Intestinal microbiota in inflammatory bowel disease: Friend of foe?

Saudi consensus guidance for the diagnosis and management of inflammatory bowel disease in children and adolescents

ABSTRACT

The management of inflammatory bowel disease (IBD) in children and adolescents is challenging. Clear evidence-based guidelines are required for this population. This article provides recommendations for managing IBD in Saudi children and adolescents aged 6-19 years, developed by the Saudi Ministry of Health in collaboration with the Saudi Society of Clinical Pharmacy and the Saudi Gastroenterology Association. All 57 guideline statements are based on the most up-to-date information for the diagnosis and management of pediatric IBD.

The Role of Fecal Microbiota Transplantation in IBD

Gut microbiota dysbiosis has a critical role in the pathogenesis of inflammatory bowel diseases, prompting the exploration of novel therapeutic approaches like fecal microbiota transplantation, which involves the transfer of fecal microbiota from a healthy donor to a recipient with the aim of restoring a balanced microbial community and attenuating inflammation. Fecal microbiota transplantation may exert beneficial effects in inflammatory bowel disease through modulation of immune responses, restoration of mucosal barrier integrity, and alteration of microbial metabolites. It could alter disease course and prevent flares, although long-term durability and safety data are lacking. This review provides a summary of current evidence on fecal microbiota transplantation in inflammatory bowel disease management, focusing on its challenges, such as variability in donor selection criteria, standardization of transplant protocols, and long-term outcomes post-transplantation.

Dietary L-arabinose-induced gut dysbiosis exacerbates Salmonella infection outcome

The gut microbiota is essential for providing colonization resistance against pathogens. Dietary sugars markedly shift the composition of the intestinal microbiota and alter host susceptibility to enteric infections. Here, we demonstrate the effect of L-arabinose on bacterial infection by using a mouse infection model with Salmonella enterica serovar Typhimurium (S. Tm). In the presence of microbiota, L-arabinose induces a dramatic expansion of Enterobacteriaceae, thereby decreasing the microbiota diversity and causing more severe systemic infection. However, L-arabinose supplementation does not alter the disease progression of Salmonella infection in a microbiota-depleted mouse model. More importantly, short-term supplementation of L-arabinose fails to exert anti-diabetic effects in Salmonella-infected hyperglycemia mice and still promotes infection. Overall, our work reveals that a high intake of dietary L-arabinose supports a bloom of Enterobacteriaceae in Salmonella-infected gut, further accelerating the process of systemic infection.IMPORTANCEL-arabinose is a promising natural sweetener and food additive for the regulation of hyperglycemia. Since diabetic subjects are more susceptible to infections, the safety of dietary L-arabinose in diabetic patients experiencing infection remains a concern. Our findings reveal that L-arabinose exacerbates Salmonella infection outcome by inducing gut microbiota dysbiosis in mice. High dietary intake of L-arabinose may be deleterious for diabetic individuals undergoing infection.

The causal relationship between inflammatory bowel diseases and erythema nodosum: a bidirectional two-sample mendelian randomization study

BACKGROUND

Individuals with inflammatory bowel disease (IBD) exhibit a heightened likelihood of developing erythema nodosum (EN), but the presence of causal link is unknown. The purpose of the present research was to investigate this connection using a bidirectional two-sample Mendelian randomization (MR) analysis.

METHODS

Summarized statistics for EN were sourced from the FinnGen consortium of European ancestry. The International Inflammatory Bowel Disease Genetic Consortium (IBDGC) was used to extract summary data for IBD. The inverse variance weighted (IVW) technique was the major method used to determine the causative link between them.

RESULTS

The study evaluated the reciprocal causal link between IBD and EN. The IVW technique confirmed a positive causal link between IBD and EN (OR = 1.237, 95% CI: 1.109-1.37, p = 1.43 × 10- 8), as well as a strong causality connection between Crohn's disease (CD) and EN (OR = 1.248, 95% CI: 1.156-1.348, p = 1.00 × 10- 4). Nevertheless, a causal connection between ulcerative colitis (UC) and EN could not be established by the data. The reverse MR research findings indicated that analysis indicated that an increase in EN risks decreased the likelihood of UC (OR = 0.927, 95% CI: 0.861-0.997, p = 0.041), but the causal association of EN to IBD and CD could not be established.

CONCLUSION

This investigation confirmed that IBD and CD had a causal connection with EN, whereas UC did not. In addition, EN may decrease the likelihood of UC. Further study must be performed to uncover the underlying pathophysiological mechanisms producing that connection.

Mapping Crohn's Disease Pathogenesis with Mycobacterium paratuberculosis: A Hijacking by a Stealth Pathogen

Mycobacterium avium ssp. paratuberculosis (MAP) has been implicated in the development of Crohn's disease (CD) for over a century. Similarities have been noted between the (histo)pathological presentation of MAP in ruminants, termed Johne's disease (JD), and appearances in humans with CD. Analyses of disease presentation and pathology suggest a multi-step process occurs that consists of MAP infection, dysbiosis of the gut microbiome, and dietary influences. Each step has a role in the disease development and requires a better understanding to implementing combination therapies, such as antibiotics, vaccination, faecal microbiota transplants (FMT) and dietary plans. To optimise responses, each must be tailored directly to the activity of MAP, otherwise therapies are open to interpretation without microbiological evidence that the organism is present and has been influenced. Microscopy and histopathology enables studies of the mycobacterium in situ and how the associated disease processes manifest in the patient e.g., granulomas, fissuring, etc. The challenge for researchers has been to prove the relationship between MAP and CD with available laboratory tests and methodologies, such as polymerase chain reaction (PCR), MAP-associated DNA sequences and bacteriological culture investigations. These have, so far, been inconclusive in revealing the relationship of MAP in patients with CD. Improved and accurate methods of detection will add to evidence for an infectious aetiology of CD. Specifically, if the bacterial pathogen can be isolated, identified and cultivated, then causal relationships to disease can be confirmed, especially if it is present in human gut tissue. This review discusses how MAP may cause the inflammation seen in CD by relating its known pathogenesis in cattle, and from examples of other mycobacterial infections in humans, and how this would impact upon the difficulties with diagnostic tests for the organism.

Anti-inflammatory and protective effects of Aripiprazole on TNBS-Induced colitis and associated depression in rats: Role of kynurenine pathway

BACKGROUND

The prevalence of depression is higher in patients with inflammatory bowel disease (IBD) than in the general population. Inflammatory cytokines and the kynurenine pathway (KP) play important roles in IBD and associated depression. Aripiprazole (ARP), an atypical antipsychotic, shows various anti-inflammatory properties and may be useful in treating major depressive disorder. This study aimed to evaluate the protective effects of ARP on TNBS-induced colitis and subsequent depression in rats, highlighting the role of the KP.

MATERIAL AND METHODS

Fifty-six male Wistar rats were used, and all groups except for the normal and sham groups received a single dose of intra-rectal TNBS. Three different doses of ARP and dexamethasone were injected intraperitoneally for two weeks in treatment groups. On the 15th day, behavioral tests were performed to evaluate depressive-like behaviors. Colon ulcer index and histological changes were assessed. The tissue levels of inflammatory cytokines, KP markers, lipopolysaccharide (LPS), nuclear factor-kappa-B (NF-κB), and zonula occludens (ZO-1) were evaluated in the colon and hippocampus.

RESULTS

TNBS effectively induced intestinal damages and subsequent depressive-like symptoms in rats. TNBS treatment significantly elevated the intestinal content of inflammatory cytokines and NF-κB expression, dysregulated the KP markers balance in both colon and hippocampus tissues, and increased the serum levels of LPS. However, treatment with ARP for 14 days successfully reversed these alterations, particularly at higher doses.

CONCLUSION

ARP could alleviate IBD-induced colon damage and associated depressive-like behaviors mainly via suppressing inflammatory cytokines activity, serum LPS concentration, and affecting the NF-κB/kynurenine pathway.

Role of sulfidogenic members of the gut microbiota in human disease

The human gut flora comprises a dynamic network of bacterial species that coexist in a finely tuned equilibrium. The interaction with intestinal bacteria profoundly influences the host's development, metabolism, immunity, and overall health. Furthermore, dysbiosis, a disruption of the gut microbiota, can induce a variety of diseases, not exclusively associated with the intestinal tract. The increased consumption of animal protein, high-fat and high-sugar diets in Western countries has been implicated in the rise of chronic and inflammatory illnesses associated with dysbiosis. In particular, this diet leads to the overgrowth of sulfide-producing bacteria, known as sulfidogenic bacteria, which has been linked to inflammatory bowel diseases and colorectal cancer, among other disorders. Sulfidogenic bacteria include sulfate-reducing bacteria (Desulfovibrio spp.) and Bilophila wadsworthia among others, which convert organic and inorganic sulfur compounds to sulfide through the dissimilatory sulfite reduction pathway. At high concentrations, sulfide is cytotoxic and disrupts the integrity of the intestinal epithelium and mucus barrier, triggering inflammation. Besides producing sulfide, B. wadsworthia has revealed significant pathogenic potential, demonstrated in the ability to cause infection, adhere to intestinal cells, promote inflammation, and compromise the integrity of the colonic mucus layer. This review delves into the mechanisms by which taurine and sulfide-driven gut dysbiosis contribute to the pathogenesis of sulfidogenic bacteria, and discusses the role of these gut microbes, particularly B. wadsworthia, in human diseases.

Lactiplantibacillus plantarum-Derived Indole-3-lactic Acid Ameliorates Intestinal Barrier Integrity through the AhR/Nrf2/NF-κB Axis

Our previous studies have shown that Lactiplantibacillus plantarum DPUL-S164-derived indole-3-lactic acid (ILA) ameliorates intestinal epithelial cell barrier injury by activating aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways and promoting tight junction protein expression. This study further explored the crucial substances of L. plantarum DPUL-S164 in alleviating intestinal barrier damage in mice through a dextran sodium sulfate-induced ulcerative colitis mouse model. Compared to dead L. plantarum DPUL-S164 (D-S164), live L. plantarum DPUL-S164 (S164) and its tryptophan metabolite, ILA, showed an effective ameliorating effect on the intestinal barrier injury of mice treated by antibiotic cocktail and sodium dextran sulfate, suggesting that the crucial substances of L. plantarum DPUL-S164 ameliorating intestinal barrier injury are its extracellular metabolites. Furthermore, S164 and its tryptophan metabolite, ILA, ameliorate intestinal barrier injury and suppress intestinal inflammation by activating the AhR-Nrf2 pathway and inhibiting the nuclear factor kappa-B (NF-κB) pathway. These results suggest that L. plantarum DPUL-S164 ameliorates intestinal epithelial barrier damage in mice, primarily by producing ILA as a ligand to activate the AhR pathway.

Bovine Milk Derived Exosomes Affect Gut Microbiota of DSS-Induced Colitis Mice

The objective of this study was to investigate the effect of bovine milk derived exosomes (MDEs) on the gut microbiota of Dextran sodium sulfate (DSS)-induced colitis mice. Total of 42 specific pathogen free (SPF) male BALB/c mice (3 weeks old) were randomly assigned to three groups including control group, DSS group (DSS) and bovine milk derived exosome group (Exo), with 7 replicates/cages per treatment and two mice in one cage. 16S rRNA gene sequencing of cecal digesta samples was conducted. DSS significantly decreased the average daily feed intake of mice in DSS and Exo groups (P = 0.03). Shannon index of the DSS group was significantly lower than the control group (P < 0.05) whereas no difference between the control group and Exo group was observed. Administration of MDEs tended to increase the relative abundance of Campylobaterota. Compared to the control group, the relative abundance of Roseburia was significantly decreased in the DSS group (P < 0.05) whereas no difference between the Exo group and control group was observed. MDEs also tended to increase the relative abundance of Lachnospiraceae_UCG_006. In conclusion, oral administration of 10 µL MDEs (1 mg/mL) positively affected gut microbiota of DSS-induced colitis mice. The results of this study provided valuable reference for MDEs application in the prevention and treatment of colitis.

Postbiotics: An alternative and innovative intervention for the therapy of inflammatory bowel disease

Inflammatory Bowel Disease (IBD) is a persistent gastrointestinal (GI) tract inflammatory disease characterized by downregulated mucosal immune activities and a disrupted microbiota environment in the intestinal lumen. The involvement of bacterium postbiotics as mediators between the immune system and gut microbiome could be critical in determining why host-microbial relationships are disrupted in IBD. Postbiotics including Short-chain fatty acids (SCFAs), Organic acids, Proteins, Vitamins, Bacteriocins, and Tryptophan (Trp) are beneficial bioactive compounds formed via commensal microbiota in the gut environment during the fermentation process that can be used to improve consumer health. The use of metabolites or fragments from microorganisms can be a very attractive treatment and prevention technique in modern medicine. Postbiotics are essential in the immune system's development since they alter the barrier tightness, and the gut ecology and indirectly shape the microbiota's structure. As a result, postbiotics may be beneficial in treating or preventing various diseases, even some for which there is no effective causative medication. Postbiotics may be a promising tool for the treatment of IBD in individuals of all ages, genders, and even geographical locations. Direct distribution of postbiotics may provide a new frontier in microbiome-based therapy for IBD since it allows both the management of host homeostasis and the correction of the negative implications of dysbiosis. Further studies of the biological effects of these metabolites are expected to reveal innovative applications in medicine and beyond. This review attempts to explore the possible postbiotic-based interventions for the treatment of IBD.

Fermented rice bran supplementation attenuates colonic injury through modulating intestinal aryl hydrocarbon receptor and innate lymphoid cells in mice with dextran sodium sulfate-induced acute colitis

This study investigated the effects of fermented rice bran (FRB) on modulating intestinal aryl hydrocarbon receptor (AhR) expression, innate lymphoid cell (ILC)3 populations, the fecal microbiota distribution, and their associations with dextran sodium sulfate (DSS)-induced acute colitis. C57BL/6 mice were assigned to four groups: 1) NC group, normal mice fed the AIN-93M diet; 2) FRB group, normal mice fed a diet supplemented with 5% FRB; 3) NCD group, DSS-treated mice fed AIN-93M; 4) FRBD group, DSS-treated mice fed a 5% FRB-supplemented diet. DSS was administered for 5 d and followed by 5 d for recovery. At the end of the experiment, mice were sacrificed. Their blood and intestinal tissues were collected. Results showed that there were no differences in colonic biological parameters and function between the NC and FRB groups. Similar fecal microbiota diversity was noted between these two groups. Compared to the non-DSS-treated groups, DSS administration led to increased intestinal permeability, enhanced inflammatory cytokine production and disease severity, whereas tight junctions and AhR, interleukin (IL)-22 expressions were downregulated, and the ILC3 population had decreased. Also, gut microbiota diversity differs from the non-DSS-treated groups and more detrimental bacterial populations exist when compared to the FRBD group. FRB supplementation in DSS-treated mice attenuated fecal microbial dysbiosis, decreased intestinal permeability, improved the barrier integrity, upregulated AhR and IL-22 expression, maintained the ILC3 population, and pathologically mitigated colonic injury. These findings suggest enhanced ILC3- and AhR-mediated functions may be partly responsible for the anti-colitis effects of FRB supplementation in DSS-induced colitis.

Exploring the Effects of Probiotic Treatment on Urinary and Serum Metabolic Profiles in Healthy Individuals

Probiotics are live microorganisms that confer health benefits when administered in adequate amounts. They are used to promote gut health and alleviate various disorders. Recently, there has been an increasing interest in the potential effects of probiotics on human physiology. In the presented study, the effects of probiotic treatment on the metabolic profiles of human urine and serum using a nuclear magnetic resonance (NMR)-based metabonomic approach were investigated. Twenty-one healthy volunteers were enrolled in the study, and they received two different dosages of probiotics for 8 weeks. During the study, urine and serum samples were collected from volunteers before and during probiotic supplementation. The results showed that probiotics had a significant impact on the urinary and serum metabolic profiles without altering their phenotypes. This study demonstrated the effects of probiotics in terms of variations of metabolite levels resulting also from the different probiotic posology. Overall, the results suggest that probiotic administration may affect both urine and serum metabolomes, although more research is needed to understand the mechanisms and clinical implications of these effects. NMR-based metabonomic analysis of biofluids is a powerful tool for monitoring host-gut microflora dynamic interaction as well as for assessing the individual response to probiotic treatment.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Lactic Acid Bacteria Isolated from Human Breast Milk Improve Colitis Induced by 2,4,6-Trinitrobenzene Sulfonic Acid by Inhibiting NF-κB Signaling in Mice

Inflammatory bowel disease (IBD), a chronic inflammatory disease, results from dysregulation of the immune responses. Some lactic acid bacteria (LAB), including Lactobacillus, alleviate IBD through immunomodulation. In this study, the anti-colitis effect of LAB isolated from human breast milk was investigated in a mouse model induced acute colitis with 2,4,6-trinitrobenzene sulfonic acid (TNBS). TNBS remarkably increased weight loss, colon shortening, and colonic mucosal proliferation, as well as the expression levels of inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-1β. Oral administration of LAB isolated from human breast milk resulted in a reduction in TNBS-induced colon shortening, as well as induced cyclooxygenase (COX)-2, nitric oxide synthase (iNOS), nuclear factor-kappa B (NF-κB). In addition, LAB suppressed inflammatory cytokines such as TNF-α, IL-6, and IL-1β, and thus showed an effect of suppressing the level of inflammation induced by TNBS. Furthermore, LAB alleviated gut microbiota dysbiosis, and inhibited intestinal permeability by increasing the expression of intestinal tight junction protein including ZO-1. Collectively, these results suggest that LAB isolated from human breast milk can be used as a functional food for colitis treatment by regulating NF-κB signaling, gut microbiota and increasing expression of intestinal tight junction protein.

Delayed and limited administration of the JAKinib tofacitinib mitigates chronic DSS-induced colitis

In inflammatory bowel disease, dysregulated T cells express pro-inflammatory cytokines. Using a chronic azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced colitis model resembling ulcerative colitis, we evaluated whether and when treatment with the Janus kinase (JAK) inhibitor tofacitinib could be curative. Comparing the treatment with two and three cycles of tofacitinib medication in drinking water - intermittently with DSS induction - revealed that two cycles were not only sufficient but also superior over the 3-x regimen. The two cycles of the 2-x protocol paralleled the second and third cycles of the longer protocol. T cells were less able to express interferon gamma (IFN-γ) and the serum levels of IFN-γ, interleukin (IL)-2, IL-6, IL-17, and tumor necrosis factor (TNF) were significantly reduced in sera, while those of IL-10 and IL-22 increased under the 2-x protocol. Likewise, the frequency and effector phenotype of regulatory T cells (Tregs) increased. This was accompanied by normal weight gain, controlled clinical scores, and restored stool consistency. The general and histologic appearance of the colons revealed healing and tissue intactness. Importantly, two phases of tofacitinib medication completely prevented AOM-incited pseudopolyps and the hyper-proliferation of epithelia, which was in contrast to the 3-x regimen. This implies that the initial IBD-induced cytokine expression is not necessarily harmful as long as inflammatory signaling can later be suppressed and that time-restricted treatment allows for anti-inflammatory and tissue-healing cytokine activities.

Inflammatory Bowel Diseases and Gut Microbiota

Inflammatory bowel disease (IBD) is an inflammatory disease of the gastrointestinal tract, the incidence of which has rapidly increased worldwide, especially in developing and Western countries. Recent research has suggested that genetic factors, the environment, microbiota, and immune responses are involved in the pathogenesis; however, the underlying causes of IBD are unclear. Recently, gut microbiota dysbiosis, especially a decrease in the abundance and diversity of specific genera, has been suggested as a trigger for IBD-initiating events. Improving the gut microbiota and identifying the specific bacterial species in IBD are essential for understanding the pathogenesis and treatment of IBD and autoimmune diseases. Here, we review the different aspects of the role played by gut microbiota in the pathogenesis of IBD and provide a theoretical basis for modulating gut microbiota through probiotics, fecal microbiota transplantation, and microbial metabolites.

Probiotics Mechanism of Action on Immune Cells and Beneficial Effects on Human Health

Immune cells and commensal microbes in the human intestine constantly communicate with and react to each other in a stable environment in order to maintain healthy immune activities. Immune system-microbiota cross-talk relies on a complex network of pathways that sustain the balance between immune tolerance and immunogenicity. Probiotic bacteria can interact and stimulate intestinal immune cells and commensal microflora to modulate specific immune functions and immune homeostasis. Growing evidence shows that probiotic bacteria present important health-promoting and immunomodulatory properties. Thus, the use of probiotics might represent a promising approach for improving immune system activities. So far, few studies have been reported on the beneficial immune modulatory effect of probiotics. However, many others, which are mainly focused on their metabolic/nutritional properties, have been published. Therefore, the mechanisms behind the interaction between host immune cells and probiotics have only been partially described. The present review aims to collect and summarize the most recent scientific results and the resulting implications of how probiotic bacteria and immune cells interact to improve immune functions. Hence, a description of the currently known immunomodulatory mechanisms of probiotic bacteria in improving the host immune system is provided.

Metabolite features of serum and intestinal microbiota response of largemouth bass (Micropterus salmoides) after Aeromonas hydrophila challenge

The enteric morphology, enteric microbiota structure and serum metabolomics of M. salmoides before and after infected by A. hydrophila were analysed to explore the pathogenic mechanism of A. hydrophila infection in M. salmoides. The results revealed that, after the infection of A. hydrophila, the villus boundary of largemouth bass became less obvious; the relative abundance of Proteobacteria and decreasing relative abundance of Tenericutes were increasing; genera relative abundance of putatively beneficial bacteria (Mycoplasma) were decreasing, whereas the genus Aeromonas increased after infection; serum metabolomic analysis showed that infection with A. hydrophila caused disorder to the metabolic processes of largemouth bass, particularly amino acid metabolism, and caused inflammation; several potential pathogen infection-related and significantly differential intestinal microbiota-related metabolite markers were identified, such as 6-hydroxy-5-methoxyindole glucuronide, zalcitabine, bilirubin, aciclovir. This study may provide new insights into the potential association between enteric microbiota and serum metabolism and the pathogenic mechanism of M. salmoides infected by A. hydrophila, providing a scientific basis for disease control in largemouth bass breeding.

The spring-like effect of microRNA-31 in balancing inflammatory and regenerative responses in colitis

Inflammatory bowel diseases (IBDs) are chronic inflammatory disorders caused by the disruption of immune tolerance to the gut microbiota. MicroRNA-31 (MIR31) has been proven to be up-regulated in intestinal tissues from patients with IBDs and colitis-associated neoplasias. While the functional role of MIR31 in colitis and related diseases remain elusive. Combining mathematical modeling and experimental analysis, we systematically explored the regulatory mechanism of MIR31 in inflammatory and epithelial regeneration responses in colitis. Level of MIR31 presents an "adaptation" behavior in dextran sulfate sodium (DSS)-induced colitis, and the similar behavior is also observed for the key cytokines of p65 and STAT3. Simulation analysis predicts MIR31 suppresses the activation of p65 and STAT3 but accelerates the recovery of epithelia in colitis, which are validated by our experimental observations. Further analysis reveals that the number of proliferative epithelial cells, which characterizes the inflammatory process and the recovery of epithelia in colitis, is mainly determined by the inhibition of MIR31 on IL17RA. MIR31 promotes epithelial regeneration in low levels of DSS-induced colitis but inhibits inflammation with high DSS levels, which is dominated by the competition for MIR31 to either inhibit inflammation or promote epithelial regeneration by binding to different targets. The binding probability determines the functional transformation of MIR31, but the functional strength is determined by MIR31 levels. Thus, the role of MIR31 in the inflammatory response can be described as the "spring-like effect," where DSS, MIR31 action strength, and proliferative epithelial cell number are regarded as external force, intrinsic spring force, and spring length, respectively. Overall, our study uncovers the vital roles of MIR31 in balancing inflammation and the recovery of epithelia in colitis, providing potential clues for the development of therapeutic targets in drug design.

Therapy Used to Promote Disease Remission Targeting Gut Dysbiosis, in UC Patients with Active Disease

Ulcerative colitis (UC) is a relapsing non-transmural chronic inflammatory disease of the colon characterized by bloody diarrhea. The etiology of UC is unknown. The goal is to reduce the inflammation and induce disease remission in UC patients with active disease. The aim of this study is to investigate the innovative treatment method used to promote disease remission in UC patients with active disease targeting gut dysbiosis. Immunosuppressants such as TNF-α blocker are used to promote disease remission in UC, but it is expensive and with side effects. Probiotic, prebiotic and diet are shown to be effective in maintaining disease remission. Fecal microbiota transplantation (FMT) might be the future therapy option to promote disease remission in UC patients with active disease. However, correct manufacturing and administration of the FMT are essential to achieve successful outcome. A few cohorts with FMT capsules show promising results in UC patients with active disease. However, randomized controlled clinical trials with long-term treatment and follow-up periods are necessary to show FMT capsules' efficacy to promote disease remission in UC patients.

Tutorial: Microbiome studies in drug metabolism

The human gastrointestinal tract is home to a dense population of microorganisms whose metabolism impacts human health and physiology. The gut microbiome encodes millions of genes, the products of which endow our bodies with unique biochemical activities. In the context of drug metabolism, microbial biochemistry in the gut influences humans in two major ways: (1) by producing small molecules that modulate expression and activity of human phase I and II pathways; and (2) by directly modifying drugs administered to humans to yield active, inactive, or toxic metabolites. Although the capacity of the microbiome to modulate drug metabolism has long been known, recent studies have explored these interactions on a much broader scale and have revealed an unprecedented scope of microbial drug metabolism. The implication of this work is that we might be able to predict the capacity of an individual's microbiome to metabolize drugs and use this information to avoid toxicity and inform proper dosing. Here, we provide a tutorial of how to study the microbiome in the context of drug metabolism, focusing on in vitro, rodent, and human studies. We then highlight some limitations and opportunities for the field.

Symbiotic bacteria stabilize the intestinal environment by producing phenylpropanoids

Salmonella enterica serovar Enteritidis (S. Enteritidis) can colonize in the intestinal tract of chickens and transmit to humans. In order to decrypt the mechanism of avian resistance to S. Enteritidis, we utilized two China local chicken breeds to generate the reciprocal crosses (the Cross and the Reverse-cross). The two lines of hybrids were orally inoculated with S. Enteritidis at 2-day old and sampled at 3 days post-inoculation. Along the analysis direction of multi-omics, differential metabolites, functional pathways and correlated microbes, we found that 12 species of microbes thrived upon S. Enteritidis challenge and probably contributed to the intestinal stability in the Cross by enhancing the production of phenylpropanoids. Our findings can help to understand the symbiotic and resistant mechanisms derived from the intestinal microbiota.

Insight into role of short chain fatty acids in regulating intestinal mucosal barrier and alleviating inflammatory bowel disease

In recent years, the importance of intestinal microbiota and its metabolites in maintaining the human intestinal environment has been gradually revealed. Therefore, short chain fatty acids (SCFAs), as the metabolites produced by the intestinal microbiota, play a momentous part in regulating the balance between the function and morphology of the mucosal barrier, regulating the proliferation and differentiation of mucosal cells, protecting the integrity and permeability of the mucosal barrier, and maintainingthe stability of tight junctions. Inflammatory bowel disease (IBD) is a chronic, inflammatory condition of the gastrointestinal tract, associated with a disturbance of intestinal barrier function and dysregulation of the intestinal immune responses, the etiology and pathogenesis of which, however, are not yet fully uncovered. Animal models and human studies have corroborated the contribution of SCFAs in enhancing the barrier function through protective effects. This review will summarize the potential role of SCFAs in IBD with regard to regulating intestinal function, hoping to provide a new target for clinical treatment of IBD.

The response of cecal microbiota to inflammatory state induced by Salmonella enterica serovar Enteritidis

By combining the experiments of reciprocal crosses of chicken infected with Salmonella enterica serovar Enteritidis (S. Enteritidis), we focused on the common response of cecal microbiota to an inflammatory state in respect of transcriptome and microbiome. The inoculation of S. Enteritidis improved the microbial diversity and promoted the microbiota evolution in our infection model. Correlation analysis between bacteria and inflammation-related genes showed that some intestinal microorganisms were “inflammophile” and thrived in an inflamed environment. The global function of cecal microbiome was to maintain the homeostasis likely by the up-regulation of microbial metabolism pathway in bacitracin, putrescine, and flavonoids production, although the bacitracin may affect the symbiotic bacteria Enterococcus. The action of S. Enteritidis had close relationships with multiple inflammation-related genes, including the genes PTAFR, LY96, and ACOD1 which proteins are related to the binding and tolerance of LPS, and the genes IL-18, IL-18R1 and IL-18RAP which products can form a functional complex and transmit IL-18 pro-inflammatory signal. Additionally, the infection of S. Enteritidis aroused the transcription of EXFABP, which protein has a potential to sequestrate the siderophore and might cause the decline of Escherichia-Shigella and Enterococcus. S. Enteritidis can escape from the sequestrating through the salmochelin, another kind of siderophore which cannot be recognized by EXFABP. Probably by this way, S. Enteritidis competed with the symbiotic bacteria and edged out the niches. Our research can help to understand the interplay between host, pathogen, and symbiotic bacteria.

Association between intestinal microbiota and inflammatory bowel disease

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), has emerged as a global disease with high incidence, long duration, devastating clinical symptoms, and low curability (relapsing immune response and barrier function defects). Mounting studies have been performed to investigate its pathogenesis to provide an ever‐expanding arsenal of therapeutic options, while the precise etiology of IBD is not completely understood yet. Recent advances in high‐throughput sequencing methods and animal models have provided new insights into the association between intestinal microbiota and IBD. In general, dysbiosis characterized by an imbalanced microbiota has been widely recognized as a pathology of IBD. However, intestinal microbiota alterations represent the cause or result of IBD process remains unclear. Therefore, more evidences are needed to identify the precise role of intestinal microbiota in the pathogenesis of IBD. Herein, this review aims to outline the current knowledge of commonly used, chemically induced, and infectious mouse models, gut microbiota alteration and how it contributes to IBD, and dysregulated metabolite production links to IBD pathogenesis.

Gastrointestinal Tract Microbiome Effect and Role in Disease Development

In recent years, it has been shown that gastrointestinal microflora has a substantial impact on the development of a large number of chronic diseases. The imbalance in the number or type of microbes in the gastrointestinal tract can lead to diseases and conditions, including autism spectrum disorder, celiac disease, Crohn’s disease, diabetes, and small bowel cancers. This can occur as a result of genetics, alcohol, tobacco, chemotherapeutics, cytostatics, as well as antibiotic overuse. Due to this, essential taxa can be lost, and the host’s metabolism can be severely affected. A less known condition called small intestine bacterial overgrowth (SIBO) can be seen in patients who suffer from hypochlorhydria and small intestine cancers. It is characterized as a state in which the bacterial population in the small intestine exceeds 10⁵–10⁶ organisms/mL. The latest examination methods such as double-balloon enteroscopy and wireless capsule endoscopy have the potential to increase the accuracy and precision of diagnosis and provide better patient care. This review paper aims to summarize the effect of the gastrointestinal environment on chronic disease severity and the development of cancers.

Akkermansia muciniphila and Gut Immune System: A Good Friendship That Attenuates Inflammatory Bowel Disease, Obesity, and Diabetes

Akkermansia muciniphila is a Gram-negative anaerobic mucus-layer-degrading bacterium that colonizes the intestinal mucosa of humans and rodents. Metagenomic data have shown an inverse correlation between the abundance of A. muciniphila and diseases such as inflammatory bowel disease (IBD), obesity, and diabetes. Thus, in recent decades, the potential of this bacterium as an immunomodulatory probiotic for autoimmune and chronic inflammatory diseases has been explored in experimental models. Corroborating these human correlation data, it has been reported that A. muciniphila slows down the development and progression of diabetes, obesity, and IBD in mice. Consequently, clinical studies with obese and diabetic patients are being performed, and the preliminary results are very promising. Therefore, this mini review highlights the main findings regarding the beneficial roles of A. muciniphila and its action mechanisms in autoimmune and chronic inflammatory diseases.

Intestine-Specific NHE3 Deletion in Adulthood Causes Microbial Dysbiosis

In the intestine, the Na⁺/H⁺ exchanger 3 (NHE3) plays a critical role for Na⁺ and fluid absorption. NHE3 deficiency predisposes patients to inflammatory bowel disease (IBD). In mice, selective deletion of intestinal NHE3 causes various local and systemic pathologies due to dramatic changes in the intestinal environment, which can influence microbiota colonization. By using metagenome shotgun sequencing, we determined the effect of inducible intestinal epithelial cell-specific deletion of NHE3 (NHE3^IEC-KO) in adulthood on the gut microbiome in mice. Compared with control mice, NHE3^IEC-KO mice show a significantly different gut microbiome signature, with an unexpected greater diversity. At the phylum level, NHE3^IEC-KO mice showed a significant expansion in Proteobacteria and a tendency for lower Firmicutes/Bacteroidetes (F/B) ratio, an indicator of dysbiosis. At the family level, NHE3^IEC-KO mice showed significant expansions in Bacteroidaceae, Rikenellaceae, Tannerellaceae, Flavobacteriaceae and Erysipelotrichaceae, but had contractions in Lachnospiraceae, Prevotellaceae and Eubacteriaceae. At the species level, after removing those with lowest occurrence and abundance, we identified 23 species that were significantly expanded (several of which are established pro-inflammatory pathobionts); whereas another 23 species were found to be contracted (some of which are potential anti-inflammatory probiotics) in NHE3^IEC-KO mice. These results reveal that intestinal NHE3 deletion creates an intestinal environment favoring the competitive advantage of inflammophilic over anti-inflammatory species, which is commonly featured in conventional NHE3 knockout mice and patients with IBD. In conclusion, our study emphasizes the importance of intestinal NHE3 for gut microbiota homeostasis, and provides a deeper understanding regarding interactions between NHE3, dysbiosis, and IBD.

The Gut Microbiota (Microbiome) in Cardiovascular Disease and Its Therapeutic Regulation

In the last two decades, considerable interest has been shown in understanding the development of the gut microbiota and its internal and external effects on the intestine, as well as the risk factors for cardiovascular diseases (CVDs) such as metabolic syndrome. The intestinal microbiota plays a pivotal role in human health and disease. Recent studies revealed that the gut microbiota can affect the host body. CVDs are a leading cause of morbidity and mortality, and patients favor death over chronic kidney disease. For the function of gut microbiota in the host, molecules have to penetrate the intestinal epithelium or the surface cells of the host. Gut microbiota can utilize trimethylamine, N-oxide, short-chain fatty acids, and primary and secondary bile acid pathways. By affecting these living cells, the gut microbiota can cause heart failure, atherosclerosis, hypertension, myocardial fibrosis, myocardial infarction, and coronary artery disease. Previous studies of the gut microbiota and its relation to stroke pathogenesis and its consequences can provide new therapeutic prospects. This review highlights the interplay between the microbiota and its metabolites and addresses related interventions for the treatment of CVDs.

Gut microbiota in various childhood disorders: Implication and indications

Gut microbiota has a significant role in gut development, maturation, and immune system differentiation. It exerts considerable effects on the child's physical and mental development. The gut microbiota composition and structure depend on many host and microbial factors. The host factors include age, genetic pool, general health, dietary factors, medication use, the intestine's pH, peristalsis, and transit time, mucus secretions, mucous immunoglobulin, and tissue oxidation-reduction potentials. The microbial factors include nutrient availability, bacterial cooperation or antagonism, and bacterial adhesion. Each part of the gut has its microbiota due to its specific characteristics. The gut microbiota interacts with different body parts, affecting the pathogenesis of many local and systemic diseases. Dysbiosis is a common finding in many childhood disorders such as autism, failure to thrive, nutritional disorders, coeliac disease, Necrotizing Enterocolitis, helicobacter pylori infection, functional gastrointestinal disorders of childhood, inflammatory bowel diseases, and many other gastrointestinal disorders. Dysbiosis is also observed in allergic conditions like atopic dermatitis, allergic rhinitis, and asthma. Dysbiosis can also impact the development and the progression of immune disorders and cardiac disorders, including heart failure. Probiotic supplements could provide some help in managing these disorders. However, we are still in need of more studies. In this narrative review, we will shed some light on the role of microbiota in the development and management of common childhood disorders.

Lactobacillus plantarum strains attenuated DSS-induced colitis in mice by modulating the gut microbiota and immune response

Gut microbiota has become a new therapeutic target in the treatment of inflammatory Bowel Disease (IBD). Probiotics are known for their beneficial effects and have shown good efficacy in the clinical treatment of IBD and animal models of colitis. However, how these probiotics contribute to the amelioration of IBD is largely unknown. In the current study, the DSS-induced mouse colitis model was treated with oral administration of Lactobacillus plantarum strains to investigate their effects on colitis. The results indicated that the L. plantarum strains improved dysbiosis and enhanced the abundance of beneficial bacteria related to short-chain fatty acids (SCFAs) production. Moreover, L. plantarum strains decreased the level of pro-inflammatory cytokines, i.e., IL-17A, IL-17F, IL-6, IL-22, and TNF-α and increased the level of anti-inflammatory cytokines, i.e., TGF-β, IL-10. Our result suggests that L. plantarum strains possess probiotic effects and can ameliorate DSS colitis in mice by modulating the resident gut microbiota and immune response.

Gut Microbiota, Macrophages and Diet: An Intriguing New Triangle in Intestinal Fibrosis

Intestinal fibrosis is a common complication in inflammatory bowel disease (IBD) without specific treatment. As macrophages are the key actors in inflammatory responses and the wound healing process, they have been extensively studied in chronic diseases these past decades. By their exceptional ability to integrate diverse stimuli in their surrounding environment, macrophages display a multitude of phenotypes to underpin a broad spectrum of functions, from the initiation to the resolution of inflammation following injury. The hypothesis that distinct macrophage subtypes could be involved in fibrogenesis and wound healing is emerging and could open up new therapeutic perspectives in the treatment of intestinal fibrosis. Gut microbiota and diet are two key factors capable of modifying intestinal macrophage profiles, shaping their specific function. Defects in macrophage polarisation, inadequate dietary habits, and alteration of microbiota composition may contribute to the development of intestinal fibrosis. In this review, we describe the intriguing triangle between intestinal macrophages, diet, and gut microbiota in homeostasis and how the perturbation of this discreet balance may lead to a pro-fibrotic environment and influence fibrogenesis in the gut.

Butyl-fructooligosaccharides modulate gut microbiota in healthy mice and ameliorate ulcerative colitis in a DSS-induced model

Butyl-fructooligosaccharides (B-FOSs) are newly synthesized prebiotics composed of short-chain FOS (GF2, 1-kestose; GF3, nystose; GF4, fructofuranosyl-nystose; GF5, 1-F-(1-b-D-fructofuranosyl)-2-nystose) bound with one or two butyric groups by ester bonds. Previous in...

Lactobacillus johnsonii Attenuates Citrobacter rodentium-Induced Colitis by Regulating Inflammatory Responses and Endoplasmic Reticulum Stress in Mice

BACKGROUND

Probiotics are beneficial in intestinal disorders. However, the benefits of Lactobacillus johnsonii in experimental colitis remain unknown.

OBJECTIVES

This study aimed to investigate the benefits of L. johnsonii against Citrobacter rodentium-induced colitis.

METHODS

Thirty-six 5-wk-old female C57BL/6J mice were randomly assigned to 3 groups (n = 12): control (Ctrl) group, Citrobacter rodentium treatment (CR) group (2 × 109 CFU C. rodentium), and Lactobacillus johnsonii and Citrobacter rodentium cotreatment (LJ + CR) group (109 CFU L. johnsonii with C. rodentium). Colon length, mucosal thickness, proinflammatory cytokine genes, and endoplasmic reticulum stress were tested.

RESULTS

The CR group had greater spleen weight, mucosal thickness, and Ki67+ cells (0.4-4.7 times), and a 23.8% shorter colon length than the Ctrl group, which in the LJ + CR group were 22.4%-77.6% lower and 30% greater than in the CR group, respectively. Relative to the Ctrl group, serum proinflammatory cytokines and immune cell infiltration were greater by 0.3-1.6 times and 6.2-8.8 times in the CR group, respectively; relative to the CR group, these were 19.9%-61.9% and 69.5%-84.2% lower in the LJ + CR group, respectively. The mRNA levels of lysozyme (Lyz) and regenerating islet-derived protein III were 22.7%-36.5% lower and 1.5-2.7 times greater in the CR group than in the Ctrl group, respectively, whereas they were 22.2%-25.7% greater and 57.2%-76.9% lower in the LJ + CR group than in the CR group, respectively. Cell apoptosis was 11.9 times greater in the CR group than in the Ctrl group, and 87.4% lower in the LJ + CR group than in the CR group. Consistently, the protein abundances of C/EBP homologous protein (CHOP), cleaved caspase 1 and 3, activating transcription factor 6α (ATF6A), and phospho-inositol-requiring enzyme 1α (P-IRE1A) were 0.3-2.1 times greater in the CR group and 31.1%-60.4% lower in the LJ + CR group. All these indexes did not differ between the Ctrl and LJ + CR groups, except for CD8+ T lymphocytes and CD11b+ and F4/80+ macrophages (1-1.5 times greater in LJ + CR) and mRNA concentration of Lyz2 (20.1% lower in LJ + CR).

CONCLUSIONS

L. johnsonii supplementation is a promising nutritional strategy for preventing C. rodentium-induced colitis in mice.

Metabolic Influences of Gut Microbiota Dysbiosis on Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are chronic medical disorders characterized by recurrent gastrointestinal inflammation. While the etiology of IBD is still unknown, the pathogenesis of the disease results from perturbations in both gut microbiota and the host immune system. Gut microbiota dysbiosis in IBD is characterized by depleted diversity, reduced abundance of short chain fatty acids (SCFAs) producers and enriched proinflammatory microbes such as adherent/invasive E. coli and H₂S producers. This dysbiosis may contribute to the inflammation through affecting either the immune system or a metabolic pathway. The immune responses to gut microbiota in IBD are extensively discussed. In this review, we highlight the main metabolic pathways that regulate the host-microbiota interaction. We also discuss the reported findings indicating that the microbial dysbiosis during IBD has a potential metabolic impact on colonocytes and this may underlie the disease progression. Moreover, we present the host metabolic defectiveness that adds to the impact of symbiont dysbiosis on the disease progression. This will raise the possibility that gut microbiota dysbiosis associated with IBD results in functional perturbations of host-microbiota interactions, and consequently modulates the disease development. Finally, we shed light on the possible therapeutic approaches of IBD through targeting gut microbiome.

Faecalibacterium prausnitzii Attenuates DSS-Induced Colitis by Inhibiting the Colonization and Pathogenicity of Candida albicans

SCOPE

Intestinal commensal microbiota interactions play critical roles in the inflammatory bowel disease (IBD) development. Candida albicans (CA) can aggravate intestinal inflammation; however, whether Faecalibacterium prausnitzii (FP) can antagonize CA is unknown.

METHODS AND RESULTS

CA are co-cultured with bacteria (FP and Escherichia coli (EC)), bacterial supernatant, and bacterial medium, respectively. Then, the CA hyphae-specific genes' expression and CA cells' morphology are investigated. The Nod-like receptor pyrin-containing protein 6 (NLRP6) inflammasome, inflammatory cytokines, and antimicrobial peptides (AMPs) production are evaluated in intestinal epithelial cells pre-treated with bacteria, bacterial med, and bacterial supernatant and exposed without or with CA. Both bacteria significantly prohibit CA numbers, while only FP and FP supernatant prohibit the transformation and virulence factors (extracellular phospholipase, secreted aspartyl proteinase, and hemolysin) secretion of CA in a co-culture system compared with media controls. Further, FP and FP supernatant promote the production of the NLRP6 inflammasome, interleukin (IL)-1β, IL-18, and antibacterial peptides (β-defensin (BD)-2 and BD-3) and inhibit in vitro and in vivo CA growth and pathogenicity, and alleviate DSS-colitis in mice, while EC do not show the similar effect.

CONCLUSION

FP improve intestinal inflammation by inhibiting CA reproduction, colonization, and pathogenicity and inducing AMP secretion in the gut. This study uncovers new relationships between intestinal microbes and fungi in IBD patients.

Fecal microbiome differs between patients with systemic sclerosis with and without small intestinal bacterial overgrowth

Introduction:

Gastrointestinal manifestations of systemic sclerosis affect up to 90% of patients, with symptoms including diarrhea and constipation. Small intestinal bacterial overgrowth is a condition associated with increased numbers of pathogenic bacteria in the small bowel. While currently unknown, it has been suggested that dysregulation of the fecal microbiota may play a role in the development of systemic sclerosis and small intestinal bacterial overgrowth.

Objectives:

Our study aimed to describe the fecal microbiota of patients with systemic sclerosis and compare it between those with and without a diagnosis of small intestinal bacterial overgrowth. We also compared the fecal microbiota of systemic sclerosis patients with that of healthy controls to understand the association between particular bacterial taxa and clinical gastrointestinal manifestations of systemic sclerosis.

Methods:

A total of 29 patients with systemic sclerosis underwent breath testing to assess for small intestinal bacterial overgrowth, provided stool samples to determine taxonomic assignments, and completed the University of California Los Angeles Scleroderma Clinical Trial Consortium Gastrointestinal Tract 2.0, which details symptoms and quality-of-life factors. Stool samples were compared between systemic sclerosis patients with and without small intestinal bacterial overgrowth, and between patients with systemic sclerosis and a healthy control cohort (n = 20), aged 18–80 years.

Results:

Fecal microbiome analyses demonstrated differences between systemic sclerosis patients with and without small intestinal bacterial overgrowth and differences in the diversity of species between healthy controls and patients with systemic sclerosis. Trends were also observed in anticentromere antibody systemic sclerosis patients, including higher Alistipies indistincus spp. levels associated with increased methane levels of breath gas testing and higher Slakia spp. levels associated with increased rates of fecal soiling.

Conclusions:

Our results suggest that changes to the fecal microbiome occur in patients with small intestinal bacterial overgrowth and systemic sclerosis when compared to healthy controls. As a cross-sectional study, the potential pathophysiologic role of an altered microbiome in the development of systemic sclerosis was not considered and hence needs to be further investigated.

The Good and the Bad: Ecological Interaction Measurements Between the Urinary Microbiota and Uropathogens

The human body harbors numerous populations of microorganisms in various ecological niches. Some of these microbial niches, such as the human gut and the respiratory system, are well studied. One system that has been understudied is the urinary tract, primarily because it has been considered sterile in the absence of infection. Thanks to modern sequencing and enhanced culture techniques, it is now known that a urinary microbiota exists. The implication is that these species live as communities in the urinary tract, forming microbial ecosystems. However, the interactions between species in such an ecosystem remains unknown. Various studies in different parts of the human body have highlighted the ability of the pre-existing microbiota to alter the course of infection by impacting the pathogenicity of bacteria either directly or indirectly. For the urinary tract, the effect of the resident microbiota on uropathogens and the phenotypic microbial interactions is largely unknown. No studies have yet measured the response of uropathogens to the resident urinary bacteria. In this study, we investigate the interactions between uropathogens, isolated from elderly individuals suffering from UTIs, and bacteria isolated from the urinary tract of asymptomatic individuals using growth measurements in conditioned media. We observed that bacteria isolated from individuals with UTI-like symptoms and bacteria isolated from asymptomatic individuals can affect each other's growth; for example, bacteria isolated from symptomatic individuals affect the growth of bacteria isolated from asymptomatic individuals more negatively than vice versa. Additionally, we show that Gram-positive bacteria alter the growth characteristics differently compared to Gram-negative bacteria. Our results are an early step in elucidating the role of microbial interactions in urinary microbial ecosystems that harbor both uropathogens and pre-existing microbiota.

RNase1 can modulate gut microbiota and metabolome after Aeromonas hydrophila infection in blunt snout bream

Pancreatic ribonuclease (RNase1) of Megalobrama amblycephala exhibits both antimicrobial and digestive activity. The gut microbiome improve the digestion and metabolic capacity and enhance the functioning of the immune system of the host against pathogenic bacteria. In this study, we aimed to assess the protective effect of RNase1 on Aeromonas hydrophila-induced inflammation and intestinal microbial metabolism. Megalobrama amblycephala were randomly divided into three groups: control (injected PBS), infection (A. hydrophila-injected), and treatment group (RNase1 pretreatment 24 h before the A. hydrophila injection). The morphological symptoms were significantly alleviated by RNase1. RNase1 reshaped the perturbed gut microbiota by upregulating Proteobacteria and Vibrio richness and downregulating Firmicutes, Chlamydiae, Bacillus, and Gemmobacter richness. The lysophosphatidylcholine, (±) 17 HETE, D- (+) -cellobiose, and PC (20:5) in the treatment group were restored by RNase 1 protein treatment to the level of the control group. In the treatment group, phospholipid metabolism, fatty acid metabolism, glucose metabolism and lipid metabolism were different from the control and infection groups. The proinflammatory factors concentration in intestinal samples significantly increased after A. hydrophila infection. Our results revealed that RNase1 plays an important role in resistance to pathogen invasion, reducing inflammation, and improving intestinal function, thus inhibiting the occurrence of disease.

IL-1 and CD40/CD40L platelet complex: elements of induction of Crohn's disease and new therapeutic targets

Ulcerative colitis (UC) and Crohn's disease (CD) are chronic and multifactorial diseases that affect the intestinal tract, both characterized by recurrent inflammation of the intestinal mucosa, resulting in abdominal pain, diarrhea, vomiting and, rectal bleeding. Inflammatory bowel diseases (IBD) regroup these two disorders. The exact pathological mechanism of IBD remains ambiguous and poorly known. In genetically predisposed patients, defects in intestinal mucosal barrier are due to an uncontrolled inflammatory response to normal flora. In addition to the genetic predisposition, these defects could be triggered by environmental factors or by a specific lifestyle which is widely accepted as etiological hypothesis. The involvement of the CD40/CD40L platelet complex in the development of IBD has been overwhelmingly demonstrated. CD40L is climacteric in cell signalling in innate and adaptive immunity, the CD40L expression on the platelet cell surface gives them an immunological competence. The IL-1, a major inflammation mediator could be involved in different ways in the development of IBD. Here, we provide a comprehensive review regarding the role of platelet CD40/CD40L in the pathophysiological effect of IL-1 in the development of Crohn's disease (CD). This review could potentially help future approaches aiming to target these two pathways for therapeutic purposes and elucidate the immunological mechanisms driving gut inflammation.

Niacin and Butyrate: Nutraceuticals Targeting Dysbiosis and Intestinal Permeability in Parkinson's Disease

Dysbiosis is implicated by many studies in the pathogenesis of Parkinson's disease (PD). Advances in sequencing technology and computing have resulted in confounding data regarding pathogenic bacterial profiles in conditions such as PD. Changes in the microbiome with reductions in short-chain fatty acid (SCFA)-producing bacteria and increases in endotoxin-producing bacteria likely contribute to the pathogenesis of PD. GPR109A, a G-protein coupled receptor found on the surface of the intestinal epithelium and immune cells, plays a key role in controlling intestinal permeability and the inflammatory cascade. The absence of GPR109A receptors is associated with decreased concentration of tight junction proteins, leading to increased intestinal permeability and susceptibility to inflammation. In inflammatory states, butyrate acts via GPR109A to increase concentrations of tight junction proteins and improve intestinal permeability. Niacin deficiency is exacerbated in PD by dopaminergic medications. Niacin supplementation has been shown to shift macrophage polarization from pro-inflammatory to an anti-inflammatory profile. Niacin and butyrate, promising nutrients and unique ligands for the G protein-coupled receptor GPR109A, are reviewed in this paper in detail.

Prebiotics and Probiotics in Inflammatory Bowel Disease: Where are we now and where are we going?

The incidence, prevalence, and cost of care associated with diagnosis and management of inflammatory bowel disease are on the rise. The role of gut microbiota in the causation of Crohn's disease and ulcerative colitis has not been established yet. Nevertheless, several animal models and human studies point towards the association. Targeting intestinal dysbiosis for remission induction, maintenance, and relapse prevention is an attractive treatment approach with minimal adverse effects. However, the data is still conflicting. The purpose of this article is to provide the most comprehensive and updated review on the utility of prebiotics and probiotics in the management of active Crohn's disease and ulcerative colitis/pouchitis and their role in the remission induction, maintenance, and relapse prevention. A thorough literature review was performed on PubMed, Ovid Medline, and EMBASE using the terms "prebiotics AND ulcerative colitis", "probiotics AND ulcerative colitis", "prebiotics AND Crohn's disease", "probiotics AND Crohn's disease", "probiotics AND acute pouchitis", "probiotics AND chronic pouchitis" and "prebiotics AND pouchitis". Observational studies and clinical trials conducted on humans and published in the English language were included. A total of 71 clinical trials evaluating the utility of prebiotics and probiotics in the management of inflammatory bowel disease were reviewed and the findings were summarized. Most of these studies on probiotics evaluated lactobacillus, De Simone Formulation or Escherichia coli Nissle 1917 and there is some evidence supporting these agents for induction and maintenance of remission in ulcerative colitis and prevention of pouchitis relapse with minimal adverse effects. The efficacy of prebiotics such as fructooligosaccharides and Plantago ovata seeds in ulcerative colitis are inconclusive and the data regarding the utility of prebiotics in pouchitis is limited. The results of the clinical trials for remission induction and maintenance in active Crohn's disease or post-operative relapse with probiotics and prebiotics are inadequate and not very convincing. Prebiotics and probiotics are safe, effective and have great therapeutic potential. However, better designed clinical trials in the multicenter setting with a large sample and long duration of intervention are needed to identify the specific strain or combination of probiotics and prebiotics which will be more beneficial and effective in patients with inflammatory bowel disease.

Vaccine Interactions With the Infant Microbiome: Do They Define Health and Disease?

Over the past decade, there has been a growing awareness of the vital role of the microbiome in the function of the immune system. Recently, several studies have demonstrated a relationship between the composition of the microbiome and the vaccine-specific immune response. As a result of these findings, the administration of probiotics has been proposed as a means of boosting vaccine-specific immunity. Early results have so far been highly inconsistent, with little evidence of sustained benefit. To date, a precise determination of the aspects of the microbiome that impact immunity is still lacking, and the mechanisms of action are also unknown. Further investigations into these questions are necessary to effectively manipulate the microbiome for the purpose of boosting immunity and enhancing vaccine-specific responses in infants. In this review, we summarize recent studies aimed at altering the neonatal gut microbiome to enhance vaccine responses and highlight gaps in knowledge and understanding. We also discuss research strategies aimed at filling these gaps and developing potential therapeutic interventions.

Increasing Evidence That Irritable Bowel Syndrome and Functional Gastrointestinal Disorders Have a Microbial Pathogenesis

The human gastrointestinal tract harbors most of the microbial cells inhabiting the body, collectively known as the microbiota. These microbes have several implications for the maintenance of structural integrity of the gastrointestinal mucosal barrier, immunomodulation, metabolism of nutrients, and protection against pathogens. Dysfunctions in these mechanisms are linked to a range of conditions in the gastrointestinal tract, including functional gastrointestinal disorders, ranging from irritable bowel syndrome, to functional constipation and functional diarrhea. Irritable bowel syndrome is characterized by chronic abdominal pain with changes in bowel habit in the absence of morphological changes. Despite the high prevalence of irritable bowel syndrome in the global population, the mechanisms responsible for this condition are poorly understood. Although alterations in the gastrointestinal microbiota, low-grade inflammation and immune activation have been implicated in the pathophysiology of functional gastrointestinal disorders, there is inconsistency between studies and a lack of consensus on what the exact role of the microbiota is, and how changes to it relate to these conditions. The complex interplay between host factors, such as microbial dysbiosis, immune activation, impaired epithelial barrier function and motility, and environmental factors, including diet, will be considered in this narrative review of the pathophysiology of functional gastrointestinal disorders.

Lactobacilli and bifidobacteria derived from infant intestines may activate macrophages and lead to different IL-10 secretion

In this study, three strains of lactobacilli and bifidobacteria originally isolated from healthy infants, were tested for their abilities to activate RAW264.7 cells. Gene expression and cytokine production of interleukin-10 (IL-10) of RAW264.7 cells were evaluated. The activation of extracellular regulated protein kinases 1/2 (ERK1/2), p38, and nuclear factor-κB (NK-κB) were also assessed. These results suggest lactobacilli and bifidobacteria in infants may promote production of IL-10 in macrophages, conferring a protective effect in hosts suffering from inflammation. Dimerization of TLR2 and MyD88 and subsequent phosphorylation of the key downstream signaling molecules, such as MAPKs and NK-κB, may be one of the key underlying mechanisms of activation of macrophages by these microbes. Bifidobacteria and lactobacilli induced macrophages to secrete IL-10 in a different manner, which may relate to their abilities to activate key signaling pathways mediated by TLR2 and MyD88.

Ulcerative colitis: Gut microbiota, immunopathogenesis and application of natural products in animal models

Ulcerative colitis (UC) is an inflammatory bowel disease with increasing incidence in the world, especially in developing countries. Although knowledge of its pathogenesis has progressed over the last years, some details require clarification. Studies have highlighted the role of microbial dysbiosis and immune dysfunction as essential factors that may initiate the typical high-grade inflammatory outcome. In order to better understand the immunopathophysiological aspects of UC, experimental murine models are valuable tools. Some of the most commonly used chemicals to induce colitis are trinitrobenzene sulfonic acid, oxazolone and dextran sodium sulfate. These may also be used to investigate new ways of preventing or treating UC and therefore improving targeting in human studies. The use of functional foods or bioactive compounds from plants may constitute an innovative direction towards the future of alternative medicine. Considering the above, this review focused on updated information regarding the 1. gut microbiota and immunopathogenesis of UC; 2. the most utilized animal models of the disease and their relevance; and 3. experimental application of natural products, not yet tested in clinical trials.

The Relationship Between Gut Microbiota and Inflammatory Diseases: The Role of Macrophages

Gut microbiota, an integral part of the human body, comprise bacteria, fungi, archaea, and protozoa. There is consensus that the disruption of the gut microbiota (termed “gut dysbiosis”) is influenced by host genetics, diet, antibiotics, and inflammation, and it is closely linked to the pathogenesis of inflammatory diseases, such as obesity and inflammatory bowel disease (IBD). Macrophages are the key players in the maintenance of tissue homeostasis by eliminating invading pathogens and exhibit extreme plasticity of their phenotypes, such as M1 or M2, which have been demonstrated to exert pro- and anti-inflammatory functions. Microbiota-derived metabolites, short-chain fatty acids (SCFAs) and Gram-negative bacterial lipopolysaccharides (LPS), exert anti-inflammatory or pro-inflammatory effects by acting on macrophages. Understanding the role of macrophages in gut microbiota-inflammation interactions might provide us a novel method for preventing and treating inflammatory diseases. In this review, we summarize the recent research on the relationship between gut microbiota and inflammation and discuss the important role of macrophages in this context.

Dietary supplementation with Lactobacillus plantarum modified gut microbiota, bile acid profile and glucose homoeostasis in weaning piglets

Bile acids (BA) have emerged as signalling molecules regulating intestinal physiology. The importance of intestinal microbiota in production of secondary BA, for example, lithocholic acid (LCA) which impairs enterocyte proliferation and permeability, triggered us to determine the effects of oral probiotics on intestinal BA metabolism. Piglets were weaned at 28 d of age and allocated into control (CON, n 14) or probiotic (PRO, n 14) group fed 50 mg of Lactobacillus plantarum daily, and gut microbiota and BA profile were determined. To test the potential interaction of LCA with bacteria endotoxins in inducing damage of enterocytes, IPEC-J2 cells were treated with LCA, lipopolysaccharide (LPS) and LCA + LPS and expressions of genes related to inflammation, antioxidant capacity and nutrient transport were determined. Compared with the CON group, the PRO group showed lower total LCA level in the ileum and higher relative abundance of the Lactobacillus genus in faeces. In contrast, the relative abundances of Bacteroides, Clostridium_sensu_stricto_1, Parabacteroides and Ruminococcus_1, important bacteria genera in BA biotransformation, were all lower in the PRO than in the CON group. Moreover, PRO piglets had lower postprandial glucagon-like peptide-1 level, while higher glucose level than CON piglets. Co-administration of LPS and LCA led to down-regulated expression of glucose and peptide transporter genes in IPEC-J2 cells. Altogether, oral L. plantarum altered BA profile probably by modulating relative abundances of gut microbial genera that play key roles in BA metabolism and might consequently impact glucose homoeostasis. The detrimental effect of LCA on nutrient transport in enterocytes might be aggravated under LPS challenge.

Serine proteases at the cutting edge of IBD: Focus on gastrointestinal inflammation

Serine proteases have been long recognized to coordinate many physiological processes and play key roles in regulating the inflammatory response. Accordingly, their dysregulation has been regularly associated with several inflammatory disorders and suggested as a central mechanism in the pathophysiology of digestive inflammation. So far, studies addressing the proteolytic homeostasis in the gut have mainly focused on host serine proteases as candidates of interest, while largely ignoring the potential contribution of their bacterial counterparts. The human gut microbiota comprises a complex ecosystem that contributes to host health and disease. Yet, our understanding of microbially produced serine proteases and investigation of whether they are causally linked to IBD is still in its infancy. In this review, we highlight recent advances in the emerging roles of host and bacterial serine proteases in digestive inflammation. We also discuss the application of available tools in the gut to monitor disease-related serine proteases. An exhaustive representation and understanding of such functional potential would help in closing existing gaps in mechanistic knowledge.