrointestinal transit ratio. In addition, GUANKE restored the protein expression of constipation-related intestinal factors (aquaporins (AQPs) and interstitial Cajal cells (ICCs)) in colon tissues measured using immunofluorescence staining; regulated the neurotransmitters and hormones, such as increased levels of 5-hydroxytryptamine, substance P, and motilin; and decreased levels of vasoactive intestinal peptide and nitric oxide in serum, as measured by an ELISA. 16S rRNA and correlation analysis of feces indicated that GUANKE administration effectively reduced constipation-induced Prevotella enrichment and suggested a potential contribution of Prevotella to diphenoxylate-induced STC in mice. GUANKE had no effect on short-chain fatty acids (SCFAs) in cecum content. This study revealed that GUANKE may alleviate constipation in mice through regulating intestinal neurotransmitter and hormone release and altering specific bacterial taxa, rather than by affecting SCFAs and the diversity of microbiota in the gut. Further research is needed to confirm if the findings observed in this study will be consistent in other animal studies or clinical trials.

Antispasmodic Effect of Valeriana pilosa Root Essential Oil and Potential Mechanisms of Action: Ex Vivo and In Silico Studies

Infusions of Valeriana pilosa are commonly used in Peruvian folk medicine for treating gastrointestinal disorders. This study aimed to investigate the spasmolytic and antispasmodic effects of Valeriana pilosa essential oil (VPEO) on rat ileum. The basal tone of ileal sections decreased in response to accumulative concentrations of VPEO. Moreover, ileal sections precontracted with acetylcholine (ACh), potassium chloride (KCl), or barium chloride (BaCl2) were relaxed in response to VPEO by a mechanism that depended on atropine, hyoscine butylbromide, solifenacin, and verapamil, but not glibenclamide. The results showed that VPEO produced a relaxant effect by inhibiting muscarinic receptors and blocking calcium channels, with no apparent effect on the opening of potassium channels. In addition, molecular docking was employed to evaluate VPEO constituents that could inhibit intestinal contractile activity. The study showed that α-cubebene, β-patchoulene, β-bourbonene, β-caryophyllene, α-guaiene, γ-muurolene, valencene, eremophyllene, and δ-cadinene displayed the highest docking scores on muscarinic acetylcholine receptors and voltage-gated calcium channels, which may antagonize M2 and/or M3 muscarinic acetylcholine receptors and block voltage-gated calcium channels. In summary, VPEO has both spasmolytic and antispasmodic effects. It may block muscarinic receptors and calcium channels, thus providing a scientific basis for its traditional use for gastrointestinal disorders.

Fu Brick Tea Alleviates Constipation via Regulating the Aquaporins-Mediated Water Transport System in Association with Gut Microbiota

This study aimed to investigate the amendatory effects of Fu brick tea aqueous extract (FTE) on constipation and its underlying molecular mechanism. The administration of FTE by oral gavage (100 and 400 mg/kg·bw) for 5 weeks significantly increased fecal water content, improved difficult defecation, and enhanced intestinal propulsion in loperamide (LOP)-induced constipated mice. FTE also reduced colonic inflammatory factors, maintained the intestinal tight junction structure, and inhibited colonic Aquaporins (AQPs) expression, thus normalizing the intestinal barrier and colonic water transport system of constipated mice. 16S rRNA gene sequence analysis results indicated that two doses of FTE increased the Firmicutes/Bacteroidota (F/B) ratio at the phylum level and increased the relative abundance of Lactobacillus from 5.6 ± 1.3 to 21.5 ± 3.4% and 28.5 ± 4.3% at the genus level, subsequently resulting in a significant elevation of colonic contents short-chain fatty acids levels. The metabolomic analysis demonstrated that FTE improved levels of 25 metabolites associated with constipation. These findings suggest that Fu brick tea has the potential to alleviate constipation by regulating gut microbiota and its metabolites, thereby improving the intestinal barrier and AQPs-mediated water transport system in mice.

The implication of gut microbiota in recovery from gastrointestinal surgery

Recovery from gastrointestinal (GI) surgery is often interrupted by the unpredictable occurrence of postoperative complications, including infections, anastomotic leak, GI dysmotility, malabsorption, cancer development, and cancer recurrence, in which the implication of gut microbiota is beginning to emerge. Gut microbiota can be imbalanced before surgery due to the underlying disease and its treatment. The immediate preparations for GI surgery, including fasting, mechanical bowel cleaning, and antibiotic intervention, disrupt gut microbiota. Surgical removal of GI segments also perturbs gut microbiota due to GI tract reconstruction and epithelial barrier destruction. In return, the altered gut microbiota contributes to the occurrence of postoperative complications. Therefore, understanding how to balance the gut microbiota during the perioperative period is important for surgeons. We aim to overview the current knowledge to investigate the role of gut microbiota in recovery from GI surgery, focusing on the crosstalk between gut microbiota and host in the pathogenesis of postoperative complications. A comprehensive understanding of the postoperative response of the GI tract to the altered gut microbiota provides valuable cues for surgeons to preserve the beneficial functions and suppress the adverse effects of gut microbiota, which will help to enhance recovery from GI surgery.

Gut-on-a-Chip Models: Current and Future Perspectives for Host-Microbial Interactions Research

The intestine contains the largest microbial community in the human body, the gut microbiome. Increasing evidence suggests that it plays a crucial role in maintaining overall health. However, while many studies have found a correlation between certain diseases and changes in the microbiome, the impact of different microbial compositions on the gut and the mechanisms by which they contribute to disease are not well understood. Traditional pre-clinical models, such as cell culture or animal models, are limited in their ability to mimic the complexity of human physiology. New mechanistic models, such as organ-on-a-chip, are being developed to address this issue. These models provide a more accurate representation of human physiology and could help bridge the gap between clinical and pre-clinical studies. Gut-on-chip models allow researchers to better understand the underlying mechanisms of disease and the effect of different microbial compositions on the gut. They can help to move the field from correlation to causation and accelerate the development of new treatments for diseases associated with changes in the gut microbiome. This review will discuss current and future perspectives of gut-on-chip models to study host-microbial interactions.

Stimulatory Effect of Lactobacillus Metabolites on Colonic Contractions in Newborn Rats

Microbiota are known to play an important role in gastrointestinal physiology and pathophysiology. Microbiota and their metabolites can affect gut motility, neural regulation and the enteric endocrine systems and immune systems of the gut. The use of fermented/hydrolyzed products may be a promising new avenue for stimulating gastrointestinal motility. The purpose of this study was to investigate the effect of lactobacillus metabolites (PP), produced using a U.S.-patented fermentation method, on rat colon motility in vitro. The distal colon was incised from newborn male Wistar rats. A sensitive tensometric method for the study of colon contractions was used. The [Ca2+]i in colon tissue was registered using a computerized ratiometric system for an intracellular ion content assay (Intracellular Imaging and Photometry System, Intracellular imaging, Inc. Cincinnati, OH, USA). The cumulative addition of PP induced contraction with sigmoid dose responses with ED50 = 0.13 ± 0.02% (n = 4), where 10% PP was accepted as a maximal dose. This contraction was accompanied by an increase in the concentration of [Ca2+]i. It was shown that introducing Lactobacillus metabolites produced using a U.S.-patented fermentation method quickly stimulates dose-dependent colon contractions and an increase in intracellular calcium. The direct application of PP via enema to the colon could stimulate colon motility and suppress pathogenic microbiota, owing to the antagonistic property of PP on pathogens.

The Gut Microbiome and Its Implication in the Mucosal Digestive Disorders

The gastrointestinal (GI) tract is one of the most studied compartments of the human body as it hosts the largest microbial community including trillions of germs. The relationship between the human and its associated flora is complex, as the microbiome plays an important role in nutrition, metabolism and immune function. With a dynamic composition, influenced by many intrinsic and extrinsic factors, there is an equilibrium maintained in the composition of GI microbiota, translated as "eubiosis". Any disruption of the microbiota leads to the development of different local and systemic diseases. This article reviews the human GI microbiome's composition and function in healthy individuals as well as its involvement in the pathogenesis of different digestive disorders. It also highlights the possibility to consider flora manipulation a therapeutic option when treating GI diseases.