Complex interactions among diet, gastrointestinal transit, and gut microbiota in humanized mice

Large intestinal nutritional and physicochemical parameters from different dog sizes reshape canine microbiota structure and functions in vitro

Different dog sizes are associated with variations in large intestinal physiology including gut microbiota, which plays a key role in animal health. This study aims to evaluate, using the CANIM-ARCOL (Canine Mucosal Artificial Colon), the relative importance of gut microbes versus physicochemical and nutritional parameters of the canine colonic environment in shaping microbiota structure and functions. CANIM-ARCOL was set up to reproduce nutrient availability, bile acid profiles, colonic pH, and transit time from small, medium, or large dogs according to in vivo data, while bioreactors were all inoculated with a fecal sample collected from medium size dogs (n = 2). Applying different dog size parameters resulted in a positive association between size and gas or SCFA production, as well as distinct microbiota profiles as revealed by 16S Metabarcoding. Comparisons with in vivo data from canine stools and previous in vitro results obtained when CANIM-ARCOL was inoculated with fecal samples from three dog sizes revealed that environmental colonic parameters were sufficient to drive microbiota functions. However, size-related fecal microbes were necessary to accurately reproduce in vitro the colonic ecosystem of small, medium, and large dogs. For the first time, this study provides mechanistic insights on which parameters from colonic ecosystem mainly drive canine microbiota in relation to dog size. The CANIM-ARCOL can be used as a relevant in vitro platform to unravel interactions between food or pharma compounds and canine colonic microbiota, under different dog size conditions. The potential of the model will be extended soon to diseased situations (e.g. chronic enteropathies or obesity).

Unveiling gut microbiota's role: Bidirectional regulation of drug transport for improved safety

Drug safety is a paramount concern in the field of drug development, with researchers increasingly focusing on the bidirectional regulation of gut microbiota in this context. The gut microbiota plays a crucial role in maintaining drug safety. It can influence drug transport processes in the body through various mechanisms, thereby modulating their efficacy and toxicity. The main mechanisms include: (1) The gut microbiota directly interacts with drugs, altering their chemical structure to reduce toxicity and enhance efficacy, thereby impacting drug transport mechanisms, drugs can also change the structure and abundance of gut bacteria; (2) bidirectional regulation of intestinal barrier permeability by gut microbiota, promoting the absorption of nontoxic drugs and inhibiting the absorption of toxic components; (3) bidirectional regulation of the expression and activity of transport proteins by gut microbiota, selectively promoting the absorption of effective components or inhibiting the absorption of toxic components. This bidirectional regulatory role enables the gut microbiota to play a key role in maintaining drug balance in the body and reducing adverse reactions. Understanding these regulatory mechanisms sheds light on novel approaches to minimize toxic side effects, enhance drug efficacy, and ultimately improve drug safety. This review systematically examines the bidirectional regulation of gut microbiota in drug transportation from the aforementioned aspects, emphasizing their significance in ensuring drug safety. Furthermore, it offers a prospective outlook from the standpoint of enhancing therapeutic efficacy and reducing drug toxicity, underscoring the importance of further exploration in this research domain. It aims to provide more effective strategies for drug development and treatment.

Baicalin ameliorates heat stress-induced hepatic injury and intestinal microecology dysbiosis in late gestational mice

Heat stress (HS) disrupts intestinal microbiota, glycolipid metabolism, and hepatic mitochondrial function in late gestational mice. Baicalin (BAI), a Chinese herbal medicine known for its heat-clearing and anti-inflammatory properties, has shown promise in modulating intestinal microecology and mitigating inflammation in various organs. This study investigates whether baicalin attenuates HS-induced intestinal microbial dysbiosis and liver damage in pregnant mice during late gestation. Twenty-four pregnant mice were randomly assigned to four groups, including thermoneutral (TN) (24 ± 1 ℃), HS (35 ± 1 ℃), HS+BAI200 (oral gavaged with 200 mg/kg BW of BAI), and HS+BAI400 (oral gavaged with 400 mg/kg BW of BAI). 400 mg/kg BAI treatment markedly decreased the rectal temperature and increased fetal weight in HS pregnant mice. Furthermore, 400 mg/kg BAI administration effectively ameliorated HS-induced hepatic damage and lipid disorders, reducing HSP70, AST, and ALT levels while increasing TG concentration. Notably, it activated a network of genes involved in lipid synthesis, including fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), and oxidation, such as peroxisome proliferator-activated receptor alpha (PPARα), carnitine palmityl transferase 1 beta (CPT1β). Moreover, BAI intervention restored the intestinal morphology and barrier function, evidenced by increased intestinal villus height, the ratio of villus height to crypt depth, and colonic goblet cells numbers. 400 mg/kg of BAI treatment up-regulated the expression of tight junction proteins, such as claudin-1 and Zonula Occludens-1 (ZO-1), in the jejunum and ileum, counteracting HS-induced downregulation. High-throughput sequencing showed that BAI treatment altered cecal microbial composition, increasing the relative abundance of beneficial Bacteroidota and decreasing Deferribacterota, Turicibacter, and Akkermansia. Spearman's correlation analysis highlighted significant correlations between differential cecal microbiota and physiological indexes. In conclusion, BAI administration alleviated adverse impacts in heat-exposed mice during late gestation, improving maternal physiological parameters, and ameliorating hepatic damage with altered cecal microbial composition. The findings suggest that BAI may regulate the gut-liver axis by modulating intestinal morphology, microecology, and hepatic function.

The importance of food quality, gut motility, and microbiome in SIBO development and treatment

The prevalence of small intestinal bacterial overgrowth (SIBO) is rising worldwide, particularly in nations with high rates of urbanization. Irritable bowel syndrome, inflammatory bowel illnesses, and nonspecific dysmotility are strongly linked to SIBO. Moreover, repeated antibiotic therapy promotes microorganisms' overgrowth through the development of antibiotic resistance. The primary cause of excessive fermentation in the small intestine is a malfunctioning gastrointestinal motor complex, which results in the gut's longer retention of food residues. There are anatomical and physiological factors affecting the functioning of the myoelectric motor complex. Except for them, diet conditions the activity of gastrointestinal transit. Indisputably, the Western type of nutrition is unfavorable. Some food components have greater importance in the functioning of the gastrointestinal motor complex than others. Tryptophan, an essential amino acid and precursor of the serotonin hormone, accelerates intestinal transit, and gastric emptying, similarly to fiber and polyphenols. Additionally, the effect of food on the microbiome is important, and diet should prevent bacterial overgrowth and exhibit antimicrobial effects against pathogens. Therefore, knowledge about proper nutrition is essential to prevent the development and recurrence of SIBO. Since the scientific world was unsure whether there was a long-term or potential solution for SIBO until quite recently, research on a number of the topics included in the article should be performed. The article aimed to summarize current knowledge about proper nutrition after SIBO eradication and the prevention of recurrent bacterial overgrowth. Moreover, a connection was found between diet, gut dysmotility, and SIBO.

Assessing the causal effects of Eubacterium and Rumphococcus on constipation: a Mendelian randomized study

Background

Constipation is affected by a number of risk variables, including cardiovascular disease and growth factors. However, the impacts of gut flora on constipation incidence has not been shown. This work, Single-Variable Mendelian Randomization (SVMR) was utilized to estimate the causal relationship between the Eubacterium genus or Rumphococcus, and constipation.

Methods

Data for constipation, Eubacterium genus and Rumphococcus were taken from the Integrated Epidemiology Unit (IEU) open GWAS database. Including 218,792 constipation samples, and there were 16,380,466 Single Nucleotide Polymorphisms (SNPs) for constipation. The ids of Eubacterium genus and Rumphococcus were sourced from MiBioGen database. The sample count for the Eubacterium genus was 17,380, with 656 SNPs. In addition, the sample size for Rumphococcus was 15,339, with 545 SNPs. The SVMR was performed to assess the risk of Eubacterium genus and Rumphococcus in constipation using weighted median, MR Egger, simple mode, inverse variance weighted (IVW), and weighted mode. Finally, we did a sensitivity analysis that included a heterogeneity, horizontal pleiotropy, and Leave-One-Out (LOO) test to examine the viability of the MR data.

Results

The SVMR revealed that the Eubacterium genus and Rumphococcus were causally connected to constipation, with Rumphococcus (P = 0.042, OR = 1.074) as a hazardous factor and Eubacterium genus (P = 0.004, OR = 0.909) as a safety factor. Sensitivity tests then revealed the absence of variability between the constipation and the exposure factors (Eubacterium genus and Rumphococcus). Additionally, there were no other confounding factors and the examined SNPs could only influence constipation through the aforementioned exposure factors, respectively. As a result, the MR results were fairly robust.

Conclusion

Our investigation verified the causal links between the Eubacterium genus or Rumphococcus, and constipation, with greater Rumphococcus expression increasing the likelihood of constipation and the opposite being true for the Eubacterium genus.

Microbiota gut-brain axis: implications for pediatric-onset leukodystrophies

Neurodegenerative disorders are a group of diseases characterized by progressive degeneration of the nervous system, leading to a gradual loss of previously acquired motor, sensory and/or cognitive functions. Leukodystrophies are amongst the most frequent childhood-onset neurodegenerative diseases and primarily affect the white matter of the brain, often resulting in neuro-motor disability. Notably, gastrointestinal (GI) symptoms and complications, such as gastroesophageal reflux disease (GERD) and dysphagia, significantly impact patients' quality of life, highlighting the need for comprehensive management strategies. Gut dysbiosis, characterized by microbial imbalance, has been implicated in various GI disorders and neurodegenerative diseases. This narrative review explores the intricate relationship between GI symptoms, Gut Microbiota (GM), and neurodegeneration. Emerging evidence underscores the profound influence of GM on neurological functions via the microbiota gut-brain axis. Animal models have demonstrated alterations in GM composition associated with neuroinflammation and neurodegeneration. Our single-centre experience reveals a high prevalence of GI symptoms in leukodystrophy population, emphasizing the importance of gastroenterological assessment and nutritional intervention in affected children. The bidirectional relationship between GI disorders and neurodegeneration suggests a potential role of gut dysbiosis in disease progression. Prospective studies investigating the GM in leukodystrophies are essential to understand the role of gut-brain axis dysfunction in disease progression and identify novel therapeutic targets. In conclusion, elucidating the interplay between GI disorders, GM, and neurodegeneration holds promise for precision treatments aimed at improving patient outcomes and quality of life.

Crisis in the gut: navigating gastrointestinal challenges in Gulf War Illness with bioengineering

Gulf War Illness (GWI) is characterized by a wide range of symptoms that manifests largely as gastrointestinal symptoms. Among these gastrointestinal symptoms, motility disorders are highly prevalent, presenting as chronic constipation, stomach pain, indigestion, diarrhea, and other conditions that severely impact the quality of life of GWI veterans. However, despite a high prevalence of gastrointestinal impairments among these veterans, most research attention has focused on neurological disturbances. This perspective provides a comprehensive overview of current in vivo research advancements elucidating the underlying mechanisms contributing to gastrointestinal disorders in GWI. Generally, these in vivo and in vitro models propose that neuroinflammation alters gut motility and drives the gastrointestinal symptoms reported in GWI. Additionally, this perspective highlights the potential and challenges of in vitro bioengineering models, which could be a crucial contributor to understanding and treating the pathology of gastrointestinal related-GWI.

Acupuncture influences multiple diseases by regulating gut microbiota

Acupuncture, an important green and side effect-free therapy in traditional Chinese medicine, is widely use both domestically and internationally. Acupuncture can interact with the gut microbiota and influence various diseases, including metabolic diseases, gastrointestinal diseases, mental disorders, nervous system diseases, and other diseases. This review presents a thorough analysis of these interactions and their impacts and examines the alterations in the gut microbiota and the potential clinical outcomes following acupuncture intervention to establish a basis for the future utilization of acupuncture in clinical treatments.

Application of In Vitro Digestion Models in the Evaluation of Dietary Supplements

Nowadays, dietary supplements are a permanent part of our diet. Using various simulated in vitro digestive models, the bioavailability of dietary supplement ingredients has also been investigated. In most cases, static models are used instead of dynamic ones. This article focuses on the division of applications of in vitro methods, such as assessing the quality of dietary supplements (in chemical and pharmaceutical form), the impact of diet on the assessment of the bioavailability of product ingredients, the impact of supplement ingredients on the state of intestinal microflora, and the development of new products using various encapsulation methods. The review included publications from 2000 to 2024 showing the use of in vitro methods in dietary supplements containing polysaccharides, proteins, elements, vitamins, and bioactive substances, as well as probiotic and prebiotic products. The impact of components in dietary supplements on the human digestive tract and their degree of bioaccessibility were determined through the use of in vitro methods. The application of in vitro methods has also become an effective tool for designing new forms of dietary supplements in order to increase the availability and durability of labile ingredients in these products.

Coffee and Parkinson's disease

Parkinson's disease (PD) is a prevalent neurodegenerative disease marked by dopaminergic neuronal loss and misfolded alpha-synuclein (α-syn) accumulation, which results in both motor and cognitive symptoms. Its occurrence grows with age, with a larger prevalence among males. Despite substantial study, effective medicines to reduce or stop the progression of diseases remain elusive. Interest has grown in examining dietary components, such as caffeine present in coffee, for potential medicinal effects. Epidemiological studies imply a lower incidence of PD with coffee drinking, attributable to caffeine's neuroprotective abilities. Beyond caffeine, coffee constituent like chlorogenic acid and cafestol have anti-Parkinsonian benefits. Moreover, coffee use has been related with variations in gut microbiota composition, which may reduce intestinal inflammation and prevent protein misfolding in enteric nerves, perhaps through the microbiota-gut-brain axis. This review gives a summary of the neuroprotective effects of coffee, investigating both its motor and non-motor advantages in individuals with PD as well as in experimental models of PD. We reviewed some bioactive constituents of coffee, their respective interactions with misfolded α-syn accumulation, and its emerging mechanisms associated to the gut microbiome.

CFP/Yit: An Inbred Mouse Strain with Slow Gastrointestinal Transit

BACKGROUND

Gastrointestinal transit (GIT) is influenced by factors including diet, medications, genetics, and gut microbiota, with slow GIT potentially indicating a functional disorder linked to conditions, such as constipation. Although GIT studies have utilized various animal models, few effectively model spontaneous slow GIT.

AIMS

We aimed to characterize the GIT phenotype of CFP/Yit (CFP), an inbred mouse strain with suggested slow GIT.

METHODS

Female and male CFP mice were compared to Crl:CD1 (ICR) mice in GIT and assessed based on oral gavage of fluorescent-labeled 70-kDa dextran, feed intake, fecal amount, and fecal water content. Histopathological analysis of the colon and analysis of gut microbiota were conducted.

RESULTS

CFP mice exhibited a shorter small intestine and a 1.4-fold longer colon compared to ICR mice. The median whole-GIT time was 6.0-fold longer in CFP mice than in ICR mice. CFP mice demonstrated slower gastric and cecal transits than ICR mice, with a median colonic transit time of 4.1 h (2.9-fold longer). CFP mice exhibited lower daily feed intakes and fecal amounts. Fecal water content was lower in CFP mice, apparently attributed to the longer colon. Histopathological analysis showed no changes in CFP mice, including tumors or inflammation. Moreover, CFP mice had a higher Firmicutes/Bacteroidota ratio and a relative abundance of Erysipelotrichaceae in cecal and fecal contents.

CONCLUSIONS

This study indicates that CFP mice exhibit slow transit in the stomach, cecum, and colon. As a novel mouse model, CFP mice can contribute to the study of gastrointestinal physiology and disease.

Revitalizing the Gut Microbiome in Chronic Kidney Disease: A Comprehensive Exploration of the Therapeutic Potential of Physical Activity

Both physical inactivity and disruptions in the gut microbiome appear to be prevalent in patients with chronic kidney disease (CKD). Engaging in physical activity could present a novel nonpharmacological strategy for enhancing the gut microbiome and mitigating the adverse effects associated with microbial dysbiosis in individuals with CKD. This narrative review explores the underlying mechanisms through which physical activity may favorably modulate microbial health, either through direct impact on the gut or through interorgan crosstalk. Also, the development of microbial dysbiosis and its interplay with physical inactivity in patients with CKD are discussed. Mechanisms and interventions through which physical activity may restore gut homeostasis in individuals with CKD are explored.

Gastrointestinal Dysmotility Predisposes to Colitis through Regulation of Gut Microbial Composition and Linoleic Acid Metabolism

Disrupted gastrointestinal (GI) motility is highly prevalent in patients with inflammatory bowel disease (IBD), but its potential causative role remains unknown. Herein, the role and the mechanism of impaired GI motility in colitis pathogenesis are investigated. Increased colonic mucosal inflammation is found in patients with chronic constipation (CC). Mice with GI dysmotility induced by genetic mutation or chemical insult exhibit increased susceptibility to colitis, dependent on the gut microbiota. GI dysmotility markedly decreases the abundance of Lactobacillus animlalis and increases the abundance of Akkermansia muciniphila. The reduction in L. animlalis, leads to the accumulation of linoleic acid due to compromised conversion to conjugated linoleic acid. The accumulation of linoleic acid inhibits Treg cell differentiation and increases colitis susceptibility via inducing macrophage infiltration and proinflammatory cytokine expression in macrophage. Lactobacillus and A. muciniphila abnormalities are also observed in CC and IBD patients, and mice receiving fecal microbiota from CC patients displayed an increased susceptibility to colitis. These findings suggest that GI dysmotility predisposes host to colitis development by modulating the composition of microbiota and facilitating linoleic acid accumulation. Targeted modulation of microbiota and linoleic acid metabolism may be promising to protect patients with motility disorder from intestinal inflammation.

A guide to germ-free and gnotobiotic mouse technology to study health and disease

The intestinal microbiota has major influence on human physiology and modulates health and disease. Complex host-microbe interactions regulate various homeostatic processes, including metabolism and immune function, while disturbances in microbiota composition (dysbiosis) are associated with a plethora of human diseases and are believed to modulate disease initiation, progression and therapy response. The vast complexity of the human microbiota and its metabolic output represents a great challenge in unraveling the molecular basis of host-microbe interactions in specific physiological contexts. To increase our understanding of these interactions, functional microbiota research using animal models in a reductionistic setting are essential. In the dynamic landscape of gut microbiota research, the use of germ-free and gnotobiotic mouse technology, in which causal disease-driving mechanisms can be dissected, represents a pivotal investigative tool for functional microbiota research in health and disease, in which causal disease-driving mechanisms can be dissected. A better understanding of the health-modulating functions of the microbiota opens perspectives for improved therapies in many diseases. In this review, we discuss practical considerations for the design and execution of germ-free and gnotobiotic experiments, including considerations around germ-free rederivation and housing conditions, route and timing of microbial administration, and dosing protocols. This comprehensive overview aims to provide researchers with valuable insights for improved experimental design in the field of functional microbiota research.

Protease-Induced Excitation of Dorsal Root Ganglion Neurons in Response to Acute Perturbation of the Gut Microbiota Is Associated With Visceral and Somatic Hypersensitivity

BACKGROUND & AIMS

Abdominal pain is a major symptom of diseases that are associated with microbial dysbiosis, including irritable bowel syndrome and inflammatory bowel disease. Germ-free mice are more prone to abdominal pain than conventionally housed mice, and reconstitution of the microbiota in germ-free mice reduces abdominal pain sensitivity. However, the mechanisms underlying microbial modulation of pain remain elusive. We hypothesized that disruption of the intestinal microbiota modulates the excitability of peripheral nociceptive neurons.

METHODS

In vivo and in vitro assays of visceral sensation were performed on mice treated with the nonabsorbable antibiotic vancomycin (50 μg/mL in drinking water) for 7 days and water-treated control mice. Bacterial dysbiosis was verified by 16s rRNA analysis of stool microbial composition.

RESULTS

Treatment of mice with vancomycin led to an increased sensitivity to colonic distension in vivo and in vitro and hyperexcitability of dorsal root ganglion (DRG) neurons in vitro, compared with controls. Interestingly, hyperexcitability of DRG neurons was not restricted to those that innervated the gut, suggesting a widespread effect of gut dysbiosis on peripheral pain circuits. Consistent with this, mice treated with vancomycin were more sensitive than control mice to thermal stimuli applied to hind paws. Incubation of DRG neurons from naive mice in serum from vancomycin-treated mice increased DRG neuron excitability, suggesting that microbial dysbiosis alters circulating mediators that influence nociception. The cysteine protease inhibitor E64 (30 nmol/L) and the protease-activated receptor 2 (PAR-2) antagonist GB-83 (10 μmol/L) each blocked the increase in DRG neuron excitability in response to serum from vancomycin-treated mice, as did the knockout of PAR-2 in NaV1.8-expressing neurons. Stool supernatant, but not colonic supernatant, from mice treated with vancomycin increased DRG neuron excitability via cysteine protease activation of PAR-2.

CONCLUSIONS

Together, these data suggest that gut microbial dysbiosis alters pain sensitivity and identify cysteine proteases as a potential mediator of this effect.

Autism spectrum disorders and the gastrointestinal tract: insights into mechanisms and clinical relevance

Autism spectrum disorders (ASDs) are recognized as central neurodevelopmental disorders diagnosed by impairments in social interactions, communication and repetitive behaviours. The recognition of ASD as a central nervous system (CNS)-mediated neurobehavioural disorder has led most of the research in ASD to be focused on the CNS. However, gastrointestinal function is also likely to be affected owing to the neural mechanistic nature of ASD and the nervous system in the gastrointestinal tract (enteric nervous system). Thus, it is unsurprising that gastrointestinal disorders, particularly constipation, diarrhoea and abdominal pain, are highly comorbid in individuals with ASD. Gastrointestinal problems have also been repeatedly associated with increased severity of the core symptoms diagnostic of ASD and other centrally mediated comorbid conditions, including psychiatric issues, irritability, rigid-compulsive behaviours and aggression. Despite the high prevalence of gastrointestinal dysfunction in ASD and its associated behavioural comorbidities, the specific links between these two conditions have not been clearly delineated, and current data linking ASD to gastrointestinal dysfunction have not been extensively reviewed. This Review outlines the established and emerging clinical and preclinical evidence that emphasizes the gut as a novel mechanistic and potential therapeutic target for individuals with ASD.

Lactobacillus plantarum 24-7 improves postoperative bloating and hard stools by modulating intestinal microbiota in patients with congenital heart disease: a randomized controlled trial

Gastrointestinal symptoms are a common postoperative complication in patients with congenital heart disease (CHD), affecting their postoperative recovery. Probiotic intervention may be a promising therapeutic approach to alleviate postoperative gastrointestinal symptoms. This study aimed to evaluate the potential of Lactobacillus plantarum 24-7 (L. plantarum 24-7) in mitigating postoperative gastrointestinal symptoms and promoting patient recovery. Adult CHD patients scheduled for surgical intervention were recruited. One hundred and twenty patients were randomized and received L. plantarum or placebo intervention twice daily for ten days. Gastrointestinal symptoms were assessed utilizing the Gastrointestinal Symptom Rating Scale (GSRS). Various postoperative variables were analyzed across both groups. Alterations in gut microbiota were evaluated through 16S rRNA sequencing. 112 patients completed the study, with 55 in the probiotic group and 57 in the placebo group. While the disparity in overall postoperative GSRS scores between the two groups did not reach statistical significance (P = 0.067), marked differences were observed in bloating (P = 0.004) and hard stool (P = 0.030) scores. Furthermore, individuals within the probiotic group exhibited lower postoperative neutrophil counts (P = 0.007) and concurrently higher lymphocyte counts (P = 0.001). Variations in the diversity and composition of postoperative gut microbiota were discerned between the probiotic and placebo groups. Remarkably, no probiotic-related adverse events were documented. Supplementation with L. plantarum was well-tolerated and demonstrated partial efficacy in ameliorating gastrointestinal symptoms in postoperative CHD patients. Modulating the gut microbiota may be a potential mechanism by which L. plantarum exerts clinical benefits.

Torreya grandis Kernel Oil Alleviates Loperamide-Induced Slow Transit Constipation via Up-Regulating the Colonic Expressions of Occludin/Claudin-1/ZO-1 and 5-HT3R/5-HT4R in BALB/c Mice

SCOPE

Torreya grandis kernel has traditionally been used to remove intestinal parasites and increases intestinal motility. However, the effect of Torreya grandis kernel oil (TKO) on constipation has not yet been investigated. Therefore, mouse model is used to investigate the effect of TKO on slow transit constipation (STC) and its possible mechanism.

METHODS AND RESULTS

The effects of TKO on intestinal motility of STC mice are evaluated by fecal weight, fecal water content, colon length, defecation test, and intestinal propulsion test. The mechanism of TKO alleviating STC is explored by detecting biochemical analysis, histological analysis, western blot, qRT-PCR, immunohistochemistry, and gut microbiota analysis. The results reveal that TKO effectively promotes defecation and intestinal motility, increases the level of endothelin-1, and restores the histopathological morphology of the colon under LOP pretreatment. The expression levels of occludin, claudin-1, and zonula occludens-1 (ZO-1) mRNA and protein are up-regulated in mice receiving TKO treatment. The colonic 5-hydroxytryptamine 3R/4R (5-HT3R/5-HT4R) expressions are also increased by TKO supplementation. Additionally, TKO rescues LOP-caused disorders of the gut microbiota.

CONCLUSION

Consumption of TKO is beneficial to STC recovery, and it can alleviate LOP-induced STC by up-regulating the colonic expressions of Occludin/Claudin-1/ZO-1 and 5-HT3R/5-HT4R.

Dietary fiber (oligosaccharide and non-starch polysaccharide) in preventing and treating functional gastrointestinal disorders - Challenges and controversies: A review

Functional gastrointestinal disorders (FGIDs) are a group of chronic or recurrent gastrointestinal functional diseases, including functional dyspepsia, irritable bowel syndrome, and functional constipation. A lack of safe and reliable treatments for abdominal pain-related FGIDs has prompted interest in new therapies. Evidence has shown that supplementation with dietary fiber may help treat FGIDs. Dietary fibers (DFs) have been demonstrated to have regulatory effects on the gut microbiota, microbiota metabolites, and gastrointestinal movement and have important implications for preventing and treating FGIDs. However, the adverse effects of some DFs, such as fermentable oligosaccharides, on FGIDs are unclear. This review provides an overview of the DFs physiological properties and functional characteristics that influence their use in management of FGIDs, with emphasis on structural modification technology to improve their therapeutic activities. The review highlights that the use of appropriate or novel fibers is a potential therapeutic approach for FGIDs.

Why do hosts malfunction without microbes? Missing benefits versus evolutionary addiction

Microbes are widely recognized to be vital to host health. This new consensus rests, in part, on experiments showing how hosts malfunction when microbes are removed. More and more microbial dependencies are being discovered, even in fundamental processes such as development, immunity, physiology, and behavior. But why do they exist? The default explanation is that microbes are beneficial; when hosts lose microbes, they also lose benefits. Here I call attention to evolutionary addiction, whereby a host trait evolves a need for microbes without having been improved by them. Evolutionary addiction should be considered when interpreting microbe-removal experiments, as it is a distinct and potentially common process. Further, it may have unique implications for the evolution and stability of host-microbe interactions.

Opioid trail: Tracking contributions to opioid use disorder from host genetics to the gut microbiome

Opioid use disorder (OUD) is a worldwide public health crisis with few effective treatment options. Traditional genetics and neuroscience approaches have provided knowledge about biological mechanisms that contribute to OUD-related phenotypes, but the complexity and magnitude of effects in the brain and body remain poorly understood. The gut-brain axis has emerged as a promising target for future therapeutics for several psychiatric conditions, so characterizing the relationship between host genetics and the gut microbiome in the context of OUD will be essential for development of novel treatments. In this review, we describe evidence that interactions between host genetics, the gut microbiome, and immune signaling likely play a key role in mediating opioid-related phenotypes. Studies in humans and model organisms consistently demonstrated that genetic background is a major determinant of gut microbiome composition. Furthermore, the gut microbiome is susceptible to environmental influences such as opioid exposure. Additional work focused on gene by microbiome interactions will be necessary to gain improved understanding of their effects on OUD-related behaviors.

5-HT4 Receptor is Protective for MPTP-induced Parkinson's Disease Mice Via Altering Gastrointestinal Motility or Gut Microbiota

Serotonergic dysfunction is related to both motor and nonmotor symptoms in Parkinson's disease (PD). As a 5-HT receptor, 5-HT4 receptor (5-HT4R) is well-studied and already-used in clinical therapy of constipation, which is a typical non-motor symptom in PD. In this study, we investigated the role of 5-HT4R as a regulator of gut function in MPTP-induced acute PD mice model. Daily intraperitoneal injection of GR 125487 (5-HT4R antagonist) was administered 3 days before MPTP treatment until sacrifice. Seven days post-MPTP treatment, feces were collected and gastrointestinal transit time (GITT) was measured, 8 days post-MPTP treatment, behavioral tests were performed, and then animals were sacrificed for the further analysis. We found GR 125487 pretreatment not only increased GITT, but also aggravated MPTP-induced motor bradykinesia. In addition, GR 125487 pretreatment exacerbated the loss of dopaminergic neurons probably by suppressing JAK2/PKA/CREB signaling pathway and increased reactive glia and neuroinflammation in the striatum. 16 S rRNA sequencing of fecal microbiota showed that GR 125487 pretreatment altered the composition of gut microbiota, in which the abundance of Akkermansia muciniphila and Clostridium clostridioforme was increased, whereas that of Parabacteroides distasonis and Bacteroides fragilis was decreased, which are closely associated with inflammation condition. Taken together, we demonstrated that GR 125487 pretreatment exacerbates MPTP-induced striatal neurodegenerative processes possibly via the JAK2/PKA/CREB pathway and neuroinflammation by altering gut microbiota composition. In the microbiota-gut-brain axis of PD, 5-HT4R should be further explored and might serve as a target for PD diagnosis and treatment.

Insights into the Current and Possible Future Use of Opioid Antagonists in Relation to Opioid-Induced Constipation and Dysbiosis

Opioid receptor agonists, particularly those that activate µ-opioid receptors (MORs), are essential analgesic agents for acute or chronic mild to severe pain treatment. However, their use has raised concerns including, among others, intestinal dysbiosis. In addition, growing data on constipation-evoked intestinal dysbiosis have been reported. Opioid-induced constipation (OIC) creates an obstacle to continuing treatment with opioid analgesics. When non-opioid therapies fail to overcome the OIC, opioid antagonists with peripheral, fast first-pass metabolism, and gastrointestinal localized effects remain the drug of choice for OIC, which are discussed here. At first glance, their use seems to only be restricted to constipation, however, recent data on OIC-related dysbiosis and its contribution to the appearance of several opioid side effects has garnered a great of attention from researchers. Peripheral MORs have also been considered as a future target for opioid analgesics with limited central side effects. The properties of MOR antagonists counteracting OIC, and with limited influence on central and possibly peripheral MOR-mediated antinociception, will be highlighted. A new concept is also proposed for developing gut-selective MOR antagonists to treat or restore OIC while keeping peripheral antinociception unaffected. The impact of opioid antagonists on OIC in relation to changes in the gut microbiome is included.

Microbiota-dependent early life programming of gastrointestinal motility

Gastrointestinal microbes modulate peristalsis and stimulate the enteric nervous system (ENS), whose development, as in the central nervous system (CNS), continues into the murine postweaning period. Given that adult CNS function depends on stimuli received during critical periods of postnatal development, we hypothesized that adult ENS function, namely motility, depends on microbial stimuli during similar critical periods. We gave fecal microbiota transplantation (FMT) to germ-free mice at weaning or as adults and found that only the mice given FMT at weaning recovered normal transit, while those given FMT as adults showed limited improvements. RNAseq of colonic muscularis propria revealed enrichments in neuron developmental pathways in mice exposed to gut microbes earlier in life, while mice exposed later - or not at all - showed exaggerated expression of inflammatory pathways. These findings highlight a microbiota-dependent sensitive period in ENS development, pointing to potential roles of the early life microbiome in later life dysmotility.

Anti-diarrheal drug loperamide induces dysbiosis in zebrafish microbiota via bacterial inhibition

BACKGROUND

Perturbations of animal-associated microbiomes from chemical stress can affect host physiology and health. While dysbiosis induced by antibiotic treatments and disease is well known, chemical, nonantibiotic drugs have recently been shown to induce changes in microbiome composition, warranting further exploration. Loperamide is an opioid-receptor agonist widely prescribed for treating acute diarrhea in humans. Loperamide is also used as a tool to study the impact of bowel dysfunction in animal models by inducing constipation, but its effect on host-associated microbiota is poorly characterized.

RESULTS

We used conventional and gnotobiotic larval zebrafish models to show that in addition to host-specific effects, loperamide also has anti-bacterial activities that directly induce changes in microbiota diversity. This dysbiosis is due to changes in bacterial colonization, since gnotobiotic zebrafish mono-colonized with bacterial strains sensitive to loperamide are colonized up to 100-fold lower when treated with loperamide. Consistently, the bacterial diversity of gnotobiotic zebrafish colonized by a mix of 5 representative bacterial strains is affected by loperamide treatment.

CONCLUSION

Our results demonstrate that loperamide, in addition to host effects, also induces dysbiosis in a vertebrate model, highlighting that established treatments can have underlooked secondary effects on microbiota structure and function. This study further provides insights for future studies exploring how common medications directly induce changes in host-associated microbiota. Video Abstract.

The cellular states and fates of shed intestinal cells

The intestinal epithelium is replaced every few days1. Enterocytes are shed into the gut lumen predominantly from the tips of villi2,3 and have been believed to rapidly die upon their dissociation from the tissue4,5. However, technical limitations prohibited studying the cellular states and fates of shed intestinal cells. Here we show that shed epithelial cells remain viable and upregulate distinct anti-microbial programmes upon shedding, using bulk and single-cell RNA sequencing of male mouse intestinal faecal washes. We further identify abundant shedding of immune cells, which is elevated in mice with dextran sulfate sodium-induced colitis. We find that faecal host transcriptomics reflect changes in the intestinal tissue following perturbations. Our study suggests potential functions of shed cells in the intestinal lumen and demonstrates that host cell transcriptomes in intestinal washes can be used to probe tissue states.

The epithelial transcriptome and mucosal microbiota are altered for goats fed with a low-protein diet

Introduction

Feeding low protein (LP) diet to animals impose severe challenge to animals' immune homeostasis. However, limited knowledge about the underlying adaption mechanism of host and ruminal microbiota responding to LP diet were well understood. Herein, this study was performed to examine the changes in relative abundance of ruminal microbiota and host ruminal mucosal transcriptome profiles in response to a LP diet.

Methods

A total of twenty-four female Xiangdong balck goats with similar weight (20.64 ± 2.40 kg) and age (8 ± 0.3 months) were randomly assigned into two groups, LP (5.52% crude protein containing diet) and CON (10.77% crude protein containing diet) groups. Upon completion of the trial, all goats were slaughtered after a 16-hour fasting period in LiuYang city (N 28°15', E 113°63') in China. HE staining, free amino acids measurement, transcriptome analysis and microbiome analysis were applied to detect the morphology alterations, free amino acids profile alterations and the shift in host ruminal mucosal transcriptome and ruminal microbiota communities.

Results

Firstly, the results showed that feeding LP diet to goats decreased the rumen papilla width (P = 0.043), surface area (P = 0.013) and total ruminal free amino acids concentration (P = 0.016). Secondly, microbiome analysis indicated that 9 microbial genera, including Eubacterium and Prevotella, were enriched in LP group while 11 microbial genera, including Butyrivibrio and Ruminococcus, were enriched in CON group. Finally, in terms of immune-related genes, the expression levels of genes involved in tight junction categories (e.g., MYH11, PPP2R2C, and MYL9) and acquired immunity (e.g., PCP4 and CXCL13) were observed to be upregulated in the LP group when compared to the CON group.

Conclusion

Under the LP diet, the rumen exhibited increased relative abundance of pathogenic microbiota and VFA-degrading microbiota, leading to disruptions in immune homeostasis within the host's ruminal mucosa. These findings indicate that the ruminal microbiota interacts with host results in the disruption in animals' immune homeostasis under LP diet challenge.

Electro-acupuncture promotes gut motility and alleviates functional constipation by regulating gut microbiota and increasing butyric acid generation in mice

OBJECTIVE

Abnormalities in the gut microbiota and intestinal short-chain fatty acid (SCFA) levels are implicated in the pathogenesis of functional constipation (FC). Electro-acupuncture (EA) has been shown to improve constipation-related symptoms and rebalance the gut microbiota. However, it is currently unknown whether the gut microbiota is a key mechanistic target for EA or how EA promotes gut motility by regulating the gut microbiota and SCFAs. Therefore, we assessed the effects of EA in FC mice and pseudo-germfree (PGF) mice to address these questions.

METHODS

Forty female Kunming mice were randomly separated into a normal control group (n = 8), an FC group (n = 8), an FC + EA group (n = 8), a PGF group (n = 8) and a PGF + EA group (n = 8). The FC group and FC + EA group were treated with diphenoxylate to establish the FC model; the PGF group and PGF + EA group were given an antibiotic cocktail to initiate the PGF model. After maintaining the model for 14 d, mice in the FC + EA and PGF + EA groups received EA stimulation at the ST25 and ST37 acupoints, once a day, 5 times per week, for 2 weeks. Fecal parameters and intestinal transit rate were calculated to assess the efficacy of EA on constipation and gastrointestinal motility. Colonic contents were used to quantify gut microbial diversity using 16S rRNA sequencing, and measure SCFA concentrations using gas chromatography-mass spectrometry.

RESULTS

EA significantly shortened the first black stool defecation time (P < 0.05) and increased the intestinal transit rate (P < 0.01), and fecal pellet number (P < 0.05), wet weight (P < 0.05) and water content (P < 0.01) over 8 h, compared with the FC group, showing that EA promoted gut motility and alleviated constipation. However, EA treatment did not reverse slow-transit colonic motility in PGF mice (P > 0.05), demonstrating that the gut microbiota may play a mechanistic role in the EA treatment of constipation. In addition, EA treatment restored the Firmicutes to Bacteroidetes ratio and significantly increased butyric acid generation in FC mice (P < 0.05), most likely due to the upregulation of Staphylococcaceae microorganisms (P < 0.01).

CONCLUSION

EA-mediated resolution of constipation occurs through rebalancing the gut microbiota and promoting butyric acid generation. Please cite this article as: Xu MM, Guo Y, Chen Y, Zhang W, Wang L, Li Y. Electro-acupuncture promotes gut motility and alleviates functional constipation by regulating gut microbiota and increasing butyric acid generation in mice. J Integr Med. 2023; Epub ahead of print.

Protective effect of L-pipecolic acid on constipation in C57BL/6 mice based on gut microbiome and serum metabolomic

BACKGROUND

Functional constipation (FC) in children affects their growth, development and quality of life. L-pipecolic acid (L-PA) was decreased in FC children based on gut microbiome and serum metabolomic. In this study, loperamide-induced constipation in mice was used to evaluate the effects of L-PA on constipated mice.

METHOD

26 FC and 28 healthy children were recruited. Stool samples and serum samples were subjected to 16S rDNA sequencing and ultra-performance liquid chromatography/quadrupole time of flight (UPLC-Q/TOF-MS) approach, respectively. A loperamide-induced mouse constipation model was developed, and all mice were randomly divided into control (Con), loperamide (Lop) and L-PA (Lop + L-PA) treatment groups (6 mice per group). The mice in the Lop + L-PA group were given L-PA (250 mg/kg, once a day) and loperamide; the Lop group was given loperamide for 1 week, and the Con group was given saline. The fecal parameters and intestinal motility of mice in each group were detected. serum 5-HT levels and colon 5-HT expression were detected by ELISA and immunohistochemistry, respectively; qRT-PCR was used to detect the expression of AQP3 and 5-HT4R mRNA in each group.

RESULTS

45 differential metabolites and 18 significantly different microbiota were found in FC children. The α and β diversity of gut microbiota in FC children was significantly reduced. Importantly, serum L-PA was significantly reduced in FC children. The KEGG pathway enrichment were mainly enriched in fatty acid biosynthesis, lysine degradation, and choline metabolism. L-PA was negatively associated with Ochrobactrum, and N6, N6, N6-trimethyl-l-lysine was positively associated with Phascolarcrobacterium. In addition, L-PA improved the fecal water content, intestinal transit rate, and increased the serum 5-HT levels in constipated mice. Moreover, L-PA increased the expression of 5-HT4R, reduced AQP3, and regulated constipation-associated genes.

CONCLUSIONS

Gut microbiota and serum metabolites were significantly altered in children with FC. The abundance of Phascolarctobacterium and Ochrobactrum and serum L-PA content were decreased in FC children. L-PA was found to alleviate the fecal water content, increase intestinal transit rate and the first black stool defecation time. L-PA improved constipation by increasing 5-HT and 5-HT4R expression while down-regulating AQP3 expression.

The diet-microbiota axis: a key regulator of intestinal permeability in human health and disease

The intestinal barrier orchestrates selective permeability to nutrients and metabolites while excluding noxious stimuli. Recent scientific advances establishing a causal role for the gut microbiota in human health outcomes have generated a resurgent interest toward intestinal permeability. Considering the well-established role of the gut barrier in protection against foreign antigens, there is mounting evidence for a causal link between gut permeability and the microbiome in regulating human health. However, an understanding of the dynamic host-microbiota interactions that govern intestinal barrier functions remains poorly defined. Furthermore, the system-level mechanisms by which microbiome-targeted therapies, such as probiotics and prebiotics, simultaneously promote intestinal barrier function and host health remain an area of active investigation. This review summarizes the recent advances in understanding the dynamics of intestinal permeability in human health and its integration with gut microbiota. We further summarize mechanisms by which probiotics/prebiotics influence the gut microbiota and intestinal barrier functions.

The postbiotic of hawthorn-probiotic ameliorating constipation caused by loperamide in elderly mice by regulating intestinal microecology

Background

Constipation is common gastrointestinal disorder with high prevalence and recurrence, making people suffering. However, the treatment for constipation remains ineffectual. We aimed to the study the effects and mechanisms of postbiotic of hawthorn-probiotic on loperamide modeled old KM mice.

Methods

Constipated mice were grouped and treated with 10% lactulose (Y), hawthorn group (S), probiotic group (F) and postbiotic of hawthorn-probiotic (FS). Fecal changes were observed. AQP3 and Enac-γ were measured by RT-qPCR and Western blotting, intestinal barrier by H&amp;E and immunofluorescence staining, cell proliferation and apoptosis by CCK8 and flow cytometry. Gut microbiota was further determined by 16 s rRNA sequence of feces.

Results

Postbiotic of hawthorn-probiotic improved intestinal movement and pathomorphology, elevated AQP3, Enac-γ and mucin-2 expression, accompanied by decreased serum TNF-α and cell apoptosis, but increased proliferation. Furthermore, it modified the gut microbiota of constipated mice, featured by upregulation of Lactobacillaceae.

Conclusion

Postbiotic of hawthorn-probiotic relieved constipation by combined effects of regulating intestinal water and sodium metabolism, maintain intestinal barrier and gut microflora.

Graphical Abstract

Nicotinamide Riboside Improves Enteric Neuropathy in Streptozocin-Induced Diabetic Rats Through Myenteric Plexus Neuroprotection

BACKGROUND

Diabetes Mellitus causes a systemic oxidative stress due in part to the hyperglycemia and the reactive oxygen species generated. Up to 75% of diabetic patients present with an autonomic neuropathy affecting the Enteric Nervous System. Deficits in the human population are chronic dysmotilities with either increased (i.e., constipation) or decreased (i.e., diarrhea) total gastrointestinal transit times. These are recapitulated in the streptozocin-induced diabetic rat, which is a model of Type I Diabetes Mellitus.

AIMS

Examine the effects that a precursor of nicotinamide adenosine dinucleotide (NAD), nicotinamide riboside (NR), had on the development of dysmotility in induced diabetic rats and if fecal microbiota transplant (FMT) could produce the same results.

MATERIALS AND METHODS

Utilizing a 6-week treatment paradigm, NR was administered intraperitoneally every 48 h. Total gastrointestinal transit time was assessed weekly utilizing the carmine red method. Three weeks following hyperglycemic induction, FMT was performed between NR-treated animals and untreated animals.

SIGNIFICANT RESULTS

There is improvement in overall gastrointestinal transit time with the use of NR. 16S microbiome sequencing demonstrated decreased alpha and beta diversity in induced diabetic rats without change in animals receiving FMT. Improvements in myenteric plexus ganglia density in small and large intestines in diabetic animals treated with NR were seen.

CONCLUSIONS

NR treatment led to functional improvement in total gastrointestinal transit time in induced diabetic animals. This was associated with neuroprotection in the myenteric plexuses of both small and large intestines of induced diabetic rats. This represents an important first step in showing NR's benefit as a treatment for diabetic enteric neuropathy. Streptozocin-induced diabetic rats have improved transit times and increased myenteric plexus ganglia density when treated with intraperitoneal nicotinamide riboside.

Cinnamic acid regulates the intestinal microbiome and short-chain fatty acids to treat slow transit constipation

BACKGROUND

Slow transit constipation (STC) is a disorder with delayed colonic transit. Cinnamic acid (CA) is an organic acid in natural plants, such as Radix Scrophulariae (Xuan Shen), with low toxicity and biological activities to modulate the intestinal microbiome.

AIM

To explore the potential effects of CA on the intestinal microbiome and the primary endogenous metabolites-short-chain fatty acids (SCFAs) and evaluate the therapeutic effects of CA in STC.

METHODS

Loperamide was applied to induce STC in mice. The treatment effects of CA on STC mice were assessed from the 24 h defecations, fecal moisture and intestinal transit rate. The enteric neurotransmitters: 5-hydroxytryptamine (5-HT) and vasoactive intestinal peptide (VIP) were determined by the enzyme-linked immunosorbent assay. Hematoxylin-eosin and Alcian blue and Periodic acid Schiff staining were used to evaluate intestinal mucosa's histopathological performance and secretory function. 16S rDNA was employed to analyze the composition and abundance of the intestinal microbiome. The SCFAs in stool samples were quantitatively detected by gas chromatography-mass spectrometry.

RESULTS

CA ameliorated the symptoms of STC and treated STC effectively. CA ameliorated the infiltration of neutrophils and lymphocytes, increased the number of goblet cells and acidic mucus secretion of the mucosa. In addition, CA significantly increased the concentration of 5-HT and reduced VIP. CA significantly improved the diversity and abundance of the beneficial microbiome. Furthermore, the production of SCFAs [including acetic acid (AA), butyric acid (BA), propionic acid (PA) and valeric acid (VA)] was significantly promoted by CA. The changed abundance of Firmicutes, Akkermansia, Lachnoclostridium, Monoglobus, UCG.005, Paenalcaligenes, Psychrobacter and Acinetobacter were involved in the production of AA, BA, PA and VA.

CONCLUSION

CA could treat STC effectively by ameliorating the composition and abundance of the intestinal microbiome to regulate the production of SCFAs.

Microbiome and metabolome reveal the metabolic and microbial variations induced by depression and constipation

BACKGROUND

Depressed patients are often accompanied with constipation symptoms, and vice versa. However, the underlying mechanisms of such a bidirectional correlation have remained elusive. We aim to reveal the possible correlations between depression and constipation from the perspectives of gut microbiome and plasma metabolome.

METHODS

We constructed the depressed model and the constipated model of rats, respectively. First, we measured the locomotor activity status and the gastrointestinal functions of rats. And then, nuclear magnetic resonance plasma metabolomics was applied to reveal the shared and the unique metabolites of depression and constipation. In addition, 16 S ribosomal RNA gene sequencing was used to detect the impacts of constipation and depression on gut microbiota of rats. Finally, a multiscale and multifactorial network, that is, the 'phenotypes - differential metabolites - microbial biomarkers' integrated network, was constructed to visualise the mechanisms of connections between depression and constipation.

RESULTS

We found that spontaneous locomotor activity and gastrointestinal functions of both depressed rats and constipated rats significantly decreased. Further, eight metabolites and 14 metabolites were associated depression and constipation, respectively. Among them, seven metabolites and four metabolic pathways were shared by constipation and depression, mainly perturbing energy metabolism and amino acid metabolism. Additionally, depression and constipation significantly disordered the functions and the compositions of gut microbiota of rats, and decreased the ratio of Firmicutes to Bacteroidetes.

CONCLUSION

The current findings provide multiscale and multifactorial perspectives for understanding the correlations between depression and constipation, and demonstrate new mechanisms of comorbidity of depression and constipation.

Twin-bioengine self-adaptive micro/nanorobots using enzyme actuation and macrophage relay for gastrointestinal inflammation therapy

A wide array of biocompatible micro/nanorobots are designed for targeted drug delivery and precision therapy largely depending on their self-adaptive ability overcoming complex barriers in vivo. Here, we report a twin-bioengine yeast micro/nanorobot (TBY-robot) with self-propelling and self-adaptive capabilities that can autonomously navigate to inflamed sites for gastrointestinal inflammation therapy via enzyme-macrophage switching (EMS). Asymmetrical TBY-robots effectively penetrated the mucus barrier and notably enhanced their intestinal retention using a dual enzyme-driven engine toward enteral glucose gradient. Thereafter, the TBY-robot was transferred to Peyer's patch, where the enzyme-driven engine switched in situ to macrophage bioengine and was subsequently relayed to inflamed sites along a chemokine gradient. Encouragingly, EMS-based delivery increased drug accumulation at the diseased site by approximately 1000-fold, markedly attenuating inflammation and ameliorating disease pathology in mouse models of colitis and gastric ulcers. These self-adaptive TBY-robots represent a safe and promising strategy for the precision treatment of gastrointestinal inflammation and other inflammatory diseases.

Soluble dietary fiber and cellulose from Saccharina japonica by-product ameliorate Loperamide-induced constipation via modulating enteric neurotransmitters, short-chain fatty acids and gut microbiota

The effects of soluble dietary fiber (SDF) and cellulose (IDF) from Saccharina japonica by-product and their differences in improving constipation were further clarified in the present study. We demonstrated that SDF was mainly made up of d-mannuronic acid and d-mannose while IDF consisted of d-glucose , which is different from other reported dietary fibers of terrestrial plants. In this research, both SDF and IDF improved fecal-related indicators, gastrointestinal transit rate and histological morphology in Lop-induced mice. Moreover, they could increase the level of antioxidant enzymes (SOD and GSH-Px), restore the expression of enteric neurotransmitters, and maintain the function of ZO-1, JAM-1 as well as Occludin. Interestingly, SDF and IDF had a significant up-regulated effect on the proportion of Muribaculacea, Prevotellaceaen and Lachnospiraceae, which are critical to preserving intestinal immune homeostasis. Besides, they promoted the biosynthesis of short-chain fatty acids (SCFAs). The overall index showed that SDF is more effective for constipation due to its better water retention capacity. Thus, they can be used as a safe dietary supplement for the treatment of chronic or occasional constipation in humans.

Alleviation of loperamide-induced constipation with sticky rice fermented huangjiu by the regulation of serum neurotransmitters and gut microbiota

BACKGROUND

Huangjiu is an important component of traditional fermented food. It is produced by cereal fermentation. Sticky rice fermented huangjiu is an abundant source of polysaccharides, oligosaccharides, proteins, amino acids, and flavor compounds (POPAF), and it has been used as a dietary supplement and pharmaceutical ingredient. The purpose of this study is to explore the alleviation of constipation using sticky rice fermented huangjiu, with the aim of providing a basis for the nutritional treatment of constipation.

RESULTS

Sticky rice fermented huangjiu was more effective in the alleviation of constipation than same concentration of ethanol treatment on serum neurotransmitters, gut microbiota, and intestinal metabolites in this 17 days constipation mouse model. Compared with ethanol treatment, the administration of sticky rice fermented huangjiu to constipated mice increased gastrointestinal motility. It alleviated the decrease in motilin (27.94%), substance P (13.85%), gastrin (63.46%), 5-hydroxytryptamine (4.55%), and short-chain fatty acid (19.80%) levels, and alleviated the increase in somatostatin levels (9.54%). Furthermore, the administration of sticky rice fermented huangjiu regulated the microbiota-mediated gut ecology through alterations in the characteristic taxa.

CONCLUSION

The results reveal that sticky rice fermented huangjiu may alleviate loperamide-induced constipation by the regulation of serum neurotransmitters and gut microbiota. These findings reveal that huangjiu is endowed with many functional components by cereal fermentation, and the bioactive substances in huangjiu can be separated and applied for medical treatment or diet therapy in the future. © 2022 Society of Chemical Industry.

Alterations in fecal β-defensin-3 secretion as a marker of instability of the gut microbiota

Compositional changes in the microbiota (dysbiosis) may be a basis for Irritable Bowel Syndrome (IBS), but biomarkers are currently unavailable to direct microbiota-directed therapy. We therefore examined whether changes in fecal β-defensin could be a marker of dysbiosis in a murine model. Experimental dysbiosis was induced using four interventions relevant to IBS: a mix of antimicrobials, westernized diets (high-fat/high-sugar and high salt diets), or mild restraint stress. Fecal mouse β-defensin-3 and 16S rRNA-based microbiome profiles were assessed at baseline and during and following these interventions. Each intervention, except for mild restraint stress, altered compositional and diversity profiles of the microbiota. Exposure to antimicrobials or a high-fat/high-sugar diet, but not mild restraint stress, resulted in decreased fecal β-defensin-3 compared to baseline. In contrast, exposure to the high salt diet increased β-defensin-3 compared to baseline. Mice exposed to the mix of antimicrobials showed the largest compositional changes and the most significant correlations between β-defensin-3 levels and bacterial diversity. The high salt diet was also associated with significant correlations between changes in β-defensin-3 and bacterial diversity, and this was not accompanied by discernible inflammatory changes in the host. Thus, dietary change or antimicrobial exposure, both recognized factors in IBS exacerbations, induced marked dysbiosis that was accompanied by changes in fecal β-defensin-3 levels. We propose that serial monitoring of fecal β-defensins may serve as a marker of dysbiosis and help identify those IBS patients who may benefit from microbiota-directed therapeutic interventions.

Impact of exclusive enteral nutrition on the gut microbiome of children with medical complexity

BACKGROUND

Children with medical complexity (CMC) often require enteral tube feedings to meet their nutrition needs. Many, however, experience symptoms of feeding intolerance, such as vomiting and pain. The goal of this analysis was to examine the relationship between diet and the gut microbiome, controlling for medications, among CMC receiving enteral tube feedings, CMC consuming oral nutrition, and healthy controls. Given the variety of available commercial formula preparations, we were also interested in examining the impact of different formula types on the CMC microbiome.

METHODS

Fecal samples from 91 children (57 CMC and 34 healthy controls) were collected and analyzed. Parents completed clinical and dietary questionnaires. 16S ribosomal RNA amplicon sequencing was completed using the QIIME2 pipeline.

RESULTS

A significant decrease in alpha diversity among CMC receiving exclusive enteral nutrition (CMC EEN) compared with healthy controls (Shannon P = 0.006 and Faith's phylogenetic distance P = 0.006) was found that was not observed between CMC receiving oral nutrition and healthy controls. Significant differences in beta diversity were also observed between CMC EEN and healthy controls, with CMC EEN having a greater relative abundance of Enterobacteriaceae and obligate anaerobes. Differences were also noted between CMC EEN and CMC receiving oral nutrition (Aitchison distance P = 0.001); however, no differences were observed between CMC receiving oral nutrition and healthy controls.

CONCLUSION

Despite similarities in medication profiles, CMC EEN have decreased alpha diversity and differences in beta diversity compared with healthy controls not observed in CMC receiving oral nutrition, highlighting the impact of diet over medications.

Interactions between NSAIDs, opioids and the gut microbiota - Future perspectives in the management of inflammation and pain

The composition of intestinal microbiota is influenced by a number of factors, including medications, which may have a substantial impact on host physiology. Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics are among those widely used medications that have been shown to alter microbiota composition in both animals and humans. Although much effort has been devoted to identify microbiota signatures associated with these medications, much less is known about the underlying mechanisms. Mucosal inflammation, changes in intestinal motility, luminal pH and bile acid metabolism, or direct drug-induced inhibitory effect on bacterial growth are all potential contributors to NSAID- and opioid-induced dysbiosis, however, only a few studies have addressed directly these issues. In addition, there is a notable overlap between the microbiota signatures of these drugs and certain diseases in which they are used, such as spondyloarthritis (SpA), rheumatoid arthritis (RA) and neuropathic pain associated with type 2 diabetes (T2D). The aims of the present review are threefold. First, we aim to provide a comprehensive up-to-date summary on the bacterial alterations caused by NSAIDs and opioids. Second, we critically review the available data on the possible underlying mechanisms of dysbiosis. Third, we review the current knowledge on gut dysbiosis associated with SpA, RA and neuropathic pain in T2D, and highlight the similarities between them and those caused by NSAIDs and opioids. We posit that drug-induced dysbiosis may contribute to the persistence of these diseases, and may potentially limit the therapeutic effect of these medications by long-term use. In this context, we will review the available literature data on the effect of probiotic supplementation and fecal microbiota transplantation on the therapeutic efficacy of NSAIDs and opioids in these diseases.

Zebrafish: an efficient vertebrate model for understanding role of gut microbiota

Gut microbiota plays a critical role in the maintenance of host health. As a low-cost and genetically tractable vertebrate model, zebrafish have been widely used for biological research. Zebrafish and humans share some similarities in intestinal physiology and function, and this allows zebrafish to be a surrogate model for investigating the crosstalk between the gut microbiota and host. Especially, zebrafish have features such as high fecundity, external fertilization, and early optical transparency. These enable the researchers to employ the fish to address questions not easily addressed in other animal models. In this review, we described the intestine structure of zebrafish. Also, we summarized the methods of generating a gnotobiotic zebrafish model, the factors affecting its intestinal flora, and the study progress of gut microbiota functions in zebrafish. Finally, we discussed the limitations and challenges of the zebrafish model for gut microbiota studies. In summary, this review established that zebrafish is an attractive research tool to understand mechanistic insights into host-microbe interaction.

Stable isotope tracing in vivo reveals a metabolic bridge linking the microbiota to host histone acetylation

The gut microbiota influences acetylation on host histones by fermenting dietary fiber into butyrate. Although butyrate could promote histone acetylation by inhibiting histone deacetylases, it may also undergo oxidation to acetyl-coenzyme A (CoA), a necessary cofactor for histone acetyltransferases. Here, we find that epithelial cells from germ-free mice harbor a loss of histone H4 acetylation across the genome except at promoter regions. Using stable isotope tracing in vivo with 13C-labeled fiber, we demonstrate that the microbiota supplies carbon for histone acetylation. Subsequent metabolomic profiling revealed hundreds of labeled molecules and supported a microbial contribution to host fatty acid metabolism, which declined in response to colitis and correlated with reduced expression of genes involved in fatty acid oxidation. These results illuminate the flow of carbon from the diet to the host via the microbiota, disruptions to which may affect energy homeostasis in the distal gut and contribute to the development of colitis.

Human gut microbiota composition and its predicted functional properties in people with western and healthy dietary patterns

PURPOSE

Some dietary habits cluster together, and for this reason it is advised to study the impact of entire dietary patterns on human health, rather than that of individual dietary habits. The main objective of this study was to evaluate differences in gut microbiota composition and their predicted functional properties between people with a healthy (HDP) and western (WDP) dietary pattern.

METHODS

A cross-sectional, observational study was carried out on 200 participants enrolled 2017-2018 in Poznań, Poland, equally distributed into HDP and WDP groups. Diet was estimated using 3-day food records and information on stool transit times was collected. Fecal microbiota composition was assessed by 16S rRNA gene sequencing and its functional properties were predicted by the PICRUSt2 workflow.

RESULTS

The α-diversity did not differ between people with WDP and HDP, but β-diversity was associated with dietary pattern. People with HDP had higher relative abundances (RA) of Firmicutes and Faecalibacterium and lower RA of Bacteroidota and Escherichia-Shigella than participants with WDP. Only a small proportion of the variance in microbiota composition (1.8%) and its functional properties (2.9%) could be explained by dietary intake (legumes, simple sugars and their sources, like fruit, soft drinks) and stool transit characteristics.

CONCLUSION

Gut microbiota composition and predicted metabolic potential is shaped by overall diet quality as well as the frequency of defecation; however, the cumulative effect of these explain only a relatively low proportion of variance.

Constipation Mitigation by Rhubarb Extract in Middle-Aged Adults Is Linked to Gut Microbiome Modulation: A Double-Blind Randomized Placebo-Controlled Trial

Gut microbiota alterations are intimately linked to chronic constipation upon aging. We investigated the role of targeted changes in the gut microbiota composition in the relief of constipation symptoms after rhubarb extract (RE) supplementation in middle-aged volunteers. Subjects (95% women, average 58 years old) were randomized to three groups treated with RE at two different doses determined by its content of rhein (supplementation of 12.5 mg and 25 mg per day) vs. placebo (maltodextrin) for 30 days. We demonstrated that daily oral supplementation of RE for 30 days was safe even at the higher dose. Stool frequency and consistency, and perceived change in transit problem, transit speed and difficulty in evacuating, investigated by validated questionnaires, were improved in both groups of RE-treated volunteers compared to placebo. Higher abundance of Lachnospiraceae (mainly Roseburia and Agathobacter) only occurred after RE treatment when present at low levels at baseline, whereas an opposite shift in short-chain fatty acid (SCFA) levels was observed in both RE-treated groups (increase) and placebo (decrease). Fecal Lachnospiraceae and SCFA were positively correlated with stool consistency. This study demonstrates that RE supplementation promotes butyrate-producing bacteria and SCFA, an effect that could contribute to relieving chronic constipation in middle-aged persons.

The role of the gut microbiome in paediatric irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common and disabling condition in children. The pathophysiology of IBS is thought to be multifactorial but remains incompletely understood. There is growing evidence implicating the gut microbiome in IBS. Intestinal dysbiosis has been demonstrated in paediatric IBS cohorts; however, no uniform or consistent pattern has been identified. The exact mechanisms by which this dysbiosis contributes to IBS symptoms remain unknown. Available evidence suggests the imbalance produces a functional dysbiosis, with altered production of gases and metabolites that interact with the intestinal wall to cause symptoms, and enrichment or depletion of certain metabolic pathways. Additional hypothesised mechanisms include increased intestinal permeability, visceral hypersensitivity and altered gastrointestinal motility; however, these remain speculative in paediatric patients, with studies limited to animal models and adult populations. Interaction between dietary components and intestinal microbiota, particularly with fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs), has drawn increasing attention. FODMAPs have been found to trigger and worsen IBS symptoms. This is thought to be related to products of their fermentation by a dysbiotic microbial population, although this remains to be proven. A low-FODMAP diet has shown promising success in ameliorating symptoms in some but not all patients. There remains much to be discovered about the role of the dysbiotic microbiome in paediatric IBS.

The pathophysiology of major depressive disorder through the lens of systems biology: Network analysis of the psycho-immune-neuroendocrine physiome

BACKGROUND/AIMS

The psycho-immune-neuroendocrine (PINE) network is a predominantly physiological (metabolomic) model constructed from the literature, inter-linking multiple biological processes associated with major depressive disorder (MDD), thereby integrating putative mechanistic pathways for MDD into a single network.

MATERIAL AND METHODS

Previously published metabolomic pathways for the PINE network based on literature searches conducted in 1991-2021 were used to construct an edge table summarizing all physiological pathways in pairs of origin nodes and target nodes. The Gephi software program was used to calculate network metrics from the edge table, including total degree and centrality measures, to ascertain key network nodes and construct a directed network graph.

RESULTS

An edge table and directional network graph of physiological relationships in the PINE network is presented. The network has properties consistent with complex biological systems, with analysis yielding key network nodes comprising pro-inflammatory cytokines (TNF- α, IL6 and IL1), glucocorticoids and corticotropin releasing hormone (CRH). These may represent central structural and regulatory elements in the context of MDD.

CONCLUSION

The identified hubs have a high degree of connection and are known to play roles in the progression from health to MDD. These nodes represent strategic targets for therapeutic intervention or prevention. Future work is required to build a weighted and dynamic simulation of the network PINE.

Environmental Stressors and the PINE Network: Can Physical Environmental Stressors Drive Long-Term Physical and Mental Health Risks?

Both psychosocial and physical environmental stressors have been linked to chronic mental health and chronic medical conditions. The psycho-immune-neuroendocrine (PINE) network details metabolomic pathways which are responsive to varied stressors and link chronic medical conditions with mental disorders, such as major depressive disorder via a network of pathophysiological pathways. The primary objective of this review is to explore evidence of relationships between airborne particulate matter (PM, as a concrete example of a physical environmental stressor), the PINE network and chronic non-communicable diseases (NCDs), including mental health sequelae, with a view to supporting the assertion that physical environmental stressors (not only psychosocial stressors) disrupt the PINE network, leading to NCDs. Biological links have been established between PM exposure, key sub-networks of the PINE model and mental health sequelae, suggesting that in theory, long-term mental health impacts of PM exposure may exist, driven by the disruption of these biological networks. This disruption could trans-generationally influence health; however, long-term studies and information on chronic outcomes following acute exposure event are still lacking, limiting what is currently known beyond the acute exposure and all-cause mortality. More empirical evidence is needed, especially to link long-term mental health sequelae to PM exposure, arising from PINE pathophysiology. Relationships between physical and psychosocial stressors, and especially the concept of such stressors acting together to impact on PINE network function, leading to linked NCDs, evokes the concept of syndemics, and these are discussed in the context of the PINE network.

Direct and indirect mechanisms by which the gut microbiota influence host serotonin systems

Mounting evidence highlights the pivotal role of enteric microbes as a dynamic interface with the host. Indeed, the gut microbiota, located in the lumen of the gastrointestinal (GI) tract, influence many essential physiological processes that are evident in both healthy and pathological states. A key signaling molecule throughout the body is serotonin (5-hydroxytryptamine; 5-HT), which acts in the GI tract to regulate numerous gut functions including intestinal motility and secretion. The gut microbiota can modulate host 5-HT systems both directly and indirectly. Direct actions of gut microbes, evidenced by studies using germ-free animals or antibiotic administration, alter the expression of key 5-HT-related genes to promote 5-HT biosynthesis. Indirectly, the gut microbiota produce numerous microbial metabolites, whose actions can influence host serotonergic systems in a variety of ways. This review summarizes the current knowledge regarding mechanisms by which gut bacteria act to regulate host 5-HT and 5-HT-mediated gut functions, as well as implications for 5-HT in the microbiota-gut-brain axis.

Electroacupuncture reduces blood glucose by regulating intestinal flora in type 2 diabetic mice

BACKGROUND

The development of diabetes is closely related to the gut microbiota in recent studies, which can be influenced by intestinal motility. A few studies report that electroacupuncture (EA) can lower blood glucose. EA can promote colonic motility and influence gut microbes. In this study, we explored the effect of the EA on blood glucose level in mice with type 2 diabetes (T2D) and its mechanism.

METHODS

The T2D mice model, fecal microbiota transplantation mice model, and Kit^W/Wv mice model （Point mutation of mouse W locus encoding kit gene）were used to investigate the effect of EA on blood glucose as well as the mechanism; The blood glucose and insulin resistance level and the intestinal flora were evaluated. The level of intestinal junction protein, inflammatory cytokines in the serum, interstitial cells of Cajal content, and colonic motility were detected. Lastly, the IKKβ/NF-κB-JNK-IRS-1-AKT pathway was explored.

RESULTS

EA lowered the blood glucose level, altered the gut microbiota, and promoted colonic motility in T2D mice. EA-altered microbiota decreased the blood glucose level and insulin resistance in the antibiotics-treated diabetic mice. EA increased tight junction protein, lowered inflammatory factors, and regulated the IKKβ/NF-κB-JNK-IRS-1-AKT pathway in the liver and muscles. EA could not reduce the blood glucose and regulated gut microbiota in the Kit^W/Wv mice model.

CONCLUSIONS

EA promoted intestinal motility to regulate the intestinal flora, thereby reducing the level of systemic inflammation, and ultimately lowering the blood glucose by the IKKβ/NF-κB-JNK-IRS-1-AKT signal pathway.

Prevention of Loperamide-Induced Constipation in Mice and Alteration of 5-Hydroxytryotamine Signaling by Ligilactobacillus salivarius Li01

Although Ligilactobacillus salivarius Li01 (Li01) has shown much promise in preventing multiple gastrointestinal diseases, the potential of the probiotic in alleviating constipation and the related mechanisms remain unclear. In this study, the effects of Li01 were evaluated in a loperamide-induced constipation mouse model. The results demonstrated that Li01 intervention can relieve constipation symptoms by improving water content, quantity, and morphology of feces and act as an intestinal barrier structure protector. Furthermore, Li01 can modulate gut motility (gastrointestinal transit rate), the fluid transit-associated expression of aquaporins, and the serum parameters vasoactive intestinal peptide, substance P, and somatostatin. Constipation significantly increased the levels of 5-hydroxytryotamine (5-HT) in serum (p < 0.01) and decreased the levels in the intestine (p < 0.001). Due to its function of elevating the expression of tryptophan hydroxylase 1, this was reversed after Li01 treatment. Li01 also promoted the expression of 5-HT receptor 3 and 4, indicating that the 5-HT signaling pathway may play a critical role in the mechanism by which Li01 alleviate constipation symptoms. Additionally, Li01 significantly altered the gut microbiota composition by enhancing the ratio of Firmicutes/Bacteroidetes and increasing the abundance of Rikenellaceae_RC9 genera. Based on the above results, Li01 may have the potential to effectively alleviate constipation by regulating the 5-HT pathway and alteration of the gut microbiota.