Gut microbiota: an Indicator to Gastrointestinal Tract Diseases

Changes in the Gut Microbiota Composition during Implantation of Composite Scaffolds Based on Poly(3-hydroxybutyrate) and Alginate on the Large-Intestine Wall

The development of biopolymer scaffolds for intestine regeneration is one of the most actively developing areas in tissue engineering. However, intestinal regenerative processes after scaffold implantation depend on the activity of the intestinal microbial community that is in close symbiosis with intestinal epithelial cells. In this work, we study the impact of different scaffolds based on biocompatible poly(3-hydroxybutyrate) (PHB) and alginate (ALG) as well as PHB/ALG scaffolds seeded with probiotic bacteria on the composition of gut microbiota of Wistar rats. Implantation of PHB/ALG scaffolds on the large-intestine wall to close its injury showed that alpha diversity of the gut microbiota was not reduced in rats implanted with different PHB/ALG scaffolds except for the PHB/ALG scaffolds with the inclusion of Lactobacillus spheres (PHB/ALG-L). The composition of the gut microbiota of rats implanted with PHB/ALG scaffolds with probiotic bacteria or in simultaneous use of an antimicrobial agent (PHB/ALG-AB) differed significantly from other experimental groups. All rats with implanted scaffolds demonstrated shifts in the composition of the gut microbiota by individual operational taxonomic units. The PHB/ALG-AB construct led to increased abundance of butyrate-producing bacteria: Ileibacterium sp. dominated in rats with implanted PHB/ALG-L and Lactobacillus sp. and Bifidobacterium sp. dominated in the control group. In addition, the PHB/ALG scaffolds had a favourable effect on the growth of commensal bacteria. Thus, the effect of implantation of the PHB/ALG scaffold compared to other scaffolds on the composition of the gut microbiota was closest to the control variant, which may demonstrate the biocompatibility of this device with the microbiota.

Atractylenolide I inhibits antibiotic-induced dysbiosis of the intestinal microbiome

Background

Atractylenolide I (AT-I) is an active component that is isolated from Rhizoma Atractylodis macrocephalae and it exerts anti-apoptotic, anti-oxidant, and anti-coagulant properties, and has been widely applied in the treatment of cardiovascular and cerebrovascular diseases in China. This study aimed to investigate the effects and possible mechanism of AT-I on intestinal dysbacteriosis in a mouse model.

Methods

Mice dysbacteriosis models were established and treated with AT-I, and the intestinal microbiome of the mice were compared. Using antibiotics-induced bacterial elimination in an intestinal dysbacteriosis-associated xenograft model, the gut microbiota-mediated anti-tumor mechanism was investigated.

Results

The intestinal microbiome was changed in the dysbacteriosis mice compared to the control mice, and AT-I could affect the intestinal microbiome of the dysbacteriosis mice. Manipulation of gut bacteria in the intestines of the dysbacteriosis-associated xenograft model further confirmed that the inhibition of tumor progression by AT-I was mediated by the gut microbiota, and that the underlying mechanism involves down-regulation of TLR4/MyD88/NF-κB signaling. AT-I repressed the phosphorylation of p65-NF-κB as well as the downstream cytokines, IL-6 and IL-1β, in dysbacteriosis mice.

Conclusions

AT-I may inhibit dysbacteriosis by affecting the intestinal microbiome via the regulation of TLR4/MyD88/NF-κB signaling. The present study provides a basis for the application of AT-I as an alternative medication for treating gastrointestinal disorders.

Impact of the Gut Microbiota Balance on the Health-Disease Relationship: The Importance of Consuming Probiotics and Prebiotics

Gut microbiota is a group of microorganisms that are deposited throughout the entire gastrointestinal tract. Currently, thanks to genomic tools, studies of gut microbiota have pointed towards the understanding of the metabolism of important bacteria that are not cultivable and their relationship with human homeostasis. Alterations in the composition of gut microbiota could explain, at least in part, some epidemics, such as diabetes and obesity. Likewise, dysbiosis has been associated with gastrointestinal disorders, neurodegenerative diseases, and even cancer. That is why several studies have recently been focused on the direct relationship that these types of conditions have with the specific composition of gut microbiota, as in the case of the microbiota-intestine-brain axis. In the same way, the control of microbiota is related to the diet. Therefore, this review highlights the importance of gut microbiota, from its composition to its relationship with the human health-disease condition, as well as emphasizes the effect of probiotic and prebiotic consumption on the balance of its composition.

Crossroad between Obesity and Gastrointestinal Cancers: A Review of Molecular Mechanisms and Interventions

The burden of gastrointestinal (GI) cancer is increasing worldwide, and in the past decade, cancer had entered the list of chronic debilitating diseases whose risk is substantially increased by hypernutrition. Obesity may increase the risk of cancer by the imbalance of various mechanisms including insulin and insulin-like growth factor1 (IGF-I) signaling, systemic inflammation, immune dysregulation, tumor angiogenesis, adipokines secretion, and intestinal microbiota that usually act interdependently. An increased understanding of the mechanisms underlying obesity-GI cancer link can provide multiple opportunities for cancer prevention. This review discusses various mechanisms involved molecular mechanisms linking obesity with GI cancers including esophagus, stomach, colorectal and hepatocellular. Furthermore, an optional intervention such as diet restriction and exercise is described, which may be preventive or therapeutic in GI cancer.

Gut Microbiome and Osteoporosis

Gut microbiome refers to the microbes that live in human digestive tract and are symbiotic with the human body. They participate in the regulation of various physiological and pathological processes of the human body and are associated with various diseases. The pathological process of osteoporosis is affected by gut microbes. The molecular mechanisms of osteoporosis mainly include: 1) Intestinal barrier and nutrient absorption (involving SCFAs). 2) Immunoregulation (Th-17 and T-reg cells balance). 3) Regulation of intestinal-brain axis (involving 5-HT). Gut microbes can increase bone mass and improve osteoporosis by inhibiting osteoclast proliferation and differentiation, inducing apoptosis, reducing bone resorption, or promoting osteoblast proliferation and maturation. However, the therapeutic effect of gut microbes on osteoporosis remains to be further proven. At present, some of the findings on the impact of gut microbes on osteoporosis has been applied in clinical, including early diagnosis and intervention of osteoporosis and adjuvant therapy. In this article, we reviewed the molecular mechanisms underlying the regulatory effect of gut microbes on osteoporosis and the clinical practice of using gut microbes to improve bone health.

Gut microbiota in ulcerative colitis: insights on pathogenesis and treatment

Gut microbiota constitute the largest reservoir of the human microbiome and are an abundant and stable ecosystem-based on its diversity, complexity, redundancy, and host interactions This ecosystem is indispensable for human development and health. The integrity of the intestinal mucosal barrier depends on its interactions with gut microbiota. The commensal bacterial community is implicated in the pathogenesis of inflammatory bowel disease (IBD), including ulcerative colitis (UC). The dysbiosis of microbes is characterized by reduced biodiversity, abnormal composition of gut microbiota, altered spatial distribution, as well as interactions among microbiota, between different strains of microbiota, and with the host. The defects in microecology, with the related metabolic pathways and molecular mechanisms, play a critical role in the innate immunity of the intestinal mucosa in UC. Fecal microbiota transplantation (FMT) has been used to treat many diseases related to gut microbiota, with the most promising outcome reported in antibiotic-associated diarrhea, followed by IBD. This review evaluated the results of various reports of FMT in UC. The efficacy of FMT remains highly controversial, and needs to be regularized by integrated management, standardization of procedures, and individualization of treatment.

Correlation between changes in gut flora and serum inflammatory factors in children with noninfectious diarrhea

Purpose

To assess the association between changes in gut flora and serum inflammatory factors in children with noninfectious diarrhea.

Basic Procedure

Ninety-three children diagnosed with and treated for noninfectious diarrhea (diarrhea group) and 80 healthy children (healthy control group) were enrolled in this study. Fresh fecal samples were diluted, and after cultivating bacteria for 48 hours at 37°C, we compared the number of bacterial cells in gut flora per gram of feces and determined gut colonization resistance.

Findings

The abundance of Escherichia coli and Enterococcus in feces was significantly higher in the diarrhea group than in the healthy control group. Conversely, the abundance of Bifidobacterium and lactic acid bacteria was significantly lower in the diarrhea group than in the healthy control group. Serum interleukin (IL)-1, IL-6, IL-17, and tumor necrosis factor (TNF)-α levels in the diarrhea group were significantly higher than those in the healthy control group. Pearson’s correlation analysis revealed that serum IL-1, IL-6, IL-17, and TNF-α levels positively correlated with abundance of E. coli and Enterococcus and negatively correlated with abundance of Bifidobacterium and lactic acid bacteria.

Conclusions

Gut dysbacteriosis and overexpression of serum inflammatory factors occur in children with noninfectious diarrhea and are closely correlated.

Ameliorative effect of Atractylodes macrocephala essential oil combined with Panax ginseng total saponins on 5-fluorouracil induced diarrhea is associated with gut microbial modulation

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) holds that deficiency of spleen-Qi is the major pathogenesis of chemotherapy-induced diarrhea (CID). Herb pair of Atractylodes macrocephala Koidz. (AM) and Panax ginseng C. A. Mey. (PG) has good effects of supplementing Qi and strengthening spleen.

AIM OF THE STUDY

To investigate therapeutic effects and mechanism of Atractylodes macrocephala essential oil (AMO) and Panax ginseng total saponins (PGS) alone and in combination (AP) on 5-fluorouracil (5-FU) chemotherapy induced diarrhea in mice.

MATERIALS AND METHODS

The mice were administered with AMO, PGS and AP respectively for 11 days, and intraperitoneally injected with 5-FU for 6 days since the 3rd day of the experiment. During the experiment, the body weights and diarrhea scores of mice were recorded daily. Thymus and spleen indexes were calculated after sacrifice of the mice. Pathological changes in ileum and colonic tissues were examined by hematoxylin-eosin (HE) staining. And the content levels of intestinal inflammatory cytokines were measured by enzyme-linked immmunosorbent assays (ELISA). 16S rDNA Amplicon Sequencing was used to analyze and interpret the gut microbiota of fecal samples.

RESULTS

AP significantly inhibited body weights loss, diarrhea, reductions of thymus and spleen indexes, and pathological changes of ileums and colons induced by 5-FU. Neither AMO nor PGS alone significantly improved above-mentioned abnormalities. Besides, AP could significantly suppressed the 5-FU-mediated increases of the intestinal inflammatory cytokines (TNF-α, IFN-γ, IL-6, IL-1β and IL-17), while AMO or PGS only inhibited some of them after 5-FU chemotherapy. Gut microbiota analysis indicated that 5-FU induced overall structural changes of gut microbiota were reversed after AP treatment. Additionally, AP significantly modulated the abundances of different phyla similar to normal values, and restored the ratios of Firmicutes/Bacteroidetes (F/B). At genus level, AP treatment dramatically decreased potential pathogens like Bacteroides, Ruminococcus, Anaerotruncus and Desulfovibrio. AP also antagonized the abnormal effects of AMO and PGS alone on certain genera like Blautia, Parabacteroides and Lactobacillus. Neither AMO nor PGS alone inhibited changes of gut microbial structure caused by 5-FU.

CONCLUSIONS

AP, combination of AMO and PGS, not AMO or PGS alone, significantly ameliorated diarrhea, inhibited intestinal pathology, and modulated gut microbial structure in 5-FU induced mice. AP also antagonized abnormal effects of AMO or PGS on certain genera. The results illustrated that gut microbiota was involved in the combined effects of AP on 5-FU induced diarrhea.

A Preliminary Study of Microbiota Diversity in Saliva and Bronchoalveolar Lavage Fluid from Patients with Primary Bronchogenic Carcinoma

Background

The present study aimed to evaluate the difference in microbiota diversity in the oral cavity and fluid bronchoalveolar lavage (BALF) of patients with lung cancer.

Material/Methods

Buccal (saliva) and lower respiratory tract BALF samples were collected from 51 patients with primary bronchogenic carcinoma and 15 healthy controls, and bacterial genomic DNA was extracted. High-throughput 16S rDNA amplicon sequencing was performed, and microbial diversity, composition, and functions of microbiota were analyzed by bioinformatics methods.

Results

Patients with lung cancer have lower microbial diversity than healthy controls in both saliva and BALF samples. Significant segregation was observed between the different pathological types of lung cancer groups and the control group regardless of the sampling site. Treponema and Filifactor were identified as potential bacterial biomarkers in BALF samples, while Filifactor was ideal to distinguish healthy controls from lung cancer patients. Moreover, the predictive variation analysis of the KEGG (Kyoto Encyclopedia of Genes and Genomes) metabolic pathway showed that the metabolic differences in microbiota varied by sampling site.

Conclusions

Lung cancer patients carry a different and less diverse microorganism community than healthy controls. Certain bacterial taxa might be associated with lung cancer, but the exact species depends on the sampling site and the pathological type. This study provides basic data on the microbiota diversity in BALF and saliva samples from lung cancer patients. Further investigation with a larger sample size should help validate the enriched species in different pathological types of lung cancers.

Human Gut Microbiota and Gastrointestinal Cancer

Human gut microbiota play an essential role in both healthy and diseased states of humans. In the past decade, the interactions between microorganisms and tumors have attracted much attention in the efforts to understand various features of the complex microbial communities, as well as the possible mechanisms through which the microbiota are involved in cancer prevention, carcinogenesis, and anti-cancer therapy. A large number of studies have indicated that microbial dysbiosis contributes to cancer susceptibility via multiple pathways. Further studies have suggested that the microbiota and their associated metabolites are not only closely related to carcinogenesis by inducing inflammation and immune dysregulation, which lead to genetic instability, but also interfere with the pharmacodynamics of anticancer agents. In this article, we mainly reviewed the influence of gut microbiota on cancers in the gastrointestinal (GI) tract (including esophageal, gastric, colorectal, liver, and pancreatic cancers) and the regulation of microbiota by diet, prebiotics, probiotics, synbiotics, antibiotics, or the Traditional Chinese Medicine. We also proposed some new strategies in the prevention and treatment of GI cancers that could be explored in the future. We hope that this review could provide a comprehensive overview of the studies on the interactions between the gut microbiota and GI cancers, which are likely to yield translational opportunities to reduce cancer morbidity and mortality by improving prevention, diagnosis, and treatment.

Gut Microbiota: An Integral Moderator in Health and Disease

The gut microbiota, as the main member in gut microecology, is an essential mediator in health and disease. The gut microbiota interacts with various organs and systems in the body, including brain, lung, liver, bone, cardiovascular system, and others. Microbiota-derived metabolites such as the short chain fatty acid (SCFA) butyrate are primary signals, which link the gut microbiota and physiology. Recently, the gut microbiota has been identified as the origin of a number of diseases by influencing the related cell signaling pathways such as WNT/beta-catenin pathway in colorectal cancer and T cell receptor signaling in the central nervous system. Moreover, several microRNAs participate in signaling networks through the intervention of the gut microbiota. The interaction between the gut microbiota and miRNAs plays a crucial role in vascular dysfunction and hepatocellular carcinoma (HCC). In this review, we will report and discuss recent findings about the crosstalk between the gut microbiota and physical organs and how the gut microbiota and miRNAs regulate each other while influencing the host via genes, proteins, or metabolites.

Human Gut Microbiota and Gastrointestinal Cancer

Human gut microbiota play an essential role in both healthy and diseased states of humans. In the past decade, the interactions between microorganisms and tumors have attracted much attention in the efforts to understand various features of the complex microbial communities, as well as the possible mechanisms through which the microbiota are involved in cancer prevention, carcinogenesis, and anti-cancer therapy. A large number of studies have indicated that microbial dysbiosis contributes to cancer susceptibility via multiple pathways. Further studies have suggested that the microbiota and their associated metabolites are not only closely related to carcinogenesis by inducing inflammation and immune dysregulation, which lead to genetic instability, but also interfere with the pharmacodynamics of anticancer agents. In this article, we mainly reviewed the influence of gut microbiota on cancers in the gastrointestinal (GI) tract (including esophageal, gastric, colorectal, liver, and pancreatic cancers) and the regulation of microbiota by diet, prebiotics, probiotics, synbiotics, antibiotics, or the Traditional Chinese Medicine. We also proposed some new strategies in the prevention and treatment of GI cancers that could be explored in the future. We hope that this review could provide a comprehensive overview of the studies on the interactions between the gut microbiota and GI cancers, which are likely to yield translational opportunities to reduce cancer morbidity and mortality by improving prevention, diagnosis, and treatment.

The Human Gastric Microbiome Is Predicated upon Infection with Helicobacter pylori

The human gastric lumen is one of the most hostile environments of the human body suspected to be sterile until the discovery of Helicobacter pylori (H.p.). State of the art next generation sequencing technologies multiply the knowledge on H.p. functional genomics as well as on the colonization of supposed sterile human environments like the gastric habitat. Here we studied in a prospective, multicenter, clinical trial the 16S rRNA gene amplicon based bacterial microbiome in a total of 30 homogenized and frozen gastric biopsy samples from eight geographic locations. The evaluation of the samples for H.p. infection status was done by histopathology and a specific PCR assay. CagA status was determined by a CagA-specific PCR assay. Patients were grouped accordingly as H.p.-negative, H.p.-positive but CagA-negative and H.p.-positive and CagA-positive (n = 10, respectively). Here we show that H.p. infection of the gastric habitat dominates the gastric microbiota in most patients and is associated with a significant decrease of the microbial alpha diversity from H.p. negative to H.p. positive with CagA as a considerable factor. The genera Actinomyces, Granulicatella, Veillonella, Fusobacterium, Neisseria, Helicobacter, Streptococcus, and Prevotella are significantly different between the H.p.-positive and H.p.-negative sample groups. Differences in microbiota found between CagA-positive and CagA-negative patients were not statistically significant and need to be re-evaluated in larger sample cohorts. In conclusion, H.p. infection dominates the gastric microbiome in a multicentre cohort of patients with varying diagnoses.

Alteration of Gut Microbiota and Inflammatory Cytokine/Chemokine Profiles in 5-Fluorouracil Induced Intestinal Mucositis

Disturbed homeostasis of gut microbiota has been suggested to be closely associated with 5-fluorouracil (5-Fu) induced mucositis. However, current knowledge of the overall profiles of 5-Fu-disturbed gut microbiota is limited, and so far there is no direct convincing evidence proving the causality between 5-Fu-disturbed microbiota and colonic mucositis. In mice, in agreement with previous reports, 5-Fu resulted in severe colonic mucositis indicated by weight loss, diarrhea, bloody stool, shortened colon, and infiltration of inflammatory cells. It significantly changed the profiles of inflammatory cytokines/chemokines in serum and colon. Adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and VE-Cadherin were increased. While tight junction protein occludin was reduced, however, zonula occludens-1 (ZO-1) and junctional adhesion molecule-A (JAM-A) were increased in colonic tissues of 5-Fu treated mice. Meanwhile, inflammation related signaling pathways including NF-κB and mitogen activated protein kinase (MAPKs) in the colon were activated. Further study disclosed that 5-Fu diminished bacterial community richness and diversity, leading to the relative lower abundance of Firmicutes and decreased Firmicutes/Bacteroidetes (F/B) ratio in feces and cecum contents. 5-Fu also reduced the proportion of Proteobacteria, Tenericutes, Cyanobacteria, and Candidate division TM7, but increased that of Verrucomicrobia and Actinobacteria in feces and/or cecum contents. The fecal transplant from healthy mice prevented body weight loss and colon shortening of 5-Fu treated mice. In addition, the fecal transplant from 5-Fu treated mice reduced body weight and colon length of vancomycin-pretreated mice. Taken together, our study demonstrated that gut microbiota was actively involved in the pathological process of 5-Fu induced intestinal mucositis, suggesting potential attenuation of 5-Fu induced intestinal mucositis by manipulating gut microbiota homeostasis.