Nutrition, IBD and Gut Microbiota: A Review

Personalized Nutrition in the Management of Female Infertility: New Insights on Chronic Low-Grade Inflammation

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting a mutual association between nutrition and female fertility. Different “fertile” dietary patterns have been studied; however, in humans, conflicting results or weak correlations are often reported, probably because of the individual variations in genome, proteome, metabolome, and microbiome and the extent of exposure to different environmental conditions. In this scenario, “precision nutrition”, namely personalized dietary patterns based on deep phenotyping and on metabolomics, microbiome, and nutrigenetics of each case, might be more efficient for infertile patients than applying a generic nutritional approach. In this review, we report on new insights into the nutritional management of infertile patients, discussing the main nutrigenetic, nutrigenomic, and microbiomic aspects that should be investigated to achieve effective personalized nutritional interventions. Specifically, we will focus on the management of low-grade chronic inflammation, which is associated with several infertility-related diseases.

Exploration of the Potential Relationship Between Gut Microbiota Remodeling Under the Influence of High-Protein Diet and Crohn's Disease

Diet and gut microbiota are both important factors in the pathogenesis of Crohn’s disease, and changes in diet can lead to alteration in gut microbiome. However, there is still insufficient exploration on interaction within the gut microbiota under high-protein diet (HPD) intervention. We analyzed the gut microbial network and marker taxa from patients with Crohn’s disease in public database (GMrepo, https://gmrepo.humangut.info) combined with investigation of the changes of composition and function of intestinal microbiome in mice fed on HPD by metagenomic sequencing. The results showed that there was an indirect negative correlation between Escherichia coli and Lachnospiraceae in patients with Crohn’s disease, and Escherichia coli was a marker for both Crohn’s disease and HPD intervention. Besides, enriched HH_1414 (one of the orthologs in eggNOG) related to tryptophan metabolism was from Helicobacter, whereas reduced orthologs (OGs) mainly contributed by Lachnospiraceae after HPD intervention. Our research indicates that some compositional changes in gut microbiota after HPD intervention are consistent with those in patients with Crohn’s disease, providing insights into potential impact of altered gut microbes under HPD on Crohn’s disease.

Traditional Chinese Medicine Alleviates Ulcerative Colitis via Modulating Gut Microbiota

Ulcerative colitis (UC) is a chronic inflammatory bowel disorder characterized by relapsing and remitting inflammation of the bowel. In recent decades, traditional Chinese medicine (TCM) has been widely used in the therapy of UC. However, its underlying mechanisms have not been sufficiently elucidated. Accumulating studies indicate that the gut microbial dysbiosis is closely related to UC. It has been demonstrated that TCM could alter the composition of intestinal microbiota by enriching beneficial and SCFA-producing bacteria and reducing pathogenic bacteria. In this review, we discussed recent evidence regarding the TCM and its role in modulating gut microbiota for the treatment of UC.

Gut microbiota and allergic diseases in children

The gut microbiota resides in the human gastrointestinal tract, where it plays an important role in maintaining host health. The human gut microbiota is established by the age of 3 years. Studies have revealed that an imbalance in the gut microbiota, termed dysbiosis, occurs due to factors such as cesarean delivery and antibiotic use before the age of 3 years and that dysbiosis is associated with a higher risk of future onset of allergic diseases. Recent advancements in next-generation sequencing methods have revealed the presence of dysbiosis in patients with allergic diseases, which increases attention on the relationship between dysbiosis and the development of allergic diseases. However, there is no unified perspective on the characteristics on dysbiosis or the mechanistic link between dysbiosis and the onset of allergic diseases. Here, we introduce the latest studies on the gut microbiota in children with allergic diseases and present the hypothesis that dysbiosis characterized by fewer butyric acid-producing bacteria leads to fewer regulatory T cells, resulting in allergic disease. Further studies on correcting dysbiosis for the prevention and treatment of allergic diseases are warranted.

Revisiting fibrosis in inflammatory bowel disease: the gut thickens

Intestinal fibrosis, which is usually the consequence of chronic inflammation, is a common complication of inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis. In the past few years, substantial advances have been made in the areas of pathogenesis, diagnosis and management of intestinal fibrosis. Of particular interest have been inflammation-independent mechanisms behind the gut fibrotic process, genetic and environmental risk factors (such as the role of the microbiota), and the generation of new in vitro and in vivo systems to study fibrogenesis in the gut. A huge amount of work has also been done in the area of biomarkers to predict or detect intestinal fibrosis, including novel cross-sectional imaging techniques. In parallel, researchers are embarking on developing and validating clinical trial end points and protocols to test novel antifibrotic agents, although no antifibrotic therapies are currently available. This Review presents the state of the art on the most recently identified pathogenic mechanisms of this serious IBD-related complication, focusing on possible targets of antifibrotic therapies, management strategies, and factors that might predict fibrosis progression or response to treatment.

Inactivation of the Pyrimidine Biosynthesis pyrD Gene Negatively Affects Biofilm Formation and Virulence Determinants in the Crohn’s Disease-Associated Adherent Invasive Escherichia coli LF82 Strain

In Crohn’s disease (CD) patients, the adherent-invasive Escherichia coli (AIEC) pathovar contributes to the chronic inflammation typical of the disease via its ability to invade gut epithelial cells and to survive in macrophages. We show that, in the AIEC strain LF82, inactivation of the pyrD gene, encoding dihydroorotate dehydrogenase (DHOD), an enzyme of the de novo pyrimidine biosynthetic pathway, completely abolished its ability of to grow in a macrophage environment-mimicking culture medium. In addition, pyrD inactivation reduced flagellar motility and strongly affected biofilm formation by downregulating transcription of both type 1 fimbriae and curli subunit genes. Thus, the pyrD gene appears to be essential for several cellular processes involved in AIEC virulence. Interestingly, vidofludimus (VF), a DHOD inhibitor, has been proposed as an effective drug in CD treatment. Despite displaying a potentially similar binding mode for both human and E. coli DHOD in computational molecular docking experiments, VF showed no activity on either growth or virulence-related processes in LF82. Altogether, our results suggest that the crucial role played by the pyrD gene in AIEC virulence, and the presence of structural differences between E. coli and human DHOD allowing for the design of specific inhibitors, make E. coli DHOD a promising target for therapeutical strategies aiming at counteracting chronic inflammation in CD by acting selectively on its bacterial triggers.

Hydroxytyrosol Alleviates Dextran Sulfate Sodium-Induced Colitis by Modulating Inflammatory Responses, Intestinal Barrier, and Microbiome

Hydroxytyrosol (HT), a polyphenol derived from olive oil, was examined against dextran sulfate sodium (DSS)-induced colitis to study its potential in preventing colitis and the underlying mechanisms involved. The low dose and high dose of HT used in mice were 10 and 50 mg/kg, respectively. Research findings have shown that HT is effective in preventing colitis by alleviating the signs of colitis. HT intervention significantly reduces colitis markers such as myeloperoxidase (MPO) and proinflammatory cytokine (IL-6, IL-1β, and TNF-α). Also, mice treated with a high dose of HT showed increased secretion of antioxidant enzymes (heme oxygenase-1 (HO) and anti-inflammatory cytokine (IL-10) by 2.32- and 2.28-fold, respectively, in comparison to the DSS-treated group. Modulation effects of HT on the antioxidant signal pathway (NRF2) and the inflammatory pathway (NF-κB) were confirmed. Meanwhile, HT promoted the regeneration of the intestinal barrier and maintained intestinal functional homeostasis by boosting the regeneration of goblet cells and the expression of mucin protein (Muc2) and tight junction (TJ) proteins (claudin-1, occludin, and Zonula Occludens-1). Moreover, HT intervention obviously transformed the gut microbiota, leading to a lower abundance of inflammation-related microbes (e.g., Bacteroidaceae and Desulfovibrionaceae) and a higher level of short-chain fatty acids (SCFAs) producing bacteria (e.g., Lachnospiraceae, Muribaculaceae, ASF356, and Colidextribacter). Scientific evidence for the beneficial effect of the "Mediterranean diet" (MD) on intestinal health was achieved by elucidating the alleviation mechanism of hydroxytyrosol on colitis.

Gut microbiome alterations in colitis rats after moxibustion at bilateral Tianshu acupoints

Background

The pathogenesis of ulcerative colitis (UC) is closely related to the gut microbiota. Moxibustion has been used to improve the inflammation and gastrointestinal dysfunctions in gastrointestinal disorders such as UC. In this study, we investigated whether moxibustion could improve the gut microbial dysbiosis induced by dextran sulphate sodium.

Methods

Twenty-five male rats were randomly assigned into five groups. The UC rat model was established by administering DSS solution. The rats in the moxibustion and normal rats with moxibustion groups were treated with moxibustion at Tianshu (bilateral, ST25) points, and the mesalazine group rats were treated with mesalazine once daily for 7 consecutive days. Disease activity index (DAI) and haematoxylin and eosin staining were used to evaluate the effect of moxibustion. Gut microbiota profiling was conducted by metagenomic high throughput sequencing technology. The gut microbiota composition, diversity and function were analyzed and compared using metagenomics methodologies.

Results

The DAI scores and histopathology scores in the moxibustion and mesalazine groups were significantly decreased compared with the UC group (P < 0.01). Moxibustion treatment increased abundance levels of Bacteroidetes, Actinobacteria, Ascomycota, Synergistetes and decreased abundance of Firmicutes, Proteobacteria. At the genus level, the abundance of Bacteroides, Bacteroides_bacterium_M7, Prevotella, Bacteroidales_bacterium_H2, were increased and Bacteroides_bacterium_H3, Parabacteroides, Porphyromonas, Alistipes, Parasutterella were decreased in the UC group in comparsion with those in the NG group. Moxibustion increased the abundance of Bacteroides and Bacteroides_bacterium_H3 and decreased Bacteroides_bacterium_M7, Prevotella, Bacteroidales_bacterium_H2. In UC group, the specie Bacteroides_massiliensis was negatively (P < 0.05) correlated with IL-23, Bacteroides_eggerthii_CAG109 and Bacteroides_eggerthii were negatively (P < 0.05) correlated with TGF-β. And the species Prevotella_sp_CAG1031 and Bacteroides_bacterium_H2 were significant positively (P < 0.05) correlated with IL-23. In addition, compare with the normal group, genes involved in certain metabolic pathways, such as energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, were under-represented in the UC group, and these changes in the metabolic pathways could be reversed by moxibustion treatment and mesalazine treatment.

Conclusions

Our findings suggest that moxibustion treatment may protect the host from mucosal inflammation by modulating the intestinal microbiota community.

Systematic review with meta-analysis: environmental and dietary differences of inflammatory bowel disease in Eastern and Western populations

BACKGROUND

While the incidence of inflammatory bowel disease (IBD) has stabilised in the West, it is still increasing in several newly industrialised countries.

AIMS

To investigate whether the environmental and dietary risk factors for IBD differ between Eastern and Western populations METHODS: We systematically searched PubMed, Embase, and Web of Science for studies published from inception through June 30, 2020. Data were pooled using a random effects model.

RESULTS

Overall, 255 studies were assessed. We identified 25 risk factors for IBD, seven of which were noted in both Eastern and Western populations: family history of Crohn's disease [CD] or ulcerative colitis [UC], former smoking (CD/UC), smoking (CD), appendicectomy (CD), tonsillectomy (CD), meat and meat products (CD), and vitamin D deficiency (UC). The remaining factors, including urban living, current smoking, antibiotics, oral contraceptives, caesarean section, isotretinoin, total energy, fat, cholesterol, fatty acids and their sub-classifications, eggs, and soft drinks, were associated with an increased risk of IBD in Western or Eastern populations only. We identified 21 protective factors for IBD, among which eight were common in the East and West: farm animals (CD/UC), Helicobacter pylori infection (CD/UC), multiple births (CD), physical activity (CD), history of breastfeeding (CD), pets (UC), current smoking (UC), and coffee intake (UC). Ten factors conferred protection against IBD in Western populations only, whereas eight factors conferred protection against IBD in Eastern populations only.

CONCLUSIONS

Numerous environmental and dietary factors influenced the development of IBD in both Western and Eastern populations, whereas certain factors influenced IBD risk differently in these populations.

Atractylenolide III inhibits epithelial‑mesenchymal transition in small intestine epithelial cells by activating the AMPK signaling pathway

Compared with the available drugs for the treatment of fibrosis in other organs, the development of intestinal anti-fibrosis drugs is limited. Therefore, it is of practical significance to examine novel drugs to delay or block the development of intestinal fibrosis. The present study aimed to investigate the effect of atractylenolide III (ATL-III) on intestinal fibrosis. An MTT assay was used to detect the effect of ATL-III on the activity of IEC-6 cells. The migration and invasion of fibrotic cells stimulated with TGF-β were determined via wound healing and Transwell assays. An immunofluorescence assay and western blotting were conducted to assess the expression levels of protein associated with epithelial-mesenchymal transition (EMT). The role of the AMP-activated protein kinase (AMPK) pathway was verified using compound C (an AMPK inhibitor) treatment. The results of the present study indicated that ATL-III had no effect on the cells at a dose of 1–20 µmol/l. Moreover, ATL-III can inhibit the invasion and migration of cells induced by TGF-β1, as well as block the EMT process. It was found that ATL-III could also activate the AMPK pathway. Furthermore, compound C reduced the inhibitory effect of ATL-III on stimulated cells, which indicated that the AMPK pathway plays a role in the inhibition process. In conclusion, ATL-III may inhibit the EMT of IEC-6 cells stimulated with TGF-β1 by activating the AMPK signaling pathway.

Gut microbiota in inflammatory bowel disease: a target for therapy not to be missed

In the last years, the gut microbiota achieved great importance, since several studies demonstrated its correlation with the immune system and with the maintenance of intestinal homeostasis, as well as with the regulation of the integrity of the epithelium and the intestinal motility. An imbalance in microbial species promotes a dysbiosis, which has been associated with chronic diseases such as metabolic syndrome, inflammatory diseases, and some behavior disorders. The association with gut microbiota and dysbiosis has been demonstrated mostly in inflammatory bowel disease (IBD). Several studies investigated the application of antibiotics, prebiotics, probiotics, and fecal microbiota transplantation in the treatment strategies for IBD. In this review, we discuss the recent findings on the potential role of the gut microbiota manipulation, with particular attention to bacterial microbiota, which could be implicated for a successful IBD therapeutic approach.

Inflammatory Bowel Disease Therapeutics: A Focus on Probiotic Engineering

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of gastrointestinal (GI) tract with dysregulated mucosal immune functions and disturbed commensal ecosystem of the intestinal lumen. IBD is categorized into two major subsets: Crohn's disease (CD) and ulcerative colitis (UC). Though advent of biologics has shifted the treatment with relatively longer remission compared to small molecule pharmaceuticals, patients still suffer from long-term complications. Since gut-microbiome is now accepted as another human organ holding potential for long-lasting human health, probiotics, and its engineering hold great promises to treat several previously untreatable chronic inflammatory conditions including IBD. Several emerging biological engineering tools have unlimited potential to manipulate probiotic bacterial system. These can produce useful therapeutic biologics with a goal to either ameliorate and/or treat previously untreatable chronic inflammatory conditions. As gut-microbiome is diverse and vary in different ethnic, geographic, and cultural human population, it will be important to develop vision for personalized probiotic treatment and develop the technology thereof to make personalized probiotic options a reality. The aim of this review paper is to present an overview of the current knowledge on both pharmacological and nonpharmacological IBD treatment modalities with a special emphasis on probiotic strains that are developed through the probiotic engineering. These engineered probiotics contain the most anti-inflammatory cytokines found within the human immune response and are currently being used to treat the intestinal inflammation in IBD for the IBD treatment.

Association between Fecal Short-Chain Fatty Acid Levels, Diet, and Body Mass Index in Patients with Inflammatory Bowel Disease

Simple Summary

Inflammatory bowel disease (IBD) is a chronic disorder of the gastrointestinal tract associated with gut inflammation and a disturbance in the amount of bacteria living in the human intestines. As a result, there is a reduction in the production of bacterial metabolites, especially short-chain fatty acids (SCFAs), which are formed from dietary fiber. The aim of our study was to assess the relationship between body mass index (BMI), the type of diet used, and changes in fecal SCFA levels in patients with IBD. We enrolled 61 patients with IBD and 16 patients as a control group. We asked all participants about their daily diet, using the simplified FF questionnaire, and measured the levels of SCFA in their stool samples. Our results revealed that underweight subjects had higher levels of isobutyric acid, whereas those with excessive weight had lower level of butyric, isovaleric, and propionic acids. Furthermore, we observed higher levels of valeric acid in controls than in IBD patients. However, we did not observe a relationship between diet habits and fecal SCFA levels. In conclusion, we demonstrated that BMI is associated with SCFA levels in patients with IBD.

Abstract

Disturbances in the production of bacterial metabolites in the intestine have been reported in diseases associated with dysbiosis, such as inflammatory bowel diseases (IBDs) that include two conditions: Crohn disease (CD) and ulcerative colitis (UC). Short-chain fatty acids (SCFAs) are the main dietary-fiber-derived bacterial metabolites associated with the course of intestinal inflammation. In this study, we assessed the relationship between body mass index (BMI), the type of diet used, and changes in fecal SCFA levels in patients with IBD. We performed nutritional assessments using a nutritional questionnaire and determined fecal SCFA levels in 43 patients with UC, 18 patients with CD, and 16 controls. Our results revealed that subjects with a BMI > 24.99 kg/m² had higher levels of isobutyric acid, whereas those with a BMI < 18.5 kg/m² had lower level of butyric, isovaleric, and propionic acids. Furthermore, we observed higher levels of valeric acid in controls than in IBD patients. We did not reveal a relationship between a specific SCFA and the type of diet, but eating habits appear to be related to the observed changes in the SCFA profile depending on BMI. In conclusion, we demonstrated that BMI is associated with SCFA levels in patients with IBD.

Nutritional Regimes Enriched with Antioxidants as an Efficient Adjuvant for IBD Patients under Infliximab Administration, a Pilot Study

Antioxidants are privileged candidates for the development of adjuvants able to improve the efficiency of pharmacological therapies, particularly for chronic inflammatory syndromes. During the last 20 years, anti-TNFα (tumor necrosis factor alpha) monoclonal antibodies infusion has been the biological therapy most frequently administered but there is still large space for improvement in disease remission rates and maintenance. In this context, nutritional bioactive compounds contained in dietary patterns or included as supplements, may act as adjuvants for the induction and maintenance of IBD (inflammatory bowel diseases) remission. To verify this possibility, a single-center preliminary study (SI-CURA, Soluzioni Innovative per la gestione del paziente e il follow up terapeutico della Colite UlceRosA) was designed and carried out to evaluate whether a daily administration of purple corn supplement could improve the response to Infliximab (IFX) infusion of IBD patients with both Crohn’s disease (CD) and ulcerative colitis (UC). A cohort of 47 patients was enrolled in the study. Biological samples were collected before the first and the third IFX infusion. All patients received nutritional guidelines, 27 of them received commercial red fruit tea with low anthocyanins content, while 20 received a purple corn supplement with a high anthocyanin content. Results show that the administration of an antioxidant-enriched purple corn supplement could improve IFX-mediated disease remission in terms of circulating inflammatory markers. Comparison between CD and UC patients revealed that, at this anthocyanin dosage, the purple corn extract administration improved the IFX response in CD but not in UC patients. Our results may pave the way for a new metacentric study of CD patients, recruiting a wider cohort and followed-up over a longer observational time.

Diet and microbiome in the beginning of the sequence of gut inflammation

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract due, at least partially, to an aberrant and excessive mucosal immune response to gut bacteria in genetically-predisposed individuals under certain environmental factors. The incidence of IBD is rising in western and newly industrialized countries, paralleling the increase of westernized dietary patterns, through new antigens, epithelial function and permeability, epigenetic mechanisms (e.g., DNA methylation), and alteration of the gut microbiome. Alteration in the composition and functionality of the gut microbiome (including bacteria, viruses and fungi) seems to be a nuclear pathogenic factor. The microbiome itself is dynamic, and the changes in food quality, dietary habits, living conditions and hygiene of these western societies, could interact in a complex manner as modulators of dysbiosis, thereby influencing the activation of immune cells' promoting inflammation. The microbiome produces diverse small molecules via several metabolic ways, with the fiber-derived short-chain fatty acids (i.e., butyrate) as main elements and having anti-inflammatory effects. These metabolites and some micronutrients of the diet (i.e., vitamins, folic acid, beta carotene and trace elements) are regulators of innate and adaptive intestinal immune homeostasis. An excessive and unhealthy consumption of sugar, animal fat and a low-vegetable and -fiber diet are risk factors for IBD appearance. Furthermore, metabolism of nutrients in intestinal epithelium and in gut microbiota is altered by inflammation, changing the demand for nutrients needed for homeostasis. This role of food and a reduced gut microbial diversity in causing IBD might also have a prophylactic or therapeutic role for IBD. The relationship between dietary intake, symptoms, and bowel inflammation could lead to dietary and lifestyle recommendations, including diets with abundant fruits, vegetables, olive oil and oily fish, which have anti-inflammatory effects and could prevent dysbiosis and IBD. Dietary modulation and appropriate exclusion diets might be a new complementary management for treatment at disease flares and in refractory patients, even reducing complications, hospitalizations and surgery, through modifying the luminal intestinal environment.

Beneficial Role of Fruits, Their Juices, and Freeze-Dried Powders on Inflammatory Bowel Disease and Related Dysbiosis

Inflammatory bowel disease (IBD) is a group of complex chronic inflammatory conditions affecting the gastrointestinal tract. It is linked to a number of genetic and environmental factors able to perturb the immune-microbiome axis. Diet is the most investigated variable both for its role in the etiology of IBD and for its beneficial potential in the treatment of the symptoms. Dietary products may influence intestinal inflammation through different mechanisms of action, such as the modulation of inflammatory mediators, the alteration of gene expression, changes in gut permeability, and modifications in enteric flora composition. A consisting number of studies deal with the link between nutrition and microbial community, and particular attention is paid to plant-based foods. The effects of the dietary intake of different fruits have been investigated so far. This review aims to present the most recent studies concerning the beneficial potential of fruit consumption on human gut microbiota. Investigated plant species are described, and obtained results are presented and discussed in order to provide an overview of both in vitro and in vivo effects of fruits, their juices, and freeze-dried powders.

The Potential Role of Phytonutrients Flavonoids Influencing Gut Microbiota in the Prophylaxis and Treatment of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), characterized by the chronic inflammation of the gastrointestinal tract, is comprised of two idiopathic chronic intestinal inflammatory diseases. As the incidence of IBD increases, so does the need for safe and effective treatments. Trillions of microorganisms are colonized in the mammalian intestine, coevolve with the host in a symbiotic relationship. Gut microbiota has been reported to be involved in the pathophysiology of IBD. In this regard, phytonutrients flavonoids have received increasing attention for their anti-oxidant and anti-inflammatory activities. In this review, we address recent advances in the interactions among flavonoids, gut microbiota, and IBD. Moreover, their possible potential mechanisms of action in IBD have been discussed. We conclude that there is a complex interaction between flavonoids and gut microbiota. It is expected that flavonoids can change or reshape the gut microbiota to provide important considerations for developing treatments for IBD.

Index-Based Dietary Patterns and Inflammatory Bowel Disease: A Systematic Review of Observational Studies

Diet is one of the most critical factors for inflammatory bowel disease (IBD). A whole dietary pattern should be considered when doing nutrient-based research to preserve the potential for synergism between nutrients. Dietary indices are important tools to evaluate diet quality, and we investigated the associations of it with IBD. Fourteen studies on the relation between index-based dietary patterns and IBD were included. 6 studies showed the relation between index-based dietary patterns and IBD risk, 7 studies explored the dietary indices and progression of IBD, and 1 study investigated the relationship between index and all-cause mortality in IBD patients. These results implied that a high score on the Mediterranean diet was negatively associated with risk and progression of IBD. However, a diet with high inflammatory potential could increase risk and aggravate disease activity in IBD. Dietary scores have the potential to evaluate the association between overall diet quality and risk and progression of IBD. Future randomized controlled trials are required to confirm the effect of the change in dietary score. This review was registered at www.crd.york.ac.uk/prospero/ as CRD42020220926.

The role of fatty acids in Crohn's disease pathophysiology - An overview

Crohn's disease (CD) is an inflammatory bowel disease (IBD) which is characterized by chronic and relapsing inflammation of the gastrointestinal (GI) tract. The etiology of CD is unknown, but factors such as epithelial barrier dysfunction, immune system imbalance, microbiota dysbiosis and environmental influences are thought to be involved in its pathogenesis. Recent studies have shown that short chain fatty acids (SCFAs) and long chain fatty acids (LCFAs) play a vital role in pathophysiology and development of CD by various mechanisms affecting pro- and anti-inflammatory mediators, and maintaining the intestinal homeostasis and regulation of gene expression. SCFAs and LCFAs activate signaling cascades that control immune functions through interaction with cell surface free fatty acid receptors (FFARs), i.e. FFAR1, FFAR2, FFAR3, and FFAR4. This review highlights the role of fatty acids in maintenance of intestinal and immune homeostasis and supports the supplementation of fatty acids as a promising adjunctive treatment for CD.

The Impact of MicroRNAs during Inflammatory Bowel Disease: Effects on the Mucus Layer and Intercellular Junctions for Gut Permeability

Research on inflammatory bowel disease (IBD) has produced mounting evidence for the modulation of microRNAs (miRNAs) during pathogenesis. MiRNAs are small, non-coding RNAs that interfere with the translation of mRNAs. Their high stability in free circulation at various regions of the body allows researchers to utilise miRNAs as biomarkers and as a focus for potential treatments of IBD. Yet, their distinct regulatory roles at the gut epithelial barrier remain elusive due to the fact that there are several external and cellular factors contributing to gut permeability. This review focuses on how miRNAs may compromise two components of the gut epithelium that together form the initial physical barrier: the mucus layer and the intercellular epithelial junctions. Here, we summarise the impact of miRNAs on goblet cell secretion and mucin structure, along with the proper function of various junctional proteins involved in paracellular transport, cell adhesion and communication. Knowledge of how this elaborate network of cells at the gut epithelial barrier becomes compromised as a result of dysregulated miRNA expression, thereby contributing to the development of IBD, will support the generation of miRNA-associated biomarker panels and therapeutic strategies that detect and ameliorate gut permeability.

Dietary Magnesium Alleviates Experimental Murine Colitis through Modulation of Gut Microbiota

Nutritional deficiencies are common in inflammatory bowel diseases (IBD). In patients, magnesium (Mg) deficiency is associated with disease severity, while in murine models, dietary Mg supplementation contributes to restoring mucosal function. Since Mg availability modulates key bacterial functions, including growth and virulence, we investigated whether the beneficial effects of Mg supplementation during colitis might be mediated by gut microbiota. The effects of dietary Mg modulation were assessed in a murine model of dextran sodium sulfate (DSS)-induced colitis by monitoring magnesemia, weight, and fecal consistency. Gut microbiota were analyzed by 16S-rRNA based profiling on fecal samples. Mg supplementation improved microbiota richness in colitic mice, increased abundance of Bifidobacterium and reduced Enterobacteriaceae. KEEG pathway analysis predicted an increase in biosynthetic metabolism, DNA repair and translation pathways during Mg supplementation and in the presence of colitis, while low Mg conditions favored catabolic processes. Thus, dietary Mg supplementation increases bacteria involved in intestinal health and metabolic homeostasis, and reduces bacteria involved in inflammation and associated with human diseases, such as IBD. These findings suggest that Mg supplementation may be a safe and cost-effective strategy to ameliorate disease symptoms and restore a beneficial intestinal flora in IBD patients.

Therapeutic Advances in Gut Microbiome Modulation in Patients with Inflammatory Bowel Disease from Pediatrics to Adulthood

There is mounting evidence that the gut microbiota plays an important role in the pathogenesis of inflammatory bowel disease (IBD). For the past decade, high throughput sequencing-based gut microbiome research has identified characteristic shifts in the composition of the intestinal microbiota in patients with IBD, suggesting that IBD results from alterations in the interactions between intestinal microbes and the host’s mucosal immune system. These studies have been the impetus for the development of new therapeutic approaches targeting the gut microbiome, such as nutritional therapies, probiotics, fecal microbiota transplant and beneficial metabolic derivatives. Innovative technologies can further our understanding of the role the microbiome plays as well as help to evaluate how the different approaches in microbiome modulation impact clinical responses in adult and pediatric patients. In this review, we highlight important microbiome studies in patients with IBD and their response to different microbiome modulation therapies, and describe the differences in therapeutic response between pediatric and adult patient cohorts.

Dysbiosis of Gut Microbiota Is Associated With the Progression of Radiation-Induced Intestinal Injury and Is Alleviated by Oral Compound Probiotics in Mouse Model

The acute radiation-induced intestinal injury (RIII) has raised much concerns and is influenced by non-cytocidal radiation effects including the perturbations in gut microbiota. Although a number of studies have reported alteration in gut microbiota following radiation, little is known about its dynamic variation in the progression of acute RIII. In this study, mouse model were treated with total body irradiation (TBI) of 0, 4, 8 and 12 Gy, and the intestinal tissues and fecal samples were collected at 6 h, 3.5 d and 7 d post radiation. We found that the intestinal injuries were manifested in a radiation dose-dependent manner. Results from 16S rRNA gene sequencing demonstrated that the diversity of gut microbiota was not significantly affected at the prodromal stage of acute RIII, after 6 h of radiation. At the critical stage of acute RIII, after 3.5 d of radiation, the composition of gut microbiota was correlated with the radiation dose. The Pearson’s correlation analysis showed that the relative abundances of phylum Proteobacteria, genera Escherichia-Shigella and Eubacterium xylanophilum_group, and species Lactobacillus murinus exhibited linear correlations with radiation dose. At the recovery stage of acute RIII, after 7 d of radiation, the diversity of gut microbiota decreased as a whole, among which the relative abundance of phyla Proteobacteria and Bacteroides increased, while that of phylum Tenericutes and genus Roseburia decreased. The intra-gastric administration of compound probiotics for 14 days improved the survival duration of mice exposed to 9 Gy TBI, alleviated the intestinal epithelial injury and partially restored the diversity of gut microbiota. Our findings suggest that acute RIII is accompanied by the dysbiosis of gut microbiota, including its decreased diversity, reduced abundance of beneficial bacteria and increased abundance of pathogens. The gut microbiota cannot be used as sensitive biomarkers at the prodromal stage in acute RIII, but are potential biomarkers at the critical stage of acute RIII. The dysbiosis is persistent until the recovery stage of acute RIII, and interventions are needed to restore it. The administration of probiotics is an effective strategy to protect against acute RIII and subsequent dysbiosis.

Cinnamic acid suppresses bone loss via induction of osteoblast differentiation with alteration of gut microbiota

Osteoporosis, a disease characterized by low bone density that poses a high risk of bone fractures, is associated with aging, diet, and menopause. Despite the various known therapeutic methods for osteoporosis treatment, the development of a new therapeutic agent without side effects in long-term use is required. Cinnamic acid (CA) is a phytochemical found in cinnamon. In this study, we evaluated the effect of CA on osteoporosis and demonstrated its mechanism in MC3T3E1 preosteoblasts and ovariectomized mice. CA treatment induced osteoblast differentiation with elevation of osteogenic markers both in vitro and in vivo. CA treatment ameliorated bone loss resulting in better bone indices, increased gut microbial diversity, and recovered changes in the gut microbial composition induced by ovariectomy. These changes were accompanied by an increase in BMP/TGFβ/Smad signaling. Therefore, CA has the potential to suppress the progress of bone loss via the enhancement of bone density through the regulation of gut microbiota.

Fat of the Gut: Epithelial Phospholipids in Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.

Butyrate functions in concert with myeloid-derived suppressor cells recruited by CCR9 to alleviate DSS-induced murine colitis

Ulcerative colitis (UC) is a precancerous disease caused mainly by a combination of genetic susceptibility, environmental factors and microbiota dysbiosis. As a kind of short-chain fatty acid (SCFA), butyrate has been shown to be closely related to the progression of colitis. However, the exact regulatory mechanism of butyrate in colitis needs to be further elucidated. In our current research, the effects of butyrate were examined in a dextran sulfate sodium (DSS)-induced murine colitis model, which simulates human UC. The administration of butyrate significantly reversed the signs of colitis and alleviated colonic histological damage in DSS‑induced colitis. The transcription levels of the main proinflammatory mediators, including tumor necrosis factor-α, interleukin-6 and interleukin-12, were also reduced, as determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). This indicates that butyrate could alleviate DSS-induced colitis by inhibiting proinflammatory mediators. In addition, we found that myeloid-derived suppressor cells (MDSCs), which have an inflammation-relieving effect, did not effectively alleviate DSS‑induced colitis but showed a compensatory increase in the DSS group. However, the compensatory increase in MDSCs in the DSS group significantly decreased after butyrate treatment. Moreover, the chemokine receptor CCR9, which mediates the homing of intestinal immune cells, also showed consistent changes similar to MDSCs. Butyrate alone did not have the aforementioned effects on mice. Thus, butyrate may effectively relieve DSS‑induced colitis by synergistic regulatory effects with MDSCs, which migrate and gather through CCR9 recruitment.

Immunoregulation by Artemisinin and Its Derivatives: A New Role for Old Antimalarial Drugs

Artemisinin and its derivatives (ARTs) are known as conventional antimalarial drugs with clinical safety and efficacy. Youyou Tu was awarded a Nobel Prize in Physiology and Medicine due to her discovery of artemisinin and its therapeutic effects on malaria. Apart from antimalarial effects, mounting evidence has demonstrated that ARTs exert therapeutic effects on inflammation and autoimmune disorders because of their anti-inflammatory and immunoregulatory properties. In this aspect, tremendous progress has been made during the past five to seven years. Therefore, the present review summarizes recent studies that have explored the anti-inflammatory and immunomodulatory effects of ARTs on autoimmune diseases and transplant rejection. In this review, we also discuss the cellular and molecular mechanisms underlying the immunomodulatory effects of ARTs. Recent preclinical studies will help lay the groundwork for clinical trials using ARTs to treat various immune-based disorders, especially autoimmune diseases.

Kynurenine Pathway of Tryptophan Metabolism in Migraine and Functional Gastrointestinal Disorders

Migraine, the leading cause of disability in the population aged below 50, is associated with functional gastrointestinal (GI) disorders (FGIDs) such as functional nausea, cyclic vomiting syndrome, and irritable bowel syndrome (IBS). Conversely, changes in intestinal GI transit may cause diarrhea or constipation and are a component of the autonomic symptoms associated with pre- and post-dorsal phases of migraine attack. These mutual relationships provoke a question on a common trigger in migraine and FGIDs. The kynurenine (l-kyn) pathway (KP) is the major route for l-tryptophan (l-Trp) metabolism and transforms l-Trp into several neuroactive compounds. Changes in KP were reported in both migraine and FGIDs. Migraine was largely untreatable, but several drugs approved lately by the FDA, including monoclonal antibodies for calcitonin gene-related peptide (CGRP) and its receptor, create a hope for a breakthrough in migraine treatment. Derivatives of l-kyn were efficient in pain relief with a mechanism including CGRP inhibition. KP products are important ligands to the aryl hydrocarbon receptor (AhR), whose activation is implicated in the pathogenesis of GI and migraine. Toll-like receptors (TLRs) may play a role in migraine and IBS pathogeneses, and KP metabolites detected downstream of TLR activation may be an IBS marker. The TLR4 signaling was observed in initiating and maintaining migraine-like behavior through myeloid differentiation primary response gene 88 (MyD88) in the mouse. The aim of this review is to justify the view that KP modulation may provide common triggers for migraine and FGIDs with the involvement of TLR, AhR, and MyD88 activation.

Systematic review with meta-analysis: dietary intake in adults with inflammatory bowel disease

BACKGROUND

Poor dietary intake is associated with the development of malnutrition, micronutrient deficiencies, anaemia and osteoporosis in individuals with inflammatory bowel disease. While trials are underway to manipulate the diet of people with IBD, there has been no comprehensive systematic review of the dietary intake of adults with IBD.

AIMS

To conduct a systematic evaluation and meta-analysis of the dietary intake of adults with IBD, including macronutrients, micronutrients and food group data.

METHODS

CINAHL, Embase, Medline and Scopus were searched from 1 January 2000 to 25 September 2020 for cohort, case-control or cross-sectional studies that reported usual dietary intake in adults. Data were pooled and reported as weighted mean intake for: all adults with IBD; Crohn's disease; ulcerative colitis; active disease; remission; males; females. A random-effects meta-analysis model compared intake with healthy individuals.

RESULTS

Forty studies were identified and 19 were included in the meta-analysis. All subgroups of adults with IBD consumed inadequate energy (mean intake in adults with IBD 1980 ± 130 kcal), fibre (14 ± 4 g), folate (246 ± 33 mg) and calcium (529 ± 114 mg) per day. Intake of breads and cereals, legumes, fruit, vegetables and dairy were inadequate. Compared to healthy individuals, adults with IBD consume significantly less dietary fibre (SMD -0.59; 95% CI: -0.73, -0.46).

CONCLUSIONS

This review provides improved clarity about the dietary intake of adults with IBD. Future attention is required to improve diet quality and increase understanding of factors influencing dietary intake in IBD.

Phase angle through electrical bioimpedance as a predictor of cellularity in inflammatory bowel disease

It is estimated in Western industrialized countries that inflammatory bowel disease (IBD) has a prevalence of 1 for every 200 inhabitants. In the past, the fat mass disproportionate increase in relation to the fat-free mass was considered uncommon in patients with IBD, due to the observation of the disease being more common with weight loss and malnutrition. However, more in-depth investigations demonstrate that the fat/lean mass disproportion stands out both in prevalence in patients with new diagnoses of ulcerative colitis or Crohn's disease as well as a factor of poor prognosis to the natural evolution of the disease or to the therapeutic response. Another important aspect associated with obesity in IBD is the increased risk of drug clearance [including anti-tumor necrosis factor (TNF) and anti-integrin agents], resulting in short half-life and low trough drug concentrations, since the levels of TNF secreted by adipocytes sequester anti-TNF agents, which could result in suboptimal response to biologics. In view of these characteristic aspects of the inflammatory process of IBD, the identification of cellular functioning is necessary, which can be associated with the staging of the underlying disease, biochemical parameters, and body composition, helping as an indicator for a more accurate clinical and nutritional conduct.

Diet quality, gut microbiota, and microRNAs associated with mild cognitive impairment in middle-aged and elderly Chinese population

BACKGROUND

Diet, the gut microbiota, and microRNAs (miRNAs) have been recognized as factors possibly influencing the pathogenesis of Alzheimer's disease. However, the combined role of diet, the gut microbiota, and miRNAs in mild cognitive impairment (MCI) has not been extensively investigated.

OBJECTIVES

To examine the associations among diet quality, the gut microbiota, miRNAs, and risks of MCI in middle-aged and elderly Chinese population.

METHODS

Participants were drawn from the Effects and Mechanism Investigation of Cholesterol and Oxysterol on Alzheimer's disease (EMCOA) study. We included 2239 participants who completed comprehensive cognitive tests and dietary surveys at baseline and follow-up. Chinese Dietary Guidelines Index 2018 (CDGI-2018), Energy-Adjusted Dietary Inflammatory Index (E-DII) and Healthy Lifestyle Score (HLS) values were calculated based on data from a standard questionnaire. Changes of gut microbiota and serum miRNA expression were detected in 75 MCI and 52 healthy participants. The receiver operating characteristic curve was performed based on a logistic regression model distinguishing patients with MCI from healthy controls.

RESULTS

Higher CDGI-2018 (RR, 0.75; 95% CI: 0.58-0.98) and HLS (RR, 0.54; 95% CI: 0.34-0.84) values and lower E-DII (RR, 1.46; 95% CI: 1.14-1.87) values were significantly associated with a lower risk of MCI. Lower microbial diversity and abundance of Faecalibacterium, unidentified Ruminococcaceae, and Alistipes were found in MCI participants compared with healthy controls. The abundance of ProteobacteriaandGammaproteobacteria was higher in MCI participants and was correlated with hsa-let-7g-5p, hsa-miR-107, and hsa-miR-186-3p. The predictive signatures of diet quality scores, differential gut microbiota, and serum miRNAs had good performance on distinguishing MCI participants from healthy individuals (AUC = 0.91).

CONCLUSIONS

A better diet quality is associated with a lower risk of MCI, which may be mediated by the microbiota composition and miRNA expression. These findings suggest that diet, the gut microbiota, and miRNAs may serve as a combinatorial biomarker to identify MCI patients and provide new insight for the diagnosis and prevention of MCI. This study was registered at the Chinese Clinical Trial Registry as ChiCTROOC-17011882.

The Mechanism of Secretion and Metabolism of Gut-Derived 5-Hydroxytryptamine

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a metabolite of tryptophan and is reported to modulate the development and neurogenesis of the enteric nervous system, gut motility, secretion, inflammation, sensation, and epithelial development. Approximately 95% of 5-HT in the body is synthesized and secreted by enterochromaffin (EC) cells, the most common type of neuroendocrine cells in the gastrointestinal (GI) tract, through sensing signals from the intestinal lumen and the circulatory system. Gut microbiota, nutrients, and hormones are the main factors that play a vital role in regulating 5-HT secretion by EC cells. Apart from being an important neurotransmitter and a paracrine signaling molecule in the gut, gut-derived 5-HT was also shown to exert other biological functions (in autism and depression) far beyond the gut. Moreover, studies conducted on the regulation of 5-HT in the immune system demonstrated that 5-HT exerts anti-inflammatory and proinflammatory effects on the gut by binding to different receptors under intestinal inflammatory conditions. Understanding the regulatory mechanisms through which 5-HT participates in cell metabolism and physiology can provide potential therapeutic strategies for treating intestinal diseases. Herein, we review recent evidence to recapitulate the mechanisms of synthesis, secretion, regulation, and biofunction of 5-HT to improve the nutrition and health of humans.

Metabolic Host-Microbiota Interactions in Autophagy and the Pathogenesis of Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD) is a family of conditions characterized by chronic, relapsing inflammation of the gastrointestinal tract. IBD afflicts over 3 million adults in the United States and shows increasing prevalence in the Westernized world. Current IBD treatments center on modulation of the damaging inflammatory response and carry risks such as immunosuppression, while the development of more effective treatments is hampered by our poor understanding of the molecular mechanisms of IBD pathogenesis. Previous genome-wide association studies (GWAS) have demonstrated that gene variants linked to the cellular response to microorganisms are most strongly associated with an increased risk of IBD. These studies are supported by mechanistic work demonstrating that IBD-associated polymorphisms compromise the intestine's anti-microbial defense. In this review, we summarize the current knowledge regarding IBD as a disease of defects in host-microbe interactions and discuss potential avenues for targeting this mechanism for future therapeutic development.

Beneficial Effects of Organosulfur Compounds from Allium cepa on Gut Health: A Systematic Review

Dietary changes affect the composition and structure of gut microbiota (GM) in animals and humans. One of the beneficial effects of consuming products derived from plants is the positive influence on immunity and gastrointestinal health. Species belonging to the genus Allium contain many organosulfur compounds (OSCs) that have been widely studied showing their biological properties and beneficial effects on intestinal health and GM. This is the first systematic review of OSCs from Allium performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and it is based on the evidence that we found in literature about the benefits on the GM and intestinal health demonstrated by OSCs from Allium, and specifically from onion. OSCs from Allium cepa have shown a significant antibacterial activity against a broad spectrum of antibiotic-resistant Gram-positive and Gram-negative bacteria. In addition, the intake of OSCs from onion was able to modulate the composition of GM, increasing the beneficial bacterial populations in animal models. Moreover, the beneficial effects observed in murine models of colitis suggest that these compounds could be suitable candidates for the treatment of inflammatory bowel disease (IBD) or reverse the dysbiosis caused by a high-fat diet (HFD). Despite the evidence found both in vitro and in vivo, we have not found any article that tested OSCs different from allicin in clinical trials or dietary intervention studies in humans. In this sense, it would be interesting to conduct new research that tests the benefits of these compounds in human GM.

Linking Inflammatory Bowel Disease Symptoms to Changes in the Gut Microbiome Structure and Function

Inflammatory bowel disease (IBD) is a chronic disease of the gastrointestinal tract that is often characterized by abdominal pain, rectal bleeding, inflammation, and weight loss. Many studies have posited that the gut microbiome may play an integral role in the onset and exacerbation of IBD. Here, we present a novel computational analysis of a previously published IBD dataset. This dataset consists of shotgun sequence data generated from fecal samples collected from individuals with IBD and an internal control group. Utilizing multiple external controls, together with appropriate techniques to handle the compositionality aspect of sequence data, our computational framework can identify and corroborate differences in the taxonomic profiles, bacterial association networks, and functional capacity within the IBD gut microbiome. Our analysis identified 42 bacterial species that are differentially abundant between IBD and every control group (one internal control and two external controls) with at least a twofold difference. Of the 42 species, 34 were significantly elevated in IBD, relative to every other control. These 34 species were still present in the control groups and appear to play important roles, according to network centrality and degree, in all bacterial association networks. Many of the species elevated in IBD have been implicated in modulating the immune response, mucin degradation, antibiotic resistance, and inflammation. We also identified elevated relative abundances of protein families related to signal transduction, sporulation and germination, and polysaccharide degradation as well as decreased relative abundance of protein families related to menaquinone and ubiquinone biosynthesis. Finally, we identified differences in functional capacities between IBD and healthy controls, and subsequently linked the changes in the functional capacity to previously published clinical research and to symptoms that commonly occur in IBD.

Roles of PRR-Mediated Signaling Pathways in the Regulation of Oxidative Stress and Inflammatory Diseases

Oxidative stress is a major contributor to the pathogenesis of various inflammatory diseases. Accumulating evidence has shown that oxidative stress is characterized by the overproduction of reactive oxygen species (ROS). Previous reviews have highlighted inflammatory signaling pathways, biomarkers, molecular targets, and pathogenetic functions mediated by oxidative stress in various diseases. The inflammatory signaling cascades are initiated through the recognition of host cell-derived damage associated molecular patterns (DAMPs) and microorganism-derived pathogen associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). In this review, the effects of PRRs from the Toll-like (TLRs), the retinoic acid-induced gene I (RIG-I)-like receptors (RLRs) and the NOD-like (NLRs) families, and the activation of these signaling pathways in regulating the production of ROS and/or oxidative stress are summarized. Furthermore, important directions for future studies, especially for pathogen-induced signaling pathways through oxidative stress are also reviewed. The present review will highlight potential therapeutic strategies relevant to inflammatory diseases based on the correlations between ROS regulation and PRRs-mediated signaling pathways.

A Gut-Ex-Vivo System to Study Gut Inflammation Associated to Inflammatory Bowel Disease (IBD)

Simple Summary

Inflammatory Bowel Disease (IBD) is a complex and multifactorial systemic disease of the gastrointestinal tract, characterized by chronic inflammation, thus resulting in tissue damage and, occasionally, in cancer development. Although the precise origin is still elusive, it is widely considered a disease of modern society, caused by a complex interaction between environment, genetic, immune system, and gut microflora (microbiota). Potentially affected by all the above-mentioned variables, which interplay are highly heterogeneous, the disease appears to be patient-specific. The latter phenomenon, together with the uncertain origin, also contributes to the lack of optimal clinical treatment of these patients. Therefore, the development of appropriate models is crucial to push the research forward and to define new valuable therapeutic approaches. Although tissue biopsies and/or animal models represent the best models to study IBD onset, progression, and clinical interventions, they are both affected by limitations such as invasiveness, cost- and time-consuming, and ethical issues such as animal suffering. Here we propose a novel approach based on the cultivation of mouse tissues (colon) in an ex vivo microfluidic device (Gut-Ex-Vivo System, GEVS) to study IBD. We demonstrate that explanted mouse tissues cultivated in our GEVS can be appropriately stimulated to recapitulate the onset of the disease, in a time- and cost- effective manner.

Abstract

Inflammatory bowel disease (IBD) is a complex, chronic, and dysregulated inflammatory condition which etiology is still largely unknown. Its prognosis and disease progression are highly variable and unpredictable. IBD comprises several heterogeneous inflammatory conditions ranging from Ulcerative Colitis (UC) to Crohn’s Disease (CD). Importantly, a definite, well-established, and effective clinical treatment for these pathologies is still lacking. The urgent need for treatment is further supported by the notion that patients affected by UC or CD are also at risk of developing cancer. Therefore, a deeper understanding of the molecular mechanisms at the basis of IBD development and progression is strictly required to design new and efficient therapeutic regimens. Although the development of animal models has undoubtedly facilitated the study of IBD, such in vivo approaches are often expensive and time-consuming. Here we propose an organ ex vivo culture (Gut-Ex-Vivo system, GEVS) based on colon from Balb/c mice cultivated in a dynamic condition, able to model the biochemical and morphological features of the mouse models exposed to DNBS (5–12 days), in 5 h. Indeed, upon DNBS exposure, we observed a dose-dependent: (i) up-regulation of the stress-related protein transglutaminase 2 (TG2); (ii) increased intestinal permeability associated with deregulated tight junction protein expression; (iii) increased expression of pro-inflammatory cytokines, such as TNFα, IFNγ, IL1β, IL6, IL17A, and IL15; (iv) down-regulation of the anti-inflammatory IL10; and (v) induction of Endoplasmic Reticulum stress (ER stress), all markers of IBD. Altogether, these data indicate that the proposed model can be efficiently used to study the pathogenesis of IBD, in a time- and cost-effective manner.

Inflammatory Potential of the Diet and Incidence of Crohn's Disease and Ulcerative Colitis in the EPIC-Spain Cohort

Diet may influence the development of inflammatory bowel disease through the modulation of inflammation. We investigated whether the inflammatory potential of the diet is associated with the risk of Crohn’s disease (CD) and ulcerative colitis (UC) in the Spanish cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Spain). The study included 32,633 participants aged 29–69 years. The inflammatory potential of the diet was measured by using an inflammatory score of the diet (ISD) based on a baseline dietary history questionnaire. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During 21 years (674,547 person-years) of follow-up, 32 and 57 participants developed CD and UC, respectively. In multivariable analysis, a one-standard deviation (SD) increment in the ISD (two-unit increase) was associated with a higher risk of CD (HR of 1.71; 95% CI: 1.05–2.80; p = 0.031). By contrast, ISD was not associated with UC (HR for one-SD increment of 0.89; 95% CI: 0.66–1.19; p = 0.436). Our results suggest that consuming a more pro-inflammatory diet may contribute to the risk of CD, supporting that a healthy diet might be beneficial in its prevention. Further, larger studies are needed to verify these findings.

Can control of gut microbiota be a future therapeutic option for inflammatory bowel disease?

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract encompassing two main clinical entities, Crohn’s disease and ulcerative colitis. Accumulated evidence indicates that an aberrant immune activation caused by the interplay of genetic susceptibility and environmental impact on the gut microbiota may be involved in the pathogenesis of IBD. Rapid advances in next-generation sequencing technology have enabled a number of studies to identify the alteration of the gut microbiota, termed dysbiosis, in IBD. Moreover, the alteration in the metabolites derived from the gut microbiota in IBD has also been described in many studies. Therefore, microbiota-based interventions such as fecal microbiota transplantation (FMT) have attracted attention as a novel therapeutic option in IBD. However, in clinical trials, the efficacy of FMT for IBD remains controversial. Additional basic and clinical studies are required to validate whether FMT can assume a complementary role in the treatment of IBD. The present review provides a synopsis on dysbiosis in IBD and on the association between the gut microbiota and the pathogenesis of IBD. In addition, we summarize the use of probiotics in IBD and the results of current clinical trials of FMT for IBD.

Tryptophan-kynurenine metabolism: a link between the gut and brain for depression in inflammatory bowel disease

Inflammatory bowel disease (IBD), which mainly includes ulcerative colitis (UC) and Crohn's disease (CD), is a group of chronic bowel diseases that are characterized by abdominal pain, diarrhea, and bloody stools. IBD is strongly associated with depression, and its patients have a higher incidence of depression than the general population. Depression also adversely affects the quality of life and disease prognosis of patients with IBD. The tryptophan-kynurenine metabolic pathway degrades more than 90% of tryptophan (TRP) throughout the body, with indoleamine 2,3-dioxygenase (IDO), the key metabolic enzyme, being activated in the inflammatory environment. A series of metabolites of the pathway are neurologically active, among which kynerunic acid (KYNA) and quinolinic acid (QUIN) are molecules of great interest in recent studies on the mechanisms of inflammation-induced depression. In this review, the relationship between depression in IBD and the tryptophan-kynurenine metabolic pathway is overviewed in the light of recent publications.

Synergic interactions between polyphenols and gut microbiota in mitigating inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are a group of chronic and recurring inflammatory conditions in the colon and intestine. Their etiology is not fully understood but involves the combination of gut dysbiosis, genetics, immune functions, and environmental factors including diet. Polyphenols from plant-based food synergistically interact with gut microbiota to suppress inflammation and alleviate symptoms of IBD. Polyphenols increase the diversity of gut microbiota, improve the relative abundance of beneficial bacteria, and inhibit the pathogenic species. Polyphenols not absorbed in the small intestine are catabolized in the colon by microbiota into microbial metabolites, many of which have higher anti-inflammatory activity and bioavailability than their precursors. The polyphenols and their microbial metabolites alleviate IBD through reduction of oxidative stress, inhibition of inflammatory cytokines secretion (TNF-α, IL-6, IL-8, and IL-1β), suppression of NF-κB, upregulation of Nrf2, gut barrier protection, and modulation of immune function. Future studies are needed to discover unknown microbial metabolites of polyphenols and correlate specific gut microbes with microbial metabolites and IBD mitigating activity. A better knowledge of the synergistic interactions between polyphenols and gut microbiota will help to devise more effective prevention strategies for IBD. This review focuses on the role of polyphenols, gut microbiota and their synergistic interactions on the alleviation of IBD as well as current trends and future directions of IBD management.

Dietary intake patterns among adults with inflammatory bowel disease in the United States, 2015

BACKGROUND

Dietary behavior and nutrient intake patterns among U.S. men and women with inflammatory bowel disease (IBD) are unclear at the population level.

METHODS

This cross-sectional study compared dietary intake patterns among U.S. adults (aged ≥18 years) with and without IBD in the 2015 National Health Interview Survey (N = 33,626). Age-standardized weighted prevalences for intake of fruits, vegetables, dairy, whole grain bread, dietary fiber, calcium, total added sugars, sugar-sweetened beverages (SSBs), processed meat, and supplement use were compared between adults with and without IBD by sex.

RESULTS

In 2015, an estimated 3 million adults (1.3%) reported IBD. Compared with adults without IBD, adults with IBD were more likely to be older, non-Hispanic white, not currently working, former smokers, and former alcohol drinkers. Overall, dietary behaviors were similar among adults with and without IBD. However, adults with IBD were more likely to take vitamin D supplements (31.5% vs 18.8%) and consume dietary fiber <16.7 grams(g)/day, the amount that 50% of U.S. adults consumed (51.8% vs 44.1%), than those without IBD. Compared with their counterparts, men with IBD were more likely to consume vegetables ≥1 time/day (84.9% vs 76.0%) and take any supplement (59.6% vs 46.0%); women with IBD were more likely to have SSBs ≥2 times/day (26.8% vs 17.8%) and total added sugars ≥14.6 teaspoons(tsp)/day, the amount that 50% of U.S. adults consumed (55.3% vs 46.7%).

CONCLUSIONS

Adopting a healthy diet, especially limiting added sugars intake among women with IBD, might be important for the overall health.

Inflammatory Bowel Diseases: Is There a Role for Nutritional Suggestions?

Nutrition has an important impact on inflammatory bowel diseases (IBD). In particular, several studies have addressed its role in their pathogenesis, showing how the incidence of IBD significantly increased in recent years. Meanwhile, nutrition should be considered a component of the treatment of the disease, both as a therapy itself, and especially in the perspective of correcting the various nutritional deficiencies shown by these patients. In this perspective, nutritional suggestions are very important even in the most severe forms of IBD, requiring hospitalization or surgical treatment. Although current knowledge about nutrition in IBD is increasing over time, nutritional suggestions are often underestimated by clinicians. This narrative review is an update summary of current knowledge on nutritional suggestions in IBD, in order to address the impact of nutrition on pathogenesis, micro- and macro-nutrients deficiencies (especially in the case of sarcopenia and obesity), as well as in hospitalized patients.

A Narrative Review of Gut-Muscle Axis and Sarcopenia: The Potential Role of Gut Microbiota

Sarcopenia is a multifactorial disease related to aging, chronic inflammation, insufficient nutrition, and physical inactivity. Previous studies have suggested that there is a relationship between sarcopenia and gut microbiota,namely, the gut-muscle axis. The present review highlights that the gut microbiota can affect muscle mass and muscle function from inflammation and immunity,substance and energy metabolism, endocrine and insulin sensitivity, etc., directly or indirectly establishing a connection with sarcopenia, thereby realizing the “gut-muscle axis”.

Luteolin suppresses 5-hydroxytryptamine elevation in stimulated RBL-2H3 cells and experimental colitis mice

Increased 5-hydroxytryptamine may be associated with the development and progression of inflammatory bowel disease. In this study, we examined the suppressive effect of flavonoids on the increased intra- and extracellular 5-hydroxytryptamine levels in rat mast RBL-2H3 cells, known to produce 5-hydroxytryptamine by the phorbol 12-myristate 13-acetate stimulation. Among the flavonoids examined, luteolin and quercetin significantly reduced the cellular 5-hydroxytryptamine concentration. Gene and protein expression analyses revealed that luteolin significantly suppressed cellular tryptophan hydroxylase 1 expression induced by phorbol 12-myristate 13-acetate stimulation. Mitogen-activated protein kinase/extracellular signal-regulated kinase signaling was also suppressed by luteolin, suggesting that this pathway is one of targets of 5-hydroxytryptamine modulation by luteolin. An in vivo experimental colitis model was prepared by administering 2.5% dextran sodium sulfate in drinking water to C57BL/6 mice for seven days. The ingestion of 0.1% dietary luteolin suppressed the increasing 5-hydroxytryptamine in the colorectal mucosa. In conclusion, luteolin possesses a suppressive effect on extensive 5-hydroxytryptamine formation in both experimental RBL-2H3 cells and colitis models.

Lychee (Litchi chinensis Sonn.) Pulp Phenolics Activate the Short-Chain Fatty Acid-Free Fatty Acid Receptor Anti-inflammatory Pathway by Regulating Microbiota and Mitigate Intestinal Barrier Damage in Dextran Sulfate Sodium-Induced Colitis in Mice

The preventive effect of lychee pulp phenolics (LPP) on dextran sulfate sodium (DSS)-induced colitis of mice and its underlying mechanisms were investigated in this research. LPP supplementation mitigated DSS-induced breakage of the gut barrier as evidenced by the increased tight junction proteins and the enhanced integrity of epithelial cells. Both LPP and 5-ASA treatments could downregulate the expressions of toll-like receptor 4 (TLR-4), NOD protein-like receptor 3 (NLRP3), and proinflammatory cytokines to normal levels. Notably, treatment with LPP at a dosage of 500 mg/kg/day effectively upregulated FFAR2 and FFAR3 expression and contents of short-chain fatty acids (SCFAs), suggesting the activation of the SCFA-FFAR (free fatty acid receptor) pathway. Consistently, the abundances of probiotic taxa and microbiota (Akkermansia, Lactobacillus, Coprococcus, and Bacteroides uniformis) associated with SCFA synthesis were elevated, whereas harmful bacteria (Enterococcus and Aggregatibacter) were suppressed. These data indicate that LPP ameliorates gut barrier damage, activates the microbiota-SCFA-FFAR signaling cascade, and suppresses the TLR4/NLRP3-NF-κB pathway, and therefore, LPP supplementation could be a promising way to protect the intestinal tract.

Pharmacological and Metabolic Significance of Bile Acids in Retinal Diseases

Bile acids (BAs) are amphipathic sterols primarily synthesized from cholesterol in the liver and released in the intestinal lumen upon food intake. BAs play important roles in micellination of dietary lipids, stimulating bile flow, promoting biliary phospholipid secretion, and regulating cholesterol synthesis and elimination. Emerging evidence, however, suggests that, aside from their conventional biological function, BAs are also important signaling molecules and therapeutic tools. In the last decade, the therapeutic applications of BAs in the treatment of ocular diseases have gained great interest. Despite the identification of BA synthesis, metabolism, and recycling in ocular tissues, much remains unknown with regards to their biological significance in the eye. Additionally, as gut microbiota directly affects the quality of circulating BAs, their analysis could derive important information on changes occurring in this microenvironment. This review aims at providing an overview of BA metabolism and biological function with a focus on their potential therapeutic and diagnostic use for retinal diseases.

Progress in understanding of mechanism of dietary therapy for ulcerative colitis with regard to intestinal microbiota

The pathogenesis of ulcerative colitis is closely related to the complex interaction between heredity, environment, and intestinal microbiota. Intestinal dysbiosis is not only the cause of ulcerative colitis, but also the pathological result of ulcerative colitis. Dietary therapies have been found to modulate the microbiota to alter the effects of environmental factors on ulcerative colitis. Dietary pattern is related to the pathogenesis, development, and prognosis of ulcerative colitis, and the role of diet in ulcerative colitis has attracted more and more attention. This article reviews the mechanisms by which dietary therapy treats ulcerative colitis with regard to regulating the brain-gut functional axis, regulating the immune function, and protecting the intestinal mucosal barrier by modulating intestinal microbiota.

Gut microbiome and Mediterranean diet in the context of obesity. Current knowledge, perspectives and potential therapeutic targets

Mediterranean Diet has been recognized as one of the healthiest and sustainable dietary patterns worldwide, based on the food habits of people living in the Mediterranean region. It is focused on a plant-based cuisine combining local agricultural products and moderate intake of fish. As eating habits seem to exert a major impact on the composition of gut microbiota, numerous studies show that an adherence to the Mediterranean diet positively influences the microbiome ecosystem network. This has a profound effect on multiple host metabolic pathways and plays a major role in immune and metabolic homeostasis. Among metabolic disorders, obesity represents a major health issue where Mediterranean Dietary regime could possibly slowdown its spread. The aim of this review is to emphasize the interaction between diet and gut microbiota and the potential beneficial effects of Mediterranean diet on metabolic disorders like obesity, which is responsible for the development of many noncommunicable diseases.