Stress disrupts intestinal mucus barrier in rats via mucin O-glycosylation shift: prevention by a probiotic treatment

α2,6-linked sialylated oligosaccharides riched in goat milk alleviate food allergy by regulating the gut flora and mucin O-glycosylation

The nutritious goat milk has low allergenicity. Oligosaccharides represent one of the crucial functional constituents in goat milk, which are structurally similar to human milk oligosaccharides (HMOs). Currently, the anti-allergic activity of GMOs has not been reported. In this study, GMOs were efficiently separated into neutral (NGMOs) and sialylated (SGMOs) fractions, following by qualitative and quantitative analysis at the isomer level using online LC-MS/MS. Fifteen NGMOs and 28 SGMOs were detected in goat milk, with 10 SGMOs reported for the first time. Distinctly, α2,6-linked SGMOs were 3.9 times more abundant in goat milk than in bovine milk, with the total relative content of 6'SL, 3'SLN and 6'NGL in SGMOs approach to 60%, which is more similar to HMOs. Orally administering GMOs, especially α2,6-linked sialylated oligosaccharides, significantly alleviated food allergy in ovalbumin-induced BALB/c mice. SGMOs restored the balance of Lachnospiraceae, Erysipelotrichaceae, and Bacteroidaceae, reconstructed the intestinal mucosal barrier, especially restored the levels of fucosylation, sialylation, and sulfation of mucin O-glycans, increased the expression of four core type 2 O-glycans (F1H2N2, F2H2N2, S1F2H2N2, and A1F1H2N2) significantly. This is the first comprehensive study of the anti-allergic activity of GMOs, and the results lay the foundation for the development of GMOs-based natural anti-allergic components.

Energy metabolism and the intestinal barrier: implications for understanding and managing intestinal diseases

The interplay between energy metabolism and the gut barrier is crucial for maintaining intestinal physiological homeostasis. Energy metabolism and the intestinal barrier perform distinct yet complementary roles that uphold intestinal ecological equilibrium. Disruptions in energy metabolism can compromise the integrity of the intestinal barrier; for example, inactivation of the AMPK pathway may lead to reduced expression of proteins associated with tight junctions. Conversely, impairment of the intestinal barrier can result in metabolic dysregulation, such as alterations in the gut microbiota that impede the production of short-chain fatty acids (SCFAs), which are essential substrates for energy metabolism. This disruption can affect energy production and modify the gut's hypoxic environment. Imbalances in these systems have been associated with the onset of various intestinal diseases. Research indicates that dietary interventions, such as a low FODMAP diet, can enhance the colonization of probiotics and improve the fermentation metabolism of SCFAs. Pharmacological strategies to elevate SCFA levels can activate the AMPK pathway and rectify abnormalities in energy metabolism. This review provides a comprehensive summary of recent advancements in elucidating the interactions between energy metabolism and the intestinal barrier.

Intestinal epithelial glycocalyx and intestinal disease

With the continuous research on glycobiology, more and more diseases are found to be associated with the glycocalyx. Glycocalyx can be categorized as endothelial glycocalyx and epithelial glycocalyx. Past studies mostly target endothelial glycocalyx, and this review focuses on the structure and function of intestinal epithelial glycocalyx, its degradation mechanism and biological relevance to different diseases of the intestinal tract, as well as the targeted delivery of drugs to organs by nanoparticle libraries mimicking the glycocalyx, in order to provide a theoretical basis for the study of potential diagnostic markers and therapeutic targets of intestinal epithelial glycocalyx in intestinal diseases.

Grape seed oil attenuates sodium arsenite-induced gastric, hepatic and colonic damage in Wistar rats

Arsenic exposure is associated with numerous morbidities due to dysfunction of various organ systems including the gastrointestinal tract. We investigated the protective effect of grape seed oil (GSO) against sodium arsenite (NaAsO2)-induced gastric, hepatic and colonic injuries in rats. Twenty-four male Wistar rats were divided into four groups of six as follows: Group A (control) received saline; group B received NaAsO2 (2.5 mg/kg) orally for 7 days; group C were treated concurrently with NaAsO2 and GSO (2 ml/kg), while group D received only GSO. Administration of NaAsO2 induced significant (p < 0.05) increases in alanine aminotransferase (ALT) and aspartate aminotransferase (AST); increased periodic acid Schiff (PAS) staining for mucus and increased goblet cell numbers in the stomach and colon; inflammatory cell infiltration and vascular congestion and alterations in the fecal bacterial flora. GSO supplementation generally promoted a reversal of changes induced by NaAsO2 towards control levels. Additionally, there was increased immunohistochemically detected expression of colonic B-cell lymphoma-1 (Bcl-2) and cytokeratins AE1/AE3, but reduced expression of mucin 1 (MUC1) and carcinoembryonic antigen (CEA) in NaAsO2 + GSO and GSO treated rats when compared with the NaAsO2 group. These results suggest that GSO promoted anti-inflammatory processes in the liver, stomach and colon, as well as opposing apoptosis in the colon, resulting in significant attenuation of damage to these tissues.

A review of the pathogenesis of epilepsy based on the microbiota-gut-brain-axis theory

The pathogenesis of epilepsy is related to the microbiota-gut-brain axis, but the mechanism has not been clarified. The microbiota-gut-brain axis is divided into the microbiota-gut-brain axis (upward pathways) and the brain-gut-microbiota axis (downward pathways) according to the direction of conduction. Gut microorganisms are involved in pathological and physiological processes in the human body and participate in epileptogenesis through neurological, immunological, endocrine, and metabolic pathways, as well as through the gut barrier and blood brain barrier mediated upward pathways. After epilepsy, the downward pathway mediated by the HPA axis and autonomic nerves triggers "leaky brain "and "leaky gut," resulting in the formation of microbial structures and enterobacterial metabolites associated with epileptogenicity, re-initiating seizures via the upward pathway. Characteristic changes in microbial and metabolic pathways in the gut of epileptic patients provide new targets for clinical prevention and treatment of epilepsy through the upward pathway. Based on these changes, this review further redescribes the pathogenesis of epilepsy and provides a new direction for its prevention and treatment.

Translational evaluation of Gelsectan® effects on gut barrier dysfunction and visceral pain in animal models and irritable bowel syndrome with diarrhoea

BACKGROUND

Gelsectan® is a formulation of xyloglucan (XG), pea protein, grape seed extract (PPGS) and xylo-oligosaccharides (XOS). Our aim was to examine the effect of Gelsectan® on rectal sensitivity in an animal model, abdominal pain in irritable bowel syndrome with diarrhoea (IBS-D) subjects and intestinal permeability in both conditions.

METHODS

Animals: Wistar rats received gavage with XOS, XG + PPGS or XG + PPGS + XOS, as a single dose or for 7 days before a partial restraint stress (PRS). Visceromotor response to rectal distension and total gut paracellular permeability to 51Cr-EDTA were assessed. Humans: IBS-D and control patients were involved. After initial colonoscopy with biopsy sampling Gelsectan® was administered to IBS-D patients for 12 weeks. Stool count and pain scores were documented. After treatment, colonoscopy was repeated. The permeability of biopsy samples was measured in Ussing-chambers. Adherent mucus layer, Muc-2 expression as well as TNFα, Interferon IFNγ were evaluated by histology/immunohistochemistry and ELISA assays, respectively.

RESULTS

Animal studies: In control rats, PRS significantly increased visceromotor response as well as gut paracellular permeability. Single dose administration of XG + PPGS + XOS failed to reverse PRS, but 7 days of oral treatment reversed PRS-induced rectal hypersensitivity and gut hyperpermeability. Human studies: Gelsectan® treatment significantly reduced and abdominal pain. Intestinal permeability in IBS-D patients was elevated compared with controls, Gelsectan® restored permeability in the ascendent colon. Periodic acid-Schiff-stained mucus layer was significantly thinner in IBS-D patients compared with controls, In both segments, mucus thickness and the proportion of Muc-2 positive cells were not affected by Gelsectan® treatment. IFNγ tissue level in the sigmoid colon shows modest mucosal inflammation in IBS-D.

CONCLUSIONS

Gelsectan® prevented rectal hypersensitivity in rats, abdominal pain in human and intestinal hyperpermeability in rat and human studies respectively. These effects involve restoration of gut permeability. Based on this translational study, Gelsectan® can be considered as an effective therapy for IBS-D symptoms.

Stress-induced mucin 13 reductions drive intestinal microbiome shifts and despair behaviors

Depression is a prevalent psychological condition with limited treatment options. While its etiology is multifactorial, both chronic stress and changes in microbiome composition are associated with disease pathology. Stress is known to induce microbiome dysbiosis, defined here as a change in microbial composition associated with a pathological condition. This state of dysbiosis is known to feedback on depressive symptoms. While studies have demonstrated that targeted restoration of the microbiome can alleviate depressive-like symptoms in mice, translating these findings to human patients has proven challenging due to the complexity of the human microbiome. As such, there is an urgent need to identify factors upstream of microbial dysbiosis. Here we investigate the role of mucin 13 as an upstream mediator of microbiome composition changes in the context of stress. Using a model of chronic stress, we show that the glycocalyx protein, mucin 13, is selectively reduced after psychological stress exposure. We further demonstrate that the reduction of Muc13 is mediated by the Hnf4 transcription factor family. Finally, we determine that deleting Muc13 is sufficient to drive microbiome shifts and despair behaviors. These findings shed light on the mechanisms behind stress-induced microbial changes and reveal a novel regulator of mucin 13 expression.

Probiotic Yeast from Miso Ameliorates Stress-Induced Visceral Hypersensitivity by Modulating the Gut Microbiota in a Rat Model of Irritable Bowel Syndrome

Background/Aims

Recent studies indicate that probiotics, which have attracted attention as a treatment for irritable bowel syndrome, affect intestinal homeostasis. In this study, we investigated whether Zygosaccharomyces sapae (strain I-6), a probiotic yeast isolated from miso (a traditional Japanese fermented food), could improve irritable bowel syndrome symptoms.

Methods

Male Wistar rats were exposed to water avoidance stress (WAS). The number of defecations during WAS and the visceral hypersensitivity before and after WAS were evaluated using colorectal distension. Tight junction changes were assessed by Western blotting. Some rats were fed with strain I-6 or β-glucan from strain I-6. Changes in the intestinal microbiota were analyzed. The effect of fecal microbiota transplantation after WAS was evaluated similarly. Caco-2 cells were stimulated with interleukin-1β and tight junction changes were investigated after coculture with strain I-6.

Results

The increased number of stool pellets and visceral hypersensitivity induced by WAS were suppressed by administering strain I-6. The decrease in tight junction protein occludin by WAS was reversed by the administration of strain I-6. β-Glucan from strain I-6 also suppressed those changes induced by WAS. In the rat intestinal microbiota, treatment with strain I-6 altered the β-diversity and induced changes in bacterial occupancy. Upon fecal microbiota transplantation, some symptoms caused by WAS were ameliorated.

Conclusions

These results suggest that traditional fermented foods such as miso in Japan are valuable sources of probiotic yeast candidates, which may be useful for preventing and treating stress-induced visceral hypersensitivity.

Pollutants, microbiota and immune system: frenemies within the gut

Pollution is a critical concern of modern society for its heterogeneous effects on human health, despite a widespread lack of awareness. Environmental pollutants promote several pathologies through different molecular mechanisms. Pollutants can affect the immune system and related pathways, perturbing its regulation and triggering pro-inflammatory responses. The exposure to several pollutants also leads to alterations in gut microbiota with a decreasing abundance of beneficial microbes, such as short-chain fatty acid-producing bacteria, and an overgrowth of pro-inflammatory species. The subsequent intestinal barrier dysfunction, together with oxidative stress and increased inflammatory responses, plays a role in the pathogenesis of gastrointestinal inflammatory diseases. Moreover, pollutants encourage the inflammation-dysplasia-carcinoma sequence through various mechanisms, such as oxidative stress, dysregulation of cellular signalling pathways, cell cycle impairment and genomic instability. In this narrative review, we will describe the interplay between pollutants, gut microbiota, and the immune system, focusing on their relationship with inflammatory bowel diseases and colorectal cancer. Understanding the biological mechanisms underlying the health-to-disease transition may allow the design of public health policies aimed at reducing the burden of disease related to pollutants.

Colon impairments and inflammation driven by an altered gut microbiota leads to social behavior deficits rescued by hyaluronic acid and celecoxib

BACKGROUND

The exact mechanisms linking the gut microbiota and social behavior are still under investigation. We aimed to explore the role of the gut microbiota in shaping social behavior deficits using selectively bred mice possessing dominant (Dom) or submissive (Sub) behavior features. Sub mice exhibit asocial, depressive- and anxiety-like behaviors, as well as systemic inflammation, all of which are shaped by their impaired gut microbiota composition.

METHODS

An age-dependent comparative analysis of the gut microbiota composition of Dom and Sub mice was performed using 16S rRNA sequencing, from early infancy to adulthood. Dom and Sub gastrointestinal (GI) tract anatomy, function, and immune profiling analyses were performed using histology, RT-PCR, flow cytometry, cytokine array, and dextran-FITC permeability assays. Short chain fatty acids (SCFA) levels in the colons of Dom and Sub mice were quantified using targeted metabolomics. To support our findings, adult Sub mice were orally treated with hyaluronic acid (HA) (30 mg/kg) or with the non-steroidal anti-inflammatory agent celecoxib (16 mg/kg).

RESULTS

We demonstrate that from early infancy the Sub mouse gut microbiota lacks essential bacteria for immune maturation, including Lactobacillus and Bifidobacterium genera. Furthermore, from birth, Sub mice possess a thicker colon mucin layer, and from early adulthood, they exhibit shorter colonic length, altered colon integrity with increased gut permeability, reduced SCFA levels and decreased regulatory T-cells, compared to Dom mice. Therapeutic intervention in adult Sub mice treated with HA, celecoxib, or both agents, rescued Sub mice phenotypes. HA treatment reduced Sub mouse gut permeability, increased colon length, and improved mouse social behavior deficits. Treatment with celecoxib increased sociability, reduced depressive- and anxiety-like behaviors, and increased colon length, and a combined treatment resulted in similar effects as celecoxib administered as a single agent.

CONCLUSIONS

Overall, our data suggest that treating colon inflammation and decreasing gut permeability can restore gut physiology and prevent social deficits later in life. These findings provide critical insights into the importance of early life gut microbiota in shaping gut immunity, functionality, and social behavior, and may be beneficial for the development of future therapeutic strategies.

Effect of chronic stress on gel-forming mucins in the small intestine of BALB/c mice

Intestinal homeostasis involves the collaboration of gut barrier components, such as goblet cells and IgA-microbiota complexes, that are under the control of stress that promotes inflammatory responses addressed primarily in the colon. The aim of this study was to evaluate the effect of stress on mucins, goblet cells, and proinflammatory parameters in the proximal and distal regions of the small intestine. A group (n = 6) of female 8-week-old BALB/c mice underwent board immobilization stress (2 h per day for 4 days) and were sacrificed with isoflurane. Samples from proximal and distal small segments were collected to analyze the following: 1) goblet cells stained with periodic acid-Schiff (PAS) and with alcian blue (AB) to visualize histologically neutral and acidic mucins, respectively; 2) IgA-microbiota complexes identified by flow cytometry in intestinal lavages; and 3) MUC2, MUC5AC, and IL-18 mRNA levels in whole mucosal scrapings by reverse transcription-qPCR. Regarding the unstressed group, in the proximal region of small intestine both PAS+ and AB+ goblet cells were unchanged; however, MUC5AC and IL-18 mRNA levels were increased, and the percentage of IgA-microbiota complexes was reduced. In the distal segment, the number of PAS+ goblet cells was increased, whereas the number of AB+ goblet cells was reduced and did not affect the remaining parameters. The data suggest that stress induces inflammation in the proximal small intestine; these findings may provide an experimental reference for human diseases that may affect the proximal small intestine, such as Crohn's disease, in which stress contributes to the progression of intestinal inflammation or relapse.

The Interaction between Stress and Inflammatory Bowel Disease in Pediatric and Adult Patients

Background: Inflammatory bowel diseases (IBDs) have seen an exponential increase in incidence, particularly among pediatric patients. Psychological stress is a significant risk factor influencing the disease course. This review assesses the interaction between stress and disease progression, focusing on articles that quantified inflammatory markers in IBD patients exposed to varying degrees of psychological stress. Methods: A systematic narrative literature review was conducted, focusing on the interaction between IBD and stress among adult and pediatric patients, as well as animal subjects. The research involved searching PubMed, Scopus, Medline, and Cochrane Library databases from 2000 to December 2023. Results: The interplay between the intestinal immunity response, the nervous system, and psychological disorders, known as the gut-brain axis, plays a major role in IBD pathophysiology. Various types of stressors alter gut mucosal integrity through different pathways, increasing gut mucosa permeability and promoting bacterial translocation. A denser microbial load in the gut wall emphasizes cytokine production, worsening the disease course. The risk of developing depression and anxiety is higher in IBD patients compared with the general population, and stress is a significant trigger for inducing acute flares of the disease. Conclusions: Further large studies should be conducted to assess the relationship between stressors, psychological disorders, and their impact on the course of IBD. Clinicians involved in the medical care of IBD patients should aim to implement stress reduction practices in addition to pharmacological therapies.

Effect of diet supplemented with functional amino acids and polyphenols on gut health in broilers subjected to a corticosterone-induced stress

To address the overuse of antimicrobials in poultry production, new functional feed ingredients, i.e. ingredients with benefits beyond meeting basic nutritional requirements, can play a crucial role thanks to their prophylactic effects. This study evaluated the effects of the supplementation of arginine, threonine and glutamine together with grape polyphenols on the gut integrity and functionality of broilers facing a stress condition. 108 straight-run newly hatched Ross PM3 chicks were kept until 35 days and were allocated to 3 treatments. Broilers in the control group were raised in standard conditions. In experimental groups, birds were administered with corticosterone in drinking water (CORT groups) to impair the global health of the animal and were fed a well-balanced diet supplemented or not with a mix of functional amino acids together with grape extracts (1 g/kg of diet-CORT + MIX group). Gut permeability was significantly increased by corticosterone in non-supplemented birds. This corticosterone-induced stress effect was alleviated in the CORT + MIX group. MIX supplementation attenuated the reduction of crypt depth induced by corticosterone. Mucin 2 and TNF-α gene expression was up-regulated in the CORT + MIX group compared to the CORT group. Caecal microbiota remained similar between the groups. These findings indicate that a balanced diet supplemented with functional AA and polyphenols can help to restore broiler intestinal barrier after a stress exposure.

Molecular Mechanisms of Reelin in the Enteric Nervous System and the Microbiota-Gut-Brain Axis: Implications for Depression and Antidepressant Therapy

Current pharmacological treatments for depression fail to produce adequate remission in a significant proportion of patients. Increasingly, other systems, such as the microbiome-gut-brain axis, are being looked at as putative novel avenues for depression treatment. Dysbiosis and dysregulation along this axis are highly comorbid with the severity of depression symptoms. The endogenous extracellular matrix protein reelin is present in all intestinal layers as well as in myenteric and submucosal ganglia, and its receptors are also present in the gut. Reelin secretion from subepithelial myofibroblasts regulates cellular migration along the crypt-villus axis in the small intestine and colon. Reelin brain expression is downregulated in mood and psychotic disorders, and reelin injections have fast antidepressant-like effects in animal models of depression. This review seeks to discuss the roles of reelin in the gastrointestinal system and propose a putative role for reelin actions in the microbiota-gut-brain axis in the pathogenesis and treatment of depression, primarily reflecting on alterations in gut epithelial cell renewal and in the clustering of serotonin transporters.

Impact of structurally diverse polysaccharides on colonic mucin O-glycosylation and gut microbiota

Understanding how dietary polysaccharides affect mucin O-glycosylation and gut microbiota could provide various nutrition-based treatments. Here, the O-glycan profile of the colonic mucosa and gut microbiome were investigated in C57BL/6J mice fed six structurally diverse dietary polysaccharides and a mixture of six fibers. Dietary polysaccharides increased total O-glycans, mainly by stimulating neutral glycans. Highly branched arabinogalactan promoted terminally fucosylated core 1 O-glycans; whereas linear polysaccharides, including pectin, konjac glucomannan, inulin, and the fiber mixture, favored terminally di-fucosylated O-glycans. The last three polysaccharides also lowered the level of sulfated O-glycans and sialylated mono-fucosylated O-glycans. Varied monosaccharide composition in mixed polysaccharides had a synergistic beneficial effect, boosting fucosylated neutral glycans, decreasing acidic glycans, and stimulating microbial richness and diversity. Dietary polysaccharides containing arabinose and sulfate groups enhanced the relative abundances of Akkermansia and Muribaculaceae, respectively. The present comparison reveals the relationship between dietary polysaccharide structure, mucin O-glycan composition, and intestinal microorganisms.

Oral nanomedicine biointeractions in the gastrointestinal tract in health and disease

Oral administration is the preferred route of administration based on the convenience for and compliance of the patient. Oral nanomedicines have been developed to overcome the limitations of free drugs and overcome gastrointestinal (GI) barriers, which are heterogeneous across healthy and diseased populations. This review aims to provide a comprehensive overview and comparison of the oral nanomedicine biointeractions in the gastrointestinal tract (GIT) in health and disease (GI and extra-GI diseases) and highlight emerging strategies that exploit these differences for oral nanomedicine-based treatment. We introduce the key GI barriers related to oral delivery and summarize their pathological changes in various diseases. We discuss nanomedicine biointeractions in the GIT in health by describing the general biointeractions based on the type of oral nanomedicine and advanced biointeractions facilitated by advanced strategies applied in this field. We then discuss nanomedicine biointeractions in different diseases and explore how pathological characteristics have been harnessed to advance the development of oral nanomedicine.

The gut mucin-microbiota interactions: a missing key to optimizing endurance performance

Endurance athletes offer unique physiology and metabolism compared to sedentary individuals. Athletes training at high intensities for prolonged periods are at risk for gastrointestinal disturbances. An important factor in endurance performance is the integrity and function of the gut barrier, which primarily depends on heavily O-glycosylated mucins. Emerging evidence shows a complex bidirectional dialogue between glycans on mucins and gut microorganisms. This review emphasizes the importance of the crosstalk between the gut microbiome and host mucus mucins and some of the mechanisms underlying this symbiosis. The contribution of mucin glycans to the composition and functionality of the gut microbiome is discussed, as well as the persuasive impact of the gut microbiome on mucin composition, thickness, and immune and metabolic functions. Lastly, we propose natural and synthetic glycans supplements to improve intestinal mucus production and barrier function, offering new opportunities to enhance endurance athletes' performance and gut health.

Microbiota-Accessible Boron-Containing Compounds in Complex Regional Pain Syndrome

The microbiota-gut-brain axis has garnered increasing attention in recent years for its role in various health conditions, including neuroinflammatory disorders like complex regional pain syndrome (CRPS). CRPS is a debilitating condition characterized by chronic neuropathic pain, and its etiology and pathophysiology remain elusive. Emerging research suggests that alterations in the gut microbiota composition and function could play a significant role in CRPS development and progression. Our paper explores the implications of microbiota in CRPS and the potential therapeutic role of boron (B). Studies have demonstrated that individuals with CRPS often exhibit dysbiosis, with imbalances in beneficial and pathogenic gut bacteria. Dysbiosis can lead to increased gut permeability and systemic inflammation, contributing to the chronic pain experienced in CRPS. B, an essential trace element, has shown promise in modulating the gut microbiome positively and exerting anti-inflammatory effects. Recent preclinical and clinical studies suggest that B supplementation may alleviate neuropathic pain and improve CRPS symptoms by restoring microbiota balance and reducing inflammation. Our review highlights the complex interplay between microbiota, inflammation, and neuropathic pain in CRPS and underscores the potential of B as a novel therapeutic approach to target the microbiota-gut-brain axis, offering hope for improved management of this challenging condition.

The impact of acute and chronic stress on gastrointestinal physiology and function: a microbiota-gut-brain axis perspective

The physiological consequences of stress often manifest in the gastrointestinal tract. Traumatic or chronic stress is associated with widespread maladaptive changes throughout the gut, although comparatively little is known about the effects of acute stress. Furthermore, these stress-induced changes in the gut may increase susceptibility to gastrointestinal disorders and infection, and impact critical features of the neural and behavioural consequences of the stress response by impairing gut-brain axis communication. Understanding the mechanisms behind changes in enteric nervous system circuitry, visceral sensitivity, gut barrier function, permeability, and the gut microbiota following stress is an important research objective with pathophysiological implications in both neurogastroenterology and psychiatry. Moreover, the gut microbiota has emerged as a key aspect of physiology sensitive to the effects of stress. In this review, we focus on different aspects of the gastrointestinal tract including gut barrier function as well as the immune, humoral and neuronal elements involved in gut-brain communication. Furthermore, we discuss the evidence for a role of stress in gastrointestinal disorders. Existing gaps in the current literature are highlighted, and possible avenues for future research with an integrated physiological perspective have been suggested. A more complete understanding of the spatial and temporal dynamics of the integrated host and microbial response to different kinds of stressors in the gastrointestinal tract will enable full exploitation of the diagnostic and therapeutic potential in the fast-evolving field of host-microbiome interactions.

Beneficial Effects of Lactobacilli Species on Intestinal Homeostasis in Low-Grade Inflammation and Stress Rodent Models and Their Implication in the Modulation of the Adhesive Junctional Complex

Intestinal barrier integrity is essential in order to maintain the homeostasis of mucosal functions and efficient defensive reactions against chemical and microbial challenges. An impairment of the intestinal barrier has been observed in several chronic diseases. The gut microbiota and its impact on intestinal homeostasis is well described and numerous studies suggest the ability of some probiotic strains to protect the intestinal epithelial integrity and host homeostasis. In this work, we aimed to assess the beneficial effects of three Lactobacillus strains (Lacticaseibacillus rhamnosus LR04, Lacticaseibacillus casei LC03, and Lactiplantibacillus plantarum CNCM I-4459) and their mechanism of action in low-grade inflammation or neonatal maternal separation models in mice. We compared the impact of these strains to that of the well-known probiotic Lacticaseibacillus rhamnosus GG. Our results demonstrated that the three strains have the potential to restore the barrier functions by (i) increasing mucus production, (ii) restoring normal permeability, and (iii) modulating colonic hypersensitivity. Moreover, gene expression analysis of junctional proteins revealed the implication of Claudin 2 and Cingulin in the mechanisms that underlie the interactions between the strains and the host. Taken together, our data suggest that LR04, CNCM I-4459, and LC03 restore the functions of an impaired intestinal barrier.

Rhubarb polysaccharide and berberine co-assembled nanoparticles ameliorate ulcerative colitis by regulating the intestinal flora

Introduction: Inflammatory bowel disease (IBD) affects about 7 million people globally, which is a chronic inflammatory condition of the gastrointestinal tract caused by gut microbiota alterations, immune dysregulation, genetic and environmental factors. Nanoparticles (NPs) deliver an active natural compound to a site harbored by disordered microbiota, they are used to interact, target and act intentionally on microbiota. Although there is accumulating evidence indicating that berberine and polysaccharide play an important role in IBD via regulating microbiota, there is limited research that presents a complete picture of exactly how their carrier-free co-assembled nanodrug affects IBD. Methods: The study establishes the carrier-free NPs formed by berberine and rhubarb polysaccharide based on the combination theory of Rheum palmatum L. and Coptis chinensis Franch., and characterizes the NPs. The IBD treatment efficacy of NPs are evaluated via IBD efficacy index, and explore the mechanism of NPs via 16S rRNA test and immunohistochemistry including occludin and zonula occludens-1. Results: The results showed that DHP and BBR were co-assembled to nanoparticles, and the BD can effectively relieve the symptoms of UC mouse induced by DSS via regulating gut microbiota and repair the gut barrier integrity, because BD have a longer retention on the colon tissue and react with the microbiota and mucus thoroughly. Interestingly, BD can enrich more probiotic than free BBR and DHP. Discussion: This design provides a better strategy and encourages future studies on IBD treatment via regulating gut microbiota and the design of novel plant polysaccharide based carrier-free co-assembly therapies.

Ambient particulate air pollution and the intestinal microbiome; a systematic review of epidemiological, in vivo and, in vitro studies

A healthy indigenous intestinal microbiome is indispensable for intra- and extra-intestinal human health. Since well-established factors such as diet and antibiotic use only explain 16 % of the inter-individual variation in gut microbiome composition, recent studies have focused on the association between ambient particulate air pollution and the intestinal microbiome. We systematically summarize and discuss all evidence concerning the effect of particulate air pollution on intestinal bacterial diversity indices, specific bacterial taxa, and potential underlying intestinal mechanisms. To this end, all possibly relevant publications published between February 1982 and January 2023 were screened, and eventually, 48 articles were included. The vast majority (n = 35) of these studies were animal studies. The exposure periods investigated in the human epidemiological studies (n = 12) ranged from infancy through elderly. This systematic review found that intestinal microbiome diversity indices were generally negatively associated with particulate air pollution in epidemiological studies, with an increase in taxa belonging to Bacteroidetes (two studies), Deferribacterota (one study), and Proteobacteria (four studies), a decrease in taxa belonging to Verrucomicrobiota (one study), and no consensus for taxa belonging to Actinobacteria (six studies) and Firmicutes (seven studies). There was no unequivocal effect of ambient particulate air pollution exposure on bacterial indices and taxa in animal studies. Only one study in humans examined a possible underlying mechanism; yet, the included in vitro and animal studies depicted higher gut damage, inflammation, oxidative stress, and permeability in exposed versus unexposed animals. Overall, the population-based studies showed a dose-related continuum of short- and long-term ambient particulate air pollution exposure on lower gut diversity and shifts in taxa over the entire life course.

The Gut Microbiome and Residential Surrounding Greenness: a Systematic Review of Epidemiological Evidence

PURPOSE OF REVIEW

A healthy indigenous intestinal microbiome is essential for human health. Well-established gut microbiome determinants only explain 16% of the inter-individual variation in gut microbiome composition. Recent studies have focused on green space as a potential determinant of the intestinal microbiome. We systematically summarize all evidence concerning the association between green space and intestinal bacterial diversity, evenness, and richness indices, specific bacterial taxa, and potential underlying mechanisms.

RECENT FINDINGS

Seven epidemiological studies were included in this review. The majority of the included studies (n = 4) reported a positive association between green space and intestinal bacterial diversity, evenness, and richness, while two reported the opposite. There was little overlap between the publications regarding the association between green space and the relative abundance of specific bacterial taxa. Only a decrease in the relative abundance of Bacteroidetes, Bacteroides, and Anaerostipes and an increase in Lachnospiraceae and Ruminococcaceae were reported in multiple studies, predominantly suggesting that green space is positively associated with the intestinal microbiome composition, and subsequently with human health. Lastly, the only examined mechanism was a reduction in perceived psychosocial stress. Mechanisms indicated in blue and white represent tested or hypothesized mechanisms, respectively. The graphical abstract was created with illustrations from BioRender, Noun Project, and Pngtree.

Sex difference in prebiotics on gut and blood-brain barrier dysfunction underlying stress-induced anxiety and depression

BACKGROUND

Most of the previous studies have demonstrated the potential antidepressive and anxiolytic role of prebiotic supplement in male subjects, yet few have females enrolled. Herein, we explored whether prebiotics administration during chronic stress prevented depression-like and anxiety-like behavior in a sex-specific manner and the mechanism of behavioral differences caused by sex.

METHODS

Female and male C57 BL/J mice on normal diet were supplemented with or without a combination of fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) during 3- and 4-week chronic restraint stress (CRS) treatment, respectively. C57 BL/J mice on normal diet without CRS were used as controls. Behavior consequences, gut microbiota, dysfunction of gut and brain-blood barriers, and inflammatory profiles were measured.

RESULTS

In the 3rd week, FOS + GOS administration attenuated stress-induced anxiety-like behavior in female, but not in male mice, and the anxiolytic effects in males were observed until the 4th week. However, protective effects of prebiotics on CRS-induced depression were not observed. Changes in the gene expression of tight junction proteins in the distal colon and hippocampus, and decreased number of colon goblet cells following CRS were restored by prebiotics only in females. In both female and male mice, prebiotics alleviated stress-induced BBB dysfunction and elevation in pro-inflammatory cytokines levels, and modulated gut microbiota caused by stress. Furthermore, correlation analysis revealed that anxiety-like behaviors were significantly correlated with levels of pro-inflammatory cytokines and gene expression of tight junction proteins in the hippocampus of female mice, and the abundance of specific gut microbes was also correlated with anxiety-like behaviors, pro-inflammatory cytokines, and gene expression of tight junction proteins in the hippocampus of female mice.

CONCLUSION

Female mice were more vulnerable to stress and prebiotics than males. The gut microbiota, gut and blood-brain barrier, and inflammatory response may mediate the protective effects of prebiotics on anxiety-like behaviors in female mice.

The Detrimental Effects of Peripartum Antibiotics on Gut Proliferation and Formula Feeding Injury in Neonatal Mice Are Alleviated with Lactobacillus rhamnosus GG

Peripartum antibiotics can negatively impact the developing gut microbiome and are associated with necrotizing enterocolitis (NEC). The mechanisms by which peripartum antibiotics increase the risk of NEC and strategies that can help mitigate this risk remain poorly understood. In this study, we determined mechanisms by which peripartum antibiotics increase neonatal gut injury and evaluated whether probiotics protect against gut injury potentiated by peripartum antibiotics. To accomplish this objective, we administered broad-spectrum antibiotics or sterile water to pregnant C57BL6 mice and induced neonatal gut injury to their pups with formula feeding. We found that pups exposed to antibiotics had reduced villus height, crypt depth, and intestinal olfactomedin 4 and proliferating cell nuclear antigen compared to the controls, indicating that peripartum antibiotics impaired intestinal proliferation. When formula feeding was used to induce NEC-like injury, more severe intestinal injury and apoptosis were observed in the pups exposed to antibiotics compared to the controls. Supplementation with the probiotic Lactobacillus rhamnosus GG (LGG) reduced the severity of formula-induced gut injury potentiated by antibiotics. Increased intestinal proliferating cell nuclear antigen and activation of the Gpr81-Wnt pathway were noted in the pups supplemented with LGG, suggesting partial restoration of intestinal proliferation by probiotics. We conclude that peripartum antibiotics potentiate neonatal gut injury by inhibiting intestinal proliferation. LGG supplementation decreases gut injury by activating the Gpr81-Wnt pathway and restoring intestinal proliferation impaired by peripartum antibiotics. Our results suggest that postnatal probiotics may be effective in mitigating the increased risk of NEC associated with peripartum antibiotic exposure in preterm infants.

Altered gut microbiota in temporal lobe epilepsy with anxiety disorders

Introduction

Patients with epilepsy are particularly vulnerable to the negative effects of anxiety disorders. In particular, temporal lobe epilepsy with anxiety disorders (TLEA) has attracted more attention in epilepsy research. The link between intestinal dysbiosis and TLEA has not been established yet. To gain deeper insight into the link between gut microbiota dysbiosis and factors affecting TLEA, the composition of the gut microbiome, including bacteria and fungi, has been examined.

Methods

The gut microbiota from 51 temporal lobe epilepsy patients has been subjected to sequencing targeting 16S rDNA (Illumina MiSeq) and from 45 temporal lobe epilepsy patients targeting the ITS-1 region (through pyrosequencing). A differential analysis has been conducted on the gut microbiota from the phylum to the genus level.

Results

TLEA patients' gut bacteria and fungal microbiota exhibited distinct characteristics and diversity as evidenced by high-throughput sequencing (HTS). TLEA patients showed higher abundances of Escherichia-Shigella (genus), Enterobacterales (order), Enterobacteriaceae (family), Proteobacteria (phylum), Gammaproteobacteria (class), and lower abundances of Clostridia (class), Firmicutes, Lachnospiraceae (family), Lachnospirales (order), and Ruminococcus (genus). Among fungi, Saccharomycetales fam. incertae sedis (family), Saccharomycetales (order), Saccharomycetes (class), and Ascomycota (phylum) were significantly more abundant in TLEA patients than in patients with temporal lobe epilepsy but without anxiety. Adoption and perception of seizure control significantly affected TLEA bacterial community structure, while yearly hospitalization frequency affected fungal community structures in TLEA patients.

Conclusion

Here, our study validated the gut microbiota dysbiosis of TLEA. Moreover, the pioneering study of bacterial and fungal microbiota profiles will help in understanding the course of TLEA and drive us toward preventing TLEA gut microbiota dysbiosis.

The protective effects of electroacupuncture on intestinal barrier lesions in IBS and UC model

Irritable bowel syndrome (IBS) and ulcerative colitis (UC) are two intestinal diseases with different pathological changes. Electroacupuncture (EA) at Zusanli (ST36) on both IBS and UC is widely used in clinic practice. But it is unclear whether acupuncture at one acupoint can treat two different intestinal diseases at different layers of intestinal barrier. To address this question, we explored three intestinal barrier lesions in IBS and UC mice with the aid of transcriptome data analysis and studied the efficacy of EA at ST36 on them. The transcriptome data analysis showed that both UC and IBS had disrupted intestinal barrier in various layers. And both UC and IBS had epithelial barrier lesions with reduction of ZO-1, Occludin and Claudin-1, while UC rather than IBS had the destruction of the mucus barrier with less MUC2 expression. As to the vascular barrier, UC showed a higher CD31 level and mesenteric blood flow reduction, while IBS showed a lower PV-1 level. EA at ST36 can significantly improve the above lesions of intestinal barrier of IBS and UC. Our results gave more details about the comprehensive protective effect of EA for UC and IBS. We guess the effect of acupuncture may be a kind of homeostasis regulation.

Alterations of the intestinal mucus layer correlate with dysbiosis and immune dysregulation in human Type 1 Diabetes

BACKGROUND

In preclinical models of Type 1 Diabetes (T1D) the integrity of the gut barrier (GB) is instrumental to avoid dysregulated crosstalk between the commensal microbiota and immune cells and to prevent autoimmunity. The GB is composed of the intestinal epithelial barrier (IEB) and of the mucus layer containing mucins and antimicrobial peptides (AMPs) that are crucial to maintain immune tolerance. In preclinical models of T1D the alterations of the GB primarily affect the mucus layer. In human T1D increased gut permeability and IEB damage have been demonstrated but the integrity of the mucus layer was never assessed.

METHODS

We evaluated GB integrity by measuring serological markers of IEB damage (serological levels of zonulin) and bacterial translocation such as lipopolysaccharide binding protein (LBP) and myeloid differentiation protein 2 (MD2), and mRNA expression of tight junction proteins, mucins and AMPs in intestinal tissue of T1D patients and healthy controls (HC). Simultaneously, we performed immunological profiling on intestinal tissue and 16S rRNA analysis on the mucus-associated gut microbiota (MAGM).

FINDINGS

Our data show a GB damage with mucus layer alterations and reduced mRNA expression of several mucins (MUC2, MUC12, MUC13, MUC15, MUC20, MUC21) and AMPs (HD4 and HD5) in T1D patients. Mucus layer alterations correlated with reduced relative abundance of short chain fatty acids (SCFA)-producing bacteria such as Bifidobacterium dentium, Clostridium butyricum and Roseburia intestinalis that regulate mucin expression and intestinal immune homeostasis. In T1D patients we also found intestinal immune dysregulation with higher percentages of effector T cells such as T helper (Th) 1, Th17 and TNF-α⁺ T cells.

INTERPRETATION

Our data show that mucus layer alterations are present in T1D subjects and associated with dysbiosis and immune dysregulation.

FUNDING

Research Grants from the Juvenile Diabetes Foundation (Grant 1-INO-2018-640-A-N to MF and 2-SRA-2019-680-S-B to JD) and from the Italian Ministry of Health (Grant RF19-12370721 to MF).

Intestinal mucus components and secretion mechanisms: what we do and do not know

Damage to the colon mucus barrier, the first line of defense against microorganisms, is an important determinant of intestinal diseases such as inflammatory bowel disease and colorectal cancer, and disorder in extraintestinal organs. The mucus layer has attracted the attention of the scientific community in recent years, and with the discovery of new mucosal components, it has become increasingly clear that the mucosal barrier is a complex system composed of many components. Moreover, certain components are jointly involved in regulating the structure and function of the mucus barrier. Therefore, a comprehensive and systematic understanding of the functional components of the mucus layer is clearly warranted. In this review, we summarize the various functional components of the mucus layer identified thus far and describe their unique roles in shaping mucosal structure and function. Furthermore, we detail the mechanisms underlying mucus secretion, including baseline and stimulated secretion. In our opinion, baseline secretion can be categorized into spontaneous Ca²⁺ oscillation-mediated slow and continuous secretion and stimulated secretion, which is mediated by massive Ca²⁺ influx induced by exogenous stimuli. This review extends the current understanding of the intestinal mucus barrier, with an emphasis on host defense strategies based on fortification of the mucus layer.

O-Mucin-degrading carbohydrate-active enzymes and their possible implication in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are modern diseases, with incidence rising around the world. They are associated with perturbation of the intestinal microbiota, and with alteration and crossing of the mucus barrier by the commensal bacteria that feed on it. In the process of mucus catabolism and invasion by gut bacteria, carbohydrate-active enzymes (CAZymes) play a critical role since mucus is mainly made up by O- and N-glycans. Moreover, the occurrence of IBD seems to be associated with low-fiber diets. Conversely, supplementation with oligosaccharides, such as human milk oligosaccharides (HMOs), which are structurally similar to intestinal mucins and could thus compete with them towards bacterial mucus-degrading CAZymes, has been suggested to prevent inflammation. In this mini-review, we will establish the current state of knowledge regarding the identification and characterization of mucus-degrading enzymes from both cultured and uncultured species of gut commensals and enteropathogens, with a particular focus on the present technological opportunities available to further the discovery of mucus-degrading CAZymes within the entire gut microbiome, by coupling microfluidics with metagenomics and culturomics. Finally, we will discuss the challenges to overcome to better assess how CAZymes targeting specific functional oligosaccharides could be involved in the modulation of the mucus-driven cross-talk between gut bacteria and their host in the context of IBD.

Orchestration of MUC2 - The key regulatory target of gut barrier and homeostasis: A review

The gut mucosa of human is covered by mucus, functioning as a crucial defense line for the intestine against external stimuli and pathogens. Mucin2 (MUC2) is a subtype of secretory mucins generated by goblet cells and is the major macromolecular component of mucus. Currently, there is an increasing interest on the investigations of MUC2, noting that its function is far beyond a maintainer of the mucus barrier. Moreover, numerous gut diseases are associated with dysregulated MUC2 production. Appropriate production level of MUC2 and mucus contributes to gut barrier function and homeostasis. The production of MUC2 is regulated by a series of physiological processes, which are orchestrated by various bioactive molecules, signaling pathways and gut microbiota, etc., forming a complex regulatory network. Incorporating the latest findings, this review provided a comprehensive summary of MUC2, including its structure, significance and secretory process. Furthermore, we also summarized the molecular mechanisms of the regulation of MUC2 production aiming to provide developmental directions for future researches on MUC2, which can act as a potential prognostic indicator and targeted therapeutic manipulation for diseases. Collectively, we elucidated the micro-level mechanisms underlying MUC2-related phenotypes, hoping to offer some constructive guidance for intestinal and overall health of mankind.

View from the Biological Property: Insight into the Functional Diversity and Complexity of the Gut Mucus

Due to mucin's important protective effect on epithelial tissue, it has garnered extensive attention. The role played by mucus in the digestive tract is undeniable. On the one hand, mucus forms "biofilm" structures that insulate harmful substances from direct contact with epithelial cells. On the other hand, a variety of immune molecules in mucus play a crucial role in the immune regulation of the digestive tract. Due to the enormous number of microorganisms in the gut, the biological properties of mucus and its protective actions are more complicated. Numerous pieces of research have hinted that the aberrant expression of intestinal mucus is closely related to impaired intestinal function. Therefore, this purposeful review aims to provide the highlights of the biological characteristics and functional categorization of mucus synthesis and secretion. In addition, we highlight a variety of the regulatory factors for mucus. Most importantly, we also summarize some of the changes and possible molecular mechanisms of mucus during certain disease processes. All these are beneficial to clinical practice, diagnosis, and treatment and can provide some potential theoretical bases. Admittedly, there are still some deficiencies or contradictory results in the current research on mucus, but none of this diminishes the importance of mucus in protective impacts.

Activation of goblet cell Piezo1 alleviates mucus barrier damage in mice exposed to WAS by inhibiting H3K9me3 modification

BACKGROUND

Our recent studies found that intestinal mechanical signals can regulate mucus synthesis and secretion of intestinal goblet cells through piezo type mechanosensitive ion channel component 1 (Piezo1), but the detailed molecular mechanisms remain to be investigated. Previous studies using a water avoidance stress (WAS) model reported decreased intestinal mucus accompanied by abnormal intestinal motility. It has also been reported that the expression of mucin2 was negatively correlated with histone H3 lysine 9 trimethylation (H3K9me3), a key regulator of histone methylation, and that mechanical stimulation can affect methylation. In this study, we aimed to determine whether and how Piezo1 expressed on goblet cells regulates mucus barrier function through methylation modification.

METHODS

A murine WAS model was established and treated with Yoda1 (Piezo1 agonist), and specific Piezo1 flox-mucin2 Cre mice were also tested. The mucus layer thickness and mucus secretion rate of mouse colonic mucosa were detected by a homemade horizontal Ussing chamber, intestinal peristaltic contraction was detected by the ink propulsion test and organ bath, goblet cells and mucus layer morphology were assessed by HE and Alcian blue staining, mucus permeability was detected by FISH, and the expression levels of Piezo1, H3K9me3 and related molecules were measured by Western blots and immunofluorescence. LS174T cells were cultured on a shaker board in vitro to simulate mechanical stimulation. Piezo1 and H3K9me3 were inhibited, and changes in mucin2 and methylation-related pathways were detected by ELISAs and Western blots. ChIP-PCR assays were used to detect the binding of H3K9me3 and mucin2 promoters under mechanical stimulation.

RESULTS

Compared with those of the controls, the mucus layer thickness and mucus secretion rate of the mice exposed to WAS were significantly decreased, the mucus permeability increased, the number of goblet cells decreased, and the intestinal contraction and peristalsis were also downregulated and disordered. Intraperitoneal injection of Yoda1 improved mucus barrier function and intestinal contraction. In the colonic mucosa of mice exposed to WAS, Piezo1 was decreased, and histone H3 lysine 9 trimethylation (H3K9me3) and methyltransferase suppressor of variegation 3-9 homolog 1 (SUV39h1) were increased, but activating Piezo1 alleviated these effects of WAS. Piezo1 flox-mucin2 Cre mice showed decreased mucus expression and increased methylation compared to wild-type mice. Cell experiments showed that mechanical stimulation induced the activation of Piezo1, decreased H3K9me3 and SUV39h1, and upregulated mucin2 expression. Inhibition of Piezo1 or H3K9me3 blocked the promoting effect of mechanical stimulation on LS174T mucin2 expression. The binding of H3K9me3 to the mucin2 promoter decreased significantly under mechanical stimulation, but this could be blocked by the Piezo1 inhibitor GsMTx4.

CONCLUSION

Piezo1 mediates mechanical stimulation to inhibit SUV39h1, thereby reducing H3K9me3 production and its binding to the mucin2 promoter, ultimately promoting mucin2 expression in goblet cells. This study further confirmed that piezo1 on goblet cells could regulate mucus barrier function through methylation.

Improvement of the intestinal epithelial barrier during laxative effects of phlorotannin in loperamide-induced constipation of SD rats

BACKGROUND

Disruptions of the intestinal epithelial barrier (IEB) are frequently observed in various digestive diseases, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). This study assessed the improvement in the IEB during the laxative activity of phlorotannin (Pt) harvested from Ecklonia cava in constipation by examining the changes in the expression of the regulatory proteins for the tight junction (TJ) and adherens junction (AJ), and inflammatory cytokines in Sprague Dawley (SD) rats with loperamide (Lm)-induced constipation after a Pt treatment.

RESULTS

The Pt treatment induced laxative activity, including the improvement of feces-related parameters, gastrointestinal transit rate, and histological structure of the mid colon in Lm-treated SD rats. In addition, significant recovery effects were detected in the histology of IEB, including the mucus layer, epithelial cells, and lamina propria in the mid colon of Lm + Pt treated SD rats. The expression levels of E-cadherin and p120-catenin for AJ and the ZO-1, occludin, and Claudin-1 genes for TJ in epithelial cells were improved remarkably after the Pt treatment, but the rate of increase was different. Furthermore, the Pt treatment increased the expression level of several inflammatory cytokines, such as TNF-α, IL-6, IL-1β, IL-13, and IL-4 in Lm + Pt treated SD rats.

CONCLUSIONS

These results provide the first evidence that the laxative activity of Pt in SD rats with Lm-induced constipation phenotypes involve improvements in the IEB.

The potential of the gut microbiome for identifying Alzheimer's disease diagnostic biomarkers and future therapies

Being isolated from the peripheral system by the blood-brain barrier, the brain has long been considered a completely impervious tissue. However, recent findings show that the gut microbiome (GM) influences gastrointestinal and brain disorders such as Alzheimer's disease (AD). Despite several hypotheses, such as neuroinflammation, tau hyperphosphorylation, amyloid plaques, neurofibrillary tangles, and oxidative stress, being proposed to explain the origin and progression of AD, the pathogenesis remains incompletely understood. Epigenetic, molecular, and pathological studies suggest that GM influences AD development and have endeavored to find predictive, sensitive, non-invasive, and accurate biomarkers for early disease diagnosis and monitoring of progression. Given the growing interest in the involvement of GM in AD, current research endeavors to identify prospective gut biomarkers for both preclinical and clinical diagnoses, as well as targeted therapy techniques. Here, we discuss the most recent findings on gut changes in AD, microbiome-based biomarkers, prospective clinical diagnostic uses, and targeted therapy approaches. Furthermore, we addressed herbal components, which could provide a new venue for AD diagnostic and therapy research.

Biotics in atopic diseases: state of the art and future perspectives

Prevalence of allergic diseases has growing in recent decades, being a significant burden for patients and their families. Different environmental factors, acting in early life, can significantly affect the timing and diversity of bacterial colonization and the immune system development. Growing evidence points to a correlation between early life microbial perturbation and development of allergic diseases. Besides, changes in the microbiota in one body site may influence other microbiota communities at distance by different mechanisms, including microbial-derived metabolites, mainly the short chain fatty acids (SCFA). Hence, there has been an increasing interest on the role of "biotics" (probiotics, prebiotics, symbiotics and postbiotics) in shaping dysbiosis and modulating allergic risk. Systemic type 2 inflammation is emerging as a common pathogenetic pathway of allergic diseases, intertwining communication with the gut mcirobiota. The aim of this review was to provide an update overview of the current knowledge of biotics in prevention and treatment of allergic diseases, also addressing research gaps which need to be filled.

Potential application of probiotics in mycotoxicosis reduction in mammals and poultry

Mycotoxins in feedstuffs are considered as a principal worry by food safety authorities worldwide because most of them can be transferred from the feed to food commodities of animal origin, and further consumed by humans. Therefore, effective alternatives for the reduction of the impact of mycotoxins need to be applied in the feed production industry. Applications of beneficial microorganisms (probiotics) can be alternative and applied as feed additives in order to reduce or eliminate the toxic effects of mycotoxins on animals. The aim of this article is to provide information on the role of beneficial microorganisms (probiotics) and point out their role in the reduction of the effect of mycotoxin toxicity in farming animals (mammals and poultry). The objective was to provide a summary of the existing knowledge based on the application of different strains belonging to the group of lactic acid bacteria (LAB) or yeasts that are already or can be future employed in the feed industry, in order to reduce mycotoxicosis presence in mammals and poultry exposed to mycotoxin-contaminated feed. Moreover, an overview of mycotoxins toxicity in mammals and poultry will be presented, and furthermore, the role of the beneficial microorganisms (including probiotics) in the reduction of mycotoxins toxicity (aflatoxicosis, deoxynivalenol, zearalenone, ochratoxin A, and fumonisin toxicities) will be described in detail.

Intestinal anti-inflammatory and visceral analgesic effects of a Serpylli herba extract in an experimental model of irritable bowel syndrome in rats

Ethnopharmacological relevance:Serpylli herba extract (SHE), composed of the aerial parts of wild thyme (Thymus serpyllum L.) (Lamiaceae family), is traditionally used in Europe and North Africa to treat diarrhea, gastric ulcers, intestinal parasites and upper respiratory tract infections. Recently, SHE has generated a great interest for irritable bowel syndrome (IBS) management, probably due to its intestinal anti-inflammatory properties shown in experimental colitis and the fact that its active components could preserve the intestinal barrier integrity, which is altered in patients with IBS.

Aim of study: We aimed to test the effects of a SHE in a rat experimental model resembling human IBS.

Materials and methods: IBS was provoked by deoxycholic acid (DCA). Rats were then treated with SHE (100 mg/kg) or gabapentin (70 mg/kg) and different inflammatory and gut barrier integrity markers were evaluated. Moreover, several gut hypersensitivity and hyperalgesia determinations were performed.

Results: SHE improved referred pain and visceral hypersensitivity. Additionally, SHE enhanced immune status by downregulating of the expression of the pro-inflammatory mediators Il-1β, Il-6, Ifn-γ, Tlr-4, and the inducible enzyme Cox-2, thus inducing visceral analgesia, and promoting the restore of the gut barrier function by upregulating the mucins Muc-2 and Muc-3. These anti-inflammatory effects could be related to its action on mast cells since it significantly inhibited the β-Hexosaminidase production in RBL-2H3 cells. Lastly, SHE also seems to modulate the serotonin pathway by restoring the altered expression of the 5-HT receptors Htr-3 and Htr-4.

Conclusion: SHE could be considered a potential new treatment for IBS, since it ameliorates hypersensitivity, visceral hyperalgesia, and inflammation. These beneficial effects may be due to the inhibition of mast cells degranulation and serotonin pathway.

Mucosal Plasma Cell Activation and Proximity to Nerve Fibres Are Associated with Glycocalyx Reduction in Diarrhoea-Predominant Irritable Bowel Syndrome: Jejunal Barrier Alterations Underlying Clinical Manifestations

Irritable bowel syndrome (IBS) is a disorder of brain-gut interaction characterised by abdominal pain and changes in bowel habits. In the diarrhoea subtype (IBS-D), altered epithelial barrier and mucosal immune activation are associated with clinical manifestations. We aimed to further evaluate plasma cells and epithelial integrity to gain understanding of IBS-D pathophysiology. One mucosal jejunal biopsy and one stool sample were obtained from healthy controls and IBS-D patients. Gastrointestinal symptoms, stress, and depression scores were recorded. In the jejunal mucosa, RNAseq and gene set enrichment analyses were performed. A morphometric analysis by electron microscopy quantified plasma cell activation and proximity to enteric nerves and glycocalyx thickness. Immunoglobulins concentration was assessed in the stool. IBS-D patients showed differential expression of humoral pathways compared to controls. Activation and proximity of plasma cells to nerves and IgG concentration were also higher in IBS-D. Glycocalyx thickness was lower in IBS-D compared to controls, and this reduction correlated with plasma cell activation, proximity to nerves, and clinical symptoms. These results support humoral activity and loss of epithelial integrity as important contributors to gut dysfunction and clinical manifestations in IBS-D. Additional studies are needed to identify the triggers of these alterations to better define IBS-D pathophysiology.

Multi-omics unravel the compromised mucosal barrier function linked to aberrant mucin O-glycans in a pig model

Early weaning stress (EWS) in piglets is associated with intestinal dysfunction. Here, utilizing a pig EWS model to mimic early-life stress (ELS) in humans, we investigated the mechanism of ELS-induced intestinal diseases through integrated multi-omics analyses of proteome, glycome, and microbiome. Our results demonstrated that EWS resulted in disrupted the ileal barrier integrity by reducing tight junction-related gene expression and interfering with cell-cell adhesion paralleled the increased proportion of pathogens such as Escherichia_Shigella and Helicobacter. Furthermore, Proteome data revealed that the accumulation of unfolded proteins and insufficient unfolded protein response (UPR) process caused by EWS led to ER stress. Data from proteome and glycome found that EWS induced aberrant mucin O-glycans, including truncated glycans, reduction in acidic glycans, and increased in fucosylated glycans. In addition, correlation test by taking fucose and inflammatory response into account suggested that enhancement of fucose expression might be a compensatory host response. Taken together, these results extend the comprehensive knowledge of the detrimental impacts and pathogenesis of EWS and help to provide intervention targets for ELS-induced intestinal diseases in the future.

Gut barrier disruption and chronic disease

The intestinal barrier protects the host against gut microbes, food antigens, and toxins present in the gastrointestinal tract. However, gut barrier integrity can be affected by intrinsic and extrinsic factors, including genetic predisposition, the Western diet, antibiotics, alcohol, circadian rhythm disruption, psychological stress, and aging. Chronic disruption of the gut barrier can lead to translocation of microbial components into the body, producing systemic, low-grade inflammation. While the association between gut barrier integrity and inflammation in intestinal diseases is well established, we review here recent studies indicating that the gut barrier and microbiota dysbiosis may contribute to the development of metabolic, autoimmune, and aging-related disorders. Emerging interventions to improve gut barrier integrity and microbiota composition are also described.

Impending Mental Health Issues During Coronavirus Disease 2019 - Time for Personalized Nutrition Based on the Gut Microbiota to Tide Over the Crisis?

Coronavirus disease 2019 (COVID-19) is a major pandemic facing the world today caused by SARS-CoV-2 which has implications on our mental health as well. The uncertain future, fear of job loss, lockdown and negative news all around have taken a heavy toll on the mental health of individuals from across the world. Stress and anxiety can affect the COVID-19 patients even more. Recent study suggests COVID-19 infection may lead to post-traumatic stress disorder (PTSD). Certain prebiotics and probiotics have been shown to have anxiolytic effect through gut microbiota modulation. Incidentally, preliminary report also suggests a differential microbial profile in COVID-19 patients as compared to healthy individuals. Gut microbiota's role in anxiety and depression is well studied. The importance of the "gut-brain" axis has been implicated in overall mental health. It is known that diet, environmental factors and genetics play an important role in shaping gut microbiota. Trials may be initiated to study if personalized diet and supplementation based on individual's gut microbiome profile may improve the general mental well-being of people prone to anxiety during this pandemic. Also, COVID-19 patients may be provided personalized nutritional therapy based on their gut microbiota profile to see if PTSD and anxiety symptoms can be alleviated.

Mucin-Type O-Glycans: Barrier, Microbiota, and Immune Anchors in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which affects about 7 million people globally, is a chronic inflammatory condition of the gastrointestinal tract caused by gut microbiota alterations, immune dysregulation, and genetic and environmental factors. The association of microbial and immune molecules with mucin-type O-glycans has been increasingly noticed by researchers. Mucin is the main component of mucus, which forms a protective barrier between the microbiota and immune cells in the colon. Mucin-type O-glycans alter the diversity of gastrointestinal microorganisms, which in turn increases the level of O-glycosylation of host intestinal proteins via the utilization of glycans. Additionally, alterations in mucin-type O-glycans not only increase the activity and stability of immune cells but are also involved in the maintenance of intestinal mucosal immune tolerance. Although there is accumulating evidence indicating that mucin-type O-glycans play an important role in IBD, there is limited literature that integrates available data to present a complete picture of exactly how O-glycans affect IBD. This review emphasizes the roles of the mucin-type O-glycans in IBD. This seeks to provide a better understanding and encourages future studies on IBD glycosylation and the design of novel glycan-inspired therapies for IBD.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

The Gut-Brain Axis

Preclinical evidence has firmly established bidirectional interactions among the brain, the gut, and the gut microbiome. Candidate signaling molecules and at least three communication channels have been identified. Communication within this system is nonlinear, is bidirectional with multiple feedback loops, and likely involves interactions between different channels. Alterations in gut-brain-microbiome interactions have been identified in rodent models of several digestive, psychiatric, and neurological disorders. While alterations in gut-brain interactions have clearly been established in irritable bowel syndrome, a causative role of the microbiome in irritable bowel syndrome remains to be determined. In the absence of specific microbial targets for more effective therapies, current approaches are limited to dietary interventions and centrally targeted pharmacological and behavioral approaches. A more comprehensive understanding of causative influences within the gut-brain-microbiome system and well-designed randomized controlled trials are needed to translate these exciting preclinical findings into effective therapies. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Clostridium butyricum Induces the Production and Glycosylation of Mucins in HT-29 Cells

C. butyricum is a common gut commensal bacterium, which has many positive functions in human intestine. In this study, we investigated the effects of monosaccharide and its derivatives on the adhesion of C. butyricum to the mucus of HT-29 cells. RNA interference was performed to assess the roles of MUC2 and glycan in the adhesion of C. butyricum to HT-29 cells. The effects of C. butyricum on the glycosylation of mucins were assayed with fluorescence microscope. The expression levels of mucins and glycotransferases were also determined. The results showed that C. butyricum could adhere to the mucins secreted by HT-29 cells. Several kinds of monosaccharides inhibited the adhesion of C. butyricum to HT-29 cells, which suggested that the mucus glycan was the attaching sites of this bacterium. Knockdown of MUC2, FUT2 or GALNT7 significantly decreased the numbers of the bacteria adhering to HT-29 cells. When colonizing on the surface of HT-29 cells, C. butyricum could increase the production of mucins, promote the expression of glycotransferase, and induce the glycosylation of mucins. These results demonstrated that the glycan of mucus played important roles in the adhesion of C. butyricum to HT-29 cells. This study indicates for the first time that C. butyricum possesses the ability to modulate the glycosylation profile of mucus secreted by HT-29 cells. These findings contribute to understanding the mechanism of interaction between colonic epithelial cells and commensal bacteria.

Otilonium Bromide treatment prevents nitrergic functional and morphological changes caused by chronic stress in the distal colon of a rat IBS model

Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder characterized by periods of remission and exacerbation. Among the risk factors to develop IBS, psychosocial stress is widely acknowledged. The water avoidance stress repeatedly applied (rWAS) is considered effective to study IBS etio-pathogenesis. Otilonium bromide (OB), a drug with multiple mechanisms of action, is largely used to treat IBS patients. Orally administered, it concentrates in the large bowel and significantly ameliorates the IBS symptomatology. Presently, we tested whether rWAS rats developed neuro-muscular abnormalities in the distal colon and whether OB treatment prevented them. The investigation was focussed on the nitrergic neurotransmission by combining functional and morphological methodologies. The results confirm rWAS as reliable animal model to investigate the cellular mechanisms responsible for IBS: exposure to one-hour psychosocial stress for 10 days depressed muscle contractility and increased iNOS expression in myenteric neurons. OB treatment counteracted these effects. We hypothesize that these effects are due to the corticotropin-releasing factor (CRF) release, the main mediator of the psychosocial stress, followed by a CRF1receptor activation. OB, that was shown to prevent CRF1r activation, reasonably interrupted the cascade events that bring to the mechanical and immunohistochemical changes affecting rWAS rat colon.